JPH04226531A - Polyamide resin, its production, 5-alkoxy-isophthalic acid and its production - Google Patents

Abstract

PURPOSE:To obtain a polyamide resin having excellent heat-resistance, solubility in organic solvent, film-forming property and formability and suitable as an electronic insulation material by using an aromatic diamine and a 5- alkoxyisophthalic acid (derivative) as starting materials. CONSTITUTION:A polyamide resin composed of the recurring unit of formula II and having a reduced viscosity of 0.2-5/g can be produced by the polycondensation reaction of an aromatic diamine of formula I (e.g. m- tolylenediamine) and a 5-alkoxyisophthalic acid (derivative) of formula II (R is 1-30C straight or branched-chain alkyl; X is hydroxyl, halogen, etc.) (e.g. 5-n-hexyloxyisophthalic acid). The 5-alkoxyisophthalic acid of formula V (R' is n-C6H13, etc.) is produced by reacting 5-hydroxyisophthalic acid of formula IV with an alkyl halide of formula R'-X (X is halogen).

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a new polyamide resin and a method for producing the same, as well as a 5-alkoxyisophthalic acid and a method for producing the same.

0002

[Prior Art] Fully aromatic polyamides synthesized from aromatic diamines and aromatic dicarboxylic acids have excellent heat resistance and electrical and mechanical properties, and are used as electrical insulating materials, high-temperature materials, and certain types of materials. It is used in a wide range of industrial materials, including materials for protective clothing.

0003

However, this type of aromatic polyamide has poor solubility in ordinary organic solvents, which is extremely inconvenient when forming fibers, films, coatings, etc. Moreover, since such aromatic polyamides have a high melting point and high crystallinity, injection molding or extrusion molding is virtually impossible. The present inventor has developed a polyamide resin that has excellent heat resistance, solubility in organic solvents, film formability, and mechanical properties, and has good moldability in injection molding, extrusion molding, etc., a method for producing the same, and 5-alkoxyisophthalic acid and The present invention provides a method for producing the same.

0004

[Means for Solving the Problems] The present invention provides general formula (I)

[Image Omitted] [In the formula, Ar represents a divalent residue of an aromatic diamine excluding the amino group, and R represents a linear or branched alkyl group having 1 to 30 carbon atoms.] The present invention relates to a polyamide resin having units.

The present invention also provides general formula (II)

[Chemical 9] H2N-Ar-NH2
(II) [In the formula, Ar represents the same thing as in the general formula (I)] The aromatic diamine represented by the general formula (III)

[Formula R represents the same as in general formula (I),
represents a hydroxy group, a halogen atom, or an alkoxy group having 1 to 4 carbon atoms. The present invention relates to a method for producing a polyamide resin having units.

The present invention also provides general formula (IV)

[Chem.11
] [In the formula, R' is n-C6H13, n-C11H23, n-
C12H25 or n-C18H37].

The present invention also provides general formula (V)

5-hydroxyisophthalic acid represented by the general formula (VI
)

[Chemical formula 13] R'-X
(VI) [In the formula, R' is the general formula (
The general formula (IV) is the same as in IV), and is characterized in that it is reacted with a halogenated alkyl represented by [X represents a halogen atom]

embedded image This invention relates to a method for producing 5-alkoxyisophthalic acid represented by the formula [wherein R' is the same as defined above].

The polyamide resin of the present invention has the general formula (
It has a repeating unit represented by I). Ar in the general formula (I) is a divalent residue of an aromatic diamine excluding the amino group, and the aromatic diamine is exemplified by the aromatic diamine represented by the general formula (II) below. I can give you what I did. General formula (I)
The number of carbon atoms of the straight chain or branched alkyl group R in is,
The number is from 1 to 30, preferably from 6 to 18. 3
When it exceeds 0, heat resistance decreases. Examples of the alkyl group include methyl group, ethyl group, n-propyl group,
Isopropyl group, n-butyl group, sec-butyl group, t
ert-butyl group, pentyl group, isopentyl group, hexyl group, heptyl group, octyl group, 2-ethylhexyl group, nonyl group, decyl group, undecyl group, dodecyl group,
Examples include octadecyl group, eicosyl group, triacontyl group, and the like.

[0009] The polyamide resin having a repeating unit represented by the general formula (I) has a reduced viscosity of 0.2 to 5.0 dl at 30°C of a solution obtained by dissolving 0.2 g of the resin in dimethylformamide to make 100 ml. /g is preferred. If this viscosity is too low, the mechanical strength of the resin tends to decrease, and if it is too high, the solubility of the resin in organic solvents tends to be poor.

[0010] In this specification, reduced viscosity (ηSP
/c) is determined by the following equation.

[Equation 1] [In the formula, η and η0 represent the viscosity of the solution and the viscosity of the solvent, respectively, and the flow times of the solution and solvent when measured using an Ubbelohde dilution type capillary viscometer are t and t, respectively.
0, η/η0=t/t0, and c is the resin concentration (g/dl) of the solution].

The polyamide resin of the present invention has N-methyl-
It dissolves well in polar solvents such as 2-pyrrolidone, dimethylacetamide, and dimethylformamide.

In the polyamide resin of the present invention, for example, the aromatic diamine represented by the general formula (II) can be combined with the aromatic diamine represented by the general formula (I).
It can be produced by polycondensation with 5-alkoxyisophthalic acid represented by II) or a derivative thereof.

Examples of the aromatic diamine represented by the general formula (II) include m-tolylene diamine, m-phenylene diamine, p-phenylene diamine, 5-chloro-
m-phenylenediamine, 4,4'-diaminodiphenyl ether, 3,3'-dimethyl-4,4'-diaminodiphenyl ether, 3,3'-dimethoxy-4,4'
-diaminodiphenyl ether, 3,3'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 4,4'-benzidine, 4,4'-diaminodiphenylthioether, 3,3'-diaminodiphenylthioether, 4,4'- Diaminobenzophenone, 3,
3'-diaminodiphenylmethane, 4,4'-diaminodiphenylmethane, 2,2'-bis(4-aminophenyl)propane, 2,2'-bis(3-aminophenyl)
Propane, 4,4'-diaminodiphenylsulfone, 4
, 4'-diaminodiphenylsulfoxide, 3,3'-
Diaminodiphenylsulfone, 3,3'-diaminobiphenyl, 1,3-bis(4-aminophenoxy)benzene, 1,3-bis(3-aminophenoxy)benzene,
1,4-bis(4-aminophenoxy)benzene, 4,
4'-[1,3-phenylenebis(1-methylethylidene)], 4,4'-[1,4-phenylenebis(1-methylethylidene)], 2,2-bis[4-(4-amino phenoxy)phenyl]propane, 2,2-bis[3-
Methyl-4-(aminophenoxy)phenyl]propane, 2,2-bis[3-chloro-4-(4-aminophenoxy)phenyl]propane, 1,1-bis[4-(4-
aminophenoxy)phenyl]ethane, bis[4-(4
-aminophenoxy)phenyl]methane, 3,3'-dimethoxy-4,4'-diaminobiphenyl, bis[4-
(4-aminophenoxy)phenyl]sulfone, bis[
4-(3-aminophenoxy)phenyl]sulfone, 2
,2-bis[4-(3-aminophenoxy)phenyl]
Propane, 4,4'-bis(4-aminophenoxy)biphenyl, 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane, 9,9-bis(
Examples include 4-aminophenyl)fluorene.

In addition to the aromatic diamines mentioned above, aliphatic diamines such as hexamethylene diamine and ethylene diamine, 1,3-bis(3-aminopropyl)tetramethyldisiloxane, 1,3-bis(4-aminophenyl) A siloxane diamine such as tetramethyldisiloxane may be used in combination as a diamine component, but in that case, it is preferably used in an amount of 30 mol % or less based on the total diamine. If there are too many of these, heat resistance tends to decrease.

[0015] Examples of the 5-alkoxyisophthalic acid in the 5-alkoxyisophthalic acid or its derivative represented by the general formula (III) include 5-n-hexyloxyisophthalic acid and 5-n-dodecyloxyisophthalic acid. , 5-n-octadecyloxyisophthalic acid and the like. 5-Alkoxyisophthalic acids are described in J. Po
lym. Sci. Part A-1, 7 volumes 3020 (
It can be produced according to the method described in (1969). Examples of these 5-alkoxyisophthalic acid derivatives include dihalides such as dichloride and dibromide, and diesters such as methyl ester and ethyl ester. The number of carbon atoms in the alkoxy group (the alkoxy group in X in general formula (III)) in the diester must be 1 to 4. When the number of carbon atoms is greater than 4, reactivity decreases.

Some of the 5-alkoxyisometallic acids represented by the general formula (III) and their derivatives are 5-alkoxyisophthalic acids represented by the general formula (IV).

Although the method for producing 5-alkoxyisophthalic acid represented by the general formula (IV) is not particularly limited, the following preparation method is preferred. That is, the general formula (V
)

5-hydroxyisophthalic acid represented by
Sulfuric acid, p-toluenesulfone in a lower alcohol such as ethanol (in order to increase the reaction temperature, a high boiling point, non-reactive, compatible solvent such as 1,2-dichloroethane may be mixed to the same volume as the alcohol). Using an acid catalyst such as an acid, the reaction is carried out at a temperature ranging from room temperature to the reflux temperature of the organic solvent used, and the general formula (VII) is obtained.

It can be a diester represented by the formula [wherein R'' represents a methyl group or an ethyl group].

Next, this ester and general formula (VI)

[Chemical formula 17] R'-X
(VI) [In the formula, R' is the same as in general formula (IV), and X represents a halogen atom] is dissolved in potassium carbonate or the like in an aprotic polar solvent such as acetone. Using a base,
The reaction was carried out at a temperature ranging from room temperature to the reflux temperature of the organic solvent used, and the general formula (VIII)

It can be a 5-alkoxyisophthalic acid diester represented by the following formula: [wherein R' has the same meaning as in general formula (IV), and R'' has the same meaning as in general formula (VII)].

Next, this 5-alkoxyisophthalic acid diester is dissolved in water using a strong base such as potassium hydroxide.
The reaction is carried out at a temperature ranging from room temperature to the reflux temperature of water, and the general formula (IV)

A 5-alkoxyisophthalic acid represented by the formula [wherein R' is the same as defined above] can be obtained.

As the dicarboxylic acid component, the general formula (I
II) together with 5-alkoxyisophthalic acid or its derivatives, terephthalic acid, isophthalic acid, 4,4
'-diphenyl ether dicarboxylic acid, 4,4'-diphenylcarboxylic acid, 1,5-naphthalene dicarboxylic acid,
Aromatic dicarboxylic acids such as 2,6-naphthalene dicarboxylic acid may also be used. These are preferably used in an amount of 50 mol % or less based on the total carboxylic acid components. If this amount is too large, the solubility in organic solvents tends to decrease. In addition, as a dicarboxylic acid component, aliphatic dicarboxylic acids such as adipic acid and sebacic acid are added to the total carboxylic acid component.
It may be used in an amount of 0 mol% or less. Too much aliphatic dicarboxylic acid tends to reduce heat resistance.

The aromatic diamine represented by the above general formula (II) and the 5-alkoxyisophthalic acid or its derivative represented by the above general formula (III) are polycondensed, and the polycondensation method is as follows: There is no particular restriction, and for example, a low temperature polycondensation method, a direct polycondensation method, an active ester method, etc. can be employed.

When employing the low temperature polycondensation method, preferably the dihalide of 5-alkoxyisophthalic acid represented by the general formula (III) is added to 1 equivalent of the aromatic diamine represented by the general formula (II). Use 0.9 to 1.2 equivalents of triethylamine, propylene oxide, styrene oxide,
In the presence of an acid acceptor such as 1,2-epoxide such as cyclohexene oxide, in a non-reactive polar solvent such as N-methyl-2-pyrrolidone or dimethylacetamide, the temperature ranges from -10-odd degrees Celsius to the reflux temperature of the organic solvent used. The reaction can be carried out at temperatures ranging up to

[0023] Furthermore, when employing the direct polycondensation method,
Aromatic diamine represented by general formula (II) and general formula (I
5-alkoxyisophthalic acid represented by II) is used in an equivalent or nearly equivalent amount, a phosphorus catalyst such as triphenyl phosphite, phosphorus trichloride, condensed phosphoric acid ester, and pyridine or a non-reactive polar solvent similar to the above. The reaction can be carried out at a temperature ranging from room temperature to the reflux temperature of the organic solvent used. In this case, the phosphorus catalyst is used in an equivalent or approximately equivalent amount to the dicarboxylic acid or the aromatic diamine, and the pyridine or organic solvent is used in an amount of 10 mol% or more based on the dicarboxylic acid or the aromatic diamine. preferable.

When the active ester method is adopted, a benzotriazyl ester is produced by reacting the dihalide of 5-alkoxyisophthalic acid represented by the general formula (III) with 1-hydroxybenzotriazole. The ester and the aromatic diamine represented by the above general formula (II) can be used in equivalent or nearly equivalent amounts, and the reaction can be carried out in the same non-reactive polar organic solvent as described above at room temperature or higher temperature.

[0025] The reaction solution obtained by either method is poured into a large excess of a lower alcohol such as methanol or a solvent that is compatible with the above organic solvent such as water and is a poor solvent with respect to the resin. Obtain a precipitate. The polyamide resin of the present invention can be recovered by filtering this and drying it.

The polyamide resin of the present invention has aliphatic side chains, and due to its bulk, it has much better solubility in organic solvents than conventional aromatic polyamides, and is resistant to other solvents. Like soluble resins, it can be formed into films, coatings, etc. by the casting method, and these films, coatings, etc. exhibit excellent heat resistance and mechanical properties, and are useful as electronic insulating materials and heat resistance. Suitable for use as adhesives and high temperature materials.

[0027]

[Examples] Next, the present invention will be explained by examples.

Example 1 100 g of 5-hydroxyisophthalic acid was placed in a three-necked flask equipped with a Liebig condenser and a thermometer.
(0.55 mol), methanol 300 ml, 1
, 300 ml of 2-dichloroethane and 50 ml of sulfuric acid were added and suspended. When the suspension was heated and stirred, 5-hydroxyisophthalic acid was completely dissolved. The mixture was heated under reflux for one day, and after the reaction was completed, methanol was distilled off under reduced pressure, and the precipitated white solid was dissolved in diethyl ether. This diethyl ether solution was washed with a saturated aqueous sodium bicarbonate solution and saturated brine, and dried over anhydrous magnesium sulfate. The solvent was distilled off under reduced pressure, and the obtained white crystals were purified by recrystallization (methanol/hexane) to obtain 5-hydroxyisophthalic acid dimethyl ester. Yield 104.1g Yield 90.2%

002
9] Next, add 5-hydroxyisophthalic acid dimethyl ester 5 to a three-necked flask equipped with a Liebig condenser and a thermometer.
0g (0.24mol), hexyl bromide 50g (0.3
7 mol), potassium carbonate 35 g (0.25 mol),
0.2 g (0.0012 mol) of potassium iodide was added and suspended in 500 ml of acetone. This suspension was heated under reflux for one day, and after the reaction was completed, the precipitate was removed by filtration, and the solvent was distilled off under reduced pressure. The obtained 5-hexyloxyisophthalic acid dimethyl ester was used in the next reaction without purification.

The 5-hexyloxyisophthalic acid dimethyl ester obtained above was placed in a three-necked flask equipped with a Liebig condenser and a thermometer, and 50 g (0.0 g) of potassium hydroxide was added.
．． 89 mol) in an aqueous solution (250 ml). 7
The mixture was heated under reflux for a period of time, and after the reaction was completed, the aqueous solution was washed with methylene chloride. The aqueous layer was adjusted to pH 1 with concentrated hydrochloric acid, and extracted with diethyl ether while salting out using ammonium sulfate. The organic layer was washed with saturated brine and dried over anhydrous sodium sulfate. The solvent was distilled off under reduced pressure, and the obtained white crystals were purified by recrystallization (acetone) to obtain 5-n-hexyloxyisophthalic acid.

Yield 54.8g Yield 86.5% (5-
from hydroxyisophthalic acid dimethyl ester)mp(
°C) 234-238 1H-NMR (60MHz, DMSO-d6) 0.6-
2.0 (br, 11H), 3.8-4.3 (br, 2H
), 7.69 (s, 2H), 8.14 (s, 1H) IR
(KBr, cm-1) 2954, 2642, 2571,
1711, 1597, 1466, 1416, 1311,
1277, 1047

Example 2 Hexyl bromide 50g (0.37m
ol) instead of undecyl bromide 87 g (0.37 mo
Perform the same operation as in Example 1 except for using l),
5-undecyloxyisophthalic acid was obtained as white crystals.

Yield 63.3g Yield 78.4% (5-
from hydroxyisophthalic acid dimethyl ester)mp(
°C) 189-194 1H-NMR (60MHz, DMSO-d6) 0.6-
2.0 (br, 21H), 3.8-4.2 (br, 2H
), 7.60 (s, 2H), 8.04 (s, 1H) IR
(KBr, cm-1) 2927, 2634, 2565,
1709, 1593, 1466, 1412, 1308,
1273,914

Example 3 Hexyl bromide 50g (0.37m
92 g (0.37 mol) of lauryl bromide instead of
) was used, but the same operation as in Example 1 was performed to obtain white crystalline 5-dodecyloxyisophthalic acid.

Yield 32.3g Yield 38.4% (5-
from hydroxyisophthalic acid dimethyl ester)mp(
°C) 173-176 1H-NMR (60MHz, DMSO-d6) 0.6-
2.0 (br, 23H), 3.8-4.2 (br, 2H
), 7.55 (s, 2H), 8.00 (s, 1H) IR
(KBr, cm-1) 2920, 2636, 2561,
1695, 1597, 1466, 1309, 1277,
1057

Example 4 Hexyl bromide 50g (0.37m
123 g (0.37 m
The same operation as in Example 1 was performed except that 5-octadecyloxyisophthalic acid was obtained as white crystals, except that 5-octadecyloxyisophthalic acid was used.

Yield 93.1g Yield 83.8% (5-
from hydroxyisophthalic acid dimethyl ester)mp(
°C) 157-161 1H-NMR (60MHz, DMSO-d6) 0.7-
2.0 (br, 35H), 3.8-4.3 (br, 2H
), 7.74 (s, 2H), 8.18, s, 1H) IR
(KBr, cm-1) 2918, 2638, 2567,
1707, 1695, 1597, 1470, 1427,
1311, 1279, 1057

Example 5 2,2-bis[4-(
4-aminophenoxy)phenyl]propane 6.07g
(14.8 mmol) and propylene oxide 2.6 g (4
4.8 mmol) was dissolved in 40 ml of N-methyl-2-pyrrolidone. While stirring, 4.50 g (14.8 mmol) of 5-n-hexyloxyisophthalic acid chloride was added in portions. At this time, the temperature in the system is 3
The temperature was kept below 0°C. Since the viscosity of the reaction system increased, stirring was stopped when the desired viscosity was reached, the reaction solution was poured into a large amount of water, and the polymer was isolated and dried under reduced pressure at 100°C.

Table 1 shows the reduced viscosity, yield, organic solvent solubility, and glass transition temperature, which is an index of the heat resistance after film formation, of the polyamide resin thus obtained. Further, the infrared absorption spectrum (film method) of the above polyamide resin is shown in FIG. As is clear from Figure 1,
Absorption of the carbonyl of the amide bond was observed at 1653 cm-1 and absorption based on N-H stretching vibration was observed at 3304 cm-1, confirming that an amide bond was formed.

Example 6 4,4'-bis(4-aminophenoxy)biphenyl 5 instead of 6.07 g (14.8 mmol) of 2,2-bis[4-(4-aminophenoxy)phenyl]propane
．． The same operation as in Example 5 was performed except that 45 g (14.8 mmol) was used. The test results are shown in Table 1. Moreover, the infrared absorption spectrum of the obtained polyamide resin is shown in FIG.

Example 7 6.07 g (14.8 mmol) of 2,2-bis[4-(4-aminophenoxy)phenyl]propane was replaced by bis[4-(4-aminophenoxy)phenyl]sulfone. Except that 42 g (14.8 mmol) was used.
The same operation as in Example 5 was performed. The test results are shown in Table 1. Moreover, the infrared absorption spectrum of the obtained polyamide resin is shown in FIG.

Example 8 4.3 g of 1,4-bis(4-aminophenoxy)benzene was substituted for 6.07 g (14.8 mmol) of 2,2-bis[4-(4-aminophenoxy)phenyl]propane.
Example 5 except that 3 g (14.8 mmol) was used.
The same operation was performed. The test results are shown in Table 1. Moreover, the infrared absorption spectrum of the obtained polyamide resin is shown in FIG.

Example 9 4.3 g of 1,3-bis(4-aminophenoxy)benzene was substituted for 6.07 g (14.8 mmol) of 2,2-bis[4-(4-aminophenoxy)phenyl]propane.
Example 5 except that 3 g (14.8 mmol) was used.
The same operation was performed. The test results are shown in Table 1. Moreover, the infrared absorption spectrum of the obtained polyamide resin is shown in FIG.

Example 10 2.96 g (14.8 mmol) of 4,4'-diaminodiphenyl ether was substituted for 6.07 g (14.8 mmol) of 2,2-bis[4-(4-aminophenoxy)phenyl]propane.
The same operation as in Example 5 was performed except that 4.8 mmol) was used. The test results are shown in Table 1. Moreover, the infrared absorption spectrum of the obtained polyamide resin is shown in FIG.

Example 11 1.60 g (14.8 mmol) of m-phenylenediamine was used in place of 6.07 g (14.8 mmol) of 2,2-bis[4-(4-aminophenoxy)phenyl]propane. The same operation as in Example 5 was performed except for the following. The test results are shown in Table 1. Moreover, the infrared absorption spectrum of the obtained polyamide resin is shown in FIG.

Example 12 1.60 g (14.8 mmol) of p-phenylenediamine was used in place of 6.07 g (14.8 mmol) of 2,2-bis[4-(4-aminophenoxy)phenyl]propane. The same operation as in Example 5 was performed except for the following. The test results are shown in Table 1. Moreover, the infrared absorption spectrum of the obtained polyamide resin is shown in FIG.

The glass transition temperature shown in Table 1 is calculated by calculating the displacement temperature of the coefficient of thermal expansion by thermomechanical analysis at a heating rate of 10.
Measured in °C/min. Solubility was evaluated by mixing 500 mg of polyamide resin with 1 ml of organic solvent and using the following criteria. +……Resin was dissolved. ±……Resin swelled. -...Resin was insoluble.

[0048]

[Table 1]

[0049]

Effects of the Invention The polyamide resin using 5-alkoxyisophthalic acid of the present invention has excellent heat resistance, solubility in organic solvents, film formability, and mechanical properties, and has excellent moldability in injection molding, extrusion molding, etc. It is suitable for electrical insulation materials, heat-resistant adhesives, high-temperature materials, etc.

[Brief explanation of the drawing]

FIG. 1 shows an infrared absorption spectrum of the polyamide resin obtained in Example 5.

FIG. 2 shows an infrared absorption spectrum of the polyamide resin obtained in Example 6.

FIG. 3 shows an infrared absorption spectrum of the polyamide resin obtained in Example 7.

FIG. 4 shows an infrared absorption spectrum of the polyamide resin obtained in Example 8.

FIG. 5 shows an infrared absorption spectrum of the polyamide resin obtained in Example 9.

FIG. 6 shows an infrared absorption spectrum of the polyamide resin obtained in Example 10.

FIG. 7 shows an infrared absorption spectrum of the polyamide resin obtained in Example 11.

FIG. 8 shows an infrared absorption spectrum of the polyamide resin obtained in Example 12.

Claims (5)

[Claims] Claim 1: General formula (I) [In the formula, Ar represents a divalent residue of an aromatic diamine excluding the amino group, and R represents a straight chain or branched chain having 1 to 30 carbon atoms. A polyamide resin having a repeating unit represented by ] representing an alkyl group. 2. The polyamide resin according to claim 1, wherein a solution obtained by dissolving 0.2 g of the polyamide resin in dimethylformamide to make 100 ml has a reduced viscosity of 0.2 to 5.0 dl/g at 30°C. [Claim 3] General formula (II) [Chemical formula 2] H2N-Ar-NH2
(II) [In the formula, Ar is the same as in the general formula (I)] An aromatic diamine represented by the general formula (III) [Formula, R is the same as in the general formula (I)] indicates something, X
2. The method for producing a polyamide resin according to claim 1, wherein the polyamide resin is polycondensed with 5-alkoxyisophthalic acid or a derivative thereof represented by the following formula: hydroxy group, halogen atom, or alkoxy group having 1 to 4 carbon atoms. [Claim 4] General formula (IV) [In the formula, R' is n-C6H13, n-C11H23, n-
5-alkoxyisophthalic acid represented by C12H25 or n-C18H37. 5. General formula (VI) is added to 5-hydroxyisophthalic acid represented by general formula (V)
) [Chemical formula 6] R'-X
(VI) [In the formula (IV), R' is the same as in the general formula (IV), and X represents a halogen atom]. 7. A method for producing 5-alkoxyisophthalic acid represented by [wherein R' is the same as in the general formula (IV)].