JP3407772B2 - Method for producing high molecular weight lactic acid-based copolyester and molded product thereof - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a lactic acid-based copolymer having a higher molecular weight by reacting a polyfunctional polycarboxylic acid (or an acid anhydride thereof) when producing a lactic acid-based copolymer. And a production method of producing a high-molecular-weight lactic acid-based copolyester having various properties by arbitrarily changing the ratio and kind of the raw material polyester to be contained in the copolymer.

The lactic acid-based copolymer according to the present invention has biodegradability and can be molded by various methods such as extrusion molding, injection molding, blow molding and press molding, and is used as a general-purpose resin. It can be molded using existing existing equipment, and is useful as a molding resin, paint resin, ink resin, adhesive resin, etc., and is particularly useful as a packaging material molding resin.

For example, as a processed product of an extruded sheet,
For trays, cups, lids, blister, etc., as film processed products, for wrap packaging, shrink packaging, stretch packaging, etc., as well as bags such as garbage bags, plastic bags, general standard bags, heavy bags, etc. It can be used advantageously. Other agricultural and fishery materials used for extruded products include agricultural mulch film, agricultural chemical sustained-release sheets, bird-prevention nets, curing sheets, seedling pots, fishing nets, seaweed cultivation nets, fishing lines, and sanitary diapers. Sanitary ware, artificial kidney for medical use,
Examples include sutures. Examples of blow-molded products include shampoo bottles, cosmetic bottles, beverage bottles, oil containers and the like. As a laminate with paper, it is used for trays, one-way containers such as cups, and megaphones.

Injection-molded products include golf tees,
It can be applied to cotton swab cores, candy sticks, brushes, toothbrushes, syringes, lids, plates, cups, combs, razor handles, tape cassettes, disposable spoons / forks, stationery such as ballpoint pens. Others, binding tape, prepaid card, balloons, pantyhose, hair cap, sponge, cellophane tape, umbrella, duck, plastic gloves,
Examples include various applications such as hair caps, ropes, tubes, foam trays, foam cushioning materials, cushioning materials, packing materials, hot melt adhesives, cigarette filters, and ship bottom paints.

[0005]

2. Description of the Related Art In recent years, due to environmental problems and the like, much research has been conducted to widely utilize lactic acid-based polymers having excellent biodegradability as general-purpose polymers, and many studies and patent applications relating to the production method have been made. ing. However, conventional polylactic acid, which is a polymer of lactic acid or lactide, or a copolymer of lactide and other monomers,
It is hard to say that it has sufficient performance in transparency,
Further, polylactic acid has problems that it is too degradable and difficult to use as a general-purpose resin except for special applications, and there is a strong demand for improvement of these polylactic acid-based resins.

International Publication No. 91/02015 describes a copolymer of an aromatic polyester such as polyethylene terephthalate or polybutylene terephthalate and polyglycolide or polylactic acid, and a method for producing the same. .

Further, as a production method, a production method by a reaction from a monomer in which lactide, butylene glycol and dimethyl terephthalate are reacted, and 220 ° C.
Describes a method for producing by transesterification between two polymers of polyglycolide and polybutylene terephthalate under high temperature. However, the examples are limited to transesterification processes between polymers.

Japanese Patent Laid-Open No. 4-504731 discloses that
It describes a method of producing a blended polymer of polylactic acid and polyethylene terephthalate by allowing lactide and polyethylene terephthalate to coexist and polymerize.
A technique for reacting a crystalline aromatic polyester with a lactone is disclosed in JP-B-48-4115 and JP-B-48-
4116, etc. With these methods,
Lactones, particularly ε-caprolactone and γ-valerolactone, are reacted with the crystalline aromatic polyester.

However, in the method described in Japanese Patent Application Laid-Open No. 4-504731, the softening point of polyethylene terephthalate is 220 ° C. or higher, and the decomposition temperature of lactide,
If the temperature is higher than 185 ° C, the obtained copolymer is markedly colored and a high molecular weight product cannot be obtained. See also
In the method of reacting lactones described in JP-B No. 115 and JP-B-48-4116, the copolymer obtained is not transparent and has a flexible property, which is preferable as a molding resin. Absent.

That is, the so-called production method from monomers, which has been reported so far, from a dicarboxylic acid component or an esterified product thereof, a diol component, and a cyclic ester such as lactide cannot achieve a sufficiently high molecular weight. This is generally well known. Further, the production method by the reaction between polymers is not realistic because the decomposition temperature of polylactic acid is much lower than the temperature at which an aromatic polyester such as polyethylene terephthalate or polybutylene terephthalate exhibits fluidity.

Further, due to the crystallinity of the aromatic polyester, the high melting temperature, and the poor compatibility with other compounds, the lactic acid-based copolyester obtained is brittle and inferior in transparency. Further, as a copolymer of lactide and an aliphatic polyester, a method of previously polymerizing ε-caprolactone to obtain a homopolymer and further block copolymerizing the lactide is described in JP-A-63-145661.

However, in the method of block-copolymerizing lactide with poly-ε-caprolactone, the obtained copolymer becomes cloudy and opaque. It is considered that this is because the poly ε-caplacacton block and the polylactic acid block in the copolymer are hard to be compatible with each other, and the aliphatic polyester having the poly ε-caprolactone chain is clouded due to the high crystallinity generally possessed. To be In addition, it has a soft property at room temperature, despite the relatively high glass transition point by differential thermal analysis.

Summarizing these conventional techniques, if they have sufficient strength, heat resistance and heat stability, they lack flexibility and transparency, and if they have sufficient flexibility and transparency, they become strong. However, since it has poor heat resistance and thermal stability, a polymer having sufficiently satisfactory properties for use as a material resin for films and sheets has not yet been obtained.

When lactide, which is a residual monomer, is used as a plasticizer as a plasticizing means, the sublimability of the lactide causes a problem of adhesion and contamination of the device in the manufacturing process due to scattering, and plasticization during storage or use. There is a problem that the plasticizing effect is lost due to the disappearance of lactide, which is an agent, from the polymer, and the contents of the package are contaminated.

Further, even when a general plasticizer is added, it is necessary to add a large amount of plasticizer for plasticizing, so that the problem of bleeding out of the plasticizer is unavoidable, and the plasticizing effect during storage is Problems such as disappearance and contamination of packaging contents have not been solved, and a polymer having sufficiently satisfactory properties has not been obtained as a polymer for packaging materials.

[0016]

Therefore, the problem to be solved by the present invention is that it has a sufficient high molecular weight, heat resistance, and thermal stability, and has a rigidity, flexibility, and transparency depending on the application. It is to provide a method for producing a lactic acid-based copolyester which is volatile.

[0017]

In order to solve such a problem, the present inventors have made earnest studies, and as a result, as a result, lactide and an aliphatic dicarboxylic acid component and / or an aromatic dicarboxylic acid component having various constituent ratios and And / or by reacting a polyfunctional carboxylic acid component having 3 or more functional groups with a polyester composed of a diol component as essential components,

Further, lactide, a polyester composed of an aliphatic dicarboxylic acid component and / or an aromatic dicarboxylic acid component having various constituent ratios and a diol component, and a polyfunctional carboxylic acid having three or more functional groups are reacted as essential components. By suppressing the decomposition into monomers at the time of molding, having a wide range of molding temperature and enabling high molecular weight, it has high strength and thermal stability during molding.

In addition, the polylactic acid that is hard and easily hydrolyzed is copolymerized with a hydrophobic polyester to suppress the hydrolyzability, and the proportion of the aliphatic dicarboxylic acid component and the aromatic dicarboxylic acid component is controlled. Tear strength when processed into a film from a hard resin having a high glass transition point and melting point by arbitrarily changing the ratio of the polyester when copolymerizing with polyester. Being able to produce various lactic acid-based polyesters up to resins with excellent flexibility and high toughness and flexibility that do not easily break,

Further, by using a polyfunctional carboxylic acid having a functionality of 3 or more, it becomes easier to increase the molecular weight, so that the type of copolyester that can be selected and the content ratio thereof can be arbitrarily selected, and thus can be widely used. Sufficient strength that can be used as a resin, having thermal stability at the time of molding, rigidity depending on the application, transparency, having flexibility, it was found that it is possible to produce a degradable high molecular weight lactic acid-based polyester, The present invention has been completed.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION That is, the present invention relates to a lactide (A) and a polyester (B) having hydroxyl groups at both ends.
1) and a polyfunctional carboxylic acid having 3 or more functional groups and / or its acid anhydride (C), (A) / (B1) = 50/50 to 9
At a weight ratio of 8/2, (C) is used in the range of 0.001 to 5% by weight based on the total of (A) and (B1), and these are added in the presence of the ring-opening polymerization catalyst (D). A method for producing a high-molecular-weight lactic acid-based copolyester, which comprises performing ring-copolymerization.

The present invention also comprises a lactide (A) and a polyester (B1) having hydroxyl groups at both ends, (A)
/ (B1) = 50/50 to 98/2 by weight in the presence of the ring-opening polymerization catalyst (D), the ring-opening copolymerization is carried out to produce a polyester. An acid and / or its acid anhydride (C) are used in the range of 0.001 to 5% by weight of (C) with respect to the total of (A) and (B1) to react. This is a method for producing a molecular weight lactic acid-based copolyester.

The present invention also relates to a polyester (B1) having hydroxyl groups at both ends and 0.001 to 5 relative to (B1).
A polyester having a weight average molecular weight of 10,000 to 300,000 and a hydroxyl group at both ends (B2) by reacting with a polyfunctional carboxylic acid having a functionality of 3 or more and / or its acid anhydride (C) used in the range of wt%. ) Is obtained, the lactide (A) is further mixed with (A) / (B2) = 50/50 to 9
A method for producing a high-molecular-weight lactic acid-based copolyester, which comprises subjecting a ring-opening copolymerization catalyst (D) to a ring-opening copolymerization at a weight ratio of 8/2.

The present invention also provides a dicarboxylic acid, a diol, and 0.001% to 5% by weight based on the dicarboxylic acid.
With a trifunctional or higher polyvalent carboxylic acid and / or its acid anhydride (C), a dehydration reaction and / or a deglycol reaction is carried out to obtain a weight average molecular weight of 10,000 to 300,000.
After the polyester (B3) of 0 was obtained, this and the lactide (A) were further mixed with (A) / (B3) = 50/50 to 98 /
A method for producing a high-molecular-weight lactic acid-based copolymerized polyester, which comprises performing ring-opening copolymerization in the presence of a ring-opening polymerization catalyst (D) at a weight ratio of 2.

More specifically, in the production method of the present invention, the polyester (B1) having hydroxyl groups at both ends is
The weight average molecular weight is 10,000 to 200,000, and the trifunctional or higher polyvalent carboxylic acid and / or its acid anhydride (C) is trimellitic acid, trimellitic anhydride,
One or more polyvalent carboxylic acids selected from the group consisting of pyromellitic acid and pyromellitic dianhydride, and / or acid anhydrides thereof.

More specifically, the present invention is directed to the production of a high-molecular-weight lactic acid-based copolyester characterized in that the polyester (B1) having hydroxyl groups at both ends has a weight average molecular weight of 10,000 to 200,000. Is the way.

Further, the present invention is characterized in that the high-molecular-weight lactic acid-based copolyester obtained by the above-mentioned production method has a weight-average molecular weight of 20,000 to 600,000. Is a manufacturing method.

The present invention also provides a method for producing a high-molecular-weight lactic acid-based copolyester as described above, which comprises using a static mixer as a polymerization reaction apparatus.
It includes a production method characterized by using a continuous polymerization apparatus comprising two or more agitated reactors connected in series.

The present invention will be described in detail below. The lactide, the polyester having hydroxyl groups at both ends, and the trifunctional or higher polyvalent carboxylic acid used in the present invention will be described in order.

The lactide used in the present invention contains 2 parts of lactic acid.
It is a compound having a cyclic esterification between molecules and is a monomer having a stereoisomer. That is, there are two L- for lactide.
There are L-lactide composed of lactic acid, D-lactide composed of D-lactic acid, and MESO-lactide composed of L-lactic acid and D-lactic acid.

A copolymer containing only L-lactide or D-lactide is crystallized to obtain a high melting point, but the lactic acid type high molecular weight polyester of the present invention can be used in combination with these three kinds of lactides depending on the use. It is possible to realize favorable resin characteristics.

In the present invention, the lactide preferably contains 75% or more of L-lactide in the total lactide in order to express high thermophysical properties, and in order to express even higher thermophysical properties, the lactide should be L-lactide. Those containing 90% or more of the total lactide are preferable.

Examples of the polyester (B) having hydroxyl groups at both end groups used in the present invention include aromatic polyesters containing an aromatic dicarboxylic acid component and a diol component, and aliphatic polyesters containing an aliphatic dicarboxylic acid component and a diol component. Examples thereof include polyesters and aliphatic / aromatic polyesters composed of an aliphatic dicarboxylic acid component, an aromatic dicarboxylic acid and a diol component.

The aromatic dicarboxylic acid component in the polyester used in the present invention is not particularly limited, but specific examples thereof include phthalic acid, isophthalic acid, terephthalic acid, naphthalenedicarboxylic acid, phthalic anhydride and the like. Other examples include alcohols with phthalic acid, isophthalic acid, terephthalic acid, naphthalenedicarboxylic acid, etc., and esters with diols.

The aliphatic dicarboxylic acid component in the polyester used in the present invention is not particularly limited, but is preferably an aliphatic dicarboxylic acid having 4 to 14 carbon atoms. Specific examples include succinic acid, adipic acid, azelaic acid, sebacic acid, brassic acid, and cyclohexanedicarboxylic acid. In addition to these, dimer acid and the like can be used.

The diol component in the polyester is not particularly limited as long as it is a diol, but among them, a diol having 2 to 10 carbon atoms is preferable, and specifically, ethylene glycol, propylene glycol, butylene glycol, pentane diol. , Hexamethylene glycol, octanediol, neopentyl glycol, cyclohexanedimethanol, xylene glycol, diethylene glycol, triethylene glycol, dipropylene glycol, dibutanediol, 3-hydroxypivalyl pivalate, and hydrogenated bisphenol A. To be

In particular, in order to increase the transparency of the obtained copolymer, it is preferable to contain neopentyl glycol, and it is preferable to contain 20% by weight or more of the diol component. The molar ratio of the dicarboxylic acid component and the diol component is 1
It is preferably before and after.

When the high-molecular-weight lactic acid-based copolyester obtained by the present invention is formed into a sheet, a sheet having high strength to a flexible sheet can be obtained. Specifically, the tensile viscoelasticity is 500 to 50,000 kg / cm ^2.
Sheet is obtained.

Further, in the present invention, an aromatic polyester,
It is also possible to use both polyesters of an aliphatic polyester not containing an aromatic ring as raw materials at the same time. Also in this case, it is preferable that both polyesters have a high molecular weight of 1,000 or more, particularly 10,000 to 2
Those of 0,000 are preferable.

The amount ratio of the aromatic polyester and the aliphatic polyester is not limited, but in order to have sufficient strength, flexibility and transparency in practical use, the total amount of the aromatic polyester and the aliphatic polyester is 100. Parts by weight,
It is preferable that 1 to 49 parts by weight of the aromatic polyester and 1 to 49 parts by weight of the aliphatic polyester are contained.

Regarding the aromatic polyester, aliphatic polyester, and aromatic / aliphatic polyester used in the present invention, the lower one of the melting point and the softening point is 200 ° C.
The following are preferred, and those of 80 to 190 ° C. are particularly preferred. The crystallinity and the non-crystallinity of the aromatic polyester are not limited, but a transparent polyester is more preferable.

Commercially-used polyethylene terephthalate, which is generally used, usually has a softening point of 220 to 255 ° C. and is not suitable for the production method of the present invention, but it has a special low softening point (softening point). 20
(0 ° C. or less), a lactic acid-based copolymer having a high molecular weight and no coloration can be obtained by the method for producing a copolymer of the present invention. The melting point referred to in the present invention is measured by differential scanning calorimetry (DSC).

The lactic acid type high molecular weight polyester of the present invention is
At the time of esterification, a high molecular weight can be obtained by using at least one or more polycarboxylic acid and / or its acid anhydride together. By the effect that branching is further introduced to broaden the molecular weight distribution, or the metal reacts with the carboxyl group of one or more functional groups of the polycarboxylic acid and / or its acid anhydride to cause the polymer to become an ionomer. As a result, it becomes possible to form films and sheets having excellent physical properties.

Examples of trifunctional or higher polycarboxylic acids and / or their acid anhydrides include trimesic acid, propanetricarboxylic acid, trimellitic acid, trimellitic anhydride, pyromellitic acid, pyromellitic anhydride, and benzophenonetetra. Carboxylic acid anhydride, cyclopentatetracarboxylic acid anhydride, 1,3,5-cyclohexanetricarboxylic acid,
Examples thereof include cyclohexanetetracarboxylic acid and cyclohexanetetracarboxylic acid anhydride. Particularly, trimellitic anhydride and pyromellitic anhydride are preferable. These polyvalent carboxylic acids and / or their acid anhydrides can be mixed and used, if necessary.

The preferred conditions for the polyester having hydroxyl groups at both ends, the polyfunctional carboxylic acid having three or more functional groups and the objective high molecular weight lactic acid-based copolymerized polyester of the present invention are shown below.

Polyester having hydroxyl groups at both ends (B
1) is a polyester having a hydroxyl group at both ends (B) for the purpose of increasing the molecular weight of the resulting lactic acid-based copolymer.
1) is a weight average molecular weight of 10,000 to 200,000
It is preferable that the number average molecular weight is 0 and the number average molecular weight is 5,000 to 100,000.

From the viewpoint of the solubility of the polyester having hydroxyl groups at both ends and the ease of production, the polyester (B1) having hydroxyl groups at both ends has a weight average molecular weight of 2
10,000-100,000, number average molecular weight 10.0
It is more preferably from 00 to 50,000.

The ratio of lactide (A) to polyester (B1) having hydroxyl groups at both ends is 50/50.
It is preferable for it to be 98/2 because the molecular weight of the obtained high molecular weight lactic acid-based copolymer is high. More preferably, (A)
When / (B1) is 65/35 to 98/2, the transparency of the obtained high molecular weight lactic acid-based copolymer is high.

The proportion of the polyfunctional carboxylic acid having 3 or more functional groups and / or its acid anhydride (C) in the production methods of claims 1 and 2 is such that the lactide (A) and the polyester (B1) having a hydroxyl group at both ends. ) 0.001 to 5% by weight is preferable based on 100% by weight of the total of components. More preferably, when it is 0.001 to 0.1% by weight, the molecular weight and flexibility of the obtained high molecular weight lactic acid-based copolymer will be high.

Polyester (B2) having hydroxyl groups at both ends obtained by reacting a polyfunctional carboxylic acid having at least three functional groups and / or its acid anhydride (C) with a polyester (B1) having hydroxyl groups at both ends. Is a weight average molecular weight of 1 for the purpose of increasing the molecular weight of the obtained lactic acid-based copolymer.
It is preferably from 30,000 to 300,000. Further, from the viewpoint of the solubility of the polyester having hydroxyl groups at both ends and the ease of production, the weight average molecular weight is 20,000 to
150,000, 10,000-80 in number average molecular weight,
It is more preferably 000.

The ratio of lactide (A) to polyester (B2) having hydroxyl groups at both ends is 50/5.
When it is from 0 to 98/2, the molecular weight of the obtained high molecular weight lactic acid-based copolyester becomes high. More preferably,
When it is 65/35 to 98/2, the transparency of the obtained high molecular weight lactic acid-based copolymer is high.

The proportion of the polyfunctional carboxylic acid having 3 or more functional groups and / or its acid anhydride (C) in the production method of claim 3 is such that the polyester (B1) having hydroxyl groups at both ends.
0.001 to 5% by weight is preferable with respect to 100% by weight of the component. It is more preferably 0.001 to 1% by weight, and even more preferably 0.001 to 0.1% by weight, so that the high molecular weight lactic acid-based copolymer obtained has high molecular weight and flexibility.

A high molecular weight polyester having hydroxyl groups at both ends, which is obtained by dehydrating and deglycolizing a trifunctional or higher polyvalent carboxylic acid and / or its acid anhydride (C), a dicarboxylic acid and a diol. (B3) is preferably a weight average molecular weight of 10,000 to 300,000 and a number average molecular weight of 10,000 to 100,000 for the purpose of increasing the molecular weight of the resulting lactic acid-based copolymer.

More preferably, the weight average molecular weight is 20,000 to 150,000, and the number average molecular weight is 10,000 to 50,000 from the viewpoint of solubility of the obtained high molecular weight polyester (B3) and easiness of production. Is more preferable.

The ratio of lactide (A) to polyester (B3) having hydroxyl groups at both ends is 50/5.
When it is from 0 to 98/2, the molecular weight of the obtained high molecular weight lactic acid-based copolymer will be high. More preferably, 65/35
When it is ˜98 / 2, the transparency of the obtained high molecular weight lactic acid-based copolymer is high.

In the polyester (B3) having hydroxyl groups at both ends, the proportion of the polyfunctional carboxylic acid having three or more functional groups and / or its acid anhydride (C) is 100% by weight of the dicarboxylic acid or its acid anhydride component. 0.001 to 0.001
5% by weight is preferred. More preferably, if it is 0.01 to 1% by weight, the molecular weight and flexibility of the obtained high molecular weight lactic acid-based copolymer will be high.

The high-molecular-weight lactic acid-based copolyester which is the target product has a weight-average molecular weight of 20,000 to 600,000.
It is preferably 0 and the number average molecular weight is 10,000 to 300,000. In consideration of physical properties such as a decrease in molecular weight during molding, processability during molding, and strength when formed into a molded product, a weight average molecular weight of 50,000-5
0,000, number average molecular weight 30,000 to 250,000
It is more preferably 00.

It is desirable to use the ring-opening polymerization catalyst (D) in the polymerization reaction. As the ring-opening polymerization catalyst (D) used in the present invention, generally, a ring-opening polymerization catalyst (D) of cyclic ester, Tin, zinc, also known as transesterification catalyst,
Examples include metals such as lead, titanium, bismuth, zirconium, and germanium, and their derivatives. Also, these metal derivatives can be used in the catalyst of the present invention, and metal organic compounds, carbonates, oxides and halides are particularly preferable. Specifically, tin octoate, tin chloride, zinc chloride, zinc acetate, lead oxide, lead carbonate, titanium chloride, alkoxy titanium, germanium oxide, and zirconium oxide are suitable.

The amount of ring-opening polymerization catalyst (D) is such that lactide (A) and polyester having hydroxyl groups at both ends ((B1) or (B2) or (B3)) and /
Or 0.005 to 100% by weight of the total of trifunctional or higher polyvalent carboxylic acid and / or its acid anhydride (C).
0.2 wt% is preferred. In order to have a sufficiently high polymerization rate and to reduce the coloring of the obtained lactic acid-based polyester, 0.01 to 0.1% by weight is particularly preferable.

When a polyfunctional carboxylic acid having a functionality of 3 or more and / or its acid anhydride (C) is reacted with a polyester (B1) having hydroxyl groups at both ends, or (C), a dicarboxylic acid and a diol are dehydrated. It is preferable to use a catalyst when the polyester is produced by the deglycolization reaction.

As the catalyst used in the present invention, any catalyst generally known as an esterification catalyst can be used, and examples thereof include tin, zinc, lead, titanium, antimony, cerium, germanium, cobalt, manganese, iron, Examples thereof include organic or inorganic metal compounds of at least one metal such as aluminum, magnesium, calcium and strontium. For example, metal alkoxides, organic acid salts, chelates, oxides and the like are used, and in particular, titanium organic compounds such as alkyl titanate, titanium oxyacetylacetonate and titanium oxalate are useful.

The catalyst is used in an amount of 100% by weight based on the total amount of trifunctional or higher polyvalent carboxylic acid and / or its acid anhydride (C), dicarboxylic acid or its acid anhydride and diol.
Is preferably 0.001 to 0.5% by weight. The polymerization rate is sufficiently high, and in order to reduce the coloration of the obtained lactic acid-based polyester, 0.01 to 0.1% by weight is particularly preferable.
Is preferred.

Next, a specific manufacturing method will be described in order.
First, lactide (A) and polyester ((B
When 1), (B2), or (B3)) is used as an essential component for polymerization, the polymerization temperature is preferably above the melting point of lactide and below 185 ° C. in view of the equilibrium of the polymerization, and is accompanied by the decomposition reaction. Coloring of the lactic acid-based polyester can be prevented. The melting point of lactide is around 100 ° C., and a temperature of 100 ° C. or higher and 185 ° C. or lower, more preferably 145 to 180 ° C. is desirable in terms of polymerization equilibrium, and to prevent a decrease in the molecular weight and coloration of the lactic acid-based polyester due to the decomposition reaction. You can

When the lactide (A), the polyester (B1) having hydroxyl groups at both ends and the polyfunctional carboxylic acid having a functionality of 3 or more and / or its acid anhydride (C) are mixed at once, the polymerization is carried out. , The mixture is heated and melted or mixed with a solvent, and then the ring-opening polymerization catalyst (D) is added.

In the case of this method, the lactide, the polyester having a hydroxyl group at the terminal, the polyfunctional carboxylic acid having three or more functional groups and the acid anhydride thereof can be polymerized / reacted at one time, and a rapid reaction can be carried out. It is most preferable from the viewpoint of.

The lactide (A) and the polyester (B1) having hydroxyl groups at both ends are subjected to ring-opening copolymerization in the presence of the ring-opening polymerization catalyst (D) to give a weight average molecular weight of 10,000.
In the case of producing a high-molecular-weight lactic acid-based copolyester of 0 to 300,000 and further reacting this with a polyfunctional carboxylic acid having a functionality of 3 or more and / or its acid anhydride,
After the mixture of (A) and (B1) is heated and melted or mixed with a solvent, the ring-opening polymerization catalyst (D) is added.

The reaction with the trifunctional or higher polyvalent carboxylic acid and / or its acid anhydride (C) is carried out at a temperature of 100 ° C. to 210 ° C. for 10 to 10 ° C. when the polymerization is carried out without a solvent after the completion of the polymerization.
React under stirring for 180 minutes. At this time, it is preferable to carry out the reaction under reduced pressure because the reaction rate becomes faster. When the polymerization is carried out with a solvent, the temperature of 80 to 210 ° C.
It is preferable to carry out the reaction for 180 minutes. At this time, a catalyst may be added if necessary.

This method is different from the case of reacting a polycondensate polyester of a hydroxycarboxylic acid such as polylactic acid with a polyvalent carboxylic acid and / or its acid anhydride. Both end groups of the polyester that reacts with the acid and / or its acid anhydride are hydroxyl groups, and the number of reactive end groups increases. Therefore, it is possible to connect all the polymer chains, which is particularly preferable.

When a polyfunctional carboxylic acid having a functionality of 3 or more and / or its acid anhydride (C) is reacted with a polyester (B1) having hydroxyl groups at both ends and then copolymerized with lactide (A), Polyester having a hydroxyl group at the end (B
After the production of 1) is finished, a polyfunctional carboxylic acid having a functionality of 3 or more and / or its acid anhydride (C) is melted by heating or mixed with a solvent, and if necessary, a catalyst is added and reacted.

In the case of using no solvent, the reaction is carried out at a temperature of 100 to 210 ° C. for 10 to 180 minutes with stirring. At this time, it is preferable to carry out the reaction under reduced pressure because the reaction rate becomes faster. 10 to 180 at a temperature of 80 to 210 ° C. where polymerization is performed with a solvent
It is preferable to carry out the reaction for minutes. After that, when the lactide (A) is mixed with a polyester (B2) having hydroxyl groups at both ends, which is obtained by reacting a polyfunctional carboxylic acid having a functionality of 3 or more and / or its acid anhydride (C), the mixture is mixed. Are melted by heating or mixed with a solvent, and then the ring-opening polymerization catalyst (D) is added.

In the case of this method, a transesterification reaction occurs when a lactide and a polyester having hydroxyl groups at both ends which are reacted with a polyfunctional carboxylic acid having three or more functional groups and / or an acid anhydride thereof are polymerized to give a homogeneous copolymerization. A coalescence is obtained.

When a trifunctional or higher polyvalent carboxylic acid and / or its acid anhydride (C) is dehydrated and deglycolized with a dicarboxylic acid and a diol and then copolymerized with lactide (A), The dehydration reaction of the trifunctional or higher polyvalent carboxylic acid and / or its acid anhydride (C), dicarboxylic acid and diol is preferably carried out at 160 to 250 ° C. for 5 to 16 hours in an inert gas atmosphere.

The deglycolization reaction is preferably carried out at 170 to 260 ° C. for 2 to 16 hours under a reduced pressure of 5 Torr or less. The polyester (B3) having hydroxyl groups at both ends thus obtained and the lactide (A) are heated and melted or mixed with a solvent, and then the ring-opening polymerization catalyst (D) is added.

The high-molecular-weight lactic acid-type copolyester obtained by these production methods has a weight average molecular weight of 20,000 to 600 in order to maintain the ease of molding at the time of molding and the strength or flexibility of the molded product. It is preferably 1,000. Further, considering the decrease in the molecular weight during molding, the weight average molecular weight is more preferably 50,000 to 600,000.

In order to prevent decomposition and coloration of lactide, an atmosphere suitable for polymerization and reaction with a trifunctional or higher functional polycarboxylic acid and / or its acid anhydride (C) is preferably a dry inert gas. Particularly, it is performed in a nitrogen or argon gas atmosphere or in a bubbling state. At the same time, a polyester ((B1) or (B1) having hydroxyl groups at both ends as a raw material
2), or (B3)) or a mixture thereof is preferably dehydrated and dried.

Since lactide can be dissolved in a solvent,
It can be polymerized using a solvent or the like. Examples of solvents that can be used are benzene, toluene, ethylbenzene, xylene,
Cyclohexanone, methyl ethyl ketone, isopropyl ether are mentioned.

The high molecular weight lactic acid type polyester of the present invention is
It is possible to manufacture using an ordinary polymerization kettle, but due to the increase in viscosity accompanying the increase in molecular weight, mixing and stirring are hindered in the copolymerization reaction using an ordinary polymerization tank, and partial alteration due to local heating Is likely to occur. Even when the product is withdrawn from the polymerization tank, the product adheres to the vessel wall or the stirring blade, leading to a decrease in yield. Therefore, the yield and the productivity can be improved by the method of continuously manufacturing.

As an example of the continuous production method, the viscosity of the raw material is low like the high molecular weight lactic acid-based polyester of the present invention, the viscosity of the polymer is drastically changed to a high viscosity of more than 10,000 poise, and the viscosity is high. Since it is extremely difficult to control the temperature of a resin that undergoes decomposition, it is preferable to use a stirring type reactor in which two or more tanks are connected in series and the temperature can be efficiently controlled by changing the stirring method as the reaction progresses.

The continuous polymerization method using two or more stirred reactors connected in series means that a plurality of stirred reactors are connected in series and the polymerization reaction proceeds to some extent in the first reactor. Then, the reaction product is transferred to the next reaction tank to further advance the reaction, and if necessary, transferred to other reaction tanks one after another to proceed the reaction. In this method, the raw materials may be mixed into the product in an unreacted state, and it is preferable to increase the number of reaction vessels to solve this problem.

The agitating reactor referred to here is a dynamic mixer having a stirrer, and specifically refers to a reaction vessel equipped with a stirrer having stirring blades connected to a power machine. Regarding the shape of the stirring blade used in the stirring reactor, in the case of continuous reaction using a multi-tank reactor, the reactor used in the initial stage of the reaction has a low viscosity state, and the shape of the blade is not particularly limited. Stirring is performed well even without it, but for the purpose of efficiently generating upstream and downstream in the reactor, turbine blades,
Fedler blades, helical ribbon blades or multistage blades thereof are preferable.

Alternatively, a blade capable of uniformly stirring the entire reaction system, such as an anchor blade, is also preferable. In the reactor used in the middle stage and the latter stage of the reaction, the state of the viscosity is high, and the blade shape greatly affects the stirring. Stirring is particularly difficult near the wall in the reactor, and for the purpose of efficiently scraping the reaction product from the wall, the entire reaction system is uniformly stirred, such as turbine blades, helical ribbon blades, and anchor blades. Wings that can be formed are preferable.

In the case of the method of producing by extracting the same amount of product while continuously supplying the raw material, the larger the total number of reactors, the less the unreacted raw material is mixed in the product. Further, the capacity of the reactor becomes small, the stirring power for each reactor is small, and the temperature control by the heat medium becomes easy. However, as the number of reactors increases, the number of motive power of the device also increases, and the number of pumps connecting the reactors also increases, which complicates the control.

Since it is economically unfavorable that the apparatus becomes complicated, the number of stirring type reactors to be used should be set as small as possible within a range where a sufficient mixing effect can be obtained.
If the capacity of the reaction tank is in excess of the amount of raw material supplied, it is considered sufficient to use two or more reactors, but it is economically important to increase the volume of the reaction tank to the amount of raw material supplied. It is considered unfavorable that the number of reactors should be 3 or more. Further, the number of reactors increases and the apparatus becomes complicated, which is not preferable from the economical point of view in operation, and the number of reactors is preferably 3 to 5 tanks.

An example of a latent heat cooling type stirring reactor is a reactor having the ability to control the reaction temperature by using the heat of evaporation of the raw material monomer or solvent. It is a reactor that has a space in the upper part of the reactor and can be cooled by radiating heat from the liquid surface of the upper part of the solution to dissipate heat. Therefore, the temperature control is easy, the reaction temperature can be set high, and high productivity can be realized. A condenser for trapping monomer and / or solvent is installed at the top of the reactor.

In this case, pumping is required for each tank to transfer the liquid from the reaction tank to the reaction tank. The raw material liquid is supplied to the first stirring reaction tank by a pump, and then the second reaction tank is pumped out from the first reaction tank. The third and subsequent tanks are also similarly pumped out. Become.

Further, the liquid-filled agitation reactor, which is mentioned as an example, is a device which can arrange the multi-tank reactors in series and feed the multi-tank reactor using a single pump. . It is sufficient to use one pump when putting the raw materials into the reactor, and it is possible to perform the reaction in a closed system, from the raw material charging to the reaction, devolatilization, and polymer pelletization without contact with the external atmosphere. You can This is an advantage that cannot be obtained by the conventional production using a batch reactor, and is a continuous polymerization method which is particularly suitable for producing a decomposable polymer which is decomposed by heat, oxygen and water used in the present invention.

As another continuous production method, it is preferable to use a static mixer. The static mixer mentioned here refers to a mixing device having a stirrer,
A static mixing device with no moving parts, i.e. without a stirrer, in which a mixing element fixed in the tube with no moving parts divides the flow and diverts or reverses the flow direction. , A mixing device that mixes solutions by repeatedly dividing, converting, and inverting the flow in the vertical and horizontal directions. Depending on the type of static mixer, some have a jacket for heat exchange on the outer circumference of the pipe, and some have a tube for heat exchange that allows the heat medium to pass through the mixing element itself. is there.

The static mixer is usually tubular, and a plurality of static mixers are linearly connected to each other, and the raw material is continuously supplied from a raw material charging port under an inert gas atmosphere. By continuously moving the polymer, it is possible to carry out the polymerization continuously, and from the charging of the raw materials to the polymerization, the deglazing, and the pelletization of the polymer without any contact with the outside atmosphere.

In the production of the high-molecular-weight lactic acid-based polyester of the present invention, all the polymerization reactions can be carried out only by a polymerization apparatus equipped with a static mixer. To
In particular, in order to exert the stirring effect remarkably, in the stage where the polymer viscosity is relatively low in the initial stage of the polymerization, polymerization is carried out in a polymerization tank having an ordinary stirrer, and the latter step of increasing the viscosity of the polymer is performed by a static mixer. Since the polymerization can be carried out in a provided polymerization apparatus, a continuous polymerization apparatus equipped with a stirring type polymerization tank and a static mixer connected thereto can also be used.

The lactide, the polyester-based polymer, and the obtained high-molecular-weight lactic acid-based polyester are easily dissolved in a solvent or the like and can be polymerized using the solvent or the like. Further, the obtained high-molecular-weight lactic acid-based polyester has a high melting point and a high melt viscosity, which makes it difficult to polymerize, but the addition of a solvent lowers the viscosity of the polymerization system, facilitates stirring, and facilitates polymerization.

Particularly when a continuous polymerization apparatus equipped with a static mixer is used, the extrusion pressure of the polymerization solution is lowered, and a polymerization apparatus having a heat medium internal device for the purpose of temperature control and a baffle plate for the purpose of stirring. Is effective because the equipment can be lightened. Furthermore, since the stirring is easy, it is easy to control the temperature and the temperature is uniform in the polymerization equipment.
A lactic acid-based polyester with less coloring is obtained.

When reacting with a trifunctional or higher polyvalent carboxylic acid and / or its acid anhydride (C), an addition line is installed so that (C) is added at the time of polymerization addition. You can

Examples of the solvent used are benzene, toluene, ethylbenzene, xylene, cyclohexanone,
Methyl ethyl ketone, methyl isobutyl ketone and isopropyl ether are preferably used. When carrying out the polymerization using a solvent, the polymerization rate becomes slow. For the purpose of improving this, the polymerization temperature is preferably 140 to 195 ° C.

During the polymerization or the reaction with a polyfunctional carboxylic acid having 3 or more functional groups and / or its acid anhydride (C), if water enters, inhibition occurs and the decomposition reaction is promoted. Good under gas atmosphere. It is particularly preferable to carry out the polymerization under a nitrogen or argon gas atmosphere or under an inert gas atmosphere.

It is desirable to carry out devolatilization under reduced pressure for the purpose of removing lactide, solvent and odorous substances remaining in the latter stage of polymerization. By this devolatilization step, the amount of residual lactide can be reduced, and the storage stability of the obtained high molecular weight lactic acid-based polyester can be significantly increased.

Residual lactide is not preferable when a high-molecular-weight lactic acid-based polyester is used as a sheet or film because it causes hydrolysis due to adhesion of water or fusion due to heat. In addition, it is not preferable because it is scattered by sublimation from the film or sheet that has been commercialized. Therefore, the amount of residual lactide in the high-molecular-weight lactic acid-based polyester of the present invention is preferably 2% by weight or less. More preferably, it is 1% by weight or less.

As a concrete devolatilization method, a method of taking out while heating under reduced pressure after polymerization is preferable. In order not to reduce the molecular weight of the high-molecular-weight lactic acid-based polyester, devolatilization conditions are as follows: devolatilization time: 2 to 30 minutes, temperature: 145
It is preferable to carry out at ˜230 ° C. and the degree of vacuum at 0.1˜200 Torr. As another devolatilization method, there is a method of pelletizing or crushing the high-molecular-weight lactic acid-based polyester after completion of the polymerization, and taking out while heating under reduced pressure.

Also in this case, the devolatilization time is 2 to 400 for the purpose of not decreasing the molecular weight of the high-molecular-weight lactic acid-based polyester.
Min, temperature 60 ~ 200 ℃, decompression degree 0.1 ~ 50To
rr is preferred. By these devolatilization methods,
Lactide remaining about 2.5% is 1.0% or less,
Further, if necessary, it can be reduced to 0.1% or less.

When the copolymer of the present invention is produced, a cyclic ester other than lactide (A) may be further added to produce a high molecular weight lactic acid-based polyester. In particular, 1 to 20% by weight of lactone can be added for the purpose of softening.

The cyclic ester to be added in addition to the lactide is not particularly limited, but specifically, a cyclic dimer of hydroxy acid such as glycolide, an intramolecular lactide, particularly ε-caprolactone, γ-valerolactone, γ
-Undecalactone and the like. When the amount of lactone increases, the glass transition point and melting point decrease, and the flexibility increases.

The production method according to the present invention can provide high-molecular-weight lactic acid-based polyester having high rigidity to high-molecular-weight lactic acid-based polyester having high flexibility. That is, the degradability and tensile elastic modulus are 500 to 50,000.
General purpose resin such as resin for packaging materials such as sheets and films, which has 0 kg / cm ² and can be widely used as general purpose resin, foaming resin, extrusion molding resin, injection molding resin, ink resin, lamination resin, etc. A polymer useful as the above can be provided, and it is particularly useful as a method for producing a polymer for a packaging material.

The lactic acid-based copolyester of the present invention has T
Sheets and films can be easily processed by extrusion molding such as die-cast molding and inflation molding. Since lactic acid-based copolyester is highly hygroscopic, it is easily hydrolyzed, and when processing packaging materials such as sheets and films, it can be easily done with a general single-screw extruder, but water management is important. .

The screw has a normal L / D of 20 to 30.
It may be a full flight type, and a vent may be attached. When using a single-screw extruder, dehumidify and dry with a vacuum dryer etc. to avoid hydrolysis in the extruder,
It is preferable to control the water content in the raw material to 50 ppm or less.
The appropriate extrusion temperature varies depending on the molecular weight of the lactic acid-based copolyester to be used and the amount of residual lactide, but is preferably at least the flow initiation temperature.

In the T die-cast molding, the sheet and the film after extrusion are cooled with a mirror surface or a satin roll which is usually temperature-controlled. At this time, an air knife can be used. Further, when a twin-screw extruder provided with a vent is used, the dehydration effect is high, and thus pre-drying is not required and efficient film formation is possible. At the time of inflation molding, molding can be easily performed with a molding device equipped with a normal circular die and an air ring, and no special auxiliary device is required. At this time, in order to avoid uneven thickness, the die, air ring or winder may be rotated.

The formed sheet or film can be uniaxially or biaxially stretched at a temperature not lower than the glass transition temperature and not higher than the melting point by a tenter system or an inflation system. By carrying out the stretching treatment, molecular orientation is caused and physical properties such as impact resistance, rigidity and transparency can be improved.

The stretching may be simultaneous stretching or sequential stretching, and the stretching speed is not particularly limited. The stretching ratio is not particularly limited either, but in biaxial stretching, it is usually effective to stretch 2 to 4 times in the machine and transverse directions. In addition, especially when shrinkage property such as shrink film when heating is required,
High-strength stretching such as 3 to 6 times in the uniaxial or biaxial direction is preferable. Further, in order to improve heat resistance, heat setting may be carried out immediately after stretching to promote strain removal or crystallization to improve heat resistance.

When forming these sheets and films,
A general filler, for example, an inorganic filler such as talc, calcium carbonate, silica, clay, diatomaceous earth, perlite, or an organic filler such as wood powder may be mixed and added. In addition, 2,6-di-t-butyl-4-methylphenol (BHT), butyl hydroxyanisole (BH
It is possible to improve thermal stability during molding by using an antioxidant such as A), a salicylic acid derivative, a benzophenone-based or benzotriazole-based UV absorber, and a stabilizer such as phosphoric acid ester or carbodiimide. it can.

The amount of these stabilizers added is not particularly limited, but it is usually preferable to add it in an amount of 0.01 to 1% with respect to the weight of the high molecular weight lactic acid-based polyester. The high-molecular-weight lactic acid-based polyester of the present invention alone has sufficient plasticity and has good melt moldability. To enhance softening, a plasticizer such as dioctyl adipate, dioctyl sebacate, trioctyl trimellitate, diethyl phthalate, dioctyl phthalate, polypropylene glycol adipic acid, butanediol adipate may be added. .

Among them, the adipic acid-based polyester plasticizer is particularly preferable in terms of moldability and flexibility, and has a weight average molecular weight of 20,000 or less, and the end of the polyester is sealed with alcohol or the like. The compatibility with the polymer is good and it is particularly preferable. The addition amount of these plasticizers is not particularly limited, for the purpose of avoiding bleeding, a phenomenon in which excess plasticizer is eluted from the resin,
1 to 30% by weight of high molecular weight lactic acid based polyester
Is preferably added in an amount of.

Further, metal soaps such as zinc stearate, magnesium stearate and calcium stearate, mineral oil, liquid paraffin, lubricants such as ethylene bisstearyl amide, nonionics such as glycerin fatty acid ester and sucrose fatty acid ester, and alkyl sulfonates. Addition of ionic surfactants such as the above, coloring agents such as titanium oxide and carbon black, etc. may be performed without any problem.

Further, by adding an inorganic foaming agent such as sodium bicarbonate or ammonium bicarbonate, an organic foaming agent such as azodicarbonamide, azobisisobutyronitrile or sulfonylhydrazide, or by adding pentane, butane,
A foaming agent such as freon may be impregnated with the polymer of the present invention in advance, or may be directly supplied into the extruder during the extrusion process to give a foam. It is also possible to make a multilayer with paper, aluminum foil, or other degradable polymer film by extrusion laminating, dry laminating or co-extrusion.

As the secondary processing method of the sheet, a vacuum forming method, a pressure forming method, a vacuum pressure forming method and the like can be used. The lactic acid-based copolyester of the present invention can be formed into a sheet by using an existing apparatus used for producing a sheet of a general-purpose resin. In the case of vacuum forming or vacuum pressure forming, plug assist forming may be performed. The stretched sheet is preferably subjected to pressure molding. It should be noted that heating and cooling of the mold can be optionally used in combination during these moldings.
In particular, the heat resistance can be improved by heating the mold above the crystallization temperature and actively promoting the crystallization.

A general processing method can be applied to the secondary processing of the film, and the bag-like material is heat-sealed by an ordinary bag-making machine such as a horizontal pillow bag-making machine, a vertical pillow bag-making machine, and a twist bag bag-making machine. Obtainable. When obtaining processed products other than these sheets and films, molds such as containers can be obtained using an ordinary injection molding machine. Blow molding is also easy, and single-layer and multi-layer bottles can be easily molded by using an existing molding machine. There is no particular problem in press molding, and a single-layer or laminated product can be obtained by an ordinary molding machine.

The high-molecular-weight lactic acid-based polyester obtained in the present invention has good biodegradability, and is discarded after being used as a general-purpose resin, packaging material, etc., or even discarded from the manufacturing process. Helps to lose weight. Even when it is dumped into the sea, it is hydrolyzed and decomposed by microorganisms. Decomposition in seawater also deteriorates the strength of the resin within a few months, and it can be decomposed before the outer shape is maintained.

[0115]

EXAMPLES The present invention will be described in more detail below with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples. All parts in the examples are on a weight basis unless otherwise specified.

The molecular weight was measured by a GPC measuring device (hereinafter abbreviated as GPC, column temperature 40 ° C., tetrahydrofuran solvent) in comparison with a polystyrene standard sample.

The glass transition point and the melting point were measured by a differential scanning calorimeter (hereinafter abbreviated as DSC). The thermogravimetric reduction rate is a differential thermogravimetric analyzer (hereinafter abbreviated as TG / DTA. 10
The temperature was raised from 20 ° C to 220 ° C at 0 ° C / min, and the temperature was maintained for 50 minutes. ) Was measured.

The tensile test was conducted with a hot press machine at 160
Using a film having a thickness of 200 μm prepared under the conditions of ˜170 ° C., 200 kg / cm ² , and 2 minutes, a tensile tester (pulling speed: 20 mm / min) was used. The measurement conditions of the Vicat softening temperature test are JIS K7206.
It was measured according to the method A. The test piece used was a one-ounce injection molding machine molded into a dumbbell shape. The following equipment was used as the above equipment.

GPC: TOSOH HLC-8020
(Tosoh Corporation) DSC: DSC 200 (Seiko Electronics Co., Ltd.) TG / DTA: TG / DTA 220 (Seiko Electronics Co., Ltd.) Tensile Tester: Tensilon (Toyo Seiki Co., Ltd.) Vicat softening temperature: HDT. VSPT. TESTER
(Made by Toyo Seiki Co., Ltd.)

Further, in this example, unless otherwise stated, an experiment was conducted using any one of the following three types of polyesters.

As a polyester containing an aliphatic dicarboxylic acid component, adipic acid component 50 mol%, ethylene glycol component 28 mol%, neopentyl glycol component 22
Those having a weight average molecular weight of 30,210 and a number average molecular weight of 15,200 composed of mol% were used. Hereinafter abbreviated as (P-1).

As a polyester containing an aromatic dicarboxylic acid component and an aliphatic dicarboxylic acid component, terephthalic acid component 14 mol%, isophthalic acid component 16 mol%, adipic acid component 20 mol%, ethylene glycol component 28 mol%, neopentyl glycol Weight average molecular weight of 45,200 consisting of 22 mol% of components, number average molecular weight of 24,700
I used the one. Hereinafter abbreviated as (P-2).

Example 1 (P-1) 10 parts, L-lactide 90 parts, pyromellitic dianhydride L-lactide and (P-1) 10 in total.
0.002 part was added to 0 part, and the mixture was melted and mixed at 175 ° C. for 0.5 hour in a nitrogen gas atmosphere, and 0.02 part of tin octoate was added as a ring-opening polymerization catalyst.

The reaction was carried out at 175 ° C. for 3 hours, and the produced copolymer was taken out. The obtained lactic acid-based high molecular weight polyester was a yellowish transparent resin. From the results of GPC, a weight average molecular weight of 315,000 and a number average molecular weight of 122,0 which are larger than the molecular weight of the polyester containing the starting aromatic dicarboxylic acid component and the aliphatic dicarboxylic acid component
A lactic acid-based high molecular weight polyester having 00 was confirmed.

From the result of GPC after 3 hours of reaction, it was confirmed that the fraction derived from the copolymer was single, and that a single copolymer was produced, and the small fraction derived from the lactide remained. confirmed. The glass transition point of this lactic acid-based high molecular weight polyester was found to be about 56 ° C, and the melting point was found to be about 158 ° C. The tensile breaking strain is 41% and the tensile breaking strength is 520 kgf.
/ Cm ² , initial tensile elastic modulus is 10,100 kgf / cm ²
Met.

Example 2 (P-2) was added to 5 parts, L-lactide (93 parts), D-lactide (2 parts), pyromellitic dianhydride to lactide and (P-2) to 100 parts in total. 05 parts and 20 parts of toluene were added, and under a nitrogen gas atmosphere, 175 ° C.
After dissolving and mixing for 5 hours, 0.02 part of tin octoate was added as a ring-opening polymerization catalyst and the reaction was carried out at 175 ° C. for 3 hours. After the reaction, toluene was removed under reduced pressure.

The produced lactic acid-based high molecular weight polyester had a weight average molecular weight of 356,000 and a number average molecular weight of 152.0.
00 was a colorless and transparent resin. It has a glass transition point of about 58 ° C., a melting point of about 160 ° C., a tensile breaking strain of 9.6%,
Tensile strength at break is 650 kgf / cm ^2, the tensile initial modulus of 13,000kgf / cm ^2.

Example 3 30 parts of (P-1), 68 parts of L-lactide, 2 parts of D-lactide, 1 part of trimellitic anhydride with respect to lactide and 100 parts of (P-1) in total. , Toluene 15 parts, and dissolved and mixed in a nitrogen gas atmosphere at 165 ° C. for 0.5 hours, and 0.02 part of tin octanoate as a ring-opening polymerization catalyst was added, followed by reaction at 165 ° C. for 3 hours. After the reaction, the toluene was removed under reduced pressure.

The lactic acid-based high molecular weight polyester produced had a weight average molecular weight of 110,000 and a number average molecular weight of 42,000.
It was a colorless transparent resin of 0. It had a glass transition point of about 53 ° C., a melting point of about 150 ° C., a tensile breaking strain of 230%, a tensile breaking strength of 490 kgf / cm ² , and an initial tensile elastic modulus of 8,100 kgf / cm ² .

Example 4 To 5 parts of (P-2), 93 parts of L-lactide, 2 parts of D-lactide and 15 parts of toluene were added, and under a nitrogen gas atmosphere, at 175 ° C. for 0.5 hour. After dissolving and mixing, 0.02 part of tin octoate as a ring-opening polymerization catalyst was added and polymerization was carried out for 3 hours. The lactic acid-based copolyester obtained had a weight average molecular weight of 161,000. Pyromellitic dianhydride was further added thereto, and lactide and (P-2) were added in total of 10
0.002 parts was added to 0 parts and reacted for 3 hours.
After the reaction, toluene was removed under reduced pressure.

The produced lactic acid type high molecular weight polyester has a weight average molecular weight of 517,000 and a number average molecular weight of 215,0.
00 was a colorless and transparent resin. It had a glass transition point of about 59 ° C., a melting point of about 158 ° C., a tensile breaking strain of 12%, a tensile breaking strength of 550 kgf / cm ² , and an initial tensile elastic modulus of 11,900 kgf / cm ² .

Example 5 To 30 parts of (P-1), 70 parts of L-lactide and 15 parts of toluene were added, and the mixture was heated to 165 ° C. under a nitrogen gas atmosphere.
After dissolving and mixing for 0.5 hour, 0.03 part of tin octoate was added as a ring-opening polymerization catalyst and polymerization was carried out for 3 hours. The lactic acid-based copolyester obtained had a weight average molecular weight of 7
It was 3,000. Further, pyromellitic dianhydride was added to the lactide and (P-1) in an amount of 0.
Addition of 05 parts and reaction for 2 hours.

After the reaction, toluene was removed under reduced pressure. The lactic acid-based high molecular weight polyester produced has a weight average molecular weight of 14
It was a colorless and transparent resin having a molecular weight of 5,000 and a number average molecular weight of 70,100. It has a glass transition point of about 54 ° C, a melting point of about 149 ° C, a tensile breaking strain of 330%, and a tensile breaking strength of 47.
0 kgf / cm ² , initial tensile elastic modulus is 8,200 kgf
Was / cm ² .

Example 6 To 5 parts of (P-1), 93 parts of L-lactide, 2 parts of D-lactide, and 20 parts of toluene were added, and the mixture was placed in a nitrogen gas atmosphere at 165 ° C. for 0.5 hours. After dissolving and mixing, 0.05 part of tin octoate was added as a ring-opening polymerization catalyst and polymerization was carried out for 3 hours. The lactic acid-based copolyester obtained had a weight average molecular weight of 161,000. Pyromellitic dianhydride was further added thereto, and lactide and (P-1) were added in total of 10
0.5 part was added to 0 part and reacted for 2 hours. After the reaction, toluene was removed under reduced pressure.

The produced lactic acid type high molecular weight polyester has a weight average molecular weight of 327,000 and a number average molecular weight of 119,0.
00 was a colorless and transparent resin. The glass transition point of which is about 57 ° C., a melting point of about 156 ° C., the tensile strain at break of 18%, a tensile break strength of 510kgf / cm ^2, the tensile initial modulus of 13,000kgf / cm ^2.

Example 7 To 20 parts of (P-1) was added 15 parts of toluene, and the mixture was dissolved and mixed in a nitrogen gas atmosphere at 100 ° C. for 0.5 hours, and then trimellitic anhydride was added. Was added to 0.002 part of 100 parts of (P-1) and 0.005 part of tetraisopropyl titanate as a catalyst, and the reaction was carried out at 120 ° C. for 2 hours. The weight average molecular weight of the obtained polyester was 54,
It was 100 and the number average molecular weight was 19,400.

Further, 70 parts of L-lactide, 10 parts of D-lactide and 0.0% of tin octoate as a ring-opening polymerization catalyst.
Two parts were added and reacted at 175 ° C. for 3 hours. After the reaction, toluene was removed under reduced pressure. The produced lactic acid-based high molecular weight polyester was a brownish transparent resin having a weight average molecular weight of 168,000 and a number average molecular weight of 55,200. It has a glass transition point of about 51 ° C, a melting point of about 154 ° C, a tensile breaking strain of 180%, and a tensile breaking strength of 420 kgf / c.
m ² and initial tensile elastic modulus were 7,900 kgf / cm ² .

Example 8 To 15 parts of toluene was added to 5 parts of (P-2), and the mixture was dissolved and mixed in a nitrogen gas atmosphere at 120 ° C. for 0.5 hour, and then pyromellitic dianhydride was added. (P-2) 0.05 part with respect to 100 parts in total, and tin octoate as a catalyst is 0.00
1 part was added and the reaction was carried out at 120 ° C. for 2 hours. The polyester obtained had a weight average molecular weight of 71,100 and a number average molecular weight of 32,400.

Furthermore, 93 parts of L-lactide, 2 parts of D-lactide, and 0.02 tin octanoate as a ring-opening polymerization catalyst were used.
A portion was added and the reaction was carried out for 3 hours at 175 ° C. After the reaction, toluene was removed under reduced pressure. The produced lactic acid-based high molecular weight polyester has a weight average molecular weight of 325,000 and a number average molecular weight of 1
It was 49,000 colorless and transparent resin. It has a glass transition point of about 56 ° C, a melting point of about 152 ° C, and a tensile breaking strain of 2
The tensile strength at break was 7%, the tensile strength at break was 560 kgf / cm ² , and the initial tensile elastic modulus was 12,000 kgf / cm ² . [Example 9] A terephthalic acid component of 31 mol%, an adipic acid component of 17 mol%, an ethylene glycol component of 23 mol%, a neopentyl glycol component of 27 mol%, and a pyromellitic dianhydride component of 0.05 mol% were charged, and the total amount was 205 to 210. After esterification at 8 ° C. to an acid value of 8.1, 100 ppm of tetraisopropyl titanate was added, the reaction was carried out at a temperature of 215 to 220 ° C., and finally a deglycolization reaction was carried out for 8 hours under a reduced pressure of 0.5 Torr.

The obtained aromatic / aliphatic polyester had a weight average molecular weight of 118,000 and a number average molecular weight of 34,50.
It was 0 (hereinafter abbreviated as (P-3)). To 10 parts of this polyester, 90 parts of L-lactide and 15 parts of toluene were added, and under a nitrogen gas atmosphere, 175 ° C. for 0.25 hours.
After dissolving and mixing, 0.02 part of tin octoate was added as a ring-opening polymerization catalyst, and after the reaction for 3 hours, 0.1 part of ε-caprolactone was further added and reacted at 175 ° C. for 1 hour. After the reaction, toluene was removed under reduced pressure.

The produced lactic acid type high molecular weight polyester has a weight average molecular weight of 340,000 and a number average molecular weight of 129,0.
It was a transparent resin with a brownish color of 00. It has a glass transition point of about 55 ° C, a melting point of about 155 ° C, and a tensile breaking strain of 2.
8%, a tensile break strength of 460kgf / cm ^2, the tensile initial modulus of 11,000kgf / cm ^2.

Example 10 27 mol% of adipic acid component, 20 mol% of succinic acid component,
Ethylene glycol component 30 mol%, neopentyl glycol component 20 mol%, pyromellitic acid component 0.3 mol% were charged and esterified at 205 to 210 ° C. to make the acid value 9.1, and then tetraisopropyl titanate 100
ppm is added, and the temperature is 215 to 220 ° C., and finally 0.
The deglycol reaction was carried out for 8 hours under a reduced pressure of 5 Torr.

The obtained aliphatic polyester had a weight average molecular weight of 53,500 and a number average molecular weight of 16,500 (hereinafter, abbreviated as P-4). 30 parts of this polyester, L
-68 parts of lactide, 2 parts of D-lactide, 1 part of toluene
5 parts were added, and under a nitrogen gas atmosphere, 175 ° C., 0.2
After dissolving and mixing for 5 hours, 0.02 part of tin octoate was added as a ring-opening polymerization catalyst and reacted for 3 hours.

After the reaction, toluene was removed under reduced pressure. The lactic acid-based high molecular weight polyester produced has a weight average molecular weight of 15
It was a colorless and transparent resin having 1,000 and a number average molecular weight of 101,000. It has a glass transition point of about 53 ° C, a melting point of about 152 ° C, a tensile breaking strain of 270% and a tensile breaking strength of 4%.
00 kgf / cm ² , initial tensile elastic modulus is 7,800 kg
It was f / cm ² .

[Embodiment 11] In this embodiment, a reaction apparatus in which three liquid-filled type stirring reactors having a 4-liter internal capacity equipped with helical stirring blades are arranged in series, and A reactor was used in which the reaction tank was connected to two devolatilization tanks via a 1 / 2-inch static mixer (Kenix static mixer manufactured by Noritake).

The raw material is supplied under the atmosphere of nitrogen gas, and after the polymer having lactide and hydroxyl group is made into a 15% solution of toluene at 110 ° C., the average residence time of the raw material is 8 hours by using a plunger pump. As such was fed to the first reactor. The catalyst used was tin octoate and was added before the first reactor. An addition line was provided at the entrance of the third reactor so that pyromellitic dianhydride can be added. The supply amount of each component is shown below.

[0147] Raw material supply flow rate: 1.5 l / hour Catalyst supply flow rate: 0.5 ml / hour Pyromellitic dianhydride supply: 5.00 g / hour

The starting lactide and the polymer component having a hydroxyl group are summarized below. L-lactide: 73% D-lactide: 4% Polymer having a hydroxyl group: 10% Toluene: 13%

Polyester is used as the polymer having a hydroxyl group, and the component is 35 mol% of adipic acid,
15 mol% succinic acid, 40 mol% ethylene glycol,
Neopentyl glycol 10 mol%, weight average molecular weight 3
5,100, number average molecular weight 18,200 (hereinafter (P-
5) and abbreviated).

250 pp. Of tin octoate as a catalyst
m was supplied so that the produced polymer was continuously extracted from the discharge part at the upper part of the final reaction tank using a gear pump.

The control temperatures of the 4-tank reactor used are shown in the table below. First reaction tank reaction temperature: 155 ° C Second reaction tank reaction temperature: 155 ° C Third reaction tank reaction temperature: 165 ° C

The conditions for the devolatilization treatment are as follows: the temperature of the heat exchanger before the first devolatilization device: 220 ° C., the degree of vacuum of the devolatilization tank: 110To
It was rr. Temperature of heat exchanger in front of second devolatilizer: 2
The degree of vacuum in the devolatilization tank was 05 ° C .: 8 Torr.

After the obtained polymer was pelletized, various properties and physical properties were measured. The obtained pellet was a slightly yellowish transparent resin. The obtained high molecular weight lactic acid-based copolyester has a weight average molecular weight of 301,
It was a colorless and transparent resin having a number average molecular weight of 101,000. It has a glass transition point of about 53 ° C and a melting point of about 1.
52 ° C, tensile breaking strain 28%, tensile breaking strength 500k
gf / cm ² , initial elastic modulus in tension is 11,800 kgf /
It was cm ² .

Example 12 A circulation polymerization line in which four static mixers having an inner diameter of 0.5 inch and a length of 60 cm were connected in series, and an inner diameter of 3
/ 4 inch, 50 cm long static mixer (made by Noritake, with 15 mixing elements) 2
A continuous polymerization apparatus having a polymerization region consisting of a circulation polymerization line equipped with a circulation gear pump and a polymerization line continuously connected to the basic series was used.

The catalyst is mixed with the main raw material by a catalyst feed pump by a static mixer (made by Noritake Co., Ltd. with 12 mixing elements) having an inner diameter of 1/4 inch and a length of 15.5 cm immediately before the main raw material feed pump.

As a main raw material solution prepared in a nitrogen gas atmosphere, 78 parts of L-lactide, 4 parts of D-lactide, an aliphatic polyester previously polymerized with trimellitic acid (29 mol% of adipic acid component, succinic acid) Ingredient 2
0 mol%, ethylene glycol component 30 mol%, neopentyl glycol component 20 mol%, trimellitic acid component 0.3 mol%, weight average molecular weight 53,500, number average molecular weight 16,500 and below (P-6) I will omit it. ) Of 50%
Using 18 parts of a toluene solution and 0.04 part of zinc 2-ethylhexanoate as a catalyst, polymerization was continuously carried out under the following conditions.

[0157] Main raw material supply flow rate: 400 ml / hour Catalyst supply flow rate: 1.6 ml / hour Reaction temperature: 160 ° C Flow rate circulated in the circulation polymerization line: 2 l / hour Reflux ratio: 5

The polymerization solution was introduced into a device comprising a heat exchanger, a devolatilizing tank and the like with a gear pump capable of keeping heat for high viscosity and devolatilized. The temperature of the heat exchanger before the devolatilization device was 200 ° C., and the degree of vacuum of the devolatilization tank was 4 to 10 Torr. The obtained lactic acid-based high molecular weight polyester was a yellowish transparent resin, and after pelletizing the resin, various properties and physical properties were measured.

From the results of GPC, a weight average molecular weight of 368,
000 high-molecular-weight lactic acid-based copolyesters were confirmed. Glass transition point is about 55 ° C, melting point is about 152 ° C, tensile breaking strain is 30%, tensile breaking strength is 490 kgf / c
m ² and initial tensile elastic modulus were 10,900 kgf / cm ² .

This high-molecular-weight lactic acid-based copolyester pellet was hot-pressed to a thickness of 10 cm × 10 c.
m, 100 μm sheet was prepared. Press conditions, 16
A sheet having a weight average molecular weight of 355,000 was obtained by pellets having a weight average molecular weight of 368,000 under the conditions of 5 ° C., 200 kg / cm ² and 2 minutes. The decrease in molecular weight was 3.5%.

This sheet was embedded in soil and a biodegradation test was tried. The results are shown in Table 1.

[0162]

[Table 1] Biodegradation test results

[Application Example 1] After the pellets obtained in Example 1 were sufficiently dried, L
Blow molding was carried out by a blow molding machine (manufactured by Japan Steel Works, Ltd.) using an extruder having a screw diameter of 40 mm with / D = 25 to obtain a 60 ml bottle excellent in mold reproducibility and transparency. The molding conditions are a cylinder temperature of 170 to 180 ° C., a cylinder head temperature of 180 ° C., a mold temperature of 32 ° C., a discharge rate of 4.2 kg / hr, and a die core of 3 kgf / cm ^2.
Blows the air.

[Application Example 2] The pellets obtained in Example 4 were thoroughly dried, then extruded with a 50 mm extruder equipped with a die having a width of 400 mm, and laminated on a paper having a basis weight of 200 g / m ² . Molding conditions are cylinder temperature 150-210 ℃, die temperature 21
The temperature was 0 ° C., the cooling roll temperature was 60 ° C., the discharge rate was 4 kg / h, and the line speed was 10 m / min. The obtained paper laminae have excellent film thickness uniformity and a laminate strength of 370 g /
It was as good as 15 mm or more.

Comparative Example 1 To 100 parts of L-lactide, 15 parts of toluene was added,
Under a nitrogen gas atmosphere, the mixture was dissolved and mixed at 175 ° C. for 0.5 hour, 0.02 part of tin octoate was added as a ring-opening polymerization catalyst, and polymerization was carried out for 3 hours. After the reaction, toluene was removed under reduced pressure. The produced L-polylactic acid had a weight average molecular weight of 27.
It was a colorless and transparent resin having a molecular weight of 3,000 and a number average molecular weight of 140,000. It has a glass transition point of about 57 ° C., a melting point of about 158 ° C., a tensile breaking strain of 6.0%, and a tensile breaking strength of 4.
50 kgf / cm ² , initial tensile elastic modulus is 11,000 k
It was gf / cm ² .

Comparative Example 2 70 parts of L-lactide was mixed with polycaprolactone (UCC).
30 parts of Tone Co., Ltd.) and 15 parts of toluene were added and dissolved and mixed in a nitrogen gas atmosphere at 175 ° C. for 0.5 hour, and 0.02 part of tin octoate was added as a ring-opening polymerization catalyst. Polymerization was carried out for 3 hours. After the reaction, toluene was removed under reduced pressure. The produced lactic acid-based copolyester was a white resin having a weight average molecular weight of 123,000 and a number average molecular weight of 62,000. It has a glass transition point of about 30 ° C., a melting point of about 149 ° C., a tensile breaking strain of 100%, a tensile breaking strength of 320 kgf / cm ² , and an initial tensile elastic modulus of 6,800.
It was kgf / cm ² .

Comparative Example 3 To 10 parts of (P-1), 90 parts of L-lactide and 20 parts of toluene were added, and the mixture was heated to 175 ° C. under a nitrogen gas atmosphere.
After dissolving and mixing for 0.5 hour, 0.02 part of tin octoate as a ring-opening polymerization catalyst was added and polymerization was carried out for 3 hours. After the reaction, toluene was removed under reduced pressure. The produced lactic acid-based copolyester was a colorless and transparent resin having a weight average molecular weight of 140,000 and a number average molecular weight of 81,000. The glass transition point of which is about 47 ° C., a melting point of about 156 ° C., the tensile strain at break 12%, a tensile break strength of 450 kgf / cm ^2, the tensile initial modulus of 10,000kgf / cm ^2.

Comparative Example 4 To 20 parts of (P-1), 70 parts of L-lactide, 10 parts of D-lactide and 20 parts of toluene were added, and under a nitrogen gas atmosphere, at 175 ° C. for 0.5 hours. After dissolving and mixing, 0.02 part of tin octoate as a ring-opening polymerization catalyst was added and polymerization was carried out for 3 hours. After the reaction, toluene was removed under reduced pressure.
The produced lactic acid-based copolyester has a weight average molecular weight of 1
It was a colorless and transparent resin having 10,000 and a number average molecular weight of 63,200. It has a glass transition point of about 44 ° C., a melting point of about 154 ° C., a tensile breaking strain of 21%, and a tensile breaking strength of 39.
0 kgf / cm ² , initial tensile elastic modulus is 7,600 kgf
Was / cm ² .

[Comparative Example 5] To 30 parts of (P-1), 68 parts of L-lactide, 2 parts of D-lactide and 20 parts of toluene were added, and under a nitrogen gas atmosphere, at 165 ° C for 0.5 hour. After dissolving and mixing, 0.03 part of tin octoate as a ring-opening polymerization catalyst was added and polymerization was carried out for 3 hours. After the reaction, toluene was removed under reduced pressure. The produced lactic acid-based copolyester has a weight average molecular weight of 7
It was a colorless and transparent resin having a molecular weight of 8,000 and a number average molecular weight of 41,000. It has a glass transition point of about 38 ° C., a melting point of about 146 ° C., a tensile breaking strain of 40%, and a tensile breaking strength of 300.
kgf / cm ² , initial tensile elastic modulus is 5,800 kgf /
It was cm ² .

Comparative Example 6 To 5 parts of (P-2), 93 parts of L-lactide, 2 parts of D-lactide and 20 parts of toluene were added, and under a nitrogen gas atmosphere, at 175 ° C. for 0.5 hour. After dissolving and mixing, 0.03 part of tin octoate as a ring-opening polymerization catalyst was added and polymerization was carried out for 3 hours. After the reaction, toluene was removed under reduced pressure. The produced lactic acid-based copolyester has a weight average molecular weight of 16
It was a colorless and transparent resin having 1,000 and a number average molecular weight of 83,200. It has a glass transition point of about 46 ° C, a melting point of about 154 ° C, a tensile breaking strain of 7.7% and a tensile breaking strength of 41.
0 kgf / cm ² , initial tensile elastic modulus is 7,500 kgf
Was / cm ² .

Comparative Example 7 To 30 parts of (P-1), 70 parts of L-lactide and 15 parts of toluene were added, and under a nitrogen gas atmosphere, 165 ° C.
After dissolving and mixing for 0.5 hour, 0.03 part of tin octoate was added as a ring-opening polymerization catalyst and polymerization was carried out for 3 hours. After the reaction, toluene was removed under reduced pressure. The produced lactic acid-based copolyester was a colorless and transparent resin having a weight average molecular weight of 73,000 and a number average molecular weight of 37,000. This had a glass transition point of about 45 ° C., a melting point of about 151 ° C., a tensile breaking strain of 78%, a tensile breaking strength of 400 kgf / cm ² , and an initial tensile elastic modulus of 7,600 kgf / cm ² .

[Comparative Example 8] To 5 parts of (P-1), 93 parts of L-lactide, 2 parts of D-lactide and 20 parts of toluene were added, and under a nitrogen gas atmosphere, at 175 ° C for 0.5 hour. After dissolving and mixing, 0.03 part of tin octoate as a ring-opening polymerization catalyst was added and polymerization was carried out for 3 hours. After the reaction, toluene was removed under reduced pressure. The produced lactic acid-based copolyester has a weight average molecular weight of 14
It was a colorless and transparent resin having a molecular weight of 4,000 and a number average molecular weight of 73,000. It has a glass transition point of about 44 ° C., a melting point of about 153 ° C., a tensile breaking strain of 3.5%, and a tensile breaking strength of 40.
0 kgf / cm ² , initial tensile elastic modulus is 10,500 kg
It was f / cm ² .

Measurement results and TG / DTA of the lactic acid-based copolyesters obtained in Examples and Comparative Examples
The measurement results (weight reduction rate) are shown in Tables 2 to 6. In addition,
The following abbreviations are used in the table.

[0174] Trimellitic acid: TM Pyromellitic dianhydride: TMA Pyromellitic acid: PM Pyromellitic dianhydride: PMDA

[0175]

[Table 2]

[0176]

[Table 3]

[0177]

[Table 4]

[0178]

[Table 5]

[0179]

[Table 6]

[0180]

INDUSTRIAL APPLICABILITY The present invention provides a method for producing a biodegradable high molecular weight lactic acid-based copolyester having sufficient high molecular weight and heat resistance, and having rigidity, flexibility and transparency depending on the use, and the production method thereof. A molded product of the high-molecular-weight lactic acid-based copolyester obtained as described above can be provided.

Claims (9)

(57) [Claims] 1. A lactide (A), a polyester (B1) having hydroxyl groups at both ends, and a polyfunctional carboxylic acid having 3 or more functional groups and / or an acid anhydride thereof (C), (A) /
(B1) = 50/50 to 98/2 in weight ratio, and (C) is 0.001 with respect to the total of (A) and (B1).
~ 5% by weight in the presence of a ring-opening polymerization catalyst (D),
A method for producing a high-molecular-weight lactic acid-based copolymerized polyester, which comprises performing ring-opening copolymerization. 2. A lactide (A) and a polyester (B1) having hydroxyl groups at both ends are (A) / (B1) = 5.
In the presence of the ring-opening polymerization catalyst (D) at a weight ratio of 0/50 to 98/2, ring-opening copolymerization is carried out to produce a polyester, which is further mixed with a polyfunctional carboxylic acid having 3 or more functional groups and / or Production of a high-molecular-weight lactic acid-based copolyester characterized by reacting an acid anhydride (C) with 0.001 to 5% by weight of (C) based on the total of (A) and (B1) Method. 3. A polyester (B1) having hydroxyl groups at both ends and a polyfunctional carboxylic acid having 3 or more functional groups and / or its acid anhydride (C), wherein (C) is less than 0.
The reaction is carried out in the range of 001 to 5% by weight to obtain a polyester (B2) having a weight average molecular weight of 10,000 to 300,000 and having hydroxyl groups at both ends, and further this and lactide (A) are A) / (B2) = 50 / 50-9
A method for producing a high-molecular-weight lactic acid-based copolyester, which comprises performing ring-opening copolymerization in the presence of a ring-opening polymerization catalyst (D) at a weight ratio of 8/2. 4. A dicarboxylic acid, a diol, and 0.001 wt% to 5 wt% of a trifunctional or higher polyvalent carboxylic acid and / or an acid anhydride thereof (C) based on the dicarboxylic acid, After a dehydration reaction and / or a deglycolization reaction to obtain a polyester (B3) having a weight average molecular weight of 10,000 to 300,000, the polyester and the lactide (A) are further mixed with (A) / (B3) = 50 / A method for producing a high-molecular-weight lactic acid-based copolyester, which comprises performing ring-opening copolymerization in the presence of a ring-opening polymerization catalyst (D) at a weight ratio of 50 to 98/2. 5. A polyester (B1) having hydroxyl groups at both ends has a weight average molecular weight of 10,000 to 200,0.
The method for producing a high-molecular-weight lactic acid-based copolyester according to any one of claims 1 to 3, characterized in that it is 00. 6. A trifunctional or higher polyvalent carboxylic acid and / or its acid anhydride (C) is one or more selected from the group consisting of trimellitic acid, trimellitic anhydride, pyromellitic acid and pyromellitic anhydride. 5. The method for producing a high-molecular-weight lactic acid-based copolyester according to any one of claims 1 to 4, which is a polycarboxylic acid and / or an acid anhydride thereof. 7. A high-molecular-weight lactic acid-based copolymer characterized in that the high-molecular-weight lactic acid-based copolyester obtained by the production method according to claim 1 has a weight-average molecular weight of 20,000-600,000. Method for producing polymerized polyester. 8. The method for producing a high molecular weight lactic acid-based copolyester according to claim 1, wherein a static mixer is used in the polymerization reaction device. 9. A high-molecular-weight lactic acid-based copolyester according to any one of claims 1 to 7, characterized in that a continuous polymerization apparatus comprising two or more agitated reactors connected in series is used. Production method.