JPH08254842A - Electrophotographic organic photoreceptor - Google Patents

Abstract

PURPOSE: To provide an electrophotographic org. photoreceptor maintaining stable characteristics even after use over a long period of time and stably giving s satisfactory image. CONSTITUTION: At least one of compds. represented by formulae I-III or a mixture of at least one of the compds. with at least one among Vitamin E group, Vitamin K group, etc., is incorporated as an antioxidant into the electric charge transferring layer of a function separated laminate type photoreceptor or the photosensitive layer of a single layer type photoreceptor. In the formulae I-III, each of R<1> -R<8> is H, hydroxyl, acetyl, alkoxy, optionally substd. alkyl, optionally substd. benzoyl, optionally substd. aryl, an optionally substd. arom. group or an optionally substd. arom. heterocyclic group. In this case, at least one of some compds. is suitable for use as an electric charge transferring material.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic organic photoconductor used in electrophotographic printers, copying machines and the like, and more particularly to an antioxidant contained in its photosensitive layer.

[0002]

2. Description of the Related Art An electrophotographic photosensitive member used in an electrophotographic printer, a copying machine or the like has a structure in which a photosensitive layer containing a photoconductive material is laminated on a conductive substrate. Conventionally, as the photoconductive material, Se, Se alloy, CdS,
Although inorganic materials such as ZnS have been widely used, organic materials have attracted attention due to the variety of materials and the advantages such as high productivity, heat stability, and safety due to the fact that a photosensitive layer can be formed by a coating method. The development and practical application of so-called organic photoconductors having a photosensitive layer containing an organic photoconductive material have been actively pursued. Among them, a so-called function-separated laminate type organic photoreceptor in which a photosensitive layer is divided into a charge generation layer that receives light and generates charge carriers and a charge transport layer that transports the generated charge carriers, is called By forming and combining materials suitable for each function, there is a possibility that electrophotographic characteristics such as sensitivity can be greatly improved.Also, select an appropriate material according to the wavelength of exposure light. It has become a mainstream of development because it has many advantages such as increased spectral sensitivity.

However, the organic photoconductors currently put into practical use have problems such as a decrease in charge potential, an increase in residual potential, and a decrease in sensitivity when used for a long time under practical conditions. Some of these causes can be external factors. That is, the photoconductor is exposed to ozone generated by corona discharge in the image forming process,
Exposure to strong external light at the time of equipment maintenance, etc. are mentioned. The influence of these external factors on the above-mentioned various characteristics can be confirmed by an experimental method such as leaving the photoconductor in an ozone atmosphere or irradiating the photoconductor with a strong light of a predetermined light amount.

In order to solve the above problems, attempts have been made to add various materials known as antioxidants and ultraviolet absorbers to the photosensitive layer.

[0005]

However, the present situation is that a technique capable of completely solving all of the above problems has not been established yet. The present invention has been made in view of the above circumstances, and an object thereof is to provide an organic photoconductor for electrophotography, which has stable characteristics even when used for a long period of time and which can stably obtain a good image. And

[0006]

According to the present invention, there is provided the above object of providing an electrophotographic organic photoreceptor comprising a photosensitive layer having an organic material as a main component on a conductive substrate. The problem is solved by providing an organic photoconductor for electrophotography, which contains as an antioxidant at least one of compounds represented by the following general formulas (I) to (III) and structural isomers thereof.

[0007]

[Chemical 13]

[Formulas (I), (II) and (III)]
Wherein R ^{1 to} R ⁸ are a hydrogen atom, a hydroxyl group, an acetyl group, an alkoxy group, a substituted or unsubstituted alkyl group, a benzoyl group, an aryl group, an aromatic group, an aromatic heterocyclic group,
Represents any of the following. It is preferable that the photosensitive layer contains at least one of the compounds represented by the following general formulas (IV) to (VIII) as a charge transport material.

[0009]

Embedded image

[In the formula (IV), R ^{9 to} R ¹³ are hydrogen atoms,
Substituted or unsubstituted alkyl group, aryl group,
It represents any one of an amino group, an aromatic group, and an aromatic heterocyclic group. ]

[0011]

[Chemical 15]

[In the formulas (V) to (VII), R ^{14 to} R ²⁸ represent any one of a hydrogen atom, a halogen atom, a hydroxyl group, a substituted or unsubstituted alkyl group and an amino group, and n Represents an integer of 0 to 4. ]

[0013]

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[In the formula (VIII), R ^{29 to} R ^{39 each} represent a hydrogen atom, a substituted or unsubstituted alkyl group or an alkoxy group below, and n represents an integer of 0 to 4. Further, in the photosensitive layer, a compound represented by the following general formulas (IX) to (XX), vitamin E, is further added as an antioxidant.
It is preferable that at least one of the group and the vitamin K group is contained.

[0015]

[Chemical 17]

[In the formula (IX), R ⁴⁰ represents any one of a hydrogen atom, an alkyl group, the following phenyl group which may have a substituent and an aralkylamino group, and R ⁴¹ represents a substituent. It represents a phenyl group which may have or a naphthyl group which may have a substituent. ]

[0017]

Embedded image

[In the formulas (X) and (XI), R ^{42 to} R ⁴⁵
Represents a hydrogen atom or a substituted or unsubstituted alkyl group. ]

[0019]

[Chemical 19]

[In the formula (XII), R ⁴⁶ and R ⁴⁷ represent a substituted or unsubstituted alkyl group or a substituted or unsubstituted alkoxy group. ]

[0021]

Embedded image

[In the formula (XIII), R ^{48 to} R ⁵¹ represent a hydrogen atom or a substituted or unsubstituted alkyl group. ]

[0023]

[Chemical 21]

[In the formula (XIV), R ⁵² represents any one of a hydroxyl group, an alkoxy group which may have a substituent and a benzoyloxy group which may have a substituent. ]

[0025]

[Chemical formula 22]

[In the formula (XV), R ⁵³ represents a substituted or unsubstituted alkyl group or a substituted or unsubstituted aryl group, and R ^{54 to} R ⁵⁶ represent a substituted or unsubstituted alkyl group. ]

[0027]

[Chemical formula 23]

[In the formula (XVI), R ⁵⁷ and R ⁵⁸ represent any of the following substituted or unsubstituted alkyl groups, aryl groups and sulfenyl groups. ]

[0029]

[Chemical formula 24]

Specific examples of the compound represented by the above general formula (I) include the following compounds (I-1-1) to (I-6-).
9) can be mentioned.

[0031]

[Chemical 25]

Specific examples of the compound represented by the general formula (II) include the following compounds (II-1-1) to
(II-4-7) can be mentioned.

[0033]

[Chemical formula 26]

Further, specific examples of the compound represented by the above general formula (III) include the following compound (III-1-
1) to (III-6-6).

[0035]

[Chemical 27]

Specific examples of the compounds represented by the above general formulas (IV) to (VIII) used as the charge transport material include the following compounds (IV-1).
~ (IV-10), (V-1) to (V-8), (VI-
1) to (VI-8), (VII-1) to (VII-1)
0) and (VIII-1) to (VIII-16).

[0037]

[Chemical 28]

[0038]

[Chemical 29]

[0039]

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[0040]

[Chemical 31]

[0041]

Embedded image

[0042]

[Chemical 33]

[0043]

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[0044]

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[0045]

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[0046]

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[0047]

[Chemical 38]

[0048]

[Chemical Formula 39]

Specific examples of the compounds represented by the above general formulas (IX) to (XVI) include the following compounds (IX-1) to (IX-6) and (X-1) to (X), respectively. −
8), (XI-1) to (XI-4), (XII-1) to
(XII-4), (XIII-1) to (XIII-
4), (XIV-1) to (XIV-4), (XV-1)
To (XV-2) and (XVI-1) to (XVI-3).

[0050]

[Chemical 40]

[0051]

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[0052]

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[0053]

[Chemical 43]

[0054]

[Chemical 44]

[0055]

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FIGS. 1, 2 and 3 are schematic sectional views showing the photoconductors of various structures according to the present invention. FIG.
Is a negative-charge function-separated laminated type photoreceptor, in which a photosensitive layer 2a in which a charge generation layer 3 containing a charge generation material 5 and a charge transport layer 4 containing a charge transport material 6 are sequentially laminated on a conductive substrate 1 is formed. It has a different configuration. FIG. 2 shows a positive charging function-separated layered type photoreceptor in which a photosensitive layer 2b in which a charge transport layer 4 containing a charge transport material 6 and a charge generating layer 3 containing a charge generating material 5 are sequentially laminated on a conductive substrate 1. It has a formed structure. In this structure, the coating layer 7 is provided on the thin charge generation layer 3 to protect it. Further, FIG. 3 shows a positively charged single-layer type photosensitive member in which a photosensitive layer 2c containing a mixture of a charge generating material 5 and a charge transporting material 6 is formed on a conductive substrate 1.

In the case where the photoreceptor has the photosensitive layer 2a shown in FIG. 1, the antioxidant of the present invention may be added to the charge transport layer 4. In addition, the photosensitive member is the photosensitive layer 2 shown in FIG.
Also in the case of the structure including b, the antioxidant of the present invention may be added to the charge transport layer 4. Further, in the case where the photoconductor has a structure including the photosensitive layer 2c shown in FIG. 3, the antioxidant of the present invention may be added to the entire photosensitive layer 2c.

In the photoconductor of the present invention, the conductive substrate is, for example, a cylinder made of an aluminum alloy or an aluminum vapor-deposited film, or one having an anodized film or a resin film formed on the surface thereof for surface decoration. Is used. As the resin film material used for surface decoration,
Insulating polymers such as casein, polyvinyl alcohol, polyamide, melanin, cellulose, polythiophene,
Examples thereof include conductive polymers such as polypyrrole and polyaniline, and those obtained by incorporating metal oxide powder and low molecular weight compounds into these polymers.

The charge generating layer comprises a charge generating material and a resin binder. As the charge generating material, the following compounds (X
XI-1) to (XXI-26).

[0060]

Embedded image

[0061]

[Chemical 47]

[0062]

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[0063]

[Chemical 49]

[0064]

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As the resin binder for the charge generation layer,
Polycarbonate, polyester, polyamide, polyurethane, epoxy, polyvinyl butyral, polyvinyl acetal, phenoxy resin, silicone resin, acrylic resin, vinyl chloride resin, vinylidene chloride resin, vinyl acetate resin, homer resin, cellulose resin, and their polymers, or These halides and cyanoethyl compounds are mentioned.

The charge transport layer comprises a charge transport material and a resin binder. As the charge transport material, the compound (IV
-1) to (IV-10) various hydrazone compounds and their derivatives, (V-1) to (V-8) various butadiene compounds and their derivatives, (VI-1) to
Various amine compounds and their derivatives shown in (VI-8), Various styryl compounds and their derivatives shown in (VII-1) to (VII-10), (VIII-1) to
The various distyryl compounds and their derivatives shown in (VIII-16) can be used alone or in combination as a mixture. Further, as the resin binder for the charge transport layer, the following (XXII-1) to (XX
Various polycarbonates, polystyrenes, polyphenylene ether acrylic resins and the like shown in II-6) can be used.

[0067]

[Chemical 51]

[0068]

By incorporating at least one of the compounds represented by the general formulas (I) to (III) in the photosensitive layer, oxidative deterioration of the photosensitive member when exposed to an ozone atmosphere,
Or to prevent photoreaction degradation when exposed to strong light,
Alternatively, the progress of these deteriorations can be significantly delayed. At this time, as the charge transport material contained in the photosensitive layer, at least one of the compounds represented by the general formulas (IV) to (VIII) is suitable. Further, at least one of the compounds represented by the general formulas (IX) to (XX), the vitamin E group, and the vitamin K group is added to the photosensitive layer, and the compound is represented by the above general formulas (I) to (III). By using in combination with at least one kind of compound, it becomes possible to further suppress the deterioration.

[0069]

Embodiments of the present invention will be described below.
A cylinder made of an aluminum alloy having an outer diameter of 60 mm, a length of 310 mm and a wall thickness of 1 mm is washed and dried to be cleaned, and then a polyamide having a number average molecular weight of 100,000 (manufactured by Daicel-Huls Co., Ltd.) is provided on the outer peripheral surface thereof. "T171") 4 parts by weight and styrene-maleic acid resin (BASF Japan Lt.
d. Product name: "Suprapearl AP") 1 part by weight is dissolved in a mixed solvent of 200 parts by weight of methanol and 100 parts by weight of 1-butanol to prepare a resin film coating solution, which is applied by dip coating to form a resin having a film thickness of 0.1 μm. A conductive film is formed by forming a film.

On this conductive substrate, 5 parts by weight of the metal-free phthalocyanine shown in the above (XXI-1) as a charge generating material, polyvinyl acetal as a resin binder (manufactured by Sekisui Chemical Co., Ltd .; trade name "ESREC KS-" 1 ") 5
By weight, 700 parts by weight of dichloromethane was mixed, and the coating liquid prepared by kneading with a mixer for 3 hours was applied by dip coating to form a charge generation layer having a thickness of 0.3 μm.

On this charge generation layer, 500 parts by weight of the compound shown in (VIII-1) above as a charge transport material and the bisphenol A type-biphenyl copolymer polycarbonate shown in (XXII-5) above as a resin binder (Idemitsu) Kosan Co., Ltd .; trade name "BP-Pc") 1000 parts by weight, antioxidant (main agent) 1 shown in the above (I-5-1)
A coating solution prepared by dissolving 0 part by weight and 5 parts by weight of the antioxidant (additive) shown in the above (XII-1) in 7,000 parts by weight of dichloromethane is applied by dip coating to form a charge transport layer having a film thickness of 20 μm. Then, it was used as a photoconductor.

Example 2 In Example 1, the antioxidant (additive) (XII-
A photoconductor was produced in the same manner as in Example 1 except that 1) was not used. Example 3 In Example 1, the antioxidant (main agent) was added to the above (II-
A photoreceptor was produced in the same manner as in Example 1 except that the compound (2-2) was replaced with the antioxidant (additive) replaced with the compound (XIII-2).

Example 4 In Example 3, the antioxidant (additive) (XIII-
A photoconductor was produced in the same manner as in Example 3 except that 2) was not used. Example 5 In Example 1, the antioxidant (main agent) was added to the above (III
-1-3), except that the antioxidant (additive) was replaced with the compound (IX-2).
A photoconductor was prepared in the same manner as in.

Example 6 In Example 5, the antioxidant (additive) (IX-2)
A photoconductor was produced in the same manner as in Example 5 except that the above was not used. Example 7 In Example 1, the antioxidant (main agent) was added to the above (II-
Example 1 except that the antioxidant (additive) was replaced with the compound of (XIV-3) above instead of the compound of 1-2).
A photoconductor was prepared in the same manner as in.

Example 8 In Example 1, the antioxidant (main agent) was added to the above (III
A photoconductor was prepared in the same manner as in Example 1 except that the compound (1-2) was replaced with the antioxidant (additive) replaced with the compound (XIV-2). Example 9 In Example 1, the resin binder of the coating liquid for the charge transport layer was the above-mentioned (XXII-2) (bisphenol Z type polycarbonate (manufactured by Mitsubishi Gas Chemical Co., Inc .; trade name “PCZ3”.
A photoconductor was prepared in the same manner as in Example 1 except that it was replaced with "00")).

Example 10 In Example 3, the resin binder of the coating liquid for the charge transport layer was (XXII-2) (bisphenol Z type polycarbonate (manufactured by Mitsubishi Gas Chemical Co., Inc .; trade name "PCZ3".
A photoconductor was prepared in the same manner as in Example 3, except that the photoconductor was replaced with "00")).

Comparative Example 1 A photoconductor was prepared in the same manner as in Example 1 except that the antioxidant (main agent) and the antioxidant (additive) were not used. Comparative Example 2 A photoconductor was prepared in the same manner as in Example 7, except that the antioxidant (main agent) and the antioxidant (additive) were not used in Example 7.

Comparative Example 3 Example 2 was repeated except that the compound (I-5-1) as the antioxidant (main agent) in Example 2 was replaced with di-t-butyl-hydroxytoluene (BHT). A photoconductor was prepared in the same manner. Comparative Example 4 In the same manner as in Example 7, except that the compound (II-1-2) as the antioxidant (main agent) in Example 7 was replaced with di-t-butyl-hydroxytoluene (BHT). A photoconductor was prepared.

Comparative Example 5 Example 8 was repeated except that the compound (III-1-2) as the antioxidant (main agent) in Example 8 was replaced with di-t-butyl-hydroxytoluene (BHT). A photoconductor was prepared in the same manner. The electrophotographic characteristics of the photoconductors of Examples and Comparative Examples obtained as described above were evaluated. For the purpose of evaluating potential fluctuations during continuous use, each photoconductor was mounted on a semiconductor laser printer with fixed output of the charging mechanism, the exposure mechanism, and the static elimination mechanism, and was kept at room temperature and normal humidity (temperature 20 ° C, relative humidity 60%). A3 in the atmosphere
A running test of printing on 50,000 sheets of paper is performed, and the light potential V _w and the dark potential V _b at the start and end of the running are measured respectively, and the potential changes ΔV _w , ΔV
_b was evaluated. Further, for the purpose of evaluating ozone resistance, each photoconductor was exposed to an atmosphere having an ozone concentration of 100 ppm for 4 hours, and the half-attenuation exposure amount before and after the exposure was measured. Further, for the purpose of evaluating the resistance to strong light fatigue, each photoconductor is irradiated with white light of 1000 lux for 1 hour, and the charge potential V _s before and after the irradiation under a constant charging condition is measured, and the charging is performed. The amount of change ΔV _s was evaluated. Table 1 shows the results.

[0080]

[Table 1]

As can be seen from Table 1, the photoconductors of Comparative Examples 1 and 2 which did not contain the antioxidant of the present invention showed a marked deterioration in electrophotographic characteristics due to exposure to ozone or strong light irradiation, and The potential fluctuation due to the running test deviates from the practical range. Further, comparing Example 1 with Comparative Example 3, Example 7 with Comparative Example 4, and Example 8 with Comparative Example 5, respectively, it can be seen that the use of the antioxidant of the present invention has made it possible to use it as an antioxidant. It can be seen that the increase in the residual potential after the running test and the change in the potential before and after the strong light fatigue test can be suppressed as compared with the case of using BHT which is present.

Further, by comparing Example 1 and Example 2, Example 3 and Example 4, and Example 5 and Example 6 respectively, among the compounds represented by the above general formulas (I) to (III), At least one of them as an antioxidant (main agent), the compounds represented by the general formulas (IX) to (XX), the vitamin E group,
By using at least one of the vitamin K group in combination as an antioxidant (additive), the electrons represented by formulas (I) to (III) can be used more effectively as compared with the case of using the compound alone as an antioxidant. It can be seen that the photographic characteristics are improved.

Further, comparing Example 1 and Example 9 and Example 3 and Example 10, respectively, when bisphenol A type-biphenyl copolymerized polycarbonate is used as the resin binder of the charge transport layer, excellent stability is obtained. I understand. As described above, the function-separated laminated type photoconductor having the configuration shown in FIG. 1 has been exemplified, but the present invention is not limited to this structure, and the function-separated laminated type photoconductor having the configuration shown in FIG. The same effect can be obtained by including the same antioxidant in the charge transport layer, and in the case of the single-layer type photoreceptor having the structure shown in FIG. 3, the same antioxidant is used in the entire photosensitive layer. By including it, the same effect can be obtained.

[0084]

According to the present invention, the compound represented by the general formula (1) is used as an antioxidant in the charge transport layer of the photosensitive layer of the function-separated laminated type organic photoreceptor or in the entire photosensitive layer of the single-layer type organic photoreceptor. By incorporating at least one of the compounds represented by formulas (I) to (III),
At least one compound represented by formula (III), a compound represented by formulas (IX) to (XX), and vitamin E
Group, and at least one kind of vitamin K group are combined and mixed to obtain an organic photoconductor for electrophotography, which has stable characteristics even when used for a long period of time and can stably obtain a good image. be able to. In this case, it is preferable to use at least one of the compounds represented by the general formulas (IV) to (XIII) as the charge transport material.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing the configuration of an embodiment of a photoconductor according to the present invention.

FIG. 2 is a schematic cross-sectional view showing the constitution of another embodiment of the photoconductor according to the present invention.

FIG. 3 is a schematic cross-sectional view showing the constitution of still another embodiment of the photoconductor according to the present invention.

[Explanation of symbols]

 1 Conductive Substrates 2a, 2b, 2c Photosensitive Layer 3 Charge Generation Layer 4 Charge Transport Layer 5 Charge Generation Material 6 Charge Transport Material 7 Coating Layer

Claims (3)

[Claims] 1. An organic photoconductor for electrophotography comprising a photosensitive layer containing an organic material as a main component on a conductive substrate, wherein the photosensitive layer contains an antioxidant represented by the following general formulas (I) to (III). An organophotoreceptor for electrophotography, characterized in that it contains at least one of the compounds shown in and the structural isomers thereof. Embedded image [In Formulas (I), (II) and (III), R ^{1 to} R ⁸
Represents any one of a hydrogen atom, a hydroxyl group, an acetyl group, an alkoxy group, a substituted or unsubstituted alkyl group, a benzoyl group, an aryl group, an aromatic group, and an aromatic heterocyclic group. ] 2. The electrophotographic apparatus according to claim 1, wherein the photosensitive layer contains at least one of the compounds represented by the following general formulas (IV) to (VIII) as a charge transport material. Organic photoconductor. Embedded image [In the formula (IV), R ^{9 to} R ¹³ represent any one of a hydrogen atom, a substituted or unsubstituted alkyl group, an aryl group, an amino group, an aromatic group, and an aromatic heterocyclic group. ] [Chemical 3] [In formulas (V) to (VII), R ^{14 to} R ^{28 each} represent a hydrogen atom, a halogen atom, a hydroxyl group, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted amino group, and n Represents an integer of 0 to 4. ] [Chemical 4] [In the formula (VIII), R ^{29 to} R ^{39 each} represent a hydrogen atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted alkoxy group, and n represents an integer of 0 to 4. ] 3. The photosensitive layer further contains at least one of compounds represented by the following general formulas (IX) to (XX), a vitamin E group, and a vitamin K group as an antioxidant. The organic photoconductor for electrophotography according to claim 1, which is characterized in that. Embedded image [In the formula (IX), R ⁴⁰ represents any one of a hydrogen atom, an alkyl group, a phenyl group which may have a substituent and an aralkylamino group which may have a substituent, and R ⁴¹ represents It represents either a phenyl group which may have a substituent or a naphthyl group which may have a substituent. ] [Chemical 6] [In the formulas (X) and (XI), R ^{42 to} R ⁴⁵ represent a hydrogen atom or a substituted or unsubstituted alkyl group. ] [Chemical 7] [In the formula (XII), R ⁴⁶ and R ⁴⁷ represent a substituted or unsubstituted alkyl group or a substituted or unsubstituted alkoxy group. ] [Chemical 8] [In the formula (XIII), R ^{48 to} R ⁵¹ represent a hydrogen atom or a substituted or unsubstituted alkyl group. ] [Chemical 9] [In the formula (XIV), R ⁵² represents any one of a hydroxyl group, an alkoxy group which may have a substituent and a benzoyloxy group which may have a substituent. ] [Chemical formula 10] [In the formula (XV), R ⁵³ represents a substituted or unsubstituted alkyl group or a substituted or unsubstituted aryl group, and R ⁵⁴
~ R ⁵⁶ represents a substituted or unsubstituted alkyl group. ] [Chemical 11] [In the formula (XVI), R ⁵⁷ represents a substituted or unsubstituted alkyl group, and R ⁵⁸ represents any of the following substituted or unsubstituted alkyl group, aryl group, and sulfenyl group. ] [Chemical formula 12]