JPH073585B2 - Electrophotographic photoconductor - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a composite type electrophotographic plate effective for image formation by electrophotography, and particularly to a charge transport layer excellent in durability (wear resistance) and resolution life. The present invention relates to a composite electrophotographic board having the same.

[Background of the Invention]

In electrophotographic copying and electrostatic recording, the latent image by corona discharge, toner development, toner image transfer, and cleaning of the transfer surface are repeated, so the electrophotographic plate surface has excellent abrasion resistance and electrophotographic characteristics. It is required that there is little change with time.

Regarding abrasion resistance, a protective layer such as a silicone oil release layer, a cellulosic resin layer, a vinyl resin layer, a silicone resin layer, a fluorine resin layer, and / or an insulating layer has been conventionally proposed. . However, these are made as thin as possible from the viewpoint of not impairing the electrophotographic characteristics, and are therefore susceptible to mechanical wear and damage, and also susceptible to chemical deterioration in the corona electric field. Further, the electrophotographic characteristics, such as the image quality, are deteriorated and satisfactory durability is not obtained. Further, forming the protective layer or the insulating layer on the charge transport layer itself always involves the problems of abrasion and interfacial delamination, and the cost increases as the number of layers increases.

[Object of the Invention]

An object of the present invention is to overcome the drawbacks of the prior art and to provide a practicable composite electrophotographic plate.

[Outline of Invention]

The present invention relates to a composite type electrophotographic plate having a charge generating layer and a charge carrier layer laminated on a conductive support, and the materials constituting the charge carrier layer are represented by the general formulas [I] and [II]. It is characterized in that a unit polymerization substance is added alone or in combination.

General formula [I] [In the formula, R ₁ represents an alkyl group having 4 or less carbon atoms, and R ₂ represents a phenyl group or a vinyl group. ] General formula [II] [In the formula, R ₁ represents an alkyl group having 4 or less carbon atoms, and R ₂ represents a phenyl group or a vinyl group. ] In a composite type electrophotographic plate, it is simple to have two layers, a charge generation layer and a charge transport layer, and the durability of the surface charge transport layer determines the life of the electrophotographic plate. It becomes an important factor to do.

The charge-transporting layer is mainly composed of a charge-transporting substance, a binder resin and an additive. The point of the present invention is to add the above specific polysiloxane as an additive. Experimental results regarding improvement of electrophotographic characteristics, improvement of durability such as abrasion resistance, improvement of workability for layer formation, etc. by the inventors' additives, many polysiloxanes are found to be effective in surface lubricity such as abrasion resistance. However, in many cases, the sensitivity of electrophotographic characteristics is particularly lowered and the residual potential is increased. Among polysiloxanes, amino-modified, carboxy-modified, epoxy-modified, epoxy-polyether-modified, ester-modified, alkyd-modified, styrene-modified polysiloxane, etc. have a large decrease in sensitivity, and when repeatedly used as a photoreceptor, the photoreceptor remains with time. The electric potential tends to increase. On the other hand, the polysiloxane described in the claims of the present invention greatly improves electrophotographic characteristics and durability. further,
Conveniently, when the charge carrier material in the form of paint is applied to the conductive support, repellency of the coated surface is prevented and the leveling effect of smoothing the coated surface is extremely large.

The above general formula [I] and / or [II] in the present invention
The addition ratio of the polysiloxane represented by is 0.001 to 5% by weight based on the total solid content of the charge transport layer, preferably
0.01-2% by weight is used. If the amount added is less than this range, the effects of abrasion resistance, chemical resistance, moisture resistance, coating film forming property, etc. will be reduced. On the other hand, if the amount added exceeds this range, the adhesiveness at the interface with the charge generation layer tends to decrease, and the sensitivity of electrophotographic characteristics tends to decrease.

Next, as the styryl dye used in the present invention, a compound represented by the following formula is particularly desirable.

Where X is and A heterocyclic group selected from (wherein Z is O or S)
And the heterocyclic group may be substituted),
n is 0, 1 or 2, and R ₄ and R ₅ have 3 carbon atoms.
It is the following alkyl groups. The substituent of such heterocyclic _{groups, -CH 3, -C 2 H 5} , a lower alkyl group such as -C ₃ H _7, -Cl, halogen group such as -Br, -N (CH _{3) 2} , −N (C _{2
H 5) 2, -N (C} 3 H 7) dialkylamino group such as _2, -OCH _3,
Examples thereof include, but are not limited to, an alkoxy group such as —OC ₂ H ₅ and a phenyl group.
Some of such compounds are listed below by structural formula.

The method for synthesizing the compound is described in JP-B-35-11218.
It is described in detail in Japanese Examined Patent Publication No. 35-11219, etc., and most of these compounds are obtained from Japan Photosensitive Dye Research Institute, Inc.
Commercially available as NK dye.

The reason why the combination of the charge-generating substance and the charge-transporting substance as in this example is preferable is not clear, but known charge-transporting substances such as pyrazoline derivatives, hydrazone compounds, triphenylmethane compounds, triphenylamine, 2 Compared with 4,4,7-trinitrofluorenone, etc., it has a relatively small ionization potential and is difficult to crystallize, and it is easy to mix with other binder resins and a strong and uniform coating film is easily obtained. To be In particular, since high sensitivity is exhibited at the time of negative charging, it is expected that the hole injection from the charge generating substance to the charge carrier substance is efficiently performed.

In addition to the styryl dye, the charge carrier substance may be a polymer having a carbazole ring such as poly-N-vinylcarbazole or poly-9-p-vinylphenylanthracene showing photoconductivity, a polymer having an anthracene ring in its side chain, or pyrazoline. A polymer having a ring, another hetero ring such as dibenizomophoene ring, or an aromatic ring in its side chain may be used in combination. Furthermore, cyanine dye bases, oxazole derivatives, oxadiazole derivatives, pyrazoline derivatives, hydrazone compounds, poly-N-vinylcarbazole, triphenylmethane compounds, triphenylamine compounds, 2,4,7-trinitro. It is also possible to use a known photoconductive low molecule such as nitrofluorenone such as fluorenone together and mix it in a general-purpose resin to form a charge transport layer. As a typical example of the oxazole derivative, Etc. Examples of cyanine dye bases that can be used in the present invention are: Is mentioned. Oxadiazole derivatives are for example Is. Pyrazoline derivatives are for example (Where X is H, -OCH ₃₎ it is.

Although these compounds can form the charge transport layer by themselves and exert their effects, they are mixed with other polymer compounds in order to improve the strength, flexibility and adhesiveness of the coating film. Can be used to increase the effect.

The type of such a polymer compound is not particularly limited, and known binder resins for electrophotographic plates, such as acrylic resin, polyester resin, polystyrene resin, epoxy resin, silicone resin, polycarbonate resin and polyester carbonate resin, phenol resin. , Urea resin, melamine resin, furan resin, urethane resin, fibrin derivative, etc. are appropriately selected and used.

Phthalocyanine can be used as the charge generating substance in the present invention. Especially τ type, τ ′ type, η type, η ′
A metal-free phthalocyanine such as a mold is preferable.

The τ type metal-free phthalocyanine is defined as follows. That is, the Bragg angle (2θ ± 0.2 degrees) is 7.6,9.2,16.8,17.
It has a strong X-ray diffraction pattern at 4,20.4 and 20.9. Especially when the infrared absorption spectrum is between 700 and 760 cm ^-1
751 ± 2 cm ^-1 is the strongest four absorption bands, 1320 ~ 1340 cm
Between two ⁻¹ absorption bands of approximately the same strength, 3288 ± 3 cm ⁻¹
Those having absorption characteristic to are desirable.

The τ ′ type metal-free phthalocyanine is defined as follows.
That is, the Bragg angle (2θ ± 0.2 degrees) is 7.5,9.1,16.8,17.3,20.3,20.8,2 for 1.541Å X-ray of CuKα ₁ / Ni.
It is a novel metal-free phthalocyanine crystal polymorph with strong X-ray diffraction patterns at 1.4 and 27.4. In particular, the infrared absorption spectrum is strongest 753 ± 2 cm ^-1 between 700~760cm ^-1 4
It is desirable to have two absorption bands between 1320-1340 cm ⁻¹ and two absorption bands of approximately the same intensity, and a characteristic absorption at 3297 ± 3 cm ⁻¹ .

The η type metal-free phthalocyanine is defined as follows. That is, 100 parts by weight of a metal-free phthalocyanine, a metal-free phthalocyanine having a substituent in the benzene nucleus, a phthalocyanine nitrogen analog having a substituent in the benzene nucleus, or a mixture of one or more of the metal phthalocyanines 50.
A mixture crystal with the following parts by weight, the absorption band of 753 ± cm ^-1 strongest four between the infrared absorption spectrum 700～760Cm ^-1, approximately the same two between 1320～1340Cm ^-1 The absorption band of strength has a characteristic absorption at 3285 ± 5 cm ⁻¹ . According to the study by the present inventor, the η type metal-free phthalocyanine has a Bragg angle (2θ ± 0.2 degrees) of 7.6, 9.2, 16.8,
Those having an X-ray diffraction pattern showing strong peaks at 17.4 and 28.5 and those having an X-ray diffraction pattern showing strong peaks at 7.6, 9.2, 16.8, 17.4, 21.5 and 27.5 are mentioned.

The η'type metal-free phthalocyanine is defined as follows.
That is, 100 parts by weight of a metal-free phthalocyanine, a metal-free phthalocyanine having a substituent in the benzene nucleus, a phthalocyanine nitrogen homostructure which may have a substituent in the benzene nucleus, or a mixture of one or more of the metal phthalocyanines.
50 is a mixture crystal with the following parts by weight, a 753 ± 1 cm ^-1 strongest four absorption bands between the infrared absorption spectrum 700～760Cm ^-1, almost two during 1320～1340Cm ^-1 It is a novel metal-free phthalocyanine crystalline polymorph with an absorption band of the same intensity at 3297 ± 5 cm ⁻¹ . According to the study by the present inventor, the η′-type metal-free phthalocyanine has a Bragg angle (2θ ± 0.2 degrees) of 7.5,9.1,16.8,17.3,20.3,20.
Those having an X-ray diffraction pattern showing strong peaks at 8,21.4 and 27.4, and 7.5,9.1,16.8,17.3,20.3,20.8,21.4,22.1,2
Those having an X-ray diffraction pattern showing strong peaks at 7.4 and 28.5 are desirable.

It should be noted that the τ-type, τ′-type, η-type, and η′-type metal-free phthalocyanines each have a maximum value in the photosensitive wavelength range of 790 to 810 nm.

The τ-type and τ′-type metal-free phthalocyanines that can be used in the present invention are produced in the following manner. That is, by stirring the α-type metal-free phthalocyanine at a temperature of 50 to 180 ° C., preferably 60 to 130 ° C. for a time sufficient for crystal conversion, or by milling with a mechanical strain force, a τ ′ type crystal form is obtained. A metal-free phthalocyanine having is prepared.

α-type phthalocyanine is a “phthalocyanine compound” of Moser and Thomas (Moser and Thomes “Phthalocyani”).
ne Compounds ") and other suitable methods are used. For example, metal-free phthalocyanines are metal phthalocyanines that can be demetallated with acids such as sulfuric acid, such as lithium phthalocyanine and sodium phthalocyanine. , Those obtained by acid treatment of metal phthalocyanine containing calcium phthalocyanine, magnesium phthalocyanine, etc., or directly from phthalodinitrile, aminoiminoisoindolenin or alkoxyiminoisoindolenin are used. The metal-free phthalocyanine obtained by the well-known method is dissolved in sulfuric acid at 5 ° C. or lower, or a sulfate salt is poured into water or ice water to reprecipitate or hydrolyze the α-type metal-free metal. Phthalocyanine is obtained.

At this time, when an inorganic pigment dissolved or dispersed in sulfuric acid or a reprecipitation solution is used, α-type metal-free phthalocyanine containing the inorganic pigment can be obtained. As the inorganic pigment, any water-insoluble powder may be used as a colorant filler, for example, titanium white, zinc white carbon, calcium carbonate, and the like, which are used in various fields as powder, for example, metal. Examples include powder, alumina, iron oxide powder, kaolin and the like.

The α-type metal-free phthalocyanine containing this inorganic pigment is extremely easy to be ground and easily made into fine particles when it is made into a pigment, as compared with the one not containing it, and it is effective in saving labor and energy.

The α-type metal-free phthalocyanine treated in this way is preferably used in a dry state, but a water-paste type can also be used. The dispersion medium for stirring and kneading may be one normally used for dispersion of pigments, emulsification and mixing, and examples thereof include glass beads, steel beads, alumina balls, and flint stones. However, distributed media is not always necessary. As the grinding aid, those usually used as a grinding aid for pigments may be used, and examples thereof include common salt, sodium bicarbonate, and sodium sulfate. However, this grinding aid is not always necessary.

If a solvent is needed for stirring, kneading, and grinding, stir,
It may be liquid at the temperature during kneading, for example, alcohol solvent such as glycerin, ethylene glycol, diethylene glycol or polyethylene glycol solvent, ethylene glycol monomethyl ether,
It is preferable to select one or more kinds from the group of cellosolve-based solvents such as ethylene glycol monoethyl ether, ketone-based solvents, ester ketone-based solvents and the like.

A typical stirring device such as a homomixer is a typical device used in the crystal transition step.
There are day parsers, agitators, stirrers or kneaders, Banbury mixers, ball mills, sand mills, attritors and the like.

The temperature range in the crystal transition step is 50 to 180 ° C, preferably 60 to 130 ° C. Further, it is also an effective method to use crystal nuclei as in the ordinary crystal transition process.

The α-type phthalocyanine used in producing the η-type and η′-type metal-free phthalocyanine usable in the present invention and a metal-free phthalocyanine having a substituent in the benzene nucleus, or a phthalocyanine nitrogen having a substituent in the benzene nucleus. The same structure or metal phthalocyanine is the "phthalocyanine compound" (Moser and Thomas) described above.
and Thomes "Phthalocyanine Compounds") and those obtained by known methods and other suitable methods are used. For example, α-type metal-free phthalocyanine can be obtained by the same formulation as described above, which may contain other inorganic pigment. Further, as the phthalocyanine nitrogen isotope, various porphines, for example, copper tetrapyridinoporphyrazine in which one or more of the benzene nucleus of phthalocyanine is replaced with a quinoline nucleus, and the like, and as the metal phthalocyanine, copper, nickel, Various materials such as cobalt, zinc, tin and aluminum can be mentioned.

As the substituent, there are an amino group, a nitro group, an alkyl group, an alkoxy group, a cyano group, a mercapto group, a halogen atom, and the like, and a sulfonic acid group, a carboxylic acid group or a metal salt thereof, an ammonium salt, an amine salt, or the like. Can be illustrated as being relatively simple. Further, various substituents can be introduced into the benzene nucleus through an alkylene group, a sulfonyl group, a carbonyl group, an imino group, etc., which are conventionally known as an aggregation inhibitor or a crystal conversion inhibitor in the technical field of phthalocyanine pigments. (See, for example, USP3973981 and U.S. Pat. No. 4088507) or unknown. As for the method of introducing each substituent, a known method is omitted. Moreover, what is not publicly known is described as a reference example in an Example.

The mixing ratio of the α-type metal-free phthalocyanine and the metal-free phthalocyanine having a substituent in the benzene nucleus, or the phthalocyanine nitrogen analogue having a substituent in the benzene nucleus or the metal phthalocyanine is 100/50 (weight ratio) or more. It may be present, but is preferably 100/30 to 100 / 0.1 (weight ratio). Above this ratio, the η-type and η′-type phthalocyanines obtained tend to bleed and the suitability as a pigment decreases.

In order to mix the above-mentioned proportions, they may be simply mixed, or may be mixed before the α-type metal-free phthalocyanine is acid-base coated. The method of stirring or milling the mixture thus mixed may be those usually used for dispersing, emulsifying, mixing, etc. of pigments, and examples of the dispersing medium for stirring and kneading include glass beads, steel beads, alumina balls, flint. Stones,
Distributed media is not necessary.

The grinding aid is a solvent at the time of kneading, the material used in the crystal transition step, and the apparatus is the same as in the above-mentioned τ-type and τ′-type metal-free phthalocyanine.

The temperature range in the crystal transition step of the η-type and η′-type metal-free phthalocyanine is 30 to 220 ° C., preferably 60 to 130 ° C. At higher temperatures, the β-type transition is likely to occur, and at lower temperatures, the η-type and η′-type transitions take a long time. Further, it is also an effective method to use crystal nuclei as in the ordinary crystal transition process.

In addition to the above τ type, τ ′ type, η type, or η ′ type metal-free phthalocyanine, the use of other charge generating substances is also included. Examples of such a charge generating substance include α
Type, β type, γ type, or X type metal-free phthalocyanine. Of course, the combined use of τ type metal-free phthalocyanine and η type metal-free phthalocyanine is also effective. It is also effective to use a phthalocyanine pigment, an azo pigment, an anthraquinone pigment, an indigoid pigment, a quinacridan pigment, a beryllene pigment, a polycyclic quinone pigment, a methine squaric acid methine pigment and the like which are known as a charge generating substance. As examples of azo pigments, (In the formula, X represents OCH ₃ or Cl), or a disazo pigment such as (In the formula, M represents Ca, Mg or Ba.).

Example of Invention

Example 1 τ-type phthalocyanine pigment (manufactured by Toyo Ink Mfg. Co., Ltd.) 1
Parts by weight and silicone resin (KR5240, Shin-Etsu Chemical Co., Ltd.) 3
Part by weight was made into a 2.5 wt% solution with a tetrahydrofuran solvent and dispersed and mixed by ultrasonic waves for 2 hours to obtain a charge generating substance, and this coating solution was dip coated on an aluminum foil having a film thickness of 100 μm. The pulling speed during dip coating is 15 mm / sec. This was dried to form a layer of charge generating material (charge generating layer). The film thickness of this layer is about 0.7 μm.

Next, a charge carrier substance having the following structural formula and a polycarbonate resin (Teijin Kasei: K1285) as a binder resin in a weight ratio.
The mixture was mixed at a ratio of 1: 3 to prepare a 10 wt% solution of methylene chloride / 1,1,2 trichloroethane = 6/4 (volume ratio). Further, at this time, the methylphenyl polysiloxane in the present invention is 0 to 7% by weight with respect to the charge carrier substance and the binder resin.
Each coating liquid added so as to obtain

This coating solution was applied onto the above charge generating substance layer by a dip coating method and dried at 100 ° C. for 2 hours to obtain an electrophotographic plate. The coating film thickness including all layers was 15 μm.

The electrophotographic photosensitive member of the composite type constituted by this example was evaluated for electrophotographic characteristics by using an electrostatic recording paper test device (SP-428 manufactured by Kawaguchi Electric Co., Ltd.). In this case, negative 5k
V corona discharge is performed for 10 seconds to charge (the surface potential V ₀ (V) immediately after charging for 10 seconds is the initial potential) and left in the dark for 30 seconds (the potential at this time is V ₃₀ (V)) Represent, (V ₃₀ /
V ₀ ) × 100 (%) is used as dark decay) Exposure was performed with a tungsten lamp so that the surface illuminance was 2 lux, the decay of the surface potential at this time and the time were recorded until V ₃₀ became 1/2. White light sensitivity (half-exposure amount, product of time t (seconds) and illuminance
E ₅₀ (lux · s)) was represented.

At the same time, the appearance finish and wear resistance of the surface were evaluated. The evaluation method of wear resistance is 5 mm thickness × 30 mm width ×
Ground the edge of a 20 mm long urethane blade at an angle of 45 ° to the surface of the electrophotographic board, and weigh 60 g on the ground.
The wear of the surface was evaluated by applying a load of and reciprocating the stroke of 60 mm. The wear rate was expressed as the wear rate after traveling 50,000 times.

The results are shown in Table 1.

As a result, the electrophotographic properties tended to deteriorate in initial potential, dark decay and sensitivity when the amount of methylphenylpolysiloxane added was 5% or more. On the other hand, as for the wear resistance, the larger the amount added, the better the result obtained.

Example 2 In a charge generation layer obtained in the same manner as in Example 1, 1 part by weight of a charge carrier substance having the following structural formula and 3 parts by weight of a saturated polyester resin (Vylon 200, manufactured by Toyobo Co., Ltd.) were added to 20 parts by weight of tetrahydrofuran. A dissolved coating solution was prepared, and methylphenylvinylpolysiloxane was added in an amount of 0 to 5 in the same manner as in Example 1.
An electrophotographic plate was obtained by applying the coating liquid added so that the amount of the electrophotographic plate would be wt%.

The electrophotographic characteristics and abrasion resistance of these electrophotographic plates were examined. The results are shown in Table 2.

Example 3 The charge generation layer obtained in the same manner as in Example 1 was mixed with 1 part by weight of a charge carrier having the following structural formula and 3 parts by weight of a polycarbonate resin (US GE; Lexan 141-111) in 1,1,2 trichloro. An electrophotographic plate was obtained by dissolving it in 20 parts by weight of ethane and applying a coating solution containing 0 to 5% by weight of methylphenylpolysiloxane. The coating thickness including all layers is 15 μm.

Regarding the electrophotographic plate thus obtained, Example 1
Repeated charging-exposure tests were conducted using the electrostatic recording paper test apparatus described in Section 1 above to evaluate the image quality before and after the test.

The electrification-exposure conditions were negative electrification 5 kV, 10 seconds, dark decay 10 seconds, exposure was a tungsten lamp with surface illuminance 2lux, and exposure time was 5 seconds. This was set as one cycle, and 1000 cycles were tested. Regarding the electrophotographic plate before and after the test, the test chart No. 1-R, 19 published by the Electrophotographic Society was manually developed.
75 resolutions were evaluated. The results are shown in the figure.

As a result, the resolution was good up to 2.0% by weight as compared with the one without addition of methylphenylpolysiloxane, and 3% gave the same result as that without addition. If importance is attached to the resolution, 0.05 to 2.0% by weight is optimal.

In addition, instead of τ type metal-free phthalocyanine, τ ′ type, η type,
Example 3 except that each metal-free phthalocyanine of η'type was used
Electrophotographic photoconductors were obtained in the same manner as above, and the electrophotographic characteristics of each were good, as in Example 3.

〔The invention's effect〕

According to the present invention, there is an effect that an electrophotographic photoreceptor having excellent surface abrasion resistance can be obtained.

[Brief description of drawings]

FIG. 1 is an electrophotographic characteristic diagram of an electrophotographic photoconductor according to an embodiment of the present invention.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁶ Identification number Reference number within the agency FI Technical indication location G03G 5/06 371 9221-2H (72) Inventor Takashi Onishi 1-1-1 Higashitaga-cho, Hitachi-shi, Ibaraki No. 1 Hitachi Ltd. Taga Factory (72) Inventor Masatsugu Ogata 3-1-1, Saiwaicho, Hitachi City, Ibaraki Hitachi Ltd. Hitachi Research Laboratory (72) Inventor Hiroyoshi Ogaku Yukiko Hitachi, Ibaraki Prefecture 3-1-1 Machi, Hitachi Research Laboratory, Hitachi Ltd. (72) Inventor Shigeo Suzuki 3-1-1, Saiwaicho, Hitachi City, Ibaraki Hitachi Ltd. Hitachi Research Laboratory (72) Inventor Shigemasa Takano Tokyo 2-33 Kyobashi, Chuo-ku, Tokyo Toyo Inki Manufacturing Co., Ltd. (72) Inventor Manabu Sawada 2-3-3, Kyobashi, Kyobashi, Chuo-ku, Tokyo Toyo Inki Manufacturing Co., Ltd. (56) Reference JP-A-57-212453 (JP, A) JP-A-57-5050 (JP, A) JP-A-49-84447 (JP, A) JP-A-55-140849 (JP, A) JP-A-50-17842 (JP, A) JP-A-49-90934 (JP, A)

Claims (1)

[Claims] 1. An electrophotographic photoreceptor comprising a charge generation layer and a charge transport layer laminated on a conductive support, wherein the material constituting the charge transport layer is represented by the general formulas [I] and [II]. The basic substance is added alone or in combination, and the addition amount of the polymeric substance is 0.05 to 2.0% by weight based on the total solid content of the material constituting the charge transport layer. The charge-transporting substance therein is a compound represented by the general formula [III], and the charge-generating substance in the charge-generating layer is τ type,
A photoconductor for electrophotography, which is a τ ′ type, η type, or η ′ type metal-free phthalocyanine. General formula [I] [In the formula, R ₁ represents an alkyl group having 4 or less carbon atoms, and R ₂ represents a phenyl group or a vinyl group. ] General formula [II] [In the formula, R ₁ represents an alkyl group having 4 or less carbon atoms, and R ₂ represents a phenyl group or a vinyl group. ] General formula [III] [Where X is A heterocyclic group selected from (wherein Z represents O or S, and the heterocyclic group may be substituted), and m
Represents 0, 1 or 2, and R ₄ and R ₅ represent an alkyl group having 3 or less carbon atoms. ]