JPH0753693A - Aliphatic polyester carbonate - Google Patents

Abstract

PURPOSE:To obtain the subject polymer useful as a biodegradable material because of its excellent mechanical strength, fluidity, injection moldability, etc., slight discoloration and high biodegradability, comprising a specific repeating unit. CONSTITUTION:This polymer comprises units of formula I and formula II (R<1> and R<2> are 2-8C alkyls) and has >=15,000 number-average molecular weight. The polymer is preferably obtained by reacting (A) an aliphatic dihydroxy compound with (B) an aliphatic dicarboxylic acid (ester) by using a transesterification catalyst composed of a Zr compound or a Hf compound at 150-220 deg.C while removing bi-products and excessive amount of the component A to give an oligomer having <=5,000 number-average molecular weight and reacting the oligomer with (C) a carbonic acid diester at 200-220 deg.C while removing phenol as a by-product and a small amount of the component A. 1,4- Butanediol is preferable as the component A, succinic acid is the component B and diphenyl carbonate as the component C, respectively.

Description

Detailed Description of the Invention

[0001]

The present invention relates to mechanical strength, fluidity,
The present invention relates to a high-molecular-weight aliphatic polyester carbonate which has excellent properties such as injection moldability and can be used as a packaging material or a molded product and has biodegradability.

[0002]

2. Description of the Related Art Conventionally, polyester carbonates using aromatic compounds have been used in various fields as molded articles, films and glass fiber reinforced plastics. Such aromatic polyesters or polycarbonates usually have a high melting point or show a high glass transition point, and thus have a drawback in melt moldability. Therefore, the melt fluidity can be improved by using an aliphatic compound. For example, production of aromatic and aliphatic copolyester carbonates or polyester carbonates of alicyclic compounds has been proposed. For the production of these polyester carbonates, as disclosed in JP-A-4-226126, an aromatic hydroxy-terminated intermediate is formed from an aromatic compound and an aliphatic dicarboxylic acid, and the polyester carbonate is formed by an interfacial method. However, there is a drawback in using phosgene. Further, JP-A-3-203926 and JP-A-3-200830.
The publication discloses a method for producing a copolyester carbonate composed of an aromatic compound and an aliphatic compound and a polyester carbonate composed of an aromatic compound and an alicyclic compound by a transesterification method. The polyester carbonate obtained by these methods is disclosed. Is not satisfactory because of insufficient melt moldability.

On the other hand, an aliphatic polyester carbonate containing no aromatic compound can be expected to have high melt fluidity.
Although the aliphatic polyester carbonate can be produced by polycondensation, the aliphatic polyester carbonate produced by polycondensation from an organic carbonate compound, an aliphatic dicarboxylic acid compound and an aliphatic diol is sufficient to have practical strength. The reality is that a polymer of molecular weight has not been obtained. For example, JP-A-2-14561
As disclosed in Japanese Patent Laid-Open No. 9-34,785 and Japanese Patent Laid-Open No. 4-342785, an oligomer having a number average molecular weight of about 6000, which is used as a component of polyurethane, is known.

As a method for producing a high molecular weight substance, a high molecular weight substance can be produced by a ring-opening polymerization method using a cyclic monomer. For example, JP-A-4-226527 discloses a cyclic ester of hydroxycarboxylic acid. A method for producing a high molecular weight aliphatic polyester carbonate by ring-opening polymerization using a cyclic carbonate and a cyclic carbonate is disclosed.
Japanese Patent No. 13321 discloses a method for ring-opening polymerization of a cyclic ester by using an hydroxy terminal of an aliphatic polycarbonate as an initiator. The aliphatic polyester carbonate obtained by the above ring-opening polymerization has a hydroxycarboxylic acid unit and an aliphatic carbonate unit as its constituent elements, and is decomposed in a natural environment in order to solve a serious plastic waste treatment problem. Although it is classified as a biodegradable polymer, it cannot be said to be an inexpensive production method because it requires a special cyclic monomer. Further, an aliphatic polyester carbonate produced from an aliphatic diol, an aliphatic dicarboxylic acid and a carbonic acid ester has hitherto not been proposed as a biodegradable polymer.

[0005]

The object of the present invention is that it is excellent in properties such as mechanical strength, fluidity and injection moldability and can be used for packaging materials, molded articles and the like and is useful as a biodegradable polymer. To provide an aliphatic polyester carbonate.

[0006]

[Means for Solving the Problems] As a result of diligent studies on the method for producing a moldable aliphatic polyester carbonate in high yield, the present inventors have found that in the presence of a specific transesterification catalyst, the aliphatic ester Not only the target high molecular weight polyester carbonate can be produced by polycondensing a basic acid or its alkyl ester with an aliphatic dihydroxy compound and a carbonic acid diester, but the obtained polyester carbonate has biodegradability. The present invention has been completed by finding out that there is.

That is, the present invention provides the following formula (1):
It relates to an aliphatic polyester carbonate having a repeating structural unit represented by (2) and having a number average molecular weight of 15,000 or more.

[0008]

[Chemical 2] Here, R ¹ and R ² are the same as above.

The aliphatic polyester carbonate of the present invention having the above structure is a biodegradable polymer.

The production of the aliphatic polyester carbonate of the present invention can be carried out by reacting an aliphatic dihydroxy compound with an aliphatic dicarboxylic acid or its alkyl ester and carbonic acid diester. It is preferable to carry out the reaction in two stages in order to avoid the by-product of the carbonic acid diester having a boiling point and the decomposition of the carbonate bond by the carboxylic acid.

That is, in the first step, the aliphatic dihydroxy compound and the aliphatic dicarboxylic acid or ester thereof are treated at a temperature of 100 to 250 ° C., preferably 150 to 220.
Water or alcohol produced as a by-product and excess aliphatic dihydroxy compound are removed at ℃ to obtain a number average molecular weight of 10,000.
Hereafter, preferably not more than 5000 polyester oligomers are produced. Here, when the molecular weight of the oligomer is high, the ratio of carbonate bonds in the polymer is remarkably low, but the carbonate bonds can easily make the molecular weight of the polyester into a high molecular weight substance as a binder of the polyester oligomer.

The first step is carried out in the presence of an ester exchange catalyst in an amount of 10 ^-4 to 1 part by weight, preferably 10 ^{-4 to} 0.1 part by weight, based on 100 parts by weight of the raw material mixture. The reaction is usually carried out under reduced pressure, and the pressure at which the above reaction is achieved is selected, but it is generally carried out under reduced pressure of 300 mmHg or less.

Next, as a second step, a reaction step of adding a carbonic acid diester to the polyester oligomer obtained in the first step to obtain a high molecular weight polymer, and the temperature is 150 to 250.
C., preferably 200-220.degree. C., to remove by-product phenols and some aliphatic dihydroxy compounds. In this second step, the higher the reaction temperature, the faster the reaction,
A too high temperature is not preferable since it may cause coloration of the polymer. In the reaction, it is preferable that the degree of pressure reduction is gradually adjusted as necessary to finally reduce the pressure to 3 mmHg or less.

Aliphatic dihydroxy compounds used to obtain the aliphatic polyester carbonates of the present invention include, for example, ethylene glycol, trimethylene glycol,
Examples include tetramethylene glycol, butanediol, pentanediol, propylene glycol, hexamethylene glycol, neopentyl glycol and the like.

The aliphatic dicarboxylic acid or its alkyl ester used to obtain the aliphatic polyester carbonate of the present invention includes, for example, succinic acid, malonic acid, glutaric acid, adipic acid, azelaic acid and their alkyl esters. Is exemplified.

These aliphatic dihydroxy compounds and aliphatic dihygyloxy compounds can be used alone or as a mixture and can be combined in a desired manner. However, those having a high melting point are preferable to obtain a suitable molding material. preferable. Therefore, considering price and physical properties, succinic acid and 1,
A combination of 4-butanediols is especially preferred.

The repeating structural units represented by the above general formulas (1) and (2) constituting the aliphatic polyester carbonate of the present invention can have a desired constitution, but the ratio of the constitutional unit (1) is not limited. When the amount is large, the flexibility of the obtained aliphatic polyester carbonate increases, but the melting point decreases. Therefore, the ratio of the structural units (1) and (2) is preferably 50/50 to 99/1 in consideration of moldability and the like.

Specific examples of the carbonic acid diester used in the present invention include dimethyl carbonate, diethyl carbonate, diisopropyl carbonate, dibutyl carbonate, diphenyl carbonate, ditolyl carbonate, bis (chlorophenyl) carbonate,
Examples thereof include m-cresyl carbonate.
Of these carbonic acid diesters, diphenyl carbonate is particularly preferable. The amount of carbonic acid diester used is 0.40 to the terminal hydroxyl groups of the aliphatic polyester oligomer.
A 0.6-fold molar amount is used, but more preferably 0.45-
It is 0.55 times the molar amount.

The aliphatic polyester carbonate obtained in the present invention has a high number average molecular weight of 15,000 or more, and a number average molecular weight of 15,000 or less is not preferable because it does not show sufficient strength as a molded article.

Further, the transesterification catalyst used in the present invention is selected from catalysts which easily give a high molecular weight compound within a desired reaction time, and examples thereof include alkali metal compounds, alkaline earth metal compounds, zinc compounds, Examples thereof include tin compounds, Group IVB compounds such as titanium, zirconium and hafnium. Among these transesterification catalysts, a zirconium compound and a hafnium compound are particularly preferably used in view of the reaction rate and the coloring of the obtained polyester carbonate. Since the catalyst used eventually remains in the produced polymer, excessive use impairs the thermal stability of the polymer, and conversely, too little is disadvantageous because it takes a long time to complete oligomer production and polymerization. . Further, for example, when the polymer according to the present invention is used as a packaging material for food, it is desirable that the amount of catalyst is as small as possible. Therefore, the catalyst amount is usually 100
Relative to the weight part, 10 ^-4 to 1 parts by weight, preferably 10 ^-4
Used in an amount range of up to 0.1 parts by weight.

The aliphatic polyester carbonate of the present invention exhibits high degradability in soil or in the presence of an enzyme, and a mulch film for covering the surface of the soil to keep the soil warm, pots or strings for planting trees, Further, it can be used as a coating material for fertilizers, etc., and can also be used as a fishing line, a fishing net, or as a sanitary material such as medical materials and sanitary products.

[0022]

EXAMPLES Next, the present invention will be described in more detail by way of examples.
To do. In the following examples, the melting point of the copolymer is
The measurement was performed using DSC-220 manufactured by Ko Denshi Co., Ltd. Both
The molecular weight of the polymer is Showa Denko using chloroform as the solvent.
It was measured by GPC System-11 manufactured by Co., Ltd. Carbonate
The bond content is NMR EX-270 manufactured by JEOL Ltd.
Using, ¹³Structural unit (1) and
(2) Dicarboxylic acid ester unit and carbonate unit
The ratio of carbonate units to the total of the ranks (mol%) and
And measured.

Example 1 35.0 g of succinic acid was placed in a 200 mL separable flask equipped with a stirrer, a fractionating condenser, a thermometer, and a gas introduction tube.
(0.30 mol), 5,4-butanediol 53.4 g
(0.60 mol) and zirconium acetylacetonate (4.4 mg) were charged, and the temperature was 150-150 ° C under a nitrogen atmosphere.
The reaction was carried out at 220 ° C for 2 hours to distill off water. Continuing,
Finally, the pressure was reduced to 3 mmHg or less and water and 1,4-
Butanediol was distilled off. The number average molecular weight of the obtained prepolymer was 1,700. The terminal hydroxyl value was 3.2 and the acid value was 0.02.

Then, 11.2 g of diphenyl carbonate was added to 50 g of the obtained prepolymer. Temperature 21
Finally, the pressure was reduced to 1 mmHg at 0 to 220 ° C. and the reaction was carried out for 4 hours. The obtained polymer was a high molecular weight compound having a number average molecular weight of 78,000 as measured by GPC, and ¹³ CNMR
It had 16% of carbonate bonds as a polycarbonate component as measured. ¹³ C NMR spectrum is shown in FIG.
Shown in. Further, the melting point was 101 ° C., and a colorless and tough film was obtained.

Example 2 According to the method of Example 1, a prepolymer having a number average molecular weight of 4,500 was synthesized, and diphenyl carbonate 2.4 was added thereto.
Polyester carbonate was synthesized in the same manner as in Example 1 except that g was used. The obtained polymer was a high molecular weight polyester carbonate containing 4% of a carbonate component and having a number average molecular weight of 85,000 and a melting point of 110 ° C.

Example 3 According to the method of Example 1, a prepolymer having a number average molecular weight of 1500 was synthesized and 13.7 g of diphenyl carbonate was synthesized.
Polyester carbonate was synthesized in the same manner as in Example 1 except that it was used. The obtained polymer was a high molecular weight polyester carbonate containing 21% of a carbonate component and having a number average molecular weight of 93,000 and a melting point of 97.8 ° C.

Example 4 Example 1 was repeated except that ethylene glycol was used in place of 1,4-butanediol to synthesize a prepolymer having a number average molecular weight of 2700, and 5.9 g of diphenyl carbonate was used. Polyester carbonate was synthesized by the same method. The obtained polyester carbonate was a high molecular weight polyester carbonate containing 10% of a carbonate component, having a number average molecular weight of 79,000 and a melting point of 98.8 ° C.

Test Example Using the aliphatic polyester carbonates obtained in Examples 1 and 2 and polycaprolactone CAPA-640 manufactured by INTEROX, a decomposition test by burying in soil was conducted. The soil temperature during the measurement is 5 cm deep
The average temperature was 20 ° C. Each sample was molded into a thickness of 0.3 mm to prepare a test piece having a size of 5 × 5 cm, which was embedded at a depth of 5 cm from the soil surface. After 16 weeks, the aliphatic polyester carbonate sample according to the present invention was observed to undergo changes such as puncture due to decomposition, but there was no significant change in the surface state of polycaprolactone. FIG. 2 shows the change in weight of the sample over time.

[0029]

INDUSTRIAL APPLICABILITY The aliphatic polyester carbonate of the present invention is excellent in properties such as mechanical strength, fluidity and injection moldability, and can be used for packaging materials, molded articles and the like and has a high molecular weight of biodegradability. It is an aliphatic polyester carbonate and is useful as a biodegradable polymer.

[Brief description of drawings]

1 shows a ¹³ C NMR spectrum of the polyester carbonate obtained in Example 1. FIG.

FIG. 2 shows a change with time in weight of a sample by an underground burial test.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Sadanori Isa 22 Wadai, Tsukuba, Ibaraki Mitsubishi Gas Chemical Co., Ltd.

Claims (1)

[Claims] 1. An aliphatic polyester carbonate comprising a repeating structural unit represented by the following formulas (1) and (2) and having a number average molecular weight of 15,000 or more. [Chemical 1] Here, R ¹ and R ² are alkyl groups having 2 to 8 carbon atoms, and these may be the same or different.