JP2009144132A - Method for producing polylactic acid-based resin - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To efficiently produce a polylactic acid-based resin having a high molecular weight and a high melting point in a preferable embodiment and excellent in heat stability and color hue. <P>SOLUTION: The method for producing the polylactic acid-based resin is to directly polycondense lactic acid as a main raw material without a solvent and comprises the following 3 processes: (A) a first process for producing a low molecular weight material having <10,000 weight-average molecular weight under at least 3 conditions selected from the following conditions: (a-1) no catalyst, (a-2) a temperature of 100-180°C, (a-3) a pressure of 0.13-1,300 Pa and (a-4) a reaction time of 0.3-15 hours; (B) a second process for producing a prepolymer having >10,000 to <100,000 weight-average molecular weight in the presence of a catalyst; and (C) a third process for producing a polymer having ≥100,000 weight-average molecular weight by carrying out a solid phase polymerization under a temperature equal to or lower than the melting point of the prepolymer. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for efficiently producing a polylactic acid-based resin having a high molecular weight and, in a preferred embodiment, having a high melting point and excellent thermal stability and hue.

  In recent years, polylactic acid has attracted attention as a plant-derived carbon neutral material from the viewpoint of environmental conservation. Polylactic acid has a high melting point of about 170 ° C. and can be melt-molded. Furthermore, since lactic acid, which is a monomer, has been produced at low cost by fermentation using microorganisms, it is a general-purpose plastic derived from petroleum raw materials. It is expected to be used as a biomass plastic that can be used as an alternative, and is gradually being used.

  The main production methods of polylactic acid include a ring-opening polymerization method in which lactide which is a dimer of lactic acid is ring-opened and polymerized, and a direct polycondensation method in which dehydration polycondensation is performed using lactic acid. Compared with the ring-opening polymerization method, it is said that polylactic acid can be produced at low cost because lactic acid can be directly used as a polymerization raw material without passing through a step of synthesizing lactide.

Patent Documents 1 to 5 describe the direct polycondensation method. However, there are problems that the molecular weight is still low and mechanical properties such as strength cannot be satisfied, a problem that a solvent removal process is necessary due to the use of a solvent, a problem that a longer polymerization time and a further improvement in productivity are necessary. There was a desire to improve them.
JP-A-8-183840 (page 1-4) JP 2000-297145 A (pages 1-7) JP 2000-297143 A (page 1-9) JP-A-11-106499 (page 1-4) JP 2000-302852 A (page 1-4)

  An object of the present invention is to provide a method for efficiently producing a polylactic acid-based resin having a high molecular weight, having a high melting point, and excellent in thermal stability and hue.

  In order to solve the above-mentioned problems, the present invention has been studied mainly with respect to reaction conditions and catalysts. As a result, it has a high molecular weight, and in a preferred embodiment, has a high melting point, and is a polylactic acid system having excellent thermal stability and hue. The present inventors have found a method for efficiently producing a resin and have reached the present invention.

That is, the method for producing the polylactic acid resin of the present invention comprises:
(1) A method for producing a polylactic acid resin using lactic acid as a main raw material by direct polycondensation in the absence of a solvent, the method comprising the following three steps,
(A) A step of producing a low molecular weight product having a weight average molecular weight of less than 10,000 under the conditions of at least three or more selected from the following as the first step.
(A-1) Non-catalyst (a-2) Temperature of 100 to 180 ° C. (a-3) Pressure of 0.13 to 1300 Pa (a-4) Reaction time of 0.3 to 15 hours (B) Second step As a process for producing a prepolymer having a weight average molecular weight of more than 10,000 and less than 100,000 in the presence of a catalyst.
(C) As the third step, a step of producing a polymer having a weight average molecular weight of 100,000 or more by performing solid phase polymerization at a temperature not higher than the melting point of the prepolymer.
(2) The method for producing a polylactic acid resin according to (1), wherein the second step (B) is performed under the following conditions:
(B-1) 140 to 240 ° C temperature (b-2) 0.13 to 1300 Pa pressure (3) The third step (C) is performed under a temperature condition of 120 to 160 ° C. (1) The manufacturing method of the polylactic acid-type resin in any one of (2),
(4) Any of (1) to (3), wherein the crystallization treatment is performed at a temperature of 50 to 150 ° C. after the completion of the second step (B) and before the start of the third step (C). A method for producing the polylactic acid resin according to claim 1,
(5) Any one of (1) to (4), wherein a catalyst deactivator is added at any stage from the start of the first step (A) to the end of the third step (C). A method for producing the polylactic acid resin according to claim 1,
(6) In (A) 1st process and / or (B) 2nd process, the apparatus which connected the reaction tank and the recirculation | reflux apparatus is used, Any one of (1)-(5) characterized by the above-mentioned. Production method of polylactic acid resin,
(7) The polylactic acid system according to (6), wherein the reaction tank used in the (A) first step and / or (B) second step is composed of two or more reaction chambers. Resin production method,
(8) In any one or more steps selected from (A) the first step, (B) the second step, and (C) the third step, water is removed from the volatile component and generated. The polylactic acid according to any one of (1) to (7), wherein lactic acid and lactide or a low molecular weight polymer thereof is returned to the reaction tank of (A) the first step and / or (B) the second step. A method for producing a lactic acid resin,
(9) As the catalyst in the second step (B), any one selected from a tin compound, a titanium compound, a lead compound, a zinc compound, a cobalt compound, an iron compound, a lithium compound, a rare earth compound, and a sulfonic acid compound The method for producing a polylactic acid resin according to any one of (1) to (8), wherein the above is used,
(10) One or more types selected from tin compounds and / or one or more types selected from sulfonic acid compounds are used as the catalyst in the second step (B) (1) to (9) A process for producing a polylactic acid resin according to any one of
(11) The tin compound is tin (II) acetate and / or tin (II) octylate, and the sulfonic acid compound is selected from methanesulfonic acid, ethanesulfonic acid, propanedisulfonic acid, and naphthalenedisulfonic acid 1 or more types, The manufacturing method of the polylactic acid-type resin as described in (10) characterized by the above-mentioned,
(12) A resin composition comprising a polylactic acid resin obtained by the production method according to any one of (1) to (11),
(13) A molded article comprising the resin composition according to (12),
(14) One or more tin compounds selected from tin (II) acetate and tin (II) octylate and one or more sulfonic acids selected from methanesulfonic acid, ethanesulfonic acid, propanedisulfonic acid, and naphthalenedisulfonic acid A polylactic acid resin containing a compound,
It is.

  In a preferred embodiment, the polylactic acid resin having a high molecular weight, a high melting point, and excellent thermal stability and hue can be produced efficiently.

  Hereinafter, the present invention will be described in detail.

  In the present invention, the polylactic acid-based resin is a polymer having L-lactic acid and / or D-lactic acid as a main component. When L-lactic acid is a main component, it is called poly-L-lactic acid, and D -When lactic acid is a main component, it is called poly-D-lactic acid.

  When the polylactic acid resin is poly-L-lactic acid, it preferably contains 70 mol% or more of L-lactic acid units, more preferably contains 90 mol% or more, and contains 95 mol% or more. It is more preferable to contain 98 mol% or more.

  When the polylactic acid resin is poly-D-lactic acid, it preferably contains 70 mol% or more, more preferably 90 mol% or more, and more preferably 95 mol% or more D-lactic acid units. It is more preferable to contain 98 mol% or more.

  In this invention, the other component unit may be included in the range which does not impair the performance of the polylactic acid-type resin obtained by this invention. Examples of component units other than L-lactic acid or D-lactic acid units include polycarboxylic acids, polyhydric alcohols, hydroxycarboxylic acids, lactones, and the like. Specifically, succinic acid, adipic acid, sebacic acid, Polycarboxylic acids such as fumaric acid, terephthalic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid, 5-sodium sulfoisophthalic acid, 5-tetrabutylphosphonium sulfoisophthalic acid or their derivatives, ethylene glycol, propylene glycol, butane Diol, hexanediol, octanediol, neopentylglycol, glycerin, trimethylolpropane, pentaerythritol, trimethylolpropane, or polyhydric alcohol obtained by adding ethylene oxide or propylene oxide to pentaerythritol, Aromatic polyhydric alcohols obtained by addition reaction of phenol with ethylene oxide, polyhydric alcohols such as diethylene glycol, triethylene glycol, polyethylene glycol, polypropylene glycol or their derivatives, glycolic acid, 3-hydroxybutyric acid, 4-hydroxybutyric acid, 4 -Hydroxycarboxylic acids such as hydroxyvaleric acid, 6-hydroxycaproic acid, and glycolide, ε-caprolactone glycolide, ε-caprolactone, β-propiolactone, δ-butyrolactone, β- or γ-butyrolactone, pivalolactone, δ-valerolactone Examples include lactones such as lactones.

In the present invention, the method for producing a polylactic acid-based resin is a method for producing a polylactic acid-based resin by direct polycondensation in the absence of a solvent using lactic acid as a main raw material, which comprises the following three steps. This is a method for producing a polylactic acid resin.
(A) A step of producing a low molecular weight product having a weight average molecular weight of less than 10,000 under the conditions of at least three or more selected from the following as the first step.
(A-1) Non-catalyst (a-2) Temperature of 100 to 180 ° C. (a-3) Pressure of 0.13 to 1300 Pa (a-4) Reaction time of 0.3 to 15 hours (B) Second step As a process for producing a prepolymer having a weight average molecular weight of more than 10,000 and less than 100,000 in the presence of a catalyst.
(C) As the third step, a step of producing a polymer having a weight average molecular weight of 100,000 or more by performing solid phase polymerization at a temperature not higher than the melting point of the prepolymer.

First, the first step will be described. In the present invention, the first step (A) is a step of producing a low molecular weight product having a weight average molecular weight of less than 10,000 under at least three conditions selected from the following.
(A-1) Non-catalyst (a-2) Temperature of 100 to 180 ° C. (a-3) Pressure of 0.13 to 1300 Pa (a-4) Reaction time of 0.3 to 15 hours

  In the present invention, (A) the first step is preferably performed without a catalyst in that a polylactic acid-based resin having a high molecular weight and a high melting point can be obtained, and a catalyst is present in that the productivity is excellent. It is preferable to satisfy (a-2) to (a-4) below. The catalyst is preferably an acid catalyst, and particularly preferably a sulfonic acid compound. Moreover, the addition amount is preferably 0.001 to 2 parts by weight with respect to 100 parts by weight of the raw material to be used (L-lactic acid and / or D-lactic acid or the like).

  In the present invention, (A) the first step is carried out at a practical reaction temperature of 100 to 100 in that a polylactic acid resin having a high molecular weight and a high melting point and excellent in hue can be obtained efficiently. It is characterized by being carried out at a temperature of 180 ° C., and is preferably carried out at a temperature of 120 to 170 ° C. in that a polylactic acid resin having a high melting point and an excellent hue can be efficiently obtained. More preferably, the temperature is 140 to 160 ° C. Further, the temperature of the first step (A) may be one step or may be two or more stages, but it is preferably two or more stages in terms of achieving a high melting point. Examples include a method of reacting at a temperature of 140 to 180 ° C. after performing the reaction at a temperature of ˜140 ° C.

  In the present invention, (A) the first step is carried out at a pressure of 0.13 to 1300 Pa as a substantial reaction pressure in that a polylactic acid resin having a high molecular weight can be obtained efficiently. It is characterized in that a polylactic acid resin excellent in hue can be obtained efficiently, preferably at a pressure of 1-1000 Pa, more preferably at a pressure of 10-900 Pa, more preferably 100-800 Pa. More preferably, it is performed at a pressure of 500 to 700 Pa. In addition, (A) the pressure in the first step may be one step or may be two or more steps, but it is preferably two or more steps in terms of high molecular weight and excellent hue. For example, after reacting at the pressure of 700-1300 Pa, the method of reacting at the pressure of 0.13-700 Pa is mentioned.

  In the present invention, (A) the first step is 0.3 to 15 in that a polylactic acid resin having a high molecular weight and a high melting point and having excellent thermal stability and hue can be obtained efficiently. It is characterized in that it is performed for a reaction time of time, and it is preferably performed for a reaction time of 1 to 10 hours, in that a polylactic acid resin excellent in hue can be efficiently obtained, and 2 to 8 hours More preferably, the reaction time is 3 to 6 hours. Moreover, (A) When performing the temperature and pressure of a 1st process in two or more steps | paragraphs, for example, it is the temperature of 100-140 degreeC, the pressure of 700-1300 Pa, and reaction time of 0.3 to 10 hours. Examples include a method in which the reaction is performed at a temperature of 140 to 180 ° C. and a pressure of 0.13 to 700 Pa and a reaction time of 0.3 to 10 hours after the reaction. In addition, even if it is a case where temperature and a pressure are performed in multiple steps of two steps or more, the total of the reaction time of (A) 1st process is 0.3 to 15 hours.

  (A) The first step may be a batch method or a continuous method, but in the case of a batch grammar, the time required to reach the substantial reaction temperature shown in (a-2) from room temperature is within 30% of the process time. Preferably, it is within 20%, more preferably within 10%. Further, the time required to reach the substantial reaction pressure shown in (a-3) from normal pressure is preferably within 50% of the process time, more preferably within 40%, and more preferably within 30%. More preferably.

  In the present invention, the first step (A) is characterized by producing a low molecular weight material having a weight average molecular weight of less than 10,000, and a polylactic acid resin having a high molecular weight and a high melting point can be obtained efficiently. Therefore, it is preferable to produce a low molecular weight body having a weight average molecular weight of 1000 to 8000, more preferably a low molecular weight body having a weight average molecular weight of 1200 to 6000, and a low molecular weight body having a weight average molecular weight of 1500 to 5000. More preferably, it is manufactured. The weight average molecular weight is a value of weight average molecular weight in terms of standard polymethyl methacrylate as measured by gel permeation chromatography (GPC) using hexafluoroisopropanol as a solvent.

  In the present invention, the (A) first step may be a batch method or a continuous method, and the reaction vessel is not particularly limited. For example, a stirring vessel type reaction vessel, a mixer type reaction vessel, a tower type reaction vessel. Further, an extruder type reaction vessel or the like can be used, and these reaction vessels can be used in combination of two or more.

  In the present invention, (A) the first step can use any reaction apparatus, but efficiently obtains a polylactic acid resin having a high molecular weight and a high melting point and excellent in thermal stability and hue. It is preferable to use an apparatus in which a reaction vessel and a reflux apparatus are connected in that they can be used.

  In the present invention, the reaction vessel may have one reaction chamber or may be composed of two or more reaction chambers divided by a partition plate or the like, but a polylactic acid resin having a high molecular weight is efficiently used. It is preferable that the reaction chamber is composed of two or more reaction chambers.

  In the present invention, the reflux device is preferably connected to the upper part of the reaction vessel, and more preferably a vacuum pump is connected to the reflux device. In the present invention, the reflux device is for separating volatile components, and works to remove a part of the volatile components from the reaction system and a part of the volatile components to return to the reaction system. Any of those having a condensing part having a water content may be used. Specifically, water is removed from volatile components, and lactic acid and lactide or their low molecular weight polymers are converted into (A) the first step and / or ( B) Any material can be used as long as it is returned to the reaction tank in the second step. Here, as a condenser which comprises a condensation part, methods, such as a double tube type, a multi-tube type, a coil type, a plate type, a plate fin type, a spiral type, and a jacket type, can be mentioned, for example. In the present invention, in order to efficiently return lactic acid and lactide or their low molecular weight polymer to the reaction vessel, the condenser temperature may be set to be equal to or higher than the melting point of lactic acid and lactide or their low molecular weight polymer. Preferably, it is 90 degreeC or more, It is more preferable that it is 100-160 degreeC, It is especially preferable that it is 105-140 degreeC.

  In the first step (A) of the present invention, the inside of the reaction system is preferably as dry as possible, and the L-lactic acid as a raw material is dried or reacted in an inert gas atmosphere such as dry nitrogen. It is effective to increase the molecular weight of the finally obtained polylactic acid resin.

  In the first step (A) of the present invention, the method of taking out the produced low molecular weight substance from the reaction tank after completion of the reaction is not particularly limited, and a method of taking out by extrusion with an inert gas such as nitrogen, a gear pump, etc. The method of taking out by an inert gas, such as nitrogen, is preferable from the point of the handleability of the low molecular weight body which is low viscosity.

  Next, the second step will be described. In the present invention, the (B) second step is a step of producing a prepolymer having a weight average molecular weight of more than 10,000 and less than 100,000 in the presence of a catalyst.

  Here, examples of the catalyst include a metal catalyst and an acid catalyst. Examples of the metal catalyst include tin compounds, titanium compounds, lead compounds, zinc compounds, cobalt compounds, iron compounds, lithium compounds, rare earth compounds, and the types of compounds include metal alkoxides, metal halogen compounds, and organic carboxylates. Carbonate, sulfate, oxide and the like are preferable. Specifically, tin powder, tin (II) chloride, tin (IV) chloride, tin (II) bromide, tin (IV) bromide, ethoxy tin (II), t-butoxy tin (IV), isopropoxy Tin (IV), tin acetate (II), tin acetate (IV), tin octylate (II), tin (II) laurate, tin (II) myristate, tin (II) palmitate, tin stearate (II) ), Tin (II) oleate, tin (II) linoleate, tin (II) acetylacetone, tin (II) oxalate, tin (II) lactate, tin (II) tartrate, tin (II) pyrophosphate, p- Phenol sulfonate tin (II), bis (methane sulfonate) tin (II), tin sulfate (II), tin oxide (II), tin oxide (IV), tin sulfide (II), tin sulfide (IV), oxidation Dimethyltin (IV), methylphenyltin (IV) oxide, dibutyltin (IV) oxide, dioctyltin (IV) oxide, diphenyltin (IV) oxide, tributyltin oxide, triethyltin hydroxide (IV) , Triphenyltin hydroxide (IV), tributyltin hydride, monobutyltin (IV) oxide, tetramethyltin (IV), tetraethyltin (IV), tetrabutyltin (IV), dibutyldiphenyltin (IV), tetraphenyl Tin (IV), tributyltin acetate (IV), triisobutyltin acetate (IV), triphenyltin acetate (IV), dibutyltin diacetate, dibutyltin dioctanoate, dibutyltin dilaurate (IV), dibutyltin maleate (IV), dibutyltin bis (acetylacetonate), tributyltin chloride (IV), dibutyltin dichloride, monobutyltin trichloride, dioctyltin dichloride, triphenyltin chloride (IV), tributyltin sulfide, tributyltin sulfate , Tin (II) trifluoromethanesulfonate, ammonium hexachlorotin (IV), dibutyltin sulfide, diphenyltin sulfide, triethyltin sulfate Tin compounds such as fine phthalocyanine tin (II), and among them, a tin compound other than tin (II) chloride are preferred. Also, titanium methoxide, titanium propoxide, titanium isopropoxide, titanium butoxide, titanium isobutoxide, titanium cyclohexyl, titanium phenoxide, titanium chloride, titanium diacetate, titanium triacetate, titanium tetraacetate, titanium (IV) oxide, etc. Titanium compounds, lead diisopropoxy (II), lead monochloride, lead acetate, lead (II) octylate, lead (II) isooctanoate, lead (II) isononanoate, lead (II) laurate, lead oleate (II), lead compounds such as lead (II) linoleate, lead naphthenate, lead (II) neodecanoate, lead oxide, lead (II) sulfate, zinc powder, methyl propoxy zinc, zinc chloride, zinc acetate, octylic acid Zinc (II), zinc naphthenate, zinc carbonate, zinc oxide, zinc sulfate and other zinc compounds, cobalt chloride, cobalt acetate, octi Cobalt (II) phosphate, cobalt (II) isooctanoate (II), isononanoate (II), cobalt laurate (II), cobalt oleate (II), cobalt linoleate (II), cobalt naphthenate, cobalt neodecanoate ( II), cobalt compounds such as cobaltous carbonate, cobaltous sulfate, cobalt oxide (II), iron chloride (II), iron acetate (II), iron octylate (II), iron naphthenate, iron carbonate (II) ), Iron compounds such as iron (II) sulfate, iron (II) oxide, lithium compounds such as propoxylithium, lithium chloride, lithium acetate, lithium octylate, lithium naphthenate, lithium carbonate, dilithium sulfate, lithium oxide, triiso Propoxy europium (III), triisopropoxyneodymium (III), triisopropoxylantan, triisopropoxysamarium (III ), Triisopropoxy yttrium, isopropoxy yttrium, dysprosium chloride, europium chloride, lanthanum chloride, neodymium chloride, samarium chloride, yttrium chloride, dysprosium triacetate (III), europium triacetate (III), lanthanum acetate, neodymium triacetate, Samarium acetate, yttrium triacetate, dysprosium carbonate (III), dysprosium carbonate (IV), europium carbonate (II), lanthanum carbonate, neodymium carbonate, samarium carbonate (II), samarium carbonate (III), yttrium carbonate, dysprosium sulfate, sulfuric acid Examples include rare earth compounds such as europium (II), lanthanum sulfate, neodymium sulfate, samarium sulfate, yttrium sulfate, europium dioxide, lanthanum oxide, neodymium oxide, samarium (III) oxide, yttrium oxide. . Other potassium compounds such as potassium isopropoxide, potassium chloride, potassium acetate, potassium octylate, potassium naphthenate, tert-butyl potassium carbonate, potassium sulfate, potassium oxide, copper (II) diisopropoxide, copper chloride (II), copper acetate (II), copper octylate, copper naphthenate, copper sulfate (II), copper compounds such as dicopper carbonate, nickel chloride, nickel acetate, nickel octylate, nickel carbonate, nickel sulfate (II) , Nickel compounds such as nickel oxide, tetraisopropoxyzirconium (IV), zirconium trichloride, zirconium acetate, zirconium octylate, zirconium naphthenate, zirconium carbonate (II), zirconium carbonate (IV), zirconium sulfate, zirconium oxide (II ) Zirconium compounds such as triisopropoxy Antimony compounds such as antimony, antimony fluoride (III), antimony fluoride (V), antimony acetate, antimony (III) oxide, magnesium, magnesium diisopropoxide, magnesium chloride, magnesium acetate, magnesium lactate, magnesium carbonate, sulfuric acid Magnesium compounds such as magnesium and magnesium oxide, calcium compounds such as diisopropoxy calcium, calcium chloride, calcium acetate, calcium octylate, calcium naphthenate, calcium lactate and calcium sulfate, aluminum, aluminum isopropoxide, aluminum chloride, aluminum acetate , Aluminum compounds such as aluminum octylate, aluminum sulfate, aluminum oxide, germanium, tetraisopropoxygermane, germanium oxide Germanium compounds such as nium (IV), triisopropoxymanganese (III), manganese trichloride, manganese acetate, manganese octylate (II), manganese naphthenate (II), manganese compounds such as manganous sulfate, bismuth chloride ( III), bismuth powder, bismuth oxide (III), bismuth acetate, bismuth octylate, bismuth neodecanoate, and the like. Also, sodium stannate, magnesium stannate, potassium stannate, calcium stannate, manganese stannate, bismuth stannate, barium stannate, strontium stannate, sodium titanate, magnesium titanate, aluminum titanate, potassium titanate, Compounds composed of two or more metal elements such as calcium titanate, cobalt titanate, zinc titanate, manganese titanate, zirconium titanate, bismuth titanate, barium titanate and strontium titanate are also preferred. The acid catalyst may be a Bronsted acid as a proton donor, a Lewis acid as an electron pair acceptor, or an organic acid or an inorganic acid. For example, monocarboxylic acid compounds such as formic acid, acetic acid, propionic acid, heptanoic acid, octanoic acid, octylic acid, nonanoic acid, isononanoic acid, trifluoroacetic acid and trichloroacetic acid, oxalic acid, succinic acid, maleic acid, tartaric acid and malonic acid Dicarboxylic acid compounds such as citric acid and tricarballylic acid, benzenesulfonic acid, n-butylbenzenesulfonic acid, n-octylbenzenesulfonic acid, n-dodecylbenzenesulfonic acid, pentadecylbenzenesulfonic acid, 2 , 5-dimethylbenzenesulfonic acid, 2,5-dibutylbenzenesulfonic acid, o-aminobenzenesulfonic acid, m-aminobenzenesulfonic acid, p-aminobenzenesulfonic acid, 3-amino-4-hydroxybenzenesulfonic acid, 5 -Amino-2-me Rubenzenesulfonic acid, 3,5-diamino-2,4,6-trimethylbenzenesulfonic acid, 2,4-dinitrobenzenesulfonic acid, p-chlorobenzenesulfonic acid, 2,5-dichlorobenzenesulfonic acid, p-phenol Sulfonic acid, cumene sulfonic acid, xylene sulfonic acid, o-cresol sulfonic acid, m-cresol sulfonic acid, p-cresol sulfonic acid, p-toluene sulfonic acid, 2-naphthalene sulfonic acid, 1-naphthalene sulfonic acid, isopropyl naphthalene sulfone Acid, dodecylnaphthalenesulfonic acid, dinonylnaphthalenesulfonic acid, dinonylnaphthalenedisulfonic acid, 1,5-naphthalenedisulfonic acid, 2,7-naphthalenedisulfonic acid, 4,4-biphenyldisulfonic acid, anthraquinone-2-sulfonic acid, m-ben Aromatic sulfonic acid such as sulfonic acid, 2,5-diamino-1,3-benzenedisulfonic acid, aniline-2,4-disulfonic acid, anthraquinone-1,5-disulfonic acid, polystyrene sulfonic acid, methanesulfonic acid, ethane Aliphatic sulfones such as sulfonic acid, 1-propanesulfonic acid, n-octylsulfonic acid, pentadecylsulfonic acid, trifluoromethanesulfonic acid, trichloromethanesulfonic acid, 1,2-ethanedisulfonic acid, 1,3-propanedisulfonic acid Acid, cyclopentane sulfonic acid, sulfonic acid compounds such as cyclohexane sulfonic acid and camphor sulfonic acid, etc., acidic amino acids such as aspartic acid and glutamic acid, ascorbic acid, retinoic acid, phosphoric acid, metaphosphoric acid, phosphorous acid Acid, hypophosphorous acid Phosphoric acid compounds such as acids, polyphosphoric acid, phosphoric acid monoesters such as monododecyl phosphate and monooctadecyl phosphate, phosphoric acid diesters such as didodecyl phosphate and dioctadecyl phosphate, phosphorous acid monoesters and phosphorous acid diesters , Boric acid, hydrochloric acid, sulfuric acid and the like. Further, the shape of the acid catalyst is not particularly limited, and any of a solid acid catalyst and a liquid acid catalyst may be used. For example, as the solid acid catalyst, acidic clay, kaolinite, bentonite, montmorillonite, talc, zirconium silicate and Natural minerals such as zeolite, oxides such as silica, alumina, titania and zirconia or oxide composites such as silica alumina, silica magnesia, silica boria, alumina boria, silica titania and silica zirconia, chlorinated alumina, fluorinated alumina, positive Examples thereof include ion exchange resins. In the case where polymerization is carried out using a racemic compound, which is an equal mixture of L-lactic acid and D-lactic acid, using a catalyst having stereoselective polymerizability, poly-L-lactic acid and poly-D-lactic acid are used. Can be manufactured simultaneously.

  In the present invention, a tin compound, a titanium compound, a lead compound, a zinc compound, a cobalt compound, an iron compound, a lithium compound, a rare earth compound, an antimony compound, in that a polylactic acid resin having a high molecular weight and a high melting point can be obtained. , Bismuth compounds, acid catalysts are preferred, and tin compounds, titanium compounds, lead compounds, zinc compounds, cobalt compounds, iron compounds, lithium compounds, rare earth compounds, sulfonic acid compounds, and phosphorus compounds are more preferred in terms of excellent productivity. More preferred are tin compounds, titanium compounds, rare earth compounds, sulfonic acid compounds, and phosphorus compounds. In addition, a tin-based organic carboxylate having two ligands is preferable as the metal catalyst in that a polylactic acid resin excellent in thermal stability and hue can be obtained, and tin acetate (II ) Or tin (II) octylate is particularly preferred, and as the acid catalyst, monosulfonic acid or disulfonic acid is preferred, and methanesulfonic acid, ethanesulfonic acid, p-toluenesulfonic acid, propanedisulfonic acid, and naphthalenedisulfonic acid are particularly preferred. preferable. Further, the catalyst may be used alone or in combination of two or more. In view of obtaining a polylactic acid resin having a high molecular weight or a high melting point and particularly excellent in heat stability, it is preferable to use one kind of disulfonic acid, and particularly preferred is propanedisulfonic acid or naphthalene disulfonic acid. . Moreover, it is preferable to use 2 or more types together in terms of efficiently obtaining a polylactic acid resin having a high molecular weight and a high melting point, and 1 type selected from tin compounds in terms of excellent productivity. It is more preferable to use one or more selected from the above and sulfonic acid compounds, and tin (II) acetate and / or octylic acid can be obtained in that a polylactic acid resin excellent in thermal stability and hue can be obtained. More preferably, tin (II) and at least one selected from methanesulfonic acid, ethanesulfonic acid, propanedisulfonic acid, and naphthalenedisulfonic acid are used, and tin (II) acetate and / or tin octylate ( Particular preference is given to using II) and methanesulfonic acid and / or propanedisulfonic acid.

  In the present invention, the amount of the catalyst used in the second step (B) is such that a polylactic acid resin having a high molecular weight and a high melting point can be efficiently obtained (L-lactic acid and / or Or 0.001 to 2 parts by weight, preferably 0.001 to 1 part by weight per 100 parts by weight of D-lactic acid or the like) to obtain a polylactic acid resin excellent in thermal stability and hue. In terms of being able to be performed, 0.001 to 0.5 parts by weight is further preferable, and 0.01 to 0.3 parts by weight is particularly preferable. When two or more types of catalysts are used in combination, the total addition amount is preferably within the above range, and is selected from one or more types selected from tin compounds other than stannous chloride and / or sulfonic acid compounds. When one or more types are used in combination, the weight ratio of the tin compound and the sulfonic acid compound is 1: 1 to 1:30 in that high polymerization activity can be maintained and coloring can be suppressed. It is preferable that the ratio is 1: 2 to 1:15 in terms of excellent productivity.

  In the present invention, (B) the second step is characterized in that a prepolymer having a weight average molecular weight of more than 10,000 and less than 100,000 is produced. It is possible to efficiently obtain a polylactic acid resin having a high molecular weight. It is preferable to produce a prepolymer having a weight average molecular weight of 20,000 to 90,000, more preferably a prepolymer having a weight average molecular weight of 25,000 to 80,000, and a weight average molecular weight of 30,000 to It is more preferable to produce a 70,000 prepolymer, and it is particularly preferred to produce a prepolymer having a weight average molecular weight of 35,000 to 65,000. The weight average molecular weight is a value of weight average molecular weight in terms of standard polymethyl methacrylate as measured by gel permeation chromatography (GPC) using hexafluoroisopropanol as a solvent.

  In the present invention, (B) the second step is preferably performed at a temperature of 140 to 240 ° C. as a substantial reaction temperature in that a polylactic acid resin having a high molecular weight can be obtained efficiently. It is preferably performed at a temperature of 150 to 210 ° C., more preferably 160 to 195 ° C. in that a polylactic acid resin having a high melting point and excellent hue can be efficiently obtained. preferable. In addition, the temperature of the (B) second step may be one step or may be two or more steps, but a polylactic acid resin having a high molecular weight and a high melting point can be efficiently obtained. It is preferable to use two or more stages, for example, a method in which the reaction is performed at a temperature of 140 to 160 ° C and then the reaction is performed at a temperature of 160 to 240 ° C.

  In the present invention, (B) the second step can be carried out at a pressure of 0.13 to 1300 Pa as a substantial reaction pressure in that a polylactic acid resin having a high molecular weight can be obtained efficiently. Preferably, it is preferably performed at a pressure of 1 to 1000 Pa, more preferably 10 to 900 Pa, and a pressure of 100 to 800 Pa in that a polylactic acid resin excellent in hue can be efficiently obtained. It is more preferable to carry out at a pressure of 200 to 700 Pa. (B) The pressure in the second step may be one step or may be two or more steps, but it is preferably two or more steps in terms of high molecular weight and excellent hue. For example, after reacting at the pressure of 700-1300 Pa, the method of reacting at the pressure of 0.13-700 Pa is mentioned.

  In the present invention, (B) the second step is preferably performed with a reaction time of 0.5 to 30 hours in that a polylactic acid resin having a high molecular weight and a high melting point can be obtained efficiently. In terms of efficiently obtaining a polylactic acid resin excellent in hue, the reaction time is preferably 1 to 15 hours, more preferably 2 to 10 hours, and more preferably 3 to 8 hours. It is more preferable to carry out with the reaction time of time, and it is especially preferable to carry out with the reaction time of 3.5 to 7 hours. Moreover, (B) When performing the temperature and pressure of a 2nd process in multiple steps of two or more steps, for example, it is the temperature of 140-160 degreeC, the pressure of 700-1300 Pa, and reaction time of 0.3 to 15 hours. Examples include a method in which the reaction is performed at a temperature of 160 to 240 ° C. and a pressure of 0.13 to 700 Pa and a reaction time of 0.3 to 15 hours after the reaction. In addition, even if it is a case where it carries out in multiple steps | paragraphs of temperature and pressure in two steps or more, the sum total of the reaction time of (B) 2nd process is 0.5 to 30 hours.

  (B) The second step may be a batch method or a continuous method, but in the case of a batch grammar, the time required to reach the substantial reaction temperature shown in (b-1) from room temperature is within 30% of the process time. Preferably, it is within 20%, more preferably within 10%. Further, the time required to reach the substantial reaction pressure shown in (b-2) from normal pressure is preferably within 50% of the process time, more preferably within 40%, and more preferably within 30%. More preferably.

  In the present invention, the second step (B) may be a batch method or a continuous method, and the reaction vessel is not particularly limited. For example, a stirring vessel type reaction vessel, a mixer type reaction vessel, a tower type reaction vessel. Further, an extruder type reaction vessel or the like can be used, and these reaction vessels can be used in combination of two or more.

  In the present invention, (B) the second step can use any reaction apparatus, but efficiently obtains a polylactic acid resin having a high molecular weight and a high melting point, and excellent in thermal stability and hue. It is preferable to use an apparatus in which a reaction vessel and a reflux apparatus are connected in that they can be used.

  In the present invention, the reaction vessel may have one reaction chamber or may be composed of two or more reaction chambers divided by a partition plate or the like, but a polylactic acid resin having a high molecular weight is efficiently used. It is preferable that the reaction chamber is composed of two or more reaction chambers.

  In the present invention, the reflux device is preferably connected to the upper part of the reaction vessel, and more preferably a vacuum pump is connected to the reflux device. In the present invention, the reflux device is for separating volatile components, and works to remove a part of the volatile components from the reaction system and a part of the volatile components to return to the reaction system. Any of those having a condensing part having a water content may be used. Specifically, water is removed from volatile components, and lactic acid and lactide or their low molecular weight polymers are converted into (A) the first step and / or ( B) Any material can be used as long as it is returned to the reaction tank in the second step. Here, as a condenser which comprises a condensation part, methods, such as a double tube type, a multi-tube type, a coil type, a plate type, a plate fin type, a spiral type, and a jacket type, can be mentioned, for example. In the present invention, in order to efficiently return lactic acid and lactide or their low molecular weight polymer to the reaction vessel, the condenser temperature may be set to be equal to or higher than the melting point of lactic acid and lactide or their low molecular weight polymer. Preferably, it is 90 degreeC or more, It is more preferable that it is 100-160 degreeC, It is especially preferable that it is 105-140 degreeC.

  In the second step (B) of the present invention, the inside of the reaction system is preferably made as dry as possible, and the polylactic acid system finally obtained is that the reaction is performed in an inert gas atmosphere such as dry nitrogen. It is effective for increasing the molecular weight of the resin.

  In the second step (B) of the present invention, the method of taking out the produced low molecular weight substance from the reaction vessel after completion of the reaction is not particularly limited, and a method of taking out by extrusion with an inert gas such as nitrogen, a gear pump, etc. The method of taking out by an inert gas, such as nitrogen, is preferable from the point of the handleability of the low molecular weight body which is low viscosity.

  Next, the third step will be described. In the present invention, the (C) third step is a step of producing a polymer having a weight average molecular weight of 100,000 or more by performing solid phase polymerization at a temperature below the melting point of the prepolymer.

  In the present invention, (C) the third step is characterized in that it is carried out at a temperature below the melting point of the prepolymer, and it is possible to efficiently obtain a polylactic acid resin having a high molecular weight and a high melting point and excellent in hue. It is preferable to carry out at a temperature of 120 to 160 ° C, more preferably at a temperature of 140 to 160 ° C, and further preferably at a temperature of 145 to 155 ° C. (C) The temperature of the third step may be one step or may be two or more steps, but it is easy to increase the molecular weight in a short time and is excellent in hue. It is preferable to increase the temperature step by step as the reaction proceeds. For example, there may be mentioned a method in which the reaction is performed at a temperature of 120 to 140 ° C. and then the reaction is performed at a temperature of 140 to 160 ° C. .

  In the present invention, (C) the third step is performed for 1 to 100 hours in that a polylactic acid-based resin having a high molecular weight and a high melting point and excellent in thermal stability and hue can be obtained efficiently. The reaction is preferably performed for a reaction time, and is preferably performed for a reaction time of 3 to 80 hours, and is preferably performed for a reaction time of 5 to 50 hours, from the viewpoint that a polylactic acid resin excellent in hue can be efficiently obtained. It is more preferable that the reaction time is 10 to 30 hours.

  Moreover, (C) When performing the temperature of 3rd process in two or more steps | paragraphs, for example, the temperature of 120-140 degreeC is used as the 1st stage for 1 to 50 hours, and the temperature of 140-160 degreeC is used as the 2nd stage. 1 to 50 hours, and it is easy to increase the molecular weight in a short time and is excellent in hue, so that the first stage is at a temperature of 120 to 140 ° C. for 5 to 20 hours and the second stage is 140 to 140 hours. More preferably, it is carried out at a temperature of 150 ° C. for 5 to 20 hours, and as a third stage at a temperature of 150 to 160 ° C. for 10 to 30 hours. In addition, even if it is a case where temperature is performed by the multistage of 2 steps or more, the total of the reaction time of (C) 3rd process is 1 to 100 hours.

  In the present invention, in the third step (C), the pressure condition is not particularly limited, and any of a reduced pressure condition, a normal pressure condition and a pressurized condition may be used, but a polylactic acid resin having a high molecular weight is efficiently used. It is preferable that it is a pressure reduction condition or a normal-pressure condition at the point which can be obtained. When performed under reduced pressure conditions, it is preferably performed at a pressure of 0.13 to 1300 Pa. In addition, it is preferably performed at a pressure of 1 to 1000 Pa, more preferably a pressure of 10 to 900 Pa, and a pressure of 100 to 800 Pa in that a polylactic acid resin excellent in hue can be efficiently obtained. It is more preferable to carry out at a pressure of 500 to 700 Pa. (C) The pressure in the third step may be one step or two or more steps, but it is preferably two or more steps in terms of high molecular weight and excellent hue. For example, after reacting at the pressure of 700-1300 Pa, the method of reacting at the pressure of 0.13-700 Pa is mentioned. When it is carried out under normal pressure conditions, it is preferably carried out under an inert gas stream such as dry nitrogen.

  In the present invention, when the (C) third step is carried out, the shape of the prepolymer is not particularly limited, and any shape such as a lump, a film, a pellet and a powder may be used. It is preferable to use pellets or powder in that it can proceed to the next step. As a method for forming pellets, a melted prepolymer is extruded into strands, pelletized with a strand cutter, dropped into droplets using a dropping nozzle, and contacted with a gas or liquid to form pellets Etc. Moreover, as a method of making into powder, the method of grind | pulverizing using a mixer, a blender, a ball mill, and a hammer grinder is mentioned. In the case of powder, the average particle diameter is preferably 0.01 to 3 mm, more preferably 0.1 to 1 mm, from the viewpoint that solid-phase polymerization can be efficiently performed.

  In the present invention, the (C) third step may be a batch process or a continuous process, and the reaction tank may be a stirred tank reaction tank, a mixer reaction tank, a tower reaction tank, or the like. Two or more reaction vessels can be used in combination.

  In the present invention, in the third step (C), the volatile component is separated, and a vaporizing portion having a function of removing a part of the volatile component outside the reaction system and a part of the volatile component being returned to the reaction system. It is preferable to use an apparatus having a condensing part. Specifically, water is removed from the volatile components, and lactic acid and lactide or their low molecular weight polymers are (A) the first step and / or (B) the first. Any device can be used as long as it is returned to the two-step reaction tank. Here, as a condenser which comprises a condensation part, methods, such as a double tube type, a multi-tube type, a coil type, a plate type, a plate fin type, a spiral type, and a jacket type, can be mentioned, for example. In the present invention, in order to efficiently return lactic acid and lactide or their low molecular weight polymer to the reaction vessel, the condenser temperature may be set to be equal to or higher than the melting point of lactic acid and lactide or their low molecular weight polymer. Preferably, it is 90 degreeC or more, It is more preferable that it is 100-160 degreeC, It is especially preferable that it is 105-140 degreeC.

  The weight average molecular weight of the polylactic acid resin obtained by the method of the present invention is not particularly limited, but is preferably 100,000 or more in view of mechanical properties. In particular, it is preferably 100,000 to 1,200,000, more preferably 120,000 to 300,000, and even more preferably 140,000 to 250,000 in terms of excellent moldability and mechanical properties. The weight average molecular weight is a value of weight average molecular weight in terms of standard polymethyl methacrylate as measured by gel permeation chromatography (GPC) using hexafluoroisopropanol as a solvent.

  In the present invention, when the (C) third step is performed, the prepolymer is preferably crystallized, and (B) the crystallization treatment is performed after the second step and (C) before the third step. More preferably.

  The method for crystallization is not particularly limited, and a known method can be used. For example, a method of treating at a crystallization temperature in a gas phase or a liquid phase, a method of volatilizing a solvent after dissolving the prepolymer in a solvent, a method of bringing the prepolymer into contact with the solvent, and a molten prepolymer Examples of the method include cooling and solidifying while performing stretching or shearing operations. From the viewpoint of easy operation, a method of treating at a crystallization temperature in a gas phase or a liquid phase is preferable.

  The crystallization temperature here is not particularly limited as long as it is higher than the glass transition temperature of the prepolymer that can be obtained in the second step (B) and lower than the melting point. It is more preferable that the temperature is within the range of the temperature-rise crystallization temperature and the temperature-fall crystallization temperature measured by a type calorimeter (DSC), and a polylactic acid resin having a high molecular weight and a high melting point and excellent in hue is efficiently obtained. It is more preferable that it is 30-170 degreeC at the point that it can be performed, It is especially preferable that it is 50-150 degreeC, It is most preferable that it is 100-140 degreeC.

  Further, the time for crystallization is not particularly limited, but it is sufficiently crystallized within 3 hours, and preferably within 2 hours. The pressure condition in the crystallization process may be any of reduced pressure, normal pressure and increased pressure.

  In the present invention, the shape of the prepolymer at the time of crystallization treatment is not particularly limited, and any of a lump, a film, a pellet, and a powder may be used, but the pellet or the powder can be efficiently crystallized. Is preferably used. As a method for forming pellets, a melted prepolymer is extruded into strands, pelletized with a strand cutter, dropped into droplets using a dropping nozzle, and contacted with a gas or liquid to form pellets Etc. Moreover, as a method of making into powder, the method of grind | pulverizing using a mixer, a blender, a ball mill, and a hammer grinder is mentioned. In the case of powder, the average particle diameter is preferably 0.01 to 3 mm, more preferably 0.1 to 1 mm, in that it can be efficiently crystallized.

  In the present invention, it is preferable to add a catalyst deactivator at any stage from the start of the first step (A) to the end of the third step (C) in terms of excellent thermal stability. When the polymerization catalyst remains, the polylactic acid-based resin may be thermally decomposed during melt kneading and melt molding by the remaining catalyst, and by adding a catalyst deactivator, thermal decomposition can be suppressed, Stability can be improved.

  Examples of the catalyst deactivator in the present invention include hindered phenol compounds, thioether compounds, vitamin compounds, triazole compounds, polyvalent amine compounds, hydrazine derivative compounds, phosphorus compounds, and the like. You may use together. Among them, it is preferable to include at least one phosphorus compound, and it is more preferable to use a phosphate compound or a phosphite compound. As further preferred examples of specific examples, “ADEKA STAB” AX-71 (dioctadecyl phosphate), PEP-8 (distearyl pentaerythritol diphosphite), PEP-36 (cyclic neopentatetrayl bis (2,6) manufactured by ADEKA) -T-butyl-4-methylphenyl) phosphite).

  Specific examples of the hindered phenol compound include n-octadecyl-3- (3 ′, 5′-di-t-butyl-4′-hydroxyphenyl) -propionate, n-octadecyl-3- (3′-methyl). -5'-t-butyl-4'-hydroxyphenyl) -propionate, n-tetradecyl-3- (3 ', 5'-di-t-butyl-4'-hydroxyphenyl) -propionate, 1,6-hexane Diol-bis- [3- (3,5-di-t-butyl-4-hydroxyphenyl) -propionate], 1,4-butanediol-bis- [3- (3,5-di-t-butyl- 4-hydroxyphenyl) -propionate], 2,2′-methylenebis- (4-methyl-t-butylphenol), triethylene glycol-bis- [3- (3-t-butyl) 5-methyl-4-hydroxyphenyl) -propionate], tetrakis [methylene-3- (3 ′, 5′-di-t-butyl-4′-hydroxyphenyl) propionate] methane, 3,9-bis [2- {3- (3-t-butyl-4-hydroxy-5-methylphenyl) propionyloxy} -1,1-dimethylethyl] 2,4,8,10-tetraoxaspiro (5,5) undecane, N, N′-bis-3- (3 ′, 5′-di-t-butyl-4′-hydroxyphenyl) propionylhexamethylenediamine, N, N′-tetramethylene-bis-3- (3′-methyl-5) '-T-butyl-4'-hydroxyphenol) propionyldiamine, N, N'-bis- [3- (3,5-di-t-butyl-4-hydroxyphenol) propionyl] Dorazine, N-salicyloyl-N′-salicylidenehydrazine, 3- (N-salicyloyl) amino-1,2,4-triazole, N, N′-bis [2- {3- (3,5-di- t-butyl-4-hydroxyphenyl) propionyloxy} ethyl] oxyamide, pentaerythrityl-tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], N, N′-hexamethylene Bis- (3,5-di-t-butyl-4-hydroxy-hydrocinnamide) and the like. Preferably, triethylene glycol-bis- [3- (3-t-butyl-5-methyl- 4-hydroxyphenyl) -propionate], tetrakis [methylene-3- (3 ′, 5′-di-t-butyl-4′-hydroxyphenyl) propionate Acid] methane, 1,6-hexanediol-bis- [3- (3,5-di-tert-butyl-4-hydroxyphenyl) -propionate], pentaerythrityl-tetrakis [3- (3,5- Di-t-butyl-4-hydroxyphenyl) propionate], N, N′-hexamethylenebis- (3,5-di-t-butyl-4-hydroxy-hydrocinnamide). Specific product names of the hindered phenol compounds include “ADEKA STAB” AO-20, AO-30, AO-40, AO-50, AO-60, AO-70, AO-80, AO-330 manufactured by ADEKA. “Irganox” 245, 259, 565, 1010, 1035, 1076, 1098, 1222, 1330, 1425, 1520, 3114, 5057, manufactured by Ciba Specialty Chemicals, “Sumilyzer” BHT-R, MDP-S, manufactured by Sumitomo Chemical Co., Ltd. Examples include BBM-S, WX-R, NW, BP-76, BP-101, GA-80, GM, GS, “Sianox” CY-1790 manufactured by Cyanamid.

  Specific examples of the thioether compound include dilauryl thiodipropionate, ditridecyl thiodipropionate, dimyristyl thiodipropionate, distearyl thiodipropionate, pentaerythritol tetrakis (3-lauryl thiopropionate) Pentaerythritol-tetrakis (3-dodecylthiopropionate), pentaerythritol-tetrakis (3-octadecylthiopropionate), pentaerythritol-tetrakis (3-myristylthiopropionate), pentaerythritol-tetrakis (3- Stearylthiopropionate). Specific trade names of thioether compounds include “ADEKA STAB” AO-23, AO-412S, AO-503A from ADEKA, “Irganox” PS802 from Ciba Specialty Chemicals, “Sumilyzer” TPL-R from Sumitomo Chemical, Examples thereof include TPM, TPS, TP-D, DSTP manufactured by API Corporation, DLTP, DLTOIB, DMTP, “Sinox” 412S manufactured by Cypro Kasei, and “Sianox” 1212 manufactured by Cyamide.

Specific examples of the vitamin compounds include d-α-tocopherol acetate, d-α-tocopherol succinate, d-α-tocopherol, d-β-tocopherol, d-γ-tocopherol, d-δ-tocopherol, d- Natural products such as α-tocotrienol, d-β-tocofetrienol, d-γ-tocofetrienol, d-δ-tocofetrienol, dl-α-tocopherol, dl-α-tocopherol acetate, succinic acid Synthetic products such as dl-α-tocopherol calcium and dl-α-tocopherol nicotinate can be mentioned. Specific product names of vitamin compounds include “Tocopherol” manufactured by Eisai, “Irganox” E201 manufactured by Ciba Specialty Chemicals, and the like.
Specific examples of the triazole compound include benzotriazole, 3- (N-salicyloyl) amino-1,2,4-triazole, and the like.

  Specific examples of the polyvalent amine compound include 3,9-bis [2- (3,5-diamino-2,4,6-triazaphenyl) ethyl] -2,4,8,10-tetraoxaspiro. [5.5] Undecane, ethylenediamine-tetraacetic acid, alkali metal salt (Li, Na, K) salt of ethylenediamine-tetraacetic acid, N, N'-disalicylidene-ethylenediamine, N, N'-disalicylidene-1 , 2-propylenediamine, N, N ″ -disalicylidene-N′-methyl-dipropylenetriamine, 3-salicyloylamino-1,2,4-triazole and the like.

  Specific examples of the hydrazine derivative-based compound include decamethylene dicarboxylic acid-bis (N′-salicyloyl hydrazide), bis (2-phenoxypropionyl hydrazide) isophthalate, N-formyl-N′-salicyloyl hydrazine. 2,2-oxamide bis- [ethyl-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], oxalyl-bis-benzylidene-hydrazide, nickel-bis (1-phenyl-3- Methyl-4-decanoyl-5-pyrazolate), 2-ethoxy-2′-ethyloxanilide, 5-t-butyl-2-ethoxy-2′-ethyloxanilide, N, N-diethyl-N ′, N'-diphenyloxamide, N, N'-diethyl-N, N'-diphenyloxamide, oxalic acid De-bis (benzylidenehydrazide), thiodipropionic acid-bis (benzylidenehydrazide), bis (salicyloylhydrazine), N-salicylidene-N′-salicyloylhydrazone, N, N′-bis [3- ( 3,5-di-tert-butyl-4-hydroxyphenyl) propionyl] hydrazine, N, N′-bis [2- [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionyloxy] Ethyl] oxamide and the like.

  Examples of phosphorus compounds include phosphite compounds and phosphate compounds. Specific examples of such phosphite compounds include tetrakis [2-t-butyl-4-thio (2′-methyl-4′-hydroxy-5′-t-butylphenyl) -5-methylphenyl] -1, 6-hexamethylene-bis (N-hydroxyethyl-N-methylsemicarbazide) -diphosphite, tetrakis [2-tert-butyl-4-thio (2'-methyl-4'-hydroxy-5'-tert-butylphenyl) -5-methylphenyl] -1,10-decamethylene-di-carboxylic acid-di-hydroxyethylcarbonylhydrazide-diphosphite, tetrakis [2-tert-butyl-4-thio (2'-methyl-4'-hydroxy-) 5'-t-butylphenyl) -5-methylphenyl] -1,10-decamethylene-di-carboxylic acid di-sali Roylhydrazide-diphosphite, tetrakis [2-tert-butyl-4-thio (2′-methyl-4′-hydroxy-5′-tert-butylphenyl) -5-methylphenyl] -di (hydroxyethylcarbonyl) hydrazide— Diphosphite, tetrakis [2-t-butyl-4-thio (2'-methyl-4'-hydroxy-5'-t-butylphenyl) -5-methylphenyl] -N, N'-bis (hydroxyethyl) oxamide -Diphosphite and the like are mentioned, and those in which at least one PO bond is bonded to an aromatic group are more preferable. Specific examples include tris (2,4-di-t-butylphenyl) phosphite, Tetrakis (2,4-di-t-butylphenyl) 4,4′-biphenylene phosphonite, bis (2,4-di-t-butylphenyl) Pentaerythritol-di-phosphite, bis (2,6-di-t-butyl-4-methylphenyl) pentaerythritol-di-phosphite, 2,2-methylenebis (4,6-di-t-butylphenyl) Octyl phosphite, 4,4′-butylidene-bis (3-methyl-6-tert-butylphenyl-di-tridecyl) phosphite, 1,1,3-tris (2-methyl-4-ditridecyl phosphite— 5-t-butyl-phenyl) butane, tris (mixed mono and di-nonylphenyl) phosphite, tris (nonylphenyl) phosphite, 4,4'-isopropylidenebis (phenyl-dialkyl phosphite) and the like Tris (2,4-di-t-butylphenyl) phosphite, 2,2-methylenebis (4,6-di) t-butylphenyl) octyl phosphite, bis (2,6-di-t-butyl-4-methylphenyl) pentaerythritol-di-phosphite, tetrakis (2,4-di-t-butylphenyl) -4, 4′-biphenylenephosphonite and the like can be preferably used. Specific product names of phosphite compounds include “ADEKA STAB” C, PEP-4C, PEP-8, PEP-11C, PEP-24G, PEP-36, HP-10, 2112, 260, 522A, manufactured by ADEKA, 329A, 1178, 1500, C, 135A, 3010, TPP, “Irgaphos” 168, manufactured by Ciba Specialty Chemicals, “Sumilyzer” P-16, manufactured by Sumitomo Chemical, “Sand Stub” manufactured by Clariant, P-EPQ, “Weston” manufactured by GE 618, 619G, 624 and the like.

  Specific examples of the phosphate compound include monostearyl acid phosphate, distearyl acid phosphate, methyl acid phosphate, isopropyl acid phosphate, butyl acid phosphate, octyl acid phosphate, isodecyl acid phosphate, etc., among them monostearyl acid phosphate Distearyl acid phosphate is preferred. Specific product names of phosphate compounds include “Irganox” MD1024 from Ciba Specialty Chemicals, “Inhibitor” OABH from Eastman Kodak, “Adekastab” CDA-1, CDA-6, AX-71 from ADEKA, etc. Can be mentioned.

  The addition amount of the catalyst deactivator is not particularly limited, but is preferably 0.001 to 2 parts by weight with respect to 100 parts by weight of the polylactic acid resin in terms of excellent thermal stability. It is more preferably ˜1 part by weight, still more preferably 0.05 to 0.5 part by weight, and most preferably 0.08 to 0.3 part by weight. The addition timing of the catalyst deactivator is not particularly limited, and may be any before or after the start of each of the first step, the second step and the third step, but a high melting point, high molecular weight polylactic acid resin is used. It is preferably added at the stage of the first step or the second step in that it can be obtained, and is added immediately before the end of the first step or at the start of the second step in terms of excellent productivity. More preferably, it is more preferably added immediately before the end of the first step and at the start of the second step. In addition, when adding at the start of a 2nd process, it is preferable to add the catalyst for solid-phase polymerization after adding a catalyst deactivator. When adding in each step of the first step or the second step, it is preferable to add 0.001 to 1 part by weight with respect to 100 parts by weight of the polylactic acid resin, and it is excellent in productivity. It is more preferable to add 0.01 to 0.5 parts by weight, more preferably 0.01 to 0.1 parts by weight. Moreover, it is also preferable to add a catalyst deactivator after completion of the third step in that a polylactic acid resin excellent in thermal stability can be obtained.

  In the present invention, the method of adding the catalyst deactivator is not particularly limited, and examples thereof include a method of melt kneading above the melting point of the polylactic acid resin, a method of removing the solvent after mixing in a solvent and the like. However, a method of melt-kneading at a melting point or higher of the polylactic acid resin is preferable in that it can be produced efficiently. The melt-kneading method may be a batch method or a continuous method. As the apparatus, a single-screw extruder, a twin-screw extruder, a multi-screw extruder, a plastmill, a kneader, a stirring reactor equipped with a decompression device, or the like is used. It is preferable to use a single screw extruder or a twin screw extruder in that it can be kneaded efficiently and uniformly.

  In the present invention, the temperature at which the catalyst deactivator is added is preferably from 180 to 250 ° C., and more preferably from 190 to 230 ° C. in terms of excellent mechanical properties.

  In the present invention, the pressure at which the catalyst deactivator is added may be any of reduced pressure, normal pressure, and increased pressure, and is preferably reduced in that the generated gas can be removed during melt-kneading.

  In the present invention, the atmospheric conditions at the time of melt kneading may be either an air atmosphere or an inert gas atmosphere such as nitrogen, but in an inert gas atmosphere in that the amount of gas generated at the time of melt kneading can be reduced. It is preferable to carry out with.

  When mixing in a solvent, a solvent in which the polymer and the monomer are dissolved is used. As the solvent, for example, chloroform, methylene chloride, acetonitrile and the like can be used. The method for removing the solvent when it is necessary to remove the solvent after mixing is not particularly limited. For example, the solvent is volatilized at room temperature and the solvent is volatilized at a temperature equal to or higher than the boiling point of the solvent under reduced pressure. Or the like can be used.

  In the polylactic acid-based resin obtained by the production method of the present invention, ordinary additives such as fillers (glass fiber, carbon fiber, metal fiber, natural fiber, organic fiber, organic fiber, Glass flakes, glass beads, ceramic fibers, ceramic beads, asbestos, wollastonite, talc, clay, mica, sericite, zeolite, bentonite, montmorillonite, synthetic mica, dolomite, kaolinite, fine silicic acid, feldspar powder, titanic acid Potassium, shirasu balloon, calcium carbonate, magnesium carbonate, barium sulfate, calcium oxide, aluminum oxide, titanium oxide, aluminum silicate, silicon oxide, gypsum, novaculite, dosonite or clay, ultraviolet absorbers (resorcinol, salicylate, benzo) Lyazole, benzophenone, etc.), heat stabilizer (hindered phenol, hydroquinone, phosphites and their substitutes, etc.), lubricant, mold release agent (montanic acid and its salt, its ester, its half ester, stearyl alcohol, stearamide) And polyethylene waxes), colorants including dyes (such as nigrosine) and pigments (such as cadmium sulfide and phthalocyanine), anti-coloring agents (such as phosphites and hypophosphites), flame retardants (red phosphorus, phosphate esters) , Brominated polystyrene, brominated polyphenylene ether, brominated polycarbonate, magnesium hydroxide, melamine and cyanuric acid or salts thereof, conductive agent or colorant (carbon black, etc.), slidability improver (graphite, fluororesin, etc.) ), Crystal nucleating agent (t Inorganic nucleating agents such as bismuth, organic amide compounds such as ethylene bislauric acid amide, ethylene bis-12-dihydroxystearic acid amide and trimesic acid tricyclohexyl amide, pigment nucleating agents such as copper phthalocyanine and pigment yellow 110, organic 1 type, or 2 or more types, such as a carboxylic acid metal salt, zinc phenylphosphonate, and an antistatic agent, can be added.

  In addition, the polylactic acid block copolymer obtained by the production method of the present invention includes other thermoplastic resins (for example, polyethylene, polypropylene, acrylic resin, polyamide, polyphenylene sulfide resin, as long as the object of the present invention is not impaired). Polyether ether ketone resin, polyester, polysulfone, polyphenylene oxide, polyacetal, polyimide, polyetherimide, etc.) or thermosetting resin (eg phenol resin, melamine resin, polyester resin, silicone resin, epoxy resin, etc.) or soft thermoplastic Less resin (eg, ethylene / glycidyl methacrylate copolymer, polyester elastomer, polyamide elastomer, ethylene / propylene terpolymer, ethylene / butene-1 copolymer, etc.) It may also further contain one or more.

  The polylactic acid-based resin obtained by the production method of the present invention has a high molecular weight even after it is once melted and solidified when it is processed into a molded product or the like, and in a preferred embodiment, has a high melting point, It is easy to form a polylactic acid resin having excellent thermal stability and hue.

  The polylactic acid resin obtained by the production method of the present invention can be widely used as a molded product. Examples of molded products include films, sheets, fibers / clothes, non-woven fabrics, injection molded products, extrusion molded products, vacuum / pressure molded products, blow molded products, and composites with other materials. The article is useful for agricultural materials, horticultural materials, fishery materials, civil engineering / architectural materials, stationery, medical supplies, automotive parts, electrical / electronic components or other uses.

  Hereinafter, the present invention will be described specifically by way of examples. Here, the number of parts in the examples indicates parts by weight.

  The measurement method and determination method used in the present invention are shown below.

(1) Weight average molecular weight (Mw)
It is a value of weight average molecular weight in terms of standard polymethyl methacrylate measured by gel permeation chromatography (GPC). GPC measurement is performed using a WATERS differential refractometer WATERS410 as a detector, a MODEL510 high-performance liquid chromatography as a pump, and a column with Shodex GPC HFIP-806M and Shodex GPC HFIP-LG connected in series. It was. The measurement conditions were a flow rate of 0.5 mL / min, hexafluoroisopropanol was used as a solvent, and 0.1 mL of a solution having a sample concentration of 1 mg / mL was injected.

(2) Melting point This is a value measured by a differential scanning calorimeter (DSC), and a DSC7 manufactured by PerkinElmer was used, and the measurement conditions were 10 mg of a sample in a nitrogen atmosphere at a heating rate of 20 ° C./min.

(3) Thermal stability This is a value measured with a thermogravimetric measuring device (TGA), using TGA7 manufactured by PerkinElmer, and as a measurement condition, the weight is retained when the sample is held at 220 ° C. for 30 minutes in a nitrogen atmosphere. Judged from the rate. It can be said that the greater the weight retention, the better the thermal stability.

(4) Hue Judging from visual judgment, the following criteria were used.
5: No coloring 4: Intermediate between 3: 3 and 5: Slight yellow coloring 2: Intermediate between 1: 1 and 3: High coloring

[Example 1]
(A) First Step In a reaction vessel equipped with a stirrer, 100 parts of a 90% L-lactic acid aqueous solution was put, the temperature was raised to 160 ° C., and the pressure was gradually reduced to 800 Pa, while removing water. It was made to react for 5 hours and the low molecular weight body (A-1) of Mw3000 was obtained.
(B) Second Step In a reaction vessel equipped with a stirrer, 100 parts of a low molecular weight substance (A-1) is placed, and the temperature is 180 ° C. under normal pressure and nitrogen atmosphere. II) 0.5 part was added, the pressure was gradually reduced to 500 Pa, and a prepolymer (B-1) having an Mw of 35,000 was obtained by carrying out a polymerization reaction for 6 hours.
(C) 3rd process 100 parts of prepolymers were put into the vacuum dryer, and it was made to react under conditions of 145 degreeC and 50 Pa for 40 hours, and polylactic acid-type resin (C-1) was obtained.

  The results are shown in Table 1 for the polylactic acid resin obtained above.

[Examples 2 to 8]
(B) The same procedure as in Example 1 was performed except that the catalyst was changed to the catalyst shown in Table 1 in the second step. The results are shown in Table 1.

[Example 9]
(B) After completion of the second step, the prepolymer (B-9) was pulverized to an average particle diameter of 0.1 mm using a hammer pulverizer, and then crystallized at 120 ° C. for 2 hours using a hot air dryer. The same procedure as in Example 1 was performed except that the conversion treatment was performed. The results are shown in Table 2.

[Example 10]
(C) It was carried out in the same manner as in Example 9 except that the reaction was carried out at 140 ° C. for 10 hours, 150 ° C. for 10 hours, and 160 ° C. for 20 hours. The results are shown in Table 2.

[Example 11]
(C) After completion of the third step, 0.5 part of the catalyst deactivator (AX-71) is blended with 100 parts of the polylactic acid resin (C-11), and melt kneading is performed using a single screw extruder. This was carried out in the same manner as in Example 10 except that a pellet-shaped polylactic acid resin (D-11) was obtained. The results are shown in Table 2.

[Example 12]
(B) After completion of the second step, the prepolymer (B-12) is pulverized to an average particle diameter of 3 mm using a hammer pulverizer, and then crystallized at 120 ° C. for 2 hours using a hot air dryer. (C) In the third step, the reaction was carried out in the same manner as in Example 11 except that the reaction was carried out at 150 ° C. for 50 hours under atmospheric pressure and nitrogen flow using a tower reactor. The results are shown in Table 2.

[Example 13]
(B) After completion of the second step, using a dropping nozzle, the prepolymer (B-13) in a molten state was dropped into droplets, and particle shaped pellets were prepared while making countercurrent contact with an air flow at 90 ° C. Then, it carried out like Example 12 except performing a crystallization process at 70 degreeC for 1 hour and 100 degreeC by 1 hour with a hot air dryer. The results are shown in Table 2.

[Examples 14 to 18]
(B) The same procedure as in Example 13 was performed except that the catalyst was changed to the catalyst shown in Table 3 in the second step. The results are shown in Table 3.

[Examples 19 to 31]
(A) Except for changing the presence or absence of catalyst, temperature, pressure, and time in the first step to the conditions shown in Table 4, and (B) changing the temperature and pressure in the second step to the conditions shown in Table 4. Was carried out in the same manner as in Example 15. The results are shown in Table 4.

[Comparative Examples 1-8]
(A) Except for changing the presence / absence of catalyst, temperature, pressure, and time in the first step to the conditions shown in Table 5, and (C) changing the temperature in the third step to 140 ° C. The same was done. The results are shown in Table 5.

  In Comparative Examples 2, 4, 6, and 7, (B) the melting point of the prepolymer after the second step is low and melts at 140 ° C. or higher, so (C) the third step cannot be performed, A high molecular weight polylactic acid resin could not be obtained.

[Comparative Example 9]
(B) All operations were performed in the same manner as in Example 15 except that the second step was changed to a non-catalytic state. The results are shown in Table 5.

Claims (14)

A method for producing a polylactic acid resin by direct polycondensation in the absence of a solvent using lactic acid as a main raw material, which comprises the following three steps.
(A) A step of producing a low molecular weight product having a weight average molecular weight of less than 10,000 under the conditions of at least three or more selected from the following as the first step.
(A-1) Non-catalyst (a-2) Temperature of 100 to 180 ° C. (a-3) Pressure of 0.13 to 1300 Pa (a-4) Reaction time of 0.3 to 15 hours (B) Second step As a process for producing a prepolymer having a weight average molecular weight of more than 10,000 and less than 100,000 in the presence of a catalyst.
(C) As the third step, a step of producing a polymer having a weight average molecular weight of 100,000 or more by performing solid phase polymerization at a temperature not higher than the melting point of the prepolymer. The method for producing a polylactic acid resin according to claim 1, wherein the second step (B) is performed under the following conditions.
(B-1) 140-240 degreeC temperature (b-2) 0.13-1300Pa pressure The method for producing a polylactic acid-based resin according to any one of claims 1 to 2, wherein the (C) third step is performed under a temperature condition of 120 to 160 ° C. The polylactic acid according to any one of claims 1 to 3, wherein the crystallization treatment is performed at a temperature of 50 to 150 ° C after the completion of the (B) second step and (C) before the start of the third step. Method for production of resin. The polylactic acid according to any one of claims 1 to 4, wherein a catalyst deactivator is added at any stage from the start of the (A) first step to the end of the (C) third step. Method for production of resin. In the (A) 1st process and / or (B) 2nd process, the apparatus which connected the reaction tank and the recirculation | reflux apparatus is used, The polylactic acid-type resin in any one of Claims 1-5 characterized by the above-mentioned. Production method. The reaction vessel used in the (A) first step and / or (B) second step is composed of two or more reaction chambers. Method. In any one or more steps selected from (A) the first step, (B) the second step, and (C) the third step, water is removed from the volatile components, and lactic acid and lactide or those The method for producing a polylactic acid-based resin according to any one of claims 1 to 7, wherein the low molecular weight polymer is returned to the reaction tank of (A) the first step and / or (B) the second step. As the catalyst in the second step (B), one or more selected from tin compounds, titanium compounds, lead compounds, zinc compounds, cobalt compounds, iron compounds, lithium compounds, rare earth compounds, and sulfonic acid compounds are used. The method for producing a polylactic acid resin according to any one of claims 1 to 8. 10. (B) One or more types selected from tin compounds and / or one or more types selected from sulfonic acid compounds are used as the catalyst in the second step. Of producing a polylactic acid resin. The tin compound is tin (II) acetate and / or tin (II) octylate, and the sulfonic acid compound is any one selected from methanesulfonic acid, ethanesulfonic acid, propanedisulfonic acid, and naphthalenedisulfonic acid It is the above, The manufacturing method of the polylactic acid-type resin of Claim 10 characterized by the above-mentioned. The resin composition containing the polylactic acid-type resin obtained by the manufacturing method in any one of Claims 1-11. A molded article comprising the resin composition according to claim 12. Contains one or more tin compounds selected from tin (II) acetate and tin (II) octylate, and one or more sulfonic acid compounds selected from methanesulfonic acid, ethanesulfonic acid, propanedisulfonic acid, and naphthalenedisulfonic acid Polylactic acid based resin.