WO2010087069A1 - Method for producing aliphatic polyester - Google Patents

Method for producing aliphatic polyester Download PDF

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Publication number
WO2010087069A1
WO2010087069A1 PCT/JP2009/070412 JP2009070412W WO2010087069A1 WO 2010087069 A1 WO2010087069 A1 WO 2010087069A1 JP 2009070412 W JP2009070412 W JP 2009070412W WO 2010087069 A1 WO2010087069 A1 WO 2010087069A1
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acid
aliphatic polyester
pka
aliphatic
hydroxy
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PCT/JP2009/070412
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French (fr)
Japanese (ja)
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鷹岡寛治
本間信孝
小原仁実
竹中真
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トヨタ自動車株式会社
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Publication of WO2010087069A1 publication Critical patent/WO2010087069A1/en

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    • 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
    • C08G63/82—Preparation processes characterised by the catalyst used
    • C08G63/823—Preparation processes characterised by the catalyst used for the preparation of polylactones or polylactides
    • 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
    • C08G63/82—Preparation processes characterised by the catalyst used
    • C08G63/87—Non-metals or inter-compounds thereof

Definitions

  • the present invention relates to a method for producing a biodegradable aliphatic polyester such as polylactic acid.
  • Aliphatic polyester is known as a biodegradable plastic having a biodegradable function that is decomposed by microorganisms, and is applied to various products as a low-load material for the environment.
  • polylactic acid is attracting attention as a bio-based polymer using biomass as a raw material from the viewpoint of depleting petroleum and suppressing an increase in carbon dioxide in the atmosphere.
  • a method for producing an aliphatic polyester for example, a method of ring-opening polymerization of a cyclic dimer, a method of directly dehydrating polycondensation of monomers and oligomers, and the like are known.
  • Patent Document 1 discloses a method in which an acid catalyst and a tin-based catalyst having a pKa of 3.66 or less are present in a method of directly dehydrating polycondensation of monomers and oligomers constituting an aliphatic polyester. According to the method disclosed in Patent Document 1, it is possible to produce an aliphatic polyester that prevents a decrease in polymerization rate and reduces coloring.
  • Patent Document 2 discloses a method for producing a higher molecular aliphatic polyester by solid-phase polymerization of an aliphatic polyester prepolymer crystal having a predetermined molecular weight in the presence of a catalyst.
  • a volatile acid such as an organic sulfonic acid compound is used as a catalyst.
  • the method of producing an aliphatic polyester by ring-opening polymerization of a cyclic dimer is faster than the method of directly polycondensing monomers and oligomers disclosed in Patent Documents 1 and 2 described above. It is characterized in that it can be produced at high speed and with higher molecular weight.
  • an aliphatic polyester having a molecular weight equivalent to the method of ring-opening polymerization of a cyclic dimer is produced. Had the problem of long reaction times.
  • the present invention makes it possible to shorten the reaction time in a method for producing an aliphatic polyester by directly polycondensing monomers and oligomers, in other words, a high molecular weight fat in a short time.
  • An object of the present invention is to provide a method capable of producing a group polyester.
  • the reaction rate can be improved by using an acid catalyst having a pKa within a predetermined range when directly polycondensing monomers and oligomers.
  • an acid catalyst having a pKa within a predetermined range when directly polycondensing monomers and oligomers.
  • the method for producing an aliphatic polyester according to the present invention is characterized in that a monomer or an oligomer constituting the aliphatic polyester is polymerized under an acid catalyst having a pKa in the range of ⁇ 2.0 to ⁇ 1.7. Is.
  • an acid catalyst having a pKa in the range of 1.85 to -1.7 it is preferable to use an acid catalyst having a pKa in the range of 1.85 to -1.7.
  • an acid catalyst having a solubility parameter value in the range of 21 to 25.
  • the acid catalyst is not particularly limited, but at least one compound selected from the group consisting of dodecylbenzenesulfonic acid, methicylenesulfonic acid and 2-naphthalenesulfonic acid can be used.
  • 2-naphthalenesulfonic acid is preferably used as the acid catalyst.
  • 2-naphthalenesulfonic acid is used as the acid catalyst, coloring of the aliphatic polyester can be suppressed.
  • examples of the monomer include aliphatic hydroxycarboxylic acid or aliphatic diol and aliphatic dicarboxylic acid.
  • the reaction rate when synthesizing an aliphatic polyester by directly polycondensing monomers and oligomers can be improved, and a high-molecular weight aliphatic polyester can be produced in a shorter time. can do. Therefore, according to the method for producing an aliphatic polyester according to the present invention, the productivity of the aliphatic polyester can be improved.
  • FIG. 4 is a characteristic diagram showing the relationship between the pKa and the weight average molecular weight of a volatile acid catalyst.
  • 2 is a photograph of polylactic acid (A) synthesized using 2-naphthalenesulfonic acid as a volatile acid catalyst and polylactic acid (B) synthesized using mesitylenesulfonic acid.
  • the monomer or oligomer constituting the aliphatic polyester has a pKa in the range of -2.0 to -1.7, preferably in the range of -1.9 to -1.7, more preferably- This is a method of direct polymerization in the presence of an acid catalyst within the range of 1.85 to -1.7.
  • pKa can be calculated from its molecular structure, for example, using software: Calculator Plugins (ChemAxons).
  • examples of the volatile acid catalyst having a pKa in the range of -2.0 to -1.7 include monoalkylbenzene sulfonic acid, dialkylbenzene sulfonic acid and trialkylbenzene sulfonic acid.
  • monoalkylbenzenesulfonic acid the alkyl group may be located at any of the para, ortho and meta positions.
  • examples of the volatile acid catalyst include carboxylic acid compounds, phosphoric acid compounds, inorganic acids such as aluminum silicate and zeolite.
  • examples of these volatile acid catalysts those in the range of ⁇ 2.0 to ⁇ 1.7 can be specified and used by calculating the pKa as described above.
  • the polymerization reaction rate decreases, and for example, a high molecular weight aliphatic polyester having a weight average molecular weight of 150,000 is synthesized. In order to do so, a long reaction time is required.
  • a volatile acid catalyst having a pKa in the range of -2.0 to -1.7
  • the polymerization reaction rate can be improved most.
  • a high molecular weight aliphatic polyester can be produced in a short time.
  • mesitylenesulfonic acid when mesitylenesulfonic acid is used, the catalyst remaining rate in the produced aliphatic polyester can be greatly reduced.
  • the catalyst residual ratio is high, the produced aliphatic polyester may deteriorate over time. Therefore, when mesitylenesulfonic acid is used, a high-quality aliphatic polyester with little deterioration with time can be produced.
  • the volatile acid catalyst having a pKa in the range of ⁇ 2.0 to ⁇ 1.7 it is preferable to use a volatile acid having a solubility parameter approximate to the solubility parameter of the aliphatic polyester to be produced.
  • the approximation means a range within ⁇ 20%, preferably within ⁇ 15%, more preferably within ⁇ 10% based on the solubility parameter of the aliphatic polyester.
  • polylactic acid when polylactic acid is produced as an aliphatic polyester, since the solubility parameter of polylactic acid is 23.3, for example, methicylene sulfonic acid having a solubility parameter close to 23.3 is used as a volatile acid catalyst. It is preferable.
  • the calculation method of the solubility parameter is not particularly limited as long as the same calculation method may be applied to both the aliphatic polyester and the volatile acid.
  • the solubility parameter can be calculated by applying the Fedor method (Fedor's Group Contribution Method). According to this Fedor method, the solubility parameter (d) can be calculated by the following equation.
  • the unit of the solubility parameter [d] is [(J / cm 3 ) 1/2 ].
  • V is the molar volume of the number of structural repeats calculated by the atomic group contribution method.
  • E coh is the molar bond energy by Fodor [J / mol]
  • E coh, i indicates the contribution of the i-th atomic group to E coh .
  • the solubility parameter of polylactic acid is calculated as follows.
  • E coh and V of CH 3 of the atomic group constituting polylactic acid are 4710 and 33.5, respectively
  • E coh and V of CH are 3430 and -1.0, respectively
  • E coh and V of -O- are respectively ECOh and V of -CO 2- are 18000 and 18.0, respectively.
  • the produced aliphatic When a volatile acid having a solubility parameter approximate to the solubility parameter of the aliphatic polyester to be produced is used as the volatile acid catalyst having a pKa in the range of -2.0 to -1.7, the produced aliphatic
  • the affinity between the polyester and the volatile acid catalyst is excellent, and as a result, the amount of the volatile acid catalyst used can be reduced. Therefore, in this case, the catalyst remaining rate in the produced aliphatic polyester can be reduced, and the production cost can be reduced.
  • the monomer of the aliphatic polyester is not limited in any way, such as aliphatic polyhydric alcohols such as aliphatic hydroxycarboxylic acids and aliphatic diols, and aliphatic dicarboxylic acids. Combinations of aliphatic polyvalent carboxylic acids can be used.
  • an aliphatic polyhydric alcohol such as an aliphatic diol or an aliphatic polyhydric alcohol and an aliphatic having an aliphatic hydroxycarboxylic acid as a structural unit instead of the aliphatic polyester monomer.
  • An oligomer made of an aliphatic polycarboxylic acid such as dicarboxylic acid may be used as a raw material.
  • aliphatic hydroxycarboxylic acids include, but are not limited to, 2-hydroxyethanoic acid, 2-hydroxypropanoic acid (ie, lactic acid), 2-hydroxybutanoic acid, 2-hydroxypentanoic acid, 2-hydroxyhexanoic acid, 2-hydroxyheptanoic acid, 2-hydroxyoctanoic acid, 2-hydroxy-2-methylpropanoic acid, 2-hydroxy-2-methylbutanoic acid, 2-hydroxy-2-ethylbutanoic 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-buty Hexanoic acid, 2-hydroxy-2-pentylhexanoic acid, 2-hydroxy-2-methylmethylprop
  • a cyclic body thing and an oligomer can also be used from aliphatic hydroxycarboxylic acid.
  • aliphatic hydroxycarboxylic acid when using aliphatic hydroxycarboxylic acid as a raw material, only 1 type may be used, but 2 or more types of mixtures may be used.
  • some of the above-mentioned aliphatic hydroxycarboxylic acids may have optical isomers, but the aliphatic hydroxycarboxylic acid used as a raw material may be in any form of D-form, L-form, and D / L-form. May be.
  • the aliphatic diol is not particularly limited, and examples thereof include ethylene glycol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 3-methyl- Examples thereof include 1,5-pentanediol, 1,6-hexanediol, 1,8-octanediol, 1,10-decanediol, 1,12-dodecanediol, propylene glycol, and neopentyl glycol.
  • As the aliphatic diol only one kind may be used, or two or more kinds may be mixed and used.
  • the aliphatic dicarboxylic acid is not particularly limited, but for example, succinic acid, oxalic acid, malonic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid. , Fumaric acid and dimer acid.
  • succinic acid oxalic acid
  • malonic acid glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid.
  • Fumaric acid and dimer acid Fumaric acid and dimer acid.
  • the aliphatic dicarboxylic acid only one kind may be used, or two or more kinds may be mixed and used.
  • the solid phase polymerization method means a polymerization method in which an oligomer or polymer (aliphatic polyester) obtained by a dehydration polycondensation reaction of these monomers is further subjected to a dehydration polycondensation reaction while maintaining a solid state. Maintaining a solid state means maintaining a temperature lower than the melting point of the oligomer or polymer.
  • a volatile acid catalyst having a pKa in the range of -2.0 to -1.7 is dehydration using monomers such as aliphatic hydroxycarboxylic acid, aliphatic diol and aliphatic dicarboxylic acid. It can be used at any stage of synthesizing oligomers and polymers by polycondensation reaction, and increasing the molecular weight by further dehydrating polycondensation reaction while maintaining the solid state of these oligomers and polymers. It may be used at this stage.
  • the volatile acid catalyst having a pKa in the range of ⁇ 2.0 to ⁇ 1.7 is a dehydration polymerization using monomers such as aliphatic hydroxycarboxylic acid, aliphatic diol, and aliphatic dicarboxylic acid. It is preferably used at the stage of synthesizing an oligomer or polymer by a condensation reaction.
  • the reaction temperature is preferably 100 ° C. to 200 ° C., preferably 110 ° C. to 180 ° C. More preferably, the temperature is 130 ° C. to 160 ° C.
  • the stage of synthesizing an oligomer or polymer by a dehydration polycondensation reaction using monomers such as aliphatic hydroxycarboxylic acid, aliphatic diol and aliphatic dicarboxylic acid until the weight average molecular weight of the oligomer or polymer reaches 2000 to 10,000.
  • the reaction is preferably allowed to proceed, more preferably the reaction is allowed to reach 3000 to 8000, still more preferably the reaction is allowed to proceed to 4000 to 6000.
  • the obtained oligomer or polymer is preferably subjected to crystallization treatment, and the softening temperature and melting start temperature are preferably increased as much as possible. This crystallization treatment varies depending on the oligomer or polymer obtained, but can be carried out, for example, by heating at 80 ° C. to 110 ° C. for 1 hour or longer.
  • the polymerization reaction can proceed in a short time when dehydration polycondensation is performed in the solid phase state later.
  • vacuum heating degree of vacuum: 1 to 10 KPa, heating temperature: 100 to 120 ° C.
  • washing with water, acetone, alcohol or the like is performed. can do.
  • the oligomer or polymer is, for example, made into powder, granules, flakes, spheres, hemispheres, pellets, and a lump. It is preferable.
  • the reaction temperature is preferably set to a high temperature as long as the oligomer or polymer does not melt.
  • the reaction temperature is preferably 100 to 140 ° C. below the melting temperature, more preferably 100 to 120 ° C.
  • the reaction temperature is preferably 140 to 180 ° C. below the melting temperature, more preferably 140 to 160 ° C. preferable.
  • the remaining volatile acid catalyst is preferably removed by a known method, if necessary.
  • a method of removing the volatile acid catalyst by contacting the obtained solid state aliphatic polyester with a solvent that elutes only the volatile acid catalyst, after dissolving the aliphatic polyester in a good solvent, the solvent And a method of extracting the volatile acid catalyst by contacting with a solvent that dissolves the volatile acid catalyst, or after dissolving the obtained aliphatic polyester in a good solvent, zeolite, molecular sieve, etc.
  • a method of removing the volatile acid catalyst by adsorbing the volatile acid catalyst to the adsorbent a known method, if necessary.
  • Aliphatic polyester produced as described above can be used alone as a raw material for various products, but in order to further improve impact resistance, rubber other than aliphatic polyester resin, elastomer, soft resin component, etc. May be used as a raw material for various products as a resin composition to which is further added.
  • Specific types of such components are not particularly limited, but may be components having good compatibility with aliphatic polyesters, or components having improved compatibility by chemical modification or addition of a compatibilizing agent. preferable.
  • the high temperature elastic modulus and the deflection temperature under load may be lowered, so that it is 20 parts by weight or less with respect to 100 parts by weight of the aliphatic polyester. It is preferably 10 parts by weight or less, more preferably 5 parts by weight or less.
  • a heat stabilizer such as an antioxidant is further added.
  • the specific kind of the heat stabilizer is not particularly limited, and the content thereof is preferably 2 parts by weight or less with respect to 100 parts by weight of the aliphatic polyester, and is 1 part by weight or less. More preferably, the amount is 0.1 parts by weight or less.
  • a lubricant e.g., a lubricant, a light stabilizer, an ultraviolet absorber, an antistatic agent, a flame retardant, a release agent, a pigment, a colorant, a dye, an antibacterial agent, as long as the characteristics are not impaired.
  • An additive such as an agent may be further added.
  • the content of such an additive is preferably 20 parts by weight or less with respect to 100 parts by weight of the aliphatic polyether in the resin composition.
  • the specific molding method and various molding conditions are appropriately selected according to the aliphatic polyester to be used, but generally the following molding methods are preferably employed. That is, (i) a step of bringing a resin composition containing an aliphatic polyester into a molten state, and (ii) a step of crystallizing the molten resin composition by holding it for a predetermined time in a state where the molten resin composition has been shifted to a temperature below its melting point Is preferred. At that time, the temperature at which the resin composition is melted in the step (i) is preferably 170 to 230 ° C.
  • the holding temperature in the step (ii) is preferably 30 to 160 ° C., and the holding time is preferably 5 to 1800 seconds.
  • the molding method is not limited to injection molding, and any method such as extrusion molding, blow molding, inflation molding, profile extrusion molding, injection blow molding, vacuum pressure molding, spinning, etc. It may be. Moreover, the shape, thickness, etc.
  • the molded product of the present invention are not particularly limited, and any of injection molded products, extrusion molded products, compression molded products, blow molded products, sheets, films, yarns, fabrics, and the like may be used. Further, after the resin composition is melt-molded as described above, the obtained molded body may be further subjected to heat treatment.
  • the heat treatment temperature is preferably 80 to 150 ° C.
  • the holding time is preferably 5 to 2000 seconds.
  • L-lactic acid Hipure 90; manufactured by Pulac Co., Ltd.
  • 2-naphthalenesulfonic acid manufactured by Tokyo Chemical Industry Co., Ltd.
  • Example 4 polylactic acid (4) was obtained in the same manner as in Example 3, except that 12.5 mg (0.25 wt%) of mesitylenesulfonic acid was used as a catalyst.
  • TSK-GEL H type (eluent: chloroform) was used.
  • Mw weight average molecular weight
  • Mn number average molecular weight
  • Tm melting point
  • Tm DSC Q100 manufactured by TI Instruments. In measuring the melting point (Tm), a method in which 10 mg of a sample was heated from room temperature to 250 ° C. at a temperature rising rate of 10 ° C./min was applied.
  • optical purity was determined by adding 5 ml of 5M NaOH and 2.5 ml of isopropanol to 1 mg of sample, hydrolyzing while stirring at 40 ° C, diluting the neutralized solution neutralized with 1M H 2 SO 4 , and using HPLC. It calculated from the following formula from the detected peak areas of L-lactic acid and D-lactic acid.
  • Optical purity 100 ⁇ [L] / ([L] + [D]) (In the formula, [L] is the weight ratio (%) of L-lactic acid, and [D] is the weight ratio (%) of D-lactic acid.)
  • LC Module I manufactured by Waters was used, and SUMICHIRAL OA-5000 manufactured by Sumika Chemical Analysis Co., Ltd. was used for the column.
  • FIG. 1 shows the results of measuring the weight average molecular weights during the reaction times of 5 h, 20 h, and 50 h (at the end of the reaction) in the production process of polylactic acid shown in Examples 1 to 4 and Comparative Examples 1 and 2 above. It was. Did. Furthermore, from the above results, the relationship between the pKa of the volatile acid catalyst used in the reaction and the weight average molecular weight of the obtained polylactic acid is shown in FIG.
  • the catalyst residual ratio was calculated as follows. That is, the gas generated when the sample was heated and incinerated at 900 ° C. was absorbed in a fixed volume of absorption liquid, and the gas was quantified by ion chromatography using the absorption liquid. And the catalyst residual rate was computed by converting the analytical value of the sulfur concentration quantified by the ion chromatography into various sulfonic acid type compounds. Further, the presence or absence of coloring of the polylactic acids (1) to (3) was determined visually. Table 2 shows the results of examining the remaining catalyst ratio and the degree of coloring calculated as described above. Moreover, the coloring degree of polylactic acid (1) and (3) was shown in FIG. In FIG. 3, (A) is polylactic acid (1) produced using 2-naphthalenesulfonic acid as a volatile acid catalyst, and (B) is produced using mesitylenesulfonic acid as a volatile acid catalyst. Polylactic acid (3).
  • dodecylbenzene sulfonic acid is a very inexpensive compound whose metal salt is very widely used in synthetic detergents and the like. Therefore, when dodecylbenzenesulfonic acid is used as the volatile acid catalyst, the production cost of the aliphatic polyester can be kept low.

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Abstract

Disclosed is a method for producing an aliphatic polyester by directly polycondensing a monomer or an oligomer whereby the reaction time can be shortened.  In other words, disclosed is a method for producing an aliphatic polyester, which has a high molecular weight, in a short period of time. By using a volatile acid catalyst, which has a pKa within a specific range, in directly polycondensing a monomer or an oligomer, the reaction speed can be increased and an aliphatic polyester having a higher molecular weight can be synthesized.

Description

脂肪族ポリエステルの製造方法Method for producing aliphatic polyester
　本発明は、例えばポリ乳酸などの生分解性を有する脂肪族ポリエステルの製造方法に関する。 The present invention relates to a method for producing a biodegradable aliphatic polyester such as polylactic acid.
　脂肪族ポリエステルは、微生物により分解される生分解性機能を備えた生分解性プラスチックとして知られており、環境に対する低負荷な素材として種々の製品に応用されている。中でもポリ乳酸は、バイオマスを原料としたバイオベースポリマーとして、石油の枯渇や大気中の炭酸ガス増加抑制の観点から注目されている。脂肪族ポリエステルの製造方法としては、例えば、環状二量体を開環重合する方法、モノマーやオリゴマーを直接脱水重縮合する方法などが知られている。 Aliphatic polyester is known as a biodegradable plastic having a biodegradable function that is decomposed by microorganisms, and is applied to various products as a low-load material for the environment. Among them, polylactic acid is attracting attention as a bio-based polymer using biomass as a raw material from the viewpoint of depleting petroleum and suppressing an increase in carbon dioxide in the atmosphere. As a method for producing an aliphatic polyester, for example, a method of ring-opening polymerization of a cyclic dimer, a method of directly dehydrating polycondensation of monomers and oligomers, and the like are known.
　特に、特許文献１には、脂肪族ポリエステルを構成するモノマーやオリゴマーを直接脱水重縮合する方法において、pKaが3.66以下の酸触媒及び錫系触媒の存在させる方法を開示している。特許文献１に開示された方法によれば、重合速度の低下を防止し、且つ着色を低減した脂肪族ポリエステルを製造できる。 In particular, Patent Document 1 discloses a method in which an acid catalyst and a tin-based catalyst having a pKa of 3.66 or less are present in a method of directly dehydrating polycondensation of monomers and oligomers constituting an aliphatic polyester. According to the method disclosed in Patent Document 1, it is possible to produce an aliphatic polyester that prevents a decrease in polymerization rate and reduces coloring.
　また、特許文献２には、所定の分子量の脂肪族ポリエステルプレポリマーの結晶を、触媒存在下で固相重合することでより高分子の脂肪族ポリエステルを製造する方法が開示されている。特許文献２に開示された方法では、触媒として揮発性酸、例えば有機スルホン酸系化合物を使用している。 Patent Document 2 discloses a method for producing a higher molecular aliphatic polyester by solid-phase polymerization of an aliphatic polyester prepolymer crystal having a predetermined molecular weight in the presence of a catalyst. In the method disclosed in Patent Document 2, a volatile acid such as an organic sulfonic acid compound is used as a catalyst.
　一方、環状二量体を開環重合することで脂肪族ポリエステルを製造する方法は、上述した特許文献１及び２に開示されている、モノマーやオリゴマーを直接重縮合する方法と比較して反応速度が速く、且つより高分子量の脂肪族ポリエステルを製造できるといった特徴がある。言い換えれば、上述した特許文献１及び２に開示されている、モノマーやオリゴマーを直接重縮合する方法では、環状二量体を開環重合する方法と同等の分子量を有する脂肪族ポリエステルを製造するには反応時間が長くなるといった問題があった。 On the other hand, the method of producing an aliphatic polyester by ring-opening polymerization of a cyclic dimer is faster than the method of directly polycondensing monomers and oligomers disclosed in Patent Documents 1 and 2 described above. It is characterized in that it can be produced at high speed and with higher molecular weight. In other words, in the method of directly polycondensing monomers and oligomers disclosed in Patent Documents 1 and 2 described above, an aliphatic polyester having a molecular weight equivalent to the method of ring-opening polymerization of a cyclic dimer is produced. Had the problem of long reaction times.
特開２００１－８９５５８号公報JP 2001-89558 A 特開２０００－３０２８５２号公報JP 2000-302852 A
　そこで、本発明は、上述したような実情に鑑み、モノマーやオリゴマーを直接重縮合して脂肪族ポリエステルを製造する方法において、反応時間短縮を可能とする、換言すれば短時間で高分子量の脂肪族ポリエステルを製造できる方法を提供することを目的とする。 Therefore, in view of the above situation, the present invention makes it possible to shorten the reaction time in a method for producing an aliphatic polyester by directly polycondensing monomers and oligomers, in other words, a high molecular weight fat in a short time. An object of the present invention is to provide a method capable of producing a group polyester.
　上述した目的を達成するため、本発明者らが鋭意検討した結果、モノマーやオリゴマーを直接重縮合する際に、pKaが所定の範囲内にある酸触媒を使用することで反応速度を向上させることができ、より高分子量の脂肪族ポリエステルを合成できることを見いだし、本発明を完成するに至った。 As a result of intensive studies by the present inventors in order to achieve the above-mentioned object, the reaction rate can be improved by using an acid catalyst having a pKa within a predetermined range when directly polycondensing monomers and oligomers. Thus, it was found that a higher molecular weight aliphatic polyester could be synthesized, and the present invention was completed.
　すなわち、本発明に係る脂肪族ポリエステルの製造方法は、当該脂肪族ポリエステルを構成するモノマー若しくはオリゴマーを、pKaが-2.0～-1.7の範囲内である酸触媒下にて重合することを特徴とするものである。 That is, the method for producing an aliphatic polyester according to the present invention is characterized in that a monomer or an oligomer constituting the aliphatic polyester is polymerized under an acid catalyst having a pKa in the range of −2.0 to −1.7. Is.
　特に、上記酸触媒としては、pKaが-1.85～-1.7の範囲内であるものを使用することが好ましい。 In particular, it is preferable to use an acid catalyst having a pKa in the range of 1.85 to -1.7.
　さらに、本発明に係る脂肪族ポリエステルの製造方法において、上記脂肪族ポリエステルとしてポリ乳酸を製造する際には、溶解度パラメータの値が21～25の範囲内である酸触媒を使用することが好ましい。 Furthermore, in the method for producing an aliphatic polyester according to the present invention, when polylactic acid is produced as the aliphatic polyester, it is preferable to use an acid catalyst having a solubility parameter value in the range of 21 to 25.
　ここで、上記酸触媒としては、特に限定されないが、ドデシルベンゼンスルホン酸、メチシレンスルホン酸及び２－ナフタレンスルホン酸からなる群から選ばれる少なくとも１種の化合物を使用することができる。 Here, the acid catalyst is not particularly limited, but at least one compound selected from the group consisting of dodecylbenzenesulfonic acid, methicylenesulfonic acid and 2-naphthalenesulfonic acid can be used.
　なかでも、上記酸触媒としては、２－ナフタレンスルホン酸を使用することが好ましい。上記酸触媒として２－ナフタレンスルホン酸を使用した場合には脂肪族ポリエステルの着色を抑制することができる。 Of these, 2-naphthalenesulfonic acid is preferably used as the acid catalyst. When 2-naphthalenesulfonic acid is used as the acid catalyst, coloring of the aliphatic polyester can be suppressed.
　また本発明に係る脂肪族ポリエステルの製造方法において、モノマーとしては、脂肪族ヒドロキシカルボン酸若しくは脂肪族ジオール及び脂肪族ジカルボン酸を挙げることができる。 In the method for producing an aliphatic polyester according to the present invention, examples of the monomer include aliphatic hydroxycarboxylic acid or aliphatic diol and aliphatic dicarboxylic acid.
　本明細書は本願の優先権の基礎である日本国特許出願2009-015683号の明細書および／または図面に記載される内容を包含する。 This specification includes the contents described in the specification and / or drawings of Japanese Patent Application No. 2009-015683, which is the basis of the priority of the present application.
　本発明に係る脂肪族ポリエステルの製造方法では、モノマーやオリゴマーを直接重縮合して脂肪族ポリエステルを合成する際の反応速度を向上させることができ、より短時間で高分子量の脂肪族ポリエステルを製造することができる。したがって、本発明に係る脂肪族ポリエステルの製造方法によれば、脂肪族ポリエステルの生産性を向上させることができる。 In the method for producing an aliphatic polyester according to the present invention, the reaction rate when synthesizing an aliphatic polyester by directly polycondensing monomers and oligomers can be improved, and a high-molecular weight aliphatic polyester can be produced in a shorter time. can do. Therefore, according to the method for producing an aliphatic polyester according to the present invention, the productivity of the aliphatic polyester can be improved.
揮発性酸触媒の種類を換えてポリ乳酸を製造した際の反応時間と重量平均分子量との関係を示す特性図である。It is a characteristic view which shows the relationship between the reaction time at the time of manufacturing polylactic acid by changing the kind of volatile acid catalyst, and a weight average molecular weight. 揮発性酸触媒のpKaと重量平均分子量との関係を示す特性図である。FIG. 4 is a characteristic diagram showing the relationship between the pKa and the weight average molecular weight of a volatile acid catalyst. 揮発性酸触媒として２－ナフタレンスルホン酸を使用して合成したポリ乳酸（A）と、メシチレンスルホン酸を使用して合成したポリ乳酸（B）の写真である。2 is a photograph of polylactic acid (A) synthesized using 2-naphthalenesulfonic acid as a volatile acid catalyst and polylactic acid (B) synthesized using mesitylenesulfonic acid.
　以下、本発明に係る脂肪族ポリエステルの製造方法を詳細に説明する。 Hereinafter, the production method of the aliphatic polyester according to the present invention will be described in detail.
　本発明に係る脂肪族ポリエステルの製造方法は、当該脂肪族ポリエステルを構成するモノマー若しくはオリゴマーを、pKaが-2.0～-1.7の範囲内、好ましくは-1.9～-1.7の範囲内、より好ましくは-1.85～-1.7の範囲内にある酸触媒の存在下で直接重合させる方法である。ここで、pKaとは、式：pKa=-log10Ka（Kaは酸解離定数）で定義される値である。酸触媒を含む酸化合物については、その分子構造からpKaを算出することができる、例えばソフトウェア：Calculator Plugins（ChemAxons社）を使用して算出することができる。 In the method for producing an aliphatic polyester according to the present invention, the monomer or oligomer constituting the aliphatic polyester has a pKa in the range of -2.0 to -1.7, preferably in the range of -1.9 to -1.7, more preferably- This is a method of direct polymerization in the presence of an acid catalyst within the range of 1.85 to -1.7. Here, pKa is a value defined by the formula: pKa = −log 10 Ka (Ka is an acid dissociation constant). For an acid compound containing an acid catalyst, pKa can be calculated from its molecular structure, for example, using software: Calculator Plugins (ChemAxons).
　ここで、pKaが-2.0～-1.7の範囲内にある酸触媒としては、特に、揮発性酸触媒であることが好ましい。揮発性酸触媒を使用することにより、例えば製造された脂肪族ポリエステルを再加熱することで当該脂肪族ポリエステルから酸触媒を除去することができる。 Here, the acid catalyst having a pKa in the range of -2.0 to -1.7 is particularly preferably a volatile acid catalyst. By using a volatile acid catalyst, the acid catalyst can be removed from the aliphatic polyester, for example, by reheating the produced aliphatic polyester.
　具体的に、pKaが-2.0～-1.7の範囲内にある揮発性酸触媒としては、特に限定されないが、ドデシルベンゼンスルホン酸（pKa＝-1.84）、メチシレンスルホン酸（pKa＝-1.75）及び２－ナフタレンスルホン酸（pKa＝-1.81）を挙げることができる。 Specifically, the volatile acid catalyst having a pKa in the range of −2.0 to −1.7 is not particularly limited, but dodecylbenzenesulfonic acid (pKa = 1.84), methicylenesulfonic acid (pKa = 1.75) and 2-Naphthalenesulfonic acid (pKa = 1.81) can be mentioned.
　また、pKaが-2.0～-1.7の範囲内にある揮発性酸触媒としては、モノアルキルベンゼンスルホン酸、ジアルキルベンゼンスルホン酸及びトリアルキルベンゼンスルホン酸を挙げることができる。モノアルキルベンゼンスルホン酸として、アルキル基はパラ位、オルト位及びメタ位のいずれに位置していても良い。例えば、モノアルキルベンゼンスルホン酸としては、p-エチルベンゼンスルホン酸（pKa＝-2.0）、o-エチルベンゼンスルホン酸（pKa＝-2.0）及びm-エチルベンゼンスルホン酸（pKa＝-2.0）を挙げることができる。また、モノアルキルベンゼンスルホン酸としては、パラ位、オルト位及びメタ位を問わず、プロピルベンゼンスルホン酸（pKa＝-1.9）、ブチルベンゼンスルホン酸（pKa＝-1.8）、オクチルベンゼンスルホン酸（pKa＝-1.8）及びラウリルベンゼンスルホン酸（pKa＝-1.8）を挙げることができる。また、ジアルキルベンゼンスルホン酸としては、2,4-ジメチルスルホン酸（pKa＝-1.9）、2,5-ジメチルスルホン酸（pKa＝-1.9）、2,4-ジエチルスルホン酸（pKa＝-1.7）及び2,5-ジエチルスルホン酸（pKa＝-1.7）を挙げることができる。 Also, examples of the volatile acid catalyst having a pKa in the range of -2.0 to -1.7 include monoalkylbenzene sulfonic acid, dialkylbenzene sulfonic acid and trialkylbenzene sulfonic acid. As monoalkylbenzenesulfonic acid, the alkyl group may be located at any of the para, ortho and meta positions. For example, examples of monoalkylbenzenesulfonic acid include p-ethylbenzenesulfonic acid (pKa = -2.0), o-ethylbenzenesulfonic acid (pKa = -2.0), and m-ethylbenzenesulfonic acid (pKa = -2.0). In addition, monoalkylbenzenesulfonic acid includes propylbenzenesulfonic acid (pKa = -1.9), butylbenzenesulfonic acid (pKa = -1.8), octylbenzenesulfonic acid (pKa =) regardless of para position, ortho position, and meta position. -1.8) and laurylbenzenesulfonic acid (pKa = -1.8). Dialkylbenzenesulfonic acids include 2,4-dimethylsulfonic acid (pKa = -1.9), 2,5-dimethylsulfonic acid (pKa = -1.9), 2,4-diethylsulfonic acid (pKa = -1.7) And 2,5-diethylsulfonic acid (pKa = -1.7).
　さらに、pKaが-2.0～-1.7の範囲内にある揮発性酸触媒としては、1-アルキル-2-ナフタレンスルホン酸（pKa＝-1.7）、3-アルキル-2-ナフタレンスルホン酸（pKa＝-1.7）、4-アルキル-2-ナフタレンスルホン酸（pKa＝-1.7）、5-アルキル-2-ナフタレンスルホン酸（pKa＝-1.7）、6-アルキル-2-ナフタレンスルホン酸（pKa＝-1.7）、7-アルキル-2-ナフタレンスルホン酸（pKa＝-1.7）、8-アルキル-2-ナフタレンスルホン酸（pKa＝-1.7）、5-アミノ-2-ナフタレンスルホン酸（pKa＝-1.9）を挙げることができる。 Further, volatile acid catalysts having a pKa in the range of -2.0 to -1.7 include 1-alkyl-2-naphthalenesulfonic acid (pKa = -1.7), 3-alkyl-2-naphthalenesulfonic acid (pKa =- 1.7), 4-alkyl-2-naphthalenesulfonic acid (pKa = -1.7), 5-alkyl-2-naphthalenesulfonic acid (pKa = -1.7), 6-alkyl-2-naphthalenesulfonic acid (pKa = -1.7) , 7-alkyl-2-naphthalenesulfonic acid (pKa = -1.7), 8-alkyl-2-naphthalenesulfonic acid (pKa = -1.7), 5-amino-2-naphthalenesulfonic acid (pKa = -1.9) be able to.
　また、揮発性酸触媒としては、スルホン酸系化合物以外にもカルボン酸系化合物、リン酸系化合物又はケイ酸アルミニウムやゼオライト等の無機酸を挙げることができる。これらの揮発性酸触媒についても、上述したようにpKaを算出することで、-2.0～-1.7の範囲内にあるものを特定し使用することができる。 In addition to the sulfonic acid compound, examples of the volatile acid catalyst include carboxylic acid compounds, phosphoric acid compounds, inorganic acids such as aluminum silicate and zeolite. As for these volatile acid catalysts, those in the range of −2.0 to −1.7 can be specified and used by calculating the pKa as described above.
　pKaが上記範囲を下回る揮発性酸触媒又は上記範囲を上回る揮発性酸触媒を使用した場合には、重合反応速度が低下してしまい、例えば重量平均分子量が150,000といった高分子量の脂肪族ポリエステルを合成するためには長時間の反応時間を要することとなる。 When a volatile acid catalyst having a pKa below the above range or a volatile acid catalyst above the above range is used, the polymerization reaction rate decreases, and for example, a high molecular weight aliphatic polyester having a weight average molecular weight of 150,000 is synthesized. In order to do so, a long reaction time is required.
　また、特に、pKaが-2.0～-1.7の範囲内にある揮発性酸触媒として、メシチレンスルホン酸（pKa＝-1.75）を使用した場合には、重合反応速度を最も向上させることができ、より短時間で高分子量の脂肪族ポリエステルを製造することができる。また、メシチレンスルホン酸を使用した場合には、製造された脂肪族ポリエステルへの触媒残存率を大幅に低減することができる。触媒残存率が高い場合には、製造された脂肪族ポリエステルが経時的劣化する虞がある。したがって、メシチレンスルホン酸を使用した場合には、経時劣化の少ない高品質な脂肪族ポリエステルの製造することができる。 In particular, when mesitylenesulfonic acid (pKa = -1.75) is used as a volatile acid catalyst having a pKa in the range of -2.0 to -1.7, the polymerization reaction rate can be improved most. A high molecular weight aliphatic polyester can be produced in a short time. In addition, when mesitylenesulfonic acid is used, the catalyst remaining rate in the produced aliphatic polyester can be greatly reduced. When the catalyst residual ratio is high, the produced aliphatic polyester may deteriorate over time. Therefore, when mesitylenesulfonic acid is used, a high-quality aliphatic polyester with little deterioration with time can be produced.
　さらに、特に、pKaが-2.0～-1.7の範囲内にある揮発性酸触媒として、２－ナフタレンスルホン酸（pKa＝-1.81）を使用した場合には、重合反応速度を向上させるのみならず、製造された脂肪族ポリエステルにおける着色を防止することができる。 Furthermore, in particular, when 2-naphthalenesulfonic acid (pKa = -1.81) is used as a volatile acid catalyst having a pKa in the range of -2.0 to -1.7, not only the polymerization reaction rate is improved, Coloring in the produced aliphatic polyester can be prevented.
　さらにまた、pKaが-2.0～-1.7の範囲内にある揮発性酸触媒としては、製造対象の脂肪族ポリエステルの溶解度パラメータに対して近似した溶解度パラメータを有する揮発性酸を使用することが好ましい。ここで、近似とは、脂肪族ポリエステルの溶解度パラメータを基準として±２０％以内、好ましくは±１５％以内、より好ましくは±１０％以内の範囲を意味する。溶解度パラメータが製造対象の脂肪族ポリエステルと近似した揮発性酸触媒を使用することによって、より高分子量の脂肪族ポリエステルを製造することができる。例えば、ポリ乳酸を脂肪族ポリエステルとして製造する場合には、ポリ乳酸の溶解度パラメータが23.3であるため、23.3に近似した溶解度パラメータを有している例えばメチシレンスルホン酸を揮発性酸触媒として使用することが好ましい。 Furthermore, as the volatile acid catalyst having a pKa in the range of −2.0 to −1.7, it is preferable to use a volatile acid having a solubility parameter approximate to the solubility parameter of the aliphatic polyester to be produced. Here, the approximation means a range within ± 20%, preferably within ± 15%, more preferably within ± 10% based on the solubility parameter of the aliphatic polyester. By using a volatile acid catalyst whose solubility parameter approximates that of the aliphatic polyester to be produced, a higher molecular weight aliphatic polyester can be produced. For example, when polylactic acid is produced as an aliphatic polyester, since the solubility parameter of polylactic acid is 23.3, for example, methicylene sulfonic acid having a solubility parameter close to 23.3 is used as a volatile acid catalyst. It is preferable.
　ここで、溶解度パラメータの算出方法は、脂肪族ポリエステル及び揮発性酸ともに同じ算出方法を適用すれば良く、特に限定されない。一例として、溶解度パラメータはFedor法（Fedor's Group Contribution Method）を適用して算出することができる。このFedor法によれば下記式によって溶解度パラメータ(d)を算出することができる。 Here, the calculation method of the solubility parameter is not particularly limited as long as the same calculation method may be applied to both the aliphatic polyester and the volatile acid. As an example, the solubility parameter can be calculated by applying the Fedor method (Fedor's Group Contribution Method). According to this Fedor method, the solubility parameter (d) can be calculated by the following equation.
Figure JPOXMLDOC01-appb-M000001
Figure JPOXMLDOC01-appb-M000001
　上記式において、溶解度パラメータ〔ｄ〕の単位は〔(J/cm3)1/2〕である。また、上記式においてVは、原子団寄与法によって算出された構成上の繰り返し数のモル体積である。さらに、EcohはFodor〔J/mol〕によるモル結合エネルギーであり、Ecoh, iはi番目の原子団のEcohへの寄与を示ししている。 In the above formula, the unit of the solubility parameter [d] is [(J / cm 3 ) 1/2 ]. In the above formula, V is the molar volume of the number of structural repeats calculated by the atomic group contribution method. Further, E coh is the molar bond energy by Fodor [J / mol], and E coh, i indicates the contribution of the i-th atomic group to E coh .
　上記式を適用すると、ポリ乳酸の溶解度パラメータは下記のように算出される。なお、ポリ乳酸を構成する原子団のCH3のEcoh及びVはそれぞれ4710及び33.5であり、CHのEcoh及びVはそれぞれ3430及び-1.0であり、-O-のEcoh及びVはそれぞれ3350及び3.8であり、-CO2-のEcoh及びVはそれぞれ18000及び18.0である。 When the above formula is applied, the solubility parameter of polylactic acid is calculated as follows. In addition, E coh and V of CH 3 of the atomic group constituting polylactic acid are 4710 and 33.5, respectively, E coh and V of CH are 3430 and -1.0, respectively, and E coh and V of -O- are respectively ECOh and V of -CO 2- are 18000 and 18.0, respectively.
Figure JPOXMLDOC01-appb-M000002
Figure JPOXMLDOC01-appb-M000002
　pKaが-2.0～-1.7の範囲内にある揮発性酸触媒として、製造対象の脂肪族ポリエステルの溶解度パラメータに対して近似した溶解度パラメータを有する揮発性酸を使用した場合には、製造した脂肪族ポリエステルと揮発性酸触媒との親和性が優れており、その結果、揮発性酸触媒の使用量を低減することができる。したがって、この場合、製造された脂肪族ポリエステルにおける触媒残存率を低減できるとともに、製造コストを低減させることができる。 When a volatile acid having a solubility parameter approximate to the solubility parameter of the aliphatic polyester to be produced is used as the volatile acid catalyst having a pKa in the range of -2.0 to -1.7, the produced aliphatic The affinity between the polyester and the volatile acid catalyst is excellent, and as a result, the amount of the volatile acid catalyst used can be reduced. Therefore, in this case, the catalyst remaining rate in the produced aliphatic polyester can be reduced, and the production cost can be reduced.
　特に、脂肪族ポリエステルとしてポリ乳酸を製造する際には、pKaが-2.0～-1.7の範囲内にあり、且つ、溶解度パラメータがポリ乳酸（23.3）と近似する揮発性酸触媒として、メシチレンスルホン酸（溶解度パラメータ＝23.6）を使用することが好ましい。メシチレンスルホン酸の存在下で脱水重縮合反応を行ってポリ乳酸を製造することによって、触媒残存率を低減できるとともに製造コストを低減させることができる。 In particular, when polylactic acid is produced as an aliphatic polyester, mesitylenesulfonic acid is used as a volatile acid catalyst having a pKa in the range of -2.0 to -1.7 and a solubility parameter similar to that of polylactic acid (23.3). It is preferred to use (solubility parameter = 23.6). By producing a polylactic acid by performing a dehydration polycondensation reaction in the presence of mesitylene sulfonic acid, the catalyst residual rate can be reduced and the production cost can be reduced.
　一方、本発明に係る脂肪族ポリエステルの製造方法において、脂肪族ポリエステルのモノマーとしては、何ら限定されず、脂肪族ヒドロキシカルボン酸、脂肪族ジオール等の脂肪族多価アルコール及び脂肪族ジカルボン酸等の脂肪族多価カルボン酸の組み合わせを使用することができる。また、本発明に係る脂肪族ポリエステルの製造方法においては、脂肪族ポリエステルのモノマーの代わりに、脂肪族ヒドロキシカルボン酸を構成単位とするオリゴマー、若しくは脂肪族ジオール等の脂肪族多価アルコール及び脂肪族ジカルボン酸等の脂肪族多価カルボン酸からなるオリゴマーを原料として使用しても良い。 On the other hand, in the method for producing an aliphatic polyester according to the present invention, the monomer of the aliphatic polyester is not limited in any way, such as aliphatic polyhydric alcohols such as aliphatic hydroxycarboxylic acids and aliphatic diols, and aliphatic dicarboxylic acids. Combinations of aliphatic polyvalent carboxylic acids can be used. Further, in the method for producing an aliphatic polyester according to the present invention, an aliphatic polyhydric alcohol such as an aliphatic diol or an aliphatic polyhydric alcohol and an aliphatic having an aliphatic hydroxycarboxylic acid as a structural unit instead of the aliphatic polyester monomer. An oligomer made of an aliphatic polycarboxylic acid such as dicarboxylic acid may be used as a raw material.
　このような脂肪族ヒドロキシカルボン酸としては、特に限定されないが、２－ヒドロキシエタン酸、２－ヒドロキシプロパン酸（すなわち乳酸）、２－ヒドロキシブタン酸、２－ヒドロキシペンタン酸、２－ヒドロキシヘキサン酸、２－ヒドロキシヘプタン酸、２－ヒドロキシオクタン酸、２－ヒドロキシ－２－メチルプロパン酸、２－ヒドロキシ－２－メチルブタン酸、２－ヒドロキシ－２－エチルブタン酸、２－ヒドロキシ－２－メチルペンタン酸、２－ヒドロキシ－２－エチルペンタン酸、２－ヒドロキシ－２－プロピルペンタン酸、２－ヒドロキシ－２－ブチルペンタン酸、２－ヒドロキシ－２－メチルヘキサン酸、２－ヒドロキシ－２－エチルヘキサン酸、２－ヒドロキシ－２－プロピルヘキサン酸、２－ヒドロキシ－２－ブチルヘキサン酸、２－ヒドロキシ－２－ペンチルヘキサン酸、２－ヒドロキシ－２－メチルヘプタン酸、２－ヒドロキシ－２－メチルヘプタン酸、２－ヒドロキシ－２－エチルヘプタン酸、２－ヒドロキシ－２－プロピルヘプタン酸、２－ヒドロキシ－２－ブチルヘプタン酸、２－ヒドロキシ－２－ペンチルヘプタン酸、２－ヒドロキシ－２－ヘキシルヘプタン酸、２－ヒドロキシ－２－メチルオクタン酸、２－ヒドロキシ－２－エチルオクタン酸、２－ヒドロキシ－２－プロピルオクタン酸、２－ヒドロキシ－２－ブチルオクタン酸、２－ヒドロキシ－２－ペンチルオクタン酸、２－ヒドロキシ－２－ヘキシルオクタン酸、２－ヒドロキシ－２－ヘプチルオクタン酸、３－ヒドロキシプロパン酸、３－ヒドロキシブタン酸、３－ヒドロキシペンタン酸、３－ヒドロキシヘキサン酸、３－ヒドロキシヘプタン酸、３－ヒドロキシオクタン酸、３－ヒドロキシ－３－メチルブタン酸、３－ヒドロキシ－３－メチルペンタン酸、３－ヒドロキシ－３－エチルペンタン酸、３－ヒドロキシ－３－メチルヘキサン酸、３－ヒドロキシ－３－エチルヘキサン酸、３－ヒドロキシ－３－プロピルヘキサン酸、３－ヒドロキシ－３－メチルヘプタン酸、３－ヒドロキシ－３－エチルヘプタン酸、３－ヒドロキシ－３－プロピルヘプタン酸、３－ヒドロキシ－３－ブチルヘプタン酸、３－ヒドロキシ－３－メチルオクタン酸、３－ヒドロキシ－３－エチルオクタン酸、３－ヒドロキシ－３－プロピルオクタン酸、３－ヒドロキシ－３－ブチルオクタン酸、３－ヒドロキシ－３－ペンチルオクタン酸、４－ヒドロキシブタン酸、４－ヒドロキシペンタン酸、４－ヒドロキシヘキサン酸、４－ヒドロキシヘプタン酸、４－ヒドロキシオクタン酸、４－ヒドロキシ－４－メチルペンタン酸、４－ヒドロキシ－４－メチルヘキサン酸、４－ヒドロキシ－４－エチルヘキサン酸、４－ヒドロキシ－４－メチルヘプタン酸、４－ヒドロキシ－４－エチルヘプタン酸、４－ヒドロキシ－４－プロピルヘプタン酸、４－ヒドロキシ－４－メチルオクタン酸、４－ヒドロキシ－４－エチルオクタン酸、４－ヒドロキシ－４－プロピルオクタン酸、４－ヒドロキシ－４－ブチルオクタン酸、５－ヒドロキシペンタン酸、５－ヒドロキシヘキサン酸、５－ヒドロキシヘプタン酸、５－ヒドロキシオクタン酸、５－ヒドロキシ－５－メチルヘキサン酸、５－ヒドロキシ－５－メチルヘプタン酸、５－ヒドロキシ－５－エチルヘプタン酸、５－ヒドロキシ－５－メチルオクタン酸、５－ヒドロキシ－５－エチルオクタン酸、５－ヒドロキシ－５－プロピルオクタン酸、６－ヒドロキシヘキサン酸、６－ヒドロキシヘプタン酸、６－ヒドロキシオクタン酸、６－ヒドロキシ－６－メチルヘプタン酸、６－ヒドロキシ－６－メチルオクタン酸、６－ヒドロキシ－６－エチルオクタン酸、７－ヒドロキシヘプタン酸、７－ヒドロキシオクタン酸、７－ヒドロキシ－７－メチルオクタン酸、８－ヒドロキシオクタン酸等を挙げることができる。また、脂肪族ヒドロキシカルボン酸から環状体物やオリゴマーを使用することもできる。また、原料として脂肪族ヒドロキシカルボン酸を使用する場合、一種のみを使用しても良いが、二種以上の混合物を用いても良い。また、上述した脂肪族ヒドロキシカルボン酸のなかには光学異性体を有する場合があるが、原料として使用する脂肪族ヒドロキシカルボン酸としては、Ｄ体、Ｌ体、Ｄ／Ｌ体の形態のいかなる形態であっても良い。 Examples of such aliphatic hydroxycarboxylic acids include, but are not limited to, 2-hydroxyethanoic acid, 2-hydroxypropanoic acid (ie, lactic acid), 2-hydroxybutanoic acid, 2-hydroxypentanoic acid, 2-hydroxyhexanoic acid, 2-hydroxyheptanoic acid, 2-hydroxyoctanoic acid, 2-hydroxy-2-methylpropanoic acid, 2-hydroxy-2-methylbutanoic acid, 2-hydroxy-2-ethylbutanoic 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-buty Hexanoic acid, 2-hydroxy-2-pentylhexanoic acid, 2-hydroxy-2-methylheptanoic acid, 2-hydroxy-2-methylheptanoic acid, 2-hydroxy-2-ethylheptanoic acid, 2-hydroxy-2-propyl Heptanoic acid, 2-hydroxy-2-butylheptanoic acid, 2-hydroxy-2-pentylheptanoic acid, 2-hydroxy-2-hexylheptanoic acid, 2-hydroxy-2-methyloctanoic acid, 2-hydroxy-2-ethyl Octanoic acid, 2-hydroxy-2-propyloctanoic acid, 2-hydroxy-2-butyloctanoic acid, 2-hydroxy-2-pentyloctanoic acid, 2-hydroxy-2-hexyloctanoic acid, 2-hydroxy-2-heptyl Octanoic acid, 3-hydroxypropanoic acid, 3-hydroxybutanoic acid, 3-hydroxype Tanic 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-propylheptanoic 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-butyloctanoic acid, 5-hydroxypentanoic acid, 5-hydroxyhexanoic acid, 5-hydroxyheptanoic acid, 5-hydroxyoctane Acid, 5-hydroxy-5-methylhexanoic acid, 5-hydroxy- -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-hydroxyoctanoic acid and the like. Moreover, a cyclic body thing and an oligomer can also be used from aliphatic hydroxycarboxylic acid. Moreover, when using aliphatic hydroxycarboxylic acid as a raw material, only 1 type may be used, but 2 or more types of mixtures may be used. In addition, some of the above-mentioned aliphatic hydroxycarboxylic acids may have optical isomers, but the aliphatic hydroxycarboxylic acid used as a raw material may be in any form of D-form, L-form, and D / L-form. May be.
　また、脂肪族ジオールとしては、特に限定されないが、例えば、エチレングリコール、１，３－プロパンジオール、１，３－ブタンジオール、１，４－ブタンジオール、１，５－ペンタンジオール、３－メチル－１，５－ペンタンジオール、１，６－ヘキサンジオール、１，８－オクタンジオール、１，１０－デカンジオール、１，１２－ドデカンジオール、プロピレングリコール及びネオペンチルグリコール等を挙げることができる。脂肪族ジオールとしては、一種のみを使用しても良いが、二種類以上を混合して使用しても良い。 The aliphatic diol is not particularly limited, and examples thereof include ethylene glycol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 3-methyl- Examples thereof include 1,5-pentanediol, 1,6-hexanediol, 1,8-octanediol, 1,10-decanediol, 1,12-dodecanediol, propylene glycol, and neopentyl glycol. As the aliphatic diol, only one kind may be used, or two or more kinds may be mixed and used.
　さらに、脂肪族ジカルボン酸としては、特に限定されないが、例えば、コハク酸、シュウ酸、マロン酸、グルタル酸、アジピン酸、ピメリン酸、スベリン酸、アゼライン酸、セバシン酸、ウンデカン二酸、ドデカン二酸、フマル酸及びダイマー酸等を挙げることができる。脂肪族ジカルボン酸としては、一種のみを使用しても良いが、二種類以上を混合して使用しても良い。 Further, the aliphatic dicarboxylic acid is not particularly limited, but for example, succinic acid, oxalic acid, malonic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid. , Fumaric acid and dimer acid. As the aliphatic dicarboxylic acid, only one kind may be used, or two or more kinds may be mixed and used.
　上述した脂肪族ヒドロキシカルボン酸、脂肪族ジオール及び脂肪族ジカルボン酸を用いた重合反応は、いわゆる固相重合法を適用することが好ましい。固相重合法とは、これらモノマーの脱水重縮合反応により得られるオリゴマー若しくはポリマー（脂肪族ポリエステル）を、固体状態を維持したままでさらに脱水重縮合反応を行う重合法を意味する。固体状態を維持するとは、当該オリゴマー若しくはポリマーの融点よりも低い温度を維持することを意味する。このような固相重合法を適用することによって、より高分子量の脂肪族ポリエステルを製造することができる。 It is preferable to apply a so-called solid phase polymerization method for the polymerization reaction using the aliphatic hydroxycarboxylic acid, the aliphatic diol and the aliphatic dicarboxylic acid described above. The solid phase polymerization method means a polymerization method in which an oligomer or polymer (aliphatic polyester) obtained by a dehydration polycondensation reaction of these monomers is further subjected to a dehydration polycondensation reaction while maintaining a solid state. Maintaining a solid state means maintaining a temperature lower than the melting point of the oligomer or polymer. By applying such a solid phase polymerization method, a higher molecular weight aliphatic polyester can be produced.
　このような固相重合法を適用する際、pKaが-2.0～-1.7の範囲内にある揮発性酸触媒は、脂肪族ヒドロキシカルボン酸、脂肪族ジオール及び脂肪族ジカルボン酸といったモノマーを用いた脱水重縮合反応によりオリゴマーやポリマーを合成する段階、これらオリゴマーやポリマーの固体状態を維持したまま更に脱水重縮合反応を行うことで高分子量化する段階のいずれの段階で使用しても良いし、両方の段階で使用しても良い。特に、固相重合法を適用する際、pKaが-2.0～-1.7の範囲内にある揮発性酸触媒は、脂肪族ヒドロキシカルボン酸、脂肪族ジオール及び脂肪族ジカルボン酸といったモノマーを用いた脱水重縮合反応によりオリゴマーやポリマーを合成する段階で使用することが好ましい。 When such a solid phase polymerization method is applied, a volatile acid catalyst having a pKa in the range of -2.0 to -1.7 is dehydration using monomers such as aliphatic hydroxycarboxylic acid, aliphatic diol and aliphatic dicarboxylic acid. It can be used at any stage of synthesizing oligomers and polymers by polycondensation reaction, and increasing the molecular weight by further dehydrating polycondensation reaction while maintaining the solid state of these oligomers and polymers. It may be used at this stage. In particular, when applying the solid phase polymerization method, the volatile acid catalyst having a pKa in the range of −2.0 to −1.7 is a dehydration polymerization using monomers such as aliphatic hydroxycarboxylic acid, aliphatic diol, and aliphatic dicarboxylic acid. It is preferably used at the stage of synthesizing an oligomer or polymer by a condensation reaction.
　また、pKaが-2.0～-1.7の範囲内にある揮発性酸触媒の存在下で脱水重縮合反応を行う際には、反応温度を１００℃～２００℃とすることが好ましく、１１０℃～１８０℃とすることがより好ましく、１３０℃～１６０℃とすることが更に好ましい。 When the dehydration polycondensation reaction is performed in the presence of a volatile acid catalyst having a pKa in the range of −2.0 to −1.7, the reaction temperature is preferably 100 ° C. to 200 ° C., preferably 110 ° C. to 180 ° C. More preferably, the temperature is 130 ° C. to 160 ° C.
　さらに、脂肪族ヒドロキシカルボン酸、脂肪族ジオール及び脂肪族ジカルボン酸といったモノマーを用いた脱水重縮合反応によりオリゴマーやポリマーを合成する段階では、当該オリゴマーやポリマーの重量平均分子量が２０００～１００００となるまで反応を進行させることが好ましく、３０００～８０００となるまで反応を進行させることがより好ましく、４０００～６０００となるまで反応を進行させることが更に好ましい。なお、得られたオリゴマーやポリマーは結晶化処理を施し、軟化温度及び融解開始温度を出来るだけ高温化しておくことが望ましい。この結晶化処理は、得られたオリゴマーやポリマーにより異なるが、例えば、８０℃～１１０℃にて１時間以上加熱するといった処理により実施できる。 Furthermore, in the stage of synthesizing an oligomer or polymer by a dehydration polycondensation reaction using monomers such as aliphatic hydroxycarboxylic acid, aliphatic diol and aliphatic dicarboxylic acid, until the weight average molecular weight of the oligomer or polymer reaches 2000 to 10,000. The reaction is preferably allowed to proceed, more preferably the reaction is allowed to reach 3000 to 8000, still more preferably the reaction is allowed to proceed to 4000 to 6000. The obtained oligomer or polymer is preferably subjected to crystallization treatment, and the softening temperature and melting start temperature are preferably increased as much as possible. This crystallization treatment varies depending on the oligomer or polymer obtained, but can be carried out, for example, by heating at 80 ° C. to 110 ° C. for 1 hour or longer.
　また、この段階の脱水重縮合反応の終了後、未反応のモノマーや低分子量のオリゴマーを除去することが好ましい。未反応のモノマーや低分子量のオリゴマーを反応系から除去することによって、後の固相状態で脱水重縮合する際に短時間で重合反応を進行させることができる。未反応のモノマーや低分子量のオリゴマーを反応系から除去する方法としては、例えば、真空加熱（真空度：１～１０KPa、加熱温度：１００～１２０℃）又は水、アセトン若しくはアルコール等による洗浄により実施することができる。 Further, it is preferable to remove unreacted monomers and low molecular weight oligomers after completion of the dehydration polycondensation reaction at this stage. By removing unreacted monomers and low molecular weight oligomers from the reaction system, the polymerization reaction can proceed in a short time when dehydration polycondensation is performed in the solid phase state later. As a method for removing unreacted monomers and low molecular weight oligomers from the reaction system, for example, vacuum heating (degree of vacuum: 1 to 10 KPa, heating temperature: 100 to 120 ° C.) or washing with water, acetone, alcohol or the like is performed. can do.
　また、得られたオリゴマーやポリマーの固相状態を維持して更に脱水重縮合反応を行う際には、当該オリゴマーやポリマーを例えば、粉末、粒、フレーク、球、半球、ペレット及び塊状等にすることが好ましい。この段階の脱水重縮合反応は、反応温度をオリゴマーやポリマーが溶融しない限度で高温とすることが好ましい。例えば、分子量Mwが２万未満のポリマーを固相状態で更に脱水重縮合させる場合には、反応温度を溶融温度未満の１００～１４０℃とすることが好ましく、１００～１２０℃とすることがより好ましい。また、分子量Mwが２万以上のポリマーを固相状態で更に脱水重縮合させる場合には、反応温度を溶融温度未満の１４０～１８０℃とすることが好ましく、１４０～１６０℃とすることがより好ましい。 Further, when the dehydration polycondensation reaction is performed while maintaining the solid state of the obtained oligomer or polymer, the oligomer or polymer is, for example, made into powder, granules, flakes, spheres, hemispheres, pellets, and a lump. It is preferable. In the dehydration polycondensation reaction at this stage, the reaction temperature is preferably set to a high temperature as long as the oligomer or polymer does not melt. For example, when a polymer having a molecular weight Mw of less than 20,000 is further subjected to dehydration polycondensation in the solid state, the reaction temperature is preferably 100 to 140 ° C. below the melting temperature, more preferably 100 to 120 ° C. preferable. When a polymer having a molecular weight Mw of 20,000 or more is further subjected to dehydration polycondensation in the solid state, the reaction temperature is preferably 140 to 180 ° C. below the melting temperature, more preferably 140 to 160 ° C. preferable.
　一方、以上で説明した脂肪族ポリエステルの製造方法では、残存する揮発性酸触媒は必要により、公知の方法により除去することが好ましい。例えば、得られた固体状態の脂肪族ポリエステルを揮発性酸触媒のみ溶出させる溶媒と接触させることで当該揮発性酸触媒を除去する方法、脂肪族系ポリエステルを良溶媒に溶解させた後、その溶媒と親和性が低くまた揮発性酸触媒を溶解させる溶媒と接触させることで当該揮発性酸触媒を抽出する方法、若しくは得られた脂肪族ポリエステルを良溶媒に溶解させた後、ゼオライト、モレキュラーシーブ等の吸着剤に揮発性酸触媒を吸着させ揮発性酸触媒を除去する方法等が挙げられる。 On the other hand, in the method for producing an aliphatic polyester described above, the remaining volatile acid catalyst is preferably removed by a known method, if necessary. For example, a method of removing the volatile acid catalyst by contacting the obtained solid state aliphatic polyester with a solvent that elutes only the volatile acid catalyst, after dissolving the aliphatic polyester in a good solvent, the solvent And a method of extracting the volatile acid catalyst by contacting with a solvent that dissolves the volatile acid catalyst, or after dissolving the obtained aliphatic polyester in a good solvent, zeolite, molecular sieve, etc. And a method of removing the volatile acid catalyst by adsorbing the volatile acid catalyst to the adsorbent.
　以上のように製造された脂肪族ポリエステルは、単独で各種製品の原材料として使用することもできるが、耐衝撃性をより向上させるために、脂肪族ポリエステル樹脂以外のゴム、エラストマ、軟質樹脂成分等が更に添加された樹脂組成物として各種製品の原材料として使用されてもよい。このような成分の具体的な種類は特に限定されないが、脂肪族ポリエステルとの相溶性が良好な成分、もしくは化学的変性や相溶化剤の添加により相溶性が改善されている成分であることが好ましい。また、このような成分を含有する場合、その含有量が多過ぎると却って高温弾性率及び荷重たわみ温度の低下を招くおそれがあるため、脂肪族ポリエステル１００重量部に対して２０重量部以下であることが好ましく、１０重量部以下であることがより好ましく、５重量部以下であることがさらに好ましい。 Aliphatic polyester produced as described above can be used alone as a raw material for various products, but in order to further improve impact resistance, rubber other than aliphatic polyester resin, elastomer, soft resin component, etc. May be used as a raw material for various products as a resin composition to which is further added. Specific types of such components are not particularly limited, but may be components having good compatibility with aliphatic polyesters, or components having improved compatibility by chemical modification or addition of a compatibilizing agent. preferable. Further, when such a component is contained, if the content is too large, the high temperature elastic modulus and the deflection temperature under load may be lowered, so that it is 20 parts by weight or less with respect to 100 parts by weight of the aliphatic polyester. It is preferably 10 parts by weight or less, more preferably 5 parts by weight or less.
　また、脂肪族ポリエステル樹脂を含む樹脂組成物においては、成形時等における熱劣化による脂肪族ポリエステルの分子量の低下によってカルボキシル基及び水酸基が増加して成形体の加水分解が促進されることをより確実に防止するために、酸化防止剤等の熱安定剤が更に添加されていることが好ましい。このような熱安定剤は、その具体的な種類は特に限定されず、また、その含有量は脂肪族ポリエステル１００重量部に対して２重量部以下であることが好ましく、１重量部以下であることがより好ましく、０．１重量部以下であることがさらに好ましい。 In addition, in a resin composition containing an aliphatic polyester resin, it is more certain that carboxyl groups and hydroxyl groups are increased due to a decrease in the molecular weight of the aliphatic polyester due to thermal deterioration during molding and the like, and hydrolysis of the molded product is promoted. In order to prevent this, it is preferable that a heat stabilizer such as an antioxidant is further added. The specific kind of the heat stabilizer is not particularly limited, and the content thereof is preferably 2 parts by weight or less with respect to 100 parts by weight of the aliphatic polyester, and is 1 part by weight or less. More preferably, the amount is 0.1 parts by weight or less.
　さらに、脂肪族ポリエステルを含む樹脂組成物においては、その特性を損なわない限りにおいて、滑剤、光安定剤、紫外線吸収剤、帯電防止剤、難燃剤、離型剤、顔料、着色剤、染料、抗菌剤等の添加剤を更に添加してもよい。このような添加剤の含有量は、樹脂組成物中において、脂肪族ポリエルテル１００重量部に対して２０重量部以下であることが好ましい。 Furthermore, in a resin composition containing an aliphatic polyester, a lubricant, a light stabilizer, an ultraviolet absorber, an antistatic agent, a flame retardant, a release agent, a pigment, a colorant, a dye, an antibacterial agent, as long as the characteristics are not impaired. An additive such as an agent may be further added. The content of such an additive is preferably 20 parts by weight or less with respect to 100 parts by weight of the aliphatic polyether in the resin composition.
　次に、製造された脂肪族ポリエステルを含む樹脂組成物を用いた成形体について説明する。具体的な成形方法及び成形における諸条件は、用いる脂肪族ポリエステル等に応じて適宜選択されるが、一般的には以下の成形方法が好適に採用される。すなわち、(i)脂肪族ポリエステルを含む樹脂組成物を溶融状態とする工程と、(ii)溶融した樹脂組成物をその融点以下の温度に移行させた状態で所定時間保持して結晶化させる工程を含む方法が好ましい。その際、(i)の工程において樹脂組成物を溶融する際の温度は、１７０～２３０℃であることが好ましい。この温度が前記下限未満であると、樹脂組成物の溶融が不十分となって諸成分が均一に分散しにくくなる傾向があり、他方、この温度が前記上限を超えると、脂肪族ポリエステルの分子量が低下して得られる成形体の物性が損なわれる傾向がある。また、(ii)の工程における保持温度は３０～１６０℃であることが好ましく、保持時間は５～１８００秒が好ましい。この保持温度が上記下限未満であると、得られる成形体における結晶化が不十分となる傾向があり、他方、保持温度が上記上限を超えると溶融により結晶化が不十分となる傾向にある。また、この保持時間が上記下限未満であると、得られる成形体における結晶化が不十分となる傾向があり、他方、保持時間が上記上限を超えると、成形体を得るための所要時間が不必要に長時間となる傾向がある。なお、成形体を製造するに際し、その成形方法は射出成形に限定されるものではなく、押出成形、ブロー成形、インフレーション成形、異形押出成形、射出ブロー成形、真空圧空成形、紡糸等のいずれの方法であってもよい。また、本発明の成形体の形状、厚み等は特に制限されず、射出成形品、押出成形品、圧縮成形品、ブロー成形品、シート、フィルム、糸、ファブリック等のいずれでもよい。また、前記のようにして樹脂組成物を溶融成形せしめた後に、得られた成形体に更に熱処理を施してもよい。その熱処理の温度は８０～１５０℃であることが好ましく、保持時間は５～２０００秒が好ましい。 Next, a molded body using the resin composition containing the produced aliphatic polyester will be described. The specific molding method and various molding conditions are appropriately selected according to the aliphatic polyester to be used, but generally the following molding methods are preferably employed. That is, (i) a step of bringing a resin composition containing an aliphatic polyester into a molten state, and (ii) a step of crystallizing the molten resin composition by holding it for a predetermined time in a state where the molten resin composition has been shifted to a temperature below its melting point Is preferred. At that time, the temperature at which the resin composition is melted in the step (i) is preferably 170 to 230 ° C. If the temperature is less than the lower limit, the resin composition tends to be insufficiently melted and the components are difficult to uniformly disperse. On the other hand, if the temperature exceeds the upper limit, the molecular weight of the aliphatic polyester There exists a tendency for the physical property of the molded object obtained by fall to be impaired. The holding temperature in the step (ii) is preferably 30 to 160 ° C., and the holding time is preferably 5 to 1800 seconds. When the holding temperature is less than the above lower limit, crystallization in the resulting molded product tends to be insufficient, and when the holding temperature exceeds the upper limit, crystallization tends to be insufficient due to melting. Further, if the holding time is less than the above lower limit, crystallization in the resulting molded article tends to be insufficient. On the other hand, if the holding time exceeds the upper limit, the time required for obtaining the molded article is insufficient. There is a tendency to take a long time if necessary. In the production of a molded body, the molding method is not limited to injection molding, and any method such as extrusion molding, blow molding, inflation molding, profile extrusion molding, injection blow molding, vacuum pressure molding, spinning, etc. It may be. Moreover, the shape, thickness, etc. of the molded product of the present invention are not particularly limited, and any of injection molded products, extrusion molded products, compression molded products, blow molded products, sheets, films, yarns, fabrics, and the like may be used. Further, after the resin composition is melt-molded as described above, the obtained molded body may be further subjected to heat treatment. The heat treatment temperature is preferably 80 to 150 ° C., and the holding time is preferably 5 to 2000 seconds.
　以下、本発明に係る脂肪族ポリエステルの製造方法の具体的な実施例を説明するが、本発明の技術的範囲は以下の実施例に限定されるものではない。 Hereinafter, specific examples of the method for producing an aliphatic polyester according to the present invention will be described, but the technical scope of the present invention is not limited to the following examples.
（実施例１）
　実施例１では、揮発性酸触媒として２－ナフタレンスルホン酸（pKa＝-1.81、溶解度パラメータ値（SP値）＝25.7）を使用し、脂肪族ポリエステルとしてポリ乳酸を合成した。具体的には、L-乳酸（Hipure90；ピューラック社製）5.00gを試験管に投入し、さらに２－ナフタレンスルホン酸（東京化成社製）を触媒として25mg（0.5wt%）添加した。室温及び常圧より段階的に昇温及び減圧して、反応温度150℃及び反応圧力30Torrの条件として脱水重縮合反応を行った。反応時間を5hとし、オリゴマーを合成した。 Example 1
In Example 1, 2-naphthalenesulfonic acid (pKa = 1.81, solubility parameter value (SP value) = 25.7) was used as a volatile acid catalyst, and polylactic acid was synthesized as an aliphatic polyester. Specifically, 5.00 g of L-lactic acid (Hipure 90; manufactured by Pulac Co., Ltd.) was put into a test tube, and 25 mg (0.5 wt%) of 2-naphthalenesulfonic acid (manufactured by Tokyo Chemical Industry Co., Ltd.) was added as a catalyst. The dehydration polycondensation reaction was carried out under conditions of a reaction temperature of 150 ° C. and a reaction pressure of 30 Torr by gradually raising and lowering the temperature from room temperature and normal pressure. The reaction time was 5 h, and an oligomer was synthesized.
　次に、得られたオリゴマーを乳鉢を用いて粉砕したのち、試験管に1.0gずつ投入した。反応温度110℃でアニーリング処理を実施した。その後、反応温度140℃及び反応圧力1Torrの条件で15h固相重合させ、さらに反応温度160℃及び反応圧力1Torrの条件で45h固相重合させて、ポリ乳酸（１）を得た。 Next, after the obtained oligomer was pulverized using a mortar, 1.0 g was added to each test tube. Annealing treatment was performed at a reaction temperature of 110 ° C. Thereafter, solid-phase polymerization was performed for 15 hours under conditions of a reaction temperature of 140 ° C. and a reaction pressure of 1 Torr, and further, solid-phase polymerization was performed for 45 hours under conditions of a reaction temperature of 160 ° C. and a reaction pressure of 1 Torr to obtain polylactic acid (1).
（実施例２）
　実施例２では、揮発性酸触媒としてドデシルベンゼンスルホン酸（pKa＝-1.84、SP値＝20.1）を用いた以外は実施例１と同様の作業を行い、ポリ乳酸（２）を得た。 (Example 2)
In Example 2, polylactic acid (2) was obtained in the same manner as in Example 1 except that dodecylbenzenesulfonic acid (pKa = 1.84, SP value = 20.1) was used as the volatile acid catalyst.
（実施例３）
　実施例３では、揮発性酸触媒としてメシチレンスルホン酸（pKa＝-1.75、SP値＝23.6）を用いた以外は実施例１と同様の作業を行い、ポリ乳酸（３）を得た。 (Example 3)
In Example 3, polylactic acid (3) was obtained in the same manner as in Example 1 except that mesitylenesulfonic acid (pKa = 1.75, SP value = 23.6) was used as the volatile acid catalyst.
（実施例４）
　実施例４では、メシチレンスルホン酸を触媒として12.5mg（0.25wt%）用いた以外は実施例３と同様の作業を行い、ポリ乳酸（４）を得た。 Example 4
In Example 4, polylactic acid (4) was obtained in the same manner as in Example 3, except that 12.5 mg (0.25 wt%) of mesitylenesulfonic acid was used as a catalyst.
（比較例１）
　比較例１では、揮発性酸触媒としてｐ－トルエンスルホン酸（pKa＝-2.14、SP値＝23.5）を用いた以外は実施例１と同様の作業を行い、ポリ乳酸（５）を得た。 (Comparative Example 1)
In Comparative Example 1, polylactic acid (5) was obtained in the same manner as in Example 1 except that p-toluenesulfonic acid (pKa = -2.14, SP value = 23.5) was used as the volatile acid catalyst.
（比較例２）
　比較例２では、揮発性酸触媒としてカンファースルホン酸（pKa＝-1.64、SP値＝33.3）を触媒として用いた以外は実施例１と同様の作業を行い、ポリ乳酸（６）を得た。 (Comparative Example 2)
In Comparative Example 2, a polylactic acid (6) was obtained in the same manner as in Example 1 except that camphorsulfonic acid (pKa = -1.64, SP value = 33.3) was used as the volatile acid catalyst.
（結果）
　以上の実施例１～４及び比較例１～２で製造したポリ乳酸（１）～（６）について、重量平均分子量（Mｗ）、数平均分子量（Ｍｎ）、融点（Ｔｍ）及び光学純度を測定した。なお、重量平均分子量（Mｗ）及び数平均分子量（Ｍｎ）は、ゲルパーミエションクロマトグラフィ（GPC）法により測定した。具体的に、重量平均分子量（Mｗ）及び数平均分子量（Ｍｎ）は、GPC測定装置として東ソー株式会社製のHLC-8100GPC（検出器：示差屈折計（RI））を使用し、カラムとして東ソー株式会社製のTSK-GEL Hタイプ（溶離液：クロロホルム）を使用した。重量平均分子量（Mｗ）及び数平均分子量（Ｍｎ）の値は標準ポリスチレンにて換算した。また、融点（Ｔｍ）は、ティエイインスツルメント社製のDSC Q100を用いた。融点（Ｔｍ）測定に際しては、試料10mgを昇温速度10℃/minで室温から250℃まで昇温させた方法を適用した。さらに光学純度は、試料1mgに5M NaOH 5mlとイソプロパノール 2.5mlを添加し、40℃で加熱撹拌しながら加水分解した後、1M H2SO4で中和した中和液を希釈し、HPLCにて測定したL-乳酸及びD-乳酸の検出ピーク面積から下記式により算出した。 (result)
For the polylactic acids (1) to (6) produced in Examples 1 to 4 and Comparative Examples 1 to 2, the weight average molecular weight (Mw), number average molecular weight (Mn), melting point (Tm) and optical purity were measured. did. In addition, the weight average molecular weight (Mw) and the number average molecular weight (Mn) were measured by a gel permeation chromatography (GPC) method. Specifically, the weight average molecular weight (Mw) and number average molecular weight (Mn) were measured using a Tosoh Co., Ltd. HLC-8100GPC (detector: differential refractometer (RI)) as a GPC measurement device, and Tosoh Corporation as a column. A company-made TSK-GEL H type (eluent: chloroform) was used. The values of weight average molecular weight (Mw) and number average molecular weight (Mn) were converted with standard polystyrene. The melting point (Tm) was DSC Q100 manufactured by TI Instruments. In measuring the melting point (Tm), a method in which 10 mg of a sample was heated from room temperature to 250 ° C. at a temperature rising rate of 10 ° C./min was applied. The optical purity was determined by adding 5 ml of 5M NaOH and 2.5 ml of isopropanol to 1 mg of sample, hydrolyzing while stirring at 40 ° C, diluting the neutralized solution neutralized with 1M H 2 SO 4 , and using HPLC. It calculated from the following formula from the detected peak areas of L-lactic acid and D-lactic acid.
　　光学純度＝１００×[L]/([L]＋[D])
（式中、[L]はL-乳酸の重量比率（％）であり、[D]はD-乳酸の重量比率（％）である。）
HPLC測定には、ウォーターズ社製のLC Module Iを使用し、カラムには株式会社住化分析センター社製のSUMICHIRAL OA-5000を使用した。 Optical purity = 100 × [L] / ([L] + [D])
(In the formula, [L] is the weight ratio (%) of L-lactic acid, and [D] is the weight ratio (%) of D-lactic acid.)
For HPLC measurement, LC Module I manufactured by Waters was used, and SUMICHIRAL OA-5000 manufactured by Sumika Chemical Analysis Co., Ltd. was used for the column.
　結果を表１に示した。 The results are shown in Table 1.
Figure JPOXMLDOC01-appb-T000003
Figure JPOXMLDOC01-appb-T000003
　また、以上の実施例１～４及び比較例１～２に示したポリ乳酸の製造過程において、反応時間5h、20h及び50h（反応終了時）の重量平均分子量を測定した結果を図１に示した。をした。さらに、以上の結果から、反応に使用した揮発性酸触媒のpKaと、得られたポリ乳酸の重量平均分子量との関係を図２に示した。 In addition, FIG. 1 shows the results of measuring the weight average molecular weights during the reaction times of 5 h, 20 h, and 50 h (at the end of the reaction) in the production process of polylactic acid shown in Examples 1 to 4 and Comparative Examples 1 and 2 above. It was. Did. Furthermore, from the above results, the relationship between the pKa of the volatile acid catalyst used in the reaction and the weight average molecular weight of the obtained polylactic acid is shown in FIG.
　表１、図１及び図２に示した結果から、pKaが-2.0～-1.7の範囲内である揮発性酸触媒の存在下で脱水重縮合反応を行った場合には、より高分子量の脂肪族ポリエステルを製造できることが明らかとなった。 From the results shown in Table 1, FIG. 1 and FIG. 2, when the dehydration polycondensation reaction is performed in the presence of a volatile acid catalyst having a pKa in the range of -2.0 to -1.7, a higher molecular weight fat is obtained. It became clear that a group polyester could be produced.
　一方、実施例１～３で製造したポリ乳酸（１）～（３）について、以下のように触媒残存率を算出した。すなわち、試料を９００℃に加熱灰化した際に発生するガスを、定容した吸収液に吸収させ、当該吸収液を用いたイオンクロマトグラフィー法によりガスを定量した。そして、イオンクロマトグラフィーで定量した硫黄濃度の分析値を各種スルホン酸系化合物に換算することで触媒残存率を算出した。また、ポリ乳酸（１）～（３）について目視により着色の有無について判定した。以上のようにして算出した触媒残存率及び着色度合いについて検討した結果を表２に示した。また、ポリ乳酸（１）及び（３）の着色度合いを図３に示した。なお、図３において（A）は揮発性酸触媒として２－ナフタレンスルホン酸を使用して製造したポリ乳酸（１）であり、（B）は揮発性酸触媒としてメシチレンスルホン酸を使用して製造したポリ乳酸（３）である。 On the other hand, for the polylactic acid (1) to (3) produced in Examples 1 to 3, the catalyst residual ratio was calculated as follows. That is, the gas generated when the sample was heated and incinerated at 900 ° C. was absorbed in a fixed volume of absorption liquid, and the gas was quantified by ion chromatography using the absorption liquid. And the catalyst residual rate was computed by converting the analytical value of the sulfur concentration quantified by the ion chromatography into various sulfonic acid type compounds. Further, the presence or absence of coloring of the polylactic acids (1) to (3) was determined visually. Table 2 shows the results of examining the remaining catalyst ratio and the degree of coloring calculated as described above. Moreover, the coloring degree of polylactic acid (1) and (3) was shown in FIG. In FIG. 3, (A) is polylactic acid (1) produced using 2-naphthalenesulfonic acid as a volatile acid catalyst, and (B) is produced using mesitylenesulfonic acid as a volatile acid catalyst. Polylactic acid (3).
Figure JPOXMLDOC01-appb-T000004
Figure JPOXMLDOC01-appb-T000004
　表２に示したように、揮発性酸触媒としてメシチレンスルホン酸を使用した場合には、触媒残存率が最も低い値となっていた。すなわち、揮発性酸触媒としてメシチレンスルホン酸を使用した場合には、より高品質な脂肪族ポリエステルを製造できることが明らかとなった。また、揮発性酸触媒としてメシチレンスルホン酸を使用した場合には、触媒使用量を低減させることができ（実施例４参照）、より低コストに脂肪族ポリエステルを製造できることが明らかとなった。 As shown in Table 2, when mesitylenesulfonic acid was used as the volatile acid catalyst, the catalyst remaining rate was the lowest value. That is, it has been clarified that when mesitylenesulfonic acid is used as the volatile acid catalyst, a higher quality aliphatic polyester can be produced. Moreover, when mesitylene sulfonic acid was used as a volatile acid catalyst, it was found that the amount of catalyst used can be reduced (see Example 4), and an aliphatic polyester can be produced at a lower cost.
　また、表２及び図３に示した結果から、揮発性酸触媒として２－ナフタレンスルホン酸を用いた場合には、殆ど着色が見られず、高品質な脂肪族ポリエステルを製造できることが明らかとなった。 Further, from the results shown in Table 2 and FIG. 3, it is clear that when 2-naphthalenesulfonic acid is used as the volatile acid catalyst, almost no coloring is observed and a high-quality aliphatic polyester can be produced. It was.
　さらに、ドデシルベンゼンスルホン酸は、その金属塩が合成洗剤等に非常に汎用されており、非常に安価な化合物である。したがって、揮発性酸触媒としてドデシルベンゼンスルホン酸を用いた場合には、脂肪族ポリエステルの製造コストを低く抑えることができる。 Furthermore, dodecylbenzene sulfonic acid is a very inexpensive compound whose metal salt is very widely used in synthetic detergents and the like. Therefore, when dodecylbenzenesulfonic acid is used as the volatile acid catalyst, the production cost of the aliphatic polyester can be kept low.
　本明細書で引用した全ての刊行物、特許および特許出願をそのまま参考として本明細書にとり入れるものとする。 All publications, patents and patent applications cited in this specification shall be incorporated into the present specification as they are.

Claims (6)

  1. 　脂肪族ポリエステルの製造方法であって、当該脂肪族ポリエステルを構成するモノマー若しくはオリゴマーを、pKaが-2.0～-1.7の範囲内である酸触媒下にて重合することを特徴とする脂肪族ポリエステルの製造方法。 A method for producing an aliphatic polyester, comprising: polymerizing a monomer or oligomer constituting the aliphatic polyester under an acid catalyst having a pKa in the range of -2.0 to -1.7. Production method.
  2. 　上記酸触媒のpKaが-1.85～-1.7の範囲内であることを特徴とする請求項１記載の脂肪族ポリエステルの製造方法。 The method for producing an aliphatic polyester according to claim 1, wherein the acid catalyst has a pKa in the range of -1.85 to -1.7.
  3. 　上記脂肪族ポリエステルとしてポリ乳酸を製造する際には、溶解度パラメータの値が21～25の範囲内である酸触媒を使用することを特徴とする請求項１記載の脂肪族ポリエステルの製造方法。 2. The method for producing an aliphatic polyester according to claim 1, wherein when the polylactic acid is produced as the aliphatic polyester, an acid catalyst having a solubility parameter value in the range of 21 to 25 is used.
  4. 　上記酸触媒は、ドデシルベンゼンスルホン酸、メチシレンスルホン酸及び２－ナフタレンスルホン酸からなる群から選ばれる少なくとも１種の化合物であることを特徴とする請求項１記載の脂肪族ポリエステルの製造方法。 The method for producing an aliphatic polyester according to claim 1, wherein the acid catalyst is at least one compound selected from the group consisting of dodecylbenzenesulfonic acid, methicylenesulfonic acid, and 2-naphthalenesulfonic acid.
  5. 　上記酸触媒は、２－ナフタレンスルホン酸であることを特徴とする請求項１記載の脂肪族ポリエステルの製造方法。 2. The method for producing an aliphatic polyester according to claim 1, wherein the acid catalyst is 2-naphthalenesulfonic acid.
  6. 　上記モノマーは、脂肪族ヒドロキシカルボン酸若しくは脂肪族ジオール及び脂肪族ジカルボン酸であることを特徴とする請求項１記載の脂肪族ポリエステルの製造方法。 2. The method for producing an aliphatic polyester according to claim 1, wherein the monomer is an aliphatic hydroxycarboxylic acid or an aliphatic diol and an aliphatic dicarboxylic acid.
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JP2000273165A (en) * 1999-01-22 2000-10-03 Mitsui Chemicals Inc Production of biodegradable aliphatic polyester
JP2001192446A (en) * 1999-10-27 2001-07-17 Mitsui Chemicals Inc Method for producing aliphatic polyester having excellent stability
JP2004307728A (en) * 2003-04-09 2004-11-04 Nippon Shokubai Co Ltd Method for producing glycolic acid oligomer
JP2007147981A (en) * 2005-11-28 2007-06-14 Fuji Xerox Co Ltd Method for manufacturing binder resin, resin particle dispersion and method for manufacturing same, electrostatic image developing toner and method for manufacturing same, electrostatic image developer, and image forming method
JP2009144132A (en) * 2007-07-09 2009-07-02 Toray Ind Inc Method for producing polylactic acid-based resin

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