JPH06157703A - Thermoplastic aliphatic polyester and its modified material - Google Patents

Abstract

PURPOSE:To dissolve problems of an aliphatic polyester compound, e.g. strength or film-forming properties without loosing its thermoplasticity by modifying the aliphatic polyester compound having those problems. CONSTITUTION:The problems are dissolved by using an aliphatic polyester copolymer containing a dibasic acid having hydroxyl groups as a constituting component and reacting a diisocyanate compound therewith so as to introduce a small amount of crosslinkings. The hydrophilic properties and the biodegradability are improve by controlling the content of the dibasic acid having hydroxyl groups to 5.1 to 10wt.%.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermoplastic aliphatic polyester, a modified product thereof and a process for producing them.

[0002]

2. Description of the Prior Art Aliphatic polyester compounds are available in 1930
It is said to have been synthesized by Carloss in the 1980s by polycondensation of an aliphatic dibasic acid and diol, which is a polymer compound known from old times. Further, the aliphatic polyester compound may be, for example, Appl. Microbiol. , 16,
It is also known to have biodegradability, as described in 900 (1968). 1975, U.S.S. S. 388
3901 shows that an aliphatic polyester compound containing succinic acid as an acid component, such as polyethylene succinate, is used as a hygienic material for implantation in an animal body and is absorbed into the body.

On the other hand, the aliphatic polyester compound has high crystallinity and is wax-like, and does not have sufficient properties as a film or fiber. For this reason, Albertson et al. Are investigating the improvement of the performance and the biodegradability of the obtained modified product by reacting an aliphatic polyester compound with a polyether compound or the like. J. Macromol. Sci.
-Chem. , A23 (3), 411 (1986),
J. Macromol. Sci. -Chem. , A25
(4), 467 (1988). Further, Tokiwa et al. Introduced a polyamide or an aromatic polyester block into the aliphatic polyester compound to modify the same. J. Appl.
Polym. Sci. 24, 1701 (1979),
J. Polym. Sci. 26, 441 (1981).
Also, Polymer Science Techno
logy 31, 61 (1988) Plenum P
For Less, New York, a polyester of tartaric acid and an aliphatic diol is crosslinked with an aliphatic diisocyanate to cause a drug to be retained in the matrix.
We are considering its sustained release.

[0004]

As described above, the conventional aliphatic polyester modified product contains in the molecule a hardly decomposable moiety such as a polyether moiety, a polyamide moiety, or an aromatic polyester moiety. There is. Therefore, even when these modified products are decomposed by microorganisms, the progress is extremely slow, or even if they progress, the hardly-degradable portion is not decomposed and remains and accumulates. The mechanical strength is improved only by increasing the refractory portion and increasing the melting point, but conversely the biodegradability is lost.

On the other hand, it has been known that polyesters of tartaric acid and aliphatic diol are reacted with a diisocyanate compound to cause cross-linking to retain the drug in the matrix and pay attention to its sustained release property. However, tartaric acid polyester is very hydrophilic and is not suitable for use as a molding plastic. Further, since tartaric acid has a very large number of hydroxyl groups, it does not cause gelation or insolubilization only when a trace amount of diisocyanate compound is used, but in order to maintain advantageous thermoplasticity in terms of moldability, Strict trace control is required. Therefore, the polymer produced
, It is difficult to maintain a constant quality. On the other hand, there is no report on a biodegradable control method of a thermoplastic aliphatic polyester compound.

[0006]

The present inventors have introduced a small amount of a cross-linking bond and a hydrophilic group into an aliphatic polyester compound, which is a material improved in elasticity and strength and is biodegradable. As a result of studies aimed at obtaining a material having high quality, the present invention has been achieved. That is, the present invention provides (1) an aliphatic polyester copolymer composed of an aliphatic dibasic acid, an aliphatic dialkol compound and optionally an aliphatic oxycarboxylic acid, wherein a hydroxyl group is used as a constituent of the acid. Modified aliphatic polyester obtained by reacting a diisocyanate compound with an aliphatic polyester copolymer containing 5.1 to 10% by weight of a dibasic acid having (2) 5.1 to 10% by weight Having 2 hydroxyl groups
Polystyrene obtained by reacting a diisocyanate compound with an aliphatic polyester copolymer containing a basic acid as a constituent and having a number average molecular weight of 5,000 to 30,000 by gel permeation chromatography based on polystyrene. With a weight average molecular weight of 30,000 to 50,000 by gel permeation chromatography
The thermoplastic aliphatic polyester modified product according to claim 1, which is 0. (3) Consists of the aliphatic dibasic acid and the aliphatic dialcohol compound according to claim 1, and / or the aliphatic oxycarboxylic acid. An aliphatic polyester copolymer containing, as an acid component, a dibasic acid having a hydroxyl group in an amount of 5.1 to 10% by weight.

First, the synthesis of an aliphatic polyester compound containing 5.1 to 10% by weight of a dibasic acid containing a hydroxyl group, which is a feature of the present invention, will be described. As the dibasic acid containing an acid component, a dialcohol component, an aliphatic oxyacid and a hydroxyl group, the following can be used. Acid components include succinic acid, adipic acid,
1.6-hexanedicarboxylic acid, 1.12-dodecanedicarboxylic acid, thiodiglycolic acid, maleic acid, fumar
Examples thereof include aliphatic dibasic acids such as acid, lower esters thereof such as methyl and ethyl, acid anhydrides and the like.

As the dialcohol component, ethylene glycol, propylene glycol and 1.4-butanedioyl are used.
, 1.6-hexanediol, 1.10-decanediol, diethylene glycol, dipropylene glycol
And aliphatic diols such as diol and ditetramethylene glycol.

Examples of the aliphatic oxyacids include glycolic acid, lactic acid, 3-hydroxybutyric acid, 4-hydroxybutyric acid, 3-hydroxyvaleric acid, 6-hydroxycaproic acid and the like. These are ester, lactone and the like. You may use it as a derivative.

The above components may be used in the form of polymer such as polyester of dibasic acid and diol, polyester of oxy acid such as poly-3-hydroxybutyric acid and polycaprolactone. It is also possible to use these as a mixture and to prepare a copolymer.

Hydroxyl group-containing 2 which is a feature of the present invention
As the basic acid, the following products are fried. That is, malic acid, 3-hydroxyglutaric acid, 3-hydroxymethylglutaric acid, tartaric acid, 5-hydroxyisophthalic acid, 2-hydroxyterephthalic acid and the like can be fried. Of these, aliphatic hydroxyl group-containing dibasic acids are suitable. These are optically active substances,
It may be an inactive form. It may also be used as a derivative such as an ester. All of these are compounds that have low reactivity of hydroxyl groups and are unlikely to cause crosslinking during the synthesis of polyester copolymers containing them. The amount used is an amount calculated to be 5.1 to 10% by weight in the copolyester. In this polyester synthesis, it is preferable that the total number of moles of the carboxyl group and the alcoholic hydroxyl group be almost equal except for the hydroxyl group of the dibasic acid having a hydroxyl group. In some cases it may be advisable to use an excess of the dialcohol component. If the amount of the hydroxyl group-containing dibasic acid used is in excess of this range, gelation tends to occur, which is not preferable.

The synthesis of this copolyester is carried out as follows. The above-mentioned raw material for synthesizing the polyester compound and the hydroxyl group-containing dibasic acid which is a feature of the present invention are heated and reacted in the presence or absence of a catalyst. At this time, a suitable solvent can be used, but it is not necessary to use it. As the reaction progresses, water or lower alcohol
In the case of the generation of silane, the reaction can be promoted by removing it to the outside of the system by means such as heating, azeotropic dehydration and reduced pressure. The reaction temperature is 30 to 200 ° C, preferably 60 to 20
It is 0 ° C. The reaction time is 1 to 30 hours, preferably 3 to
It is 15 hours, and the optimum time varies depending on the catalyst used. The reaction proceeds almost quantitatively.

As the catalyst used at this time, mineral acids such as hydrochloric acid, sulfuric acid and phosphoric acid, and strong organic acids such as methanesulfonic acid, trifluoromethanesulfonic acid, trifluoroacetic acid and p-toluenesulfonic acid can be used. The amount used is 0.01 to 5% by weight, preferably 0.05 to 1% by weight of the reaction product. As a metal catalyst, Zn, Sn, Ti, S
It is also possible to use a mineral acid salt or organic acid salt such as b or Co. The amount used is 0.001 to 5% by weight, preferably 0.005 to 2% by weight, of the reaction product. A catalyst may not be used, but in that case the reaction rate is slightly reduced.

As a solvent for the reaction, halogenated hydrocarbons such as methylene chloride, chloroform and 1.2-dichloroethane, aromatic hydrocarbons such as benzene, toluene, xylene, ethylbenzene, chlorobenzene and dichlorobenzene, or halogenated aromas. Group hydrocarbons, ketones such as acetone, methyl ethyl ketone and methyl isobutyl ketone, and ethers such as dibutyl ether, diglyme, tetrahydrofuran and dioxane can be used.
The amount used is 0.5 to 10 times the reaction amount, preferably 2 times.
About 8 times is particularly preferable. It is of course possible to carry out without solvent, and it is carried out under melting. At this time, it is preferable to use an apparatus capable of efficiently stirring in a high-viscosity state, and at the end of the reaction, good results are obtained when using an apparatus capable of distilling off low-boiling substances by reducing pressure.

5.1 to 10 thus synthesized
The copolymerized polyester containing a dibasic acid having a hydroxyl group in a weight percentage as a constituent component has a number average molecular weight of 5,000 to 30,000, preferably 7,000 as determined by gel permeation chromatography based on polystyrene.
It is good to adjust to ~ 30,000. For this purpose, it is preferable to control by a gel permeation method or a means such as viscosity measurement. Hereinafter, in this specification, the gel permeation method is abbreviated as the GPC method, and the molecular weight uses the value based on polystyrene based on the GPC method.

When the value of the molecular weight is in this range, the ratio of cross-linking in the target modified product obtained by the reaction with the following diisocyanate compound can be controlled, and a constant quality can be obtained. . It also gives good results in terms of physical properties. However, when the reaction with diisocyanate is not carried out, the weight average molecular weight by GPC method is 30,000.
When adjusted to ˜300,000, a copolyester having good physical properties may be obtained, probably due to cross-linking by an ester bond.

Next, the reaction between the copolymerized polyester compound containing a dibasic acid having a hydroxyl group as a constituent and the diisocyanate compound will be described. The reaction temperature is 20 to 250 ° C, preferably 30 to 150 ° C,
It is carried out for 1 to 30 hours, preferably 2 to 10 hours to obtain the target modified aliphatic polyester compound. The diisocyanate compound used at this time is an aliphatic diisocyanate such as 1.4-diisocyanatobutane, 16-diisocyanatohexane, 1.12-diisocyanatododecane,
Aliphatic diisocyanate such as isophorone diisocyanate
And aromatic diisocyanates such as diphenylmethane diisocyanate and tolylene diisocyanate. The amount used is 10 to 10 of the number of moles calculated based on the number average molecular weight of the copolymerized polyester.
An amount of 300%, preferably 20-200% is used. Alternatively, the hydroxyl value can be measured and based on this, the equivalent can be 0.5 to 200%, preferably 1 to 100%.

When a solvent is used, the same solvent as that used when synthesizing the above-mentioned copolymerized polyester containing a dibasic acid having a hydroxyl group as a constituent can be used, and the same amount can be used. Good.

The reaction was controlled by GPC analysis or viscosity measurement to obtain a weight average molecular weight of 30,000-50.
It is preferably 0000, preferably 50,000 to 300,000. The reaction can be stopped at the end by the addition of alcohol, amine, water and the like. When carrying out this modification reaction, it is advantageous to carry out the synthesis of the aliphatic polyester containing a hydroxyl group in the preceding stage and to carry out the reaction continuously.

After the desired product is obtained, when a solvent is used, the solvent can be distilled off and molded into pellets or flakes from the molten state and taken out. When an acid catalyst is used, it is desirable to neutralize it with a basic substance, remove it as an insoluble substance, or remove it by using an ion exchange resin or the like. Alternatively, it can be poured into a poor solvent to form a powder or granules.

The aliphatic polyester and the modified product thus obtained are soluble in halogenohydrocarbons, aromatic hydrocarbons, ketones and the like, have elasticity, and are thermoplastic. It can be processed into a film, a fiber or the like by casting from a solution, a hot melt extrusion method (inflation) or the like.

[0022]

Embodiments will be described in more detail with reference to embodiments.

Example 1 In a 300 ml four-necked flask, 15.0 g of succinic acid, 7.96 g of adipic acid, and 17.8 of 1.4-butanediol.
4 g, L-tartaric acid 2.5 g, methanesulfonic acid 0.3
g and 80 ml of toluene were charged and heated. About 95 ℃
Since water had distilled off at that point, it was removed using a Stark & Dane trap and reacted for 6 hours. 7.1 ml of water
The distillation boiling point rose to 112 ° C. At this time, the number average molecular weight by GPC method was 12,000. 1- here
0.25 ml of 6-diisocyanatohexane was dissolved in 5 ml of toluene and charged, and the mixture was reacted at 80 ° C. for 4 hours. At this time, the number average molecular weight was 30,000 and the weight average molecular weight was 125,000. After cooling to 60 ° C., 0.3 ml of pyridine was added thereto, and 200 ml of methanol was gradually added to form a precipitate. This was filtered, washed with water, and dried to obtain 32.1 g of a modified thermoplastic aliphatic polyester containing tartaric acid of 6.9% by weight. The melting point was measured by the capillary method and was 74 to 92 ° C.

Example 2 The reaction was carried out in the same manner as in Example 1, but 0.5 g of methanesulfonic acid was used, and the reaction was carried out for 9 hours, without reaction with diisocyanate. The target product was taken out in the same manner, and the number average molecular weight was 27,000 and the weight average molecular weight was 9200.
31.0 g of 0 thermoplastic aliphatic polyester was obtained. The melting point was 71 to 88 ° C.

Example 3 In a 100 ml four-necked flask, 10.4 g of succinic acid,
Charge 1.44-butanediol 9.74 g, poly-3-hydroxybutyric acid 0.77 g, DL-malic acid 1.5 g, methanesulfonic acid 0.05 g, and toluene 45 ml 10
The reaction was carried out at around 0 ° C while removing distilled water. After 12 hours, 3.9 ml of water was distilled out and the boiling point became 112 ° C. At this time, the number average molecular weight was 11,000. 0.3-ml of 1.6-diisocyanatohexane was dissolved in 10 ml of toluene and added thereto, and the mixture was reacted at 90 ° C for 4 hours. The number average molecular weight is 31,000 and the weight average molecular weight is 13.
It became 3000. As in Example 1, pyridine 0.0
5 g and 100 ml of methanol were precipitated, filtered, washed with water and dried to obtain 17.1 g of a modified thermoplastic aliphatic polyester. The melting point was 97-105 ° C.

Measurement of Physical Properties With respect to the aliphatic polyester copolymer and modified product of the present invention obtained in each example, a film was prepared by a melt extrusion method, and physical properties were measured 2 weeks later. Examples Tensile strength Elongation at break Kgf / mm ² % 1 1.8 420 2 1.2 210 210 3 2.1 65

Biodegradability Test A film of about 100 μm was prepared from the copolyester of each example or a modified product thereof by the same method as the physical property test, and embedded in soil to observe the degree of decomposition. It was carried out for 2 months in a greenhouse at about 25 ° C. The results are shown in four stages of ABCD. Example 1 B Example 2 A to B Example 3 B Polycaprolactone * B to C * Molecular weight 40,000 (Daicel KK) A: Many large holes are formed. B: There are many small holes. C: Small holes are sparse. D: Almost no change is observed.

[0028]

EFFECT OF THE INVENTION An aliphatic polyester copolymer excellent in film suitability such as tensile strength and elongation and modified products thereof are obtained.

Claims (3)

[Claims] 1. An aliphatic polyester copolymer composed of an aliphatic dibasic acid, an aliphatic dialcohol compound and optionally an aliphatic oxycarboxylic acid, which has a hydroxyl group as a constituent of the acid. 5.1 to basic acid
A modified thermoplastic aliphatic polyester obtained by reacting an aliphatic polyester copolymer containing 10% by weight with a diisocyanate compound. 2. An aliphatic compound containing 5.1 to 10% by weight of a dibasic acid having a hydroxyl group as a constituent and having a number average molecular weight of 5,000 to 30,000 by gel permeation chromatography based on polystyrene. The weight average molecular weight obtained by reacting a polyester copolymer with a diisocyanate compound by gel permeation chromatography based on polystyrene is 30,000 to 50.
The thermoplastic aliphatic polyester modified product according to claim 1, which is 0000. 3. An aliphatic polyester copolymer composed of an aliphatic dibasic acid, an aliphatic dialcohol compound and optionally an aliphatic oxycarboxylic acid according to claim 1, which is a constituent component of the acid. As an aliphatic polyester copolymer containing 5.1 to 10% by weight of a dibasic acid having a hydroxyl group.