JP2014114418A - Method for producing aliphatic polyester - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing an aliphatic polyester having excellent hydrolysis resistance and thermal stability with a high productivity by shortening the polymerization reaction time without complicating a reaction process.SOLUTION: In the method for producing an aliphatic polyester, comprising using, as main raw materials, an aliphatic dicarboxylic acid and an aliphatic diol and producing the aliphatic polyester through an esterification reaction and/or a transesterification reaction, and a polycondensation reaction, at an arbitrary stage to the initiation of the polycondensation reaction, an aromatic dicarboxylic acid is added to the reaction system in an amount of 0.025 to 10 mol% with respect to the aliphatic dicarboxylic acid.

Description

  The present invention relates to a method for producing an aliphatic polyester. Specifically, the present invention relates to an efficient method for producing an aliphatic polyester having a high molecular weight and high thermal stability.

  The aliphatic polyester having biodegradability has been applied to fibers, molded articles, films, sheets, and the like as resins that can avoid environmental burdens more than ever since the awareness of environmental problems is increasing. For example, polybutylene succinate and / or polybutylene adipate having biodegradability has been developed as a general-purpose resin in place of polyethylene because it has similar mechanical properties to polyethylene.

  In general, as an economically advantageous method for producing a polyester, an ester low polymer can be obtained by a direct esterification reaction between a dicarboxylic acid and a diol in the presence of a catalyst or an ester exchange reaction between an alkyl ester of a dicarboxylic acid and a diol. After producing this, a method for producing a polyester having a high degree of polymerization by distilling the produced diol off from the reaction system while carrying out a transesterification reaction under heating and reduced pressure has been known and adopted for a long time.

  However, in the case of aliphatic polyesters, the thermal stability is often low, and the molecular weight is lowered due to thermal decomposition during the polycondensation reaction. Therefore, the conventional polyester production method has a high degree of polymerization that has practically sufficient strength. This polyester was not easily obtained, and once thermal decomposition was caused, it tended to be markedly colored. From such a background, various devices have been devised in the manufacturing method.

  In general, as a method for producing a polyester having a high degree of polymerization, for example, melt polymerization is performed using a titanium compound or a zirconium compound as a catalyst, and diisocyanate (for example, see Patent Document 1) or diphenyl carbonate (for example, Patent Document 2) as a chain extender. A method has been proposed in which the melt viscosity of a polymer is increased by extending the polymer chain length by adding a polymer to the polymer. Since the method of adding these chain extenders can easily increase the molecular weight of the polyester, it is considered to be an effective method for producing an aliphatic polyester at first glance. Problems such as complications, and the resulting polyester has a tendency to decrease biodegradability due to urethane bonds and carbonate bonds in the molecule in addition to a slight decrease in crystallinity and melting point. There is.

  Further, as a branching agent, 0.5 to 5 mol% of a trifunctional oxycarboxylic acid or 0.1 to 3 mol% of a tetrafunctional oxycarboxylic acid is added to the dicarboxylic acid to branch the structure of the polyester. Is disclosed (for example, see Patent Document 3). However, polyesters that have increased melt viscosity by introducing a large amount of trifunctional or tetrafunctional oxycarboxylic acid in this way tend to have higher polymer terminal (hydroxyl group or carboxyl group) concentration that can cause a decrease in thermal stability. In addition, the practical physical properties are insufficient.

JP-A-4-189822 JP-A-8-301999 Japanese Patent Laid-Open No. 5-170885

  An object of the present invention is to provide a method for producing an aliphatic polyester excellent in hydrolysis resistance and thermal stability with high productivity by shortening the polymerization reaction time without complicating the reaction process.

  As a result of intensive studies to solve the above-mentioned problems, the inventors of the present invention have prepared an aromatic dicarboxylic acid before the polycondensation reaction in a method for producing an aliphatic polyester comprising an aliphatic diol component and an aliphatic carboxylic acid component. By adding at a predetermined ratio, the polymerization reaction time is shortened without complicating the reaction process, and an aliphatic polyester excellent in hydrolysis resistance and thermal stability is found with a high productivity, The present invention has been completed.

  The gist of the present invention is “in the method of producing an aliphatic polyester using an aliphatic dicarboxylic acid and an aliphatic diol as main raw materials and undergoing an esterification and / or transesterification reaction and a polycondensation reaction. In this stage, an aliphatic dicarboxylic acid in an amount of 0.025 mol% to 10 mol% based on the aliphatic dicarboxylic acid is added to the reaction system. ”

  ADVANTAGE OF THE INVENTION According to this invention, the polymerization reaction time is shortened without making a reaction process complicated, The method of manufacturing aliphatic polyester excellent in hydrolysis resistance and heat stability with high productivity is provided.

Below, the typical aspect for implementing this invention is demonstrated concretely, However, This invention is not limited to the following aspects, unless the summary is exceeded.
The present invention relates to a method for producing an aliphatic polyester by using an aliphatic dicarboxylic acid and an aliphatic diol as main raw materials and undergoing esterification and / or transesterification reaction and polycondensation reaction, and any stage until the start of the polycondensation reaction. Then, a predetermined amount of aromatic dicarboxylic acid is added to the reaction system with respect to the aliphatic dicarboxylic acid.

  In the present invention, “mainly using an aliphatic dicarboxylic acid and an aliphatic diol” means that the aliphatic diol unit and the aliphatic dicarboxylic acid are based on 100 mol% of all monomer units of the aliphatic polyester to be produced. This means that the raw material is set so that the sum of the acid units is 80 mol% or more. Moreover, with respect to aliphatic dicarboxylic acid, the quantity with respect to the aliphatic dicarboxylic acid used as a raw material is meant.

In addition, “esterification and / or transesterification” means that the esterification rate of the esterification reaction product is 80% or more. Here, the esterification rate indicates the ratio of the esterified acid component to the total acid component in the esterification reaction product, and is represented by the following formula.
Esterification rate (%) = (saponification value−acid value) / saponification value) × 100

<Aliphatic diol>
The aliphatic diol according to the present invention is not particularly limited as long as it is an aliphatic compound having two hydroxy groups, but the lower limit of the carbon number is 2 or more, and the upper limit is usually 10 or less, preferably 6 or less. Of the aliphatic diol. Among these, an aliphatic diol having an even number of carbon atoms or a mixture thereof is preferable because a polyester having a higher melting point can be obtained.

Specific examples of the aliphatic diol include, for example, ethylene glycol, 1,3-trimethylene glycol, 1,2-propylene glycol, 1,4-butanediol, neopentyl glycol, 1,6-hexamethylene glycol, decamethylene. Examples include glycol and 1,4-cyclohexanedimethanol. These may be used alone or as a mixture of two or more.

  Of these, ethylene glycol, 1,3-trimethylene glycol, 1,4-butanediol and 1,4-cyclohexanedimethanol are preferred, and among them, ethylene glycol and 1,4-butanediol, and mixtures thereof are preferred. More preferably, 1,4-butanediol is the main component, or 1,4-butanediol is particularly preferable. The main component as used herein refers to a component that usually occupies 60 mol% or more, preferably 70 mol% or more, more preferably 80 mol% or more, and particularly preferably 90 mol% or more with respect to all aliphatic diol units. .

  Further, both terminal hydroxy polyethers may be used by mixing with the above aliphatic diol. Examples of both-terminal hydroxy polyethers include those having a lower limit of carbon number of usually 4 or more, preferably 10 or more, and an upper limit of usually 1000 or less, preferably 200 or less, more preferably 100 or less.

  Specific examples of both terminal hydroxy polyethers include diethylene glycol, triethylene glycol, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, poly 1,3-propanediol, and poly 1,6-hexamethylene glycol. . In addition, a copolymerized polyether of polyethylene glycol and polypropylene glycol can be used. The use amount of these both terminal hydroxy polyethers is usually 90% by weight or less, preferably 50% by weight or less, more preferably 30% by weight or less as the content of both terminal hydroxy polyether units in the polyester.

  In the present invention, these diols may be derived from biomass resources. Specifically, the diol compound may be produced directly from a carbon source such as glucose by a fermentation method, or a dicarboxylic acid, dicarboxylic acid anhydride, or cyclic ether obtained by the fermentation method is converted into a diol compound by a chemical reaction. May be.

  For example, 1,4-butanediol is produced by chemical synthesis from succinic acid, succinic anhydride, succinic acid ester, maleic acid, maleic anhydride, maleic acid ester, tetrahydrofuran, γ-butyrolactone, etc. obtained by fermentation. Alternatively, 1,4-butanediol may be produced from 1,3-butadiene obtained by a fermentation method. Among these, a method of hydrogenating succinic acid with a reduction catalyst to obtain 1,4-butanediol is efficient and preferable.

<Aliphatic dicarboxylic acid>
The aliphatic dicarboxylic acid according to the present invention is not particularly limited as long as it is derived from an aliphatic compound having two carboxyl groups, but the lower limit of the carbon number is 2 or more, and the upper limit is usually 12 or less. Preferably, 6 or less aliphatic dicarboxylic acids are used.
Specific examples of the aliphatic dicarboxylic acid include oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, suberic acid, sebacic acid, and cyclohexanedicarboxylic acid, which are usually chains having 2 to 12 carbon atoms. Or alicyclic dicarboxylic acids. Moreover, as derivatives of aliphatic dicarboxylic acids, alkyl esters having 1 to 4 carbon atoms such as methyl esters, ethyl esters, propyl esters and butyl esters of aliphatic dicarboxylic acids, and aliphatic dicarboxylic acids such as succinic anhydride, etc. Cyclic acid anhydrides can also be used. These may be used alone or as a mixture of two or more. Among these, a chain aliphatic dicarboxylic acid having 2 to 6 carbon atoms is preferable, and specifically, adipic acid, succinic acid, or a mixture thereof is preferable. Moreover, as a derivative of aliphatic dicarboxylic acid, the methyl ester of adipic acid and succinic acid, or a mixture thereof is preferable.

  These aliphatic dicarboxylic acids can be produced using petroleum resource derivatives as starting materials, but can also be produced using carbon sources derived from renewable plant resources. Carbon sources derived from plant resources usually include carbohydrates such as galactose, lactose, glucose, fructose, glycerol, sucrose, saccharose, starch and cellulose; fermentation of polyalcohols such as glycerin, mannitol, xylitol and ribitol Glucose, fructose, and glycerol are preferable, and glucose is particularly preferable. As a broader plant-derived material, cellulose, which is the main component of paper, is preferable. Moreover, the starch saccharified liquid, molasses, etc. containing the said fermentable saccharides are also used. These fermentable carbohydrates may be used alone or in combination of two or more.

As a method for producing these aliphatic dicarboxylic acids, a method of microbial conversion of a carbon source derived from plant resources can be employed. However, the microorganism to be used is not particularly limited as long as it has the ability to produce dicarboxylic acids. For example, anaerobic bacteria such as Anaerobiospirillum (USP 5143833), Actinobacillus (USP-5504004), Escherichia (
USP-5770435) and other facultative anaerobes such as the genus Corynebacterium (JP111135)
88), aerobic bacteria belonging to the genera Bacillus, Rizobium, Brevibacterium, Arthrobacter (Japanese Patent Laid-Open No. 2003-235593), anaerobic rumen bacteria such as Bacteroides ruminicola, Bacteroides amylophilus, E. coli (J. Bacteriol., 57: 147-158) or E. coli. E. coli strains (Tokuyo 2000-500333, USP-6159738) can be used.

<Aromatic dicarboxylic acid>
The aromatic dicarboxylic acid according to the present invention is not particularly limited as long as it is an aromatic compound having two carboxyl groups. The aromatic compound may be a compound having aromaticity, a benzene aromatic compound having an aromatic ring in which one or a plurality of benzene rings are condensed or connected, or a benzene ring. Non-benzenoid aromatic compounds that have no aromaticity but exhibit aromaticity.
Among them, benzene-based aromatic dicarboxylic acid is preferably used from the viewpoint of reactivity, and the number of aromatic rings to which the benzene ring is condensed or connected is usually 1 to 5, preferably 1 to 3, particularly preferably. It is a dicarboxylic acid compound having one or two benzene rings. If the number of aromatic rings is large, there may be a case where there is not sufficient molecular chain extension action due to a decrease in reactivity.

  Specifically, as an aromatic dicarboxylic acid compound having one benzene ring, terephthalic acid, phthalic acid, isophthalic acid, dibromoisophthalic acid, sodium sulfoisophthalate, phenylenedioxydicarboxylic acid; aromatic dicarboxylic acid having a plurality of aromatic rings Biphenyl dicarboxylic acid, diphenyl ether dicarboxylic acid, diphenyl ketone dicarboxylic acid, diphenoxyethane dicarboxylic acid, diphenyl sulfone dicarboxylic acid, naphthalenedicarboxylic acid; non-benzenoid aromatic dicarboxylic acid as pyridine dicarboxylic acid, furandicarboxylic acid, thiophene dicarboxylic acid And the like. In addition, the substituent position of dicarboxylic acid is not specifically limited.

Moreover, the C1-C4 alkylester derivative of these aromatic dicarboxylic acids may be sufficient.
Among these, terephthalic acid, isophthalic acid, naphthalene dicarboxylic acid or their alkyl ester derivatives having 1 to 4 carbon atoms are preferable, and terephthalic acid, naphthalene dicarboxylic acid or their alkyl ester derivatives having 1 to 2 carbon atoms are particularly preferable. . These may be used alone or in combination of two or more.

  The addition amount of the aromatic dicarboxylic acid in the method for producing the aliphatic polyester of the present invention is 0.025 mol% or more and 10 mol% or less, preferably 0.05 mol% or more, more preferably, based on the aliphatic dicarboxylic acid component. Is 0.1 mol% or more, most preferably 0.3 mol% or more, while the upper limit is preferably 8 mol% or less, more preferably 6 mol% or less, particularly preferably 5 mol% or less, and most preferably 4%. It is as follows. If the amount of aromatic dicarboxylic acid added is too large, the biodegradability deteriorates, and if it is too small, the effect of improving the molecular weight (solution viscosity), thermal stability and shortening the polymerization reaction time does not occur.

In the method for producing an aliphatic polyester of the present invention, the addition of an aromatic dicarboxylic acid before the polycondensation reaction reduces the amount of terminal carboxyl groups, and the detailed effect of shortening the polymerization time is unknown. The inventors believe that the aromatic dicarboxylic acid component acts as a chain extender between polyester oligomers having a certain molecular chain length, thereby promoting the growth of the molecular chain length and obtaining the above effect.
More specifically, by controlling the addition amount of the aromatic dicarboxylic acid, the reaction rate of the aromatic dicarboxylic acid is controlled, and further, as described later, by optimizing the addition time of the aromatic dicarboxylic acid, It is considered that the oligomer growth by the condensation of aliphatic dicarboxylic acid precedes, and then the aromatic dicarboxylic acid can chain-extend the oligomers.

<Other copolymer components>
In the method for producing an aliphatic polyester of the present invention, the polymerization rate and various physical properties of the resulting polyester may be improved by adding other copolymerization components.
Specific examples of other copolymerization components include bifunctional oxycarboxylic acids, trifunctional or higher polyhydric alcohols, trifunctional or higher polyvalent carboxylic acids and / or their anhydrides to form a crosslinked structure. And at least one polyfunctional compound selected from the group consisting of tri- or higher functional oxycarboxylic acids. Among these copolymer components, a bifunctional and / or trifunctional or higher functional oxycarboxylic acid is particularly preferably used because a copolymer polyester having a high degree of polymerization tends to be easily produced. Among them, the use of a tri- or higher functional oxycarboxylic acid is most preferable since a polyester having a high degree of polymerization can be easily produced with a very small amount.

  Specific examples of the bifunctional oxycarboxylic acid include lactic acid, glycolic acid, hydroxybutyric acid, hydroxycaproic acid, 2-hydroxy-3,3-dimethylbutyric acid, 2-hydroxy-3-methylbutyric acid, and 2-hydroxyiso Examples include caproic acid, and these may be esters of oxycarboxylic acid, lactones such as caprolactone, or derivatives such as oxycarboxylic acid polymers. These oxycarboxylic acids can be used alone or as a mixture of two or more. When optical isomers exist in these, any of D-form, L-form, and racemic form may be sufficient. Of these, readily available lactic acid or glycolic acid is particularly preferable. As an acquisition form, an aqueous solution of 30 to 95% by weight is preferable because it can be easily obtained.

  The amount of the bifunctional oxycarboxylic acid is usually 0.02 mol% or more, preferably 0.5 mol% or more, more preferably as a lower limit with respect to 100 mol% of all monomer units constituting the polyester. 1.0 mol% or more. On the other hand, the upper limit of the amount used is usually 30 mol% or less, preferably 20 mol% or less, more preferably 10 mol% or less.

Specific examples of the trifunctional or higher polyhydric alcohol include glycerin, trimethylolpropane, 1,2,4-butanetriol, pentaerythritol, and the like. These may be used alone or as a mixture of two or more. You can also.

Specific examples of the trifunctional or higher polyvalent carboxylic acid or anhydride thereof include propanetricarboxylic acid, trimellitic acid, trimellitic anhydride, pyromellitic acid, pyromellitic anhydride,
Examples thereof include benzophenone tetracarboxylic acid anhydride and cyclopentatetracarboxylic acid anhydride, and these can be used alone or as a mixture of two or more.

  Specific examples of the trifunctional or higher functional oxycarboxylic acid include malic acid, hydroxyglutaric acid, hydroxymethylglutaric acid, tartaric acid, citric acid, hydroxyisophthalic acid, hydroxyterephthalic acid, and the like. It can also be used as a mixture of seeds or more. In particular, malic acid, tartaric acid, citric acid and a mixture thereof are preferable because of easy availability.

  The amount of the above-mentioned trifunctional or higher polyfunctional compound unit causes the generation of gel, and therefore the upper limit is usually 3 mol% or less, preferably 1 with respect to 100 mol% of all monomer units constituting the polyester. The mol% or less, more preferably 0.50 mol% or less, particularly preferably 0.3 mol% or less. On the other hand, when a tri- or higher functional compound is used as a copolymerization component for the purpose of easily producing a polyester having a high degree of polymerization, the lower limit of the amount of use at which the effect is manifested is the total monomer units constituting the polyester. It is 0.0001 mol% or more normally with respect to 100 mol%, Preferably it is 0.001 mol% or more, More preferably, it is 0.005 mol% or more, Most preferably, it is 0.01 mol% or more.

<Method for producing aliphatic polyester>
As a method for producing the aliphatic polyester of the present invention, if a step of performing a polycondensation reaction after performing an esterification reaction and / or a transesterification reaction using an aliphatic dicarboxylic acid and an aliphatic diol as main raw materials will be described later. Except for the characteristics of the present invention, known manufacturing methods can be used. From the viewpoint of economy and simplicity of the production process, a method of producing a polyester by melt polymerization is preferably used.

The polycondensation reaction is preferably performed in the presence of a polymerization catalyst. The addition timing of the polymerization catalyst is not particularly limited as long as it is before the polycondensation reaction, and it may be added when the raw materials are charged, or may be added at the start of pressure reduction.
The polymerization catalyst is generally a compound containing a group 1 to group 15 metal element excluding hydrogen and carbon in the periodic table. Specifically, at least one metal selected from the group consisting of titanium, zirconium, tin, antimony, cerium, germanium, zinc, cobalt, manganese, iron, aluminum, magnesium, calcium, strontium, sodium and potassium A compound containing an organic group such as a carboxylate salt, an alkoxy salt, an organic sulfonate salt, or a β-diketonate salt, and an inorganic compound such as an oxide or composite oxide or halide of the above-mentioned metal or a mixture thereof. Can be mentioned.

Furthermore, when a known layered silicate described in “Clay Minerals” by Haruo Shiramizu, Asakura Shoten (1995) or the like is used alone or in combination with the above metal compound, the polymerization rate may be improved. Therefore, such a catalyst system is also preferably used.
Specific examples of layered silicates include kaolins such as dickite, nacrite, kaolinite, anorokite, metahalloysite, halloysite, serpentine groups such as chrysotile, lizardite, antigolite, montmorillonite, zauconite, beidellite, Smectites such as nontronite, saponite, hectorite, stevensite, vermiculites such as vermiculite, mica, illite, sericite, mica such as sea green stone, attapulgite, sepiolite, palygorskite, bentonite, pyrophyllite, talc And chlorite group.

Among these, metal compounds containing titanium, zirconium, germanium, zinc, aluminum, magnesium and calcium, and mixtures thereof are preferable, and among these, titanium compounds, zirconium compounds and germanium compounds are particularly preferable. Also,
When the catalyst is in a molten or dissolved state at the time of polymerization, the polymerization rate may increase. Therefore, a catalyst that is liquid at the time of polymerization or is soluble in an ester low polymer or polyester is preferably used.

Titanium compounds include tetra-n-propyl titanate, tetraisopropyl titanate and tetra-n-butyl titanate, titanium (oxy) acetylacetonate, titanium tetraacetylacetonate, titanium bis (ammonium lactate) dihydroxide, polyhydroxytitanium stearate Preferred are rate, titanium lactate, butyl titanate dimer, titanium oxide, titania / silica composite oxide (for example, product name: C-94 manufactured by Acordis Industrial Fibers), tetra-n-butyl titanate, titanium (oxy) acetylacetate Nate, titanium tetraacetylacetonate, polyhydroxytitanium stearate, titanium lactate, butyl titanate dimer, titania / silica composite oxide (for example, product names manufactured by Acordis Industrial Fibers: -94) and the like are preferable.

  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 and the like are preferable.

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

  The amount of catalyst added in the case of using a metal compound as the polymerization catalyst is such that the lower limit is usually 0.1 ppm or more, preferably 1 ppm or more, and the upper limit is usually 30000 ppm or less, preferably as the amount of metal relative to the produced polyester. Is 500 ppm or less, more preferably 250 ppm or less. If the amount of catalyst used is too large, it is not only economically disadvantageous, but also the thermal stability and hydrolysis resistance of the polymer may decrease due to an increase in the residual catalyst concentration. On the other hand, when the amount is too small, the polymerization activity is lowered, and accordingly, decomposition of the polymer is induced during the production of the polymer, and it tends to be difficult to obtain a polymer exhibiting practically useful physical properties.

  In addition, from the viewpoint of providing an aliphatic polyester having a biodegradable function and environmentally friendly, among the above polymerization catalysts, in particular, tin-containing compounds and antimony-containing compounds are relatively highly toxic, It is preferable to limit the amount of these compounds used. Therefore, the amount used when a tin-containing compound or an antimony-containing compound is used as a polymerization catalyst is usually 60 ppm or less, preferably 10 ppm or less, more preferably 1 ppm or less as a metal amount with respect to the produced polyester in the case of a tin compound catalyst. On the other hand, in the case of an antimony compound catalyst, the amount of metal relative to the polyester produced is usually 100 ppm or less, preferably 50 ppm or less, more preferably 10 ppm or less.

A conventionally well-known range can be employ | adopted for conditions, such as temperature at the time of manufacturing the aliphatic polyester of this invention, time, and a pressure.
As for the reaction temperature of the esterification reaction and / or transesterification reaction between the aliphatic dicarboxylic acid component and the aliphatic diol component, the lower limit is usually 150 ° C. or higher, preferably 180 ° C. or higher, and the upper limit is usually 260 ° C. or lower, preferably 250 ° C. It is as follows. The reaction atmosphere is usually an inert gas atmosphere such as nitrogen or argon. The reaction pressure is usually normal pressure to 10 kPa, but normal pressure is preferred.
The reaction time is usually 1 hour or longer, and the upper limit is usually 10 hours or shorter, preferably 4 hours or shorter.

In the subsequent polycondensation reaction, the lower limit of the pressure is usually 0.01 × 10 ³ Pa or more, preferably 0.
. It is 03 × 10 ³ Pa or more, and the upper limit is usually 1.4 × 10 ³ Pa or less, preferably 0.6 × 10 ³ Pa or less, more preferably 0.3 × 10 ³ Pa or less. At this time, the lower limit of the reaction temperature is usually 150 ° C. or higher, preferably 180 ° C. or higher, more preferably 200 ° C. or higher, and the upper limit is usually 260 ° C. or lower, preferably 250 ° C. or lower. The lower limit of the reaction time is usually 1 hour or longer, preferably 2 hours or longer, and the upper limit is usually 15 hours or shorter, preferably 10 hours or shorter.

In the method for producing the aliphatic polyester of the present invention, it is necessary to add a specified amount of the aromatic dicarboxylic acid compound at an arbitrary time before the start of the polycondensation reaction. Here, the start of the polycondensation reaction refers to the time when the pressure reduction of the polycondensation reaction is started.
For example, as a first, it is possible to react with raw material monomers in a batch, and as a second, after an esterification reaction and / or a transesterification reaction between an aliphatic diol and an aliphatic dicarboxylic acid. An aromatic dicarboxylic acid compound may be added at any time point to cause a polycondensation reaction. In order to shorten the polycondensation reaction time, it is preferable to add the aromatic dicarboxylic acid compound at any point after the esterification reaction and / or the transesterification reaction. In that case, it is preferable from the viewpoint of simplification of the process to add it simultaneously with the polymerization catalyst solution or in a state dissolved in the polymerization catalyst solution.

  As the reaction apparatus used in the method for producing the aliphatic polyester of the present invention, a known vertical or horizontal stirred tank reactor can be used. For example, melt polymerization is performed in two stages of esterification and / or transesterification and reduced pressure polycondensation using the same or different reactors, and a vacuum pump and a reactor are used as the reduced pressure polycondensation reactor. A method of using a stirred tank reactor equipped with a evacuation pipe for decompression to be connected can be mentioned. In addition, a condenser is connected between the vacuum exhaust pipe connecting the vacuum pump and the reactor, and the volatile components and unreacted monomers generated during the condensation polymerization reaction are recovered by the condenser. Is preferred.

  In the method for producing an aliphatic polyester of the present invention, the esterification reaction and / or transesterification reaction between the aliphatic dicarboxylic acid and the aliphatic diol is performed, and then the transesterification reaction of the alcohol terminal of the polyester is performed under reduced pressure. A method of increasing the degree of polymerization of polyester while distilling off the generated diol, or increasing the degree of polymerization of polyester while distilling off aliphatic dicarboxylic acid and / or its acid anhydride ring from the terminal of aliphatic carboxylic acid of polyester A method may be used. In the latter case, the removal of the aliphatic carboxylic acid and / or its anhydride ring is usually carried out during the polycondensation reaction under reduced pressure in the latter stage of the melt polymerization step. Although the method of distilling the body by heating is employed, since the aliphatic dicarboxylic acid easily becomes an acid anhydride ring under the polycondensation reaction conditions, it may be distilled by heating in the form of an acid anhydride ring. Many. At this time, the chain or cyclic ether and / or diol derived from the aliphatic diol may also be removed together with the aliphatic dicarboxylic acid and / or the acid anhydride cyclic. Furthermore, the method of distilling off both the dicarboxylic acid component and the diol component of the cyclic monomer is a preferred embodiment because the polymerization rate is improved.

In the method for producing an aliphatic polyester according to the present invention, when using a method for producing an aliphatic polyester having a high degree of polymerization by distilling off an aliphatic dicarboxylic acid and / or an acid anhydride ring, a vacuum pump and The temperature of the reaction vessel side exhaust port of the exhaust pipe for pressure reduction connecting the reactor is equal to the melting point of the aliphatic dicarboxylic acid anhydride ring or the boiling point of the aliphatic dicarboxylic acid anhydride ring at the degree of vacuum during the polycondensation reaction. It is preferable to keep the temperature lower than the lower one because the acid anhydride cyclic product formed can be efficiently removed from the reaction system, and the desired high degree of polymerization aliphatic polyester can be produced in a short time. Furthermore, it is more preferable that the piping temperature from the reaction vessel side exhaust port to the condenser is maintained at a temperature equal to or higher than the melting point of the acid anhydride ring or the boiling point in the degree of vacuum during the polycondensation reaction.

  In the method for producing an aliphatic polyester of the present invention, the molar ratio of the aliphatic diol component and the aliphatic dicarboxylic acid component for obtaining an aliphatic polyester having a desired degree of polymerization is preferably in a range depending on the purpose and the type of raw material. Although the amount of the diol component relative to 1 mol of the acid component is different, the lower limit is usually 0.8 mol or more, preferably 0.9 mol or more, particularly preferably 0.95 mol or more, and the upper limit is usually 1.5 mol. Hereinafter, it is preferably 1.3 mol or less.

<Aliphatic polyester and its use>
The intrinsic viscosity (IV) value of the aliphatic polyester obtained by the production method of the present invention is usually 1.50 dL / g or more, preferably 1.55 dL / g or more.
Intrinsic viscosity (IV) is a measure of the degree of polymerization, and it is generally said that the higher the polyester, the better if it is in a range where there is no inconvenience in molding because the polyester produced has sufficient mechanical properties for practical use. Yes. This factor is also a factor that affects the carboxyl group terminal concentration in the polyester. However, the increase in the viscosity of the polymer may increase the hydrophobicity and improve the hydrolysis resistance. In addition, the measurement conditions of intrinsic viscosity (IV) as used in the field of this invention are mentioned later.

  The number of terminal carboxyl groups (AV) of the aliphatic polyester obtained by the production method of the present invention is usually 18.5 eq / ton or less, preferably 15 eq / ton or less, more preferably 10 eq / ton. Such a polyester is characterized by excellent thermal stability and little deterioration in quality during molding, that is, there are few side reactions such as end group cleavage and main chain cleavage during melt molding.

  On the other hand, in the production of polyester having substantially no carboxyl group terminal, the conventional production method has a very slow polymerization rate and requires an extremely high investment in ultra-high vacuum equipment. On the other hand, when the carboxyl group terminal is present in the produced polyester and / or oligoester, the polymerization rate is high, and a polyester having a high degree of polymerization can be easily obtained. It is preferable that a terminal carboxyl group is present at a concentration of 1 eq / ton or more, preferably 0.5 eq / ton or more, particularly 1 eq / ton or more.

  These terminal concentrations can be controlled by adjusting the dicarboxylic acid / diol charge balance at the time of production. Further, as another method for controlling the terminal concentration, a method of controlling by adding an appropriate amount of at least one trifunctional or higher functional compound unit to the polymerization system is also preferably used.

  In this polymerization system with a low terminal amount ratio, the polymerization reaction time of the polyester becomes long, and the resulting molecular weight decrease and coloration due to thermal decomposition of the polyester are caused, so in order to produce a polyester exhibiting practically sufficient characteristics, It requires extremely expensive capital investment such as the use of ultra-high vacuum equipment. On the other hand, a polymerization system having a high amount ratio tends to produce a polyester having low hydrolysis resistance, or the viscosity of the polyester is too high, which may adversely affect the extraction or moldability after the polymerization reaction. .

The amount of catalyst metal contained in the aliphatic polyester obtained by the production method of the present invention depends on the metal species of the catalyst used, but the smaller the amount used, the lower the hydrolyzability and thermal decomposability of the polyester. In many cases, a polymer having a low carboxyl group terminal concentration in the polymer can be obtained. For example, when the amount of titanium contained in the aliphatic polyester produced when a titanium-containing catalyst is used as the catalyst is 10 ppm or less, the reason has not yet been clarified, but the number of carboxyl group ends is 10 eq / ton or less. Polyester showing excellent hydrolysis resistance can be easily produced.

In the aliphatic polyester obtained by the production method of the present invention, various additives such as a heat stabilizer, an antioxidant, a crystal nucleating agent, a flame retardant, an antistatic agent, a release agent, and the like can be used as long as the characteristics are not impaired. An ultraviolet absorber or the like may be added during polymerization.
In addition to the various additives shown above at the time of molding, glass fiber, carbon fiber, titanium whisker, mica, talc, CaCO ₃ , TiO ₂ , silica and other reinforcing agents and fillers should be added for molding. You can also.

The aliphatic polyester obtained by the production method of the present invention is excellent in heat resistance and color tone, and also excellent in hydrolysis resistance and biodegradability, and can be manufactured at low cost, so it can be used for various film applications and injection molded products. Suitable for
The molding method is not particularly limited, and known methods such as compression molding, layer molding, injection molding, extrusion molding, vacuum molding, pressure molding, and blow molding can be used.
Examples of the molded body produced using the molding method include films, sheets, foams, plates, fibers, containers, and the like. More specifically, a laminate film, monofilament, multifilament, non-woven fabric, flat yarn, staple, crimped fiber, split yarn, composite fiber and the like can be mentioned.
Applications of these molded products are not limited. Specifically, food films, fresh food trays and fast food containers, outdoor leisure products, fishing lines, fishing nets, vegetation nets, water retention sheets, coating materials, agricultural multi-films, Fertilizer coating material, striped tape, split yarn, composite fiber, shopping bag, garbage bag, compost bag, cosmetic container, detergent container, bleach container, rope, binding material, surgical thread, sanitary cover stock material, cold box It can be used for cushion materials and synthetic paper.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to a following example at all unless the summary is exceeded. In addition, the measuring method of the physical property and evaluation item which were employ | adopted in the following examples is as follows.

<Intrinsic viscosity (IV) dL / g>
Using an Ubbelohde viscometer, it was determined as follows. That is, a mixed solvent of phenol / tetrachloroethane (mass ratio 1/1) was used, and at 30 ° C., the polymer solution having a concentration of 0.5 g / dL and the number of falling seconds of the solvent alone were measured, and the following formula (1) I asked more.
IV = ((1 + 4KHη _SP ) 0.5-1) / (2KHC) (1)
(Where η _SP = η / η ₀ −1, η is the sample solution falling seconds, η ₀ is the solvent dropping seconds, C is the sample solution concentration (g / dL), and KH is the Huggins constant. (KH adopted 0.33.)

<Amount of terminal carboxyl group of polyester (AV) eq / ton>
After pulverizing the pelletized polyester, it was dried at 140 ° C. for 15 minutes in a hot air dryer, 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. Then, it was dissolved in 195 ° C. for 3 minutes while blowing dry nitrogen gas. 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 sodium benzyl alcohol solution of sodium hydroxide with stirring while blowing dry nitrogen gas. did. Moreover, the same operation was implemented as a blank, without adding a polyester sample, and the amount of terminal carboxyl groups (acid value) was computed by the following formula | equation (2).

Terminal carboxyl content (eq / ton) = (ab) × 0.1 × f / w (2)
Here, a is the amount of benzyl alcohol solution of 0.1 mol / L sodium hydroxide required for titration (μL), b is benzyl of 0.1 mol / L sodium hydroxide required for titration with a blank. The amount of alcohol solution (μL), w is the amount of polyester sample (g), and f is the titer of 0.1 mol / L sodium hydroxide in benzyl alcohol.
The titer (f) of a benzyl alcohol solution of 0.1 mol / L 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 with 0.4 cm ³ of benzyl alcohol solution of 1 mol / L sodium hydroxide, and then adding 0.2 cm ³ of 0.1 mol / L aqueous hydrochloric acid solution with known titer as a standard solution, and again, The solution was titrated to a discoloration point with a 0.1 mol / L sodium hydroxide solution in benzyl alcohol (the above operation was performed while blowing dry nitrogen gas). And titer (f) was computed by the following formula | equation (3).
Titer (f) = titer of 0.1 mol / L hydrochloric acid aqueous solution x sampling amount of 0.1 N hydrochloric acid aqueous solution (µL) / titration amount of benzyl alcohol solution of 0.1 mol / L sodium hydroxide (µL) ... (3)

[Preparation of catalyst]
62.0 g of magnesium acetate tetrahydrate was put into a 500 ml glass eggplant-shaped flask equipped with a stirrer, and 250 g of absolute ethanol (purity 99% or more) was further added. Further, 35.8 g 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, 75.0 g 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 a 1 L eggplant-shaped flask, and concentrated under reduced pressure by an evaporator in an oil bath at 60 ° C. After about 1 hour, most of the ethanol was distilled off, leaving a translucent viscous liquid. The temperature of the oil bath was further raised to 80 ° C., and further concentration was performed under a reduced pressure of 0.7 kPa. The viscous liquid gradually changed from the surface to a powder form, and was completely pulverized after about 2 hours. Then, it returned to normal pressure using nitrogen, and it cooled to room temperature, and obtained 108 g of pale yellow powder.

A sample obtained by subjecting a metal element contained in the obtained catalyst to 0.1 g of a sample obtained by wet decomposition with hydrogen peroxide in a Kjeldahl flask in the presence of sulfuric acid and then with a constant volume of distilled water was used. As a result of quantitative analysis using ICP-AES ULTRACE JY-138U type manufactured by YVON, the titanium atom (T) content was 10.3 wt%, the Mg atom (M) content was 6.8 wt%, and the phosphorus atom The (P) content was 8.7% by weight, and the molar ratios were T / P = 0.78 and M / P = 1.0. In addition, the weight after the reaction was reduced by 37% of the total weight of the raw material excluding the ethanol solvent, compared with the weight before the reaction. Further, the powdery catalyst was dissolved in 1,4-butanediol so that the titanium atom content was 34000 ppm. The storage stability of the catalyst in 1,4-butanediol was good, and in the catalyst solution stored at 40 ° C. in a nitrogen atmosphere, no precipitate was observed for at least 40 days. Further, as a result of measuring the pH electrode immersed in a liquid catalyst in the atmosphere using an automatic titrator (AUT-301 type) manufactured by Toa DKK, the pH of this catalyst solution was 6.1. In this catalyst solution, absorption peaks derived from alkoxide groups of butanol and 1,4-butanediol are not observed on ¹ H-NMR, and no organic alkoxide group is bonded to the titanium metal of the catalyst. There was found.

[Example 1]
In a reaction vessel equipped with a stirrer, a nitrogen inlet, a heating device, a thermometer and a vacuum outlet, 100 parts by weight of succinic acid, 99.2 parts by weight of 1,4-butanediol, terephthalic acid (
Sometimes abbreviated as TPA. ) 2.81 parts by weight were charged, and the inside of the system was put into a nitrogen atmosphere by nitrogen-vacuum substitution. While stirring the system, the temperature was raised to 230 ° C. over 1 hour, and the reaction was carried out at this temperature for 1 hour. Thereafter, the above catalyst solution was added. The amount added was such that the titanium atoms were 50 ppm with respect to the weight of the resulting aliphatic polyester resin. Next, while stirring the system at 150 rpm, the temperature was raised to 250 ° C. over 30 minutes, and the pressure was reduced to 70 Pa at the same time, and the stirring rotation speed of the stirring device after the pressure reduction was gradually reduced to 150 rpm, 60 rpm, 40 rpm, and 20 rpm. It was. The reaction was terminated when 300 minutes had elapsed from the start of decompression to obtain 100 g of an aliphatic polyester resin. The obtained polyester was extracted as a strand from the bottom of the reaction vessel at 230 ° C., submerged in 10 ° C. water, dried by heating at 60 ° C. for 8 hours under vacuum, and the strand was cut with a cutter to obtain white pellets. It was. In addition, as a result of analyzing the obtained pellet on ¹ H-NMR, aromatic dicarboxylic acid addition amount with respect to the aliphatic dicarboxylic acid component was 2.0 mol%. The obtained pellet had an intrinsic viscosity (IV) of 1.65 dL / g and a terminal carboxyl group amount (AV) of 18.0 eq / ton.

[Example 2]
100 g of polyester pellets were produced under the same conditions as in Example 1 except that terephthalic acid was added simultaneously with the catalyst solution. The reaction was terminated when 300 minutes had elapsed since the start of decompression. The obtained pellet had an IV of 1.72 dL / g and an AV of 14.0 eq / ton.

[Example 3]
100 g of polyester pellets were produced under the same conditions as in Example 1 except that the amount of terephthalic acid was changed to 2.12 parts by weight and added at the same time as the catalyst solution. The reaction was terminated when 295 minutes had elapsed since the start of pressure reduction. The obtained pellet had an IV of 1.64 dL / g and an AV of 12.9 eq / ton.

[Example 4]
100 g of polyester pellets were produced under the same conditions as in Example 1 except that the amount of terephthalic acid was changed to 1.41 parts by weight and added at the same time as the catalyst solution. The reaction was terminated when 300 minutes had elapsed since the start of decompression. The obtained pellet had an IV of 1.70 dL / g and an AV of 16.9 eq / ton.

[Comparative Example 1]
100 g of polyester pellets were produced under the same conditions as in Example 1 except that terephthalic acid was not added. The reaction was terminated in 300 minutes from the start of decompression, and polyester pellets were obtained in the same manner as in Example 1. The obtained pellet had an IV of 1.67 dL / g and an AV of 20.6 eq / ton.

^*1脂肪族ジカルボン酸成分に対しての芳香族ジカルボン酸添加量。
Before ES:エステル化及びエステル交換反応前に添加。
After ES: エステル化及びエステル交換反応後に添加。

^* 1Aromatic dicarboxylic acid added to the aliphatic dicarboxylic acid component.
Before ES: added before esterification and transesterification.
After ES: Added after esterification and transesterification.

  In Examples 1 to 4 in which the aromatic dicarboxylic acid was added before the start of the polycondensation reaction, the amount of terminal carboxyl groups (AV) was reduced as compared with Comparative Example 1 which did not contain an aromatic dicarboxylic acid.

[Example 5]
The addition amount of terephthalic acid was changed to 1.41 parts by weight, 0.114 parts by weight of trimethylolpropane (hereinafter sometimes abbreviated as TMP) was added, and the polymerization reaction time was adjusted to the target viscosity (IV 1
. 65 dL / g) and 100 g of polyester pellets were produced under the same conditions as in Example 1. The target viscosity was reached when 255 minutes had elapsed from the start of pressure reduction. The obtained pellet had an IV of 1.66 dL / g and an AV of 16.5 eq / ton.
The target viscosity was estimated by measuring the torque value (N · m) of the stirring device.

[Example 6]
100 g of polyester pellets were produced under the same conditions as in Example 5 except that terephthalic acid was added simultaneously with the catalyst solution. The reaction was terminated when 245 minutes had elapsed since the start of pressure reduction. The obtained pellet had an IV of 1.65 dL / g and an AV of 10.6 eq / ton.

[Example 7]
100 g of polyester pellets were produced under the same conditions as in Example 5 except that 0.71 part by weight of terephthalic acid and 0.227 part by weight of trimethylolpropane were changed. The target viscosity was reached when 265 minutes had elapsed from the start of pressure reduction. The obtained pellet had an IV of 1.61 dL / g and an AV of 18.2 eq / ton.

[Example 8]
100 g of polyester pellets were produced under the same conditions as in Example 5 except that 0.71 part by weight of terephthalic acid and 0.227 part by weight of trimethylolpropane were added and terephthalic acid was added simultaneously with the catalyst solution. The reaction was terminated when 245 minutes had elapsed since the start of pressure reduction. The obtained pellet had an IV of 1.58 dL / g and an AV of 13.5 eq / ton.

[Example 9]
100 g of polyester pellets were produced under the same conditions as in Example 5 except that 1.83 parts by weight of 2,6-naphthalenedicarboxylic acid (hereinafter sometimes abbreviated as 2,6NDC) was added instead of terephthalic acid. The target viscosity was reached when 300 minutes had elapsed from the start of pressure reduction. The obtained pellet had an IV of 1.62 dL / g and an AV of 13.0 eq / ton.

[Example 10]
100 g of polyester pellets were produced under the same conditions as in Example 5 except that 1.83 parts by weight of 1,4-naphthalenedicarboxylic acid (hereinafter sometimes abbreviated as 1,4NDC) was added instead of terephthalic acid. The target viscosity was reached when 279 minutes had elapsed since the start of pressure reduction. The obtained pellet had an IV of 1.62 dL / g and an AV of 13.3 eq / ton.

^*1脂肪族ジカルボン酸成分に対しての芳香族ジカルボン酸量。
^*2ポリエステル全単量体単位に対するモル％。

^* 1Aromatic dicarboxylic acid content relative to aliphatic dicarboxylic acid component.
^* 2Mole% based on all monomer units of polyester.

  In Examples 5 to 8, in which a specified amount of terephthalic acid was added together with the branching agent before the start of the polycondensation reaction, the polymerization time was greatly reduced as compared with Comparative Example 1. Further, in Examples 6 and 8 in which terephthalic acid was added after the esterification reaction and / or transesterification reaction, the effect of further shortening the polymerization time and decreasing the AV value was observed.

Claims (8)

  In the method for producing an aliphatic polyester using an aliphatic dicarboxylic acid and an aliphatic diol as main raw materials and undergoing esterification and / or transesterification reaction and polycondensation reaction, at any stage up to the start of the polycondensation reaction, A method for producing an aliphatic polyester, comprising adding 0.025 mol% or more and 10 mol% or less of an aromatic dicarboxylic acid to the reaction system with respect to the aromatic dicarboxylic acid.   The method for producing an aliphatic polyester according to claim 1, wherein the aromatic dicarboxylic acid is added after the esterification reaction and / or the transesterification reaction.   The aliphatic polyester according to claim 2, wherein at least one polyfunctional compound selected from the group consisting of a trifunctional or higher polyhydric alcohol, a trifunctional or higher polycarboxylic acid, and a trifunctional or higher oxycarboxylic acid is added. Production method.   The method for producing an aliphatic polyester according to claim 3, wherein the addition amount of the polyfunctional compound is 0.0001 mol% or more and 3 mol% or less with respect to 100 mol% of all monomer units constituting the polyester.   The method for producing an aliphatic polyester according to any one of claims 1 to 4, wherein the aromatic dicarboxylic acid is terephthalic acid or naphthalenedicarboxylic acid.   The method for producing an aliphatic polyester according to any one of claims 1 to 5, wherein the aliphatic dicarboxylic acid is an aliphatic dicarboxylic acid derived from a biomass resource.   The method for producing an aliphatic polyester according to any one of claims 1 to 6, wherein the aliphatic dicarboxylic acid is succinic acid. The method for producing an aliphatic polyester according to any one of claims 1 to 7, wherein the aliphatic diol is 1,4-butanediol.