JPH0677159B2 - Electrophotographic photoreceptor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Field of Industrial Application> The present invention relates to an electrophotographic photoreceptor, and more particularly to an electrophotographic photoreceptor having a surface protective layer.

<Prior Art> In an image forming apparatus such as a copying machine utilizing a so-called Carlson process, an electrophotographic photoreceptor having a photosensitive layer formed on a conductive base material is used.

The electrophotographic photoreceptor is repeatedly subjected to electrical, optical and mechanical shocks during the image forming process, and therefore, for the purpose of improving durability against these shocks, on the photosensitive layer,
A surface protection layer containing a binder resin is laminated.

As the binder resin, a thermosetting resin such as polyurethane resin, epoxy resin, or silicone resin is mainly used in order to improve the hardness of the surface protective layer. However, the thermosetting resin alone is fragile and easily damaged by sliding friction, has insufficient gas barrier properties, and easily passes ozone generated by corona discharge for charging the photoreceptor,
There is a problem that the photosensitive layer is damaged by ozone.

Therefore, an electrophotographic photosensitive member (see JP-A-62-108260) in which a thermosetting silicone resin and a polyvinyl acetal are used together as a binder resin for the surface protective layer, a thermosetting acrylic resin, a thermosetting silicone resin, For thermosetting resins such as epoxy resin, urethane resin, urea resin, phenol resin, polyester resin, alkyd resin, and melamine resin, polypropylene, acrylic resin, methacrylic resin, polyvinyl chloride, polyvinyl acetate, polybutyral, polycarbonate , An electrophotographic photosensitive member (see JP-A-63-18354) in which a thermoplastic resin such as a thermoplastic silicone resin is contained in the solid content of the protective layer in an amount of less than 50% by weight has been proposed. .

<Problems to be Solved by the Invention> However, in the combined system of the conventional thermosetting resin and the thermoplastic resin, the gas barrier property against ozone is not yet sufficient, the transparency of the surface protective layer is not good, heat As compared with the case where the curable resin alone is used, the surface hardness is low, and the surface protective layer is liable to be damaged. Further, in the above combined system, the initial sensitivity is low, and the surface potential is lowered when repeated exposure is performed. In some cases, the residual potential rises and the photosensitive characteristics of the electrophotographic photosensitive member are adversely affected.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a thermosetting resin alone without adversely affecting the sensitivity characteristics, physical properties and the like of an electrophotographic photoreceptor. Another object of the present invention is to provide an electrophotographic photosensitive member having a surface protective layer with improved gas barrier properties, brittleness against sliding friction and the like.

<Means and Actions for Solving the Problems> An electrophotographic photoreceptor according to the present invention (hereinafter referred to as “photoreceptor of the present invention”) for solving the above problems is a surface protective layer containing a thermosetting silicone resin. However, polyvinyl acetate with an average degree of polymerization of 2000 or less is the solid content of the thermosetting silicone resin.
It is characterized by containing 0.1 to 30 parts by weight with respect to 100 parts by weight.

Further, instead of the polyvinyl acetate, a polyamide resin,
Further, one kind of polyvinyl pyridine having an average molecular weight of 10,000 or less may be contained in an amount of 0.1 to 30 parts by weight based on 100 parts by weight of the solid content of the thermosetting silicone resin.

In the photoreceptor of the present invention having the above-mentioned constitution, the above-mentioned three kinds of thermoplastic resins (hereinafter collectively referred to as “thermoplastic resin for the present invention”) are added to 100 parts by weight of the solid content of the thermosetting silicone resin.
Of 0.1) to 0.1 to 30 parts by weight of the thermoplastic resin, the surface protective layer is strong against sliding friction and has high surface hardness, and is excellent in gas barrier property and transparency. It has excellent physical properties.

Further, the photoconductor of the present invention provided with the surface protective layer has excellent initial photosensitivity, such as high initial sensitivity, no decrease in surface potential due to repeated exposure, and low residual potential.

The reason why the photoconductor of the present invention exerts the above remarkable effects is not known at present. As is well known, the combination of a plurality of resin materials, and the relationship between their physical properties, has not been firmly theorized, especially when a thermosetting resin and a thermoplastic resin are combined, There are many unclear points regarding the physical properties of the resin. Therefore, the fact that the photoconductor of the present invention having the surface protective layer having the above-mentioned constitution can exert the above-mentioned remarkable effects was completely unexpected to those skilled in the art, and the reason for this is now known. However, it is completely impossible.

Regarding the constitution in which polyvinyl acetate is used in combination with the thermosetting silicone resin, as described above, JP-A-63-18354
Already disclosed in the publication, an average degree of polymerization of 2000 or less, polyvinyl acetate which cannot act alone as a binder resin, 0.1 to 30 parts by weight based on 100 parts by weight of the solid content of the thermosetting silicone resin. With regard to the configuration to be used in combination, the inventors found out as a result of various studies, and it is a completely novel configuration.

The present invention will be described in detail below.

The thermosetting silicone resin used in the present invention,
Hydrolysates of silane compounds such as tetraalkoxysilane, trialkoxyalkylsilane, dialkoxydialkylsilane and other organosilanes, trichloroalkylsilane, dichlorodialkylsilane and other organohalogensilanes, either alone or in combination of two or more ( So-called organopolysiloxanes) or their initial condensation reaction products are preferred. As the alkoxy group and the alkyl group of the silane-based compound, a methoxy group, an ethoxy group, methyl,
A lower group having about 1 to 4 carbon atoms such as ethyl is preferable.

Depending on the conditions, the thermosetting silicone resin can be cured only by heating without using a catalyst, but in general, a catalyst is often used in order to complete the curing reaction smoothly and uniformly.

As the curing catalyst for the thermosetting silicone resin, various ones such as inorganic acids or organic acids, alkalis such as amines and the like can be used. Further, if necessary, a conventionally known curing aid and the like can be used in combination.

The content ratio of the thermoplastic resin for use in the present invention used in combination with the thermosetting silicone resin needs to be in the range of 1 to 30 parts by weight with respect to 100 parts by weight of the solid content of the thermosetting silicone resin after curing. is there. This is because if it is less than 0.1 parts by weight, the gas barrier property against ozone, the brittleness against sliding friction, etc. cannot be sufficiently improved, and if it exceeds 30 parts by weight, the surface hardness, the transparency and the like decrease, and This is because the sensitivity characteristics of the electrophotographic photoreceptor are adversely affected. The content of the thermoplastic resin for use in the present invention is preferably 1 to 10 parts by weight in the above range.

Among the thermoplastic resins for the present invention, polyvinyl acetate needs to have an average degree of polymerization of 2000 or less. This is because if the average degree of polymerization exceeds 2000, the surface hardness, transparency, etc. of the surface protective layer will deteriorate and the sensitivity characteristics of the electrophotographic photosensitive member will be adversely affected.

Polyamide resin includes polycapramide (6-nylon), polyhexamethylene adipamide (6,6-nylon), polyhexamethylene sebacamide (6,10-nylon), polyundecane amide (11-nylon), poly −
A conventionally known polymer having an acid amide bond such as ω-aminoheptanoic acid (7-nylon) and poly-ω-aminononanoic acid (9-nylon) is used.

Polyvinyl pyridine includes 2-vinyl pyridine, 3-vinyl pyridine and 4-vinyl pyridine, which may be used alone or in combination.
It is obtained by polymerizing at least one species, and its average molecular weight needs to be 10,000 or less. This is because when the average molecular weight exceeds 10,000, the transparency of the surface protective layer decreases and the sensitivity characteristics of the electrophotographic photosensitive member are adversely affected.

In addition, as the binder resin, a thermosetting resin or a thermoplastic resin other than those described above can be used in combination as long as the characteristics of the film are not impaired. As the binder resin other than the above,
Curable acrylic resin; alkyd resin; unsaturated polyester resin; diallyl phthalate resin; phenolic resin;
Urea resin; benzoguanamine resin; melamine resin; styrene polymer; acrylic polymer; styrene-acrylic copolymer; polyethylene, ethylene-vinyl acetate copolymer, olefin polymers such as chlorinated polyethylene, polypropylene and 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.

In the surface protective layer, conventionally known sensitizers such as terphenyl, halonaphthoquinones, and acenaphthylene; fluorene compounds such as 9- (N, N-diphenylhydrazino) fluorene and 9-carbazolyliminofluorene; conductive materials Various additives such as a property-imparting agent; an antioxidant such as an amine-based or phenol-based agent; a deterioration inhibitor such as an ultraviolet absorber such as a benzophenone-based agent; and a plasticizer can be contained.

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

The photosensitive member of the present invention can have the same structure as that of the related art except for the structure other than the surface protective layer, using the same material as the conventional one.

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 according to the mechanism and structure of the image forming apparatus in which the electrophotographic photosensitive member is incorporated. 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 having no conductivity, and the surface thereof may be provided with conductivity. .

As the conductive material used in the conductive base material having the former structure, the surface was anodized,
Or untreated aluminum, copper, tin, platinum, gold,
A metal material such as silver, vanadium, molybdenum, chromium, cadmium, titanium, nickel, palladium, indium, stainless steel, or brass is preferable.

On the other hand, as the latter structure, on the surface of a synthetic resin base material or a glass base material, a thin film made of a conductive material such as the above-exemplified metals or aluminum iodide, tin oxide, indium oxide, a vacuum deposition method or Structures laminated by a known film forming method such as a wet plating method, structures in which a film such as the metal material is laminated on the surface of the synthetic resin molded product or the glass substrate, the synthetic resin molded product or the glass substrate A structure in which a substance imparting conductivity is injected into the surface is exemplified.

The conductive base material may be subjected to a surface treatment with a surface treatment agent such as a silane coupling agent or a titanium coupling agent, if necessary, to enhance the adhesion to the photosensitive layer.

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

The photosensitive layer may be made of a semiconductor material, an organic material, or a composite material thereof, having the following structure.

A single layer type photosensitive layer made of a semiconductor material.

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

A charge generation layer containing a charge generation material in a binder resin,
A laminated organic photosensitive layer comprising a charge transport layer containing a charge transport material in a binder resin.

A composite type photosensitive layer in which a charge generation layer made of a semiconductor material and the organic charge transport layer are laminated.

As a semiconductor material that can be used alone as a charge generation layer in a composite type photosensitive layer to form a photosensitive layer,
In addition to α-Se, for example, amorphous chalcogenides such as α-As ₂ Se ₃ , α-Se AsTe and amorphous silicon (α-Si) are exemplified. The photosensitive layer or charge generating layer made of the above semiconductor material can be formed by a known thin film forming method such as a vacuum vapor deposition method or a glow discharge decomposition method.

As the organic or inorganic charge generating material used for the charge generating layer in the single-layer type or laminated type organic photosensitive layer,
For example, the powder of the semiconductor material exemplified above; ZnO, CdS, etc. II-V
Group I microcrystals; pyrylium salts; azo compounds; bisazo compounds; phthalocyanine compounds; ansanthrone compounds; perylene compounds; indigo compounds; triphenylmethane compounds; threnic compounds; toluidine compounds; pyrazoline compounds Quinacridone compounds; pyrrolopyrrole compounds are exemplified. And, among the above-exemplified compounds, belong to a phthalocyanine compound,
Aluminum phthalocyanine, copper phthalocyanine, metal free phthalocyanine, titanyl phthalocyanine and the like having various crystal types such as α type, β type and γ type are preferably used, and particularly, the above metal free phthalocyanine and / or titanyl phthalocyanine is more preferably used. There is. The charge generating materials may be used alone or in combination of plural kinds.

Examples of the charge transport material contained in the charge transport layer in the single-layer type or multilayer type organic photosensitive layer or the composite type photosensitive layer include tetracyanoethylene; 2,4,7-trinitro-9-fluorenone. Fluorenone compounds such as; nitration compounds such as dinitroanthracene; succinic anhydride; maleic anhydride; dibromomaleic anhydride; triphenylmethane compounds; 2,5-di (4-dimethylaminophenyl) -1,3, Oxadiazole compounds such as 4-oxadiazole; styryl compounds such as 9- (4-diethylaminostyryl) anthracene; carbazole compounds such as poly-N-vinylcarbazole; 1-phenyl-3-
Pyrazoline compounds such as (p-dimethylaminophenyl) pyrazolin; amine derivatives such as 4,4 ′, 4 ″ -tris (N, N-diphenylamino) triphenylamine; 1,1-bis (4-diethylaminophenyl) -4,4-diphenyl-
Conjugated unsaturated compounds such as 1,3-butadiene; hydrazone compounds such as 4- (N, N-diethylamino) benzaldehyde-N, N-diphenylhydrazone; indole compounds,
Oxazole compounds, isoxazole compounds, thiazole compounds, thiazole compounds, imidazole compounds, pyrazole compounds, pyrazoline compounds,
Nitrogen-containing cyclic compounds such as triazole compounds; condensed polycyclic compounds are exemplified. The above charge transport materials can be used alone or in combination of two or more. Among the above charge transport materials, the photoconductive polymer material such as poly-N-vinylcarbazole can also be used as the binder resin for the photosensitive layer.

Further, the single-layer type or laminated type organic photosensitive layer, the layer such as the charge transport layer in the composite type photosensitive layer, the sensitizer, a fluorene compound, an antioxidant, a deterioration inhibitor such as an ultraviolet absorber, Additives such as plasticizers may be included.

In the single-layer organic photosensitive layer, the content ratio of the charge generation material to 100 parts by weight of the binder resin is preferably in the range of 2 to 20 parts by weight, particularly preferably 3 to 15 parts by weight,
On the other hand, the content ratio of the charge transport material to 100 parts by weight of the binder resin is preferably in the range of 40 to 200 parts by weight, and particularly preferably in the range of 50 to 100 parts by weight. If the charge generating material is less than 2 parts by weight or the charge transporting material is less than 40 parts by weight, the sensitivity of the photoconductor becomes insufficient and the residual potential becomes large. This is because if the amount exceeds or the amount of the charge transport material exceeds 200 parts by weight, the abrasion resistance of the photoreceptor cannot be sufficiently obtained.

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

On the other hand, in the layers constituting the laminated organic photosensitive layer, the content ratio of the charge generating material to the binder resin 100 parts by weight in the charge generating layer is in the range of 5 to 500 parts by weight, particularly 10 to 250 parts by weight.
It is preferably within the range of parts by weight. This is because if the amount of the charge generating material is less than 5 parts by weight, the charge generating ability is too small, and if it exceeds 500 parts by weight, the adhesiveness with other adjacent layers or substrates is deteriorated.

The thickness of the charge generation layer is 0.01 to 3 μm, particularly 0.1 to 2 μm.
It is preferably in the range of μm.

Further, among the layers constituting the laminated organic photosensitive layer and the composite type photosensitive layer, in the charge transport layer, the content ratio of the charge transport material relative to 100 parts by weight of the binder resin is in the range of 10 to 500 parts by weight, and particularly, It is preferably in the range of 25 to 200 parts by weight. This is because if the charge transport material is less than 10 parts by weight, the charge transport ability is insufficient, and if it exceeds 500 parts by weight, the mechanical strength of the charge transport layer is lowered.

The thickness of the charge transport layer is 2 to 100 μm, particularly 5 to 30 μm.
It is preferably within the range of m.

As described above, the organic layer such as the single-layer type or laminated type organic photosensitive layer, the charge transport layer of the composite type photosensitive layer, and the surface protective layer is a coating liquid for each layer containing the above-mentioned components. Is adjusted, and each of the coating liquids is sequentially applied onto the conductive base material layer by layer so as to form the above-mentioned layer structure, and dried or cured to form a laminate.

When preparing the above-mentioned coating liquid, various solvents can be used depending on the type of binder resin or the like used. Examples of the solvent include aliphatic hydrocarbons such as n-hexane, octane and cyclohexane; benzene, xylene,
Aromatic hydrocarbons such as toluene; halogenated hydrocarbons such as dichloromethane, carbon tetrachloride, chlorobenzene, methylene chloride; methyl alcohol, ethyl alcohol, isopropyl alcohol, allyl alcohol, cyclopentanol, benzyl alcohol, furfuryl alcohol, diacetone Alcohols such as alcohols; ethers such as dimethyl ether, diethyl ether, tetrahydrofuran, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol dimethyl ether; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone;
Examples of various solvents include esters such as ethyl acetate and methyl acetate; dimethylformamide; dimethylsulfoxide and the like, and these are used alone or in combination of two or more. Further, when adjusting the above-mentioned coating liquid, a surfactant, a leveling agent, or the like may be used in combination in order to improve dispersibility, coatability, and the like.

Further, the coating solution is a conventional method, for example, a mixer,
It can be prepared using a ball mill, paint shaker, sand mill, attritor, ultrasonic disperser, or the like.

<Example> Hereinafter, the present invention will be described in more detail based on Examples.

Examples 1-5, Comparative Examples 1,2,4,5 Polyarylate (manufactured by Unitika Ltd., trade name U-100) 100 parts by weight, 4- (N, N-diethylamino) benzaldehyde-
A charge transporting coating solution consisting of 100 parts by weight of N, N-diphenylhydrazone and 900 parts by weight of methylene chloride (CH ₂ Cl ₂ ) was prepared, and this coating solution was applied onto an aluminum tube having an outer diameter of 78 mm and a length of 340 mm. After that, heat dry at 100 ℃ for 3 minutes,
A charge transport layer having a film thickness of 20 μm was formed.

Next, on the charge transport layer, 80 parts by weight of 2,7-dibromoanthansulone (manufactured by ICI), 20 parts by weight of metal-free phthalocyanine (manufactured by BASF), polyvinyl acetate (manufactured by Nippon Synthetic Chemical Co., Ltd., trade name) YS-N) 50 parts by weight and diacetone alcohol 20000 parts by weight were applied to the charge generation layer coating liquid and dried under the same conditions as above to form a 0.5 μm-thickness charge generation layer.

Next, 57.4 parts by weight of 0.02N hydrochloric acid and isopropyl alcohol 3
After mixing with 6 parts by weight, 80 parts by weight of methyltrimethoxysilane and 20 parts by weight of glycidoxypropyltrimethoxysilane were gradually added dropwise with stirring while maintaining the liquid temperature of the mixed solution at 20 to 25 ° C. A silane hydrolyzate solution was obtained by leaving it at room temperature for 1 hour.

Then, in this silane hydrolyzate solution, the average degree of polymerization shown in Table 1, the amount of polyvinyl acetate, 20 parts by weight of acetic acid, 0.5 parts by weight of triethylamine as a curing agent, and antimony-doped tin oxide as a conductivity-imparting agent were added. 50 parts by weight of fine powder (Sumitomo Cement Co., Ltd.) and silicone surfactant 0.3
A coating solution for a surface protective layer is prepared by adding 1 part by weight, and the coating solution for a surface protective layer is coated on the charge generation layer, and the temperature is 110 ° C.
Was heat-cured for 1 hour to form a silicone resin surface protective layer having a film thickness of 2.5 μm, and a drum type electrophotographic photoreceptor having a laminated type photosensitive layer was prepared.

The polyvinyl acetate was prepared by a solution polymerization method in which a vinyl acetate monomer was diluted with methyl alcohol and azobisisobutyronitrile (AIBN) was used as a polymerization initiator. The average degree of polymerization was adjusted by appropriately controlling the amount of catalyst, the amount of solvent and the like.

Comparative Example 3 An electrophotographic photosensitive member was produced in the same manner as in Example 1 except that polyvinyl acetate was not added to the surface protective layer coating liquid.

Examples 6 to 8 and Comparative Examples 6, 7, 9 Instead of polyvinyl acetate, a coating solution for a surface protective layer containing a polyamide resin (manufactured by Toray, CM4000) in an amount shown in Table 2 was used. An electrophotographic photosensitive member was produced in the same manner as in Example 1 except for the above.

Comparative Example 8 An electrophotographic photosensitive member was produced in the same manner as in Example 6 except that the coating solution for the surface protective layer did not contain a polyamide resin.

Examples 9 to 12, Comparative Examples 10, 11, 13 and 14 Instead of polyvinyl acetate, polyvinyl pyridine having the average molecular weight and compounding amount shown in Table 3 (all manufactured by Koei Chemical Industry Co., Ltd.)
An electrophotographic photoreceptor was prepared in the same manner as in Example 1 except that the surface protective layer coating solution containing was used.

Comparative Example 12 An electrophotographic photosensitive member was produced in the same manner as in Example 9 except that polyvinyl pyridine was not added to the surface protective layer coating liquid.

The following tests were carried out on the electrophotographic photosensitive members produced in the above-mentioned Examples and Comparative Examples.

Surface potential measurement Each of the above electrophotographic photoconductors was loaded into an electrostatic copying tester (Gentec Cynthia 30M model, manufactured by Gentec),
The surface was positively charged and the surface potential V ₁ sp (V) was measured.

Half-exposure amount, residual potential measurement Using the halogen lamp which is the exposure light source of the electrostatic copying test device, each electrophotographic photosensitive member in the charged state is exposed under the conditions of an exposure intensity of 0.92 mW / cm ² and an exposure time of 60 msec. Exposure was performed, and the time until the surface potential V ₁ sp became 1/2 was determined, and the half-exposure amount E1 / 2 (μJ / cm ² ) was calculated.

Further, the surface potential after 0.4 seconds has elapsed from the start of the exposure,
It was measured as the residual potential Vr.p (V).

Measurement of surface potential change after repeated exposure Each of the above electrophotographic photoconductors was copied to a copying machine (manufactured by Mita Kogyo Co., Ltd., DC-111
After performing a copying process on 500 sheets, the surface potential was measured as the surface potential V ₂ sp (V) after repeated exposure.

Further, the difference between the V ₁ sp value and the V ₂ sp value was calculated as the surface potential change value ΔV (V).

Measurement of changes in surface potential after exposure to ozone Each of the above electrophotographic photoconductors was copied by a copier (manufactured by Mita Kogyo, DC-152Z).
The main charger of the copier is operated to generate negative corona discharge, and the density near the surface of the photoconductor is increased.
It was exposed to an ozone atmosphere of 7 ppm for 60 minutes. afterwards,
The surface potential of each electrophotographic photosensitive member was measured, and the difference from the V ₁ sp value was calculated as the ozone exposure potential change value ΔVO ₃ (V).

Abrasion resistance test Drum polishing tester (manufactured by Mita Kogyo) for each electrophotographic photoreceptor
And a drum tester installed on this drum polishing tester, which rotates once during 1000 revolutions of the photoconductor, has a polishing test paper (Sumitomo 3M, trade name Imperial Wrapping Film, particle size 12 μm) Aluminum oxide powder on the surface) was loaded and the polishing test paper was pressed against the surface of the photoconductor at a linear pressure of 10 g / mm,
The amount of wear (μm) when the photoreceptor was rotated 400 times was measured.

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

The above results are shown in Table 1 for each type of thermoplastic resin for the present invention.
~ Shown in Table 3.

From the results of Table 1, in the combined system using polyvinyl acetate as the thermoplastic resin, the blending amount of polyvinyl acetate exceeds 50 parts by weight with respect to 100 parts by weight of the solid content of the thermosetting silicone resin. In this case (Comparative Example 4), the photosensitive properties such as initial sensitivity and abrasion resistance were almost the same as those in Examples 1 to 5, but the surface protective layer became cloudy. Furthermore, when the blending amount of polyvinyl acetate reaches 60 parts by weight (Comparative Example 1),
Photosensitive properties were adversely affected such as increase in residual potential and half-exposure amount, and abrasion resistance was also significantly deteriorated. On the other hand, when the blending amount of polyvinyl acetate was less than 0.1 parts by weight and became 0.05 parts by weight (Comparative Example 5), cracks were generated in the surface protective layer, and it could not be used as an electrophotographic photoreceptor (black streaks on the image). It came in). Therefore, the measurement of photosensitivity and the like was abandoned. When polyvinyl acetate having an average degree of polymerization of 2500 was used (Comparative Example 2), the residual potential and half-exposure amount increased, the abrasion resistance decreased, and white turbidity was observed in the surface protective layer. When polyvinyl acetate was not added (Comparative Example 3), the gas barrier property against ozone was remarkably deteriorated, the abrasion resistance was poor, and the amount of decrease in the surface potential after repeated exposure was large. Turned out to be brittle. On the other hand, the electrophotographic photoreceptors of Examples 1 to 5 are superior to the above-mentioned comparative examples in all respects such as the photosensitive characteristics such as half-exposure amount, abrasion resistance, appearance and gas barrier property. It turned out to be.

From the results of Table 2, in the combined system using the polyamide resin as the thermoplastic resin, when the blending amount of the polyamide resin with respect to 100 parts by weight of the solid content of the thermosetting silicone resin exceeds 30 parts by weight and becomes 50 parts by weight ( Comparative Example 9) Photosensitive properties such as initial sensitivity and abrasion resistance were almost the same as those in Examples 6 to 8, but the surface protective layer became cloudy. Further, when the blending amount of the polyamide resin was 60 parts by weight (Comparative Example 7), the residual potential and the half-exposure amount increased, and the photosensitive characteristics were adversely affected, and the abrasion resistance was significantly reduced. On the other hand, when the blending amount of the polyamide resin is less than 0.1 parts by weight and becomes 0.05 parts by weight (Comparative Example 6), cracks are generated in the surface protective layer, which cannot be used as an electrophotographic photoreceptor (black streaks appear on the image. It became a thing. Therefore, the measurement of photosensitivity and the like was abandoned. Further, when the polyamide resin is not blended (Comparative Example 8), the gas barrier property against ozone is remarkably deteriorated, the abrasion resistance is poor, and the amount of reduction in the surface potential after repeated exposure is large. It turned out to be brittle. On the other hand, the electrophotographic photoreceptors of Examples 6 to 8 are superior to the comparative examples in all respects such as the photosensitive characteristics such as half exposure amount, abrasion resistance, appearance, gas barrier property and the like. It turned out to be.

From the results of Table 3, in the combined system using polyvinyl pyridine as the thermoplastic resin, when the blending amount of polyvinyl pyridine exceeds 30 parts by weight and becomes 50 parts by weight with respect to 100 parts by weight of the solid content of the thermosetting silicone resin ( Comparative Example 13),
The abrasion resistance was almost the same as in Examples 9 to 12, but the amount of decrease in the surface potential after repeated exposure increased, and the surface protective layer became cloudy. Further, when the blending amount of polyvinyl pyridine was 60 parts by weight (Comparative Example 11), the residual potential was high, the half-exposure amount was large, and the abrasion resistance was lowered. On the other hand, when the blending amount of polyvinyl pyridine is less than 0.1 parts by weight and becomes 0.05 parts by weight (Comparative Example 14), cracks are generated in the surface protective layer and it cannot be used as an electrophotographic photoreceptor (black streaks appear on the image. It became a thing. Therefore, the measurement of photosensitivity and the like was abandoned. The average molecular weight of 15
When 000 polyvinyl pyridine was used (Comparative Example 10), the residual potential was high and the half-exposure amount was large,
Further, the amount of decrease in surface potential after repeated exposure was greatly increased, and white turbidity was observed in the surface protective layer. When polyvinyl pyridine was not blended (Comparative Example 12), the gas barrier property against ozone was significantly deteriorated, the abrasion resistance was poor, and the amount of decrease in surface potential after repeated exposure was large. It turned out to be brittle. On the other hand, the electrophotographic photoreceptors of Examples 9 to 12 are superior to the above-mentioned comparative examples in all respects such as photosensitive characteristics such as half exposure amount, abrasion resistance, appearance, gas barrier property, and the like. It turned out to be.

Further, all of the electrophotographic photoreceptors of Examples 1 to 12 above,
The surface protective layer was excellent in flexibility, the peeling strength between the photosensitive layer as the underlayer and the surface protective layer was large, and cracks were not observed.

<Effects of the Invention> As described above, according to the electrophotographic photoreceptor of the present invention, since the surface protective layer containing the thermosetting silicone resin contains the thermoplastic resin for the present invention, electrophotography It is possible to improve the gas barrier properties, the brittleness against sliding friction, etc., without adversely affecting the sensitivity characteristics and physical properties of the photoconductor, as compared with the case of using the thermosetting resin alone.

Continuation of the front page (56) Reference JP 61-51155 (JP, A) JP 50-50928 (JP, A) JP 55-98756 (JP, A) JP 51-78331 (JP , A)

Claims (3)

[Claims] 1. An electrophotographic photosensitive member having a surface protective layer containing a thermosetting silicone resin, wherein the surface protective layer comprises polyvinyl acetate having an average degree of polymerization of 2000 or less and a solid content of the thermosetting silicone resin. An electrophotographic photoreceptor containing 0.1 to 30 parts by weight per 100 parts by weight. 2. The electrophotographic photosensitive member according to claim 1, wherein the surface protective layer comprises a polyamide resin in place of polyvinyl acetate and 0.1 to 30 parts by weight based on 100 parts by weight of the solid content of the thermosetting silicone resin. An electrophotographic photosensitive member characterized by containing a part thereof. 3. The electrophotographic photosensitive member according to claim 1, wherein the surface protective layer is replaced with polyvinyl acetate and polyvinyl pyridine having an average molecular weight of 10,000 or less is added to 100 parts by weight of the solid content of the thermosetting silicone resin. On the other hand, an electrophotographic photoreceptor containing 0.1 to 30 parts by weight.