JP2002088145A - Method of manufacturing lactic acid copolyester - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing a lactic acid copolymer in a non-solvent condition, comprising a copolymerizable monomer or a polymer and a lactide in an incompatible mixing ratio in the non-solvent condition, excellent in transparency and elongation under a tension. SOLUTION: This method starts a copolymerization by adding a polymerization catalyst to an aliphatic polyester in a starting ratio capable of forming a homogeneous mixed system and gradually adds the lactide to the reaction system while keeping the homogeneous system.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention has excellent hydrolysis resistance, bleed-out resistance and biodegradability, and is used for blow molding, extrusion molding, injection molding, inflation molding, lamination molding,
The present invention relates to a method for producing a lactic acid-based copolymer polyester, which can be molded by various methods such as press molding and extrusion foam molding.

[0002] The lactic acid-based copolyester of the present invention includes resins for biomaterials, resins for molding, materials for sheets and films,
It is useful as a resin for paints, a resin for inks, an adhesive resin, lamination to paper, a foamed resin material, etc., and is particularly useful as a packaging material because of its excellent transparency.

[0003] Packaging materials include, for example, sheets, trays, cups, dishes, blisters, PTPs, and the like, and films, such as wrap films, food packaging bags, other general packaging bags, garbage bags, shopping bags, and general standards. It is useful for bags such as bags and heavy bags.

[0004]

2. Description of the Related Art It has long been known that polylactic acid can be obtained by a polycondensation method of lactic acid or a ring-opening polymerization of lactide, which is a cyclic monomer, and is mainly used as a suture or a biodegradable molding material. Have been. In the polycondensation method, lactic acid is used as a starting material and a dehydration reaction is allowed to proceed to obtain tens of thousands of polylactic acid. In this reaction, the condensation reaction in the region of several thousands to tens of thousands in which the concentration of the terminal group is reduced is slowed, so that much time is required for increasing the molecular weight. JP-A-06-
As disclosed in Japanese Patent Application Laid-Open No. 065360, there is an example in which 100,000 or more polylactic acid is obtained using a special solvent and a catalyst, but the polymerization time still remains as a major problem.

On the other hand, in ring-opening polymerization of a cyclic monomer of lactic acid called lactide, high molecular weight polylactic acid of 200,000 or more can be obtained. The problem with this polymerization method is that polylactic acid has a very high melt viscosity and is a polymer that is very susceptible to thermal decomposition. JP 5
JP-93050 discloses a continuous production method of polylactic acid using a CSTR system in which agitation type reaction vessels are connected in series. JP-A-8-100057 discloses a manufacturing method combining a static mixer and a CSTR. In these production methods, a problem at the time of withdrawal from the reactor and an efficient removal of residual monomers, which are problems in batch production, have been achieved by continuous polymerization.

Although this polylactic acid has high rigidity, it has a problem of low flexibility and fragility, and various techniques have been developed to improve this point. Among them, a method of copolymerizing a soft polyester or polyether is known.

In JP-A-6-306111, a lactic acid copolymer having an aliphatic polyester block is obtained by performing ring-opening polymerization of lactide in the presence of a high-molecular-weight aliphatic polyester. This copolymer is
It is softened by the introduction of the aliphatic polyester, eliminating the fragility of polylactic acid, and also realizing high transparency. Further, a softened material suitable for processing into a film or a sheet can be provided without substantially impairing the heat resistance of the polylactic acid depending on the amount added and the component.

As a method for producing the lactic acid-based copolymerized polyester, Japanese Patent Application Laid-Open No. 7-026001 discloses a continuous reaction apparatus equipped with a static mixer, in which a bicarboxylic acid ester of hydroxycarboxylic acid, a lactone, a hydroxyl group and / or
Alternatively, a monomer or polymer selected from the group consisting of a polymer having an ester bond is continuously supplied, and continuously reacted at a conversion of 85% or more in the presence or absence of a solvent, and then the remaining monomer is removed by devolatilization. And discloses a method for continuously producing a lactic acid-based copolyester having a weight average molecular weight of 10,000 or more.

In Japanese Patent Application Laid-Open No. Hei 7-233245, lactide and 2 to 50 parts by weight of a polymer having a hydroxyl group are added to a first reactor of a continuous reactor in which three or more stirred reactors are connected in series. Is melted or dissolved in a solvent and supplied continuously, and further transferred sequentially from the first reactor to each of the serially connected reactors, where the first reactor and each of the connected reactors Discloses a method for continuously producing a lactic acid-based copolymerized polyester to be subjected to ring-opening copolymerization.

[0010] However, although the above-mentioned polymerization reaction is suitable for a polylactic acid-based copolymer having a very high viscosity, a lactic acid-based copolymer having a composition ratio in which the comonomer or polymer is not compatible with lactide is used. If so, an appropriate solvent had to be selected and used.

However, since the solvents which can be used for the polymerization reaction of polylactic acid are very limited, depending on the selection of comonomers and copolymers, it is necessary to proceed the copolymerization at a desired copolymerization ratio and under uniform conditions. Was often difficult.

Further, in connection with recent environmental problems, desolvation has been called for, and the use of a solvent not only increases the processing cost, but also the system for recovering and using the residual monomer requires the use of a solvent. Since the combined use decreases the efficiency, it has been desired to produce a lactic acid-based copolymerized polyester without solvent.

As described above, when obtaining a lactic acid-based copolymer having a composition ratio in which the comonomer or polymer is not compatible with lactide, there has been no known method for producing the lactic acid-based copolymer without using any solvent.

DISCLOSURE OF THE INVENTION The present invention relates to a method for producing a lactic acid-based copolymer having excellent transparency and tensile elongation comprising a copolymerizable monomer or polymer and a lactide having a mixing ratio that is incompatible with each other in the absence of a solvent. It is to provide a method of manufacturing with.

[0014]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems. As a result, in the case of many aliphatic polyesters, the concentration range in which the lactide cannot be uniformly mixed is determined when the lactide is excessive. It was found that when the polyester became excessive, most of the polyester could be uniformly mixed with lactide.

Then, the copolymerization of the aliphatic polyester (B) to be copolymerized with the lactide (A) is started at a ratio different from the desired ratio and at a ratio allowing both to be uniformly mixed. It has been found that lactide (A) is added continuously or stepwise so as to have a desired final composition ratio to produce a lactic acid-based copolymer having a desired composition ratio under an unnecessary agent, thereby completing the present invention. Reached. That is,

(1) A lactide (A) and an aliphatic polyester (B) composed of an aliphatic diol (I) and an aliphatic dicarboxylic acid (II) are initially mixed in a composition ratio (A) /
(B) is mixed homogeneously, a polymerization catalyst is added to start copolymerization, and lactide (A) is added stepwise or continuously from the initial composition ratio to the final composition ratio while maintaining uniform mixing. A method for producing a lactic acid-based copolymerized polyester for polymerization,

(2) The initial composition ratio is (A) / (B) = 1
/ 99 to 70/30, the method for producing a lactic acid-based copolymerized polyester according to (1),

(3) The final composition ratio is (A) / (B) = 9
The production method according to (1) or (2), wherein the production method is 7/3 to 50/50.

(4) 100 to 300 parts by weight of lactide (A) is added stepwise or continuously to lactide (A) added at the initial composition ratio from the initial composition ratio to the final composition ratio and copolymerized. (1) The method for producing a lactic acid-based copolymerized polyester according to any one of (1) to (3),

(5) The lactic acid-based polyester according to any one of (1) to (4), wherein the aliphatic diol (I) is an aliphatic diol (I) containing a dimer diol. Production method,

(6) The aliphatic dicarboxylic acid (II) is
(1) The method for producing a lactic acid-based copolymer polyester according to any one of (1) to (5), which is an aliphatic dicarboxylic acid (II) containing dimer acid;

(7) A fatty acid polyester (B) comprising an aliphatic polyester (B) comprising an aliphatic diol (I) and an aliphatic dicarboxylic acid (II) having a high molecular weight by an acid anhydride component or a polyfunctional isocyanate component. B) The method for producing a lactic acid-based copolymerized polyester according to any one of (1) to (6),

(8) The aliphatic polyester (B) comprising the aliphatic diol (I) and the aliphatic dicarboxylic acid (II) is an aliphatic polyester (B) which may contain an aromatic dicarboxylic acid ( 1) The method for producing a lactic acid-based copolyester according to any one of (1) to (7),

(9) The method for producing a lactic acid-based copolymerized polyester according to any one of (1) to (8), wherein the copolymerization is carried out using a stirring type reaction tank and / or a static mixer.

(10) A polymerization catalyst is added at the initial composition ratio (A) / (B), copolymerization is started using a stirring type reaction tank, and lactide (A) is converted from the initial composition ratio to the final composition ratio. (1) The method for producing a lactic acid-based copolymerized polyester according to any one of (1) to (9), wherein the lactic acid-based copolymerized polyester is added stepwise or continuously up to

(11) A polymerization catalyst is added at an initial composition ratio (A) / (B) to form a homogeneous mixture, and copolymerization is started.
(1) The method for producing a lactic acid-based copolymerized polyester according to any one of (1) to (10), wherein the copolymerization is performed while partially circulating the copolymer using a loop-type reaction vessel.

(12) A devolatilization tank is provided, and unreacted monomers of lactide (A) are distilled off in the devolatilization tank and recovered again in a lactide storage tank (1) to (1).
1) A method for producing a lactic acid-based copolymerized polyester according to any one of 1).

[0028]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in order.

First, lactide (A) which is a raw material used in the production method of the present invention will be described. Lactide (A) used in the present invention is a compound in which two molecules of lactic acid are cyclically dimerized by dehydration condensation, and is a monomer having a stereoisomer. That is, examples of the lactide include L-lactide composed of two molecules of L-lactic acid, D-lactide composed of two molecules of D-lactic acid, and meso-lactide composed of D-lactic acid and L-lactic acid.

A copolymer containing only L-lactide or D-lactide crystallizes and has a high melting point. In the lactic acid-based copolyester of the present invention, preferable resin properties can be realized by combining three kinds of lactides in various ratios according to applications. In the present invention, these optical isomer monomers may be used alone or may be composed of a plurality of optical isomer monomers selected from these groups. However, in order to exhibit preferable resin characteristics, it is preferable to use 95 parts by weight or more of L-lactide or D-lactide in the lactide monomer.

Next, the aliphatic polyester (B) which is a raw material used in the production method of the present invention will be described. The aliphatic polyester (B) used in the present invention preferably has a concentration range insoluble in lactide. Lactide,
Since polylactic acid has many oxygen atoms, it tends to be difficult to uniformly mix with the aliphatic polyester (B) having many carbon atoms per unit. Therefore, it is particularly effective when a diol or dicarboxylic acid having a large number of carbon atoms is used.

The aliphatic polyester (B) which can be used in the present invention is a polyester comprising a diol and a dicarboxylic acid, a polyester comprising a hydroxycarboxylic acid, and a copolymer thereof.

The aliphatic diol (I) that can be used in the present invention is a diol having 2 to 45 carbon atoms. Specific examples include ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol,

1,11-undecanediol, 1,12
-Dodecanediol, 1,4-cyclohexanedimethanol, propylene glycol, 1,3-butanediol, 1,2-butanediol, neopentyl glycol, 3,3-diethyl-1,3-propanediol,
3,3-dibutyl-1,3-propanediol, 1,2
-Butanediol, 1,2-pentanediol, 1,3
-Pentanediol, 2,3-pentanediol, 2,
4-pentanediol,

Diols such as 1,4-pentanediol, 1,2-hexanediol, 1,3-hexanediol, 1,4-hexanediol, 1,5-hexanediol, n-butoxyethylene glycol, and dimer acid Dimer diol, diethylene glycol having ether oxygen, dipropylene glycol, triethylene glycol, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, xylylene glycol having an aromatic group, phenylethylene glycol, etc.

The aliphatic dicarboxylic acid (II) which can be used in the present invention is preferably a dicarboxylic acid having 4 to 45 carbon atoms. Specific examples include succinic acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, decanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, dimer acid, hydrogenated dimer acid and the like.

In addition, an aromatic dicarboxylic acid can be used in combination with an aliphatic dicarboxylic acid. For example, phthalic acid, terephthalic acid, isophthalic acid, bisphenol A, biphenol and the like can be used in the present invention. However, the amount of these dicarboxylic acids used is preferably not more than 50 mol% based on the total amount of dicarboxylic acid components. This is because the melting point of the aliphatic polyester (B) is increased, so that the lactide (A)
Polymerization at a temperature unsuitable for copolymerization with
This is because it may become completely insoluble with the lactide (A).

In the present invention, when a structural unit having more than 30 carbon atoms, such as dimer acid or dimer diol, is used, when lactide (A) exceeds the charged amount of aliphatic polyester (B), In many cases, two layers are formed. When polymerizing under such conditions,
Production with good reproducibility becomes difficult depending on the stirring conditions.

The dimer acid or dimer diol which can be used in the present invention is a dicarboxylic acid having 24 or more carbon atoms produced by a thermal dimerization reaction of an unsaturated fatty acid or unsaturated aliphatic alcohol having 12 or more carbon atoms or a reduction thereof. It is a body diol. The starting material of dimer acid is oleic acid or tall oil fatty acid and has low toxicity.

Although various reaction mechanisms have been proposed, the Diels-Alder cyclization reaction by heating is considered to be the main mechanism, and many have an alicyclic structure in the molecule. There are unsaturated double bonds in the molecule and fatty acids saturated by hydrogenation. Many commercially available dimer acids contain a small amount of monomeric acid or trimer acid.

Aliphatic polyester (B) using these
Polyamide and polyamide are known to provide resins and paints having excellent flexibility and coatability. In particular, the application to polyamide hot melt adhesives is great. In the present invention,
Either unsaturated dimer acid or saturated dimer acid may be used. The purity of the dimer acid is desirably 90% or more, preferably 95% or more, and more preferably 99% or more.

The aliphatic polyester (B) used in the present invention
Are preferably those using dimer acid or dimer diol. In particular, aliphatic polyesters (B) using other than these dicarboxylic acids and diols can also be used. The aliphatic polyester (B) in which the content of dimer diol or dimer acid exceeds 50 parts by weight based on the weight of all diols or dicarboxylic acids
However, many have a region insoluble in lactide (A), and in such a case, the present invention is particularly suitable.

However, the present invention is not limited to the aliphatic polyester (B) which is insoluble in the lactide (A) but also to the aliphatic polyester (B) which is soluble in the aliphatic polyester (B) in any concentration range. Applicable.

The aliphatic polyester (B) may be produced from the aliphatic diol (I) and the aliphatic dicarboxylic acid (II) by a conventionally known method. For example, an aliphatic diol and an aliphatic dicarboxylic acid in a molar ratio of 1.2 to 1.2
130: 1 to 220 ° C. in an inert gas atmosphere at 1.5: 1
Water is distilled off by stirring while gradually increasing the temperature at a rate of 5 to 10 ° C. per hour until the temperature is increased.

After reacting for 6 to 12 hours, 0.1 to 10 KPa
While gradually increasing the degree of vacuum, excess diol components are distilled off. After reducing the pressure for 2 to 3 hours, an aliphatic polyester can be obtained by adding a transesterification catalyst and, if necessary, an antioxidant and reacting at 210 to 230 ° C. for 4 to 12 hours while reducing the pressure at 1 KPa or less. .

As the above-mentioned transesterification catalyst, a metal catalyst such as titanium, tin, zinc and zirconium can be used in an amount of 10 to 1000 ppm based on the aliphatic polyester (B). By adding 10 to 1000 ppm of these compounds, it is possible to reduce coloring which becomes a problem during the transesterification reaction.

When the content of dimer acid is small, the molecular weight is 1
It is difficult to obtain an aliphatic polyester (B) of 100,000 or more. Therefore, the aliphatic polyester (B) having a weight-average molecular weight of 40,000 to 50,000 is synthesized by suppressing the reaction temperature to 220 ° C. or lower, The molecular weight of the aromatic polyester (B) can be increased to 100,000 or more.

When the aliphatic polyester (B) is branched to reduce the melt viscosity, the aliphatic polyester (B) can be reacted with a polyfunctional isocyanate or an acid anhydride.

The acid anhydride used in the present invention is a carboxylic acid anhydride having two or more carboxyl groups in one molecule. Specific examples of the carboxylic anhydride include succinic anhydride, cyclohexanedicarboxylic anhydride, phthalic anhydride, maleic anhydride, trimellitic anhydride, pyromellitic dianhydride and mixtures thereof.

The polyfunctional isocyanate referred to in the present invention means one having two or more isocyanate groups.
Particularly, those having only an isocyanate group as the type of the functional group are preferable. For the purpose of obtaining a urethane bond-containing polyester having a substantially linear structure, a bifunctional polyester is preferred.

Specific examples of the bifunctional isocyanate include, for example, hexamethylene diisocyanate, 2,4
-Tolylene diisocyanate, 2,5-tolylene diisocyanate, toluene diisocyanate, xylylene diisocyanate, diphenylmethane diisocyanate,
Examples include 1,5-naphthylene diisocyanate, isophorone diisocyanate, hydrogenated diphenylmethane diisocyanate, or mixtures thereof.

Further, those having three or more polyfunctional isocyanates can be used. In this case, the obtained polymer chains become star-shaped. In order to obtain such a compound, a compound obtained by modifying a polyhydric alcohol with a bifunctional isocyanate, such as a compound obtained by modifying pentaerythritol with a bifunctional isocyanate, may be used.

As the polyfunctional isocyanate used in the present invention, several kinds of polyfunctional isocyanates can be used in combination.
When used in combination with a functional isocyanate, it can be reacted and gelled without gelling.

The reaction of the aliphatic polyester (B) with the carboxylic acid anhydride or di- or triisocyanate is carried out by adding the carboxylic acid to the reaction product immediately after the completion of the polymerization reaction of the aliphatic polyester (B) with the diol and the dicarboxylic acid. A method in which an anhydride or an isocyanate is mixed and reacted by stirring in a molten state for a short time, or a method in which the anhydride or the isocyanate is added again to the aliphatic polyester (B) obtained by polymerization and melt-mixed may be used.

The reaction between the aliphatic polyester (B) and the carboxylic acid anhydride or isocyanate is carried out by adding the carboxylic acid anhydride or the carboxylic acid anhydride immediately after the completion of the polymerization reaction of the aliphatic polyester (B) with the diol and the dicarboxylic acid. A method in which isocyanate is mixed and reacted while stirring in a molten state for a short time, or a method in which the isocyanate is added again to the aliphatic polyester (B) obtained by polymerization and melt-mixed may be used.

The temperature at which the carboxylic anhydride or isocyanate is mixed and reacted with the aliphatic polyester (B) is usually 70 ° C. to 220 ° C., preferably 100 ° C. to 19 ° C.
0 ° C. In the reaction of the polyfunctional isocyanate, it is preferable to use an ester polymerization catalyst such as N, N-dimethylaniline, tin octoate, dibutyltin dilaurate, tetraisopropyl titanate, or a urethane catalyst.

The above-mentioned carboxylic anhydrides and polyfunctional isocyanates can be used as a mixture, if necessary. The amount of these used is preferably 0.01% by weight to 5% by weight of the aliphatic polyester (B), more preferably 0.1% by weight to 1% by weight.

Next, a method for producing the lactic acid-based copolymerized polyester of the present invention will be described.

In the present invention, “homogeneous mixing” means that when the aliphatic polyester (B) is mixed with the lactide (A) at a temperature of 100 ° C. or more, which is the melting point of the lactide, the lactide (A) is converted to the aliphatic polyester. (B) means that it is dissolved and does not separate into two solution phases. That is, even if the stirring is stopped, the transparent state is maintained and the lactide (A) and the aliphatic polyester (B) do not separate into two layers or become cloudy.

When two solution phases are separated without uniform mixing, that is, when a ring-opening polymerization catalyst is added in a heterogeneous mixing state, the catalyst reacts with the polyester terminal to cause block copolymerization, and in addition to lactide (A) A homopolymer cannot be obtained due to the homopolymerization of As a result, the transparency of the polymer is greatly reduced, which is not preferable.

Therefore, in the present invention, as the first step, 10
Aliphatic polyester (B) in a molten state at 0 to 200 ° C
As the initial composition ratio, the weight ratio of lactide (A) / aliphatic polyester (B) is 1/99 to 70/30, preferably 10/90 to 50/50, particularly preferably 20/50.
The lactide (A) is mixed and uniformly mixed so as to be 80 to 50/50 to obtain a uniformly mixed solution.

However, when the lactide (A) and the aliphatic polyester (B) are not uniformly mixed at the desired initial composition ratio and become non-uniform, the amount of the lactide (A) to be added is appropriately reduced, and the excess amount of the lactide (A) is reduced. By mixing under the condition that the amount of lactide (A) added is smaller than the initial composition ratio, uniform mixing can be achieved from such a non-uniform mixing state. This optimum initial composition ratio depends on the type of polyester, and particularly when the aliphatic polyester has a large number of carbon atoms, it is preferable to reduce the amount of lactide (A).

In the second step, the homogeneously mixed solution obtained in the first step is added to the homogeneously mixed solution in a state of 110 to 200 while maintaining the homogeneously mixed state.
The polymerization is started at a temperature of 160 ° C., preferably 160 to 180 ° C. by adding a polymerization catalyst, and the reaction is carried out for 0.5 to 3 hours. Subsequently, as a third step, while maintaining a uniform mixing state, lactide (A) is further added stepwise or continuously from the initial composition ratio to the final composition ratio, and copolymerization is performed for 1 to 4 hours. The lactic acid-based copolyester of the present invention can be produced without a solvent.

The final composition ratio is 97/3 to 30/70, preferably 90/10 to 50/50. As a result, the lactide (A) / aliphatic polyester (B) composition ratio becomes 97
/ 3 to 30/70 lactic acid-based copolymerized polyester can be obtained. As described above, it is possible to produce a lactic acid-based copolymer polyester having a wide range of composition from a large lactide component to a small lactide component.

The amount of lactide (A) to be added stepwise or continuously from the initial composition ratio to the final composition ratio is 100 to 300 weight per lactide (A) added at the initial composition ratio. Parts by weight, more preferably 100 to 200 parts by weight. If it exceeds 300 parts by weight, the amount of lactide (A) added is too large, and the mixture becomes non-uniform again.

When the lactide (A) is added stepwise, the addition is carried out in two or more portions. In this case, it is preferable to add 15 minutes to 1 hour between the additions. The reason is that it is better to allow enough time for the polyester to be blocked by adding lactide (A) added later.
This is because the mixing becomes easier.

The lactic acid-based copolymerized polyester produced by the production method of the present invention was found to have a polymerization conversion of 2% by gel permeation chromatography (GPC).
160-180 ° C in the process, 9
When the lactide (A) is added and stirred as the third step, the viscosity increases again while the molten polymer is dissolved in the lactide (A), and the total polymerization time is about 3 to 4 hours. Thus, the residual monomer can be reduced to 5% or less.

Examples of the polymerization catalyst include tin octoate, titanium tetraisopropoxide, titanium bisacetylacetonate and the like, and may be added in an amount of 50 to 2000 ppm based on the lactide (A) and the aliphatic polyester (B).

The ring-opening polymerization of lactide (A) is at most 200 ° C., preferably at most 180 ° C., in order to prevent coloring and decomposition.
The following reaction temperature is preferable, and the reaction is preferably performed in an atmosphere of an inert gas such as nitrogen and argon in order to prevent decomposition and coloring of lactide (A). Further, since the presence of water in the reaction system is not preferable, the aliphatic polyester (B) to be used must be sufficiently dried.

In the present invention, the storage stability can be further improved by performing a deactivation treatment of the polymerization catalyst after the polymerization. The deactivation treatment of the polymerization catalyst includes not only deactivation of the polymerization catalyst with a chelating agent or acidic phosphates, but also removal of the polymerization catalyst in the resin.

By adding a chelating agent and / or an acidic phosphoric acid ester after or after the production of the lactic acid-based copolymerized polyester, the polymerization catalyst used for producing the lactic acid-based copolymerized polyester can be deactivated.

If the polymerization catalyst used for the production of the lactic acid-based copolymerized polyester remains in the lactic acid-based copolymerized polyester, the thermal stability is poor. The lactic acid structural units in the polyester are regenerated in the form of lactide, and the strength and storage stability of the produced film are reduced. Add catalyst deactivator,
These points are significantly improved by removing the polymerization catalyst. The catalyst deactivator usually adheres to the polymerization catalyst in the lactic acid-based copolymerized polyester in a chelate-like form and is contained in the lactic acid-based copolymerized polyester, but may be further removed.

The amount of the chelating agent and / or acidic phosphate ester used in the present invention varies depending on the type of the catalyst used in the production of the lactic acid-based copolymerized polyester and the reaction conditions. Any amount may be used as long as it is inactivated, and it is usually 0.001 to 5 parts by weight, preferably 0.1 part by weight, based on 1 part by weight of the used catalyst, before taking out the polymer after the lactic acid-based copolymerized polyester polymerization reaction or at the time of kneading. ~ 1
Add 00 parts by weight. These chelating agents and / or acidic phosphates may be added and kneaded to the produced lactic acid-based copolymerized polyester.

The chelating agent component used in the present invention is not particularly limited, but specific examples thereof include ethylenediaminetetraacetic acid, disodium ethylenediaminetetraacetate, oxalic acid, phosphoric acid, pyrophosphoric acid, alizarin, acetylacetone, and diethylenetriaminepentaacetic acid. Triethylenetetramine hexaacetic acid, catechol, 4-t-butylcatechol, L (+)-tartaric acid, DL-tartaric acid, glycine, chromotropic acid, benzoylacetone, citric acid, gallic acid, dimercaptopropanol, triethanolamine, Examples include cyclohexanediaminetetraacetic acid, ditoluoyltartaric acid, and dibenzoyltartaric acid.

The acidic phosphoric acid ester used in the present invention forms a complex with the metal ion of the catalyst contained in the hydroxycarboxylic acid-based polyester, loses the catalytic activity, and has the effect of suppressing the cleavage of the polymer chain. Is shown. The acidic phosphates refer to acidic phosphates, phosphonates, alkylphosphonic acids, and the like, and mixtures thereof.

The acidic phosphoric esters used in the present invention include acidic phosphoric esters, phosphonic esters, alkylphosphonic acids and the like, and mixtures thereof.
Specifically, examples of acidic phosphate esters include monomethyl phosphate, dimethyl phosphate, monoethyl phosphate, diethyl phosphate, monopropyl phosphate, dipropyl phosphate, monoisopropyl phosphate, diisopropyl phosphate, monobutyl phosphate, Dibutyl phosphate, monopentyl phosphate, dipentyl phosphate, monohexyl phosphate, dihexyl phosphate, monooctyl phosphate, dioctyl phosphate, mono-2-ethylhexyl phosphate, di-2-ethylhexyl phosphate,
Monodecyl phosphate,

Didecyl phosphate, monoisodecyl phosphate,
Diisodecyl phosphate, monoundecyl phosphate, diundecyl phosphate, monododecyl phosphate, didodecyl phosphate,
Monotetradecyl phosphate, ditetradecyl phosphate, monohexadecyl phosphate, dihexadecyl phosphate, monooctadecyl phosphate, dioctadecyl phosphate, monophenyl phosphate, diphenyl phosphate, monobenzyl phosphate, dibenzyl phosphate, etc.

Examples of the phosphonate include monomethyl phosphonate, monoethyl phosphonate, monopropyl phosphonate, monoisopropyl phosphonate, monobutyl phosphonate, monopentyl phosphonate, monohexyl phosphonate, monooctyl phosphonate, monoethylhexyl phosphonate, Monodecyl phosphonate, monoisodecyl phosphonate, monoundecyl phosphonate, monododecyl phosphonate, monotetradecyl phosphonate, monohexadecyl phosphonate, monooctadecyl phosphonate, monophenyl phosphonate, monobenzyl phosphonate, etc.

Examples of the alkylphosphonic acid include monomethylphosphonic acid, dimethylphosphonic acid, monoethylphosphonic acid, diethylphosphonic acid, monopropylphosphonic acid, dipropylphosphonic acid, monoisopropylphosphonic acid, diisopropylphosphonic acid, monobutylphosphonic acid, Dibutylphosphonic acid, monopentylphosphonic acid, dipentylphosphonic acid, monohexylphosphonic acid, dihexylphosphonic acid, isooctylphosphonic acid, dioctylphosphonic acid, monoethylhexylphosphonic acid, diethylhexylphosphonic acid, monodecylphosphonic acid, didecylphosphonic acid ,

Monoisodecylphosphonic acid, diisodecylphosphonic acid, monoundecylphosphonic acid, diundecylphosphonic acid, monododecylphosphonic acid, didodecylphosphonic acid, monotetradecylphosphonic acid, ditetradecylphosphonic acid, monohexadecylphosphonic Acid, dihexadecylphosphonic acid, monooctadecylphosphonic acid, dioctadecylphosphonic acid, etc., monophenylphosphonic acid,
Mention may be made of diphenylphosphonic acid, monobenzylphosphonic acid, dibenzylphosphonic acid and the like, and mixtures thereof. The acidic phosphoric acid ester component is excellent in workability due to good solubility in an organic solvent, excellent in reactivity with a lactic acid-based copolymerized polyester, and excellent in deactivating a polymerization catalyst.

Next, the manufacturing apparatus used in the present invention will be described. In the present invention, the reaction can be carried out using a reaction vessel equipped with a stirrer and / or a static mixer. The reaction tank with a stirrer means a vertical or horizontal reaction tank with a stirrer. In these reaction vessels, it is possible to carry out batch polymerization. In the case of a batch type reaction mode, lactide (A) is used in the same reaction tank at the initial composition ratio.
And the aliphatic polyester (B) are mixed, and the polymerization is started by adding a catalyst. After a predetermined time, the lactide (A) is added to the same reaction tank, and the polymerization is performed while always maintaining a uniform state. Things.

The time until the addition of the lactide (A) is preferably set to a time until the lactide (A) is sufficiently consumed. Depending on the addition amount of the lactide (A) and the polymerization temperature, the time until the addition of the lactide (A) is increased. When the addition amount is smaller than that of the aliphatic polyester (B) and the polymerization temperature is 180 to 200 ° C, 15 minutes to 1 hour is preferable. Further, the addition of lactide (A) in the middle is 2 if the batch type polymerization method is used.
It is also possible to add it one or more times or while dropping continuously.

The production method of the present invention is applicable to continuous polymerization. In continuous polymerization, lactide (A) is supplied to a reaction vessel at a constant rate, and is passed through a reaction vessel with a plurality of stirrers or a static mixer at a constant rate.
A method for continuously obtaining a polymer, which is particularly suitable for mass production. A combination of a plurality of reaction vessels with a stirrer as shown in FIG. 1 is called a CSTR method.

In the present invention, the liquid is fed from the storage tank of lactide (A) and aliphatic polyester (B) to the prepolymerization tank so as to have the initial composition ratio, and after being sufficiently mixed, transferred to the first reaction tank. And then add the catalyst. It is preferable to add lactide (A) in the second and subsequent reaction tanks and carry out polymerization until lactide (A) is sufficiently consumed at a desired mixing ratio.
In the CSTR method, the Weissenberg phenomenon may occur in a region where the viscosity is extremely high in the late stage of the polymerization. It is preferable to use a reaction tank having a reaction tank or a reaction tank called a static mixer.

The static mixer may be used alone or in combination with CTSR. When combined with a CSTR, a combination in which the latter stage of polymerization is performed by a static mixer as shown in FIG. 2 is preferable. When the polymerization is carried out only by a static mixer, it is preferable to form a reaction system as shown in FIG. 3, for example.

In a system using a static mixer, since the solutions having different viscosities are rich in mixing properties, a more stable production can be performed as compared with the system using only the CSTR. In this case, a more efficient reaction can be achieved by setting a loop line that partially returns the solution with a low reaction addition rate to the initial line at the beginning of the reaction. Also in the production using a static mixer, regarding the addition of lactide (A) in the middle, the final composition ratio of the polymer is determined by the setting of the polymer feeding speed and the lactide (A) feeding speed, as in the CSTR method.

In the case of continuous polymerization, it is necessary to supply lactide (A) at a constant rate. In the case of the present invention, however, the polymerization is further carried out at the initial composition ratio, and the obtained prepolymer is fed at a constant rate. It is necessary to add lactide (A) while supplying the lactide (A) to the second reaction tank. In order to satisfy these conditions, it is necessary to use a pump with high quantitativeness as a pump for sending liquid. However, it is preferable to use a gear pump as the liquid sending means used in the latter stage of the polymerization.

Next, an example of the copolymerization method will be specifically described with reference to the drawings.

First, referring to FIG. 1, the overall configuration of a manufacturing apparatus to which the present invention is applied will be described. Reference numeral 1 in the figure denotes a pre-mixing tank in which lactide (A) and aliphatic polyester (B) are uniformly mixed at the above-mentioned initial composition ratio. Subsequently, the pre-mixing tank 1 is completely dissolved in a nitrogen atmosphere. Next, the catalyst is transferred from the premixing tank 1 to the catalyst mixing tank 3 via the pump P1, and the polymerization catalyst is transferred from the catalyst storage tank 2 to the catalyst mixing tank 3 via the pump P2 to be stirred and mixed.

The homogeneous mixed solution stirred and mixed in the catalyst mixing tank 3 is transferred to the prereactor 4 via the pump P3.
Stir and mix at 140-180 ° C. Then, ring-opening polymerization of lactide is started from the polyester terminal, and a copolymer having a composition according to the initial composition ratio is produced. At this time, the solution maintains transparency, and the viscosity increases according to the amount of lactide (A) added.

The residence time in the prereactor 4 depends on the composition ratio of the lactide (A) and the aliphatic polyester (B), but is about 0.5 to 2 hours. Subsequently, the copolymer is transferred to the second mixing tank 6 via the gear pump P4,
Further, lactide (A) is transferred from the lactide storage tank 5 via the pump P5 to the second mixing tank 6 so as to have a final composition ratio. In the second mixing tank 6, the two are stirred and mixed. At this time, it is preferable that the addition of lactide (A) in the pump P5 is continuously supplied at a predetermined transfer speed.

At this time, the final composition ratio is determined by the ratio of the transfer speed of the prepolymer to the supply speed of the lactide (A). Further, the stirring property in the second mixing tank 6 is very important, and it is preferable to select a stirring blade suitable for mixing liquids having different viscosities. For example, a full zone blade manufactured by Kobe Steel Co., Ltd. can handle low to high viscosity and is one of the stirring blades suitable for use in the present invention.

The copolymer and lactide (A) sufficiently stirred and mixed in the second mixing tank 6 are passed through a gear pump P6.
Transferred to the second reaction tank 7, residence time of 1 to 3 hours, 16
The mixture is stirred and mixed at 0 to 220 ° C. and copolymerized. For the second reaction tank 7, it is preferable to select a stirring blade that is compatible with high viscosity and has high stirring and mixing properties. For example, as shown in FIG. 2, it is preferable to use static mixer reaction tanks 15 and 16 as the second reaction tank.

The lactic acid-based copolyester produced in the second reaction tank 7 is transferred to an extruder 8 via a gear pump P7 and extruded from the extruder 8, thereby obtaining the lactic acid-based copolyester of the present invention. Can be.

FIG. 3 shows an example of the overall configuration of a manufacturing apparatus using a static mixer to which the present invention is applied.
Will be described. Reference numeral 18 in the figure denotes that the lactide (A) and the aliphatic polyester (B) are uniformly mixed in the above-mentioned initial composition ratio in the pre-mixing tank, and completely dissolved in the pre-mixing tank 18 under a nitrogen atmosphere. Next, the pump P1
5, the polymerization catalyst is transferred from the catalyst storage tank 19 to the catalyst mixing tank 20 via the pump P16, and is stirred and mixed.

The homogeneous mixed solution stirred and mixed in the catalyst mixing tank 20 is supplied to a static mixer 21 via a pump P17.
Transfer to The reaction solution (hereinafter, may be referred to as a “prepolymer solution”) is further fed to the static mixer 22 and further transferred to the static mixer 25 via the pump P18. At this time, a part of the reaction solution is sent to the static mixer 23 by the pump P19 and returned to the static mixer 22 again, thereby playing a role of maintaining proper polymerization solution viscosity and polymerization conversion.

On the other hand, the pump P
The lactide monomer is introduced into the mixer 25 through the mixer 20, and the copolymerization is further performed while mixing the lactide monomer and the prepolymer solution in the mixer 25. The static mixer 2 is sent to the static mixer 27 and is also supplied from the lactide storage tank 26 through the pump P22.
7. Introduce lactide monomer. The reaction solution is introduced from the static mixer 27 to the static mixers 28 and 29 via the gear pump P22.

The polymer is transferred from the static mixer 29 to the extruder 29 via the gear pump P23, and pelletized while devolatilizing the residual monomer as required. The residence time of each static mixer is preferably 0.5 to 2 hours.

The polymerization conversion of the lactic acid-based copolymerized polyester by the production method of the present invention is preferably 95% or more, but the remaining lactide (A) is reduced to the second reaction tank 7, the static mixer reaction tank 16, or A devolatilization tank may be further provided via a gear pump in the reaction tank in which the copolymerization reaction has been performed at the final composition ratio, such as 27, to perform distillation under reduced pressure. As this devolatilization tank, a twin-screw extruder, a thin-film distillation apparatus, a strand type devolatilization tank, or the like can be used. The devolatilized lactide (A) can be efficiently produced by re-collecting it in the lactide storage layer. It is preferable from the viewpoint of the quality of the polymer to return to the storage layer after performing purification such as distillation.

The viscoelasticity of the lactic acid-based copolymerized polyester at room temperature becomes softer as the number of carbon atoms in the main chain of the diol constituting the aliphatic polyester used for the copolymerization increases. Moreover, it becomes softer as the amount of dicarboxylic acid used in combination with dimer acid increases. Therefore, the viscoelasticity may be appropriately adjusted according to the application.

The lactic acid-based copolyester obtained by the present invention is a resin having a high flexibility and a resin having a tensile elongation at break of 100% or more.

The lactic acid-based copolyester obtained by the present invention is a resin having good transparency, and has a haze of 20% or less in a 250 μm sheet. If the composition ratio of the polyester is 40% or less, a transparent sheet of 10% or less can be obtained.

The lactic acid-based copolyester obtained in the present invention has a glass transition temperature of 45 ° C. or more or a temperature of 140 to 180 ° C.
Can also be synthesized. Furthermore, the synthesis of a copolymer having a glass transition temperature of 50 ° C. or higher also depends on the constituents of the aliphatic polyester (B).

The lactic acid-based copolymerized polyester obtained in the present invention has good biodegradability, and is subject to degradation by hydrolysis, biodegradation, etc., even when discarded in the sea. In seawater, the strength as a resin deteriorates in several months, and it can be decomposed without maintaining its external shape. When compost is used, it is biodegraded in a shorter period of time until the original form is not retained. Further, the lactic acid-based copolymerized polyester obtained in the present invention does not emit toxic gas or toxic substance even when incinerated.

The lactic acid-based copolyester of the present invention can be used for molding resin, sheet / film material, coating resin, ink resin, toner resin, adhesive resin, lamination to paper, foamed resin material, etc. Useful as packaging materials and adhesives. Packaging materials include, for example, trays, cups, plates, blisters and the like as sheets, and films as wrap films, food packaging, other general packaging, garbage bags, shopping bags, general standard bags, heavy bags, and other bags. Useful for

It is also useful as a blow molded product for other uses, for example, shampoo bottles, cosmetic bottles, beverage bottles, oil containers, etc., and as sanitary products, disposable diapers, sanitary products, and medical devices. As artificial kidneys, sutures, etc., and as agricultural materials, germinated sheets, seed strings,
It is useful for agricultural multi-films, coating agents for slow-release pesticides and fertilizers, bird nets, curing sheets, seedling pots and the like.

Further, fishing materials include fishing nets, seaweed cultivation nets, fishing lines, ship bottom paints and the like, and injection molded products include:
Golf tee, cotton swab core, candy stick, brush,
It is useful for toothbrushes, syringes, dishes, cups, combs, razor handles, tape cassettes, disposable spoons and forks, and stationery such as ballpoint pens.

Also, as a lamination product on paper,
Tray, cup, plate, megaphone, etc., binding tape, prepayment card, balloon, pantyhose, hair cap, sponge, cellophane tape, umbrella,
Examples include synthetic feathers, plastic gloves, hair caps, ropes, nonwoven fabrics, tubes, hot melt adhesives, foam trays, foam cushioning materials, cushioning materials, packing materials, and cigarette filters. Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples.

[0109]

Example Reference Example 1 (Synthesis of Aliphatic Polyester A-1) Dimer acid (aliphatic unsaturated carboxylic acid having 18 carbon atoms) was placed in a 500 mL reaction vessel equipped with a stirrer, a rectifier, and a gas inlet tube. Dimer; Cognis Enpol 1061 (DA))
Was charged with 1 molar equivalent and 1.4 molar equivalents of ethylene glycol (EG), and the mixture was heated and stirred under a nitrogen stream while raising the temperature from 150 ° C. to 7 ° C. in one hour. The temperature was raised to 220 ° C. while distilling off generated water, and after 2 hours, titanium tetraisopropoxide was used as a transesterification catalyst at 70 pp
m, and the pressure was reduced to 0.1 KPa, followed by stirring for 6 hours.

As a result, a viscous aliphatic polyester (referred to as A-1) was obtained. The number average molecular weight of this polymer was 23,000 by gel permeation chromatography (hereinafter abbreviated as GPC) in terms of polystyrene, and the weight average molecular weight was 45,000.

Reference Example 2 (Aliphatic polyester A-2)
Synthesis of dimer acid (a dimer of an aliphatic unsaturated carboxylic acid having 18 carbon atoms; Enpol 1061 (DA) manufactured by Cognis) in a 500 mL reaction vessel equipped with a stirrer, a rectifier, and a gas inlet tube.
With 0.6 molar equivalents of cyclohexanedicarboxylic acid (CH
DA) 0.4 molar equivalent, 0.9 molar equivalent of 1,4-butanediol (BG) and 0.5 molar equivalent of dimer diol (reduction of dimer of aliphatic unsaturated dicarboxylic acid having 18 carbon atoms) Body: Cognis dimer diol (DDO))
And heated and stirred in a nitrogen stream while increasing the temperature from 150 ° C. by 7 ° C. in one hour. The temperature was raised to 220 ° C. while distilling off the generated water, and after 2 hours, 70 ppm of titanium tetrabutoxide was added as a transesterification catalyst.
The pressure was reduced to 1 KPa, and the mixture was stirred for 3 hours. Furthermore, pyromellitic dianhydride (PMDA) was added to the theoretical yield at 0.1%.
The mixture was stirred at 210 ° C. under reduced pressure of 0.1 KPa for 3 hours.

As a result, a viscous aliphatic polyester (referred to as A-2) was obtained. As a result of measurement by GPC, this polymer had a number average molecular weight of 40,000 and a weight average molecular weight of 73,000.

Reference Example 3 (Aliphatic polyester A-3)
In a 50 L reaction tank equipped with a stirrer, a rectifier, and a gas introduction tube,
Dimer diol (a dimer of an aliphatic saturated carboxylic acid having 18 carbon atoms; Enpol 1008 manufactured by Cognis, Inc. (EM10
08)) was charged with 0.7 molar equivalents, 0.3 molar equivalents of sebacic acid, and 1.4 molar equivalents of propylene glycol (EG), and the temperature was raised from 150 ° C. in a nitrogen stream at 7 ° C. for 1 hour. While stirring. The temperature was raised to 220 ° C. while distilling off generated water. After 2 hours, 70 ppm of tin octoate was added as a transesterification catalyst, and 0.1 KPa
The mixture was stirred under reduced pressure for 3 hours. To this polymerization solution, 0.1% by weight of hexamethylene diisocyanate (HMDI) of the theoretical yield was added and stirred at 170 ° C.

As a result, a viscous aliphatic polyester (referred to as A-3) was obtained. As a result of measurement by GPC, this polymer had a number average molecular weight of 47,000 and a weight average molecular weight of 110,000. Table 1 shows the results of Reference Examples 1 to 3.

(Example 1) (Synthesis of lactic acid-based copolymerized polyester) The high molecular weight aliphatic polyester (A
-1) 70 g and L-lactide 30 g were put in a separable flask and melted at 180 ° C. When the solution becomes homogeneous, add 300 ppm of tin octoate and add
After stirring for 1.5 hours, a clear and viscous solution was obtained. When 100 g of L-lactide was added to the reaction solution and stirred for 2 hours, the viscosity was further increased while maintaining the transparency. After the completion of the polymerization, 500 ppm of ethylhexanoic acid phosphate was added.

The obtained lactic acid-based copolymerized polyester was G
PC number average molecular weight 72,000, weight average molecular weight 15
It was confirmed to be a 000 monomodal copolymer. The glass transition temperature of this polymer was measured by a differential calorimeter (D
SC). The transparency of the polymer is 250
The sheet having a thickness of μm was good at 1.1%.

(Example 2) (Synthesis of lactic acid-based copolymerized polyester) The high molecular weight aliphatic polyester (A
-1) Put 80 g, 19.4 g of L-lactide and 0.6 g of D-lactide in a separable flask,
Melted. After the solution is homogeneous, tin octoate 3
After adding 50 ppm and stirring at 180 ° C. for 1.5 hours, a clear and viscous solution was obtained. To this reaction solution, 116.4 g of L-lactide and 3.30 g of D-lactide were added.
When 6 g was added and the mixture was further stirred for 2 hours, the viscosity was further increased while maintaining the transparency. Furthermore, L-lactide 9
When 7 g and 3 g of D-lactide were added and stirred for 2 hours, the viscosity further increased. After the completion of the polymerization, 500 ppm of ethylhexanoic acid phosphate was added.

The resulting lactic acid-based copolymerized polyester was
Number average molecular weight 95,000, weight average molecular weight 21 by PC
It was confirmed to be a 000 monomodal copolymer. The glass transition temperature of this polymer was measured by a differential calorimeter (D
SC). The transparency of the polymer is 250
The sheet having a thickness of μm was good at 0.7%.

(Example 3) (Synthesis of lactic acid-based copolymerized polyester) The high molecular weight aliphatic polyester (A
-1) 90 g, 9.5 g of L-lactide and 0.5 g of D-lactide were put in a separable flask and melted at 180 ° C. After the solution is homogeneous, tin octoate 40
When 0 ppm was added and the mixture was stirred at 180 ° C. for 1.5 hours, the mixture was transparent and slightly increased in viscosity. In this reaction solution,
When 95 g of L-lactide and 5 g of D-lactide were added and stirred for 2 hours, the viscosity was further increased while maintaining the transparency. Further, 237.5 g of L-lactide, D
Addition of 12.5 g of lactide and stirring for a further 2 hours further increased the viscosity. After the completion of the polymerization, 500 ppm of ethylhexanoic acid phosphate was added.

The obtained lactic acid-based copolymerized polyester was G
Number average molecular weight 110,000 by PC, weight average molecular weight 2
It was confirmed to be 50,000 monomodal copolymer. The glass transition temperature of this polymer was measured by a differential calorimeter (D
SC) was 58 ° C. The transparency of the polymer is 250
The sheet having a thickness of μm was good at 0.5%.

Table 2 shows the results of Examples 1 to 3.

(Example 4) (Continuous polymerization of lactic acid-based copolymerized polyester using a static mixer) The high-molecular-weight aliphatic polyester (A
-2) 500 g and 500 g of L-lactide were put into a 2 L reaction vessel with a discharge port, and were melted at 180 ° C. After the solution became homogeneous, 50 g / h was introduced into a 100 mL catalyst mixed layer using a plunger pump, and tin octoate was continuously introduced to a concentration of 300 ppm. Further, the mixture was introduced from the catalyst mixed layer through a plunger pump into a connected static mixer. The total holding capacity of the static mixer is 250
g, a loop line branched from the first holding capacity of 25 g and partially returned to the head of the mixer.
Further, 25 g of lactide per hour is introduced into the locations of 50 g and 100 g of the holding capacity. When continuous polymerization was performed in this continuous reactor while adding lactide, a highly viscous polymer was obtained from the end point of the static mixer.

The obtained lactic acid-based copolymerized polyester was G
Number average molecular weight 79,000 by PC, weight average molecular weight 20
It was confirmed to be a 000 monomodal copolymer. The glass transition temperature of this polymer was measured by a differential calorimeter (D
SC). The transparency of the polymer is 250
The sheet having a thickness of μm was good at 0.9%.

(Example 5) (Continuous polymerization of lactic acid-based copolymerized polyester of the static mixer type) The high-molecular-weight aliphatic polyester (A
-2) 500 g and 500 g of L-lactide were put into a 2 L reaction vessel with a discharge port, and were melted at 180 ° C. After the solution became homogeneous, 50 g / h was introduced into a 100 mL catalyst mixed layer using a plunger pump, and tin octoate was continuously introduced to a concentration of 300 ppm. Further, 50 g / h of the continuous reaction apparatus used in Example 4 was applied to the 50 g and 100 g holding volumes, respectively.
g and 100 g of lactide were introduced to carry out continuous polymerization. As a result, a highly viscous polymer was obtained from the end point of the static mixer.

The obtained lactic acid-based copolymerized polyester was G
Number average molecular weight 95,000, weight average molecular weight 24
It was confirmed to be a 000 monomodal copolymer. The glass transition temperature of this polymer was measured by a differential calorimeter (D
SC). The transparency of the polymer is 250
The sheet having a thickness of μm was good at 0.5%.

(Example 6) (Two-step continuous polymerization of CSTR-type lactic acid-based copolymerized polyester) The high-molecular-weight aliphatic polyester (A
-3) 60 kg, L-lactide 39.6 kg, D-
Lactide 0.4 kg is charged into a 200 L reaction tank, and 120
Melted at ° C. After the solution became homogeneous, the solution was fed to the 10 L catalyst mixing tank at a rate of 5 kg / hour by a plunger pump. The tin octanoate was continuously added to the catalyst mixed layer at a concentration of 400 ppm, and the mixed solution was added at a rate of 180 kg / h at 5 kg / hour.
The solution was sent to a 10 L prereactor at ℃. Here, after having been retained for 1 hour, it is transferred to a 20 L lactide (A) mixing tank,
A lactide solution (L / D = 99/1) was introduced into the lactide mixing tank at a transfer rate of 5 kg / hour from the lactide storage tank, and the polymer solution and the lactide (A) solution were mixed. The polymer / lactide solution became homogeneous. Further, 50 L of the solution was poured from the mixing tank at a rate of 5 kg / hour.
Was transferred to a second reaction tank and introduced into an extruder with a residence time of 3 hours to distill off residual monomers, and pelletized.

The obtained lactic acid-based copolymerized polyester was G
Number average molecular weight 110,000 by PC, weight average molecular weight 1
It was confirmed to be a 70,000 monomodal copolymer. The glass transition temperature of this polymer was measured by a differential calorimeter (D
SC) was 58 ° C. The transparency of the polymer is 250
The sheet having a thickness of μm was good at 1.1%.

Table 3 shows the results of Examples 4 to 6.

(Example 7) (Preparation of lactic acid-based copolymerized polyester sheet) The lactic acid-based copolymerized polyester obtained in
The mixture was dried by heating under reduced pressure for 6 hours. 3.3 g of this polymer and a thickness of 250μ penetrating a 10 cm × 10 cm square
m PET sheet with a 100 μm thick PET sheet, while heating and melting at 170 ° C., 200 kg / cm ²
For 1 minute.

Next, the sheet was placed in a water-cooled press for 10 minutes, taken out, and left at room temperature for 24 hours. 1 obtained
When the haze of a sheet having a thickness of 0 cm × 10 cm and a thickness of 250 μm was measured according to JIS-K-7127, the haze of the sheet was 0.5%.

(Example 8) Biodegradability test of lactic acid-based copolyester sheet The lactic acid-based copolyester sheet obtained in each of Examples 1 to 6 was sandwiched between wire meshes and left in an electric composting device maintained at 45 ° C. did. Stirring was performed every few hours so as not to cause an anaerobic environment. Thirty days later, when the sheet was taken out, it was almost ragged and remained in its original form. After 60 days, the sheet disappeared and could not be confirmed.

(Comparative Example 1) (Synthesis of lactic acid-based copolymerized polyester) 30 parts by weight of polyester A-1 synthesized in Reference Example 1, 68.9 parts by weight of L-lactide, and 1.1 parts by weight of D-lactide The part was placed in a separable flask and melted at 170 ° C. The solution remained separated in two layers. To this, 200 ppm of tin octoate was added and reacted at 170 ° C. with high-speed stirring at 200 rpm. The reaction system became cloudy and the viscosity increased.

The obtained lactic acid-based copolymerized polyester was G
PC number average molecular weight 77,000, weight average molecular weight 13
It was confirmed that the copolymer was 7,000. The glass transition temperature of this polymer was 5 as measured by a differential calorimeter (DSC).
9 ° C. The transparency of the polymer was 41.1% for a 250 μm thick sheet, indicating high turbidity. Also,
In the tensile elongation test, the tensile elongation at break was 25%.

[0134]

[Table 1]

[0135]

[Table 2]

[0136]

[Table 3]

[0137]

According to the present invention, there is provided a method for producing a lactic acid-based copolymer having excellent transparency and tensile elongation comprising a copolymerized monomer or polymer and a lactide having a mixing ratio incompatible with each other in the absence of a solvent. Can be provided.

[Brief description of the drawings]

FIG. 1 is a diagram showing an example of an overall configuration diagram of a CSTR type manufacturing apparatus of the present invention.

FIG. 2 is a diagram showing an example of an overall configuration diagram of a manufacturing apparatus including a static mixer reaction tank in the CSTR system of the present invention.

FIG. 3 is a diagram showing an example of an overall configuration diagram of a manufacturing apparatus including a loop type reaction tank according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Pre-mixing tank 2 Catalyst storage tank 3 Catalyst mixing tank 4 Pre-reactor 5 Lactide storage tank 6 Second mixing tank 7 Second reaction tank 8 Extruder 9 Pre-mixing tank 10 Catalyst storage tank 11 Catalyst mixing tank 12 Pre-reactor 13 Lactide storage Tank 14 Second mixing tank 15 Static mixer 16 Static mixer 17 Extruder 18 Pre-mixing tank 19 Catalyst storage tank 20 Catalyst mixing tank 21 Static mixer 22 Static mixer 23 Static mixer 24 Lactide storage tank 25 Static mixer 26 Lactide storage tank 27 Static mixer 28 static mixer 29 static mixer 30 extruder P1 pump P2 pump P3 pump P4 gear pump P5 pump P6 gear pump P7 gear pump P8 pump P9 Pump P10 Pump P11 Gear Pump P12 Pump P13 Gear Pump P14 Gear Pump P15 Pump P16 Pump P17 Pump P18 Pump P19 Pump P20 Pump P21 Pump P22 Gear Pump P23 Gear Pump

 ──────────────────────────────────────────────────続 き Continued on the front page F-term (reference) 4J029 AA05 AB04 AC03 AE01 AE11 AE13 AE18 BA01 BA02 BA03 BA04 BA05 BA07 BA08 BA09 BA10 BB06A BB12A BB13A CA02 CA04 CA06 CB04A CB05A CB06A EH03 JC152 JF181 JFKB KB LA04 LA10 LA12

Claims (12)

[Claims] 1. A lactide (A) and an aliphatic polyester (B) comprising an aliphatic diol (I) and an aliphatic dicarboxylic acid (II) are uniformly mixed at an initial composition ratio (A) / (B). Lactide (A) is added in a stepwise or continuous manner from the initial composition ratio to the final composition ratio while maintaining uniform mixing, and then the copolymerization is started. A method for producing a polymerized polyester. 2. The initial composition ratio is (A) / (B) = 1/99.
The method for producing a lactic acid-based copolymerized polyester according to claim 1, wherein the ratio is from 70 to 30/30. 3. The final composition ratio is (A) / (B) = 97/3.
3. The method according to claim 1, wherein the ratio is from 50 to 50/50. 4. Lactide (A) added at an initial composition ratio
4. A method according to claim 1, wherein 100 to 300 parts by weight of lactide (A) is added stepwise or continuously from the initial composition ratio to the final composition ratio to carry out copolymerization. The method for producing a lactic acid-based copolymerized polyester according to the above item. 5. The method for producing a lactic acid-based copolymerized polyester according to claim 1, wherein the aliphatic diol (I) is an aliphatic diol (I) containing a dimer diol. . 6. The lactic acid-based copolymerized polyester according to claim 1, wherein the aliphatic dicarboxylic acid (II) is a dimer acid-containing aliphatic dicarboxylic acid (II). Manufacturing method. 7. An aliphatic polyester (B) comprising an aliphatic diol (I) and an aliphatic dicarboxylic acid (II),
A fatty acid polyester (B) whose molecular weight is increased by an acid anhydride component or a polyfunctional isocyanate component.
7. The method for producing a lactic acid-based copolymerized polyester according to any one of 6. 8. An aliphatic polyester (B) comprising an aliphatic diol (I) and an aliphatic dicarboxylic acid (II),
The method for producing a lactic acid-based copolymer polyester according to any one of claims 1 to 7, which is an aliphatic polyester (B) that may contain an aromatic dicarboxylic acid. 9. The method according to claim 1, wherein the copolymerization is carried out using a stirring type reaction tank and / or a static mixer.
The method for producing a lactic acid-based copolymerized polyester according to any one of Items 1 to 8. 10. A polymerization catalyst is added at an initial composition ratio (A) / (B), copolymerization is started using a stirring type reaction tank, and lactide (A) is converted from an initial composition ratio to a final composition ratio. It is added stepwise or continuously until all the way, and copolymerization is carried out using a static mixer.
10. The method for producing a lactic acid-based copolymerized polyester according to any one of items 9 to 9. 11. The initial composition ratio (A) /
The copolymerization is started by adding a polymerization catalyst in (B), and the copolymerization is further performed while partially circulating the copolymer using a loop type reaction tank. The method for producing the lactic acid-based copolymerized polyester according to claim 1. 12. A devolatilization tank, wherein unreacted monomer of lactide (A) is distilled off in the devolatilization tank and recovered in a lactide storage tank. The method for producing a lactic acid-based copolymerized polyester according to the above item.