JPH0892361A - Production method of aliphatic polyester - Google Patents

Abstract

(57) [Abstract] [PROBLEMS] To provide a method for producing a high molecular weight aliphatic polyester from a dibasic aliphatic carboxylic acid diester and an aliphatic glycol, which has improved mechanical properties such as mechanical strength. A method for producing an aliphatic polyester by reacting a dibasic aliphatic carboxylic acid diester and an aliphatic glycol, which is divided into at least two times at intervals of at least 10 minutes at the start of the reaction and during the reaction. A method for producing an aliphatic polyester, which comprises adding a catalyst to a reaction system.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for producing an aliphatic polyester.

[0002]

2. Description of the Related Art Conventionally, dibasic aliphatic carboxylic acids such as oxalic acid, malonic acid, succinic acid, and adipic acid, and aliphatic polyesters such as ethylene glycol and 1,4-butanediol have been used in the synthesis of aliphatic polyesters. The method of polycondensing glycol or the method of ring-opening polymerization of cyclic lactones has been generally used.

However, in the polycondensation reaction between the dibasic aliphatic carboxylic acid and the aliphatic glycol, since the dibasic aliphatic carboxylic acid is a solid at room temperature, a large stirring power is required when starting the reaction with the aliphatic glycol. It is inconvenient to handle. And more importantly, the number average molecular weight (hereinafter sometimes abbreviated as Mn) is 2
It is extremely difficult to synthesize more than 10,000 aliphatic polyesters. Therefore, the obtained aliphatic polyester having Mn of less than 20,000 has a drawback that mechanical properties such as mechanical strength generally required as a resin are insufficient.
It has been difficult to mold films, fibers and other molded articles.

Therefore, in order to obtain a high molecular weight aliphatic polyester, the aliphatic polyester synthesized by the reaction of a dibasic aliphatic carboxylic acid and an aliphatic glycol is further reacted with diisocyanate as a crosslinking agent to increase the molecular weight. A method has been reported (JP-A-4-189822). However, in this method, the reaction process has two stages, and the operation becomes complicated. In addition, mechanical properties such as strength at break and elongation at break are significantly reduced due to a three-dimensional crosslinking reaction or the like. Furthermore, due to the nitrogen and metal elements that the crosslinking agent has,
There are problems such as deterioration of insulation rate, coloring, deterioration of biodegradability, and concern about environmental safety of decomposition products.

Further, in JP-A-5-310898, a polyester diol is produced from a glycol component and an aliphatic dicarboxylic acid (or its anhydride) component, and then, in the presence of a catalyst, at high temperature and high vacuum (0 0.005-0.1
A method for producing a high molecular weight aliphatic polyester by carrying out a deglycolization reaction at mmHg) is disclosed. However, in the above method, the reaction must be carried out under high vacuum, the control is complicated, and the apparatus becomes special and expensive.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to improve mechanical properties such as mechanical strength in a synthetic method of aliphatic polyester by polycondensation reaction of dibasic aliphatic carboxylic acid diester and aliphatic glycol. It is to provide a method for producing a high molecular weight aliphatic polyester.

[0007]

The present invention provides (1) a method for producing an aliphatic polyester by reacting a dibasic aliphatic carboxylic acid diester and an aliphatic glycol,
It is a process for producing an aliphatic polyester by adding the catalyst to the reaction system at least twice at intervals of at least 10 minutes at the start of the reaction and during the reaction.

In a preferred embodiment of the present invention, (2) the dibasic aliphatic carboxylic acid diester contains 30% by weight or more of the succinic acid diester, and (3) the succinic acid diester is succinic acid. A method for producing the aliphatic polyester according to the above (2), which is diethyl acid;
(4) Aliphatic glycol is 1,4-butanediol 7
The method for producing an aliphatic polyester according to any one of (1) to (3) above, which comprises 0% by weight or more, and (5) the reaction is carried out at normal pressure and subsequently at reduced pressure, at the start of the reaction and at the reaction step of the reduced pressure. The method for producing an aliphatic polyester according to any one of (1) to (4) above, wherein the catalyst is reacted once within 30 minutes to 5 hours after starting the reduced pressure reaction. Examples thereof include the method (5) for producing an aliphatic polyester added to the system.

Examples of the dibasic aliphatic carboxylic acid diester used in the present invention include diesters of dibasic carboxylic acid having 2 to 10 carbon atoms. Specifically, succinic acid diester, adipic acid diester, dodecane dicarboxylic acid diester, oxalic acid diester, malonic acid diester, glutaric acid diester, pimelic acid diester, suberic acid diester, azelaic acid diester,
Examples thereof include sebacic acid diester and nonanedicarboxylic acid diester. Since many dibasic aliphatic carboxylic acid diesters are liquid at room temperature, they are easier to stir at the start of the reaction and have higher stirring efficiency than when dibasic aliphatic carboxylic acids are used. The dibasic aliphatic carboxylic acid diester is preferably dimethyl or diethyl ester in terms of cost and ease of reaction operation. Among them, dimethyl succinate or diethyl succinate is particularly preferable. Further, diethyl succinate is preferable to dimethyl succinate because it has a lower melting point, is a liquid at around room temperature, is easy to handle, and has a high boiling point to raise the reaction temperature. The dibasic aliphatic carboxylic acid diesters may be used alone or in combination of two or more. For example, a mixture of 30 to 90% by weight of diethyl succinate and 10 to 70% by weight of another dibasic aliphatic carboxylic acid diester such as diethyl adipate or / and diethyl dodecanedicarboxylate can be used.

Examples of the aliphatic diol that can be used in the present invention include those having an alkylene group having 2 to 10 carbon atoms. Specifically, ethylene glycol, 1,4-butanediol, 1,6-hexanediol, 1,2-propanediol, 1,3-propanediol, 1,3-butanediol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, 1,7
-Heptanediol, 1,8-octanediol, 1,
9-nonanediol, 1,10-decanediol, neopentyl glycol and the like can be mentioned. Among these, ethylene glycol, 1,4-butanediol, 1,6-
Hexanediol is preferable because it can produce an aliphatic polyester having a high melting point and excellent moldability. The above aliphatic glycols may be used alone or in combination of two or more.

The method for synthesizing the aliphatic polyester of the present invention is a known polyester production method in which a dibasic aliphatic carboxylic acid diester is used in place of the dibasic aliphatic carboxylic acid, and a catalyst is used at the start of the reaction and During the reaction,
At least 2 at least 10 minutes apart from each other
It is characterized in that it is added in batches. The aliphatic polyester thus obtained has a high molecular weight. The catalyst is preferably added at least once to the reaction system at the start of the reaction and in the reaction step of reduced pressure in the reaction step performed at normal pressure and subsequently under reduced pressure, and the reduced pressure reaction is performed in the reaction step of reduced pressure. It is preferable to add the catalyst to the reaction system within 30 minutes to 5 hours after the start. More preferably, the starting point of the reaction and the point of time when the reduced pressure reaction is performed for about 2 hours can be mentioned. In the present invention, by adding the catalyst at least twice, it is possible to produce a higher molecular weight aliphatic polyester with the same catalyst amount as compared with the method of adding the catalyst only once at the start of the reaction. Is also less colored.

The amount of catalyst in each time may be an amount obtained by equally dividing the total amount of catalyst, but is not limited thereto. When the total amount of catalyst (X) is added in n times, the amount of catalyst in one time is, for example, 0.1 · X / n or more, particularly 0.3 ·.
It is preferably X / n or more.

The catalysts that can be used in the present invention include Ti, Ge, Zn, Fe, Mn, Sn, Co and Z.
Examples thereof include metal compounds such as r, V, Ir, Ce, Li and Ca, preferably organic metal compounds such as alkoxide and acetylacetonate. Among these, for example, oxobis (acetylacetonato) titanium, dibutoxydiacetoacetoxytitanium, tetraethoxytitanium, tetraisopropoxytitanium, tetrabutoxytitanium and the like are highly active and particularly preferable. The amount of the catalyst used may be in a conventional range, and is usually about 10 mmol to 0.0 per 1 mol of the dibasic aliphatic carboxylic acid diester as a raw material.
It is 1 millimole, preferably about 5 millimole to 0.1 millimole (this amount of catalyst means the total amount of catalyst used in two or more portions).

In the present invention, the reaction is preferably carried out at normal pressure and subsequent reduced pressure. Normal pressure reaction is about 20-22
It is carried out at 0 ° C. under an atmosphere of an inert gas until the alcohol is completely distilled off. If the temperature is lower than this temperature, the reaction rate is slow and the practicality is poor, and if the temperature is higher than this temperature, the risk of polymer decomposition is high, which is not preferable.

The reduced pressure reaction is carried out at about 150 to 250 ° C. under a vacuum of about 30 to 0.1 Torr. In order to obtain a higher molecular weight aliphatic polyester, it is preferable to carry out the pressure reduction in two or more steps. For example, first, about 20 to 5 To
The pressure is reduced to rr and the temperature is about 150 to 220 ° C. and the pressure is about 0.
Do for 5 to 2 hours. Then, set the vacuum degree to about 3 to 0.5 Torr.
to about 1 to 10 at a temperature of about 180 to 250 ° C.
Allow more reaction for time. The catalyst may be added at any time during the depressurization reaction even when the depressurization is performed in two or more steps, but it is preferable to add the catalyst at least once during the depressurization reaction after the second step.

The final addition of the catalyst is preferably carried out at least 30 minutes before the end of the reaction.

In the method of the present invention, if necessary, various additives such as an antioxidant, a reaction accelerator and an ultraviolet absorber can be added to the reaction system. As a result, the effects of shortening the manufacturing process and improving the physical properties of the resulting aliphatic polyester can be obtained.

Examples of the above antioxidant include hydroquinone monoalkyl ether and the like.

The present invention will be described in more detail with reference to the following examples.

[0020]

【Example】

(Example 1) Diethyl succinate (hereinafter abbreviated as DES) 1.0 mol, 1,4-in a 500 ml separable flask equipped with a stirrer, a nitrogen inlet, and a Liebig condenser.
After adding 1.2 mol of butanediol (hereinafter abbreviated as BDO) and replacing the inside of the flask with nitrogen, 0.5 mmol of tetraisopropoxytitanium was added, and the reaction temperature was gradually raised to 160 ° C. with vigorous stirring. Then, the reaction was continued as it was for about 2 hours until the ethanol was no longer distilled off. Then, reduce the pressure in the flask to 10 Torr and
The reaction was conducted for an hour, the pressure was further reduced to 1 Torr, and the pressure was maintained for 1 hour. Then, tetraisopropoxy titanium 0.5m
mol was added, the temperature was raised, and polycondensation was performed for 4 hours under the conditions of a reaction temperature of 220 ° C. and a vacuum degree of 1 Torr. The yield of the obtained white resin was 95% or more based on the DES used. Moreover, Mn and Mw (in terms of polymethylmethacrylate) were measured by GPC. The results are shown in Table 1. Furthermore, using the obtained resin, molding under the following conditions,
The mechanical properties of the molded product were measured. The results are shown in Table 2.
Molding conditions: injection molding was performed at 150 ° C., and physical properties were measured 3 days after molding.

(Example 2) The second addition of the catalyst was carried out by 1T.
A resin was produced in the same manner as in Example 1 except that it was performed immediately before the pressure was reduced to orr. The yield of the obtained resin is 9
It was 5% or more. The Mn and Mw of the obtained resin are shown in Table 1.
Shown in. In addition, molding was performed in the same manner as in Example 1 to measure the mechanical properties of the molded product. The results are shown in Table 2.

Example 3 A resin was produced in the same manner as in Example 1 except that a mixture of DES 80% by weight and diethyl adipate 20% by weight was used as the dibasic aliphatic carboxylic acid diester. The yield of resin obtained is 90%
That was all. Table 1 shows Mn and Mw of the obtained resin. In addition, molding was performed in the same manner as in Example 1 to measure the mechanical properties of the molded product. The results are shown in Table 2.

Example 4 A resin was produced in the same manner as in Example 1 except that a mixture of DES 60% by weight and diethyl adipate 40% by weight was used as the dibasic aliphatic carboxylic acid diester. The yield of resin obtained is 90%
That was all. Table 1 shows Mn and Mw of the obtained resin. In addition, molding was performed in the same manner as in Example 1 to measure the mechanical properties of the molded product. The results are shown in Table 2.

Example 5 40% by weight of DES as dibasic aliphatic carboxylic acid diester, diethyl adipate 3
0% by weight and diethyl dodecanedicarboxylate 30% by weight
A resin was produced in the same manner as in Example 1 except that the mixture of above was used. The yield of the obtained resin was 90% or more. Table 1 shows Mn and Mw of the obtained resin. Also,
Molding was performed in the same manner as in Example 1, and the mechanical properties of the molded product were measured. The results are shown in Table 2. (Example 6) A resin was produced in the same manner as in Example 1 except that a mixture of 80% by weight of BDO and 20% by weight of ethylene glycol was used as the aliphatic glycol. The yield of resin obtained is 90%
That was all. Table 1 shows Mn and Mw of the obtained resin. In addition, molding was performed in the same manner as in Example 1 to measure the mechanical properties of the molded product. The results are shown in Table 2.

(Example 7) BD as an aliphatic glycol
80% by weight O and 20% by weight 1,6-hexanediol
A resin was produced in the same manner as in Example 1 except that the mixture of 1 was used. The yield of the obtained resin was 90% or more.
Table 1 shows Mn and Mw of the obtained resin. In addition, molding was performed in the same manner as in Example 1 to measure the mechanical properties of the molded product. The results are shown in Table 2.

Example 8 A resin was produced in the same manner as in Example 1 except that titanium tetrabutoxy was used as the catalyst. The yield of the obtained resin was 95% or more.
Table 1 shows Mn and Mw of the obtained resin. In addition, molding was performed in the same manner as in Example 1 to measure the mechanical properties of the molded product. The results are shown in Table 2.

Comparative Example 1 1.0 mmol at the start of the reaction
A resin was produced in the same manner as in Example 1 except that tetraisopropoxy titanium was added and the second addition of the catalyst was not performed. The yield of the obtained resin was about 85%. Table 1 shows Mn and Mw of the obtained resin. Also,
An attempt was made to carry out molding to measure the mechanical properties of the molded product in the same manner as in Example 1, but the resin obtained was extremely brittle and did not have the strength to withstand the work of molding / mechanical properties measurement. It was

COMPARATIVE EXAMPLE 2 1.0 mol of succinic acid and 1.2 mol of BDO were placed in a 500 ml separable flask equipped with a stirrer, a nitrogen inlet, and a Liebig condenser.
After purging the inside of the flask with nitrogen, the reaction temperature was gradually raised to 200 ° C. with vigorous stirring. Then, the reaction was continued as it was until the water was distilled off. After that, the pressure inside the flask was reduced to 10 Torr and the reaction was performed for 1 hour, 1.2 mmol of tetraisopropoxytitanium was added, the pressure was further reduced to 1 Torr, and the temperature was raised to 220 ° C.
Polycondensation was carried out for 4 hours under the conditions of ° C and a vacuum degree of 1 Torr. The yield of the obtained white resin was 90% or more based on the used succinic acid. Table 1 shows Mn and Mw of the obtained resin. Further, the mechanical properties of the obtained resin were measured in the same manner as in Example 1. The results are shown in Table 2.

[0029]

[Table 1]

[0030]

[Table 2] Since the method of the present invention has almost no carboxyl group in the reaction system, and that the component to be distilled is an alcohol having a smaller latent heat than water, it is polymerized as compared with the case of using a dibasic aliphatic carboxylic acid.・ Debalance of depolymerization is different, M
It is considered that an aliphatic polyester in which n exceeds 30,000 can be easily synthesized.

As is apparent from Examples 1 and 2 and Comparative Example 1, in order to produce a high molecular weight aliphatic polyester having sufficient mechanical properties, it is necessary to add the catalyst at least twice. Is. According to the method of the invention,
An aliphatic polyester having sufficient mechanical properties can be obtained without using a crosslinking agent. As a result, the problems caused by nitrogen and metals that are often contained in the crosslinking agent do not occur. Further, as is clear from Examples 3 to 7, mechanical properties such as bending strength, tensile strength and impact resistance are controlled by copolymerizing two or more kinds of dibasic aliphatic carboxylic acid diesters or aliphatic diols. it can.

[0032]

INDUSTRIAL APPLICABILITY The present invention is a method useful for producing a high molecular weight aliphatic polyester having mechanical properties such as sufficient mechanical strength. The polyester obtained by the method of the present invention is a film or sheet. Suitable for molding etc. Further, the aliphatic polyester produced by the method of the present invention has biodegradability, and thus is an extremely useful polymer for environmental protection.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Hiro Ueno 1-3-1 Nishitsurugaoka, Oi-cho, Iruma-gun, Saitama Prefecture Tonen Corporation Research Institute

Claims (1)

[Claims] 1. A method for producing an aliphatic polyester by reacting a dibasic aliphatic carboxylic acid diester and an aliphatic glycol, which is carried out at least twice at an interval of at least 10 minutes from each other at the start and during the reaction. A method for producing an aliphatic polyester, which comprises adding a catalyst to a reaction system separately.