Method for producing aliphatic aromatic polyester

Abstract

Provided is a method for improving past crystallization deficiencies and producing an aliphatic-aromatic polyester having a high degree of crystallization when producing an aliphatic-aromatic polyester such as PBST by a polycondensation reaction through an esterification and / or transesterification reaction. A method for producing an aliphatic-aromatic polyester, the method involving causing a nucleating agent that satisfies the conditions of formula (1) to be present in the reaction system when producing an aliphatic-aromatic polyester by subjecting an aliphatic diol component, an aliphatic dicarboxylic acid component, and an aromatic dicarboxylic acid component that serve as raw materials to a polycondensation reaction through an esterification and / or transesterification reaction in the presence of a catalyst.　Formula (1): 0°C<Tm1-Tm2≤100°C (where Tm1 is the melting point (°C) of the nucleating agent, and Tm2 is the melting point (°C) of the aliphatic-aromatic polyester)

Description

[Technical Field]

[0001] The present invention relates to a method for producing an aliphatic-aromatic polyester using an aliphatic diol component, an aliphatic dicarboxylic acid component, and an aromatic dicarboxylic acid component as main raw materials. [Background technology]

[0002] Various materials such as paper, plastics, and aluminum foil are used for packaging liquids, powders, and solids for various foods, medicines, and miscellaneous goods, as well as agricultural and construction materials. Among these, plastics are used in a wide range of applications as molded articles such as bags and containers due to their excellent strength, water resistance, formability, transparency, cost, etc.

[0003] Currently, plastics widely used for applications such as bags and containers include polyethylene, polypropylene, polystyrene, polyvinyl chloride, and polyethylene terephthalate. However, molded products made from these plastics do not biodegrade or hydrolyze in the natural environment, or decompose very slowly. Therefore, after use, they may remain in the soil when buried, or may cause damage to the landscape when dumped. Furthermore, even when incinerated, they pose problems such as generating harmful gases and damaging incinerators.

[0004] Biodegradable resins have been attracting attention as environmentally friendly plastics that can solve these problems. Films made from biodegradable resins can be buried in the ground after use and will decompose in the soil, which can help prevent global warming and soil and air pollution. For this reason, biodegradable resin films have recently been widely used for garbage bags, shopping bags, etc.

[0005] However, these biodegradable resin films generally have poor mechanical properties, and therefore, much research has been conducted to improve the mechanical properties while maintaining good biodegradability. As a polyester that combines biodegradability with mechanical properties and moldability, aliphatic-aromatic polyesters such as polybutylene succinate terephthalate (PBST) have been proposed, which are obtained by using an aliphatic diol such as 1,4-butanediol as the diol component and aliphatic dicarboxylic acids such as succinic acid and aromatic dicarboxylic acids such as terephthalic acid as the dicarboxylic acid components.

[0006] Aliphatic aromatic polyesters such as PBST are produced through an esterification step and a polycondensation step, similar to other polyesters. Patent Document 1 discloses an aliphatic aromatic polyester containing at least aliphatic dicarboxylic acid units, aromatic dicarboxylic acid units, aliphatic and / or alicyclic diol units, and structural units having a specific amount of trifunctional or higher functional ester-forming groups. Specifically, Patent Document 1 discloses that polybutylene succinate terephthalate (PBST) is produced through an esterification step and a polycondensation step using succinic acid as the raw material aliphatic dicarboxylic acid, terephthalic acid as the aromatic dicarboxylic acid, 1,4-butanediol as the aliphatic diol, and malic acid as the trifunctional or higher functional oxycarboxylic acid, using a titanium compound such as titanium tetrabutylate or an alkaline earth metal such as magnesium acetate as a catalyst.

[0007] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-31457

[0008] In general, an industrial method for producing an aliphatic aromatic polyester such as PBST is a method in which raw materials, an aliphatic diol component, an aliphatic dicarboxylic acid component, and an aromatic dicarboxylic acid component, are continuously supplied to a reaction system in the presence of a catalyst, and a polycondensation reaction step is carried out to cause an esterification and / or transesterification reaction, and the high-temperature molten polymer continuously obtained from the reaction system is granulated (pelletized) while being cooled.

[0009] It has been found that when an aliphatic aromatic polyester such as PBST is produced by the method described in Patent Document 1, the resulting aliphatic aromatic polyester crystallizes insufficiently, resulting in blocking of the resulting aliphatic aromatic polyester resin pellets. Furthermore, as a result, the cooling process for cooling the high-temperature molten polymer to ensure sufficient crystallization time becomes lengthy, potentially making the process economically inefficient for industrial production of an aliphatic aromatic polyester such as PBST. Furthermore, when an aliphatic aromatic polyester such as PBST, which has a slow crystallization rate, is used by the method described in Patent Document 1 to produce molded products such as films or bags obtained by inflation molding, there are concerns that the films may not be able to be cut due to fusion bonding, or that the opening of the bags obtained by inflation molding may be insufficient. Summary of the Invention

[0010] In order to solve the above-mentioned problems of the conventional art, an object of the present invention is to provide a method for producing an aliphatic aromatic polyester such as PBST by an esterification and / or transesterification reaction followed by a polycondensation reaction, thereby improving the conventional insufficient crystallization and producing an aliphatic aromatic polyester with a high degree of crystallinity.

[0011] The present inventors have found that when an aliphatic aromatic polyester such as PBST is produced by a polycondensation reaction via an esterification and / or transesterification reaction, the presence of a specific nucleating agent in the reaction system can improve the insufficient crystallization and solve the above-mentioned problems, and have completed the present invention. The gist of the present invention lies in the following [1] to [9].

[0012] [1] A method for producing an aliphatic aromatic polyester, characterized in that when an aliphatic aromatic polyester is produced by carrying out an esterification and / or transesterification reaction of an aliphatic diol component, an aliphatic dicarboxylic acid component, and an aromatic dicarboxylic acid component as raw materials in the presence of a catalyst, followed by a polycondensation reaction, a nucleating agent satisfying the conditions of the following formula (1) is present in the reaction system. 0℃ <Tm 1 -Tm 2 ≦100℃ (1) (In the above formula (1), Tm 1 : Melting point of nucleating agent (℃), Tm 2 : Melting point of aliphatic aromatic polyester (℃)

[0013] [2] The method for producing an aliphatic aromatic polyester according to [1], wherein the nucleating agent is present in an amount of 100 to 10,000 ppm by weight based on the aliphatic aromatic polyester produced.

[0014] [3] The method for producing an aliphatic aromatic polyester according to [1] or [2], wherein the molar ratio of the aliphatic dicarboxylic acid component to the aromatic dicarboxylic acid component is 40:60 to 60:40.

[0015] [4] The method for producing an aliphatic aromatic polyester according to any one of [1] to [3], wherein the esterification and / or transesterification reaction is carried out in the presence of a basic inorganic compound.

[0016] [5] The method for producing an aliphatic aromatic polyester according to [4], wherein the basic inorganic compound is present in an amount of 1 to 100 ppm by weight in terms of metal atoms relative to the aliphatic aromatic polyester produced.

[0017] [6] The method for producing an aliphatic aromatic polyester according to any one of [1] to [5], wherein the aliphatic dicarboxylic acid component is a succinic acid component.

[0018] [7] The method for producing an aliphatic aromatic polyester according to any one of [1] to [6], wherein the aromatic dicarboxylic acid component is a terephthalic acid component and / or a furandicarboxylic acid component.

[0019] [8] The method for producing an aliphatic aromatic polyester according to any one of [1] to [7], wherein the aliphatic dicarboxylic acid component is derived from biomass.

[0020] [9] The method for producing an aliphatic aromatic polyester according to any one of [1] to [8], wherein the aliphatic diol component is derived from biomass. [Effects of the Invention]

[0021] According to the present invention, when an aliphatic aromatic polyester such as PBST is produced by an esterification and / or transesterification reaction followed by a polycondensation reaction, the presence of a specific nucleating agent in the reaction system improves insufficient crystallization, making it possible to produce an aliphatic aromatic polyester industrially advantageously without problems such as blocking and film-to-film fusion, which are similar to those of resin pellets. Furthermore, it is expected that this aliphatic aromatic polyester will be used to provide high-quality molded products. DETAILED DESCRIPTION OF THE INVENTION

[0022] The following describes in detail the embodiments of the present invention. The following description of the components is an example (typical example) of the embodiment of the present invention, and the present invention is not limited to these details as long as it does not deviate from the gist of the present invention.

[0023] In this specification, "mass %", "mass ppm", and "parts by mass" have the same meaning as "weight %", "weight ppm", and "parts by weight", respectively.

[0024] The method for producing an aliphatic aromatic polyester of the present invention is characterized in that, when producing an aliphatic aromatic polyester by subjecting an aliphatic diol component, an aliphatic dicarboxylic acid component, and an aromatic dicarboxylic acid component as raw materials to an esterification and / or transesterification reaction and then a polycondensation reaction in the presence of a catalyst, a nucleating agent satisfying the conditions of the following formula (1) is present in the reaction system: 0℃ <Tm 1 -Tm 2 ≦100℃ (1) (In the above formula (1), Tm 1 : Melting point of nucleating agent (℃), Tm 2 : Melting point of aliphatic aromatic polyester (℃)

[0025] Here, the term "aliphatic dicarboxylic acid component" is a general term for aliphatic dicarboxylic acids that serve as polyester raw materials, such as aliphatic dicarboxylic acids and aliphatic dicarboxylic acid derivatives such as aliphatic dicarboxylic acid alkyl esters. The term "aromatic dicarboxylic acid component" is a general term for aromatic dicarboxylic acids that serve as polyester raw materials, such as aromatic dicarboxylic acids and aromatic dicarboxylic acid derivatives such as aromatic dicarboxylic acid alkyl esters.

[0026] In the present invention, the term "aromatic dicarboxylic acid" refers to a broader definition of "aromatic dicarboxylic acid" that includes "heteroaromatic dicarboxylic acid."

[0027] Hereinafter, the aliphatic aromatic polyester produced by the method for producing an aliphatic aromatic polyester of the present invention may be referred to as the "aliphatic aromatic polyester of the present invention." The aliphatic aromatic polyester may also be simply referred to as the "polyester."

[0028] The production method of the present invention includes an esterification and / or transesterification reaction step in which at least an aliphatic diol component, an aliphatic dicarboxylic acid component, and an aromatic dicarboxylic acid component are reacted as main raw materials in the presence of a catalyst, followed by a polycondensation reaction step. "Using an aliphatic diol component, an aliphatic dicarboxylic acid component, and an aromatic dicarboxylic acid component as main raw materials" means that the diol component used as a raw material is mainly composed of an aliphatic diol component, and that the dicarboxylic acid component used as a raw material is mainly composed of an aliphatic dicarboxylic acid component and an aromatic dicarboxylic acid component.

[0029] Here, "containing an aliphatic diol component as a main component" means "the total molar ratio of the aliphatic diol component is the highest among the raw material diol components." In particular, from the viewpoint of the physical properties and biodegradability of the resulting polyester, the total amount of the aliphatic diol component relative to the total amount of the raw material diol components is preferably 50 mol % or more, more preferably 60 mol % or more, even more preferably 70 mol % or more, and particularly preferably 90 to 100 mol %.

[0030] Furthermore, "mainly composed of aliphatic dicarboxylic acids and aromatic dicarboxylic acids" means "the total molar ratio of the aliphatic dicarboxylic acid components and aromatic dicarboxylic acid components is the highest among the raw carboxylic acid components." In particular, from the viewpoint of the physical properties and biodegradability of the resulting polyester, the total of the aliphatic dicarboxylic acid components and aromatic dicarboxylic acid components is preferably 50 mol % or more, more preferably 60 mol % or more, even more preferably 70 mol % or more, and particularly preferably 90 to 100 mol % of the total raw carboxylic acid components.

[0031] In the present invention, each reaction step in producing a polyester can be carried out by a batch method or a continuous method. From the viewpoint of stabilizing quality and energy efficiency, a so-called continuous method in which raw materials are continuously supplied and polyester is continuously obtained is preferred.

[0032] <Nucleating agent> The nucleating agent used in the method for producing an aliphatic aromatic polyester of the present invention has a melting point (Tm 2 (℃)) and the melting point of the nucleating agent (Tm 1 (℃)) 1 -Tm 2 ) is in the range of 0 to 100°C. By using a nucleating agent that satisfies such melting point conditions, it is possible to shorten the peak time of exothermic crystallization during cooling of the molten aliphatic aromatic polyester obtained by the polycondensation reaction (peak time of crystallization during cooling, which will be described later), thereby accelerating the crystallization of the aliphatic aromatic polyester during cooling. This shortens the cooling step, allowing for economically efficient continuous production of pellets of the aliphatic aromatic polyester.

[0033] Nucleating agent melting point Tm 1 There is no particular limitation on the method for measuring this, and it can be measured, for example, by a visual method (JIS K6220) or a thermal analysis method using DCS or DTA. For commercially available products, the catalog value can be used.

[0034] Melting point (Tm) of aliphatic aromatic polyester 2The method for measuring the melting point of the aliphatic aromatic polyester of the present invention is not particularly limited, and it can be measured, for example, by the method described in the Examples section below. The preferred melting point of the aliphatic aromatic polyester of the present invention will be described later.

[0035] In the present invention, the melting point (Tm 2 (℃)) and the melting point of the nucleating agent (Tm 1 (℃)) 1 -Tm 2 ) is 100°C or less, preferably 50°C or less, more preferably 40°C or less, even more preferably 20°C or less, and most preferably 15°C or less. 1 -Tm 2 The smaller the value of Tm, the shorter the crystallization exothermic peak time can be. However, since the nucleating agent acts as a crystal nucleus, it needs to solidify faster than the aliphatic aromatic polyester. 1 -Tm 2 is 0°C or higher, preferably 1°C or higher, and more preferably 3°C or higher.

[0036] The type of nucleating agent is not particularly limited as long as it satisfies the above conditions. Examples of nucleating agents that can be used include hydrocarbon-based nucleating agents such as polyethylene wax and polypropylene wax, aliphatic amide-based nucleating agents, and phosphate metal salt-based nucleating agents. From the viewpoint of their influence on the color tone and polymerizability of the resulting aliphatic aromatic polyester, hydrocarbon-based nucleating agents are preferred, more preferably polyethylene wax and polypropylene wax, and even more preferably polyethylene wax. Polyethylene waxes and polypropylene waxes with various melting points depending on the molecular weight, the presence or absence of branching, the composition of copolymer components, etc. are commercially available, and it is possible to select and use from among the commercially available products those that satisfy the above-mentioned melting point conditions.

[0037] The nucleating agent may be used alone or in combination of two or more kinds, as long as it satisfies the above-mentioned melting point condition.

[0038] In the method for producing an aliphatic aromatic polyester of the present invention, the method for introducing a nucleating agent into the reaction system is not particularly limited. The nucleating agent may be present in the esterification and / or transesterification reaction system or in the polycondensation reaction system. Examples include a method of supplying the nucleating agent to the esterification and / or transesterification reaction reactor together with the raw materials, such as the aliphatic diol component, the aliphatic dicarboxylic acid component, and the aromatic dicarboxylic acid component, described below; a method of adding the nucleating agent directly to the esterification and / or transesterification reaction reactor separately from these raw materials; a method of adding the nucleating agent to the polycondensation reaction reactor; or a method of adding the nucleating agent in an extruder attached to the polycondensation reaction reactor that transports the high-temperature molten polyester to the next step. Two or more of these methods may also be used in combination.

[0039] In the method for producing an aliphatic aromatic polyester of the present invention, the amount of nucleating agent present in the reaction system is preferably 100 to 10,000 ppm by weight relative to the aliphatic aromatic polyester produced. This amount of nucleating agent is more preferably 200 to 5,000 ppm by weight, and even more preferably 500 to 3,000 ppm by weight. If the amount of nucleating agent is below the above upper limit, the amount of nucleating agent distilled from the reaction system can be reduced, preventing it from being unable to be recovered in the subsequent distillation or distillation system, thereby increasing the load on the entire process. If the amount of nucleating agent is above the above lower limit, crystallization of the resulting aliphatic aromatic polyester can be sufficiently promoted.

[0040] <Diol ingredient> As the diol component used in the present invention, as described above, at least an aliphatic diol component is used, and as long as the total molar ratio of the aliphatic diol component is the largest among the raw material diol components, any diol component that is normally used as a raw material for polyesters can be used without any particular limitation.

[0041] Examples of the aliphatic diol component include alkylene diols such as ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, and neopentyl glycol; oxyalkylene diols such as diethylene glycol, polyethylene glycol, polypropylene glycol, and polytetramethylene ether glycol; and cycloalkylene diols such as 1,2-cyclohexanediol, 1,4-cyclohexanediol, 1,2-cyclohexanedimethanol, and 1,4-cyclohexanedimethanol. Among these, from the viewpoint of the physical properties of the polyester obtained, alkylene diols having 6 or less carbon atoms, such as ethylene glycol, 1,3-propanediol, and 1,4-butanediol, and cycloalkylene diols having 6 or less carbon atoms, such as 1,4-cyclohexanedimethanol, are preferred, and 1,4-butanediol is particularly preferred. Two or more of these may be used in combination.

[0042] When 1,4-butanediol is used as the aliphatic diol component, the amount of 1,4-butanediol used is preferably 50 mol % or more, more preferably 70 mol % or more, and particularly preferably 90 to 100 mol %, based on the total aliphatic diol components, from the viewpoints of the melting point (heat resistance), biodegradability, and mechanical properties of the resulting polyester.

[0043] Of the aliphatic diol components, ethylene glycol, 1,3-propanediol, and 1,4-butanediol derived from biomass (plant raw materials) are preferably used.

[0044] <Dicarboxylic acid component> As the carboxylic acid component used in the present invention, as described above, at least an aliphatic dicarboxylic acid component and an aromatic dicarboxylic acid component are used, and as long as the total molar ratio of these components is the largest among the raw material dicarboxylic acid components, any carboxylic acid component that is normally used as a raw material for polyesters can be used without any particular restrictions.

[0045] Among the dicarboxylic acid components, examples of aliphatic dicarboxylic acid components include aliphatic dicarboxylic acids such as oxalic acid, malonic acid, succinic acid, succinic anhydride, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecadicarboxylic acid, dodecadicarboxylic acid, and dimer acid, and hydrogenated aromatic dicarboxylic acids such as hexahydrophthalic acid, hexahydroisophthalic acid, and hexahydroterephthalic acid. Among these, aliphatic dicarboxylic acids such as succinic acid, succinic anhydride, adipic acid, and sebacic acid, or derivatives thereof such as alkyl esters, are preferred in terms of the physical properties of the resulting polyester. Succinic acid is particularly preferred due to its significant effect in improving crystallization according to the present invention. Two or more of these may be used in combination.

[0046] Of these aliphatic dicarboxylic acid components, succinic acid, succinic anhydride, adipic acid, and the like are preferably derived from biomass (plant raw materials).

[0047] When succinic acid is used as the aliphatic dicarboxylic acid component, the amount of succinic acid used is preferably 50 mol % or more, more preferably 70 mol % or more, and particularly preferably 90 to 100 mol %, of the total aliphatic dicarboxylic acid components, from the viewpoints of the melting point (heat resistance), biodegradability, and mechanical properties of the resulting polyester.

[0048] Examples of aromatic dicarboxylic acid components include terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid, diphenyldicarboxylic acid, furandicarboxylic acid, and derivatives thereof such as alkyl esters. From the viewpoint of the physical properties of the resulting polyester, terephthalic acid, isophthalic acid, and furandicarboxylic acid are preferred, with terephthalic acid and furandicarboxylic acid being particularly preferred. These may be used alone or as a mixture of two or more.

[0049] When terephthalic acid is used as the aromatic dicarboxylic acid component, the amount of terephthalic acid used is preferably 50 mol % or more, more preferably 70 mol % or more, and particularly preferably 90 to 100 mol %, based on the total aromatic dicarboxylic acid components, from the viewpoint of the melting point (heat resistance) and mechanical properties of the resulting polyester.

[0050] The molar ratio of the aliphatic dicarboxylic acid component to the aromatic dicarboxylic acid component used in the present invention is preferably aliphatic dicarboxylic acid component:aromatic dicarboxylic acid component=40:60 to 60:40, and particularly preferably aliphatic dicarboxylic acid component:aromatic dicarboxylic acid component=50:50 to 60:40 from the viewpoints of the heat resistance, biodegradability, mechanical properties, and moldability of the resulting polyester.

[0051] In the method for producing an aliphatic aromatic polyester of the present invention, the aliphatic aromatic polyester to be produced is not particularly limited as long as it is obtained by combining the above-mentioned aliphatic diol component, aliphatic dicarboxylic acid component, and aromatic dicarboxylic acid component, but is preferably polybutylene succinate terephthalate (PBST) or polybutylene succinate furanoate (PBSF).

[0052] <Other copolymer components> The aliphatic aromatic polyester of the present invention may be copolymerized with other components in addition to the aliphatic diol component, the aliphatic dicarboxylic acid component, and the aromatic dicarboxylic acid component. Examples of copolymerization components that can be used in this case include hydroxycarboxylic acids such as lactic acid, glycolic acid, hydroxybutyric acid, hydroxycaproic acid, 2-hydroxy-3,3-dimethylbutyric acid, 2-hydroxy-3-methylbutyric acid, 2-hydroxyisocaproic acid, malic acid, maleic acid, citric acid, and fumaric acid, as well as esters, lactones, and hydroxycarboxylic acid polymers of these hydroxycarboxylic acids, trifunctional or higher polyhydric alcohols such as glycerin, trimethylolpropane, and pentaerythritol, and trifunctional or higher polycarboxylic acids or anhydrides thereof such as propanetricarboxylic acid, pyromellitic acid, trimellitic acid, benzophenonetetracarboxylic acid, and anhydrides thereof.

[0053] Among these, polyesters with high viscosity can be easily obtained by adding small amounts of trifunctional or higher hydroxycarboxylic acids, trifunctional or higher alcohols, trifunctional or higher carboxylic acids, etc. Among these, hydroxycarboxylic acids such as malic acid, citric acid, and fumaric acid, and polyhydric alcohols such as glycerin, trimethylolpropane, and pentaerythritol are preferred, with trimethylolpropane being particularly preferred.

[0054] When a tri- or higher functional compound is used, the amount used is preferably 0.001 to 5 mol %, more preferably 0.05 to 0.5 mol %, based on the total dicarboxylic acid components. If the amount of the tri- or higher functional compound used is equal to or less than the above upper limit, it is easy to prevent gel (unmelted material) from forming in the resulting polyester. If the amount of the tri- or higher functional compound used is equal to or more than the above lower limit, it is easy to obtain the advantages of using a polyfunctional compound (usually, it is possible to increase the viscosity of the resulting polyester).

[0055] <Basic inorganic compounds> In the method for producing an aliphatic aromatic polyester of the present invention, it is preferable to have a basic inorganic compound present in the esterification and / or transesterification reaction step. By having a basic inorganic compound present in the esterification and / or transesterification reaction step, the amount of tetrahydrofuran in the resulting aliphatic aromatic polyester can be reduced, and the terminal acid value can also be reduced.

[0056] Examples of the basic inorganic compound to be present include alkali metal hydroxides such as sodium hydroxide, potassium hydroxide, and lithium hydroxide, and sodium hydroxide is preferred. These may be used alone or as a mixture of two or more kinds.

[0057] The amount of the basic inorganic compound used is preferably 1 to 100 ppm by weight, more preferably 1 to 50 ppm by weight, based on the amount of metal atoms of the resulting aliphatic aromatic polyester. When the amount of the basic inorganic compound is equal to or greater than the lower limit, the above-mentioned effects of the basic inorganic compound can be sufficiently obtained. When the amount of the basic inorganic compound is equal to or less than the upper limit, problems such as a decrease in polymerization activity and the generation of foreign matter due to reaction with the dicarboxylic acid component can be suppressed.

[0058] The basic inorganic compound may be present in the esterification and / or transesterification reaction step, and may be added to the esterification and / or transesterification reaction step or in a step prior to the esterification and / or transesterification reaction step. For example, the basic inorganic compound may be supplied to the esterification and / or transesterification reaction tank together with the raw material aliphatic diol component, aliphatic dicarboxylic acid component, aromatic dicarboxylic acid component, etc., or may be supplied directly to the reaction tank separately from these raw materials.

[0059] <Method of producing aliphatic aromatic polyester> The method for producing the aliphatic aromatic polyester of the present invention will be explained below by taking the continuous production method as an example. Hereinafter, an example will be given of a method for producing an aliphatic aromatic polyester by an esterification reaction step using an aliphatic diol, an aliphatic dicarboxylic acid, and an aromatic dicarboxylic acid, followed by a polycondensation reaction step. However, the esterification reaction step may be a transesterification reaction step, or may be a step in which both the esterification reaction and the transesterification reaction are carried out.

[0060] In the continuous production method, for example, an aliphatic dicarboxylic acid, an aromatic dicarboxylic acid, and an aliphatic diol are reacted in a plurality of continuous reaction vessels to undergo an esterification reaction step and a melt polycondensation reaction step, thereby continuously obtaining polyester pellets. The method is not limited to the continuous method, and any conventionally known method for producing an aliphatic aromatic polyester can be employed as long as it does not impair the effects of the present invention.

[0061] The esterification reaction step in which at least the dicarboxylic acid component and the diol component are reacted and the subsequent polycondensation reaction step can be carried out in a single reaction tank or in multiple reaction tanks in series, and is preferably carried out in multiple reaction tanks in order to reduce variations in the physical properties of the resulting polyester.

[0062] In the following, the supply of a nucleating agent and the supply of a basic inorganic compound are omitted, but in the present invention, as described above, a specific nucleating agent is supplied to the esterification and / or transesterification reaction step and the polycondensation reaction step, and preferably a basic inorganic compound is supplied to the esterification and / or transesterification reaction step.

[0063] <Esterification reaction step> The reaction temperature in the esterification reaction step is not particularly limited as long as it is a temperature at which the esterification reaction can be carried out. However, in order to increase the reaction rate, it is preferably 200°C or higher, more preferably 210°C or higher. On the other hand, to prevent discoloration of the polyester, the reaction temperature is preferably 270°C or lower, more preferably 260°C or lower, and particularly preferably 250°C or lower. If the reaction temperature is too low, the esterification reaction rate will be slow, requiring a long reaction time, and undesirable reactions such as dehydration decomposition of the aliphatic diol will occur frequently. If the reaction temperature is too high, the decomposition amounts of the aliphatic diol, aliphatic dicarboxylic acid, and aromatic dicarboxylic acid will increase, and the amount of scattered material in the reaction vessel will increase, which will likely cause the generation of foreign matter and the reaction product will likely become turbid (haze). The esterification reaction temperature is preferably a constant temperature. A constant temperature stabilizes the esterification rate. The constant temperature is within ±5°C of the set temperature, and preferably ±2°C.

[0064] The reaction atmosphere is preferably an inert gas atmosphere such as nitrogen or argon.

[0065] The reaction pressure is preferably 50 kPa to 200 kPa, more preferably 60 kPa or more, even more preferably 70 kPa or more, more preferably 130 kPa or less, and even more preferably 110 kPa or less. If the reaction pressure is below the lower limit, the amount of flying material in the reaction vessel increases, the haze of the reaction product increases, and this is likely to cause an increase in foreign matter. In addition, more aliphatic diol is distilled out of the reaction system, which is likely to result in a decrease in the polycondensation reaction rate. If the reaction pressure exceeds the upper limit, the dehydration decomposition of the aliphatic diol increases, which is likely to result in a decrease in the polycondensation reaction rate.

[0066] The reaction time is preferably 1 hour or longer, and the upper limit is preferably 10 hours or shorter, more preferably 4 hours or shorter.

[0067] The molar ratio of the aliphatic diol to the total aliphatic dicarboxylic acid and aromatic dicarboxylic acid undergoing the esterification reaction represents the molar ratio of the aliphatic diol and esterified aliphatic diol to the aliphatic dicarboxylic acid and aromatic dicarboxylic acid and esterified aliphatic dicarboxylic acid present in the gas phase and reaction liquid phase of the esterification reactor. This does not include the aliphatic dicarboxylic acid, aromatic dicarboxylic acid, aliphatic diol, and their decomposition products that are decomposed in the reaction system and do not contribute to the esterification reaction. Examples of compounds that are decomposed and do not contribute to the esterification reaction include the decomposition of the aliphatic diol 1,4-butanediol to tetrahydrofuran, and tetrahydrofuran is not included in this molar ratio. In the present invention, the lower limit of the molar ratio is usually 1.10 or more, preferably 1.12 or more, more preferably 1.15 or more, and particularly preferably 1.20 or more. The upper limit of the molar ratio is usually 3.00 or less, preferably 2.50 or less, more preferably 2.30 or less, and particularly preferably 2.00 or less. If the reaction molar ratio is less than the lower limit, the esterification reaction is likely to be insufficient, making it difficult to proceed with the polycondensation reaction, which is a post-step reaction, and to obtain a polyester with a high degree of polymerization. If the reaction molar ratio exceeds the upper limit, the amounts of decomposition of the aliphatic diol, aliphatic dicarboxylic acid, and aromatic dicarboxylic acid tend to increase. In order to maintain this reaction molar ratio within the preferred range, it is a preferred method to appropriately supply aliphatic diol to the esterification reaction system.

[0068] <Polycondensation reaction step> In the method for producing an aliphatic aromatic polyester of the present invention, the esterification reaction step is followed by a polycondensation reaction in a polycondensation reaction step. The polycondensation reaction can be carried out under reduced pressure using a plurality of continuous reaction vessels.

[0069] The reaction pressure in the final polycondensation reaction tank in the polycondensation reaction step is usually 0.01 kPa or higher, preferably 0.03 kPa or higher, with the upper limit being usually 1.4 kPa or lower, preferably 0.4 kPa or lower. If the pressure during the polycondensation reaction is too high, the polycondensation time becomes longer, which can lead to thermal decomposition of the polyester, resulting in a decrease in molecular weight and coloration, making it difficult to produce a polyester with sufficient properties for practical use. A production method using ultra-high vacuum polycondensation equipment that sets the reaction pressure at less than 0.01 kPa is a preferred embodiment from the perspective of improving the polycondensation reaction rate, but requires extremely expensive capital investment, making it economically disadvantageous.

[0070] The lower limit of the reaction temperature is usually 215°C, preferably 220°C, and the upper limit is usually 270°C, preferably 260°C. If the reaction temperature is below the lower limit, the polycondensation reaction rate is slow, and not only does it take a long time to produce a polyester with a high degree of polymerization, but it also requires a high-power stirrer, which is economically disadvantageous. If the reaction temperature exceeds the upper limit, thermal decomposition of the polyester during production tends to occur, making it difficult to produce a polyester with a high degree of polymerization.

[0071] The lower limit of the reaction time is usually 1 hour, and the upper limit is usually 15 hours, preferably 10 hours, and more preferably 8 hours. If the reaction time is too short, the reaction is insufficient, making it difficult to obtain a polyester with a high degree of polymerization, and the mechanical properties of the molded product tend to be poor. If the reaction time is too long, the molecular weight of the polyester decreases significantly due to thermal decomposition, and not only do the mechanical properties of the molded product tend to be poor, but the amount of carboxyl terminal groups, which has a negative effect on the durability of the polyester, may increase due to thermal decomposition.

[0072] By controlling the polycondensation reaction temperature, time and reaction pressure, a polyester having a desired intrinsic viscosity can be obtained.

[0073] <Reaction catalyst> The esterification reaction and polycondensation reaction can be accelerated by using a reaction catalyst. When a catalyst is used, adding the catalyst to the gas phase of the reaction vessel can increase the haze of the resulting polyester and can also cause the catalyst to become a foreign substance. Therefore, it is preferable to add the catalyst to the reaction liquid.

[0074] In the polycondensation reaction, the reaction does not proceed easily without a catalyst, so it is preferable to use a catalyst. The polycondensation reaction catalyst may be added at any stage between the esterification reaction step and the polycondensation reaction step. The polycondensation reaction catalyst may be added in multiple batches between the esterification reaction step and the polycondensation reaction step.

[0075] The polycondensation reaction catalyst generally uses a compound containing at least one metal element selected from Groups 1 to 14 of the periodic table. Specific examples of metal elements include scandium, yttrium, samarium, titanium, zirconium, vanadium, chromium, molybdenum, tungsten, tin, antimony, cerium, germanium, zinc, cobalt, manganese, iron, aluminum, magnesium, calcium, strontium, sodium, and potassium. Among these, scandium, yttrium, titanium, zirconium, vanadium, molybdenum, tungsten, zinc, iron, and germanium are preferred, with titanium, zirconium, tungsten, iron, and germanium being particularly preferred. Furthermore, to reduce the polyester end concentration, which affects the thermal stability of polyester, among the above metals, metal elements selected from Groups 3 to 6 of the periodic table that exhibit Lewis acidity are preferred. Specifically, scandium, titanium, zirconium, vanadium, molybdenum, and tungsten are included, and titanium and zirconium are particularly preferred because of their availability, with titanium being even more preferred in terms of reaction activity. Here, the periodic table refers to the long-form periodic table (Nomenclature of Inorganic Chemistry IUPAC Recommendations 2005).

[0076] In the present invention, a titanium compound is preferably used as a catalyst in the esterification reaction step.

[0077] The titanium compound is preferably a tetraalkyl titanate or a hydrolyzate thereof, specifically, tetra-n-propyl titanate, tetraisopropyl titanate, tetra-n-butyl titanate, tetra-t-butyl titanate, tetraphenyl titanate, tetracyclohexyl titanate, tetrabenzyl titanate, mixed titanates thereof, and hydrolyzates thereof.

[0078] Also usable are titanium(oxy)acetylacetonate, titanium tetraacetylacetonate, titanium(diisoproxide)acetylacetonate, titanium bis(ammonium lactate)dihydroxide, titanium bis(ethylacetoacetate)diisopropoxide, titanium(triethanolaminate)isopropoxide, polyhydroxytitanium stearate, titanium lactate, titanium triethanolaminate, and butyl titanate dimer.

[0079] Among these, tetra-n-propyl titanate, tetraisopropyl titanate, tetra-n-butyl titanate, titanium(oxy)acetylacetonate, titanium tetraacetylacetonate, titanium bis(ammonium lactate) dihydroxide, polyhydroxytitanium stearate, titanium lactate, and butyl titanate dimer are preferred, and tetra-n-butyl titanate, titanium(oxy)acetylacetonate, titanium tetraacetylacetonate, polyhydroxytitanium stearate, titanium lactate, and butyl titanate dimer are more preferred, with tetra-n-butyl titanate, polyhydroxytitanium stearate, titanium(oxy)acetylacetonate, and titanium tetraacetylacetonate being particularly preferred.

[0080] These titanium compounds are supplied to the esterification reaction step as a catalyst solution prepared using a catalyst dissolving solvent such as alcohols such as methanol, ethanol, isopropanol, butanol, diols such as ethylene glycol, butanediol, pentanediol, ethers such as diethyl ether, tetrahydrofuran, nitriles such as acetonitrile, hydrocarbon compounds such as heptane, toluene, water, and mixtures thereof, so that the titanium compound concentration is usually 0.05 to 5% by weight.

[0081] <Phosphorus compounds> In the production of aliphatic aromatic polyesters, particularly when adipic acid is used as an aliphatic dicarboxylic acid component, the resulting aliphatic aromatic polyester is colored red to pink. Molded articles obtained by molding the colored aliphatic aromatic polyesters may have a reddish tinge and may be of poor quality. Furthermore, the high decomposition rate of 1,4-butanediol used as a raw material diol component may lead to problems such as the easy by-production of tetrahydrofuran, resulting in inefficiency (such as a worsening of the 1,4-butanediol consumption rate).

[0082] The gases distilled from the esterification and / or transesterification reactor and the polycondensation reactor are mainly composed of by-product aliphatic diol components and water, and, for example, when 1,4-butanediol is used as the aliphatic diol component, also contain tetrahydrofuran, which is a decomposition product of 1,4-butanediol. These gas components are usually separated and collected using a rectification column or a wet condenser, and some of the high-boiling components, which are mainly composed of the raw diol components, may be reused as raw materials. However, because tetrahydrofuran does not contribute to the esterification reaction, a large amount of tetrahydrofuran by-product undesirably leads to a deterioration in the unit consumption of 1,4-butanediol.

[0083] As a method for solving this problem, suppressing the by-production of tetrahydrofuran, and producing a high-quality aliphatic aromatic polyester with good color tone, an effective method is to control the terminal acid value of an ester oligomer obtained through an esterification and / or transesterification reaction step in which an aliphatic diol component, an aliphatic dicarboxylic acid component, and an aromatic dicarboxylic acid component are reacted to each other, to 30 to 1000 eq. / ton, and then bring this ester oligomer with the controlled terminal acid value into contact with a phosphorus compound and then carry out a polycondensation reaction.

[0084] In this case, examples of the phosphorus compound to be contacted with the ester oligomer having a terminal acid value of 30 to 1000 eq. / ton obtained in the esterification and / or transesterification reaction step include orthophosphoric acid, polyphosphoric acid, pentavalent phosphorus compounds such as trimethyl phosphate, triethyl phosphate, tri-n-butyl phosphate, trioctyl phosphate, triphenyl phosphate, tricresyl phosphate, tris(triethylene glycol) phosphate, ethyl diethylphosphonoacetate, methyl acid phosphate, ethyl acid phosphate, isopropyl acid phosphate, butyl acid phosphate, monobutyl phosphate, dibutyl phosphate, dioctyl phosphate, and triethylene glycol acid phosphate, and trivalent phosphorus compounds such as phosphorous acid, hypophosphorous acid, diethyl phosphite, trisdodecyl phosphite, trisnonyldecyl phosphite, and triphenyl phosphite. Among these, acidic phosphoric acid ester compounds are preferred. As the acidic phosphate ester compound, a compound having an ester structure of phosphoric acid having at least one hydroxyl group, represented by the following general formula (I) and / or (II), is preferably used.

[0085] [ka]

[0086] In the formula, R, R', and R" each represent an alkyl group having 1 to 6 carbon atoms, a cyclohexyl group, an aryl group, or a 2-hydroxyethyl group, and in formula (I), R and R' may be the same or different.

[0087] Specific examples of such acidic phosphate ester compounds include methyl acid phosphate, ethyl acid phosphate, isopropyl acid phosphate, butyl acid phosphate, and octyl acid phosphate, with ethyl acid phosphate and butyl acid phosphate being preferred. These acidic phosphate ester compounds may be used alone or in combination of two or more.

[0088] Acidic phosphate ester compounds include monoesters represented by the above general formula (II) and diesters represented by the above general formula (I). It is preferable to use monoesters or mixtures of monoesters and diesters because they provide catalysts with high catalytic activity. The weight ratio of monoesters to diesters (monoesters:diesters) is preferably 80:20 or more, more preferably 70:30 or more, and particularly preferably 60:40 or more, and is preferably 20:80 or more, more preferably 30:70 or more, and particularly preferably 40:60 or more.

[0089] In such a method using a phosphorus compound, it is preferable to contact an alkaline earth metal compound with the ester oligomer together with the phosphorus compound. In this case, examples of the alkaline earth metal compound include various compounds of beryllium, magnesium, calcium, strontium, and barium. From the viewpoints of ease of handling and availability, and catalytic effect, magnesium and calcium compounds are preferred, and among them, magnesium compounds with excellent catalytic effect are preferred. Specific examples of magnesium compounds include magnesium acetate, magnesium hydroxide, magnesium carbonate, magnesium oxide, magnesium alkoxide, magnesium hydrogen phosphate, etc. Among these, magnesium acetate is preferred.

[0090] These phosphorus compounds and alkaline earth metal compounds are preferably added to the ester oligomer supplied to the polycondensation reaction step as a catalyst solution prepared using a solvent exemplified as a catalyst dissolving solvent used in preparing the above-mentioned titanium compound catalyst solution so that the phosphorus compound has a concentration of 0.01 to 7.6 wt % and the alkaline earth metal compound has a concentration of 0.02 to 9.7 wt %.

[0091] There are no particular restrictions on the amounts or ratios of the titanium compound used in the esterification reaction step and the phosphorus compound and alkaline earth metal compound used in the polycondensation reaction step. For example, the titanium compound is preferably used in an amount of 5 to 100 ppm by weight, calculated as Ti, relative to the resulting polyester. The phosphorus compound is preferably used in an amount such that the molar ratio of the titanium compound added in terms of P to the molar amount added in terms of Ti (P / Ti molar ratio) is 0.5 to 2.5. The alkaline earth metal compound is preferably used in an amount such that the molar ratio of the titanium compound added in terms of alkaline earth metal to the molar amount added in terms of Ti (alkaline earth metal / Ti molar ratio) is 0.5 to 3.0. Using too much of either catalyst compound is not only economically disadvantageous, but also, for reasons that are not yet clear, may increase the terminal acid value of the final polyester. This may result in a decrease in the thermal stability and hydrolysis resistance of the polyester due to an increase in the terminal acid value and residual catalyst concentration. Conversely, using too little catalyst compound reduces the reaction activity, which may induce thermal decomposition of the polyester during polyester production, making it difficult to obtain a polyester with practically useful physical properties.

[0092] <Reaction tank> The esterification reaction tank used in the present invention may be any known type, such as a vertical agitated complete mixing tank, a vertical thermal convection mixing tank, or a tower-type continuous reaction tank. The reaction tank may be a single tank or a plurality of tanks of the same or different types connected in series. Among these, a reaction tank equipped with an agitator is preferred, and the agitator may be a conventional type consisting of a power unit, a bearing, a shaft, and an agitator blade, or a high-speed rotating type such as a turbine stator type high-speed rotating agitator, a disk mill type agitator, or a rotor mill type agitator.

[0093] There are no limitations on the type of stirring, and in addition to the usual stirring method of directly stirring the reaction liquid in the reaction tank from the top, bottom, side, etc. of the reaction tank, a method can also be used in which a part of the reaction liquid is taken out of the reaction tank via piping, etc., and stirred with a line mixer, etc., to circulate the reaction liquid. Known types of stirring blades can also be selected, and specific examples include propeller blades, screw blades, turbine blades, fan turbine blades, disk turbine blades, Pfaudler blades, Fullzone blades, Max Blend blades, etc.

[0094] The type of polycondensation reaction tank used in the present invention is not particularly limited, and examples thereof include a vertical agitation polymerization tank, a horizontal agitation polymerization tank, and a thin-film evaporation polymerization tank. The polycondensation reaction tank can be a single tank, or a plurality of tanks of the same or different types connected in series. In the later stages of polycondensation when the viscosity of the reaction liquid increases, it is preferable to select a horizontal agitation polymerization tank that has a thin-film evaporation function that is excellent in interface renewal, plug flow, and self-cleaning properties.

[0095] <Pelletization> The polyester in a molten state at a high temperature obtained through the above polycondensation reaction can be pelletized while being cooled to give polyester pellets.

[0096] Widely used pelletizing methods include the strand cutting method, in which polyester in a molten state at high temperature is extruded from the nozzle holes of a die head using a gear pump or extruder, and the strands are cut with a cutter while being cooled with water or the like, or after being cooled and solidified; and the underwater hot cutting method, in which the polyester is extruded into water from the nozzle holes and immediately cut in the molten state.

[0097] For the aliphatic aromatic polyester of the present invention, the underwater hot cutting method is preferred because it results in fewer cutting chips in the obtained pellets, a smaller angle of repose of the obtained pellets, and good pellet transport stability and feeding stability to the molding machine during molding. The cooling water temperature in the underwater cutting method is preferably 10°C or higher, more preferably 20°C or higher, and is preferably 70°C or lower, more preferably 60°C or lower, and even more preferably 50°C or lower.

[0098] The pellets may be spherical, ellipsoidal, cylindrical, elliptical cylinder, oblong cylinder, prismatic, or flattened from these shapes. In the underwater hot cutting method, the pellets are often ellipsoidal, cylindrical, elliptical cylinder, spherical, or flattened from these shapes, with ellipsoidal and cylindrical shapes being preferred.

[0099] <Polyester manufacturing process> In the production of the aliphatic aromatic polyester of the present invention, raw materials are usually mixed with an aliphatic diol component such as 1,4-butanediol in a raw material mixing tank and supplied to an esterification reaction tank in the form of a slurry or liquid through a raw material supply line. When a catalyst is added during the esterification reaction, a solution of the aliphatic diol component such as 1,4-butanediol is prepared in a catalyst preparation tank, and then the catalyst solution is supplied through a catalyst supply line.

[0100] The gas distilled from the esterification reactor passes through a distillation line and is separated into high-boiling components and low-boiling components in a fractionator. Usually, the high-boiling components are mainly aliphatic diol components such as 1,4-butanediol, and the low-boiling components are mainly water and decomposition products of aliphatic diol components such as 1,4-butanediol.

[0101] The high-boiling components separated in the rectification column are withdrawn through the withdrawal line and pumped, with a portion circulated through the recycle line to the esterification reaction tank and a portion returned through the circulation line to the rectification column. The surplus is withdrawn to the outside through the withdrawal line. Meanwhile, the light-boiling components separated in the rectification column are withdrawn through the gas withdrawal line, condensed in the condenser, and temporarily stored in a tank through a condensate line. A portion of the light-boiling components collected in the tank are returned to the rectification column through the withdrawal line, pump, and circulation line, with the remainder being withdrawn to the outside of the system through the withdrawal line. The condenser is connected to an exhaust device through a vent line. The esterification reaction product produced in the esterification reaction tank is supplied to a polycondensation reaction tank (first polycondensation reaction tank) through a withdrawal pump and an esterification reaction product withdrawal line.

[0102] <Physical properties of polyester> The aliphatic aromatic polyester of the present invention obtained by the method for producing an aliphatic aromatic polyester of the present invention is produced so as to contain a specific nucleating agent in a suitable amount relative to the polyester as described above, as a result of the presence of the specific nucleating agent in the production process.

[0103] The lower limit of the intrinsic viscosity (IV) of the aliphatic aromatic polyester of the present invention is preferably 1.0 dL / g or more, particularly preferably 1.2 dL / g or more. The upper limit of the intrinsic viscosity of the aliphatic aromatic polyester of the present invention is preferably 2.5 dL / g, more preferably 2.2 dL / g, particularly preferably 2.0 dL / g. If the intrinsic viscosity is below the lower limit, it is difficult to obtain sufficient mechanical strength when molded into a molded product. If the intrinsic viscosity exceeds the upper limit, the melt viscosity during molding is high, making molding difficult. The intrinsic viscosity of the aliphatic aromatic polyester of the present invention is measured by the method described in the Examples section below.

[0104] The terminal acid value of the aliphatic aromatic polyester of the present invention is preferably 30 eq. / ton or less, more preferably 20 eq. / ton or less, and even more preferably 15 eq. / ton or less. If the terminal acid value of the aliphatic aromatic polyester exceeds the upper limit, the viscosity decrease due to hydrolysis becomes significant, and the quality may be significantly impaired. The terminal acid value of the aliphatic aromatic polyester of the present invention is measured by the method described in the Examples section below.

[0105] The melting point (Tm 2 Although there is no particular limitation on the melting point (Tm), the melting point of the aliphatic aromatic polyester satisfying the above-mentioned suitable intrinsic viscosity and terminal acid value is usually about 100 to 150°C. Therefore, the nucleating agent used in the present invention is 1 ) is preferably about 100 to 165° C. The melting point of the aliphatic aromatic polyester of the present invention is measured by the method described in the Examples section below.

[0106] The temperature-decreasing crystallization peak time of the aliphatic aromatic polyester of the present invention as measured by DSC is preferably 60 seconds or less, more preferably 50 seconds or less. If the temperature-decreasing crystallization peak time is equal to or less than the upper limit, crystallization is sufficiently promoted, and problems due to insufficient crystallization can be suppressed. There is no particular lower limit for the temperature-decreasing crystallization peak time, but it is usually about 30 seconds. The temperature-decreasing crystallization peak time of the aliphatic aromatic polyester of the present invention is measured by the method described in the Examples section below.

[0107] <Polyester composition> The aliphatic aromatic polyester of the present invention may be blended with an aliphatic polyester or an aliphatic hydroxycarboxylic acid polyester. Furthermore, as needed, carbodiimide compounds, fillers, plasticizers, and other biodegradable resins (e.g., polycaprolactone, polyamide, polyvinyl alcohol, cellulose ester, etc.), fine powders of animal or plant substances such as starch, cellulose, paper, wood flour, chitin / chitosan, coconut shell powder, and walnut shell powder, or mixtures thereof, may be blended within the scope of the present invention. Furthermore, in order to adjust the physical properties and processability of the molded product, additives such as heat stabilizers, plasticizers, lubricants, antiblocking agents, nucleating agents other than those satisfying formula (1), inorganic fillers, colorants, pigments, UV absorbers, and light stabilizers, modifiers, and crosslinking agents may be added.

[0108] The method for producing a polyester composition from the aliphatic aromatic polyester of the present invention is not particularly limited, and examples include a method in which raw material chips of the blended polyesters are melt-mixed in the same extruder; a method in which each is melted in a separate extruder and then mixed; a method in which the raw material chips are mixed by kneading using a conventional kneader such as a single-screw extruder, a twin-screw extruder, a Banbury mixer, a roll mixer, a Brabender plastograph, a kneader blender, etc. It is also possible to directly feed each raw material chip into a molding machine to prepare the composition and simultaneously obtain a molded product thereof. [Example]

[0109] The present invention will be described in more detail below with reference to examples. The present invention is not limited to the following examples in any way, as long as the gist of the present invention is not exceeded.

[0110] The methods for measuring the physical properties and evaluation items used in the following examples are as follows.

[0111] <Intrinsic viscosity (IV) (dL / g)> The viscosity was measured using an Ubbelohde viscometer in the following manner. Using a mixed solvent of phenol / tetrachloroethane (mass ratio 1 / 1), the number of seconds it took for a polymer solution with a concentration of 0.5 g / dL and the solvent alone to fall at 30° C. was measured and calculated using the following formula (2). IV=((1+4K H η SP ) 0.5 -1) / (2K H C) …(2) η SP =η / η0-1, where η is the time it takes for the sample solution to fall, η0 is the time it takes for the solvent to fall, C is the concentration of the sample solution (g / dL), and K H is Huggins' constant. K H was set to 0.33.

[0112] <Terminal acid value of ester oligomer (eq. / ton)> 0.3 g of paste-like ester oligomer was placed in a 100 mL beaker, 40 mL of benzyl alcohol was added, and the mixture was heated on a hot plate at 180 °C while blowing in dry nitrogen gas. After 20 minutes, the mixture was cooled to 60 °C with water, while checking for dissolution. Oil droplets on the beaker walls were washed away with 10 mL of benzyl alcohol. One to two drops of phenol red indicator were added to the solution, and the mixture was titrated with a 0.1 mol / L solution of potassium hydroxide in methanol while stirring and blowing in dry nitrogen gas. The titration was completed when the color changed from yellow to red. A blank was also prepared using benzyl alcohol alone, and the terminal acid value (amount of terminal carboxyl groups) was calculated using the following formula (3):

[0113] <Terminal acid value of polyester (eq. / ton)> Polyester pellets were dried in a vacuum oven at 60°C for 8 hours and cooled to room temperature in a desiccator. 0.5 g of the sample was weighed and placed in a test tube. 25 mL of benzyl alcohol was added and dissolved at 195°C for 3 minutes while blowing in dry nitrogen gas. The solution was then cooled and stirred in an ice bath for 40 seconds, after which 2 mL of ethanol was gradually added. One to two drops of phenol red indicator were added to the solution, and titration was completed with a 0.1 mol / L solution of sodium hydroxide in benzyl alcohol while blowing in dry nitrogen gas and stirring. The titration was completed when the color changed from yellow to red. A blank was also prepared by repeating the procedure without adding the polyester sample. The terminal acid value (amount of terminal carboxyl groups) was calculated using the following equation (3): <Formula for calculating terminal acid value> Terminal acid value (eq. / ton)=(ab)×0.1×f / w…(3)

[0114] where a is the amount (μL) of 0.1 mol / L sodium hydroxide solution in benzyl alcohol required for titration, b is the amount (μL) of 0.1 mol / L sodium hydroxide solution in benzyl alcohol required for titration of the blank, w is the amount (g) of the ester oligomer or polyester sample, and f is the titer of the 0.1 mol / L sodium hydroxide solution in benzyl alcohol. The potency (f) of a 0.1 mol / L solution of sodium hydroxide in benzyl alcohol was determined by the following method. Add 5cm of methanol to a test tube 3 Add 1-2 drops of phenol red as an indicator to an ethanol solution of phenol red, and add 0.4 cm of 0.1 mol / L sodium hydroxide solution in benzyl alcohol. 3 Titrate to the color change point with 0.2 cm of 0.1 mol / L hydrochloric acid solution with a known titer as the standard solution. 3 The solution was collected and added, and titrated again with 0.1 mol / L sodium hydroxide in benzyl alcohol to the point of color change (the above operations were carried out under a stream of dry nitrogen gas). The titer (f) was calculated using the following formula (4). Titer (f) = Titer of 0.1 mol / L hydrochloric acid solution × Amount of 0.1 N hydrochloric acid solution collected (μL) / Titer of 0.1 mol / L sodium hydroxide solution in benzyl alcohol (μL) ... (4)

[0115] <Polyester melting point (℃)> For the following Examples 1 to 3 and Comparative Example 1, the endothermic peak temperature was measured using a DSC6220 (manufactured by SII NanoTechnology Inc.) when the temperature was raised from room temperature to 250°C at a rate of 20°C / min, and this was taken as the melting point of the polyester. For the following Examples 5 to 13 and Comparative Examples 2 to 5, the endothermic peak temperature was measured using a DSC7020 (manufactured by Hitachi High-Tech Science Corporation) when the temperature was raised from room temperature to 250°C at a rate of 20°C / min, and this was taken as the melting point of the polyester.

[0116] <Melting enthalpy ratio of polyester> Using a Hitachi High-Tech Science DSC7020, the sample was heated from room temperature to 200°C at a rate of 10°C / min, then cooled from 200°C to -50°C at a rate of 10°C / min, and then heated again from -50°C to 200°C at a rate of 10°C / min. When measuring the DSC of a resin obtained by removing the nucleating agent from an aliphatic aromatic polyester using the above method, the area of the endothermic peak corresponding to the melting of the sample resin during the second heating process was defined as the enthalpy of fusion (ΔHm, ΔHm0, respectively). The value obtained by dividing ΔHm by ΔHm0 (ΔHm / ΔHm0) was defined as the enthalpy of fusion and used for evaluation. This (ΔHm / ΔHm0) value is an index of the degree of crystallization promotion; a larger value indicates greater crystallization promotion.

[0117] <Polyester temperature-reducing crystallization peak time (sec)> 10±1 mg of polyester was placed in an open aluminum pan for DSC measurement and heated to 200°C for 10 minutes under a nitrogen atmosphere. While still in the molten state, the sample pan was placed in a DSC6220 (SII NanoTechnology) and isothermal measurements were performed at 10°C. The time at which the heat generated by crystallization reached its maximum was recorded, and similar measurements were performed at 20°C, 30°C, and 40°C. The shortest time to reach the maximum heat generation was taken as the peak crystallization time during cooling. The smaller this value, the more accelerated the crystallization.

[0118] [Preparation of polycondensation catalyst] A reactor equipped with a stirrer was charged with 343.5 parts by weight of magnesium acetate tetrahydrate, followed by 1,434 parts by weight of anhydrous ethanol (purity ≥99 wt%). 218.3 parts by weight of ethyl acid phosphate (monoester:diester mixture weight ratio 45:55) was then added, and the mixture was stirred at 23°C. After confirming complete dissolution of the magnesium acetate, 410.0 parts by weight of tetra-n-butyl titanate was added. Stirring was continued for an additional 10 minutes, yielding a homogeneous mixture. This mixture was concentrated under reduced pressure, controlling the temperature below 60°C. Approximately half of the ethanol added was distilled off, leaving a translucent, viscous liquid. 1,108 parts by weight of 1,4-butanediol was added, and the mixture was further concentrated under reduced pressure, controlling the temperature below 80°C, to yield a catalyst solution with a titanium atom content of 3.5 wt%.

[0119] [Example 1] A reaction vessel equipped with a stirrer, nitrogen inlet, heater, thermometer, and pressure regulator was charged with the following raw materials: 33.6 parts by weight of succinic acid, 38.6 parts by weight of terephthalic acid, 69.7 parts by weight of 1,4-butanediol, 0.138 parts by weight of trimethylolpropane, 0.10 parts by weight of polyethylene wax (Honeywell "ACumist B6", melting point: 124°C), and 0.0017 parts by weight of sodium hydroxide (NaOH). Tetra-n-butyl titanate was added to the resulting polyester at 30 ppm by weight of titanium atoms. Nitrogen gas was introduced into the vessel while stirring the contents, and the system was purged under reduced pressure to create a nitrogen atmosphere. The system was then heated from 160°C to 230°C over 1 hour with stirring, and the reaction was continued at this temperature for 3 hours. The terminal acid value of the resulting ester oligomer was measured and found to be 90 eq. / ton.

[0120] To this ester oligomer, the catalyst solution was added in an amount to give 70 ppm by weight of titanium atoms per polyester obtained, and the mixture was heated to 250°C over 45 minutes, and at the same time, 0.07 × 10 3 The pressure was reduced to 0.1 Pa or less, and polycondensation was continued while maintaining the heated and reduced pressure state. When a predetermined viscosity was reached, the polymerization was terminated to obtain a polyester copolymer.

[0121] The distillate from the esterification reaction and polycondensation reaction was collected, and the tetrahydrofuran concentration was measured by absolute calibration of gas chromatography. The amount of tetrahydrofuran by-product (THF by-product amount) was calculated to be 0.0047 parts by weight per 100 parts by weight of polyester copolymer.

[0122] [Comparative Example 1] A polyester copolymer was obtained in the same manner as in Example 1, except that polyethylene wax and sodium hydroxide were not added.

[0123] [Example 2] A polyester copolymer was obtained in the same manner as in Example 1, except that the amount of polyethylene wax added was changed to 10 times the amount used in Example 1.

[0124] [Example 3] A polyester copolymer was obtained in the same manner as in Example 1, except that polypropylene wax ("PP7502" manufactured by Clariant Chemicals, melting point: 160°C) was added instead of polyethylene wax.

[0125] [Example 4] A polyester copolymer was obtained in the same manner as in Example 1, except that the amount of sodium hydroxide added was changed to 10 times the amount in Example 1.

[0126] The melting points (Tm 2 The results are shown in Table 1 together with the production conditions. Furthermore, in Examples 1 and 4 and Comparative Example 1, the polymerization time, the intrinsic viscosity (IV) of the produced polyester copolymer, the polymerization rate calculated by dividing the intrinsic viscosity by the polymerization time, the terminal acid value of the produced polyester polymer, and the amount of THF by-produced during production were measured, and the results are shown in Table 2 together with the production conditions.

[0127] In Tables 1 and 2, polyethylene wax is referred to as "PE-Wax" and polypropylene wax is referred to as "PP-Wax." The melting point (Tm 1 ) and the melting point (Tm 2 ) difference (Tm 1 -Tm 2 ) is referred to as "ΔTm". In Tables 1 and 2, the amount of nucleating agent added is the amount added relative to the polyester copolymer, and the amount of basic inorganic compound added is the amount added as metal atoms relative to the polyester copolymer.

[0128] [Table 1]

[0129] [Table 2]

[0130] From Table 1, it can be seen that the polyester copolymers of Examples 1 to 3, in which a nucleating agent satisfying formula (1) according to the present invention was present in the reaction system, had a shorter temperature-lowering crystallization peak time than the polyester copolymer of Comparative Example 1, in which this nucleating agent was not present, and thus crystallization was promoted.

[0131] Comparison of Examples 1 and 4 with Comparative Example 1 in Table 2 reveals that in Examples 1 and 4, the addition of NaOH suppresses (neutralizes) the acid-induced decomposition reaction, thereby reducing the amount of by-produced THF and the terminal acid value.

[0132] [Example 5] A reaction vessel equipped with a stirrer, nitrogen inlet, heater, thermometer, and pressure regulator was charged with the following raw materials: 24.2 parts by weight of succinic acid, 48.0 parts by weight of 2,5-furandicarboxylic acid, 92.4 parts by weight of 1,4-butanediol, 0.138 parts by weight of trimethylolpropane, and 1.00 parts by weight of polyethylene wax (Honeywell "ACumist B6", melting point: 124°C). Tetra-n-butyl titanate was added to the resulting polyester at 30 ppm by weight of titanium atoms. Nitrogen gas was introduced into the vessel while stirring, and the system was purged under reduced pressure to create a nitrogen atmosphere. The system was then heated from 170°C to 190°C over 1 hour with stirring, and the reaction was allowed to proceed at this temperature for 1-2 hours. Thereafter, tetra-n-butyl titanate was further added in an amount to give 70 ppm by weight of titanium atoms per polyester obtained, and the mixture was heated to 240°C over 1.5 hours, and simultaneously 0.07 × 10 3 The pressure was reduced to 0.1 Pa or less, and polycondensation was continued while maintaining the heated and reduced pressure state. When a predetermined viscosity was reached, the polymerization was terminated to obtain a polyester copolymer.

[0133] Comparative Example 2 A polyester copolymer was obtained in the same manner as in Example 5, except that polyethylene wax was not added. The distillate from this esterification reaction and polycondensation reaction was recovered, and the tetrahydrofuran concentration was measured by gas chromatography. The amount of tetrahydrofuran by-product (THF by-product amount) was calculated to be 19.2 parts by weight per 100 parts by weight of the polyester copolymer.

[0134] [Example 6] A reaction vessel equipped with a stirrer, nitrogen inlet, heater, thermometer, and pressure regulator was charged with raw materials: 24.2 parts by weight of succinic acid, 48.0 parts by weight of 2,5-furandicarboxylic acid, 92.4 parts by weight of 1,4-butanediol, and 0.138 parts by weight of trimethylolpropane. Furthermore, tetra-n-butyl titanate was added to the resulting polyester at a concentration of 30 ppm by weight of titanium atoms. Nitrogen gas was introduced into the vessel while stirring the contents, and the system was purged under reduced pressure to create a nitrogen atmosphere. Next, the system was heated from 170°C to 190°C over 1 hour with stirring, and the reaction was continued at this temperature for 1-2 hours. Subsequently, tetra-n-butyl titanate was added in an amount to provide 70 ppm by weight of titanium atoms per polyester, and the temperature was raised to 240°C over 1.5 hours. At the same time, 0.07 x 10 mol / L of tetra-n-butyl titanate was added to the resulting polyester at a concentration of 70 ppm by weight of titanium atoms. The temperature was then raised to 240°C over 1.5 hours. At the same time, 0.07 x 10 mol / L of tetra-n-butyl titanate was added to the resulting polyester at a concentration of 70 ppm by weight of titanium atoms. The reaction mixture was then heated to 240°C over 1.5 hours. 3 The pressure was reduced to 0.01 Pa or less, and a polycondensation reaction was carried out while maintaining the heated and reduced pressure state until a predetermined viscosity was reached. Next, 100 parts by mass of the molten resin was added with 1.00 parts by weight of polyethylene wax ("Luwax AH3" manufactured by BASF, melting point: 113°C) and kneaded, and then the polymerization was terminated to obtain a polyester copolymer.

[0135] [Example 7] The same procedure was carried out as in Example 6, except that the polyethylene wax (BASF's "Luwax AH3") was replaced with a polyethylene wax (Honeywell's "ACumist A6", melting point: 132°C), to obtain a polyester copolymer.

[0136] [Example 8] The same procedure was repeated in Example 6, except that the polyethylene wax ("Luwax AH3" manufactured by BASF) was replaced with a fatty acid amide ("Slipax H" manufactured by Mitsubishi Chemical Corporation, compound name: ethylene bis-12-hydroxystearic acid amide, melting point: 145°C), to obtain a polyester copolymer.

[0137] [Example 9] The same procedure was repeated in Example 6, except that the polyethylene wax ("Luwax AH3" manufactured by BASF) was replaced with a phosphate metal salt ("Ecopromote" manufactured by Nissan Chemical Industries, Ltd., compound name: zinc phenylphosphonate, melting point: 164°C), to obtain a polyester copolymer.

[0138] Comparative Example 3 The same procedure was carried out as in Example 6, except that the polyethylene wax ("Luwax AH3" manufactured by BASF) was replaced with talc ("Nano Ace D-600" manufactured by Nippon Talc Co., Ltd., melting point: 900°C or higher (decomposition)), to obtain a polyester copolymer.

[0139] Comparative Example 4 The same procedure was carried out as in Example 6, except that the polyethylene wax ("Luwax AH3" manufactured by BASF) was replaced with talc ("MS-KY" manufactured by Nippon Talc Co., Ltd., melting point 900°C or higher (decomposition)), to obtain a polyester copolymer.

[0140] [Example 10] The polyester copolymer obtained in Example 5 was fed to a twin-screw extruder (Parker Corporation, HK-25D (41D), cylinder temperature: 220°C) equipped with an underwater cutter (ECON, EUP10, cooling water temperature: 14 to 28°C), melt-kneaded, and then cut to produce spheroidal pellets (major axis approximately 5 mm, minor axis approximately 3 mm) made of an aliphatic aromatic polyester composition. Immediately after cutting, the pellets were cooled with cooling water at 15 to 30°C for several seconds, then centrifuged and recovered.

[0141] [Example 11] A polyester copolymer was obtained in the same manner as in Example 5, except that the amount of polyethylene wax added was changed to 0.1 times (1000 ppm by weight). The obtained polyester copolymer was then made into pellets in the same manner as in Example 10. Immediately after cutting, the pellets were cooled in cooling water at 15 to 30°C for a few seconds, then centrifuged and dehydrated, and recovered.

[0142] No significant fusion was observed in the pellets after pelletization in either of Examples 10 and 11. In particular, when the cooling water temperature was lowered, a tendency for fusion to be reduced was observed.

[0143] [Example 12] A polyester copolymer was obtained in the same manner as in Example 5, except that tetraethylammonium hydroxide (Et4NOH, manufactured by Tokyo Chemical Industry Co., Ltd.) was added simultaneously with the charging of the raw materials so that the amount was 300 ppm by weight based on the polyester obtained. The distillate from the esterification reaction and polycondensation reaction was collected, and the tetrahydrofuran concentration was measured by gas chromatography. The amount of tetrahydrofuran by-product (THF by-product amount) was calculated to be 16.3 parts by weight per 100 parts by weight of the polyester copolymer.

[0144] [Example 13] A polyester copolymer was produced in the same manner as in Example 5, except that sodium hydroxide (NaOH, manufactured by Tokyo Chemical Industry Co., Ltd.) was added simultaneously with the charging of the raw materials so that the sodium atom content per polyester obtained was 30 ppm by weight. The distillate from the esterification reaction and polycondensation reaction was recovered, and the tetrahydrofuran concentration was measured by gas chromatography. The amount of tetrahydrofuran by-product (THF by-product amount) was calculated to be 17.0 parts by weight per 100 parts by weight of the polyester copolymer.

[0145] Comparative Example 5 Production was carried out in the same manner as in Comparative Example 2, except that 22.3 parts by weight of succinic acid, 52.2 parts by weight of dimethyl 2,5-furandicarboxylate, 68.1 parts by weight of 1,4-butanediol, and 0.138 parts by weight of trimethylolpropane were used as raw materials, and a polyester copolymer containing no nucleating agent was obtained. The distillate from the esterification reaction and polycondensation reaction was recovered, and the tetrahydrofuran concentration was measured by gas chromatography. The amount of tetrahydrofuran by-product (THF by-product amount) was calculated to be 7.4 parts by weight per 100 parts by weight of the polyester copolymer.

[0146] The melting points (Tm 2 The melting enthalpy ratio (ΔHm / ΔHm0) was measured, and the results are shown in Tables 3A, 3B, and 4 together with the production conditions. For Examples 10 and 11, the pellet shape and pelletizability were evaluated, and the results are also shown in Table 4.

[0147] In addition, the polymerization time in Examples 12 and 13 and Comparative Examples 2 and 5, the intrinsic viscosity (IV) of the produced polyester copolymer, the polymerization rate calculated by dividing the intrinsic viscosity by the polymerization time, the terminal acid value of the produced polyester copolymer, the amount of THF by-produced during production, and the melting point (Tm 2 The melting enthalpy ratio (ΔHm / ΔHm0) was measured, and the results are shown in Table 5 together with the production conditions.

[0148] In Tables 3A, 3B, 4, and 5, polyethylene wax is referred to as "PE-Wax" and the melting point (Tm 1 ) and the melting point (Tm 2 ) difference (Tm 1 -Tm 2 ) is referred to as "ΔTm". The amounts of nucleating agent and basic organic compound added in Tables 3A, 3B, 4 and 5 are the amounts added relative to the polyester copolymer, and the amount of basic inorganic compound added is the amount added as metal atoms relative to the polyester copolymer.

[0149] [Table 3]

[0150] [Table 4]

[0151] [Table 5]

[0152] From Tables 3A and 3B, it can be seen that the polyester copolymers of Examples 5 to 9, which contain a nucleating agent satisfying formula (1) according to the present invention, have larger ΔHm / ΔHm0 values than the polyester copolymer of Comparative Example 2, which does not contain a nucleating agent, and thus have promoted crystallization. In Comparative Examples 3 and 4, in which a nucleating agent not satisfying formula (1) was used, the value of ΔHm / ΔHm0 was not large enough, and it was found that the effect of promoting crystallization was low.

[0153] As can be seen from Examples 10 and 11 in Table 4, although the value of ΔHm / ΔHm0 varies slightly depending on the amount of nucleating agent added that satisfies formula (1), in all cases, by pelletizing the aliphatic aromatic polyester of the present invention using an underwater cutter, it is possible to pelletize it into ellipsoidal pellets that are less likely to fuse together, and almost no blocking was observed.

[0154] A comparison of Examples 12 and 13 with Comparative Examples 2 and 5 in Table 5 shows that even when a furandicarboxylic acid component is used as a raw material, the addition of a basic compound (Examples 12 and 13) can suppress (neutralize) the decomposition reaction by acid, thereby reducing the amount of THF by-product.

[0155] Although the present invention has been described in detail with reference to specific embodiments, it will be apparent to those skilled in the art that various modifications can be made without departing from the spirit and scope of the invention. This application is based on Japanese Patent Application No. 2020-021757, filed on February 12, 2020, the entire contents of which are incorporated by reference.

Claims

1. A method for producing an aliphatic aromatic polyester by carrying out an esterification and / or transesterification reaction of an aliphatic diol component, an aliphatic dicarboxylic acid component, and an aromatic dicarboxylic acid component as raw materials in the presence of a catalyst, followed by a polycondensation reaction, in which a nucleating agent satisfying the condition of the following formula (1) is present in the reaction system, In the aliphatic diol component, the amount of 1,4-butanediol used is 70 mol % or more based on the total amount of the aliphatic diol component, A method for producing an aliphatic aromatic polyester, wherein the molar ratio of the aliphatic dicarboxylic acid component to the aromatic dicarboxylic acid component is 50:50 to 60:

40. 0℃<Tm １ -Tm ２ ≦100℃ ・・・(1) (In the above formula (1), Tm １ : Melting point of nucleating agent (°C), Tm ２ : melting point of aliphatic aromatic polyester (°C)

2. A method for producing an aliphatic aromatic polyester as described in claim 1, wherein the intrinsic viscosity (IV) of the aliphatic aromatic polyester is 1.0 dL / g or more and 2.5 dL / g or less.

3. 3. The method for producing an aliphatic aromatic polyester according to claim 1, wherein the nucleating agent is present in an amount of 100 to 10,000 ppm by weight based on the aliphatic aromatic polyester produced.

4. The method for producing an aliphatic aromatic polyester according to any one of claims 1 to 3, wherein the esterification and / or transesterification reaction is carried out in the presence of a basic inorganic compound.

5. 5. The method for producing an aliphatic aromatic polyester according to claim 4, wherein the basic inorganic compound is present in an amount of 1 to 100 ppm by weight in terms of metal atoms relative to the aliphatic aromatic polyester produced.

6. The method for producing an aliphatic aromatic polyester according to any one of claims 1 to 5, wherein the aliphatic dicarboxylic acid component is a succinic acid component.

7. The method for producing an aliphatic aromatic polyester according to any one of claims 1 to 6, wherein the aromatic dicarboxylic acid component is a terephthalic acid component and / or a furandicarboxylic acid component.

8. The method for producing an aliphatic aromatic polyester according to any one of claims 1 to 7, wherein the aliphatic dicarboxylic acid component is derived from biomass.

9. The method for producing an aliphatic aromatic polyester according to any one of claims 1 to 8, wherein the aliphatic diol component is derived from biomass.

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