JPH03200974A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To obtain the electrophotographic sensitive body having a surface protective layer which has the high bondability to a photosensitive layer and has excellent mechanical strength and a better electrical conductivity by applying specific oligomer and any of a coating liquid (1), coating liquid (2) and coating liquid (3) which are respectively specific on the photosensitive layer and curing the coatings. CONSTITUTION:The oligomer expressed by formulas I and II and any of the coating liquid (1) contg. methyl etherified melamine formaldehyde resin at 0.1 to 15 pts. wt. per 100 pts.wt. this oligomer the coating liquid (2) contg. an acrylic polymer at 0.1 to 30 pts. wt. per 100 pts. wt. the oligomer and the coating liquid (3) contg. a specific thermoplastic resin are applied on the photosensitive layer and are cured. In the formulas I, II, R<1> denotes <=6C alkylene group; R<2> denotes <=4C alkyl group; R<3> denotes a group expressed by -OR<2> or <=4C alkyl group. The electrophotographic sensitive body having the surface protective layer which has the high bondability to the photosensitive layer and has the excellent mechanical strength and the better electrical conductivity is obtd. in this way.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to an electrophotographic photoreceptor, and more specifically,
The present invention relates to an electrophotographic photoreceptor having a surface protective layer that has good binding properties with a photosensitive layer and high mechanical strength.

<Prior Art> In image forming apparatuses such as copying machines that utilize the so-called Carlson process, electrophotographic photoreceptors are used in which a photosensitive layer is formed on a conductive base material.

Electrophotographic photoreceptors are repeatedly subjected to electrical, optical, and mechanical shocks during image formation, so organic photoreceptors in particular are subject to improvements in mechanical strength, charging ability, and stain resistance, as well as improvements that are harmful to the photoreceptor. A surface protective layer is provided on a photosensitive layer for the purpose of blocking light and the like.

As such a surface protective layer, silicone resin is mainly used because of its high physical stability and hardness.

<Problem to be solved by the invention> However, since the silicone resin conventionally used has too high hardness, the surface protective layer using this resin has a problem of poor impact resistance and easy cracking. there were. Further, the silicone resin has a problem of poor binding with the photosensitive layer.

Therefore, an electrophotographic photoreceptor using a thermosetting silicone resin and a thermoplastic resin such as polyvinyl acetate as a binder resin for the surface protective layer (see Japanese Patent Laid-Open No. 6318354,
(hereinafter referred to as combination system 1), an electrophotographic photoreceptor using a combination of thermosetting silicone resin and butyl etherified melamine formaldehyde resin (see JP-A No. 63-2071,
(hereinafter referred to as combination system 2), electrophotographic photoreceptor using a combination of thermosetting silicone resin and acrylic polymer (JP-A-60
(See Japanese Patent Publication No. 3639, hereinafter referred to as combination system 3), etc. have been proposed.

However, in combination system 1, the sensitivity of the photoreceptor is not sufficient, and the surface hardness is lower than in the case of thermosetting silicone resin alone, and the physical properties of the surface protective layer such as 1, which are more susceptible to damage. In addition, especially in systems that use polyvinyl acetate in combination with thermosetting silicone resin, the coating solution used to form the surface protective layer lacks stability, resulting in whitening of the film after the pot life. There was also the problem.

On the other hand, in combination system 2, the resins constituting the system are all thermosetting resins that form a three-dimensional structure with high hardness when cured, so the formed surface protective layer has a high surface hardness. , because the compatibility between the silicone site and the melamine site in the layer is not sufficient, many voids that become structural traps are created between the two sites, resulting in deterioration of charging characteristics and potential loss when repeatedly exposed to light. There was a risk that the photosensitive characteristics of the electrophotographic photoreceptor would be adversely affected, such as a decrease in the stability of the electrophotographic photoreceptor.

In addition, Combination System 3 uses an acrylic polymer that has excellent optical properties and is more compatible with thermosetting silicone resin than polyvinyl acetate, so it has improved photosensitive characteristics compared to Combination System 2. can do. However, the acrylic polymer in combination system 3 has an average molecular weight of 8
Since it has a high molecular weight of 000 to 60,000, it is difficult to dissolve it in the coating liquid. Therefore, if the above-mentioned acrylic polymer is insufficiently dissolved in the coating solution, a uniform layer cannot be formed, unevenness, cloudiness, etc. occur, and the transparency of the surface protective layer deteriorates. There have been problems in that the photosensitive properties of the film deteriorate, or the strength of the surface protective layer decreases, making it brittle against sliding friction and prone to cracking.

According to the studies of the present inventors, instead of the butyl etherified melamine formaldehyde resin, methyl etherified melamine formaldehyde resin or methyl-butyl mixed etherified melamine formaldehyde resin (hereinafter, the above two are collectively referred to as "specific etherified melamine formaldehyde resin") has been found. In a combination system using a formaldehyde resin), the above-mentioned specific etherified melamine formaldehyde resin has higher crosslinking properties than the conventional butyl etherified melamine formaldehyde resin, and when cured, the S of the thermosetting silicone resin
Although it does not covalently bond with the i-OH group, the above S
It was found that because a sufficiently large molecular interaction occurs with the i-OH group, the compatibility between the silicone site and the melamine site in the layer is improved, and a dense film with few structural traps can be formed. . However, in the above combination system, in order to improve the conductivity of the layer by the aromatic π electrons of melamine, methyl etherified melamine formaldehyde resin is added to 100 parts by weight of the non-volatile solid content of the thermosetting silicone resin. 15 parts by weight, methyl
In the case of butyl mixed etherified melamine formaldehyde resin, if it is blended in an amount exceeding 30 parts by weight, the interaction with the thermosetting silicone resin is too strong, causing internal stress in the surface protective layer and causing cracks, etc. There was a problem.

This invention was made to solve these problems, and it has strong binding properties with the photosensitive layer and excellent mechanical strength, and also has a negative effect on the photosensitive characteristics, physical properties, etc. of the electrophotographic photoreceptor. It is an object of the present invention to provide an electrophotographic photoreceptor having a surface protective layer that is free from electrical conductivity and has more excellent conductivity.

Means and Effects for Solving the Problems In order to solve the above problems, the electrophotographic photoreceptor of the present invention comprises at least one of the alkoxysilane compounds represented by the following shells (1) and (II). and a coating liquid (1) containing methyl etherified melamine formaldehyde resin in an amount of 0.1 to 15 parts by weight per 100 parts by weight of the oligomer, and 0.1 to 30 parts by weight per 100 parts by weight of the oligomer. A coating solution containing an acrylic polymer having an average molecular weight of 6,000 parts or less (2), or 5 to 50 parts by weight per 100 parts by weight of the oligomer.
Contains parts by weight of methyl etherified melamine formaldehyde resin and/or methyl-butyl mixed etherified melamine formaldehyde resin and 1 to 11% by weight of thermoplastic resin based on the total amount of the oligomer and etherified melamine formaldehyde resin. Coating liquid (3
) is coated on the photosensitive layer and cured to form a surface protective layer.

(Formula (1), (In IIl, R1 is an alkylene group having 6 or less carbon atoms, R2 is an alkyl group having 4 or less carbon atoms, and R3 is a group represented by 10R2 or an alkyl group having 4 or less carbon atoms. In the surface protective layer, conductive metal oxide fine particles as a conductivity imparting agent are mixed into the coating liquids (1), (2) and (3), so that the conductive metal oxide fine particles are uniformly distributed. It is preferable that the conductive metal oxide fine particles be dispersed in a colloidal solution.

In addition, the above etherified melamine formaldehyde resin is
The number average molecular weight is preferably 1500 or less, and the thermoplastic resin is preferably polyvinyl acetate and/or polymethyl methacrylate.

In the electrophotographic photoreceptor of the present invention having the above structure, since the oligomer made of the alkoxysilane compound represented by the formulas (I) and (II) is used as the thermosetting silicone resin, the resulting surface The protective layer has excellent adhesiveness and mechanical strength (abrasion resistance, etc.). The adhesion of the coating film can be improved by coating liquids (1), (2) and <3) contained in the structure of the oligomer when coating the photosensitive layer and curing to form a surface protective layer.
This is thought to be caused by the fact that the hydroxyl group formed by ring opening of the epoxy group forms a covalent bond or hydrogen bond with a polar group such as an amino group or hydroxyl group present on the surface of the photosensitive layer.

Next, the cases where each coating liquid (1), (2) and (3) are used will be described.

When coating liquid (1) is used, the methyl etherified melamine formaldehyde resin contained in the coating liquid (1) has higher crosslinking properties than the conventional butyl etherified melamine formaldehyde resin, and when cured, the 5i- Although it does not form a covalent bond with the OH group, a sufficiently large molecular interaction occurs with the 5i-OH group, improving the compatibility between the silicone site and the melamine site in the layer, and eliminating structural traps. A less dense film is formed.

The content of the methyl etherified melamine formaldehyde resin is 0.1 to 15 parts by weight based on 100 parts by weight of the alkoxysilane compound oligomer in the coating liquid (1).
The reason why it is limited to parts by weight is as follows. That is, if the content of the methyl etherified melamine formaldehyde resin is less than 0.1 part by weight, the effect of adding the methyl etherified melamine formaldehyde resin cannot be sufficiently obtained, and the surface protective layer after curing becomes brittle against sliding friction. In addition to the above problems, the photosensitive characteristics deteriorate due to a lack of aromatic π electrons in the layer. On the other hand, if the content of the methyl etherified melamine formaldehyde resin exceeds 15 parts by weight, the interaction between the two resins will be too strong, causing internal stress in the surface protective layer and cracks, etc., resulting in a clean surface protective layer. will not be obtained.

Methyl etherified melamine formaldehyde resin can be produced by dissolving melamine in methyl alcohol and dropping formaldehyde thereto to perform an addition reaction and methyl etherification reaction, or by dissolving melamine and formaldehyde in methyl alcohol and adding this solution. It is produced by a method of heating addition reaction and methyl etherification reaction, etc., and some or all of the methylol groups in mono- or hexamethylolmelamine, which is a reaction product of melamine and formaldehyde, are methyl etherified. or its initial condensation reaction product, and those supplied in a liquid or syrup state are preferably used.

The number average molecular weight of the methyl etherified melamine formaldehyde resin is not particularly limited in this invention, but is 150
If it exceeds 0, the reactivity decreases, so the number average molecular weight is preferably 1,500 or less. Further, in the above-mentioned methyl etherified melamine formaldehyde resin, the number of bound formaldehydes per melamine nucleus is 3 to 6, and it is preferable that 3 to 6 of them are methyl etherified. If the number of bound formaldehydes per melamine nucleus is less than 3, the surface protective layer may have poor mechanical strength.

Furthermore, if the number of formaldehydes methylated is less than three, the coating solution for the surface protective layer may lack stability.

When using coating liquid (2), the average molecular weight of the acrylic polymer contained in coating liquid (2) is as small as 6,000 or less, so it is easier to dissolve in the coating liquid than conventional ones. The surface protective layer formed is uniform and has excellent optical properties and physical properties.

The reason why the content of the acrylic polymer is limited to 0.1 to 30 parts by weight based on 100 parts by weight of the alkoxysilane compound oligomer in the coating solution (2) is as follows. If the content of the acrylic polymer is less than 0.1 part by weight, the effect of adding the acrylic polymer will not be sufficiently obtained, and the surface protective layer after curing will have physical properties such as cracks and brittleness against sliding friction. On the other hand, if the content of the acrylic polymer exceeds 30 parts by weight, it becomes difficult to dissolve in the coating solution, causing unevenness, and the transparency of the surface protective layer deteriorates, resulting in damage to the photoreceptor. The photosensitive properties deteriorate.Therefore, the content of the acrylic polymer is 0.1 to 1.
More preferably, the amount is 5 parts by weight.

Examples of the acrylic polymer include homopolymers and copolymers made of acrylic monomers such as methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, butyl acrylate, and butyl methacrylate. The reason why the average molecular weight of the acrylic polymer is limited to 6000 or less is that if the average molecular weight exceeds 6000, the solubility in the coating liquid decreases, making it impossible to form a uniform film. It is from.

When the coating liquid (3) is used, the function of the specific etherified melamine formaldehyde resin contained in the coating liquid (3) is the same as that of the coating liquid (1) described above.

Further, as described above, since both resins forming the layer form a three-dimensional structure upon curing, the surface protective layer after curing has a high surface hardness.

Moreover, as mentioned above, both resins are highly compatible, and the three-dimensional structure after curing becomes a complex one, and together with the elasticity provided by the thermoplastic resin, the oligomer of the alkoxysilane compound ( Compared to the case where thermosetting silicone resin is used alone, the brittleness against sliding friction, etc. is improved.

Among the specified etherified melamine formaldehyde resins,
The methyl-butyl mixed etherified melamine formaldehyde resin is a mono- or hexa-methylol melamine in which at least one of the methylol groups is methyl etherified and at least one of the remaining methylol groups is butyl etherified, or an initial condensation reaction product thereof. Similarly, those supplied in the form of liquid or syrup are preferably used.

The number average molecular weight of the methyl-butyl mixed etherified melamine formaldehyde resin is not particularly limited in the present invention, but if it exceeds 1,500, the reactivity decreases, so the number average molecular weight is preferably 1,500 or less. Further, it is preferable that the number of bound formaldehydes per melamine nucleus in the resin is 3 to 6, of which 2 to 5 are methyl etherified and 1 to 2 are butyl etherified. If the number of bound formaldehydes per melamine nucleus is less than 3, the surface protective layer may have poor mechanical strength.

Furthermore, if the number of methyl etherified formaldehydes is less than 2, the surface potential will decrease significantly due to repeated exposure, and if it exceeds 5, cracks may easily occur. Furthermore, if the number of butyl etherified particles is less than one, cracks are likely to occur, and if it exceeds three, there is a risk that the surface potential will decrease significantly due to repeated exposure.

In addition, oligomer 100 of the alkoxysilane compound
The content of the specific etherified melamine formaldehyde resin is within the range of 5 to 50 parts by weight, and the content of the thermoplastic resin is 1 to 11% by weight of the total amount of the oligomer and the specific etherified melamine formaldehyde resin. The reason why each is limited within the range of is as follows. In other words, if the content of the specific etherified melamine formaldehyde resin is less than 5 parts by weight, problems such as brittleness against sliding friction will occur in the surface protective layer after curing, regardless of the content ratio of the thermoplastic resin, and problems will occur in the layer. Due to the lack of aromatic π electrons, the photosensitive characteristics deteriorate.

On the other hand, if the content of the specific etherified melamine formaldehyde resin exceeds 50 parts by weight, the interaction between the reheat-curable resins will be too strong, causing internal stress in the surface protective layer regardless of the blending ratio of the thermoplastic resin. This causes cracks and the like, making it impossible to obtain a clean surface protective layer.

Note that each of the above-mentioned curable resins can be cured by simply heating without using a catalyst depending on the conditions.
Usually, a catalyst is often used to complete the curing reaction smoothly and uniformly.

As the curing catalyst, various catalysts can be used, such as inorganic acids, organic acids, and alkalis such as amines.

Further, if necessary, a conventionally known curing aid or the like can be used in combination.

The thermoplastic resin acts as a buffer that reduces internal stress in the surface protective layer, so even if a larger amount of the above-mentioned specific etherified melamine formaldehyde resin is incorporated into the layer, there is no risk of cracking, etc. The conductivity of the layer can be further improved by the large amount of aromatic π electrons contained in the resin and the conductivity imparting agent contained in the layer.

Therefore, the electrophotographic photoreceptor of the present invention has excellent photosensitivity.

In addition, if the content of the thermoplastic resin is less than 1% by weight, the higher the content of the specific etherified melamine formaldehyde resin, the more internal stress will occur in the surface protective layer and cracks will occur, making it difficult to obtain a clean surface protective layer. I won't be able to do it.

If the content of the thermoplastic resin exceeds 11% by weight, the surface protective layer will become softened, and the lower the content of the specific etherified melamine formaldehyde resin, the more clouding and deterioration of photosensitive properties will occur.

The thermoplastic resins contained in the surface protective layer together with the above-mentioned both curing resins include, for example, styrene polymers; acrylic polymers; styrene-acrylic copolymers; polyethylene, ethylene-vinyl acetate copolymers, and chlorine. Olefin polymers such as polyethylene, polypropylene, and ionomers; polyvinyl chloride; vinyl chloride-vinyl acetate copolymer; polyvinyl acetate; saturated polyester: polyamide;
Various synthetic resin materials can be used, such as thermoplastic polyurethane resin; polycarbonate; polyarylate; polysulfone; ketone resin; polyvinyl butyral resin: polyether resin, but polyvinyl acetate and acrylic polymers are particularly preferred. Ru.

In systems using polyvinyl acetate as the thermoplastic resin, the flexibility of polyvinyl acetate improves the brittleness of the surface protective layer, improves mechanical strength, and makes it possible to extend the lifespan.

On the other hand, polymethyl methacrylate (
In a system using an acrylic polymer such as PMMA), further photosensitivity can be achieved based on the high optical properties of the acrylic polymer.

In addition, the above polyvinyl acetate and acrylic polymer are
Each can be used alone or both can be used in combination, and it is also possible to mix other thermoplastic resins.

Next, the oligomers as thermosetting silicone resins contained in each of the above coating solutions (1), (2) and (3) will be described.

The oligomer as a thermosetting silicone resin is prepared by treating at least one of the alkoxysilane compounds represented by formulas (1) and (I) with hydrochloric acid, sulfuric acid, It is produced by hydrolysis and condensation using an acid catalyst such as perchloric acid as shown below.

That is, among the alkoxysilane compounds represented by the above-mentioned shells (1) and (1), the alkoxy group is hydrolyzed to form a silanol group (S 1-0H), and these silanol groups or silanol groups and unreacted alkoxy groups are condensed to form an oligomer in which a plurality of alkoxysilane compounds are connected by siloxane bonds (Si-O-3i).

Furthermore, unlike conventional compounds, the alkoxysilane compound has at least three functional groups (i.e., one epoxy group and at least two alkoxy groups), and during the above reaction, the epoxy group is A portion of the oligomer undergoes ring opening and polymerization, resulting in a three-dimensionally expanded structure.

As mentioned above, the alkoxysilane compound is oligomerized by the coating liquid (1), (2) using the alkoxysilane compound represented by the monomer formula (1) and the alkoxysilane compound (1) in an unreacted state. and (3) have low viscosity and cannot be coated, so the main purpose is to increase the viscosity.

If the alkoxysilane compound, which has been oligomerized and has increased viscosity (molecular weight), is diluted with an appropriate solvent to prepare a coating solution with a viscosity suitable for coating, a larger amount of coating solution can be obtained from a predetermined amount of monomer. you can get
Cost reduction becomes possible. Moreover, this coating liquid (1)
, (2) and (3), as mentioned above, already have a three-dimensionally expanded structure;
Compared to the case of obtaining a three-dimensional cured product from conventional mainly linear oligomers, the film-forming property is superior and can be formed easily. The effect of the epoxy group other than the epoxy group on the photosensitive layer as a base has the advantage that it has excellent adhesiveness and mechanical strength (abrasion resistance, etc.).

The degree of polymerization of the oligomer is not particularly limited, but it is appropriate to have a degree of polymerization of about 5 to 10. If the degree of polymerization is smaller than this range, it is not possible to reduce costs by improving the viscosity as described above. , and the film forming properties are poor.
Conversely, when the degree of polymerization is greater than this range, the physical properties of the coating film (
(adhesiveness, mechanical strength, etc.), which are both undesirable.

Improvements in the adhesion and mechanical strength of the surface protective layer as described above can be expected even when a normal acid catalyst such as sulfuric acid is used, but when perchloric acid (HCjO4) is used as the acid catalyst, , oligomers can be made three-dimensional more efficiently,
The above-mentioned perchloric acid is more preferred as the acid catalyst for oligomerization, since the physical properties of the resulting surface protective layer are also improved.

It is appropriate to mix the perchloric acid in a proportion of 0.1 to 3 parts by weight per 100 parts by weight of the alkoxysilane compound in order to obtain stable film-forming properties. In addition, when using the above-mentioned alkoxysilane compound and perchloric acid, the water for hydrolysis is preferably 5 to 20 parts by weight per 100 parts by weight of the alkoxysilane compound in order to obtain a suitable oligomer. .

In addition, various organic solvents can be mentioned as solvents used in the oligomerization reaction, but from the viewpoint of coating film performance and manufacturing cost, coating solutions (1), (2), and (3) described below are recommended.
Formation solvents are preferably used.

In addition, examples of the alkylene group having 6 or less carbon atoms corresponding to R1 in the alkoxysilane compound represented by formula (13, (If)) include methylene, methylmethylene, dimethylmethylene, ethylene, trimethylene, and 1-methyl. trimethylene, 2-methyltrimethylene, 2,2-dimethyltrimethylene, tetramethylene, pentamethylene,
Examples of the alkyl group having 4 or less carbon atoms corresponding to R2 include hexamethylene, methyl, ethyl,
Examples include propyl, isopropyl, butyl, isopropyl, tertiary butyl, and the like.

Examples of solvents for dissolving or dispersing each of the above components to form coating solutions (1), (2) and (3) for the surface protective layer include isopropyl alcohol, aliphatic solvents such as n-hexane, octane, and cyclohexane. Aromatic hydrocarbons such as benzene, toluene, xylene; Halogenated hydrocarbons such as dichloromethane, dichloroethane, carbon tetrachloride, chlorobenzene; Dimethyl ether, diethyl ether, tetrahydrofuran, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol dimethyl ether ethers such as acetone, methyl ethyl ketone, cyclohexanone, etc.; esters such as ethyl acetate, methyl acetate, dimethylformamide; dimethyl sulfoxide, etc. These may be used alone or in combination of two or more. .

The above coating solutions (1), (2) and (3) can be cured by simply heating without using a catalyst depending on the conditions, but usually in order to complete the curing reaction smoothly and uniformly, A catalyst is often used.

As the curing catalyst, various catalysts can be used, such as inorganic acids, organic acids, and alkalis such as amines.

Further, if necessary, a conventionally known curing aid or the like can be used in combination.

Further, it is preferable that a conductivity imparting agent is dispersed in the surface protective layer for the purpose of facilitating charge injection into the lower layer in the image forming process.

Examples of conductivity imparting agents include tin oxide, titanium oxide,
Examples include simple metal oxides such as indium oxide and antimony oxide, and conductive metal oxides such as a solid solution of tin oxide and antimony oxide. Generally, conductive metal oxides are stirred and mixed in the coating solution before curing in the form of fine particles, and are dispersed in the surface protective layer as the coating film hardens; however, in the form of fine particles, they tend to aggregate. Since long stirring is required to uniformly disperse coating liquids (1), (2) and (3), each coating liquid (1) ( It is preferable to mix it into 2) and (3). In the above colloidal solution,
The conductive metal oxide fine particles repel each other due to their own surface charges and prevent agglomeration in the coating solutions (1), (2), and (3), so by stirring and mixing for a short time, It can be uniformly dispersed in each coating liquid (1), (2) and (3).

The method for producing a colloidal solution of conductive metal oxide fine particles is as follows:
The conductivity varies depending on the type of metal oxide. For example, a colloidal solution of antimony pentoxide (Sb2O,) is prepared by mixing anhydrous antimony trioxide and nitric acid, and after heating, it is mixed with α-hydroxycarboxylic acid and N.

A method in which an organic solvent such as N-dimethylformamide (DMF) is added in this order and water as a byproduct is removed by distillation (see JP-A-47-11382),
Hydrogen halides such as hydrogen chloride, monohydric or dihydric alcohols such as ethylene glycol, DMF
A method of adding a hydrophilic organic solvent, such as α-hydroxycarboxylic acid, and dispersing antimony trioxide therein, and oxidizing the mixture with hydrogen peroxide (Japanese Patent Laid-Open No. 52-38
495, JP-A-52-38496), etc.

As a dispersion medium for preparing the above-mentioned antimony pentoxide colloidal solution, so as not to attack the underlying photosensitive layer,
Organic small methyl alcohol, ethyl alcohol,
It is preferable to use alcohols such as n-propyl alcohol, isopropyl alcohol, butyl alcohol.

In addition, in the case of a colloidal solution of a solid solution of tin oxide (Sn02, SnO, etc.) and antimony oxide (Sb20s, 5b203, etc.), for example, as shown in FIG. It can be prepared by, for example, a method of adsorbing silicon oxide particles 2. In the structure shown in FIG. 1, the silicon oxide particles 2 adsorbed on the surface of the solid solution particles 1 come into contact with the dispersion medium to generate OH groups and become negatively charged. The surface is designed to have an electric charge.

The above-mentioned solid solution particles of tin oxide and antimony oxide are usually formed by doping fine particles of tin oxide with antimony, and are not particularly limited, but the content ratio of antimony in the solid solution particles is 0.001 to 30% by weight. %, more preferably 5 to 20% by weight. The content of antimony in the solid solution particles is 0
．． If the amount is less than 0.001% by weight or exceeds 30% by weight, there is a risk that sufficient conductivity may not be obtained.

Further, the particle size of the solid solution particles is not particularly limited, but in the case of a colloidal solution of a solid solution, it is preferably 1 to 100 nm. If the particle size of the solid solution particles is less than lnm, the electrical resistance of the surface protective layer increases, so the amount added increases.
If it exceeds 1100n, dispersion stability may deteriorate.

Although the ratio of silicon oxide to the solid solution particles is not particularly limited, it is preferably 10 parts by weight or less with respect to 100 parts by weight of the solid solution particles. If the ratio of silicon oxide to 100 parts by weight of the solid solution particles exceeds 10 parts by weight, there is a risk that sufficient electrical conductivity will not be obtained.

As the dispersion medium constituting the colloidal solution together with the solid solution particles, as described above, a polar solvent is used to negatively charge silicon oxide, and has particularly good compatibility with the coating solution for the protective layer. Methyl alcohol, ethyl alcohol, n-
Alcohols such as propyl alcohol, isopropyl alcohol, butyl alcohol are preferably used.

The binder resin constituting the surface protective layer may contain thermosetting resins or thermoplastic resins other than those mentioned above, as long as the properties of the film are not impaired.

Other binder resins other than those mentioned above include, for example, curable acrylic resins; alkyd resins; unsaturated polyester resins; diallyl phthalate resins; phenol resins; urea resins; benzoguanamine resins; melamine resins other than specific etherified resins; Coalescence; Acrylic polymer; Styrene-acrylic copolymer; Olefin polymers such as polyethylene, ethylene-vinyl acetate copolymer, chlorinated polyethylene, polypropylene, ionomer; Polyvinyl chloride; Vinyl chloride-vinyl acetate copolymer Polyvinyl acetate; saturated polyester; polyamide; thermoplastic polyurethane resin; polycarbonate: polyarylate; polysulfone; ketone resin; polyvinyl butyral resin; polyether resin.

The surface protective layer may contain conventionally known sensitizers such as terphenyl, halonaphthoquinones, and acenaphthylene; 9-(
Fluorene compounds such as N,N-diphenylhydrazino)fluorene and 9-carbazolyliminofluorene; conductivity imparting agents; amine-based and phenol-based antioxidants;
Anti-degradation agents such as ultraviolet absorbers such as benzophenone;
Various additives such as plasticizers can be included.

The thickness of the surface protective layer is 0.1 to 10 μm, especially 2 to 10 μm.
It is preferably within the range of 5 μm.

Note that this noodle photoreceptor can be constructed using the same materials as the conventional one and have the same structure as the conventional one except for the surface protective layer.

First, the conductive base material will be described.

The conductive base material is formed into an appropriate shape, such as a sheet shape or a drum shape, depending on the mechanism and structure of the image forming apparatus in which the electrophotographic photoreceptor is installed.

Further, the conductive base material may be entirely composed of a conductive material such as metal, or the base material itself may be formed of a structural material that does not have conductivity, and its surface may be imparted with conductivity. .

The conductive materials used in the conductive base material having the former structure include, for example, alumite-treated or untreated aluminum, copper, tin, platinum,
Metal materials such as gold, silver, vanadium, molybdenum, chromium, cadmium, titanium, nickel, palladium, indium, stainless steel, and brass are preferred.

On the other hand, in the latter structure, a thin film made of a conductive material such as the above-mentioned metal, aluminum iodide, tin oxide, or indium oxide is deposited on the surface of a synthetic resin base material or a glass base material using a vacuum evaporation method or A structure in which a film of the above-mentioned metal material is laminated on the surface of the above-mentioned synthetic resin molded product or glass base material, a structure in which a film of the above-mentioned metal material, etc. is laminated on the surface of the above-mentioned synthetic resin molded product or glass base material, etc. Examples include a structure in which a substance that imparts conductivity is injected into the surface.

Note that the conductive base material may be surface-treated with a surface treatment agent such as a silane coupling agent or a titanium coupling agent to improve adhesion to the photosensitive layer, if necessary.

Next, the photosensitive layer formed on the conductive substrate will be described.

The photosensitive layer can be made of a semiconductor material, an organic material, or a composite material thereof and has the following structure.

■ Single-layer photosensitive layer made of semiconductor material.

■ A single-layer organic photosensitive layer containing a charge-generating material and a charge-transporting material in a binder resin.

■ A laminated organic photosensitive layer consisting of a charge generation layer containing a charge generation material in a binder resin and a charge transport layer containing a charge transport material in a binder resin.

(2) A composite photosensitive layer in which a charge generation layer made of a semiconductor material and the organic charge transport layer described above are laminated.

Semiconductor materials that can be used as a charge generation layer in a composite photosensitive layer and can also form a photosensitive layer by themselves include:
For example, amorphous chalcogenides such as a-AS2 Se3 and a-SeAsTe, amorphous selenium (a-
8e) and amorphous silicon (a-Si). The photosensitive layer or charge generation layer made of the above semiconductor material can be formed by a known thin film forming method such as a vacuum deposition method or a glow discharge decomposition method.

Organic or inorganic charge-generating materials used in the charge-generating layer in single-layer or laminated organic photosensitive layers include:
For example, powder of the above-mentioned semiconductor materials; tt-vi group microcrystalline pyrylium salts such as ZnO and CdS; azo compounds;
Bisazo compounds; phthalocyanine compounds; anthanthrone compounds; perylene compounds; indigo compounds; triphenylmethane compounds; thren compounds; toluidine compounds; pyrazoline compounds; quinacridone compounds; pyrrolopyrrole compounds, etc. It will be done. Among the above-exemplified compounds, aluminum phthalocyanine, copper phthalocyanine, metal-free phthalocyanine, oxotitanyl phthalocyanine, etc., which belong to phthalocyanine compounds and have various crystal forms such as α-type, β-type, and γ-type, are preferably used. , the above-mentioned metal-free phthalocyanine and/or oxotitanylphthalocyanine are more preferably used. Note that the charge generating materials described above may be used alone or in combination.

In addition, examples of the charge transporting material contained in the charge transporting layer in the single-layer type or laminated type organic photosensitive layer or the composite type photosensitive layer include tetracyanoethylene, 2,4.7-
Fluorenone compounds such as dolinitro-9-fluorenone; nitrated compounds such as dinitroanthracene; succinic anhydride; maleic anhydride; dibromomaleic anhydride; triphenylmethane compounds; 2.5-di(4-dimethylaminophenyl) - Oxadiazole compounds such as 1,3,4-oxadiazole; Styryl compounds such as 9-(4-diethylaminostyryl)anthracene; Carbazole compounds such as poly-N-vinylcarbazole;
Pyrazoline compounds such as 1-phenyl-3-(p-dimethylaminophenyl)pyrazoline, 4.4', 4'-
) Amine derivatives such as lis(N, N-diphenylamino)triphenylamine; Conjugated unsaturated compounds such as 1.1-bis(4-diethylaminophenyl)-4,4-diphenyl-1,3-butadiene; 4- Hydrazone compounds such as (N,N-diethylamino)benzaldehyde-N,N-diphenylhydrazone; indole compounds, oxazole compounds, isoxazole compounds, thiazole compounds, thiadiazole compounds, imidazole compounds, pyrazole compounds, Examples include nitrogen-containing cyclic compounds such as pyrazoline compounds and triazole compounds: fused polycyclic compounds. The above charge transport materials can also be used alone or in combination. Incidentally, among the above-mentioned charge transport materials, a polymeric material having photoconductivity such as the above-mentioned poly-N-vinylcarbazole can also be used as a binder resin for the photosensitive layer.

In addition, in layers such as the single layer type or laminated type organic photosensitive layer and the charge transport layer in the composite type photosensitive layer, deterioration inhibitors such as the sensitizer, fluorene compound, antioxidant, and ultraviolet absorber, Additives such as plasticizers can be included.

In the single-layer type organic photosensitive layer, the content ratio of the charge generating material to 100 parts by weight of the binder resin is preferably within the range of 2 to 20 parts by weight, particularly within the range of 3 to 15 parts by weight; The content ratio of the charge transport material to 100 parts by weight of the binder resin is within the range of 40 to 200 parts by weight, particularly 50 parts by weight.
It is preferably within the range of 100 parts by weight. If the charge generating material is less than 2 parts by weight, or if the charge transporting material is less than 40 parts by weight, the sensitivity of the photoreceptor will be insufficient or the residual potential will become large; if the charge generating material is more than 20 parts by weight, or , when the charge transport material exceeds 200 parts by weight,
The photoreceptor will not have sufficient wear resistance.

The single-layer type photosensitive layer can be formed to have an appropriate thickness, but it is usually preferably formed within the range of 10 to 50 μm, particularly 15 to 25 μm.

On the other hand, among the layers constituting the laminated organic photosensitive layer, the content ratio of the charge generating material in the charge generating layer to 100 parts by weight of the binder resin is within the range of 5 to 500 parts by weight, particularly 1
It is preferably within the range of 0 to 250 parts by weight. If the charge generation material is less than 5 parts by weight, the charge generation ability is too small;
If the amount exceeds 0.00 parts by weight, the adhesion to other adjacent layers or substrates will decrease.

The thickness of the charge generation layer is 0.01 to 3 μm, especially 0.01 to 3 μm.
It is preferably within the range of 1 to 2 μm.

Further, among the layers constituting the laminated organic photosensitive layer and the composite photosensitive layer, the content ratio of the charge transport material to 100 parts by weight of the binder resin in the charge transport layer is within the range of 10 to 500 parts by weight, particularly It is preferably within the range of 25 to 200 parts by weight. If the amount of the charge transport material is less than 10 parts by weight, the charge transport ability will not be sufficient, and if it exceeds 500 parts by weight, the mechanical strength of the charge transport layer will decrease.

The thickness of the charge transport layer is 2 to 100 μm, particularly 5 to 3 μm.
It is preferably within the range of 0 μm.

The organic layers described above, such as the single layer type or multilayer type organic photosensitive layer, the charge transport layer of the composite type photosensitive layer, and the surface protective layer, are coated with a coating solution for each layer containing the above-mentioned components. These coating solutions can be sequentially coated onto the conductive substrate layer by layer and dried or cured to form a laminate so as to form the above-described layer structure.

In addition, when preparing the above-mentioned coating liquid, various solvents can be used depending on the type of binder resin and the like used. Examples of the solvent include aliphatic hydrocarbons such as n-hexane, octane, and cyclohexane; aromatic hydrocarbons such as benzene, xylene, and toluene; halogenated hydrocarbons such as dichloromethane, carbon tetrachloride, chlorobenzene, and methylene chloride; Alcohols such as methyl alcohol, ethyl alcohol, isopropyl alcohol, allyl alcohol, cyclopentanol, benzyl alcohol, furfuryl alcohol, diacetone alcohol; dimethyl ether, diethyl ether, tetrahydrofuran,
Ethers such as ethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol dimethyl ether; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone; esters such as ethyl acetate, methyl acetate; dimethyl formamide; various solvents such as dimethyl sulfoxide These can be used singly or in combination of two or more. In addition, the above coating liquids (1), (2) and (3)
), in order to improve dispersibility, coatability, etc.
A surfactant, a leveling agent, etc. may be used in combination.

Further, the above coating solutions (1), (2) and (3) can be prepared by conventional methods such as a mixer, a ball mill, a paint shaker, a sand mill, an attritor, an ultrasonic dispersion machine and the like.

(The following is a blank space) <Examples> The present invention will be described in more detail below based on Examples.

Examples 1 to 2.7 to 9 and Comparative Example 3.4 Polyarylate as binder resin (manufactured by Unitika, trade name U-100)
) 100 parts by weight, 4-(N,N-
A charge transporting coating solution was prepared consisting of 100 parts by weight of diethylamino)benzaldehyde-N,N-diphenylhydrazone and 900 parts by weight of methylene chloride (CH2Cl3) as a solvent.
After coating on an aluminum tube with a length of 340 mm, 90
It was heated and dried at ℃ for 30 minutes to form a charge transport layer with a thickness of about 20 μm.

Next, on the charge transport layer, 2.
80 parts by weight of 7-dibromoanthanthrone (manufactured by IC1) and 2 parts by weight of metal-free phthalocyanine (manufactured by BASF)
0 parts by weight, 50 parts by weight of polyvinyl acetate (manufactured by Nippon Gosei Kagaku Co., Ltd., trade name Y5-N) as a binder resin, and 2000 parts by weight of diacetoxyalcohol as a solvent. It was dried by heating at 110° C. for 30 minutes to form a charge generation layer having a thickness of 0.5 μm.

Next, 0.0% perchloric acid is used as an oligomerization catalyst. 1 part by weight, 67 parts by weight of isopropyl alcohol, and 11 parts by weight of water, and while stirring while maintaining the temperature of the mixture at 20 to 25 ° C., an alkoxysilane compound represented by the above formula (1). , 100 parts by weight of 3-glycidoxypropyltrimethoxysilane (manufactured by Chisso Corporation, trade name S-510) was gradually added dropwise, and the mixture was allowed to stand at room temperature for 3 days to obtain an oligomer solution.

Next, 1.8-diazabicyclo[5,4,0]undecene-7 (DBU) as a polycondensation catalyst was added to this solution.
2 parts by weight and 100 parts by weight of the oligomer in the solution,
Methyl etherified melamine formaldehyde resin (manufactured by Mitsui Cyinamide Co., Ltd., trade name: Cymel 370) in the amount shown in Table 1 was blended and stirred for 2 hours to prepare a coating solution for a surface protective layer.

Next, solid solution particles of tin oxide and antimony oxide (containing 10% by weight of antimony and having a particle size of 10 to 20 nm) are added to the coating liquid as a conductivity imparting agent.
A colloidal solution (manufactured by Yasan Kagaku Co., Ltd.), which is negatively charged with 9 parts by weight of silicon oxide particles and dispersed in isopropyl alcohol as a dispersion medium, is added to the resin solid content in the coating solution. , blended into the silicone resin coating liquid at the blending ratio shown in Table 1,
Stir and mix in a ball mill for 1 hour, and then apply the mixture of the coating solution and solid solution particles on the charge generation layer,
This was heated and cured at 110° C. for 2 hours to form a surface protective layer with a thickness of 2.5 μm, thereby producing a drum-shaped electrophotographic photoreceptor having a laminated photosensitive layer.

Examples 3 to 6 Instead of a colloidal solution in which solid solution particles of tin oxide and antimony oxide were dispersed in isopropyl alcohol, a colloidal solution in which fine particles of antimony pentoxide were dispersed in inpropyl alcohol (manufactured by 8 Sankagaku Co., Ltd.) was used. , trade name Suncolloid, solid content 20% by weight) was used, and this colloidal solution was applied to the above silicone resin coating in a proportion shown in Table 1 based on the resin solid content in the coating solution. In the same manner as in Example 1 above, except that it was blended into the liquid,
An electrophotographic photoreceptor was produced.

Example 10 β-(3,4-epoxycyclohexyl)'ethyltrimethoxysilane (nitrogen), which is an alkoxysilane compound represented by the formula (I Manufactured by company, product name S-503
) 1'00 parts by weight was used to obtain an oligomer solution, and an electrophotographic photoreceptor was produced in the same manner as in Example 1 above, except that this oligomer solution was used to produce a coating solution for a surface protective layer. .

Comparative Example 1 An electrophotographic photoreceptor was produced in the same manner as in Example 1 above, except that the methyl etherified melamine formaldehyde resin was not blended.

Comparative Example 2 Instead of methyl etherified melamine formaldehyde resin, polyvinyl acetate (manufactured by Nippon Gosei Kagaku Co., Ltd., trade name Y5-
Example 1 above except that 0.1 part by weight of N) was blended.
An electrophotographic photoreceptor was produced in the same manner.

Comparative Example 5 In place of methyl etherified melamine formaldehyde resin, butyl etherified melamine formaldehyde resin (
An electrophotographic photoreceptor was produced in the same manner as in Example 1, except that 0.1 part by weight of Kneepan 128 (trade name, manufactured by Mitsui Cyinamide Co., Ltd.) was blended.

Comparative Example 6 An electrophotographic photoreceptor was produced in the same manner as in Example 1, except that 100 parts by weight of tetraethoxysilane was added in place of 3-glycidoxypropyltrimethoxysilane.

The following tests were conducted on the electrophotographic photoreceptors produced in the above Examples and Comparative Examples.

Surface Potential Measurement Each of the electrophotographic photoreceptors described above was loaded into an electrostatic copying tester (manufactured by Zientic Co., Ltd., model Zientic Cynthia 30M), and its surface was positively charged to determine the surface potential V r s, p.
, (V) were measured.

Half-decreased exposure measurement Each electrophotographic photoreceptor in the above charged state was exposed to light using a halogen lamp as the exposure light source of the electrostatic copying tester under conditions of an exposure intensity of 0.92 mW/cm2 and an exposure time of 60 msec, The surface potential V, S.

The time required for p to become 1/2 was determined, and the half-reduced exposure amount E 1/2 (1ux-See) was calculated.

Measurement of surface potential change after repeated exposure Each of the above electrophotographic photoreceptors was used in a copying machine (manufactured by Sanda Kogyo Co., Ltd.).

DC-111 model) and after 500 copies were processed, the surface potential was changed to the surface potential after repeated exposure V 2
It was measured as s, p, (V).

Further, from the surface potential measurement value V1s, p, value and the surface potential measurement value V2S, p, value after repeated exposure, the following formula (
The surface potential change value -ΔV (V) was calculated using al.

- ΔV (V) - V2S, p, (V) - V, S, p, (V) - (a) Adhesion measurement For each photoconductor, use a cutter knife to cut 10 strips at 11111 intervals, perpendicular to each other. Make cuts that reach the base material and make 100 base holes of lmm x 1mm.
After pasting Nichiban tape on top of this base layer, it was strongly peeled off upwards 90'' to observe the peeling of the surface protective layer.Then, among the base layers of 1 mm x 1 mm, the number of sheets that did not peel off from the photoreceptor. was recorded.

Abrasion resistance test Each electrophotographic photoreceptor was tested using a drum polishing tester (manufactured by Sanda Kogyo Co., Ltd.)
At the same time, an abrasive test paper (manufactured by Sumira 3'M Co., Ltd., trade name: Imperial Wrapping Film, (aluminum oxide powder with a particle size of 12 μm adhered to the surface) was loaded, and this abrasive test paper was applied to the surface of the photoreceptor with a linear pressure of 10 g/m.
The amount of wear (μm) was measured when the photoreceptor was rotated 100 times while being pressed at a pressure of m.m.

exterior The appearance of the surface protective layer was visually observed.

The above results are shown in Table 1.

(The following is a blank space) From the results in Table 1, it can be seen that the electrophotographic photoreceptors of Examples 1 to 10 all had a greater amount of change in surface potential after repeated exposure than Comparative Example 5, which contained a butyl etherified melamine formaldehyde resin. Noticeably small.

From this, it is predicted that the surface protective layers in Examples 1 to 10 have good compatibility between the silicone sites and the melamine sites in the layer, and are dense films with few structural traps.

Moreover, in Examples 1 to 10, the initial surface potential and the surface potential after repeated exposure are higher than Comparative Example 1 in which no melamine formaldehyde resin was blended. This shows that the combination of methyl etherified melamine formaldehyde resin improves the photosensitivity.

From the results of the abrasion resistance test, the surface protective layers in Examples 1 to 10 were found to have better abrasion resistance than Comparative Example 1, in which no melamine formaldehyde resin was blended, and Comparative Example 2, in which polyvinyl acetate was blended. I understand.

In addition, as the alkoxysilane compound, the formula (I),
In Comparative Example 6 using a material other than that corresponding to (I), cracks occurred in the surface protective layer and peeling of the layer was observed in a considerable portion. On the contrary, Examples 1-1
At No. 0, no cracks or peeling were observed, and from this it can be seen that Examples 1 to 10 are all excellent in the adhesiveness of the surface protective layer.

Furthermore, from the results of Examples 1 to 10 and Comparative Example 3.4, the amount of the methyl etherified melamine formaldehyde resin was outside the range of 0.1 to 15 parts by weight based on 100 parts by weight of the alkoxysilane compound oligomer. It can be seen that a clean film cannot be formed.

Examples 11 to 14 and Comparative Examples 7 and 8 In place of the methyl etherified melamine formaldehyde resin, an acrylic ester-methacrylic ester copolymer (manufactured by Nippon Shokubai Co., Ltd., trade name Aloron 4501, average molecular weight 5000 to 6000) was used. An electrophotographic photoreceptor was produced in the same manner as in Example 1 above, except that a coating solution for a surface protective layer was produced.

Example 15 Instead of a colloidal solution in which solid solution particles of tin oxide and antimony oxide were dispersed in isopropyl alcohol, a colloidal solution in which fine particles of antimony pentoxide were dispersed in isopropyl algol (manufactured by 0 San Kagaku Co., Ltd., trade name) was used. The electrophotographic process was carried out in the same manner as in Example 11, except that 10 parts by weight of this colloid solution was added to the resin solid content in the coating solution. The body was created.

Example 16 Instead of 3-glycidoxypropyltrimethoxysilane, β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane (manufactured by Chisso Corporation), which is an alkoxysilane compound represented by the above formula (I[), was used. , product name S-503)
An electrophotographic photoreceptor was produced in the same manner as in Example 11, except that 100 parts by weight of the oligomer solution was used to obtain an oligomer solution, and this oligomer solution was used to produce a coating solution for a surface protective layer.

Comparative Example 9.10 Acrylic ester with average molecular weight of 5000 to 6000
Instead of methacrylic acid ester copolymer, average molecular weight 5
An electrophotographic photoreceptor was produced in the same manner as in Example 11, except that 5,000 polyacrylate (manufactured by Mitsubishi Rayon Co., Ltd., trade name: DIANAL BR105) was blended.

. Comparative Example 11 An electrophotographic photoreceptor was produced in the same manner as in Example 11, except that 100 parts by weight of tetraethoxysilane was added in place of 3-glycidoxypropyltrimethoxysilane.

The electrophotographic photoreceptors prepared in each of the above Examples and Comparative Examples were subjected to the aforementioned tests of surface potential measurement, half-decrease exposure measurement, surface potential change measurement after repeated exposure, abrasion resistance test, and appearance observation. .

The above results are shown in Table 2.

(Margins below) From the results in Table 2, it can be seen that the electrophotographic photoreceptors of Examples 11 to 16 were all more susceptible to repeated exposure than Comparative Example 9.10, which contained an acrylic polymer with an average molecular weight exceeding 6,000. The amount of subsequent surface potential change is small, and the amount of wear is small.

From this, it can be seen that the surface protective layers in Examples 11 to 16 were uniform and had excellent physical properties and photosensitive characteristics.

Furthermore, from the results of Examples 11 to 16 and Comparative Example 7.8, it was found that the amount of acrylic polymer in the coating solution was 0.
．． It can be seen that if it is less than 1 part by weight, the physical properties of the surface protective layer deteriorate, and if it exceeds 30 parts by weight, the photosensitive characteristics are deteriorated.

In addition, as the alkoxysilane compound, the formula (I),
Comparative example 1 using something other than what corresponds to (l[)
In No. 1, cracks occurred in the surface protective layer, and peeling of the layer was observed in a considerable portion. On the other hand, in Examples 11 to 16, no cracks or peeling were observed.
From this, it can be seen that all of the above Examples 11 to 16 have excellent adhesive properties of the surface protective layer.

Examples 17 to 22 and Comparative Examples 12 to 25 Instead of the methyl etherified melamine formaldehyde resin, a specific etherified melamine formaldehyde resin was used in the amount shown in Table 3, and for the total amount of the oligomer and the specific etherified melamine formaldehyde resin. , and polyvinyl butyral (manufactured by Denki Kagaku Co., Ltd., trade name: Denka Butyral 5000A) in the proportions shown in Table 3, and stirred for 2 hours.
An electrophotographic photoreceptor was produced in the same manner as in Example 1 above, except that a coating solution for a surface protective layer was prepared.

Examples 23 to 26 Instead of a colloidal solution in which solid solution particles of tin oxide and antimony oxide were dispersed in isopropyl alcohol, a colloidal solution in which fine particles of antimony pentoxide were dispersed in isopropyl alcohol (manufactured by 0 San Kagaku Co., Ltd., Using the product name Suncolloid (solid content 20% by weight), the colloid solution was prepared so that the resin solid content (P) in the coating liquid and the solid content (M) in the colloid solution were P:M-100. An electrophotographic photoreceptor was produced in the same manner as in Example 17, except that the silicone resin coating solution was blended in a ratio of :60 (weight ratio).

Examples 27 to 34 A colloidal solution in which solid solution particles of tin oxide and antimony oxide were dispersed in isopropyl alcohol was mixed with the resin solid content (P) in the coating liquid and the solid content (M) in the colloidal solution.
So that P:M-100:60 (weight ratio)
An electrophotographic photoreceptor was produced in the same manner as in Example 17 above, except that it was blended into the silicone resin coating liquid.

The electrophotographic photoreceptors prepared in each of the above Examples and Comparative Examples were subjected to the above-mentioned surface potential measurement, half-decay exposure measurement, abrasion resistance test, and appearance observation.

Example 35 Instead of 3-glycidoxypropyltrimethoxysilane, β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane (manufactured by Chisso Corporation, commercial product), which is an alkoxysilane compound represented by the formula (II1), was used. name S-503)
An electrophotographic photoreceptor was produced in the same manner as in Example 17, except that 100 parts by weight of the oligomer solution was used to obtain an oligomer solution, and this oligomer solution was used to produce a coating solution for a surface protective layer.

Comparative Example 26 An electrophotographic photoreceptor was produced in the same manner as in Example 17 except that melamine formaldehyde resin and thermoplastic resin were not blended.

Comparative Example 27 An electrophotographic photoreceptor was produced in the same manner as in Example 17, except that 100 parts by weight of tetraethoxysilane was added in place of 3-glycidoxypropyltrimethoxysilane.

Examples 36 to 45, Comparative Examples 28 to 45 Instead of polyvinyl butyral, polyvinyl acetate (manufactured by Nippon Gosei Kagaku Co., Ltd., trade name Y5-N) was used in the blending ratio shown in Table 3.
) was used, but an electrophotographic photoreceptor was produced in the same manner as in Example 17 above.

Examples 46 to 49 Instead of a colloidal solution in which solid solution particles of tin oxide and antimony oxide were dispersed in isopropyl alcohol, a colloidal solution in which fine particles of antimony pentoxide were dispersed in isopropyl alcohol (manufactured by Nissan Chemical Co., Ltd., a product) was used. The colloidal solution was prepared so that the resin solid content (P) in the coating liquid and the solid content (M) in the colloidal solution were PGM-100:60 (weight%). An electrophotographic photoreceptor was produced in the same manner as in Example 36 above, except that it was blended into the silicone resin coating liquid so that the ratio was as follows.

Examples 50 to 57 A colloidal solution in which solid solution particles of tin oxide and antimony oxide were dispersed in isopropyl alcohol was mixed with the resin solid content (P) in the coating liquid and the solid content (M) in the colloidal solution.
So that P:M-100:60 (weight ratio)
An electrophotographic photoreceptor was produced in the same manner as in Example 36 above, except that it was blended into the silicone resin coating liquid.

Examples 58 to 6, Comparative Examples 46 to 61 Instead of polyvinyl butyral, an acrylic polymer (manufactured by Mitsubishi Rayon Co., Ltd., trade name BR-
An electrophotographic photoreceptor was produced in the same manner as in Example 17 above, except that Example 105) was used.

Examples 70 to 73 Instead of a colloidal solution in which solid solution particles of tin oxide and antimony oxide were dispersed in isopropyl alcohol, a colloidal solution in which fine particles of antimony pentoxide were dispersed in isopropyl alcohol (manufactured by Nissan Chemical Co., Ltd., a product) was used. The colloidal solution was prepared so that the resin solid content (P) in the coating solution and the solid content (M) in the colloidal solution were PGM-100:60 ( An electrophotographic photoreceptor was produced in the same manner as in Example 58 above, except that the silicone resin coating liquid was blended so as to have the following weight ratio.

Examples 74 to 81 A colloidal solution in which solid solution particles of tin oxide and antimony oxide were dispersed in isopropyl alcohol was mixed with the resin solid content (P) in the coating liquid and the solid content (M) in the colloidal solution.
So that P:M-100:60 (weight ratio)
Other than being blended into the silicone resin coating solution mentioned above,
An electrophotographic photoreceptor was produced in the same manner as in Example 58 above.

The electrophotographic photoreceptors prepared in each of the above Examples and Comparative Examples were subjected to the aforementioned surface potential measurement, half-life exposure measurement, abrasion resistance test, and appearance observation.

The above results are shown in Table 3.

The symbols *1 to *5 shown in Table 3 are as follows.

[*1] MBEMH: Methylbutyl mixed etherified melamine formaldehyde resin (manufactured by Sumitomo Chemical Co., Ltd., trade name Sumimaru M 65B) MEMH: Methyl etherified melamine formaldehyde resin (manufactured by Mitsui Cynamide Co., Ltd., trade name Cymel 370) BEMH Nibutyl etherified melamine formaldehyde Resin (manufactured by Mitsui Cynamid Co., Ltd., trade name Kneepan 128) [*2] PVB: Polyvinyl butyral PVAc: Polyvinyl acetate AC Niacrylic polymer [*3] A: Antimony pentoxide colloidal solution B Solid solution of tin dioxide and antimony oxide Colloidal solution [*4] Could not be measured due to cracks.

[*5 Could not be measured due to cloudiness.

(Left below) From the results in Table 3, it can be seen that in any of the three combination systems using polyvinyl butyral, polyvinyl acetate, and acrylic polymer as thermoplastic resins, the specific ether The content of the etherified melamine formaldehyde resin is within the range of 5 to 50 parts by weight, and the content of the thermoplastic resin is within the range of 1 to 11% by weight of the total amount of the oligomer and the specific etherified melamine formaldehyde resin. Only then can it be possible to produce an electrophotographic photoreceptor that has excellent photosensitive characteristics, physical properties, etc., improved fragility to sliding friction, etc., and has a surface protective layer with even better conductivity. I understand.

Also, when comparing individual strips, the system using polyvinyl acetate as the thermoplastic resin has superior wear resistance compared to other systems.
It can be seen that the system using an acrylic polymer has excellent photosensitive characteristics, such as a half-decreased exposure amount and a small residual potential, compared to other systems.

Comparing Comparative Example 26 with the above-mentioned individual strips, each of the above-mentioned strips has better photosensitive characteristics than the oligomer alone.
It can be seen that it has excellent wear resistance.

In addition, as the alkoxysilane compound, the formula m, (
In Comparative Example 27, which used a material other than the one corresponding to 1), cracks occurred in the surface protective layer and peeling of the layer was observed in a considerable part, but in the examples of monographs, both cracks and peeling were observed. This was not observed at all, and from this fact, it can be seen that the surface protective layer of each of the above-mentioned Examples has excellent adhesion.

Examples 82 and 83 and Comparative Example 62 To the oligomer solution prepared in Example 17, 10 parts by weight of an etherified melamine formaldehyde resin was added to the oligomer solution prepared in Example 17, and 10 parts by weight of an etherified melamine formaldehyde resin was added to the oligomer solution prepared in Example 17. A coating solution for a surface protective layer was prepared by blending 9.09% by weight of an acrylic polymer (manufactured by Mitsubishi Rayon Co., Ltd., trade name BR-105) with respect to the total amount, and the rest was as described in Example 17 above. An electrophotographic photoreceptor was produced in the same manner.

The electrophotographic photoreceptors of the above Examples and Comparative Examples were subjected to the aforementioned tests of surface potential measurement, half-decrease exposure measurement, and observation of appearance and surface potential change measurement after repeated exposure.

The above results are shown in Table 4.

(The following is a blank space) From the results in Table 4, it was found that in systems using butyl etherified melamine formaldehyde resins, which are not included in the specific etherified melamine formaldehyde resins, the photosensitivity properties were significantly deteriorated by repeated exposure.

<Effects of the Invention> Since the electrophotographic photoreceptor of the present invention is constructed as described above, it has high binding properties with the photosensitive layer and excellent mechanical strength, and the photosensitive characteristics of the electrophotographic photoreceptor are improved. , it has a surface protective layer that does not adversely affect physical properties, etc., and has even better conductivity.

In addition, when polyvinyl acetate is used as the thermoplastic resin, the flexibility of polyvinyl acetate improves the brittleness of the surface protective layer, improves mechanical strength, and extends the service life. .

On the other hand, polymethyl methacrylate (
When an acrylic polymer such as PMMA) is used, even higher sensitivity can be achieved based on the high optical properties of the acrylic polymer.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing a state in which the solid solution particles of tin oxide and antimony oxide are charged by adsorbing silicon oxide particles onto the surface of the solid solution particles. 1...Solid solution particles, 2...Silicon oxide particles.

Claims (1)

[Claims] 1. An oligomer consisting of at least one of the alkoxysilane compounds represented by the following general formulas (I) and (II); Coating liquid (1) containing 1 to 15 parts by weight of methyl etherified melamine formaldehyde resin, the oligomer 1
0.00 parts by weight. Coating liquid (2) containing 1 to 30 parts by weight of an acrylic polymer having an average molecular weight of 6000 or less, or 5 to 50 parts by weight of methyl etherified melamine formaldehyde resin and/or methyl-etherified melamine formaldehyde resin and/or methyl- A coating liquid (3) containing a butyl mixed etherified melamine formaldehyde resin and a thermoplastic resin of 1 to 11% by weight based on the total amount of the oligomer and the etherified melamine formaldehyde resin is applied onto the photosensitive layer. An electrophotographic photoreceptor characterized by having a surface protective layer formed by coating and curing. ▲There are mathematical formulas, chemical formulas, tables, etc.▼(I) ▲There are mathematical formulas, chemical formulas, tables, etc.▼(II) (In formulas (I) and (II), R^1 is an alkylene group with 6 or less carbon atoms, R ^2 is an alkyl group having 4 or less carbon atoms, R^
3 represents a group represented by -OR^2 or an alkyl group having 4 or less carbon atoms) 2. Conductive metal oxide fine particles are mixed in the coating liquids (1), (2) and (3). 2. The electrophotographic photoreceptor according to claim 1, wherein the conductive metal oxide fine particles are dispersed in the surface protective layer as a conductivity imparting agent. 3. The electrophotographic photoreceptor according to claim 2, wherein the conductive metal oxide fine particles are used in the form of a colloidal solution and are uniformly dispersed in the surface protective layer. 4. The electrophotographic photoreceptor according to any one of claims 1 to 3, wherein the etherified melamine formaldehyde resin has a number average molecular weight of 1,500 or less. 5. The electrophotographic photoreceptor according to claims 1 to 4, wherein the thermoplastic resin is polyvinyl acetate and/or polymethyl methacrylate.