JPS6338942A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To obtain a sensitive body having high sensitivity and suitable for analogue copying and digital copying by forming an electric charge generating layer consisting of a first electric charge generating layer having sensitivity at >=700nm and a second electric charge generating layer having sensitivity at 400-700nm. CONSTITUTION:An intermediate layer 2 having 10<5>-10<14>OMEGAcm volume resistivity and 0.1-10mum thickness is formed on an electrically conductive support 1. A first electric charge generating layer 3 having sensitivity to light of >=700nm wavelength and a second electric charge generating layer 4 having sensitivity to light of 400-700nm wavelength are successively formed on the layer 2, and an electric charge transferring layer 5 is formed on the layer 4 to obtain a multifunctional electrophotographic sensitive body. When the sensitive body is used, analogue copying with tungsten lamp or the like as a light source and digital copying with semiconductor laser or the like as a light source can be selectively carried out.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to an electrophotographic photoreceptor, and more particularly to a laminated electrophotographic photoreceptor suitable for forming analog images and digital images.

[Prior art]

In recent years, the performance of electrophotographic copying machines has improved dramatically, and it has become possible to stably obtain high-quality images.

By the way, as a means of forming an electrostatic charge image on a photoreceptor,
Generally, after uniformly charging a photoreceptor, (i) background exposure is performed using a light source such as tungsten, halogen, or fluorescent light to form an electrostatic charge image (analog image forming method); ) A method (digital image forming method) is known in which an electrostatic charge image is formed by performing dot image exposure using a light source such as a semiconductor laser.

The former (i) is particularly advantageous for obtaining enhanced continuous tone or halftone images, and the latter (jf) is particularly advantageous for obtaining negative images or positive line drawings by reversal development.

However, although it is easy to install two types of light sources, such as tungsten and semiconductor lasers, in a copying machine, it is possible to have good sensitivity to these light sources, and at the same time, it is possible to obtain high-quality copies by image forming method using either light source. The reality is that an electrophotographic photoreceptor that can provide this has not yet been developed.

〔the purpose〕

A first object of the present invention is to provide a multifunctional electrophotographic photoreceptor that can selectively perform analog copying using the aforementioned tungsten or the like as a light source, or digital copying using a semiconductor laser or the like as a light source. The second object of the present invention is 400n@
The present invention generally provides an electrophotographic photoreceptor having good panchromatic sensitivity over the range of 400 to 800 nm.

〔composition〕

The laminated electrophotographic photoreceptor of the present invention has a volume resistivity of 10" to 1014 Ωl and a film thickness of 0.1 to 10" on a conductive support.
A first charge generation layer sensitive to light with a wavelength of 700nm or more is provided on the intermediate layer, and a second charge generation layer sensitive to light in the wavelength range of 400 to 700n+11 is further provided on this intermediate layer. A charge generation layer and a charge transfer layer are sequentially provided.

FIG. 1 shows a cross section of an example of a photoreceptor according to the present invention.

Examples of the conductive support 1 include metals such as aluminum, nickel, stainless steel, and copper, as well as substrates such as paper and plastic films subjected to conductive treatment, or substrates provided with a conductive layer on the surface of the substrate.

In the present invention, as described later, since the first charge generation layer 3 is sensitive to wavelengths of 700r++s or more, the optical energy bandgap is narrow, and therefore the conductive support 1 and the first charge generation layer 3 It is effective to provide an intermediate layer 2 between the two, and is particularly effective for improving fatigue resistance.

The volume resistivity of the intermediate layer 2 is 10S to 10<14>[Omega]l, preferably 10@ to 10<14>[Omega]l. If it is less than 10 sΩ1, charge will be injected from the conductive support 1 during charging, resulting in deterioration of the charging characteristics, while if it is more than 10 14 Ω1, a residual potential will occur. Further, the thickness of the intermediate layer 2 is suitably about 0.1 to 10 μm.

The intermediate layer 2 is a resin layer made of polyamide resin, polyvinyl alcohol, polyvinyl acetal, polyacrylic acid, etc., or these resins are coated with TlO2°5nOz, SiOx p
It can be formed by dispersing a white pigment such as Mg○ or ZnO.

The first charge generation layer 3 is a layer sensitive to light with a wavelength of 700 n+s or more (for example, light in a wavelength range of 700 to 800 r++*), and includes metal-free phthalocyanine, metal phthalocyanine,
Square dyes, azulenium dyes, trisazo pigments, etc. are used as charge generating materials here. In particular, as a charge generating substance for the first charge generating layer 3 in the present invention, a trisazo pigment represented by the following formula (1) % formula % (1) (wherein A represents a coupler residue) is used. Effective. Some specific examples of this trisazo pigment are as follows. However, for the sake of convenience, only the blade Puller residue will be mentioned here.

Pigment Blood -m-'' L-m-Pigment & -1-JL-11 Pigment Circle □J [□ Pigment & □-A----Pigment Pigment-11 pieces 111 Pigment & -11 pieces 111 Pigment Arashi -n-Pigment Application -11-Δ-111 These charge-generating substances can be used alone or crushed into fine particles to produce polyester, polystyrene, polycarbonate, and polyacrylate.

It is used by dispersing it in resins such as polyvinyl butyral, polyvinyl acetate, and ethyl cellulose. The thickness of this first charge generation layer 3 formed on the intermediate layer 2 is 0.05 to 3
It is about μm. The amount of the charge generating substance in the first charge generating layer 3 is suitably about 1 to 95% by weight.

The second charge generation layer 4 is a layer sensitive to light in the wavelength range of 400 to 700 nm, and a charge generation substance is used therein. The charge generating material here is of course different from that used in the first charge generating layer, and specifically, C.I. Pigment Blue 25 (color index Cl2
1180), CI Pigment Red 41 (CI2
1200), CI Acid Red 52 (CI45
100), CI Basic Red 3 (CI452
10), an azo pigment having a carbazole skeleton (Japanese Patent Application Laid-Open No.
3-95033), azo pigments having a distyrylbenzene skeleton (described in JP-A-53-133445), azo pigments having a triphenylamine skeleton (described in JP-A-53-133445),
JP-A-53-132347 describes a), an azo pigment having a dibenzothiophene skeleton (JP-A-54-217)
58), an azo pigment having an oxadiazole skeleton (described in JP-A No. 54-12742), an azo pigment having a fluorenone skeleton (described in JP-A-54-2283)
4), azo pigments having a bisstilbene skeleton (described in JP-A-54-17733), azo pigments having a distyryloxadiazole skeleton (described in JP-A-54-17733),
-2129), azo pigments having a distyrylcarbazole skeleton (described in JP-A-54-14967), Argo Scarlet B (/<
Indus Thread Scarlet R (manufactured by Bayer AG) and other perylene pigments. In addition,
These charge generating substances may be used alone or in combination of two or more.

The charge generating materials used in the second charge generating layer 4 include polyester, polystyrene, polycarbonate, polyacrylate, polyvinyl butyral, polyvinyl acetate,
After being dispersed in a resin solution such as ethyl cellulose or polysulfone, it is coated on the first charge generation layer 3 to form the second charge generation layer 4. The amount of the charge generating substance contained in the second charge generating layer 4 is suitably about 1 to 80% by weight. Further, the thickness of this second charge generation layer 5 is 0.05
The thickness is preferably about 3 μm.

As described above, in the present invention, two types of pigments are combined and laminated as two charge generation layers to obtain high sensitivity in the wavelength range of 400 to 800 nm.

The reason why the charge generation layer of the present invention is formed as a multilayer by the first charge generation layer 3 and the second charge generation layer 4 is that organic charge generation pigments generally have a color tone of red to orange, red, blue, etc. It is sensitive to green, yellow, red, etc. light, and 4
This is because a highly sensitive organic charge-generating pigment that exhibits absorption over the entire wavelength range of 00 to 800 nm has not yet been found.

The charge transfer layer 5 is formed on the second charge generation layer 4 . This layer 5 is made by dissolving a charge-transporting substance such as polyvinylcarbazole, α-phenylstilbene compound (JP-A-58-198043), or hydrazone compound (JP-A-55-46760) in a film-forming resin. This is because the charge-transporting substance that is formed by this process generally has a low molecular weight and has poor film-forming properties by itself. Examples of such film-forming resins include polyester, polysulfone, polycarbonate, polymethacrylic acid esters, and polystyrene.

The appropriate thickness of the charge transfer layer 5 is about 10 to 30 μm. Further, the proportion of the charge transporting substance in the charge transfer layer 5 is suitably about 25 to 60% by weight.

Although the laminated electrophotographic photoreceptor according to the present invention has the above-described structure, a protective layer may be provided on the charge transfer layer 5. Incidentally, the charge transfer layer 5 in the photoreceptor of the present invention has a property that the mobility of positive carriers is much larger than that of negative carriers.

Therefore, negative polarity is suitable for charging.

To form an image using the photoreceptor of the present invention, the photoreceptor is uniformly negatively charged in accordance with a conventional method, and then, if an analog image is to be obtained, a light source such as tungsten (with a wavelength of 400 to 700 nm) is used.
An image with good halftone reproducibility can be obtained by exposing the image to 0 nm light g), developing it in a conventional manner, and transferring the image to transfer paper (plain paper, etc.). In addition, when obtaining a digital image, after charging, dot-like image exposure is performed using a light source such as a semiconductor laser (a light source with a wavelength of 700 nm or more), then development is performed in the usual manner, and sharp lines can be obtained by transferring to transfer paper. An image is obtained.

It is also possible to create a photoreceptor by swapping the positions of the first charge generation layer 3 and the second charge generation layer 4, but in this case, the photosensitivity in the wavelength range of 400 nm to 700 r+m will decrease, and the analog Inconveniences arise when obtaining images.

Next, examples will be shown.

Example 1 Tie on a 40φ340m aluminum cylinder (Tie Bake manufactured by Ishihara Sangyo Co., Ltd.) 40 gr polyamide resin (CM-8000 manufactured by Toshisha Co., Ltd.) 40 gr methanol A mixture of 400 gr was dispersed in a ball mill for 12 hours, and a prepared liquid was dried. The intermediate layer (volume resistance 3
X105Ωa=) was formed. On the other hand, after dispersing 50g of the pigment Nα9 in a ball mill for 48 hours, methyl ethyl ketone (
400 gr of M E K ) was added, and the mixture was further dispersed for 24 hours, and then diluted (red down) with 2000 gr of M E K to prepare a first charge generation layer forming liquid.

This was applied onto the above-mentioned intermediate layer by a dipping method, and then heated to 130°C for 1
After drying for 0 minutes, a first charge generation layer having a thickness of about 0.1 μl was provided. Next, add 48g of Anon 200gr on top of this.
600g of time-dispersed mixed solvent of anon:MEK=1:1
After adding R and dispersing for 5 hours, the solution prepared by letting down with M E K 10100O was applied by dipping method.
A second charge generation layer having a thickness of about 0.2 .mu.l was provided by drying at .degree. C. for 10 minutes.

Next, a solution having the composition shown below was applied onto the second charge generation layer by a dipping method to form a charge transfer layer having a thickness of about 22 μm.

N-o-CH=C-o-CH3240gr+ CH.

Polycarbonate (Teijinsha 11C-1400) 24
0gr dichloromethane 1520g
r Silicone oil (Shin-Etsu Silicon Co., Ltd. 11KF-50) 1
grAbout the photoreceptor for electrophotography created in this way, as a measurement for analog copying, JP-A-60-1001
By the device described in Publication No. 67.

Its photosensitivity properties were investigated. That is, the charging is at the discharge voltage -5KV
Rotate at a scanning speed of 2000 rpm for 20 seconds and
The dark decay was set to Vo for 20 seconds. Also.

Light was irradiated using a tungsten lamp (color temperature 2856K, illuminance 2. flux) with a slit width of 3I, and the surface potential was 1.
The exposure amount required to attenuate to 72 (half-reduced exposure amount) is E1.
/2 lux·sec, and the potential after 30 seconds after light irradiation (
residual potential) is V,. Closed.

On the other hand, as a measurement for digital copying, JP-A-60-10
A xenon lamp was installed as a light source in the apparatus described in Japanese Patent No. 0167, and a monochromator was used to separate light of 780 nm wavelength and irradiate it onto the photoreceptor (light intensity: 36 μW). Charging and dark decay were carried out in the same manner as the measurements for analog copying described above.

These results are shown in Table-1. In addition, this photoreceptor is
A durability test of 10,000 sheets was conducted using the built-in copying machine shown in the figure. Here, a voltage of -6.5 KV was applied to the charger 7, exposed with a halogen lamp 8, developed with a two-component developer, and then the toner image was transferred onto the transfer paper 12.

Further, 10,000 copies were made by scanning with a polygon mirror using a semiconductor laser (wavelength: 780 nm) as an exposure light source. These electrical properties are also shown in Table 1.

Incidentally, even after copying -10,000 copies, no abnormal images were observed with thin lines in both analog and digital images, and the halftones and halftone dots of the analog images were all good.

Example 2 A mixture consisting of 400g of Anone was placed in a ball mill on the same support as in Example 1 with an intermediate layer, and after dispersing for 48 hours, 400g of furan was added and dispersed for 6 hours, and furan:MEK=1
A solution prepared by letting down 800 gr of a mixed solvent of 2 (weight ratio) was applied by dipping, and dried at 130° C. for 10 minutes to provide a first charge generation layer with a thickness of about 0.2 μm.

After dispersing the mixture on the first charge generation layer in a ball mill for 24 hours, 400 g of a mixed solvent of furan:MEK=1:1 (weight ratio) was added and dispersed again for 4 hours. :1
A solution prepared by letting down with 800g of mixed solvent (weight ratio) was applied by dipping method, and dried to a thickness of approximately 0.1 μm.
A thick second charge generation layer was provided.

Next, the following formulation solution was applied to the second charge generation layer by dipping and dried at 120 DEG C. for minutes to form a charge transfer layer having a thickness of about 20 .mu.m.

a)(.

Polycarbonate (C-1400 manufactured by Ontaisha) 280
grtetrahydrofuran 1700gr
Silicone oil (KF-50 manufactured by Shin-Etsu Chemical Co., Ltd.) 0.5
The image results of the laminated electrophotographic photoreceptor thus prepared were almost the same as in Example 1, and were good. Further, the electrical characteristics are shown in Table-1.

Example 3 40φ340ffI! A 4% methanol-butanol (7:3) solution of polyamide resin (CX-GOOO manufactured by Toshisha Co., Ltd.) was applied by dipping onto an aluminum cylinder of approximately 0.
．． 4 μrn thick intermediate layer (volume resistance 5×10”Ωam)
has been established. After pulverizing and dispersing on this intermediate layer with a ball mill for 12 hours, 400g of THF (tetrahydrofuran) was added, and after dispersing for 1 hour, T
The paint obtained by letdown with HF 2000gr was applied by dipping method and dried at 130°C for 10 minutes to give a coating of approximately 0.0
A first charge generation layer having a thickness of 7 μm was provided. On top of this, 100g of furan was pulverized and dispersed in a ball mill for 36 hours, then 400g of Anon: MEK = 11 (weight ratio) was added and dispersed again for 2 hours, and further let down with 1200g of furan:MEK = 11 (weight ratio). was applied by dipping method and dried to a coating of about 0.12
A second charge generation layer having a thickness of μm was provided.

Next, the same charge transfer layer as in Example 2 was provided to produce an electrophotographic photoreceptor. The electrical characteristics of this are shown in Table 1.

Moreover, the image results of this were almost as good as those of Example 1.

Comparative Example 1 An intermediate layer with the following formulation (thickness: approximately 1 μm, volume resistance: 4×10 5 Ω 1
) was established.

After 400 gr of methanol and 160 gr of butanol, a first charge generation layer, a second charge generation layer, and a charge transfer layer were provided in the same manner as in Example 1 to prepare a comparative electrophotographic photoreceptor. The characteristics of this are shown in Table-1. Furthermore, the image results of this comparative photoreceptor showed that in analog images, the image density was low from the beginning of copying, and the image density became half of the initial value after about 5,000 copies were made. Digital copying was useless from the beginning and was quickly discontinued.

Comparative Example 2 An intermediate layer of the following formulation (thickness: approximately 4 μm, volume resistance: 5×10 5 Ω 1
) was established.

Conductive T10z (Mitsubishi Metals T-1) 40gr
Polyamide resin (CM-8000 manufactured by Toshisha) 40
gr methanol 400gr
Thereafter, a first charge generation layer, a second charge generation layer, and a charge transfer layer were provided in the same manner as in Example 1.

A comparative electrophotographic photoreceptor was prepared. The characteristics of this are shown below.
Shown in 1. Furthermore, the image results of this comparative photoreceptor showed that in analog images, the image density was high from the beginning of copying. Digital copying was useless from the beginning and was quickly discontinued.

Comparative Example 3 An intermediate layer (thickness approximately 2 μm, volume resistance 1015 Ω1 or more) having the following formulation was provided on an aluminum cylinder of 40φ340 m by a dipping method.

Toluene 400grM
After E K 400 gr, the first charge generation layer and the second charge generation layer were coated to the same thickness as in Example 1 by spraying.

For the charge transfer layer, the solution used in Example 1 was diluted with furan and spray coated to the same thickness. The characteristics of the comparative photoreceptor thus prepared were as shown in Table 1. Furthermore, in the image results of this comparative photoreceptor, in analog images, background stains became noticeable around 5,000 copies. Digital copying was useless from the beginning and was quickly discontinued.

Comparative Example 4 A comparative electrophotographic photoreceptor was prepared in exactly the same manner as in Example 1 except that the positions of the first charge generation layer and the second charge generation layer in Example 1 were reversed. The characteristics of this are shown below.
Shown in 1. Furthermore, in the image results of this comparative photoreceptor, in analog images, background stains became noticeable after about 3000 copies were made. Digital copying was useless from the beginning and was quickly discontinued.

(The following is a blank space) [Effects] As described above, the present invention provides a charge generation layer with a multilayer structure including a first charge generation layer sensitive to 700 nm or more and a second charge generation layer sensitive to 400 to 700 nm. As a result, a high-sensitivity photoreceptor suitable for analog and digital copying was obtained.
Furthermore, by providing an intermediate layer having a volume resistivity of 105 to 1014 Ω■, high durability was achieved.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a representative example of an electrophotographic photoreceptor according to the present invention, and FIG. 2 is a schematic diagram showing an example of a copying machine using this photoreceptor. DESCRIPTION OF SYMBOLS 1...Support 2...Intermediate layer 3...First charge generation layer 4...Second charge generation layer 5...Charge transfer layer 6...Photoreceptor 7...Charging Device 9...Second exposure section (semiconductor laser) 10...Developing section 11...Pre-transfer exposure 12...Transfer paper
13...Transfer/separation charge 14...Cleaning section

Claims (1)

[Claims] 1. Volume resistance on conductive support is 10^5 ~ 10^1^
An intermediate layer having a film thickness of 4 Ωcm and a film thickness of 0.1 to 10 μm is provided, a first charge generation layer sensitive to light with a wavelength of 700 nm or more is provided on the intermediate layer, and a
a second charge generation layer sensitive to light in a wavelength range of 0 nm;
A laminated electrophotographic photoreceptor, characterized in that a charge transfer layer and a charge transfer layer are sequentially provided.