JPH03100559A - Electrophotographic sensitive body using laser beams - Google Patents

Abstract

PURPOSE:To obtain an electrophotographic sensitive body using semiconductor laser beams and stably high in sensitivity to the beams by incorporating a specified polymethine type cyanine dye as a sensitizing dye and using a specified cyclic acid anhydride in combination with the dye. CONSTITUTION:The electrophotographic sensitive layer using the laser beams and containing photoconductive zinc oxide, a binder resin and at least one of the sensitizing dyes represented by formulae I and II as a sensitizer is formed on a conductive substrate resistant to water. At least one of the sensitizing dye assistants made of cyclic acid anhydride derived from aromatic acid having >=3 -COOH on a benzene ring is used in combination with the dye. In formulae I and II, each of R<1> - R<4> is methyl, ethyl, or the like, and X is Br or Cl, thus permitting the obtained photosensitive body to be high in sensitivity to the semiconductor laser beams and superior in environmental stability.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an electrophotographic photoreceptor for use with laser light. More specifically, the present invention relates to an electrophotographic photoreceptor spectrally sensitized to semiconductor laser light, ie, red light to infrared light.

[Conventional technology]

Generally, an electrophotographic photoreceptor with a zinc oxide-resin dispersion system has photoconductive zinc oxide as a main component on the surface of a conductive substrate.
A photosensitive layer is formed by blending a binder and a sensitizer with this.

The sensitive wavelength range of zinc oxide itself contained in the photosensitive layer is
Because it exists only near the ultraviolet region (370n+),
In order to use this in an electrophotographic photoreceptor that can also be used for visible light, it is generally necessary to add an aggravating dye to broaden the wavelength range to which it is sensitive.

Conventionally, visible light was used as the exposure light source for these electrophotographic photoreceptors, but with the development of recording equipment such as laser printers, laser light such as helium neon laser is now increasingly used for argon laser formation. Became. When using such a laser beam in the visible range, it is known that zinc oxide is spectrally sensitized by adding a sensitizing dye such as rose bengal, erythrosine, or bromophenol blue.

However, recently, semiconductor laser light (visible to near-infrared long-wavelength light with a wavelength of 700 to 11,000 nm) is being used, which is cheaper than these laser lights, can be directly modulated, and can make devices more compact. It is becoming. The sensitivity of zinc oxide photoreceptors added with the above-mentioned sensitizing dyes to such semiconductor laser light is extremely low or has no sensitivity at all; therefore, such photoreceptors are not suitable for semiconductor laser light. It is inappropriate as such.

Examples of electrophotographic photoreceptors sensitive to the wavelength range of semiconductor laser light include JP-A-57-46245, JP-A-58-58554, JP-A-58-59453, and JP-A-59-22053. , JP-A-59-78358, JP-A-60-26949, etc. Such a zinc oxide electrophotographic photoreceptor is one in which a sensitizing dye such as a polymethine cyanine dye is blended into the photosensitive layer to perform spectral sensitization to long wavelength light. However, the sensitivity of these electrophotographic photoreceptors with only added sensitizing dyes is still not satisfactory, especially in recording equipment such as laser printers, which require high-speed scanning exposure. Therefore, conventional electrophotographic photoreceptors containing sensitizing dyes as described above are considered to be impractical.

In addition to the sensitizing dyes, some electrophotographic photoreceptors sensitive to the semiconductor laser light mentioned above also contain sensitizing aids such as benzoquinone, chloranil, phthalic anhydride, dinitrobenzoic acid, and tetracyanoquinodimethane. Although some electron-affinity compounds are used, their aggravating effect is not sufficient due to the insufficient adsorption of these compounds to the surface of zinc oxide, and the problem with the electrophotographic photosensitive layer in the dark. Some have the disadvantage of lowering the resistance more than necessary.

[Problem to be solved by the invention]

The present invention provides an electrophotographic photoreceptor that has extremely high sensitivity to long-wavelength light of wavelengths 700 to 11,000 nm, and therefore has high sensitivity and is stable for use with semiconductor laser light. .

[Means and effects for solving the problem] As a result of intensive research in order to solve the above-mentioned problems and obtain a good electrophotographic photoreceptor for laser beams, the present inventor has developed a specific polymethine cyanine as a sensitizing dye. Using a dye and combining it with a specific cyclic acid anhydride, 700-1000n
It was revealed that the present invention shows extremely high sensitivity to light with a wavelength of -. That is, the electrophotographic photoreceptor for laser light of the present invention includes a support having conductivity and water resistance, a support formed thereon, and a photoconductive zinc oxide, a resin binder, and a sensitizer. and an electrophotographic photosensitive layer for laser light, wherein the sensitizer has (a) the following general formulas (I) and (U): and [wherein R1, R2, R3, and R4 are , each independently of the others, CI+3. CzHs, and -C1i□C1 (= represents an I member selected from the CHz group, X is Br, Cff and I atom, and CZO,
and 0302*, representing one member selected from C83.

]; (b) 3 or more -C00 as substituents on the benzene ring;
and a sensitizing aid consisting of at least one cyclic acid anhydride derived from an aromatic acid having 8 groups.

In the present invention, the content of the sensitizing dye contained in the electrophotographic photosensitive layer is generally o, oo
It is preferably within the range of t to 0.5%, and 0.01
It is more preferably within the range of 0.2%.

The cyclic acid anhydride used as a sensitizing aid in the present invention may have one, two or three cyclic acid anhydride structures per benzene ring. Specific examples include aromatic cyclic acid anhydrides such as pyromellitic anhydride and trimellidic anhydride. Since these cyclic acid anhydrides have a strong adsorption power to zinc oxide, they significantly enhance the sensitizing effect and also rarely worsen dark decay. Such a sensitizing effect is caused by the general formula (I) and (
It is particularly effective when used in combination with a sensitizing dye consisting of a polymethine cyanine dye shown in II).

Generally, the content of the sensitizing aid contained in the electrophotographic photosensitive layer is preferably within the range of 0.01 to 1%, and within the range of 0.02 to 0.5%, based on the weight of zinc oxide. It is more preferable that the

The zinc oxide used in the electrophotographic photosensitive layer has photoconductivity, and -a is a fine powder having a particle size of 0.1 to 0.5 μm.

The insulating binder resin used in the electrophotographic photosensitive layer may be made of a single type of resin, or may be a mixture of two or more types of binder resins. Examples of such binder resin include polyester resin, acrylic resin, epoxy resin, polycarbonate resin, melamine resin, butyral resin, silicon resin, polyurethane resin, polyamide resin, alkyd resin, polystyrene resin, xylene resin, phenoxy resin, etc. is used.

The solid content of the resin binder contained in the electrophotographic photosensitive layer is preferably 10 to 30% based on the weight of zinc oxide;
It is more preferably within the range of ~25%.

Examples of the conductive support for the electrophotographic photoreceptor of the present invention include known supports, such as metal sheets, metal foils, paper and plastic films laminated with metal foils, paper and plastic films with vapor-deposited metal layers, and
You can choose from conductive treated paper, plastic film, etc.

To produce the electrophotographic photoreceptor of the present invention, first, a sensitizer consisting of a predetermined amount of zinc oxide, a sensitizing dye, and a sensitizing aid;
A coating solution is prepared by mixing and dispersing the resin binder and an organic solvent such as toluene or ethyl acetate using a mixing and dispersing machine such as a ball mill, sand grinder, or paint shaker. In this mixing step, all components may be mixed at the same time, but
Preferably, the sensitizing aid is adsorbed on the surface of the zinc oxide particles in advance, and then the remaining components are mixed therein. In this case, zinc oxide is added and dispersed in a solution containing a sensitizing aid, and then the solvent is evaporated, or the sensitizing dye and resin binder are sequentially added to this dispersion without evaporating. Preferably, a liquid is prepared.

Next, the obtained coating liquid is applied onto one surface of the support and dried to form an electrophotographic photosensitive layer. The thickness of the electrophotographic photosensitive layer in this case affects chargeability, sensitivity, and resolution, and is usually preferably in the range of 5 to 25 mm.
More preferably, the distance is within the range of 0 to 20 m.

Scanning exposure with semiconductor laser light (780n+++) is performed to form an electrostatic latent image on the electrophotographic photosensitive layer, and this electrostatic latent image is developed with toner and fixed by heating to obtain a toner image on the plate.

Next, the obtained printing plate is used as it is by being mounted on an offset printing machine.

〔Example〕

Next, the present invention will be explained in more detail with reference to examples, but these are not intended to limit the content of the present invention. Note that "parts" and "%" in the examples represent parts by weight and % by weight, respectively, unless otherwise specified.

Sharpened zinc oxide (manufactured by Sakai Chemical Co., Ltd., trademark: 5AZEX 1200)
0) 90 parts polyacrylic resin (manufactured by Mitsubishi Rayon Co., Ltd., trademark: LR-
188) 25 parts trimellitic anhydride (sensitizing aid) 0.1 part toluene 1
20 parts were mixed. To this mixed solution, a solution of 0.02 part of the compound of the general formula (I) [wherein R1 and R2 both represent -GHz CH''''CHz group] dissolved in 3 parts of dimethyl formaldehyde was added as a sensitizing dye. In addition, this mixed solution was dispersed with a sand grinder to obtain a coating liquid.

As a support, a thick paper with a basis weight of 80 g/rrf and a thickness of 10
A composite sheet made by laminating μ aluminum foil was used.

The coating solution was applied onto the aluminum foil surface of the support, dried with hot air at 100°C, and the thickness was 15711 mm.
The electrophotographic photosensitive layer No. 1 was formed to obtain an electrophotographic photoreceptor.

After conditioning the obtained electrophotographic photoreceptor for 24 hours in a dark place in a 25°C 150% RH atmosphere, the surface of the photoreceptor was negatively corona charged at -6 kV, and then irradiated with light having a wavelength of 780 nm. Then, the attenuation of the potential on the surface of the photoreceptor was measured, and from the measurement results, the half-reduction exposure amount was determined as the sensitivity of the photoreceptor. Also, after negative corona charging, leave it for 60 seconds in a dark place, and the potential after 60 seconds is the initial potential ■. The value divided by is calculated, and this value is taken as the dark decay retention rate. These results are shown in Table 1.

Further, the obtained photoreceptor was negatively corona charged at -6 kV, and then irradiated and scanned with semiconductor laser light (51, wavelength 780 nm) according to a predetermined pattern. Next, the electrophotographic photosensitive layer irradiated with laser light was developed using a positively charged toner (manufactured by Itek). After development, use an etchant (Ite
After desensitization treatment using a product from Company K), printing was performed using an offset printing machine (Ryobi 2800CD, Synflo type), and printing stains, fine line reproducibility, and resolution were evaluated. The results are shown in Table 1.

The same operation as in Example 1 was performed. However, as a sensitizing dye,
0.02 part of the compound of the general formula (I) (wherein R+ and RZ both represent a -C1h group) was used.

The test results are shown in Table 1.

Step 1 The same operation as in Example 1 was performed. However, as a sensitizing dye,
Compound 0. of the general formula (II) [wherein R3 and R4 both represent -cHz-CI=CH].
02 parts were used.

The test results are shown in Table 1.

The same operation as in Example 1 was carried out9 However, as a sensitizing agent,
0.1 part of pyromellitic anhydride was used.

The test results are shown in Table 1.

, Comparison 1) The same operation as in Example 1 was performed. However, no sensitizing agent was used.

The test results are shown in Table 1.

Stop comparison lit The same operation as in Example 1 was performed. However, as a sensitizing agent,
0.1 part of phthalic anhydride was used.

The test results are shown in Table 1.

The same operation as in Example 2 was performed. However, as a sensitizing agent,
0.1 part of phthalic anhydride was used.

The test results are shown in Table 1.

1tJfJL4 The same operation as in Example 3 was performed. However, as a sensitizing agent,
0.1 part of phthalic anhydride was used.

The test results are shown in Table 1.

↓Part 11'' The same operation as in Example 1 was performed. However, as a sensitizing agent,
061 parts of benzoquinone was used.

The test results are shown in Table 1.

, L Comparison J- The same operation as in Example 1 was performed. However, as a sensitizing agent,
0.1 part of chloranil was used.

The test results are shown in Table 1.

Table 1 〔note〕 *1 The printed matter was subjected to sensory evaluation as follows.

O: Good △: Slightly poor ×: Poor Actual image L [L- The photoreceptor prepared in each of Examples 1 to 4 was
After being left for 12 hours under the low humidity condition of 0% R1+, the high humidity condition of 30° C. 185% RH, and the heating condition of 80° C., the obtained photoconductor was treated in the same manner as in Example 1. The resistance to low humidity and high temperature environments and heat resistance were evaluated. The results are shown in Table 2.

Table 2 (Example 5) As Table 1 clearly shows, the photoreceptors of Examples 1 to 4 had high sensitivity to semiconductor laser light (wavelength 780 nm). In Comparative Examples 1 to 6, practical sensitivity could not be obtained. Further, as shown in Table 2, it was found that there was little variation in sensitivity, dark decay, and printability even under high temperature, low humidity conditions, and under heating conditions. By using a specific cyclic acid anhydride as a sensitizing agent, it is possible to obtain an electrophotographic photoreceptor using zinc oxide that improves sensitivity, reduces dark decay, and is resistant to environmental changes. is now possible.

〔Effect of the invention〕

The electrophotographic photoreceptor for laser light of the present invention exhibits high sensitivity to laser light, particularly semiconductor laser light, and provides a photoreceptor with excellent environmental stability.

This has made it possible to put into practical use scanning exposure using semiconductor laser light, which has been considered difficult for zinc oxide electrophotographic photoreceptors.

Claims (1)

[Claims] 1. Electrophotography for laser light comprising a support having conductivity and water resistance, photoconductive zinc oxide formed thereon, a resin binder, and a sensitizer. The sensitizer has a photosensitive layer, and the sensitizer has (a) the following general formulas (I) and (II); ▼(II) [However, in the above formula, R^1, R^2, R^3, and R^
4 are -CH_3, -C_2H, each independently from the other
_5, and -CH_2-CH=CH_2 group;
Represents one member selected from. ] A sensitizing dye consisting of at least one compound represented by (b) 3 or more -COO as a substituent on the benzene ring
1. An electrophotographic photoreceptor for laser light, comprising a sensitizing aid consisting of at least one cyclic acid anhydride derived from an aromatic acid having an H group.