JPH05105749A - Aromatic copolyester - Google Patents

Abstract

PURPOSE:To obtain a thermotropic liquid crystal aromatic copolyester having melt-formability and heat-resistance and sufficiently high mechanical properties by using dimethylbiphenyldicarboxylic acid and polyethylene terephthalate as essential components. CONSTITUTION:The objective copolyester is composed of the recurring unite of formula I to formula VI (R is H, 1-8C alkyl, aryl or halogen). The amount of the recurring unit of formula I in the total unit is <=85mol%, that of the recurring unit of formula V is 0-75mol%, the ratio of (II+III)/(II+III+IV) is 0.05-1 and the amount of (II+III+IV) is equimolar to the unit of formula VI.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a novel thermotropic liquid crystal copolyester.

[0002]

2. Description of the Related Art In recent years, various engineering plastics have been developed. Among them, liquid crystal copolymers having optical anisotropy have been attracting attention. A
dvances inPolymer Science
60/61 p. 61 1984 describes homopolymers of P-hydroxybenzoic acid, copolymers of terephthalic acid and hydroquinone, copolymers of naphthalene-2,6-dicarboxylic acid and hydroquinone, and the like. Polymers have melting points of 61 each
Since it was as high as 0 ° C., 596 ° C. and 577 ° C., it was practically impossible to perform melt processing without decomposing the polymer.
Further, Japanese Patent Publication No. 47-47870 discloses a copolymer of P-hydroxybenzoic acid, terephthalic acid and hydroquinone, which is 500 ° C.
It has the above high melting point and is extremely difficult to melt process.

As a method for lowering the melting point of the above P-hydroxybenzoic acid homopolymer or a copolymer of P-hydroxybenzoic acid, terephthalic acid and hydroquinone, a method of copolymerizing with polyethylene terephthalate is known (Mol. Cryst). .Liq.Cry
st. 1989, Vol. 169, pp. 23-49). However, in this polyethylene terephthalate copolymerization system,
It is said that the moldability and the heat resistance are in a relationship between the front and back, and the heat resistance decreases as the melting point decreases. Also, as the content of polyethylene terephthalate increases, liquid crystallinity is lost.

[0004]

OBJECT OF THE INVENTION The present invention is directed to 3,3'-dimethylbiphenyl-4,4'-dicarboxylic acid and / or 3,4'-
A dimethyl biphenyl-4,3'-dicarboxylic acid, a novel copolyester having polyethylene terephthalate as an essential component, and a machine having good melt moldability and heat resistance, and having sufficient practicality. Provided is a copolyester having physical properties.

[0005]

The present invention comprises repeating units A, B, C, D, E and F of the following formula:

[Chemical 1] (In the formula, R represents a hydrogen atom, an alkyl group or an aryl group having 1 to 8 carbon atoms, or a halogen atom.) A / [A + B + C + D + E] has a molar ratio of 85/100 or less, and E / [A + B + C + D + E] The molar ratio is greater than 0 and 70/100 or less, and [B + C] / [B
+ C + D] molar ratio is greater than 5/100 and less than or equal to 1, and [B + C + D] and F are substantially equimolar to provide an aromatic copolyester.

The repeating unit A forming the aromatic copolyester of the present invention is derived from p-hydroxybenzoic acid, its carboxylic acid ester, p-acetoxybenzoic acid and the like.

The repeating unit B forming the aromatic copolyester of the present invention is 3,3'-dimethylbiphenyl-
It is derived from 4,4'-dicarboxylic acid, its dicarboxylic acid ester and the like.

The repeating unit C forming the aromatic copolyester of the present invention is 3,4'-dimethylbiphenyl-
It is derived from 4,3′-dicarboxylic acid, its dicarboxylic acid ester and the like.

The above 3,3'-dimethylbiphenyl-
4,4'-dicarboxylic acid and 3,4'-dimethylbiphenyl-4,3'-dicarboxylic acid can be synthesized by, for example, an oxidative coupling reaction of alkyl o-toluate (Japanese Patent Application No. 63-267202). , And Japanese Patent Application No. 1-211334).

The repeating unit E forming the aromatic copolyester of the present invention is derived from polyethylene terephthalate synthesized by a known method. The polyethylene terephthalate has a logarithmic viscosity η _inh at 30 ° C. in a mixed solvent of phenol and tetrachloroethane (weight ratio of 1: 1) of 0.05 to 1.0 dl / g, preferably 0.1 to 0. The range is 0.7. When polyethylene terephthalate having an η _inh outside this range is used, the mechanical strength of the obtained aromatic copolyester decreases.
Alternatively, acetylated polyethylene terephthalate obtained by heating and drying polyethylene terephthalate with acetic anhydride may be used.

The repeating unit F forming the aromatic copolyester of the present invention is derived from a hydroquinone derivative. Examples of the hydroquinone derivative include hydroquinone, methylhydroquinone, ethylhydroquinone, propylhydroquinone, butylhydroquinone, and other alkyl group-substituted hydroquinones having 1 to 8 carbon atoms, aryl group-substituted hydroquinone such as phenylhydroquinone, and halogen group-substituted hydroquinone such as chlorohydroquinone and the like. Specific examples thereof include diacetyl derivatives of In the present invention, the repeating unit F may be derived from a mixture of the above-mentioned plural kinds of hydroquinone derivatives.

In the aromatic copolyester of the present invention, the molar ratio of A / [A + B + C + D + E] is 85/10.
0 or less, preferably 20/100 to 80/100
Is. If this molar ratio exceeds 85/100, the melting temperature of the aromatic copolyester becomes high and molding is difficult. The molar ratio of E / [A + B + C + D + E] is more than 0 and 70/100 or less, preferably 5/100.
~ 50/100. The molar ratio of [B + C] / [B + C + D] is larger than 5/100, preferably 8/100.
It is larger and is 1 or less. If this molar ratio is less than 5/100, the melting temperature of the aromatic copolyester becomes high as in the above case, and the molding process is difficult. Also, [B + C
+ D] and F are substantially equimolar.

In addition to the above formulas A, B, C, D, E and F, the formulas A, B, C, D, E and F are replaced by small amounts of other monomers capable of forming ester bonds. Good. Specific examples of the other monomer capable of forming an ester bond include isophthalic acid, naphthalene-1,5-dicarboxylic acid, diphenylether-4,4′-dicarboxylic acid, diphenylsulfone-4,4′-dicarboxylic acid,
Diphenyl ketone-4,4'-dicarboxylic acid, 2,2 '
-Diphenylpropane-4,4'-dicarboxylic acid and other dicarboxylic acid compounds, resorcin, 2,5-di-t-butylhydroquinone, 2,3,5-trimethylhydroquinone, 1,5-dihydroxynaphthalene, 2,2- Dihydroxy compounds such as bis (4-hydroxyphenyl) propane, bis (4-hydroxyphenyl) ketone, bis (4-hydroxyphenyl) sulfone, bis (4-hydroxyphenyl) ether, m-hydroxybenzoic acid, 4-hydroxy- 4'-carboxydiphenyl, 1
An oxycarboxy compound such as -hydroxy-4-naphthoic acid may be mentioned. Of these monomers,
The substitution ratio with respect to (A + B + C + D + E + F) is preferably 10 mol% or less in order to make the melting temperature of the aromatic copolyester relatively low.

The aromatic copolyester of the present invention is synthesized by a polycondensation reaction. In particular, a deacetic acid polymerization method from an acetyl derivative of a carboxylic acid component and a hydroxy component is common. The polycondensation reaction can be carried out in the presence or absence of a catalyst. Specific examples of the catalyst include metals and metal compounds such as stannous acetate, ferrous acetate, sodium acetate, antimony trioxide, magnesium, acetylacetone iron (III) or titanium tetrabutoxide, but are not limited thereto. It is not something that will be done.

The polycondensation reaction is carried out in the presence of a stabilizer for the purpose of preventing discoloration due to heat deterioration during polymerization and improving the thermal stability of the resulting polymer, as long as the physical properties of the resulting polymer are not significantly affected. It can be carried out. As a specific example of the stabilizer,
Phosphorous compounds such as phosphoric acid, phosphorous acid, sodium hypophosphite, triphenyl phosphate, triphenyl phosphite,
Alternatively, but not limited to, hindered phenols. In the case of the deacetic acid polymerization method, the reaction temperature is 230 to 350 ° C., the temperature is raised stepwise to distill off acetic acid, and then the pressure is reduced (to 0.1 mmHg).
And complete the reaction. The reaction time is preferably 1 to 10 hours.

[0016]

The copolyester of the present invention forms a molten state at a relatively low temperature, for example, a temperature of 400 ° C. or lower,
Bulk moldings, films, fibers and the like can be produced by various commonly known molding methods. Further, since it is dissolved in an organic polar solvent such as pentafluorophenol or p-chlorophenol, it is possible to obtain a molded product by a dissolution processing method. These molded products are
It can be widely used for electronic and automobile materials. As a remarkable property, since it has liquid crystallinity in a molten state, it can be formed into a highly molecularly oriented molded product, and thus a polymer material excellent in mechanical strength can be produced.

[0017]

EXAMPLES Examples 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 methods. (1) Optical anisotropy onset temperature: Place the sample on a polarizing microscope,
Using a TH600RMS type heating device manufactured by Lincom Co., the temperature was raised at 10 ° C./min under a nitrogen stream, and the naked eye was observed. (2) Thermal decomposition start temperature; SSC / manufactured by Seiko Denshi Kogyo Co., Ltd.
Using a 5200 TGA apparatus, the sample was heated in nitrogen at 10 ° C./min, and the change in weight with time was observed. (3) Melting point: SSC / 5200 manufactured by Seiko Instruments Inc.
Using a DSC device, the sample was heated in nitrogen at 20 ° C./min and the endothermic peak was observed. (4) Logarithmic viscosity: The 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 = 1n (t / t ₀ ) / c where t ₀ is the drop time of pentafluorophenol, t is the drop time of the sample solution, and c is the concentration of the sample.

Reference Example 1 A 100 mL glass separable three-necked flask was equipped with a stirrer, a nitrogen introducing tube and a cooling tube. In this container, 29.13 g of dimethyl terephthalate (150 m
M), ethylene glycol 20 mL (360 mM), calcium acetate dihydrate 0.027 g (0.15 mM),
0.009 g (0.03 mM) of antimony oxide was charged, and the temperature was raised from 180 ° C. to 200 ° C. in 3 hours under a nitrogen stream. During this period, almost the theoretical amount of methanol was distilled.
After this, connect a vacuum pump to the reaction system and
The pressure was reduced to mHg. Further, the temperature is raised to 220 ° C., and 40
When the reaction was continued for a minute, a part of the reaction solution began to solidify. Nitrogen was introduced to normal pressure, and the mixture was allowed to cool. The crude reaction product was dissolved in a mixed solution of phenol and tetrachloroethane (weight ratio: 1: 1) and poured into 1 L of methanol for precipitation.
The precipitate was collected by filtration, washed well with methanol, and then dried. The yield was 25.68 g, and the yield was 89%. The logarithmic viscosity of this polyethylene terephthalate is 30 in a mixed solvent of phenol and tetrachloroethane (weight ratio 1: 1).
It was 0.1 at a temperature of 1.0 dl / g. Acetic anhydride 4 was added to 16.05 g of the above polyethylene terephthalate.
0 mL was added and it heated at 140 degreeC for 2 hours. After distilling off excess acetic anhydride, it was dried at 60 ° C. overnight to obtain acetylated polyethylene terephthalate (hereinafter referred to as PETAC). The weight increase was 5.4%.

Example 1 An upper part of a glass separable three-necked flask was used in a stainless steel container (100 mL), and a stirrer, a nitrogen introducing tube and a Claisen were attached. In this container, 3,3 '
-Dimethylbiphenyl-4,4'-dicarboxylic acid 5.4
1 g (20.0 mM), terephthalic acid 3.32 g (2
0.0 mM), hydroquinone diacetate 7.87 g
(40.5 mM), PETAC 4.05 g (20.0
mM), 10.81 g of p-acetoxybenzoic acid (60.
0 mM) and 0.031 g of triphenyl phosphate (0.
(1 mM), vacuum deaeration and nitrogen substitution were repeated 3 times, and then the temperature was raised stepwise from 240 ° C. to 310 ° C. over 3 hours and 50 minutes in a metal bath in which tin was dissolved. Was distilled. The system was gradually depressurized to 0.1 mmHg for 30 minutes at 310 ° C. and stirred for 1 hour. Nitrogen was introduced to normal pressure, and the mixture was allowed to cool and returned to room temperature. The polymer is crushed, taken out of the container, washed with acetone, dried and
22.03 g of copolyester was obtained (96% yield). Table 1 shows the measurement results of the optical anisotropy onset temperature, melting point, thermal decomposition onset temperature and logarithmic viscosity of the obtained copolyester.

Example 2 In Example 1, 3,3'-dimethylbiphenyl-
2.97 g (11.0 mM) of 4,4'-dicarboxylic acid,
3,4'-Dimethylbiphenyl-4,3'-dicarboxylic acid 2.43 g (9.0 mM), terephthalic acid 3.32 g
(20.0 mM), hydroquinone diacetate 7.8
7 g (40.5 mM), PETAC 4.05 g (2
0.0 mM), p-acetoxybenzoic acid 10.81 g
(60.0 mM) and triphenyl phosphate 0.031
22.10 g of copolyester was obtained in the same manner as in Example 1 except that polycondensation was performed using g (0.1 mM) (yield 96%). Table 1 shows the measurement results of the optical anisotropy onset temperature, melting point, thermal decomposition onset temperature and logarithmic viscosity of the obtained copolyester.

Example 3 In the same reaction vessel as in Example 1, 9.19 g (34 m) of 3,3'-dimethylbiphenyl-4,4'-dicarboxylic acid was added.
M), terephthalic acid 5.65 g (34 mM), hydroquinone diacetate 13.40 g (69 mM), PET
Ac 3.44 g (20.0 mM) and iron acetylacetone 0.003 g were charged, and vacuum degassing and nitrogen substitution were performed to 3 times.
After repeating this operation, the temperature was raised stepwise from 240 ° C. to 310 ° C. over 5 hours in a metal bath containing tin. 310 ° C
After stirring for 1 hour, the pressure was gradually reduced to 0.1 mmHg, and the mixture was further stirred for 1 hour. It was treated in the same manner as in Example 1 to obtain 21.70 g of copolyester (yield 94.
%). Optical anisotropy onset temperature of the obtained copolyester,
Table 1 shows the measurement results of the melting point, the thermal decomposition starting temperature and the logarithmic viscosity.

[Table 1]

Claims (1)

[Claims] 1. Comprised of repeating units A, B, C, D, E and F of the formula: (In the formula, R represents a hydrogen atom, an alkyl group or an aryl group having 1 to 8 carbon atoms, or a halogen atom.) A / [A + B + C + D + E] has a molar ratio of 85/100 or less, and E / [A + B + C + D + E] The molar ratio is greater than 0 and 70/100 or less, and [B + C] / [B
An aromatic copolyester in which the molar ratio of + C + D] is greater than 5/100 and is 1 or less, and [B + C + D] and F are substantially equimolar.