JP5291273B2 - Method for producing aliphatic polyester - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing an aliphatic polyester excellent in stability without a special process for removing a catalyst in producing the aliphatic polyester obtained from an aliphatic dihydric alcohol and an aliphatic dicarboxylic acid. SOLUTION: This method for producing the aliphatic polyester having a weight average molecular weight Mw2 represented by the numerical formula (2) 5&times;104<=Mw2<=1&times;106 and (3) Mw1<Mw2 (Mw1 is mentioned below) comprises performing solid phase polymerization of a crystallized aliphatic polyester prepolymer having a weight average molecular weight Mw1 represented by the numerical formula (1) 2&times;103<=Mw1<=1&times;105 and obtained from the aliphatic dihydric alcohol and the aliphatic diarboxylic acid in the presence of a volatile catalyst. Since the catalyst can be removed simultaneously with the solid phase polymerization and/or while the same reaction system is kept after the solid phase polymerization, a process for producing the polyester can be rationalized in comparison with a conventional technology requiring a complicated process for removing a catalyst. Consequently, the high-molecular weight aliphatic polyester obtained has equal stability to an aliphatic polyester where a conventional removal of a catalyst has been performed.

Description

  In the present invention, an aliphatic polyester composed of an aliphatic dihydric alcohol and an aliphatic dicarboxylic acid, which is a biodegradable polymer useful as an alternative to a general-purpose resin, is subjected to solid phase polymerization in the presence of a nonmetallic volatile catalyst. The present invention relates to a method for producing an aliphatic polyester. Furthermore, the present invention provides a method for producing an aliphatic polyester capable of producing an aliphatic polyester having excellent stability without using a special catalyst removal step by using a non-metallic volatile catalyst. About.

In recent years, waste disposal has become a problem in connection with environmental protection. In particular, general-purpose molded and processed products of general-purpose polymer materials, when buried as waste, do not have degradability or disintegration due to microorganisms, etc., and therefore remain semi-permanently as a foreign substance. It is a problem that the additives such as elution dissolve and pollute the environment.
In addition, when incinerated as waste, the high amount of heat generated by combustion damages the furnace, and the flue gas and exhaust gas generated by combustion may cause air pollution, ozone depletion, global warming, acid rain, etc. Things that could be the cause have been highlighted.

  In such a background, polyhydroxycarboxylic acid such as polylactic acid, polyglycolic acid, poly-3-hydroxybutyric acid, polycaprolactone, polyethylene succinate, polybutylene succinate, polyethylene adipate, etc. that biodegrade in the natural environment In recent years, aliphatic polyester has attracted attention, and research and development has been actively conducted.

  Regarding the aliphatic polyester, for example, as disclosed in JP-A-4-189822 and JP-A-4-189823, a method for obtaining a high molecular weight aliphatic polyester by reacting a polymer terminal with diisocyanate in a molten state, US Pat. No. 5,401,796 discloses a method for obtaining a high molecular weight aliphatic polyester without using a diisocyanate by carrying out a dehydration condensation reaction using an organic solvent.

Conventional techniques relating to solid phase polymerization of aliphatic polyesters include the following.
In JP-A-8-34843, an aliphatic polyester having a relative viscosity of 1.5 or more is crystallized and then solid-phase polymerized at a temperature lower than its melting point in an inert gas atmosphere or under reduced pressure. A technique relating to a method for producing a high molecular weight aliphatic polyester is disclosed.
The catalyst disclosed here is a metal compound such as titanium, germanium, antimony, magnesium, calcium, zinc, iron, zirconium, vanadium, lithium, cobalt, manganese, metal alkoxide, metal acetylacetonate, metal oxide, It is described that it is used in the form of a metal complex, a metal hydroxide, an organic acid salt or the like. That is, there is no disclosure using a non-metallic volatile catalyst such as an organic sulfonic acid compound.

  In addition, including the case of the solid phase polymerization method described above, if the catalyst used in the polymerization remains in the polyester while maintaining its activity, for example, when such a polyester is molded, It is known that the molecular weight is lowered by heat, and it is difficult to say that such a polyester has a sufficient function in molding processability and heat resistance. Therefore, in order to ensure the stability of the polyester, a method of deactivating the catalyst after polymerization by adding various kinds of catalyst deactivators such as phosphoric acid and phosphorous acid or additives called polymer stabilizers In addition, a method of removing the catalyst from the polyester has been practiced.

  Additives are added to the polymerization system after the completion of polymerization, compared to solution polymerization methods using solvents and melt polymerization methods that polymerize polyesters in a molten state. However, in the solid phase polymerization method, after the polymerization is completed, the solid state polymer must be melted and then the additive must be added to make the process one more complicated. . However, in any case, there is a problem that additives and deactivated catalyst remain in the obtained polyester.

  On the other hand, the method of removing the catalyst from the polyester is preferable to the method of adding an additive in the sense that the residue in the polyester can be removed, but the method of removing the catalyst from the polyester is different from the polymerization step in the operating conditions. In addition, since the equipment is necessary, there are problems that the number of processes increases and the operation becomes complicated.

Problems to be solved by the invention

  Accordingly, an object of the present invention is to produce an aliphatic polyester excellent in stability without the need for a special catalyst removal step when producing an aliphatic polyester comprising an aliphatic binary alcohol and an aliphatic dicarboxylic acid. The manufacturing method of this is provided.

Means for solving the problem

As a result of intensive investigations in view of the problems of the prior art described above, the present inventors use a volatile catalyst in producing an aliphatic polyester composed of an aliphatic dihydric alcohol and an aliphatic dicarboxylic acid. As a result of solid phase polymerization, it was found that an aliphatic polyester excellent in stability can be produced without requiring a special catalyst removal step, and the present invention has been completed.
That is, the method for producing an aliphatic polyester according to the present invention is specified by the matters described in [1] to [8] below.

[1] An aliphatic polyester prepolymer comprising a crystallized aliphatic dihydric alcohol and an aliphatic dicarboxylic acid having a weight average molecular weight (Mw ₁ ) in the numerical range represented by the formula (1) (Equation 10) By solid-phase polymerization of the polymer in the presence of a volatile catalyst, the polymer has a weight average molecular weight (Mw ₂ ) in the numerical range represented by Equation (2) (Equation 11) and Equation (3) (Equation 12). A method for producing an aliphatic polyester, comprising obtaining an aliphatic polyester.
[Expression 10]
2 × 10 ³ ≦ Mw ₁ ≦ 1 × 10 ⁵ (1)
## EQU11 ##
5 × 10 ⁴ ≦ Mw ₂ ≦ 1 × 10 ⁶ (2)
[Expression 12]
Mw ₁ <Mw ₂ (3)

[2] The method for producing an aliphatic polyester as described in [1], wherein the catalyst residual ratio R represented by Formula (4) (Equation 13) is 50% or less.
[Formula 13]
_{R [%] = C A [} ppm] ÷ C B [ppm] × 100 (4)
(In Formula (4), R is a catalyst residual rate [%] which is a measure of change in catalyst concentration before and after solid-phase polymerization, and C _B [ppm] is calculated by Formula (5) (Formula 14). The theoretical catalyst concentration in the case where all of the catalyst charged in the reaction system before solid phase polymerization and / or during solid phase polymerization remains in the aliphatic polyester, and C _A [ppm] is the formula (6) ( The catalyst concentration in the aliphatic polyester finally obtained after completion of solid-phase polymerization, calculated by equation 15))
[Expression 14]
C _B [ppm] = W _B [g] ÷ W _P [g] × 10 ⁶ (5)
(In Formula (5), W _B [g] is the total weight of the catalyst charged in the reaction system before and / or during the solid phase polymerization, and W _P [g] is the end of the solid phase polymerization. And the weight of the aliphatic polyester finally obtained)
[Expression 15]
C _A [ppm] = W _A [g] ÷ W _P [g] × 10 ⁶ (6)
(In Formula (6), W _A [g] is the weight of the catalyst finally contained in the aliphatic polyester obtained after completion of the solid phase polymerization, and W _P [g] is the end of the solid phase polymerization. And the weight of the aliphatic polyester finally obtained)

[3] The aliphatic polyester prepolymer is a polybutylene succinate prepolymer composed of succinic acid and 1,4-butanediol, and the aliphatic polyester is polybutylene succinate, described in [1] or [2] Of producing aliphatic polyester.
[4] The method for producing an aliphatic polyester as described in [1] or [2], wherein the volatile catalyst is an organic sulfonic acid compound.

[5] The organic sulfonic acid compound is at least one selected from the group consisting of methanesulfonic acid, ethanesulfonic acid, 1-propanesulfonic acid, benzenesulfonic acid, p-chlorobenzenesulfonic acid, and m-xylene-4-sulfonic acid. [4] The method for producing an aliphatic polyester described in [4].
[6] The production of the aliphatic polyester according to [4] or [5], wherein the catalyst concentration in the finally obtained aliphatic polyester is 0 to 300 ppm in terms of sulfur content. Method.

[7] As the step (A), an aliphatic dihydric alcohol and an aliphatic divalent carboxylic acid are subjected to a polycondensation reaction in the presence or absence of a catalyst, in the presence or absence of a solvent, and the formula (1). A step of producing an aliphatic polyester prepolymer having a weight average molecular weight (Mw ₁ ) in the numerical range represented by (Expression 16);
[Expression 16]
2 × 10 ³ ≦ Mw ₁ ≦ 1 × 10 ⁵ (1)
As the step (B), a step of crystallizing the aliphatic polyester prepolymer obtained in the step (A),
(C) As a step, a step of solid-phase polymerization of the crystallized aliphatic polyester prepolymer obtained in (B) step in the presence of a volatile catalyst,
Composed of steps consisting of, equation (2) (number 17) and Equation (3) the production method of aliphatic polyester having a weight average molecular weight in the numerical range indicated by (Equation 18) (Mw _2).
[Expression 17]
5 × 10 ⁴ ≦ Mw ₂ ≦ 1 × 10 ⁶ (2)
[Formula 18]
Mw ₁ <Mw ₂ (3)

[8] The aliphatic dihydric alcohol is 1,4-butanediol, the aliphatic divalent carboxylic acid is succinic acid, and the volatile catalyst is methanesulfonic acid, ethanesulfonic acid, 1-propanesulfonic acid, benzenesulfonic acid. , P-chlorobenzenesulfonic acid, m-xylene-4-sulfonic acid, The manufacturing method of the aliphatic polyester as described in [7] containing at least 1 type selected from the group.

The production method of the present invention comprises a crystallization comprising an aliphatic dihydric alcohol and an aliphatic divalent carboxylic acid having a weight average molecular weight (Mw ₁ ) in the numerical range represented by the formula (1) (Equation 19). The obtained aliphatic polyester prepolymer is subjected to solid-phase polymerization in the presence of a volatile catalyst, so that the weight average molecular weight in the numerical range represented by the formulas (2), (20), and (3), (21) An aliphatic polyester having (Mw ₂ ) is obtained.
[Equation 19]
2 × 10 ³ ≦ Mw ₁ ≦ 1 × 10 ⁵ (1)
[Expression 20]
5 × 10 ⁴ ≦ Mw ₂ ≦ 1 × 10 ⁶ (2)
[Expression 21]
Mw ₁ <Mw ₂ (3)

[Concept of terms used in this application specification]
(1) The concept of the term “volatile catalyst” The concept of the term “volatile catalyst” described in the present specification is obtained by producing an aliphatic polyester by solid-phase polymerization. ) Means a catalyst having a function capable of setting the catalyst residual ratio R defined by () to any numerical value within the range represented by Formula (7) (Formula 25).
[Expression 22]
_{R [%] = C A [} ppm] ÷ C B [ppm] × 100 (4)
(In Formula (4), R is a catalyst residual rate [%] which is a measure of a change in catalyst concentration before and after solid phase polymerization, and C _B [ppm] is calculated by Formula (5) (Formula 23). The theoretical catalyst concentration in the case where all of the catalyst charged in the reaction system before solid phase polymerization and / or during solid phase polymerization remains in the aliphatic polyester, and C _A [ppm] is the formula (6) ( The catalyst concentration in the aliphatic polyester finally obtained after completion of solid-phase polymerization, calculated by equation 24))
[Expression 23]
C _B [ppm] = W _B [g] ÷ W _P [g] × 10 ⁶ (5)
(In Formula (5), W _B [g] is the total weight of the catalyst charged in the reaction system before and / or during the solid phase polymerization, and W _P [g] is the end of the solid phase polymerization. And the weight of the aliphatic polyester finally obtained)
[Expression 24]
C _A [ppm] = W _A [g] ÷ W _P [g] × 10 ⁶ (6)
(In Formula (6), W _A [g] is the weight of the catalyst finally contained in the aliphatic polyester obtained after completion of the solid phase polymerization, and W _P [g] is the end of the solid phase polymerization. And the weight of the aliphatic polyester finally obtained)
[Expression 25]
0 [%] ≦ R [%] <100 [%] (7)
(In Equation (7), R [%] is the catalyst residual rate [%], which is a measure of the change in catalyst concentration before and after solid phase polymerization, calculated by Equation (4)).

That is, by using the volatile catalyst in the method of the present invention, the catalyst concentration C _A [ppm] in the aliphatic polyester finally obtained after completion of the solid-phase polymerization is expressed by Equation (5). It becomes smaller than the catalyst concentration C _B [ppm] calculated from the weight of the catalyst charged in the reaction system before and / or during the solid phase polymerization.
It can be said that the smaller the value of the catalyst residual ratio R [%], the better the characteristics as a volatile catalyst, and the higher the stability of the resulting polyester.
The value of the catalyst residual rate R [%] varies depending on the type of volatile catalyst, the amount used, the reaction method, and the reaction conditions. Generally, the value of the catalyst residual rate R [%] is 50% or less. Is preferable, and it is further more preferable that it is 20% or less.

  An example of a catalyst having such a function is one having a vapor pressure at the temperature at which solid-phase polymerization is performed. When the aliphatic polyester prepolymer is solid-phase polymerized using such a catalyst, the aliphatic polyester prepolymer is polycondensed to increase the molecular weight, and the catalyst is volatilized from the polymer by its own vapor pressure, and the polymer is polymerized. The catalyst concentration in the medium is reduced.

(2) Concept of the term “prepolymer” In the present specification, the concept of the term “prepolymer” includes oligomers and polymers subjected to a polycondensation reaction for use in solid phase polymerization.

[Method for producing aliphatic polyester prepolymer comprising aliphatic dicarboxylic acid and aliphatic dihydric alcohol]
An aliphatic polyester prepolymer composed of an aliphatic divalent carboxylic acid and an aliphatic dihydric alcohol used in the present invention comprises an aliphatic divalent carboxylic acid and an aliphatic dihydric alcohol in a solvent in the presence or absence of a catalyst. In the presence or absence of a polycondensation reaction.
The aliphatic divalent carboxylic acid used in the present invention is not particularly limited as long as the resulting aliphatic polyester prepolymer has crystallinity.

Specific examples of the aliphatic divalent carboxylic acid used in the present invention include, for example, succinic acid, oxalic acid, malonic acid, glutamic acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid, Examples include aliphatic dicarboxylic acids such as dodecanedioic acid and 3,3-dimethylpentanedioic acid, and alicyclic dicarboxylic acids such as cyclohexanedicarboxylic acid. Moreover, the acid anhydride of the said acid can also be used. These can be used alone or in combination of two or more. Of these, succinic acid is preferred.
Furthermore, when it has an asymmetric carbon in the molecule, there are D-form, L-form, and an equivalent mixture (racemic form) thereof, any of which can be used.
A small amount of an aliphatic polyvalent carboxylic acid having 3 or more carboxyl groups and / or an acid anhydride thereof, such as 1,2,3,4-butanetetracarboxylic acid, may be added.

The aliphatic dihydric alcohol used in the present invention is not particularly limited as long as the resulting aliphatic polyester prepolymer has crystallinity.
Specific examples of the aliphatic dihydric alcohol used in the present invention include, for example, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, 1,3-butanediol, 1,4-butanediol, 3- Methyl-1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, neopentyl glycol, 1,4-cyclohexanedimethanol, etc. Can be mentioned. These can be used alone or in combination of two or more.
Among these, ethylene glycol and 1,4-butanediol are preferable.
Moreover, when it has an asymmetric carbon in a molecule | numerator, although D body, L body, and those equivalent mixtures (racemic body) exist, any of them can be used.
A small amount of an aliphatic polyhydric alcohol having three or more hydroxyl groups such as trimethylolpropane and pentaerythritol may be added.

The polycondensation reaction includes a solution polymerization method in which an aliphatic binary carboxylic acid and an aliphatic dihydric alcohol are subjected to a polycondensation reaction in an organic solvent, and a melt polymerization method in which a polycondensation reaction is performed without a solvent. A known method is appropriately selected and used depending on the average molecular weight (Mw) and the ease of operation.
As the solution polymerization method, for example, a method according to the description of US-5,401,796 is used.

  The method for producing the aliphatic polyester prepolymer by the melt polymerization method is not particularly limited, and a polycondensation reaction can be performed under an inert gas atmosphere and / or under reduced pressure. The reaction temperature is not particularly limited as long as the monomer (aliphatic dicarboxylic acid and aliphatic dihydric alcohol) present in the reaction system and the resulting aliphatic polyester prepolymer are in a molten state and the progress of the polycondensation reaction can be maintained. In consideration of the production rate of the aliphatic polyester and the thermal decomposition rate, a range of 100 to 200 ° C is preferable, and a range of 110 to 180 ° C is more preferable.

  The method of polycondensation reaction in an organic solvent is excellent in that an aliphatic polyester prepolymer having a weight average molecular weight of 15000 or more can be easily obtained. In addition, the method of polycondensation reaction without solvent is excellent in that it is easy to operate because it eliminates the trouble of distilling off the organic solvent.

Further, when the aliphatic polyester prepolymer is produced, the polycondensation reaction may be carried out in the presence of a catalyst or in the absence thereof, but the polycondensation reaction is usually carried out in the presence of a catalyst.
The catalyst used in the present invention is a volatile catalyst that can reduce the catalyst content in the polymer before and after solid phase polymerization.
The volatile catalyst used in the present invention is not particularly limited as long as it substantially accelerates the progress of the polycondensation reaction and has volatility.
Specific examples of the volatile catalyst used in the present invention include organic sulfonic acid compounds.

  Specific examples of the organic sulfonic acid include, for example, methanesulfonic acid, ethanesulfonic acid, 1-propanesulfonic acid, 1-butanesulfonic acid, 1-pentanesulfonic acid, 1-hexanesulfonic acid, 1-heptanesulfonic acid, 1 -Alkanesulfonic acid such as octanesulfonic acid, 1-nonanesulfonic acid, 1-decanesulfonic acid, halogen-substituted alkanesulfonic acid such as trifluoromethanesulfonic acid, benzenesulfonic acid, p-toluenesulfonic acid, p-xylene-2-sulfonic acid Benzenesulfonic acid such as m-xylene-4-sulfonic acid, p-ethylbenzenesulfonic acid, p-chlorobenzenesulfonic acid, p-nitrobenzenesulfonic acid, o-nitrobenzenesulfonic acid, p-hydroxybenzenesulfonic acid, sulfobenzoic acid, and the like Benzenesulfonic acid derivative , Naphthalene-1-sulfonic acid, naphthalene-2-sulfonic acid, naphthalenesulfonic acid such as 2,5-naphthalenedisulfonic acid, and naphthalenesulfonic acid derivatives. Among them, methanesulfonic acid, ethanesulfonic acid 1-propanesulfonic acid, benzenesulfonic acid, p-chlorobenzenesulfonic acid and m-xylene-4-sulfonic acid are preferable, and methanesulfonic acid, ethanesulfonic acid and 1-propanesulfonic acid are particularly preferable. These can be used alone or in combination of two or more.

  Some of the above organic sulfonic acids have water of crystallization, and in this case, when adding a catalyst, it may be necessary to consider a decrease in weight average molecular weight due to water of crystallization. When the weight average molecular weight (Mw) at the time of adding the catalyst is 1,000 or less, the catalyst may be added with water of crystallization, but when the weight average molecular weight (Mw) exceeds 1,000, the weight may be increased. The higher the average molecular weight (Mw), the easier the weight average molecular weight of the aliphatic polyester to decrease due to the water of crystallization of the catalyst. It is preferable because it does not inhibit.

In the present invention, the amount of the volatile catalyst used is not particularly limited as long as the reaction can be substantially accelerated in consideration of the properties of the catalyst itself such as the volatility of the catalyst and the acid strength, and the reaction conditions.
The preferred use amount of the volatile catalyst varies depending on the type of the catalyst used, but generally it is preferably in the range of 0.00005 to 10% by weight of the resulting aliphatic polyester prepolymer or aliphatic polyester. In consideration, the range of 0.001 to 5% by weight is more preferable, and the range of 0.1 to 2% by weight is more preferable.

  In the present invention, the weight average molecular weight (Mw) and molecular weight distribution of the aliphatic polyester prepolymer are not particularly limited as long as the aliphatic polyester prepolymer is crystallized and a sufficiently high molecular weight aliphatic polyester is obtained by solid phase polymerization. The reaction conditions such as the type and amount of the catalyst, the reaction temperature, the reaction time, etc. can be appropriately selected to control the catalyst, but the aliphatic polyester prepolymer contains unreacted aliphatic divalent carboxylic acid and If an aliphatic dihydric alcohol is contained, the unreacted monomer volatilizes during the solid-phase polymerization, and the high molecular weight having sufficient mechanical strength is obtained because the equivalent ratio of the reacting carboxyl group and hydroxyl group is not matched. Aliphatic polyester may not be obtained. Therefore, the weight average molecular weight of the aliphatic polyester prepolymer preferably has a molecular weight such that substantially no unreacted monomer remains in the prepolymer.

  Considering these, the weight average molecular weight of the aliphatic polyester prepolymer used in the present invention is generally 2,000 to 100,000, but may be 5,000 to 100,000. Preferably, it is 6,000 to 100,000, more preferably 8,000 to 100,000, and most preferably 10,000 to 100,000.

EP-0953589A2 includes a crystallized aliphatic polyester prepolymer containing 50% or more of an aliphatic hydroxycarboxylic acid unit and having a weight average molecular weight of 2,000 to 100,000 in the presence of a catalyst. A process for producing an aliphatic polyester containing 50% or more of an aliphatic hydroxycarboxylic acid unit having a weight average molecular weight of 50,000 to 1,000,000 by solid phase polymerization is disclosed. The catalyst disclosed in EP-0935589A2 includes volatile catalysts such as organic sulfonic acid compounds.
When an aliphatic polyester prepolymer containing 50% or more of an aliphatic hydroxycarboxylic acid unit is solid-phase polymerized, the aliphatic hydroxycarboxylic acid unit mainly undergoes a dehydration polycondensation reaction to increase the molecular weight. Since aliphatic hydroxycarboxylic acids such as L-lactic acid each have one hydroxyl group and one carboxyl group in the molecule, the equivalent ratio of hydroxyl groups to carboxyl groups in the process of producing an aliphatic polyester by dehydration polycondensation reaction ( The number of moles of hydroxyl groups / number of moles of carboxyl groups) hardly deviates from 1.

  On the other hand, an aliphatic polyester obtained by polycondensation reaction between an aliphatic divalent carboxylic acid and an aliphatic dihydric alcohol, like the aliphatic polyester of the present application, is an aliphatic divalent carboxylic acid or fatty acid during the polycondensation reaction. If the equivalent ratio of hydroxyl group to carboxyl group deviates significantly from 1 due to volatilization of the aliphatic dihydric alcohol, a high molecular weight aliphatic polyester cannot be obtained. Therefore, the equivalent ratio of hydroxyl groups to carboxyl groups (number of moles of hydroxyl groups / number of moles of carboxyl groups) in the aliphatic polyester prepolymer comprising the aliphatic divalent carboxylic acid and the aliphatic dihydric alcohol of the present application is the aliphatic polyester prepolymer. Is a polybutylene succinate, it is preferably 0.99 to 1.01. Further, based on the above reasons, the aliphatic polyester pre-polymer is prevented so that the aliphatic dicarboxylic acid and the aliphatic dihydric alcohol are not volatilized during the solid phase polymerization and the equivalent ratio of the hydroxyl group to the carboxyl group is not greatly deviated from 1. It is preferable that the polymer does not substantially contain an aliphatic divalent carboxylic acid or an aliphatic dihydric alcohol, which are monomer components.

[Prepolymer solidification process]
The prepolymer solidification step is a step of obtaining a solid prepolymer after a polycondensation reaction between an aliphatic dihydric alcohol and an aliphatic divalent carboxylic acid.
The method for obtaining the solid prepolymer is not particularly limited, but is appropriately selected according to the presence or absence of an organic solvent, the crystallinity and the amount of the prepolymer.
As a method for solidifying the prepolymer, for example, in the case of polycondensation reaction in an organic solvent, it is simply cooled to crystallize the prepolymer, or the organic solvent is distilled off. When there is little (for example, when the prepolymer concentration is 90% or more, etc.), a method of contacting with a liquid is used. And a method of pelletizing with a pellet manufacturing apparatus.
Furthermore, in order to obtain a solid prepolymer corresponding to a desired shape (for example, powder, granule, granule, pellet, etc.) and particle diameter, the following appropriate treatment may be performed.

(1) Method for making solid prepolymer into powder The method for making solid prepolymer into powder is not particularly limited. For example, the prepolymer is crystallized after the prepolymer is crystallized at the end of the polyester prepolymer production step. And a method of separating the organic solvent.
(2) Method for making solid prepolymer particles and pellets The method for making solid prepolymer particles and pellets is not particularly limited. For example, a polycondensation reaction was performed using a small amount of an organic solvent. Examples thereof include a method of bringing a prepolymer solution into contact with a liquid of a prepolymer in the case of polycondensation reaction without solvent or a prepolymer.

There is no limitation on the method of contacting the liquid in a solution state (when an organic solvent is used) or a molten state (when an organic solvent is not used). For example, when a prepolymer melt is dropped into water and solidified, spherical pellets are obtained.
Moreover, when solidifying by making contact with a liquid, after making it solidify, it can also crystallize, making it contact with a liquid.
Furthermore, after completion of the polycondensation reaction, a method of obtaining pellets by transferring the reaction solution to an extruder and pelletizing, a method of producing pellets by a pellet production apparatus, and the like are also included.

The pellet manufacturing apparatus is not particularly limited. For example, Sandvik's strip former, funnel former, double roll feeder, Kaiser rotary drop former, piston drop former, Mitsubishi Examples include a drum cooler manufactured by Kasei Engineering, a steel belt cooler manufactured by Nippon Belling, and a hybrid former.
An aliphatic polyester prepolymer melt droplet generator and a solution droplet generator are not particularly limited, and specific examples thereof include a Kastor pastilator.

  In addition, if a Sandvik Rohtoformer is used, an aliphatic polyester prepolymer having a relative viscosity of less than 1.5 and a relatively low weight average molecular weight can be granulated. However, the relative viscosity here uses a mixed solvent of phenol / tetrachloroethane (1/1, weight ratio) as a solvent, and the viscosity of the polymer solution at a concentration of 0.5 g / deciliter is 30 by using an Ubbelohde viscometer. Obtained by measuring at ° C.

The pellet shape and grain shape are not particularly limited. The pellet shape and particle shape need not be a specific shape such as a pulverized shape, a chip shape, a spherical shape, a cylindrical shape, a marble shape, or a tablet shape, but in general, a spherical shape, a cylindrical shape, or a marble shape is preferable.
The particle diameter of the solid prepolymer is not particularly limited, but is usually set in consideration of the ease of operation in the process and the speed and efficiency with which the volatile catalyst evaporates from the polyester in solid phase polymerization. The
In particular, the particle diameter of the solid prepolymer is set taking into account that the volatility of the volatile catalyst (the ability of the catalyst to evaporate from the polymerized polyester in solid phase polymerization) is fully expressed. Is done.
In consideration of the solid prepolymer surface area per unit weight of the solid prepolymer so that the volatility is sufficiently developed, generally, the particle diameter of the solid prepolymer is 10 μm to 10 mm. Is preferable, 0.1 mm to 10 mm is more preferable, and 1 mm to 5 mm is more preferable.

  In the step of producing the solid prepolymer, a catalyst used in the solid phase polymerization step may be added. The method for adding the catalyst is not particularly limited. Since it is preferable to uniformly disperse the catalyst in the prepolymer, specific examples thereof include, for example, adding the catalyst when pulverizing the bulk prepolymer or adding the catalyst when pelletizing. it can.

[Prepolymer crystallization process]
The prepolymer crystallization step is a step of crystallizing the solid prepolymer obtained in the prepolymer solidification step.
The method for crystallizing the prepolymer in the prepolymer crystallization step is not particularly limited. For example, various methods known in the art such as heating in a gas phase such as in a heated nitrogen gas atmosphere, or contacting with a liquid. For example, a method for crystallization can be used. Moreover, you may add a crystal nucleating agent as needed.

  The method for contacting the aliphatic polyester prepolymer with the liquid for crystallization is not particularly limited. For example, when the aliphatic polyester prepolymer is in a solid state, the aliphatic polyester prepolymer solid is charged into a liquid and brought into contact with the liquid, or conversely, the liquid is poured into the aliphatic polyester prepolymer solid to obtain a liquid. The method of making it contact with is mentioned.

  Examples of a method for charging the aliphatic polyester prepolymer solid into the liquid for crystallization include a method using a tank and a method using a tower. When using a tank, it may or may not be stirred, but it is preferable to stir to prevent the prepolymers from contacting each other. When a tower is used, the aliphatic polyester prepolymer solids and the liquid can be contacted in countercurrent or in parallel. It is also possible to charge the aliphatic polyester prepolymer solids into the flowing liquid.

  For crystallization, the method of pouring the liquid into the aliphatic polyester prepolymer solids and bringing them into contact with each other can be carried out by spraying the liquid on the aliphatic polyester prepolymer solids or by applying it to a column packed with the aliphatic polyester prepolymer solids. A method of circulating a liquid may be used.

  The liquid used for crystallization is not particularly limited as long as the aliphatic polyester prepolymer does not dissolve at the liquid temperature to be crystallized, and water, alcohol, aliphatic hydrocarbons, ketones, ethers, esters, etc. Any commonly used solvent can be used. These may have a single composition or may be used as a mixture. Moreover, you may add an organic acid to a liquid as needed.

  Examples of the alcohol used as the liquid used for crystallization include methanol, ethanol, propanol, iso-propanol, butanol, iso-butanol, sec-butanol, tert-butanol, pentanol, iso-pentanol, and tert-pentanol. Hexanol, iso-hexanol, tert-hexanol, and cyclohexanol. Examples of the aliphatic hydrocarbon include hexane, cyclohexane, n-heptane, n-octane, n-nonane, n-decane, n-undecane, n-dodecane, n-tridecane, and n-tetradecane. Examples of the ketone include acetone and methyl ethyl ketone, examples of the ether include methyl-t-butyl ether and dibutyl ether, and examples of the esters include ethyl acetate, butyl acetate, methyl lactate, ethyl lactate, and butyl lactate. Among these, water is preferable.

Further, the amount of liquid used for crystallization is not particularly limited as long as the prepolymers are not fused together.
After the aliphatic polyester prepolymer is crystallized by contacting with a liquid, the prepolymer crystallized by a known method and the liquid can be separated. After separation from the liquid, an aliphatic polyester prepolymer that is dried and crystallized by a known method can be obtained.

[Solid-state polymerization process]
The solid phase polymerization step is a step of solid phase polymerization of the crystallized aliphatic polyester prepolymer in the presence of the volatile catalyst.
The solid-state polymerization reaction conditions are such that the polymer (aliphatic polyester prepolymer and reaction product aliphatic polyester) existing in the reaction system is maintained in a substantially solid state, and the catalyst in the aliphatic polyester after solid-phase polymerization. The concentration is less than or equal to the value of the catalyst concentration before solid phase polymerization, and the weight average molecular weight (Mw) of the aliphatic polyester after solid phase polymerization is greater than or equal to the value of the weight average molecular weight (Mw) before solid phase polymerization. If there is no particular limitation.

The solid-state polymerization reaction conditions are such that the polymer (aliphatic polyester prepolymer and reaction product aliphatic polyester) existing in the reaction system is maintained in a substantially solid state, and the catalyst in the aliphatic polyester after solid-phase polymerization. The concentration is equal to or less than the value of the catalyst concentration before solid-phase polymerization, and the weight average molecular weight (MW ₁ ) of the aliphatic polyester prepolymer before solid-phase polymerization is in the numerical range represented by Equation (1) (Equation 26). Yes, the weight average molecular weight (Mw ₂ ) of the aliphatic polyester after solid-phase polymerization is not particularly limited as long as it is in the numerical range represented by the formula (2) (formula 27) and the formula (3) (formula 28).
[Equation 26]
2 × 10 ³ ≦ Mw ₁ ≦ 1 × 10 ⁵ (1)
[Expression 27]
5 × 10 ⁴ ≦ Mw ₂ ≦ 1 × 10 ⁶ (2)
[Expression 28]
MW ₁ <Mw ₂ (3)

In this way, after solid phase polymerization, the catalyst residual rate R [%] calculated by Equation (4) (Equation 30) is controlled within the numerical range indicated by Equation (7) (Equation 29). R is preferably 50% or less, and more preferably 20% or less. .
[Expression 29]
0 [%] ≦ R [%] <100 [%] (7)
(In Equation (7), R [%] is the catalyst residual rate [%], which is a measure of change in catalyst concentration after solid-phase polymerization, calculated by Equation (4)).
[30]
R [%] = C _A [ppm] ÷ C _B [ppm] x 100 (4)
(In Formula (4), C _B [ppm] is calculated by Formula (5) (Formula 31), and the catalyst charged in the reaction system before and / or during solid phase polymerization is all aliphatic. The theoretical catalyst concentration in the case of remaining in the polyester, and C _A [ppm] is the catalyst in the aliphatic polyester finally obtained after solid-phase polymerization, calculated by Equation (6) (Equation 32) Concentration)
[31]
C _B [ppm] = W _B [g] ÷ W _P [g] × 10 ⁶ (5)
(In Formula (5), W _B [g] is the total weight of the catalyst charged in the reaction system before and / or during solid phase polymerization, and W _P [g] is after solid phase polymerization. Is the weight of the aliphatic polyester finally obtained)
[Expression 32]
C _A [ppm] = W _A [g] ÷ W _P [g] × 10 ⁶ (6)
(In Formula (6), W _A [g] is the catalyst weight contained in the aliphatic polyester finally obtained after solid phase polymerization, and W _P [g] is It is the weight of the aliphatic polyester finally obtained)

The reaction temperature in the solid phase polymerization step is not particularly limited as long as the polymer (aliphatic polyester prepolymer and aliphatic polyester as a reaction product) existing in the reaction system is maintained in a substantially solid state.
In general, the higher the reaction temperature, the faster the polymerization rate and the easier the volatile catalyst will evaporate. For this reason, in order to obtain a high molecular weight polyester, the volatilization rate of the catalyst is taken into consideration in the temperature range from the glass transition temperature (Tg) to the melting point (Tm) of the polymer (the prepolymer and the reaction product polyester). To set the reaction temperature.

The solid phase polymerization step of the present invention is preferably performed in a flowing gas atmosphere in order to remove water generated by the polymerization.
Specific examples of the gas used in the solid phase polymerization process, that is, the gas to be circulated in the reaction system include, for example, inert gas such as nitrogen gas, helium gas, argon gas, xenon gas, krypton gas, dry air, etc. Is mentioned.

The water content of the circulating gas is preferably as low as possible and is substantially anhydrous. If the water content is high, the water produced by the polycondensation reaction cannot be removed efficiently, which is not preferable because the polymerization rate becomes slow. In this case, the gas can be used after being dehydrated by passing it through a layer filled with molecular sieves or ion exchange resins.
When the moisture content of the circulating gas is indicated by a dew point, the dew point of the gas is preferably −20 ° C. or lower, and more preferably −50 ° C. or lower.

The flow rate of the flow gas is the polymerization rate, the type and amount of volatile catalyst used, the rate and efficiency at which the volatile catalyst is stripped from the aliphatic polyester in the solid phase polymerization process, and the water generated by solid phase polymerization is removed. It is set in consideration of speed, efficiency, reached weight average molecular weight (Mw) and the like.
The effect of circulating the flow gas into the reaction system is that water generated by solid phase polymerization can be efficiently removed out of the system, and thereby a sufficiently high weight average molecular weight aliphatic polyester can be obtained efficiently. It is in.
Therefore, it is generally considered that the higher the flow rate of the flow gas, the more efficiently the water generated in the solid phase polymerization can be removed. On the other hand, the volatilization of the volatile catalyst from the aliphatic polyester in the solid phase polymerization. Since the speed is also increased, when an aliphatic polyester having a high weight average molecular weight (for example, Mw = 5 × 10 ⁴ to 1 × 10 ⁶ ) is desired, it is distributed in at least a part of the process of the dehydration polycondensation reaction. It is necessary to control the gas flow rate to a certain level.

Usually, when an aliphatic polyester having a high weight average molecular weight (for example, Mw = 5 × 10 ⁴ to 1 × 10 ⁶ ) is desired, the flow rate of the flow gas per 1 g of the prepolymer is 0.02 to 200 [ ml / min] is preferred, 0.3 to 150 [ml / min] is more preferred, and 0.5 to 100 [ml / min] is even more preferred.
When the flow rate of the circulating gas per 1 g of the prepolymer is less than 0.02 [ml / min], the efficiency of removing the produced water in the polycondensation reaction is remarkably deteriorated, and a high weight average molecular weight (for example, Mw = 5 A polyester having × 10 ⁴ to 1 × 10 ⁶ ) cannot be obtained. In terms of linear velocity, it is preferably 0.01 to 500 [cm / sec].

When the solid-phase polymerization step is performed under reduced pressure, the degree of reduced pressure in the reaction system is such that the progress of the polycondensation reaction is substantially maintained and a sufficiently high weight average molecular weight (for example, Mw = 5 × 10 ⁴ to 1 ×). If an aliphatic polyester having 10 ⁶ ) is obtained, there is no particular limitation.
When the solid-phase polymerization step is performed under reduced pressure, the degree of vacuum in the reaction system depends on the polymerization rate, the type and amount of the volatile catalyst, the rate at which the volatile catalyst evaporates from the aliphatic polyester in the solid-phase polymerization, The efficiency is set in consideration of the speed and efficiency of removing water generated by solid phase polymerization, the reached weight average molecular weight (Mw), and the like.

When the solid phase polymerization step is performed under pressure, the pressure in the reaction system substantially maintains the progress of the polycondensation reaction and is sufficiently high in weight average molecular weight (for example, Mw = 5 × 10 ⁴ to 1 × 10 If aliphatic polyester which has ⁶ ) is obtained, it will not restrict | limit in particular.
When the solid phase polymerization process is performed under pressure, the pressure in the reaction system depends on the polymerization rate, the type and amount of volatile catalyst used, and the rate and efficiency with which the volatile catalyst evaporates from the aliphatic polyester in the solid phase polymerization. It is set in consideration of the speed and efficiency of removing water produced by the dehydration polycondensation reaction, the reached weight average molecular weight (Mw), and the like. Generally, when a solid phase polymerization process is performed under pressure, the volatile catalyst is less likely to be volatilized.

The method for reducing the catalyst concentration in the aliphatic polyester is that the catalyst concentration in the finally obtained aliphatic polyester after the solid phase polymerization is changed before the solid phase polymerization and / or during the solid phase polymerization. There is no particular restriction as long as the catalyst charged in the catalyst is less than the theoretical catalyst concentration when all of the catalyst is left in the aliphatic polyester.
For example, in the case where the catalyst concentration in the aliphatic polyester is simultaneously reduced while performing the solid phase polymerization, or when the solid state polymerization is performed by changing the reaction conditions in multiple stages or continuously, the solid phase in the first half of the reaction In the polymerization, solid phase polymerization is performed without reducing the catalyst concentration in the aliphatic polyester as much as possible, and the catalyst concentration in the aliphatic polyester is simultaneously reduced while performing the solid phase polymerization in the solid phase polymerization in the latter half of the reaction. be able to.
Further, in the solid phase polymerization, after the weight average molecular weight does not increase, the catalyst may be removed while maintaining the reaction conditions in order to further reduce the catalyst concentration in the aliphatic polyester.

In general, the relationship between the reaction conditions and the volatility of the catalyst is as follows (1) to (4).
(1) When the reaction pressure is increased, the volatile catalyst is less likely to be volatilized from the aliphatic polyester.
(2) When the reaction temperature is increased, the volatile catalyst is easily volatilized from the aliphatic polyester.
(3) When the reaction time is lengthened, the volatile catalyst is easily volatilized from the aliphatic polyester.
(4) When the flow rate of the circulation gas is increased, the volatile catalyst is easily volatilized from the aliphatic polyester.

  In the present invention, by using a volatile catalyst and volatilizing the volatile catalyst in the same reaction system at the same time and / or after the solid phase polymerization, the high molecular weight and without a complicated catalyst removal step. An aliphatic polyester having excellent stability can be produced.

[Catalyst concentration (C _A ) in aliphatic polyester finally obtained after solid-phase polymerization]
Generally, after solid-phase polymerization, the final catalyst concentration (C _A ) in the aliphatic polyester should be as low as possible in consideration of stability during processing and catalyst elution and bleed out during use. Is preferred.

When an organic sulfonic acid compound is used as a volatile catalyst in the method of the present invention, the relationship between the residual catalyst concentration and the stability varies greatly depending on the type of the organic sulfonic acid compound. It is preferable to express it by the concentration of the sulfonic acid functional group or the concentration of the elemental sulfur related to the catalyst activity.
In consideration of the above points, when using an organic sulfonic acid compound as a volatile catalyst, the catalyst concentration (C _A ) in the aliphatic polyester finally obtained after solid-phase polymerization is converted to a sulfur content. Therefore, it is preferably 300 [ppm] or less, and more preferably 150 [ppm] or less.

[Weight average molecular weight (Mw) of aliphatic polyester]
The weight average molecular weight (Mw) and molecular weight distribution of the aliphatic polyester according to the present invention are the reaction conditions such as the type and amount of the catalyst, the reaction pressure, the reaction temperature, the reaction time, the flow rate of the flow gas, and the particle diameter of the aliphatic polyester. By selecting appropriately, it can control to a desired thing.
The weight average molecular weight (Mw) of the aliphatic polyester according to the present invention is generally preferably in the range of about 50,000 to 1,000,000, and in the range of 70,000 to 500,000. More preferred are those in the range of 100,000 to 300,000.

[Molding method and application of aliphatic polyester]
The aliphatic polyester according to the present invention can be suitably used as a substitute for a resin that has been publicly known and used for medical purposes, food packaging, and general purpose before the present application.
The use of the aliphatic polyester according to the present invention is not particularly limited. However, since the weight average molecular weight is remarkably high and the mechanical properties (tensile strength, tensile elongation, etc.) are excellent, food containers, industrial fibers, Application to films and the like is also suitable.
The method for molding the aliphatic polyester according to the present invention is not particularly limited, and specifically, injection molding, extrusion molding, inflation molding, extrusion hollow molding, foam molding, calendar molding, blow molding, balloon molding, vacuum molding. And a molding method such as spinning.

  In addition, the aliphatic polyester is produced by a suitable molding method, for example, a writing instrument member such as a ballpoint pen, a mechanical pencil, or a pencil, a stationery member, a golf tee, a starting ball-type smoke ball member, or an oral drug product. Capsules, anal / vaginal suppository carrier, skin / mucosal suppository carrier, agricultural chemical capsule, fertilizer capsule, seedling capsule, compost, fishing line spool, fishing float, fake fishing bait, lure, fishery buoy, Hunting decoys, hunting shot capsules, tableware and other camping equipment, nails, stakes, binding materials, anti-slip materials for muddy and snowy roads, blocks, lunch boxes, tableware, lunch boxes and side dishes sold at convenience stores Containers, chopsticks, disposable chopsticks, forks, spoons, skewers, toothpicks, cup ramen cups, cups used in beverage vending machines Containers and trays for foodstuffs such as fresh fish, meat, fruits and vegetables, tofu, sugar beets, trobaco used in the fresh fish market, bottles for dairy products such as milk, yogurt, and lactic acid bacteria beverages, carbonated drinks, soft drinks, etc. Bottles for soft drinks, bottles for liquor drinks such as beer and whiskey, bottles with or without pumps for shampoo and liquid soap, tubes for toothpaste, cosmetic containers, detergent containers, bleach containers, cold boxes, Flower pots, water purifier cartridge casings, casings for artificial kidneys and livers, syringe barrels, cushioning materials for use in transporting home appliances such as TVs and stereos, precision machines such as computers, printers and watches It can be used as a cushioning material for use during transportation, and as a cushioning material for use in transportation of ceramic products such as glass and ceramics. That.

  The present invention is described in detail below with reference to synthesis examples, embodiments, and examples. Note that the descriptions of synthesis examples, embodiments, and examples in the specification of the present application are explanations for supporting the understanding of the contents of the present invention, and the descriptions are based on the basis for narrowly interpreting the technical scope of the present invention. Is not of a character.

The evaluation method used in this example is as follows.
(1) Weight average molecular weight The weight average molecular weight (Mw) of the obtained aliphatic polyester was calculated | required by the gel permeation chromatography (GPC, column temperature 40 degreeC, chloroform solvent) by the comparison with a polystyrene standard sample.
(2) Catalyst concentration (sulfur concentration) in aliphatic polyester
The catalyst concentration (sulfur concentration) in the aliphatic polyester was quantified by ion chromatography.
That is, the gas generated when the sample is heated to 900 ° C. (Ar / O ₂ ) and incinerated in a closed system is absorbed in a constant volume of absorption liquid (1% -H ₂ O ₂ solution) Quantified by chromatography.
The ion chromatography DX-300 type made by Dionex Co., Ltd. was used for the ion chromatography measurement.

(3) Catalyst residual ratio (R)
The catalyst residual ratio (R) was calculated according to the mathematical formula shown in the detailed description of the present invention. However, after the solid phase polymerization, the catalyst concentration C _A of the finally obtained aliphatic polyester sulfur analysis value was determined by (2), was converted to various organic sulfonic acid compounds used in Examples.
In the following examples, after the solid-phase polymerization, the catalyst concentration C _A in the aliphatic polyester finally obtained, and the catalyst charged before and / or during the solid-phase polymerization are all contained in the polyester. The theoretical catalyst concentration C _B in the case of remaining is simply referred to as catalyst concentration C _A and catalyst concentration C _B , respectively.

(4) Weight molecular weight retention ratio during pressing The weight molecular weight retention ratio during pressing was calculated from the ratio of the weight average molecular weight before producing the heated press film at 150 ° C. and the weight average molecular weight after producing the hot press film.
The press film was prepared by subjecting the aliphatic polyester obtained by solid-phase polymerization to a vacuum drying treatment at 60 ° C. for 5 hours, followed by heating at a pressing temperature of 150 ° C. for 3 minutes and a pressing pressure of 10 MPa for 1 minute for a total of 4 minutes. Thus, a film having a thickness of 100 μm was produced.

Example 1
115.1 g (= 1 mol) of succinic acid, 91.0 g (= 1.01 mol) of 1,4-butanediol, and 0.86 g of methanesulfonic acid were placed in a 500 ml round bottom flask equipped with a Dean-Stark trap. The mixture was stirred at 150 ° C./nitrogen atmosphere for 9 hours and further at 150 ° C./15 mmHg for 0.5 hour while distilling off water outside the system. The weight average molecular weight at this time was 27,000.
Thereafter, the reaction solution can be dropped from the bottom of the flask, transferred to a separable flask equipped with a heater, and the reaction solution is dropped into water from the bottom of the flask while keeping the liquid temperature at 140 ° C. to solidify and crystallize. 158.2 g (yield 92%) of the aliphatic polyester prepolymer thus obtained was obtained.
After 60 g of this prepolymer was dried under a nitrogen atmosphere, it was charged into a solid phase polymerization reactor made of SUS, and solid phase polymerization was carried out for 100 hours under the conditions of 100 ° C./nitrogen flow rate of 50 ml / min. The dew point of the nitrogen gas used was −60 ° C.
Furthermore, in order to remove the catalyst, heating was continued at 105 ° C./nitrogen flow rate of 6000 ml / min for 30 hours.
In this way, 57 g (yield 95%) of aliphatic polyester (polybutylene succinate) was obtained. Various physical properties are shown below.
Weight average molecular weight (Mw) = 108,000
Tensile strength = 260 [kg / cm ² ]
Tensile elongation = 480 [%]
Catalyst concentration C _A = 420 [ppm] (sulfur analysis value: 140 [ppm])
Catalyst concentration C _B = 5700 [ppm]
Catalyst residual ratio R = 7.4 [%]
Pressing molecular weight retention = 94 [%]

Example 2
115.1 g (= 1 mol) of succinic acid, 91.0 g (= 1.01 mol) of 1,4-butanediol, and 0.86 g of ethanesulfonic acid were placed in a 500 ml round bottom flask equipped with a Dean-Stark trap. The mixture was stirred at 150 ° C./nitrogen atmosphere for 9 hours and further at 150 ° C./15 mmHg for 0.5 hour while distilling off water outside the system. The weight average molecular weight at this time was 26,000.
Thereafter, the reaction solution can be dropped from the bottom of the flask, transferred to a separable flask equipped with a heater, and the reaction solution is dropped into water from the bottom of the flask while keeping the liquid temperature at 140 ° C. to solidify and crystallize. 157.7 g (yield 92%) of the aliphatic polyester prepolymer thus obtained was obtained.
After 60 g of this prepolymer was dried under a nitrogen atmosphere, it was charged into a solid phase polymerization reactor made of SUS, and solid phase polymerization was carried out for 100 hours under the conditions of 100 ° C./nitrogen flow rate of 50 ml / min. The dew point of the nitrogen gas used was −60 ° C.
Furthermore, in order to remove the catalyst, heating was continued at 105 ° C./nitrogen flow rate of 6000 ml / min for 30 hours.
In this way, 56 g (yield 93%) of aliphatic polyester (polybutylene succinate) was obtained. Various physical properties are shown below.
Weight average molecular weight (Mw) = 103,000
Tensile strength = 250 [kg / cm ² ]
Tensile elongation = 480 [%]
Catalyst concentration C _A = 520 [ppm] (Sulfur analysis value: 150 [ppm])
Catalyst concentration C _B = 5800 [ppm]
Catalyst residual ratio R = 9.0 [%]
Pressing molecular weight retention = 93 [%]

Example 3
A 500 ml round bottom flask equipped with a Dean-Stark trap containing 118.1 g (= 1 mol) of succinic acid, 91.0 g (= 1.01 mol) of 1,4-butanediol, and 0.86 g of 1-propanesulfonic acid. The mixture was stirred at 150 ° C./nitrogen atmosphere for 9 hours and further at 150 ° C./15 mmHg for 0.5 hour while distilling off water outside the system. The weight average molecular weight at this time was 26,000.
Thereafter, the reaction solution can be dropped from the bottom of the flask, transferred to a separable flask equipped with a heater, and the reaction solution is dropped into water from the bottom of the flask while keeping the liquid temperature at 140 ° C. to solidify and crystallize. 157.0 g (yield 91%) of the aliphatic polyester prepolymer thus obtained was obtained.
After 60 g of this prepolymer was dried under a nitrogen atmosphere, it was charged into a solid phase polymerization reactor made of SUS, and solid phase polymerization was carried out for 100 hours under the conditions of 100 ° C./nitrogen flow rate of 50 ml / min. The dew point of the nitrogen gas used was −60 ° C.
Furthermore, in order to remove the catalyst, heating was continued at 105 ° C./nitrogen flow rate of 6000 ml / min for 30 hours.
In this way, 56 g (yield 93%) of aliphatic polyester (polybutylene succinate) was obtained. Various physical properties are shown below.
Weight average molecular weight (Mw) = 103,000
Tensile strength = 250 [kg / cm ² ]
Tensile elongation = 480 [%]
Catalyst concentration C _A = 580 [ppm] (Sulfur analysis value: 150 [ppm])
Catalyst concentration C _B = 5900 [ppm]
Catalyst residual ratio R = 9.8 [%]
Pressing molecular weight retention = 93 [%]

Comparative Example 1
A 500 ml round bottom flask equipped with a Dean-Stark trap was charged with 118.1 g (= 1 mol) of succinic acid, 91.0 g (= 1.01 mol) of 1,4-butanediol and 0.86 g of metallic tin. The mixture was heated and stirred while distilling water out of the system at 150 ° C./nitrogen atmosphere for 9 hours and further at 150 ° C./15 mmHg for 0.5 hour. The weight average molecular weight at this time was 24,000.
Thereafter, the reaction solution can be dropped from the bottom of the flask, transferred to a separable flask equipped with a heater, and the reaction solution is dropped into water from the bottom of the flask while keeping the liquid temperature at 140 ° C. to solidify and crystallize. 157.7 g (yield 92%) of the aliphatic polyester prepolymer thus obtained was obtained.
After 60 g of this prepolymer was dried in a nitrogen atmosphere, it was charged into a solid phase polymerization reactor manufactured by SUS, and was subjected to 100 ° C./nitrogen flow rate of 50 ml / min for 100 hours, 105 ° C./nitrogen flow rate of 6000 ml / min. Solid phase polymerization was carried out for 130 hours in total for 30 hours in min. The yield of the aliphatic polyester at the time when the solid phase polymerization was completed was 55 g (yield 92%). The dew point of the nitrogen gas used was −60 ° C.
Thereafter, the polymer after the solid phase polymerization was dissolved in 500 ml of chloroform, and the polymer was precipitated with 6000 ml of acetone. Thereafter, in order to remove the catalyst, sludge was performed with 500 ml of methyl tertiary butyl ether containing 0.5 wt% hydrochloric acid, followed by filtration twice. Finally, the polymer washed with 1000 ml of methyl tertiary butyl ether was dried to obtain 52 g (yield 87%) of an aliphatic polyester (polybutylene succinate).
Various physical properties are shown below. The catalyst concentration (tin concentration) was quantified by fluorescent X-ray analysis.
Weight average molecular weight (Mw) = 98,000
Tensile strength = 230 [kg / cm ² ]
Tensile elongation = 470 [%]
Catalyst concentration (tin concentration) C _A = 5900 [ppm]
Catalyst concentration (tin concentration) C _B = 5900 [ppm]
Catalyst residual ratio R = 100 [%]
Tin concentration after catalyst removal = 20 [ppm]
Pressing molecular weight retention = 93%

Comparative Example 2
A 500 ml round bottom flask equipped with a Dean-Stark trap was charged with 118.1 g (= 1 mol) of succinic acid, 91.0 g (= 1.01 mol) of 1,4-butanediol and 0.86 g of metallic tin. The mixture was heated and stirred while distilling water out of the system at 150 ° C./nitrogen atmosphere for 9 hours and further at 150 ° C./15 mmHg for 0.5 hour. The weight average molecular weight at this time was 24,000.
Thereafter, the reaction solution can be dropped from the bottom of the flask, transferred to a separable flask equipped with a heater, and the reaction solution is dropped into water from the bottom of the flask while keeping the liquid temperature at 140 ° C. to solidify and crystallize. 157.7 g (yield 92%) of the aliphatic polyester prepolymer thus obtained was obtained.
After 60 g of this prepolymer was dried in a nitrogen atmosphere, it was charged into a solid phase polymerization reactor manufactured by SUS, and was subjected to 100 ° C./nitrogen flow rate of 50 ml / min for 100 hours, 105 ° C./nitrogen flow rate of 6000 ml / min. Solid phase polymerization was carried out for 130 hours in total for 30 hours in min. The yield of the aliphatic polyester (polybutylene succinate) at the time when the solid phase polymerization was completed was 55 g (yield 92%). The dew point of the nitrogen gas used was −60 ° C.
Various physical properties are shown below. The catalyst concentration (tin concentration) was quantified by fluorescent X-ray analysis.
Weight average molecular weight (Mw) = 98,000
Catalyst concentration (tin concentration) C _A = 5900 [ppm]
Catalyst concentration (tin concentration) C _B = 5900 [ppm]
Catalyst residual ratio R = 100 [%]
Pressing molecular weight retention = 30%

Effect of the invention

  Since the aliphatic polyester production method of the present invention uses a volatile catalyst as a catalyst, the catalyst can be removed while maintaining the same reaction system simultaneously with and / or after solid-phase polymerization. Compared with conventional techniques that require a catalyst removal step, the manufacturing process can be streamlined. Therefore, the high molecular weight aliphatic polyester obtained by the present invention has the same stability as the conventional aliphatic polyester subjected to catalyst removal. Furthermore, since the production method of the aliphatic polyester according to the present invention can improve the volumetric efficiency of the equipment as compared with the production method in which the polycondensation reaction is performed in an organic solvent, the equipment cost can be kept low.

Claims (7)

An aliphatic polyester prepolymer comprising a crystallized aliphatic dihydric alcohol and an aliphatic divalent carboxylic acid having a weight average molecular weight (Mw ₁ ) in the numerical range represented by the formula (1) (Equation 1), By solid-phase polymerization in the presence of a volatile catalyst that is an organic sulfonic acid compound , the weight average molecular weight (Mw) in the numerical range represented by Formula (2) (Formula 2) and Formula (3) (Formula 3) ₂ ) A method for producing an aliphatic polyester, comprising obtaining an aliphatic polyester having
[Expression 1]

[Expression 2]

[Equation 3]

2. The method for producing an aliphatic polyester according to claim 1, wherein the catalyst residual ratio R represented by Formula (4) (Equation 4) is 50% or less.
[Expression 4]

(In Formula (4), R is a catalyst residual rate [%] which is a measure of a change in catalyst concentration before and after solid phase polymerization, and C _B [ppm] is calculated by Formula (5) (Formula 5). The theoretical catalyst concentration in the case where all of the catalyst charged in the reaction system before solid phase polymerization and / or during solid phase polymerization remains in the aliphatic polyester, and C _A [ppm] is the formula (6) ( The catalyst concentration in the aliphatic polyester finally obtained after completion of solid-phase polymerization, calculated by Equation 6))
[Equation 5]

(In Formula (5), W _B [g] is the total weight of the catalyst charged in the reaction system before and / or during the solid phase polymerization, and W _P [g] is the end of the solid phase polymerization. And the weight of the aliphatic polyester finally obtained)
[Formula 6]

(In Formula (6), W _A [g] is the weight of catalyst contained in the aliphatic polyester finally obtained after completion of solid-phase polymerization, and W _P [g] is the end of solid-state polymerization. And the weight of the aliphatic polyester finally obtained)
The aliphatic polyester prepolymer is a polybutylene succinate prepolymer comprising succinic acid and 1,4-butanediol, and the aliphatic polyester is polybutylene succinate. The aliphatic polyester prepolymer according to claim 1 or 2, wherein the aliphatic polyester prepolymer is a polybutylene succinate. Production method.
The organic sulfonic acid compound contains at least one selected from the group consisting of methanesulfonic acid, ethanesulfonic acid, 1-propanesulfonic acid, benzenesulfonic acid, p-chlorobenzenesulfonic acid, and m-xylene-4-sulfonic acid. The method for producing an aliphatic polyester according to any one of claims 1 to 3 .
The production of the aliphatic polyester according to any one of claims 1 to 3, wherein the catalyst concentration in the finally obtained aliphatic polyester is 0 to 300 ppm in terms of sulfur content. Method.
As the step (A), an aliphatic dihydric alcohol and an aliphatic divalent carboxylic acid, the presence or absence of a catalyst of a volatile catalyst is an organic sulfonic acid compound, the presence or absence of a solvent, heavy A step of producing an aliphatic polyester prepolymer having a weight average molecular weight (Mw ₁ ) in a numerical range represented by Formula (1) (Equation 7) by a condensation reaction;
[Expression 7]

As the step (B), a step of crystallizing the aliphatic polyester prepolymer obtained in the step (A),
(C) As the step, the step of solid-phase polymerization of the crystallized aliphatic polyester prepolymer obtained in the step (B) in the presence of a volatile catalyst that is an organic sulfonic acid compound ,
Composed of steps consisting of, equation (2) (8) and Equation (3) the production method of aliphatic polyester having a weight average molecular weight in the numerical range indicated by (Equation 9) (Mw _2).
[Equation 8]

[Equation 9]

The aliphatic dihydric alcohol is 1,4-butanediol, the aliphatic divalent carboxylic acid is succinic acid, and the volatile catalyst is methanesulfonic acid, ethanesulfonic acid, 1-propanesulfonic acid, benzenesulfonic acid, p- The method for producing an aliphatic polyester according to claim 6 , comprising at least one selected from the group consisting of chlorobenzenesulfonic acid and m-xylene-4-sulfonic acid.