JP2001192444A - Method for polymerizing aliphatic polyester in solid phase - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for simply producing a high-molecular weight aliphatic polyester substitutable for a general purpose resin required to have toughness in a high volume efficiency. SOLUTION: This method for producing the aliphatic polyester having 50,000 to 1,000,000 weight-average molecular weight, containing >=50% aliphatic hydroxycarboxylic acid unit comprises changing solid-phase polymerization temperatures (reaction temperatures) in the middle of the solid-phase polymerization when a crystallized aliphatic polyester prepolymer having 2,000-100,000 weight-average molecular weight, containing >=50% aliphatic hydroxycarboxylic acid unit is subjected to solid-phase polymerization in the presence of a catalyst.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for solid-state polymerization of an aliphatic polyester containing at least 50% of an aliphatic hydroxycarboxylic acid unit which is a biodegradable polymer useful as a substitute for a medical material or a general-purpose resin. More specifically, when a crystallized low-molecular-weight aliphatic polyester prepolymer containing 50% or more of an aliphatic hydroxycarboxylic acid unit is subjected to solid-state polymerization in the presence of a catalyst, the solid-state polymerization temperature during the solid-state polymerization is increased. (Reaction temperature) by changing 50 units of the aliphatic hydroxycarboxylic acid unit.
% Of a high-molecular-weight aliphatic polyester containing 0.1% by weight or more.

[0002]

2. Description of the Related Art In recent years, waste disposal has become a problem in connection with environmental protection. In particular, molded products and processed products of general-purpose general-purpose polymer materials, when buried as waste, have no decomposability or disintegration by microorganisms or the like, so they remain semi-permanently as foreign substances, and furthermore, a plasticizer. There is a problem that the additives such as elute and contaminate the environment. Also,
When incinerated as waste, the high heat generated by combustion can damage the furnace, and the smoke and exhaust gases generated by combustion can cause air pollution, ozone depletion, global warming, and acid rain. The gains have been highlighted.

[0003] From such a background, there is a demand for a polymer material that is tough but has low heat of combustion and does not damage the furnace, even when it is required to be decomposed or incinerated when it is landfilled after use. Despite the increase, it is not always possible to say that a polymer material that can meet such demands has been supplied. Polylactic acid, which is a kind of aliphatic polyhydroxycarboxylic acid, is highly transparent, tough, and has a property of easily hydrolyzing in the presence of water.
Therefore, when it is used as a general-purpose resin, it is environmentally friendly because it decomposes after disposal without polluting the environment, and when it is placed in a living body as a medical material, it achieves its purpose as a medical material. Prior to the present application, the excellent property of being bio-friendly because it is decomposed and absorbed in the living body without causing toxicity to the living body after the application was already noticed.

Conventionally, high-molecular-weight aliphatic polyhydroxycarboxylic acids have been prepared by ring-opening polymerization of cyclic dimers of aliphatic hydroxycarboxylic acids such as glycolide and lactide, and aliphatic hydroxycarboxylic acids such as lactic acid and glycolic acid. (US Pat. No. 5,310,8)
No. 65) and the like. In the case of ring-opening polymerization of a cyclic dimer of an aliphatic hydroxycarboxylic acid, the polymerization is usually performed in a molten state, and in the case of directly performing a dehydration polycondensation reaction of an aliphatic hydroxycarboxylic acid, the polymerization is usually performed in an organic solvent. The ring-opening polymerization method must use expensive lactide or the like obtained by a complicated production method, and the direct dehydration polycondensation method has a poor volumetric efficiency because it is a reaction in an organic solvent.

[0005] The method of obtaining an aliphatic polyhydroxycarboxylic acid by solid-phase polymerization is a simple, simple and high-volume efficiency method. The following method is disclosed as a method for solid-phase polymerization of an aliphatic hydroxycarboxylic acid. Japanese Patent Laid-Open No. 5-
No. 255488 (European Patent Publication EP-A-500)
No. 098), a homopolymer or copolymer of low molecular weight L- and / or D-lactic acid, which is a powder or a particle and has a crystallinity of 10% or more as measured by X-ray diffraction, is placed in an inert gas atmosphere or vacuum. Techniques for increasing the molecular weight by heating below the glass transition temperature of the polymer and below the melting temperature of the polymer are disclosed.
As a feature of the present invention, since the polymerization is carried out in the absence of a catalyst, it is possible to obtain a polymer containing no catalyst residue at all, and it is important to control the release of pharmaceuticals and to produce bioabsorbable prostheses. A functional polymer can be obtained. However, since no catalyst is used, it is not possible to obtain a polymer having a high molecular weight that can be used as a substitute for a general-purpose resin requiring toughness. Also, by the present inventors,
EP-953589A2 has a weight average molecular weight of 2,000.
A weight-average molecular weight of 50,000 to 1,000, which is obtained by solid-state polymerization of an aliphatic polyester prepolymer containing 50% or more of 0 to 100,000 crystallized aliphatic hydroxycarboxylic acid units in the presence of a catalyst. 000
Discloses a method for producing an aliphatic polyester containing at least 50% of an aliphatic hydroxycarboxylic acid unit, and the examples describe an example of solid-state polymerization with changing temperature. However, there is no mention of the effect of changing the temperature (particularly the prevention of fusion of the prepolymer).

[0006]

Accordingly, an object of the present invention is to provide an aliphatic hydroxycarboxylic acid such as lactic acid and glycolic acid, and an aliphatic polyhydric alcohol such as 1,4-butanediol and succinic acid. Inexpensive raw materials such as aliphatic polycarboxylic acids are polycondensed, and a prepolymer, which is an easily obtained low molecular weight aliphatic polyester, is used as a starting material, and the prepolymer is crystallized and then solidified in the presence of a catalyst. An object of the present invention is to provide a method for easily producing an aliphatic polyester having a high molecular weight as a substitute for a general-purpose resin requiring toughness by a polycondensation reaction in a phase with high volumetric efficiency.

Another object of the present invention is to change the solid-phase polymerization temperature during the solid-phase polymerization so that the solid-state polymerization can be performed without fusing the low-molecular-weight aliphatic polyester prepolymer. An object of the present invention is to provide a method for producing a high-molecular-weight aliphatic polyester which can be performed, and a method for producing an aliphatic polyester having excellent stability.

[0008]

That is, the present invention is specified by the following items [1] to [17].

[1] An aliphatic polyester prepolymer having a weight average molecular weight (Mw ₁ ) in the numerical range represented by the mathematical formula (1) and containing at least 50% of a crystallized aliphatic hydroxycarboxylic acid unit is prepared by using a catalyst in the presence of a catalyst. In the solid-phase polymerization below, the solid-state polymerization temperature (reaction temperature) is changed in the course of the solid-state polymerization, and the weight satisfying the numerical ranges indicated by the mathematical formulas (2) and (3) simultaneously. A solid phase polymerization method of an aliphatic polyester having an average molecular weight (Mw ₂ ) and containing 50% or more of an aliphatic hydroxycarboxylic acid unit. 2,000 ≦ Mw ₁ ≦ 100,000 (1) 50,000 ≦ Mw ₂ ≦ 1,000,000 (2) Mw ₁ <Mw ₂ (3)

[2] The method for solid-state polymerization of aliphatic polyester according to [1], wherein changing the solid-state polymerization temperature (reaction temperature) is increasing the temperature.

[3] Changing the solid-state polymerization temperature (reaction temperature) starts the solid-state polymerization at the solid-state polymerization temperature (reaction temperature) (T ₁ ) within the numerical range represented by the equation (4). And
The aliphatic according to [1], wherein the temperature is changed to a solid-state polymerization temperature (reaction temperature) (T ₂ ) in the numerical range represented by Expressions (5) and (6) during the solid-state polymerization. A method for solid phase polymerization of polyester. _{100 ℃ ≦ T 1 ≦ 130 ℃} (4) 120 ℃ ≦ T 2 <170 ℃ (5) T 1 <T 2 (6)

[4] Changing the solid-state polymerization temperature (reaction temperature) starts the solid-state polymerization at a solid-state polymerization temperature (reaction temperature) (T ₃ ) within the numerical range represented by the equation (7). And
During the solid-phase polymerization, the solid-state polymerization temperature (reaction temperature) (T ₄ ) within the numerical range shown by the mathematical formulas (8) and (10), and the numerical values shown by the mathematical formulas (9) and (10) The method for solid-state polymerization of aliphatic polyester according to [1], wherein the temperature is changed to a solid-state polymerization temperature (reaction temperature) (T ₅ ) within the range. _{100 ℃ ≦ T 3 ≦ 130 ℃} (7) 120 ℃ ≦ T 4 ≦ 160 ℃ (8) 140 ℃ ≦ T 5 <170 ℃ (9) T 3 <T 4 <T 5 (10)

[5] The catalyst is a volatile catalyst,
The method for solid-state polymerization of an aliphatic polyester according to any one of [1] to [4].

[6] The process for producing an aliphatic polyester according to [5], wherein the volatile catalyst has a catalyst residual ratio R of 50% or less as shown by the following equation (11). R [%] = C _A [ppm] ÷ C _B [ppm] × 100 (11) (In the formula (11), R is a catalyst residual ratio [%] which is a measure of a change in catalyst concentration before and after the solid-state polymerization reaction. And the C _B [ppm] is calculated by the formula (12), and the catalyst charged into the reaction system before the solid-state polymerization and / or during the solid-state polymerization reaction remains in the aliphatic polyester. Is the theoretical catalyst concentration in the case, and C _A [ppm] is the catalyst concentration in the aliphatic polyester finally obtained after the solid-state polymerization reaction, which is calculated by Expression (13).) C _B [ppm] = W in _{B [g] ÷ W P [} g] × 10 6 (12) ( equation _{(11), W B [g} ] is a solid phase prior to polymerization,
And / or the total weight of the catalyst charged into the reaction system during the solid-state polymerization reaction, and W _P [g] is
It is the weight of the aliphatic polyester finally obtained. ) C _A [ppm] = W _A [g] ÷ W _P [g] × 10 ⁶ (13) (In the formula (13), W _A [g] is finally obtained after the solid-state polymerization reaction is completed. and a catalyst weight contained in the aliphatic polyester, W _P [g] after solid-phase polymerization reaction was completed, the weight of the finally obtained aliphatic polyester.)

[7] The method for solid phase polymerization of an aliphatic polyester according to [5] or [6], wherein the volatile catalyst is an organic sulfonic acid compound.

[8] The organic sulfonic acid compound is methanesulfonic acid, ethanesulfonic acid, 1-propanesulfonic acid, benzenesulfonic acid, p-toluenesulfonic acid,
The method for solid-state polymerization of aliphatic polyester according to [7], which is at least one selected from the group consisting of m-xylene-4-sulfonic acid, p-chlorobenzenesulfonic acid, and 2,5-dichlorobenzenesulfonic acid.

[9] The catalyst concentration in the finally obtained aliphatic polyester is from 0 to 300 pp in terms of sulfur content.
m, the solid-state polymerization method of the aliphatic polyester according to [7] or [8].

[10] The catalyst is a nonvolatile catalyst,
The method for solid-state polymerization of an aliphatic polyester according to any one of [1] to [4].

[11] The method for solid-state polymerization of an aliphatic polyester according to [10], wherein the non-volatile catalyst is tin metal or tin (II) oxide.

[12] A crystallized aliphatic polyester prepolymer obtained by contacting a solid aliphatic polyester prepolymer with a liquid that does not dissolve the aliphatic polyester prepolymer, thereby crystallizing the aliphatic polyester prepolymer. The method for solid-phase polymerization of an aliphatic polyester according to [1], wherein

[13] The crystallized aliphatic polyester prepolymer is obtained by contacting the molten aliphatic polyester prepolymer with a liquid that does not dissolve the aliphatic polyester prepolymer, thereby solidifying and crystallizing the aliphatic polyester prepolymer. A method for solid-state polymerization of an aliphatic polyester according to [1], wherein

[14] The crystallized aliphatic polyester prepolymer is solidified and crystallized by bringing a solution in which the aliphatic polyester prepolymer is dissolved in a solvent into contact with a liquid in which the aliphatic polyester prepolymer is not dissolved. The solid-state polymerization method for an aliphatic polyester according to [1], which is obtained by the above method.

[15] The method for solid-state polymerization of an aliphatic polyester according to any one of [12] to [14], wherein the liquid contains water at least in part.

[16] The method for solid-state polymerization of aliphatic polyester according to [1] or [9], wherein the aliphatic polyester prepolymer is polylactic acid.

[17] The aliphatic polyester prepolymer is a star polymer comprising L-lactic acid, pentaerythritol and succinic acid, or a star polymer comprising L-lactic acid, trimethylolpropane and succinic acid. , [1] or [9].

[0026]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention relates to an aliphatic polyester prepolymer containing at least 50% of a crystallized aliphatic hydroxycarboxylic acid unit having a weight average molecular weight (Mw ₁ ) in the numerical range represented by the formula (1). Is characterized by changing the solid-state polymerization temperature (reaction temperature) during the solid-phase polymerization in the solid-state polymerization in the presence of a catalyst, to a numerical range represented by Expressions (2) and (3). This is a solid-state polymerization method of an aliphatic polyester containing a certain weight average molecular weight (Mw ₂ ) and 50% or more of an aliphatic hydroxycarboxylic acid unit.

2,000 ≦ Mw ₁ ≦ 100,000 (1)

50,000 ≦ Mw ₂ ≦ 1,000,000 (2)

Mw ₁ <Mw ₂ (3)

[Solid State Polymerization] In the method for producing an aliphatic polyester by solid state polymerization of the present invention, the aliphatic polyester prepolymer (hereinafter, referred to as prepolymer) crystallized in the presence of a catalyst is preferably used in a solid state. Is characterized by performing dehydration polycondensation (solid phase polymerization) under a flowing gas atmosphere. In the solid phase polymerization method of the present invention, the polymer (a prepolymer and an aliphatic polyester which is a reaction product) present in the reaction system substantially maintains a solid state, and the weight average of the aliphatic polyester after the solid phase polymerization is completed. The molecular weight (Mw) is not particularly limited as long as it is equal to or greater than the value of the weight average molecular weight (Mw) of the prepolymer before the start of solid phase polymerization. That is, according to the solid-state polymerization method of the present invention, the polymer (prepolymer and aliphatic polyester which is a reaction product) existing in the reaction system is maintained substantially in a solid state, and the weight of the prepolymer before the start of the solid-state polymerization is The average molecular weight (Mw ₁ ) is in the numerical range represented by the mathematical formula (1), and the weight average molecular weight (Mw ₂ ) of the aliphatic polyester after the solid phase polymerization is represented by the mathematical formulas (2) and (3). There is no particular limitation as long as the value is within the specified range.

2,000 ≦ Mw ₁ ≦ 100,000 (1)

50,000 ≦ Mw ₂ ≦ 1,000,000 (2)

Mw ₁ <Mw ₂ (3)

1. Catalyst in Solid State Polymerization In the solid state polymerization of the present invention, any of a volatile catalyst and a nonvolatile catalyst can be used as a catalyst. However, it is preferable to use a volatile catalyst that volatilizes from the reaction system during the reaction because the remaining amount of the catalyst in the produced aliphatic polyester is small.

Volatile Catalyst The volatile catalyst used in the present invention is not particularly limited as long as it substantially promotes the progress of the depolymerization polycondensation reaction of the prepolymer and has volatility. Here, the volatility of the catalyst refers to at least one reaction condition group in the solid-state polymerization, namely, a reaction condition group consisting of a reaction pressure, a reaction temperature, a reaction time, a flow rate of a flowing gas, and a particle diameter of a prepolymer. It means a function that can control the residual catalyst ratio R [%] calculated by the equation (11) to an arbitrary value within the numerical range shown by the equation (14) in relation to the condition.

0 [%] ≦ R [%] <100 [%] (14) (In the equation (14), R [%] is the catalyst concentration before and after the solid-state polymerization reaction calculated by the equation (11). The catalyst residual ratio [%], which is a measure of the change of the catalyst, is shown.)

R [%] = C _A [ppm] ÷ C _B [ppm] × 100 (11) (In the formula (11), R is a measure of the change in the catalyst concentration before and after the solid-state polymerization reaction. a rate _{[%], C B [ppm} ] is equation (12) is calculated by a solid phase prior to polymerization, and / or solid phase polymerization catalyst are all aliphatic polyester was charged to the reaction system during the reaction Is the theoretical catalyst concentration when remaining, and C _A [ppm] is the catalyst concentration in the aliphatic polyester finally obtained after the solid-state polymerization reaction, which is calculated by Expression (13). )

[0038] In _{C B [ppm] = W B} [g] ÷ W P [g] × 10 6 (12) ( Equation _{(12), W B [g} ] is a solid phase prior to polymerization,
And / or the total weight of the catalyst charged into the reaction system during the solid-state polymerization reaction, and W _P [g] is
It is the weight of the aliphatic polyester finally obtained. )

C _A [ppm] = W _A [g] ÷ W _P [g] × 10 ⁶ (13) (In the equation (13), W _A [g] is finally determined after the solid-state polymerization reaction is completed. The weight of the catalyst contained in the obtained aliphatic polyester, and W _P [g] is the weight of the finally obtained aliphatic polyester after the solid phase polymerization reaction.)

That is, by using a volatile catalyst in the method of the present invention, the catalyst concentration C _A [ppm] in the finally obtained aliphatic polyester after the solid phase polymerization reaction is completed.
Becomes smaller than the catalyst concentration C _B [ppm] represented by Expression (12). It can be said that the smaller the value of the catalyst residual ratio R [%] is, the more excellent the characteristics as a volatile catalyst are, and generally, a highly stable aliphatic aliphatic polyester is easily obtained.

The value of the residual catalyst ratio R [%] varies depending on the type, amount, reaction system and reaction conditions of the volatile catalyst.
The value of the residual catalyst ratio R [%] of the volatile catalyst used in the present invention is not particularly limited, but is generally the residual catalyst ratio R [%].
Is preferably 50% or less, more preferably 20% or less.

Specific examples of the volatile catalyst used in the present invention include, for example, organic sulfonic acid compounds. Specific examples of the organic sulfonic acid-based compound include, for example, methanesulfonic acid, ethanesulfonic acid, 1-propanesulfonic acid, 1-butanesulfonic acid, 1-pentanesulfonic acid, 1-hexanesulfonic acid, 1-heptanesulfonic, C1-C10 alkanesulfonic acid such as 1-octanesulfonic acid, 1-nonanesulfonic acid, 1-decanesulfonic acid, ethanedisulfonic acid, trifluoromethanesulfonic acid, 3-hydroxypropanesulfonic acid, sulfoacetic acid, taurine, aminomethane Substituted alkanesulfonic acids such as sulfonic acid, benzenesulfonic acid, p-toluenesulfonic acid, p-xylene-2-sulfonic acid, m-xylene-4-sulfonic acid, mesitylenesulfonic acid, p-
Chlorobenzenesulfonic acid, 2,5-dichlorobenzenesulfonic acid, o-nitrobenzenesulfonic acid, m-nitrobenzenesulfonic acid, p-nitrobenzenesulfonic acid, p-aminobenzenesulfonic acid, o-hydroxybenzenesulfonic acid, p-hydroxybenzenesulfonic Acid, benzenesulfonic acid and benzenesulfonic acid derivatives such as o-sulfobenzoic acid, and naphthalene such as naphthalene-1-sulfonic acid, naphthalene-2-sulfonic acid, 1,5-naphthalenedisulfonic acid and 2,5-naphthalenedisulfonic acid Sulfonic acid and naphthalene sulfonic acid derivatives, camphorsulfonic acid, 4-hydroxypyridine-3-sulfonic acid, and the like can be mentioned. Also, acid anhydrides of these organic sulfonic acids can be used. Among these, methanesulfonic acid, ethanesulfonic acid, 1-propanesulfonic acid, benzenesulfonic acid, p-toluenesulfonic acid, m-xylene-4-sulfonic acid, p-chlorobenzenesulfonic acid, 2,5-dichlorobenzene Sulfonic acid is particularly preferred. These can be used alone or in combination of two or more. Some types of the organic sulfonic acids have water of crystallization. In this case, when the catalyst is added, reduction of the weight average molecular weight of the aliphatic polyester obtained by the water of crystallization may need to be considered. When the weight average molecular weight (Mw) of the prepolymer is 1,000 or less, the catalyst may be added with water of crystallization, but when the weight average molecular weight (Mw) of the prepolymer exceeds 1,000, As the weight average molecular weight (Mw) increases, the weight average molecular weight of the aliphatic polyester obtained tends to decrease due to the water of crystallization of the catalyst. Therefore, it is more preferable to remove the water of crystallization of the catalyst before adding the catalyst, This is preferable because it does not hinder the progress of the reaction.

Amount of Volatile Catalyst Used In the present invention, the amount of the volatile catalyst used is to substantially promote the reaction in consideration of the properties of the catalyst itself such as the volatility of the catalyst and the acid strength, and the reaction conditions. There is no particular limitation if it is possible. The preferred amount of the volatile catalyst varies depending on the type of the catalyst used, but is generally preferably in the range of 0.05 to 10% by weight of the obtained aliphatic polyester,
The range of 0.10 to 5% by weight is more preferable.

Nonvolatile Catalyst The nonvolatile catalyst used in the present invention is not particularly limited as long as it substantially promotes the progress of the solid-state polymerization reaction. Specific examples of the catalyst include, for example, metals of Groups II, III, IV, and V of the periodic table, oxides thereof, and salts thereof. More specifically, metals such as zinc powder, tin powder, aluminum, magnesium, and germanium, tin (II) oxide, antimony (III) oxide, zinc oxide, aluminum oxide, magnesium oxide, titanium oxide (IV), and germanium oxide (I
V) and other metal oxides, tin (II) chloride, tin (IV) chloride, tin (II) bromide, tin (IV) bromide, antimony fluoride (II)
I), metal halides such as antimony (V) fluoride, zinc chloride, magnesium chloride, and aluminum chloride; sulfates such as tin (II) sulfate, zinc sulfate and aluminum sulfate; carbonates such as magnesium carbonate and zinc carbonate; Borates such as zinc borate; organic carboxylates such as tin (II) acetate, tin (II) octoate, tin (II) lactate, zinc acetate and aluminum acetate; tin (II) trifluoromethanesulfonate; Zinc methanesulfonate, magnesium trifluoromethanesulfonate, tin (II) methanesulfonate, p-
Organic sulfonates such as tin (II) toluenesulfonate and the like.

Other examples include organic metal oxides of the above metals such as dibutyltin oxide or metal alkoxides of the above metals such as titanium isopropoxide.
Alternatively, an alkyl metal of the above metals such as diethyl zinc and the like can be mentioned. Among these, tin powder (metal tin), tin oxide (I
I) and the like are preferred. These can be used alone or in combination of two or more.

Use Amount of Non-Volatile Catalyst The use amount of the non-volatile catalyst is not particularly limited as long as it substantially accelerates the reaction rate. The amount of non-volatile catalyst used depends on the type of catalyst used,
Generally, 0.000 of the resulting aliphatic polyester
The range is preferably from 05 to 5% by weight, and more preferably from 0.0001 to 1% by weight in consideration of economy.

2. Reaction temperature in solid-phase polymerization The reaction temperature in solid-phase polymerization is not particularly limited as long as the polymer (prepolymer and aliphatic polyester as a reaction product) existing in the reaction system substantially maintains a solid state. It is preferable that the temperature is 100 ° C. or higher and lower than the melting point (Tm). In general, the higher the solid phase polymerization temperature (reaction temperature), the faster the polymerization rate, and it is preferable from the viewpoint of efficiency to carry out the polymerization at a temperature below the melting point and as high as possible,
Since the molecular weight of the prepolymer is relatively low, it is difficult to carry out solid-state polymerization at a high temperature from the beginning, and the phenomenon that the prepolymers fuse together even if they do not melt is often seen. On the other hand, the Tm of the polymer increases in proportion to the molecular weight, the degree of crystallinity, and the like.
As in (Method 2), it is preferable to carry out solid-state polymerization at a relatively low temperature at the beginning of polymerization, and to raise the polymerization temperature when the molecular weight and the degree of crystallinity increase to some extent. By such a method, the fusion of the prepolymers is prevented, and the solid phase polymerization can be smoothly performed in the moving bed reactor.

(Method 1) Solid-state polymerization is started at a solid-state polymerization temperature (reaction temperature) (T ₁ ) within the numerical range shown by the equation (4), and during the solid-state polymerization, the equation (5) And the solid-state polymerization temperature (reaction temperature) within the numerical range represented by Equation (6)
(T ₂ ).

100 ° C. ≦ T ₁ ≦ 130 ° C. (4)

120 ° C. ≦ T ₂ <170 ° C. (5)

T ₁ <T ₂ (6)

(Method 2) Solid-state polymerization is started at a solid-state polymerization temperature (reaction temperature) (T ₃ ) within the numerical range shown by the equation (7), and during the solid-state polymerization, the equation (8) And the solid-state polymerization temperature (reaction temperature) in the numerical range represented by Equation (10)
(T ₄ ) and the solid-state polymerization temperature (reaction temperature) (T ₅ ) within the numerical ranges shown by Expressions (9) and (10).

100 ° C. ≦ T ₃ ≦ 130 ° C. (7)

120 ° C. ≦ T ₄ ≦ 160 ° C. (8)

140 ° C. ≦ T ₅ <170 ° C. (9)

T ₃ <T ₄ <T ₅ (10)

When a volatile catalyst is used as the catalyst, generally, the higher the solid phase polymerization temperature (reaction temperature), the higher the volatility of the catalyst. From the viewpoint of the amount of the catalyst remaining in the aromatic polyester, it is preferable that the solid phase polymerization temperature is higher, and by increasing the solid phase polymerization temperature (reaction temperature) as in the above (method 1) or (method 2), And a highly stable aliphatic polyester is easily obtained. Stability includes thermal stability, wet heat resistance, etc., and thermal stability is evaluated by the change in weight average molecular weight when a press film is made from an aliphatic polyester. The film is left in an environment of 50 ° C. and 80% humidity for 6 days, and evaluated by a change in weight average molecular weight before and after the test.

3. When performing solid-phase polymerization in a flowing gas atmosphere The solid-phase polymerization of the present invention is preferably performed in a flowing gas atmosphere in order to remove water generated by the polymerization. The flowing gas used in the solid-phase polymerization of the present invention, that is, specific examples of the gas flowing through the reaction system include, for example, an inert gas such as a nitrogen gas, a helium gas, an argon gas, a xenon gas, a krypton gas, and a dry gas. Air and the like can be mentioned. Among them, an inert gas is preferable.

The water content of the flowing gas is as low as possible and is preferably substantially anhydrous.
If the water content is large, water generated by the solid-state polymerization reaction cannot be efficiently removed, so that the polymerization rate is undesirably reduced. In this case, the gas can be used after being dehydrated by passing the gas through a layer filled with molecular sieves or ion exchange resins. When the water content of the flowing gas is indicated by a dew point, the dew point of the gas is preferably −20 ° C. or less, and −50 ° C.
It is more preferred that:

The flow rate of the flowing gas is determined in consideration of the polymerization rate, the type and amount of the volatile catalyst used when a volatile catalyst is used as the catalyst, and the rate of volatilization of the volatile catalyst from the reaction system.
There is no particular limitation as long as the generated water can be removed to such an extent that an aliphatic polyester having a sufficiently high weight average molecular weight can be obtained.

The effect of flowing the flowing gas through the reaction system is as follows.
Water produced by the solid-state polymerization reaction can be efficiently removed to the outside of the system, whereby an aliphatic polyester having a sufficiently high weight average molecular weight can be efficiently obtained. The flow rate of the flowing gas depends on the polymerization rate, the type and amount of volatile catalyst used when a volatile catalyst is used as the catalyst, the rate and efficiency at which the volatile catalyst is volatilized from the aliphatic polyester during the dehydration polycondensation reaction. It is set in consideration of the speed and efficiency of removing water generated by the solid-phase polymerization reaction, the attained weight average molecular weight (Mw), and the like.

In general, the larger the flow rate of the flowing gas, the more efficiently water generated in the solid-state polymerization reaction can be removed. On the other hand, when a volatile catalyst is used as a catalyst, the water in the solid-state polymerization reaction can be reduced. Since the volatilization rate of the volatile catalyst is increased from the aliphatic polyester, when an aliphatic polyester having a high weight-average molecular weight (for example, Mw = 5 × 10 ⁴ to 1 × 10 ⁶ ) is expected, a solid-phase polymerization reaction is required. In at least a part of the process, it is necessary to suppress the flow rate of the flowing gas to a certain level.

Usually, a high weight average molecular weight (for example, Mw
= 5 × 10 ⁴ to 1 × 10 ⁶ ), the flow rate of the flowing gas per 1 g of the prepolymer is preferably 0.02 to 200 [ml / min], preferably 0.5 to 200 [ml / min]. -150 [ml / min] is more preferable.
0-100 [ml / min] is more preferable. Generally, the flow rate of the flowing gas per 1 g of the prepolymer is 0.
When the concentration is less than 02 [ml / min], the efficiency of removing generated water in the solid-state polymerization reaction is remarkably deteriorated, and a fat having a high weight average molecular weight (for example, Mw = 5 × 10 ⁴ to 1 × 10 ⁶ ) is used. Group polyester cannot be obtained. Expressed in linear velocity,
It is preferably 0.01 to 500 [cm / sec].

4. When performing solid-phase polymerization under reduced pressure When performing solid-state polymerization under reduced pressure, the degree of reduced pressure in the reaction system is substantially high while maintaining the progress of the solid-state polymerization reaction, a sufficiently high weight average molecular weight (for example, There is no particular limitation as long as an aliphatic polyester having Mw = 5 × 10 ⁴ to 1 × 10 ⁶ ) is obtained. When performing solid-state polymerization under reduced pressure, the degree of reduced pressure in the reaction system, the polymerization rate, the type and amount of volatile catalyst, the volatile catalyst is volatilized from the aliphatic polyester in the process of the solid-phase polymerization reaction It is set in consideration of the speed and efficiency, the speed and efficiency of removing water generated by the dehydration polycondensation reaction, the attained weight average molecular weight (Mw), and the like.

5. When Solid Phase Polymerization is Performed Under Pressure When solid phase polymerization is performed under pressure, the pressure in the reaction system is substantially high while maintaining the progress of the solid phase polymerization reaction, and a sufficiently high weight average molecular weight (for example, Mw = 5 × 10 ⁴ to 1 × 10 ⁶ ), as long as an aliphatic polyester having the same can be obtained. When performing solid state polymerization under pressure, the pressure in the reaction system is
Polymerization rate, type and amount of volatile catalyst used, rate and efficiency of volatile catalyst volatilizing from aliphatic polyester during solid phase polymerization reaction, rate and efficiency of removing water generated by dehydration polycondensation reaction , Reached weight average molecular weight (M
w) and so on. Generally, when the solid-phase polymerization is performed under pressure, the used volatile catalyst is less likely to volatilize from the reaction system than under normal pressure.

[Step of Producing Prepolymer] A prepolymer containing 50% or more of an aliphatic hydroxycarboxylic acid unit and having a weight average molecular weight (Mw ₁ ) represented by the formula (1), which is used in the solid phase polymerization of the present invention. There are also the following types.

2,000 ≦ Mw ₁ ≦ 100,000 (1)

A homopolymer or copolymer of an aliphatic polyhydroxycarboxylic acid obtained from an aliphatic hydroxycarboxylic acid or a mixture thereof.

A copolymer of an aliphatic polyhydroxycarboxylic acid, an aliphatic polyester comprising an aliphatic dihydric alcohol and an aliphatic dibasic acid, or a mixture thereof.

[0070] Copolymers or mixtures of aliphatic polyhydroxycarboxylic acids and polysaccharides.

Copolymers of aliphatic polyhydroxycarboxylic acids, polysaccharides, aliphatic dihydric alcohols and aliphatic polyesters composed of aliphatic dibasic acids or mixtures thereof.

A star polymer comprising an aliphatic hydroxycarboxylic acid, an aliphatic polyhydric alcohol having three or more hydroxyl groups, an aliphatic polybasic acid having two or more carboxyl groups, and / or an anhydride thereof.

A star polymer comprising an aliphatic hydroxycarboxylic acid, an aliphatic polybasic acid having three or more carboxyl groups and / or an anhydride thereof, and an aliphatic polyhydric alcohol having two or more hydroxyl groups.

The aliphatic hydroxycarboxylic acid for producing the prepolymer is not particularly limited.
Preferred specific examples include, in addition to lactic acid, glycolic acid, 3-hydroxybutyric acid, 4-hydroxybutyric acid, 4-hydroxyvaleric acid, 5-hydroxyvaleric acid, 6-hydroxycaproic acid and the like. These hydroxycarboxylic acids may be used alone or in combination of two or more. In the case where the molecule has an asymmetric carbon atom such as lactic acid, D-form, L-form, and an equivalent mixture thereof (racemic body) exist, but the obtained prepolymer polymer has poor crystallinity. If so, any of them can be used. Among them, L-lactic acid produced by a fermentation method having an optical purity of 95% or more, preferably 98% or more, is particularly preferred.

The aliphatic dihydric alcohol for producing the above prepolymer is not particularly limited. Suitable specific examples include, for example, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, 1,3-butanediol, 1,4-butanediol, 3-methyl-1,5-pentanediol, , 6-hexanediol, 1,7-
Heptanediol, 1,8-octanediol, 1,9
-Nonanediol, neopentyl glycol, 1,4-
Cyclohexane dimethanol and the like. These can be used alone or in combination of two or more. When the compound has an asymmetric carbon in the molecule, the D-form,
There are L-forms and equal mixtures (racemates) thereof, any of which can be used.

The aliphatic dibasic acid for producing the above prepolymer is not particularly limited. Specific examples of the aliphatic dibasic acid include, for example, succinic acid, oxalic acid, malonic acid, glutanic acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecandioic acid, dodecandioic acid, 3, Examples thereof include aliphatic dicarboxylic acids such as 3-dimethylpentanedioic acid and alicyclic dicarboxylic acids such as cyclohexanedicarboxylic acid. These can be used alone or
Two or more types can be used in combination. Also,
When the compound has an asymmetric carbon atom in the molecule, a D-form, an L-form and an equivalent mixture thereof (racemic form) exist, and any of them can be used.

The polysaccharide for producing the prepolymer is not particularly limited. Specific examples of polysaccharides include, for example, regenerated cellulose such as cellulose, cellulose nitrate, cellulose acetate, methyl cellulose, ethyl cellulose, CMC (carboxymethyl cellulose), nitrocellulose, cellophane, viscose rayon, cupra, hemicellulose, starch, amylopectin, dextrin, Dextran, glycogen, pectin, chitin, chitosan, and the like, and mixtures thereof and derivatives thereof. Of these, particularly preferred are cellulose acetate, which is an esterified cellulose, and ethyl cellulose, which is an etherified cellulose. The weight average molecular weight of the polysaccharide is 3,000
0 or more is preferable, and 10,000 or more is more preferable.
The substitution degree of the esterified cellulose and the etherified cellulose is preferably 0.3 to 3.0, and 1.0 to 3.0.
It is preferably 2.8.

The aliphatic polyhydric alcohol having 2 to 3 or more hydroxyl groups for producing the above prepolymer is not particularly limited. Specific examples of the aliphatic polyhydric alcohol having two to three or more hydroxyl groups include:
In addition to the above aliphatic dihydric alcohols, for example, glycerin, pentaerythritol, dipentaerythritol,
Examples include aliphatic polyhydric alcohols having three or more hydroxyl groups, such as trimethylolethane, trimethylolpropane, and inositol. These can be used alone or in combination of two or more. When the compound has an asymmetric carbon atom in the molecule, there are a D-form, an L-form and an equivalent mixture thereof (racemic form), and any of them can be used.

The aliphatic polybasic acid having 2 to 3 or more carboxyl groups for producing the above prepolymer is not particularly limited. Specific examples of the aliphatic polybasic acid having two to three or more carboxyl groups include, in addition to the above-mentioned aliphatic dibasic acids, for example, 1, 2, 3, 4,
5,6-cyclohexanehexacarboxylic acid, 1,2,2
3,4-cyclopentanetetracarboxylic acid, tetrahydrofuran 2R, 3T, 4T, 5C-tetracarboxylic acid,
1,2,3,4-cyclobutanetetracarboxylic acid, 4-
Carboxy-1,1-cyclohexanediacetic acid, 1,3
5-cyclohexanetricarboxylic acid, (1α, 3α, 5
β) cyclic compounds such as 1,3,5-trimethyl-1,3,5-cyclohexanetricarboxylic acid, 2,3,4,5-furantetracarboxylic acid and anhydrides thereof, butane-
1,2,3,4-tetracarboxylic acid, meso-butane-1,2,3,4-tetracarboxylic acid, 1,3,5-pentanetricarboxylic acid, 2-methylpropanetricarboxylic acid, 1,2,3 -Propanetricarboxylic acid, 1,1,
Examples thereof include aliphatic polybasic acids having three or more carboxyl groups, such as linear compounds such as 2-ethanetricarboxylic acid and 1,2,4-butanetricarboxylic acid and anhydrides thereof.
Among aliphatic polybasic acids having three or more carboxyl groups, linear compounds and anhydrides thereof are preferred. They are,
They can be used alone or in combination of two or more. When the compound has an asymmetric carbon atom in the molecule, there are a D-form, an L-form and an equivalent mixture thereof (racemic form), and any of them can be used.

The prepolymer is preferably an aliphatic hydroxycarboxylic acid or an aliphatic polycarboxylic acid having an aliphatic hydroxycarboxylic acid, an aliphatic polyhydric alcohol having three or more hydroxyl groups, and an aliphatic polybasic acid having two or more carboxyl groups. Or an aliphatic hydroxycarboxylic acid, an aliphatic polybasic acid having three or more carboxyl groups and an aliphatic polyhydric alcohol having two or more hydroxyl groups by a dehydration polycondensation reaction.

In the process of producing an aliphatic polyhydroxycarboxylic acid by subjecting an aliphatic hydroxycarboxylic acid to a dehydration polycondensation reaction, the prepolymers (a) and (b) can be used as other aliphatic hydroxycarboxylic acids or aliphatic dicarboxylic acids. Aliphatic polyester consisting of a dihydric alcohol and an aliphatic dibasic acid,
Alternatively, it is obtained by mixing or copolymerizing polysaccharides.
As the prepolymer used in the solid phase polymerization of the present invention,
And the prepolymers of are preferred.

As the prepolymer, polylactic acid using lactic acid as a raw material is more preferable, and poly L-lactic acid is particularly preferable.

As the prepolymer, a star polymer composed of L-lactic acid, pentaerythritol and succinic acid or a star polymer composed of L-lactic acid, trimethylolpropane and succinic acid is particularly preferred.

In the above prepolymer, an aliphatic polyhydric alcohol having three or more hydroxyl groups, an aliphatic polybasic acid having two or more carboxyl groups and / or an acid anhydride thereof, and three or more carboxyl groups The composition of an aliphatic polybasic acid and / or an acid anhydride thereof and an aliphatic polyhydric alcohol having two or more hydroxyl groups is as follows. That is, the weight of the aliphatic polyhydric alcohol having three or more hydroxyl groups and the weight of the aliphatic polybasic acid having three or more carboxyl groups and / or the acid anhydride thereof are completely different from those of the aliphatic hydroxycarboxylic acid alone. 0.005 to 10 based on the weight of the polymer assuming polymerization
%, Preferably 0.01 to 5%,
And an equivalent ratio of a hydroxyl group of an aliphatic polyhydric alcohol having three or more hydroxyl groups and a carboxyl group of an aliphatic polybasic acid having two or more carboxyl groups and / or an acid anhydride thereof, and three or more carboxyl groups The equivalent ratio of the carboxyl group of the aliphatic polybasic acid having a group and / or the acid anhydride thereof to the hydroxyl group of the aliphatic polyhydric alcohol having two or more hydroxyl groups is 100: 50 to 200, preferably 100: 8.
0 to 120, more preferably 100: 90 to 110.

The method for producing the prepolymer by the dehydration polycondensation reaction includes a melt polymerization method and a solution polymerization method using an organic solvent. The method may be appropriately selected depending on the desired weight average molecular weight (Mw) and the simplicity of the operation. A known reaction method is selected and used. For example, the melt polymerization method described in JP-A-59-96123, U.S. Pat. Nos. 5,310,865, 5,401,796, 5,817,728 and European Patent Publication EP0829503-A. A method according to the described solution polymerization method is used.

When a catalyst is used in the production of the prepolymer, the volatile catalyst and the nonvolatile catalyst used in the solid phase polymerization can be used as they are. Generally, a solution polymerization method using an organic solvent can efficiently obtain a prepolymer having a weight average molecular weight of 15,000 or more. Further, in the case of dehydration polycondensation of lactic acid, the use of a solution polymerization method has a feature that it is possible to prevent clogging of a condenser portion due to crystallization of lactide produced as a by-product. On the other hand, the melt polymerization method that does not use an organic solvent has a feature that the operation is simple because the labor for distilling off the organic solvent can be omitted.

However, as in the melt polymerization method described in JP-A-59-96123, dehydration polycondensation of an aliphatic hydroxycarboxylic acid having an asymmetric carbon atom such as lactic acid at a high reaction temperature of 220 to 260 ° C. When the reaction is performed, the optical purity of the obtained prepolymer decreases, and the moldability of the aliphatic polyester obtained by solid-phase polymerization deteriorates. Therefore, it is preferable that the aliphatic hydroxycarboxylic acid having an asymmetric carbon atom such as lactic acid is subjected to dehydration polycondensation under the following reaction conditions.

That is, as a first step, an aliphatic hydroxycarboxylic acid containing 50% by weight or more of an aliphatic hydroxycarboxylic acid having an asymmetric carbon atom or an oligomer thereof is dissolved in an organic solvent in the presence or absence of a catalyst. _A step of producing an aliphatic hydroxycarboxylic acid oligomer having a weight average molecular weight Mw _A represented by Formula (18) by dehydration condensation at a reaction temperature RT ₁ represented by Formula (15) in the presence or absence thereof As a second step, the aliphatic hydroxycarboxylic acid oligomer produced in the first step is expressed by the formula (1)
6) and dehydration condensation at a reaction temperature RT ₂ represented by equation (17), to produce the aliphatic hydroxycarboxylic acid prepolymer having a weight average molecular weight Mw _B represented by the formula (19) and Equation (20) And a process for producing an aliphatic polyhydroxycarboxylic acid prepolymer.

50 ° C. ≦ RT ₁ ≦ 140 ° C. (15)

130 ° C. ≦ RT ₂ ≦ 170 ° C. (16)

RT ₁ <RT ₂ (17)

750 ≦ Mw _A ≦ 5,000 (18)

2,000 ≦ Mw _B ≦ 20,000 (19)

Mw _A <Mw _B (20) Aliphatic hydroxycarboxylic acid 50 having an asymmetric carbon atom
% Or more of the aliphatic hydroxycarboxylic acid or oligomer thereof is composed of an aliphatic polyhydric alcohol having three or more hydroxyl groups and an aliphatic polybasic acid having two or more carboxyl groups or an anhydride thereof, or three or more. The above-mentioned aliphatic polybasic acid having a carboxyl group or an anhydride thereof and an aliphatic polyhydric alcohol having two or more hydroxyl groups can be contained. As a result, an aliphatic polyester star polymer having a high melt tension can be obtained. In particular, the aliphatic hydroxycarboxylic acid is L-lactic acid, the aliphatic polyhydric alcohol having three or more hydroxyl groups is pentaerythritol or trimethylolpropane, and the aliphatic polybasic acid having two or more carboxyl groups or Preferably, the anhydride is succinic acid or succinic anhydride.

An aliphatic polyhydric alcohol having three or more hydroxyl groups, an aliphatic polybasic acid having two or more carboxyl groups and / or an acid anhydride thereof, and an aliphatic polybasic having three or more carboxyl groups The composition of an acid and / or an acid anhydride thereof and an aliphatic polyhydric alcohol having two or more hydroxyl groups is as follows. That is, the weight of the aliphatic polyhydric alcohol having three or more hydroxyl groups and the weight of the aliphatic polybasic acid having three or more carboxyl groups and / or the acid anhydride thereof are completely different from those of the aliphatic hydroxycarboxylic acid alone. Based on the weight of the polymer assuming polymerization,
It is equivalent to 0.005 to 10%, preferably 0.01 to 5%, and has a hydroxyl group of an aliphatic polyhydric alcohol having three or more hydroxyl groups and an aliphatic polyhydric alcohol having two or more carboxyl groups. Equivalent ratio of carboxyl group of basic acid and / or acid anhydride thereof, and aliphatic polybasic acid having three or more carboxyl groups and / or aliphatic acid having carboxyl group of acid anhydride and two or more hydroxyl groups The equivalent ratio of the hydroxyl groups of the polyhydric alcohol is 100: 50 to 200, preferably 100: 80 to 120, and more preferably 100: 80.
This corresponds to 90 to 110. When the weight of the aliphatic polyhydric alcohol having three or more hydroxyl groups and the aliphatic polybasic acid having three or more carboxyl groups and / or the anhydride thereof is less than 0.005%, after solid-state polymerization, The melt tension of the aliphatic polyester tends to be insufficient, and when it exceeds 10%, the aliphatic polyester after solid-phase polymerization tends to be brittle.

The equivalent ratio of the aliphatic polyhydric alcohol having three or more hydroxyl groups to the aliphatic polybasic acid having two or more carboxyl groups and / or the carboxyl group of an acid anhydride thereof, and three or more A carboxyl group of an aliphatic polybasic acid having a carboxyl group and / or an acid anhydride thereof;
When the equivalent ratio of the hydroxyl group of the aliphatic polyhydric alcohol having at least two hydroxyl groups is out of the above range, the melt tension of the aliphatic polyester after the solid phase polymerization becomes insufficient, or the molecular weight of the aliphatic polyester during the solid state polymerization. , And there is a tendency that it is difficult to select an aliphatic polyester having practical strength.

(1) First Step In this step, the reaction conditions are not particularly limited, except that the dehydration polycondensation reaction is performed in a relatively low temperature range shown in the formula (15). When a catalyst is used in this step, those used in solid phase polymerization are used as they are. When an organic solvent is used, the solvent described in US Pat. No. 5,310,865 can be used as it is. The reaction is preferably performed under an inert gas atmosphere and / or under reduced pressure. In addition, reaction conditions can be appropriately selected, for example, using an organic solvent depending on a desired molecular weight and simplicity of operation. For example, when lactic acid is subjected to dehydration polycondensation reaction as an aliphatic hydroxycarboxylic acid having an asymmetric carbon atom, when an organic solvent is used, lactide, which is a cyclic dimer of lactic acid generated by an equilibrium reaction with the obtained oligomer, is used. This is effective in that the clogging of a pipe connected to a condenser or the like in the reactor due to condensation and crystallization can be easily prevented. Conversely, when an organic solvent is not used, the operation for separating the oligomer obtained after the reaction from the organic solvent can be omitted, so that the operation is simple.

The molecular weight of the oligomer obtained in this step is 750 to 2,000 in weight average molecular weight, more preferably 1,000 to 2,000, and 1,5 to 2,000.
00 to 2,000 is most preferred. Weight average molecular weight (M
If w) is less than 750, the temperature must be increased in the subsequent second step to proceed the polycondensation reaction, and it becomes difficult to suppress racemization of the aliphatic hydroxycarboxylic acid having an asymmetric carbon atom. The optical purity of the aliphatic hydroxycarboxylic acid oligomer as the prepolymer obtained in the second step is undesirably reduced. In addition, the weight average molecular weight is 2,
If more than 000 are to be obtained in the first step,
Although the decrease in the optical purity of the obtained oligomer is suppressed, a problem that the polymerization time is prolonged is not preferred.
In order to increase the molecular weight by continuing the polymerization in this temperature range, it is necessary to increase the catalyst addition amount or set the reaction system under severe conditions such as under a high vacuum (for example, under a high vacuum of 5 mmHg or less). Therefore, the operation of removing the catalyst from the prepolymer becomes complicated, and a special device is required to maintain a high vacuum, which is industrially disadvantageous and is not preferable.

(2) Second Step The second step is a step of increasing the molecular weight in a short time from the oligomer obtained in the first step to obtain an aliphatic hydroxycarboxylic acid prepolymer having a desired molecular weight. Condensation conditions are not particularly limited, as long as the polycondensation reaction is carried out in the same manner as in the first step, except that the temperature range is within the ranges shown in Formulas (16) and (17). Regarding the temperature conditions, it is not preferable that the temperature is lower than 130 ° C. because the reaction rate becomes low. When the reaction temperature is higher than 170 ° C., the rate is increased but the decrease in optical purity due to the racemization of the aliphatic hydroxycarboxylic acid component having an asymmetric carbon atom of the obtained prepolymer becomes large, or the prepolymer is colored. It is not preferable because of the tendency.

(3) Molecular Weight of Aliphatic Hydroxycarboxylic Acid Prepolymer The weight average molecular weight (Mw) and molecular weight distribution of the aliphatic hydroxycarboxylic acid prepolymer depend on the reaction conditions such as the type and amount of the catalyst, the reaction temperature and the reaction time. By appropriate selection, it can be controlled to a desired one. According to this method, an aliphatic hydroxycarboxylic acid prepolymer having a weight-average molecular weight (Mw) of 20,000 or less can be suitably produced.
w _B ) It is possible to suitably obtain those having a range of 2,000 to 20,000. Weight average molecular weight (Mw) of 2
Although it is possible to obtain those exceeding 000 by the method of the present invention, the aliphatic hydroxycarboxylic acid prepolymer obtained or the aliphatic polyhydroxycarboxylic acid obtained by solid-phase polymerization using the same is obtained. It is not preferable because it tends to be colored.

[Method of Crystallizing Prepolymer] The reaction mixture (prepolymer) obtained by the dehydration polycondensation reaction is solidified, and the solid prepolymer is crystallized.

1. Solidification of prepolymer The method for obtaining a solid prepolymer is not particularly limited, but depends on whether or not an organic solvent is used in the prepolymer production step by a dehydration polycondensation reaction, the crystallinity of the prepolymer, and the amount of the prepolymer. Selected as appropriate. As a method for solidifying the prepolymer, for example, when an organic solvent is used in the production process of the prepolymer, the organic solvent may be distilled off. In particular, when the amount of the organic solvent used is small (for example, when the concentration of the prepolymer is 90% or more), it can be directly contacted with a liquid such as water to be solidified. If no organic solvent is used in the prepolymer production process,
It can be solidified by a simple cooling method or by contact with a liquid such as water. Further, in order to obtain a solid prepolymer having a desired shape (eg, powder, granule, granule, pellet, etc.) and particle size, the following appropriate treatment may be performed in some cases.

Method for Obtaining Powdered Solid Prepolymer The method for obtaining the powdered solid prepolymer is not particularly limited. For example, when a solvent is used in a dehydration polycondensation reaction, the prepolymer is crystallized from a solution. By doing so, a powdery prepolymer can be obtained.

Method for Obtaining Particulate or Pellet-Shaped Solid Prepolymer The method for obtaining the particulate or pellet-shaped solid prepolymer is not particularly limited. By bringing the solution or melt into contact with a liquid such as water, a solid prepolymer in the form of particles or pellets can be obtained. A method of contacting a prepolymer in a molten state or a solution state with a liquid such as water,
It is not limited at all. For example, when the prepolymer melt is dropped into water and solidified, spherical pellets are obtained. In this case, after the prepolymer is solidified by contact with a liquid such as water, it can be crystallized as it is in a crystallization step described later.

Further, the prepolymer obtained by the dehydration polycondensation reaction can be transferred to an extruder and pelletized, or can be pelletized while distilling off the organic solvent in the extruder. Pellet production equipment is not particularly limited, for example, Sandvik strip former, rotoformer, double roll feeder, Kaiser rotary dropformer, and piston type dropformer, Mitsubishi Examples include a drum cooler manufactured by Kasei Engineering Co., Ltd., a steel belt cooler manufactured by Nippon Belding Co., Ltd., and a hybrid former. The apparatus for generating a melt droplet of a prepolymer such as polylactic acid and the apparatus for generating a solution droplet are not particularly limited, but specific examples thereof include a Kaiser Inc. pastilator. The shape of the pellets and the shape of the particles are not particularly limited. The pellet shape or the grain shape does not need to be a specific shape such as a crushed shape, a chip shape, a spherical shape, a cylindrical shape, a marble shape, a tablet shape, but generally, a spherical shape, a cylindrical shape, or a marble shape is preferable.

Particle Size of Solid Prepolymer The particle size of the solid prepolymer is not particularly limited. The particle size of the solid prepolymer is set in consideration of operability in a step such as a solid phase polymerization step, and a rate and efficiency at which a volatile catalyst evaporates in the solid phase polymerization step.
In particular, the particle size is set so that the volatility of the volatile catalyst is sufficiently exhibited. in this way. In consideration of the surface area per unit weight of the solid prepolymer so that the volatility of the catalyst is sufficiently exhibited, it is generally preferable that the particle diameter of the solid prepolymer is 10 μm to 10 mm. , 0.1 mm to 10 mm is more preferable,
1 mm to 5 mm is more preferable.

Addition of Polymerization Catalyst in Step of Producing Solid Prepolymer In the step of producing a solid prepolymer, a catalyst used in the solid phase polymerization step may be added. The method for adding the catalyst is not particularly limited. Since it is preferable to uniformly disperse the catalyst in the prepolymer, specific examples thereof include, for example, adding a catalyst when pulverizing a lump of prepolymer or adding a catalyst when pelletizing. it can.

2. Prepolymer Crystallization Method The solidified prepolymer is crystallized by the above method. In the present invention, crystallization is measured by a differential scanning calorimeter (DSC) measurement (measurement conditions; sample weight = 5 mg, temperature conditions = 20 ° C. to 200 ° C., heating rate = 10 ° C./min). This means that a solid having a heat of crystallization of 30 [J / g] or less is obtained. The method for crystallizing the prepolymer is not particularly limited. Conventionally known various methods such as heating a solid prepolymer in a gas phase can be used, but a method of contacting with a liquid according to the present invention is preferable. JP-A-8-34843 describes that low molecular weight aliphatic polyesters are brittle and have problems such as breakage of pellets and generation of powder during melt pelletization.
Therefore, the method described below, in which the solid prepolymer of the present invention is brought into contact with a liquid and crystallized, solves such a problem, can prevent the fusion of the prepolymer, and can be performed at a low temperature and a short time. Can be said to be an excellent method because crystallization is possible.

Crystallization Method In the present invention, the method for bringing the prepolymer into contact with the liquid is not particularly limited. For example, when the prepolymer is a solid, the solid prepolymer may be charged into a liquid and brought into contact with the liquid, or conversely, the liquid may be poured into the solid prepolymer and brought into contact with the liquid. As a method of charging the solid prepolymer into the liquid, for example, a method using a tank,
There is a method using a tower. When a tank is used, stirring may or may not be performed, but stirring is preferred to prevent the prepolymers from contacting each other. When a column is used, the solid prepolymer and the liquid can be brought into contact with each other in countercurrent or cocurrent. It is also possible to charge a solid prepolymer into the flowing liquid. The method of pouring the liquid into the solid prepolymer and bringing the liquid into contact with the solid prepolymer may be a method of spraying the liquid on the solid prepolymer or flowing the liquid through a column filled with the solid prepolymer.

Liquid Used for Crystallization The liquid used for crystallization may be any liquid that does not dissolve the solid prepolymer at the liquid temperature for crystallization.
Commonly used general-purpose solvents such as water, alcohols, aliphatic hydrocarbons, aromatic hydrocarbons, ketones, ethers, and esters can be used. These may be used alone or in combination. Moreover, you may add an organic acid as needed. Specifically, examples of the alcohol include methanol, ethanol, propanol, iso-propanol, butanol, iso-butanol, sec-butanol, tert-butanol,
Pentanol, iso-pentanol, tert-pentanol, hexanol, iso-hexanol, te
rt-hexanol and cyclohexanol. Examples of the aliphatic hydrocarbon include hexane, cyclohexane, n-heptane, n-octane, n-nonane, n-decane, n-undecane, n-dodecane, n-tridecane, and n-tetradecane. As aromatic hydrocarbons, benzene, toluene, xylene, mesitylene,
Cumene, cymene, styrene, ethylbenzene. Ketones include acetone and methyl ethyl ketone, ethers include methyl-t-butyl ether, dibutyl ether and anisole, and esters include ethyl acetate, butyl acetate, methyl lactate, ethyl lactate and butyl lactate. Can be Of these liquids, water is preferred. When the prepolymer is polylactic acid, the crystallization by contacting with water has an effect of suppressing the coloring of the polymer during the solid-phase polymerization, as compared with the method of crystallization by heating in a normal gas phase.

Concentration of Prepolymer in Crystallization The amount of the solid prepolymer subjected to crystallization is 0.1% by weight or more and less than 100% by weight based on the total weight of the liquid and the prepolymer to be treated per unit time. , But preferably 1% by weight or more and 80% by weight or less.
If the amount of the solid prepolymer exceeds 80% by weight, it is not preferable that the temperature of the liquid is equal to or higher than the glass transition temperature of the prepolymer, because the liquid easily fuses.

Crystallization temperature The contact temperature may be at least the freezing point of the liquid to be used and less than the melting point of the prepolymer. However, in order to be able to crystallize efficiently, it must be at least the glass transition temperature of the prepolymer and at most the melting point. Is preferred. When the crystallization temperature is equal to or higher than the glass transition temperature of the prepolymer, a phenomenon occurs in which the prepolymers fuse with each other when they come into contact with each other. Therefore, fusion can be prevented by interposing a liquid. Even if the crystallization temperature is lower than the glass transition temperature of the prepolymer, the prepolymer crystallizes, but the crystallization time becomes longer and the efficiency is poor. The temperature of the liquid is
As long as the temperature is within the range, the temperature may be gradually increased or may be gradually cooled. After the surface of the prepolymer is crystallized at a liquid temperature equal to or lower than the glass transition temperature of the prepolymer, the temperature can be raised to increase the crystallization efficiency. The rate of temperature rise when the temperature is gradually increased and the rate of cooling when the temperature is gradually cooled are not particularly limited, but are preferably 0.1 to 20 [° C./min]. In the case where crystallization is performed continuously, it is preferable to maintain the temperature of the liquid at a constant temperature.

Crystallization Time The time for contacting with the liquid is not particularly limited as long as the prepolymer is crystallized, but the impurities in the prepolymer can be removed during crystallization. Set in consideration of the ease of drying later. Generally, it is preferably 1 to 180 minutes, more preferably 10 to 120 minutes. When the molecular weight of the prepolymer is 10,000 or less, 1
If the prepolymer is brought into contact with the liquid for 80 minutes or more, the strength of the prepolymer may decrease, which is not preferable. For example, polylactic acid having a molecular weight of 10,000 has a temperature of 50.degree.
Crystallizes in 0 minutes.

Drying of the Crystallized Prepolymer After crystallization of the prepolymer by contact with a liquid, the crystallized prepolymer and the liquid are separated by a known method. After being separated from the liquid, it is dried by a known method to obtain a crystallized prepolymer. Note that somewhere in this crystallization step, a catalyst used in the solid-state polymerization reaction, that is, a volatile catalyst or a nonvolatile catalyst may be added.

[Weight average molecular weight of aliphatic polyester]
In the present invention, the weight average molecular weight of the aliphatic polyester obtained by the solid phase polymerization method is not particularly limited as long as the weight average molecular weight (Mw ₂ ) is within the numerical range represented by the formula (2). The preferred range varies slightly depending on the type of polyester.

5 × 10 ⁴ ≦ Mw ₂ ≦ 1 × 10 ⁶ (2)

The aliphatic polyester obtained by solid-state polymerization of the above prepolymers (1) and (2)
It is preferably from 000 to 1,000,000, and 100,
000-500,000 is more preferred. In addition, for the aliphatic polyesters obtained by solid-phase polymerization of the prepolymers (3) to (6), the prepolymers (1) and (2) are subjected to solid-phase polymerization in order to express a high melt tension. It is preferable that the molecular weight is higher than that of the obtained aliphatic polyester, and the range is 50,000 to 1,000,000.
Is preferable, 100,000 to 500,000 is more preferable, and 200,000 to 500,000 is further preferable.

[Uses of Aliphatic Polyesters] The aliphatic polyesters according to the present invention are suitable as a substitute for resins used for medical use, food packaging and general use which were known and used before the present application. Can be used. Although the use of the aliphatic polyester according to the present invention is not particularly limited, the weight average molecular weight is remarkably high and the mechanical properties (tensile strength, elastic modulus, breaking strength, etc.) are excellent, so that the food container, industrial Application to fibers, tire cords, and magnetic tape base films is also suitable.

[Method of Forming and Using the Aliphatic Polyester According to the Present Invention] The method of forming and processing the aliphatic polyester obtained by the present invention is not particularly limited.
Molding methods such as injection molding, extrusion molding, inflation molding, extrusion hollow molding, foam molding, calendar molding, blow molding, balloon molding, vacuum molding, and spinning are exemplified.
In addition, the polyester may be formed by a suitable molding method, for example, members of writing utensils such as ballpoint pens, mechanical pens, pencils, etc., members of stationery, golf tees, members of smoke-generating golf balls for the opening ball type, capsules for oral medicine,
Suppository carrier for anal and vagina, carrier for patch for skin and mucous membranes, capsule for pesticides, capsule for fertilizer, capsule for seedling, compost, fishing line spool, fishing float, fishing bait, lure, fishing buoy, hunting Decoys, hunting shot capsules, camping equipment such as tableware, nails, piles, binding materials, non-slip materials for muddy and snowy roads, blocks, lunch boxes, tableware, containers for lunch boxes and prepared dishes sold at convenience stores,
Chopsticks, disposable chopsticks, forks, spoons, skewers, toothpicks, cups for cup ramen, cups used in beverage vending machines, containers and trays for foodstuffs such as fresh fish, meat, fruits and vegetables, tofu, prepared foods, fresh fish Torobaco as used in the market, bottles for dairy products such as milk, yogurt, lactic acid bacteria drinks, bottles for soft drinks such as carbonated drinks and soft drinks, bottles for alcoholic drinks such as beer and whiskey,
Bottles with or without pumps for shampoo and liquid soap, tubes for toothpaste, cosmetic containers, detergent containers, bleach containers, cool boxes, flowerpots, casings for water purifier cartridges, casings for artificial kidneys and artificial livers, Syringe parts, cushioning materials for transporting home appliances such as televisions and stereos, cushioning materials for transportation of precision machinery such as computers, printers, clocks, and ceramic products such as glass and ceramics. It can be used as a cushioning material for use during transportation.

[0120]

The present invention will be described in detail below with reference to examples. The description of the examples in the specification of the present application is an explanation for assisting the understanding of the contents of the present invention, and the description is not of a nature that is a basis for interpreting the technical scope of the present invention narrowly. Absent. The evaluation method used in this example is as follows.

1) Weight Average Molecular Weight The weight average molecular weight (Mw) of the obtained aliphatic polyester polymer was determined by gel permeation chromatography (column temperature: 40 ° C., chloroform solvent) in comparison with a polystyrene standard sample. .

2) Optical purity of lactic acid component Sample preparation: 1 g of a sample (solid sample was ground into a powder in a mortar) was weighed in a 50 ml Erlenmeyer flask, and 2.5 ml of isopropyl alcohol and 5 m of 5N-NaOH were added.
and hydrolyze while stirring on a hot plate at 40 ° C. After the polymer has been decomposed and completely dissolved, it is cooled to room temperature and neutralized by adding 20 ml of 1N HCl. 1 ml of the decomposed neutralized solution was collected in a 25 ml volumetric flask, made up with an HPLC mobile phase solution having the following composition, and then measured by an HPLC method set under the following conditions to determine the area ratio of the D / L form peak of lactic acid. Calculated. Measurement conditions: Column: SUMICHIRAL OA-5
000 (Sumitika Analysis Center) Mobile phase: 1 mM CuSO ₄ aqueous solution / isopropyl alcohol = 98/2 Flow rate: 1 ml / min Detection wavelength: 254 nm Temperature: room temperature (25 ° C.) Injection volume: 5 μl

3) Measurement of water content in solvent The measurement was carried out using a Karl Fischer moisture meter (MKC-210, manufactured by Kyoto Electronics Industry Co., Ltd.).

4) Differential thermal analysis: Analysis was performed with a scanning calorimeter (DSC-3100, manufactured by Mac Science) in a temperature range of -20 ° C to 230 ° C.

5) Tensile Strength Tensile strength was measured using a film sample prepared by hot pressing at 180 ° C. in accordance with Japanese Industrial Standard JIS K-6732.

6) Haze (Haze) A 100 μm-thick film sample hot-pressed at 180 ° C. was subjected to Japanese Industrial Standard JIS K-6714.
Was measured using a Haze meter TC-HIII (Tokyo Denshoku Co., Ltd.).

7) Yellowness (YI value) A plate sample having a thickness of 2 mm was prepared.
According to Japanese Industrial Standard JIS K-7103,
SM color computer (Model: SM-6-IS-2
B, Suga Test Instruments Co., Ltd.).

8) Catalyst concentration (sulfur concentration) in aliphatic polyester The catalyst concentration (sulfur concentration) in the aliphatic polyester was determined by ion chromatography. That is, the gas generated when the sample is heated to 900 ° C. (Ar / O ₂ ) in a closed system and incinerated is supplied to a fixed volume absorbing solution (1% -H ₂ O _2).
Solution) and quantified by ion chromatography. For the measurement of ion chromatography, Ion Chromato DX-300 manufactured by Dionex was used.

9) Residual Catalyst Rate (R) The residual catalyst rate (R) was calculated according to the formula shown in the detailed description of the present invention. However, after the completion of the dehydration polycondensation reaction,
Catalyst concentration C _A in aliphatic polyester finally obtained
The sulfur analysis values determined in 8) were converted to the various organic sulfonic acid compounds used in the examples. In the following examples, after the completion of the dehydration polycondensation reaction, the catalyst concentration C _A in the finally obtained aliphatic polyester, and the catalyst charged into the reaction system in the dehydration polycondensation reaction are all contained in the aliphatic polyester. theoretical catalyst concentration C _B in the case of remaining, respectively,
They are simply referred to as catalyst concentration C _A and catalyst concentration C _B.

10) Retention of molecular weight during pressing The thermal stability was evaluated by the retention of molecular weight during pressing. The molecular weight retention during pressing was calculated from the ratio of the weight average molecular weight before preparing a hot press film at 190 ° C. to the weight average molecular weight after preparing a hot press film. Press film is obtained by subjecting aliphatic polyester obtained by solid-state polymerization to 5 ° C at 60 ° C.
After performing vacuum drying for a time, at a press temperature of 190 ° C,
The film was heated at a holding pressure of 10 MPa for 1 minute for a total of 4 minutes to produce a film having a thickness of 100 μm.

11) Flexural Strength The flexural strength was measured using a molded article having a predetermined shape which was injection molded at 180 to 200 ° C. in accordance with Japanese Industrial Standard JIS K-7113.

12) Melt tension (MT value) After measuring the melt flow index at two appropriate temperatures using a load of 2160 g, the melt flow index is 10 g / 10 minutes from the temperature-melt flow index-plot. The temperature was determined and the melt tension was measured at that temperature. 13) Degradability A film hot-pressed at 180 ° C. was embedded in a compost at room temperature for 30 days, and the tensile strength was measured before and after embedding to evaluate the degradability.

Example 1 88% L-lactic acid 102.3
g, p-toluenesulfonic acid monohydrate (0.80 g) in 50
The mixture was placed in a 0 ml round-bottom flask and heated from room temperature to 160 ° C. over 1 hour under a normal pressure and nitrogen atmosphere.
After maintaining at 1 ° C. for 1 hour, the pressure was gradually reduced from normal pressure to 10 mmHg over 2 hours while maintaining 160 ° C., and finally, the reaction was carried out at 160 ° C./10 mmHg for 6 hours.
The molecular weight at this time was 8,200. Thereafter, the reaction solution was discharged into an enamel vat and cooled to 30 ° C. to obtain 67.7 g (yield 94.0%) of a prepolymer. This prepolymer is pulverized in a mortar and then sieved to obtain a particle diameter of 0.1.
A granular prepolymer of 5 to 2 mm was obtained. 20.00 g of this prepolymer was charged into 80 g of water at 50 ° C., and crystallized for 60 minutes with stirring. 5.00 g of the prepolymer dried in an inert oven at 60 ° C. was added to SU
S (stainless steel) vertical reactor, charged 1
1 hour at 20 ° C / nitrogen flow rate 200 [ml / min]
120 hours at 40 ° C./nitrogen flow rate 200 [ml / min]
Perform solid phase polymerization to obtain aliphatic polyester (polylactic acid)
4.75 g (95.0% yield) was obtained. The aliphatic polyester (polylactic acid) was not fused. The nitrogen gas used had a dew point of -60 ° C. The properties of the aliphatic polyester obtained by the solid-state polymerization are as follows. Weight average molecular weight (Mw) = 140,000 Catalyst concentration C _A = 914 [ppm] (Sulfur analysis value: 170
[Ppm]) Catalyst concentration C _B = 1300 [ppm] Residual rate of catalyst R = 8.1 [%] Retention rate of molecular weight during pressing = 92%

Example 2 88% L-lactic acid 102.3
g, p-toluenesulfonic acid monohydrate (0.80 g) in 50
The mixture was placed in a 0 ml round-bottom flask and heated from room temperature to 160 ° C. over 1 hour under a normal pressure and nitrogen atmosphere.
After maintaining at 1 ° C. for 1 hour, the pressure was gradually reduced from normal pressure to 10 mmHg over 2 hours while maintaining 160 ° C., and finally, the reaction was carried out at 160 ° C./10 mmHg for 6 hours.
The molecular weight at this time was 8,200. Thereafter, the reaction solution was discharged into an enamel vat and cooled to 30 ° C. to obtain 67.7 g (yield 94.0%) of a prepolymer. This prepolymer is pulverized in a mortar and then sieved to obtain a particle diameter of 0.1.
A granular prepolymer of 5 to 2 mm was obtained. 20.00 g of this prepolymer was charged into 80 g of water at 50 ° C., and crystallized for 60 minutes with stirring. 5.00 g of the prepolymer dried in an inert oven at 60 ° C. was added to SU
S (stainless steel) vertical reactor, charged 1
1 hour at 20 ° C / nitrogen flow rate 200 [ml / min]
1 hour at 40 ° C./nitrogen flow rate 200 [ml / min]
Solid phase polymerization is performed at 60 ° C./nitrogen flow rate 200 [ml / min] for 40 hours to obtain an aliphatic polyester (polylactic acid).
4.77 g (95.4% yield) was obtained. The aliphatic polyester (polylactic acid) was not fused. The nitrogen gas used had a dew point of -60 ° C. The properties of the aliphatic polyester obtained by the solid-state polymerization are as follows. Weight average molecular weight (Mw) = 138,000 Catalyst concentration C _A = 751 [ppm] (Sulfur analysis value: 140
[Ppm]) Catalyst concentration C _B = 11200 [ppm] Residual rate of catalyst R = 6.7 [%] Retention rate of molecular weight during pressing = 94%

Example 3 Production of Prepolymer A prepolymer was produced under the following reaction conditions. The weight average molecular weight (Mw) of the obtained prepolymer was 13,300.
Met. <Reaction conditions> Monomer 88% L-lactic acid 400.0 g Volatile catalyst p-toluenesulfonic acid monohydrate 3.11 g Reactor 500 ml round bottom flask Reaction temperature and reaction time (reaction pressure and reaction atmosphere) Next 5 stages. 1st stage; temperature rise from 25 to 100 ° C over 30 minutes (atmospheric pressure / nitrogen atmosphere) 2nd stage; temperature rise from 100 to 160 ° C over 1 hour (atmospheric pressure / nitrogen atmosphere) 3rd stage; Maintained at 160 ° C for 1 hour (atmospheric pressure / nitrogen atmosphere) 4th stage; Maintained at 160 ° C for 2 hours (atmospheric pressure / nitrogen atmosphere → reduced to 10 mmHg) 5th stage; Maintained at 160 ° C for 8 hours (maintained at 10 mmHg) Solidification of prepolymer After measuring the tare of a round bottom flask and calculating the yield of the prepolymer (267.5 g, 95.0% yield), the reaction solution was discharged into an enamel vat and cooled to 30 ° C. after,
The prepolymer was pulverized in a mortar and sieved to obtain a granular prepolymer having a particle diameter of 0.5 to 2.0 mm. Crystallization of Prepolymer 5.00 g of the prepolymer was charged into a vertical reactor made of SUS (stainless steel) and crystallized at 80 ° C./nitrogen atmosphere for 1 hour. Solid phase polymerization Following crystallization of the prepolymer, SU
In a vertical reactor made by S, the following two-stage solid-state polymerization was performed. First stage: reaction pressure 760 [mmHg], reaction temperature 14
0 ° C., flowing gas (nitrogen gas), flow rate 5 [ml / min], reaction time 40 hours, solid phase polymerization 2nd stage; reaction pressure 760 [mmHg], reaction temperature 16
0 ° C, flowing gas (nitrogen gas), flow rate 200 [ml /
Minutes] and a solid phase polymerization of 60 hours in 4.75 g of aliphatic polyester (polylactic acid) (yield 9).
5.0%). The dew point of the used nitrogen gas is -60 ° C
Met. The properties of the aliphatic polyester obtained by the solid-state polymerization are as follows. Weight average molecular weight (Mw) = 146,000 Catalyst concentration C _A = 751 [ppm] (Sulfur analysis value: 140
[Ppm]) Catalyst concentration C _B = 11000 [ppm] Residual rate of catalyst R = 6.8 [%] Retention rate of molecular weight during pressing = 94%

Example 4 Production of Prepolymer A prepolymer was produced under the following reaction conditions. The weight average molecular weight (Mw) of the obtained prepolymer was 13,000.
Met. <Reaction conditions> Monomer 88% L-lactic acid 400.0 g Volatile catalyst Methanesulfonic acid 2.82 g Reactor 500 ml round bottom flask Reaction temperature and reaction time (reaction pressure and reaction atmosphere) The following five stages were used. 1st stage; temperature rise from 25 to 100 ° C over 30 minutes (atmospheric pressure / nitrogen atmosphere) 2nd stage; temperature rise from 100 to 160 ° C over 1 hour (atmospheric pressure / nitrogen atmosphere) 3rd stage; Maintained at 160 ° C for 1 hour (atmospheric pressure / nitrogen atmosphere) 4th stage; Maintained at 160 ° C for 2 hours (atmospheric pressure / nitrogen atmosphere → reduced to 10 mmHg) 5th stage; Maintained at 160 ° C for 8 hours (maintained at 10 mmHg)

Solidification of Prepolymer After measuring the tare of a round bottom flask and calculating the yield of the prepolymer (268.4 g, 95.3% yield), the reaction solution was discharged into an enamel vat, Cool down to ℃
The prepolymer was pulverized in a mortar and sieved to obtain a granular prepolymer having a particle diameter of 0.5 to 2.0 mm.

Crystallization of Prepolymer 5.00 g of the prepolymer was charged into a SUS (stainless steel) vertical reactor and crystallized at 80 ° C./nitrogen atmosphere for 1 hour.

Solid State Polymerization Following the crystallization of the prepolymer, the following two stages of solid state polymerization were carried out in a vertical reactor made of SUS. First stage: reaction pressure 760 [mmHg], reaction temperature 14
0 ° C., flowing gas (nitrogen gas), flow rate 5 [ml / min], reaction time 40 hours, solid phase polymerization 2nd stage; reaction pressure 760 [mmHg], reaction temperature 16
0 ° C, flowing gas (nitrogen gas), flow rate 200 [ml /
Minutes] and a reaction time of 60 hours to obtain 4.75 g (yield 95.0%) of solid-phase polymerized aliphatic polyester (polylactic acid). The nitrogen gas used had a dew point of -60 ° C. The properties of the aliphatic polyester obtained by the solid-state polymerization are as follows. Weight average molecular weight (Mw) = 133,000 Catalyst concentration C _A = 329 [ppm] (Sulfur analysis value: 110
[Ppm]) catalyst concentration C _B = 11100 [ppm] catalyst residual percentage R = 3.0 [%] Press at molecular weight retention rate = 92%

Example 5 Production of Prepolymer A prepolymer was produced under the following reaction conditions. The weight average molecular weight (Mw) of the obtained prepolymer was 13,000.
Met. <Reaction conditions> Monomer 88% L-lactic acid 400.0 g Volatile catalyst Ethansulfonic acid 2.82 g Reactor 500 ml round bottom flask Reaction temperature and reaction time (reaction pressure and reaction atmosphere) The following five stages were used. 1st stage; temperature rise from 25 to 100 ° C over 30 minutes (atmospheric pressure / nitrogen atmosphere) 2nd stage; temperature rise from 100 to 160 ° C over 1 hour (atmospheric pressure / nitrogen atmosphere) 3rd stage; 160 ° C 1 hour (atmospheric pressure / nitrogen atmosphere) 4th stage; maintained at 160 ° C. for 2 hours (atmospheric pressure / nitrogen atmosphere → reduced pressure to 10 mmHg) 5th stage; maintained at 160 ° C. for 8 hours (maintained at 10 mmHg) Prepolymer Solidification After measuring the tare of the round bottom flask and calculating the yield of the prepolymer (266.7 g, 94.7% yield), the reaction solution was discharged into an enamel vat and cooled to 30 ° C. ,
The prepolymer was pulverized in a mortar and sieved to obtain a granular prepolymer having a particle diameter of 0.5 to 2.0 mm. Crystallization of Prepolymer 5.00 g of the prepolymer was charged into a vertical reactor made of SUS (stainless steel) and crystallized at 80 ° C./nitrogen atmosphere for 1 hour. Solid-State Polymerization Following the crystallization of the prepolymer, the following two-stage solid-state polymerization was performed in a SUS vertical reactor. First stage: reaction pressure 760 [mmHg], reaction temperature 14
0 ° C., flowing gas (nitrogen gas), flow rate 5 [ml / min], reaction time 40 hours, solid phase polymerization 2nd stage; reaction pressure 760 [mmHg], reaction temperature 16
0 ° C, flowing gas (nitrogen gas), flow rate 200 [ml /
Minutes] and a solid phase polymerization of 60 hours with 4.78 g of aliphatic polyester (polylactic acid) (yield 9).
5.6%). The dew point of the used nitrogen gas is -60 ° C
Met. The properties of the aliphatic polyester obtained by the solid-state polymerization are as follows. Weight average molecular weight (Mw) = 130,000 Catalyst concentration C _A = 377 [ppm] (Sulfur analysis value: 110
[Ppm]) catalyst concentration C _B = 11100 [ppm] catalyst residual percentage R = 3.4 [%] Press at molecular weight retention rate = 92%

Example 6 Production of Prepolymer A prepolymer was produced under the following reaction conditions. The weight average molecular weight (Mw) of the obtained prepolymer was 12,000.
Met. <Reaction conditions> Monomer 88% L-lactic acid 400.0 g Volatile catalyst 1-propane sulfone 2.82 g Reactor 500 ml round bottom flask Reaction temperature and reaction time (reaction pressure and reaction atmosphere) The following five steps were used. . 1st stage; temperature rise from 25 to 100 ° C over 30 minutes (atmospheric pressure / nitrogen atmosphere) 2nd stage; temperature rise from 100 to 160 ° C over 1 hour (atmospheric pressure / nitrogen atmosphere) 3rd stage; 160 ° C 1 hour (atmospheric pressure / nitrogen atmosphere) 4th stage; maintained at 160 ° C. for 2 hours (atmospheric pressure / nitrogen atmosphere → reduced pressure to 10 mmHg) 5th stage; maintained at 160 ° C. for 8 hours (maintained at 10 mmHg) Prepolymer Solidification After measuring the tare of the round bottom flask and calculating the yield of the prepolymer (264.1 g, 93.8% yield), the reaction solution was discharged into an enamel vat and cooled to 30 ° C. ,
The prepolymer was pulverized in a mortar and sieved to obtain a granular prepolymer having a particle diameter of 0.5 to 2.0 mm. Crystallization of Prepolymer 5.00 g of the prepolymer was charged into a vertical reactor made of SUS (stainless steel) and crystallized at 80 ° C./nitrogen atmosphere for 1 hour. Solid-State Polymerization Following the crystallization of the prepolymer, the following two-stage solid-state polymerization was performed in a SUS vertical reactor. First stage: reaction pressure 760 [mmHg], reaction temperature 14
0 ° C., flowing gas (nitrogen gas), flow rate 5 [ml / min], reaction time 40 hours, solid phase polymerization 2nd stage; reaction pressure 760 [mmHg], reaction temperature 16
0 ° C, flowing gas (nitrogen gas), flow rate 200 [ml /
Minutes] and a reaction time of 60 hours to obtain 4.76 g (yield 95.2%) of solid-phase polymerized aliphatic polyester (polylactic acid). The nitrogen gas used had a dew point of -60 ° C. The properties of the aliphatic polyester obtained by the solid-state polymerization are as follows. Weight average molecular weight (Mw) = 130,000 Catalyst concentration C _A = 387 [ppm] (Sulfur analysis value: 100
[Ppm]) Catalyst concentration C _B = 11200 [ppm] Catalyst residual ratio R = 3.5 [%] Retention rate of molecular weight during pressing = 93%

Example 7 Production of Prepolymer A prepolymer was produced under the following reaction conditions. The weight average molecular weight (Mw) of the obtained prepolymer was 12,000. <Reaction conditions> Monomer 88% L-lactic acid 400.0 g Volatile catalyst p-chlorobenzenesulfonic acid 1.69 g Reactor 500 ml round bottom flask Reaction temperature and reaction time (reaction pressure and reaction atmosphere) did. 1st stage; temperature rise from 25 to 100 ° C over 30 minutes (atmospheric pressure / nitrogen atmosphere) 2nd stage; temperature rise from 100 to 160 ° C over 1 hour (atmospheric pressure / nitrogen atmosphere) 3rd stage; 160 ° C 1 hour (atmospheric pressure / nitrogen atmosphere) 4th stage; maintained at 160 ° C. for 2 hours (atmospheric pressure / nitrogen atmosphere → reduced pressure to 10 mmHg) 5th stage; maintained at 160 ° C. for 10 hours (maintained at 10 mmHg) Prepolymer Solidification After measuring the tare of the round bottom flask and calculating the yield of the prepolymer (265.3 g, 94.2% yield), the reaction solution was discharged into an enamel vat and cooled to 30 ° C. ,
The prepolymer was pulverized in a mortar and sieved to obtain a granular prepolymer having a particle diameter of 0.5 to 2.0 mm. Crystallization of Prepolymer 5.00 g of the prepolymer was charged into a vertical reactor made of SUS (stainless steel) and crystallized at 80 ° C./nitrogen atmosphere for 1 hour. Solid-State Polymerization Following the third step, the following two-stage solid-state polymerization was performed in a SUS vertical reactor. First stage: reaction pressure 760 [mmHg], reaction temperature 14
0 ° C., flowing gas (nitrogen gas), flow rate 5 [ml / min], reaction time 60 hours, solid phase polymerization 2nd stage; reaction pressure 760 [mmHg], reaction temperature 16
0 ° C, flowing gas (nitrogen gas), flow rate 200 [ml /
Minutes] and a reaction time of 60 hours, and 4.74 g of an aliphatic polyester (polylactic acid) (solid yield 9)
4.8%). The dew point of the used nitrogen gas is -60 ° C
Met. The properties of the aliphatic polyester obtained by the solid-state polymerization are as follows. Weight average molecular weight (Mw) = 138,000 Catalyst concentration C _A = 840 [ppm] (Sulfur analysis value: 140
[Ppm]) Catalyst concentration C _B = 6720 [ppm] Catalyst residual ratio R = 1
2.5 [%] Molecular weight retention during pressing = 90%

Example 8 Production of Prepolymer A reaction was carried out in the following three stages under the following reaction conditions. The weight average molecular weight (Mw) of the obtained prepolymer was 20,000
It was 0. <Reaction conditions> Monomer 88% L-lactic acid 102.3 g Volatile catalyst p-toluenesulfonic acid monohydrate
80 g <First stage> Reactor 500 ml round bottom flask Reaction temperature 140 ° C. Reaction pressure 100 mmHg Reaction time 3 hours Reaction operation The mixture was heated and stirred while distilling water out of the reaction system. <Second stage> Reactor 50 equipped with Dean Stark trap
0 ml round bottom flask Reaction temperature 140 ° C. Reaction pressure 270 mmHg Reaction time 4 hours Reaction operation 72 g of o-dichlorobenzene were charged into a Dean-Stark trap and a reaction mass, respectively.
It was azeotropically dehydrated for 4 hours. <Third Stage> Reactor The Dean-Stark trap is removed, and the returning organic solvent (o-dichlorobenzene) passes through the molecular sieve packed bed (the bed filled with 30 g of molecular sieve 3A) and returns to the round bottom flask again. Reaction temperature 140 ° C. Reaction pressure 270 mmHg Reaction time 8 hours Reaction operation 8 hours in a molecular sieve filled tube
54 g of [ppm] o-dichlorobenzene was charged to the reaction mass, and 144 g of o-dichlorobenzene was charged. The mixture was heated and stirred so that the refluxing organic solvent returned to the round bottom flask through the molecular sieve packed tube. Solidification of prepolymer After cooling the reaction solution to 30 ° C to crystallize the polymer,
The o-dichlorobenzene was distilled off at 60 ° C./10 mmHg, and the polymer was dried under a nitrogen atmosphere to obtain 67.6 g (yield 93.9%) of a powdery prepolymer. Further, this powdery prepolymer was drawn and sieved using a melt indexer to obtain a pellet-shaped prepolymer having a particle diameter of 0.5 to 2.0 mm. Crystallization of Prepolymer 5.00 g of the prepolymer was charged into a vertical reactor made of SUS (stainless steel) and crystallized at 80 ° C./nitrogen atmosphere for 1 hour. Solid phase polymerization Following crystallization of the prepolymer, SU
In a vertical reactor made by S, the following two-stage solid-state polymerization was performed. First stage: reaction pressure 760 [mmHg], reaction temperature 14
0 ° C., flowing gas (nitrogen gas), flow rate 5 [ml / min], reaction time 40 hours, solid phase polymerization 2nd stage; reaction pressure 760 [mmHg], reaction temperature 16
0 ° C, flowing gas (nitrogen gas), flow rate 200 [ml /
Minutes], and a solid phase polymerization of 60 hours in 4.77 g of aliphatic polyester (polylactic acid) (yield 9)
5.4%). The dew point of the used nitrogen gas is -60 ° C
Met. The properties of the aliphatic polyester obtained by the solid-state polymerization are as follows. Weight average molecular weight (Mw) = 143,000 Catalyst concentration C _A = 751 [ppm] (Sulfur analysis value: 140
[Ppm]) Catalyst concentration C _B = 11200 [ppm] Residual rate of catalyst R = 6.7 [%] Retention rate of molecular weight during pressing = 94%

Example 9 Production of Prepolymer A prepolymer was produced under the following reaction conditions. The weight average molecular weight (Mw) of the obtained prepolymer was 12,000. <Reaction conditions> Monomer 88% L-lactic acid 400.0 g Volatile catalyst Benzenesulfonic acid monohydrate
88 g reactor 500 ml round bottom flask Reaction temperature and reaction time (reaction pressure and reaction atmosphere) The following five stages were used. 1st stage; temperature rise from 25 to 100 ° C over 30 minutes (atmospheric pressure / nitrogen atmosphere) 2nd stage; temperature rise from 100 to 160 ° C over 1 hour (atmospheric pressure / nitrogen atmosphere) 3rd stage; 160 ° C 1 hour (atmospheric pressure / nitrogen atmosphere) 4th stage; maintained at 160 ° C. for 2 hours (atmospheric pressure / nitrogen atmosphere → reduced pressure to 10 mmHg) 5th stage; maintained at 160 ° C. for 10 hours (maintained at 10 mmHg) Prepolymer Solidification After measuring the tare of the round bottom flask and calculating the yield of the prepolymer (265.3 g, 94.2% yield), the reaction solution was discharged into an enamel vat and cooled to 30 ° C. ,
The prepolymer was pulverized in a mortar and sieved to obtain a granular prepolymer having a particle diameter of 0.5 to 2.0 mm. Crystallization of Prepolymer 5.00 g of the prepolymer was charged into a vertical reactor made of SUS (stainless steel) and crystallized at 80 ° C./nitrogen atmosphere for 1 hour. Solid-State Polymerization Following the crystallization of the prepolymer, the following two-stage solid-state polymerization was performed in a SUS vertical reactor. First stage: reaction pressure 760 [mmHg], reaction temperature 14
0 ° C., flowing gas (nitrogen gas), flow rate 5 [ml / min], reaction time 60 hours, solid phase polymerization 2nd stage; reaction pressure 760 [mmHg], reaction temperature 16
0 ° C, flowing gas (nitrogen gas), flow rate 200 [ml /
Minutes] and a solid phase polymerization of 60 hours in 4.75 g of aliphatic polyester (polylactic acid) (yield 9).
5.0%). The dew point of the used nitrogen gas is -60 ° C
Met. The properties of the aliphatic polyester obtained by the solid-state polymerization are as follows. Weight average molecular weight (Mw) = 129,000 Catalyst concentration C _A = 690 [ppm] (Sulfur analysis value: 140
[Ppm]) Catalyst concentration C _B = 6710 [ppm] Residual rate of catalyst R = 10.3 [%] Retention rate of molecular weight during pressing = 91%

Examples of the preparation and crystallization of the prepolymer used for the solid phase polymerization of Examples 10 to 17 are described below.

[Prepolymer Production Example 1] A 500 ml glass four-necked flask was charged with 400 g of 90% L-lactic acid (D-form content: 0.40%) and 1.91 g of p-toluenesulfonic acid monohydrate. After the replacement, the degree of pressure reduction is 80 m
The temperature was raised from room temperature to 120 ° C. with mHg. At about 60 ° C., water began to distill, and the temperature was raised to 120 ° C. over 1 hour, taking this time as 0 hour. After the temperature reached 120 ° C., the pressure was kept at 80 mmHg for another 1 hour. After this 12
At 0 ° C., the degree of pressure reduction was changed from 80 mmHg to 10 mmHg in 30 minutes, and the temperature was maintained for 3 hours. The weight average molecular weight (Mw) of the total of 5 hours and 30 minutes up to this point is 1500, and D
The body content was 0.41%. Next, the degree of decompression 10 mm
The temperature was raised from 120 ° C. to 160 ° C. in 1 hour while maintaining Hg,
The dehydration condensation was continued under the conditions of 10 mmHg and 160 ° C.
10 mmHg, 160 ° C, 10 hours (total 16 hours 30
Minute), the reaction was stopped to obtain 273 g of a polymer. (Yield 94.8%) The obtained polylactic acid was 16,000, and the D-form content was 0.66%.

[Prepolymer Production Example 2] A 500 ml glass four-necked flask was charged with 400 g of 90% L-lactic acid (D-form content: 0.40%) and 1.58 g of methanesulfonic acid, followed by purging with nitrogen. The temperature was raised from room temperature to 120 ° C at a reduced pressure of 80 mmHg. Water starts to distill at about 60 ° C,
With this time taken as 0 hour, the temperature was raised to 120 ° C. over 1 hour, and after the temperature reached 120 ° C., the pressure was kept at 80 mmHg for another 1 hour. After this, 80 mmH at 120 ° C
The degree of reduced pressure was changed from g to 10 mmHg in 30 minutes, and the temperature was maintained for 3 hours. The weight average molecular weight (Mw) for a total of 5 hours and 30 minutes up to this point is 1500, and the D-form content is 0.4
1%. Next, the pressure reduction degree is kept at 10 mmHg for 120 minutes.
Temperature from 160 ° C to 160 ° C in 1 hour, 10 mmHg, 1
The dehydration condensation was continued at 60 ° C. 10mmHg, 1
The reaction was stopped at 60 ° C. for 10 hours (16 hours and 30 minutes in total) to obtain 272 g of a polymer. (Yield 94.4%) The obtained polylactic acid was 15,000, and the D-form content was 0.69%.
Met.

[Prepolymer Prepolymer Crystallization Example 1]
Each of the prepolymers of Prepolymer Production Examples 1 to 4 was pulverized in a mortar and sieved to a particle size of 2.36 to 2.80.
(Mm) granular prepolymer was obtained. For each of these prepolymers, 20 g of the prepolymer was charged into 80 g of water at 50 ° C. and left to crystallize for 60 minutes. No fusion or breakage of the prepolymers was observed. These crystallized prepolymers were designated as crystallized prepolymers 1 and 2.

[Solid State Polymerization]

Example 10 Crystallized Prepolymer 1
Was weighed in an amount of 5.00 g and charged in a SUS vertical reactor.
140 ° C. under nitrogen gas flow (nitrogen flow rate 50 ml / m)
in), 20 hours, 160 ° C., under nitrogen gas flow (nitrogen flow rate 25 ml / m
in), 40 hours, 160 ° C., under nitrogen gas flow (nitrogen flow rate 200 ml /
(min) for 20 hours to obtain 4.61 g of polylactic acid (yield: 92.2%). The nitrogen gas used had a dew point of -60 ° C. The properties of the aliphatic polyester obtained by the solid-state polymerization are as follows. Weight average molecular weight (Mw): 128,000 Differential thermal analysis: glass transition temperature is 58.0 ° C., melting point is 1.
66.0 ° C. Tensile strength: 570 [kg / cm ² ] (break) Tensile elongation: 8 [%] Haze: <1 [%] Yellowness (YI value): 7.0 D-body content: 0.82 [%] Catalyst concentration C _A : 646 [ppm] (Sulfur analysis value: 120
[Ppm]) Catalyst concentration C _B : 6870 [ppm] Residual rate of catalyst R: 9.4 [%] Retention rate of molecular weight during pressing: 93 [%] Degradability: The film was deteriorated to such an extent that the strength could not be measured.

Example 11 Prepolymer 2 was added at 5.00
g in a vertical reactor made of SUS and placed in a blow dryer at 140 ° C. under nitrogen gas flow (nitrogen flow rate 5 ml / mi).
n) for 20 hours at 160 ° C. under nitrogen gas flow (nitrogen flow rate 2.5 ml /
min), 40 hours, 160 ° C., under nitrogen gas flow (nitrogen flow rate 50 ml / m
In), solid phase polymerization was performed under the reaction conditions of 20 hours, and 4.60 g (yield: 92.0%) of polylactic acid was obtained. The nitrogen gas used had a dew point of -60 ° C. The properties of the aliphatic polyester obtained by the solid-state polymerization are as follows. Weight average molecular weight (Mw): 130,000 Differential thermal analysis: glass transition temperature is 58.0 ° C., melting point is 1.
66.3 ° C. Tensile strength: 580 [kg / cm ² ] (break) Tensile elongation: 8 [%] Haze: <1 [%] Yellowness (YI value): 4.5 D-body content: 0.87 [%] Catalyst concentration C _A : 450 [ppm] (Sulfur analysis value: 150
[Ppm]) Catalyst concentration C _B : 6320 [ppm] Residual rate of catalyst R: 7.1 [%] Retention rate of molecular weight during pressing: 93 [%] Degradability: The film was deteriorated to such an extent that the strength could not be measured. Solid-state polymerization of star polymer, etc.

Example 12 88% L-lactic acid 102.3
g, 0.78 g of paratoluenesulfonic acid monohydrate in 50
After charging the mixture in a 0 ml round bottom flask and subjecting it to a nitrogen atmosphere, the temperature was raised from room temperature to 160 ° C. over 1 hour.
After maintaining for 160 hours, the pressure was gradually reduced from normal pressure to 10 mmHg over 2 hours while maintaining 160 ° C.
The reaction was performed at 160 ° C./10 mmHg for 4 hours. The molecular weight at this time was 15,000. Here, 18 g of polybutylene succinate (molecular weight 40,000) was added to the reaction mass, and the reaction was further performed at 160 ° C./10 mmHg for 3 hours. The molecular weight at this time was 15,000. After this,
The reaction solution was discharged into an enamel vat, cooled to 30 ° C., and then the prepolymer was ground in a mortar to obtain a granular prepolymer. The obtained prepolymer was charged into a U-shaped glass tube, and the temperature was 80 ° C./1 hour and the nitrogen flow rate was 50 [ml / min].
After crystallization at 120 ° C./20 hours, nitrogen flow rate 50 [ml / min] for 20 hours, 140 ° C./150 hours, nitrogen flow rate 50 [ml / min], 150 ° C./20 hours
Heating was performed at a nitrogen flow rate of 200 [ml / min] to obtain 82.8 g (yield 92.0%) of an aliphatic polyester. Various physical properties are shown below. Weight average molecular weight: 104,000 Differential thermal analysis: glass transition temperature 25.7 ° C., melting point 14
8.4 ° C. Tensile strength: 300 kg / cm ² (yield) 320 kg / cm ² (break) Tensile elongation: 260% Haze: <1% Yellowness (YI value): 11 Retention of molecular weight during pressing: 90 [%] Degradability: The film was so deteriorated that its strength could not be measured.

Example 13 88% L-lactic acid 102.3
g, pentaerythritol 0.136 g, succinic acid 0.1 g.
236 g, p-toluenesulfonic acid monohydrate 0.78 g
Was charged into a 500 ml round bottom flask, and the temperature was raised from room temperature to 160 ° C. over 1 hour under a nitrogen atmosphere.
After maintaining at 160 ° C for 1 hour, the pressure was gradually reduced from normal pressure to 10 mmHg over 2 hours while maintaining the temperature at 160 ° C, and finally, the reaction was performed at 160 ° C / 10 mmHg for 8 hours.
The molecular weight at this time was 18,000. Thereafter, the reaction solution was discharged into an enamel vat, cooled to 30 ° C.,
The prepolymer was ground in a mortar to obtain a granular prepolymer. The obtained prepolymer was charged into a U-shaped glass tube, crystallized at 80 ° C./1 hour with a nitrogen flow rate of 60 [ml / min], and then 140 ° C./20 hours with a nitrogen flow rate of 6
The mixture was heated at 0 [ml / min] for 20 hours and at 160 ° C. for 40 hours. Various physical properties are shown below. Weight average molecular weight: 481,000 Differential thermal analysis: glass transition temperature is 59.8 ° C., melting point is 17.
2.8 ° C. Tensile strength: 620 kg / cm ² (break) Tensile elongation: 8% Flexural strength: 830 kg / cm ² Haze: 3.5% Yellowness (YI value): 2.7 In addition, melt flow index (MI) Value) is 10 g
/ 10 min and the melt tension at that temperature (M
T value) and evaluation of degradability are shown below. Temperature (MI: 10 g / 10 min): 200 (° C.) Melt tension (MT value): 3.2 (g) Molecular weight retention during pressing: 93 [%] Degradability: The film deteriorates so that the strength cannot be measured. I was

Example 14 88% L-lactic acid 102.3
g, pentaerythritol 0.0136 g, succinic acid 0.0236 g, p-toluenesulfonic acid monohydrate 0.1 g.
78 g was charged into a 500 ml round bottom flask and heated from room temperature to 160 ° C. over 1 hour under a nitrogen atmosphere.
After maintaining at 160 ° C. for 1 hour, the pressure was gradually reduced from normal pressure to 10 mmHg over 2 hours while maintaining the temperature at 160 ° C., and finally, the reaction was performed at 160 ° C./10 mmHg for 8 hours. The molecular weight at this time was 14,000.
Thereafter, the reaction solution was discharged into an enamel vat, cooled to 30 ° C., and then the prepolymer was ground in a mortar to obtain a granular prepolymer. The obtained prepolymer was charged into a U-shaped glass tube, and the temperature was 80 ° C./1 hour and the nitrogen flow rate was 60 [ml].
/ Min] at 140 ° C. for 20 hours and a nitrogen flow rate of 60 ml / min for 20 hours at 160 ° C./40 min.
Time Nitrogen flow rate 2400 [ml / min] Heated to obtain 66.3 g (yield 92.0%) of aliphatic polyester. Various physical properties are shown below. Weight average molecular weight: 210,000 Differential thermal analysis: glass transition temperature is 59.3 ° C., melting point is 16.
1.8 ° C. Tensile strength: 590 kg / cm ² (break) Tensile elongation: 8% Flexural strength: 790 kg / cm ² Haze: 3.0% Yellowness (YI value): 2.1 Also, melt flow index (MI) Value) is 10 g
/ 10 min and the melt tension at that temperature (M
T value) and evaluation of degradability are shown below. Temperature (MI: 10 g / 10 min): 200 (° C.) Melt tension (MT value): 2.7 (g) Molecular weight retention during pressing: 93 [%] Degradability: The film deteriorates so that the strength cannot be measured. I was

Example 15 88% L-lactic acid 102.3
g, pentaerythritol 0.136 g, succinic acid 0.1 g.
236 g and methanesulfonic acid 0.58 g were charged into a 500 ml round-bottomed flask, and a nitrogen atmosphere was applied.
The temperature was raised to 60 ° C. over 1 hour and maintained at 160 ° C. for 1 hour. Then, while maintaining the temperature at 160 ° C., the pressure was gradually reduced from normal pressure to 10 mmHg over 2 hours.
The reaction was carried out at / 10 mmHg for 8 hours. The molecular weight at this time was 18,000. Thereafter, the reaction solution was discharged into an enamel vat, cooled to 30 ° C., and then the prepolymer was ground in a mortar to obtain a granular prepolymer. The obtained prepolymer was charged into a U-shaped glass tube and heated at 80 ° C. /
After crystallization for 1 hour at a nitrogen flow rate of 60 [ml / min], 140 ° C / 20 hours nitrogen flow rate of 20 [ml / min]
For 20 hours, 160 ° C / 40 hours Nitrogen flow rate 1200
[Ml / min] 66.5g of aliphatic polyester by heating
(92.3% yield). Various physical properties are shown below. Weight average molecular weight: 314,000 Differential thermal analysis: glass transition temperature: 59.8 ° C., melting point: 17
2.8 ° C. Tensile strength: 620 kg / cm ² (break) Tensile elongation: 8% Flexural strength: 810 kg / cm ² Haze: 3.5% Yellowness (YI value): 2.5 Further, melt flow index (MI) Value) is 10 g
/ 10 min and the melt tension at that temperature (M
T value) and evaluation of degradability are shown below. Temperature (MI: 10 g / 10 min): 195 (° C.) Melt tension (MT value): 2.7 (g) Molecular weight retention during pressing: 93 [%] Degradability: The film deteriorates so that the strength cannot be measured. I was

Example 16 88% L-lactic acid 102.3
g, trimethylolpropane 0.134 g, succinic acid 0.178 g, p-toluenesulfonic acid monohydrate 0.7
8 g was charged into a 500 ml round-bottom flask, and the temperature was raised from room temperature to 160 ° C. over 1 hour under a nitrogen atmosphere.
After holding at 60 ° C for 1 hour, while maintaining 160 ° C,
Gradually reduce the pressure from normal pressure to 10 mmHg over 2 hours,
Finally, the reaction was performed at 160 ° C./10 mmHg for 8 hours. The molecular weight at this time was 14,000. Thereafter, the reaction solution was discharged into an enamel vat, cooled to 30 ° C., and then the prepolymer was ground in a mortar to obtain a granular prepolymer. The obtained prepolymer was charged into a U-shaped glass tube, and the nitrogen flow rate was 60 [ml / 80 ° C / 1 hour.
Min), and heated at 140 ° C./20 hours with a nitrogen flow rate of 60 [ml / min] for 20 hours and 160 ° C./40 hours with a nitrogen flow rate of 2400 [ml / min] to obtain 66.5 g of aliphatic polyester ( Yield 92.3%). Various physical properties are shown below. Weight average molecular weight: 261,000 Differential thermal analysis: glass transition temperature is 59.6 ° C., melting point is 17.
1.8 ° C. Tensile strength: 600 kg / cm ² (break) Tensile elongation: 8% Flexural strength: 800 kg / cm ² Haze: 3.1% Yellowness (YI value): 3.2 Also, melt flow index (MI) The temperature at which the value (value) is 10 g / 10 minutes, the melt tension (MT value) at that temperature, and the evaluation of the decomposability are shown below. Temperature (MI: 10 g / 10 min): 195 (° C.) Melt tension (MT value): 3.0 (g) Molecular weight retention during pressing: 93 [%] Degradability: The film deteriorates so that the strength cannot be measured. I was

Comparative Example 1 88% L-lactic acid 102.3
g, p-toluenesulfonic acid monohydrate (0.80 g) in 50
The mixture was placed in a 0 ml round-bottom flask and heated from room temperature to 160 ° C. over 1 hour under a normal pressure and nitrogen atmosphere.
After maintaining at 1 ° C. for 1 hour, the pressure was gradually reduced from normal pressure to 10 mmHg over 2 hours while maintaining 160 ° C., and finally, the reaction was carried out at 160 ° C./10 mmHg for 6 hours.
The molecular weight at this time was 8,200. Thereafter, the reaction solution was discharged into an enamel vat and cooled to 30 ° C. to obtain 67.7 g (yield 94.0%) of a prepolymer. This prepolymer is pulverized in a mortar and then sieved to obtain a particle diameter of 0.1.
A granular prepolymer of 5 to 2 mm was obtained. 20.00 g of this prepolymer was charged into 80 g of water at 50 ° C., and crystallized for 60 minutes with stirring. 5.00 g of the prepolymer dried in an inert oven at 60 ° C. was added to SU
S (stainless steel) vertical reactor, charged 1
Solid phase polymerization is carried out at 40 ° C./nitrogen flow rate 200 [ml / min] for 80 hours to obtain aliphatic polyester (polylactic acid)
4.77 g (95.4% yield) was obtained. The aliphatic polyester (polylactic acid) was fused. The nitrogen gas used had a dew point of -60 ° C. The properties of the aliphatic polyester obtained by the solid-state polymerization are as follows. Weight average molecular weight (Mw) = 133,000 Catalyst concentration C _A = 1774 [ppm] (Sulfur analysis value: 33
0 [ppm]) Catalyst concentration C _B = 11200 [ppm] Residual rate of catalyst R = 15.8 [%] Retention rate of molecular weight during pressing = 70%

According to the present invention, it is possible to provide a method for easily producing an aliphatic polyester having a high molecular weight as a substitute for a general-purpose resin requiring toughness with high volumetric efficiency.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Masanobu Ajioka 30 Asmuta-cho, Omuta-shi, Fukuoka Prefecture Mitsui Chemicals Co., Ltd. (72) Inventor Katsuyuki Sakai 6-1-2 Waki-machi, Kuki-gun, Yamaguchi Prefecture Mitsui Chemicals Co., Ltd. (72) Inventor Hiroyuki Suzuki 30 Asamuta-cho, Omuta-shi, Fukuoka Mitsui Chemical Co., Ltd. (72 ) Inventor Ryo Shinagawa 30 Mitsui Chemicals Co., Ltd., Omuta-shi, Fukuoka Prefecture (72) Inventor Shinji Ogawa 30 Asamuta-cho, Omuta-shi, Fukuoka Prefecture In Mitsui Chemicals Co., Ltd. (72) Inventor Yasushi Kotaki 30 Muta-cho Mitsui Chemicals F-term (reference) 4J029 AA01 AA02 AA05 AB04 AC01 AD01 CA04 EA05 FC05 FC08 JC361 JF371 KD01 KD02 KE12 KF02 KF07 KF09

Claims (17)

[Claims] 1. A weight within a numerical range represented by equation (1).
Weight average molecular weight (Mw ₁) Having a crystallized aliphatic arsenic
Aliphatic resin containing at least 50% of a droxycarboxylic acid unit
Solid-state polymerization of ester prepolymer in the presence of catalyst
During the solid phase polymerization, the solid state polymerization temperature (reaction temperature)
Equations (2) and (3) characterized by being changed
Weight average molecular weight that simultaneously satisfies the numerical range indicated by
(Mw_Two) Having an aliphatic hydroxycarboxylic acid unit
Solid state polymerization of aliphatic polyester containing 50% or more
Law. 2 × 10^Three ≤ Mw₁ ≦ 1 × 10^Five (1) 5 × 10^Four ≤ Mw_Two ≦ 1 × 10⁶ (2) Mw₁ <Mw_Two (3) 2. The method for solid-state polymerization of an aliphatic polyester according to claim 1, wherein changing the solid-state polymerization temperature (reaction temperature) is increasing the temperature. 3. Changing the solid-state polymerization temperature (reaction temperature) is to start the solid-state polymerization at a solid-state polymerization temperature (reaction temperature) (T ₁ ) within the numerical range represented by Formula (4). The fat according to claim 1, wherein during the solid phase polymerization, the fat is changed to a solid phase polymerization temperature (reaction temperature) (T ₂ ) within a numerical range represented by Expressions (5) and (6). A method for solid-state polymerization of an aromatic polyester. _{100 ℃ ≦ T 1 ≦ 130 ℃} (4) 120 ℃ ≦ T 2 <170 ℃ (5) T 1 <T 2 (6) 4. Changing the solid-state polymerization temperature (reaction temperature) starts the solid-state polymerization at a solid-state polymerization temperature (reaction temperature) (T ₃ ) within the numerical range represented by the equation (7). During the solid-phase polymerization, the solid-state polymerization temperature (reaction temperature) (T ₄ ) within the numerical range represented by the mathematical formulas (8) and (10), and the mathematical formulas (9) and (10) are given. is to change to the solid state polymerization temperature in the numerical range (reaction temperature) (T _5), the solid-phase polymerization process of aliphatic polyester according to claim 1. _{100 ℃ ≦ T 3 ≦ 130 ℃} (7) 120 ℃ ≦ T 4 ≦ 160 ℃ (8) 140 ℃ ≦ T 5 <170 ℃ (9) T 3 <T 4 <T 5 (10) 5. The method for solid-state polymerization of an aliphatic polyester according to claim 1, wherein the catalyst is a volatile catalyst. 6. The method for producing an aliphatic polyester according to claim 5, wherein the volatile catalyst has a catalyst residual ratio R of 50% or less, which is represented by Formula (11). R [%] = C _A [ppm] ÷ C _B [ppm] × 100 (11) (In the formula (11), R is a catalyst residual ratio [%] which is a measure of a change in the catalyst concentration before and after the solid-state polymerization reaction. And the C _B [ppm] is calculated by the formula (12), and the catalyst charged into the reaction system before the solid-state polymerization and / or during the solid-state polymerization reaction remains in the aliphatic polyester. Is the theoretical catalyst concentration in the case, and C _A [ppm] is the catalyst concentration in the aliphatic polyester finally obtained after the solid-state polymerization reaction, which is calculated by Expression (13).) C _B [ppm] = W in _{B [g] ÷ W P [} g] × 10 6 (12) ( equation _{(12), W B [g} ] is a solid phase prior to polymerization,
And / or the total weight of the catalyst charged into the reaction system during the solid-state polymerization reaction, and W _P [g] is
It is the weight of the aliphatic polyester finally obtained. ) C _A [ppm] = W _A [g] ÷ W _P [g] × 10 ⁶ (13) (In the formula (13), W _A [g] is finally obtained after the solid-state polymerization reaction is completed. and a catalyst weight contained in the aliphatic polyester, W _P [g] after solid-phase polymerization reaction was completed, the weight of the finally obtained aliphatic polyester.) 7. The method for solid-state polymerization of an aliphatic polyester according to claim 5, wherein the volatile catalyst is an organic sulfonic acid-based compound. 8. An organic sulfonic acid-based compound comprising: methanesulfonic acid, ethanesulfonic acid, 1-propanesulfonic acid,
The benzene sulfonic acid, p-toluene sulfonic acid, m-xylene-4-sulfonic acid, p-chlorobenzene sulfonic acid, and at least one selected from the group consisting of 2,5-dichlorobenzene sulfonic acid. Solid-state polymerization method of a modified aliphatic polyester. 9. The method for solid-state polymerization of an aliphatic polyester according to claim 7, wherein the catalyst concentration in the finally obtained aliphatic polyester is 0 to 300 ppm in terms of sulfur content. 10. The method for solid-state polymerization of an aliphatic polyester according to claim 1, wherein the catalyst is a nonvolatile catalyst. 11. The method according to claim 1, wherein the non-volatile catalyst is metallic tin or tin oxide (I
The method for solid-phase polymerization of an aliphatic polyester according to claim 10, which is I). 12. The crystallized aliphatic polyester prepolymer is obtained by bringing an aliphatic polyester prepolymer in a solid state into contact with a liquid that does not dissolve the aliphatic polyester prepolymer, thereby crystallizing the aliphatic polyester prepolymer. A method for solid-state polymerization of an aliphatic polyester according to claim 1. 13. A crystallized aliphatic polyester prepolymer is obtained by contacting a molten aliphatic polyester prepolymer with a liquid that does not dissolve the aliphatic polyester prepolymer, thereby solidifying and crystallizing the aliphatic polyester prepolymer. The method for solid-phase polymerization of an aliphatic polyester according to claim 1, wherein 14. A method in which a crystallized aliphatic polyester prepolymer is solidified and crystallized by bringing a solution in which an aliphatic polyester prepolymer is dissolved in a solvent into contact with a liquid in which the aliphatic polyester prepolymer is not dissolved. The method for solid-phase polymerization of an aliphatic polyester according to claim 1, which is obtained by the following method. 15. The method for solid-state polymerization of an aliphatic polyester according to claim 12, wherein the liquid contains water at least in part. 16. The solid phase polymerization method for an aliphatic polyester according to claim 1, wherein the aliphatic polyester prepolymer is polylactic acid. 17. The aliphatic polyester prepolymer,
The aliphatic polyester according to claim 1 or 9, which is a star polymer comprising L-lactic acid, pentaerythritol and succinic acid, or a star polymer comprising L-lactic acid, trimethylolpropane and succinic acid. Solid state polymerization method.