JPH0784514B2 - Method for producing copolyester - Google Patents

Description

TECHNICAL FIELD The present invention relates to a novel method for producing a copolyester having a high elastic modulus and a high strength. The copolyester produced in this manner forms a thermotropic liquid crystal, and is therefore easily molded and can be commercialized as a molding material, a film, or a fiber.

[Conventional technology]

In recent years, regardless of whether it is a fiber, film or molded product,
There is a strong demand for materials with excellent rigidity, heat resistance and chemical resistance. Polyester has come to be widely accepted for general molded articles, but many polyesters are inferior in flexural modulus and flexural strength, so that they are not suitable for applications requiring high elastic modulus and high strength. In order to improve this mechanical physical property, a method of blending a reinforcing material such as calcium carbonate or glass fiber is known, but since the specific gravity of the material becomes large, the advantage of lightweight, which is a characteristic of plastics, is reduced. At the time of molding, the molding machine is heavily worn and there are many practical problems.

In recent years, liquid crystalline polyester has been attracting attention as a polyester suitable for applications requiring a high elastic modulus and high strength without requiring a reinforcing material. It has become particularly noticeable that Journal of Polymer Science Polymer Chemistry Edition 14 (1976) p. 2043 and Japanese Patent Publication No. 56-18016.
This is after Jackson announced a thermal liquid crystal polymer consisting of polyethylene terephthalate and acetoxybenzoic acid. Among them, Jakson reported that this liquid crystal polymer exhibits 5 times or more rigidity, 4 times or more strength, and 25 times or more impact strength of polyethylene terephthalate, and shows new possibility for high performance resin. Indicated.

On the other hand, we first formula (A) [Wherein R ¹ is a divalent aromatic hydrocarbon group having 6 to 20 carbon atoms, a divalent alicyclic hydrocarbon group having 4 to 20 carbon atoms and / or a divalent aliphatic group having 1 to 40 carbon atoms] Group (however, the hydrogen atom of the aromatic ring of the aromatic hydrocarbon group may be substituted with a halogen atom, an alkyl or alkoxy group having 1 to 4 carbon atoms), and R ² is a divalent group having 2 to 40 carbon atoms. Aliphatic hydrocarbons, divalent alicyclic hydrocarbon groups having 4 to 20 carbon atoms, divalent aromatic hydrocarbon groups having 6 to 20 carbon atoms forming an aromatic ring (provided that aromatic hydrocarbon groups A hydrogen atom of the aromatic ring may be substituted with a halogen atom, an alkyl group having 1 to 4 carbon atoms or an alkoxy group), or a polyalkylene oxide divalent radical having a molecular weight of 80 to 8000]. The raw material consists of oligoesters or polyesters in the amount of repeating units that make up these 95 mol% and the general formula ^{(B) HO-R 3 COOH} ...... (B) [the number of carbon atoms wherein R ³ is to form an aromatic hydrocarbon ring having 6 to 20
A divalent aromatic group (provided that the hydrogen atom of the aromatic hydrocarbon group may be substituted with a halogen atom, an alkyl group having 1 to 4 carbon atoms or an alkoxy group). From the 3rd step, a copolymerized oligomer is prepared by reacting mol% (1st step), then an acylating agent is added to perform acylation (2nd step), and polymerization is further performed under reduced pressure (3rd step). Has been filed for a method for producing a copolyester (JP-A-60-186525, JP-A-60-245630).
issue).

Further, although a patent application has been filed in Japanese Patent Application No. 60-20761 for a method in which the rate of polymerization is high and the amount of sublimate is remarkably reduced, the copolymerized polyester produced in this manner is not sufficient in thermal stability. .

[Object of the Invention]

In view of such a point, as a result of intensive studies, we have found a method for producing a copolyester having good thermal stability.

That is, the present invention provides a starting oligoester consisting of repeating units represented by the general formula (A) in which the terminal OH group and the terminal COOH group have 10 equivalents ≦ terminal OH group equivalent−terminal COOH group with respect to —OR ² O-100 equivalent. A method for producing a copolyester is characterized in that an oligoester having an equivalent weight of ≦ 70 equivalent is used.

[Structure of Invention]

 The present invention will be described in more detail.

The copolymerized polyester produced by the conventional method is the same as the copolymerized oligomer produced in the first step. (Wherein, R ² and R ³ R ² in (A) and (B) formula
And R ³ are synonymous. ), The balance between the --OH and --COOH groups of the end groups may be lost, and the --COOH group ends may become excessive.Therefore, other than OH groups may be present in the copolymer.
The copolyester became unstable to heat due to the reaction of the COOH group with the acylating agent to form an acid anhydride bond and the residual carboxylic acid remaining in the final copolyester. It is considered to be a thing.

Therefore, in the present invention, by using those having a range of the terminal group of the oligoester as a raw material defined in advance, the terminal OH group and the terminal COOH group are balanced, so that an acid anhydride is less likely to be formed, and thermal stability is improved. It has become possible to produce excellent copolyesters.

The present invention is carried out by reacting a starting oligoester comprising a repeating unit represented by the general formula (A) with a hydroxycarboxylic acid to form a copolymer oligomer, which is then acylated and further polymerized under reduced pressure. More specifically, in order to produce a starting oligoester consisting of the repeating unit represented by the general formula (A), a dicarboxylic acid represented by the general formula (E) HOOCR ¹ COOH (E) (wherein R ¹ Is the same as in general formula (A)) and its ester are used. Examples of carboxylic acid include terephthalic acid, methoxyterephthalic acid, ethoxyterephthalic acid, fluoroterephthalic acid, chloroterephthalic acid, methylterephthalic acid and isophthalic acid. , Phthalic acid, methoxyisophthalic acid, diphenylmethane 4,4'-dicarboxylic acid, diphenylmethane 3,3'-dicarboxylic acid, diphenyl ether 4,4'-dicarboxylic acid, diphenyl-4,
4'-dicarboxylic acid, naphthalene-2,6-dicarboxylic acid,
Naphthalene 1,5 dicarboxylic acid, naphthalene 1,4 dicarboxylic acid, adipic acid, sebacic acid, azelaic acid, speric acid, dodecane dicarboxylic acid, 3-methyl azelaic acid,
Examples thereof include glital acid, succinic acid, cyclohexane 1,4 dicarboxylic acid, cyclohexane 1,3 dicarboxylic acid and cyclopentane 1,3 dicarboxylic acid. These may be mixed and used, and any of those represented by the general formula (E) can be used.

Further, a general formula (F) used for producing a starting oligoester composed of a repeating unit represented by the general formula (A)
Specific examples of the diol HOR ² OH (F) (wherein R ² is the same as in the general formula (A)) represented by ethylene glycol, 1,3-propanediol, 1,2-propanediol, 1,3-butanediol, 1,4-butanediol, neopentyl glycol,
1,6-hexanediol, 1,12-dodecanediol, cyclohexane 1,4 diol, cyclohexane 1,3 diol, cyclohexane 1,2-diol, cyclopentane 1,3
-Diol, diethylene glycol, polyethylene glycol, hydroquinone, resorcinol, bisphenol A, methylhydroquinone, chlorohydroquinone, 2,6
Examples thereof include naphthalene diol. These may be used as a mixture, and any of those represented by the general formula (F) can be used.

Raw oligoesters produced from these have an OH group and / or a COOH group at the end.
By regulating the number of OH groups and COOH groups, especially the difference (the number of OH groups-the number of COOH groups), a copolyester having good stability can be produced.

The range is −OR ² O− 10 equivalents to 100 equivalents ≦ terminal OH group equivalent−terminal COOH group equivalent ≦ 70 equivalents.
[I]. The free (E) and (F) ends are also included in this. Using less than 10 equivalents of oligoester (D)
This is not preferable because the terminal COOH groups are considerably excessive due to the formation of the above, and the purpose cannot be achieved (polymer stability is poor). On the other hand, if the amount exceeds 70 equivalents, the stability of the polymer will be good, but the polymerization rate will decrease, which is not preferable. The difference between the terminal OH group and the terminal COOH group is preferably 15 to 50 equivalents, more preferably 18 to 30 equivalents. The reason that defines the formula [I] with respect to -O-R ² -O-100 equivalents are as follows.

The starting oligoester is produced by using the diol represented by the general formula (F) and the dicarboxylic acid represented by the general formula (E). However, when the diol is used in excess as compared with the dicarboxylic acid, both of the following formulas are used. A large amount of raw oligoester having a diol unit at the end is contained in the raw oligoester produced.

In such a case, since the formula (A) unit does not take into consideration the --O--R ² --O-- unit at one end of the above formula for defining the formula (A) unit, --O--R ² -O-Specified per unit. When the starting oligoester in the range of the formula [I] is used, the end groups are well balanced during the polymerization, so that the resulting copolyester has good stability and a high polymerization rate. The terminal group of the raw oligoester is H-NMR, ¹³ C-
It can be quantified by NMR, titration method and the like. In particular, it is more preferable to use an oligoester in which a COOH group does not substantially exist in the terminal group of the raw oligoester (a 1/10 or less amount of COOH group compared to the OH group) from the viewpoint of reproducibility.

The starting oligoester can be obtained by directly reacting (E) and (F), or can be produced by the transesterification method of the diester of (E) and (F).

The latter transesterification method is preferred in order to make the starting oligoester substantially free of COOH groups.

As the starting oligoester consisting of the repeating unit represented by the formula (A) used in the present invention, any one represented by the general formula (A) can be used, but polyethylene terephthalate and polybutylene terephthalate are easily available. And their oligomers are preferred, and polyethylene terephthalate and its oligomers are particularly preferred.

As the hydroxycarboxylic acid of the formula (B), para-hydroxybenzoic acid, 4-hydroxy-3-chlorobenzoic acid, meta-hydroxybenzoic acid, 4-hydroxy-3,5-dimethylbenzoic acid, 2-oxy6-naphthoic acid, 1- Oxy-5-naphthoic acid, 1-hydroxy-4-naphthoic acid, Schuringer acid, vanillic acid, 4-hydroxy-3-methylbenzoic acid and the like can be mentioned. It is preferable to use para-hydroxybenzoic acid alone in order to maintain the melt anisotropy, but any of the hydroxycarboxylic acids represented by the general formula (B) can be used, and they can be used by mixing them. I don't care.

The reaction of the hydroxycarboxylic acid (B) with the starting oligoester consisting of the repeating unit represented by the general formula (A) is carried out at 200 to 350 ° C, preferably 220 to 300 ° C, and the reaction is carried out for 5 minutes to 10 hours. Preferably for 20 minutes to 5 hours.

The reaction is carried out until the residual amount of the oxycarboxylic acid compound is usually 70 mol% or less, preferably 50 mol% or less, particularly preferably 40 mol% or less based on the charged amount.

The reaction can be carried out without a catalyst, but a catalyst is added if necessary.

The second step, acylation, is to use an acylating agent (acylating agent).
/ (B) is not more than 1.5 times mol, preferably not less than 0.8 mol and 1.3
It is carried out in an amount of less than 1 mol, and in that case, the dropping time of the acylating agent is 10 minutes or longer, preferably 20 minutes or longer. The contact with the acylating agent is performed at 80 ° C to 350 ° C, preferably 100 ° C to 300 ° C, more preferably 120 ° C to 260 ° C, and may be pressurized.

Further, the system may be lowered to the boiling point of the acylating agent or lower to carry out the acylation. The reaction is 10 minutes or more to 10 hours, preferably 20
It is carried out in the range of minutes to 5 hours.

As the acylating agent, acetic anhydride, propionic anhydride,
Butyric anhydride, benzoic anhydride and the like are used, but any of those generally usable as an acylating agent can be used, and of these, acetic anhydride is typical from the viewpoint of reactivity and cost.

Then the third stage polymerization is 200 ℃ ~ 350 ℃, preferably 220 ℃
Although it is carried out at ~ 330 ° C, it is preferable to gradually reduce the pressure in this case, and the time required for gradually reducing the pressure from 760 mmHg to 1 mmHg is 30 minutes or more, preferably 60 minutes or more. Especially, it is important to gradually reduce the pressure from 10 mmHg / min to 1 mmHg / min.

The second step and the third step can be carried out without a catalyst, but are carried out in the presence of a catalyst if necessary.

As the catalyst used in the first step, the second step and the third step, a transesterification catalyst, a polycondensation catalyst, an acylation catalyst,
Decarboxylic acid catalysts are used, and these may be used as a mixture. The amount used is 5 to 5 relative to the polymer
The amount is 0000 ppm, preferably 50 to 5000 ppm.

Further, ηinh was measured at 30 ° C. at 0.5 g / dl in a mixed liquid of phenol and tetrachloroethane = 1: 1 (weight ratio). Ηinh of the final product is 0.3 dl / g or more, preferably 0.35 dl / g or more.

〔Example〕

The present invention will be specifically described below with reference to examples, but the present invention is not limited to the following examples as long as the gist thereof is not exceeded.

<Quantification of oligoethylene terephthalate end group> Quantification of terminal OH group Oligoethylene terephthalate was dissolved in hexafluoroisopropanol / deuterated chloroform and H-NMR
It was in agreement with the value obtained from ¹³ C-NMR.

Quantification of terminal COOH groups Oligoethylene terephthalate was dissolved in DMF by heating and NaO
Titrated with H (alcohol solution).

The results are shown below.

Example 1 A glass polymerization tube equipped with a stirring blade, a nitrogen inlet, and a depressurizing port was used.
-Hydroxybenzoic acid 51.8 g (0.375 mol), oligoethylene terephthalate oligomer (a) 72.1 g (0.375 mol as the amount of repeating units), stannous acetate 0.037 g were charged, and reduced pressure-nitrogen substitution was repeated 3 times, and finally Fill with nitrogen and place under a stream of nitrogen at a flow rate of 0.5 / min. 240 polymerization tubes
When immersed in an oil bath at ℃, the content melts in about 30 minutes, so stirring is started and transesterification is carried out for 2 hours to produce a copolymerized oligomer.

Then, the temperature was lowered to 140 ° C in about 30 minutes, and then 42 g of acetic anhydride (0.
(413 mol) is added dropwise over 30 minutes, and stirring is continued for another hour as it is to carry out acylation. After that, the temperature of the oil bath was raised to 275 ° C over 2 hours, and zinc acetate dihydrate 0.0
Add 68 g and gradually apply vacuum. Then, after a high vacuum of 0.3 mmHg is reached, polymerization is carried out for 4 hours. The product is taken out by breaking the glass polymerization tube, chipped, and vacuum dried at 130 ° C. overnight. The polymer obtained is opalescent and opaque.
It was inh = 0.59.

Even when the polymer was oven dried at 120 ° C. for 130 hours, ηinh = 0.59, which was excellent in thermal stability.

Moreover, the acid anhydride bond was completely absent from the result of IR.

Examples 2 to 5 Comparative Examples 1 to 3 Oligoethylene terephthalates (b) to (e) having the same formulation as Example 1 (corresponding to Examples 2 to 5 respectively)
(F), (g), and (h) (corresponding to Comparative Examples 1, 2, and 3 respectively) were used. The polymerization time of Comparative Example 3 was 12 hours. 13 oven dry them at ηinh and 120 ° C
Ηinh after 0 hours and polymer anhydride bond (IR
(Measurement) is summarized below.

In Examples 1 to 5, the stability of the polymer was good and there was no acid anhydride bond, and in Comparative Examples 1 and 2, the polymer was poor in stability and the acid anhydride bond was detected.

Example 6 30.7 g of oligoethylene terephthalate (b) and 88.3 g of parahydroxybenzoic acid were charged, and transesterification was performed at 220 ° C. for 2 hours to prepare a copolymerized oligomer, and then 140 ° C.
Then, 81.6 g of acetic anhydride was dropped, and thereafter, the procedure was exactly the same as in Example 1.

Ηinh of this polymer was 0.94, ηinh was 0.93 after oven drying at 120 ° C. for 130 hours, and no acid anhydride bond was detected.

〔The invention's effect〕

As described above, according to the method of the present invention, a copolyester having excellent thermal stability can be obtained.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Shigeru Muramatsu 1 Toho-cho, Yokkaichi-shi, Mie Mitsubishi Chemical Industries Yokkaichi Plant (56) Reference JP-A-63-277231 (JP, A) JP-A-SHO 61-181825 (JP, A) JP 60-245630 (JP, A) JP-B 3-64533 (JP, B2)

Claims (9)

[Claims] 1. A general formula (A) [Wherein R ¹ is a divalent aromatic hydrocarbon group having 6 to 20 carbon atoms, a divalent alicyclic hydrocarbon group having 4 to 20 carbon atoms and / or a divalent aliphatic group having 1 to 40 carbon atoms] Represents a hydrocarbon group (however, the hydrogen atom of the aromatic ring of the aromatic hydrocarbon group may be substituted with a halogen atom, an alkyl or alkoxy group having 1 to 4 carbon atoms), and R ² has 2 to 2 carbon atoms. 40 divalent aliphatic hydrocarbon groups, 4 to 20 carbon divalent alicyclic hydrocarbon groups, 6 to 20 carbon atoms forming an aromatic ring divalent aromatic hydrocarbon group (however, The hydrogen atom of the aromatic ring of the aromatic hydrocarbon group may be substituted with a halogen atom, an alkyl group having 1 to 4 carbon atoms or an alkoxy group), or a polyalkylene oxide divalent radical having a molecular weight of 80 to 8000]. The starting oligoester consisting of the repeating units represented is 5-9 by the amount of the repeating units constituting them. 5 mol% and the general formula (B) HO—R ³ COOH (B) [wherein R ³ has 6 to 20 carbon atoms forming an aromatic ring 2]
95-5 mol% of a hydroxycarboxylic acid represented by a valent aromatic hydrocarbon group (provided that the hydrogen atom of the aromatic hydrocarbon group may be substituted with a halogen atom, an alkyl group having 1 to 4 carbon atoms or an alkoxy group) To produce a copolymerized oligomer (first step), then an acylating agent is added to perform acylation (second step), and polymerization is further performed under reduced pressure (third step). In the above, as the raw material oligoester, the terminal OH group and the terminal COOH group are —O—R ² —O—
With respect to 100 equivalents, 10 equivalents ≦ terminal OH group equivalent−terminal COOH group equivalent ≦ 70 equivalent
[I] A method for producing a copolyester, characterized by using the following. 2. The method for producing a copolyester according to claim 1, wherein the raw oligoester has substantially no terminal COOH group. 3. A raw oligoester is And those prepared from a ^{HO-R 2 -OH (R 5} , R 4 represents an alkyl group, R ^1, R ² is Formula (A) and synonymous.) Claims, characterized in that A method for producing a copolyester according to claim 1. 4. The method for producing a copolyester according to claim 1, wherein the amount of the acylating agent is the amount of the acylating agent / the amount of the hydroxycarboxylic acid is 1.5 (molar ratio). . 5. The production method according to claim ¹ , wherein 60% or more of R ^{1 in} the formula (A) is a 1,4-phenylene group. 6. The method according to claim 1, wherein R ² in the formula (A) is an aliphatic hydrocarbon group having 2 to 6 carbon atoms. 7. The method according to claim ^1, wherein R ¹ in the formula (A) is a 1,4 phenylene group. 8. The method according to claim 1, wherein R ² in the formula (A) is an aliphatic hydrocarbon group having 2 carbon atoms. 9. The production method according to claim 1, wherein R ³ in the formula (B) is a 1,4 phenylene group.