AROMATIC COPOLYESTERS

Abstract: An aromatic copolyester from which molded articles can be prepared comprises substantially equimolar proportions of [A] units derived from an aromatic dicarboxylic acid having 8 to 16 carbon atoms and [B] units derived from an aromatic diol component composed of (a) 20 to 95 mole %, based on the to­ tal moles of compounds (a) and (b) below, of a bisphenol com­ pound represented by the formula wherein X represents a direct bond or a divalent group se­ lected from C₁-X₈ alkylidene groups, O, S, SO, SO₂ and CO, and (b) 5 to 80 mole %, based on the total moles of the com­ pounds (a) and (b), of a compound selected from specific diva­ lent phenolic compounds. The aromatic copolyester has an intrinsic viscosity [η], de­ termined at 60°C in pentafluorophenol, of at least 0.4 dl/g.

Description: This invention relates to an aromatic copolyester derived from an aromatic dicarboxylic acid component and an aromatic diol component, which is not described in the known literature and has excellent heat resistance and hydrolysis resistance. Many proposals have been made on heat-resistant aromatic polyesters or copolyesters derived from an aromatic dicarboxylic acid component such as terephthalic acid or isophthalic acid and an aromatic diol component such as bisphenols, for example in J. Polymer Science, 40 , 399 (1959), Visokomol. Soyed, 1 , 834 (1959), Japanese Patent Publication No. 15247/1963 (corresponding to British Patent No. 924,607), British Patent No. 897,640, Japanese Patent Publication No. 5599/1962 (corresponding to U. S. Patent No. 3,133,898), and Japanese Laid-Open Patent Publications Nos. 73021/1982, 96019/1982, 111317/1982, and 180525/1983. These known aromatic polyesters or copolyesters have the defect of inferior hydrolysis resistance at high temperatures. For example, poly(isopropylidene-4,4'-diphenylene isophthalate terephthalate) which has already come into commercial production readily undergoes hydrolysis in an atomosphere where water is present at high temperatures, for example in boling water, and are drastically reduced in performance. Thus, the conventional aromatic polyesters or copolyesters have the defect that they have inferior hydrolysis resistance at high temperatures, and are susceptible to hydrolysis during molding or during use at high temperatures. The invention seeks to provide an aromatic copolyester which can overcome the aforesaid technical trouble or defect and provides an aromatic copolyester comprising substantially equimolar proportions of [A] units derived from an aromatic dicarboxylic acid component having 8 to 16 carbon atoms and [B] units derived from an aromatic diol component, characterised in that (I) the diol component [B] is composed of (a) 20 to 95 mole %, based on the total moles of compounds (a) and (b) below, of a bisphenol compound (a) represented by the formula wherein X represents a direct bond or a divalent group selected from C₁-C₈ alkylidene groups, O, S, SO, SO₂, and CO, and (b) 5 to 80 mole %, based on the total moles of the compounds (a) and (b), of a compound selected from (b-1) a divalent phenol compound represented by the formula wherein each of R¹ and R² independently represents a hydrogen atom, a C₁-C₃ alkyl group, isobutyl group or a phenyl group, and (b-2) a dihydric phenol compound represented by the formula wherein each of R³, R⁴, R⁵ and R⁶ independently represents a C₁-C₃ alkyl group and each of R⁷, R⁸, R⁹ and R¹⁰ independently represents a hydrogen atom, a C₁-C₃ alkyl group or a phenyl group, and (II) the aromatic copolyester has an intrinsic viscosity [η], determined at 60°C in pentafluorophenol, of at least 0.4 dl/g. The aromatic copolyester of the invention exhibits excellent heat resistance and hydrolysis resistance. In the present invention, aromatic dicarboxylic acids having 8 to 16 carbon atoms are used as the aromatic dicarboxylic acid component [A]. These ester-forming aromatic dicarboxylic acids are well known per se , and can be used in the production of the aromatic copolyester of this invention. The component [A] may be aromatic dicarboxylic acids having 8 to 16 carbon atoms, and functional derivatives thereof such as acid halides and aryl esters (e.g. phenyl or triphenyl esters). Specific examples include terephthalic acid, isophthalic acid, or orthophthalic acid, 2,6-naphthalenedicarboxylic acid, 4,4-biphenyldicarboxylic acid, mixtures of at least two of these acids, and the functional derivatives thereof. Preferred units [A] derived from the aromatic dicarboxylic acid component are those derived from terephthalic acid and/or isophthalic acid. Units derived from a mixture of both are especially preferred. In the present invention, the aromatic diol component [B] is composed of 20 to 95 mole% of the bisphenol compound (a) and 5 to 80 mole% of the dihydric phenol compound (b), the proportions being based on the total moles of the bisphenol compound (a) and the dihydric phenol compound (b) selected from the compounds (b-1) and (b-2) mentioned above. Preferably, it is composed of 25 to 90 mole%, more preferably 30 to 80 mole%, of the bisphenol compound (a) and 10 to 75 mole%, more preferably 20 to 70 mole%, of the dihydric phenol compound (b) Examples of the C₁-C₈ alkylidene groups in the formula of the bisphenol compound (a) are methylidene, ethylidene and propylidene. Specific examples of the bisphenol compound (a) are 4,4'-dihydroxydiphenyl, bis(4-hydroxyphenyl)methane, 2,2-bis(4-hydroxyphenyl)propane, 2.2-bis(4-hydroxyphenyl)butane, 4,4'-cyclohexylidenediphenol, 1-phenyl-1,1-bis(4-hydroxyphenyl)ethane, 4,4'-dihydroxybenzophenone, 4,4'-dihydroxydiphenylether, 4,4'-thiodiphenol, and bis(4-hydroxyphenyl)sulfone. The dihydric phenol compound (b) is a compound (b-1) or (b-2). Specific examples of the dihydric phenol compound (b-1) include 3,6-dihydroxyxanthene, 3,6-dihydroxy-9-methylxanthene, 3,6-dihydroxy-9,9-dimethylxanthene, 3,6-dihydroxy-9-methyl-9-ethylxanthene, 3,6-dihydroxy-9-methyl-9-isobutylxanthene, and 3,6-dihydroxy-9-methyl-9-phenylxanthene. Specific examples of such dihydric phenol compound (b-2) include 9,10-dihydro-2,4,5,7-tetramethyl-3,6-dihydroxyanthracene, 9-hydro-2,4,5,7,10,10-hexamethyl-3,6-dihydroxyanthracene, 2,4,5,7,9,10-hexamethyl-3,6-dihydroxyanthracene, 2,4,5,7,9,9,10,10-octamethyl-3,6-dihydroxyanthracene, 2,4,5,7,9,10,10-heptamethyl-9-ethyl-3,6-dihydroxyanthracene, 2,4,5,7,9,10-hexamethyl-9,10-diethyl-3,6-dihydroxyanthracene, 2,4,5,7,9,10,10-heptamethyl-9-phenyl-3,6-dihydroxyanthracene, and 2,4,5,7-tetraethyl-9,9,10,10-tetramethyl-3,6-dihydroxyanthracene. The aromatic copolyester of this invention consists of the units [A] derived from the aromatic dicarboxylic acid component and the units [B] derived from the aromatic diol component condensed in the alternately arranged state, and is a substantially linear high polymer as a result of formation of ester linkages. The molecular end of the copolyester may be a carboxyl group, a hydroxyl group. Alternatively, the terminal carboxyl group may be esterified with a lower alcohol, or the terminal hydroxyl group may be esterified with a lower carboxylic acid. The aromatic copolyester of this invention has an intrinsic viscosity [η], measured at 60°C in pentafluorophenol, of at least 0.4 dl/g, preferably at least 0.5 dl/g, and a glass transition temperature of preferably at least 130°C, for example 130 to 300°C, more preferably 150 to 280°C. In addition to excellent heat resistance shown by the above glass transition temperature, the aromatic copolyester of this invention has an excellent hydrolysis resistance of, for example, at least 60%, preferably at least 65%, especially preferably at least 70%. Means of producing polyesters from aromatic dicarboxylic acids and aromatic diols by utilizing known polyester-forming reactions such as solution polymerization, melt polymerization and interfacial polymerization are well known and established in the art, and can be utilized in the production of the aromatic copolyesters of this invention. They are briefly described below. Melt-polymerization:- The aromatic dicarboxylic acid or its ester-forming derivative and the aromatic diol or its ester-forming derivative are reacted in the molten state at a high temperature, and low-boiling compounds formed as by-products by the reaction are removed from the reaction system by, for example, distillion under reduced pressure (see, for example, Japanese Patent Publication No. 15247/1963 corresponding to British Patent No. 924,607). The reaction conditions may, for example, include agitation, a reaction temperature of about 250 to 400°C and a reaction pressure of atmospheric pressure to 13 Pa (0.1 mmHg). Solution polymerization:- A solution of the aromatic dicarboxylic acid or its ester-forming derivative or its acid halide and the aromatic diol or its ester-forming derivative is formed by using a high-boiling solvent such as diphenyl ether, benzophenone, meta-terphenyl, chlorinated biphenyl and brominated naphthalene. The solution is reacted at a high temperature, or if required in the presence of a basic compound such as a tertiary amine and N-methylpyrrolidone to promote the reaction [see, for example, Japanese Patent Publication No. 5599/1962 corresponding to U. S. Patent No. 3,133,898 and British Patent No. 966,483; Industrial & Engineering Chemistry, 51 , 147 (1959)). The reaction conditions may, for example, include agitation, a reaction temperature of about 100 to 300°C and a reaction pressure of atmospheric pressure to 13 Pa (0.1 mmHg). Interfacial polymerization: An acid halide of the aromatic dicarboxylic acid is dissolved in an organic solvent, and separately, the aromatic diol is converted to its metal salt such as sodium salt and dissolved in water. The two solutions are then brought into contact with each other to react on their interface the acid halide with the salt of the aromatic diol[see,f or example, J. Polym. Sci., 40 , 399 (1959); British Patent No. 897,640; Jaapnese Patent Publication No. 18399/1962; and Japanese Patent Publication No. 4996/1967). The reaction conditions include agitation, a reaction temperature of about 0 to 100°C, and a reaction pressure of atmospheric pressure. Since the aromatic copolyesters of this invention have better heat resistance and hydrolysis resistance than conventional aromatic polyesters, their degradation during melt-molding and during use at high temperatures can be prevented. The aromatic copolyesters of this invention can be used for example as component part of electrical and electronic instruments and appliances, automobiles, and precision instruments and appliances. The following examples specifically illustrate the production of the aromatic copolyesters of this invention and their excellent properties. In these examples, the amounts of the starting materials, solvents, catalysts and other materials used are indicated in parts by weight. The glass transition point of the aromatic copolyester is determined by a differential scanning calorimeter. The hydrolysis resistance of the aromatic copolyester is the percent retention of the intrinsic viscosity [η] of a molded article of the polyester immersed for 10 days in boiling water based on its initial intrinsic viscosity before immersion. The heat distortion temperature of the aromatic copolyester was measured and determined in accordance with JIS K-6871. The mechanical properties were measured and determined in accordance with the methods of JIS K-6745 and JIS K-6719. EXAMPLES 1-3 An aromatic copolyester was produced by using each of the diols, each of the aromatic dicarboxylic acid dichlorides indicated in Table 1 in the proportions indicated. An aqueous solution prepared by dissolving the diol indicated in Table 1, sodium hydroxide (82.8 parts), sodium hydrosulfate (2 parts) and triethylbenzyl ammonium bromide (1.8 parts) in water (5000 parts) and a solution of the aromatic dicarboxylic acid dichloride indicated in Table 1 in methylene chloride (3000 parts) were contacted at 10 to 20°C with stirring at high speeds to perform interfacial polymerization. Acetone was added to the reaction mixture to precipitate the resulting aromatic polyester, and the precipitate was isolated and recovered. Table 1 summarizes the intrinsic viscosities, glass transition temperatures, heat distortion temperatures, tensile strengths and Izod impact strengths of the resulting aromatic polyesters. EXAMPLES 4-8 Example 1 was repeated except that each of the diols and each of the aromatic dicarboxylic acid dichlorides indicated in Table 2 were used in the proportions indicated. Table 2 summarizes the intrinsic viscosities, glass transition temperatures, heat distortion temperatures and hydrolysis resistances of the aromatic polyesters obtained. EXAMPLES 9-11 Aromatic copolyesters were produced by using the aromatic dicarboxylic acids and diol diacetates shown in Table 3 in the amounts indicated. A reactor was charged with each of the aromatic dicarboxylic acids, each of the diol acetates, triphenyl phosphate (0.33 parts) and tetrabutoxy titanate (0.1 part), and they were reacted at 250 to 310°C under atmospheric pressure for about 1.5 hours with stirring in an atmosphere of nitrogen while distilling off acetic acid. Then, over the course of about 2 hours, the pressure of the reaction system was gradually reduced, and the temperature was raised so that finally the pressure reached about 133 Pa (1 mmHg) and the temperature rose to 355°C. Table 3 summarizes the intrinsic viscosities, glass transition temperatures and hydrolysis resistances of the resulting aromatic polyesters. EXAMPLES 12-16 Example 9 was repeated except that the aromatic dicarboxylic acids and diol diacetates indicated in Table 4 were used in the proportions indicated. Table 4 summarizes the intrinsic viscosities, glass transition temperatures and hydrolysis resistances of the resulting aromatic polyesters of the resulting aromatic copolyesters.

Claims: An aromatic copolyester comprising substantially equimolar proportions of [A] units derived from an aromatic dicarboxylic acid having 8 to 16 carbon atoms and [B] units derived from an aromatic diol component; characterized in that (I) the diol component [B] is composed of (a) 20 to 95 mole %, based on the total moles of compounds (a) and (b) below, of a bisphenol compound (a) represented by the formula wherein X represents a direct bond or a divalent group selected from C₁-C₈ alkylidene groups, O, S, SO, SO₂ and CO, and (b) 5 to 80 mole %, based on the total moles of the compounds (a) and (b), of a compound selected from (b-1) a divalent phenol compound represented by the formula wherein each of R¹ and R² independently represents a hydrogen atom, a C₁-C₃ alkyl group, isobutyl group or a phenyl group, and (b-2) a dihydric phenol compound represented by the formula wherein each of R³, R⁴, R⁵ and R⁶ independently represents a C₁ -C₃ alkyl group and each of R⁷, R⁸, R⁹ and R¹⁰, independently represents a hydrogen atom, a C₁-C₃ alkyl group or a phenyl group, and (II) the aromatic copolyester has an intrinsic viscosity [η], determined at 60°C in pentafluorophenol, of at least 0.4 dl/g. A copolyester according to claim 1 which has a glass transition temperature of at least 130°C. A copolyester according to claim 1 or 2 which has a hydrolysis resistance of at least 60%. Molded articles prepared from a copolyester as claimed in any one of the preceding claims.

Inventors: NAKANO, TAKAYUKI, SOTOYAMA, TOSHIKI, YATSU, TADAO
Applicants: MITSUI PETROCHEMICAL INDUSTRIES, LTD.
Application year: 1985
Main classification: C08G63
IPC codes: C08G63