JP2690761B2 - Electrophotographic photoreceptor - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an electrophotographic photoreceptor, and more particularly, to an electrophotographic photoreceptor formed by laminating a photosensitive layer, a surface protective layer, and the like. .

<Prior Art> In an image forming apparatus such as a copying machine using a so-called Carlson process, a conductive base material is formed on a conductive base material.
An electrophotographic photosensitive member in which a single or multiple photosensitive layers, a surface protective layer and the like are laminated is used. As the photosensitive layer and the surface protective layer, an organic layer containing a binder resin, which has a wide selection of materials, is excellent in productivity, and has a high degree of freedom in functional design, is preferably used.

The electrophotographic photosensitive member is repeatedly subjected to electrical, optical and thermal shocks during the image forming process, so that the binder resin, charge generating material, charge transporting material and the like contained in each layer are prevented from being oxidized. Therefore, an antioxidant is added to any of the above layers.

Oxidation of the binder resin, the generation of free radicals, radical chain,
Peroxide generation, free radical re-generation due to peroxide decomposition, etc.
It is known to proceed by a combination of various reactions. Therefore, various antioxidants, such as primary antioxidants and secondary antioxidants, which are compatible with any of the above various reactions, are provided. The primary antioxidant captures free radicals generated by direct oxidation and terminates the chain of the oxidation reaction, and the secondary antioxidant generates peroxides generated by oxidation and generates free radicals. It decomposes without letting it go.

Also. As an antioxidant for an electrophotographic photoreceptor, not only is it excellent in the function peculiar to the above-mentioned antioxidant, but performance such as not adversely affecting the photosensitive characteristics of the electrophotographic photoreceptor is required. Various antioxidants having some performance have been proposed.

For example, as primary antioxidants, hindered phenols, paraphenylenediamines, hydroquinones (see JP-A-63-18354), hindered phenols having a specific structure (see JP-A-63-44662). )
And the like are preferred. As the secondary antioxidant, organic sulfur compounds, organic phosphorus compounds and the like are known to be preferable for electrophotographic photoreceptors.

<Problems to be Solved by the Invention> As described above, since the antioxidants such as the primary antioxidant and the secondary antioxidant each correspond only to a part of the complicated oxidation reaction, The use of each of the antioxidants alone cannot completely prevent the progress of complicated oxidation reaction. Therefore, it is necessary to use a plurality of different types of antioxidants in combination.

However, in the combined use system of the primary antioxidant and the secondary antioxidant, depending on the combination, the action of the primary antioxidant is too strong, and the action of the secondary antioxidant cannot be sufficiently exerted. In some cases, the functions of both antioxidants were offset, and when used in combination, the antioxidant function was rather decreased.

The present invention has been made in view of the above circumstances, and an object of the invention is to have both a primary oxidation deterioration prevention function and a secondary oxidation deterioration prevention function without adversely affecting photosensitive characteristics. An object is to provide an excellent electrophotographic photoreceptor.

<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-mentioned problems includes at least a layer containing a binder resin. It is further characterized by containing at least one compound selected from the group consisting of compounds represented by the following general formulas [I] and [II].

In the photoreceptor of the present invention having the above constitution, the compound represented by the general formula [I] (hereinafter referred to as "specific compound [I]"
And a compound represented by the general formula [II] (hereinafter referred to as "specific compound [II]") each have a molecule corresponding to a hindered phenol and a moiety corresponding to an organic phosphorus compound. Since it is provided inside, there is no fear that both parts will cancel each other when it is contained in the layer containing the binder resin. In addition, the specific compound [I] contained in the layer,
In [II], the portion corresponding to the hindered phenol captures the free radical generated by direct oxidation, terminates the chain of the oxidation reaction, and the portion corresponding to the organophosphorus compound is
Since the generated peroxide is decomposed, the photoreceptor of the present invention having a layer containing the specific compound [I] and / or the specific compound [II] has a primary oxidation deterioration preventing function and a secondary oxidation deterioration preventing function. It will be excellent for both. Further, the specific compounds [I] and [II] do not adversely affect the photosensitive characteristics of the photoconductor.

 Hereinafter, the present invention will be described in detail.

Among the specific compounds contained in the photoreceptor of the present invention, the specific compound [I] is, for example, 3,4 or
It is produced by reacting 5,6-dibenzo-1,2-oxaphosphane-2-oxide (hereinafter referred to as "DBOPO") with a hindered phenol represented by the general formula [IV].

In addition, the reaction of both is performed by the formula [I
V] is a dehydration condensation reaction with the OH group on the methyl group side in the compound of [V].

Further, the specific compound [II], for example, the above DBOPO,
It is produced by reacting with a hindered phenol represented by the following general formula [V].

The reaction between the two is an addition reaction between the P—H bond in DBOPO and CH═CH ₂ in the compound of formula [V].

The content of the specific compounds [I] and [II] in the layer containing the binder resin is in the range of 0.1 to 50 parts by weight based on 100 parts by weight of the solid content of the binder resin in the layer. Is preferred and 1
More preferably, it is in the range of 20 parts by weight. The content of the specific compound is 0.1 per 100 parts by weight of the solid content of the binder resin.
When it is less than 50 parts by weight, both the primary oxidation prevention function and the secondary oxidation prevention function of the electrophotographic photosensitive member are not sufficient, and when it exceeds 50 parts by weight, the photosensitive properties such as residual potential and half-exposure amount, and the properties such as abrasion resistance. This is because it will adversely affect

INDUSTRIAL APPLICABILITY The photoconductor of the present invention can be applied to conventionally known laminated type photoconductors having various layer structures.
The layer containing a binder resin containing a means a layer of an electrophotographic photoreceptor, for example, as follows.

A surface protective layer formed on a photosensitive layer made of a semiconductor material or an organic photosensitive layer.

A single-layer organic photosensitive layer containing a charge generation material and a charge transport material.

Any one of a stacked organic photosensitive layer comprising a charge generation layer and a charge transport layer.

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

The binder resin contained in each layer is a thermosetting silicone resin; an epoxy resin; a polyurethane resin; a curable acrylic resin; an alkyd resin; an unsaturated polyester resin; a diallyl phthalate resin; a phenol resin; a urea resin; a benzoguanamine resin; a melamine. Resin: Styrene-based polymer; Acrylic-based polymer; Styrene-acrylic-based copolymer; Polyethylene, ethylene-vinyl acetate copolymer,
Olefin polymers such as chlorinated polyethylene, polypropylene, and ionomer; polyvinyl chloride;
Vinyl acetate copolymers; polyvinyl acetates; saturated polyesters; polyamides; thermoplastic polyurethane resins; polycarbonates; polyarylates; polysulfones; ketone resins; polyvinyl butyral resins; polyether resins, and in particular condensates of organopolysiloxanes. A thermosetting silicone resin as a main component is preferably used.

Further, in each of the above layers, a conventionally known sensitizer such as terphenyl, halonaphthoquinones, and acenaphthylene; 9- (N, N
Fluorene compounds such as -diphenylhydrazino) fluorene and 9-carbazolyliminofluorene; deterioration inhibitors such as light stabilizers and ultraviolet absorbers; various additives other than specific compounds such as plasticizers may be contained. it can.

The photoreceptor of the present invention can be made of the same material as that of the related art except for the additive, and can have the same structure as the related art.

 First, the conductive substrate will be described.

The conductive base material is formed in an appropriate shape such as a sheet shape or a drum shape according to the mechanism and structure of the image forming apparatus into which the electrophotographic photosensitive member is incorporated. Further, the conductive substrate may be entirely formed of a conductive material such as a metal,
The base material itself may be formed of a structural material having no conductivity, and its surface may be provided with conductivity.

As the conductive material used in the conductive substrate having the former structure, the surface is 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, as the latter structure, on the surface of a synthetic resin substrate or a glass substrate, a thin film made of a conductive material such as the above-mentioned metals, aluminum iodide, tin oxide, and indium oxide is formed by vacuum evaporation or The structure laminated by a known film forming method such as a wet plating method, the structure formed by laminating a film of the metal material or the like 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.

As described above, the photosensitive layer is a semiconductor material or an organic material,
Alternatively, a structure composed of these composite materials can be used.

Semiconductor materials that can be used alone as the charge generating layer in the composite photosensitive layer and can form the photosensitive layer by themselves include, for example, amorphous chalcogenides such as α-Se, α-As ₂ Se ₃ , α-SeAsTe, and amorphous silicon ( α-S
i). The photosensitive layer or the charge generation layer made of the semiconductor material can be formed by a known thin film forming method such as a vacuum evaporation method and a glow discharge decomposition method.

The organic or inorganic charge generating material used for the charge generating layer and the monolayer type organic photosensitive layer in the stacked organic photosensitive layer includes, for example, a powder of the semiconductor material; ZnO, CdS
II-VI group microcrystals such as; pyrylium salts; azo compounds; bisazo compounds; phthalocyanine compounds; ansanthrone compounds; perylene compounds; indigo compounds;
Examples include triphenylmethane compounds; threnic compounds; toluidine compounds; pyrazoline compounds; quinacridone compounds; pyrrolopyrrole compounds. And
Among the above compounds, aluminum phthalocyanine, copper phthalocyanine, metal-free phthalocyanine, titanyl phthalocyanine, etc. having various crystal types such as α-type, β-type, γ-type belonging to the phthalocyanine-based compound are preferably used, and particularly, the above metal-free phthalocyanine And / or titanyl phthalocyanine is more preferably used. The charge generation materials may be used alone or in combination of two or more.

Examples of the charge transporting material used for the charge transporting layer in the laminated organic photosensitive layer or the composite photosensitive layer, and the charge transporting material used in the single layered organic photosensitive layer include tetracyanoethylene; 2,4,7-trinitro-9-fluorenone. Fluorenone compounds such as
Nitrated compounds such as dinitroanthracene; succinic anhydride; maleic anhydride; dibromomaleic anhydride; triphenylmethane compounds; 2,5-di (4-dimethylaminophenyl) -1,3,4-oxadiazole An oxadiazole compound; a styryl compound such as 9- (4-diethylaminostyryl) anthracene; a carbazole compound 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;
Nitrogen-containing cyclic compounds such as oxazole compounds, isoxazole compounds, thiazole compounds, thiadiazole compounds, imidazole compounds, pyrazole compounds, pyrazoline compounds and triazole compounds; condensed polycyclic compounds. The above charge transport materials can be used alone or in combination of two or more. In addition, among the above charge transport materials, a photoconductive polymer material such as poly-N-vinylcarbazole can also be used as a binder resin for the photosensitive layer.

In the single-layer type 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 in the range of 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 amount of the charge generating material is less than 2 parts by weight or the amount of the charge transporting material is less than 40 parts by weight, the sensitivity of the photoreceptor becomes insufficient or the residual potential becomes large. If the charge transporting material exceeds 200 parts by weight, the abrasion resistance of the photoconductor cannot be sufficiently obtained.

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

On the other hand, among the layers constituting the laminated organic photosensitive layer, the content ratio of the charge generation material to 100 parts by weight of the binder resin in the charge generation layer is in the range of 5 to 500 parts by weight, particularly 10 to 2 parts by weight.
Preferably it is in the range of 50 parts by weight. If the amount of the charge generating material is less than 5 parts by weight, the charge generating ability is too small, and if the amount exceeds 500 parts by weight, the adhesion to other adjacent layers or substrates is reduced.

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

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

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

 Next, the surface protective layer will be described.

The surface protective layer contains the above-exemplified binder resin as a main component, and may further contain an appropriate amount of additives such as a conductivity-imparting agent and a benzophenone-based ultraviolet absorber, if necessary.

The film thickness of the surface protective layer is 0.1 to 10 μm, and particularly [1]
It is preferable that it is within the range of 5 μm.

As described above, the organic layer such as the single-layer or multilayer organic photosensitive layer, the charge transporting layer of the composite photosensitive layer, and the surface protective layer are coating liquids for each layer containing the above-described components. Are adjusted, and these coating liquids are sequentially applied on a conductive substrate for each layer so as to form the above-described layer configuration, and then dried or cured to form a laminate.

In preparing the coating solution, various solvents can be used depending on the type of the binder resin or the like to be 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, and cyclohexanone;
Various solvents such as esters such as ethyl acetate and methyl acetate; dimethylformamide; dimethyl sulfoxide, and the like, may be used alone or in combination of two or more. When preparing the coating liquid, a surfactant, a leveling agent, and the like may be used in combination in order to improve dispersibility, coatability, and the like.

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

As a coating method of the coating liquid, various conventionally used coating methods such as a dip coating method (dipping method), a spray coating method, a spin coating method, a roller coating method, a blade coating method, a curtain coating method and a bar coating method. Can be mentioned.

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

Preparation of Specific Compound Preparation of Specific Compound [I] After adding DBOPO represented by the formula [III] (manufactured by Sanko Chemical Co., Ltd., trade name HCA) to an inert solvent, the liquid temperature is 50 to 80 ° C.
A solution was prepared by stirring while maintaining the above. Then in this solution,
In the general formula [IV], hindered phenols in which R ₁ and R ₂ are both t-butyl groups (manufactured by Shell Chemical Co., trade name In
ox 100) is gradually added (addition amount is 1 mol of hindered phenols to 1 mol of DBOPO), and liquid temperature is adjusted to 10 after completion of addition.
The reaction was carried out for 1.5 to 3 hours while maintaining the temperature at 0 to 130 ° C. And
After completion of the reaction, the reaction solution is cooled to precipitate a reaction product,
The specific compound [I] was obtained through the steps of filtration, washing and drying.

-Preparation of specific compound [II] As a compound to be reacted with DBOPO, hindered phenols (Sumitizer GM, manufactured by Sumitomo Chemical Co., Ltd.) in which R ₁ is a t-butyl group in General Formula [V] was used. A specific compound [II] was obtained in the same manner as above except for the above.

Example 1 Polyarylate (manufactured by Unitika Ltd., trade name U-100) 100
A coating solution for charge transport layer comprising 100 parts by weight of 4- (N, N-diethylamino) benzaldehyde-N, N-diphenylhydrazone and 900 parts by weight of methylene chloride (CH ₂ Cl ₂ ) was prepared. The outer diameter is 78 mm ×
After coating on a 340 mm long aluminum tube, 30 at 100 ° C
It was heated and dried for a minute to form a charge transport layer having a film thickness of 20 μm.

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) A charge generation layer coating solution consisting of 50 parts by weight of Y5-N) and 2000 parts by weight of diacetone alcohol was applied by a dipping method and dried under the same conditions as above to form a charge generation layer having a thickness of 0.5 μm. .

And 100 parts by weight of a thermosetting silicone resin (Toshiba Silicone, trade name Tosguard 510), 50 parts by weight of antimony-doped tin oxide fine powder (made by Sumitomo Cement) as a conductivity-imparting agent, and triethylamine 1 as a curing agent. Parts by weight, 300 parts by weight of isopropyl alcohol as a solvent, and 10 parts by weight of the specific compound [I] are applied onto the charge generation layer by a dipping method, and the coating solution is applied at 110 ° C. for 1 hour. Heat cured to a film thickness of 2.5 μm
The surface protective layer made of silicone resin was formed to prepare a drum type electrophotographic photoreceptor having a layer-type photosensitive layer.

Example 2 An electrophotographic photosensitive member was produced in the same manner as in Example 1 except that 10 parts by weight of the specific compound [II] was used instead of 10 parts by weight of the specific compound [I].

Comparative Example 1 Instead of 10 parts by weight of the specific compound [I], the compound represented by the general formula [I]
V] in which R ₁ and R ₂ are both t-butyl groups (Shell Chemical Co., Ltd., trade name Inox 100)
An electrophotographic photosensitive member was produced in the same manner as in Example 1 except that 10 parts by weight was used.

Comparative Example 2 Instead of 10 parts by weight of the specific compound [I], 10 parts by weight of a hindered phenol in which R ₁ is a t-butyl group in the general formula [V] (Sumitizer GM, trade name). In the same manner as in Example 1 except that
An electrophotographic photosensitive member was manufactured.

Comparative Example 3 An electrophotographic photosensitive member was produced in the same manner as in Example 1 except that 10 parts by weight of the specific compound [I] was not added.

Comparative Example 4 Instead of 10 parts by weight of the specific compound [I], the compound of the above formula [III]
An electrophotographic photosensitive member was produced in the same manner as in Example 1 except that 10 parts by weight of DBOPO (manufactured by Sanko Chemical Co., Ltd., trade name HCA) represented by

Example 3 An electrophotographic photosensitive member was produced in the same manner as in Example 1 except that the blending amount of the specific compound [I] was 0.1 part by weight.

Example 4 An electrophotographic photosensitive member was produced in the same manner as in Example 1 except that the blending amount of the specific compound [I] was 50 parts by weight.

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 photoreceptors was loaded into an electrostatic copying tester (Gentec Cynthia 30M type machine manufactured by Gentech), the surface thereof was charged positively, and the surface potential V ₁ sp (V)
Was measured.

Half-dose exposure and residual potential measurement Each electrophotographic photoconductor in the above charged state was exposed to a halogen lamp, which is the exposure light source of the electrostatic copying tester, to determine the exposure intensity.
The surface potential V ₁ sp is 1/2 when exposed to 0.92 mW / cm ²
Half-exposure dose E1 / 2 (μJ / cm ² )
Was calculated.

Further, after the exposure at the above exposure intensity for the exposure time of 60 mSec., The surface potential at 0.4 seconds after the start of the exposure was measured as the residual potential Vr.p. (V).

Measurement of Surface Potential Change after Repeated Exposure
After carrying out 500 sheets of copy processing after loading into an 11-inch machine), the surface potential was measured as the surface potential V ₂ sp (V) after repeated exposure.

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

Measurement of surface potential change after light irradiation Each of the above electrophotographic photoconductors was measured with a white fluorescent lamp at 1000 Lu.
After irradiating with light under the conditions of x and 10 minutes, and allowing to stand for 30 seconds, the surface potential of each electrophotographic photosensitive member was measured as the surface potential VP after light irradiation. The difference between the V ₁ sp value and the VP value was calculated as a surface potential change value ΔVP (V) after light irradiation.

 The above results are shown in the table.

From the results in the above table, when no additives such as a specific compound were contained in each layer (Comparative Example 3), the surface potential after repeated exposure and the surface potential after light irradiation remarkably decreased.

Further, in the case where the hindered phenol is contained in the surface protective layer in place of the specific compound (Comparative Examples 1 and 2), and when DBOPO as an organic phosphorus compound is contained in place of the specific compound (comparison In each case of Example 4), the surface potential after repeated exposure and the surface potential after light irradiation were still greatly reduced.

On the other hand, the electrophotographic photoreceptors of Examples 1 to 4 are all excellent in photosensitivity such as a high initial surface potential, a low residual potential and a small half-exposure amount, and the surface after repeated exposure. It has excellent oxidation resistance, such as a small decrease in electric potential and surface potential after light irradiation. Therefore, it is excellent in both primary oxidation deterioration prevention function and secondary oxidation deterioration prevention function. Was inferred.

<Effects of the Invention> As described above, according to the electrophotographic photoreceptor of the present invention, since the layer containing the binder resin contains the specific compound, the photosensitive characteristics are not adversely affected, and It is possible to improve both the primary oxidation deterioration prevention function and the secondary oxidation deterioration prevention function.

Claims (1)

(57) [Claims] 1. At least one of the layers containing a binder resin contains at least one compound selected from the group consisting of compounds represented by the following general formulas [I] and [II]. An electrophotographic photoreceptor characterized by the above.