JPH0344292B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a conductive substrate suitable for electrophotographic photoreceptors.

Prior Art Conventionally, metal substrates typified by aluminum pipes have often been used as conductive substrates for electrophotographic photoreceptors. Furthermore, it is well known to use a conductive film in which a metal such as Al or Ni-Cr is vapor-deposited on a polymer film in order to impart flexibility to the photoreceptor or to reduce costs.

However, although these metal-deposited films have excellent conductivity of 10 ² to ^{10 3} Ω/□,
Poor environmental stability, O ₃ generated due to use and storage in high humidity environments or during electrophotographic processes
Chemical oxidation by oxidation causes a significant decrease in conductivity. Furthermore, due to insufficient adhesion, there were drawbacks such as delamination due to stress caused by running.

As an attempt to improve these issues,
No. 143443, Japanese Patent Publication No. 156604, No. 156604, Japanese Patent Application Publication No. 1987-
No. 11825, etc., but all of these have insufficient conductivity (surface resistance≫10 ⁵ Ω/□) to be used as substrates for electrophotographic photoreceptors, and the carrier generated in the photoconductive layer is It is insufficient to escape to the ground, and therefore, when used as a base material for an electrophotographic photoreceptor, it has the disadvantage that surface charges remain.

Purpose of the Invention The present invention improves the above-mentioned drawbacks of the prior art, and provides a material with a surface resistance as a conductive substrate for electrophotographic photoreceptors.
To obtain a base material having a conductive layer having excellent conductivity of 10 ⁵ Ω/□ or less, not being oxidized even under high humidity, having no temperature/humidity dependence in resistivity, and having excellent adhesiveness. purpose.

Structure of the Invention The present invention provides a conductive layer of a conductive base material for an electrophotographic photoreceptor, which is formed by forming a conductive layer on a support, which is composed of tin oxide as a main component and 2 to 30% by weight of antimony oxide. A layer having a thickness of 2 to 5 μm is formed by dispersing 60 to 80% by weight of a conductive solid solution fine powder having an average particle size of 0.1 μm or less in a binder resin.

In the present invention, the conductive fine powder includes fine particles containing tin oxide and antimony oxide in a single particle;
A solid solution of tin oxide and antimony oxide is particularly suitable.

In this case, the amount of antimony oxide relative to the solid solution is
2 to 30% by weight, especially 10 to 20% by weight are preferred. Under these conditions, the color of the conductive layer becomes pale blue to gray.

When Sb ₂ O ₃ is less than 2% by weight, conductivity is insufficient. On the other hand, the amount of Sb ₂ O ₃ may be more than 30% by weight, but if transparency is also desired, it is preferably used in an amount of 30% by weight or less.

The average particle size of the powder is 0.1μm or less, especially 0.02~0.06μm
m is preferred. If the particle size is 0.02 μm or less, the conductivity tends to deteriorate, and if the particle size is 0.1 μm or more, the surface unevenness of the conductive layer becomes large, and the thickness of the photoconductive layer to be formed on it increases. Because the image becomes uneven, unevenness will appear on the copy.

It is desirable that the material used as the binder resin has excellent mechanical strength, adhesiveness, and solvent resistance. For example, polyester resin, polycarbonate resin, polyurethane resin, epoxy resin, acrylic resin, vinyl chloride-vinyl acetate copolymer, silicone resin, alkyd resin, polyvinyl chloride resin, cyclized butadiene rubber, fluororesin, etc. can be used. In particular, when solvent resistance is required, it is desirable to use a curable resin.

In the present invention, a solvent is used to dissolve the binder resin and disperse the conductive fine particles appropriately.

Solvents used for this conductive layer lacquer include alcohols such as methanol and ethanol, aromatic hydrocarbons such as toluene and xylene, esters, ethers, halogenated hydrocarbons such as methylene chloride and trichloroethane, and cyclohexane. Examples include one or a mixture of aliphatic hydrocarbons such as, but these vary depending on the binder resin, coating method, etc., and are not particularly limited.

To disperse the conductive powder into the binder resin and obtain the fat particle size, use a ball mill, homogenizer,
Dispersing machines such as Attritor and Glenmill are used.

The appropriate thickness of the conductive layer in a dry state is 2 to 5 μm.

The present inventors have discovered that the surface resistivity of an electrophotographic photoreceptor largely depends on the thickness of the conductive layer. That is, as shown in Figure 1, the thickness of the conductive layer is 1μ.
When the thickness is less than m, the surface resistivity increases rapidly, but if the film is too thick, the strength of the conductive layer decreases, causing cracks when stress is applied, and in severe cases, peeling. . Further, when the film thickness is increased, there is also a drawback that the cost of the material increases. Therefore, the film thickness is preferably 2 to 5 μm.

In the case of a film thickness of this level, it has a transmittance of 40 to 60% (wavelength: 550 nm), so it has the advantage that it can also be used for back exposure.

In the present invention, conventional thermoplastic and thermosetting polymeric materials are used as the support on which the conductive layer is applied.

The polymeric substances include those known as oligomers and initial condensates in addition to so-called polymeric substances in the field of ordinary polymer chemistry.

That is, synthetic resins such as addition polymers, ring-opening polymers, and polycondensates involving so-called unsaturated bonds, synthetic fibers, synthetic polymer substances known as synthetic rubber, natural rubber, cellulose, gelatin, proteins,
Examples include natural polymeric substances such as paper and wood, and derivatives thereof.

For example, synthetic polymer substances include olefins, allyl compounds, halogenated olefins, styrenes, heterocyclic vinyls, acetylenes, arenes, butadienes, N-vinyl compounds, vinyl esters, and vinyl ethers. , vinyl ketones, acrylic acids, acrylonitriles, acrylamides, methacrylic acids, oxiranes, lactams, and other monomers alone or in copolymers.

Alternatively, polyimine, polyester, polyether, polycarbonate, polysulfide,
Polysulfone, polysulfonamide, polypeptide, polyamide, polyimide, polyurethane, polyurea, polyanhydride, alkyd resin, unsaturated polyester, epoxy resin, ketone resin, phenolic resin, urea resin, melamine resin, furan resin, xylene resin, There are various types of resins such as thermosetting resins, thermoplastic resins, and hardened resins such as toluene resin, aniline resin, diallyl phthalate resin, and silicone resin.

These resins may be used alone depending on the purpose, but may also be blends, craft polymers, copolymers, block copolymers, etc. of these resins, or mixtures or laminates of these resins.

For these shapes, molded products, films,
It may be thread-like or cylindrical.

These shapes, sizes, compositions, etc. can be changed widely depending on the use, and are not particularly limited.

As a method for applying the conductive lacquer on the support, known coating methods such as a roll coater such as Reverse or Gravure, a wire bar coater, a blade coater, a side press, an air knife, and a spray are used. when drying 2
A conductive layer is formed to have a thickness of ~5 μm.

The photoconductive layer provided on the conductive layer of the present invention may be a vapor deposited film of Se, Se-Te alloy, Se-As alloy, Se-Sb alloy, Se-Bi alloy, or polyvinylcarbazole/trinitrofluorenone (PVK/
An organic photoconductor such as TNF), an inorganic photoconductor such as ZnO or CdS dispersed in a binder resin, or a stack of a charge generation layer and a charge transport layer can be used.

Further, a barrier layer may be provided between the conductive layer and the photoconductive layer, or a barrier material may be added to the conductive layer.

Hereinafter, the conductive substrate for electrophotographic photoreceptors of the present invention will be explained with reference to Examples and Comparative Examples.

Example 1 Tin oxide-antimony oxide solid solution fine powder containing 20% by weight of antimony oxide (average particle size 0.06μ)
m) 55.6 g of acrylic polyol resin (38% solution by weight, trade name, "Rethane Clear" manufactured by Kansai Paint Co., Ltd.) and polyester resin (trade name,
Toyobo “Pylon 200”) 3g and xylene 63
This mixture was dispersed and mixed in a ball mill for 12 hours. After dispersion, 91 g of an isocyanate compound (65% by weight solution, trade name, "Rethane Curing Agent" manufactured by Kansai Paint Co., Ltd.) was added to this mixture to prepare a coating solution.

This was applied onto a 75 μm thick polyethylene terephthalate (PET) film using a dip coater to give a dry film thickness of 3 μm to obtain a conductive base material. When the surface resistance of the conductive layer was measured, it was 1×
It was 10 ⁵ Ω/□. PVK-TNF on this conductive layer
A photoreceptor was provided with a photoconductive layer consisting of (1:1 weight ratio). When this photoreceptor was evaluated by an electrophotographic process, a sufficient contrast potential could be obtained, and no defects were observed on copies. The adhesion of this photoreceptor was evaluated by a tape test method, but no peeling occurred.

In addition, only conductive substrates can be used at 40℃ and humidity (RH).
Although it was left in a 100% environment for 7 days, no change was observed in its surface resistance value.

Example 2 Add binder resin to 70g of conductive powder using polyester resin (trade name, “Pylon 200” manufactured by Toyobo Co., Ltd.)
A conductive base material was obtained in the same manner as in Example 1, except that the amount of the isocyanate compound (trade name, "Coronate L" manufactured by Nippon Polyurethane Co., Ltd.) was 1 g. The surface resistance was 9×10 ⁴ Ω/□. When this was evaluated in the same manner as in Example 1, good results were obtained.

Comparative Example 1 Al was deposited to a thickness of 500 Å on a 75 μm thick PET film to obtain a conductive base material. The surface resistance is 1
It was ×10 ² Ω/□. When this was used as a photoreceptor in the same manner as in Example 1 and the adhesiveness was evaluated by the tape test method, it was found to have peeled off from the Al layer. Also,
When this photoreceptor was left in an environment of 40°C and 95% RH for 3 days, partial oxidation of Al was observed, which appeared as white spot defects on copies.

Comparative Example 2 SnO ₂ fine powder 70 instead of the conductive powder of Example 1
A conductive base material was obtained in the same manner as in Example 1 except that G was used. When this surface resistance was measured, it was 5×
It was 10 ⁷ Ω/□. A photoreceptor was prepared on this conductive base material in the same manner as in Example 1, and evaluated using an electrophotographic process, but a sufficient contrast potential could not be obtained and the copy was pitch black.

Comparative Example 3 A conductive base material was obtained by changing the thickness of the conductive layer of Example 1 to 0.5 μm. This surface resistance was 2×10 ⁶ Ω/□, and when a photoreceptor was prepared from these in the same manner as in Comparative Example 2 and subjected to a copy test, it turned completely black.

Effects of the Invention The present invention supports a conductive layer in which 60 to 80% by weight of a solid solution powder of tin oxide as a main component and 2 to 30% by weight of antimony oxide with an average particle size of 0.1 μm or less is dispersed in a binder resin. It provides a conductive base material for electrophotographic photoreceptors formed on a body, and is transparent and has excellent conductivity (surface resistance) that is independent of temperature and humidity.
10 ⁵ Ω/□ or less), does not oxidize even under high humidity, and has excellent adhesive properties.

[Brief explanation of drawings]

FIG. 1 is a graph showing the relationship between the film layer of the conductive layer and the surface resistivity.

Claims (1)

[Scope of Claims] 1. A conductive base material for an electrophotographic photoreceptor in which a conductive layer is formed on a support, wherein the conductive layer consists of an average of tin oxide as a main component and 2 to 30% by weight of antimony oxide. 1. A conductive substrate comprising a layer having a thickness of 2 to 5 μm and comprising conductive fine powder with a particle size of 0.1 μm or less dispersed in a binder resin in an amount of 60 to 80% by weight.