JPS609259B2 - Photosensitive materials for electrophotography - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to electrophotography, particularly to a method for roughening an electrophotographic photosensitive layer using an organic photoconductive substance, and to improving the ease of addition. It is characterized by having an appropriate amount of a roughening agent prepared by mixing low molecular weight polyethylene and silicon dioxide fine powder dispersed in the optical layer.
An object of the present invention is to provide an organic electrophotographic photosensitive material having a box-shaped photosensitive layer with improved heat resistance and excellent rewriting properties.

Conventionally, electrophotographic photoreceptors generally have a thin layer of an inorganic or organic semiconductor on a support such as a metal plate, conductively treated paper, tracing vapor, various plastic films, or a glass plate. In the case of an electrophotographic photoreceptor having an inorganic photoconductor layer, such as a photoconductor layer made of zinc oxide and a binder, the surface is naturally heat-resistant and rough. The photoconductor layer is opaque, so there is no practical problem in terms of retouchability even if it is used in a dry type photocopying machine that fixes images by heating at high temperatures. It is difficult to use. In the case of an electrophotographic photoreceptor using an organic photoconductor layer, the layer is composed of, for example, a polynuclear aromatic pinyl polymer that itself has film-forming properties, a vinyl polymer that has hetero side chains, or the like, or Non-film properties, such as oxadiazole series, thiazole series, thiadiazole series, triazole series, imidazole series, imidazolone series, oxazole series, pyrazoline series, imidazolidine series, pyrazine series, triazine series, oxazolone series, quinoxaline series, quinazo 1' In the case of a polymeric material such as a nitrogen-based, furan-based, acridine-based, carbazole-based, phenoazine-based, allylamine-based, etc., other polymeric substances having suitable film-forming properties such as phenol resin, alkyd resin, polyester resin, diaryl phthalate resin may be used. , epoxy resin, vinyl chloride resin, vinylidene chloride resin, vinyl acetate resin, styrene resin, styrene copolymer resin, methacrylate resin, polyamide resin, polyphenylene oxide resin, polysulfone resin, polycarbonate resin, etc., are bonded appropriately. used as an agent,
Furthermore, as a sensitizing dye, for example, Victoria Blue B,
Crystal violet, ethyl violet, methyl violet, malachite green, rhodamine B, rhodamine 8C, rose besogal, fluorescein, methylene blue, etc. are used, and as chemical sensitizers, for example, tetracyanoethylene, tetracyanoquinodimethane, bromanil, chloranil, Benzoquinone, naphthoquinone, anthraquinone, and derivatives thereof, p-nitrophenol, picric acid, 1,3,5-trinitrobesozene, monochloroacetic acid, and the like are used. Since the organic photoconductor layer thus obtained has good transparency, a transparent support is also selected, and it is now used as a second original for diazo copying. However, since the surface is extremely smooth, it is extremely difficult to write on it with a pencil or the like, and when it is copied using, for example, a known wet-type electronic copying machine, the toner fixability is also poor. An object of the present invention is to uniformly roughen the surface of the organic electrophotographic photoreceptor described above, and to further improve the ease of writing, particularly when copying with a dry type electronic copying machine.

Conventionally, methods for roughening the surface of such an organic electrophotographic photoreceptor include a method of dispersing inorganic fine powder in the photosensitive layer, a method of precipitating an organic polymer substance, making it into fine particles, and dispersing it. .

In the case of the former method of dispersing inorganic fine powder, various pigments such as calcium carbonate, zinc oxide, titanium dioxide, silicon dioxide, glass powder, talc, etc. are used dispersed as the inorganic fine powder, and it has excellent heat resistance. However, these inorganic fine powders, except for silicon dioxide, generally have the disadvantage of poor transparency in diazo copying. Generally, in fields requiring diazo copying, fine powder of sulfur dioxide is used as a phase agent. However, when these inorganic fine powders are dispersed as a surface roughening agent in a photosensitive layer coating solution, the dispersion stability is extremely poor, and it is difficult to produce an electrophotographic photoreceptor having a uniform rough surface. In order to improve dispersion stability, it is possible to add various commercially available dispersants, but this causes problems such as a decrease in sensitivity and a decrease in image density. The latter method of precipitating organic polymer substances was developed in Tokuseki Sho 5.
There are methods described in Japanese Patent Application No. 0-6344 and Japanese Patent Application No. 49-93958. Although JP-A-50-6344 is an effective method, it has drawbacks such as poor stability and manufacturing difficulties, such as selection of solvent, selection of manufacturing conditions, and agglomeration and coarsening of particles after dispersion. The method of the patent application group 1983-939 has good dispersion stability of the surface roughening agent in the photosensitive layer coating solution, and can form an effective surface roughness at low temperatures, but it has poor heat resistance, so it cannot be used in dry type electronic copying machines, etc. When image fixing is carried out at a high temperature of 100 qo or more, the surface roughening agent softens or melts and loses writability, and it also has the disadvantage of being inferior in writability compared to the former method of dispersing inorganic fine powder. . The present invention provides an organic electrophotographic photoreceptor which solves all the drawbacks of the above-mentioned two methods and takes advantage of only the advantages of both methods.

That is, the present invention is characterized in that a phase-forming agent obtained by mixing low molecular weight polyethylene and fine silicon dioxide powder is dispersed in an electrophotographic photosensitive layer using an organic photoconductor on a support. The present invention provides an organic electrophotographic photosensitive material.

According to the present invention, the dispersion stability of the roughening agent in the photosensitive layer coating solution is extremely excellent, and it is possible to obtain an organic electrophotographic light-sensitive material with a homogeneous roughened surface, which also has excellent heat resistance. Therefore, it is possible to obtain an excellent organic electrophotographic light-sensitive material that does not deteriorate in its retouchability with a pencil or the like even when it is copied using a dry electrophotographic copying machine that performs heat fixing.

Next, the present invention will be specifically explained.

The low molecular weight polyethylene used in the present invention has a molecular weight of 1
,000 to 15,000 preferably (molecular weight 1,500 to
5,000 is good.

Such low molecular weight polyethylene is melted in organic solvents such as benzene, toluene, xylene, etc., aromatic hydrocarbon solvents, carbon tetrachloride, trichlene, chloroform, monochlorobenzene, etc. when hot, and precipitated when cold. Tokubuta No. 49-93958 describes a method for roughening the surface using only low molecular weight polyethylene. Next, as the silicon dioxide fine powder used in the present invention, one having a particle size of 50 microns or less, preferably one with a particle diameter of 20 microns or less and having high purity is preferred.For example, silicon tetrachloride is hydrolyzed in an oxygen flame. Preferred are a dry process silicon dioxide fine powder produced by a dry process, a wet process silicon dioxide fine powder produced by decomposing silicate with acid or carbon dioxide, and a fine borosilicate powder produced by gelling citric acid.

As a method for preparing the surface roughening agent of the present invention, for example, low molecular weight polyethylene is dissolved in toluene heated to 70 o Prepare by cooling to room temperature as you go.

Although there is no particular restriction on the mixing ratio of low molecular weight polyethylene and silicon dioxide fine powder, it is preferable that the amount of camphorium dioxide fine powder is about 0.2 to 2 parts by weight per 1 part by weight of low molecular weight polyethylene. The surface-graining agent thus obtained is mixed and dispersed in an organic electrophotographic photosensitive layer coating solution, and the coating solution is coated on a support in a thin layer of about 6 layers per dry weight by a known method. Coating to produce an organic electrophotographic photoreceptor. There is no particular limit to the amount of the hammering agent added, but it is preferably in the range of 2 to 5 weight percent in terms of solid content, based on the dry organic electrophotographic photosensitive layer. If the amount added is too large, the sensitivity of the photosensitive layer will decrease,
If it is too small, the writability will deteriorate, which is not preferable. Next, the present invention will be explained in more detail with reference to Examples, but the present invention is not particularly limited by these Examples.

Example 1 N,N,N',N'-tetrabenzyl-m-phenylenediamine (organic photoconductor)
Polycarbonate resin (trade name, manufactured by Mitsubishi Gas Chemical Co., Ltd.) (88%) and 1.5% (chemical sensitizer) of p-nitrophenol (chemical sensitizer) were dissolved in 100 g of monochlorobenzene, and this was designated as A.

Next, 1 mol. Cool to room temperature while using a rope frame and ultrasonic dispersion, and use this as roughening agent B. B is mixed into A and a uniform dispersion is made by ultrasonic dispersion. To this, 1% of crystal violet and N,N-dimethyformamide solution were added for 5 hours, and applied with a wire bar to a conductive-treated tracing paper so that the dry weight was 4 degrees/force. , an organic electrophotographic photosensitive material was obtained. This dispersion was allowed to stand for 2 hours, but no sedimentation or aggregation occurred. Furthermore, the photosensitive surface of this product was extremely uniform and rough, and furthermore, it could be remarked with a pencil having a hardness of 4 days very well. Next, printing was carried out using a dry electronic copying machine (Jumbo Printer 500FX manufactured by Canon K.K.), and a high-density copy without capri was obtained. After copying, the retouchability of the photosensitive surface was examined again, and it showed the same good retouchability as before copying. Further, when printing was carried out using a wet type electronic copying machine, the toner fixability was also good. For comparison, instead of the roughening agent B in this example, the average molecular weight 5,
A surface roughening agent made only of low molecular weight polyethylene 000 and a surface roughening agent made only of fine silicon dioxide powder were prepared, placed in A, and subjected to ultrasonic dispersion to produce an organic electrophotographic light-sensitive material. The one made only of molecular weight polyethylene has extremely poor retouchability after copying with the above-mentioned dry copying machine, and the latter one made only of fine silicon dioxide powder has extremely poor stability of the dispersion, and settles in one hour. An organic electrophotographic material having a uniform lees surface due to aggregation was not obtained. Example 2 An average molecular weight of 2 was used instead of the low molecular weight polyethylene of Example 1.
,000 low molecular weight polyethylene was used in the same manner as in Example 1, good results were obtained.

Example 3 N,N,N',N'-tetrabenzyl-p-phenylene diamine (organic photoconductor) for 10 days, polyphenylene oxide resin (average degree of polymerization 80) for 10 days, and N,N'-jet One day of tilthioparbylic acid was dissolved in 90 g of o-xylene, and this was designated as A.

Next, one day of low molecular weight polyethylene with an average molecular weight of 4,000 was melted at a temperature of 90oC or higher using 10 o-xylene,
After dissolving, 0.5 μm of the silicon dioxide fine powder described in Example 1 was added, and the mixture was cooled while being dispersed with water and ultrasonic waves, and this was used as a roughening agent B. B was mixed into A and the same procedure as in Example 1 was carried out to obtain an organic electrophotographic light-sensitive material. This product also showed the same excellent dispersion stability and ease of addition as in Example 1. Example 4 Good results were obtained in the same manner as in Example 3 using fine silicon dioxide powder having an average particle size of 3.3 microns instead of the fine silicon dioxide powder in Example 3.

Example 5 In the roughening agent B of Example 3, 1.5 tons of low molecular weight polyethylene with an average molecular weight of 4,000 was dissolved at a temperature of 90 qo or more in 12 o-xylene, and after melting, silicon dioxide fine powder (average particle size) was dissolved. 1.5 mm (diameter: 40 millimeters) was added, and the mixture was cooled while being dispersed by hawking and ultrasonic waves, and this was used as a surface roughening agent B.

Other than that, A is mixed into B in the same manner as in Example 3,
An organic electrophotographic light-sensitive material was obtained in the same manner as in Example 1.

Claims (1)

[Claims] 1. Organic electrophotography characterized in that a roughening agent obtained by mixing low molecular weight polyethylene and silicon oxide fine powder is dispersed in an electrophotographic photosensitive layer using an organic photoconductor on a support. Photosensitive materials for use.