JP3480274B2 - Method for producing aliphatic polyester copolymer - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing a high molecular weight aliphatic polyester copolymer which can be molded by a general-purpose plastic molding method such as an injection molding method, a hollow molding method and an extrusion molding method. More specifically, it has excellent physical properties and melt viscosity required for molding, good productivity,
The present invention also relates to a method for producing an aliphatic polyester copolymer having excellent biodegradability.

[0002]

2. Description of the Related Art High molecular weight polyesters having a number average molecular weight of 10,000 or more, which have hitherto been used for molding films, fibers and other molded articles, are PEs made from aromatic polyesters such as terephthalic acid and ethylene glycol.
It was no exaggeration to say that it was limited to T, or PBT made from terephthalic acid and 1,4-butanediol. On the other hand, the reason why the practical application of the aliphatic polyester was extremely difficult is that the melting point of the aliphatic polyester is relatively low, and the number average molecular weight of the aliphatic polyester is 15 in the polycondensation reaction which is generally known. It is difficult to obtain 000 or more, and even if obtained, the number average molecular weight is 1 which is easily decomposed by heat and is generally easy to obtain.
For example, about 10,000 copolymers could not provide sufficient strength for practical use.

Further, in JP-A-4-189822 and JP-A-5-287043, the number average molecular weight is 5,000 or more, preferably 10,000 or more.
By adding a diisocyanate group as a coupling agent to a polyester diol whose terminal group is substantially a hydroxyl group in a molten state above its melting point, a high molecular weight aliphatic polyester containing a urethane bond can be obtained. Is described. However, as far as the inventors of the present invention are aware, when an aliphatic polyester containing a urethane bond is molded by a general-purpose plastic molding method, there are problems such as coloring and generation of microgel depending on conditions.

The inventors of the present invention previously disclosed in Japanese Unexamined Patent Publication No. 8-25968.
In JP-A-0, No. 0,096,989, by copolymerizing an aliphatic diol, an aliphatic dicarboxylic acid or a functional derivative thereof, a bifunctional aliphatic oxycarboxylic acid, and a trifunctional polyhydric alcohol, the melt viscosity is high and the melt viscosity is higher than the number average molecular weight. , A method for producing an aliphatic polyester copolymer having a large weight average molecular weight was proposed, but it was still insufficient in terms of productivity. Also, this aliphatic polyester copolymer had a slow biodegradability.

It is generally known that it is useful to copolymerize a polyfunctional polyol to form a crosslinked structure in order to increase the melt viscosity of the aliphatic polyester copolymer (WO96 / 19521, JP-A-9-77
850). However, even if 1,2,6-hexanetriol, glycerin, trimethylolpropane, etc., which are exemplified in these publications, are used in combination, the polymerization rate is not always sufficiently high.

[0006]

The object of the present invention is to provide a high molecular weight aliphatic polyester copolymer having excellent physical properties, melt viscosity and biodegradability, which is applicable to various fields such as molded articles, films and fibers. It is to provide a method for producing a polymer with high productivity.

[0007]

Means for Solving the Problems As a result of intensive studies for solving the above problems, the present inventor has found that a specific trifunctional polyol is allowed to coexist in a reaction system when an aliphatic polyester copolymer is produced. It was found that, by this, the polymerization rate was significantly increased and an aliphatic polyester copolymer having improved biodegradability was obtained. That is, the gist of the present invention is to produce an aliphatic polyester copolymer by reacting (a) an aliphatic diol, (b) an aliphatic dicarboxylic acid or a derivative thereof, and (c) a bifunctional aliphatic oxycarboxylic acid. A method for producing an aliphatic polyester copolymer having a number average molecular weight of 10,000 to 200,000, which is characterized in that a trifunctional polyol (d) represented by the formula (I) is allowed to coexist in a reaction system.

[0008]

[Chemical 6]

[0009]

DETAILED DESCRIPTION OF THE INVENTION

<(A) Aliphatic diol> The (a) aliphatic diol used in the present invention is an aliphatic compound having two hydroxyl groups, preferably represented by the following formula (III). Is.

HO-R ¹ -OH (III)

(Where R is¹Is a divalent aliphatic hydrocarbon group,
Preferably, the carbon number is 2 to 11, and particularly preferably the carbon number is 2 to 11.
6 is a divalent aliphatic hydrocarbon group. Preferred R¹Is-
(CH ₂)_m-, And m is an integer from 2 to 11, preferably
Or an integer of 2 to 6) The aliphatic diol that can be used in the present invention is particularly limited
However, a specific example is ethylene glycol
1,3-propanediol, 1,4-butanedio
1,5-pentanediol, 1,6-hexanedio
1,4-cyclohexanediol, 1,6-cyclo
Examples include rohexanedimethanol. These alone
They may be used or two or more may be used in combination. The resulting copolymerization
From the viewpoint of physical properties, aliphatic diols are 1,4-butane.
Diol, ethylene glycol or 1,6-hexa
It is especially preferred that it is a diol.

<(B) Aliphatic Dicarboxylic Acid or Derivative Thereof> The aliphatic dicarboxylic acid used in the present invention is not particularly limited as long as it has two carboxylic acid groups in the molecule. The (b) aliphatic dicarboxylic acid is preferably represented by the following formula (IV).

[0012]

Embedded image HOOC-R ² —COOH (IV)

(In the formula, R ² is a direct bond or a divalent aliphatic hydrocarbon group, preferably a divalent aliphatic hydrocarbon group having 2 to 11 carbon atoms, particularly preferably 2 to 6 carbon atoms. .
Preferred R ² is, - (CH _{2) p} - is. However, p
Is 0 or an integer of 1 to 11, preferably 0 or 1 to 6.
A preferable specific example of the aliphatic dicarboxylic acid is oxalic acid, succinic acid, glutaric acid, adipic acid, sebacic acid,
Examples thereof include suberic acid and dodecanedioic acid. As the derivative, an acid anhydride or a lower alkyl ester of an aliphatic carboxylic acid is preferable, and an acid anhydride is preferable. From the physical properties of the resulting copolymer, the component (b) is preferably succinic acid or succinic anhydride. These dicarboxylic acids or derivatives may be used alone or in combination of two or more. <(C) Bifunctional aliphatic oxycarboxylic acid> The bifunctional aliphatic oxycarboxylic acid used in the present invention is not particularly limited as long as it has one hydroxyl group and one carboxylic acid group in the molecule. Although not limited to these, an aliphatic oxycarboxylic acid represented by the following formula (V) is preferable.

[0014]

Embedded image HO—R ³ —COOH (V)

(In the formula, R ³ is a divalent aliphatic hydrocarbon group,
Preferably, it has 1 to 11 carbon atoms, and particularly preferably 1 to 11 carbon atoms.
6 is a divalent aliphatic hydrocarbon group. Of these R ³ , chain-like ones are preferably used. More preferably, a compound having a hydroxyl group and a carboxyl group at one carbon atom, especially a compound of formula (II)

[0016]

[Chemical 10]

(In the formula, n is 0 or an integer of 1 or more, preferably 0 or 1 to 10, more preferably 0 or 1
.About.5). When the (c) bifunctional aliphatic oxycarboxylic acid represented by the formula (II) is used, the polymerization rate is increased. Specific examples of this bifunctional aliphatic oxycarboxylic acid include lactic acid, glycolic acid, 3-hydroxybutyric acid, 4-hydroxybutyric acid, 2-hydroxy-n-butyric acid, 2-hydroxy-3,3-dimethylbutyric acid, 2- Examples thereof include those obtained by ring-opening lactones such as hydroxy-3-methylbutyric acid, 2-methyllactic acid, 2-hydroxycaproic acid, caprolactone, and mixtures thereof. When these have optical isomers, D
It may be a body, an L body, or a racemic body, and may have a solid, liquid, or aqueous solution shape. In particular, lactic acid, glycolic acid and aqueous solutions of these which are easy to obtain and whose increase in polymerization rate during use is particularly remarkable are preferable. 50% for lactic acid and glycolic acid, 70
%, 90% aqueous solution is generally commercially available and easily available. <(D) Trifunctional polyol> In the present invention, the following formula (I) is used.
The trifunctional polyol shown in is used.

[0018]

[Chemical 11]

Even in the case of a trifunctional polyol, when the hydroxymethylhexanediol represented by the formula (I) is used in combination, an aliphatic polyester copolymer having a high polymerization rate and high productivity can be produced. Further, when this hydroxymethylhexanediol is used in combination, the biodegradability, which is a characteristic of the aliphatic polyester, is improved.

<Production Method of Aliphatic Polyester Copolymer> The production of the aliphatic polyester copolymer is usually carried out by esterification and subsequent deglycolization reaction. The esterification reaction may be carried out at a temperature of 120 ° C. to 240 ° C., preferably 150 ° C. to 240 ° C., a reaction time of 1 hour or more, preferably 1 to 10 hours, under an inert dry gas atmosphere, and atmospheric pressure. The subsequent deglycol reaction is performed at a temperature of 150 ° C.
˜240 ° C., preferably 180 ° C. to 240 ° C., reaction time 1 hour or more, preferably 2 to 15 hours, the pressure is gradually reduced from atmospheric pressure, and finally 10 mmHg or less, preferably 2 mmHg or less.

The amount of the aliphatic diol (a) used is substantially equimolar to the amount of the aliphatic dicarboxylic acid or its derivative (b), but it is distilled during the esterification reaction in the actual production process. Therefore, it is usually used in excess of 1 to 20 mol% relative to 100 mol of the aliphatic dicarboxylic acid or its derivative (b).

The amount of the bifunctional aliphatic oxycarboxylic acid (c) used in the present invention is generally 0.04 to 60 per 100 mol of the aliphatic dicarboxylic acid or its derivative (b).
Mol, preferably 1 to 20 mol, more preferably 3 to 1
0 mol. If the amount of the bifunctional aliphatic oxycarboxylic acid is too small, the effect of the present invention is difficult to appear, and if it is too large, the crystallinity tends to be lost, which is not preferable in molding.

The addition timing of the bifunctional aliphatic oxycarboxylic acid (c) is not particularly limited as long as it is before the polyester forming reaction. For example, (1) the raw material in a state where the catalyst is previously dissolved in the aliphatic oxycarboxylic acid solution. A method of adding the catalyst at the time of charging or during the esterification reaction, or (2) a method of simultaneously adding the catalyst at the time of charging the raw materials, and the like are preferable.

The proportion of the trifunctional aliphatic polyol (d) used in the present invention is generally 0.01 to 5 relative to 100 mol of the aliphatic dicarboxylic acid or its derivative (b).
It is a mole. If the addition amount of the trifunctional aliphatic polyol (d) is less than 0.01 mol, the effect of the addition is difficult to appear, and if it exceeds 5 mol, the risk of gelation during the reaction increases. A desirable use ratio is 0.1 to 1.0 mol. The addition timing of the trifunctional aliphatic polyol (d) is not particularly limited as long as it is before the polyester is formed, and it is convenient to add the trifunctional aliphatic polyol (d) at the time of charging the raw materials, but it may be added during the esterification reaction.

The method for producing an aliphatic polyester copolymer according to the present invention is generally carried out by using the above raw materials in the presence of a polymerization catalyst. As the catalyst, any catalyst that can be used for producing a polyester copolymer can be selected, but germanium, titanium, antimony, tin, magnesium,
Examples include metal compounds soluble in the reaction system such as calcium and zinc. Among these, germanium compounds are preferable, and organic germanium compounds such as tetraalkoxy germanium or inorganic germanium compounds such as germanium oxide and germanium chloride are particularly preferable. From the price and availability, germanium oxide,
Tetraethoxy germanium, tetrabutoxy germanium and the like are particularly preferable. The amount of these catalysts used is
It is generally 0.001 to 3% by weight, more preferably 0.005 to 1.5% by weight, based on the amount of monomers used, that is, the total amount of components (a) to (d). The catalyst may be added at any time before the polyester is formed, but may be added at the time of charging the raw materials or at the start of depressurization. It is particularly preferable to add the catalyst simultaneously with the bifunctional aliphatic oxycarboxylic acid at the time of charging the raw materials, or to add the catalyst dissolved in the bifunctional aliphatic oxycarboxylic acid and its aqueous solution.

Conditions such as temperature, time and pressure for producing the aliphatic polyester copolymer are not particularly limited as long as the desired polyester copolymer can be obtained, but the temperature is 150 to 260 ° C. , Preferably 180-2
30 degreeC, superposition | polymerization time is 1 hour or more, Preferably it is 2-15 hours, Decompression degree is 10 mmHg or less, More preferably, it is 2 mm.
It is preferable to select from the range of Hg or less.

<Aliphatic Polyester Copolymer> The aliphatic polyester copolymer produced by the production method of the present invention comprises the component (a) and the component (b) as main polyester constituents. When the raw materials are mixed in the mixing ratio as described above, generally, the molar ratio of (a) the aliphatic diol unit and (b) the aliphatic dicarboxylic acid functional derivative unit becomes substantially equal, and the aliphatic polyester When the number of moles of all the constituent components of the copolymer is 100 mol%, the amount of the (c) bifunctional aliphatic oxycarboxylic acid unit is 0.
It is from 02 to 30 mol%.

These have a structure branched or crosslinked by a part of the trifunctional aliphatic polyol unit. That is, a trifunctional aliphatic polyol unit forms a crosslinked structure and a branched structure. The (d) trifunctional aliphatic polyol unit is usually 0.01 to 100 mol per 100 mol of the component (b).
It is used in a proportion of 5.0 mol, preferably 0.1 to 1.0 mol. In addition, even if the trifunctional component (d) is copolymerized, the polyester copolymer according to the present invention is fusible and belongs to the category of thermoplastic resins.

Further, the present invention is a method for producing an aliphatic polyester copolymer having a relatively large molecular weight, and the number average molecular weight Mn thereof is generally 10,000 or more and 200,000 or less, usually 30,000 or more and 200,000 or less, Is. Further, other copolymer components can be introduced into the aliphatic polyester copolymer produced by the production method of the present invention, as long as the effects of the present invention are not impaired.
Other copolymerizable components include aromatic oxycarboxylic acids such as hydroxybenzoic acid, aromatic diols such as bisphenol A, aromatic dicarboxylic acids such as terephthalic acid and isophthalic acid, or trifunctional or higher functional aromatic polyols and fats. Group polycarboxylic acids, aromatic polycarboxylic acids, tetrafunctional or higher functional oxycarboxylic acids, and the like. These ingredients are
It is 50 mol% or less, particularly 20 mol% or less. Further, in the aliphatic polyester copolymer produced by the production method of the present invention,
In practical use, lubricants, waxes, colorants, fillers, stabilizers and the like can be used in combination, if necessary.

[0030]

EXAMPLES The following examples serve to explain the present invention more specifically. The present invention is not limited to these examples as long as the gist thereof is not exceeded. The number average molecular weight in the examples is measured by the following method. Number average molecular weight (Mn) Gel permeation chromatography (GP
It was measured by the C) method. The sample was dissolved in chloroform and measured by polystyrene conversion using a Tosoh HLC-8020 type GPC device. Column is PLgel
-10 μ-MIX was used.

Example 1 94.5 g of succinic acid and 79.3 of 1,4-butanediol were placed in a polymerization tube equipped with a stirring blade, nitrogen introduction and a pressure reducing port.
g, 90% of 1% by weight of germanium oxide dissolved in advance
A lactic acid aqueous solution (4.8 g) and hydroxymethylhexanediol (0.12 g, 0.1 mol based on 100 mol of succinic acid) were charged, and the mixture was reacted in a nitrogen atmosphere at 180 ° C for 0.5 hours and then up to 220 ° C in 1 hour. The temperature was raised and the pressure was reduced to 0.5 mmHg over 1.5 hours. 0.5 continuously
Polymerization reaction was carried out for 4 hours under reduced pressure of mmHg. The obtained polyester is milky white and has an Mn of 64000.
Met. The melt viscosity at 220 ° C. and a shear rate of 1000 sec ⁻¹ was 1200 poise. When this polymer was hot-pressed at 220 ° C. to form a film having a thickness of 200 μm and embedded in soil, a weight loss of 32% was recognized in 3 months.

Example 2 A reaction was carried out in the same manner as in Example 1 except that 0.36 g of hydroxymethylhexanediol (0.3 mol based on 100 mol of succinic acid) and a polymerization time of 3 hours were used. The obtained polyester was milky white and Mn was 66000. The melt viscosity at 220 ° C. and a shear rate of 1000 sec ⁻¹ was 1300 poise. 22 this polymer
When a film having a thickness of 200 μm was prepared by hot pressing at 0 ° C. and embedded in soil, a weight reduction of 40% was recognized in 3 months.

Comparative Example 1 A reaction was conducted in the same manner as in Example 1 except that 0.32 g of trimethylolpropane (0.3 mol based on 100 mol of succinic acid) was used instead of hydroxymethylhexanediol. The obtained polyester is milky white, M
n was 31000. 220 ° C, shear rate 1000
The melt viscosity at sec ^-1 was 750 poise. When this polymer was hot-pressed at 220 ° C. to form a film having a thickness of 200 μm and embedded in soil, only 5% weight loss was observed in 3 months.

Comparative Example 2 The reaction was performed in the same manner as in Example 1 except that 0.22 g of glycerin (0.3 mol based on 100 mol of succinic acid) was used instead of hydroxymethylhexanediol. The obtained polyester is milky white and has Mn of 29000.
Met. The melt viscosity at 220 ° C. and a shear rate of 1000 sec ⁻¹ was 700 poise. This polymer is 2
When a film having a thickness of 200 μm was prepared by hot pressing at 20 ° C. and embedded in soil, only 5% weight loss was observed in 3 months.

Comparative Example 3 94.5 g of succinic acid and 79.3 of 1,4-butanediol were placed in a polymerization tube equipped with a stirring blade, a nitrogen inlet and a pressure reducing port.
g, 90% of 1% by weight of germanium oxide dissolved in advance
A lactic acid aqueous solution (4.8 g) was charged and reacted at 180 ° C. for 0.5 hours in a nitrogen atmosphere, then heated to 220 ° C. in 1 hour and depressurized to 0.5 mmHg over 1.5 hours.
Subsequently, a polymerization reaction was carried out for 4 hours under a reduced pressure of 0.5 mmHg. The obtained polyester is milky white,
Mn was 27,000. 220 ° C, shear rate 100
The melt viscosity at ⁰ sec ^-1 was 600 poise.
This polymer is hot pressed at 220 ° C. to a thickness of 200 μm.
When the film was prepared and embedded in soil, only 3% weight loss was observed in 3 months.

[0036]

EFFECTS OF THE INVENTION According to the present invention, an aliphatic polyester copolymer having a higher polymerization rate than that in the past, that is, having high productivity and high viscosity can be produced, and further, the obtained aliphatic polyester copolymer is raw. The degradability rate is also fast. Since the aliphatic polyester copolymer obtained by the present invention has a high melt viscosity, it is advantageous for various moldings such as injection molding, blow molding and extrusion molding.

Claims (9)

(57) [Claims] 1. A reaction system for producing an aliphatic polyester copolymer by reacting (a) an aliphatic diol, (b) an aliphatic dicarboxylic acid or a derivative thereof, and (c) a bifunctional aliphatic oxycarboxylic acid. The method for producing an aliphatic polyester copolymer having a number average molecular weight of 10,000 to 200,000, which comprises coexisting with (d) below. (D) Trifunctional polyol represented by the formula (I): 2. An aliphatic diol (a) in the presence of a catalyst,
(B) Aliphatic dicarboxylic acid or derivative thereof, (c) 2
Functional aliphatic oxycarboxylic acid, and (d) trifunctional polyol represented by the formula (I): The method according to claim 1, wherein the reaction is carried out. 3. An aqueous solution of (c) a bifunctional aliphatic oxycarboxylic acid containing a catalyst is represented by (a) an aliphatic diol, (b) an aliphatic dicarboxylic acid or a derivative thereof, and (d) a formula (I). Trifunctional polyol The method of claim 2, wherein the method is added to the mixture of. 4. The method according to claim 2, wherein the catalyst is a germanium compound. 5. The amount of (a) the aliphatic diol is 10 to 100 mol of the (b) aliphatic dicarboxylic acid or its derivative.
0 to 120 moles, (c) 0.04 to 60 moles of bifunctional aliphatic oxycarboxylic acid, (d) trifunctional polyol represented by the formula (I) Is reacted at a ratio of 0.01 to 5.0 mol.
4. The method according to any one of 3 to 3. 6. The (c) bifunctional aliphatic oxycarboxylic acid has the formula (II): (In formula, n shows 0 or an integer greater than or equal to 1), The method of any one of Claims 1-5. 7. The method according to claim 1, wherein (c) the bifunctional aliphatic oxycarboxylic acid is lactic acid or glycolic acid. 8. The (a) aliphatic diol is 1,4-butanediol or ethylene glycol.
7. The method according to any one of 7. 9. The (b) aliphatic dicarboxylic acid or derivative thereof is succinic acid or succinic anhydride.
8. The method according to any one of item 8.