JPH034902B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electrophotographic photoreceptor that uses a specific phthalocyanine mixture and zinc oxide as a photoconductor element, has excellent sensitivity and durability, and has no problems in terms of safety and hygiene.

Generally, in electrophotography, like the xerography method, a photoreceptor in which a photoconductor element such as selenium or cadmium sulfide is formed into a thin film on a metal drum is charged in a dark place, and a light image is irradiated (exposed). After forming an electrostatic latent image, a visible image is created using toner (development), and this is transferred and fixed onto paper, etc., or a photoconductive layer (photosensitive layer) is conductive as in the electrofax method. There is a method in which a permanent visible image is obtained on a photoconductive layer by forming the photoconductive layer on paper, charging it, exposing it to light, developing it, and fixing it on the photoreceptor.

Photoconductor elements currently widely used for electrophotographic photoreceptors include inorganic compounds such as amorphous selenium, cadmium sulfide, and zinc oxide.
Amorphous selenium has good properties as a photoconductor element, but it is difficult to manufacture because it must be manufactured by vapor deposition, and the vapor-deposited film is not flexible and is highly toxic, so it must be handled with care. However, it also has the disadvantage of being expensive. Cadmium sulfide and zinc oxide are used in the form of a photoconductive layer dispersed in a binder resin, with a resin/photoconductor element weight ratio of 0.2.
Practical sensitivity cannot be obtained unless it is ~0.3 or less, and therefore it has drawbacks in mechanical properties such as flexibility, smoothness, hardness, tensile strength, and abrasion resistance. Therefore, it cannot withstand repeated use as it is, and cadmium sulfide also requires consideration of hygiene issues.

On the other hand, phthalocyanine is known as an organic compound, which can be dispersed in a binder resin and coated on a conductive substrate, and has excellent flexibility and processability, but when used alone, it has low sensitivity. This is not sufficient for practical use, and sensitization can be achieved by using chemical sensitization and optical sensitization in combination. As a chemical sensitizer,
2,4,7-trinitro-9-fluorenone (TNF), 2,4,5,7-tetranitro-9-
Polycyclic or heterocyclic nitro compounds such as fluorenone (TENF), quinones such as anthraquinone, aromatic amines such as tetramethyl-P-phenylenediamine, and nitrile compounds such as tetracyanoethylene are known. Furthermore, xanthene dyes and quinoline dyes are known as optical sensitizers. However, if these substances are added until a sensitivity sufficient for practical use is achieved, these substances themselves have problems in charging resistance, light resistance, etc., and fatigue phenomena due to continuous charging and exposure to light become a significant problem in practical use. In addition, NTF as a chemical sensitizer,
TENF has a particularly excellent sensitizing effect and is actually often used for organic photoconductors. However, these substances are very expensive, and if a large amount of these substances is added to obtain the sensitivity required for practical use, the photoreceptor becomes very expensive. Furthermore, TNF, TENF, etc. have hygiene problems for the human body, and their use is questionable.

The present invention solves the above-mentioned drawbacks, and does not require chemical sensitizers, which have problems such as hygiene, and significantly improves charging characteristics, and improves sensitivity and durability after repeated use. The present invention relates to an electrophotographic photoreceptor having a photosensitive layer that is excellent, inexpensive, and has excellent hygiene properties. That is, the present invention provides acid pasting-treated phthalocyanine derivatives (B) of ε-type copper phthalocyanine (A), phthalocyanine having an electron-withdrawing group, or a mixture of phthalocyanine having an electron-withdrawing group and other phthalocyanines, and zinc oxide
The present invention provides an electrophotographic photoreceptor characterized in that a photoconductor element is a mixture with (C).

In the present invention, the ε-type copper phthalocyanine (A) is disclosed in Japanese Patent Publication No. 40-2780, filed by the same applicant as the present application,
As detailed in Publications No. 52-6300 and No. 52-6301, when measuring the X-ray diffraction angle, the interplanar spacing is
Strongest line corresponding to 9.72Å, strong line at 11.63Å, 6.24,
5.10, 4.35, 4.19, 3.87, 3.36, 3.28, and 3.03
A weak line is shown in Å. Incidentally, it is known from Japanese Patent Publication No. 1667-1987, filed by the same applicant as the present application, that this ε-type copper phthalocyanine (A) exhibits excellent effects as a photoconductor element for electrophotographic plates.

The present invention is characterized in that the ε-type copper phthalocyanine (A) is mixed with a phthalocyanine derivative (B), and is acid pasted to form fine particles containing electrons such as nitro groups. Due to the presence of the phthalocyanine derivative (B) having an attractive group, electrophotographic properties such as photosensitivity can be further improved, and sensitivity can be achieved without any practical problems without using sensitizers that pose hygiene problems such as TNF. By using zinc oxide (C), the electrophotographic properties such as the stability of repeated charging may vary depending on the type and amount of the phthalocyanine derivative, but by using an appropriate combination, cadmium sulfide, etc. It is possible to obtain the same level of photosensitivity as the photoconductor element, and even more durability.

Phthalocyanines with electron-withdrawing groups include metal-free or various metal phthalocyanine molecules with electron-withdrawing groups such as halogen atoms, nitro groups, cyano groups, sulfone groups, carboxyl groups, sulfamide groups, and carboxamide groups in the benzene nucleus. Therefore, it has been replaced. This phthalocyanine derivative can be obtained by using phthalonitrile, phthalic acid, phthalic anhydride, or phthalimide substituted with the above-mentioned substituents as the raw material for phthalocyanine during phthalocyanine synthesis; It can be obtained by using both. The method for producing the phthalocyanine derivative is not particularly limited. Also,
The number of substituents in one molecule of the phthalocyanine derivative is 1 to 16.

The above-mentioned phthalocyanine having an electron-withdrawing group is subjected to acid pasting treatment together with other phthalocyanine having no electron-withdrawing group, if necessary, to obtain a phthalocyanine derivative (B). Here, acid pasting treatment refers to phthalocyanine having the above-mentioned electron-withdrawing group or other phthalocyanine to sulfuric acid, orthosulfuric acid, pyrophosphoric acid, chlorosulfonic acid, hydrochloric acid, hydroiodic acid, hydrofluoric acid,
forming a salt with an inorganic acid such as hydrobromic acid,
As is known in the organic pigment industry, this is a treatment method in which a phthalocyanine derivative is poured into water, and the precipitated phthalocyanine derivative is filtered, washed with water, and dried, and a product having an α-type crystal form is obtained.

The mixing weight ratio of the ε-type copper phthalocyanine (A) and the phthalocyanine derivative (B) is about 100/0.01 to 200, preferably about 100/0.1 to 100, and has electron-withdrawing properties for all mixed phthalocyanine units. The number of groups is 0.001 or more, preferably 0.01 or more,
It is preferable to mix so that the number is 2 or less.

Zinc oxide (C) that is known per se as a photoconductor element is used. Zinc oxide (C) is added at a weight ratio of about 1/10 to 10/10, preferably 3/10 to 6/10, to the mixture of ε-type copper phthalocyanine (A) and phthalocyanine derivative (B). used.

In order to make an electrophotographic photoreceptor from the mixture of the above-mentioned ε-type copper phthalocyanine (A), phthalocyanine derivative (B) and zinc oxide (C), together with a binder resin, a solvent, etc.
The mixture is uniformly dispersed using a kneading and dispersing machine such as a ball mill or attritor, and coated onto a conductive support to form a photosensitive layer. The electrophotographic photoreceptor of the present invention may include not only an electrophotographic photoreceptor with only a photosensitive layer on a conductive support, but also an electrophotographic photoreceptor with a barrier layer, an insulating layer, and a photosensitive layer of another photoconductor element laminated thereon. It is also possible to use a sensitizer in combination.

Binder resins include melamine resins, epoxy resins, silicone resins, polyurethane resins, acrylic resins, xylene resins, vinyl chloride-vinyl acetate copolymer resins, polycarbonate resins, cellulose derivatives, and other insulation materials with a volume resistivity of 10Ω or more. It is a binder resin with properties.

As a conductive support, an aluminum plate, conductively treated paper, conductively treated plastic film, etc. is coated to form a photosensitive layer. As for the coating method, if necessary, a solvent is added to adjust the viscosity, and a film is formed using an air knife coater, a blade coater, a rod coater, a reverse roll coater, a spray coater, a hot coater, a squeeze coater, or the like. After coating, drying is performed using a suitable drying device.

The present invention will be explained below by giving examples. In the examples, "parts" indicate parts by weight.

Example 1 40 parts of copper phthalocyanine and 0.5 parts of tetranitrocopper phthalocyanine are dissolved in 500 parts of 98% concentrated sulfuric acid with thorough stirring. Pour the dissolved solution into 5,000 parts of water to precipitate a composition of copper phthalocyanine and tetranitrocopper phthalocyanine, then filter, wash with water, and remove under reduced pressure.
Dry at 120℃.

50 parts of the composition thus obtained and ε-type copper phthalocyanine (Lionol Blue ER. Toyo Ink Mfg. Co., Ltd.)
Disperse 100 parts of product name) in 5000 parts of methanol to make a uniform mixed dispersion. Thereafter, it is filtered and dried at 120° C. under reduced pressure to obtain a mixture [], and a photoconductive composition is prepared based on the following formulation.

Mixture [] 10 parts Acrylic polyol (Takerakku UA-702,
Takeda Pharmaceutical Co., Ltd. (trade name) 25 parts Epoxy resin (Epicote #1007, Ciel Chemical Co., Ltd. trade name) 2 parts Methyl ethyl ketone 26 parts Cellosolve acetate 26 parts Chemical Industry SAZEX #2000) 35
% and further kneaded for 10 hours to obtain a photoconductive composition.

This photoconductive composition was then applied to the aluminum of a laminate film of 5μ thick aluminum film and 75μ thick polyester film to a dry film thickness.
It was roll coated to a thickness of 8μ and placed in an oven uniformly heated to 110° C. for 1 hour to prepare an electrophotographic photoreceptor. For the sample obtained in this way, +
Corona discharge is applied at 6.0 KV, corona gap 10 mm, and charging speed of 10 m/min, and 10 seconds after the discharge stops, it is exposed to a 2854 K tungsten light source with an illuminance of 10 _Lux . The amount of light irradiation required for the potential immediately before exposure to decrease by 50% at this time was defined as the sensitivity. The sample measured in this manner had a maximum surface potential of 570 V, a dark decay rate of 2%, a sensitivity of 2.5 L _ux ·sec., and a residual potential of 15 V, showing values sufficient for practical use in both chargeability and sensitivity. Using this photoreceptor, an image was created by the following development and transfer method.

Positive charge is given to the photoreceptor by corona discharge at 100W.
A positive film original image is projected at 10 _Lux for 1 second using a tungsten light source for enlargement to form an electrostatic latent image on the photoreceptor, and then a visible image is obtained using negatively charged powder toner. A piece of high-quality paper was placed on top of it, and a visible image was transferred from the back of the paper using a positively charged corona discharge with an applied potential of +5KV, and fixed using an infrared lamp. The image obtained by this operation was extremely faithful to the original, and a clear, high-contrast image with no background smudges was obtained. Furthermore, regarding charge retention, there is no change in electrophotographic properties even after repeated copying.
The 15,000 copies were of similar quality to the original.

Comparative Example 1 When the electrophotographic properties were investigated when an electrophotographic photoreceptor was prepared as a photoconductive composition using ε-type copper phthalocyanine alone instead of the mixture [] shown in Example 1 in the same manner as in Example 1, it was found that the maximum surface The potential was 780 V, the dark decay rate was 38%, the sensitivity was 17.4 _Lux ·sec., and the residual potential was 25 V, which were impractical values in sensitivity when no sensitizer was used.

Comparative Example 2 Mixture of Example 1 [] 10 parts acrylic polyol (Takerak UA-702,
36 parts Epoxy resin (Epicote #1007, trade name manufactured by Ciel Chemical Co., Ltd.) 6 parts Methyl ethyl ketone 20 parts Cellosolve acetate 20 parts Electrophotographic photosensitive composition was prepared in the same manner as in Example 1 using the above formulation. When examining the electrophotographic characteristics when used as a body, the maximum surface potential is 580V, the dark decay rate is 11%, the sensitivity is 15L _ux・sec., and the residual potential is 20V.
Although an improvement in sensitivity was observed, there was a problem with repeated charge retention, and the image density decreased after 1000 sheets.

Example 2 40 parts of metal-free phthalocyanine and 1.5 parts of mononitro copper phthalocyanine are dissolved in 1000 parts of 98% concentrated sulfuric acid with thorough stirring. The dissolved solution is poured into 10,000 parts of water to precipitate the phthalocyanine composition, which is then filtered, washed with water, and dried at 120°C under reduced pressure.

30 parts of the composition thus obtained was mixed with 100 parts of ε-type copper phthalocyanine (Lionol Blue ER), and a mixture [] was prepared in the same manner as in Example 1. Create a conductive composition.

Mixture [] 10 parts acrylic resin (T-coat PFX-7120, trade name manufactured by Toyo Ink Co., Ltd.) 40 parts silicone resin (Shin-Etsu Silicone KR-211,
Shin-Etsu Chemical (product name) 15 parts Methyl ethyl ketone 35 parts Toluene 25 parts The above composition was milled in a magnetic ball mill for 48 hours, and 35 parts of zinc oxide (same as in Example 1) was added.
The mixture is further kneaded for 10 hours to obtain a photoconductive composition. This photoconductive composition was prepared in the same manner as in Example 1 to about 80 μm.
The film was roll coated onto a hard aluminum plate to a thickness of 6 μm, and after the film was formed, it was placed in an oven uniformly heated to 150° C. for 15 minutes to form an electrophotographic photoreceptor.

The maximum surface potential, dark decay rate, and sensitivity of the thus obtained photoreceptor were measured in the same manner as in Example 1. As a result, the maximum surface potential was 580 V, and the dark decay rate was 2.3.
%, the sensitivity was 3.5L _ux ·sec., and a photoreceptor with extremely good charge retention was obtained.

When an image was created using this photoreceptor in the same manner as in Example 1, an electrophotographic photoreceptor that was clear, faithful to the original, high in contrast, and durable for repeated use as in Example 1 was obtained.

Example 3 40 parts of copper phthalocyanine and 0.5 part of tetracyanocobalt phthalocyanine were dispersed in 200 parts of glacial acetic acid,
10 parts of 98% sulfuric acid was added dropwise while stirring, and after stirring for 10 hours, the solid matter was filtered out, and the phthalocyanine composition was precipitated through ammonia gas, washed with water, and dried at 120°C under reduced pressure. do.

A photoconductive composition is prepared from the mixture thus obtained according to the following formulation.

Mixture [] 10 parts ε-type copper phthalocyanine 5 parts branched polyester polyol (Desmophene #800, trade name manufactured by Nippon Polyurethane Industries) 52 parts Cellosolve acetate 120 parts Polyisocyanate compound (Desmodyur N
-75, trade name manufactured by Nippon Polyurethane Industry Co., Ltd.) 8.4 parts The upper four points of the above five points were kneaded in a magnetic ball mill at room temperature for 30 hours using the above composition, and then mixed with zinc oxide (same as in Example 1). Mix 50 parts and add 10
The mixture is milled for a period of time, and then a polyisocyanate compound is added to form a photoconductive composition.

The resulting photoconductive composition was coated with 99.99% pure aluminum powder on a 75μ polyester film.
Roll-coat the film to a thickness of 15μ on a substrate vacuum-deposited to a thickness of approximately 1μ at a vacuum level of 10torr.
This was left for a minute to obtain an electrophotographic photoreceptor.

The photoreceptor thus obtained was measured in the same manner as in Example 1, and the maximum surface potential was 950V.
A photoreceptor with a dark decay rate of 1.2%, a sensitivity of 3.5L _ux ·sec., excellent charge retention and repeated chargeability, and a high coating strength was obtained. When an image was created using this photoreceptor in the same manner as in Example 1, a clear image faithful to the original pattern was obtained.

Example 4 50 parts of trinitrocopper phthalocyanine in 98% concentrated sulfuric acid
Dissolve in 600 parts with sufficient stirring. The dissolved solution is poured into 6000 parts of water to precipitate a composition of α-type trinitrocopper phthalocyanine, which is then filtered, washed with water, and dried at 120°C under reduced pressure. Using 50 parts of the composition thus obtained and 100 parts of ε-type copper phthalocyanine,
Otherwise, a photoconductive composition was prepared in the same manner as in Example 1, and the electrophotographic properties were examined when it was used as an electrophotographic photoreceptor.The maximum surface potential was 720V, the dark decay rate was 3%, and the sensitivity was 29L _ux・sec.Residual potential The voltage was 7V, and the repeatability of charging was good.

Example 5 An electrophotographic photoreceptor was prepared in the same manner as in Example 4 except that tetracyanocopper phthalocyanine was used instead of trinitrocopper phthalocyanine.The electrophotographic properties were investigated and the maximum surface potential was 830V, the dark decay rate was 3.7%, Sensitivity was 3.1L _ux ·sec. Residual potential was 3V, and repeat charging performance was good.

Claims (1)

[Claims] 1 ε-type copper phthalocyanine (A), a phthalocyanine derivative (B) treated with acid pasting of a phthalocyanine having an electron-withdrawing group or a mixture of a phthalocyanine having an electron-withdrawing group and other phthalocyanines, and zinc oxide ( An electrophotographic photoreceptor characterized in that a photoconductor element is a mixture of C).