JPH1160711A - Production of aliphatic polyester - Google Patents

Abstract

PROBLEM TO BE SOLVED: To smoothly, steadily and stably obtain the subject polymer useful as a high quality material for medical use and the like by subjecting an aliphatic polyhydric alcohol, an aliphatic polybasic acid, and the like to a dehydrative polycondensation reaction under the control of reaction conditions based on specific measurement data. SOLUTION: This method for producing an aliphatic polyester comprises subjecting an aliphatic polyhydric alcohol and an aliphatic polybasic acid and/or a hydroxycarboxylic acid, or their oligomer or polymer to a thermal dehydrative polycondensation reaction in an organic solvent to obtain the polyester having a weight-average mol.wt. of >=15,000, while measuring one or more physical properties selected from the number of terminal groups, the content of water, a concentration and the mol.wt. in the reaction mixture with time by the use of a near IR light spectroscopic meter having an analyzer capable of carrying out multivariate analyses by chemometrics and controlling a reaction time and two or more reaction conditions selected from the temperature of a reactor, the pressure of the reactor, the flow of an inactive gas, the content of water, the concentration and a refluxing amount on the basis of the measurement results.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing an aliphatic polyester useful as a biodegradable polymer as a substitute for a medical material or a general-purpose resin. More specifically, in a method for producing an aliphatic polyester, a desired aliphatic polyester can be obtained by quickly measuring the physical properties of a reaction mixture during the dehydration condensation reaction and quickly and automatically controlling the reaction conditions. Relates to a method for producing aliphatic polyesters that can be obtained constantly, with high quality and quickly.

[0002]

2. Description of the Related Art Aliphatic polyesters have excellent mechanical properties, physical properties and chemical properties, and are decomposed in a natural environment without causing any harm. It has a biodegradable function of becoming carbon dioxide gas, and in recent years has been attracting attention in various fields such as medical materials and alternatives to general-purpose resins from the viewpoint of environmental protection. Expected.

In general, aliphatic polyesters are produced by dehydration polycondensation of a polyhydric alcohol and a polybasic acid, deglycolization of a low molecular weight polyester having a terminal hydroxy group, or dehydration polycondensation or dehydration dimerization of a hydroxycarboxylic acid. After the dimer is obtained, it is produced by a method such as ring-opening melt polymerization. The group of the present inventors has so far
The direct dehydration polymerization method capable of industrially producing aliphatic polyesters efficiently, easily and inexpensively has been intensively studied (JP-A-6-172502, JP-A-7-2702).
No. 986).

Here, in order to obtain aliphatic polyesters having a high molecular weight (the high molecular weight is about 15,000 or more in terms of weight average molecular weight), the temperature, pressure,
A method of controlling the flow rate of inert gas, moisture, concentration, reflux amount, reaction time, etc. is employed.However, in general, it is not possible to keep the reaction conditions under specific conditions due to fluctuations caused by equipment constants, various internal and external factors. Have difficulty. Therefore, usually, the polymerization is controlled by controlling physical properties such as the number of terminal groups (or terminal group concentration), moisture, concentration, molecular weight and the like in the polymerization reaction mixture over time.

Heretofore, these physical properties have been measured separately by different analytical techniques. For example, the number of terminal groups (or terminal group concentration) can be determined by a method based on chemical titration (for example, see JIS K0070). The water content is determined by a method of measuring using a Karl Fischer water content measuring device or the like.

[0006] Concerning the concentration, in the case of the solute concentration of aliphatic polyesters in the reaction mixture, a method of isolating the aliphatic polyesters from a predetermined amount of the reaction mixture and measuring the weight of the aliphatic polyesters to calculate the concentration; A method of calculating by measuring the weight after removing the organic solvent and volatile impurities and unreacted raw materials by evaporating to dryness, a calibration prepared in advance from an elution curve by gel permeation chromatography of a predetermined amount of the reaction mixture It is determined by a method of calculating the solute concentration according to the line, or the like.

In the case of the concentration of impurities in the reaction mixture, the measuring method differs depending on the target impurity. For example, after performing a pretreatment such as hydrolysis of the reaction mixture, an elution curve by high performance liquid chromatography or the like is measured. It is determined by a method of quantification from a calibration curve prepared in advance or the like.

For the molecular weight, a method of measuring the intrinsic viscosity using a viscometer and converting it into a molecular weight according to a calibration curve prepared in advance, a calibration curve calculated by a standard sample by measuring an elution curve by gel permeation chromatography In accordance with the following formula.

Usually, in controlling the polymerization, it is necessary to simultaneously control a plurality of physical property values over time, each of which requires a separate sample. Therefore, a plurality of samples are required, and the number of sampling points is increasing at present. This has taken a considerable amount of time for sampling, and has been one of the causes of an increase in product loss due to the sampling and a disturbance in the reaction system.

The time required from the sampling to the determination of the physical property value differs depending on the management target and the measuring means or measuring method or analyzing method for each physical property, and usually requires about 30 minutes to 2 hours. At present, pre-processing may take time. This has led to the reality that real-time control of polymerization is not always feasible in managing a plurality of physical properties at the same time. That is, at present, the current polymerization conditions are set by estimating from the evaluation while evaluating the progress of the past physical property values over time. Therefore civil war,
It is extremely difficult to instantaneously grasp changes in polymerization conditions due to disturbances and the like, and polymerization control has not been carried out quickly without delay.

Further, in the above-mentioned measurement of the physical property values, since specialized skills are required for each of them, high-precision and training for minimizing the measurement error are required, the specific human At present, it is the current situation that multiple point measurement is repeatedly performed in some cases. In some cases, a large amount of reagents and solvents are required for measurement, the installation environment of the measurement device needs to be managed strictly, and the maintenance of the measurement device may be complicated or complicated. Therefore, the measurement has not always been able to be carried out simply and economically.

As described above, the rapid control of the polymerization, the smooth and steady polymerization, and as a result, the stable production of high-quality aliphatic polyesters can be achieved by the current measurement method and The management method was extremely difficult.

In view of such problems, various methods for producing polyesters using a near-infrared spectrometer have recently been disclosed. For example, JP-A-2-306937 discloses a polyesterification method for obtaining a polyester by a polycondensation reaction between a polycarboxylic acid and a polyhydric alcohol, wherein the acid value of the polyhydric carboxylic acid as a raw material, the hydroxyl value of the polyhydric alcohol, The ester value and water content of the polyester product are measured at predetermined time intervals using a near-infrared absorption spectrometer, and the measured values are used to determine the temperature, pressure, nitrogen flow rate, and reaction temperature of the reaction vessel. An automatic polyesterification method with time control is disclosed.

In the above method, an acid value, a hydroxyl value,
It is disclosed that ester number and moisture can be measured quickly and accurately.

However, although it is possible to secondary calculate the molecular weight from the acid value, hydroxyl value, ester value and the like according to a calibration curve prepared in advance, the range of molecular weight to which it can be applied is about several thousands. The degree is the upper limit. Further, there is no description about measuring the molecular weight of a polymerization reaction product directly using a near-infrared spectrometer. Further 600n
Since the entire near-infrared wavelength region from m to 2500 nm is scanned, it takes time to measure the spectrum. The spectrum is measured at time intervals such as 0.5 minutes, and then the spectrum is analyzed. And performing reaction control is virtually impossible.

Japanese Patent Application Laid-Open No. 9-3172 discloses a method for producing a polyester-based plasticizer by using a dibasic acid and a diol as main raw materials by esterification and subsequent condensation reaction. Using a measuring device including a near-infrared spectroscopic analyzer, at a predetermined time interval, measure the near-infrared absorption spectrum of the reaction, and from the measurement data, the acid value of the reaction system, hydroxyl value, molecular weight, and The water content is calculated, b) from these calculated values, control information is obtained using an arithmetic device, and c) the pressure of the reaction vessel, the flow rate of nitrogen and the reaction time are controlled in accordance with this information, whereby the polyester plasticizer is obtained. A method of making is disclosed.
The publication states that fluctuations caused by device constants and various internal and external factors can be grasped without delay, and quick control can be performed.

However, the polyester plasticizer produced in the publication is produced substantially in the absence of an organic solvent, and the method for producing high molecular weight aliphatic polyesters desired by the present inventors is as follows. The reaction form is different. In the present invention, this fact means that by using an organic solvent, in the near-infrared absorption spectrum of the measured object during the dehydration condensation reaction, the aliphatic polyesters and the organic solvent that are solutes appear simultaneously, The spectral pattern is very different from the near-infrared absorption spectrum as seen in the polyester plasticizer produced in the publication, and the aliphatic polyesters that are solutes are diluted with an organic solvent, so that the relative fat The reason is that the intensity of the near-infrared absorption spectrum of the aromatic polyester becomes weak.

As physical properties necessary for controlling the reaction conditions and the reaction time, there is a new item called concentration in addition to the items described in the publication. There is no description in this publication about measurement using an analyzer. Further, the molecular weight described in the publication is up to 10,000, and as a result of comparative study by the present inventors, an aliphatic having a weight average molecular weight (Mw) desired by the present inventors of 15,000 or more is obtained. Polyesters were found to have significantly different spectral patterns and significantly different properties of the reaction mixture. This means that the technique disclosed in the publication cannot solve the problem of the present inventors, and it is necessary to develop a more advanced technique.

[0019]

SUMMARY OF THE INVENTION The present invention is directed to a reaction mixture containing an aliphatic polyhydric alcohol and an aliphatic polybasic acid and / or hydroxycarboxylic acid, or an oligomer or polymer thereof, and containing an organic solvent. During the production of aliphatic polyesters having a weight average molecular weight of 15,000 or more that undergo a dehydration condensation reaction, physical properties such as the number of terminal groups (or terminal group concentration), moisture, concentration, and molecular weight in the polymerization reaction mixture are determined by chemometrics. Measured using a measuring device including a near-infrared spectrometer having an analyzer capable of performing multivariate analysis, and based on the obtained measurement data, the temperature of the reaction vessel, the pressure, the flow rate of the inert gas, the moisture, It is an object to provide a method for controlling the concentration, the reflux amount of an organic solvent, the reaction time, and the like.

[0020]

SUMMARY OF THE INVENTION In view of the state of the prior art as described above, the present inventors have measured the properties of a reaction mixture quickly, and controlled the reaction conditions quickly and automatically. As a result of intensive studies on the production method of polyesters, it was found that even in the presence of an organic solvent, physical properties such as the number of terminal groups (or terminal group concentration), moisture, concentration, molecular weight, etc. can be simultaneously measured from the near infrared absorption spectrum. The present invention has been reached.

That is, according to the present invention, aliphatic polyhydric alcohols or mixtures thereof and aliphatic polybasic acids or mixtures thereof, or oligomers or polymers thereof, and / or hydroxycarboxylic acids or mixtures thereof as main raw materials, or mixtures thereof A method for producing an aliphatic polyester having a weight-average molecular weight of 15,000 or more, wherein the oligomer or the polymer is subjected to a dehydration condensation reaction in a reaction mixture containing an organic solvent,

A) Using a measuring device including a near-infrared spectrometer having an analyzing device capable of performing multivariate analysis by chemometrics, measuring the near-infrared absorption spectrum of the measured object during the dehydration condensation reaction, Subsequently, based on the measurement data, the number of terminal groups (or terminal group concentration), moisture, concentration, at least one physical property value selected from molecular weight is calculated,

B) Device control information is obtained from these calculated values using a computing device. C) Specific reaction conditions and reaction times are controlled by remotely controlling the instrumentation equipment of the reactor based on this information. This is a method for producing aliphatic polyesters.

[0024]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.
A feature of the production method of the present invention is that a heat dehydration condensation reaction is carried out in the presence of an organic solvent so that the weight average molecular weight is
During the production of the above aliphatic polyesters, the number of terminal groups (or terminal group concentration) of the reaction mixture over time using a measuring device including a near-infrared spectrometer, moisture, concentration,
It is to control at least one physical property value selected from the molecular weight and to control the polymerization, but it is preferably selected from the reaction vessel temperature, pressure, inert gas flow rate, moisture, concentration, reflux amount. The purpose is to control the polymerization by at least two reaction conditions.

The following are specific examples of the aliphatic polyhydric alcohol used in the reaction of the present invention. Ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, 1,3-butanediol, 1,4-butanediol, 3-methyl-1,5
-Pentanediol, 1,6-hexanediol, 1,
9-nonanediol, neopentyl glycol, polytetramethylene glycol, 1,4-cyclohexanedimethanol, 1,4-benzenedimethanol, trimethylolpropane, trimethylolethane, trimethylolheptane, 1,2,4-butanetriol , 1,2,6
-Hexanetriol and the like. These may be used alone or in combination of two or more. Particularly preferably used aliphatic polyhydric alcohols are aliphatic diols, for example, ethylene glycol, propylene glycol, 1,3-butanediol, 1,4-butanediol, 1,6-hexanediol, 1,9- Nonanediol, or a mixture thereof.

Specific examples of the aliphatic polybasic acid used in the reaction of the present invention include the following. Succinic acid, oxalic acid, malonic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecandioic acid, dodecandioic acid, fumaric acid, maleic acid,
And tricarbaryllic acid. These may be used alone or in combination of two or more. Particularly preferably used aliphatic polybasic acids are aliphatic dicarboxylic acids, for example, succinic acid, oxalic acid, malonic acid,
Glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecandioic acid, dodecandioic acid, or mixtures thereof.

Specific examples of the hydroxycarboxylic acid used in the reaction of the present invention include the following. Glycolic acid, 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-ethyl Pentanoic acid, 2-hydroxy-2-propylpentanoic acid, 2-hydroxy-2-butylpentanoic acid, 2-hydroxy-2-methylhexanoic acid, 2-hydroxy-2-ethylhexano Ic acid, 2-hydro Ci-2-propylhexanoic acid, 2-hydroxy-2-butylhexanoic acid, 2-hydroxy-2-pentylhexanoic acid, 2-hydroxy-2-methylheptanoic acid, 2-hydroxy- 2-methylheptanoic acid, 2-hydroxy-2-ethylheptanoic acid, 2-hydroxy-2-propylheptanoic acid, 2-hydroxy-2-butylheptanoic acid, 2-hydroxy-2-pentyl Heptanoic acid, 2-hydroxy-2-hexylheptanoic acid, 2-hydroxy-2-methyloctanoic acid, 2-hydroxy-2-ethyloctanoic acid, 2-hydroxy-2-propyloctano Ic acid, 2-hydroxy- -Butyloctanoic acid, 2-hydroxy-2-pentyloctanoic acid, 2-hydroxy-2-hexyloctanoic acid, 2-hydroxy-2-heptyloctanoic acid, 3-hydroxypropanoic acid , 3-hydroxybutanoic acid, 3-
Hydroxypentanoic acid, 3-hydroxyhexanoic acid, 3-hydroxyheptanoic acid, 3-hydroxyoctanoic acid, 3
-Hydroxy-3-methylbutanoic acid, 3-
Hydroxy-3-methylpentanoic acid, 3-
Hydroxy-3-ethylpentanoic acid, 3-
Hydroxy-3-methylhexanoic acid, 3-
Hydroxy-3-ethylhexanoic acid, 3-
Hydroxy-3-propylhexanoic acid, 3
-Hydroxy-3-methylheptanoic acid, 3
-Hydroxy-3-ethylheptanoic acid, 3
-Hydroxy-3-propylheptanoic acid,
3-hydroxy-3-butylheptanoic acid,
3-hydroxy-3-methyloctanoic acid,
3-hydroxy-3-ethyloctanoic acid,
3-hydroxy-3-propyl octanoic acid, 3-hydroxy-3-butyl octanoic acid, 3-hydroxy-3-pentyl octanoic 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-hydroxyoctanoic acid,
5-hydroxy-5-methylhexanoic acid,
5-hydroxy-5-methylheptanoic acid,
5-hydroxy-5-ethylheptanoic acid,
5-hydroxy-5-methyloctanoic acid,
5-hydroxy-5-ethyloctanoic acid,
5-hydroxy-5-propyloctanoic acid, 6-hydroxyhexanoic acid, 6-hydroxyheptanoic acid, 6-hydroxyoctanoic acid, 6-hydroxy-6-methylheptanoic acid, 6- Hydroxy-6-methyloctanoic acid, 6-hydroxy-6-ethyloctanoic acid, 7-hydroxyheptanoic acid, 7-hydroxyoctanoic acid, 7-hydroxy-7-methyloctanoic acid, Aliphatic hydroxycarboxylic acids such as 8-hydroxyoctanoic acid; These may be used alone or in combination of two or more. Particularly preferably used hydroxycarboxylic acids are lactic acid, glycolic acid, 3-hydroxybutyric acid, 4-hydroxybutyric acid, 3-hydroxyvaleric acid, or a mixture thereof.

In addition, other monomers may be used in combination as long as the object of the invention is not impaired. Examples of monomers used include aromatic hydroxycarboxylic acids such as hydroxybenzoic acid, diphenols such as hydroquinone, aromatic polybasic acids such as phthalic acid, and hydroxyl groups such as malic acid, citric acid, and tartaric acid, and carboxyl groups. A compound having both groups in the molecule, at least one of which is two or more.

In the reaction of the present invention, an oligomer or polymer derived from the above-mentioned aliphatic polyhydric alcohol and aliphatic polybasic acid and / or hydroxycarboxylic acid can be used as a raw material. And they may be used as one kind or a mixture of two or more kinds.

When these aliphatic polyhydric alcohol and aliphatic polybasic acid, and / or hydroxycarboxylic acid, or an oligomer or polymer derived therefrom have an optically active carbon, D-form, L-form, Each may be used alone or a mixture of D-form and L-form, that is, a racemic form.

As used herein, the term "number of terminal groups" means the total number of hydroxyl groups and carboxyl groups present at the molecular terminals of aliphatic polyesters.
A numerical value expressed as the number of moles of the terminal group may be used, or a numerical value expressed as the number of moles of the terminal group per unit mass of the aliphatic polyester may be used as the terminal group concentration. In the method of the present invention, when expressed as a terminal group concentration, it is usually in the range of about 2 × 10 ⁻⁵ mol / g to about 2 × 10 ⁻² mol / g until polymerization is completed. Examples of the method for measuring the number of terminal groups include a method for quantifying a hydroxyl group and a carboxyl group by acid / alkali neutralization titration, and a method using a nuclear magnetic resonance spectrum (NMR).

As used herein, the term “moisture” refers to a moisture value generally expressed in units of concentration. In this specification, the moisture value in an organic solvent inside or outside a reaction system is defined as the weight concentration. The notation used is used. The unit of the concentration includes a volume concentration, a molar concentration and the like in addition to the weight concentration, and there is no limitation as long as the unit can control the polymerization reaction. In the method of the present invention,
For example, the water value in the organic solvent in the reaction system is usually from about 1 ppm to about 10,000 pp until the polymerization is completed.
m.

As used herein, “molecular weight” refers to
It means the average molecular weight of the polydisperse sample. In this specification, the weight average molecular weight (Mw) is used, but as other indexes, for example, known indexes such as a number average molecular weight (Mn), a z average molecular weight (Mz), and a viscosity average molecular weight (Mv). If so, you are not subject to any restrictions.

The molecular weight that can be measured in the present invention ranges from about 10,000 in weight average molecular weight (Mw) to the target molecular weight of the desired aliphatic polyester, and is preferably from about 10,000 to 500,000. .

Depending on the embodiment, examples of the method of measuring the molecular weight used in preparing a calibration curve described later include, for example, a method using intrinsic viscosity, gel permeation chromatography, nuclear magnetic resonance spectrum (NMR), a light scattering method, and a sedimentation equilibrium. And a membrane osmotic pressure method. However, there is no particular limitation as long as the average molecular weight can be determined within a range where the polymerization reaction is controlled.

The organic solvent used in the reaction of the present invention includes aromatic hydrocarbons, halogenated aromatic hydrocarbons, halogenated aliphatic hydrocarbons, ether hydrocarbons and the like.
As the aromatic hydrocarbon, toluene, o-xylene, p
-Xylene, m-xylene, ethylbenzene, o-diethylbenzene, p-diethylbenzene, m-diethylbenzene, isopropylbenzene, amylbenzene, diamylbenzene, p-cymene, naphthalene, biphenyl and the like.

As the halogenated aromatic hydrocarbon, chlorobenzene, o-chlorotoluene, m-chlorotoluene, p-chlorotoluene, 1-chloroethylbenzene,
2-chloroethylbenzene, 3-chloroethylbenzene, o-dichlorobenzene, m-dichlorobenzene, p
-Dichlorobenzene, 1,2,3-trichlorobenzene, 1,2,4-trichlorobenzene, 1,3,5-trichlorobenzene, bromobenzene, o-bromotoluene, m-bromotoluene, p-bromotoluene, -Bromoethylbenzene, 2-bromoethylbenzene, 3-
Bromoethylbenzene, o-dibromobenzene, m-dibromobenzene, p-dibromobenzene, 1-chloronaphthalene, 2-chloronaphthalene, 1-bromonaphthalene, 2-bromonaphthalene, 1-fluoronaphthalene and the like can be mentioned.

Examples of the halogenated aliphatic hydrocarbon include trichloromethane, tetrachloromethane, 1,1-dichloroethane, 1,2-dichloroethane, 1,1,1-trichloroethane, 1,1,2-trichloroethane 1,1, 1
-Trichloroethylene, 1,1,1,2-tetrachloroethane, 1-chloropropane, 1-chlorobutane, 1,
2-dichloropropane, 1,3-dichloropropane,
1,4-dichlorobutane, 1,2-dibromoethane,
1,1,1-tribromoethane, 1,1,2-tribromoethane 1,1,1-tribromoethylene, 1,1,
1,2-tetrabromoethane, 1-bromopropane, 1
-Bromobutane, 1,2-dibromopropane, 1,3-
Examples thereof include dibromopropane and 1,4-dibromobutane.

Examples of the ether hydrocarbon include anisole, ethoxybenzene, o-cresyl methyl ether,
m-cresyl methyl ether, p-cresyl methyl ether, 2-chloromethoxybenzene, 4-chloromethoxybenzene, dichloroethyl ether, isopropyl ether, n-butyl ether, diisoamyl ether,
Diphenyl ether, 3-phenoxytoluene, and the like. These may be one kind or a mixture of two or more kinds, and there is no limitation.

The reaction solvent can be used in an amount such that the concentration of the polymer is usually 3 to 80% by weight, and preferably in a range where the concentration of the polymer is 5 to 50% by weight. If the content is more than 80% by weight, the viscosity of the polymer when heated and dissolved becomes extremely high, and it is difficult to handle, manufacture and measure the reaction mixture during stirring during the reaction, subsequent liquid transfer and near infrared spectroscopic measurement. Such an operation may become difficult. Further, the transmittance of the reaction mixture for near-infrared light may be extremely reduced, which is not preferable. On the other hand, when it is lower than 3% by weight, there is no problem in the reaction and the post-treatment, but the volume efficiency is poor and the productivity tends to be disadvantageous.

Here, “concentration” used in the present specification
Is generally called solute concentration, and in this specification, the weight concentration of the aliphatic polyesters as the target product in the reaction mixture, which is described above as the polymer concentration, is used. The unit of the concentration includes a volume concentration, a molar concentration and the like in addition to the weight concentration, and there is no limitation as long as the unit can control the polymerization reaction. Further, in the reaction mixture of the present invention, in addition to the reaction products, various solutes such as catalysts, impurities derived from raw materials, other solutes such as dissolved oxygen, organic solvents, and the like, which can be subjected to concentration measurement, coexist. However, according to the method of the present invention, it is possible to measure the concentration of any object.

The reaction of the present invention can use a catalyst,
Examples thereof include Periodic Tables I, II, III, IV,
Group V metals or salts or hydroxides and oxides thereof. For example, metals such as zinc, tin, aluminum, magnesium, antimony, titanium, and zirconium, tin oxide, antimony oxide, lead oxide, aluminum oxide, magnesium oxide, titanium oxide, and other metal oxides, zinc chloride, stannous chloride, and chloride Stannic, stannous bromide, stannic bromide, antimony fluoride, zinc chloride, magnesium chloride,
Metal halides such as aluminum chloride, sodium hydroxide, potassium hydroxide, calcium hydroxide, magnesium hydroxide, aluminum hydroxide, zinc hydroxide, tin hydroxide, iron hydroxide, cobalt hydroxide, nickel hydroxide, hydroxide Metal hydroxides such as copper, cesium hydroxide, strontium hydroxide, barium hydroxide, lithium hydroxide, zirconium hydroxide, sulfates such as tin sulfate, zinc sulfate, aluminum sulfate, magnesium carbonate, zinc carbonate, calcium carbonate, etc. Organic carboxylate such as carbonate, tin acetate, tin octoate, tin lactate, zinc acetate, aluminum acetate, iron lactate,
Organic sulfonates such as tin trifluoromethanesulfonate and tin p-toluenesulfonate are exemplified.

Other examples include organic metal oxides of the above metals such as dibutyltin oxide, metal alkoxides of the above metals such as titanium isopropoxide, alkyl metals of the above metals such as diethyl zinc, and ion exchange resins.

When a catalyst is used, the amount of the catalyst used is 0.0001 to 10 of the aliphatic polyhydric alcohol and the aliphatic polybasic acid, and / or the hydroxycarboxylic acid, or the oligomer or polymer derived therefrom. weight%
It is.

The reaction according to the invention is preferably carried out with an aliphatic polyhydric alcohol and an aliphatic polybasic acid, and / or a hydroxycarboxylic acid, or an oligomer derived therefrom,
Alternatively, the polymer is heated to reflux in an organic solvent in the presence of a catalyst. Here, when an organic solvent that can azeotrope with water is used, water produced by the polymerization reaction can be removed to the outside of the reaction system by this azeotropic dehydration operation. In addition, this operation has an effect of distilling out impurities derived from raw materials which can be a terminal stopper out of the reaction system together with evaporation of the solvent, and is important for producing a high molecular weight aliphatic polyester. Therefore, the organic solvent containing impurities to be refluxed may be subjected to a process of once distilling out of the reaction system to remove the impurities and then returning to the reaction system again, or by charging an organic solvent containing no impurities, A process for replacing the organic solvent in the reaction system may be employed.

As a method for removing impurities from the organic solvent, the impurities may be removed by, for example, distillation, or some of the impurities may be brought into contact with water to be extracted and removed into a water layer, and the organic solvent to be returned into the reaction system. Therefore, any method may be used as long as the impurities can be removed.

The temperature of the organic solvent under reflux is preferably 80 to 250 ° C., more preferably 110 to 170 ° C. When the temperature is lower than 80 ° C., the effect of removing impurities is reduced, which is not preferable. On the other hand, when the temperature is higher than 250 ° C. or higher, the aliphatic polyesters may be thermally degraded. The pressure may be either normal pressure or reduced pressure, and the pressure at which the mixture is refluxed in the above temperature range is appropriately selected depending on the reaction solvent used.

The time for heating to reflux and, in some cases, the time for azeotropic dehydration vary depending on the reaction conditions such as the temperature and pressure of the reaction tank, the scale of the reaction, and the like, but are 0.5 to 60 hours, preferably 2. 0 to 30 hours is good. 0.5
When the time is less than the time, the effect of removing the impurities described above is not so large. When the time is more than 60 hours, there is no further effect of removing the impurities. By performing such an operation, the amount of impurities in the reaction system is extremely reduced, and a polymer having a higher molecular weight can be obtained.

The dehydration polycondensation conditions in the reaction of the present invention are as follows:
Under normal pressure or under reduced pressure, the reaction temperature can be up to the reflux temperature of the solvent used, preferably 50 to
The temperature is 250 ° C, more preferably 100 to 170 ° C. 5
If the temperature is lower than 0 ° C., the efficiency of removing water generated by the reaction out of the reaction system by azeotropy with the solvent is deteriorated, so that the reaction rate is significantly reduced. If the temperature exceeds 250 ° C., the polymer may be degraded or the reaction solution may be colored, thereby deteriorating the quality of the obtained product.

With respect to the apparatus for performing dehydration polycondensation, an organic solvent which evaporates together with the produced water is guided to the outside of the reaction system, which can be subjected to a dehydration treatment with a known dehydrating agent such as molecular sieve or ion exchange resin. There are no other restrictions as long as it has a structure that can be returned to the reaction system.

As used herein, the term “reflux amount” refers to
It means the amount of the organic solvent returned per unit time with respect to the amount of the aliphatic polyester present in the reaction system. In the dehydration polycondensation in the reaction of the present invention, in order to effectively guide the generated water out of the reaction system, it is possible to proceed with the polymerization while maintaining a predetermined reflux amount, in a shorter time, a high-quality aliphatic polyester. Is one of the conditions for producing such a product.
The amount of reflux is limited by the type and amount of the organic solvent used, the reaction temperature, the reaction pressure, the flow rate of the inert gas to be entrained, the method of dehydrating the organic solvent containing generated water led out of the reaction system, the structure of the reaction apparatus, and the like. However, it is preferable to control the amount of the aliphatic polyester in the reaction system at about 0.5 times to about 10 times per hour.

In the reaction of the present invention, the molecular weight of the reaction mixture is
The process is continued until an aliphatic polyester having a desired molecular weight can be recovered from the reaction mixture. The molecular weight of the aliphatic polyester in the reaction mixture produced by the reaction of the present invention can be controlled by the type of the organic solvent, the type and amount of the catalyst, the reaction conditions, and the like, and is usually determined by the weight average molecular weight (Mw). Often between about 15,000 and about 500,000.

The time required for completing the polymerization reaction varies depending on the reaction conditions such as the temperature and pressure of the reaction tank, the scale of the reaction, etc., but is usually from 1 hour to 150 hours. When the molecular weight of the reaction mixture reaches a value at which an aliphatic polyester having a desired molecular weight can be recovered from the reaction mixture, the reaction device is stored in an arithmetic unit for remotely controlling instrumentation equipment of the reactor so as to end the reaction. This is one of the preferred embodiments.

The reaction of the present invention is preferably carried out in a vacuum or in an atmosphere of an inert gas such as nitrogen or argon while preventing moisture from entering from outside the system and removing moisture generated in the system. It may be performed while replacing with a gas or while bubbling an inert gas.

The reaction of the present invention can be carried out by a continuous operation or a batch operation. Further, the dehydration of the organic solvent and the charging of the organic solvent can be performed by a continuous operation or a batch operation.

The measuring device including the near infrared spectrometer used in the present invention is not particularly limited as long as it has an analyzing device capable of performing multivariate analysis by chemometrics.
It is possible to use a measuring device that is already sold as a device for measuring the octane number of gasoline, the measurement of hydrogen sulfide / carbon dioxide in a desulfurization plant, the measurement of impurities in ethylene glycol, and the like. Preferably, a measuring device including a near-infrared spectrometer in which a measuring cell and a main body having a light source, an interferometer and a detector are connected by an optical fiber can be used. This makes it possible to suppress the loss of light source energy and to install the main body and the measurement cell in a state where they are isolated.

Specifically, the main body can be installed in a non-explosion-proof area, and the measuring cell can be installed in the explosion-proof area. Preferably, a measuring device equipped with a device for performing near-infrared light spectroscopy by Fourier transform can be used. This enables high sensitivity,
High-accuracy, high-speed measurement can be realized. Also preferably,
As a near-infrared light source and a reference light interferometer, a measuring device equipped with a transcept interferometer can be used. This allows the interferometer to have a completely sealed structure. If the moving mirror unit has a voice coil,
High durability can be maintained against the influence of the external world which works against the optical system such as vibration and temperature change. “Infraspec NR500” (trade name, manufactured by Yokogawa Electric Corporation) as a measuring device including such a kind of near-infrared spectrometer.
And a measuring device including:

As used herein, the term “chemometrics” refers to mathematical methods and statistical methods used to design or select optimal measurement procedures and experiments and to analyze chemical data to extract as much information as possible. A discipline that uses a generic method. The problem of the present invention can be solved by using the method based on the regression method as the present invention among the analysis methods derived thereby. Specifically, Fanout out linear multiple regression analysis (ML
R: Multiple Linear Regress
ion), principal component regression analysis (PCR: Principa)
l Component Regression), P
LS regression analysis (PLS: Partial Least)
There is no particular limitation as long as there is an analytical method such as Squares) and a method in which the physical property values are calibrated with an accuracy that meets the management target for each physical property within the range of controlling the polymerization reaction. All of these analysis methods are commercially available as computer software and can be easily obtained.

In the method of the present invention, a measuring device including a near-infrared spectrometer having an analyzing device that can use the above-described analyzing method is used. Thereby, the number of terminal groups, moisture, concentration or molecular weight of the reaction mixture can be calculated from the measurement data of different wavelength regions in the near infrared absorption spectrum of the reaction mixture. In general, near-infrared absorption spectra provide information on changes in the energy state of molecular vibration and molecular rotation of molecules. For example, from 1,800 nm to 2.5
In the region of 00 nm, an absorption band mainly due to the coupling sound of the reference vibration is observed. 1,100nm to 1,800nm
In the region of, an absorption band mainly due to the first harmonic of the reference vibration is observed. In the region from 750 nm to 1,100 nm, absorption bands mainly due to the second and third harmonics of the reference vibration are observed. Specifically, OH, CH, NH, CO
Coupling sound such as stretching vibration caused by functional groups such as
Second harmonic and third harmonic absorption appear in this near infrared region. These absorption spectra may be used as they are, but depending on the case, may be obtained by mathematically subtracting the absorption spectrum attributable to a specific substance from the obtained absorption spectrum (generally called a difference spectrum). A spectrum that has been subjected to arithmetic processing, such as a spectrum obtained by performing one-time differentiation on the obtained absorption spectrum (generally called a first-order differential spectrum) or a spectrum obtained by performing a second-order differentiation on the obtained absorption spectrum (generally called a second-order differential spectrum) The spectrum may be used, and sufficient correlation can be expected in preparing a calibration curve described later, and there is no limitation as long as the spectrum has universality in actually measuring the physical property values.

From these spectra, a plurality of wavelength regions having a high correlation with the number of terminal groups, water content, concentration or molecular weight of the reaction mixture calculated by a known method are selected at a plurality of locations, and from the measured data of these wavelength regions. A regression equation for calculating the number of terminal groups, water content, concentration or molecular weight is derived. The derived regression equation is calculated by hijacking a calibration curve created based on measurement data for a known reference sample in advance.If it is confirmed that there is sufficient correlation, the unknown regression method It can be applied to the analysis of

One of the remarkable features of the present invention is that a concentration corresponding to the mixture ratio was obtained from a near infrared absorption spectrum from a chemically identical product and an organic solvent. It is. That is, the fact that the near-infrared absorption spectrum of the reaction mixture has concentration dependence was not known at all before the present invention, and was very surprising.
In the method of the present invention, each physical property value was calculated by applying the above method to each physical property.

As a measuring cell installed in a measuring apparatus including a near infrared spectrometer used in the present invention, a conventionally known measuring cell commercially available can be used. When performing online measurement of the spectrum, the measurement cell is installed in a place directly in contact with the reaction solution, specifically, installed in the reaction tank, or installed in a circulation line outside the reaction tank,
Alternatively, it is desirable to provide a dedicated bypass line for sampling separately and install it during the introduction. Various commercially available materials such as Pyrex glass and quartz may be used as the material of the cell, and a material having substantially no absorption derived from the cell in a desired measurement wavelength region may be appropriately selected and used.

Here, a particularly important fact is that the object to be measured in the production method of the present invention is a polymerization reaction product containing an organic solvent, and its properties may not always be substantially colorless and transparent. This has been a very serious obstacle in measuring the near infrared absorption spectrum.
That is, the intensity of the transmitted light from the measurement cell becomes extremely weak as compared with the light incident on the measurement cell, and as a result, a phenomenon occurs in which the absorbance increases. An object that is not substantially colorless and transparent induces irregular reflection when light is transmitted, and the amount of light reaching the light receiving portion for near-infrared light is reduced. In measurement, a decrease in the amount of received light is regarded as absorption of near-infrared light of the object to be measured, and the resulting absorption spectrum exhibits the spectrum at a position where the absorbance is large.

In such a case, even in a wavelength region where near-infrared light is not substantially absorbed, a phenomenon in which the spectrum is irregularly waved as if near-infrared light was absorbed. Or abnormal behavior of the spectrum based on noise caused by diffuse reflection, such as a phenomenon in which the baseline of the spectrum is extremely inclined. Various causes can be considered as the cause, for example, the solubility or concentration of the target product at the measurement temperature, various physical properties of by-products or unreacted products or impurities in the polymerization reaction, the reaction catalyst, or the target product. It is thought to be due to the properties and the like that have already existed.

As a result of intensive studies on this point, it was found that by adjusting the cell length so that all of the near-infrared absorption spectra fall within the predetermined absorbance range, the near-infrared ray which does not hinder the subsequent analysis can be obtained. It was found that an absorption spectrum was obtained, and the present invention was completed. In the method of the present invention, this fact is the basis, and various physical properties can be analyzed using a conventionally known near-infrared spectroscopic analysis method, while maintaining simple and high accuracy unlike the past, and as a result, the polymerization reaction is controlled. And controllability.

The predetermined range of the absorbance in the method of the present invention is specifically in the range of 0 abs to 1 abs in terms of absorbance, preferably in the range of 0 abs to 0.9 abs. K0115
reference). Therefore, it is necessary to adjust the cell length so that all the near-infrared absorption spectra of the object to be measured fall within the above-described range in the entire range within the wavelength range used for measurement. The optimum cell length will take a different value each time depending on the properties of the measured object, etc. for the above-mentioned reason, but a plurality of the above-mentioned calibration curves are calculated in advance for a predetermined cell, and the calculated values are calculated by an arithmetic unit. By storing the data and calling and applying an appropriate calibration curve corresponding to a predetermined cell length, each physical property value can be calculated. In order to control the polymerization reaction more easily, preferably, an appropriate cell length is determined in advance so that all the measurements until the end of one polymerization reaction are performed with the same cell length, and the desired data is determined. It is desirable to adjust it so that it can be obtained. The optimum cell length can be easily determined by a person skilled in the art by experiments and the like.

In the present invention, a known apparatus can be used as the reaction apparatus. FIG. 1 shows a schematic diagram of an example of the apparatus.
(1) is a reaction tank, (2) is a condenser, (3) is a vacuum generator, (4) is a pressure regulating valve, (5) is a receiver, and (6) dehydrates an organic solvent to a predetermined moisture value. Dehydration equipment, (7)
Is an inert gas line, (8) is an organic solvent line, (9)
Is a flow meter, (10) is a temperature control unit, (11) is a jacket for heating or cooling the reaction tank, (12) is a pump, (1)
3) is a circulation pipe, (14) is a measurement cell, (15) is an optical fiber, (16) is a set of near-infrared spectrometers, (1)
7) is a computer for system control, (18) is a stirrer, and (19) is a motor.

The calculated value of the number of terminal groups, water content, concentration or molecular weight of the reaction mixture by the above-mentioned measuring device is transferred to an arithmetic unit included in the system control computer (17).
Here, device control information for performing a desired calculation is obtained. For the control method of the instrumentation device, for example, a known method such as PID control and one-loop control can be applied.
There is no limitation as long as it is a control method in which each physical property can be managed with high precision and universality within the range of controlling the polymerization reaction. Based on this information, for example, predetermined instrumentation devices such as a temperature control unit (10), a pressure regulating valve (4), and a flow meter (9) are remotely operated to control the temperature, pressure,
The operation is performed such that the flow rate, concentration, and reflux amount of the inert gas match the desired reaction conditions.

It is within the scope of the present invention to store a desired control mode in advance in the arithmetic unit so that any control can be performed. According to the method of the present invention, various physical properties of the polymerization reaction mixture can be obtained quickly and with high accuracy, the fluctuation of the polymerization reaction causing the change of the various physical properties can be quickly grasped, and the control of the polymerization conditions can be quickly performed. As a result, it is possible to produce products of excellent quality universally and stably. In addition, by storing a desired control mode so as to be changed in a predetermined pattern, the automatic operation of the manufacturing apparatus can be performed.

[0070]

EXAMPLES Examples of the present invention will be described below, but the present invention is not limited to the method and apparatus described below unless departing from the gist of the invention.

Example 1 Using the apparatus shown in FIG. 1, polylactic acid was produced as follows. 50 kg of 90% L-lactic acid and 178 g of metal tin were charged into a reaction vessel (1), and were heated at 140 ° C./1.0 in a nitrogen atmosphere.
The mixture was heated and stirred at 2 × 10 ⁵ pa for 9 hours while distilling water out of the system, and oligomerized. To this, 43 kg of o-dichlorobenzene was added, and while bubbling nitrogen gas,
The mixture was heated to reflux at about 140 ° C./2.66 to 3.33 × 10 ⁴ pa. Thereby, azeotropic dehydration was performed. At this time, the mixture of the azeotropic o-dichlorobenzene and the produced water is separated by a receiver in the dehydrator (6), and the o-dichlorobenzene in the lower phase is prevented so that water droplets do not return to the reaction system. Was always returned to the reaction system.

After the completion of the azeotropic dehydration, the nitrogen gas was continuously bubbled at about 140 ° C./2.66 to 3.33 × 1.
0 ⁴ was heated under reflux while adding appropriate o- dichlorobenzene so as to maintain a predetermined concentration defined by a weight average molecular weight of a given recirculation amount and the reaction mixture (Mw) in pa. At this time, the refluxed mixture of o-dichlorobenzene and generated water is passed through a tube provided in the dehydrator (6) and filled with 20 kg of a dried ion-exchange resin (Levatit S100 manufactured by Bayer AG). After the o-dichlorobenzene became substantially anhydrous, it was returned to the reaction system. Weight average molecular weight (Mw) of reaction mixture
Was about 50,000, the reaction conditions were reduced to about 1
The temperature was changed to 10 ° C./0.80 to 1.20 × 10 ⁴ pa to obtain a predetermined reflux amount and a weight average molecular weight (M
The heating and refluxing was continued while appropriately adding o-dichlorobenzene so as to maintain the predetermined concentration determined by w). At this time, the mixture of the refluxing o-dichlorobenzene and the produced water is subjected to the same treatment by the above-mentioned method, and is returned to the reaction system after the o-dichlorobenzene becomes substantially anhydrous. I did it.

During the period from the azeotropic dehydration to the end of the polymerization, the near-infrared absorption spectrum of the reaction mixture was measured using the circulation pipe (13).
The near-infrared absorption spectrum of the organic solvent taken out from the measuring cell (14) installed in the reactor and refluxed from the reaction system is measured by the measuring cell (14) installed between the receiver (5) and the dehydrator (6). ). This is an optical fiber (15)
And a measuring device (16) including a near-infrared spectrometer, which is installed outside the reaction system and has an analyzer capable of performing multivariate analysis called “InfraspecNR500” manufactured by Yokogawa Electric Corporation. sent.

The near-infrared absorption spectrum of the reaction mixture was measured every 5 hours using this near-infrared spectrometer (16), and the water in the organic solvent distilled out of the reaction system, the terminal group of the reaction mixture, The concentration, moisture, solute concentration and molecular weight were calculated. The analysis equipment included in this includes 9 standard samples.
Using a calibration curve obtained by scanning 240 times at a wavelength step of 2 nm over a wavelength range of 00 to 2,100 nm,
The properties of Table 1 were obtained. For example, in the calculation of the molecular weight, the second derivative spectrum of the near-infrared absorption spectrum of the reaction mixture was used, and a calibration curve with a correlation coefficient of 0.9961 was given in a wavelength region of 900 to 1,800 nm. .

At the same time as the above-described calculation by the near-infrared spectroscopy, the measurement of each physical property value by a conventionally known analysis method was performed in parallel. The results are also shown in Table 1. The measurement of each physical property value by a conventionally known analysis method was performed as follows.

1) Moisture Karl Fischer moisture meter M, manufactured by Kyoto Electronics Industry Co., Ltd.
It measured using KC-210.

2) Terminal Group Concentration of Reaction Mixture Carboxyl groups were calculated by neutralization titration with alkali and measuring the required amount of alkali (mol) per 1 g of sample. Further, the hydroxyl group was esterified with acetic anhydride, and the excess acetic anhydride was neutralized and titrated with alkali, and the required amount of acetic anhydride (mol) per 1 g of the sample was measured by reverse titration and calculated.

3) Solute Concentration A solute concentration was measured by a method of calculating a solute concentration from a peak area value of an elution curve of a predetermined amount of a reaction mixture by gel permeation chromatography according to a previously prepared calibration curve.

4) Molecular Weight (Weight Average Molecular Weight (Mw)) The molecular weight was measured by gel permeation chromatography (column temperature: 40 ° C., chloroform solvent) in comparison with a polystyrene standard sample.

The terminal group concentration obtained by the near infrared spectroscopy described above,
The calculated values of water, solute concentration and molecular weight were transferred to a computer for system control (17), where calculations necessary for control were performed to obtain control information. Based on this information, the temperature, pressure, inert gas flow rate, moisture, concentration, and reflux amount of the reaction tank are controlled via the pressure regulating valve (4), the flow meter (9), and the temperature controller (10). Automatic operation of the manufacturing apparatus was performed. Table 1 shows the control results of the azeotropic dehydration step and the dehydration polycondensation step. In the azeotropic dehydration step, the computer for system control (17) was operated until the number of terminal groups in the reaction mixture became 2 × 10 ⁻⁴ mol / g or less and the water content in the reaction mixture became 100 ppm or less. At that time, the reaction is switched to the dehydration polycondensation reaction. In the dehydration polycondensation reaction, the water content in the o-dichlorobenzene refluxed from the reaction system becomes 5 ppm or less, and the weight average molecular weight (Mw) of the reaction mixture reaches 150,000. Until the end of the reaction, at which point the reaction was stopped. In addition, the temperature, pressure, inert gas flow rate, concentration and reflux amount of the reaction vessel are changed in a predetermined pattern according to the calculated values of the terminal group concentration, moisture, solute concentration and molecular weight according to the progress of both processes. I remembered it.

[0081]

[Table 1]

Example 2 Using the apparatus shown in FIG. 1, polyethylene succinate was produced as follows. Ethylene glycol 29.3
kg, 55.3 kg of succinic acid, and 810 g of tin oxide in a reaction vessel (1), and placed under a nitrogen atmosphere at 150 ° C./1.02×
The mixture was heated and stirred at 10 ⁵ pa for 5 hours while distilling water out of the system to form an oligomer. Diphenyl ether 2
While adding 70 kg, bubbling nitrogen gas, about 1
The mixture was heated to reflux at 40 ° C./2.50 to 4.00 × 10 ³ pa. Thereby, azeotropic dehydration was performed. At this time, the mixture of azeotropic diphenyl ether and generated water is separated by a receiver in the dehydrator (6), and only the lower-phase diphenyl ether is kept in the reaction system without water droplets returning to the reaction system. I put it back.

After the completion of the azeotropic dehydration, the temperature was kept at about 130 ° C./1.50 to 2.50 × 1 while continuously bubbling nitrogen gas.
The mixture was heated to reflux while appropriately adding diphenyl ether so as to maintain a predetermined reflux amount at 0 ³ pa and a predetermined concentration determined by the weight average molecular weight (Mw) of the reaction mixture. At this time, the mixture of the refluxing diphenyl ether and the produced water is passed through a tube provided in the dehydrator (6) and filled with 20 kg of a dried ion-exchange resin (manufactured by Levatit S100, Bayer AG). After it was substantially anhydrous, it was returned to the reaction system. Hereinafter, calculation of each physical property value, calculation of control information, and control of the polymerization reaction were performed in the same manner as in Example-1. Table 2 shows the control results of the azeotropic dehydration step and the dehydration polycondensation step. However, o-dichlorobenzene in Example-1 is to be interpreted as being replaced with diphenyl ether. This system control computer (1)
7) In the azeotropic dehydration step, the reaction is continued until the number of terminal groups in the reaction mixture becomes 2 × 10 ⁻⁴ mol / g or less and the water content in the reaction mixture becomes 250 ppm or less. The reaction is switched to the reaction, and in the dehydration polycondensation reaction, the reaction is continued until the water content in the diphenyl ether refluxed from the reaction system becomes 5 ppm or less and the weight average molecular weight (Mw) of the reaction mixture reaches 155,000. It was remembered to stop. Also used in the near-infrared spectroscopy analyzer set (16) to analyze the water in the organic solvent distilled from the reaction system to be calculated, the terminal group concentration of the reaction mixture, the water, solute concentration and the molecular weight. The calibration curve has been previously derived separately from Example 1. For example, in the calculation of molecular weight, the second derivative spectrum of the near-infrared absorption spectrum of the reaction mixture was used, and the wavelength region of 900 to 1,800 nm was used. And gave a calibration curve with a correlation coefficient of 0.9975.

[0084]

[Table 2]

Example 3 Using the apparatus shown in FIG. 1, a polylactic acid / polyethylene succinate copolymer was produced as follows. 90%
26.7 kg of L-lactic acid and 114 g of metal tin were placed in a reaction tank (1)
At 140 ° C./1.02×10 ⁵ under nitrogen atmosphere
Heating and stirring while distilling water out of the system for 9 hours at pa,
Oligomerized.

23 kg of o-dichlorobenzene was added thereto, and the mixture was added at about 140 ° C./2.
The mixture was heated to reflux at 66 to 3.33 × 10 ⁴ pa. Thereby, azeotropic dehydration was performed. At this time, the mixture of the azeotropic o-dichlorobenzene and the produced water is separated by a receiver in the dehydrator (6), and the o-dichlorobenzene in the lower phase is prevented so that water droplets do not return to the reaction system. Was always returned to the reaction system.

After completion of the azeotropic dehydration, 4.8 kg of polyethylene succinate produced by the method of Example 2 and recovered by a known method and 3.1 kg of additional o-dichlorobenzene were charged into the reaction tank (1). And about 140 ° C./2.66 to 3.33 × 10 while bubbling nitrogen gas.
^The mixture was heated to reflux while appropriately adding o-dichlorobenzene so as to maintain a predetermined reflux amount and a predetermined concentration determined by the weight average molecular weight (Mw) of the reaction mixture at ⁴ pa. At this time, the refluxed mixture of o-dichlorobenzene and generated water is passed through a tube provided in the dehydrator (6) and filled with 20 kg of a dried ion-exchange resin (Levatit S100 manufactured by Bayer AG). After the o-dichlorobenzene became substantially anhydrous, it was returned to the reaction system.

The weight average molecular weight (Mw) of the reaction mixture is
When it reached about 50,000, the reaction condition was reduced to about 110.
° C / 0.80 to 1.20 × 10 ⁴ pa, and o-dichlorobenzene was added as appropriate so as to maintain a predetermined reflux rate and a predetermined concentration determined by the weight average molecular weight (Mw) of the reaction mixture. The heating reflux was continued while heating.
At this time, the mixture of the refluxing o-dichlorobenzene and the produced water is subjected to the same treatment by the above-mentioned method,
-Dichlorobenzene was returned to the reaction system after it became substantially anhydrous. Hereinafter, calculation of each physical property value, calculation of control information, and control of the polymerization reaction were performed in the same manner as in Example-1. Table 3 shows the control results of the azeotropic dehydration step and the dehydration polycondensation step. However, in the near-infrared spectroscopic analyzer set (16), the calculated water content in the organic solvent distilled out of the reaction system, the terminal group concentration of the reaction mixture,
Calibration curves used for analyzing water, solute concentration and molecular weight are derived in advance separately from Example-1 for the dehydration polycondensation step after azeotropic dehydration, and for example, in the calculation of molecular weight, Using the second derivative spectrum of the near-infrared absorption spectrum of the reaction mixture, 900 to 1,80
In the 0 nm wavelength region, a calibration curve having a correlation coefficient of 0.9970 was given.

[0089]

[Table 3]

[0090]

According to the production method of the present invention, a plurality of physical property values can be managed quickly and easily, and the internal disturbance and the external disturbance of the reaction system can be grasped instantaneously. Therefore, the control of the polymerization can be quickly performed, and the polymerization can be smoothly and constantly performed.
As a result, it has become possible to stably produce high-quality aliphatic polyesters.

[Brief description of the drawings]

FIG. 1 shows an example of an apparatus for producing an aliphatic polyester.

[Explanation of symbols]

 1. Reaction tank 2. Capacitor 3. Vacuum generator 4. Pressure regulating valve 5. Receiver 6. 6. A dehydrator for dehydrating an organic solvent to a predetermined moisture value. 7. Inert gas line Organic solvent line 9. Flow meter 10. Temperature controller 11. 11. Heating or cooling jacket for reaction tank Pump 13. Circulation pipe 14. Measurement cell 15. Optical fiber 16. Near infrared spectrometer 17. Computer for system control 18. Stirrer 19. Electric motor

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Koichi Ichise 30 Asamuta-cho, Omuta-shi, Fukuoka Prefecture Mitsui Toatsu Chemicals Co., Ltd.

Claims (9)

[Claims] An aliphatic polyhydric alcohol or a mixture thereof and an aliphatic polybasic acid or a mixture thereof as main raw materials,
Or their oligomers or polymers, and / or
Or a method for producing an aliphatic polyester having a weight average molecular weight of 15,000 or more, wherein a hydroxycarboxylic acid or a mixture thereof, or an oligomer or a polymer thereof is subjected to a dehydration condensation reaction in a reaction mixture containing an organic solvent. A) using a measurement device including a near-infrared spectrometer having an analysis device capable of performing multivariate analysis by chemometrics,
The near-infrared absorption spectrum of the object to be measured during the dehydration condensation reaction is measured, and at least one physical property selected from the number of terminal groups (or terminal group concentration), moisture, concentration, and molecular weight based on the measured data. B) equipment control information is obtained from these calculated values using an arithmetic unit, and c) specific reaction conditions and reaction times are determined by remotely controlling the instrumentation equipment of the reactor based on this information. A method for producing aliphatic polyesters to be controlled. 2. The method according to claim 1, wherein the specific reaction conditions are at least two selected from the temperature, pressure, inert gas flow rate, moisture, concentration, and reflux amount of the reaction tank. 3. The near infrared absorption spectrum of an aliphatic polyester obtained by a near infrared spectrometer, part or all of a spectrum corresponding to a wavelength ranging from 900 nm to 2100 nm, or measurement data thereof. 3. The manufacturing method according to claim 1, wherein data obtained by arithmetically processing is used. 4. The absorbance of a near-infrared absorption spectrum of an object to be measured is 0 in all ranges within a wavelength range used for measurement.
The method according to claim 1, wherein the near-infrared absorption spectrum is measured by adjusting a cell length of the measurement cell so as to fall within the range of abs to 1 abs. 5. The method according to claim 4, wherein the near infrared spectrometer and the measuring cell included in the measuring device are connected by an optical fiber. 6. The method according to claim 1, wherein the aliphatic polyhydric alcohol is an aliphatic diol. 7. The method according to claim 1, wherein the aliphatic polybasic acid is an aliphatic dicarboxylic acid. 8. The method according to claim 1, wherein the hydroxycarboxylic acid is lactic acid, glycolic acid, 3-hydroxybutyric acid, 4-hydroxybutyric acid, 3-hydroxyvaleric acid, or a mixture thereof. 9. The production method according to claim 1, wherein the control of the reaction time is performed by storing the data in an arithmetic unit so as to end when the molecular weight reaches a predetermined value.