JPH0553360A - Catalyst for hardening surface layer of electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To allow the formation of a surface layer having excellent wear resistance without adversely affecting the photosensitive characteristics of the electrophotographic sensitive body by using a specific tetraphenyl borate compd. as an effective component. CONSTITUTION:The catalyst for hardening the surface layer of the electrophotographic sensitive body contains the tetraphenyl borate compd. expressed by formula I as its effective component. This tetraphenyl borate compd. has a part making the action similar to the action of ternary amine centering at a nitrogen atom in a heterocycle. The surface layer contg. a thermosetting resin which can be cured by the ternary amine, such as polyurethane resin, can, therefore, be cured by using this catalyst. The surface layer having the higher wear resistance than in the case of use of an org. tin compd. as the catalyst for curing is formed if such catalyst is used. The formed surface layer has an excellent initial sensitivity and is less dropped in the surface potential after repetitive exposing. The catalyst remaining on the surface layer does not adversely affect the photosensitive characteristics any more.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a catalyst for curing a surface layer of an electrophotographic photoreceptor.

[0002]

2. Description of the Related Art In an image forming apparatus such as a copying machine utilizing the so-called Carlson process, an electrophotographic photoreceptor having a photosensitive layer formed on a conductive base material is used. The electrophotographic photosensitive member 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, etc., on the photosensitive layer having various structures, Relatively high hardness,
Hardness of the surface of the photosensitive layer is obtained by laminating a surface protective layer containing a thermosetting resin such as a polyurethane resin or an epoxy resin as a binder resin, or by including the thermosetting resin as a binder resin on the surface layer of the photosensitive layer. Are being improved.

Depending on the conditions, the above thermosetting resin can be cured only by heating without using a catalyst. Usually, a catalyst is used in order to complete the curing reaction smoothly and uniformly. Many. There are various types of curing catalysts for thermosetting resins, such as inorganic acids or organic acids, alkalis such as amines, etc., but on the surface of the electrophotographic photoreceptor such as the surface protective layer or the surface layer of the photosensitive layer. The following performance is required for the curing catalyst for curing the thermosetting resin contained in the positioned layer (hereinafter referred to as “surface layer”). (1) A surface layer having excellent mechanical strength can be formed by curing. (2) The sensitivity of the electrophotographic photoreceptor should not be adversely affected.

Organotin compounds such as dibutyltin dilaurate (DTL) and dibutyltin dioctate (DTO) have been proposed as those having the above-mentioned properties to some extent (see JP-A-60-4945).

[0005]

However, the surface layer cured by using the above organic tin compound still has insufficient abrasion resistance. Further, the initial sensitivity of the electrophotographic photosensitive member may be insufficient, or the surface potential of the photosensitive member may be lowered by repeated exposure, so that the catalyst remaining in the surface layer may adversely affect the photosensitive characteristics.

The present invention has been made in view of the above circumstances, and an object of the present invention is not to adversely affect the characteristics of an electrophotographic photosensitive member and to provide a surface layer excellent in abrasion resistance. The object of the present invention is to provide a catalyst for curing the surface layer of the electrophotographic photosensitive member, which is suitable for forming the film.

[0007]

Means and Actions for Solving the Problems In order to solve the above problems, a catalyst for curing a surface layer of an electrophotographic photoreceptor according to the present invention (hereinafter referred to as "catalyst of the present invention") is represented by the following general formula (I ) The tetraphenyl borate compound represented by

[0008]

[Chemical 2]

The above-mentioned general formula, which is an active ingredient of the catalyst of the present invention,
The tetraphenylborate compound represented by (I) has a heterocyclic ring centered on a nitrogen atom and having a function similar to that of a tertiary amine. Therefore, a surface layer containing a thermosetting resin (hereinafter referred to as "amine-curable thermosetting resin") that can be cured by the tertiary amine, such as a polyurethane resin, an epoxy resin, or a silicone resin, is used in the present invention. It can be cured using a catalyst.

When the catalyst of the present invention is used, a surface layer having excellent abrasion resistance can be formed as compared with the case where the organotin compound is used as a curing catalyst. Also,
The formed surface layer has excellent initial sensitivity and a small decrease in surface potential after repeated exposure, which indicates that the catalyst remaining in the surface layer does not adversely affect the characteristics of the electrophotographic photoreceptor.

The above-mentioned general formula, which is an active ingredient of the catalyst of the present invention,
The tetraphenylborate compound represented by (I) can cure a surface layer containing a thermosetting resin such as an epoxy resin. The tetraphenylborate compound of the catalyst of the present invention is 1,8-diazabicyclo (5,4,0) undecene-7 (hereinafter referred to as "D") represented by the following formula (II).
It can be obtained by reacting a derivative (abbreviated as “BU”) with approximately equivalent amount of sodium tetraphenylborate.

[0012]

[Chemical 3]

(In the formula, X represents a halogen atom.)
This reaction can use a known method, for example,
When water or a mixture of water and alcohol is used as a reaction solvent and both compounds are mixed, a fine insoluble matter is produced. The method of mixing is not particularly limited, but usually the opposite compounds are made into a solution, and the mixture is stirred for 0 to 1
Uniform mixing may be performed at 00 ° C. After filtration or centrifugation (washing if necessary, or purification by recrystallization), drying is performed to obtain the target compound.

The sodium halide, which is a by-product of this reaction, generally has an adverse effect on the physical properties of the cured product.
Remove to m or less, preferably to several tens of ppm or less. on the other hand,
The water content has an adverse effect on the pot life of the catalyst and the like, so it is made 5% or less, preferably 1% or less. The compound obtained is in powder form and can be used as it is, but it may be ground if necessary.

The ratio of the catalyst of the present invention to the thermosetting resin is not particularly limited, but it is preferably within the range of 0.1 to 15% by weight based on the total solid components of the thermosetting resin, and particularly 0. It is more preferably within the range of 0.5 to 10% by weight. This is because if it is less than 0.1% by weight, the thermosetting resin in the surface layer cannot be sufficiently cured and a surface layer excellent in abrasion resistance cannot be formed. If it exceeds the range, the sensitivity of the electrophotographic photosensitive member is insufficient, and the surface potential of the photosensitive member is lowered by repeated exposure, which adversely affects the performance of the electrophotographic photosensitive member.

The catalyst of the present invention can be used in combination with a conventionally known curing aid and the like, if necessary. The catalyst of the present invention having the above structure can be used for curing the surface layer containing the amine-curable thermosetting resin regardless of the layer structure of the electrophotographic photoreceptor. Here, the surface layer on which the catalyst of the present invention is used means, for example, the following layer located on the surface of the electrophotographic photosensitive member. A surface protective layer formed on a photosensitive layer or an organic photosensitive layer made of a semiconductor material. A single-layer type organic photosensitive layer containing a charge generating material and a charge transporting material. A surface layer of a laminated 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 sequentially laminated.

As the binder resin, a thermosetting resin or a thermoplastic resin other than the above may be used in combination within the range where the characteristics of the film are not impaired. Other binder resins other than the above are curable acrylic resins; alkyd resins; unsaturated polyester resins; diallyl phthalate resins; phenol resins; urea resins; benzoguanamine resins; melamine resins; styrene polymers; acrylic polymers; Styrene-acrylic copolymers; olefin polymers such as polyethylene, ethylene-vinyl acetate copolymers, chlorinated polyethylene, polypropylene, and ionomers; polyvinyl chloride; vinyl chloride-vinyl acetate copolymers; polyvinyl acetate; saturated Examples include polyesters, polyamides, thermoplastic polyurethane resins, polycarbonates, polyarylates, polysulfones, ketone resins, polyvinyl butyral resins, and polyether resins.

Next, the construction of each member, the material for forming each layer, and the like, which will serve as a reference when an electrophotographic photosensitive member is produced using the catalyst of the present invention, will be described. It should be added that these can be the same as conventional ones.
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 is alumite treated or untreated, aluminum, copper, tin,
Platinum, gold, silver, vanadium, molybdenum, chromium, cadmium, titanium, nickel, palladium, indium,
Metallic materials such as stainless steel and brass are preferred. On the other hand, as the latter structure, on the surface of the synthetic resin base material or the glass base material, a thin film made of a conductive material such as the above-mentioned metals or aluminum iodide, tin oxide, indium oxide,
Structures laminated by a known film forming method such as a vacuum deposition method or a wet plating method, a structure in which a film of the metal material or the like is laminated on the surface of the synthetic resin molded product or a glass substrate, the synthetic resin molded product, On the surface of the glass substrate,
An example is a structure in which a substance that imparts conductivity is injected.

If necessary, 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 to enhance the adhesion to the photosensitive layer. The photosensitive layer may be made of a semiconductor material, an organic material, or a composite material thereof as described above. Used as a charge generation layer in the composite type photosensitive layer,
As the semiconductor material capable of forming the photosensitive layer alone, in addition to α-Se described above, for example, α-As ₂ Se ₃ , α-Se As Te
Examples thereof include amorphous chalcogenides and amorphous silicon (α-Si). 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.

Examples of the organic or inorganic charge generating material used for the charge generating layer in the single-layer type or laminated type organic photosensitive layer include, for example, the semiconductor material powders described above; Zn.
II-VI group crystallites such as O and CdS; pyrylium salts; azo compounds; bisazo compounds; phthalocyanine compounds; anthanthrone compounds; perylene compounds; indigo compounds; triphenylmethane compounds; slene compounds; Examples include toluidine compounds, pyrazoline compounds, quinacridone compounds, and pyrrolopyrrole compounds. And, among the compounds exemplified above, aluminum phthalocyanine, copper phthalocyanine, metal-free phthalocyanine, titanyl phthalocyanine, and the like having various crystal forms such as α-type, β-type, and γ-type belonging to the phthalocyanine-based compound are preferably used, and particularly, The above-mentioned metal-free phthalocyanine and / or titanyl phthalocyanine is more preferably used. The charge generating materials may be used alone or in combination of two or more.

The charge transporting material contained in the charge transporting layer of the single-layer type or multilayer type organic photosensitive layer or the composite type photosensitive layer is, for example, tetracyanoethylene;
Fluorenone compounds such as 2,4,7-trinitro-9-fluorenone; nitrated compounds such as dinitroanthracene; succinic anhydride; maleic anhydride; dibromomaleic anhydride; triphenylmethane compounds; 2,5-di ( Oxadiazole compounds such as 4-dimethylaminophenyl) -1,3,4-oxadiazole; Styryl compounds such as 9- (4-diethylaminostyryl) anthracene; Carbazole compounds such as poly-N-vinylcarbazole A pyrazoline-based compound such as 1-phenyl-3- (p-dimethylaminophenyl) pyrazolin; 4,
Amine derivatives such as 4 ′, 4 ″ -tris (N, N-diphenylamino) triphenylamine; 1,1-bis (4-
Diethylaminophenyl) -4,4-diphenyl-1,
Conjugated unsaturated compounds such as 3-butadiene; 4- (N, N-
Hydrazone compounds such as diethylamino) benzaldehyde-N, N-diphenylhydrazone; indole compounds, oxazole compounds, isoxazole compounds, thiazole compounds, thiadiazole compounds, imidazole compounds, pyrazole compounds, pyrazoline compounds, triazoles A nitrogen-containing cyclic compound such as a system compound; a condensed polycyclic compound is 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. Further, the single-layer type or laminated type organic photosensitive layer, the charge transport layer in the composite type photosensitive layer, and the layer such as the surface protective layer, terphenyl, halonaphthoquinones, conventionally known sensitizers such as acenaphthylene, 9-
Fluorene compounds such as (N, N-diphenylhydrazino) fluorene and 9-carbazolyliminofluorene,
Various additives such as an antioxidant, a deterioration inhibitor such as an ultraviolet absorber, a plasticizer and the like can be contained.

Binder resin 1 in the single-layer organic photosensitive layer
The content ratio of the charge generation material with respect to 00 parts by weight is 2 to 2
It is preferably in the range of 0 parts by weight, particularly in the range of 3 to 15 parts by weight, while the content ratio of the charge transport material to 100 parts by weight of the binder resin is in the range of 40 to 200 parts by weight, particularly 50 parts by weight. It is preferably in the range of ˜100 parts by weight. This is because 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 photoreceptor becomes insufficient or 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 above single-layer type photosensitive layer can be formed to an appropriate thickness, but it is usually 10 to 50 μm, especially 15 to 25 μm.
Is preferably formed within the range. On the other hand, of the layers constituting the laminated organic photosensitive layer, in the charge generation layer,
The content ratio of the charge generation material to 100 parts by weight of the binder resin is preferably in the range of 5 to 500 parts by weight, particularly preferably in the range of 10 to 250 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 layers and the base material provided adjacently is deteriorated.

The thickness of the charge generation layer is 0.01 to 3 μm.
m, and particularly preferably in the range of 0.1 to 2 μm. Further, among the layers constituting the laminated organic photosensitive layer and the composite type photosensitive layer, the binder resin 100 in the charge transport layer is used.
The content ratio of the charge transport material with respect to parts by weight is 10 to 50.
It is preferably in the range of 0 parts by weight, particularly preferably in the range of 25 to 200 parts by weight. This is because if the amount of 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 decreases.

The thickness of the charge transport layer is 2 to 100 μm.
m, particularly preferably in the range of 5 to 30 μm.
Next, the surface protective layer will be described. The surface protective layer contains the above-exemplified binder resin as a main component, and if necessary, a conductivity-imparting agent; an amine-based or phenol-based antioxidant;
An additive such as a benzophenone-based ultraviolet absorber may be contained in an appropriate amount.

The thickness of the surface protective layer is 0.1 to 10 μm.
m, particularly preferably in the range of 1 to 5 μm. As described above, the organic layers 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 are coating liquids for each layer containing the above-mentioned components. Is adjusted, and each of the coating solutions is sequentially applied onto the conductive base material for each layer so as to form the above-mentioned layer structure, and dried or cured to form a laminate.

When preparing the coating solution, various solvents can be used depending on the type of binder resin used. Examples of the solvent include aliphatic hydrocarbons such as n-hexane, octane and cyclohexane; benzene,
Aromatic hydrocarbons such as xylene and toluene; halogenated hydrocarbons such as dichloromethane, carbon tetrachloride, chlorobenzene and methylene chloride; methyl alcohol, ethyl alcohol, isopropyl alcohol, allyl alcohol, cyclopentanol, benzyl alcohol, furfuryl alcohol, Alcohols such as diacetone alcohol; 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; ethyl acetate, methyl acetate Esters such as;
Various solvents such as dimethylformamide and dimethylsulfoxide are exemplified, and these are used alone or in combination of two or more. Further, when preparing the above-mentioned coating liquid, an interfacial lubricant, a leveling agent, etc. 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, a mixer, a ball mill, a paint shaker, a sand mill, an attritor, an ultrasonic disperser or the like.

[0031]

EXAMPLES The present invention will be described in more detail based on the following examples. Example 1 polyarylate 100 parts by weight, 4- (N, N- diethylamino) benzaldehyde -N, N-diphenyl hydrazone 100 parts by weight of methylene chloride (CH ₂ Cl ₂₎ 9
A coating solution for charge transport consisting of 100 parts by weight was prepared, and the coating solution was applied on an aluminum tube having an outer diameter of 78 mm and a length of 340 mm, and then dried by heating at 100 ° C. for 30 minutes to transport a charge having a thickness of 20 μm. Layers were formed.

Next, a charge generation layer comprising 80 parts by weight of 2,7-dibromoanthansulone, 20 parts by weight of metal-free phthalocyanine, 50 parts by weight of polyvinyl acetate and 2000 parts by weight of diacetone alcohol on the charge transport layer. The coating liquid was applied and dried under the same conditions as above to form a charge generation layer having a film thickness of 0.5 μm. Next, 0.02N
Hydrochloric acid 57.4 parts by weight and isopropyl alcohol 36 parts by weight were mixed, and methyltrimethoxysilane 144.g was added while stirring while maintaining the liquid temperature of the mixed solution at 20 to 25 ° C.
After gradually dropping 7 parts by weight, the reaction solution was allowed to stand at room temperature for 1 hour to obtain 238.1 parts by weight of a reaction solution containing 100 parts by weight of a hydrolysis product of methyltrimethoxysilane.

Then, a bisphenol A type epoxy resin (epoxy equivalent of 180 to 190) was added to this reaction solution.
3 parts by weight, 0.3 parts by weight of a tetraphenylborate compound represented by the following formula (I), 19.6 parts by weight of acetic acid, 32.7 parts by weight of n-butyl acetate, 16.4 parts by weight of carbitol acetate, xylene. 16.4 parts by weight, 0.3 parts by weight of a silicone-based surfactant, and 50 parts by weight of antimony-doped tin oxide fine powder as a conductivity-imparting agent were added to prepare a coating solution for a surface protection layer, and this surface protection was prepared. A layer-type coating liquid is applied on the charge generation layer, and is heated and cured at 110 ° C. for 1 hour to form a silicone resin surface protective layer having a film thickness of 2.5 μm, and a drum type electron having a laminated photosensitive layer. A photographic photoreceptor was produced.

[0034]

[Chemical 4]

Example 2 Instead of 3.3 parts by weight of bisphenol A type epoxy resin, polyglycol type epoxy resin (epoxy equivalent 15
0) An electrophotographic photosensitive member was produced in the same manner as in Example 1 except that the surface protective layer coating liquid containing 5.0 parts by weight was used. Comparative Example 1 Instead of 0.3 part by weight of the tetraphenylborate compound,
An electrophotographic photosensitive member was produced in the same manner as in Example 1 except that the coating solution for the surface protective layer containing 1 part by weight of dibutyltin dilaurate was used.

Comparative Example 2 Instead of 0.3 part by weight of the tetraphenylborate compound,
An electrophotographic photosensitive member was produced in the same manner as in Example 1 except that the coating solution for the surface protective layer containing 1 part by weight of triethylamine was used. For each electrophotographic photosensitive member produced in Examples 1 and 2 and Comparative Examples 1 and 2,
The following tests were conducted.

Surface potential measurement Each of the above electrophotographic photoconductors was loaded in an electrostatic copying tester (Gentech Cynthia 30M model, manufactured by Gentech Co., Ltd.) and the surface thereof was positively charged to give a surface potential V ₁ sp. (V)
Was measured. Half-dose exposure amount, residual potential measurement Each electrophotographic photosensitive member in the above charged state was exposed to an exposure intensity of 0.92 mW / cm ² and an exposure time of 60 mSec. By using a halogen lamp as an exposure source of the electrostatic copying test apparatus. Exposure was carried out under the conditions described above, and the time required for the surface potential V ₁ sp to become 1/2 was obtained, and the half-exposure amount E 1/2 (μJ / cm ² ) was calculated.

The surface potential 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 Each of the above electrophotographic photosensitive members was copied by a copying machine (manufactured by Mita Kogyo Co., Ltd.
(111 type machine) and after processing 500 copies, the surface potential is determined by the surface potential V ₂ sp (V) after repeated exposure.
Was measured as.

The difference between the V ₁ sp value and the V ₂ sp value was calculated as the surface potential change value ΔV (V). Abrasion resistance test Drum polishing tester (manufactured by Mita Kogyo) for each electrophotographic photoreceptor
The drum tester is mounted on the drum tester and is rotated once during 1000 revolutions of the photoconductor. The tester is mounted on the tester mounting ring (manufactured by Sumitomo 3M, trade name Imperial Wrapping Film, particle size 12 μm). (Aluminum oxide powder adhered to the surface) was loaded, and the abrasion amount (μ when the photoconductor was rotated 400 times while pressing this polishing test paper against the photoconductor surface with a linear pressure of 10 g / mm).
m) was measured.

The above results are shown in the table.

[0041]

[Table 1]

As is clear from the table, the electrophotographic photosensitive members produced in Examples 1 and 2 are both Comparative Examples 1 and 2.
It was found that the composition has excellent photosensitivity characteristics such as a low residual potential, a small half-exposure amount, and a small decrease in the surface potential after repeated exposure, as compared with those in Example 1. It was also found that the electrophotographic photosensitive members produced in each of the examples had excellent wear resistance of the surface protective layer as the surface layer.

In each of the above-mentioned examples, the curing efficiency of the surface protective layer is not affected by humidity in the atmosphere and the like, and the curing efficiency is good, and the storage stability of the coating solution for the surface protective layer is good. The surface protective layer after curing was excellent in transparency and no crack was observed.

[0044]

As described above, according to the catalyst for curing the surface layer of the electrophotographic photosensitive member of the present invention, by curing the thermosetting resin contained in the surface layer, the photosensitivity of the electrophotographic photosensitive member is improved. It is possible to form a surface layer that does not have an adverse effect on the heat resistance and has excellent wear resistance.

Claims (1)

[Claims] 1. A catalyst for curing a surface layer of an electrophotographic photoreceptor, which comprises a tetraphenylborate compound represented by the following general formula (I) as an active ingredient. [Chemical 1]