JPH11269259A - Molding material for optical recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a molding material for optical recording media which exhibits low birefringence and high heat resistance by using a polycarbonate resin which has two kinds of structural units, the content of one kind being specified based on the total structural units, and has a specified intrinsic viscosity. SOLUTION: The polycarbonate resin has structural units represented by formulas I and II. the structural units of formula I accounting for 5-50 mol.% of the total structural units, and has an intrinsic viscosity of 0.30-0.50 dl/g. In formula I, R1 to R8 are each H, a halogen, 1-6C alkyl, 6-12C aryl, or the like. In formula II, Re to R16 are each H, a halogen, 1-6C alkyl, 6-12C aryl, or the like; Y is a group of formula III (wherein R17 to R20 are each H, a 1-6C alkyl, or the like, or R17 to R20 combine together to form a carbocycle or heterocycle); b, c, and d are each an integer of 0-20; and e and f are each an integer of 1-100.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polycarbonate resin having excellent heat resistance, moldability, etc. and reduced birefringence suitable for manufacturing optical recording media such as compact disks, laser disks, optical cards, MO disks and the like. The present invention relates to a molding material for an optical recording medium.

[0002]

2. Description of the Related Art Bisphenol A type polycarbonate resins have recently been widely used as base materials for optical disks, taking advantage of their characteristics such as transparency, heat resistance, hydrolysis resistance and dimensional stability. However, there are some problems when using polycarbonate for optical disks.

Of the performance as an optical disk substrate, birefringence, which substantially weakens a laser beam used for reading and writing information, is the most important problem. For a material having a large birefringence, errors increase, and as a recording medium, Is inferior in reliability.

[0004] Various polycarbonate resin materials have been developed for the purpose of reducing the birefringence. (JP 6
However, these birefringences cannot be said to be sufficient for optical discs with higher densities. Also, recently, it has been required to reduce birefringence at oblique incidence, which is difficult to improve under molding conditions.

Therefore, a polycarbonate-polystyrene copolymer (PC-PS) having reduced birefringence is disclosed in JP-A-2-29412. This PC-PS is greatly improved in birefringence as compared with the conventional one, but has the disadvantage that heat resistance is inferior to that of polycarbonate due to the use of PS. Further, in recent optical discs, pits are shortened, higher transferability is required, and shortening of molding time is required for mass productivity.
For this reason, there is a demand for a higher molding temperature than in the past.
-PS has a problem in heat resistance and its use is limited.

On the other hand, a modified polycarbonate resin having a structure derived from binaphthol as a polycarbonate resin is disclosed in JP-A-10-7782. However, although this modified polycarbonate resin was known as a wet molding material, its use as a molding material for optical recording media was not known.

[0007]

Means for Solving the Problems The present inventors have made intensive studies to solve the conventional problems, and as a result, a polycarbonate resin having a structure derived from a specific binaphthol has low birefringence and heat resistance. The present invention has been found to be a high-quality optical recording medium molding material having both of the above and has completed the present invention.

[0008]

DETAILED DESCRIPTION OF THE INVENTION That is, the present invention relates to a compound represented by the general formula (A):
And a polycarbonate having a structural unit represented by the general formula (B), wherein the structural unit of the general formula (A) is 5 to 50 mol% of all the structural units, and has an intrinsic viscosity of 0.30 to 0.50 dl / g. The present invention provides a molding material for an optical recording medium.

Embedded image (In the formula, R _{1 to} R ₈ each represent hydrogen, fluorine, chlorine,
Bromine, iodine, alkyl group having 1 to 6 carbon atoms, 6 to 6 carbon atoms
And 12 represents an aryl group, an alkenyl group having 2 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or an aralkyl group having 7 to 17 carbon atoms. )

Embedded image (Wherein, R _{9 to} R ₁₆ are each hydrogen, fluorine, chlorine,
Bromine, iodine, alkyl group having 1 to 6 carbon atoms, 6 to 6 carbon atoms
And 12 represents an aryl group, an alkenyl group having 2 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or an aralkyl group having 7 to 17 carbon atoms. Y is

Embedded image Wherein R _{17 to} R ₂₀ are each hydrogen and carbon number 1
Represents an alkyl group having 6 to 6 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms or an aryl group having 6 to 12 carbon atoms, or R _{17 to} R ₂₀ are bonded together to form a carbon ring Or a group that forms a heterocyclic ring. b, c, and d are 0 to
Integer of 20, e and f represent an integer of 1 to 100. )

Further, in the present invention, a polycarbonate resin having a molecular terminal derived from a monohydric phenol represented by the general formula (C) is preferable.

Embedded image (Wherein, R ₂₁ represents an alkyl group having 4 to 20 carbon atoms;
_{22 to} R ₂₃ each represent hydrogen, an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or an aryl group having 6 to 12 carbon atoms. g represents an integer of 0 or 1. )

The polycarbonate of the present invention can be produced by a known method used for producing a polycarbonate from bisphenol A, for example, a direct reaction of a bisphenol with phosgene (phosgene method), or a transesterification of a bisphenol with a diaryl carbonate. A method such as a reaction (ester exchange method) can be employed.

In the phosgene method and the transesterification method, the phosgene method is preferable in consideration of the reactivity of binaphthols which induce the structure of the general formula (A).

In the former phosgene method, bisphenols deriving the general formula (B), binaphthols deriving the general formula (A) in the present invention, and phosgene are usually reacted in the presence of an acid binder and a solvent. . Examples of the acid binder include pyridine and hydroxides of alkali metals such as sodium hydroxide and potassium hydroxide. Examples of the solvent include methylene chloride, chloroform, chlorobenzene, and xylene.
Further, a catalyst such as a tertiary amine such as triethylamine or a quaternary ammonium salt is used to promote the polycondensation reaction, and phenol or pt is used for controlling the degree of polymerization.
Monofunctional compounds such as butylphenol, p-cumylphenol and phenols represented by the general formula (C) are added as a molecular weight regulator. Further, if desired, a small amount of an antioxidant such as sodium sulfite or hydrosulfite or a branching agent such as phloroglucin or isatin bisphenol may be added. The reaction is usually carried out at a temperature of 0 to 150 ° C, preferably 5 to 40 ° C. The reaction time depends on the reaction temperature, but is usually 0.5 minutes to 10 minutes.
Time, preferably 1 minute to 2 hours. During the reaction, it is desirable to maintain the pH of the reaction system at 10 or more.

On the other hand, in the latter transesterification method, binaphthols deriving the general formula (A), bisphenols deriving the general formula (B) and diaryl carbonate are mixed and reacted at a high temperature under reduced pressure. At this time,
Monofunctional compounds such as phenol, pt-butylphenol, p-cumylphenol and phenols represented by the general formula (C) may be added as a molecular weight regulator. The reaction is usually carried out at a temperature in the range of 150 to 350 ° C., preferably 200 to 300 ° C., and the degree of reduced pressure is preferably 1 mmHg or less at the final stage of the reaction, and is derived from the diaryl carbonate formed by the transesterification reaction. Phenols are distilled out of the system. The reaction time depends on the reaction temperature and the degree of pressure reduction, but is usually about 1 to 4 hours. The reaction is preferably performed in an atmosphere of an inert gas such as nitrogen or argon. Further, if desired, the reaction may be carried out by adding an antioxidant or a branching agent.

The bisphenols derived from the general formula (B) used in the production of the polycarbonate in the present invention are specifically 4,4'-biphenyldiol, bis (4-hydroxyphenyl) methane, bis ( 4-hydroxyphenyl) ether, bis (4-hydroxyphenyl) sulfone, bis (4-hydroxyphenyl) sulfoxide, bis (4-hydroxyphenyl) sulfide, bis (4-hydroxyphenyl) ketone, 1,1-bis (4 -Hydroxyphenyl) ethane, 2,2-bis (4-hydroxyphenyl) propane (bisphenol A; BPA), 2,2-bis (4-hydroxyphenyl) butane, 1,1-bis (4-hydroxyphenyl) ) Cyclohexane (bisphenol Z; BPZ), 1,1-
Bis (4-hydroxyphenyl) -3,3,5-trimethylcyclohexane, 2,2-bis (4-hydroxy-3,5-dibromophenyl) propane, 2,2-bis (4-hydroxy-3,5- Dichlorophenyl) propane, 2,2-bis (4-hydroxy-3-
Bromophenyl) propane, 2,2-bis (4-hydroxy-
3-chlorophenyl) propane, 2,2-bis (4-hydroxy
-3-methylphenyl) propane, 2,2-bis (4-hydroxy-3,5-dimethylphenyl) propane, 1,1-bis (4-hydroxyphenyl) -1-phenylethane, bis (4-hydroxyphenyl) ) Diphenylmethane, α, ω-bis [2-
(P-hydroxyphenyl) ethyl] polydimethylsiloxane, α, ω-bis [3- (o-hydroxyphenyl) propyl] polydimethylsiloxane, and the like. These may be used in combination of two or more. Among these, 2,2-bis (4-hydroxyphenyl) propane is particularly preferred.

On the other hand, examples of the carbonate-forming compound include phosgene, diphenyl carbonate, and di-carbonate.
Bisallyl carbonates such as p-tolyl carbonate, phenyl-p-tolyl carbonate, di-p-chlorophenyl carbonate, and dinaphthyl carbonate are exemplified. These compounds can be used in combination of two or more.

Specific examples of the binaphthols derived from the general formula (A) include 1,1′-bi-2-naphthol, 6,
6'-dibromo-1,1'-bi-2-naphthol, 6,6'-dimethyl-1,1'-bi-2-naphthol, 6,6'-dichloro-1,1'-
Bi-2-naphthol, 6,6'-difluoro-1,1'-bi-2-naphthol, 3,3'-difluoro-1,1'-bi-2-naphthol, 3,3'-dimethyl-1 , 1'-bi-2-naphthol, 3,3'-
Dibromo-1,1'-bi-2-naphthol, 3,3'-di-t-butyl-1,1'-bi-2-naphthol, 5,5'-dimethyl-7,7'-diethyl-1 , 1′-Bi-2-naphthol, 6,6′-diphenyl-1,
1'-bi-2-naphthol, 6,6'-diallyl-1,1'-bi-2-
Naphthol and the like. These 1,1′-bi-2-naphthols may be used in combination of two or more. Although these 1,1'-bi-2-naphthols have optical isomers, any of R, S and racemic may be used. Among the 1,1′-bi-2-naphthols, from the viewpoint of reactivity and fluidity, 1,1′-bi-2-naphthol and 6,6′-dimethyl-1,1′-bi-2-naphthol. Is more preferred.

Further, as the molecular weight regulator of the present invention, monohydric phenols represented by the general formula (C), which are expected to be effective in improving fluidity, are preferred. Specifically, butylphenol, octylphenol, nonylphenol, decanylphenol And long-chain alkyl-substituted phenols such as tetradecanylphenol, heptadecanylphenol, and octadecanylphenol; such as butyl hydroxybenzoate, octyl hydroxybenzoate, nonyl hydroxybenzoate, decanyl hydroxybenzoate, and heptadecanyl hydroxybenzoate; Hydroxybenzoic acid long-chain alkyl esters are exemplified.

The polycarbonate polymer synthesized by these reactions can be molded by a known molding method such as extrusion molding, injection molding, blow molding, compression molding, or wet molding. It is desirable that extrusion and injection molding can be easily performed, and in particular, in the case of precision molding for optical recording media, the intrinsic viscosity is preferably in the range of 0.30 to 0.50 dl / g.

The structural unit of the general formula (A) of the present invention is one of all structural units in consideration of moldability, heat resistance and low birefringence.
The content is preferably 5 to 50 mol%, and particularly preferably 10 to 40 mol% in order to make heat resistance and low birefringence more clear. When the structural unit of the general formula (A) is less than 5 mol%, the birefringence becomes too large, and when it is 10 mol% or more, the effect of improving birefringence becomes more remarkable. If it exceeds 40 mol%, the molding conditions become narrow due to an increase in the glass transition temperature, so that molding defects and an increase in birefringence due to molecular orientation tend to occur. If it exceeds 50 mol%, injection molding becomes extremely difficult.

The polycarbonate resin of the present invention is a molding material for optical recording media having a high glass transition temperature and excellent heat resistance. However, if the glass transition temperature is too high, the fluidity is reduced. Decrease. The glass transition temperature is preferably 120 ° C. or more and 180 ° C. or less to show sufficient moldability, and is 170 ° C. or less to show good injection moldability, in order to exhibit heat resistance equivalent to or higher than that of conventional polycarbonate. .

The polycarbonate molding material for an optical recording medium of the present invention must be highly refined as in the case of a general polycarbonate for an optical disk. Specifically, dust having a diameter of 50 μm or more is substantially not detected, dust having a diameter of 0.5 to 50 μm is 3 × 10 ⁴ or less, inorganic and organic residual chlorine is 2 ppm or less, residual alkali metal is 2 ppm or less, and residual hydroxyl group Purification is performed so as to satisfy the criteria as low as possible, such as 200 ppm or less, residual nitrogen amount 5 ppm or less, residual monomer 20 ppm or less. In some cases, post-treatment such as extraction is performed to remove low molecular weight substances or remove solvents.

The polycarbonate molding material for an optical recording medium may be a hindered phenol-based or phosphite-based antioxidant; Lubricants and mold release agents such as ester, fatty acid, fatty acid glyceride, beeswax and other natural fats and oils; benzotriazole, benzophenone, dibenzoylmethane, and salicylate light stabilizers; polyalkylene glycol, fatty acid glyceride, etc. An antistatic agent or the like may be appropriately used in combination, and furthermore, it is possible to use it arbitrarily by mixing it with ordinary polycarbonate for optical recording media within the range that does not impair the performance in terms of cost and the like. The molding temperature when the present molding material is injection-molded is preferably 280 to 360 ° C from the viewpoint of fluidity.

[0023]

Next, the present invention will be described in more detail by way of examples, which should not be construed as limiting the present invention.

Example 1 1,1'- was added to 58 liters of 8.8% (w / v) aqueous sodium hydroxide solution.
Bi-2-naphthol 2.86kg (hereinafter abbreviated as BN1, 10mol)
2,2-bis (4-hydroxyphenyl) propane (hereinafter BPA
Abbreviation, 30mol) 6.84kg and hydrosulfite 10g
Was added and dissolved. To this was added 36 liters of methylene chloride, 375 g of pt-butylphenol (hereinafter abbreviated as PTBP, 2.5 mol) was added while stirring at 15 ° C., and then 5 kg of phosgene was blown in over 50 minutes. After the completion of the blowing, 5 g of triethylbenzylammonium chloride was added, and the mixture was vigorously stirred to emulsify the reaction solution. After emulsification, 20 ml of triethylamine was added, and the mixture was stirred for about 1 hour to carry out polymerization. After separating the polymerization solution into an aqueous phase and an organic phase, neutralizing the organic phase with phosphoric acid, and repeating washing with water until the conductivity of the washing solution becomes 10 μS or less,
A purified resin solution was obtained. The obtained purified resin liquid was slowly dropped into 45 ° C. hot water under vigorous stirring to solidify the polymer while removing the solvent. The solid was filtered and dried to obtain a white powdery polymer. This polymer had an intrinsic viscosity [η] of 0.37 dl / g at a temperature of 20 ° C. of a solution having a concentration of 0.5 g / dl using methylene chloride as a solvent. As a result of analyzing the obtained polymer from an infrared absorption spectrum, 1770 cm
Absorption by a carbonyl group in a position near ^-1, observed absorption by ether bond position near 1240 cm ^-1, to have a carbonate bond was confirmed. Also, 3650-3200
Almost no hydroxyl-derived absorption was observed at the position of cm ^-1 . Furthermore, absorption derived from a naphthalene ring was observed at around 780 cm ^-1 . The monomer in this polycarbonate is G
20ppm for both BN1 and BPA as measured by PC analysis
It was below. As a result of combining them, this polymer was recognized as a copolycarbonate polymer consisting of the following structural units.

[0025]

Embedded image

To the obtained polycarbonate powder, 300 ppm of stearic acid monoglyceride was added, and the mixture was treated with a vented 50 mm extruder equipped with a 50 μm polymer filter.
C. and extruded to form a melt pellet. The obtained pellets were obtained at a resin temperature of 350 ° C., a mold temperature of 100 ° C., and an injection pressure of 29.4 MPa, with an outer diameter of 120 mm and a thickness of 1.
A 2 mm disk was injection molded, and allowed to stand indoors for 2 days, and the birefringence at 30 ^° oblique incidence was measured. The glass transition temperature (Tg) of the extruded pellet was measured and used as a measure of heat resistance. Table 1 shows the results.

Example 2 BN1 was 4.58 kg (16 mol), BPA was 5.47 g (24 mol), PT
The procedure was performed in the same manner as in Example 1 except that BP was changed to 825 g (2.5 mol) of p-heptadecanylphenol. Table 1 shows the results. The intrinsic viscosity [η] of the obtained polymer was 0.36 dl / g, and it was confirmed by infrared absorption spectrum analysis and the like that this polymer was a copolycarbonate polymer having the following structural units.

[0028]

Embedded image

Example 3 Instead of BN1, 2.51 kg of 6,6′-dimethyl-1,1′-bi-2-naphthol (hereinafter abbreviated as BN2, 8 mol) was used, and BPA was 7.3 kN.
The procedure was performed in the same manner as in Example 1 except that g (32 mol) was used. Table 1 shows the results. The intrinsic viscosity [η] of the obtained polymer was 0.35 dl / g, and this polymer was recognized as a copolycarbonate polymer having the following structural unit from an infrared absorption spectrum or the like.

[0030]

Embedded image

Example 4 Instead of BN1, 1.26 kg (4 mol) of BN2 and 8.21 kg of BPA
(36 mol) was conducted in the same manner as in Example 1.
Table 1 shows the results. The intrinsic viscosity [η] of the obtained polymer is
At 0.35 dl / g, a copolycarbonate polymer having the same structural units as in Example 3 except for the copolymerization ratio was recognized.

Example 5 Instead of PTBP, 310 g of n-butyl p-hydroxybenzoate
(Hereinafter abbreviated as PHBB, 1.6 mol) was carried out in the same manner as in Example 1. Table 1 shows the results. The intrinsic viscosity [η] of the obtained polymer was 0.49 dl / g, and the polymer was recognized as a copolycarbonate polymer having the following structural unit from infrared absorption spectra and the like.

[0033]

Embedded image

Example 6 BPA was 4.56 kg (20 mol), BN1 was 2.86 kg (10 mol), 2,
2-bis (4-hydroxy-3-methylphenyl) propane 2.
The procedure was performed in the same manner as in Example 1 except that 56 kg (hereinafter, abbreviated as DMBPA, 10 mol) was used. Table 1 shows the results. The intrinsic viscosity [η] of the obtained polymer was 0.37 dl / g, and the polymer was recognized as a copolycarbonate polymer having the following structural unit from an infrared absorption spectrum or the like.

[0035]

Embedded image

Comparative Example 1 A BPA type polycarbonate for optical recording media (H-4000 manufactured by Mitsubishi Gas Chemical Co., Ltd., [η] = 0.35 dl / g) was used in place of the polycarbonate of Example 1. The same test was performed. Table 1 shows the results.

COMPARATIVE EXAMPLE 2 A polycarbonate-polystyrene copolymer for commercial optical recording media (ODX manufactured by Mitsubishi Gas Chemical Co., Ltd., [η] = 1.08 dl / g) was used in place of the polycarbonate of Example 1. The same test as in Example 1 was performed. Table 1 shows the results.

Comparative Example 3 The procedure of Example 1 was repeated except that BPA was changed to 4.1 kg (18 mol) and BN1 was changed to 6.29 kg (22 mol). Table 1 shows the results. The intrinsic viscosity [η] of the obtained polymer was 0.38 dl / g. From the infrared absorption spectrum and the like, this polymer was recognized as a copolycarbonate polymer having the same structural units as in Example 1 except for the polymerization ratio. .

[0039]

[Table 1] Oblique birefringence (nm) Heat resistance Appearance BN concentration Intrinsic viscosity Distance from center Glass transition temperature mol% dl / g R = 24mm R = 42mm R = 56mm ℃ ─────────── ──────────────────────── Actual 1 25 0.37 18 12 13 156 Good Actual 2 40 0.36 11 8 9 150 〃 Actual 3 20 0.35 20 15 21 150 〃 Actual 4 10 0.36 31 23 25 149 〃 Actual 5 25 0.49 17 11 14 149 〃 Actual 6 25 0.37 20 13 12 152 〃比 Ratio 1 0.35 92 75 90 143 Good Ratio 2 1.08 22 16 15 113 Bubble generation ratio 3 55 0.38------171 Poor filling ─────── ────────────────────────────

(Measurement method) Birefringence: using an automatic ellipsometer manufactured by Mizojiri Optical Industry Co., Ltd.
Measurement wavelength 632.8nm. Glass transition temperature: Measured by DSC manufactured by Shimadzu Corporation. BN concentration: ratio of general formula (A) structural unit to all structural units (mol%) Intrinsic viscosity: 0.5 g / 100 cc dichloromethane resin solution at 20 ° C.
The intrinsic viscosity [η] (dl / g) was determined with a Huggins constant of 0.45.

[0041]

According to the present invention, it is possible to provide a molding material for an optical recording medium having excellent heat resistance, moldability and low birefringence. In particular, it is suitable for rewritable optical disks and magneto-optical disks that require high-density recording and reliability.

────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] April 9, 1998

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0003

[Correction method] Change

[Correction contents]

[0003]

Among the performances of an optical disk substrate, birefringence, which substantially weakens a laser beam used for reading and writing information, is the most important problem. Increase
The reliability as a recording medium is inferior.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hideki Watanabe 2--12 Kanshucho, Toyonaka-shi, Osaka Mitsubishi Gas Chemical Co., Ltd. Osaka factory

Claims (5)

[Claims] 1. It has a structural unit represented by the general formula (A) or (B), wherein the structural unit of the general formula (A) is 5 to 50 mol% of all the structural units, and the intrinsic viscosity is 0.30-0.50dl
A molding material for an optical recording medium, comprising a polycarbonate resin of / g. Embedded image (In the formula, R _{1 to} R ₈ each represent hydrogen, fluorine, chlorine,
Bromine, iodine, alkyl group having 1 to 6 carbon atoms, 6 to 6 carbon atoms
And 12 represents an aryl group, an alkenyl group having 2 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or an aralkyl group having 7 to 17 carbon atoms. ) (Wherein, R _{9 to} R ₁₆ are each hydrogen, fluorine, chlorine,
Bromine, iodine, alkyl group having 1 to 6 carbon atoms, 6 to 6 carbon atoms
And 12 represents an aryl group, an alkenyl group having 2 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or an aralkyl group having 7 to 17 carbon atoms. Y is Wherein R _{17 to} R ₂₀ are each hydrogen and carbon number 1
Represents an alkyl group having 6 to 6 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms or an aryl group having 6 to 12 carbon atoms, or R _{17 to} R ₂₀ are bonded together to form a carbon ring. Or a group that forms a heterocyclic ring. b, c, and d are 0 to
Integer of 20, e and f represent an integer of 1 to 100. ) 2. The structural unit represented by the general formula (A) is represented by 1,
1'-bi-2-naphthol, 6,6'-dimethyl-1,1'-bi-2-
The molding material for an optical recording medium according to claim 1, which is derived from naphthol. 3. The method according to claim 1, wherein the structural unit represented by the general formula (B) is 2,2-
The molding material for an optical recording medium according to claim 1, which is derived from bis (4-hydroxyphenyl) propane. 4. The molding material for an optical recording medium according to claim 1, wherein the structural unit represented by the general formula (A) accounts for 10 to 40 mol% of all structural units. 5. The molding material for an optical recording medium according to claim 1, wherein the molecular terminal is derived from a monohydric phenol represented by the general formula (C). Embedded image (Wherein, R ₂₁ represents an alkyl group having 4 to 20 carbon atoms;
_{22 to} R ₂₃ each represent hydrogen, an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or an aryl group having 6 to 12 carbon atoms. g represents an integer of 0 or 1. )