JPH02148041A - Catalyst for hardening surface layer of electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To form the surface layer superior in abrasion resistance by using a specified compound as the effective component of the catalyst for hardening the surface layer. CONSTITUTION:The hardening catalyst contains as the effective component at least one kind of compound selected from the compounds of formula I and the compounds of formula II, and since each of these compounds has an atomic group serviceable like the tertiary amine having a nitrogen atom in the center on a hetero ring, it can harden the surface layer containing a thermosetting resin, thus permitting the surface layer superior in abrasion resistance to be formed. In formula II, R is alkyl, acyl, aryl, arylsulfonyl, or alkoxy.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a catalyst for curing the surface layer of an electrophotographic photoreceptor.

<Prior Art> In an image forming apparatus such as a copying machine that utilizes the so-called Carlson process, an electrophotographic photoreceptor in which a photosensitive layer is formed on a conductive base is used.

The electrophotographic photoreceptor is repeatedly subjected to electrical, optical, and mechanical impacts during the image forming process, so in order to improve its durability against these impacts, the electrophotographic photoreceptor is coated on the photosensitive layer with the various structures described above. A relatively hard thermosetting resin such as polyurethane resin or epoxy resin is used as a binder resin.
In order to improve the hardness of the surface of the photosensitive layer, the hardness of the surface of the photosensitive layer is improved by laminating a surface protective layer containing 7. .

The thermosetting resin described above can be cured simply by heating without using a catalyst depending on the conditions, but usually,
A catalyst is often used to complete the curing reaction smoothly and uniformly.

Catalysts for curing thermosetting resins include inorganic or organic acids,
There are various types of alkalis such as amines, etc., but the heat contained in the layer located on the surface of the electrophotographic photoreceptor (hereinafter referred to as the "surface layer"), such as the surface protective layer and the surface layer of the photosensitive layer, A curing catalyst for curing a curable resin is required to have the following performance.

(1) A surface layer with excellent mechanical strength can be formed by curing.

(2) It should not adversely affect the sensitivity, etc. of the electrophotographic photoreceptor.

Organic tin compounds such as dibutyl tin dilaure (DTL) and dibutyl tin dioctate (DTO) have been proposed as having the above-mentioned performance to some extent (see Japanese Patent Application Laid-open No. 4945/1983).

<Problems to be Solved by the Invention> However, the surface layer cured using the above organic tin compound still does not have sufficient wear resistance.

In addition, the initial sensitivity of the electrophotographic photoreceptor may be insufficient,
When repeated exposures were carried out 17 times, the catalyst remaining on the surface layer sometimes had an adverse effect on the photosensitive characteristics, such as a decrease in the surface potential of the photoreceptor.

This invention has been made in view of the above circumstances, and its purpose is to form a surface layer that does not adversely affect the characteristics of an electrophotographic photoreceptor and has excellent wear resistance. An object of the present invention is to provide a catalyst suitable for curing the surface layer of an electrophotographic photoreceptor.

Means and operation for solving the above problems> In order to solve the above problems, the catalyst for curing the surface layer of an electrophotographic photoreceptor according to the present invention (hereinafter referred to as the "catalyst of the present invention") has the following general formula (1 ) and the following general formula [I
The active ingredient is at least one compound selected from the group consisting of the compounds represented by [).

1,8-diaza-bicyclo[5,4,01undecene-7 (hereinafter referred to as rDBUJ), which is represented by the above general formula [I], which is an active component of the catalyst of the present invention, and the above general formula [1[ ] All of the DBU acid salts have a heterocyclic ring having a nitrogen atom-centered moiety that functions similarly to a tertiary amine. For this reason, the above-mentioned third
A surface layer containing a thermosetting resin that can be cured by grade amine (hereinafter referred to as [amine-curable thermosetting resin]),
It can be cured using the catalyst of the present invention.

When the catalyst of the present invention is used, a surface layer with superior wear resistance can be formed compared to when the organotin compound is used as a curing catalyst. In addition, the formed surface layer has excellent initial sensitivity and a small decrease in surface potential after repeated exposures, which indicates that the catalyst remaining in the surface layer will not have an adverse effect on the characteristics of the electrophotographic photoreceptor. Recognize.

The reason why the catalyst of the present invention exhibits the above-mentioned remarkable effects is not clear at present. As is well known, there are many unknown points regarding the relationship between the combination of a thermosetting resin material and a curing catalyst and the physical properties of the cured resin, and the influence of the catalyst remaining in the cured resin. therefore,
It was unexpected even for those skilled in the art that the catalyst of the present invention having the above structure was able to exhibit particularly remarkable effects as a catalyst for curing the surface layer of an electrophotographic photoreceptor, and the reason is It is currently impossible to elucidate this.

In the acid salt of DBU represented by the general formula [1], preferable ones among the above-mentioned layers corresponding to R in the formula include a phenyl group belonging to an aryl group,
Examples include a formyl group and an octanoyl group that belong to the acyl group, and each toluenesulfonyl group of 0-1-1p- that belongs to the arylsulfonyl group.

Furthermore, the proportion of the catalyst of the present invention to be used in the thermosetting resin is not particularly limited;
, 1 to 20% by weight, and particularly preferably 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 with excellent wear resistance cannot be formed.
This is because if the overlapping temperature is exceeded, the performance of the electrophotographic photoreceptor will be adversely affected, such as the sensitivity of the electrophotographic photoreceptor becoming insufficient or the surface potential of the photoreceptor decreasing when exposed repeatedly.

The catalyst of the present invention can also be used together with conventionally known curing aids 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-curing thermosetting resin, regardless of the layer structure of the electrophotographic photoreceptor.

Here, the surface layer to which the catalyst of the present invention is used refers to, for example, the following layer located on the surface of the electrophotographic photoreceptor.

■ 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-generating material and a charge-transporting material.

■ The surface layer of a laminated organic photosensitive layer consisting of a charge generation layer and a charge transport layer.

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

Note that as the binder resin, thermosetting resins or thermoplastic resins other than those mentioned above can be used in combination within a range that does not impair the properties of the film. Other binder resins other than the above include curable acrylic resin; alkyd resin: unsaturated polyester resin; diallyl phthalate resin; phenol resin; urea resin; benzoguanamine resin; melamine resin; styrene polymer; acrylic polymer; Styrene-acrylic copolymer; Olefin polymers such as polyethylene, ethylene-vinyl acetate copolymer, chlorinated polyethylene, polypropylene, ionomer; Polyvinyl chloride: Vinyl chloride-vinyl acetate copolymer; Polyvinyl acetate; Saturated Examples include polyester: polyamide; thermoplastic polyurethane resin: polycarbonate; polyarylate; polysulfone: ketone resin; polyvinyl butyral resin; polyether resin.

Next, the structure of each member, the material forming each layer, etc. will be described as reference when manufacturing an electrophotographic photoreceptor using the catalyst of the present invention. It should be noted that these may be the same as conventional ones.

First, the conductive base material will be described.

The conductive base material is formed into an appropriate shape, such as a sheet 1 shape or a drum shape, depending on the mechanism and structure of the image forming apparatus in which the electrophotographic photoreceptor is installed. Also,"
The second conductive base may be constructed entirely of a conductive material such as metal, or the base material itself may be formed of a structural material that does not have conductivity, and its surface may be imparted with conductivity.

In addition, the conductive materials used in the conductive base material having the former structure include those whose surfaces are alumite-treated,
Alternatively, metal materials such as untreated aluminum, copper, tin, platinum, gold, silver, vanadium, molybdenum, chromium, cadmium, titanium, nickel, palladium, indium, stainless steel, and brass are preferred.

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

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

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

As described above, the photosensitive layer can be made of a semiconductor material, an organic material, or a composite material thereof.

Semiconductor materials that can be used as a charge generation layer in a composite photosensitive layer and can also form a photosensitive layer by themselves include:
In addition to the above-mentioned α-, for example, α-AS2'xs,
Examples include amorphous chalcogenides such as a-8eAsTe and amorphous silicon (α-3L). The photosensitive layer or charge generation layer made of the above semiconductor material can be formed by a known thin film forming method such as a vacuum deposition method or a glow discharge decomposition method.

] 1 Organic or inorganic charge generating materials used for the charge generating layer in a single layer type or multilayer type organic photosensitive layer include:
For example, powder of the above-mentioned semiconductor material; ZTIOSCdS
II-Vll microcrystalline pyrylium salts; azo compounds; bisazo compounds, phthalocyanine compounds; anthanthrone compounds; perylene compounds; indigo compounds; triphenylmethane compounds; threne compounds; toluidine compounds, pyrazolines Examples include quinacridone-based compounds: pyrrolovirol-based compounds. Among the above-exemplified compounds, aluminum phthalocyanine, copper phthalocyanine, metal-free phthalocyanine, titanyl phthalocyanine, etc., which belong to phthalocyanine compounds and have various crystal forms such as α-type, β-type, and γ-type, are preferably used, and in particular, The above metal-free phthalocyanine and/or titanyl phthalocyanine are more preferably used. Note that the charge generating materials described above may be used alone or in combination.

Further, as the charge transport material contained in the charge transport layer in the single-layer type or multi-layer type organic photosensitive layer or the composite type photosensitive layer, for example, tetracyanoethylene, 2,4.7
- Fluorine, non-fluorene compounds such as dolinitro-9-fluorenone; nitrated compounds such as dinitroanthracene; succinic anhydride: maleic anhydride.

Dibromomaleic anhydride nitriphenylmethane compound; 2,5-di(4-dimethylaminophenyl> -i,
Oxadiazole compounds such as 3,4-oxadiazole; Styryl compounds such as 9-(4-diethylaminostyryl)anthracene; Carbazole compounds such as poly-N-vinylcarbazole; l-phenyl-3-(p-
Pyrazoline compounds such as dimethylaminophenyl)pyrazoline; 4,4°, 4°゛-Tris(N.

Amine derivatives such as N-diphenylamino)triphenylamine; 1. ■-Bis(4-diethylaminophenyl)
Conjugated unsaturated compounds such as -4,4-diphenyl-1,3-butadiene; hydrazone compounds such as 4-(N,N-diethylamino)benzaldehyde-N,N-diphenylhydrazone; indole compounds, oxazole compounds, Isoxazole compounds, thiazole compounds, thiadiazole compounds, imidazole compounds,
Nitrogen-containing cyclic compounds such as pyrazole compounds, pyrazoline compounds, and triazole compounds; fused polycyclic compounds are exemplified. The above charge transport materials can also be used alone or in combination. Note that among the charge transport materials described above, polymeric materials having photoconductivity such as the poly-N-vinylcarbazole can also be used as the binder resin.

In addition, layers such as the single-layer type or laminated type organic photosensitive layer, the charge transport layer in the composite type photosensitive layer, and the surface protective layer may contain conventionally known sensitizers such as terphenyl, halonaphthoquinones, acenaphthylene, etc. Contain various additives such as fluorene compounds such as 9-(N,N-diphenylhydrazino)fluorene and 9-carbazolyliminofluorene, antioxidants, deterioration inhibitors such as ultraviolet absorbers, and plasticizers. be able to.

In the single-layer type organic photosensitive layer, the content ratio of the charge generating material to 100 parts by weight of the binder resin is preferably within the range of 2 to 20 parts by weight, particularly within the range of 3 to 15 parts by weight; The content ratio of the charge transport material to 100 parts by weight of the binder resin is within the range of 40 to 200 parts by weight, particularly 50 parts by weight.
It is preferably within the range of 100 parts by weight. This is because if the charge generation material is less than 2 parts by weight or the charge transport material is less than 40 parts by weight, the sensitivity of the photoreceptor becomes insufficient or the residual potential increases.
This is because if the amount exceeds 0 parts by weight or if the amount of the charge transport material exceeds 200 parts by weight, sufficient abrasion resistance of the photoreceptor cannot be obtained.

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

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

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

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

The thickness of the charge transport layer is 2 to 100 μm, especially 5 to 3 μm.
It is preferably within the range of 0/7I.

Next, the surface protective layer will be described.

The surface protective layer is mainly composed of the above-mentioned binder resin, and optionally contains additives such as a conductivity improving agent; an amine-based or phenol-based antioxidant; and a benzophenone-based ultraviolet absorber. It is also possible to contain a certain amount.

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

This is explained below.In addition, organic layers such as a single-layer type or multi-layer type organic photosensitive layer, a charge transport layer of a composite type photosensitive layer, and a surface protective layer should be placed on the side of each layer containing the above-mentioned components. It is possible to prepare a coating liquid and apply these coating liquids to the conductive material layer by layer in order so as to form the above-mentioned layer structure, and then dry or harden them to form a laminate.

In addition, when preparing the above-mentioned coating liquid, various solvents can be used depending on the type of binder resin and the like used. The above solvents include aliphatic hydrocarbons such as n-hexane, octane and cyclohexane; aromatic hydrocarbons such as benzene, xylene and toluene; halogenated hydrocarbons such as dichloromethane, carbon tetrachloride, chlorobenzene and methylene chloride; methyl Alcohols such as alcohol, ethyl alcohol, isopropyl alcohol, allyl alcohol, cyclopentanol, benzyl alcohol, furfuryl alcohol, diacetone alcohol; di]7 Methyl ether, diethyl ether, tetrahydrofuran, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, Ethers such as diethylene glycol dimethyl ether; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; esters such as ethyl acetate and methyl acetate;
Various solvents such as dimethylformamide and dimethyl sulfoxide are exemplified, and these solvents may be used alone or in combination of two or more. Furthermore, when preparing the above-mentioned coating liquid, an interfacial lubricant, a leveling agent, etc. may be used in combination in order to improve dispersibility, coating properties, etc.

Further, the above coating liquid can be prepared by a conventional method such as a mixer,
It can be prepared using a ball mill, paint shaker, sand mill, attritor, ultrasonic disperser, etc.

<Examples> The present invention will be described in more detail below based on Examples.

Example 1 Boarylate (manufactured by Unitika, trade name u-ioo)
A charge transporting coating solution was prepared consisting of 100 parts by weight of 4-(N,N-diethylamino)benzaldehyde-N,N-diphenylhydrazone and 900 parts by weight of methylene chloride (CH2Cfz). After coating on an aluminum tube of 78 mm x 340 mm length, it was heated and dried at 100°C for 30 minutes to a film thickness of 2.
A charge transport layer of ゜μ layer was formed.

Next, on the charge transport layer, 80 parts by weight of 2,7-dibromoanthanthrone (manufactured by ICI), 20 parts by weight of metal-free phthalocyanine (manufactured by BASF), and polyvinyl acetate (manufactured by Nippon Gosei Kagaku Co., Ltd., trade name: A charge generation layer coating solution consisting of 50 parts by weight of YS-N) and 2000 parts by weight of diacetone alcohol was applied and dried under the same conditions as above to form a charge generation layer with a thickness of 0.5 μm.

Next, 57.4 parts by weight of 0.02N hydrochloric acid and 36 parts by weight of isopropyl alcohol were mixed, and the liquid temperature of the above mixture was lowered to 2.
While stirring and maintaining the temperature at 0 to 25°C, 144.7 parts by weight of methyltrimethoxysilane was gradually added dropwise, and the mixture was left at room temperature for 1 hour to form a reaction containing 100 parts by weight of a hydrolysis product of methyltrimethoxysilane. Solution 238.
1 part by weight was obtained.

Then, to this reaction solution, 3.3 parts by weight of bisphenol A-based epoxy resin (manufactured by Shell Chemical Co., Ltd., trade name Epicote 827.Epoxy weight 1180-190'), D B
U 0.3 parts by weight, acetic acid 19.6 parts by weight, n-butyl acetate 32.7 parts by weight, carpitol acetate 1
6.4 parts by weight, 16.4 parts by weight of xylene, 0.3 parts by weight of silicone surfactant, and antimony-doped tin oxide fine powder as a conductivity imparting agent (manufactured by Susumu Cement Co., Ltd.)
50 parts by weight was added to prepare a surface protective layer coating solution, and this surface protective layer coating solution was coated on the charge generation layer (7,
The material was cured by heating at 110° C. for 1 hour to form a silicone resin surface protective layer having a thickness of 2.5 μm, thereby producing a drum-shaped electrophotographic photoreceptor having a laminated photosensitive layer.

Example 2 In place of 0.3 parts by weight of DBU, the formula (II
) In the same manner as in Example 1 above, except that a surface protective layer coating solution containing 1 part by weight of an acid salt of DBU in which R is a phenyl group (manufactured by Zan Abro Co., Ltd., trade name SAN α1) was used. An electrophotographic photoreceptor was produced.

Example 3 Instead of 3.3 parts by weight of bisphenol A-based epoxy resin, polyglycol-based epoxy resin (manufactured by Nagashio Sangyo Co., Ltd., trade name: Denacol EX-314, epoxy equivalent: 150)
5. An electrophotographic photoreceptor was produced in the same manner as in Example above, except that a coating liquid for a surface protective layer containing Q parts by weight was used.

Example 4 Polyvinyl acetate (manufactured by Nippon Gosei Kagaku Co., Ltd., trade name YS-N) was used instead of 3.3 parts by weight of bisphenol A-based epoxy resin.
) An electrophotographic photoreceptor was produced in the same manner as in Example 1 above, except that a surface protective layer coating liquid containing 5.0 parts by weight was used.

Comparative Example 1 An electrophotographic photoreceptor was prepared in the same manner as in Example 1 above, except that a surface protective layer coating solution containing 1 part by weight of dibutyltin dilaurate was used instead of 0.3 parts by weight of DBU. was created.

Comparative Example 2 An electrophotographic photoreceptor was produced in the same manner as in Example 1, except that a surface protective layer coating solution containing 1 part by weight of triethylamine was used instead of 0.3 parts by weight of DBU. did.

Comparative Example 3 In place of 0.3 parts by weight of DBU, 1 part by weight of sodium acetate
An electrophotographic photoreceptor was produced in the same manner as in Example 1 above, except that a coating liquid for a surface protective layer containing 5 parts by weight was used.

The following tests were conducted on each of the electrophotographic photoreceptors produced in Examples 1 to 4 and Comparative Examples 1 to 3 above.

Surface Potential Measurement" Section 2 Each electrophotographic photoreceptor was loaded into an electrostatic copying tester (manufactured by Zientic Co., Ltd., Model Zientic Cynthia 30M machine), and its surface was positively charged to determine the surface potential V+ s, p.
, (V) were measured.

Half-decreased exposure amount and residual potential measurement Each electrophotographic photoreceptor in the above-mentioned charged state was measured using a halogen lamp, which is the exposure source of the electrostatic copying tester described in 1. Exposure intensity was 0.92 mW/cm, and exposure time was 60 IllScc.
.

The time required for the surface potential vls,p to decrease to 1/2 is determined, and the half-reduction exposure ff1El/2 (μJ
/Ci) was calculated.

Further, the surface potential 0.4 seconds after the start of the exposure was measured as the residual potential V r,p (V).

Measurement of surface potential change after repeated exposure (2) Each electrophotographic photoreceptor was loaded into a copying machine (3[]]]] Industrial Co., Ltd. model DC-111, and after 500 copies were processed, the surface potential was measured. , repetition 1, surface potential after exposure ■2s,
It was measured as p, (V).

Further, the difference between the VI S,p value and the v2s,p value was calculated as 1, and the surface potential change value Δ■ (■).

Abrasion resistance test Each electrophotographic photoreceptor was subjected to a drum polishing tester (manufactured by Sanda Kogyo Co., Ltd.)
At the same time, an abrasive test paper (manufactured by Jujutsu 3M Co., Ltd., trade name: Imperial Wrapping Film, particle size: 12 μl) was loaded onto the abrasive test paper mounting ring that rotates once every 1,000 revolutions of the photoreceptor, which is provided on this drum abrasive testing machine. aluminum oxide powder adhered to the surface),
Amount of wear when the photoconductor was rotated 400 times while pressing this abrasive test paper against the surface of the photoconductor with a linear pressure of Log/n+m (
μm) was measured.

The above results are shown in the table.

(The following is a blank space) As is clear from the table, the electrophotographic photoreceptors produced in Examples 1 to 4 all had lower residual potentials and smaller half-life exposures than Comparative Examples 1 to 3. It was found that the photosensitive properties were excellent, such as a small decrease in surface potential after repeated exposure. Further, it was also found that the electrophotographic photoreceptors produced in each example had excellent abrasion resistance of the surface protective layer as the surface layer.

In addition, in each of the Examples described in 2, the curing rate of the surface protective layer is not affected by atmospheric humidity, etc., and the curing efficiency is good, and the coating solution for the surface protective layer has good storage stability.
Furthermore, the surface protective layer after curing had excellent transparency and no cracks were observed.

<Effects of the Invention> As described in 2 below, the catalyst for curing the surface layer of an electrophotographic photoreceptor of the present invention cures the thermosetting resin contained in the surface layer, thereby curing the electrophotographic photoreceptor. It becomes possible to form a surface layer with excellent abrasion resistance without adversely affecting the photosensitive characteristics.

Procedural amendment (voluntary) February 2, 1990

Claims (1)

[Claims] 1. An electrophotographic photoreceptor containing as an active ingredient at least one compound selected from the group consisting of a compound represented by the following general formula [I] and a compound represented by the following general formula [II] Catalyst for surface layer curing. ▲There are mathematical formulas, chemical formulas, tables, etc.▼...[I] ▲There are mathematical formulas, chemical formulas, tables, etc.▼...[II] [However, R in the above formula [II] is an alkyl group, an acyl group,
Represents an organic group selected from the group consisting of an aryl group, an arylsulfonyl group, and an alkoxy group. ]