JPH04145446A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To obtain a sensitive body hardly causing dark attenuation, nearly maintaining development contrast and having superior electrostatic chargeability, low residual potential and superior durability by forming an underlayer contg. Zr and Si in a specified ratio. CONSTITUTION:An underlayer is formed on an electrically conductive substrate. This underlayer is a coating film of an inorg. high molecular material contg. Zr and Si and the Si content is 5-25mol% of the total Zr and Si content. The coating film is formed by applying and hardening a soln. contg. a Zr compd. and a silane coupling agent. A photosensitive layer having a single-layer or laminated structure is then formed on the underlayer.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to an electrophotographic photoreceptor comprising a conductive substrate, an undercoat layer and a photosensitive layer, and in particular an electrophotographic photoreceptor having an improved undercoat layer. Regarding the body.

(Prior Art) Electrophotographic copying machines are becoming faster and faster year by year, and machines that can copy a variety of paper sizes are being developed. Along with this, there is a demand for photoreceptors with high photosensitivity and long life to meet these demands.

In addition, in recent years, functionally separated electrophotographic photoreceptors in which photoreceptor functions are shared among multiple members have been developed to improve electrophotographic properties such as charge retention characteristics, cyclic stability, photoresponsiveness, spectral characteristics, and mechanical strength. Many have been proposed.

The drawbacks of these electrophotographic photoreceptors include: (1) lack of repeated development contrast stability and environmental stability;
■ Image defects called white spots, black spots, rough spots, pinholes, etc. are likely to occur; ■ The adhesive strength between the substrate and the photosensitive layer is low, and the photosensitive layer peels off during use, resulting in insufficient durability. It was known that there were some.

As a measure to solve these problems, attempts have been made to provide a resin layer between the substrate and the photosensitive layer.

Examples of the resin include polyparaxylene, casein, polyvinyl alcohol, and phenol). , polyvinyl acetal resin, melamine resin, nitrocellulose, ethylene-acrylic acid copolymer, polyamide (nylon 6, nylon 6G, nylon 610, copolymerized nylon, alkoxymethylated nylon, etc.), polyurethane, gelatin,
It is known to use polyvinylpyrrolidone, polyvinylpyridine, polyvinylmethyl ether, and the like.

Various proposals have also been made to form the intermediate layer using organic zirconium compounds such as carbon dioxide, zirconium chelate compounds, and zirconium alkoxides, and silane coupling agents. (For example, JP-A-59-223439, JP-A-61-94057, JP-A-62-273549).

(Problem to be Solved by the Invention) By the way, when providing a resin layer as an undercoat layer, the volume resistance can be kept low to the extent that the electrophotographic properties are not deteriorated by using a resin containing a relatively large amount of polar groups as the main layer. However, the volume resistivity of the resin is strongly dependent on ionic conductivity and is therefore significantly affected by temperature and humidity.
Alternatively, when placed under high temperature and high humidity, the resin layer may become extremely high in resistance, resulting in deterioration of the electrophotographic properties of the photosensitive layer, or the resin layer may become extremely low in resistance, resulting in the failure of the intended resin layer. function may be lost.

Therefore, in the conventionally known resin layer, only a part of the drawbacks of the photoreceptor can be improved, or if environmental characteristics are included, the effect is halved, and it is technically extremely insufficient.

On the other hand, when an organic zirconium compound or a silane coupling agent is used, the above-mentioned problems are considerably improved, but there is a problem that development contrast decreases due to an increase in residual potential. When a zirconium chelate compound is used, the thermosetting reactivity is insufficient, and when a zirconium alkoxide or silane coupling agent is used, the coating solution or coating film formation becomes unstable over time due to hydrolysis. However, it has not always been completely satisfactory, since it has problems such as thickness and disadvantages in the preparation of the intermediate layer.

As described above, in the conventional techniques, the effect of the lower bow layer to eliminate various drawbacks of an electrophotographic photoreceptor is still insufficient, and the characteristics of the photoreceptor are unsatisfactory.

A first object of the present invention is to provide an electrophotographic photoreceptor that has low dark decay, excellent charging characteristics, is less susceptible to deterioration in development contrast, and particularly has a low residual potential.

A second object of the present invention is to provide an electrophotographic photoreceptor in which image quality defects such as white spots, dark spots, roughness, and pinholes are less likely to occur.

A third object of the present invention is to provide an electrophotographic photoreceptor having electrophotographic properties with little environmental fluctuation and excellent durability.

(Means and effects for solving the problem) The present inventors,
As a result of studies, the inventors have found that the above object can be achieved by forming an undercoat layer containing silicon and zirconium in a specific composition ratio, and have completed the present invention.

That is, the present invention provides an electrophotographic photoreceptor comprising a photosensitive layer provided on a conductive substrate via an undercoat layer, wherein the undercoat layer contains zirconium and silicon, and the silicon content is equal to or less than that of zirconium and silicon. It is characterized by being 5 to 25 mol% based on the total weight.

Hereinafter, the present invention will be explained in detail.

In the present invention, known conductive supports can be used. For example, aluminum, stainless steel, etc. can be suitably used.

A subbing layer is formed on the conductive support.

The undercoat layer is a coating film made of an inorganic polymer material containing zirconium and silicon. The coating film made of this inorganic polymer material is formed by applying a solution containing a zirconium compound and a silane coupling agent and curing it. Typical examples include zirconium chelate compounds. Zirconium chelate compounds are described in 3.4.6.
The eight-molecular coordination type is generally used and is represented by the following formula.

M (Z r X14.6.8 ) (wherein M: metal ion or hydrogen ion (valence omitted)
(amino alcohol, glycol, hydroxy acid or amino acid residue) Typical examples include zirconium tetraacetylacetonate, zirconium trilaftate salt, zirconium tetraoxalate salt, zirconium hexafluoro salt, zirconium octafluoro salt, etc. It will be done.

Other examples include zirconium alkoxides. Zirconium alkoxide is represented by the formula % (in the formula, R: alkyl group), and representative examples include zirconium tetraethoxide, zirconium tetrapropoxide, zirconium tetrabutoxide, etc. .

Furthermore, the zirconium compound may be formed from both a chelate component and an alkoxide component. For example, zirconium tributoxyacetylacetonate, zirconium dibutoxybisacetylacetonate,
Examples include zirconium butoxytrisethyl acetoacetate.

Two or more of these zirconium compounds may be used in combination.

Two or more of these zirconium compounds may be used in combination.

Examples of the silane coupling agent include vinyltrichlorosilane, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris-2-methoxyethoxysilane, vinyltriacetoxysilane, γ-glycidoxypropyltrimethoxysilane, and γ-methacryloxypropyltrimethoxysilane. Methoxysilane, γ-aminopropyltriethoxysilane, γ-chloropropyltrimethoxysilane, γ-2-
Aminoethylaminopropyltrimethoxysilane, γ-
Examples include mercaptopropyltrimethoxysilane, γ-ureidopropyltriethoxysilane, and β-3,4-epoxycyclohexylethyltrimethoxysilane.

In the present invention, the mixing ratio of the zirconium compound and the silane coupling agent is set so that the amount of silicon is 5 to 25 mol % based on the total amount of zirconium and silicon in the undercoat layer. The mixing ratio of the zirconium compound and the silane coupling agent in the present invention can be determined based on the weight of each compound when preparing the coating solution.

When the silicon content exceeds the above range, the volume resistance of the undercoat layer increases, causing problems such as an increase in residual potential during repeated use.

Inclusion of a silane coupling agent improves the uniformity of the coating film and its adhesion to the substrate and photosensitive layer, so when forming the undercoat layer, mix the silane coupling agent appropriately to increase the silicon content above the level above. It is necessary to set it within the range of .

In the present invention, the thickness of the undercoat layer is generally 0.01 to 5.
μm1 is preferably set to 0.2 to 2 μm.

In order to form the undercoat layer, it is necessary to prepare a coating solution, and examples of solvents for dissolving the zirconium compound and silane coupling agent include ethanol, methanol, propatool, butanol, etc. Alcohols, aromatic hydrocarbons such as toluene, and esters such as ethyl acetate and cellosolve acetate can be used alone or in combination.

When applying the coating liquid, for example, dip coating method, spray coating method, blade coating method,
Oating methods such as spinner coating method, bead coating method, curtain coating method, etc. can be used, and drying is carried out at 10 to 250°C, preferably 120 to 250°C.
The drying can be carried out by blow drying or static drying at a temperature in the range of 00°C for 5 minutes to 5 hours, preferably 10 minutes to 2 hours.

A photosensitive layer is provided on the subbing layer, and the photosensitive layer may have a single layer structure or a laminated structure. Examples of the single-layer structure include a dye-sensitized ZnO photosensitive layer, a CdS photosensitive layer, and a photosensitive layer in which a charge-generating substance is dispersed in a charge-transporting substance.

Further, in the case of a laminated structure, there may be one in which a charge generation layer and a charge transport layer are separated in function. The charge generation layer and the charge transport layer may be stacked on the conductive substrate in any order.

The charge generation layer is formed by dispersing a charge generation material in a binder resin as required. Examples of charge generating substances include selenium and selenium alloys; CdS, Cd5eSCdS
Inorganic photoconductors such as Se, ZnO and ZnS; metal or non-metallic phthalocyanine pigments; azo pigments such as bisazo pigments and trisazo pigments; squareium compounds; azulenium compounds; perylene pigments; indigo pigments; quinacridone pigments; polycyclic quinones Pigments; cyanine dyes; xanthine dyes; charge transfer complexes made of poly-N-vinylcarbazole and trinitrofluorenone; and eutectic complexes made of pyrylium salt dyes and polycarbonate resins.

Examples of the binder resin include well-known ones such as polycarbonate, polystyrene, polyester, polyvinyl butyral, methacrylic acid ester polymer or copolymer, vinyl acetate polymer or copolymer, cellulose ester or ether, polybutadiene, polyurethane, and epoxy resin. Resin etc. are used.

The charge transport layer is composed mainly of a charge transport substance. As a charge transport material, it is transparent to visible light,
And, there is no particular restriction as long as it has charge transport ability, and specifically, imidazole, pyrazoline, thiazole, oxadiazole, oxazole, hydrazine, ketazine, azine, carbazole, polyvinylcarbazole, etc. derivatives, triphenylamine derivatives, stilbene derivatives, benzidine derivatives, etc. A binder resin is used in combination as necessary, but
Examples of the binder resin include polycarbonate, polyarylate, polyester, polystyrene, styrene-acrylonitrile copolymer, polysulfone, polymethacrylate, and styrene-methacrylate copolymer.

(Example) Hereinafter, the present invention will be explained in more detail with reference to Examples.

Example 1 A coating solution for forming an undercoat layer was prepared containing the following components.

Zirconium tetraacetylacetonate (XC15G
, ■Matsumoto Bunbu) 10 parts by weight γ-(2-aminoethyl)aminopropyltrimethodixylan (SH602G).

(manufactured by Toray Silicone ■) 0.5 parts by weight Methyl alcohol 75 parts by weight n-butyl alcohol 25 parts by weight This coating solution was applied onto an aluminum pipe by dip coating method,
It was dried by heating at .degree. C. for 10 minutes to form a subbing layer with a thickness of 0.1 .mu.m.

Next, 87 parts by weight of granular trigonal selenium and vinyl chloride-
A solution of 13 parts by weight of vinyl acetate copolymer (trade name: Solution Vinyl VMC [manufactured by Union Carbide Co., Ltd.] dissolved in 200 parts by weight of n-butyl acetate,
Dispersion treatment was performed for 24 hours using an attritor.

Next, acetic acid n-
It was diluted by adding 57 parts by weight of butyl to obtain a dip coating solution.

Using this dip coating solution, the undercoat layer on the aluminum pipe was dip coated and dried by heating at 100° C. for 5 minutes to form a charge generation layer with a thickness of about 0.1 μm.

Next, N, N'-diphenyl-N, N'-bis(
3-methylphenyl)-[1,1'-biphenyl]-4
．． 10 parts by weight of 4' diamine, 1 part of polycarbonate Z resin
A coating solution for forming a charge transport layer was prepared by dissolving 0 parts by weight in 80 parts by weight of monochlorobenzene. This coating liquid was applied onto the charge generation layer and dried with hot air at 100° C. for 60 minutes to form a charge transport layer with a thickness of 25 μm.

The electrophotographic photoreceptor manufactured in this way is used in a copying machine (F
X5G30 modified machine, manufactured by Fuji Xerox), and after adjusting the dark potential VD to 1800V
The bright area potential VL was measured when exposure of egg /ad was applied. Thereafter, an endurance test of 1,000 copies was conducted, and changes in the dark potential VD and the bright potential VL were measured.

At the same time, image quality was evaluated. The results are shown in Table 1 below.

Example 2 Example 1 except that the mixing ratio of zirconium tetraacetylacetonate and γ(2-aminoethyl)aminopropyltrimethodixylan was 3:1 (molar ratio).
An electrophotographic photoreceptor was manufactured in the same manner as above, and evaluated in the same manner. The results are shown in Table 1 below.

Comparative Example 1 An electrophotographic photoreceptor was prepared in the same manner as in Example 1, except that the mixing ratio of zirconium tetraacetylacetonate and γ(2-aminoethyl)aminopropyltrimethodixylan was 2.1 (molar ratio). was manufactured and evaluated in the same manner. The results are shown in Table 1 below.

Comparative Example 2 An electrophotographic photoreceptor was prepared in the same manner as in Example 1, except that the mixing ratio of zirconium tetraacetylacetonate and γ(2-aminoethyl)aminopropyltrimethodixylan was 1.1 (molar ratio). was manufactured and evaluated in the same manner. The results are shown in Table 1 below.

Example 3 An electrophotographic photoreceptor was produced in the same manner as in Example 1, except that the coating liquid for forming the undercoat layer had the following composition, and was evaluated in the same manner. The results are shown in Table 1 below.

Tributoxyzirconium acetyl 10 parts by weight Acetonate 50wt% solution (ZC540, manufactured by Matsumoto Bunkata) γ-Aminopropyltrimethoxysilane (AIIIO,
Made by Nippon Unicar ■ 0.24 parts by weight ethyl alcohol
75 parts by weight n-butyl alcohol
25 parts by weight Example 4 Tributoxyzirconium acetylacetonate and γ
-The mixing ratio with aminopropyltrimethoxysilane is 3
An electrophotographic photoreceptor was produced in the same manner as in Example 3, except that the molar ratio was set to 1 (molar ratio), and evaluation was performed in the same manner. The results are shown in Table 1 below.

Comparative Example 3 Tributoxyzirconium φ acetylacetonate and γ
-The mixing ratio with aminopropyltrimethoxysilane is l
:1 (molar ratio), an electrophotographic photoreceptor was produced in the same manner as in Example 3, and evaluated in the same manner. The results are shown in Table 1 below.

Comparative Example 4 Example 3 except that no silane coupling agent was used.
An electrophotographic photoreceptor was manufactured in the same manner as above, and evaluated in the same manner. The results are shown in Table 1 below.

Table 1 Umbrella 1) Both the literature density and white background fog were stable, and clear copies were obtained.

02) Fog started to appear on the images after copying about 10,000 copies.

Kasako) After about 10,000 copies, peeling of the paint film and black spots began to appear on the images.

(Effects of the Invention) Since the electrophotographic photoreceptor of the present invention is provided with an undercoat layer containing zirconium and silicon in a predetermined ratio as described above,
It has electrophotographic properties with little dark decay, excellent charging properties, low development contrast, low residual potential, and excellent durability with little environmental fluctuation. Therefore, when a large number of sheets are continuously copied, the electrophotographic characteristics are stable, and excellent images without image quality defects such as white spots, black spots, rough spots, pinholes, etc. can be stably obtained.

Applicant: Fujitsu Xerox Co., Ltd.

Claims (1)

[Claims] (1) In an electrophotographic photoreceptor in which a photosensitive layer is provided on a conductive substrate via a subbing layer, the subbing layer contains zirconium and silicon, and the silicon content is equal to the total amount of zirconium and silicon. An electrophotographic photoreceptor characterized in that the content thereof is 5 to 25 mol %.