JP2583164B2 - Method for producing aromatic copolyester - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a thermotropic aromatic copolyester which can be melt-processed at a relatively low temperature.

[0002]

2. Description of the Related Art In recent years, various engineering plastics have been developed. In particular, liquid crystal copolymers having optical anisotropy have attracted attention. Adva
nces in Polymer Science 6
0/61, p. 61, 1984, describes a homopolymer of P-hydroxybenzoic acid and a copolymer of terephthalic acid and hydroquinone, but these polymers have melting points as high as 610 ° C. and 596 ° C., respectively. It is difficult to melt-process without decomposition. Japanese Patent Publication No. 47-47870 discloses a copolymer of P-hydroxybenzoic acid, terephthalic acid and hydroquinone. This copolymer has a high melting point of 500 ° C. or more and is extremely difficult to melt-process. Have difficulty.

[0003] Various proposals have been made on methods for improving the melt processability by lowering the melting point of liquid crystal copolyester (Brit. Polymer Journal 132).
1980), and in particular, JP-A-64-66231 discloses a method of using 2,2′-dimethylbiphenyl-4,4′-dicarboxylic acid as a comonomer component. Makromolecules, Vol. 20, No. 2
P. 374 In 1987, as a comonomer component,
2'-bis (trifluoromethyl) -biphenyl-4,
The use of 4'-dicarboxylic acids is described.
However, 2,2'-disubstituted biphenyl-4,4'-dicarboxylic acids interfere with the coplanarity of the phenyl ring, thus reducing the crystallinity of the polymer. Generally, polymers having low crystallinity have disadvantages such as insufficient mechanical strength.

[0004] The applicant of the present invention discloses a method of melting 3,3'-dimethylbiphenyl-4,4'-dicarboxylic acid and 3,4'-dimethylbiphenyl-4,3'-dicarboxylic acid at a relatively low temperature using a comonomer component. Processable aromatic copolyesters are disclosed in Japanese Patent Application Nos. 2-110151 and 2-19.
No. 3943. The proposed aromatic copolyester has a melting point that can be melt-molded without excessive loss of crystallinity.

[0005]

DISCLOSURE OF THE INVENTION As a result of studying the method for producing the above-mentioned aromatic copolyester, the present inventors have used alkanoylated aromatic oxycarboxylic acid compounds and aromatic dihydroxy compounds as raw materials, and precondensed these alkanoylated compounds. When an aromatic dicarboxylic acid compound is added to the precondensate and polycondensed, the monomer component is randomly introduced into the polymer, and an aromatic copolyester having excellent heat resistance and excellent mechanical strength is obtained. After investigation, the present production method was proposed.

[0006]

The present invention relates to an alkanoyl compound (I) of an aromatic oxycarboxylic acid compound represented by the following formula A and an alkanoyl compound of an aromatic dihydroxy compound represented by the following formula E: (III) is pre-condensed, and then the aromatic dicarboxylic acid compound (II) represented by the following formulas B, C, and D is added to the pre-condensate,

[0007]

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The polycondensation at a temperature in the range of 200 to 350 ° C. and the molar ratio of each compound to be subjected to the polycondensation reaction are (I) / [(I) + (II)] = 1/100 to 85
/ 100, (II) / (III) = 1 to 1.1, and the ratio of (formula B + formula C) in the aromatic dicarboxylic acid compound (II) is at least 5 mol%. To a method for producing an aromatic polyester. (In the above formula, R represents a hydrogen atom, an alkyl group or aryl group having 1 to 8 carbon atoms, or a halogen atom, and R 'represents an alkyl group or aryl group having 1 to 8 carbon atoms.)

The alkanoylated compound of the formula A and the alkanoylated compound of the formula E used in the present invention can each be easily prepared by a conventional alkanoylation of the corresponding hydroxy compound. As the alkanoylating agent, for example, acetic anhydride, propionic anhydride, acetyl chloride and the like can be used, and acetic anhydride is particularly preferred. The pre-condensation comprises mixing the compounds of formulas A and E,
0.5-260 ° C. while removing the corresponding acid at 0-260 ° C.
The reaction is continued for 5 hours to complete the precondensation of Formulas A and E. Polycondensation can be performed by directly adding an aromatic dicarboxylic acid compound to the precondensation mixture. Or
Once allowed to cool, a predetermined amount can be taken out and polycondensed. The polycondensation is performed at 200 to 350 ° C, preferably 230
The temperature is raised to 330 ° C., the temperature is raised stepwise over 1 to 10 hours to remove generated acid, and the pressure is reduced (about 0.5 torr) to complete the reaction.

The copolymerized polyester produced in the present invention is:
Consists of repeating units derived from the above formulas A, B, C, D and E. The molar ratio of (I) / [(I) + (II)] of the aromatic copolyester of the present invention is 1/100.
８５85/100, preferably 1/100 to 78/10
0, particularly preferably 1/100 to 70/100.
If the molar ratio exceeds 85/100, the melting temperature of the aromatic copolyester becomes high, and molding processing is difficult.

The molar ratio of (II) / (III) is 1-1.
When the molar ratio is less than 1, the polycondensation reaction rate is low, and a copolyester having a high degree of polymerization cannot be obtained.
In the case of 1.1 or more, a polymer having a high degree of polymerization can be obtained. This is not preferable because it easily occurs. The proportion of (formula B + formula C) in the aromatic dicarboxylic acid compound (II) is at least 5 mol%, preferably at least 8 mol%. If the amount is less than 5 mol%, the melting temperature of the aromatic copolyester becomes high similarly to the above, and molding is difficult.

In addition to the above formulas A, B, C, D and E,
Formulas A, B, C, D and E may be substituted by small amounts of monomers capable of forming other ester bonds. Specific examples of other monomers capable of forming an ester bond include isophthalic acid, naphthalene-1,5-dicarboxylic acid, diphenylether-4,4′-dicarboxylic acid,
Dicarboxylic acid compounds such as diphenylsulfone-4,4'-dicarboxylic acid, diphenylketone-4,4'-dicarboxylic acid, 2,2'-diphenylpropane-4,4'-dicarboxylic acid, resorcinol, 2,5-dicarboxylic acid -T-butylhydroquinone, 2,3,5-trimethylhydroquinone, 1,5-dihydroxynaphthalene, 2,2-bis (4-hydroxyphenyl) propane, bis (4-hydroxyphenyl) ketone, bis (4-hydroxyphenyl) ) Alkanoylated dihydroxy compounds such as sulfone and bis (4-hydroxyphenyl) ether, m
Alkanoylated oxycarboxy compounds such as -hydroxybenzoic acid, 4-hydroxy-4'-carboxydiphenyl, and 1-hydroxy-4-naphthoic acid can be mentioned. (A + B + C + D) of these monomers
The substitution ratio with respect to + E) is preferably 10 mol% or less in order to make the melting point of the aromatic copolyester relatively low.

A feature of the present invention is that, in the production of the above-mentioned copolymerized polyester, after the formulas A and E are preliminarily subjected to a contact reaction (precondensation), a dicarboxylic acid compound as a remaining comonomer component is added, and polymerization (polymerization) is performed. (Condensation reaction). The purpose of the precondensation is to suppress the formation of the homocondensate of formula A.

The precondensation and polycondensation reactions can be carried out in the presence or absence of a catalyst. Specific examples of the catalyst include stannous acetate, ferrous acetate, sodium acetate,
Examples include, but are not limited to, metals and metal compounds such as antimony trioxide, magnesium, iron (III) acetylacetone, and titanium tetrabutoxide. The amount of addition is 0.1 to the weight of the produced polymer.
001 to 0.5%. The timing of addition may be at the start of the precondensation reaction or at the start of the polycondensation. In order to prevent discoloration due to thermal degradation during polymerization and improve the thermal stability of the produced polymer,
Precondensation and polycondensation reactions can be performed in the presence of a stabilizer. As specific examples of the stabilizer, phosphoric acid, phosphorous acid,
Examples include phosphorus compounds such as sodium hypophosphite, triphenyl phosphate, and triphenyl phosphite, but are not limited thereto. The amount of addition is 0.001-1% based on the weight of the produced polymer. The timing of addition may be at the start of the precondensation reaction or at the start of the polycondensation.

The aromatic copolyester produced according to the present invention can be prepared at 60 ° C. in pentafluorophenol,
At a concentration of 0.2 g / dl, logarithmic viscosity (η _inh ) 1.0
It has the above. The wholly aromatic copolyester produced according to the present invention exhibits optical anisotropy (liquid crystallinity) in a molten state when observed under a polarizing microscope. Further, by adopting this production method, a wholly aromatic copolyester having significantly reduced homoblocks of paraoxybenzoyl units, improved homogeneity and excellent heat resistance can be obtained.

【The invention's effect】

The wholly aromatic copolyester produced according to the present invention forms a molten state at a relatively low temperature, for example, at a temperature of 400 ° C. or less, and can be formed into bulk molded articles and films by various commonly known molding methods. , Fibers and the like. Further, since it is dissolved in an organic polar solvent such as pentafluorophenol and p-chlorophenol, it is possible to obtain a molded article by a solution processing method. These molded articles can be widely used for electric, electronic, automotive materials and the like. As a remarkable property, since it has liquid crystallinity in a molten state, a molded article having a high degree of molecular orientation can be obtained, and thus a polymer material having excellent mechanical strength can be produced.

[0017]

Embodiments of the present invention will be described below. (Measurement method) Each physical property value shown in the examples of the present invention was measured by the following method. (1) Optical anisotropy: The sample was placed on a polarizing microscope, and the temperature was raised at a rate of 10 ° C./min under a nitrogen stream using a TH600 RMS type heating device manufactured by Linkham Inc., and observed visually. (2) Thermal decomposition onset temperature; SSC / Seiko Denshi Kogyo
Using a 5200 TGA instrument, the sample was placed in nitrogen at
And the change in weight over time was observed. (3) Melting point: SSC / 5200 manufactured by Seiko Denshi Kogyo KK
The sample was heated in nitrogen at a rate of 20 ° C./min using a DSC apparatus, and an endothermic peak was observed.

(4) Logarithmic viscosity: A sample was dissolved in pentafluorophenol at a concentration of 0.2 g / dl at 60 ° C. and measured using an Ubbelohde viscometer. η
_inh was calculated according to the following equation. η _inh = ln (t
/ T _O ) / c where t _O is the falling time of pentafluorophenol, t is the falling time of the sample solution, and c is the concentration of the sample. (5) Melt viscosity The melt viscosity was measured with a cone plate using a dynamic spectrometer RDS (II) manufactured by Rheometrics. Frequency 1.0Hz (6.28 RAD / SE
C) Under a nitrogen atmosphere, a polymer viscosity at 300 ° C. was obtained.

Example 1 In a 100 ml SUS316 container, the upper part of a glass separable three-necked flask was used, and in a container equipped with a stirrer, a nitrogen inlet tube, and Claisen, 11.88 g of diacetoxyhydroquinone (61.
2 mmol), 7.21 g of p-acetoxybenzoic acid (4
0 mmol). After degassing with a vacuum pump and repeating nitrogen purging three times, 240 min.
After heating at 30 ° C. for 30 minutes, the temperature was raised to 250 ° C., and the reaction was continued for 1 hour to complete the precondensation. During this time, acetic acid produced was distilled off while flowing nitrogen. During this time, the reaction solution was colorless and transparent. After the completion of the reaction, the pressure in the reaction vessel was reduced to 100 ° C. or lower to recover 2.10 g of acetic acid.

To the precondensation mixture, 5.41 g of 3,3′-dimethylbiphenyl-4,4′-dicarboxylic acid (PA)
(20 mmol), 3,4'-dimethylbiphenyl-
4.32 g of 4,3′-dicarboxylic acid (QA) (16 mm
ol), 3.99 g of terephthalic acid (TPA) (24 mm
ol) and 30 mg of triphenyl phosphite. After degassing with a vacuum pump and repeating nitrogen replacement three times, the mixture was heated in a tin bath at 240 ° C. for 30 minutes. The temperature was raised to 300 ° C. over 2.5 hours, kept at 300 ° C. for 1.5 hours, and the acetic acid generated was distilled off together with flowing nitrogen. While maintaining the temperature at 300 ° C., the degree of pressure reduction was gradually increased. Decompression degree is 0.
After reaching 1 torr or less, the reaction was further continued for 1 hour (polycondensation reaction). After completion of the reaction, the temperature was returned to normal temperature and normal pressure while introducing nitrogen. The obtained polymer was pulverized and taken out of the container. The fluidity of the obtained polymer was good. Polymer yield, optical anisotropy temperature, melting point,
Table 1 shows the thermal decomposition onset temperature, logarithmic viscosity and melt viscosity.

Example 2 A 1 L SUS316 vessel equipped with a PID control temperature controller was connected with a stirrer, a nitrogen inlet tube, and a trap for recovering distilled acetic acid. In this container, 169.69 g of diacetoxyhydroquinone (874 mmol)
l), 99.88 g of p-acetoxybenzoic acid (554 m
mol). After degassing with a vacuum pump and repeating nitrogen replacement three times, the temperature of the reaction vessel was heated to 240 ° C. After keeping at 240 ° C for 30 minutes, the temperature was raised to 250 ° C,
The reaction was continued for one hour. During this time, acetic acid produced was distilled off while flowing nitrogen (preliminary condensation). After the completion of the precondensation, the reaction vessel is cooled to 100 ° C. or less, and
8.8 g of acetic acid was recovered.

To the precondensation mixture, 3,3'-dimethylbiphenyl-4,4'-dicarboxylic acid (PA) 74.92
g (277 mmol), 3,4′-dimethylbiphenyl-4,3′-dicarboxylic acid (QA) 59.94 g (22
2 mmol), 55.25 g of terephthalic acid (TPA)
(332 mmol) and 0.4 of triphetyl phosphite
5 g were added. After repeating the degassing nitrogen substitution at normal temperature three times, the temperature of the reaction vessel was raised to 240 ° C. The temperature was raised to 310 ° C. over 2.5 hours, kept at 310 ° C. for 1 hour, and the produced acetic acid was distilled off together with flowing nitrogen. While maintaining the temperature at 310 ° C., the degree of pressure reduction was gradually increased. The reaction was continued for 2 hours after the maximum capacity of the vacuum system was reached. Finally, the degree of pressure reduction in the reaction tank was 1.0 torr.

After the completion of the reaction, the pressure was returned to normal pressure by introducing nitrogen, and the temperature of the reaction vessel was raised to 320 ° C. After the temperature was raised, the polymer outlet at the bottom of the reaction tank was opened, and the obtained polymer was extruded at a nitrogen pressure of 1.3 atm. The obtained polymer had good fluidity, and 80% of the produced polymer was recovered by the above operation. Temperature of polymer yield, optical anisotropy,
Table 1 shows melting point, thermal decomposition onset temperature, logarithmic viscosity and melt viscosity.
It was shown to. The polymer yield in the table is the sum of the polymer obtained from the outlet and the polymer adhering in the reaction tank.

Example 3 In Example 1, 32 mg of triphenyl phosphate was used in place of 30 mg of triphenyl phosphite, and 0.1 to
The procedure was performed in the same manner as in Example 1 except that the reaction time after the pressure reached rr or less was changed to 45 minutes. The fluidity of the obtained polymer was good. Table 1 shows the yield of the polymer, the temperature showing the optical anisotropy, the melting point, the thermal decomposition onset temperature, the logarithmic viscosity and the melt viscosity.

Comparative Example In the same reaction vessel as in Example 1, 11.88 g (61.2 mmol) of diacetoxyhydroquinone, 7.21 g (40 mmol) of p-acetoxybenzoic acid, and 3,3′-dimethylbiphenyl-4,4 ′ -Dicarboxylic acid (PA) 5.
41 g (20 mmol), 4.32 g of 3,4′-dimethylbiphenyl-4,3′-dicarboxylic acid (QA) (16
mmol), 3.99 g of terephthalic acid (TPA) (2
4 mmol) and 30 mg of triphenyl phosphite. The same operation as the polycondensation reaction of Example 1 was repeated without performing the precondensation.

Under observation with a polarizing microscope, the obtained polymer showed optical anisotropy and was confirmed to have liquid crystallinity. However, insoluble components were mixed in the melt and the polymer was not uniform. Was. In addition, the melt viscosity was higher than in the examples, and the thermal decomposition onset temperature was lower than in the examples. Table 1 shows the yield of the polymer, the temperature showing the optical anisotropy, the melting point, the thermal decomposition onset temperature, the logarithmic viscosity and the melt viscosity.

[Table 1]

Claims (1)

(57) [Claims] 1. An alkanoylated compound (I) of an aromatic oxycarboxylic acid compound represented by the following formula A and an alkanoylated compound (I) of an aromatic dihydroxy compound represented by the following formula E:
II) is pre-condensed, and the pre-condensate is then converted to the following formula B:
By adding an aromatic dicarboxylic acid compound (II) represented by C or D, The polycondensation at a temperature in the range of 200 to 350 ° C., and the molar ratio of each compound to be subjected to the polycondensation reaction is defined as (I) /
[(I) + (II)] = 1/100 to 85/100,
(II) / (III) = 1 to 1.1, and the ratio of (formula B + formula C) in the aromatic dicarboxylic acid compound (II) is at least 5 mol%. Polyester manufacturing method. (In the above formula, R is a hydrogen atom,
R 1 represents an alkyl group or an aryl group having 1 to 8 carbon atoms or a halogen atom, and R ′ represents an alkyl group or an aryl group having 1 to 8 carbon atoms. )