JP5729217B2 - Method for producing aliphatic polyester - Google Patents

Description

  The present invention relates to a method for producing an aliphatic polyester, and more particularly to a method for producing an aliphatic polyester having a good color tone.

In recent years, environmental issues have been emphasized, and countermeasures against the problem of environmental burdens on a global scale such as the depletion of fossil fuel raw materials used as plastic raw materials and the increase of carbon dioxide in the atmosphere are necessary.
Against this background, aliphatic polyesters composed of aliphatic dicarboxylic acids and aliphatic diols can be produced from the raw aliphatic dicarboxylic acids, such as succinic acid and adipic acid, from plant-derived glucose using a fermentation method, Group diols such as ethylene glycol, propanediol, butanediol, etc. can be produced from plant-derived raw materials, so that the supply of raw materials becomes irrelevant to the depletion of fossil fuel raw materials, and carbon dioxide is absorbed by plant growth, so carbon dioxide It can greatly contribute to emission reduction and is also expected as a biodegradable plastic.
Aliphatic polyesters can usually be obtained from aliphatic dicarboxylic acids and aliphatic diols through an esterification reaction and a melt polycondensation reaction. Unlike aromatic polyesters such as polyethylene terephthalate, aliphatic polyesters have a thermal stability during melting. Relatively poor, easy to color and difficult to obtain high viscosity.
For this reason, for example, Patent Document 1 proposes to add a trifunctional oxycarboxylic acid and react to increase the viscosity. Patent Document 2 proposes to add a diisocyanate compound to increase the degree of polymerization and increase the viscosity. Patent Document 3 proposes that a phosphorus compound is present during polymerization together with a reaction catalyst, and a biaxial continuous reaction apparatus is used in a high molecular weight process.

: Japanese Patent No. 3079717 : JP-A-5-70543 : JP 2006-274253 A

In the technique of adding a trifunctional oxycarboxylic acid to react and the technique of adding a diisocyanate compound, there is a problem that the viscosity of the polyester is rapidly increased and the viscosity control is difficult, and gel-like foreign matters are easily generated.
In addition, in the technology in which a phosphorus compound is present in the polymerization together with the reaction catalyst and the biaxial continuous reaction apparatus is used in the high molecular weight process, the esterification reaction time is relatively long, and before the specific high molecular weight process is performed. Since it is pelletized and again applied to the polymerization reactor, it is not always an efficient method. The problem to be solved by the present invention is that, in the production of aliphatic polyester, the viscosity of the polyester to be produced can be easily controlled, and an efficient production of a high-viscosity aliphatic polyester with less gel-like foreign matter and less coloration. A method is provided.

In the method for producing an aliphatic polyester in which an aliphatic dicarboxylic acid and an aliphatic diol are used as raw materials and a polyester is obtained through an esterification step and a polycondensation reaction step, the present inventors supply specific components during the reaction. The present inventors have found that a polyester having a good color tone and a high polymerization degree can be obtained. That is, the gist of the present invention is as follows.
(1) A raw material preparation step for mixing an aliphatic dicarboxylic acid and an aliphatic diol, an esterification step for esterifying the raw material in an esterification reaction vessel, and a reaction product obtained in the esterification step in a polycondensation reaction vessel. In the method for producing an aliphatic polyester having a polycondensation reaction step for condensation, at least one reaction vessel selected from an esterification reaction vessel and a polycondensation reaction vessel has a wet condenser, and the aliphatic dicarboxylic acid discharged from the condenser An amount of 3% by weight or more and 15% by weight or less based on the total amount of all the aliphatic diols supplied to the raw material preparation step and the esterification step of the cyclic monomer compound composed of an acid component and an aliphatic diol component, raw material preparation A method for producing an aliphatic polyester to be supplied to any step between the step and the esterification step.
(2) The aliphatic diol contains 1,4-butanediol and is 0.1% by weight based on the total amount of 1,4-butanediol supplied to the raw material preparation step and the esterification step.
The method for producing an aliphatic polyester according to (1), which contains 2- (4′-hydroxybutoxy) tetrahydrofuran in an amount of 0.5% by weight or less.
(3) A distillate obtained from at least one reaction vessel selected from an esterification reaction vessel and a polycondensation reaction vessel is supplied to any step from the raw material preparation step to the esterification step, (1) or ( The manufacturing method of aliphatic polyester as described in 2).
(4) The method for producing an aliphatic polyester according to any one of (1) to (3), wherein the aliphatic polyester is produced continuously .
(5 ) The polycondensation reaction tank has a wet condenser, and the aliphatic polyester low polymer collected in the separator installed between the polycondensation reaction tank and the wet condenser is supplied to the esterification reaction tank. The method for producing an aliphatic polyester according to any one of (1) to ( 4 ).

  According to the present invention, when an aliphatic polyester mainly composed of an aliphatic dicarboxylic acid and an aliphatic diol component is produced, a polyester having a good color tone and a high polymerization degree can be efficiently obtained. Further, by reusing the distillate in the production reaction, a polyester having a higher degree of polymerization and less color can be obtained than in the case of not reusing.

It is a figure which shows an example of the process drawing of the raw material preparation process in this invention. It is a figure which shows an example of the process drawing of the esterification reaction process in this invention. It is a figure which shows an example of the process drawing of the polycondensation reaction process in this invention. It is a figure which shows the partial example of the collection process figure of the distillation system of the polycondensation reaction process in this invention.

The present invention relates to a method for producing an aliphatic polyester having a raw material preparation step, an esterification step, and a polycondensation reaction step using an aliphatic dicarboxylic acid and an aliphatic diol as raw materials, the raw material preparation step and the esterification reaction tank A cyclic monomer compound (hereinafter sometimes abbreviated as CM) in an amount of 3 wt% or more and 15 wt% or less with respect to the total amount of all aliphatic diols supplied to is esterified after the raw material preparation step Supply to any process up to the process.
Here, CM is a cyclic compound formed by dehydration condensation of an aliphatic dicarboxylic acid and an aliphatic diol, and may be referred to as a structural portion derived from an aliphatic dicarboxylic acid (hereinafter referred to as an aliphatic dicarboxylic acid component). ) And a structural portion derived from an aliphatic diol (hereinafter sometimes referred to as an aliphatic dicarboxylic acid component), and is a compound having only one aliphatic dicarboxylic acid component and one aliphatic diol component. .

<Dicarboxylic acid>
The aliphatic dicarboxylic acid according to the present invention can be used without particular limitation as long as it is usually used as a raw material for polyester. More specifically, an aliphatic hydrocarbon having two carboxyl groups is used as the aliphatic hydrocarbon, and the aliphatic hydrocarbon is a linear aliphatic hydrocarbon or a branched aliphatic hydrocarbon. Alternatively, a cyclic aliphatic hydrocarbon (alicyclic hydrocarbon) may be used, but a linear aliphatic hydrocarbon is preferably used. As the aliphatic dicarboxylic acid according to the present invention, a compound having an aliphatic hydrocarbon preferably having 2 to 40 carbon atoms, more preferably 20 or less carbon atoms, still more preferably 12 or less carbon atoms, Particularly preferably, a compound in which two carboxyl groups are bonded to an aliphatic hydrocarbon having 8 or less carbon atoms is used. For example, oxalic acid, malonic acid, succinic acid, succinic anhydride, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecadicarboxylic acid, dodecadicarboxylic acid, dimer acid, hexahydrophthalic acid, Hexahydroisophthalic acid, hexahydroterephthalic acid and the like can be mentioned, and among these, succinic acid, succinic anhydride, adipic acid and sebacic acid are preferable from the viewpoint of the physical properties of the resulting polyester. In particular, succinic acid and succinic anhydride are preferable. Two or more of these may be used in combination.

  When succinic acid is used as the dicarboxylic acid, the amount of succinic acid used is 50 mol% or more based on the total aliphatic dicarboxylic acid from the viewpoint of the melting point (heat resistance), biodegradability and mechanical properties of the resulting polyester. It is preferably 70 mol% or more, more preferably 90 mol% or more.

Moreover, in the manufacturing method of the aliphatic polyester of this invention, you may use together dicarboxylic acid other than aliphatic dicarboxylic acid as a raw material. In this case, the amount of the dicarboxylic acid other than the aliphatic dicarboxylic acid used in combination is in a range not exceeding the molar ratio of the aliphatic dicarboxylic acid in terms of the molar ratio with respect to the whole dicarboxylic acid. Among these, from the viewpoint of the physical properties and biodegradability of the polyester, the total of the aliphatic dicarboxylic acids is preferably 50 mol% or more, more preferably 60 mol% or more, still more preferably based on the total of the raw material dicarboxylic acids. Is 70%, particularly preferably 90% or more.
Examples of dicarboxylic acids other than aliphatic dicarboxylic acids include aromatic dicarboxylic acids. As the aromatic dicarboxylic acid, those having 2 or less aromatic rings are preferable, and aromatic dicarboxylic acids having one aromatic ring are more preferable. Specific examples include terephthalic acid, isophthalic acid, 4,4′-diphenyldicarboxylic acid, 4,4′-diphenyl ether dicarboxylic acid, 4,4′-benzophenone dicarboxylic acid, and 4,4′-diphenoxyethanedicarboxylic acid. 4,4′-diphenylsulfone dicarboxylic acid, 2,6-naphthalenedicarboxylic acid, and the like are preferable, and terephthalic acid and isophthalic acid are more preferable. These may be used alone or as a mixture of two or more thereof in addition to the aliphatic dicarboxylic acid. In addition, the dicarboxylic acid used in the present invention may be derived from a compound derived from petroleum or may be derived from a compound derived from a plant raw material, but is derived from a plant raw material. It is preferable to include those derived from the prepared compounds. In particular, it preferably contains succinic acid, succinic anhydride, adipic acid, and sebacic acid derived from plant raw materials.

<Diol>
The aliphatic diol according to the present invention can be used without particular limitation as long as it is usually used as a raw material for polyester, but more specifically, an aliphatic hydrocarbon or ether bond group having two hydroxyl groups. The aliphatic hydrocarbons are linked by a cyclic aliphatic hydrocarbon (aliphatic hydrocarbon), whether it is a straight chain aliphatic hydrocarbon or a branched aliphatic hydrocarbon. A compound having 2 to 20 carbon atoms, more preferably 12 carbon atoms, which may be a cyclic hydrocarbon).
In the following, a compound in which two hydroxyl groups are bonded to an aliphatic hydrocarbon having 6 or less carbon atoms is used. In addition, when the aliphatic hydrocarbon is connected by an ether bond group, the number of carbon atoms connected is preferably in the above range. For example, ethylene glycol, diethylene glycol, polyethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, polypropylene glycol, polytetramethylene glycol, dibutylene glycol, 1,5-pentanediol, Aliphatic diols such as neopentyl glycol, 1,6-hexanediol, 1,8-octanediol, 1,2-cyclohexanediol, 1,4-cyclohexanediol, 1,1-cyclohexanedimethylol, 1,4-cyclohexane Examples include alicyclic diols such as dimethylol, isosorbide, isomannide, isoidet, erythritan, and various tricyclodecane dimethanols.
Among these, a linear aliphatic hydrocarbon having 4 or less carbon atoms in a hydrocarbon moiety having two hydroxyl groups is preferable, and 1,4-butanediol is more preferable. In particular, the aliphatic diol is 1,4-butanediol, and is 0.1% by weight to 0.8% based on the total amount of 1,4-butanediol supplied to the raw material preparation step and the esterification reaction tank. 5% by weight of 2- (4′-
It is preferable to use 1,4-butanediol containing hydroxybutoxy) tetrahydrofuran (hereinafter sometimes abbreviated as HBTF).

Moreover, in the manufacturing method of the aliphatic polyester of this invention, you may use together diols other than said aliphatic diol as a raw material. In this case, the amount of diol other than the aliphatic diol used in combination is in a range not exceeding the molar ratio of the aliphatic diol in terms of the molar ratio relative to the whole diol. Among these, from the viewpoints of polyester physical properties and biodegradability, the total of aliphatic diols is preferably 50 mol% or more, more preferably 60 mol% or more, still more preferably, based on the total of raw material diols. 70%, particularly preferably 90% or more.
Examples of diols other than aliphatic diols include aromatic diols. As the aromatic diol, those having 2 or less aromatic rings are preferable, and aromatic diols having one aromatic ring are more preferable. Specific examples include aromatic diols such as xylylene glycol, 4,4′-dihydroxybiphenyl, 2,2-bis (4-hydroxyphenyl) propane, and bis (4-hydroxyphenyl) sulfone.
Two or more of these diols may be used in combination. As the diol, 1,4-butanediol can be particularly preferably used from the viewpoints of industrial availability, reactivity, and physical properties of the resulting polyester. When 1,4-butanediol is used, the amount of 1,4-butanediol used is 50 moles with respect to the total aliphatic diol from the viewpoint of the melting point (heat resistance), biodegradability, and mechanical properties of the resulting polyester. % Or more, more preferably 70 mol% or more, particularly preferably 90 mol% or more.
In addition, the diol used in the present invention may be derived from a compound derived from petroleum or may be derived from a compound derived from a plant material, but is derived from a plant material. It is preferable to include those derived from the above compounds. In particular, diols derived from plant materials such as isosorbide, isomannide, isoidet, and erythritan can be exemplified. Ethylene glycol, 1,3-propanediol, 1,4-butanediol and the like are also derived from plant materials. Can be used.

<Other copolymer components>
The polyester of the present invention may be copolymerized with other components other than the dicarboxylic acid and the diol. Examples of copolymer components that can be used in this case include lactic acid, glycolic acid, hydroxybutyric acid, hydroxycaproic acid, 2-hydroxy3,3-dimethylbutyric acid, 2-hydroxy-3-methylbutyric acid, and 2-hydroxyisocaprone. Oxycarboxylic acids such as acid, malic acid, maleic acid, citric acid and fumaric acid, and esters or lactones of these oxycarboxylic acids, oxycarboxylic acid polymers, etc., or trifunctional or more functional groups such as glycerin, trimethylolpropane and pentaerythritol Or polyhydric carboxylic acids having three or more functional groups such as propanetricarboxylic acid, pyromellitic acid, trimellitic acid benzophenone tetracarboxylic acid and anhydrides thereof, or the like. Further, tri- or higher-functional oxycarboxylic acid, tri- or higher-functional alcohol, tri- or higher-functional carboxylic acid, and the like can be easily obtained by adding a small amount of polyester. Of these, oxycarboxylic acids such as malic acid, citric acid, and fumaric acid are preferable, and malic acid is particularly preferably used.

  The trifunctional or higher polyfunctional compound is preferably 0.001 to 5 mol%, more preferably 0.05 to 0.5 mol%, based on the total dicarboxylic acid. If the upper limit of this range is exceeded, gel (unmelted product) is likely to be formed in the obtained polyester, and if it is less than the lower limit, it is possible to increase the viscosity of the resulting polyester (usually by using a polyfunctional compound). ) Is difficult to obtain.

<Manufacture of polyester>
In the present invention, each reaction in producing the polyester can be carried out by a batch method or a continuous method. From the viewpoints of quality stabilization and energy efficiency, the raw materials are continuously supplied to obtain the polyester continuously. A so-called continuous process is preferred.
The polyester production method of the present invention will be described below by taking a continuous production method as an example, but the present invention is not limited to this unless it exceeds the gist of the present invention.

  In the present invention, in the continuous method, a polyester can be continuously obtained through an esterification reaction step and a melt polycondensation reaction step using a plurality of continuous esterification reaction vessels and polycondensation reaction vessels.

(Raw material preparation process)
The raw material aliphatic dicarboxylic acid, aliphatic diol, and the like are mixed in advance in the raw material preparation step into a slurry or liquid fluid before being subjected to the esterification reaction step.
In this case, the lower limit of the molar ratio of the aliphatic diol to the aliphatic dicarboxylic acid is usually 1.10, preferably 1.12, more preferably 1.15, and particularly preferably 1.20. The upper limit is usually 2.00, preferably 1.80, more preferably 1.60, particularly preferably 1.55. While the raw materials are being mixed, the dicarboxylic acid and the diol may cause an esterification reaction, but in the present invention, it does not prevent a partial esterification reaction from occurring during the raw material preparation step. However, the mixing temperature is preferably higher than the melting point of the aliphatic diol, and the temperature at which the esterification reaction does not proceed remarkably. The upper limit is usually 70 ° C., preferably 60 ° C., more preferably 50 ° C., particularly preferably 40 ° C. .

(Esterification reaction process)
The esterification reaction step in the present invention is a step of performing esterification by reacting a raw material dicarboxylic acid and a diol, but even if a partial esterification reaction has occurred, the raw material preparation step is an esterification step. Are distinguished. More specifically, the esterification step refers to a step in which the esterification rate at the reaction vessel outlet is 50% or more, and the reaction vessel in this case is referred to as an esterification reaction vessel. The esterification reaction may be performed in a plurality of reaction vessels. Even in this case, a reaction vessel having an esterification rate of 50% or more at each reaction vessel outlet is referred to as an esterification reaction vessel.
The esterification reaction of dicarboxylic acid and diol can be performed in a plurality of continuous reaction tanks, but can also be performed in one tank. The lower limit of the reaction temperature is usually 200 ° C, preferably 210 ° C, and the upper limit is usually 250 ° C, more preferably 245 ° C, more preferably 240 ° C. If it is less than the lower limit, the esterification reaction rate is slow, requiring a long reaction time, and an undesirable reaction such as dehydration decomposition of aliphatic diol may occur. If the upper limit is exceeded, the aliphatic diol and the aliphatic dicarboxylic acid will be decomposed more, and the amount of scattered matter will increase in the reaction tank, causing foreign matter to be easily generated, and the reaction product tends to become cloudy (haze). The esterification temperature is preferably a constant temperature. The esterification rate is stabilized due to the constant temperature. The constant temperature is a set temperature ± 5 ° C., preferably ± 2 ° C.

  The reaction atmosphere is usually an inert gas atmosphere such as nitrogen or argon. The reaction pressure is usually 50 kPa to 200 kPa, and the lower limit is preferably 60 kPa, more preferably 70 kPa, and the upper limit is preferably 130 kPa, more preferably 110 kPa. If it is less than the lower limit, the amount of scattered matter in the reaction tank increases and the haze of the reaction product increases, which tends to cause an increase in foreign matter. . If the upper limit is exceeded, the dehydration decomposition of the aliphatic diol increases, and the polycondensation rate tends to decrease.

  The reaction time is usually 1 hour or longer, and the upper limit is usually 10 hours or shorter, preferably 4 hours or shorter. The molar ratio of the aliphatic diol to the aliphatic dicarboxylic acid for carrying out the esterification reaction is determined based on the aliphatic dicarboxylic acid and the esterified aliphatic dicarboxylic acid present in the gas phase and reaction liquid phase of the esterification reactor. It represents the molar ratio between the diol and the esterified aliphatic diol, and does not include aliphatic dicarboxylic acids, aliphatic diols and their decomposition products that are decomposed in the reaction system and do not contribute to the esterification reaction. The fact that it is decomposed and does not contribute to the esterification reaction does not include, for example, those in which 1,4-butanediol, which is an aliphatic diol, is decomposed into tetrahydrofuran, in this molar ratio. In the present invention, the lower limit of the molar ratio is usually 1.10, preferably 1.12, more preferably 1.15, and particularly preferably 1.20. The upper limit is usually 2.00, preferably 1.80, more preferably 1.60, particularly preferably 1.55. If it is less than the lower limit, the esterification reaction tends to be insufficient, and the polycondensation reaction which is a reaction in the subsequent step is difficult to proceed, and it is difficult to obtain a polyester having a high polymerization degree. If the upper limit is exceeded, the decomposition amount of the aliphatic diol and aliphatic dicarboxylic acid increases. In order to keep this molar ratio within a preferable range, it is a preferable method to appropriately supplement the esterification reaction system with an aliphatic diol.

In the present invention, CM is supplied to at least one of the steps from the raw material preparation step to the esterification step. The aliphatic dicarboxylic acid component and the aliphatic diol component constituting this CM are derived from their origins. As the aliphatic dicarboxylic acid or aliphatic diol, the above-mentioned molar ratio is included.
In the present invention, an esterification reaction product having an esterification rate of 80% or more is subjected to a polycondensation reaction. In the present invention, the polycondensation reaction means a high molecular weight reaction of polyester performed at a reaction pressure of 50 kPa or less, the esterification reaction is 50 to 200 kPa, usually performed in an esterification reaction tank, and the polycondensation reaction is 50 kPa or less, preferably It is carried out in a polycondensation reaction tank at 10 kPa or less. In the present invention, the esterification rate indicates the ratio of the esterified acid component to the total acid component in the esterification reaction product sample, and is represented by the following formula.

Esterification rate (%) = (saponification value−acid value) / saponification value × 100

  The esterification rate of the esterification reaction product is preferably 85% or more, more preferably 88% or more, and particularly preferably 90% or more. If it is less than the lower limit, the polycondensation reactivity, which is a reaction in the subsequent step, is deteriorated. Further, the amount of scattered matter during the polycondensation reaction increases, adheres to the wall surface and solidifies, and further, this scattered matter falls into the reaction material, causing haze deterioration (foreign matter generation). The upper limit is preferably 99% for the polycondensation reaction, which is a post-process reaction, but is usually 99%.

  In the present invention, the haze is reduced by performing a continuous reaction with the molar ratio of dicarboxylic acid and diol in the esterification reaction, reaction temperature, reaction pressure and reaction rate within the above ranges and continuously subjecting to a polycondensation reaction. A high-quality polyester with few foreign substances can be obtained efficiently.

(Polycondensation reaction process)
The polycondensation reaction step in the present invention is a step of polycondensation of the reaction product obtained through the esterification step, but is distinguished from the esterification step even if some esterification reaction occurs in the step. Is done. More specifically, the polycondensation reaction step refers to a step in which the esterification rate of the reaction product obtained through the esterification step charged into the reaction vessel is 80% or more. Called the tank.
The polycondensation reaction can be performed under reduced pressure using a plurality of continuous reaction vessels. Regarding the reaction pressure of the final polycondensation reaction tank, the lower limit is usually 0.01 kPa or more, preferably 0.03 kPa or more, and the upper limit is usually 1.4 kPa or less, preferably 0.4 kPa or less. If the pressure during the polycondensation reaction is too high, the polycondensation time will be prolonged, and accordingly, the molecular weight will be lowered or colored due to thermal decomposition of the polyester, which tends to make it difficult to produce a polyester exhibiting practically sufficient characteristics.

  On the other hand, the method of producing using an ultra-high vacuum polycondensation equipment with a reaction pressure of less than 0.01 kPa is a preferred embodiment from the viewpoint of improving the polycondensation reaction rate, but requires extremely expensive equipment investment. Therefore, it is economically disadvantageous. The lower limit of the reaction temperature is usually 215 ° C, preferably 220 ° C, and the upper limit is usually in the range of 270 ° C, preferably 260 ° C. If it is less than the lower limit, the polycondensation reaction rate is slow, and not only a long time is required for producing a polyester having a high degree of polymerization, but also a high power stirrer is required, which is economically disadvantageous. On the other hand, if the amount exceeds the upper limit, thermal decomposition of the polyester during production tends to be caused, and it tends to be difficult to produce polyester having a high degree of polymerization.

  The lower limit of the reaction time is usually 1 hour, and the upper limit is usually 15 hours, preferably 10 hours, more preferably 8 hours. If the reaction time is too short, the reaction is insufficient and it is difficult to obtain a polyester having a high degree of polymerization, and the mechanical properties of the molded product tend to be inferior. On the other hand, if the reaction time is too long, the molecular weight drop due to the thermal decomposition of the polyester becomes remarkable, the mechanical properties of the molded product tend to be inferior, and the terminal amount of the carboxyl group that adversely affects the durability of the polyester is thermally decomposed. May increase due to

  A polyester having a desired intrinsic viscosity can be obtained by controlling the polycondensation reaction temperature, time and pressure.

(Supply of cyclic monomeric compound (CM))
In the present invention, 3 to 15% by weight of CM is supplied to at least one of the steps after the raw material preparation step to the esterification step with respect to the total aliphatic diol used as the raw material. . The amount of CM added to the aliphatic diol is preferably 5% by weight, more preferably 8% by weight, and the upper limit is preferably 12% by weight, more preferably 10% by weight. When the CM content is less than the lower limit, the color tone b value of the obtained polyester tends to increase and become inferior. If the amount exceeds the upper limit, the distillate distilled from the esterification reaction tank and the polycondensation reaction tank has a large amount of clogging distillate, which tends to cause pipe clogging.

  CM in the present invention can be obtained by reacting an aliphatic dicarboxylic acid and an aliphatic diol in an aliphatic diol. A specific example of CM is a cyclic monomer compound composed of succinic acid as an aliphatic dicarboxylic acid and 1,4-butanediol as an aliphatic diol, and can be quantitatively measured by gas chromatography or liquid chromatography. It is.

Further, an aliphatic diol distilled from each reaction tank in the esterification reaction and polycondensation reaction, and CM in a distillate containing water as a main component can also be used. In this case, since the distillate from the polycondensation reaction tank has a high CM concentration and is liquid, it is stored or directly added to the raw material aliphatic diol or the raw material preparation step or the esterification reaction step. It is an efficient method to use it in an appropriate amount.

(Reaction catalyst)
The esterification reaction and polycondensation reaction are promoted by using a reaction catalyst. In the esterification reaction, a sufficient reaction rate can be obtained without an esterification reaction catalyst. In addition, if an esterification reaction catalyst is present during the esterification reaction, the catalyst may cause insoluble precipitates in the reaction product due to water generated by the esterification reaction, which may impair the transparency of the resulting polyester (ie, increase haze). Moreover, since it may become a foreign material, it is preferable not to use the reaction catalyst during the esterification reaction. Moreover, when a catalyst is added to the gas phase part of the reaction vessel, the haze may be increased, and the catalyst may be converted into a foreign substance.

  In the polycondensation reaction, it is difficult to proceed without a catalyst, and it is preferable to use a catalyst. As the polycondensation reaction catalyst, a metal compound containing at least one of the metal elements of Groups 1 to 14 of the periodic table is generally used. Specific examples of metal elements include scandium, yttrium, samarium, titanium, zirconium, vanadium, chromium, molybdenum, tungsten, tin, antimony, cerium, germanium, zinc, cobalt, manganese, iron, aluminum, magnesium, calcium, Examples include strontium, sodium and potassium. Among them, scandium, yttrium, titanium, zirconium, vanadium, molybdenum, tungsten, zinc, iron, and germanium are preferable, and titanium, zirconium, tungsten, and germanium are particularly preferable. Furthermore, in order to reduce the polyester terminal density | concentration which affects the thermal stability of polyester, among the said metals, the periodic table 3-6 metal element which shows Lewis acidity is preferable. Specifically, scandium, titanium, zirconium, vanadium, molybdenum, and tungsten are preferable, and titanium and zirconium are particularly preferable from the viewpoint of availability, and titanium is more preferable from the viewpoint of reaction activity.

In the present invention, as a catalyst, a compound containing an organic group such as a carboxylate salt, an alkoxy salt organic sulfonate salt or a β-diketonate salt containing these metal elements, and the above-described metal oxide, halide, etc. Inorganic compounds and mixtures thereof are preferably used.
In the present invention, the catalyst is preferably a liquid at the time of polymerization or a compound that dissolves in an ester low polymer or polyester because the polymerization rate is increased when the catalyst is melted or dissolved at the time of polymerization. The polycondensation is preferably carried out without a solvent. Alternatively, a small amount of solvent may be used to dissolve the catalyst. Examples of the solvent for dissolving the catalyst include alcohols such as methanol, ethanol, isopropanol, and butanol, diols such as ethylene glycol, butanediol, and pentanediol, ethers such as diethyl ether and tetrahydrofuran, and nitriles such as acetonitrile. , Hydrocarbon compounds such as heptane and toluene, water and mixtures thereof, and the like. The amount used is usually such that the catalyst concentration is 0.0001 wt% or more and 99 wt% or less.

  As the titanium compound, tetraalkyl titanate and a hydrolyzate thereof are preferable. Specifically, tetra-n-propyl titanate, tetraisopropyl titanate, tetra-n-butyl titanate, tetra-t-butyl titanate, tetraphenyl titanate, Examples include tetracyclohexyl titanate, tetrabenzyl titanate and mixed titanates thereof, and hydrolysates thereof.

In addition, titanium (oxy) acetylacetonate, titanium tetraacetylacetonate, titanium (diisoproxide) acetylacetonate, titanium bis (ammonium lactate) dihydroxide, titanium bis (ethylacetoacetate) diisopropoxide, titanium (triethanolaminate) ) Isopropoxide, polyhydroxytitanium stearate, titanium lactate, titanium triethanolamate, butyl titanate dimer and the like are also preferably used. Moreover, the liquid substance obtained by mixing alcohol, an alkaline-earth metal compound, a phosphate ester compound, and a titanium compound is also used. Among these, tetra-n-propyl titanate, tetraisopropyl titanate and tetra-n-butyl titanate, titanium (oxy) acetylacetonate, titanium tetraacetylacetonate, titanium bis (ammonium lactate) dihydroxide, polyhydroxytitanium stearate Preferred is a liquid obtained by mixing rate, titanium lactate, butyl titanate dimer, and alcohol, alkaline earth metal compound, phosphate ester compound, and titanium compound. Tetra-n-butyl titanate, titanium (oxy) Acetyl acetonate, titanium tetraacetyl acetonate, polyhydroxy titanium stearate, titanium lactate, butyl titanate dimer and alcohol, alkaline earth metal compound A liquid obtained by mixing an acid ester compound and a titanium compound is more preferable, in particular, tetra-n-butyl titanate, polyhydroxy titanium stearate, titanium (oxy) acetylacetonate, titanium tetraacetylacetonate, and A liquid material obtained by mixing an alcohol, an alkaline earth metal compound, a phosphate ester compound, and a titanium compound is preferable.

  Specific examples of the zirconium compound include zirconium tetraacetate, zirconium acetylate hydroxide, zirconium tris (butoxy) stearate, zirconyl diacetate, zirconium oxalate, zirconyl oxalate, potassium potassium oxalate, and polyhydroxyzirconium. Examples include stearate, zirconium ethoxide, zirconium tetra-n-propoxide, zirconium tetraisopropoxide, zirconium tetra-n-butoxide, zirconium tetra-t-butoxide, zirconium tributoxyacetylacetonate and mixtures thereof. Among these, zirconyl diacetate, zirconium tris (butoxy) stearate, zirconium tetraacetate, zirconium acetate acetate, zirconium ammonium oxalate, zirconium potassium oxalate, polyhydroxyzirconium stearate, zirconium tetra-n- Propoxide, zirconium tetraisopropoxide, zirconium tetra-n-butoxide, zirconium tetra-t-butoxide are preferred, zirconyl diacetate, zirconium tetraacetate, zirconium acetate acetate hydroxide, zirconium tris (butoxy) stearate, sulphur Zirconium ammonium acid, zirconium tetra-n-propoxide, zirconium tetra-n-butoxide are more preferred, Preferred for reasons of zirconium tris (butoxy) stearate is easily obtained polyester having a high degree of polymerization without colored.

  Specific examples of the germanium compound include inorganic germanium compounds such as germanium oxide and germanium chloride, and organic germanium compounds such as tetraalkoxygermanium. From the viewpoint of price and availability, germanium oxide, tetraethoxygermanium and mu and tetrabutoxygermanium are preferable, and germanium oxide is particularly preferable.

When these metal compounds are used as a polycondensation catalyst, the amount of the catalyst added is usually 0.1 mass ppm or more, preferably 0.5 mass ppm or more, more preferably 1 as the metal amount with respect to the produced polyester. The upper limit is usually 3000 ppm or less, preferably 1000 ppm or less, more preferably 250 ppm or less, and particularly preferably 130 ppm or less. If too much catalyst is used, it is not only economically disadvantageous, but the reason is not yet clear, but the carboxyl group terminal concentration in the polyester may increase, so the carboxyl group terminal amount and residual catalyst concentration. The increase in the temperature may reduce the thermal stability and hydrolysis resistance of the polyester. On the other hand, if the amount is too small, the polymerization activity is lowered, and accordingly, thermal decomposition of the polyester is induced during the production of the polyester,
Polyesters showing practically useful physical properties are difficult to obtain.

  The position of addition of the catalyst to the reaction system is not particularly limited as long as it is before the polycondensation reaction step, and may be added at the time of charging the raw material, but the catalyst is used in a situation where a lot of water is present or generated. If it coexists, the catalyst is deactivated and foreign matter may be precipitated, which may impair the quality of the product. Therefore, it is preferably added after the esterification reaction step.

<Reaction tank>
(Esterification reaction tank)
As the esterification reaction tank used in the present invention, known ones can be used, and any of a vertical stirring complete mixing tank, a vertical heat convection mixing tank, a tower type continuous reaction tank, etc. may be used. A single tank or a plurality of tanks in which similar or different tanks are connected in series may be used. Among them, a reaction tank having a stirrer is preferable. As a stirrer, in addition to a normal type including a power unit, a receiver, a shaft, and a stirring blade, a turbine stator type high-speed rotary stirrer, a disk mill type stirrer, a rotor mill type stirrer, etc. The type that rotates at a high speed can also be used.

  There is no limitation on the form of stirring, and in addition to the normal stirring method in which the reaction liquid in the reaction tank is directly stirred from the top, bottom, side, etc. of the reaction tank, a part of the reaction liquid is piped outside the reaction tank It is possible to take a method of circulating the reaction liquid by taking it out with a line mixer and the like. Known types of stirring blades can be selected, and specific examples include propeller blades, screw blades, turbine blades, fan turbine blades, disk turbine blades, fouller blades, full zone blades, Max blend blades, and the like.

(Polycondensation reaction tank)
There is no restriction | limiting in particular in the type of the polycondensation reaction tank used for this invention, For example, a vertical stirring polymerization tank, a horizontal stirring polymerization tank, a thin film evaporation type polymerization tank etc. can be mentioned. The number of polycondensation reaction tanks can be one, or a plurality of tanks of the same or different types can be connected in series. It is preferable to select a horizontal stirring polymerization machine having a thin film evaporation function excellent in renewability, plug flow property, and self-cleaning property.

(Condenser)
As the condenser used in the present invention, known ones such as a water cooling type, an air cooling type, and an evaporation type can be used. For example, as a water cooling type, a shell-and-tube condenser and a double pipe condenser are used as an air cooling type. A plate fin tube condenser can be used, and an evaporation condenser or the like can be adopted as an evaporation type. The condenser of the present invention may be provided in one or both of the ester tank and the polycondensation reaction tank, or may be provided in plural. Moreover, it is preferable that at least one of the condensers is a wet condenser, and it is preferable that the condenser be condensed with an aliphatic diol.
As a wet capacitor, one or more shelves are provided, and for example, 1,4-butanediol is circulated and flowed down as a cooling liquid from above to generate a liquid film, and exhaust is brought into contact with the liquid film. A method using a shelf type for dissolving and collecting process scattered matters, a shower nozzle is provided above, and for example, 1,4-butanediol is sprayed as a cooling liquid, and the process scattered matters are brought into contact with the liquid droplets by exhaust. There are a method using a shower type that dissolves and collects, a combination of a shelf type and a shower type, a method in which the shelf type is arranged at the top and the shower type is arranged at the bottom, and any of them may be used.
The CM discharged from the condenser according to the present invention is preferably supplied anywhere between the raw material preparation step and the esterification step. Moreover, it is preferable that there is a separator between the condenser of the present invention and the polycondensation reaction tank, and it is a preferable aspect to supply the low polymer collected in the separator to the esterification reaction tank.

<Example of manufacturing process>
As an example, a method for producing a polyester using succinic acid as an aliphatic dicarboxylic acid, 1,4-butanediol (hereinafter sometimes abbreviated as BD) as an aliphatic diol, and malic acid as a polyfunctional compound. Although a preferred embodiment will be described, the present invention is not limited to this.

  Hereinafter, preferred embodiments of a method for producing polyester will be described with reference to the accompanying drawings. FIG. 1 is an explanatory diagram of an example of a raw material preparation process employed in the present invention, FIG. 2 is an explanatory diagram of an example of an esterification reaction process employed in the present invention, and FIG. 3 is an example of a polycondensation process employed in the present invention. It is explanatory drawing of. FIG. 4 is an explanatory view of an example of a distillation system in the polycondensation step employed in the present invention.

In FIG. 1, succinic acid is supplied from the raw material supply line (1), BD and malic acid are supplied from the raw material supply line (2), and a BD solution of CM is supplied from the raw material supply line (3) to the raw material preparation tank (A). The raw material slurry is prepared by stirring and mixing, and sent to the raw slurry storage tank (B) from the slurry lines (4), (6) and the pump (C). A part of the slurry is circulated from the slurry line (5) to the raw material preparation tank (A). Here, an example is shown in which CM is supplied from the line (3). However, the CM may be supplied from the raw material supply line (10) to the raw material slurry storage tank (B) and the esterification reaction tank (E) (the supply line is illustrated). Absent). The slurry in the storage tank (B) is stirred and mixed using the pump (D) while the slurry is circulated through the slurry extraction line (7) and the circulation line (8) and held. The prepared slurry is supplied from the storage tank (B) to the esterification reaction tank (E) through the slurry supply line (9). The raw material malic acid can be added as a solid to the slurry preparation tank from the raw material supply line (1), or added to the slurry supply line (9) as a BD solution or BD slurry from the raw material supply line (10). You can also
Moreover, when adding a catalyst at the time of esterification, after making it the solution of BD with a catalyst adjustment tank (not shown), it is made by supplying a solution to a supply line (24). In FIG. 1, the supply line (24) is connected to the recirculation line (22) of the recirculated 1,4-butanediol, and both are mixed and then supplied to the liquid phase part of the esterification reaction tank (E). Indicated. The low molecular weight component containing CM distilled from the polycondensation reactor and collected in the separator (g, h, j) is fed to the recycle line (22) for recycle 1,4-butanediol. It can also add to an esterification reaction tank (E) from a line (24).

  The gas distilled from the esterification reaction tank (E) is separated into a high-boiling component and a low-boiling component in the rectification tower (F) through the distillation line (13). Usually, the main component of the high boiling component is BD, and the main component of the low boiling component is water and tetrahydrofuran (hereinafter sometimes abbreviated as THF) which is a decomposition product of BD.

  The high-boiling components separated in the rectification column (F) are extracted from the extraction line (20), passed through the pump (J), and partly from the BD recirculation line (22) to the esterification reaction tank (E). And a part is returned to the rectification column (F) from the circulation line (21). The surplus is withdrawn from the extraction line (23) to the outside (not shown). On the other hand, the light boiling components separated in the rectification column (F) are extracted from the gas extraction line (14), condensed in the condenser (G), and temporarily passed through the condensate line (16) to the tank (H). Can be stored. A part of the light boiling components collected in the tank (H) is returned to the rectification column (F) through the extraction line (17), the pump (K) and the circulation line (18), and the remainder is extracted. It is extracted outside through the line (19). The condenser (G) is connected to an exhaust device (not shown) through a vent line (15). The esterification reaction product generated in the esterification reaction vessel (E) is supplied to the first polycondensation reaction vessel (L) in FIG. 2 via the extraction pump (I) and the extraction line (12) of the esterification reaction product. Is done.

In the process shown in FIG. 1, the supply line (24) is connected to the recirculation line (22), but both may be independent. The raw material supply line (9) is an esterification reaction tank (
It may be connected to the liquid phase part of E).

  When a catalyst is added to the esterification reaction product before the polycondensation tank, it is adjusted to a predetermined concentration in a catalyst preparation tank (not shown), and then the esterification reaction product is removed through the catalyst supply line (28) in FIG. Supplied to the exit line (12).

  Next, the esterification reactant supplied to the first polycondensation reaction tank (L) through the filter (R) from the esterification reactant extraction line (12) shown in FIG. 3 is polycondensed under reduced pressure. After that, it becomes a polyester low polymer, and is then supplied to the second polycondensation reaction tank (M) through the extraction gear pump (O), the extraction line (30), and the filter (S). In the second polycondensation reaction tank (M), the polycondensation reaction usually proceeds at a lower pressure than the first polycondensation reaction tank (L). The obtained polycondensate is supplied to the third polycondensation tank (N) through the extraction gear pump (P), the extraction line (31) serving as the outlet channel, and the filter (T). The third polycondensation reaction tank (N) is a horizontal reaction tank composed of a plurality of stirring blade blocks and equipped with a biaxial self-cleaning type stirring blade. The polycondensation reaction product introduced into the third polycondensation reaction tank (N) from the second polycondensation reaction tank (M) through the extraction line (31) is further pelletized after further polycondensation reaction is advanced here. Is done. The filters R, S, T, and U are not necessarily all installed, and can be appropriately installed in consideration of the foreign matter removing effect and the operation stability.

  The melted polyester is extracted into the atmosphere in the form of a melted strand from the die head (V) via the extraction gear pump (Q), the extraction line (32) which is the outlet channel, and the filter (U). After cooling with water or the like, it is cut with a rotary cutter (W) to form polyester pellets. Further, it can be extracted in the form of a strand into the water without being extracted into the atmosphere, and cut into a pellet by a rotary underwater cutter.

The distillation lines (25), (26), and (27) shown in FIGS. 3 and 4 are respectively a first polycondensation reaction tank (L), a second polycondensation reaction tank (M), and a third polycondensation reaction. It is a vent line of a tank (N). The distillate distilled from the polycondensation reaction tanks (L), (M), and (N), respectively, is a separator (g) having a cooling function via the distillation lines (25), (26), and (27), In (h) and (i), the liquid component and the gas component are separated and the liquid component is supplied to the esterification reaction tank (E) through the recovery line (48) and the supply line (24), or into the slurry preparation tank through the raw material supply line. Can be returned.
The gas component is condensed in wet capacitors (a), (b), and (c) attached to each reactor. The condensed distillate is stored in the tanks (d), (e), and (f), and is sent to the wet condenser again as a circulation BD to be used as a spray liquid for condensing the distillate. Since the distillate contains water and THF produced by the reaction, CM and other oligomers entrained by droplets, the supply lines (42), (43) are used for the purpose of avoiding pressure loss and blockage in the wet condenser. BD can be additionally added through (44). In the tank (f) to which BD is additionally added from the supply line (42), the liquid level is kept constant. Therefore, the distillate extracted in the overflow form from the extraction line (41) is sent to the circulation line (37). And used as a spray for the wet condenser (b). Similarly, in order to make the liquid level constant in the tank (e), the distillate extracted in the overflow form from the extraction line (40) is sent to the circulation line (36) and sprayed from the wet condenser (a). Used as a liquid. The distillate withdrawn from the tank (d) in an overflow form is recycled as a slurry preparation or esterification reaction raw material through a draw line (39).

<Polyester>
MVR of polyester obtained in the present invention (measurement method described in the Examples) is preferably the upper limit is 30 ^(cm 3/10 min), particularly preferably from 10 ^(cm 3/10 min). The lower limit is preferably 0.1 ^(cm 3/10 min), more preferably 0.3 ^(cm 3/10 min)
By and particularly preferably 0.5 ^(cm 3/10 min). When the intrinsic viscosity exceeds the upper limit, it is difficult to obtain sufficient mechanical strength when formed into a molded product. When the intrinsic viscosity is less than the lower limit, the melt viscosity is high during molding and molding is difficult. The amount of terminal carboxyl groups of the polyester of the present invention is usually 80 (equivalent / ton) or less, preferably 60 (equivalent / ton) or less, more preferably 40 (equivalent / ton) or less, particularly preferably 25 (equivalent / ton). ) The lower the lower limit, the better the thermal stability and hydrolysis resistance, but it is usually 5 (equivalent / ton). If the upper limit is exceeded, the thermal stability is poor and thermal decomposition increases during molding.

  The average molecular weight of the polyester obtained in the present invention can be measured by gel permeation chromatography (GPC), and the weight average molecular weight using polystyrene as a standard substance is usually 10,000 to 1,000,000. Although it is below, since it is advantageous in terms of moldability and mechanical strength, it is preferably 20,000 or more and 500,000 or less, more preferably 50,000 or more and 400,000 or less.

  The polyester obtained in the present invention may contain a cyclic dimer compound. The content of the cyclic dimer compound of polyester is usually from 4,000 ppm to 10,000 ppm by weight, and the content can be reduced by extraction with a solvent, if necessary. If the content of the cyclic dimer compound is large, if the polyester is molded for a certain period after molding, it may cause problems such as cloudiness (synonymous with bleed out and whitening) on the surface and loss of surface gloss. .

<Polyester composition>
You may mix | blend aromatic-aliphatic copolymer polyester, aliphatic oxycarboxylic acid, etc. with the polyester of this invention. In addition to carbodiimide compounds, fillers, and plasticizers used as necessary, other biodegradable resins, such as polycaprolactone, polyamide, polyvinyl alcohol, cellulose ester, and the like, as long as the effects of the present invention are not impaired, starch Cellulose, paper, wood powder, chitin / chitosan, animal / plant substance fine powder such as coconut shell powder, walnut shell powder, or a mixture thereof can be blended. Furthermore, additives such as heat stabilizers, plasticizers, lubricants, antiblocking agents, nucleating agents, inorganic fillers, colorants, pigments, ultraviolet absorbers, light stabilizers, etc., are used for the purpose of adjusting the physical properties and processability of the molded product. Further, a modifier, a crosslinking agent, etc. may be included.

  The method for producing the polyester composition of the present invention is not particularly limited, but is a method in which the blended additive and the polyester raw material chips are melt-mixed in the same extruder, and each is melted in a separate extruder and then mixed. Examples thereof include mixing by kneading using a conventional kneader such as a method, a single screw extruder, a twin screw extruder, a Banbury mixer, a roll mixer, a Brabender plastograph, and a kneader blender. In addition, it is possible to obtain a molded body at the same time as preparing a composition by directly supplying each raw material chip to a molding machine.

EXAMPLES Hereinafter, although an Example and a comparative example are given and this invention is demonstrated further in detail, this invention is not limited by a following example, unless the summary is exceeded.
The analysis method in the present invention is shown below.

<PH analysis of catalyst solution>
Using an automatic titrator (AUT-301 type) manufactured by Toa DKK, the pH electrode was immersed in a liquid catalyst and measured under the atmosphere.
<Terminal carboxyl group concentration of esterification reaction product equivalent / ton>
A sample of 0.3 g of the esterification reaction product was heated to 40 mL of benzyl alcohol at 180 ° C. for 20 minutes, cooled for 10 minutes, and then titrated with a 0.1 mol·L- ¹ KOH / methanol solution to obtain an equivalent value / ton. It is represented by.

<Esterification rate%>
It calculated from the acid value and the saponification value by the following calculation formula (1). As the acid value, the terminal carboxyl group concentration of the esterification reaction product was used. The saponification value was determined by hydrolyzing the esterification reaction product with a 0.5N KOH / ethanol solution and titrating with 0.5N hydrochloric acid.
Esterification rate (%) = ((saponification value−acid value) / saponification value) × 100 Formula (1)

<Intrinsic viscosity (IV) dL / g>
It calculated | required in the following way using the Ubbelohde type viscometer. That is, using a mixed solvent of phenol / tetrachloroethane (weight ratio 1/1) and measuring the number of seconds of dropping only the polyester sample solution having a concentration of 0.5 g / dL and the solvent at 30 ° C., the following formula (2 )

IV = ((1 + 4KHηsp) 0.5-1) / (2KHC) Formula (2)

Here, ηsp = η / η ₀ −1, η is the sample solution drop time, η ₀ is the solvent drop time, C is the sample solution concentration (g / dL), and KH is the Huggins constant. . KH adopted 0.33.

<Melt Volume Flow rate: Measurement of (MVR ^cm 3/10 min)>
MVR which is a melt flow volume was measured according to the method of JIS-K7210 (1999) using a Takara Industries melt indexer. Specifically, MVR was measured by subjecting the aliphatic polyester dried at 80 ° C. for 12 hours to a melt indexer. The conditions for melt indexer, melt flow volume per unit of time measured by a load 2.16kg a ^(cm 3/10 min) was MVR at 190 ° C..

<Measurement of terminal carboxyl group concentration of polyester: equivalent / ton>
After pulverizing the pelletized polyester, it was dried in a hot air dryer at 60 ° C. for 30 minutes, and 0.1 g was accurately weighed from a sample cooled to room temperature in a desiccator, and 3 mL of benzyl alcohol was added. The solution was dissolved at 195 ° C. for 3 minutes while blowing dry nitrogen gas, and then 5 cm ³ of chloroform was gradually added and cooled to room temperature. Add 1 to 2 drops of phenol red indicator to this solution and titrate with 0.1 mol·L ⁻¹ sodium benzyl alcohol solution with stirring while blowing dry nitrogen gas. Ended. Moreover, the same operation was implemented as a blank, without adding a polyester sample, and the amount of terminal carboxyl groups (Hereinafter, an acid value or AV may be abbreviated.) Was calculated by the following formula (3).

  Terminal carboxyl content (equivalent / ton) = (ab) × 0.1 × f / w Formula (3)

In the above formula (3), a is the amount of 0.1 mol·L- ¹ sodium benzyl alcohol solution of sodium hydroxide required for titration (μL), and b is 0.1 mol·L required for titration with a blank. ^-1 amount of sodium hydroxide in benzyl alcohol solution (μL), w is the amount of polyester sample (g), f is the titer of 0.1 mol·L ⁻¹ sodium hydroxide in benzyl alcohol solution . The titer (f) of a benzyl alcohol solution of 0.1 mol·L ⁻¹ sodium hydroxide was determined by the following method. Collect 5 cm ³ of methanol in a test tube and add 1-2 drops as an indicator of phenol red in ethanol solution. Titration to a discoloration point was performed with 0.4 cm ³ of a benzyl alcohol solution of ¹ mol·L ⁻¹ sodium hydroxide, and then 0.2 cm ³ of 0.1 mol·L ⁻¹ hydrochloric acid aqueous solution having a known titer was taken as a standard solution. In addition, the solution was titrated again with a 0.1 mol·L ⁻¹ sodium hydroxide solution in benzyl alcohol to the discoloration point (the above operation was performed while blowing dry nitrogen gas).
The titer (f) was calculated by the following formula (4).

The titer (f) = 0.1mol · ^L titer × amount of collected aqueous hydrochloric acid 0.1N aqueous hydrochloric acid ^-1 ([mu] L) of sodium hydroxide /0.1mol · ^{L -1} benzyl alcohol solution titration Amount (μL) Equation (4)

  The lower the terminal carboxyl group concentration, the better the heat resistance and hydrolytic property of the polyester.

<Color b value>
Reference to JIS Z8730 (2009) by filling pellet-shaped polyester into a cylindrical powder measurement cell having an inner diameter of 30 mm and a depth of 12 mm, and using a colorimetric color difference meter Z300A (Nippon Denshoku Industries Co., Ltd.) The b value by the color coordinate of Hunter's color difference formula in the Lab display system described in Example 1 was obtained by a reflection method as a simple average of values measured by rotating the measurement cell by 90 degrees and measuring four positions.

<Solution haze%>
2.70 g of a polyester sample was placed in 20 mL of a mixture of phenol / tetrachloroethane = 3/2 (weight ratio), dissolved in 110 ° C. for 30 minutes, and then cooled in a constant temperature water bath at 30 ° C. for 15 minutes. A turbidimeter (NDH-300A) manufactured by Nippon Denshoku Co., Ltd. was used to measure the turbidity of the solution in a cell having an optical path length of 10 mm to obtain a solution haze. It shows that transparency is so favorable that a value is low.

<Water concentration (% by weight) in the collected liquid>
The distillate was precisely weighed, the amount of water μg was measured with a Karl Fischer moisture meter, and the ratio of the weight of water in 1,4-butanediol and in the recovered liquid of the polymerization distillate was determined.

<Measurement of 1,4-butanediol and HBTF content in recovered liquid>
The 1,4-butanediol and the HBTF concentration (% by weight) in the recovered liquid were determined by combining gas chromatography (GC) and moisture measurement.
The organic component was quantified by the modified area percentage method using GC, and the organic component was recalculated so that the sum of the moisture and the organic component obtained previously was 100%, and the concentration of HBTF was calculated. For recalculation of the organic component, it was determined using the effective carbon number based on the correction coefficient of 1,4-butanediol as the standard (1.000). 0.9228 was used as the correction factor for HBTF.

The apparatus is GC-14B (manufactured by Shimadzu Corporation) (split ratio: 1/90, RANGE: 10 ¹ ), and the column is DB-WAX (inner diameter: 0.32 mm, length: 60 m, membrane pressure) manufactured by J & W. : 0.5 μm). The temperature of the injection section and detector was 240 ° C., the column temperature was raised from 90 ° C. to 230 ° C. at 7 ° C./min, and then maintained at 230 ° C. for 20 minutes. Nitrogen (1 mL / min) was used as the carrier gas.
<Measurement of CM (cyclic monomer) content>
The CM concentration (% by weight) in the recovered liquid was determined by combining gas chromatography (GC) and moisture measurement as in the measurement of the HBTF content. The concentration of 1,4-butanediol, tetrahydrofuran and HBTF determined from GC and the value obtained by subtracting the amount of water determined from moisture measurement from 100% was taken as the CM concentration. The GC was performed under the same conditions as the HBTF content, and 0.7476 was used as the correction factor for tetrahydrofuran.
<Recycling rate>
The usage rate of the recovered liquid in the recovery tank (p) with respect to the total aliphatic diol amount supplied to the raw material preparation step and the esterification reaction step was calculated as the recycle rate.

[Example 1]
[Preparation of catalyst for polycondensation]
100 parts by weight of magnesium acetate tetrahydrate was placed in a glass eggplant-shaped flask equipped with a stirrer, and 1500 parts by weight of absolute ethanol (purity 99% by weight or more) was further added. Furthermore, 130.8 parts by weight of ethyl acid phosphate (mixing weight ratio of monoester and diester was 45:55) was added and stirred at 23 ° C. After confirming that magnesium acetate was completely dissolved after 15 minutes, 529.5 parts by weight of tetra-n-butyl titanate was added. Stirring was further continued for 10 minutes to obtain a uniform mixed solution. This mixed solution was transferred to an eggplant-shaped flask and concentrated under reduced pressure by an evaporator in an oil bath at 60 ° C. After 1 hour, most of ethanol was distilled off to obtain a translucent viscous liquid. The temperature of the oil bath was further raised to 80 ° C., and further concentrated under a reduced pressure of 5 Torr to obtain a viscous liquid. This liquid catalyst was dissolved in 1,4-butanediol to prepare a titanium atom content of 3.5% by weight. The storage stability in 1,4-butanediol was good, and the catalyst solution stored at 40 ° C. under a nitrogen atmosphere did not show the formation of precipitates for at least 40 days. The catalyst solution had a pH of 6.3.

[Production of aliphatic polyester]
An aliphatic polyester was produced by the raw material preparation step shown in FIG. 1, the esterification step shown in FIG. 2, the polycondensation step shown in FIG. 3, and the distillate recovery step shown in FIG. First, with respect to 1.00 mol of succinic acid containing 0.18% by weight of malic acid, 1.30 mol of 1,4-butanediol containing 0.15 wt% of HBTF and a total amount of malic acid of 0 The slurry at 50 ° C. mixed so as to have a ratio of .0028 mol was adjusted in the slurry preparation tank (A), and this slurry was passed through the slurry extraction line (4), the pump (C), and the slurry supply line (6). Then, it was transferred to the slurry storage tank (B), and was charged in advance from the slurry storage tank (B) through the slurry supply line (9) with an aliphatic polyester low molecular weight substance (esterification reaction product) having an esterification rate of 99% by weight in a nitrogen atmosphere. It supplied continuously to the esterification reaction tank (E) which has a stirrer so that it might become 58.8 kg / h.

  The esterification reaction vessel (E) is set to an internal temperature of 230 ° C. and a pressure of 101 kPa, and water, tetrahydrofuran, excess 1,4-butanediol and the like produced are distilled from the distillation line (13), and a rectifying column (F ) Separated into a high boiling component and a low boiling component. A part of the high-boiling component at the bottom of the column after the system was stabilized was extracted outside through an extraction line (23) so that the liquid level of the rectification column (F) was constant. On the other hand, the low-boiling components mainly composed of water and tetrahydrofuran are extracted in the form of gas from the top of the column and condensed by the condenser (G), so that the liquid level in the tank (H) becomes constant. ) Extracted outside. At the same time, the total amount of the bottom component of the rectifying column (F) at 100 ° C. (98% by weight or more is 1,4-butanediol) from the BD recirculation line (22) is also esterified from the supply line (24). Tetrahydrofuran generated in the reaction tank and equimolar 1,4-butanediol 2.2 kg / hr are supplied together, and the molar ratio of 1,4-butanediol to succinic acid in the esterification reaction tank is 1.30. Adjusted as follows. The supply amount of the recirculation line (22) and the supply line (24) was 6.3 kg / h.

The esterification reaction product produced in the esterification reaction tank (E) is continuously extracted from the esterification reaction product extraction line (12) using the pump (I), and the liquid in the esterification reaction tank (E). The liquid level was controlled so that the average residence time in terms of succinic acid unit was 4.4 hours. The esterification reaction product extracted from the extraction line (12) was continuously supplied to the first polycondensation reaction tank (L). After the system was stabilized, the esterification rate of the esterification reaction product collected at the outlet of the esterification reaction vessel (E) was 93.4%, and the terminal carboxyl concentration was 643 equivalent / ton.
After preparing the catalyst solution prepared in advance by the above-mentioned method in a catalyst preparation tank so that the concentration as titanium atom is 0.1% by weight, the catalyst solution is diluted with 1,4-butanediol, 29) through the esterification reaction product extraction line continuously at 2.2 kg / h (
12) (the catalyst was added to the liquid phase of the reaction solution). The supply was stable during the operation period.

  The internal temperature of the first polycondensation reaction tank (L) was 240 ° C., the pressure was 2.7 kPa, and the liquid level was controlled so that the residence time was 120 minutes. An initial polycondensation reaction was performed while extracting water, tetrahydrofuran, 1,4-butanediol, and CM from a vent line (25) connected to a decompressor (not shown). The extracted reaction liquid was continuously supplied to the second double condensation reactor (M).

  The internal temperature of the second double condensation reactor (M) was 245 ° C., the pressure was 400 Pa, and water, tetrahydrofuran, 1,4-butanediol, CM from a vent line (26) connected to a decompressor (not shown). The polycondensation reaction was further advanced while extracting the water. The residence time was 150 minutes. The obtained polyester was continuously supplied to the third polycondensation reactor (N) via the extraction line (31) by the extraction gear pump (P). The third polycondensation reactor (N) has an internal temperature of 245 ° C., a pressure of 130 Pa, a liquid level controlled so that the residence time is 180 minutes, and a vent line connected to a decompressor (not shown). While extracting water, tetrahydrofuran, 1,4-butanediol, and CM from (27), the polycondensation reaction was further advanced. The obtained polyester passed through the polymer filter (U), and then was continuously extracted in a strand form from the die head (V) and cut with a rotary cutter (W) to obtain pellets.

<Recovery of polymerization distillate>
BD containing 0.15% by weight of HBTF is continuously supplied from the supply line (42) to the circulation line (38) at 17.7 kg / hr, and the distillate extracted from the vent line (27) is wet. It was condensed with a condenser (c). The overflow liquid in the tank (f) was continuously supplied to the circulation line (37) through the extraction line (41), and the distillate extracted from the vent line (26) was condensed in the wet condenser (b). Similarly, the overflow liquid in the tank (e) is continuously supplied to the circulation line (36) through the extraction line (40), and the distillate extracted from the vent line (25) is condensed in the wet condenser (a). I let you. The overflow liquid in the tank (d) was sent to the recovery tank (p) at 30.7 kg / hr through the extraction line (39). At this time, BGTF in the recovered solution was 0.16% by weight and CM was 3.0% by weight. From the raw material supply line (3) through the recovery line (49) so that the recovered liquid has a recycling rate of 50% (the recovered liquid is reused corresponding to 50% of 1,4-butanediol necessary for slurry preparation). It supplied to the slurry preparation tank (A). The HBTF in the recovered liquid after the continuous operation for 7 days from the beginning of the recovery of the polymerization distillate was 0.18% by weight, and the CM was 5.0% by weight. Table 1 shows the results of the physical properties of the obtained aliphatic polyester and the state of blockage of the wet capacitor. In addition, regarding the state of blockage of the wet capacitor, “O” indicates that no blockage occurred, “△” indicates partial blockage, and “X” indicates blockage. As described. The same applies to the following examples and comparative examples.

[Example 2]
An aliphatic polyester was obtained in the same manner as in Example 1 except that the recovered liquid was continuously supplied from the raw material supply line (3) to the slurry preparation tank (A) at 29.3 kg / hr through the recovery line (49). . The HBTF in the recovered liquid after 7 days of continuous operation was 0.48% by weight and CM was 14.9% by weight. Table 1 shows the results of the physical properties of the obtained aliphatic polyester and the state of blockage of the wet capacitor.

[Example 3]
Using 1.4-butanediol made by Mitsubishi Chemical containing 0.20 wt% of HBTF, a 1.50-fold mole of slurry is prepared with respect to 1.00 mole of succinic acid, and the recovered liquid has a recycling rate of 100%. Thus, an aliphatic polyester was obtained in the same manner as in Example 1 except that it was supplied from the raw material supply line (3) to the slurry preparation tank (A) through the recovery line (49). After the continuous operation for 7 days, HBTF in the collected liquid was 0.63% by weight and CM was 12.4% by weight. Table 1 shows the results of the physical properties of the obtained aliphatic polyester and the state of blockage of the wet capacitor.

[Example 4]
A slurry preparation tank from the raw material supply line (3) through the recovery line (49) so that 1,4-butanediol made by Nanya containing 0.07 wt% of HBTF is used and the recovery rate is 100%. An aliphatic polyester was obtained in the same manner as in Example 1 except that it was supplied to (A). The HBTF in the collected liquid after 7 days of continuous operation was 0.22% by weight and CM was 9.9% by weight. Table 1 shows the results of the physical properties of the obtained aliphatic polyester and the state of blockage of the wet capacitor.

[Example 5]
Using BASF 1,4-butanediol containing 0.01 wt% of HBTF, the recovered liquid is made into a slurry preparation tank (3) from the raw material supply line (3) through the recovery line (49) so that the recycling rate becomes 100%. An aliphatic polyester was obtained in the same manner as in Example 1 except that it was supplied to A). After 7 days of continuous operation, HBTF in the collected liquid was 0.03% by weight, and CM was 7.4% by weight. Table 1 shows the results of the physical properties of the obtained aliphatic polyester and the state of blockage of the wet capacitor.

[Comparative Example 1]
An aliphatic polyester was obtained in the same manner as in Example 1 except that the recovered liquid was not reused as a raw material for slurry preparation. Table 1 shows the physical properties of the obtained aliphatic polyester in the collected liquid after 7 days of continuous operation and the results of the condition of the clogging of the wet capacitor.

[Comparative Example 2]
Using 1,4-butanediol made by Mitsubishi Chemical containing 0.20 wt% of HBTF and collecting the recovered liquid from the raw material supply line (3) through the recovery line (49) so that the recovered liquid has a recycling rate of 100%. An aliphatic polyester was obtained in the same manner as in Example 1 except that the slurry was supplied to the slurry preparation tank (A). After 7 days of continuous operation, HBTF in the collected liquid was 0.63% by weight and CM was 17.3% by weight. Table 1 shows the results of the physical properties of the obtained aliphatic polyester and the state of blockage of the wet capacitor.

[Comparative Example 3]
Using 1,4-butanediol made by Nanya, containing 0.07 wt% of HBTF, a slurry of 1.20 times mol with respect to 1.00 mol of succinic acid was prepared, and the recovered liquid had a recycling rate of 100% Thus, an aliphatic polyester was obtained in the same manner as in Example 1 except that it was supplied from the raw material supply line (3) to the slurry preparation tank (A) through the recovery line (49). After 7 days of continuous operation, HBTF in the collected liquid was 0.22% by weight and CM was 17.3% by weight. Table 1 shows the results of the physical properties of the obtained aliphatic polyester and the state of blockage of the wet capacitor.

[Comparative Example 4]
An aliphatic polyester was obtained in the same manner as in Example 1 except that BASF 1,4-butanediol containing 0.01 wt% of HBTF was used and the recovered liquid was not reused as a raw material for slurry preparation. . Table 1 shows the physical properties of the aliphatic polyester obtained after the continuous operation for 7 days and the results of the condition of the wet capacitor blockage.

[Example 6]
A low molecular weight component containing CM collected in a separator (g, h, i) heated to 130 ° C. is supplied from a supply line (24) through a recovery line (48) heated to 130 ° C. An aliphatic polyester was obtained in the same manner as in Example 1 except that the esterification reaction tank (E) was supplied at 0.45 kg / hr. After 7 days of continuous operation, HBTF in the collected liquid was 0.16% by weight and CM was 5.9% by weight. Table 1 shows the results of the physical properties of the obtained aliphatic polyester and the state of blockage of the wet capacitor.

According to the method for producing a polyester of the present invention, an industrially advantageous and efficient production method,
A polyester having a good color tone and a high degree of polymerization can be produced efficiently.

A: Slurry preparation tank
B: Slurry storage tank
C: Pump D: Pump
E: Esterification reaction tank
F: Rectification tower
G: Capacitor H: Tank
I: Extraction pump
J, K: Pump
L: First polycondensation reaction tank
M: Second double condensation reactor
N: Third triple condensation reactor
O, P, Q: Extraction gear pump
R, S, T, U: Filter
V: Dice head
W: Rotary cutter
1: Raw material supply line
2: Raw material supply line
3: Raw material supply line
4: Slurry extraction line
5: Slurry circulation line
6: Slurry supply line
7: Slurry extraction line
8: Slurry circulation line
9: Slurry supply line
10: Raw material supply line
11: Supply line
12: Extraction line for esterification reaction product
13: Distillation line
14: Degassing line
15: Vent line
16: Condensate line
17: Extraction line
18: Circulation line
19: Extraction line
20: Extraction line
21: Circulation line
22: BD recirculation line
23: Extraction line
24: Supply line
25, 26, 27: Distillation line
28: Supply line
29: Catalyst supply line
30, 31, 32: Polycondensation reaction product extraction line
33, 34, 35: Condensation lines 36, 37, 38: Circulation lines 39, 40, 41: Extraction lines 42, 43, 44: Supply lines 45, 46, 47: Vent lines 48, 49: Recovery lines 50: Waste lines a, b, c: wet condensers d, e, f, p: tanks g, h, i: separators j, k, l: heat exchangers m, n, o: pumps

Claims (5)

A raw material preparation step for mixing an aliphatic dicarboxylic acid and an aliphatic diol, an esterification step for esterifying the raw material in an esterification reaction vessel, and a polycondensation in which a reaction product obtained in the esterification step is polycondensed in a polycondensation reaction vessel. In the method for producing an aliphatic polyester having a condensation reaction step, at least one reaction vessel selected from an esterification reaction vessel and a polycondensation reaction vessel has a wet condenser, and an aliphatic dicarboxylic acid component discharged from the condenser ; An amount of 3% by weight or more and 15% by weight or less based on the total amount of all aliphatic diols supplied to the raw material preparation step and the esterification step of the cyclic monomer compound comprising the aliphatic diol component, starting from the raw material preparation step The manufacturing method of the aliphatic polyester supplied to one of the steps until the conversion step. The aliphatic diol contains 1,4-butanediol and is 0.1% by weight or more and 0.1% by weight or more based on the total amount of 1,4-butanediol supplied to the raw material preparation step and the esterification step.
The method for producing an aliphatic polyester according to claim 1, comprising 2- (4'-hydroxybutoxy) tetrahydrofuran in an amount of 5% by weight or less. The distillate obtained from at least one reaction vessel selected from an esterification reaction vessel and a polycondensation reaction vessel is supplied to any step from the raw material preparation step to the esterification step. The manufacturing method of aliphatic polyester of description. The method for producing an aliphatic polyester according to any one of claims 1 to 3, wherein the aliphatic polyester is produced in a continuous manner. The polycondensation reaction tank has a wet condenser, and the aliphatic polyester low polymer collected in a separator installed between the polycondensation reaction tank and the wet condenser is supplied to the esterification reaction tank. The manufacturing method of the aliphatic polyester of any one of Claims 1-4 .

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