JPH07330883A - Production of high-polymerization degree aliphatic polyester - Google Patents

Abstract

PURPOSE:To highly easily obtain the subject polyester excellent in biodegradability and mechanical performance by reaction of a specific compound with an OH-terminated low-polymerization degree aliphatic polyester. CONSTITUTION:This polyester is obtained by reaction of a (A) hydroxyl- terminated low-polymerization degree aliphatic polyester with (B) an N,N'- acylbislactam compound of the formula (R<1> is a divalent aliphatic group; (n) is 0 or 1) (e.g. N,N'-succinylbiscaprolactam) normally at 0.01-10 pts.wt. based on 100 pts.wt. of the component A. It is preferable that the acid component constituting the component A be succinic acid or adipic acid, the glycol component be ethylene glycol or propylene glycol, and the objective polyes has >=60 deg.C melting point and >=30000 number-average molecular weight.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing a high molecular weight aliphatic polyester having excellent mechanical properties. More specifically, the main constituent is an aliphatic polyester,
A high degree of polymerization sufficient to have excellent mechanical performance,
Moreover, the present invention relates to a method for producing a high molecular weight aliphatic polyester which is rich in biodegradability.

[0002]

2. Description of the Related Art From the standpoint of global environment conservation, various degradable materials have been developed also in the field of polymers. Among them, as biodegradable polymers, polyesters, especially aliphatic polyesters, have been mainly developed. For example, polyesters obtained by ring-opening polymerization of lactones such as lactide, glycolide, β-propiolactone, γ-valerolactone and ε-caprolactone, polyesters containing an aliphatic dicarboxylic acid component and an aliphatic diol component are excellent in biodegradability. It is a material.

However, the polymerization reaction of these is generally slow, and it is difficult to obtain a polymer having a high degree of polymerization. Therefore, it has been proposed to use a specific polymerization catalyst or to increase the degree of polymerization by adding a diisocyanate compound capable of reacting with a hydroxyl group terminal and highly polymerizing, as a polymer chain extender (JP-A-5-295068, JP-A-5-2950
69, JP-A-5-295070, and JP-A-5-295.
071, JP-A-5-295098, and JP-A-5-29
5099, etc.). Specifically, for example, a low polymerization degree aliphatic polyester having a hydroxyl group at the polymer terminal and prepared from adipic acid or succinic acid and 1,4-butanediol, hexamethylene diisocyanate, diphenylmethane diisocyanate, isophorone diisocyanate, tolylene diisocyanate A polyvalent isocyanate such as isocyanate is added, and a hydroxyl group terminal and an isocyanate group are reacted with each other to form a urethane bond, thereby achieving high polymerization.

This method is effective for high polymerization and, as a result, improvement of mechanical properties, but it introduces a biodegradable urethane bond into the polymer chain, resulting in biodegradation. Deteriorates performance.

[0005]

An object of the present invention is to provide a method for producing an aliphatic polyester having a high degree of polymerization which is excellent in biodegradability and mechanical performance.

[0006]

[Means for Solving the Problems] In order to obtain a high-polymerization degree aliphatic polyester which is easy to polymerize a low molecular weight aliphatic polyester, is excellent in physical properties, and is excellent in biodegradability. As a result of intensive studies, the inventors have found a chain extender capable of promoting biodegradability as well as exerting no influence on biodegradability, and thus reached the present invention.

That is, according to the present invention, a low-polymerization degree aliphatic polyester having a hydroxyl group at the polymer chain end and the following general formula (1)

[0008]

[Chemical 2]

(In the formula, two R _{1 s} are the same or different and each is a divalent aliphatic group, R ₂ is a divalent organic group, n is the number of R ₂ , and Or 1, the N, N′-acylbislactam compound represented by the formula (1) is reacted to provide a method for producing a highly polymerized aliphatic polyester, and the above-mentioned object of the present invention is achieved.

The present invention will be described in detail below, and the other objects, constitutions and advantages and effects based on the same of the present invention will become apparent.

The low-polymerization degree aliphatic polyester, which is a precursor for obtaining the high-polymerization degree aliphatic polyester, is one of all components constituting the high-polymerization degree aliphatic polyester from the viewpoint of biodegradability. , With 8 aliphatic components
It is preferably 0 mol% or more, and particularly preferably 90 mol% or more.

Among the components constituting the low-polymerization degree aliphatic polyester, an aliphatic dicarboxylic acid having 2 to 12 carbon atoms is preferable as an acid component, and specifically, oxalic acid, succinic acid, glutaric acid, adipic acid and suberic acid. , Azelaic acid, sebacic acid, dodecanoic acid and the like. Also,
The glycol component constituting the polyester is preferably an aliphatic glycol having 2 to 12 carbon atoms, and specific examples thereof include ethylene glycol, propylene glycol, tetramethylene glycol and hexanemethylene glycol. These acid components or glycol components may be used alone or in combination of two or more.

Further, a lactone component can be mentioned as a component constituting the low-polymerization degree aliphatic polyester.
As the lactone component, a lactone having 3 to 8 carbon atoms is preferable, and specific examples thereof include lactide, glycotide, propiolactone, valerolactone, and caprolactone.

Further, the low degree of polymerization aliphatic polyester is
A trifunctional or higher functional polyhydric alcohol component such as glycerol or pentol, and a trifunctional or higher functional component such as malic acid, citric acid or tartaric acid may be included.

The low degree of polymerization aliphatic polyester has a hydroxyl group at the polymer terminal, but it is not necessary that the hydroxyl group be present at the terminal of all polymer chains.

Such a low-polymerization degree aliphatic polyester can be obtained by a method known per se. For example, a direct esterification reaction of dicarboxylic acid or its acid anhydride with glycol, or a transesterification reaction of dicarboxylic acid diester with glycol to give a glycol ester of dicarboxylic acid, and then a deglycolization reaction under reduced pressure to carry out a polymerization reaction. Is common.

For these reactions, it is effective to use a catalyst if necessary. As the catalyst, those known per se can be used, and for example, an organometallic compound is preferably used. As such metal compounds, titanium tetrabutoxide, tetraisopropyl titanate, titanium compounds such as titanium acetate, tin compounds such as dibutyltin oxide, aluminum compounds such as triethylaluminum, antimony trioxide, antimony acetate, germanium oxide, zinc acetate, etc. Can be preferably exemplified.

In the present invention, the low-polymerization degree aliphatic polyester as a precursor is reacted with the N, N′-acylbislactam compound represented by the above formula (1) to obtain the following reaction formula (2).

[0019]

[Chemical 3]

According to the above, a high-polymerization degree aliphatic polyester is produced.

In the general formula (1), R ₁ is a divalent aliphatic group, and the carbon number of R ₁ is 1 to form a ring.
It is preferably 10 to 10. Preferred specific examples of R ₁ include methylene, ethylene, trimethylene, tetramethylene, pentamethylene, hexamethylene, heptamethylene, octamethylene, decamethylene and the like. The two R _{1 s} in the general formula (1) may be the same or different.

R ₂ in the general formula (1) is a divalent organic group, and preferably has 1 to 12 carbon atoms.
Specific preferred examples of R ₂ include aliphatic groups such as methylene, ethylene, propylene and tetramethylene, alicyclic groups such as cyclohexylene and aromatic groups such as phenylene, biphenylene and naphthalene.

In the lactam compound represented by the general formula (1), R ₂ may be absent and two carbonyl groups may be directly bonded. Specific examples of the lactam compound represented by the general formula (1) include N, N'-succilbiscaprolactam, N, N'-adipylbisbutyrolactam, N, N'-
Suberyl biscaprolactam, N, N'-succil bispiperidone, N, N'-adipyl bispiperidone, N,
Condensates of monolactam with aliphatic dicarboxylic acids such as N'-adipylbisbutyrolactam, N, N'-adipylbispyrrolidone, N, N'-terephthaloylbiscaprolactam, N, N'-tere Phthaloyl bispiperidone,
N, N'-terephthaloylbisbutyrolactam, N, N '
Examples thereof include a condensate of an aromatic dicarboxylic acid such as terephthaloylbispyrrolidone and N, N′-isophthaloylbiscaprolactam with a monolactam.

The N, N'-acyl bislactam compound represented by the general formula (1) is an aliphatic polyester having the highest degree of polymerization by using the same amount as the hydroxyl group present in the precursor, the low degree of polymerization aliphatic polyester. Is obtained. Normal,
Low degree of polymerization is 100 parts by weight per 100 parts by weight of polyester.
01 to 10 parts by weight is used. The amount of the bislactam compound used can be appropriately adjusted in order to obtain a high-polymerization degree aliphatic polyester having a desired molecular weight. Excessive use of the bislactam compound may cause coloration and gel formation.

Regarding the reaction between the low-polymerization degree aliphatic polyester and the lactam compound represented by the general formula (1), (a) the polycondensation reaction for producing the precursor low-polymerization degree aliphatic polyester has considerably progressed. At this point, the bislactam compound is added, and the reaction is carried out while stirring at a temperature not lower than the melting temperature of the polyester, preferably not lower than 300 ° C. (b) Once the low polymerization degree aliphatic polyester has been obtained, Examples include a method in which a bislactam compound and a polyester are melt-mixed at a temperature equal to or higher than the melting temperature of the polyester and reacted before molding.

As a means for mixing the bislactam compound represented by the formula (1) with the low degree of polymerization aliphatic polyester, it may be mixed directly or may be dissolved in a solvent and mixed.

Further, it is preferable to carry out the reaction under reduced pressure so that lactam produced as a by-product during the reaction is removed to the outside of the reaction system.

In the thus obtained high-polymerization degree aliphatic lactam, the constituent units are substantially bound only via the ester bond. The number average molecular weight is 1 as a value measured by the method described in Examples below.
A degree of polymerization of 2,000 or more is preferred. In order to further improve the physical properties of the molded product, the number average molecular weight should be 2
It is preferably 20,000 or more, more preferably 30,000 or more. Further, the melting point of the high-polymerization degree aliphatic polyester is preferably 60 ° C. or higher in terms of practicality. In addition, various modifiers,
Needless to say, for example, an inorganic pigment, an organic pigment, a heat stabilizer, an oxidation stabilizer, a light resistance improver or the like may be added.

The high-polymerization degree aliphatic polyester obtained by the method of the present invention has a high strength and a high biodegradability because it can be produced in a short time, has excellent mechanical properties, and has an improved biodegradability. It is possible to obtain a molded product of This highly polymerized aliphatic polyester can be spun, stretched to form a thread, or discharged from a die to form a film, and can be injection-molded to be an injection-molded article.

[0030]

EXAMPLES The present invention will be specifically described with reference to the following examples. The molecular weight was determined by gel permeation chromatography (GPC) of JASCO Corporation. The measurement conditions are as follows. Sample: 50 mg dissolved in a mixed solvent of chloroform (9.8 ml) and hexafluoroisopropanol (0.2 ml) Column: SHODEX K-803 to 806 4 columns Temperature: 40 ° C. Flow rate: 1.0 ml / min Detector; 830-RI standard polymer manufactured by JASCO Corporation; polystyrene (Waters (Mill
ipore corp. In addition, "parts" in the examples are all parts by weight,
The melting point was measured by a differential scanning calorimeter (DSC) in Chisso.
It is a value measured at a temperature rising rate of 20 ° C./min.

[Example 1] 146 parts of dimethyl succinate and 135 parts of tetramethylene glycol were placed in a three-necked flask equipped with a rectification column, 0.14 parts of tetrabutoxytitanium as a catalyst was added, and the temperature was raised. , Transesterification reaction was carried out, and the generated methanol was distilled off. Then, the reaction product was transferred to a three-necked flask equipped with a stirrer and a condenser, and under a nitrogen atmosphere at a temperature of 250 ° C. under atmospheric pressure for 5 minutes,
Then, while depressurizing, finally, polymerization was carried out under a high vacuum of 0.1 mmHg while deglycolizing. When the torque increase of the stirrer slowed down, break the vacuum with nitrogen,
N, N'-terephthaloylbiscaprolactam (hereinafter,
0.86 parts (abbreviated as TCL) (corresponding to 0.5% by weight with respect to the polyester) was added as a powder while stirring, and a reaction occurred while foaming. After the addition, the pressure was reduced and the reaction was continued for 15 minutes. During this period, the torque of the stirrer increased and the melt viscosity was rapidly increased. The obtained polyester was taken out and the molecular weight was measured by GPC. As a result, a light yellow polyester having a very high molecular weight, having a number average molecular weight Mn of 197,000 and a weight average molecular weight Mw of 462,000, was obtained. Melting point measured by DSC is 115 ° C
No nitrogen component was detected by elemental analysis, and it was confirmed by infrared spectroscopic analysis (FI-IR) that there was no amide group derived from lactam in the polymer.

[Comparative Example 1] Example 1 without adding TCL
When a polyester was polymerized in the same manner as above, the degree of polymerization did not increase, and Mn = 18,000 and Mw = 44,000, and only a polyester having a low molecular weight was obtained.

Comparative Example 2 Diphenylmethane diisocyanate (DPMDI) was used instead of TCL in Example 1.
When 2.0 parts was similarly added at a temperature of 250 ° C. at the final stage of the polymerization, not only coloring but also a gel-like substance considered to originate from the urethane bond formed was generated.

[Examples 2, 3 and 4] In the same manner as in Example 1, after carrying out the transesterification reaction and the polymerization reaction,
TCL was added to polyester in the weight ratios shown in Table 1, and the reaction under reduced pressure was carried out for 15 minutes. The physical properties of the obtained polymer are summarized in Table 1. All were high molecular weight polyesters.

[0035]

[Table 1]

[Examples 5, 6 and 7] 174 parts of dimethyl adipate, 135 parts of tetramethylene glycol and 0.139 parts of tetrabutyl titanate were mixed to prepare Example 1
The transesterification reaction and the subsequent polymerization reaction were carried out in the same manner as above, and when the increase in melt viscosity slowed down, a predetermined amount of TCL shown below was added, and the mixture was reacted under reduced pressure for 15 minutes. The molecular weight and melting point of the obtained polyester are shown in Table 2.

[0037]

[Table 2]

[Comparative Example 3] In the same manner as in Example 5, TC
When polymerized without using L, Mn = 13,000,
It was Mw = 27,000.

[Examples 8, 9 and 10] Succinic acid and adipic acid were charged at a molar ratio of 9/1, 8/2 and 7/3 (succinic acid / adipic acid), respectively, and tetramethylene glycol (C ₄ G) was added in a molar amount of 1.5 times the total amount of succinic acid and adipic acid, a direct esterification reaction was carried out at a reaction temperature of 200 ° C., water was distilled off, and 10 mmol% of tetrabutoxytitanium was added to prepare 220 Polymerization reaction was carried out under reduced pressure at ° C. After the polymerization reaction under vacuum for 3 hours, 2.61 parts, 2.67 parts and 2.71 parts (corresponding to 1.5% by weight based on polyester) of TCL were added respectively, and the reaction was carried out under reduced pressure for 15 minutes. After continuing, the viscosity increased rapidly. However, there was no phenomenon of gelation. Table 3 shows the physical properties of polyester.

[0040]

[Table 3]

Example 11 The polyesters obtained in Examples 1 to 10 were melted at 150 ° C. and pressure-molded to give a thickness of 200.
It was made into a sheet shape of μm. Then 50 mg of this sample
Is immersed in 100 ml of a phosphate buffer solution (pH = 7) containing 50 mg of the degrading enzyme Rhizopus alizae,
The samples were treated at 35 ° C. for 72 hours and the weight loss rates were compared. For comparison, samples of Comparative Examples 1 and 3 not using TCL and Comparative Example 2 using DPMDI were simultaneously evaluated for reference. The results are shown in Table 4.

[0042]

[Table 4]

From the above examples, it can be seen that the high degree of polymerization aliphatic polyester produced by the method of the present invention is also excellent in biodegradability.

[0044]

EFFECTS OF THE INVENTION According to the present invention, an aliphatic polyester having a high degree of polymerization can be obtained very easily, and the obtained polyester has no urethane bond, and practically all of the bonds are esters, which is excellent. Has biodegradability. Since the product from this polyester has a high molecular weight, it has excellent mechanical properties and is useful as a general resin, film or fiber. INDUSTRIAL APPLICABILITY The present invention provides a method for producing an excellent material that can be used particularly for applications requiring biodegradability.

Claims (5)

[Claims] 1. A low-polymerization degree aliphatic polyester having a hydroxyl group at a polymer chain end and the following general formula (1): (In the formula, two R _{1 s} are the same or different and each is a divalent aliphatic group, R ₂ is a divalent organic group, n is the number of R ₂ , and is 0 or 1. A) a N, N′-acylbislactam compound represented by the formula (1) is reacted. 2. The production method according to claim 1, wherein the acid component of the low-polymerization degree aliphatic polyester contains at least one of succinic acid and adipic acid as a main component. 3. The N, N′-acylbislactam compound represented by the formula (1) is a condensate of an aliphatic dicarboxylic acid and a monolactam or a condensate of an aromatic dicarboxylic acid and a monolactam. 2. The manufacturing method according to 2. 4. The high-polymerization degree aliphatic polyester has a melting point of 6
4. The method according to claim 1, wherein the number average molecular weight is 0 ° C. or higher and the number average molecular weight is 30,000 or higher. 5. The production method according to claim 1, wherein the high-polymerization degree aliphatic polyester is biodegradable.