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WO1999019378A1 - Procedes de production d'acide polyhydroxy carboxylique et de glycolide - Google Patents

Procedes de production d'acide polyhydroxy carboxylique et de glycolide Download PDF

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Publication number
WO1999019378A1
WO1999019378A1 PCT/JP1998/004618 JP9804618W WO9919378A1 WO 1999019378 A1 WO1999019378 A1 WO 1999019378A1 JP 9804618 W JP9804618 W JP 9804618W WO 9919378 A1 WO9919378 A1 WO 9919378A1
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WIPO (PCT)
Prior art keywords
solid
prepolymer
temperature
acid
reaction
Prior art date
Application number
PCT/JP1998/004618
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English (en)
Japanese (ja)
Inventor
Mitsuru Hoshino
Kazuyuki Yamane
Yukichika Kawakami
Yasushi Okada
Original Assignee
Kureha Kagaku Kogyo K.K.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
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Publication date
Priority claimed from JP29633397A external-priority patent/JPH11116666A/ja
Priority claimed from JP31123497A external-priority patent/JPH11130847A/ja
Application filed by Kureha Kagaku Kogyo K.K. filed Critical Kureha Kagaku Kogyo K.K.
Publication of WO1999019378A1 publication Critical patent/WO1999019378A1/fr

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G63/00—Macromolecular compounds obtained by reactions forming a carboxylic ester link in the main chain of the macromolecule
    • C08G63/02—Polyesters derived from hydroxycarboxylic acids or from polycarboxylic acids and polyhydroxy compounds
    • C08G63/06—Polyesters derived from hydroxycarboxylic acids or from polycarboxylic acids and polyhydroxy compounds derived from hydroxycarboxylic acids
    • C08G63/08—Lactones or lactides
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G63/00—Macromolecular compounds obtained by reactions forming a carboxylic ester link in the main chain of the macromolecule
    • C08G63/02—Polyesters derived from hydroxycarboxylic acids or from polycarboxylic acids and polyhydroxy compounds
    • C08G63/06—Polyesters derived from hydroxycarboxylic acids or from polycarboxylic acids and polyhydroxy compounds derived from hydroxycarboxylic acids
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G63/00—Macromolecular compounds obtained by reactions forming a carboxylic ester link in the main chain of the macromolecule
    • C08G63/78—Preparation processes
    • C08G63/80—Solid-state polycondensation

Definitions

  • the present invention relates to a method for producing polyhydroxycarboxylic acid such as polyglycolic acid, and more particularly, to economically produce polyhydroxycarboxylic acid having excellent melt moldability and mechanical properties. On how to do it.
  • Polyhydroxycarboxylic acid obtained by the production method of the present invention is a polymer having a high molecular weight, has biodegradability, and can be obtained as a high-quality polymer. It is useful as a substitute for medical materials and general-purpose resins, for example.
  • Polyhydroxycarboxylic acid typified by polyglycolic acid and polylactic acid, is degraded in the natural environment and eventually has the biodegradability of being converted into water and carbon dioxide by microorganisms .
  • polyhydroxycarboxylic acids are receiving attention in fields such as medical materials and general-purpose resin substitutes.
  • biodegradable polyhydroxycarboxylic acid can be said to meet the needs of the times.
  • conventionally it has been very difficult to economically obtain a high-molecular-weight, high-quality polyhydroxycarboxylic acid.
  • poly (hydroxycarboxylic acid) production methods include cyclic dimers such as lactide (a cyclic dimer of lactic acid) and glycolide (a cyclic dimer of glycolic acid).
  • cyclic dimers such as lactide (a cyclic dimer of lactic acid) and glycolide (a cyclic dimer of glycolic acid).
  • the cyclic dimer is catalyzed (eg, A method of performing ring-opening melt polymerization in the presence of tin stannate) is known.
  • a polymer having a high molecular weight can be obtained.
  • this method has complicated reaction steps and operations.
  • JP-A-6-635360 describes that a hydroxycarboxylic acid or an oligomer thereof is subjected to a dehydration polycondensation reaction in a reaction mixture containing an organic solvent in the substantial absence of water. Then, a method for producing a polyhydroxycarponic acid having a weight average molecular weight of not less than 1500 is described.
  • the examples in this publication show that polylactic acid having a high molecular weight of up to about 180,000 was obtained.
  • the publication does not describe any examples relating to polyglycolic acid. Polyglycolic acid does not dissolve in chloroform-methylene chloride.
  • the average molecular weight measurement method described in the official gazette that is, gel partitioning in a crotch-form solution
  • Chromatography and the method of measuring logarithmic viscosity using a Ubbelohde viscometer with a methylene chloride solution cannot be applied to polyglycolic acid. Therefore, according to the content of this publication, it can be said that polyglycolic acid can be obtained as a polymer having a weight average molecular weight of 150,000 or more necessary for exhibiting sufficient mechanical properties by the above method. It cannot be estimated.
  • Japanese Patent Application Laid-Open No. 7-173264 discloses that a hydroxycarboxylic acid ester or a mixture thereof or an oligomer thereof is subjected to a condensation reaction in the presence of a catalyst to give a weight average molecular weight of about 15
  • a process for producing polyhydroxycarboxylic acids of at least 2,000 is disclosed.
  • the gazette It is described that the weight average molecular weight of the poly (hydroxycarboxylic acid) obtained by the method is as low as about 15,500 to 100,000. Therefore, this production method cannot obtain a high molecular weight polyhydroxycarboxylic acid having sufficient mechanical properties.
  • a low molecular weight polymer is prepared by polycondensation of a hydroxycarboxylic acid, and the low molecular weight polymer is prepared.
  • a method of prolonging quenching by reacting with a binder Specifically, Japanese Patent Application Laid-Open No.
  • 62-280220 discloses that (co) polycondensation of lactic acid and glycolic acid is carried out to obtain low molecular weight polylactide, polyglycolide, Alternatively, a copolycondensate thereof is prepared and then reacted with an oxychloride selected from a dichloride compound or thionyl chloride, and then subjected to a melt polycondensation reaction, or an amine compound is added. It describes a method for producing high molecular weight polylactide, polyglycolide, or a copolycondensate thereof by reacting.
  • the examples in the publication show that the obtained polymer has a molecular weight of less than 20,000, and its mechanical properties are insufficient, so that its use is limited. With this method, it is not possible to obtain polyhydroxycarboxylic acid exhibiting sufficient mechanical properties.
  • Japanese Patent Application Laid-Open No. H11-156319 discloses that when glycolic acid and Z or lactic acid are polycondensed to produce an aliphatic polyester, ethylene glycol, 1,2-propylene glycol and the like are used.
  • a method for producing an aliphatic polyester which is added to glycols to increase the molecular weight by solid phase polymerization is disclosed.
  • this method has a problem that an undesirable heterogeneous structure is introduced into the formed polymer.
  • hydroxycarboxylic acids such as glycolic acid are difficult to isolate and purify using general-purpose purification methods such as distillation, so complicated operations are required to obtain high-purity substances.
  • general-purpose purification methods such as distillation
  • the yield was low. Therefore, high-purity hydroxycarboxylic acids are very expensive and their industrial use is very limited.
  • An object of the present invention is to provide a method for economically producing a high molecular weight polyhydroxycarboxylic acid having excellent melt moldability and mechanical properties.
  • Another object of the present invention is to provide a method for economically producing high-quality, high-molecular-weight polyhydroxycarboxylic acid with reduced coloring.
  • the present inventors have made intensive studies to overcome the problems of the prior art, and as a result, polycondensation of an alkyl glycolate to produce a glycolic acid prepolymer was performed. It has been found that high-molecular-weight polyglycolic acid can be obtained by solid-phase polymerization of poly (glycolic acid). According to this method, a high-molecular-weight polyglycolic acid having a weight-average molecular weight of 150,000 or more can be obtained at relatively low cost. The ease of purification eliminates the problem of introducing unwanted heterologous structures into the resulting polymer. The method of the present invention can be extended to a method for producing polyhydroxycarboxylic acid using a hydroxycarboxylic acid alkyl ester.
  • the present inventors have further studied and found that at least a part (that is, part or all) of the hydroxycarboxylic acid alkyl ester is hydrolyzed to give the hydroxycarboxylic acid.
  • the hydrolysis product By subjecting the hydrolysis product to polycondensation to form a prepolymer, and then subjecting the produced prepolymer to solid-state polymerization to obtain a high molecular weight High-quality polyhydroxycarboxylic acid was obtained.
  • the purification of the hydroxycarboxylic acid ester is easy, so that a high-purity hydroxycarboxylic acid ester can be used.
  • Hydroxycarboxylic acids in the product also have high purity.
  • a hydrolysis product as a raw material similarly to the case where a hydroxycarboxylic acid ester is used as a raw material, a high molecular weight polyglycolic acid having a weight average molecular weight of 150,000 or more is used. Can be obtained at relatively low cost, and the problem of introducing an undesirable heterogeneous structure into the formed polymer is eliminated. Further, according to the production method using the hydrolysis product, it is possible to obtain high-quality polyhydroxycarboxylic acid with little coloring. This production method is particularly suitable as a method for producing high-quality, high-molecular-weight polyglycolic acid.
  • the glycolic acid prepolymer is ground into a powder and supplied to the reactor in a very small amount (approximately 20 g Zh) while being reduced in pressure (12 to 15 torr) to 270 to 28
  • a method has been proposed in which depolymerization is carried out by heating to a high temperature of 0 ° C. and the generated glycol is collected in a trap (US Pat. No. 2,668,162).
  • this method is difficult to scale up, and the prepolymer becomes heavy during heating and remains in the reactor as a large amount of residue. Cleaning is also complicated.
  • Another object of the present invention is to provide a novel method for economically producing high-purity glycolide.
  • the present invention has been completed based on these findings.
  • hydroxycarboxylic acid-containing hydrolysis product (B) obtained by hydrolyzing at least a part of the hydroxycarboxylic acid alkyl ester to form a prepolymer. Then, (2) a method for producing polyhydroxycarboxylic acid by solid-phase polymerization of the produced prepolymer is provided.
  • the hydroxycarboxylic acid alkyl ester is used.
  • the stele is an alkyl glycolate
  • the prepolymer is a prepolymer of glycolic acid
  • the polyhydroxycarboxylic acid is polyglycolic acid. Is provided.
  • a hydroxycarboxylic acid alkyl ester (A) or a hydroxycarboxylic acid-containing product obtained by hydrolyzing a part or all of the hydroxycarboxylic acid alkyl ester is used as a starting material.
  • a hydrolysis product (B) is used as a starting material.
  • hydroxycarboxylic acids examples include lactic acid, glycolic acid, 2-hydroxyisobutanoic acid, 3-hydroxybutanoic acid, 4-hydroxybutanoic acid, and 6-hydroxycabronate. Acids etc. can be mentioned. Among these, lactic acid and glycolic acid are preferred, and glycolic acid is particularly preferred.
  • hydroxycarboxylic acid alkyl ester used in the present invention an ester of hydroxycanolevonic acid and a lower alcohol is preferable.
  • Lower alcohols include methanol, ethanol, phenol, and isopro. Examples include Knoll, Butanol, Pennell, Hexanol, Heptanol, and Octanol.
  • methanol, ethanol, phenol and isop Alcohols having 1 to 4 carbon atoms, such as lopanol and butanol are particularly preferred. This is because the use of a hydroxycarboxylic acid alkyl ester having 1 to 4 carbon atoms in the alkyl group facilitates dealcoholization during polycondensation and hydrolytic decomposition. Since these hydroxycarboxylic acid alkyl esters can be isolated by distillation or the like, high-purity products can be obtained relatively easily.
  • hydroxycarboxylic acid esters include, for example, methyl glycolate, ethyl glycolate, ethyl glycolate n-propyl, and glycolate.
  • examples include isopropyl, n-butyl glycolate, isobutyl glycolate, and t-butyl glycolate.
  • methyl glycolate and ethyl glycolate are particularly preferred because of their ease of dealcoholization.
  • the purity of the alkyl ester of hydroxycarboxylic acid is not particularly limited.However, in order to obtain a high-molecular-weight polymer, the content of a low-molecular-weight compound serving as an impurity that stops the polymerization reaction is reduced as much as possible. It is desirable to keep it.
  • impurities include, for example, when methyl glycolate is used as the alkyl ester of hydroxycarboxylic acid, methyl methoxyacetate, diglycol And methyl oleate.
  • the content of these impurities is usually less than 1% by weight, preferably less than 0.3% by weight, and more preferably less than 0.1% by weight, which is sufficient for increasing the molecular weight. It is desirable in doing.
  • azoalkylyl hydroxycarboxylates are usually used alone, but may be used in combination of two or more as required. However, when a mixture of two or more alkyl hydroxycarbonates is used, it is desirable for the solid phase polymerization to be performed so that the crystallinity of the resulting prepolymer is not hindered.
  • Other monomers include, for example, lactic acid, glycolic acid, 2—hydroxyisobutanoic acid, 3—hydroxybutanoic acid, 4-hydroxybutanoic acid, 6—hydroxycabronic acid, and the like.
  • Hydroxycarboxylic acid Ethylene oxalate, Lactide, Lactones (eg, / 3-propiolactone, / 3-Butyrolactone, Pinoclorola Cuton, arbutyrolactone, (5—valerolactone, / 3—methyl-1 5—norrerolactone, £ 1 liter prolactone), lingerle Methylene carbonate, and cyclic monomers such as 1,3-dioxane; fats such as ethylene glycol, propylene glycol, and 1,4-butanediol Aliphatic dicarbonates and aliphatic dicarbonates such as succinic acid and adipic acid Or a mixture of substantially equimolar amounts thereof with an alkyl ester; etc.
  • the other monomers may be used alone or in combination of two or more. The amount of other monomers used is desirably within a range that does not inhibit the crystallinity of the prepolymer.
  • Hydrolysis of the hydroxycarboxylic acid alkyl ester can be easily carried out by adding water to the hydroxycarboxylic acid alkyl ester and heating. Water may be added to the reaction system in its entirety at the start of the hydrolysis reaction, but may be added in several portions if necessary, or may be added continuously.
  • a solid catalyst When hydrolyzing the hydroxycarboxylic acid alkyl ester, a solid catalyst may be used, if necessary.
  • the solid catalyst include sulfonate-based ammonium salt-based ion exchange resins. After the completion of the hydrolysis reaction, these solid catalysts can be easily removed by filtration or the like.
  • a solid catalyst is filled in a column, and the mixture can be hydrolyzed by passing a mixture of a hydroxycarboxylic acid alkyl ester and water. Hydrolysis of hydroxycarboxylic acid alkyl esters produces hydroxycarboxylic acids and alcohols. Removal of the formed alcohol gives the hydroxycarboxylic acid.
  • Partial hydrolysis of the hydroxycarboxylic acid alkyl ester results in a mixture of hydroxycarboxylic acid and hydroxycarboxylic acid alkyl ester.
  • a hydrolysis product is referred to as a hydroxycarboxylic acid-containing hydrolysis product (B).
  • hydrolysis reaction is an elimination equilibrium reaction between the ester group and the hydroxyl group of the hydroxycarboxylic acid alkyl ester, it is necessary to increase the amount of water added and to remove Z or the produced alcohol out of the system. And can proceed efficiently.
  • the amount of water added in the hydrolysis reaction is not particularly limited as long as it is at least an amount sufficient to hydrolyze at least a part of the hydroxycarboxylic acid ester. Usually, it is not less than equivalent (more than equimolar), preferably not less than 2 equivalents and not more than 20 equivalents. If the amount of water added is too small, the reaction rate of the hydrolysis reaction becomes extremely slow, and it is difficult to increase the hydrolysis reaction rate to a desired level. Even if the amount of water added is too large, the effect of increasing the efficiency of the hydrolysis reaction is saturated, so that it is not economical.
  • the hydrolysis of the alkyl hydroxycarbonate need not necessarily be carried out quantitatively, but is usually at least 50 mol%, preferably at least 80 mol%, of the charged hydroxycarboxylic acid alkyl ester. More preferably, at least 99 mol% is hydrolyzed to hydroxycarboxylic acid.
  • the upper limit of the hydrolysis reaction rate is 100 mol%.
  • the hydrolysis product (B) is produced when the hydrolysis reaction rate is more than 99 mol%. Is substantially all hydroxycarboxylic acid.
  • the hydrolysis product (B) is a mixture in which, when the hydrolysis reaction rate is, for example, 80 mol%, 80 mol% is hydroxycarboxylic acid and the remaining 20 mol% is alkyl hydroxycarbonate. is there.
  • Hydroxycarboxylic acid alkyl ester (A) has a too low rate of hydrolysis because of the low rate of polycondensation and solid-state polymerization in the absence of a catalyst. Under this condition, it becomes difficult to shorten the reaction time or to improve the yield of the polycondensate or the solid-phase polymer.
  • hydroxycarboxylic acid alkyl esters tend to be colored when polycondensation or solid-phase polymerization is carried out using a catalyst. Therefore, if a hydrolysis product (B) having a hydrolysis reaction rate that is too low is used, It becomes difficult to prevent coloring in the presence of a catalyst.
  • the hydrolysis product (B) in which at least 10 mol%, and in many cases at least 30 mol% of the hydroxycarboxylic acid alkyl ester is hydrolyzed to hydroxycarboxylic acid, the reaction rate and the prevention of discoloration can be improved. Some improvement effects can be obtained.
  • the hydrolysis reaction and the dehydration reaction can proceed simultaneously. Alkyl hydroxycarbonate remaining unreacted during the hydrolysis reaction may be removed from the reaction system before the polycondensation reaction and during the Z or polycondensation reaction. After the hydrolysis reaction, water or produced alcohol may remain in the reaction system.
  • the operation of dehydration and dealcoholation during the hydrolysis reaction may involve a polycondensation reaction of hydroxycarboxylic acid ester and / or hydroxycarboxylic acid. May not always be clearly distinguished in stages. Therefore, in the present invention, when the hydrolysis product (B) is used, at least a part of the polycondensation reaction may proceed during the hydrolysis reaction. That is, a polycondensation reaction product may be contained in the hydrolysis product.
  • the step of hydrolyzing the hydroxycarboxylic acid alkyl ester (A) to produce the hydroxycarboxylic acid-containing hydrolysis product (B) is carried out by the following pre-polymerization reaction by polycondensation reaction. This corresponds to the first step of (1).
  • a hydroxycarboxylic acid-containing hydrolysis product obtained by hydrolyzing at least a part of the hydroxycarboxylic acid alkyl ester (A) or the hydroxycarboxylic acid alkyl ester is obtained.
  • the product (B) is polycondensed to form a hydroxycarboxylic acid prepolymer (hereinafter simply referred to as “prepolymer”).
  • prepolymer a polycondensation reaction involving a dealcoholization reaction and a Z or dehydration reaction proceeds.
  • a polycondensation reaction may be performed subsequently in a reactor in which the hydroxycarboxylic acid alkyl ester is hydrolyzed, The hydrolysis reaction and the polycondensation reaction may be performed in separate apparatuses.
  • an inert gas such as nitrogen gas is added to the reaction system to facilitate the dealcoholization reaction and the Z or dehydration reaction. The flow may be continued, or the pressure of the reaction system may be reduced.
  • the polycondensation reaction is usually above 80 ° C, preferably 100 to 230 ° C, more preferably 110 to 220 ° C, most preferably 120 ⁇ 2 1 0 Performed in a temperature range of ° C. If the reaction temperature is too low, the reaction rate will increase significantly. If the reaction temperature is too high, the thermal stability of the formed prepolymer is impaired, and the prepolymer is easily colored. The reaction temperature does not need to be kept constant during the polycondensation reaction, but may be varied as needed.
  • the polycondensation of (A) or the hydrolysis product containing hydroxycarboxylic acid (B) produces prepolymers of relatively low molecular weight, often crystalline. If the prepolymer is not crystalline, it tends to be in a molten state during the solid-state polymerization reaction, and as a result, side reactions are likely to occur.
  • the weight average molecular weight of the prepolymer is usually from 5,000 to 5,000, preferably less than 50,000, and preferably from 8,000 to 100,000. If the weight average molecular weight of the prepolymer is too low, it takes a long time to obtain a high molecular weight polyhydroxycarboxylic acid by the subsequent solid-phase polymerization, which is not economical.
  • the weight average molecular weight is not less than 150,000 or more depending on the polycondensation of the hydroxycarboxylic acid alkyl ester (A) or the hydrolysis product (B) alone without combining with solid-state polymerization. It is difficult to obtain high molecular weight polymers.
  • the glass transition temperature of the prepolymer is usually 100 ° C or lower, and is usually about 20 to 50 ° C. Since the prepolymer has an appropriate glass transition temperature and is crystalline, solid-state polymerization can be easily performed.
  • the melting point of the prepolymer is preferably in the range of 130 to 230, more preferably in the range of 150 to 225 ° C. If the melting point of the prepolymer is too low, it is difficult to shorten the reaction time by setting the solid-state polymerization temperature high.
  • the polycondensation of (B) is reversed when the resulting prepolymer reaches a predetermined molecular weight. End point.
  • the produced prepolymer has a relatively low molecular weight, it is liquid at the end of the polycondensation reaction, and solidifies and crystallizes upon cooling. If the resulting prepolymer has a relatively high molecular weight, the solidification stage is the end point of the polycondensation reaction. After the completion of the reaction, solid-phase polymerization may be performed as it is.However, in order to increase the total surface area, it is preferable that the prepolymer is granulated by a treatment such as pulverization and then solid-phase polymerization is performed. It is more efficient.
  • the prepolymer has a crystallinity of at least 10% when determined by the amount of molten enthalpy. If the crystallinity is too low, solid-state polymerization becomes difficult and side reactions are likely to occur.
  • the crystallinity of the prepolymer is preferably greater than or equal to 20%, more preferably greater than or equal to 30%, and often greater than or equal to 40%.
  • the upper limit of the crystallinity is usually about 70%, and in many cases about 60%.
  • the synthesis of the prepolymer can be carried out without a catalyst, but a catalyst may be used to shorten the polymerization time.
  • Catalysts include stannous chloride, stannic chloride, stannous sulfate, stannous oxide, stannic oxide, tetraphenyltin, stannous octoate, and stannous acetate.
  • Tin-based catalysts such as monoacid and stannic acetate; Titanium-based catalysts such as titanium tetrachloride, isopropionate titanate, and butyl titanate; metal germanium, germanium tetrachloride, and germanium oxide Germanium-based catalysts such as rumanium; and metal oxide-based catalysts such as zinc oxide, antimony trioxide, lead oxide, aluminum oxide, and iron oxide.
  • Titanium-based catalysts such as titanium tetrachloride, isopropionate titanate, and butyl titanate
  • Germanium-based catalysts such as rumanium
  • metal oxide-based catalysts such as zinc oxide, antimony trioxide, lead oxide, aluminum oxide, and iron oxide.
  • a polycondensation catalyst referenced to the metal atom, of the monomer 1 mole, preferable to rather the 1 X 1 0- 5 ⁇ 1 X 1 0 2 eq, favored more properly it is added at a rate of 3 X 1 0 one 5 ⁇ 5 X 1 0 ⁇ equivalent.
  • the monomer means a hydroxycarboxylic acid alkyl ester and Z or hydroxycarboxylic acid. If the addition amount of the polycondensation catalyst is too small, the polymerization time becomes long, and the purpose of adding the catalyst cannot be sufficiently achieved.
  • the polycondensation catalyst is added to the reaction system as it is, or dissolved or mixed in an appropriate liquid. The addition may be made at once or in portions. The polycondensation catalyst may be added to the reaction system at any time until the polycondensation reaction is substantially completed.
  • the synthesis of the prepolymer is preferably carried out without a catalyst in consideration of the suppression of coloring of the polyhydroxycarboxylic acid and the handling of the remaining catalyst.
  • a coloring inhibitor may be added if necessary.
  • a phosphorus compound can be suitably used as a coloring inhibitor. Examples of the phosphorus compound include phosphoric acid, trimethyl phosphinate, triethyl phosphinate, triphenyl phosphite, monomethyl polyphosphate, and polymethyl phosphate.
  • the phosphorus compound is preferably used in an amount of 0.01 to 10 parts by weight, more preferably 0.1 to 10 parts by weight, based on 100 parts by weight of the product theoretically obtained by the polycondensation reaction. 0 3 to 3 parts by weight are added. If the amount is too small, the effect of preventing coloration is small. If the amount is too large, the reaction rate of polycondensation may be reduced.
  • the phosphorus compound is added to the reaction system as it is, or dissolved or mixed in an appropriate liquid. Additions can be made in batches or split Is also good. The phosphorus compound may be added to the reaction system at any time until the polycondensation reaction is substantially completed.
  • a high molecular weight polyhydroxycarboxylic acid is produced by subjecting the prepolymer obtained by the above method to solid phase polymerization.
  • the shape of the prepolymer may be any of a lump, a pellet, a granule, a powder, and the like, and is not particularly limited. If the prepolymer is made finer by pulverization or the like, the total surface area increases, so that the solid phase reaction can be promoted.
  • the solid phase polymerization is usually carried out by heating to a temperature equal to or higher than the glass transition temperature of the prepolymer in an inert gas atmosphere, under reduced pressure, or in an inert solvent.
  • the polymerization reaction is performed in a solid state literally. Therefore, the upper limit of the reaction temperature of solid-state polymerization is determined by the melting point of the prepolymer and the solid-state polymerization reaction product.
  • the reaction temperature is lower than the melting point of the prepolymer, preferably 5 ° C or less of the melting point of the prepolymer, more preferably 10 ° C.
  • the pre-polymer is melted, so it can no longer be called solid-state polymerization, and it becomes melt polymerization.
  • U In melt polymerization, side reactions become very likely to occur and it is difficult to increase the molecular weight.
  • the prepolymer is heated to a temperature very close to the melting point and solid-state polymerization is initiated, side reactions are likely to occur, which tends to cause a decrease in molecular weight, generation of gas, coloring, and the like. Not good.
  • the pre-polymer or the product during the solid-state polymerization reaction (hereinafter, both are called ⁇ solid-state polymerization reaction
  • the melting point of In such a case, the reaction temperature of solid-state polymerization can be gradually increased.
  • the reaction temperature is increased during the solid-state polymerization at the start of the solid-state polymerization described above.
  • the temperature can be raised to a temperature exceeding the temperature, thereby increasing the reaction rate of solid-state polymerization. Therefore, for example, during the solid phase polymerization, the reaction temperature can be raised to a temperature higher than the melting point of the prepolymer produced in step (1), and the solid phase polymerization reaction can be continued.
  • the reaction temperature must be controlled to a temperature at which the solid-state polymerization reaction product maintains a solid state, and the melting point of the solid-state polymerization reaction product at that point should be 5 ° C or less. Preferably, it should be 1 o ° c or less.
  • the reaction temperature of solid-state polymerization is a temperature higher than the glass transition temperature of the prepolymer, from the viewpoints of the reaction rate, maintenance of the solid state, and the physical properties of the formed polymer. It is preferable that the temperature is appropriately determined within a temperature range at which the material can maintain a solid state.
  • the reaction temperature is often between 100 and 230. Preferably, it is determined within the range of C. More specifically, the temperature is higher than the glass transition temperature of the prepolymer, preferably 100 ° C or higher, and the melting point of the immediately preceding prepolymer obtained in step (1). At lower temperatures, solid state polymerization can be initiated and the reaction temperature can be raised as the melting point of the solid state polymerization reaction product increases during solid state polymerization.
  • the temperature is controlled to a temperature of 230 ° C or lower and the temperature at which the solid-state polymerization reaction product maintains a solid state. It is preferable to continue the phase polymerization.
  • Solid-phase polymerization is usually carried out under the following conditions: (1) under an atmosphere of an inert gas such as nitrogen or argon, (2) under reduced pressure, or (3) under an inert solvent such as liquid paraffin. This is done by heating the polymer. At the start of and during solid state polymerization, the reaction temperature is controlled to a temperature at which the prepolymer and the solid state polymerization reaction product maintain a solid state. By this solid-state polymerization, high-molecular-weight polymers can be obtained by avoiding undesired side reactions.
  • an inert gas such as nitrogen or argon
  • an inert solvent such as liquid paraffin
  • the molecular weight of the polymer produced by solid-state polymerization is 150,000 in order to exhibit stable and sufficient mechanical properties for applications such as films and molded products. As described above, more preferably, it is more preferably 200,000 or more.
  • Solid phase polymerization can be carried out without a catalyst, but a catalyst may be used to shorten the polymerization time.
  • Catalysts include stannous chloride, stannic chloride, stannous sulfate, stannous oxide, stannic oxide, tetraphenyltin, stannous octoate, and stannous acetate.
  • Tin-based catalysts such as acid and stannic acetate; Titanium-based catalysts such as titanium tetrachloride, isopropionate titanate and butyl titanate; metal germanium, germanium tetrachloride, and germanium oxide
  • a metal oxide catalyst such as zinc oxide, antimony trioxide, lead oxide, aluminum oxide, iron oxide, and the like.
  • the catalyst When a catalyst is used in the solid phase polymerization, the catalyst is usually used in an amount of 0.001 to 2 parts by weight, preferably 0.005 to 0 parts by weight, per 100 parts by weight of the prepolymer. . Add 5 parts by weight. If the amount of the catalyst is too small, the effect of shortening the solid-state polymerization time is small, and the purpose of adding the catalyst cannot be sufficiently achieved. If the amount of catalyst added is too large, the color of the formed polymer becomes too large, which may impair the commercial value.
  • the catalyst is added to the reaction system as it is or after being dissolved or mixed in an appropriate liquid. The catalyst may be added all at once or in portions. The catalyst is substantially Any time may be added to the reaction system until the solid-phase polymerization reaction is completed. However, in the solid-state polymerization reaction, it is preferable to carry out the reaction without a catalyst in consideration of suppressing the coloring of the produced polymer and handling the remaining catalyst.
  • a coloring inhibitor When performing solid phase polymerization, a coloring inhibitor can be added if necessary.
  • a coloring inhibitor a phosphorus compound can be suitably used.
  • the phosphorus compound include phosphoric acid, trimethyl phosphate, triethyl phosphate, triphenyl phosphate, monoethyl polyester polyphosphate, and polyethyl phosphate. Getyl ester, pyrrolinic acid, triethylpyrrolineate, hexamethylpyrrolineate, phosphite, triethyl phosphite, triphenyl phosphite And so on. These phosphorus compounds can be used alone or in combination of two or more.
  • the phosphorus compound is usually added in an amount of 0.001 to 10 parts by weight, preferably 0.003 to 3 parts by weight, based on 100 parts by weight of the prepolymer. If the amount is too small, the effect of preventing coloring is small, and if it is too large, the polymerization rate may be slow.
  • the phosphorus compound is added to the reaction system as it is, or dissolved or mixed in an appropriate liquid. The addition may be made at once or in portions.
  • the phosphorus compound may be added to the reaction system at any time as long as the solid-state polymerization reaction is practically completed. In the case where a coloring inhibitor has already been added during the synthesis of the prepolymer, it is not necessary to add the coloring inhibitor again during the solid phase polymerization, but it may be added if desired.
  • the solid-phase polymerization can be terminated preferably at any time when a polyhydroxycarboxylic acid having a weight average molecular weight of 150,000 or more is produced. It is more preferable to produce a polymer having a weight average molecular weight of 200,000 or more by solid phase polymerization. Manufacturing method of glycolide
  • the glycol since the glycol may sublime, by collecting the by-product glycolide, it is possible to obtain a high-purity glycolide. it can.
  • Glycolide has been used as a raw material for polyglycolic acid (polyglycolide) and glycolic acid copolymer, but it is economically efficient. It was very difficult to mass-produce the glycol.
  • At least one type of glycolic acid polymer selected from the group consisting of crystalline glycolic acid prepolymer and polyglycolic acid was added at 220 ° C or higher.
  • the solid-phase depolymerization is preferably performed at a temperature in the range of 220 ° C or more and less than 245 ° C.
  • the solid-phase depolymerization is performed under a temperature condition in which the glycolic acid polymer maintains a solid state.
  • the glycolic acid polymer has a melting point of 220 ° C. or more. If the melting point of the glycolic acid polymer is lower than 220 ° C before the solid phase depolymerization reaction, it is desirable to increase the melting point by heat treatment or the like. If the solid phase depolymerization temperature is higher than 245 ° C, the glycolic acid polymer is easily decomposed.
  • the glycolic acid polymer is obtained by polycondensing a glycolic acid alkyl ester or a glycolic acid-containing hydrolysis product obtained by hydrolyzing at least a part of the glycolic acid alkyl ester.
  • Prepolymers or polymers have a relatively high melting point, which allows for solid-state depolymerization at high temperatures, and high yields of glycosides. You.
  • Glycolic acid polymers include flakes, pellets, powders, particles, etc. Any shape can be used, but it is preferable to reduce the size by grinding to increase the reaction rate.
  • the conditions of the solid-phase depolymerization are the same as those of the solid-phase polymerization described above, except for the above temperature conditions. That is, in the solid phase depolymerization, when a glycolic acid prepolymer or a solid phase polymerization reaction product during the solid phase polymerization reaction of the prepolymer is used as a raw material, Compete with The solid-phase depolymerization is preferably carried out under a normal pressure under an inert gas stream or under reduced pressure. Glycoride generated by the solid-phase depolymerization sublimates, so that it can be recovered by collecting it outside the system.
  • the glycol In a pressurized system, the glycol is not discharged out of the system, so the equilibrium reaction between solid-phase depolymerization and solid-phase polymerization is likely to occur, and glycol is not easily generated. Isolation is often difficult and is not preferred.
  • the sublimated glycol can be recovered by a conventional method. Although the solid phase depolymerization occurs even at a temperature lower than 220 ° C, the reaction rate is slow. Therefore, in order to obtain a good yield of the glycol, the reaction temperature is set to 220 ° C or higher. On the other hand, when the reaction temperature exceeds 245 ° C, it becomes difficult to maintain the glycolic acid polymer in a solid state, and the glycolic acid polymer becomes heavy. Residue easily.
  • the yield of glycolide can be increased.
  • high-molecular-weight polyglycolic acid can be obtained at the same time without producing a heavy residue.
  • the glycol obtained by solid phase depolymerization can be used as it is, but if necessary, the purity can be further increased by a purification operation such as recrystallization.
  • the weight average molecular weight was determined under the following conditions using a GPC (gel permeation chromatography) analyzer.
  • HFIP Hydrophilicity Sopronol
  • HFIP—LG + HFIP—806 MX: 2 pieces: SHODEX HFIP—LG + HFIP—806 MX: 2 pieces: SHODEX
  • the molecular weight is 8 2 Elution of 70,000, 101,000, 34,000, 100,000, and 0.2000 known molecular weight PMMA (methyl polymethacrylate) standards by RI detection
  • a calibration curve obtained from the time was prepared in advance, and the weight average molecular weight was calculated from the elution time.
  • the melting point was determined using a DSC (differential scanning calorimeter) under the following conditions.
  • the glass transition temperature in the present invention is defined as the starting temperature of the second-order transition of the temperature change curve of the amount of heat in the transition region from the glass state to the rubber state using a differential scanning calorimeter (DSC).
  • DSC differential scanning calorimeter
  • the prepolymer was sandwiched between aluminum sheets, melt-pressed at a temperature of the obtained melting point plus 10 ° C, and rapidly cooled with ice water to obtain a sheet-like amorphous polymer. Cut out this, pack about 10 mg into aluminum, and use DSC 25 manufactured by METTLER ONE, Inc. under nitrogen atmosphere of 50 mL / min. The temperature rises to 260 ° C at a rate of one minute, and the transition temperature of the temperature change curve of the amount of heat in the secondary transition region corresponding to the transition region from the glassy state to the rubbery state is the glass transition temperature. And
  • Low-molecular-weight compounds in the hydroxycarboxylic acid alkyl ester which are impurities that stop the polymerization, were quantitatively analyzed by gas chromatography.
  • the content of impurities in the methyl glycolate used in this example was 0.01 wt.% Or less, which was below the detection limit of gas chromatography.
  • glycolic acid a special-grade reagent manufactured by Kanto Chemical Industry Co., Ltd. was used.
  • the crystallinity of the prepolymer was determined from the enthalpy of fusion according to the following method using DSC.
  • the prepolymer obtained in this way has a crystallinity of 52%, a weight average molecular weight of 620,000, a melting point of 207 ° C, and a glass transition temperature of 38 ° C. Met.
  • the prepolymer obtained in this way has a crystallinity of 49%, a weight average molecular weight of 10,000,000, a melting point of 1950 ° C, and a glass transition temperature of 37. there were.
  • the prepolymer obtained in this manner had a crystallinity of 56%, a weight average molecular weight of 16,000, a melting point of 21.5 ° C, and a glass transition temperature of 37 ° C. Was.
  • Solid phase polymerization was carried out in the same manner as in Example 4, except that the prepolymer obtained in Synthesis Example 4 was used.
  • the polymer obtained after the reaction had a weight average molecular weight of 86,000 and a melting point of 214 ° C and 2229 ° C.
  • a solution of a mixture of phenol / 2,4,5—trichlorophenol [0.5 / 10 (weight ratio)] having a concentration of 0.5 g Zdl was prepared.
  • en / C was determined at 0.0 ⁇ 0.1 ° C. using an Ubbelohde viscometer, it was 0.26.
  • Table 1 shows the results of Examples 1 to 4 and Comparative Examples 1 and 2.
  • the capacitor was removed from the autoclave and heated gradually to 150 ° C to perform dehydration (dehydration and dealcoholation).
  • dehydration and dealcoholation When the distillation of water almost disappeared, the temperature was raised to 180 ° C., and the removal of the condensed water was continued under a reduced pressure of 5 kPa (50 mbar) for 2 hours. Further, the temperature was raised to 200 ° C., and the removal of the condensed water was continued under a reduced pressure of 0.1 lkPa (lmbar) for 2 hours. After cooling to room temperature, 3885 g of a white solid was removed.
  • the obtained prepolymer had a crystallinity of 52%, a weight average molecular weight of 220,000, a melting point of 205 ° C, and a glass transition temperature of 37 ° C.
  • the capacitor was removed from the autoclave and heated gradually to 150 ° C to perform a dehydration operation.
  • the temperature was raised to 180 ° C. when almost no water distilled, and the removal of condensed water was continued under reduced pressure of 5 kPa (50 mbar) for 2 hours. Further, the temperature was raised to 200 ° C., and the removal of the condensed water was continued under a reduced pressure of 0.1 kPa (lmbar) for 2 hours. After cooling to room temperature, 393 g of a white solid were removed.
  • the obtained prepolymer had a crystallinity of 49%, a weight average molecular weight of 188,000, a melting point of 204 ° C and a glass transition temperature of 37 ° C.
  • Solid state polymerization After pulverizing the prepolymer obtained in the above Synthesis Example 6 in a mortar, 50 g of a fluid paraffin and 20 g of the prepolymer were charged into an eggplant-shaped flask and stirred. While heating at 190 ° C for 1 hour and at 210 ° C for 4 hours, solid-state polymerization was performed. After the polymer was filtered off, it was washed with hexane and dried. The polymer formed after drying was almost white, had a weight average molecular weight of 163,000 and a melting point of 226 ° C.
  • the capacitor was removed from the autoclave and heated gradually to 150 ° C to perform a dehydration operation.
  • add 0.05 g of stannic chloride raise the temperature to 180 ° C, and reduce the pressure to 5 kPa (50 mbar) for 2 hours.
  • the removal of the condensed water was continued. Further, the temperature was raised to 200, and the removal of condensed water was continued under a reduced pressure of 0.1 lkPa (lmbar) for 1 hour.
  • 390 g of a white solid was removed.
  • the obtained prepolymer had a crystallinity of 56%, a weight average molecular weight of 48,000, a melting point of 206 ° C, and a glass transition temperature of 38 ° C.
  • the capacitor was removed from the above autoclave, heated gradually to 150 ° C, and dewatered.
  • the temperature was raised to 180 ° C. when almost no water was distilled off, and the removal of condensed water was continued under reduced pressure of 5 kPa (50 mbar) for 2 hours. Further, the temperature was raised to 215 ° C, and the removal of the condensed water was continued under a reduced pressure of 0.1 kPa (lmbar) for 2 hours.
  • 390 g of a white solid was removed.
  • the resulting prepolymer had a crystallinity of 50%, a weight-average molecular weight of 200000, a melting point of 211 ° C, and a glass transition temperature of 38 ° C.
  • glycol was 15 g (75% yield).
  • the polymer remaining in the flask due to solid-state polymerization remained in a solid state, and could be easily removed by tilting the flask. After removing the polymer, no deposits were found on the flask, and cleaning of the flask was easy.
  • the extracted polymer had a weight average molecular weight of 492,000 and a melting point of 238 ° C.
  • the prepolymer obtained in this manner had a crystallinity of 53%, a weight average molecular weight of 650,000, a melting point of 220 ° C, and a glass transition temperature of 38 ° C. there were.
  • Solid phase polymerization and solid phase depolymerization were carried out in the same manner as in Example 10 except that the prepolymer (melting point: 220 ° C.) obtained in Synthesis Example 11 above was used.
  • the obtained glycol was 14 g (70% yield).
  • the polymer remaining in the flask due to solid-state polymerization remained in a solid state and could be easily removed by tilting the flask. After removing the polymer, no deposits were found on the flask, and the cleaning of the flask was easy.
  • the removed polymer had a weight average molecular weight of 31,000 and a melting point of 2336 ° C.
  • glycol was 16 g (80% yield). However, in the flask, a black-brown mass in which the prepolymer became heavy under high temperature conditions was firmly attached.
  • the present invention there is provided a method for economically producing a high molecular weight polyhydroxycarboxylic acid having excellent melt moldability and mechanical properties.
  • the polyhydroxycarboxylic acid obtained by the production method of the present invention has a high molecular weight, has biodegradability, and can be obtained as a high-quality polymer. Therefore, they are useful in a wide range of fields, for example, as substitutes for medical materials and general-purpose resins.
  • high-purity glycolide useful as a raw material such as polyglycolide (polyglycolic acid) can be efficiently obtained.

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  • Chemical & Material Sciences (AREA)
  • Health & Medical Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Medicinal Chemistry (AREA)
  • Polymers & Plastics (AREA)
  • Organic Chemistry (AREA)
  • Polyesters Or Polycarbonates (AREA)

Abstract

L'invention concerne un procédé de production d'un acide polyhydroxy carboxylique, le procédé consistant à polymériser par condensation soit un alkyl hydroxy carboxylate, soit un hydrolysat contenant un acide hydroxy carboxylique et obtenu par hydrolyse d'au moins une partie de l'alkyl hydroxy carboxylate pour produire un prépolymère puis polymérisation du prépolymère obtenu par polymérisation à l'état solide; l'invention concerne également un procédé de production d'un glycolide, le procédé consistant à soumettre le prépolymère d'acide glycolique ou l'acide polyglycolique obtenu à une dépolymérisation à l'état solide.
PCT/JP1998/004618 1997-10-13 1998-10-13 Procedes de production d'acide polyhydroxy carboxylique et de glycolide WO1999019378A1 (fr)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
JP9/296333 1997-10-13
JP29633397A JPH11116666A (ja) 1997-10-13 1997-10-13 ポリグリコール酸の製造方法
JP31123497A JPH11130847A (ja) 1997-10-28 1997-10-28 ポリヒドロキシカルボン酸の製造方法
JP9/311234 1997-10-28

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Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2001030883A1 (fr) * 1999-10-27 2001-05-03 Mitsui Chemicals, Inc Procede de production d'un polyester aliphatique ayant une excellente stabilite
US7005536B2 (en) 2002-07-12 2006-02-28 Nippon Shokubai Co., Ltd. Method for producing diol derivatives
CN103265688A (zh) * 2013-06-13 2013-08-28 武汉大学 一种羟基乙酸聚合物的制备方法
CN107064318A (zh) * 2016-07-22 2017-08-18 中南大学 一种乙交酯标准物质及其制备方法和检测方法
WO2020087223A1 (fr) * 2018-10-29 2020-05-07 Pujing Chemical Industry Co., Ltd Nouvel acide polyglycolique et son procédé de préparation par polycondensation
WO2020087217A1 (fr) * 2018-10-29 2020-05-07 Pujing Chemical Industry Co., Ltd Production de glycolide à partir de polyglycolate de méthyle
CN111548339A (zh) * 2020-04-10 2020-08-18 深圳光华伟业股份有限公司 乙醇酸酯制备乙交酯的工艺方法
CN111763308A (zh) * 2020-06-11 2020-10-13 江苏金聚合金材料有限公司 一种酸性催化剂催化乙醇酸甲酯聚合生成聚乙醇酸的方法
CN113929885A (zh) * 2021-10-19 2022-01-14 江苏金之虹新材料有限公司 一种复合催化剂及其在制备乙交酯中的应用
CN114437020A (zh) * 2022-02-23 2022-05-06 中国科学院长春应用化学研究所 一种乙交酯的制备方法

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JPH06172341A (ja) * 1992-09-16 1994-06-21 Basf Ag グリコリド又はラクチドの製法
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JPH06329774A (ja) * 1993-05-24 1994-11-29 Nippon Shokubai Co Ltd ポリ（ヒドロキシアルカノエート）の製造方法
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JPS5996123A (ja) * 1982-11-25 1984-06-02 Showa Highpolymer Co Ltd 高分子量ポリラクタイドの製造方法
JPS61236820A (ja) * 1985-04-15 1986-10-22 Bio Materiaru Yunibaasu:Kk 低分子量グリコ−ル酸−乳酸共重合体
JPH02268179A (ja) * 1989-03-22 1990-11-01 E I Du Pont De Nemours & Co 環状エステルの製造方法
JPH04227626A (ja) * 1990-03-21 1992-08-17 Sam Yang Co Ltd グリコリドの製造方法
US5247058A (en) * 1992-01-24 1993-09-21 Cargill, Incorporated Continuous process for manufacture of lactide polymers with controlled optical purity
US5258488A (en) * 1992-01-24 1993-11-02 Cargill, Incorporated Continuous process for manufacture of lactide polymers with controlled optical purity
US5357035A (en) * 1992-01-24 1994-10-18 Cargill, Incorporated Continuous process for manufacture of lactide polymers with purification by distillation
JPH06172341A (ja) * 1992-09-16 1994-06-21 Basf Ag グリコリド又はラクチドの製法
JPH06329774A (ja) * 1993-05-24 1994-11-29 Nippon Shokubai Co Ltd ポリ（ヒドロキシアルカノエート）の製造方法
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Cited By (15)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2001030883A1 (fr) * 1999-10-27 2001-05-03 Mitsui Chemicals, Inc Procede de production d'un polyester aliphatique ayant une excellente stabilite
US6528617B1 (en) 1999-10-27 2003-03-04 Mitsui Chemicals, Inc. Process for producing aliphatic polyester excellent in stability
US7005536B2 (en) 2002-07-12 2006-02-28 Nippon Shokubai Co., Ltd. Method for producing diol derivatives
CN103265688A (zh) * 2013-06-13 2013-08-28 武汉大学 一种羟基乙酸聚合物的制备方法
CN107064318A (zh) * 2016-07-22 2017-08-18 中南大学 一种乙交酯标准物质及其制备方法和检测方法
CN107064318B (zh) * 2016-07-22 2019-12-06 中南大学 一种乙交酯标准物质及其制备方法和检测方法
WO2020087223A1 (fr) * 2018-10-29 2020-05-07 Pujing Chemical Industry Co., Ltd Nouvel acide polyglycolique et son procédé de préparation par polycondensation
WO2020087217A1 (fr) * 2018-10-29 2020-05-07 Pujing Chemical Industry Co., Ltd Production de glycolide à partir de polyglycolate de méthyle
CN111548339A (zh) * 2020-04-10 2020-08-18 深圳光华伟业股份有限公司 乙醇酸酯制备乙交酯的工艺方法
CN111763308A (zh) * 2020-06-11 2020-10-13 江苏金聚合金材料有限公司 一种酸性催化剂催化乙醇酸甲酯聚合生成聚乙醇酸的方法
CN111763308B (zh) * 2020-06-11 2022-05-13 江苏金聚合金材料有限公司 一种酸性催化剂催化乙醇酸甲酯聚合生成聚乙醇酸的方法
CN113929885A (zh) * 2021-10-19 2022-01-14 江苏金之虹新材料有限公司 一种复合催化剂及其在制备乙交酯中的应用
CN113929885B (zh) * 2021-10-19 2023-01-20 江苏金之虹新材料有限公司 一种复合催化剂及其在制备乙交酯中的应用
CN114437020A (zh) * 2022-02-23 2022-05-06 中国科学院长春应用化学研究所 一种乙交酯的制备方法
CN114437020B (zh) * 2022-02-23 2023-03-24 中国科学院长春应用化学研究所 一种乙交酯的制备方法

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