JP2000347433A - Electrophotographic photoreceptor and electrophotographic apparatus using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrophotographic photoreceptor capable of easily judging the success or failure of a product in manufacturing process and forming images high in quality and definition and to provide an electrophotographic apparatus made by using this. SOLUTION: The electrophotographic photoreceptor formed by successively laminating a undercoat layer made of a white pigment and a binder and a photosensitive layer on a conductive substrate and a ratio of the relative mirror reflectance of the above laminated layers to the mirror reflectance of the substrate of <=16% in the case of 600-900 nm wavelength. Preferably, in the case of using a 780 nm light incident at an angle of 5 deg..

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an electrophotographic photosensitive member and an electrophotographic apparatus, and more particularly to an electrophotographic photosensitive member and an electrophotographic apparatus suitable for a digital system.

[0002]

2. Description of the Related Art In order to manufacture a laminated electrophotographic photosensitive member, a photosensitive layer (charge generation layer) and, if necessary, a charge transfer layer are sequentially laminated on a conductive substrate. An undercoat layer is often used to improve the adhesion between the conductive substrate and the photosensitive layer and to block the injection of electric charge from the conductive substrate. In a general electrophotographic photosensitive member, the undercoat layer is used. Layer / photosensitive layer /
Since the charge transfer layers are sequentially stacked, the manufacturing process is complicated. As the undercoat layer, a resin or a resin in which a white pigment is dispersed is used. Recently, in an electrophotographic system using a laser beam of a single wavelength, moire is likely to occur due to interference. Therefore, a technique for preventing moire by roughening the surface of a conductive substrate (Japanese Patent Laid-Open No. 6-2)
No. 08237). However, the method described in this publication requires a process for roughening the surface of the conductive substrate, and the surface condition of the conductive substrate is liable to change due to wear, deterioration, etc. of tools and equipment, and the conductive substrate Handling is also troublesome.

Japanese Patent Application Laid-Open No. 60-186850 discloses a technique for preventing the moire caused by interference fringes such as laser light by setting the average surface roughness of an undercoating layer made of a resin to a half wavelength or more of a light source for image exposure. Is disclosed. However, according to the method described in this publication, not only is it difficult to make the surface of the undercoat layer made of a resin uniformly and reproducibly and uniformly to a desired roughness, but also a process for roughening the surface of the undercoat layer is required. Required.

On the other hand, an undercoat layer in which a white pigment is dispersed in a resin can be formed by coating without adding a special process, and light scattering by white pigment particles occurs. Optimal.

The present inventors applied an undercoat layer in which a white pigment was dispersed in a resin as disclosed in Japanese Patent No. 2506694 and JP-A-2-67565 on a conductive substrate. An electrophotographic photoreceptor comprising a photosensitive layer and a charge transfer layer has been studied diligently. However, when the electrophotographic photosensitive member is incorporated into an electrophotographic apparatus and an image forming test is performed while mass-producing the electrophotographic photosensitive member, a satisfactory image may not be obtained in some cases. In particular, image blurring due to poor charging, and the phenomenon of insect biting occurring in the transfer process may frequently occur, and this is particularly likely to occur when a multicolor image is formed as compared with a single color image.
A comparison between an electrophotographic photoreceptor having inferior image quality and a normal electrophotographic photoreceptor showed no clear difference between the two by inspection at a static level and a visual level. After all,
The only way to determine the acceptability of the photoreceptor is to perform an image forming test, which takes a great deal of time and effort.

[0006]

SUMMARY OF THE INVENTION The present invention relates to an electrophotographic photoreceptor capable of easily determining whether or not a product is acceptable in a manufacturing process and forming a high-quality, high-definition image, and an electrophotographic photoreceptor using the same. It is an object to provide a photographic device.

[0007]

According to the present invention, in order to solve the above-mentioned problems, an electrophotographic photosensitive member comprising a conductive substrate and an undercoating layer comprising a white pigment and a binder and a photosensitive layer sequentially laminated thereon. An electrophotographic apparatus, wherein a relative mirror reflectance of a laminate in which an undercoat layer is laminated on a conductive substrate is 16% or less with respect to a mirror reflectance of the conductive substrate with light having a wavelength of 600 to 900 nm. An electrophotographic photosensitive member is provided. Further, according to the present invention, in an electrophotographic photoreceptor obtained by sequentially laminating an undercoat layer made of a white pigment and a binder and a photosensitive layer on a conductive substrate, a wavelength of 780 nm
Wavelength of the laminate obtained by laminating the undercoat layer on the conductive substrate with respect to the specular reflectance of the conductive substrate at an incident angle of light of 5 °
The relative specular reflectance at an incident angle of light of 5 nm at 80 nm is 16
% Or less is provided. Further, according to the present invention, there is provided the electrophotographic photoreceptor having the above structure, wherein 60% by weight or more of the white pigment is titanium oxide. Further, according to the present invention, there is provided an electrophotographic apparatus characterized by using the electrophotographic photoreceptor having the above configuration. Further, according to the present invention, there is provided an electrophotographic apparatus, wherein the charging means is of a contact charging type in the above configuration. Further, according to the present invention, there is provided an electrophotographic apparatus characterized in that in the above configuration, the charging means is of a contact type. Further, according to the present invention, there is provided an electrophotographic apparatus which is a multicolor image forming electrophotographic apparatus having the above-mentioned configuration.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The inventors of the present invention carefully observed whether or not an electrophotographic photosensitive member was acceptable or not before conducting an image forming test from the manufacturing process of the electrophotographic photosensitive member. Although the electrophotographic photoreceptor having poor inferiority is small immediately after preparing the coating solution for the undercoat layer, it tends to be generated in the coating solution for the undercoat layer after a certain period of time. It has been found that there is almost no correlation between the storage period of the liquid and the coating solution of the charge transfer layer. Considering this result,
The coating liquid for the undercoat layer is prepared by dispersing a white pigment in a solution in which a resin is dissolved in a solvent, and while using the coating liquid while stirring, precipitation of the white pigment occurs with time, It is considered that the state of the coating liquid may slightly change, for example, the particle size of the white pigment changes due to the stirring. On the other hand, the coating liquid for the photosensitive layer and the charge transfer layer is difficult to settle because the pigment is lightweight and has a small particle size, or simply dissolves a resin or the like in a solvent, and the particles themselves do not exist. If the solvent is prevented from evaporating, avoiding contact with oxidizing gas, and carefully used and stored in a dark place, the dispersion state of the coating liquid is unlikely to change.

[0009] However, although it can be inferred that the effect of the undercoat layer on the acceptance or rejection of the electrophotographic photoreceptor is large, even if the viscosity of the coating solution of the undercoat layer is analyzed, no clear guideline can be obtained, and the image quality cannot be improved. With regard to the surface condition of the undercoat layer according to the above, almost no pass / fail difference could be determined by inspection and visual inspection using a conventional contact-type surface roughness meter. The present inventors conducted further intensive studies to clarify the difference between the pass and fail results. As a result, the undercoat layer in which the pigment was dispersed in the resin was applied to the conductive substrate, and the undercoat layer was formed by drying. It has been found that the electrophotographic photoreceptor produced when the condition of the surface of the drawing layer satisfies certain conditions has no problem in image quality, and the present invention has been completed.

That is, the electrophotographic photoreceptor of the present invention is an electrophotographic photoreceptor obtained by sequentially laminating an undercoating layer containing a white pigment and a binder on a conductive substrate and a photosensitive layer. The relative specular reflectance of a laminate obtained by laminating an undercoat layer on a conductive substrate is 16% or less of the specular reflectance of the conductive substrate. The relative specular reflectance is more preferably 13%
Hereinafter, it is more preferably 0.1 to 12%. If the relative specular reflectance is larger than 16%, image blur and worming tend to occur. The specular reflectance in the present specification refers to, among the light reflected by the surface of the base 1, the incident light as shown in FIG.
The intensity of specularly reflected light is measured, and the ratio of the intensity of specularly reflected light to the intensity of incident light is referred to. Therefore, the fact that the specular reflectance is small indicates that, for example, the surface of the base 1 is minutely rough and scatters incident light, or that the base 1 or a substance on the surface of the base 1 absorbs the incident light. I have. The present invention is an invention found by paying attention to the specular reflectance of the undercoat layer. However, it is difficult to directly measure the specular reflectivity of only the undercoat layer. Therefore, in the present invention, the specular reflectivity of the conductive substrate is used for reference, and the specular reflectivity of the conductive substrate with respect to the specular reflectivity of the conductive substrate is used. It has been found that the relative specular reflectance, which is the ratio of the specular reflectance of a laminate having an undercoat layer, is a simple measurement, has good reproducibility, and is extremely useful in determining the acceptability of a photoreceptor. In the present invention, the wavelength of incident light in the relative specular reflectance measurement is from 600 to 900 nm, preferably from 700 to 850 nm, and most preferably 780 nm. The relative specular reflectance changes depending on the wavelength of the incident light. When the wavelength is short, the incident light is more easily scattered in the undercoat layer than when the wavelength is long, so that the relative specular reflectance becomes small. Conversely, if the wavelength is long, the relative reflectance of the undercoat layer increases. In the present invention, the use of 600 to 900 nm as the wavelength of the incident light can accurately show the fine state of the good undercoat layer,
When the wavelength of the incident light is out of the above range, even if the relative specular reflectance is 16% or less, it is not always possible to say that the electrophotographic photosensitive member has good image quality. In principle, the incident angle θ of the incident light in the measurement of the relative specular reflectance in the present invention may be any angle, but in consideration of the measurement accuracy and the size of the measuring device, 1 ° to 30 ° Preferably it is 2 ° to 10 °, most preferably 5 °. If the angle of incidence is less than 1 °, the optical path length for accurate measurement must be sufficiently long, which increases the size of the measuring instrument. Bad and not desirable.

The undercoat layer of the electrophotographic photoreceptor of the present invention has a thickness of 0.5 to 15 μm, preferably 1 to 12 μm, and contains a white pigment and a resin as main components. Examples of the white pigment include metal oxides such as titanium oxide, aluminum oxide, zirconium oxide, and zinc oxide. Among them, titanium oxide, which is excellent in preventing charge injection from a conductive substrate, is most preferable. When the proportion of titanium oxide in the white pigment in the undercoat layer is 60% by weight or more, preferably 70% by weight, more preferably 80% by weight or more, an electrophotographic photoreceptor having particularly high image quality can be produced. it can. If the proportion of titanium oxide in the undercoat layer is 60% by weight or less, the characteristics of the undercoat layer may fluctuate due to environmental fluctuations, and the effect of blocking charge injection from the conductive substrate may become unstable.

The resin used for the undercoat layer of the electrophotographic photoreceptor of the present invention includes polyamide, polyvinyl alcohol,
Examples thereof include thermoplastic resins such as casein and methylcellulose, and thermosetting resins such as acryl, phenol, melamine, alkyd, unsaturated polyester, and epoxy.

The conductive substrate used in the electrophotographic photoreceptor of the present invention may be a sheet or drum made of a metal such as copper, aluminum, gold, silver, platinum, iron, palladium, nickel or an alloy containing these metals as a main component. Examples thereof include a sheet molded into a shape and a sheet in which the above-described metal, tin oxide, indium oxide, or the like is adhered to a plastic film or the like by vacuum evaporation, electroless plating, or the like. The surface of the conductive substrate may be roughened by a mechanical, chemical or electrochemical method to improve the adhesion to the undercoat layer and prevent moiré. In the electrophotographic photoreceptor of the present invention, when the conductive substrate has a curved surface for measuring the relative specular reflectance such as a small-diameter cylindrical drum, the diameter of the incident light used for the measurement is made sufficiently small and the relative specular reflectance is reduced. It is preferable that the measurement is performed by regarding the rate measurement surface as a flat surface. In addition, simply, the undercoat layer is laminated on a flat plate or a large-diameter drum having substantially the same surface condition and the same material and the same thickness as the conductive base under the same coating conditions as the actual electrophotographic photoreceptor, Pass / fail can also be determined by measuring the relative reflectance.

In providing the photosensitive layer on the undercoat layer thus formed, the photosensitive layer can be provided by a known method, and a known organic and inorganic material can be used as a material constituting the photosensitive layer. Can be used. Further, the structure of the photosensitive layer is not particularly limited, and even if the photosensitive layer is a single-layer type photosensitive layer containing a charge generating material and a charge transporting material, the photosensitive layer contains the charge generating layer containing the charge generating material and the charge transporting material. It may be a function-separated type photosensitive layer in which the formed charge transport layer is laminated, and a protective layer or the like may be provided on the surface of the photosensitive layer.

The charge generating material used in the electrophotographic photoreceptor of the present invention includes, for example, monoazo pigments, bisazo pigments, trisazo pigments, tetrakisazo pigments, triarylmethane dyes, thiazine dyes, oxazine dyes, Xanthene dyes, cyanine dyes, styryl dyes, pyrylium dyes, quinacridone pigments, indigo pigments, perylene pigments, polycyclic quinone pigments, bisbenzimidazole pigments, indathrone pigments, squarylium pigments, phthalocyanines Organic pigments and dyes such as pigments, and inorganic materials such as selenium, selenium-arsenic, selenium-tellurium, cadmium sulfide, zinc oxide, titanium oxide, and amorphous silicon can be used.

Examples of the charge transport material used in the electrophotographic photoreceptor of the present invention include anthracene derivatives, pyrene derivatives, carbazole derivatives, tetrazole derivatives, metallocene derivatives, phenothiazine derivatives, pyrazoline compounds, hydrazone compounds, styryl compounds, and styrylhydrazone compounds. , Enamine compound, butadiene compound, distyryl compound, oxazole compound, oxadiazole compound, thiazole compound, imidazole compound, triphenylamine derivative, phenylenediamine derivative,
An aminostilbene derivative, a triphenylmethane derivative and the like can be used.

The binder resin used for forming the above-mentioned photosensitive layer is electrically insulating, and is a thermoplastic resin, a thermosetting resin, a photocurable resin and a photoconductive resin known per se. And the like, and suitable binder resins include, for example, polyvinyl chloride, polyvinylidene chloride,
Vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinyl acetate-maleic anhydride copolymer, ethylene-vinyl acetate copolymer, polyvinyl butyral, polyvinyl acetal, polyester, phenoxy resin, (meth) acrylic resin, polystyrene, polycarbonate Thermosetting resins such as thermoplastic resins such as polyarylate, polysulfone, polyethersulfone, and ABS resin, phenolic resins, epoxy resins, urethane resins, melamine resins, isocyanate resins, alkyd resins, silicone resins, and thermosetting acrylic resins And photoconductive resins such as polyvinyl carbazole, polyvinyl anthracene, and polyvinyl pyrene, but are not particularly limited thereto.

The electrophotographic photosensitive member of the present invention is excellent in image quality when used in an electrophotographic apparatus and is very preferable. The electrophotographic apparatus using the electrophotographic photosensitive member of the present invention is at least charged,
It has various sections for performing image exposure, development, transfer, and cleaning steps. As a charging means in the charging step, a corona charging method, a charging roller, a charging belt, a charging blade,
Although any of the contact charging methods using a charging brush or the like is satisfactory, the effect of the present invention is high with a contact charging method using less oxidizing gas such as ozone. That is, a wavelength of 600 to
For the specular reflectance of the conductive substrate at 900 nm light,
When the relative specular reflectance of the laminate in which the undercoat layer is laminated on the conductive substrate is greater than 16%, poor charging is likely to occur, whereas when the relative reflectance is 16% or less, uniform charging becomes possible.
It is possible to form a stable and high quality image. Transfer means include a non-contact transfer method using corona discharge, a transfer roller,
The contact transfer method using a transfer belt, a transfer blade, or the like is good in any case, but the effect of the present invention is particularly high in the case of the contact transfer method.

In the electrophotographic apparatus of the present invention, the reason why the effect of the present invention is enhanced when the contact method is selected for both the charging means and the transfer means is not clear, but the wavelength is 600 to 9 nm.
The relative roughness of the undercoat layer of the laminate obtained by laminating the undercoat layer on the conductive substrate with respect to the specular reflectance of the conductive substrate at 00 nm light is 16%, and the surface roughness of the undercoat layer surface is 16%.
Even if the charge transfer layers are sequentially laminated, the state of the surface of the photoconductor is maintained to some extent. Therefore, the undercoat layer is laminated on the conductive substrate with respect to the specular reflectance of the conductive substrate at a wavelength of 600 to 900 nm. It is considered that the minute difference in the charging state and the minute difference in the electrostatic latent image corresponding to the relative mirror reflectance of the laminate of 16% or less enhance the effect in the contact charging system and / or the contact transfer system.

The electrophotographic apparatus of the present invention can form a high-quality image particularly when digital processing is performed rather than analog processing. Further, the electrophotographic apparatus of the present invention is capable of forming a good image even in single-color and multi-color image formation,
Particularly, in the case of forming a multicolor image, the effect of the present invention is enhanced.

[0021]

The present invention will be described in more detail with reference to the following examples.

Examples 1 to 4, Comparative Example 1 15 parts by weight of an acrylic resin (Acrydic A-460-60 (manufactured by Dainippon Ink and Chemicals)) and a melamine resin (Super Beckamine L-121-60 (Dainippon Ink) Dissolve 10 parts by weight in 80 parts by weight of methyl ethyl ketone, add 70 parts by weight of titanium oxide powder (TM-1 (manufactured by Fuji Titanium Industry)), disperse the mixture in a ball mill for 24 hours, and apply the undercoat layer. A liquid was made. This is 80m in diameter
m, applied to a nickel seamless belt having a length of 360 mm, and dried at 140 ° C. for 20 minutes to form an undercoat layer having a thickness of 2 μm. Next, 15 parts by weight of a butyral resin (Eslec BLS (manufactured by Sekisui Chemical)) was dissolved in 150 parts by weight of cyclohexanone, and 10 parts by weight of a trisazo pigment having the following structural formula was added thereto and dispersed by a ball mill for 48 hours.

Embedded image Further, 210 parts by weight of cyclohexanone was added and dispersed for 3 hours. This was diluted with cyclohexanone while stirring so that the solid content became 1.5% by weight. The photosensitive layer coating solution thus obtained is applied on the undercoat layer and dried,
A photosensitive layer having a thickness of about 0.2 μm was formed. 6 parts by weight of a charge transport material having the following structural formula,

Embedded image 10 parts by weight of polycarbonate resin (Panlite K-1300 (manufactured by Teijin Chemicals)), silicone oil (KF-50)
(Shin-Etsu Chemical Co., Ltd.) 0.002 parts by weight was dissolved in 90 parts by weight of methylene chloride. The thus obtained charge transfer layer coating solution was applied on the photosensitive layer and dried to a thickness of 23 μm.
m was formed to prepare an electrophotographic photoreceptor.

The electrophotographic photosensitive member was mass-produced by the above method. With the mass production, each coating liquid decreased, but mass production was performed while adding each newly prepared coating liquid to the decrease. Each coating liquid was managed while periodically inspecting the viscosity and the solid content concentration. On the 2nd, 20th, 50th, 100th, and 134th days after the start of mass production, the electrophotographic photosensitive member and the nickel seamless belt, on which only the undercoat layer was formed, were extracted, and electrophotography was performed. The image of the photoreceptor was evaluated. The image forming test of the electrophotographic photosensitive member was performed using a digital color electrophotographic apparatus using a charging roller and a transfer belt. In the case where only an undercoat layer is formed on a nickel seamless belt, a specular reflectance measuring device (for an incident angle of 5 °) P /
Using a spectrophotometer UV-1200 (manufactured by Shimadzu Corporation) equipped with N206-14046 (manufactured by Shimadzu Corporation), the relative specular reflectance with respect to the nickel seamless belt at a wavelength of 780 nm of incident light and 5 ° of incident light was measured. Table 1 shows the measurement results.

[Table 1]

Example 5 The procedure of Example 1 was repeated except that the undercoat layer coating solution, the photosensitive layer coating solution, and the charge transfer layer coating solution were each adjusted and then the coating was started within 20 hours. An electrophotographic photoreceptor was produced in the same manner.

Example 6 The procedure of Example 5 was repeated except that titanium oxide powder 7
Same as Example 5 except that 35 parts by weight of titanium oxide powder and 35 parts by weight of aluminum oxide powder (A-32 (manufactured by Nippon Light Metal)) were used in place of 0 part by weight to prepare an undercoat layer coating solution. Thus, an electrophotographic photosensitive member was manufactured.

Example 7 In Example 5, the titanium oxide powder 7 of the undercoat layer coating liquid was used.
In the same manner as in Example 5 except that 60 parts by weight of titanium oxide powder and 10 parts by weight of aluminum oxide powder (A-32 (manufactured by Nippon Light Metal Co., Ltd.)) were used instead of 0 part by weight to prepare an undercoat layer coating solution. Thus, an electrophotographic photosensitive member was manufactured.

Comparative Example 2 An electrophotographic photosensitive member was prepared in the same manner as in Example 5, except that the dispersion time of the undercoat layer coating solution in the ball mill was set to 100 hours and the undercoat layer coating solution was adjusted. Produced.

The electrophotographic photosensitive members produced in Examples 5 to 7 and Comparative Example 2 were incorporated into the digital electrophotographic apparatus used in Example 1, and an image forming test was performed in an environment of 30 ° C. and 90% RH. Table 2 shows the measurement results.

[Table 2]

Comparative Example 3 In the image forming test of Example 1, an image forming test was carried out using an electrophotographic apparatus experimental machine using the same charging roller and transfer belt except that it was an analog single color. Smear of the background was slightly observed from the beginning of the test, and after 10,000 images were formed, the stain became severe.

Example 8 The procedure of Example 3 was repeated, except that a non-contact charger using corona discharge was used in place of the charging roller of the electrophotographic apparatus experimental machine. A formation test was performed. Two of the three electrophotographic photoreceptors were good after forming 30,000 sheets of image, but one of
Slight image blurring occurred after 10,000 sheets of images were formed.

[0031]

According to the first aspect of the present invention, a wavelength of 600 to
For the specular reflectance of the conductive substrate at 900 nm light,
Provided is an electrophotographic photoreceptor, particularly a digital electrophotographic photoreceptor capable of forming excellent image quality by setting the relative specular reflectance of a laminate in which an undercoat layer is laminated on a conductive substrate to 16% or less. can do. According to the invention of claim 2, as a measurement of a relative specular reflectance of a laminate obtained by laminating an undercoat layer on the conductive substrate with respect to a specular reflectance of the conductive substrate, the incident angle of light at 780 nm is 5 °. By measuring the relative specular reflectance at an incident angle of light of 5 ° at 780 nm of a laminate obtained by laminating an undercoat layer on a conductive substrate, with respect to the specular reflectance of the conductive substrate, Provided is an electrophotographic photoreceptor, particularly a digital electrophotographic photoreceptor capable of forming excellent image quality by enabling measurement with good reproducibility and setting the relative specular reflectance to 16% or less by the measuring method. be able to. According to the third aspect of the present invention, there is provided an electrophotographic photoreceptor capable of forming excellent image quality with little change in environment by using 60% by weight or more of white pigment as titanium oxide. Can be. According to the invention of claim 4, by using the electrophotographic photosensitive member according to any one of claims 1 to 3, it is possible to provide an electrophotographic apparatus capable of forming excellent image quality, particularly a digital electrophotographic apparatus. . According to the invention of claim 5, the charging means is a contact charging system,
An electrophotographic apparatus capable of forming excellent image quality with less generation of ozone can be provided. According to the sixth aspect of the present invention, it is possible to provide an electrophotographic apparatus capable of forming excellent image quality by using a transfer unit as a contact type. According to a seventh aspect, a color electrophotographic apparatus, in particular, a digital color electrophotographic apparatus capable of forming a high-quality, high-definition multicolor image can be provided by using the electrophotographic photosensitive member according to any one of the first to third aspects. .

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of specular reflectance.

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Michio Kimura, 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Company, Ltd. (72) Shinji Nori, 1-3-6 Nakamagome, Ota-ku, Tokyo F-term in Ricoh Co., Ltd. (reference) 2H003 AA18 BB11 CC04 2H030 BB71 2H068 AA44 AA48 AA49 CA29 FA17 FB07 FB11 FC01

Claims (7)

[Claims] 1. An electrophotographic photoreceptor comprising an undercoat layer composed of a white pigment and a binder and a photosensitive layer sequentially laminated on a conductive substrate, the electrophotographic photosensitive member having a wavelength of 600 to 900 nm with respect to the mirror reflectance of the conductive substrate. An electrophotographic photoreceptor for an electrophotographic apparatus, wherein a laminate in which an undercoat layer is laminated on a conductive substrate has a relative specular reflectance of 16% or less. 2. An electrophotographic photosensitive member in which a subbing layer made of a white pigment and a binder and a photosensitive layer are sequentially laminated on a conductive substrate, the electrophotographic photosensitive member having a wavelength of 780 nm and an incident angle of light of 5 °. An electrophotographic photoreceptor, wherein a relative specular reflectance at an incident angle of light of 5 ° at a wavelength of 780 nm of a laminate in which an undercoat layer is laminated on a conductive substrate is 16% or less with respect to a specular reflectance. . 3. The electrophotographic photoreceptor according to claim 1, wherein 60% by weight or more of the white pigment is titanium oxide. 4. An electrophotographic apparatus using the electrophotographic photoreceptor according to claim 1. 5. An electrophotographic apparatus according to claim 4, wherein said charging means is of a contact charging type. 6. The electrophotographic apparatus according to claim 4, wherein the charging means is of a contact type. 7. The electrophotographic apparatus according to claim 4, which is a multicolor image forming electrophotographic apparatus.