JPH02168257A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To obtain an electrophotographic sensitive body having improved photosensitive characteristics by using a high molecular binder for charge transfer layer in combination with a charge transfer material. CONSTITUTION:The high molecular binder to be used consists of methyl phenyl siloxane polymer, dimethyl siloxane polymer, methyl phenyl siloxane/org. high molecular compd. copolymer or a mixture thereof, dimethyl siloxane/org. high molecular compd. copolymer or a mixture thereof. Such high molecular compds. have photoconductive characteristics in themselves, and the binders are used as material for a charge transfer layer. Suitable org. compds. to be mixed with the siloxane are alkyd resin, acrylic resin, carbonate resin, polyester resin, and polyimide resin. Thus, the photosensitive characteristics of an electrophotographic sensitive body are improved.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an electrophotographic photoreceptor for forming an image for electrophotography, and more particularly, it relates to a photoreceptor for electrophotography, in which a silicone polymer material having a specific molecular structure is used as a binder. An electrophotographic photoreceptor comprising an organic photoconductor having a charge transport layer containing the photoconductor is flashed.

Conventional technology Organic photoreceptors (abbreviated as OPC) are superior to inorganic photoreceptors in that they can synthesize materials with high sensitivity to various wavelengths through molecular design, are non-polluting, are more productive, and are more economical. It has certain characteristics, and active research and development is currently underway. Significant improvements have also been made in terms of permanence and sensitivity, which were conventionally considered problems of organic photoreceptors, and some of these improvements have been put into practical use, and are now becoming the mainstay of photoreceptors for electrophotography.

OPC is usually used in a double-layered structure consisting of a charge generation layer (CGL) that absorbs light and generates carriers and a charge transfer layer (CTL and cooling) that moves the generated carriers. is planned.

Materials used for CGL include perylene compounds,
Various organic materials such as phthalocyanine thread compounds, thiapyrylium compounds, anthanthrone compounds, squarylium compounds, and bisazo compounds are being investigated.

On the other hand, the materials used for CTL (CTM) are:
Various hydrazone compounds, oxazole compounds, triphenylmethane compounds, arylamine compounds, etc. have been developed.

Furthermore, in recent years, there has been an increasing demand for the use of these organic photoreceptors in the near-infrared region, which corresponds to semiconductor laser light (780-8301m), as photoreceptors for digital recording in laser printers, etc. The development of organic photoreceptors with high sensitivity is currently underway. Organic photoreceptors have an advantage over inorganic photoreceptors in terms of sensitivity, and phthalonanine pigments, trisazo pigments, azulenium dyes, etc. have been developed as charge-generating materials (C()M). There is.

These materials are formed on a substrate such as a drum or belt by a relatively simple coating method together with a binder polymer. Binder polymers used for this purpose include polyester resins, polycarbonate resins, acrylic resins, acrylic-styrene resins, polyvinyl butyral resins, and the like. -Generally, in a double layer structure, C
(]L is applied to a thickness of several microns, while CTL is applied to a thickness of several tens of microns.At this time, for reasons such as strength and printing durability, CGL is applied to the substrate side, and CTL is applied to the surface side. Normally, it is formed as follows.In such a configuration,
Since only those in which c''rM operates by the movement of holes have been put into practical use, the double layer photoreceptor is of a negatively charged type.

Problems to be Solved by the Invention In such a negative band formation method, ozone is generated due to negative charges. Such ozone not only accelerates the deterioration of the photoreceptor through oxidation, but also is harmful to the human body. Further, one of the major problems with OPC is the problem of residual potential. Residual potential accumulates through repeated use and does not completely recover to its initial state even after dark adaptation. Therefore, these are a very big problem for the durability of OPC.

The purpose of the present invention is to solve the above-mentioned drawbacks of OPC materials, and to provide an organic photoreceptor that has high performance, high sensitivity, and durability, and can especially be used in positive charging systems. .

Means for Solving the Problems In order to achieve the above objects, the present invention uses methylphenylsiloxane, dimethylsiloxane, methylphenylsiloxane-organic polymer copolymer, dimethylsiloxane-as a binder for the charge transfer layer of an organic photoreceptor. At least one volatile compound selected from organic polymer copolymers, mixtures of methylphenylsiloxane and organic polymers, and mixtures of dimethylsiloxane and organic molecules is used.

Function: The binder for the polymeric charge transfer layer according to the present invention described above can achieve wide characteristics as a photoreceptor by combining it with an appropriate CTM. Conventional binder resins do not have photoconductive properties by themselves, but the polymer of the present invention itself has photoconductive properties, so high sensitivity is achieved by using this polymer. In particular, it has the great feature of being able to use a positive charging method. Furthermore, since these polymers have film-forming ability, CTLs can be formed without the need for ordinary binder resins. Excellent properties can also be achieved by combining it with various conventional binder resins. moreover,
Since these polymers have high thermal stability, CTLs with excellent durability can be formed.

Example The present invention will be explained in detail below.

In order to solve the above problem, we developed a binder resin for C'l'L, which has not been studied much in the past. As a result, a novel high-performance polymer binder was discovered and the present invention was completed. The polymeric binder according to the present invention is methylphenylsiloxane, dimethylsiloxane, methylphenylsiloxane-organic polymer copolymer or a mixture thereof, dimethylsiloxane-organic polymer copolymer or a mixture thereof. As a result of various studies, it was discovered that this polymer itself has photoconductive properties.
Therefore, it has become clear that the use of these binders in CTL has the effect of improving its photosensitivity properties. More surprisingly, it was found that by using this binder polymer, excellent positive charging characteristics appeared in a two-layer structure in which CTI was laminated on COL. The appearance of positive charging characteristics indicates that the CTL is causing electron movement, and is a new phenomenon that has not been previously known.

Therefore, as a binder for CTL according to this invention,
Use methylphenylsiloxane or dimethylsiloxane. Since it is difficult for i/methylsilochitin to form a good film when used alone, it is generally crosslinked using hydrogen silane or the like, or used in combination with an organic polymer. Methylphenylsiloxane forms good films by itself, but it can also be used in combination with organic polymers.

Examples of organic polymers used in combination with the above siloxane include alkyd resin, acrylic resin, carbonate resin, epoxy resin, melamine formaldehyde resin, urea formaldehyde resin, dioctyl phthalate, ethyl cellulose, phenol resin, rosin-modified phenol resin, and styrenated alkyd. At least one selected from resin, polyester resin, epoxy ester resin, polyimide resin, etc. is preferable, and alkyd resin, acrylic resin, carbonate resin, 4-lyester resin, and polyimide resin are particularly suitable for this purpose. It will be done.

Further, the charge transfer material to be combined with the binder is preferably at least one fit selected from hydrazone compounds, oxazole compounds, triphenylmethane compounds, and arylamine thread compounds, especially hydrazone compounds. is optimal. The conductive support serving as the substrate of the organic photoconductive layer is not particularly limited, and can be appropriately selected depending on the intended use. Specifically, metals such as aluminum, glass, paper, or plastics on which a conductive layer is formed by a method such as metal vapor deposition are preferably used. Moreover, it can take various shapes such as a drum shape, a belt shape, and a sheet shape.

Although the polymer binder for CTL of the present invention can be used in a negative charge mode, it is more effectively used in a positive charge mode. In that case, high sensitivity can be achieved by combining it with the conventionally used αN to create a double layer structure. In this case, the CGL is installed on the substrate side, and the CT of the present invention is placed on top of it.
It has a double layer structure with L.

As the CGM used for this purpose, αN, which is usually used in organic photoreceptors, can be widely used, and there are no particular limitations. For example, compounds (1) to (+4) in FIG. 1 can be exemplified. Among them, the phthalonanines shown in (1) and (2) are preferably used for the purpose of the present invention, and X-type, τ-type metal-free phthalocyanine, and ε-type steel phthalocyanine are particularly optimal.

Moreover, CT which can be used together with the binder of the present invention
As M, various hydrazone compounds, oxazole compounds, triphenylmethane compounds, etc. can be widely used. For example, the compounds shown in FIG. 2 09-0υ can be exemplified as CTMs used for such purposes.

Furthermore, although the polymer binder of the present invention forms an excellent film by itself, it can be combined with various binder polymers to improve its strength and adhesion to COL. For such a composite purpose, a low polymerization type methylphenyl silicone or dimethylsiloxane phase having a silanol type or methoxy group at the end is effectively used.

By combining such materials, for example, a system using methylphenylsiloxane as a binder achieves a maximum sensitivity of 1.7 lux and 5ecO with a half-reduced exposure sensitivity due to positive charging, while a mixed system of methylphenylsiloxane and acrylic achieves a high sensitivity of 5 ecO. ], 9 lux, sec high sensitivity was achieved.

Furthermore, these systems were very stable, with almost no change in their properties even after repeated testing 1000 times.

The electrophotographic photoreceptor according to the present invention described above is
For example, it can be used for various recording systems such as copying machines, printers, and facsimiles, and its use is not limited to the number of tatami mats. It should be noted that the electrophotographic photoreceptor according to the present invention is not limited to the above-mentioned examples, but may include, for example, forming a surface protective layer of an insulating resin on the organic photoreceptor layer as necessary,
It is also possible to provide a blocking layer between the OL and the substrate.

Next, the present invention will be described in more detail with reference to Examples and Comparative Examples.

Example 1 - Type X metal-free phthalocyanine dispersed in dioxane solvent [
Manufactured by Inu Nippon Ink Chemical Industry ■, Fastge 77' Roux (
Fastogen Blue) 8120 B] Bath solution was coated on an aluminum drum by the dip method and treated in vacuum at 140°C for 1 hour to form CC) L (thickness 1-2
ttm) was formed.

Next, add methylphenylsiloxane (Toshiba Silicone ■Shitsu, Silicone Varnish ST 117) and c'IM shown in Figure 2.
H (4-dibenzylamino-2-methylbenzaldehyde-1,1'-diphenylhydrazone: Yanan Perfumery Industry ■
manufactured by CTC-191) in a ratio of 1:2, and
It was applied onto GL to form a CTL coating with a thickness of 15 to 18 μm. The coating film was heat-treated at 150° C. for 1 hour in the air to obtain a photoreceptor with a two-layer structure.

The photosensitive characteristics of each photoconductor obtained in this way were evaluated by Kawaguchi Electric (
Using a Kiki EPA-8100 paper analyzer,
White light from tungsten was irradiated to measure the photosensitivity (half-reduction exposure amount El/2) due to negative charging. Furthermore, 100
The photosensitivity after 0 repeated tests was also measured in the same manner.

As a result, the sensitivity E1/2 due to positive charging was 1.71ux.

sec, and the characteristics after 1000 repeated tests are:
1, g lux, sec. Also, the sensitivity El/2 due to negative charging is 2.01ux, sec, similarly 100
Characteristics after 0 repeated tests are 2.3 lux, sec
Met.

-Comparative Example 1- For comparison, a two-layer structure photoreceptor was prepared with the same configuration as in Example 1 using polyester resin instead of siloxane, and its characteristics were measured.

As a result, the sensitivity 'E 1/2 due to negative charging is 3.3 l
ux.

sec, similarly, the characteristics after 1000 repeated tests are 6
, □ lux, sec, and did not show good sensitivity with positive charging. Therefore, the usefulness of the present invention was proven. Example 2 - Characteristics of methylphenylonloxane-organic polymer copolymer and dimethylsiloxane-organic polymer copolymer in each building.
A photoreceptor with a double layer structure prepared in the same manner as in Example 1 was used for evaluation. The results are shown in Table 1.

These results show that the binder polymer of the present invention exhibits excellent photosensitive properties in both positively charged and negatively charged systems, and particularly shows excellent properties in positively charged states, and also has excellent repeat stability.

Incidentally, it is not necessary that the cylochitin and the organic polymer be made into a copolymer, and the same effect can be obtained by simply mixing or making them into a composite. However, in this case, the sensitivity and repetition stability generally tend to be worse than when a copolymer is used.

Example 3 - A solution consisting of ε-type copper phthalocyanine [Toyo Ink Manufacturing Co., Ltd. (Liophon) ERPC:] dispersed in a solvent and polyvinyl butyral was coated on an aluminum drum to form CGL (thickness 1-2 μm). .

Next, the methylphenylsiloxane-acrylic copolymer and (l-phenyl-1,2,3,4-tetrahydroquinoline-6-carbaldehyde-1,1-diphenyl) of CTh1 in FIG. Hydrazone: C'l'M made by Asan Fragrance Industry (Suriso CTC-236)
It was applied onto GL to form a coating film with a thickness of 15 to 20 μm. The coating film was heat treated in vacuum at 140° C. for 1 hour to obtain a photoreceptor with a two-layer structure. As a result, the sensitivity to positive charge is E
t/2=2. Q lux, sec, characteristics after 1999 repeated tests were 2 and 3 lux, sec, respectively.

Example 4 Using the same method as Example 3, 09 to C in Fig. 2 are used as CTM.
Using the material No. 31), its photosensitive characteristics due to positive charging were measured. The results are shown in Table 2. These results show that the binder polymer of the present invention can be effectively used for various organic compounds (5'λ1).

Table 82 Table 3 Example 5 - Using the same method as Example 4, (3) to (C of +41) in Figure i1
A COL is formed using a GM compound, and a compound ■ is formed on the same layer.
and CTL using methylphenylsiloxane as a binder were laminated to obtain a photoreceptor with a two-layer structure.

Table 3 shows the photosensitive characteristics of each positive charge.

These results revealed that the binder of the present invention is effective for various types of COM.

Effects of the Invention As described above, the electrophotographic photoreceptor according to the present invention has higher sensitivity and excellent stability than conventional photoreceptors. In particular, it has the characteristic that it can be applied to positive charging systems, and is expected to be applied to various recording devices that use electrophotographic photoreceptors.

[Brief explanation of the drawing]

Claims (2)

[Claims] (1) As a binder for the charge transfer layer, methylphenylsiloxane, dimethylsiloxane, methylphenylsiloxane-organic polymer copolymer, dimethylsiloxane-organic polymer copolymer, mixture of methylphenylsiloxane and organic polymer, dimethyl A photoreceptor for electrophotography, characterized in that at least one kind selected from a mixture of siloxane and an organic polymer is used. (2) The organic polymer according to claim 1 is an alkyd resin,
An electrophotographic photoreceptor made of at least one member selected from acrylic resin, carbonate resin, epoxy resin, polyester resin, and polyimide resin.