JP2005298605A - Method for producing aliphatic polyhydroxycarboxylic acid - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing an aliphatic polyhydroxycarboxylic acid having such a high molecular weight as capable of substituting for general-purpose resins by exhibiting a a high polymerization rate in production while use of flow gas is decreased. <P>SOLUTION: The method for producing the aliphatic polyhydroxycarboxylic acid is characterized by producing it in at least some steps of polycondensation reaction, by solidus polymerization of a crystallized aliphatic polyhydroxycarboxylic acid prepolymer at a temperature keeping solid state under a pressure condition of &le;1 kPa in the gas flow of &ge;90 m/hr empty column velocity, when producing the aliphatic polyhydroxycarboxylic acid by polycondensation. <P>COPYRIGHT: (C)2006,JPO&amp;NCIPI

Description

  The present invention relates to a method for producing an aliphatic polyhydroxycarboxylic acid. More specifically, the present invention relates to a method for producing a high molecular weight aliphatic polyhydroxycarboxylic acid by solid phase polymerization under reduced pressure conditions and under flowing gas.

Plastics have the advantages of being light and durable, being inexpensive and capable of being supplied in large quantities, and have brought richness and convenience to social life. However, in recent years, from the viewpoint of protecting the natural environment, the problem of plastic waste has been raised, and a polymer that decomposes in the natural environment and a molded body thereof have been demanded. Since aliphatic polyhydroxycarboxylic acids have the property of easily degrading under natural environment, they have recently attracted attention as polymer materials for materials such as containers, films, sheets, etc., and various polymers have been developed. It has been.
For example, as a method for producing a high molecular weight aliphatic polyhydroxycarboxylic acid, a hydroxycarboxylic acid and / or a derivative thereof is once subjected to dehydration condensation and then thermally decomposed to produce a hydroxycarboxylic acid cyclic dimer ester. A method of ring-opening polymerization in the presence of is known (for example, see Patent Document 1).

However, although this method has an advantage that a high molecular weight product can be obtained, there is a problem that the resin is pyrolyzed and carbonized in the step of producing a hydroxycarboxylic acid cyclic dimer ester. In the step of purifying the dimer ester, there are problems such as a complicated management method for stably maintaining the purity of the cyclic ester.
As a method for producing a high molecular weight aliphatic polyhydroxycarboxylic acid, a method in which a raw material containing a hydroxycarboxylic acid and / or a derivative thereof is directly polycondensed is also known.
Examples of the polycondensation method include (a) a so-called melt polymerization method in which a polycondensation reaction is performed at a temperature equal to or higher than the melting point of the resin, (b) a so-called solution polymerization method in which a polycondensation reaction is performed in the presence of an organic solvent, c) There is a so-called solid phase polymerization method in which a polycondensation reaction is performed while maintaining a solid state below the melting point of the resin.

However, among these polymerization methods, the method of producing a high molecular weight aliphatic polyhydroxycarboxylic acid by the melt polymerization method increases the viscosity of the polymerization system as the degree of polymerization increases, and low molecular weight components such as reaction by-product water As a result, it was difficult to distill out of the system, and it was difficult to increase the degree of polymerization. Further, the solution polymerization method has problems such as poor volumetric efficiency, requires equipment such as dehydration drying, separation or recovery, and purification of the organic solvent, and further residual solvent in the resin. It was.
On the other hand, the solid phase polymerization method is an excellent method having advantages such as high volumetric efficiency and has already been disclosed in some ways.

For example, Patent Document 2 is characterized in that, when an aliphatic polyester is produced by dehydration polycondensation of hydroxycarboxylic acid, heat dehydration is performed in the presence of a germanium compound in an inert gas stream or under reduced pressure. A method for producing an aliphatic polyester is disclosed. The publication describes that the obtained aliphatic polyester can be further subjected to solid-phase polymerization or the like to further increase the molecular weight, but the high molecular weight aliphatic having sufficient mechanical properties is described. Polyhydroxycarboxylic acid has not been obtained. Further, details of the solid-state polymerization conditions are not described.
Patent Document 3 proposes a method for producing an aliphatic polyester characterized in that glycol is added when producing an aliphatic polyester by polycondensation of glycolic acid and / or lactic acid. Describes that solid phase polymerization can be carried out as part of the polycondensation reaction, but has not yet yielded a high molecular weight aliphatic polyhydroxycarboxylic acid having sufficient mechanical properties. Further, there is no description of the details of the solid phase polymerization method, and only the method of solid phase polymerization under reduced pressure conditions is described.

  Furthermore, in Patent Document 4, in a method for producing a polyhydroxycarboxylic acid including a solid-phase polymerization step, a granular material of polyhydroxycarboxylic acid is heated at a temperature not lower than the glass transition temperature and not higher than the melting point under stirring conditions. There has been proposed a method for producing a polyhydroxycarboxylic acid, which is heated and crystallized to a granular material having thermal properties, then heated to a solid phase polycondensation reaction temperature, and then solid phase polycondensed. Patent Document 5 proposes a method in which a glycolic acid alkyl ester is polycondensed to produce a prepolymer, and solid phase polymerization is performed at a temperature at which the prepolymer maintains a solid state. Patent Document 6 discloses a method in which glycolic acid obtained by hydrolyzing at least part of an alkyl ester of glycolic acid is polycondensed to produce a prepolymer, and solid-phase polymerization is performed at a temperature at which the prepolymer maintains a solid state. Has been proposed. In these publications, there is a description that solid-phase polymerization may be carried out under reduced pressure or under an inert gas atmosphere. No details regarding speed are given.

Examples of these patent documents include a weight average molecular weight obtained by gel permeation chromatography (GPC) using polymethyl methacrylate (PMMA) having a known molecular weight as a standard substance and hexafluoroisopropanol (HFIP) as a solvent. After preparing a crystallized prepolymer having a molecular weight of 48,000 to 62,000, the same measurement was performed by solid-phase polymerization for 30 to 40 hours under conditions of 0.1 mbar or nitrogen gas flow. It is shown that polyglycolic acid having a weight average molecular weight of up to 451,000 was obtained by the method.
In general, when the molecular weight of polyamide or the like is measured by GPC method using hexafluoroisopropanol as a solvent, the salt is measured by dissolving a salt such as sodium trifluoroacetate in hexafluoroisopropanol.

  In view of this point, the present inventors set the molecular weight of a glycolic acid polymer containing about 80 mol% or more of a glycolic acid unit, HFIP in which the polymer is soluble as a solvent, and further adding PMMA having a known molecular weight. When measuring as a standard substance, the molecular weight measurement obtained varies greatly depending on the presence or absence of sodium trifluoroacetate dissolved in HFIP or the concentration of sodium trifluoroacetate dissolved in HFIP solvent. When measuring using an eluent that does not contain sodium trifluoroacetate or an eluent with a low content of the compound, the numerical value is not reproducible and the measured value of the molecular weight is extremely large. I found.

  Furthermore, as a result of repeated attempts by the inventors to produce polyglycolic acid according to the examples of Patent Document 5 and Patent Document 6, respectively, the weight in GPC using HFIP not containing sodium trifluoroacetate as a solvent was determined. The value obtained by repeatedly measuring the average molecular weight was 7,000 to 70,000 for the prepolymer, and 200,000 to 500,000 for the polyglycolic acid after the solid phase polymerization. However, the weight average molecular weight measured with GPC using HFIP in which 80 mM sodium trifluoroacetate is dissolved is a weight average molecular weight of the crystallized prepolymer of 10,000 or less. With respect to glycolic acid, the molecular weight obtained varies greatly, and all have low values of 55,000 or less. Further, the molded product obtained by molding the obtained polyglycolic acid did not have such strength that it could be substituted for a general-purpose resin.

  Patent Document 7 uses a main raw material having an impurity content of a specific amount or less, and in the presence or absence of a reducing agent, in the presence of a polymerization catalyst, at least a part of the polymerization reaction is carried out by a solid phase polymerization reaction. A method for producing a biodegradable aliphatic polyester has been proposed. Further, in Patent Document 8, a main raw material having a very small specific impurity content is used, a polymerization reaction is performed in the presence or absence of a reducing agent and in the presence of a specific polymerization catalyst, and at least one polymerization reaction is performed. A method for producing a biodegradable aliphatic polyester in which a part is subjected to a solid phase polymerization reaction has been proposed. Further, Patent Literature 9, Patent Literature 10, and Patent Literature 11 disclose a crystallized aliphatic polyester prepolymer containing 50% or more of hydroxycarboxylic acid units and having a weight average molecular weight of 2,000 to 100,000. There has been proposed a method for producing an aliphatic polyester having a weight average molecular weight of 50,000 or more and 1,000,000 or less by solid-phase polymerization in the presence thereof. However, in the method described in the above publication, in order to produce an aliphatic polyhydroxycarboxylic acid having a relatively high molecular weight, a long reaction time is required under heating and under an inert gas flow such as nitrogen. .

  On the other hand, in order to increase the reaction rate and perform the reaction efficiently, it was necessary to circulate a large amount of inert gas. When a large amount of inert gas is used in this way, it is industrially necessary to dehumidify the inert gas and circulate it. As the method, for example, the inert gas is passed through a layer filled with molecular sieves or an apparatus cooled to a very low temperature. However, at this time, cyclic esters that are by-produced during the solid-phase polymerization reaction of the aliphatic hydroxycarboxylic acid and distill with the inert gas are contained in the molecular sieve layer or inside the apparatus cooled to a cryogenic temperature. There is a tendency to accumulate, and problems such as deterioration of long-term continuous operation occur. For this reason, when producing an aliphatic polyhydroxycarboxylic acid having a high molecular weight by solid phase polymerization, it has been required to reduce the amount of nitrogen used while maintaining a high reaction rate.

  On the other hand, Patent Documents 7 and 8 have a description that solid phase polymerization may be carried out under reduced pressure and / or in an inert gas atmosphere. Further, in Patent Documents 9, 10, and 11, further, when performing solid-phase polymerization in a flowing gas atmosphere, the flow rate of the flowing gas per unit resin, unit time, and the flow gas linear velocity are further described. There is a description. However, there is no description or suggestion of details regarding conditions such as pressure and flow gas linear velocity when solid-state polymerization is performed under reduced pressure conditions while flowing gas.

Japanese Unexamined Patent Publication No. 63-17929 Japanese Patent Laid-Open No. 5-43665 JP-A-1-156319 JP 2001-64375 A JP-A-11-116666 JP-A-11-130847 JP 2001-114882 A JP 2001-114883 A JP 2000-302852 A JP 2001-192444 A JP 2001-122594 A

  An object of the present invention is to provide a method for producing a high molecular weight aliphatic polyhydroxycarboxylic acid that can replace a general-purpose resin at a high polymerization rate while reducing the amount of gas used.

  As a result of intensive investigations to solve the above problems, the present inventors have determined that the pressure range is a specific pressure or lower when solid-state polymerization of the crystallized aliphatic polyhydroxycarboxylic acid prepolymer under gas flow is performed. As a result, it was found that a large difference was observed in the behavior of the polycondensation reaction. As a result of further investigations, high-molecular-weight fats can be obtained at a very high polymerization rate with a low nitrogen flow rate by conducting a solid-phase polymerization reaction under conditions of a specific pressure or lower and a gas with a specific superficial velocity. It discovered that group polyhydroxycarboxylic acid could be manufactured and the said subject could be solved.

That is, the present invention relates to the following items 1) to 10).
1) In producing an aliphatic polyhydroxycarboxylic acid by polycondensation, at least part of the polycondensation reaction, the crystallized aliphatic polyhydroxycarboxylic acid prepolymer is subjected to 90 m under a pressure condition of 1 kPa or less. A method for producing an aliphatic polyhydroxycarboxylic acid, which comprises solid-phase polymerization at a temperature that maintains a solid state while allowing a gas to flow at a superficial velocity of at least / hr.
2) The method for producing an aliphatic polyhydroxycarboxylic acid as described in 1) above, wherein the superficial velocity at which the gas flows is 250,000 m / hr or less.
3) The process for producing an aliphatic polyhydroxycarboxylic acid according to 1) or 2) above, wherein the gas flow rate is 50 liter / hr or less per 1 kg of the aliphatic polyhydroxycarboxylic acid.
4) The method for producing an aliphatic polyhydroxycarboxylic acid according to any one of 1) to 3) above, wherein solid phase polymerization is performed in a fixed bed reactor.
5) The method for producing an aliphatic polyhydroxycarboxylic acid according to any one of 1) to 3) above, wherein solid phase polymerization is performed in a moving bed reactor.
6) The method for producing an aliphatic polyhydroxycarboxylic acid as described in 5) above, wherein the solid phase polymerization is carried out by bringing an aliphatic polyhydroxycarboxylic acid prepolymer into alternating current contact with a flowing gas.
7) The process for producing an aliphatic polyhydroxycarboxylic acid according to any one of 1) to 6) above, wherein solid phase polymerization is performed in a column reactor.
8) The aliphatic polyhydroxy of any one of 1) to 7) above, wherein the crystallized aliphatic polyhydroxycarboxylic acid prepolymer has a weight average molecular weight of 25,000 or more. A method for producing carboxylic acid.
9) The production of an aliphatic polyhydroxycarboxylic acid according to any one of 1) to 8) above, wherein the aliphatic polyhydroxycarboxylic acid contains 80 mol% or more of an aliphatic hydroxycarboxylic acid unit. Method.
10) The method for producing an aliphatic polyhydroxycarboxylic acid according to any one of 1) to 9) above, wherein the aliphatic polyhydroxycarboxylic acid contains 80 mol% or more of a glycolic acid unit.

  According to the method of the present invention, a high-molecular weight aliphatic polyhydroxycarboxylic acid that can be substituted for general-purpose resins such as packaging materials, agricultural materials, civil engineering and building materials, and machine parts, reduces the amount of gas used. Thus, it is possible to produce at a high polymerization rate by a simple method excellent in continuous stability.

Hereinafter, embodiments of the present invention will be described in detail.
The aliphatic polyhydroxycarboxylic acid in the present invention refers to a crystallizable resin containing an aliphatic hydroxycarboxylic acid unit as a main repeating unit structure.
When the content of the aliphatic hydroxycarboxylic acid unit is less than 50 mol%, the crystallinity is remarkably lowered, and the aliphatic polyhydroxycarboxylic acid shaped product may be extremely firmly fused during solid phase polymerization. The content of the aliphatic hydroxycarboxylic acid unit in the aliphatic polyhydroxycarboxylic acid is preferably 80 mol% or more.
Such aliphatic polyhydroxy carboxylic acids may be homopolymers, copolymers or mixtures thereof consisting of aliphatic hydroxy carboxylic acid units.

Furthermore, as other copolycondensation units, a compound unit capable of copolycondensation with an aliphatic hydroxycarboxylic acid and / or a derivative thereof, for example, a copolymer containing a polyol unit and / or a polycarboxylic acid unit, or a mixture thereof Furthermore, it may be a mixture with a homopolymer or copolymer comprising the above aliphatic hydroxycarboxylic acid units.
The copolymer used in the present invention may be a random copolymer, a block copolymer, an alternating copolymer, or a graft copolymer. Further, the mixture includes the concept of polymer blend and polymer alloy.
The aliphatic polyhydroxycarboxylic acid used in the present invention can be produced by a conventionally known production method.

  For example, when the aliphatic polyhydroxycarboxylic acid is a homopolymer or copolymer of aliphatic hydroxycarboxylic acid units, one or more hydroxycarboxylic acids and / or derivatives thereof in the presence or absence of a catalyst In addition, for example, an aliphatic polyhydroxycarboxylic acid can be copolycondensed with an aliphatic hydroxycarboxylic acid unit and a polyol unit and / or an aliphatic hydroxycarboxylic acid such as a polycarboxylic acid unit and / or a derivative thereof. In the absence or presence of a solvent, in the presence or absence of a catalyst, and one or more aliphatic hydroxycarboxylic acids and / or derivatives thereof, Copolycondensation with aliphatic hydroxycarboxylic acids such as polyols and / or polycarboxylic acids and / or their derivatives In the absence or presence of a solvent, in the presence or absence of a catalyst, one or more aliphatic hydroxycarboxylic acids and / or their derivatives, diols and polycondensates. It can be produced by a method such as polycondensation with an aliphatic polyester comprising carboxylic acid.

Furthermore, a state in which an aliphatic polyhydroxycarboxylic acid and another polyester, for example, a polyester composed of a polyol and a polycarboxylic acid, or a polyester composed of an aliphatic hydroxycarboxylic acid and a polyol and / or a polycarboxylic acid are heated and melted. Thus, if necessary, it can also be produced by a method of performing a transesterification reaction or the like.
Among the above-mentioned methods for producing an aliphatic polyhydroxycarboxylic acid, a method for producing an aliphatic polyhydroxycarboxylic acid by polycondensation is preferably used because the aliphatic polyhydroxycarboxylic acid can be produced with a small number of steps.

  Examples of the aliphatic hydroxycarboxylic acid used as a raw material when producing the aliphatic polyhydroxycarboxylic acid include glycolic acid, lactic acid, 2-hydroxybutanoic acid, 2-hydroxypentanoic acid, and 2-hydroxyhexanoic. Acid, 2-hydroxyheptanoic acid, 2-hydroxyoctanoic acid, 2-hydroxy-2-methylpropanoic acid, 2-hydroxy-2-methylbutanoic acid, 2-hydroxy-2-ethylbuta Noic acid, 2-hydroxy-2-methylpentanoic acid, 2-hydroxy-2-ethylpentanoic acid, 2-hydroxy-2-propylpentanoic acid, 2-hydroxy-2-butylpentanoic Acid, 2 − Hydroxy-2-methylhexanoic acid, 2-hydroxy-2-ethylhexanoic acid, 2-hydroxy-2-propylhexanoic acid,

  2-hydroxy-2-butylhexanoic acid, 2-hydroxy-2-pentylhexanoic acid, 2-hydroxy-2-methylheptanoic acid, 2-hydroxy-2-methylheptanoic acid, 2- Hydroxy-2-ethylheptanoic acid, 2-hydroxy-2-propylheptanoic acid, 2-hydroxy-2-butylheptanoic acid, 2-hydroxy-2-pentylheptanoic acid, 2-hydroxy-2 -Hexylheptanoic acid, 2-hydroxy-2-methyloctanoic acid, 2-hydroxy-2-ethyloctanoic acid, 2-hydroxy-2-propyloctanoic acid, 2-hydroxy-2-butyl Octanoic acid, 2-hydride Loxy-2-pentyloctanoic acid, 2-hydroxy-2-hexyloctanoic acid, 2-hydroxy-2-heptyloctanoic acid,

  3-hydroxypropanoic acid, 3-hydroxybutanoic acid, 3-hydroxypentanoic acid, 3-hydroxyhexanoic acid, 3-hydroxyheptanoic acid, 3-hydroxyoctanoic acid, 3- Hydroxy-3-methylbutanoic acid, 3-hydroxy-3-methylpentanoic acid, 3-hydroxy-3-ethylpentanoic acid, 3-hydroxy-3-methylhexanoic acid, 3-hydroxy- 3-ethylhexanoic acid, 3-hydroxy-3-propylhexanoic acid, 3-hydroxy-3-methylheptanoic acid, 3-hydroxy-3-ethylheptanoic acid, 3-hydroxy-3- Propyl heptanoic Acid, 3-hydroxy-3-butylheptanoic acid, 3-hydroxy-3-methyloctanoic acid, 3-hydroxy-3-ethyloctanoic acid, 3-hydroxy-3-propyloctanoic acid, 3-hydroxy-3-butyloctanoic acid, 3-hydroxy-3-pentyloctanoic acid,

  4-hydroxybutanoic acid, 4-hydroxypentanoic acid, 4-hydroxyhexanoic acid, 4-hydroxyheptanoic acid, 4-hydroxyoctanoic acid, 4-hydroxy-4-methylpentanoic Acid, 4-hydroxy-4-methylhexanoic acid, 4-hydroxy-4-ethylhexanoic acid, 4-hydroxy-4-methylheptanoic acid, 4-hydroxy-4-ethylheptanoic acid, 4-hydroxy-4-propylheptanoic acid, 4-hydroxy-4-methyloctanoic acid, 4-hydroxy-4-ethyloctanoic acid, 4-hydroxy-4-propyloctanoic acid, 4- Hydroxy-4-bu Le-octanoic acid, 5-hydroxy-pentanoic acid, 5-hydroxy hexanoic acid, 5-hydroxy-heptanoate dichroic acid, 5-hydroxy-octanoic acid, 5-hydroxy-5-methyl-hexanoic acid,

  5-hydroxy-5-methylheptanoic acid, 5-hydroxy-5-ethylheptanoic acid, 5-hydroxy-5-methyloctanoic acid, 5-hydroxy-5-ethyloctanoic acid, 5- Hydroxy-5-propyloctanoic acid, 6-hydroxyhexanoic acid, 6-hydroxyheptanoic acid, 6-hydroxyoctanoic acid, 6-hydroxy-6-methylheptanoic acid, 6- Hydroxy-6-methyloctanoic acid, 6-hydroxy-6-ethyloctanoic acid, 7-hydroxyheptanoic acid, 7-hydroxyoctanoic acid, 7-hydroxy-7-methyloctanoic acid, 8-hydroxyoctano Aliphatic monohydroxy monocarboxylic acid such as uck acid, 12-hydroxy stearic acid, 16-hydroxy hexadecanoic acid, 2-hydroxy ethoxy acetic acid, 2-hydroxy propoxy acetic acid, etc. Hydroxy monocarboxylic acid etc. can be mentioned.

Furthermore, aliphatic polyhydroxyhydroxycarboxylic acids such as glyceric acid, aravic acid, mannonic acid, galactonic acid, aliphatic monohydroxypolycarboxylic acids such as malic acid and citric acid, fats such as diglyceric acid and mannose sugar It is also possible to use a group polyvalent hydroxy polyvalent carboxylic acid in combination.
Examples of the derivative of the aliphatic hydroxycarboxylic acid used for producing the aliphatic polyhydroxycarboxylic acid include polycondensates of the above aliphatic hydroxycarboxylic acids and the above hydroxycarboxylic acids and 1 to 10 carbon atoms. Monofunctional alcohols such as esters with methanol, ethanol, propanol, isopropanol, butanol, pentanol, hexanol, octanol, etc., and cyclic dimer esters comprising glycolide, lactide, glycolic acid and lactic acid, etc. Examples include cyclic dimer esters composed of aliphatic hydroxycarboxylic acids, and lactones that are cyclic esters of aliphatic hydroxycarboxylic acids such as β-propiolactone, γ-butyrolactone, δ-valerolactone, and ε-caprolactone. . These may be used alone or in combination of two or more. Any compound having an asymmetric carbon atom in the unit structure and having an optical isomer can be used.

Here, the polycondensate in the present invention means a polycondensate capable of further polycondensation.
In the present invention, other copolycondensation components that can be used together with the aliphatic hydroxycarboxylic acid and / or its derivative include, for example, aromatic hydroxycarboxylic acid and / or its derivative, polyol, polycarboxylic acid and / or its derivative Derivatives, amino acids, polyvalent amines, lactams and the like can be mentioned. Such copolycondensation components may be used alone or in combination of two or more.

  Examples of the aromatic hydroxycarboxylic acid that can be used as a copolymerization component when producing an aliphatic polyhydroxycarboxylic acid include aromatic monohydroxymonocarboxylic acids such as hydroxybenzoic acid, 2,3-dihydroxybenzoic acid, 2 , 4-dihydroxybenzoic acid, 2,5-dihydroxybenzoic acid, 2,6-dihydroxybenzoic acid, 3,4-dihydroxybenzoic acid, 3,5-dihydroxybenzoic acid and other aromatic polyvalent hydroxymonocarboxylic acids, 4 -Aromatic monohydroxy polyvalent carboxylic acids such as hydroxyisophthalic acid and 5-hydroxyisophthalic acid, aromatic polyvalent hydroxy polyvalent carboxylic acids such as 2,5-dihydroxyterephthalic acid, glyceric acid, alabonic acid, mannonic acid, galactone Aliphatic polyhydroxymonocarboxylic acids such as acids, malic acid, citric acid, etc. Aliphatic monohydroxy polycarboxylic acid, diglycerin acid, polyhydroxy polycarboxylic acids such as manno sugar acid.

Examples of the derivative of the aromatic hydroxycarboxylic acid used for producing the aliphatic polyhydroxycarboxylic acid include, for example, the above polycondensates of the aromatic hydroxycarboxylic acid, the above hydroxycarboxylic acid and the carbon number of 1 to 10 And monofunctional alcohols such as esters with methanol, ethanol, propanol, isopropanol, butanol, pentanol, hexanol, octanol and the like. These may be used alone or in combination of two or more. Any compound having an asymmetric carbon atom in the unit structure and having an optical isomer can be used.
Examples of the polyol that can be used as a copolymerization component when producing an aliphatic polyhydroxycarboxylic acid include compounds containing two or more hydroxyl groups in one molecule, and a polyol having 2 to 20 carbon atoms is preferable.

  Examples of such polyols include ethylene glycol, 1,3-propanediol, 1,2-propanediol, 1,4-butanediol, 2,3-butanediol, 1,5-pentanediol, 1,6- Hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,12-dodecanediol, 1,4-cyclohexanediol, 1,2-cyclohexane Diols, aliphatic diols such as 1,3-cyclohexanediol, neopentyl glycol, bisphenol A, catechol, resorcinol, 1,2-benzenedimethanol, 1,3-benzenedimethanol, 1,4-benzenedimethanol, etc. Aromatic diols, and further diols containing heteroatoms, eg , Diethylene glycol, triethylene glycol, tetraethylene glycol, tetramethylene glycol,

Aliphatic diols such as polytetramethylene glycol having a hydroxyl group of 99% or more of the terminal, glycerin, 1,2,4-butanetriol, trimethylolethane, trimethylolpropane, butane-1,2,3-triol Aliphatic triol such as 1,2,4-benzenetriol, aromatic triol such as 1,3,5-benzenetriol, starch, glucose, cellulose, hemicellulose, xylose, arabinose, mannose, galactose, xylitol, arabinitol, mannitol , Sugars such as galactitol, pentaerythritol, chitin, chitosan, dextrin, dextran, carboxymethylcellulose, amylopectin, glycogen and the like.
These may be used alone or in combination of two or more. Of these, any compound having an asymmetric carbon atom in the molecule and having an optical isomer can be used.

  Among these, considering the side reaction during polycondensation, or considering the thermal decomposability at the time of melt molding of the resulting copolymer, or heat aging resistance, the polyol may be a diol having 3 or more carbon atoms, for example, 1,3-propanediol, 1,2-propanediol, 1,4-butanediol, 2,3-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1 , 8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,12-dodecanediol, 1,4-cyclohexanediol, 1,2-cyclohexanediol, 1,3-cyclohexanediol, neopentyl Aliphatic diols such as glycol and tetramethylene glycol, bisphenol A, catechol, resorcinol, 1, - benzene dimethanol, 1,3-benzene dimethanol, aromatic diols such as 1,4-benzene dimethanol, more preferably used.

The polycarboxylic acid that can be used as a copolymerization component when producing an aliphatic polyhydroxycarboxylic acid is one containing two or more carboxyl group units in one molecule, and having 2 to 20 carbon atoms. Carboxylic acid is preferred.
Examples of such polycarboxylic acids include oxalic acid, malonic acid, glutaric acid, succinic acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, fumaric acid, maleic acid , Diglycolic acid, aliphatic dicarboxylic acid such as 1,4-cyclohexanedicarboxylic acid, aromatic dicarboxylic acid such as phthalic acid, isophthalic acid, terephthalic acid, propanetricarboxylic acid, trimellitic acid, pyromellitic acid, 1,3, Aliphatic tricarboxylic acids such as 6-hexane tricarboxylic acid, aromatic tricarboxylic acids such as 1,2,3-benzenetricarboxylic acid, 1,2,4-benzenetricarboxylic acid, 1,3,5-benzenetricarboxylic acid, ethylenediamine And tetracarboxylic acid such as acetic acid. These can be used alone or in admixture of two or more.

Examples of polycarboxylic acid derivatives include esters and glycols of the corresponding polycarboxylic acids and monofunctional alcohols having 1 to 10 carbon atoms, such as methanol, ethanol, propanol, isopropanol, butanol, pentanol, hexanol, octanol and the like. Examples thereof include esters with acids and corresponding derivatives of polycarboxylic acid anhydrides.
Among these polycarboxylic acids, more preferably, oxalic acid, malonic acid, glutaric acid, succinic acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, diglycolic acid , Aliphatic dicarboxylic acids such as 1,4-cyclohexanedicarboxylic acid and / or derivatives thereof, aromatic dicarboxylic acids such as phthalic acid, isophthalic acid and terephthalic acid and / or derivatives thereof, propanetricarboxylic acid, trimellitic acid, pyromellitic Acid, aliphatic tricarboxylic acid such as 1,3,6-hexanetricarboxylic acid and / or its derivative, 1,2,3-benzenetricarboxylic acid, 1,2,4-benzenetricarboxylic acid, 1,3,5-benzene Aromatic tricarboxylic acids such as tricarboxylic acids and / or derivatives thereof are used.

As an amino acid that can be used as a copolymerization component when producing an aliphatic polyhydroxycarboxylic acid, an amino acid having 2 to 20 carbon atoms is preferable. Examples of such amino acids include glycine, (+)-alanine, β-alanine, (−)-asparagine, (+)-aspartic acid, (−)-cysteine, (+)-glutamine, (+) — Glutamine, (−)-hydroxylysine, (−)-leucine, (+)-isoleucine, (+)-lysine, (−)-methionine, (−)-serine, (−)-threonine, (+)-valine Aminobutyric acid, azaserine, arginine, ethionine and the like.
The polyvalent amine that can be used as a copolymerization component when producing an aliphatic polyhydroxycarboxylic acid is preferably a polyvalent amine having 0 to 20 carbon atoms. Examples of such amines include hydrazine, methyl hydrazine, monomethylene diamine, dimethylene diamine, trimethylene diamine, tetramethylene diamine, pentamethylene diamine, hexamethylene diamine, heptamethylene diamine, octamethylene diamine, nonamethylene diamine, Examples include methylene diamine, undecamethylene diamine, and dodecamethylene diamine.

  As a lactam that can be used as a copolymerization component when producing an aliphatic polyhydroxycarboxylic acid, a lactam having 2 to 20 carbon atoms is preferable. Examples of such lactams include glycine anhydride, propane lactam, α-pyrrolidone, α-piperidone, ε-caprolactam, α-methyl-caprolactam, β-methyl-caprolactam, γ-methyl-caprolactam, δ-methyl-caprolactam. , Ε-methyl-caprolactam, N-methyl-caprolactam, β, γ-dimethyl-caprolactam, γ-ethyl-caprolactam, γ-isopropyl-caprolactam, ε-isopropyl-caprolactam, γ-butyl-caprolactam, γ-hexacyclobenzyl -Caprolactam, omega-enantolactam, omega-capryllactam, caprilactam, laurolactam, etc.

Any of the above compounds having an asymmetric carbon atom and capable of having an optical isomer can be used.
Copolycondensable with the above aliphatic hydroxycarboxylic acids and / or derivatives thereof, polyols, polycarboxylic acids and / or derivatives thereof, and aliphatic hydroxycarboxylic acids such as amino acids, polyvalent amines and lactams and / or derivatives thereof Such a component can be used for the production of the aliphatic polyhydroxycarboxylic acid used in the present invention in any state of solid, liquid, and aqueous solution.
The prepolymer in the present invention means a polycondensate capable of further polycondensation.

  The content of the aliphatic hydroxycarboxylic acid unit contained in the aliphatic polyhydroxycarboxylic acid prepolymer that can be used in the present invention is such that the aliphatic polyhydroxycarboxylic acid has sufficient crystallinity, From the viewpoint of suppressing the fusion of the aliphatic polyhydroxycarboxylic acid, the aliphatic hydroxycarboxylic acid unit in the aliphatic polyhydroxycarboxylic acid prepolymer needs to be 50 mol% or more. In order to increase the hardness of the granulated product and to prevent the granulated product from being damaged and the amount of fine powder generated when the granulated product is dried, crystallized or subjected to solid phase polymerization, the aliphatic hydroxycarboxylic acid unit is reduced. An aliphatic polyhydroxycarboxylic acid containing 80 mol% or more is more preferable, and an aliphatic polyhydroxycarboxylic acid containing 80 mol% or more of a glycolic acid unit is still more preferable. The aliphatic polyhydroxycarboxylic acid containing 50 mol% or more of the aliphatic hydroxycarboxylic acid unit can be produced, for example, by polycondensing a raw material containing 50 mol% or more of the aliphatic polyhydroxycarboxylic acid.

  The reaction temperature for producing the aliphatic polyhydroxycarboxylic acid prepolymer used in the present invention by polycondensation varies depending on the type and molecular weight of the target aliphatic polyhydroxycarboxylic acid prepolymer, but is not limited. 20 ° C. or higher and 350 ° C. or lower, preferably 50 ° C. or higher and 280 ° C. or lower, more preferably 80 ° C. or higher and 250 ° C. or lower. If the temperature is lower than 20 ° C., the polycondensation reaction rate is remarkably reduced, and the reaction time becomes long. On the other hand, when it exceeds 350 ° C., coloring due to thermal decomposition of the polymer tends to increase.

The atmosphere of the polycondensation reaction is, for example, nitrogen, helium, neon, argon, krypton, xenon, carbon dioxide, or lower saturation having 1 to 4 carbon atoms in order to suppress coloring of the aliphatic polyhydroxycarboxylic acid prepolymer. It is preferable to carry out under the atmosphere of 1 type, or 2 or more types of inert gas chosen from hydrocarbon etc. under pressure, circulation, and / or pressure reduction. When the reaction is carried out in a reduced pressure state, although it varies depending on the type of aliphatic polyhydroxycarboxylic acid and the operating temperature, a range of 1.333 Pa to 1.014 × 10 ⁵ Pa is usually exemplified.
When the above-mentioned aliphatic polyhydroxycarboxylic acid prepolymer is produced by polycondensation, a method which is carried out while adjusting the operation temperature and / or the operation pressure in multiple stages is a preferred mode.

  When the aliphatic polyhydroxycarboxylic acid prepolymer used in the present invention is produced by polycondensation, the use of a polycondensation reaction apparatus capable of ensuring a relatively high evaporation specific surface area is the fact that an aliphatic polyhydroxycarboxylic acid having a high molecular weight is used. This is the preferred mode because the acid can be produced. Examples of the polycondensation reaction apparatus that can ensure such a high evaporation specific surface area include, for example, a biaxial horizontal high-viscosity reactor, and a high specific surface area polymerization apparatus that has a molten polymer support such as a wire or wire mesh in its tower as its structure. The method of using is mentioned.

Furthermore, within the range of not impairing the effects of the present invention, in the middle of the polycondensation reaction, a compound having two or more isocyanate groups and / or epoxy groups in one structural unit known in the art can be added, and more easily in one hour. It is also possible to increase the molecular weight. The amount of these compounds added is usually in the range of 0.05% by mass to 5% by mass with respect to the aliphatic polyhydroxycarboxylic acid polymer.
Said polycondensation reaction can be performed combining the batch type and / or continuous type 1 type, or 2 or more types of reaction apparatus.
When the aliphatic polyhydroxycarboxylic acid prepolymer used in the present invention is produced by polycondensation, the polycondensation reaction can be carried out without adding a catalyst. The catalyst can be used.

  As the catalyst, the semimetals of Group 1, 2, 3, 4, 5, 8, 12, Group 13 excluding boron, Group 14 excluding carbon, and Group 15 excluding nitrogen are included. Examples thereof include metals, metal salts of these metals, metal oxides, metal hydroxides, metal alkoxides, and metal sulfonates. For example, metals such as titanium, zirconium, niobium, tungsten, zinc, germanium, tin, antimony, metal oxides such as magnesium oxide, titanium oxide, zinc oxide, germanium oxide, silica, alumina, tin oxide, antimony oxide, fluorination Tin, antimony fluoride, magnesium chloride, aluminum chloride, zinc chloride, stannous chloride, stannic chloride, stannous bromide, stannic bromide, aluminum sulfate, zinc sulfate, tin sulfate, magnesium carbonate, carbonic acid Metal salts such as calcium, zinc carbonate, lithium hydroxide, sodium hydroxide, potassium hydroxide, magnesium hydroxide, calcium hydroxide, strontium hydroxide, barium hydroxide, aluminum hydroxide, zirconium hydroxide, iron hydroxide, Metal hydroxides such as cobalt hydroxide, nickel hydroxide, copper hydroxide, and zinc hydroxide Metal carboxylates such as magnesium acetate, aluminum acetate, zinc acetate, tin acetate, tin octoate, tin stearate, iron lactate and tin lactate, metals such as magnesium, lanthanoid, titanium, hafnium, iron, germanium, tin and antimony Organic metal salts such as alkoxide and dibutyltin oxide, organic sulfonates such as tin methanesulfonate, tin trifluoromethanesulfonate and tin p-toluenesulfonate, and ion exchange resins such as Amberlite and Dowex.

Furthermore, inorganic acids such as hydrochloric acid, perchloric acid, nitric acid, nitrous acid, sulfuric acid, sulfurous acid, phosphoric acid, phosphorous acid, polyphosphoric acid, organic acids such as p-toluenesulfonic acid, naphthalenesulfonic acid, methanesulfonic acid, etc. Is mentioned.
The catalyst is not limited to these, and can be used alone or in combination of two or more.
These catalyst species are used, for example, by directly adding to the raw material compound or an aqueous solution of the raw material compound, or after obtaining a polycondensate, etc. After hydrolysis in the presence of water and / or aliphatic hydroxycarboxylic acid, it may be added to the raw material or polycondensate for use.

The polycondensate here is not limited in molecular weight or the like as long as further melt polymerization is possible.
The amount of the catalyst used is preferably in the range of 1 × 10 ⁻¹⁰ mol or more and 1 × 10 ⁻² mol or less as a metal atom per 1 g of the compound used as a raw material. When the amount of catalyst used per 1 g of the compound used as a raw material is less than 1 × 10 ⁻¹⁰ mol as a metal atom, the effect of increasing the polycondensation rate is not sufficiently exhibited, and exceeds 1 × 10 ⁻² mol. In some cases, side reactions such as resin coloring tend to increase remarkably.
When the aliphatic polyhydroxycarboxylic acid used in the present invention is produced by polycondensation, it is also possible to carry out the reaction by adding a coloring inhibitor in order to suppress coloring due to thermal degradation during polycondensation. The anti-coloring agent can be added to the reaction system as it is or dissolved or mixed in an appropriate liquid. There is no limitation on the addition timing of the coloring inhibitor, and it may be added to the reaction system at any timing as long as it is from the concentration or condensation process of the raw material monomer until the polycondensation reaction is substantially completed. Addition may be performed in a lump or divided.

  The heat stabilizer used for polycondensation is phosphoric acid, trimethyl phosphate, triethyl phosphate, triphenyl phosphate, polyphosphoric acid monoethyl ester, polyphosphoric acid diethyl ester, pyrophosphoric acid, triethyl pyrophosphate, pyrophosphoric acid Hexamethylamide, phosphorous acid, triethyl phosphite, triphenyl phosphite, tris (2-tert-butylphenyl) phosphite, tris (2,4-ditert-butylphenyl) phosphite, tris (2, 5-di-tert-butylphenyl) phosphite, tris (2-tert-butyl-4-methylphenyl) phosphite, tris (2-tert-butyl-5-methylphenyl) phosphite, tris (2-tert-butyl) -4,6-dimethylphenyl) phosphite, trisnonylphenylphosphine Phyto, tris (mono and dinonylphenyl) phosphite, monomethyl phosphonate, monoethyl phosphonate, monopropyl phosphonate, monoisopropyl phosphonate, monobutyl phosphonate, monopentyl phosphonate, monohexyl phosphonate, monooctyl phosphonate, phosphone Monoethylhexyl acid, monodecyl phosphonate, monoisodecyl phosphonate,

  Monoundecyl phosphonate, monododecyl phosphonate, monotetradecyl phosphonate, monohexadecyl phosphonate, monooctadecyl phosphonate, monophenyl phosphonate monobenzyl, monomethylphosphonic acid, dimethylphosphonic acid, monoethylphosphonic acid, diethylphosphone Acid, monopropylphosphonic acid, dipropylphosphonic acid, monoisopropylphosphonic acid, diisopropylphosphonic acid, monobutylphosphonic acid, dibutylphosphonic acid, monopentylphosphonic acid, dipentylphosphonic acid, monohexylphosphonic acid, dihexylphosphonic acid, isooctyl Phosphonic acid, diisooctylphosphonic acid, monooctylphosphonic acid, dioctylphosphonic acid, monoethylhexylphosphonic acid, diethylhexylphosphonic acid, monodecylphosphine Phosphate, Jideshiruhosuhon acid, monoisodecyl acid, diisodecyl phosphonate, mono-undecyl acid, diundecyl acid, mono-dodecyl phosphonic acid, didodecyl acid,

  Monotetradecylphosphonic acid, ditetradecylphosphonic acid, monohexadecylphosphonic acid, dihexadecylphosphonic acid, monooctadecylphosphonic acid, dioctadecylphosphonic acid, monophenylphosphonic acid, diphenylphosphonic acid, monobenzylphosphonic acid, Dibenzylphosphonic acid, calcium monohydrogen phosphate, calcium monohydrogen phosphate dihydrate, calcium dihydrogen phosphate, calcium dihydrogen phosphate monohydrate, calcium diphosphate, tricalcium phosphate, tetracalcium phosphate Phosphorus compounds such as octacalcium phosphate pentahydrate, calcium phosphite monohydrate, and calcium hypophosphite are preferably used.

These heat stabilizers can be used alone or in combination of two or more. The addition rate of the heat stabilizer is preferably 0.0005% by mass or more and 10% by mass or less, more preferably 0.005% by mass or more and 6% by mass or less with respect to the raw material monomer. Even if the addition rate of the heat stabilizer exceeds 10% by mass, the effect of preventing coloration does not increase, and if the addition rate is less than 0.0005% by mass, the effect of preventing coloration does not sufficiently appear. There is no limitation on the addition timing of these heat stabilizers, and they can be added directly to the raw material aqueous solution, added during the polycondensation reaction, or added after the completion of the polymerization reaction.
Further, as other additives, conventionally known heat stabilizers other than those mentioned above, antioxidants such as phenols and thioethers, etc., nucleating agents, fatty acid metal salts such as calcium stearate, etc. alone or 2 It is also possible to add or combine more than one species.

  On the other hand, the aliphatic polyhydroxycarboxylic acid prepolymer used in the present invention is an aliphatic polyester composed of an aliphatic polyhydroxycarboxylic acid and a polyol and an aliphatic polycarboxylic acid, or an aliphatic hydroxycarboxylic acid and a polyol and / or a fat. The reaction temperature for heating and melting an aliphatic polyester composed of an aliphatic polycarboxylic acid and producing it by transesterification is the aliphatic polyhydroxycarboxylic acid used, the aliphatic polyester composed of a polyol and an aliphatic polycarboxylic acid In addition, since it varies depending on the type and molecular weight of an aliphatic polyester composed of an aliphatic hydroxycarboxylic acid and a polyol and / or an aliphatic polycarboxylic acid, it is not limited, but is usually 100 ° C. or higher and 350 ° C. or lower, preferably 150 ° C. or higher. 280 ° C or lower, even better Details, can be exemplified in the range of 180 ° C. or higher 250 ° C. or less. When the aliphatic polyester used is not melted at a temperature lower than 100 ° C., the transesterification rate is remarkably reduced, and the reaction time is prolonged. On the other hand, when the temperature exceeds 350 ° C., coloring due to thermal decomposition of the aliphatic polyester used tends to increase.

  The aliphatic polyhydroxycarboxylic acid prepolymer used in the present invention is an aliphatic polyester comprising an aliphatic polyhydroxycarboxylic acid and a polyol and an aliphatic polycarboxylic acid, or an aliphatic hydroxycarboxylic acid and a polyol and / or an aliphatic poly Examples of the atmosphere when the aliphatic polyester composed of carboxylic acid is heated and melted and produced by transesterification include nitrogen, helium, neon, argon, krypton, xenon, carbon dioxide, carbon number of 1 to 4 Examples thereof include an atmosphere of inert gas such as lower saturated hydrocarbons, and one or more gases selected from gases such as air, under circulation, under reduced pressure or under pressure, or a combination thereof.

Among these, in order to suppress coloring of the aliphatic polyhydroxycarboxylic acid and the aliphatic polyhydroxycarboxylic acid prepolymer produced by transesterification, for example, nitrogen, helium, neon, argon, krypton, xenon, carbon dioxide or It is preferably carried out under an atmosphere of one or two or more inert gases selected from lower saturated hydrocarbons having 1 to 4 carbon atoms and the like, under pressure, under flow and / or under reduced pressure. When the reaction is carried out in a reduced pressure state, although it varies depending on the type of aliphatic polyhydroxycarboxylic acid and the operating temperature, a range of 1.333 Pa to 1.014 × 10 ⁵ Pa is usually exemplified.
The gas used at this time is preferably a dry gas having as low a water content as possible in order to suppress a decrease in molecular weight due to hydrolysis of the aliphatic polyester during the transesterification reaction. When the moisture content of the gas is indicated by a dew point, it is preferably −10 ° C. or lower, more preferably −40 ° C. or lower.
In addition, the water content of the aliphatic polyhydroxycarboxylic acid or the aliphatic polyester before being subjected to transesterification is such that the water content is low in order to suppress a decrease in molecular weight due to hydrolysis of the aliphatic polyester during the transesterification reaction. The lower the better. When the water content is represented by a numerical value, it is preferably 1,000 ppm or less, more preferably 500 ppm or less, and still more preferably 300 ppm or less.

  In the present invention, the aliphatic polyhydroxycarboxylic acid prepolymer is not particularly limited as long as it has a crystallizable weight average molecular weight, but is dried at the time of granulation or after granulation as necessary. Furthermore, in view of breakage during crystallization operation and generation of fine powder, the weight average molecular weight is preferably 3,000 or more. More preferably, it is 5,000 or more, more preferably 10,000 or more, and particularly preferably 25,000 or more. On the other hand, the upper limit of the weight average molecular weight of the aliphatic polyhydroxycarboxylic acid prepolymer is not particularly limited, but the polycondensation time in the molten state for producing the aliphatic polyhydroxycarboxylic acid prepolymer increases, and the prepolymer Is remarkably colored or the workability at the time of granulation may be lowered, and is preferably 150,000 or less, more preferably 100,000 or less, more preferably 90,000 or less, and still more preferably 80,000. Hereinafter, it is particularly preferably 70,000 or less.

  The method for granulating the aliphatic polyhydroxycarboxylic acid prepolymer is not limited. For example, the aliphatic polyhydroxycarboxylic acid prepolymer in a molten state is converted into nitrogen, helium, neon, argon, krypton, xenon, carbon dioxide or A solid or a strand-like material is solidified in an inert gas in one or two or more gases selected from an inert gas such as a lower saturated hydrocarbon having 1 to 4 carbon atoms and a gas such as air. A solid, and the solid is pulverized or cut into particles, pellets, or the like, or nitrogen, helium, neon, argon, krypton, xenon, carbon dioxide, or a lower saturated hydrocarbon having 1 to 4 carbon atoms In an inert gas or air atmosphere such as aliphatic polyhydroxycarboxylic acid prepolymer in a molten state, for example, Sandvik Using a strip former, funnel former, double roll feeder, Kaiser rotary drop former, piston type drop former, etc. to form droplets into solids such as pellets, etc. A method of bringing the aliphatic polyhydroxycarboxylic acid prepolymer into contact with a liquid such as water to form a solid such as particles or pellets, and bringing the aliphatic polyhydroxycarboxylic acid prepolymer in a molten state into contact with a liquid such as water After the extrusion of the molten aliphatic polyhydroxycarboxylic acid prepolymer through a gear pump as necessary, after extruding from a die, a solid such as a lump by pulverizing the lump etc. Alternatively, it is moved into an extruder and then brought into contact with a liquid such as water to form a strand or Obtained bets solid, pelleted solid, or a method in which chips and the like.

The method for bringing the molten aliphatic polyhydroxycarboxylic acid prepolymer into contact with a liquid such as water is not limited in any way. For example, the molten aliphatic polyhydroxycarboxylic acid prepolymer is dropped into water or hot water. Thus, a spherical pellet is obtained by solidifying.
In the present invention, the granulated aliphatic polyhydroxycarboxylic acid prepolymer is referred to as an aliphatic polyhydroxycarboxylic acid granule.
In the present invention, there is no limitation on the particle shape or pellet shape of the aliphatic polyhydroxycarboxylic acid granular material, but general shapes are powdery, pulverized, chip-like, spherical, cylindrical, tablet-like, marble-like Etc.

The particle diameter of the aliphatic polyhydroxycarboxylic acid granular material is not limited. In general, the smaller the particle size of a solid polymer, the larger the surface area. Therefore, it is advantageous in terms of the reaction surface during the subsequent solid-phase polymerization, but it is easy to handle and easy to crack during solid-phase polymerization. In consideration, the maximum diameter is usually preferably 0.05 mm or more and 20 mm or less, more preferably 0.1 mm or more and 10 mm or less, and further preferably 1 mm or more and 5 mm or less.
When granulation is carried out by contacting with a liquid such as water, an inert gas such as nitrogen, helium, neon, argon, krypton, xenon, carbon dioxide, or a lower saturated hydrocarbon having 1 to 4 carbon atoms, Surface adhering liquid can be removed by a method of removing the surface adhering liquid with air or the like or a gas comprising a mixture thereof, a method of dehydrating with a centrifugal dehydrator or the like, or a combination thereof. In addition, drying can be performed under a conventionally known method, for example, stirring, mixing, flowing, or mixing conditions under reduced pressure, gas flow, or mixing conditions thereof. Furthermore, it is also possible to carry out by combining these methods.

When the gas is circulated at the time of drying, for example, nitrogen, helium, neon, argon, krypton, xenon, carbon dioxide gas or an inert gas such as lower saturated hydrocarbon having 1 to 4 carbon atoms, air, etc. A gas composed of one or more selected from these gases can be used.
The temperature at the time of drying is not particularly limited as long as it is a temperature range below the melting point of the aliphatic polyhydroxycarboxylic acid granular material. When the aliphatic polyhydroxycarboxylic acid granular material is crystallized during drying to become a granular material having a melting point, and further when the melting point is increased by a drying operation, drying is performed within the range up to the melting point after the increase. Is possible. It is preferable to carry out at a temperature of 10 ° C. or higher and 150 ° C. or lower, in order to suppress a decrease in molecular weight due to hydrolysis of the aliphatic polyhydroxycarboxylic acid granular crystallized product and efficiently dry, It is more preferable to carry out at a temperature, and it is more preferable to carry out at a temperature of 50 ° C. or higher and 140 ° C. or lower. The temperature at the time of drying need not be constant as long as it is within the above range, and can be increased or decreased.

The time for drying is not particularly limited as long as the water content of the aliphatic polyhydroxycarboxylic acid particulates can be sufficiently reduced, and is usually in the range of 10 seconds to 100 hours.
In the present invention, the crystallization treatment is performed by measuring from −20 ° C. to 250 ° C. at a temperature rising rate of −20 ° C. using a differential scanning calorimeter (DSC), and the detected endothermic peak area and exothermic peak area are individually determined. The absolute value of the calorific value (hereinafter abbreviated as ΔHc) and the absolute value of the endothermic amount (hereinafter, abbreviated as “JC / g”) converted from the weight of the sample used for measurement to the unit weight. , Which is abbreviated as ΔHm), is a treatment for obtaining aliphatic polyhydroxycarboxylic acid granules having a value of [ΔHm−ΔHc] of 10 J / g or more. When the value of [ΔHm−ΔHc] is less than 10 J / g, subsequent solid phase polymerization becomes difficult due to fusion and aggregation of the aliphatic polyhydroxycarboxylic acid particulates. [ΔHm−ΔHc] of the aliphatic polyhydroxycarboxylic acid particulate is preferably 20 J / g or more, and more preferably 30 J / g or more.

In the present invention, an aliphatic polyhydroxycarboxylic acid granular material having a [ΔHm−ΔHc] value of 10 J / g or more is referred to as an aliphatic polyhydroxycarboxylic acid granular crystallized product.
Surface adhering liquid that is carried out when the value of [ΔHm−ΔHc] is already 10 J / g or more in the solid state that is passed through the granulation of the aliphatic polyhydroxycarboxylic acid prepolymer, or when necessary If the value of [ΔHm-ΔHc] is 10 J / g or more when removing the particulate matter or drying the granular material as necessary, the operation is included in the crystallization treatment. The

  When the aliphatic polyhydroxycarboxylic acid granular material is crystallized, there is no limitation on the method of the crystallizing treatment, and a known method can be used. For example, it is composed of one or more selected from inert gases such as nitrogen, helium, neon, argon, krypton, xenon, carbon dioxide, lower saturated hydrocarbons having 1 to 4 carbon atoms, and gases such as air. In a gas atmosphere, under circulation, under reduced pressure or under pressure, or a combination thereof, a method of crystallizing by heating, nitrogen, helium, neon, argon, krypton, xenon, carbon dioxide, carbon number 1 to 4 A method in which the solid aliphatic polyhydroxycarboxylic acid particulates are not dissolved at a temperature for crystallization at a temperature under the inert gas atmosphere, such as lower saturated hydrocarbons, etc., under circulation, under pressure or under reduced pressure, or a combination thereof. , For example, water, alcohols, aliphatic hydrocarbons, aromatic hydrocarbons, ketones, ethers, esters, etc. , And a method of contacting these mixtures are used.

Furthermore, as a mode, by rotating or vibrating a method of performing in a stationary state, a method of performing mechanical stirring (for example, a method of using a stirring blade), a vertical, horizontal, or slanted tank or tower itself A method of performing solid mixing, a method of performing phase shift from the upper part to the lower part of the tank or tower or tower, or a method of performing phase movement from the lower part to the upper part, a method of performing the flow by gas, or a combination thereof Methods and the like.
The temperature at the time of crystallization treatment varies depending on the composition ratio of the aliphatic polyhydroxycarboxylic acid prepolymer, the type of copolymer compound, etc., but is not less than the glass transition temperature of the aliphatic polyhydroxycarboxylic acid prepolymer and not more than 220 ° C. Range.

The time required for the crystallization treatment of the aliphatic polyhydroxycarboxylic acid particles is arbitrary. Generally, it is 0.5 minutes or more and 10 hours or less, preferably 1 minute or more and 8 hours or less, more preferably 5 minutes or more and 6 hours or less. The crystallization treatment can be carried out in a batch and / or continuous reaction mode. It can also be carried out in multiple stages.
Further, prior to the crystallization treatment of the aliphatic polyhydroxycarboxylic acid granular material by the above-mentioned known method, in order to prevent fusion of the granulated product during the crystallization, 25 ° C. or more and 200 ° C. or less in advance. Containing water vapor at a temperature of 0.001 mol to 0.135 mol per liter, such as nitrogen, helium, neon, argon, krypton, xenon, carbon dioxide or lower saturated hydrocarbons having 1 to 4 carbon atoms. Crystallize the surface of the aliphatic polyhydroxycarboxylic acid particulates by contact treatment with one or two or more gases selected from active gas or air, or depending on temperature and pressure conditions, steam or other gas such as steam. It is also possible to carry out a processing method.

  When the gas containing water vapor and the aliphatic polyhydroxycarboxylic acid particulates are brought into contact with each other, the gas containing water vapor is added to the fat to efficiently crystallize the surface of the aliphatic polyhydroxycarboxylic acid particulates. It is preferable to carry out by supplying or presenting 0.5 g or more per 1 kg of the group polyhydroxycarboxylic acid granular material. The contact between the aliphatic polyhydroxycarboxylic acid particulates and the gas containing water vapor can be performed under an atmospheric pressure atmosphere, under pressure, under flow and / or under reduced pressure. Among these, in order to continuously and industrially easily make contact between the aliphatic polyhydroxycarboxylic acid particulates and the gas containing water vapor in an industrially easy manner, or under the atmospheric pressure atmosphere of the gas containing water vapor, or It is preferred to operate under distribution.

The time when the aliphatic polyhydroxycarboxylic acid particulates are brought into contact with the gas containing water vapor varies depending on the type and molecular weight of the aliphatic polyhydroxycarboxylic acid prepolymer, the amount of water vapor in the gas, the temperature, and the like. Although there is no particular limitation, in order to suppress hydrolysis of the aliphatic polyhydroxycarboxylic acid prepolymer, it is preferably 1 second to 15 minutes, more preferably 10 seconds to 10 minutes, and more preferably 20 seconds to 5 minutes. preferable.
The method of bringing the aliphatic polyhydroxycarboxylic acid granules into contact with the gas containing water vapor is not particularly limited as long as the aliphatic polyhydroxycarboxylic acid granules can come into contact with the gas containing water vapor. Or it can carry out combining 1 type, or 2 or more types of apparatus of a continuous type.

In the present invention, the weight average molecular weight of the aliphatic polyhydroxycarboxylic acid granular crystallized product is preferably 3,000 or more in consideration of damage during solid phase polymerization and generation of fine powder. More preferably, it is 5,000 or more, and particularly preferably 10,000 or more. Furthermore, it is most preferably 25,000 or more in that the reaction rate of the solid phase polymerization reaction is increased.
In the present invention, the conditions for solid-phase polymerization of the aliphatic polyhydroxycarboxylic acid granular crystallized product are as follows: the temperature at which the granular crystallized product maintains a solid state is an air pressure of 90 m / hr or higher in a pressure range of 1 kPa or lower. It is necessary to circulate the gas at the tower speed.
The value of the superficial velocity in the present invention refers to the value under the reaction temperature and reaction pressure conditions.

When the pressure during the solid-phase polymerization reaction exceeds 1 kPa, or when the superficial velocity of the flow gas during the solid-phase polymerization reaction is less than 90 m / hr, the reaction rate is significantly reduced, This is not preferable because the phase polymerization time becomes long.
In consideration of the solid-phase polymerization reaction rate, the pressure during the solid-phase polymerization is preferably as low as possible, preferably 0.8 kPa or less, more preferably 0.6 kPa or less, still more preferably 0.4 kPa or less, particularly preferably. The range is 0.2 kPa or less. Although there is no limitation in particular about the minimum of a pressure, when considering that a vacuum installation enlarges, it is 0.0001 kPa or more normally. If the pressure at the time of performing solid phase polymerization is in the above-mentioned range, it is not necessary to be constant, and it can be increased or decreased, or can be changed in combination.

The superficial velocity of the flow gas is preferably as large as possible considering the solid phase polymerization reaction rate, preferably 110 m / hr or more, more preferably 150 m / hr or more, still more preferably 180 m / hr, particularly preferably 200 m / hr or more. It is. The upper limit of the superficial velocity of the flow gas is not particularly limited, but is preferably 250,000 m / hr or less in order to suppress the fluidization phenomenon of the aliphatic polyhydroxycarboxylic acid granular crystallized product during the solid phase polymerization reaction, 150,000 m / hr or less is more preferable. As long as the superficial velocity is within the above range, it can be increased, decreased, or further combined. The superficial velocity can be changed as appropriate by appropriately selecting the pressure during the reaction, the amount of flow gas described below, and the internal diameter of the reaction apparatus.
The flow rate when the gas is circulated takes into account the shape, particle size, crystallinity, etc. of the aliphatic polyhydroxycarboxylic acid granular crystallization product, the temperature and pressure at which the solid-phase polymerization reaction is carried out, or the superficial velocity of the circulation gas. It is only necessary to distill off the water produced to such an extent that a granular crystallized product of aliphatic polyhydroxycarboxylic acid having a sufficiently high weight average molecular weight can be obtained.

  In general, the greater the flow rate of the gas that flows, the higher the efficiency of removing the generated water, but usually within the range of 0.01 liter / hr or more per kg of crystallization prepolymer in terms of normal pressure and 20 ° C. is there. From the viewpoint of improving the polycondensation reaction rate, the flow rate of the flow gas is preferably 0.1 liter / hr or more, more preferably 0.5 liter / hr or more. The upper limit of the flow rate of the circulating gas is not particularly limited as long as it satisfies the solid-state polymerization conditions of the present invention. However, even if it exceeds 100 liters / hr in terms of normal pressure per kg of the crystallization prepolymer, the flow rate can be increased. Since the contribution to the improvement of the condensation reaction rate is small, it is not necessary to increase the amount exceeding 100 liters / hr. From the viewpoint of improving the polycondensation reaction rate, the flow rate of the flow gas is preferably 80 liter / hr or less, more preferably 60 liter / hr or less, further preferably 50 liter / hr or less, particularly preferably 40 liter / hr or less. It is. If the flow rate of the circulating gas is within the above range, it can be increased or decreased, or can be changed in combination.

The circulating gas is composed of one or more selected from inert gases such as nitrogen, helium, neon, argon, krypton, xenon, carbon dioxide, lower saturated hydrocarbons having 1 to 4 carbon atoms, air, and the like. Gas. Among these gases, nitrogen, helium, neon, argon, krypton, xenon, carbon dioxide, lower saturation with 1 to 4 carbon atoms is used to suppress coloring of aliphatic polyhydroxycarboxylic acid during solid-phase polymerization. A gas composed of one or more selected from inert gases such as hydrocarbons is preferably used.
The inert gas to be circulated is preferably a dry gas that has a water content as low as possible and is substantially anhydrous. When the water content is high, the water produced by the solid-phase polymerization reaction cannot be removed efficiently, and the polymerization rate becomes slow. When the water content of the circulating gas is indicated by a dew point, it is preferably −10 ° C. or lower, more preferably −40 ° C. or lower, still more preferably −50 ° C. or lower, and particularly preferably −60 ° C. or lower. The gas to be circulated can be used after passing through a layer filled with molecular sieves, ion exchange resins or the like, or dehydrated by cooling.

  The reaction temperature at the time of performing solid-phase polymerization is not limited as long as the aliphatic polyhydroxycarboxylic acid particulate crystallized product existing in the reaction system is maintained in a substantially solid state. It is in the range from the glass transition temperature of the crystallized product to less than the melting point. Considering the polymerization rate of solid phase polymerization, it is preferably 100 ° C. or higher and lower than the melting point of the aliphatic polyhydroxycarboxylic acid granular crystallized product, more preferably 120 ° C. or higher and the aliphatic polyhydroxycarboxylic acid granular crystallized product ( The melting point is −5 ° C.) or less, more preferably 130 ° C. or more and the temperature range of (melting point−10) ° C. or less of the aliphatic polyhydroxycarboxylic acid granular crystallized product. At this time, the reaction temperature during solid-phase polymerization need not be constant during the reaction as long as it is within the above-mentioned temperature range.

During the solid-state polymerization reaction, if the melting point of the aliphatic polyhydroxycarboxylic acid granular crystallized product increases due to an increase in molecular weight or annealing effect, the reaction temperature is raised to the melting point range of the aliphatic polyhydroxycarboxylic acid granular crystallized product at that time. It is also possible to carry out a solid phase polymerization reaction.
The time required for the solid phase polymerization reaction depends on the type of the aliphatic polyhydroxycarboxylic acid, the molecular weight of the granular crystallized product, the molecular weight of the target aliphatic polyhydroxycarboxylic acid, the type of polycondensator used, and the reaction conditions. Although not limited, it is preferably 0.5 hours or more and 100 hours or less, more preferably 2 hours or more and 50 hours or less.

There are no particular limitations on the apparatus for performing solid phase polymerization, and the method for contacting the flow gas with the aliphatic polyhydroxycarboxylic acid granular crystallized product as long as the requirements of the present invention can be satisfied. It can be carried out by combining a continuous type of reaction device of one type or two or more types and a contact method with a circulating gas. For example, as an apparatus for performing solid phase polymerization, a vertical or horizontal fixed bed reactor, a moving bed reactor, or the like can be exemplified. Of these, vertical fixed bed reactors and moving bed reactors are preferably used.
The inside of the apparatus is not particularly limited as long as solid phase polymerization can be performed within a range that can satisfy the requirements of the present invention, and may be tapered or uneven.

  Furthermore, there may be a support inside the device. The support may be directly connected to the upper part of the solid phase polymerization reactor, or may be directly connected to the lower part of the polymerization machine. Moreover, you may connect to both upper part and the lower part. There is no restriction | limiting in the shape of the cross section of a support body, Usually, it selects from shapes, such as circular shape, ellipse shape, triangular shape, square shape, polygonal shape, star shape. The shape of the cross section may be constant in the length direction or may be different. Further, the support may be hollow. When the support is hollow, a method of putting a heating medium in the hollow part is also possible. The support may be a single support or a combination of multiple supports. Further, the surface of the support may be smooth or uneven. Moreover, you may have a protrusion partially.

Further, for example, as a method of contacting the flow gas with the aliphatic polyhydroxycarboxylic acid, when the solid phase polymerization is performed using a fixed bed reactor, the flow gas is, for example, above or below the reactor, Alternatively, it can be distributed from the side or the like.
In addition, when solid-phase polymerization is carried out using a moving bed reactor, a method of bringing an aliphatic polyhydroxycarboxylic acid granular crystallized product and a circulating gas into AC contact, or a method of bringing a circulating gas into parallel flow contact, etc. Can be illustrated. Further, when using a moving bed reactor, it is possible to carry out the reaction while sequentially or continuously extracting a part of the aliphatic polyhydroxycarboxylic acid at or near the tip in the moving direction. Moreover, it is also possible to supply the aliphatic hydroxycarboxylic acid granular crystallized product to be subjected to solid phase polymerization sequentially or continuously from the end in the direction opposite to the moving direction as required. Among the above methods, the method of alternating contact between the aliphatic polyhydroxycarboxylic acid granular crystallized product and the flow gas is a preferable method because an aliphatic polyhydroxycarboxylic acid having a high molecular weight can be obtained.

In the present invention, the equipment for reducing the pressure includes conventionally known vacuum pumps, for example, reciprocating pumps such as piston vacuum pumps, rotary pumps such as liquid ring vacuum pumps, oil rotary pumps, roots vacuum pumps, etc., turbine vacuum Gases such as mechanical pumps such as pumps, molecular pumps, turbo molecular pumps, fluid-operated pumps such as ejector pumps, diffusion pumps, and vapor injection pumps, adsorption pumps, getter pumps, getter ion pumps, sputter ion pumps, cryopumps, etc. Therefore, it is possible to use one type or a combination of two or more types of built-in vacuum pumps.
The material of the polycondenser used in the present invention is not limited, and usually has corrosion resistance etc. from glass, stainless steel, carbon steel, nickel, hastelloy, titanium, chromium, zirconium, other alloys and polymer materials with high heat resistance. Selected in consideration. The surface of the polycondensator may be subjected to various treatments as necessary, such as plating, lining, passivation treatment, acid washing, and alkali washing.

The weight average molecular weight of the aliphatic polyhydroxycarboxylic acid after solid phase polymerization obtained by the present invention is usually 1,000,000 or less.
The aliphatic polyhydroxycarboxylic acid obtained in the present invention can be subjected to terminal modification by reacting with an acid anhydride such as acetic anhydride, an epoxy compound or the like after the polycondensation reaction, if necessary.
The aliphatic polyhydroxycarboxylic acid of the present invention includes, as necessary, known heat stabilizers, phenol-based, thioether-based antioxidants, ultraviolet inhibitors, hindered amine-based light stabilizers, moisture-proofing agents, waterproofing. Agent, water repellent, lubricant, release agent, pigment, dye, nucleating agent, plasticizer, inorganic filler, fatty acid metal salt such as calcium stearate, other thermoplastic resins, etc. It can be added or blended. The amount of these additives is usually in the range of 0.0005% by mass to 40% by mass, and preferably in the range of 0.001% by mass to 30% by mass.

EXAMPLES The present invention will be specifically described below with reference to examples, but these examples do not limit the scope of the present invention.
The characteristics of the polymer used in the present invention are measured by the following method.
(1) Content ratio of monomer units constituting aliphatic polyhydroxycarboxylic acid Obtained by freeze-pulverizing aliphatic polyhydroxycarboxylic acid and drying it under vacuum at room temperature (25 ° C) to a water content of 1000 ppm or less A very small amount of tetramethylsilane was added as a reference substance to a deuterated hexafluoroisopropanol solution of an aliphatic polyhydroxycarboxylic acid dissolved in a deuterated hexafluoroisopropanol solvent at a rate of 1 ml per 30 mg of the ground product. A sample is used as a measurement sample. Using this measurement sample, 1H-NMR measurement of 400 MHz (manufactured by JASCO Corporation α-400) was performed at a total number of 500 times, and the obtained results were analyzed to construct monomer units other than diglycolic acid units. The amount is calculated as a molar ratio.

(2) Weight average molecular weight of aliphatic polyhydroxycarboxylic acid Using a gel permeation chromatography (GPC) analyzer 8020GPC system manufactured by Tosoh Corporation, the weight average molecular weight is obtained under the following conditions.
As a solvent to be used, hexafluoroisopropanol in which 80 mM sodium trifluoroacetate (a reagent manufactured by Wako Pure Chemical Industries, Ltd.) is dissolved is prepared in advance. That is, a solution in which 6.48 g of sodium trifluoroacetate is dissolved in 1000 g of hexafluoroisopropanol (hereinafter abbreviated as an eluent) is prepared.
After precisely weighing 1 g of a granular crystallized product of aliphatic polyhydroxycarboxylic acid obtained by drying to a water content of 1000 ppm or less at room temperature (25 ° C.) under vacuum, it was dissolved in 150 g of the eluent, and then 0. What was filtered with a 2 μm filter is used as a measurement sample solution.
At a column temperature of 40 ° C., the eluent was supplied under the condition of a flow rate of 1 ml / min. [Column configuration is Tsquardcolumn HHR-H (registered trademark) manufactured by Tosoh Corp. (Registered trademark) G5000HHR and Tosoh Co., Ltd. Tskel (registered trademark) G3000HHR one by one in series], molecular weight 1,577,000, 685,000, 333,000, 100,250, 62 , 600, 24, 300, 12,700, 4,700, 1,680, 1140, RI dispersion of monodisperse polymethyl methacrylate standard material and molecular weight monomer (molecular weight 100) manufactured by Polymer Laboratories with known molecular weight Prepare a calibration curve obtained from the elution time by The weight average molecular weight is calculated from the delivery time.

(3) Measurement method of crystallization calorie, heat of fusion, glass transition temperature and melting point of aliphatic polyhydroxycarboxylic acid Molybdenum of 1000 ppm at room temperature (25 ° C.) under vacuum from aliphatic polyhydroxycarboxylic acid granular crystallized product The granular crystallized product itself obtained by drying is used as a sample and measured by a differential scanning calorimeter (DSC) under the following measurement conditions based on JIS K7121.
Sample weight: about 25mg
Temperature condition: -20 ° C to 250 ° C
Temperature increase rate: 10 ° C / min

(4) Amount of fine powder 100 g or more of an aliphatic polyhydroxycarboxylic acid granular material was washed on a 50 mesh sieve to remove fine powder having a size of less than 50 mesh adhering to the surface of the granular material. Separate particulates. The fine powder and the granular material are dried at room temperature (25 ° C.) under vacuum for 24 hours or more, and each weight is measured. The amount of fine powder generated is expressed as a mass fraction (% by mass) of the mass of the fine powder after drying to the sum of the mass of the fine powder after drying and the granular material.

[Resin production example 1]
To a 20-liter glass-lined autoclave with a baffle plate equipped with a glass distilling tube and a glass-lined flat blade-type stirring blade, 10 kg, 90% by mass of a 70 mass% glycolic acid aqueous solution (Glypure 70 manufactured by DuPont). 1.26 kg of L-lactic acid aqueous solution (Pureac HiPure 90), 2.7 g of neopentyl glycol (special grade of Wako Pure Chemicals) and 0.05% by mass of tetraisopropoxygermanium (monomer) After charging 2 × 10 ⁻⁶ mol) as germanium metal atoms per gram, nitrogen substitution was performed.
Subsequently, the autoclave was heated to 150 ° C. under a nitrogen stream and kept for 1.5 hours for dehydration. Next, the pressure was gradually lowered and reacted at 5.0 × 10 ⁴ Pa for 1 hour and 2.0 × 10 ³ Pa for 50 minutes, then the temperature was raised to 200 ° C. and the pressure was 6.0 × 10 ^2. The pressure was reduced to Pa, and the polycondensation reaction was performed for 120 minutes.
Next, the obtained polycondensate was transferred to a 20-liter stainless steel VCR polymerization machine (registered trademark; manufactured by Mitsubishi Heavy Industries, Ltd.), which was replaced with nitrogen, while maintaining the molten state. The reaction was continued at × 10 ² Pa for 6 hours.
After completion of the reaction, the pressure was increased with nitrogen, and the resin was discharged as a strand from the bottom of the polymerization machine into running water at about 10 ° C., and after cutting in running water, centrifugal dehydration was performed to obtain a diameter of 2 mm. A cylindrical amorphous polyhydroxycarboxylic acid granular material A having a length of 3 mm was prepared.
The granule A was dried at room temperature (25 ° C.) under vacuum for 24 hours, and the pellets having a water content of 1000 ppm or less had a weight average molecular weight of 55,000, the resin composition had a glycolic acid unit content of 88 mol%, and neopentyl glycol units. It was 0.03 mol%. The glass transition temperature was 37 ° C. This method was repeated to produce the required resin amount.

[Resin production example 2]
To a 20-liter glass-lined autoclave with a baffle plate equipped with a glass distilling tube and a glass-lined flat blade-type stirring blade, 10 kg, 90% by mass of a 70 mass% glycolic acid aqueous solution (Glypure 70 manufactured by DuPont). 1.26 kg of L-lactic acid aqueous solution (Pureac HiPure 90), 2.7 g of neopentyl glycol (special grade of Wako Pure Chemicals) and 0.05% by mass of tetraisopropoxygermanium (monomer) After charging 2 × 10 ⁻⁶ mol) as germanium metal atoms per gram, nitrogen substitution was performed. Subsequently, the autoclave was heated to 150 ° C. under a nitrogen stream and kept for 1.5 hours for dehydration. Then, the pressure is gradually lowered at 5.0 × 10 ⁴ Pa for 1 hour, 2.5 × 10 ⁴ Pa for 0.5 hour, 1.0 × 10 ⁴ Pa for 50 minutes, and 5.0 × 10 ³ Pa. After 50 minutes of reaction at 2.0 × 10 ³ Pa for 50 minutes, the temperature was raised to 200 ° C., the pressure was lowered to 6.0 × 10 ² Pa, and a polycondensation reaction was performed for 70 minutes. After completion of the reaction, pressurize with nitrogen, discharge the resin as a strand from the bottom of the polymerization machine into running water at about 10 ° C., perform cutting in running water, perform centrifugal dehydration, and circle with a diameter of 2 mm and a length of 3 mm. Columnar amorphous aliphatic polyhydroxycarboxylic acid granules B were prepared.
The granular material B was dried under vacuum at room temperature (25 ° C.) for 24 hours, and the pellets having a water content of 1000 ppm or less had a weight average molecular weight of 7,000, the resin composition had a glycolic acid unit content of 88 mol%, and neopentyl glycol units. It was 0.03 mol%. The glass transition temperature was 37 ° C. This method was repeated to produce the required resin amount.

[Resin Production Example 3]
The feed amount of 90 mass% L-lactic acid aqueous solution (HiPure 90 manufactured by Pulac Co., Ltd.) was 0.59 kg and the feed amount of neopentyl glycol (special grade product of Wako Pure Chemical Industries, Ltd.) was 2.6 g. A cylindrical amorphous aliphatic polyhydroxycarboxylic acid granular material C having a diameter of 2 mm and a length of 3 mm was prepared in the same manner as in Resin Production Example 1 except that the reaction conditions were 210 ° C. and 5 hours. .
The granular material C was dried under vacuum at room temperature (25 ° C.) for 24 hours, and the pellets having a water content of 1000 ppm or less had a weight average molecular weight of 56,000, the resin composition had a glycolic acid unit content of 94 mol%, and neopentyl glycol units. It was 0.03 mol%. The glass transition temperature was 37 ° C. This method was repeated to produce the required resin amount.

[Resin Production Example 4]
To a 20-liter glass-lined autoclave with a baffle plate equipped with a glass distilling tube and a glass-lined flat blade-type stirring blade, 9.2 kg of 90 mass% glycolic acid aqueous solution (Glypure 70 manufactured by DuPont) was added. 376 g of mass% L-lactic acid aqueous solution (Pureac HiPure 90), 335 g of 1,6-hexanediol (Wako Pure Chemical Industries reagent special grade), 400 g of adipic acid (Wako Pure Chemical Industries reagent special grade) Except for charging, a cylindrical amorphous aliphatic polyhydroxycarboxylic acid granular material D having a diameter of 2 mm and a length of 3 mm was prepared in the same manner as in Resin Production Example 1.
The granular material D was dried at room temperature (25 ° C.) under vacuum for 24 hours, and the pellets having a water content of 1000 ppm or less had a weight average molecular weight of 48,000, the resin composition had a glycolic acid unit content of 90 mol%, 1,6- The hexanediol unit was 3 mol% and the adipic acid unit was 3 mol%. The glass transition temperature was 37 ° C. This method was repeated to produce the required resin amount.

[Resin Production Example 5]
As a raw material, 10 kg of 90 mass% L-lactic acid aqueous solution (Pureac HiPure 90) and 0.05 mass% tetraisopropoxygermanium (2 × 10 ⁻⁶ mol as germanium metal atoms per 1 g of monomer) with respect to the aqueous raw material solution The polycondensation conditions in a glass-lined 20 liter autoclave at 150 ° C. for 1.5 hours, and then the pressure was gradually reduced at 5.0 × 10 ⁴ Pa for 1 hour, 2.5 × 10 After reacting at ⁴ Pa for 0.5 hour, 1.0 × 10 ⁴ Pa for 50 minutes, 5.0 × 10 ³ Pa for 50 minutes, and 2.0 × 10 ³ Pa for 50 minutes, the temperature was raised to 185 ° C. the temperature was raised, it was performed 120 minutes polycondensation reaction by lowering the pressure to 6.0 × 10 2 ^Pa, while the polycondensate obtained was kept molten, nitrogen-purged stainless steel 20 liters of VCR polymerizer; transferred to (R manufactured by Mitsubishi Heavy Industries Co.), subsequently 185 ° C., except for continuing the reaction for 8 hours at 4 × 10 2 ^Pa in the same manner as in Resin Production Example 1 Thus, a cylindrical amorphous aliphatic polyhydroxycarboxylic acid granular material E having a diameter of 2 mm and a length of 3 mm was prepared.
The granular material E was dried at room temperature (25 ° C.) under vacuum for 24 hours, and the weight average molecular weight of pellets having a water content of 1000 ppm or less was 45,000. The glass transition temperature was 55 ° C. This method was repeated to produce the required resin amount.

[Resin Production Example 6]
As a raw material, 10 kg of 90% by mass L-lactic acid aqueous solution (Pureac HiPure 90) and 0.04% by mass of stannic chloride with respect to the raw material aqueous solution (2 × 10 ⁻⁶ mol as a tin metal atom per 1 g of monomer) A cylindrical amorphous aliphatic polyhydroxycarboxylic acid particle F having a diameter of 2 mm and a length of 3 mm was prepared in the same manner as in Resin Production Example 1 except that was used.
The granule F was dried at room temperature (25 ° C.) under vacuum for 24 hours, and the weight average molecular weight of pellets having a water content of 1000 ppm or less was 43,000. The glass transition temperature was 55 ° C. This method was repeated to produce the required resin amount.

[Reference Example 1]
(A) Crystallization treatment A Teflon (registered trademark) sheet was laid on the bat, and the aliphatic polyhydroxycarboxylic acid granular material A was sparsely spread, and 2 kPa while flowing nitrogen at 1 liter / min in a vacuum dryer. Under a reduced pressure of 80 ° C. for 5 hours, followed by heating to 100 ° C. for 3 hours, then heating to 120 ° C. for 3 hours, then heating to 150 ° C. for 3 hours, then heating to 170 ° C. Was crystallized for 2 hours and then allowed to cool to room temperature under reduced pressure. The obtained granular crystallized product has a cylindrical shape with a diameter of about 2 mm and a length of about 3 mm, a weight average molecular weight of 55,000, a melting point of 187 ° C., and a heat of fusion (ΔHm) of 45 J / g. The amount of heat of formation (ΔHc) was not observed. The obtained aliphatic polyhydroxycarboxylic acid granular crystallized product is referred to as granular crystallized product A2.

(B) Solid phase polymerization A solid phase polymerization reaction was carried out using a fixed bed reactor.
0.31 kg of the granular crystallized product A2 was filled into a cylindrical SUS316 cylindrical vertical reaction tube having an inner diameter of 21.2 mm and a length of 150 mm in which a filter having a mesh diameter of 15 μm was connected to the upper end and the lower end. A nitrogen gas having a dew point of −90 ° C. as a circulating gas was heated to 170 ° C. at a flow rate of 1.797 liters / hr (20 ° C., a value at normal pressure) as a circulating gas, and a temperature of 170 ° C. was maintained at 30 ° C. The solid phase polymerization reaction was carried out for a time. The flow rate of nitrogen gas is 57.756 liters / hr per kg of granular crystallized product in terms of normal pressure and 20 ° C., and the superficial velocity of the flow of nitrogen gas is 7.7 m / hr.
The weight average molecular weight of the aliphatic polyhydroxycarboxylic acid obtained after the solid phase polymerization reaction was 91,000. The increase in the weight average molecular weight per hour obtained by dividing the difference in weight average molecular weight before and after the reaction by the reaction time was 1,200. Thereafter, the increase in the weight average molecular weight per hour is used as an index of the polymerization rate.

[Reference Example 2]
The same conditions as in Reference Example 1 except that the granular crystallization product A2 was used and the flow rate of flowing nitrogen gas was 71.417 liters / hr (value at 20 ° C., normal pressure) corresponding to about 40 times that of Reference Example 1. A solid state polymerization reaction was carried out.
The superficial velocity of nitrogen gas is 306 m / hr.
The weight average molecular weight of the aliphatic polyhydroxycarboxylic acid obtained after the solid phase polymerization reaction was 98,000. The amount of increase in the weight average molecular weight per hour obtained by dividing the difference in weight average molecular weight before and after the reaction by the reaction time was 1,440, and the polymerization rate was slightly increased with respect to Reference Example 1.

[Example 1]
(A) Crystallization treatment A granular crystallized product A2 was produced in the same manner as in Reference Example 1 (A).
(B) Solid phase polymerization The solid phase polymerization reaction was carried out by the following method using a fixed bed reactor.
0.31 kg of the granular crystallized product A2 was filled into a cylindrical SUS316 cylindrical vertical reaction tube having an inner diameter of 21.2 mm and a length of 150 mm connected to a filter having a mesh diameter of 15 μm at the upper and lower ends. Using a rotary vacuum pump, a nitrogen gas with a reaction pressure of 1 kPa and a dew point of −90 ° C. was circulated at a flow rate of 0.705 liter / hr (20 ° C., value at normal pressure), and a temperature of 170 ° C. The solid phase polymerization reaction was carried out for a time. The superficial velocity of nitrogen gas is 306 m / hr.
The weight average molecular weight of the aliphatic polyhydroxycarboxylic acid obtained after the solid phase polymerization reaction was 103,000. The difference in weight average molecular weight before and after the reaction is divided by the reaction time, and the increase in the weight average molecular weight per hour is 1,600, which is 0.5 times the amount of nitrogen relative to Reference Example 1 or Reference Example 2. Even at a high flow rate, it was possible to produce a high molecular weight aliphatic polyhydroxycarboxylic acid at a high polymerization rate.

[Example 2]
Example 1 (B) except that the granular crystallization product A2 was used, the reaction pressure was 0.5 kPa, and the flow rate of the flowing nitrogen gas was 0.353 liter / hr (value at 20 ° C., normal pressure). A solid state polymerization reaction was carried out under the same conditions. The superficial velocity of nitrogen gas is 306 m / hr.
The weight average molecular weight of the aliphatic polyhydroxycarboxylic acid obtained after the solid phase polymerization reaction was 120,000. The increase in the weight average molecular weight per hour obtained by dividing the difference between the weight average molecular weight before and after the reaction by the reaction time is 2,167, which is 0.2 times the amount of nitrogen relative to Reference Example 1 or Reference Example 2. Even at a high flow rate, it was possible to produce a high molecular weight aliphatic polyhydroxycarboxylic acid at a high polymerization rate.

[Example 3]
Example 1 (B) except that the granular crystallization product A2 was used, the reaction pressure was 0.15 kPa, and the flow rate of the flowing nitrogen gas was 0.106 liter / hr (value at 20 ° C., normal pressure). A solid state polymerization reaction was carried out under the same conditions. The superficial velocity of nitrogen gas is 306 m / hr.
The weight average molecular weight of the aliphatic polyhydroxycarboxylic acid obtained after the solid phase polymerization reaction was 163,000. The difference in weight average molecular weight before and after the reaction is divided by the reaction time, and the amount of increase in the weight average molecular weight per hour is 3,600. At high speeds, it was possible to produce high molecular weight aliphatic polyhydroxycarboxylic acids.

[Example 4]
Example 1 (B) except that granular crystallization product A2 was used, the reaction pressure was 0.5 kPa, and the flow rate of flowing nitrogen gas was 0.115 liter / hr (value at 20 ° C., normal pressure). A solid state polymerization reaction was carried out under the same conditions. The superficial speed of nitrogen gas is 100 m / hr.
The weight average molecular weight of the aliphatic polyhydroxycarboxylic acid obtained after the solid phase polymerization reaction was 105,000. The increase in the weight average molecular weight per hour obtained by dividing the difference between the weight average molecular weights before and after the reaction by the reaction time is 1,667, which is 0.07 times the amount of nitrogen relative to Reference Example 1 or Reference Example 2. Even at a high flow rate, it was possible to produce a high molecular weight aliphatic polyhydroxycarboxylic acid at a high polymerization rate.

[Example 5]
(A) Crystallization treatment An upper layer portion having a steam supply port and a gas supply port, a central portion in which a 30-mesh wire mesh is held in a horizontal direction, and a gas containing water vapor are retained as necessary. On the other hand, 1 kg of the aliphatic polyhydroxycarboxylic acid granular material A was sparsely charged on the wire net of the apparatus, which comprises a lower layer having a discharge port capable of discharging. Subsequently, saturated steam at 100 ° C. was circulated at a flow rate of 100 g / min for 90 seconds in an air atmosphere at atmospheric pressure. After the flow of water vapor was stopped, the granular crystallized product was taken out and dehydrated with a centrifugal dehydrator. As a result of analyzing the obtained granular crystallized product, the heat of crystallization (ΔHc) was 10 J / g, the heat of fusion (ΔHm) was 15 J / g, and the weight average molecular weight was 55,000. This operation was repeated to prepare a necessary amount of granular materials.
The obtained granular material is charged into a 100 liter double cone dryer equipped with an introduction pipe capable of controlling the temperature of the circulating gas, a circulating gas distillation pipe capable of external cooling, and a trap having a sufficient heat transfer area. While distilling the water from the outside to 5 ° C. and cooling the trap to −40 ° C., nitrogen at a dew point temperature of −80 ° C. was passed through 10 liters (25 ° C., value at atmospheric pressure) / hr, and 80 ° C. For 2 hours, at 100 ° C. for 6 hours, at 130 ° C. for 2 hours, at 150 ° C. for 2 hours and at 170 ° C. for 2 hours, and then cooled to room temperature and the contents were taken out.
The obtained granular crystallized product was not fused, and its shape was a cylindrical shape having a diameter of about 2 mm and a length of about 3 mm. The weight average molecular weight was 55,000, the melting point was 186 ° C., the heat of fusion (ΔHm) was 44 J / g, and the heat of crystallization (ΔHc) was not observed. Furthermore, the generation amount of fine powder was 200 ppm. The obtained aliphatic polyhydroxycarboxylic acid granular crystallized product is referred to as granular crystallized product A3.

(B) Solid-phase polymerization Implemented except that the granular crystallized product A3 was used, the reaction pressure was 0.5 kPa, and the flow rate of flowing nitrogen gas was 0.196 liter / hr (20 ° C., value at normal pressure). A solid phase polymerization reaction was carried out under the same conditions as in Example 1 (B). The superficial speed of nitrogen gas is 170 m / hr.
The weight average molecular weight of the aliphatic polyhydroxycarboxylic acid obtained after the solid phase polymerization reaction was 110,000. The amount of increase in the weight average molecular weight per hour obtained by dividing the difference in weight average molecular weight before and after the reaction by the reaction time is 1,833, which is less than 0.11 times the amount of nitrogen relative to Reference Example 1 or Reference Example 2. Even at a high flow rate, it was possible to produce a high molecular weight aliphatic polyhydroxycarboxylic acid at a high polymerization rate.

[Example 6]
Example 1 (B) except that the granular crystallization product A2 was used, the reaction pressure was 0.5 kPa, and the flow rate of the flowing nitrogen gas was 1.078 liter / hr (value at 20 ° C., normal pressure). A solid state polymerization reaction was carried out under the same conditions. The superficial velocity of nitrogen gas is 936 m / hr.
The weight average molecular weight of the aliphatic polyhydroxycarboxylic acid obtained after the solid phase polymerization reaction was 129,000. The difference in weight average molecular weight before and after the reaction is divided by the reaction time, and the increase in the weight average molecular weight per hour is 2,467, which is 0.6 times the nitrogen flow rate of Reference Example 1 or Reference Example 2. However, it was possible to produce a high molecular weight aliphatic polyhydroxycarboxylic acid at a high polymerization rate.

[Comparative Example 1]
Example 1 (B) except that the granular crystallization product A2 was used, the reaction pressure was set to 3.0 kPa, and the flow rate of flowing nitrogen gas was set to 2.115 liter / hr (value at 20 ° C., normal pressure). A solid state polymerization reaction was carried out under the same conditions. The superficial velocity of nitrogen gas is 306 m / hr.
The weight average molecular weight of the aliphatic polyhydroxycarboxylic acid obtained after the solid phase polymerization reaction was 93,000. The increase in the weight average molecular weight per hour obtained by dividing the difference in weight average molecular weight before and after the reaction by the reaction time was as low as 1,267.

[Comparative Example 2]
Example 1 (B) except that the granular crystallization product A2 was used, the reaction pressure was 10.0 kPa, and the flow rate of the flowing nitrogen gas was 7.05 liter / hr (value at 20 ° C., normal pressure). A solid state polymerization reaction was carried out under the same conditions. The superficial velocity of nitrogen gas is 306 m / hr.
The weight average molecular weight of the aliphatic polyhydroxycarboxylic acid obtained after the solid phase polymerization reaction was 91,000. The increase in the weight average molecular weight per hour obtained by dividing the difference in weight average molecular weight before and after the reaction by the reaction time was as low as 1,200.

[Comparative Example 3]
Example 1 (B) except that the granular crystallization product A2 was used, the reaction pressure was 0.5 kPa, and the flow rate of the flowing nitrogen gas was 0.086 liters / hr (value at 20 ° C., normal pressure). A solid state polymerization reaction was carried out under the same conditions. The superficial velocity of nitrogen gas is 75 m / hr.
The weight average molecular weight of the aliphatic polyhydroxycarboxylic acid obtained after the solid phase polymerization reaction was 101,000. The increase in the weight average molecular weight per hour obtained by dividing the difference in weight average molecular weight before and after the reaction by the reaction time was as low as 1,533.

[Comparative Example 4]
Example 1 (B) except that the granular crystallization product A2 was used, the reaction pressure was 0.5 kPa, and the flow rate of the flowing nitrogen gas was 0.058 liter / hr (value at 20 ° C., normal pressure). A solid state polymerization reaction was carried out under the same conditions. The superficial velocity of nitrogen gas is 50 m / hr.
The weight average molecular weight of the aliphatic polyhydroxycarboxylic acid obtained after the solid phase polymerization reaction was 101,000. The increase in the weight average molecular weight per hour obtained by dividing the difference in weight average molecular weight before and after the reaction by the reaction time was as low as 1,533.

[Example 7]
(A) Crystallization treatment An upper layer portion having a steam supply port and a gas supply port, a central portion in which a 30-mesh wire mesh is held in a horizontal direction, and a gas containing water vapor are retained as necessary. On the other hand, 1 kg of the aliphatic polyhydroxycarboxylic acid granular material B was sparsely charged on the wire mesh of the apparatus comprising the lower layer part having a discharge port capable of discharging. Subsequently, saturated steam at 100 ° C. was circulated at a flow rate of 100 g / min for 90 seconds in an air atmosphere at atmospheric pressure. After the flow of water vapor was stopped, the granular crystallized product was taken out and dehydrated with a centrifugal dehydrator. As a result of analyzing the obtained granular crystallized product, the heat of crystallization (ΔHc) was 9 J / g, the heat of fusion (ΔHm) was 15 J / g, and the weight average molecular weight was 7,000. This operation was repeated to prepare a necessary amount of granular materials.
The obtained granular material is charged into a 100 liter double cone dryer equipped with an introduction pipe capable of controlling the temperature of the circulating gas, a circulating gas distillation pipe capable of external cooling, and a trap having a sufficient heat transfer area. While distilling the water from the outside to 5 ° C. and cooling the trap to −40 ° C., nitrogen at a dew point temperature of −80 ° C. was passed through 10 liters (25 ° C., value at atmospheric pressure) / hr, and 80 ° C. 2 hours at 100 ° C., 2 hours at 100 ° C., 1 hour at 130 ° C., 1 hour at 150 ° C., 1 hour at 170 ° C., and then cooled to room temperature to take out the contents.
The obtained granular crystallized product was not fused, and its shape was a cylindrical shape having a diameter of about 2 mm and a length of about 3 mm. The weight average molecular weight was 7,000, the melting point was 185 ° C., the heat of fusion (ΔHm) was 46 J / g, and the heat of crystallization (ΔHc) was not observed. Moreover, the generation amount of fine powder was 550 ppm. The obtained aliphatic polyhydroxycarboxylic acid granular crystallized product is referred to as granular crystallized product B2.

(B) Solid-phase polymerization Implemented except that the granular crystallized product B2 was used, the reaction pressure was set to 0.1 kPa, and the flow rate of flowing nitrogen gas was set to 0.097 l / hr (20 ° C., value at normal pressure). A solid phase polymerization reaction was carried out under the same conditions as in Example 1 (B). The superficial velocity of nitrogen gas is 420 m / hr.
The weight average molecular weight of the aliphatic polyhydroxycarboxylic acid obtained after the solid phase polymerization reaction was 108,000. The increase in the weight average molecular weight per hour obtained by dividing the difference in weight average molecular weight before and after the reaction by the reaction time is 3,367, which is 0.06 times the amount of nitrogen relative to Reference Example 1 or Reference Example 2. Even at a high flow rate, it was possible to produce a high molecular weight aliphatic polyhydroxycarboxylic acid at a high polymerization rate.

[Example 8]
(A) Crystallization treatment A granular crystallized product was obtained in the same manner as in Example 1 (A) except that the aliphatic polyhydroxycarboxylic acid granular product C was used. The obtained granular crystallized product has a cylindrical shape with a diameter of about 2 mm and a length of about 3 mm, a weight average molecular weight of 56,000, a melting point of 193 ° C., and a heat of fusion (ΔHm) of 58 J / g. The amount of heat of formation (ΔHc) was not observed. The obtained aliphatic polyhydroxycarboxylic acid granular crystallized product is referred to as granular crystallized product C2.
(B) Solid-phase polymerization Using a granular crystallized product C2, the reaction pressure was 0.15 kPa, the flow gas was carbon dioxide with a dew point of -85 ° C, and the flow rate was 0.106 liter / hr (20 ° C, normal pressure). The solid phase polymerization reaction was carried out under the same conditions as in Example 1 (B) except that the value in (1) was changed. The superficial velocity of carbon dioxide gas is 306 m / hr.
The weight average molecular weight of the aliphatic polyhydroxycarboxylic acid obtained after the solid phase polymerization reaction was 154,000. The increase in the weight average molecular weight per hour obtained by dividing the difference in weight average molecular weight before and after the reaction by the reaction time is 3,267, which is 0.06 times the amount of nitrogen relative to Reference Example 1 or Reference Example 2. Even at a high flow rate, it was possible to produce a high molecular weight aliphatic polyhydroxycarboxylic acid at a high polymerization rate.

[Example 9]
(A) Crystallization treatment A granular crystallized product was obtained in the same manner as in Example 1 (A) except that the aliphatic polyhydroxycarboxylic acid granular material D was used. The shape of the obtained granular crystallized product is a cylindrical shape having a diameter of about 2 mm and a length of about 3 mm, a weight average molecular weight of 48,000, a melting point of 190 ° C., and a heat of fusion (ΔHm) of 51 J / g. The amount of heat of formation (ΔHc) was not observed. The obtained aliphatic polyhydroxycarboxylic acid granular crystallized product is referred to as granular crystallized product D2.
(B) Solid-phase polymerization Implemented except that granular crystallized product D2 was used, the reaction pressure was 0.15 kPa, and the flow rate of flowing nitrogen gas was 0.106 liter / hr (20 ° C., value at normal pressure). A solid phase polymerization reaction was carried out under the same conditions as in Example 1 (B). The superficial velocity of nitrogen gas is 306 m / hr. The weight average molecular weight of the aliphatic polyhydroxycarboxylic acid obtained after the solid phase polymerization reaction was 146,000. The increase in the weight average molecular weight per hour obtained by dividing the difference in weight average molecular weight before and after the reaction by the reaction time is 3,267, which is 0.06 times the amount of nitrogen relative to Reference Example 1 or Reference Example 2. Even at a high flow rate, it was possible to produce a high molecular weight aliphatic polyhydroxycarboxylic acid at a high polymerization rate.

[Example 10]
(A) Crystallization treatment Using the aliphatic polyhydroxycarboxylic acid particulate E, the temperature condition was 80 ° C. for 5 hours, the temperature was subsequently raised to 100 ° C. for 3 hours, and then the temperature was raised to 120 ° C. for 3 hours. Subsequently, a granular crystallized product was obtained in the same manner as in Example 1 (A) except that the temperature was raised and the temperature was changed to 145 ° C. for 2 hours.
The obtained granular crystallized product has a cylindrical shape with a diameter of about 2 mm and a length of about 3 mm, a weight average molecular weight of 45,000, a melting point of 162 ° C., and a heat of fusion (ΔHm) of 50 J / g. The amount of heat of formation (ΔHc) was not observed. The obtained aliphatic polyhydroxycarboxylic acid granular crystallized product is referred to as granular crystallized product E2.
(B) Solid phase polymerization Using the granular crystallized product E2, the temperature of the solid phase polymerization reaction was set to 145 ° C., the reaction pressure was set to 0.15 kPa, and the flow rate of flowing nitrogen gas was 0.112 liter / hr (20 The solid phase polymerization reaction was carried out under the same conditions as in Example 1 (B) except that the values were set to ° C. and values at normal pressure. The superficial velocity of nitrogen gas is 306 m / hr. The weight average molecular weight of the aliphatic polyhydroxycarboxylic acid obtained after the solid phase polymerization reaction was 136,000. The difference in weight average molecular weight before and after the reaction is divided by the reaction time, and the increase in the weight average molecular weight per hour is 3,033. Compared to Reference Example 1 or Reference Example 2, the amount of nitrogen is 0.07 times or less. Even at a high flow rate, it was possible to produce a high molecular weight aliphatic polyhydroxycarboxylic acid at a high polymerization rate.

[Example 11]
(A) Crystallization treatment A granular crystallized product was obtained in the same manner as in Example 10 (A) except that the aliphatic polyhydroxycarboxylic acid granular material F was used. The shape of the obtained granular crystallized product is a cylindrical shape having a diameter of about 2 mm and a length of about 3 mm, a weight average molecular weight of 43,000, a melting point of 160 ° C., and a heat of fusion (ΔHm) of 49 J / g. The amount of heat of formation (ΔHc) was not observed. The obtained aliphatic polyhydroxycarboxylic acid granular crystallized product is referred to as granular crystallized product F2.
(B) Solid phase polymerization A solid phase polymerization reaction was carried out under the same conditions as in Example 10 (B) except that the granular crystallized product F2 was used. The weight average molecular weight of the aliphatic polyhydroxycarboxylic acid obtained after the solid phase polymerization reaction was 129,000. The increase in the weight average molecular weight per hour obtained by dividing the difference between the weight average molecular weight before and after the reaction by the reaction time is 2,867, which is 0.07 times the amount of nitrogen relative to Reference Example 1 or Reference Example 2. Even at a high flow rate, it was possible to produce a high molecular weight aliphatic polyhydroxycarboxylic acid at a high polymerization rate.

[Reference Example 3]
The solid phase polymerization reaction was carried out using a moving bed type continuous reaction apparatus.
The reactor having a moving bed has an inner diameter of 20 cm and a height of 400 cm, and is installed vertically. The outside of the reactor has a jacket structure and is heated by a heat medium. A gas supply port heated to a predetermined temperature and a pressure inside the reactor are maintained while maintaining the pressure inside the reactor. On the other hand, equipment capable of discharging acid is provided with a vent port for discharging an inert gas and equipment capable of supplying an aliphatic polyhydroxycarboxylic acid granular crystallized product at the upper part of the reactor.
The granular crystallized product A3 obtained by repeatedly carrying out the same method as in Example 5 (A) is fed at 2.45 kg / hr from the upper part of the reactor having the moving bed, and from the lower part of the reactor having the moving bed. A solid phase polymerization reaction was carried out while extracting at 2.45 kg / hr.
The reactor having the moving bed is maintained at a temperature of 170 ° C., and from the lower part of the reactor, nitrogen gas having a dew point of −90 ° C., 20 ° C. and a flow rate at normal pressure of 10385.78 liters / hr is supplied. After heating to 170 ° C., the reaction was carried out while alternatingly contacting the flow gas and the granular crystallized product by discharging from the vent port installed in the upper part of the reactor while flowing through the reactor.
The average flow rate of nitrogen gas is 4239 liters / hr per kg of granular crystallization product in terms of atmospheric pressure and 20 ° C., the superficial velocity of the flow of nitrogen gas is 500 m / hr, and the aliphatic polyhydroxycarboxylic acid The average residence time inside the reactor is 32 hours.
Based on the time when the reaction system was stable, the weight average molecular weight of the aliphatic polyhydroxycarboxylic acid obtained after 32 hours was 91,000. The increase in the weight average molecular weight per hour obtained by dividing the difference in weight average molecular weight before and after the reaction by the average residence time was 1,125.

[Example 12]
The solid phase polymerization reaction was carried out using a moving bed type continuous reaction apparatus.
The reactor having a moving bed has an inner diameter of 20 cm and a height of 400 cm, and is installed vertically. The outside of the reactor has a jacket structure and is heated by a heat medium. A gas supply port heated to a predetermined temperature and a pressure inside the reactor are maintained while maintaining the pressure inside the reactor. On the other hand, there is a facility capable of discharging an acid, while a vent port for controlling the pressure of an inert gas supply facility at the upper part of the reactor and an aliphatic polyhydroxycarboxylic acid particulate while maintaining the pressure inside the reactor. Equipment capable of supplying a crystallized product is provided.
The granular crystallized product A3 obtained by repeatedly carrying out the same method as in Example 5 (A) is fed at 2.45 kg / hr from the upper part of the reactor having the moving bed, and from the lower part of the reactor having the moving bed. A solid phase polymerization reaction was carried out while extracting at 2.45 kg / hr.

The reactor having the moving bed is maintained at a temperature of 170 ° C., and nitrogen gas having a dew point of −90 ° C., 20 ° C. and a flow rate of 46.136 liters / hr at normal pressure is supplied from the lower part of the reactor as 170 ° C. After heating to 0 ° C., the gas inside the reactor was discharged from the vent port installed at the top of the reactor while maintaining the pressure inside the reactor at 0.15 kPa, thereby allowing the gas to flow and the granular crystals. The reaction was carried out with alternating contact with the compound.
The average flow rate of nitrogen gas is 18.831 liter / hr per 1 kg of granular crystallized substance in terms of atmospheric pressure and 20 ° C. The superficial velocity of the nitrogen gas is 1,500 m / hr. The average residence time of the aliphatic polyhydroxycarboxylic acid inside the reactor is 32 hours.
Based on the time when the reaction system was stable, the weight average molecular weight of the aliphatic polyhydroxycarboxylic acid obtained after 32 hours was 156,000. The amount of increase in weight average molecular weight per hour obtained by dividing the difference in weight average molecular weight before and after the reaction by the average residence time is 3,150, and even when the nitrogen flow rate is 0.004 times that of Reference Example 3, It was possible to produce a high molecular weight aliphatic polyhydroxycarboxylic acid at a high polymerization rate.

According to the method of the present invention, a high-molecular weight aliphatic polyhydroxycarboxylic acid that can be substituted for general-purpose resins such as packaging materials, agricultural materials, civil engineering and building materials, and machine parts, reduces the amount of gas used. Thus, it is preferably used as a method for easily producing at a high polymerization rate by a method having excellent continuous stability.

Claims (10)

In the production of an aliphatic polyhydroxycarboxylic acid by polycondensation, at least part of the polycondensation reaction, the crystallized aliphatic polyhydroxycarboxylic acid prepolymer is subjected to 90 m / hr under a pressure condition of 1 kPa or less. A method for producing an aliphatic polyhydroxycarboxylic acid, characterized in that an aliphatic polyhydroxycarboxylic acid is produced by solid-phase polymerization at a temperature that maintains a solid state while flowing a gas at the above superficial velocity. The method for producing an aliphatic polyhydroxycarboxylic acid according to claim 1, wherein a superficial velocity at which the gas is circulated is 250,000 m / hr or less. The method for producing an aliphatic polyhydroxycarboxylic acid according to claim 1 or 2, wherein the gas flow rate is 50 liters / hr or less per kg of the aliphatic polyhydroxycarboxylic acid. The method for producing an aliphatic polyhydroxycarboxylic acid according to any one of claims 1 to 3, wherein solid phase polymerization is performed in a fixed bed reactor. The method for producing an aliphatic polyhydroxycarboxylic acid according to any one of claims 1 to 3, wherein solid phase polymerization is performed in a moving bed reactor. 6. The method for producing an aliphatic polyhydroxycarboxylic acid according to claim 5, wherein the solid phase polymerization is carried out by bringing the aliphatic polyhydroxycarboxylic acid prepolymer into alternating current contact with the flowing gas. The method for producing an aliphatic polyhydroxycarboxylic acid according to any one of claims 1 to 6, wherein solid phase polymerization is performed in a tower reactor. The weight average molecular weight of the aliphatic polyhydroxycarboxylic acid prepolymer subjected to crystallization treatment is 25,000 or more, and the aliphatic polyhydroxycarboxylic acid according to any one of claims 1 to 7, Production method. The method for producing an aliphatic polyhydroxycarboxylic acid according to any one of claims 1 to 8, wherein the aliphatic polyhydroxycarboxylic acid contains at least 80 mol% of an aliphatic hydroxycarboxylic acid unit. The method for producing an aliphatic polyhydroxycarboxylic acid according to any one of claims 1 to 9, wherein the aliphatic polyhydroxycarboxylic acid contains at least 80 mol% of a glycolic acid unit.