JP3148955B2 - Electrophotographic photoreceptor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an electrophotographic photosensitive member, and more particularly, to an electrophotographic photosensitive member having a photosensitive layer containing a carrier generating substance and a carrier transporting substance.

[0002]

2. Description of the Related Art Conventionally, selenium,
Those having a photosensitive layer containing an inorganic photoconductor such as zinc oxide, cadmium sulfide, or silicon as a main component have been widely known. However, these are not always satisfactory in characteristics such as thermal stability and durability, and also have problems in production and handling.

On the other hand, a photoreceptor having a photosensitive layer containing an organic photoconductive compound as a main component is relatively easy to manufacture, inexpensive, easy to handle, and generally used as a selenium photoreceptor. It has many advantages, such as better thermal stability, and as such an organic photoconductive compound, poly-N-vinylcarbazole is the most well-known, and this is 2,4,7- A photoreceptor having a photosensitive layer mainly composed of a charge transfer complex formed from a Lewis acid such as trinitro-9-fluorenone has already been put to practical use.

On the other hand, there is known a photoconductor having a function-separating type photosensitive layer of a laminated type or a single layer type in which a carrier generating function and a carrier transporting function of the photoconductor are respectively assigned to different substances. A photoreceptor having a photosensitive layer including a carrier generating layer composed of a thin amorphous selenium layer and a carrier transporting layer containing poly-N-vinylcarbazole as a main component has already been put to practical use.

[0005] However, poly-N-vinylcarbazole is
Lack of flexibility, the film is hard and brittle, easily cracks and peeling, and the photoreceptor using this is inferior in durability. In practice, the residual potential increases, and the residual potential accumulates with repeated use, so that the fog gradually increases and the copied image is damaged.

In addition, since low molecular organic photoconductive compounds generally do not have a film-forming ability, they are used in combination with an appropriate binder, and the physical properties or photosensitive characteristics of the film can be improved by selecting the type and composition ratio of the binder. Although it is preferable in that it can be controlled to some extent, types of organic photoconductive compounds having high compatibility with the binder are limited. Photoconductor in reality,
In particular, there are few types of binders that can be used for forming the photosensitive layer of the electrophotographic photosensitive member.

For example, US Pat. No. 3,189,447 describes 2,5
-Bis (p-diethylaminophenyl) -1,3,4-oxadiazole has low compatibility with binders commonly used as materials for the photosensitive layer of the electrophotographic photoreceptor, such as polyester and polycarbonate, and has poor electrophotographic properties. When the photosensitive layer is formed by mixing at a ratio required for conditioning, crystals of oxadiazole come to be precipitated at a temperature of 50 ° C. or more, and have a disadvantage that electrophotographic properties such as charge holding power and sensitivity are reduced. .

On the other hand, the diarylalkane derivative described in US Pat. No. 3,820,989 has little compatibility problem with a binder, but has low stability to light, and is used for repetitive transfer type electrophotography in which charging and exposure are repeated. When it is suitable for the photosensitive layer of the photoreceptor, the sensitivity of the photosensitive layer gradually decreases.

US Patent No. 3,274,000, JP-B-47-3642
No. 8 describes different types of phenothiazine derivatives, but all have the disadvantages of low photosensitivity and low stability upon repeated use.

The stilbene compounds described in JP-A-58-65440 and JP-A-58-198043 have relatively good charge holding power and sensitivity, but they are not satisfactory in durability when used repeatedly. Absent. These compounds also have a problem in sensitivity at low potential.

As a matter of fact, a carrier transporting material having practically satisfactory characteristics for producing an electrophotographic photosensitive member has not been found yet.

[0012]

SUMMARY OF THE INVENTION An object of the present invention is to provide a photosensitive member having high sensitivity.

Another object of the present invention is to provide an electrophotographic photosensitive member having high sensitivity and low residual potential.

Another object of the present invention is to provide an electrophotographic photosensitive member having high repetition stability.

[0015]

[Means for Solving the Problem] As a result of intensive studies in line with the above-mentioned object, the embodiments of the above-mentioned constituents have been identified by the general formulas (A), (B) and (D) shown in [Formula 1]. It has been found that electrophotographic photoreceptors containing at least one of the compounds represented have excellent utility.

Next, specific examples of the compound according to the present invention are A,
Examples are given for groups B and D.

[0017]

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[0018]

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[0019]

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[0020]

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[0021]

[0022]

[0023]

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[0024]

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[0025]

[0026]

[0027]

The synthesis examples of the exemplified compounds of the present invention are shown below.

[0029]

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As shown in the formula (1), 0.36 g of NaH and 30 ml of toluene were added to a 200 ml four-necked flask, and dissolved in 30 ml of toluene by dissolving 1 ; 5.16 g, 2 and 3.0 g while stirring under a nitrogen stream. Was added dropwise. After further stirring at room temperature for 3 hours, the reaction solution was poured into water, and the toluene phase was washed with water until the aqueous phase became neutral. After drying, the target product was isolated by column chromatography on silica gel C-200 and recrystallized from an acetone-methanol mixture to give 5.2 g of a pale yellow powder (89% yield).
I got

Although various structures are known for the structure of the electrophotographic photosensitive member, the electrophotographic photosensitive member of the present invention can take any of these forms.

Usually, the configuration is as shown in FIGS. 1 (1) to 1 (6). 1 (1) and 2 (2), a carrier generating layer 2 mainly composed of a carrier generating substance is provided on a conductive support 1.
And a photosensitive layer 4 composed of a laminate of a carrier transport layer 3 containing a carrier transport material as a main component.

The photosensitive layer 4 may be provided via an intermediate layer 5 provided on a conductive support, as shown in FIGS. Thus, when the photosensitive layer 4 has a two-layer structure, a photosensitive member having the best electrophotographic characteristics can be obtained.
In the present invention, as shown in FIGS. 5 and 6, the photosensitive layer 4 formed by dispersing the carrier generating substance 7 in a layer 6 containing a carrier transporting substance as a main component is used as a conductive support. 1 may be provided directly or via an intermediate layer 5. In the present invention, a protective layer 8 may be provided as the outermost layer as shown in FIG.

The following are examples of the carrier generating substance used in the carrier generating layer of the photosensitive layer according to the present invention.

(1) Azo dyes such as monoazo dyes, disazo dyes and trisazo dyes (2) Perylene dyes such as perylene anhydride and perylene imide (3) Indigo dyes such as indigo and thioindigo (4) Anthra Polycyclic quinones such as quinone, pyrenequinone and flavanthrone (5) quinacridone dye (6) bisbenzimidazole dye (7) indathrone dye (8) squarylium dye (9) cyanine dye (10) Azurenium-based dyes (11) Triphenylmethane-based dyes (12) Amorphous silicon (13) Phthalocyanine-based pigments such as metal phthalocyanine and metal-free phthalocyanine (14) Selenium, selenium-tellurium, selenium-arsenic (15) CdS, CdSe (16 ) Pyrylium salt dyes, thiapyrylium salt dyes, etc. It can be used alone or in combination of two or more. Since the compound of the present invention has no coating forming ability by itself, a photosensitive layer is formed by combining various binders.

Any binder can be used here, but it is hydrophobic and has a high dielectric constant.
It is preferable to use an electrically insulating film-forming polymer. Examples of such a high-molecular polymer include the following, but are not limited thereto.

(P-1) Polycarbonate (P-2) Polyester (P-3) Methacrylic resin (P-4) Acrylic resin (P-5) Polyvinyl chloride (P-6) Polyvinylidene chloride (P-7) Polystyrene (P-8) Polyvinyl acetate (P-9) Styrene-butadiene copolymer (P-10) Vinylidene chloride-acrylonitrile copolymer (P-11) Vinyl chloride-vinyl acetate copolymer (P-12) Chloride Vinyl-vinyl acetate-maleic anhydride copolymer (P-13) Silicone resin (P-14) Silicone-alkyd resin (P-15) Phenol formaldehyde resin (P-16) Styrene-alkyd resin (P-17) Poly -N-vinylcarbazole (P-18) polyvinyl butyral (P-19) polyvinyl formal These binder resins are used alone. There can be used as a mixture of two or more.

The solvent for forming the carrier generation layer and the transport layer according to the present invention includes N, N-dimethylformamide, acetone, methyl ethyl ketone, cyclohexanone, benzene, toluene, xylene, chloroform, 1,2-dichloroethane. , 1,2-dichloropropane, 1,
1,2-trichloroethane, 1,1,1-trichloroethane, trichloroethylene, tetrachloroethane, dichloromethane, tetrahydrofuran, dioxane, methanol, ethanol, isopropanol, ethyl acetate, butyl acetate, dimethyl sulfoxide, methyl cellosolve and the like. , Can also be used as a mixture.

When the photoreceptor of the present invention is a laminated photoreceptor, the weight ratio of the binder and the carrier transporting substance to the carrier generating substance in the carrier generating layer is 0.2 to 5 parts by weight when the carrier generating substance is 1 part by weight. And 0 to 1 part by weight of a carrier transporting substance.

Further, the carrier generating layer may be formed of the carrier generating substance alone.

If the content of the carrier-generating substance is less than 15% (by weight) in the carrier-generating layer, the photosensitivity is low and the residual potential is increased, and if it is more than this, the dark decay and the receiving potential are reduced.

The thickness of the carrier generation layer formed as described above is preferably 0.01 to 10 μm, particularly preferably
0.1 to 5 μm.

The amount of the carrier transporting material is preferably from 20 to 200 parts by weight, particularly preferably from 30 to 150 parts by weight, per 100 parts by weight of the binder resin in the carrier transporting layer.

The thickness of the carrier transport layer to be formed is
It is preferably from 5 to 50 μm, particularly preferably from 10 to 35 μm.

On the other hand, when the photoreceptor of the present invention has a single-layer structure,
The weight ratio of the binder and the carrier transporting substance to the carrier generating substance is preferably 0.2 to 5 parts by weight of the binder and 1 to 5 parts by weight of the carrier transporting substance, when the carrier generating substance is 1 part by weight. Is preferably 5 to 50 μm, particularly preferably 5 to 30 μm.

Examples of the conductive support used in the electrophotographic photoreceptor of the present invention include a metal plate, a metal drum or a conductive polymer containing an alloy, a conductive compound such as indium oxide, and aluminum or palladium containing an alloy. Paper, plastic film, etc., which are made conductive by applying, depositing or laminating a thin metal layer such as gold.

As the binder used for the intermediate layer, the protective layer and the like, those mentioned above for the carrier generating layer and the carrier transporting layer can be used. In addition, polyamide resin, nylon resin, ethylene-vinyl acetate, etc. Polymer, ethylene-vinyl acetate-maleic anhydride copolymer,
Ethylene resins such as ethylene-vinyl acetate-methacrylic acid copolymer, polyvinyl alcohol, cellulose derivatives and the like are effective.

Organic amines can be added to the photosensitive layer of the present invention for the purpose of improving the carrier generating function of the carrier generating substance. Among the organic amines, it is particularly preferable to add a secondary amine.

The above-mentioned photosensitive layer contains storability, durability,
For the purpose of improving environmental resistance, a deterioration preventing agent such as an antioxidant and a light stabilizer can be contained. Compounds used for such purposes include, for example, chromanol derivatives such as tocopherol and etherified or esterified compounds thereof, polyarylalkane compounds, hydroquinone derivatives and mono- and dietherified compounds thereof, benzophenone derivatives, benzotriazole derivatives, thioethers Compounds, phosphonates, phosphites, phenylenediamine derivatives, phenolic compounds, hindered phenolic compounds, linear amine compounds,
Cyclic amine compounds, hindered amine compounds, and the like are effective. Specific examples of particularly effective compounds include Ao-
1 "IRGANOX 1010", Ao-2 "IRGANOX565" (manufactured by Ciba-Geigy), Ao-3 "Sumilyzer BHT", Ao-4
Hindered phenol compounds such as "Sumilyzer MDP" (manufactured by Sumitomo Chemical Co., Ltd.), Ao-5 "Sanol LS-262"
And hindered amine compounds such as Ao-6 "Sanol LS-622LD" (manufactured by Sankyo). The weight ratio of these compounds to the carrier transporting material is from 1: 0.001 to 0.1, preferably from 1: 0.05 to 0.1.

In the present invention, one or more kinds of electron-accepting substances can be contained in the carrier generating layer for the purpose of improving sensitivity, reducing residual potential or reducing fatigue upon repeated use. Examples of the electron accepting substance that can be used here include succinic anhydride, maleic anhydride, dibromomaleic anhydride, phthalic anhydride, tetrachlorophthalic anhydride, tetrabromophthalic anhydride, 3-nitrophthalic anhydride, and 4-nitrophthalic anhydride. ―
Nitrophthalic anhydride, pyromellitic anhydride, melitic anhydride, tetracyanoethylene, tetracyanoquinodimethane, o-dinitrobenzene, m-dinitrobenzene, 1,3,
5-trinitrobenzene, paranitrobenzonitrile,
Piclink chloride, quinone chlorimide, chloranil, bulmanil, dichlorodicyanoparabenzoquinone,
Anthraquinone, dinitroanthraquinone, 2,7-dinitrofluorenone, 2,4,7-trinitrofluorenone,
2,4,5,7-tetranitrofluorenone, 9-fluorenylidenemalonodinitrile, polynitro-9-fluorenylidene-malonodinitrile, picric acid, o-nitrobenzoic acid, p-nitrobenzoic acid, 3,5-dinitrobenzoate Acid, pentafluorobenzoic acid, 5-nitrosalicylic acid, 3,5-dinitrosalicylic acid, phthalic acid, melitic acid, and others JP-A-1-206349, JP-A-2-214866, JP-A-2-135362, U.S. Patent
No. 455,659, compounds having a high electron affinity.

The amount of the electron accepting substance to be added is, in terms of weight ratio, carrier generating substance: electron accepting substance = 100: 0.01 to 200, preferably 100: 0.1 to 100.

The electron accepting substance may be added to the carrier transport layer. The amount of the electron-accepting substance added to the layer is carrier transporting substance: electron-accepting substance = 100: 0.01 to 1 by weight ratio.
00, preferably 100: 0.1 to 50.

The photoreceptor of the present invention may further contain, if necessary, an ultraviolet absorber for the purpose of protecting the photosensitive layer, and may contain a dye for correcting color sensitivity.

The electrophotographic photoreceptor of the present invention has the above-mentioned structure and, as will be apparent from the examples described later, has excellent charging characteristics, sensitivity characteristics and image forming characteristics, and especially when used repeatedly. Also, it has little fatigue deterioration and excellent durability.

Further, the electrophotographic photosensitive member of the present invention can be widely used in application fields such as a photosensitive member of a printer using a laser, a cathode ray tube (CRT), and a light emitting diode (LED) as a light source, in addition to an electrophotographic copying machine. .

[0056]

EXAMPLES The present invention will be described below in more detail with reference to Examples, but it should not be construed that the present invention is limited thereto.

Example 1 On a conductive support obtained by evaporating aluminum on a polyester film, a vinyl chloride-vinyl acetate-maleic anhydride copolymer "ESREC MF-10" (manufactured by Sekisui Chemical Co., Ltd.) having a thickness of 0.04 An intermediate layer having a thickness of μm is provided thereon, and dibromoanthranthrone “Monolite Red 2Y” (CI No. 5
1.5 g of polycarbonate "PANLITE L-1250" (manufactured by Teijin Chemicals) was dissolved in a dispersion obtained by adding 1 g of 9300 ICI) to 30 ml of 1,2-dichloroethane and dispersing with a ball mill, and thoroughly mixed. The coating solution was applied so that the film thickness after drying became 2 μm, to form a carrier generation layer.

A solution prepared by dissolving 5 g of Exemplified Compound (1), 10 g of polycarbonate "Z-200" (Mitsubishi Gas Chemical) and 0.5 g of a deterioration inhibitor shown in Table 1 in 80 ml of 1,2-dichloroethane was dried. Was applied to a thickness of 20 μm to form a carrier transporting layer, whereby a photoreceptor of the present invention was prepared.

The photoreceptor thus obtained was evaluated for the following characteristics using EPA-8100 manufactured by Kawaguchi Electric Co., Ltd.
After charging for 5 seconds at a charged voltage of -6 KV, the photosensitive member was left to stand for 5 seconds, and then irradiated with a halogen lamp light so that the illuminance on the surface of the photosensitive member became 2 lux.
/ 2. Further, the residual potential Vr after exposure at an exposure amount of 30 lux · sec was determined.

Examples 2 to 5 Photoconductors were prepared and measured in the same manner as in Example 1 except that the exemplified compounds shown in Table 1 were used instead of the exemplified compound (1).

Comparative Example (1) Compound T shown in the following [Chemical Formula 14] as a carrier transporting substance
A comparative photoconductor was prepared in the same manner as in Example 1 except that-(1) was used.

The comparative photoreceptor was measured in the same manner as in Example 1.

Table 1 shows the results of Examples 1 to 5 and Comparative Example (1).
Put together.

[0064]

[Table 1]

Example 6 An intermediate layer of polyamide resin "A-70" (manufactured by Toray Industries, Inc.) having a thickness of 0.1 μm was provided on a conductive support obtained by evaporating aluminum on a polyester film.

2 g of bisazo pigment G- (1) having the structure shown below and 2 g of polycarbonate resin “PANLITE L-1250” were mixed with 100 ml of 1,2-dichloroethane, and the mixture was mixed with a sand grinder for 8 hours. Dispersed. This dispersion was applied onto the intermediate layer so that the thickness after drying was 0.2 μm.

Illustrative compound (15) as a carrier transporting substance
A photoreceptor was prepared in the same manner as in Example 1 by adding 1.5% by weight of a deterioration inhibitor shown in Table 2 to the carrier transporting substance. The same measurement as in Example 1 was performed for this photoconductor.

Examples 7 to 9 Photoconductors were prepared and measured in the same manner as in Example 6, except that the exemplified compounds shown in Table 2 were used instead of the exemplified compound (15).

Comparative Example (2) The compound T-
A comparative photoconductor was prepared in the same manner as in Example 6, except that (2) was used.

The same measurement as in Example 1 was performed for this photoreceptor.

Table 2 shows the results of Examples 6 to 9 and Comparative Example (2).

[0072]

[Table 2]

Example 11 An intermediate layer of polyamide resin "CM8000" (manufactured by Toray Industries, Inc.) having a thickness of 0.2 μm was provided on a conductive support obtained by evaporating aluminum on a polyester film.

2 g of titanyl phthalocyanine having an X-ray diffraction spectrum shown in FIG. 2 and a silicone resin “KR-5240,
15% xylene-butanol solution ”(Shin-Etsu Chemical Co., Ltd.)
0 g was dispersed in 100 ml of isopropyl alcohol by using a sand mill.
It was applied to a thickness of 0.2 μm.

Next, 7 g of Exemplified Compound (8) as a carrier transporting substance and 10 g of polycarbonate “Z-200” were further placed thereon.
And 0.5 g of the deterioration inhibitor shown in Table 3 in 1,2-dichloroethane 80
Dissolved in ml. This solution was applied to a thickness of 20 μm after drying to form a carrier transport layer.

This photoreceptor was measured in the same manner as in Example 1.

Example 12 An intermediate layer having a thickness of 0.2 μm made of ethylene-vinyl acetate-methacrylic acid copolymer resin “ELVACS 4260” (manufactured by Du Pont-Mitsui Chemicals) was formed on an aluminum drum.

As the carrier transporting material of the present invention, 1 g of the exemplified compound (7) and the polyester resin “Vylon 200”
A solution prepared by dissolving 1.5 g (manufactured by Toyobo Co., Ltd.) in 1,2-dichloroethane (10 ml) was applied on the intermediate layer, dried, and dried to a film thickness of 15 μm.
A carrier transport layer was formed. On the other hand, 1 g of titanyl phthalocyanine having an X-ray diffraction spectrum shown in FIG. 2 as a carrier-generating substance, 3 g of polycarbonate "Panlite L-1250" (manufactured by Teijin Chemicals Ltd.) as a binder resin, 15 ml of monochlorobenzene as a dispersion medium, and 1,2 -Dichloroethane
After dispersing 35 ml using a ball mill, Exemplified Compound (7) was further added as a carrier transporting substance so as to be 75 wt% with respect to the binder resin. The dispersion thus obtained was applied on the carrier transporting layer by a spray coating method to form a carrier generating layer having a thickness of 2 μm.

The photoreceptor thus obtained was evaluated in the same manner as in Example 1 except that the charging polarity was set to a positive polarity.

Example 13 An intermediate layer having a thickness of 0.15 μm and made of a vinyl chloride-vinyl acetate-maleic anhydride copolymer “ESREC MF-10” (manufactured by Sekisui Chemical Co., Ltd.) was formed on an aluminum drum. On the other hand, 1 g of dibromoanthuanthrone “Monolite Red 2Y” as a carrier-generating substance was ball-milled, and then polycarbonate resin “Panlite L-1250” 3
g, monochlorobenzene 15g, 1,2-dichloroethane 35g
Was added to perform dispersion. To the obtained dispersion, 2 g of the compound 22 of the carrier transporting substance of the present invention and 0.1 g of a deterioration inhibitor shown in Table 3 were further added, and the mixture was applied on the intermediate layer by a spray coating method and dried. A photosensitive layer having a thickness of 20 μm was formed.

The photoreceptor thus obtained was evaluated in the same manner as in Evaluation 1 except that the charging polarity was set to a positive polarity.

Table 3 shows the results of Examples 11, 12, and 13 described above.

[0083]

[Table 3]

Example 14 Carrier-generating substance G- having the structure shown in [Formula 15]
(2) 1 part, 50 parts of 1,2-dichloroethane as a dispersion medium was dispersed using a sand mill, and this was applied using a wire bar on a polyester base on which aluminum was deposited,
A carrier generating layer having a thickness of 0.3 μm was formed. Next, 1 part of the exemplified compound (43), 1.3 parts of a polycarbonate resin “Iupilon Z-200” (manufactured by Mitsubishi Gas Chemical Company), and a small amount of silicone oil “KF-54” (manufactured by Shin-Etsu Chemical Co., Ltd.) A solution obtained by dissolving 0.05 part of the agent in 10 parts of 1,2-dichloroethane was applied using a blade coater and dried, and then the film thickness was 22 μm.
m was formed.

Examples 15 to 17 Photoconductors of the present invention were prepared in the same manner as in Example 14, except that the exemplified compound (43) in Example 14 was replaced with the exemplified compounds shown in Table 4.

Comparative Example (3) A compound was prepared in the same manner as in Example 14 except that the exemplified compound (43) in Example 14 was replaced with the compound T- (3) shown in [Formula 14].
A photoconductor for comparison was prepared.

The photoreceptor thus obtained was measured in the same manner as in Example 1.

Table 4 shows the results of Examples 14 to 17 and Comparative Example (3).

[0089]

[Table 4]

[0090]

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[0091]

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[0092]

The electrophotographic photoreceptor of the present invention has excellent chargeability, high sensitivity, surface potential even when used repeatedly,
Stable performance is obtained with little degradation of sensitivity.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a configuration example of a photoconductor of the present invention.

FIG. 2 is an X-ray diffraction spectrum of titanyl phthalocyanine used in Examples 11 and 12.

[Explanation of symbols]

 Reference Signs List 1 support 2 carrier generating layer 3 carrier transporting layer 4 photosensitive layer 5 intermediate layer 6 layer containing carrier transporting substance 7 carrier generating substance 8 protective layer

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) G03G 5/00 CA (STN) REGISTRY (STN)

Claims (1)

(57) [Claims] 1. An electrophotographic photoreceptor having a layer containing compounds represented by formulas (A), (B) and (D). Embedded image [Wherein R _{1 to} R ₄ represent a hydrogen atom, a halogen atom, an alkyl group, an aryl group, or an alkylamino group, and these groups may have a substituent. Ar ¹ and Ar ² are an aryl group,
Represents a heterocyclic group, and these groups may have a substituent.
R ₅ and Ar ³ represent an aryl group and may have a substituent. ]