Copolyester ether

Abstract

Provided are a compostable copolyester ether having excellent heat resistance and hydrolysis resistance, and a molded article thereof. This copolyester ether consists of a polyester component composed mainly of a dicarboxylic acid component and an aliphatic diol component and a polyether component composed mainly of polyethylene glycol, and is characterized in that the reduced viscosity of the copolyester ether is 0.5-2.0 dL / g, the main component of the dicarboxylic acid component is 2,5-furandicarboxylic acid, and the aliphatic diol component contains one or more components selected from the group consisting of ethylene glycol, 1,3-propanediol, and 1,4-butanediol. The molded article is mainly composed of the copolyester ether and is any of a fiber, a film, and a bottle.

Description

Copolymerized polyester ether

[0001] The present invention relates to a compostable copolyester ether having excellent heat resistance and hydrolysis resistance.

[0002] In recent years, concerns about the environmental leakage and accumulation of plastics have led to a demand for plastics that can be disposed of in an environmentally friendly manner. Compostable plastics, among other things, are environmentally friendly because they are decomposed by microorganisms. An example of a compostable plastic is polybutylene adipate terephthalate (hereinafter sometimes abbreviated as PBAT). PBAT contains aromatic components, resulting in excellent physical properties and heat resistance. However, its melting point is approximately 60-150°C, which is inferior to that of aromatic polyesters (see Patent Document 1). Another example of a compostable plastic is polylactic acid (hereinafter sometimes abbreviated as PLA). While PLA's melting point varies depending on the amount of isomers, reducing the amount of isomers allows it to achieve a high melting point of approximately 170°C. However, its susceptibility to hydrolysis raises concerns about its durability. Improvements to the hydrolysis resistance of PLA have been investigated. For example, Patent Document 2 discloses the addition of carbodiimide compounds to reduce the hydrolysis rate. However, the carbodiimide compounds are non-plant-derived, raising concerns about their environmental impact.

[0003] Aromatic polyesters are examples of materials with excellent heat resistance and hydrolysis resistance. Among these, polyalkylene furanoates containing 2,5-furandicarboxylic acid structural units, such as polyethylene furanoate (hereinafter sometimes abbreviated as PEF), have a melting point of approximately 210°C, and polybutylene furanoate (hereinafter sometimes abbreviated as PBF), have a melting point of approximately 170°C. While these materials possess excellent heat resistance, their raw materials, 2,5-furandicarboxylic acid and plant-derived diol components, are already commercially available, making them environmentally friendly. Furthermore, these plastics can be produced using known aromatic polyester preparation methods. However, while the compostability of polyalkylene furanoates has already been discussed, it is believed to be inferior to that of PLA and PBAT.

[0004] Copolymerization of PBF with an aliphatic dicarboxylic acid component has been investigated to improve compost degradability. Non-Patent Document 1 (2013) found that PBF was copolymerized with diglycolic acid as an aliphatic component, and that the higher the diglycol content, the better the compost degradability. In particular, when the acid component contains 20 mol% diglycolic acid, the compost degradability is equivalent to that of PBAT. However, when the diglycolic acid content exceeds 20 mol%, the melting point is below 150°C, and both a high melting point and excellent compost degradability cannot be achieved.

[0005] Patent No. 3411289 Publication JP-A-11-80522

[0006] Yunxiao Dong, et al. , Bio-based poly(butylene diglycolate-co-furandicarboxylate) copolyesters with balanced mechanical, barrier and biodegradable properties: A prospective substance for PBAT, Polymer Degradation and Stability, 2022, 202, 110010.

[0007] The present invention has been made in view of the problems inherent in the prior art, and an object of the present invention is to provide a compostable copolymerized polyester ether having excellent heat resistance and hydrolysis resistance.

[0008] In order to achieve the above object, the present inventors have focused on polyalkylene ether glycols, which have high molecular weights and excellent bond stability, and have investigated the use of polyalkylene ether glycols. As a result, they have found that copolymerizing polyethylene glycol, which has excellent hydrophilicity, with polyalkylene furanoate results in a polymer that has higher heat resistance and compost degradability than PBAT, while also having better hydrolysis resistance than PLA and heat resistance equal to or greater than that of PLA, which has a relatively high melting point.

[0009] That is, the present invention has the following configurations. [1] A copolymerized polyester ether composed of a polyester component primarily composed of a dicarboxylic acid component and an aliphatic diol component, and a polyether component primarily composed of polyethylene glycol, wherein the copolymerized polyester ether has a reduced viscosity of 0.5 to 2.0 dL / g, the dicarboxylic acid component is primarily 2,5-furandicarboxylic acid, and the aliphatic diol component contains one or more components selected from the group consisting of ethylene glycol, 1,3-propanediol, and 1,4-butanediol. [2] The copolymerized polyester ether according to [1] above, wherein the mass loss rate of a copolymerized polyester ether film in the following simple composting test is higher than the mass loss rate of a polybutylene adipate terephthalate film. <Simple Composting Test> 50 g of Yawata Bussan Compost YK-12 and pure water were placed in a bottomed glass tube having an inner diameter of 46 mm and a height of 108 mm, and the mixture was mixed uniformly. Two 10 mm square, 0.5 mm thick films were embedded in the center of the container and allowed to stand at a temperature of 58°C and a humidity of 95% RH for 672 hours. The mass loss rate was calculated from the film masses before and after standing using the following formula: Mass loss rate [%] = 100 - M2 / M1 x 100, where M1 is the mass of the film before standing and M2 is the mass of the film after standing. Polybutylene adipate terephthalate film: A film obtained by melt-forming a 0.5 mm thick film of polybutylene adipate terephthalate having a reduced viscosity of 1.68 dL / g and a terephthalic acid content of 51 mol% in the dicarboxylic acid component and then quenching. Copolymerized polyester ether film: A film obtained by melt-forming the copolymerized polyester ether at 240°C to a thickness of 0.5 mm and then crystallizing it for 120 minutes in a hot air dryer heated to 140°C. [3] The copolymerized polyester ether according to the above [1] or [2], wherein the content of the 2,5-furan dicarboxylic acid is 95 to 100 mol % of the total dicarboxylic acid component. [4] The copolymerized polyester ether according to any one of the above [1] to [3], wherein the aliphatic diol component contains ethylene glycol.[5] The copolymerized polyester ether according to any one of [1] to [4] above, wherein the aliphatic diol component comprises 1,4-butanediol. [6] The copolymerized polyester ether according to any one of [1] to [5] above, wherein the content of the polyethylene glycol is 7 to 50 mass% of the total copolymerized polyester ether. [7] The copolymerized polyester ether according to any one of [1] to [6] above, wherein the number-average molecular weight of the polyethylene glycol is 500 to 5,000. [8] The copolymerized polyester ether according to any one of [1] to [7] above, wherein the melting point is 150°C or higher when melted at 300°C, quenched to -50°C at a rate of 20°C / min, and then heated again to 300°C at a rate of 2°C / min, as measured by a differential scanning calorimeter. [9] The copolymerized polyester ether according to any one of [1] to [8] above, wherein the 5% weight loss temperature is 300°C or higher when heated from room temperature at a rate of 10°C / min under a nitrogen atmosphere as measured by a thermogravimetric analyzer.

[10] The copolymerized polyester ether according to any one of [1] to [9] above, which has a reduced viscosity ηsp / c retention rate of 30% or more in a pressure cooker test at a test temperature of 121°C for a test time of 10 hours.

[11] The copolymerized polyester ether according to any one of [1] to

[10] above, which contains 100 to 500 ppm of antimony.

[12] A molded article which is primarily composed of the copolymerized polyester ether according to any one of [1] to

[11] above, and is in the form of a fiber, a film, a sheet, or a bottle.

[0010] It is possible to obtain a copolymerized polyester ether that has higher heat resistance and compostability than PBAT, an existing compostable plastic, better hydrolysis resistance than PLA, an existing compostable plastic, and heat resistance equal to or greater than that of PLA. The raw materials for the copolymerized polyester ether invented are commercially available plant-derived products, and can be polymerized using known methods, so it has a low environmental impact and is highly productive.

[0011] The present invention will be described in detail below. (Description of Composition) The copolymerized polyester ether of the present invention is composed of a polyester component primarily composed of a dicarboxylic acid component and an aliphatic diol component, and a polyether component primarily composed of polyethylene glycol. The dicarboxylic acid component is primarily composed of 2,5-furandicarboxylic acid. The aliphatic diol component contains one or more components selected from the group consisting of ethylene glycol, 1,3-propanediol, and 1,4-butanediol. The polyethylene glycol component is preferably primarily composed of a polyethylene glycol component having a number average molecular weight of 500 to 5,000. Here, the term "primarily composed" refers to a component independently accounting for 80 mol% or more, and may account for 90 mol% or more, 95 mol% or more, 98 mol% or more, or 100 mol%.

[0012] <Polyester Component> The main dicarboxylic acid component in the polyester component constituting the copolymerized polyester ether is 2,5-furandicarboxylic acid. The ratio (content) of 2,5-furandicarboxylic acid to the total dicarboxylic acid components is preferably 90 mol% or more, more preferably 94 mol% or more, even more preferably 95 mol% or more, particularly preferably 96 mol% or more, most preferably 98 mol% or more, and may even be 100 mol%. One or more aromatic dicarboxylic acid components other than 2,5-furandicarboxylic acid may be contained. The aromatic dicarboxylic acid component other than 2,5-furandicarboxylic acid preferably contains an aromatic dicarboxylic acid component having 6 to 22 carbon atoms other than 2,5-furandicarboxylic acid, and the total ratio of the aromatic dicarboxylic acid component having 6 to 22 carbon atoms other than 2,5-furandicarboxylic acid to the total dicarboxylic acid components is preferably less than 10 mol%, more preferably less than 5 mol%. Specific examples of aromatic dicarboxylic acid components having 6 to 22 carbon atoms other than 2,5-furandicarboxylic acid include terephthalic acid, isophthalic acid, phthalic acid, naphthalenedicarboxylic acid, 4,4'-dicarboxybiphenyl, 2,3-furandicarboxylic acid, 2,4-furandicarboxylic acid, and 3,4-furandicarboxylic acid.

[0013] An aliphatic dicarboxylic acid component may be copolymerized as the dicarboxylic acid component in the polyester component constituting the copolymerized polyester ether, which may improve the compost decomposition rate. The dicarboxylic acid component may contain one or more aliphatic dicarboxylic acid components. The total ratio of the aliphatic dicarboxylic acid component to the total dicarboxylic acid component is preferably less than 10 mol%, more preferably less than 5 mol%. By having the ratio of the aliphatic dicarboxylic acid component less than 10 mol%, the copolymerized polyester ether can achieve excellent heat resistance with a melting point of 150°C or higher. Specific examples of aliphatic dicarboxylic acids include malonic acid, succinic acid, glutaric acid, adipic acid, azelaic acid, and sebacic acid.

[0014] The aliphatic diol component in the polyester component constituting the copolymerized polyester ether contains one or more components selected from the group consisting of ethylene glycol, 1,3-propanediol, and 1,4-butanediol. A high melting point can be obtained by selecting at least one of the three aliphatic diols. The three linear aliphatic diols preferably account for 80 mol% or more of the total diol component, more preferably 90 mol% or more, even more preferably 95 mol% or more, and may even be 100 mol%. By having the three linear aliphatic diols account for 80 mol% or more of the total diol component, a high melting point and excellent thermal decomposition resistance can be obtained.

[0015] In one embodiment, the aliphatic diol component preferably contains ethylene glycol, and in another embodiment, the aliphatic diol component preferably contains 1,4-butanediol.

[0016] The oligoalkylene glycol having a molecular weight of less than 500 produced by condensation of the linear aliphatic diol component during the production of the copolymerized polyester ether may be contained in an amount of less than 5 mol% relative to the total diol components, and specific examples thereof include diethylene glycol, triethylene glycol, and oligoethylene glycols with even higher degrees of polymerization, which are produced when ethylene glycol is used. If the oligoalkylene glycol having a molecular weight of less than 500 is less than 5 mol% relative to the total diol components constituting the copolymerized polyester ether, a copolymerized polyester ether having excellent heat resistance and color tone can be obtained.

[0017] <Polyether Component> The polyether component constituting the copolymerized polyester ether is mainly composed of a polyethylene glycol component. The content of the polyethylene glycol component in the copolymerized polyester ether is preferably 7% by mass or more and 50% by mass or less. If the polyethylene glycol content is 7% by mass or more, excellent compost degradability is obtained, and if the polyethylene glycol content is 50% by mass or less, a high melting point is obtained, and more preferably 40% by mass or less.

[0018] Because the polyethylene glycol component is chemically stable, it is unlikely to inhibit the formation and maintenance of alkylene furanoate chains during the production and use of the copolymerized polyester ether. Therefore, the high melting point inherent to the alkylene furanoate chain can be maintained. The alkylene furanoate chains may be bonded via a chain extender, but direct bonding is preferred to obtain a copolymerized polyester ether with a high melting point.

[0019] The number-average molecular weight of the polyethylene glycol component constituting the copolymerized polyester ether is preferably 500 to 5000, more preferably 600 to 4000, and even more preferably 800 to 3000. When the number-average molecular weight of the polyethylene glycol component is within this range, alkylene furanoate chains are easily maintained, resulting in a high melting point, and the copolymerized polyester ether is reduced in molecular weight by enzymes excreted by microorganisms, so that it is quickly metabolized when taken into the body of the microorganism.

[0020] The polyether component may contain 5% by mass or less of a polyalkylene ether glycol having a structure different from the polyethylene glycol component, based on 100% by mass of polyethylene glycol, more preferably less than 1% by mass, and even more preferably less than 0.1% by mass. When the content of polyalkylene ether glycol other than polyethylene glycol is 5% by mass or less based on the mass of polyethylene glycol, an excellent compost decomposition rate can be achieved.

[0021] (Production Method) The copolymerized polyester ether of the present invention can be produced by a known method for producing copolymerized polyesters. For example, the desired copolymerized polyester ether can be obtained by esterifying or transesterifying 2,5-furandicarboxylic acid with an aliphatic diol at 150°C to 220°C, followed by adding polyethylene glycol and a catalyst, stirring, and polycondensing at 190°C to 280°C while reducing the pressure. Alternatively, the desired copolymerized polyester ether can be obtained by polycondensing and transesterifying a polyalkylene furanoate synthesized by a known method with polyethylene glycol at 200°C to 280°C while stirring under reduced pressure. By setting the reaction temperature to 150°C or higher (preferably 190°C or higher, 200°C or higher, or 220°C or higher), it is easy to remove excess diol components and to obtain a copolymerized polyester ether with a high degree of polymerization. Furthermore, by setting the reaction temperature to 280°C or lower, it is easy to suppress thermal decomposition of the 2,5-furandicarboxylic acid structural unit. In the synthesis of the copolymerized polyester ether by the transesterification of polyalkylene furanoate and polyethylene glycol, it is preferable to use a catalyst, but if the catalyst used in the production of the polyalkylene furanoate remains in the polyalkylene furanoate while maintaining its catalytic activity, it is not necessary to add an additional catalyst. The copolymerized polyester ether obtained by the above-mentioned melt polymerization / melt reaction may be further subjected to solid-state polymerization to increase the degree of polymerization.

[0022] The copolymerized polyester ether of the present invention has a reduced viscosity of 0.5 to 2.0 dL / g, preferably 0.6 to 1.8 dL / g, and more preferably 0.7 to 1.5 dL / g. When the reduced viscosity is within this range, molded articles having high mechanical strength can be obtained, and a melt viscosity that facilitates melt molding can be obtained.

[0023] The end group structure of the copolymerized polyester ether of the present invention is not particularly limited, but is preferably composed mainly of carboxyl and hydroxyl terminals, and more preferably 50 eq / ton or less of the carboxyl terminal and 120 eq / ton or less of the hydroxyl terminal. Terminal groups derived from thermal decomposition during polymerization or from raw materials may include furan ring terminals, vinyl terminals, methoxy terminals, etc. Since other terminals excluding the carboxyl and hydroxyl terminals affect the polymerizability and coloration during molding, it is preferable that the total amount of the other terminals be 50 eq / ton or less.

[0024] The copolymer polyester ether of the present invention is compostable. Compostability refers to the property that, when a plastic test piece is buried in compost maintained at approximately 58°C, it is broken down by microorganisms in the compost and ultimately decomposed into carbon dioxide and water, and some of it can become material for the microorganisms' bodies. This process is called compost decomposition, and compostable plastics are called compostable plastics. Compostable plastics are decomposed in two main steps. First, extracellular enzymes excreted by microorganisms catalyze the hydrolysis reaction of the plastic, reducing its molecular weight. This process can also result in other factors, such as chemical hydrolysis reactions not involving enzymes or degradation by ultraviolet light. Next, the plastic, reduced to a water-soluble level, penetrates the cell membrane of the microorganisms while remaining dissolved in water, and is decomposed into carbon dioxide and water through metabolic reactions within the microorganisms.

[0025] The copolymerized polyester ether of the present invention is a compostable plastic. While it is generally possible to obtain information on compostability by evaluation according to JIS K 6953-1, JIS K 6953-1 potentially requires a very long incubation period of up to six months. Therefore, in the present invention, evaluation was performed over a relatively short period using the simplified composting test defined in this specification. In the simplified composting test, the temperature and moisture content within the compost are controlled by using a thermo-hygrostat to control the temperature and humidity of the ambient air in contact with the compost, and the mass loss rate of a plastic film buried in the compost is measured. The compost used was a compost inoculum with excellent activity at around 58°C, as specified in JIS K 6953-1. Furthermore, since the activity of the compost is prone to change, it was used immediately after opening. Furthermore, because the type and number of microorganisms present vary depending on the lot of compost used and the time elapsed since purchase, compostability was determined by a relative evaluation against a blank. It seems that PBAT or PLA, which are known as compostable plastics, could be used as a blank, but since it is necessary to maintain a high humidity setting in order to control the moisture content of the compost in a thermo-hygrostat, PLA, which has extremely low hydrolysis resistance, would significantly fragment the sample even without the involvement of microorganisms, making it difficult to recover and quantify the undecomposed material. Therefore, PBAT, which is compostable and has relatively high hydrolysis resistance, was used as the blank.

[0026] In the simplified composting test, when undecomposed test pieces were removed from the compost after a certain test period, all test pieces, including fragmented pieces, were collected to the extent that they could be visually confirmed, washed with pure water to remove any compost-related contaminants, and vacuum dried at 30°C for 17 hours to remove excess moisture before being weighed. The masses before and after the test were compared, and the mass loss rate was calculated to compare the compost decomposition rate with that of the blank. As compost decomposition progressed, microbial colonies and compost adhered to the film and could not be easily removed. Therefore, if the film was washed to the extent that it was not damaged, and even if microbial colonies and compost remained, and the sample could not be completely recovered within the visually visible range for mass evaluation, the data were not used to calculate the mass loss rate.

[0027] A thermo-hygrostat was used to control the test temperature and moisture content of the compost in the simple compost test, with the temperature set to 58°C. The moisture content of the compost was evaluated in advance by evaluating the solid content, and water was added to bring the moisture content to 75%. The moisture content of the compost was maintained by setting the thermo-hygrostat to 95% RH during the test. The solid content was calculated by weighing 10 g of compost and comparing it with the mass after leaving it to stand for 24 hours in a hot air dryer heated to 60°C.

[0028] Crystallized films were used as samples for evaluation in the simplified composting test. Enzymes generally preferentially decompose the amorphous portions of plastics, leaving the crystalline portions intact. Therefore, even for plastics with the same composition, the higher the crystallinity, the slower the composting rate. To avoid limiting the crystallinity of copolymerized polyester ethers for various applications, it is important to evaluate their composting rate in the crystalline state. Therefore, samples that are amorphous after melt-film formation are crystallized by heating. Furthermore, because the surface area per volume of the evaluation sample affects composting rate, crystallized films adjusted to a specific thickness were cut into uniform shapes and used for the simplified composting test. Specifically, two 0.5 mm-thick crystallized films cut to 10 mm x 10 mm were buried in compost with a moisture content of 75% and placed in a thermo-hygrostat adjusted to 58°C and 95% RH. After 28 days, the films were recovered, washed with pure water, and dried at 30°C for 17 hours to calculate the mass loss.

[0029] The mass loss rate of the copolymerized polyester ether film obtained from the copolymerized polyester ether of the present invention is preferably higher than the mass loss rate of the polybutylene adipate terephthalate film. A specific method for measuring the mass loss rate will be described later.

[0030] The melting point of the copolymerized polyester ether of the present invention is not particularly limited, but when measured by a differential scanning calorimeter, the melting point is preferably 150°C or higher, more preferably 165°C or higher, even more preferably 170°C or higher, and particularly preferably 180°C or higher, when the copolymerized polyester ether is melted at 300°C, rapidly cooled to -50°C at a rate of 20°C / min, and then heated again to 300°C at a rate of 2°C / min. PLA, which has a high melting point among commercially available compostable plastics, is known to have a different melting point depending on the isomer content, and the melting point of particularly high-melting-point grades is 150 to 173°C. A copolymerized polyester ether in the above range is preferably equivalent to or higher than the melting point of high-melting-point grade PLA.

[0031] The copolymerized polyester ether of the present invention has excellent thermal decomposition resistance. Thermogravimetric analysis (TGA) allows the temperature at which a sample thermally decomposes to be evaluated by measuring its weight while heating it. The temperature at which the sample loses 5% of its mass relative to the mass before heating when heated from room temperature at a rate of 10°C / min under a nitrogen atmosphere, is defined as Td. The Td of the copolymerized polyester ether of the present invention is preferably 300°C or higher, more preferably 330°C or higher, even more preferably 350°C or higher, particularly preferably 370°C or higher, and most preferably 380°C or higher. A Td of 300°C or higher suppresses deterioration of physical properties due to thermal decomposition during melt molding. The upper limit of Td of the copolymerized polyester ether of the present invention is not particularly limited, but is, for example, 420°C or lower.

[0032] The copolymerized polyester ether of the present invention is compostable but has sufficient hydrolysis resistance for practical use. Its retention of reduced viscosity ηsp / c in a pressure cooker test at 121°C for 10 hours is preferably higher than that of PLA, specifically, preferably 30% or more, more preferably 40% or more, and even more preferably 60% or more. The upper limit of the retention is not particularly limited, but is, for example, 95% or less.

[0033] (Additives) When producing copolymerized polyester ethers, known polyester polymerization catalysts can be used. For example, acetates and carbonates of lead, zinc, manganese, calcium, cobalt, aluminum, magnesium, sodium, and the like; metal oxides of magnesium, zinc, lead, antimony, germanium, iron, and the like; and organometallic compounds of tin, lead, titanium, and the like can be used alone or in combination depending on the reaction system. Among these, the use of a relatively inexpensive antimony catalyst can sometimes result in excellent polymerization properties, crystallization rate, and color tone. When using an antimony catalyst, the amount of antimony element relative to the copolymerized polyester ether produced using the catalyst is preferably 50 to 5,000 ppm by mass, more preferably 100 to 1,000 ppm by mass, and even more preferably 100 to 500 ppm by mass. When the ratio of antimony element relative to the copolymerized polyester ether produced is within this range, sufficient reduced viscosity is easily achieved, thermal decomposition resistance is relatively good, and coloration tends to be less likely.

[0034] When producing a copolymerized polyester ether, an antioxidant may be used before, during, or after the reaction to suppress thermal degradation, oxidative degradation, and the like. Examples of suitable antioxidants include phosphorus-based, thioether-based, and phenol-based antioxidants. These antioxidants can be used alone or in combination. The total amount of antioxidant added is preferably 0.1% by mass or more and 5% by mass or less based on the copolymerized polyester ether produced. When the amount added is within this range, the effect of suppressing thermal and oxidative degradation of the copolymerized polyester ether is exhibited, and adverse effects on other physical properties also tend to be suppressed.

[0035] A filler may be added to the copolymerized polyester ether of the present invention. Specific examples of fillers include talc, silica, bentonite, montlorinite, zeolite, mica, saponite, hectorite, kaolin, carbon black, carbon nanofiber, metal benzoates, metal stearates, and metal silicates, which may be effective in improving crystallization rate and gas barrier properties. Furthermore, bio-derived components such as starch, cellulose, other sugars, and proteins may be added, which may be effective in improving compost degradability. These may be added alone or in combination of two or more. The amount of filler, bio-derived components, etc. added is not particularly limited, but a total amount of 10% by mass or less based on the copolymerized polyester ether is preferred.

[0036] (Explanation of Use) The copolymerized polyester ether of the present invention has excellent heat resistance and mechanical properties, and therefore can provide molded articles by known molding methods used for general-purpose plastics. When producing molded articles, the copolymerized polyester ether of the present invention can be used alone, in a mixture with other resins, or with some additives. Typical examples of molded articles include fibers, films, sheets, bottles, etc. In particular, it is expected to be used as a substitute for petroleum-derived plastics.

[0037] This application claims the benefit of priority based on Japanese Patent Application No. 2024-107537, filed on July 3, 2024. The entire contents of the specification of Japanese Patent Application No. 2024-107537, filed on July 3, 2024, are incorporated herein by reference.

[0038] Examples and analytical methods are specifically described below, but the present invention is not limited to these examples.

[0039] (Production Example 1) Production of PEF

[0043] 58 parts by mass of 2,5-furandicarboxylic acid (FDCA), 42 parts by mass of ethylene glycol (EG) (EG / FDCA molar ratio: 1.8), and 0.3 mol % triethylamine (relative to furandicarboxylic acid) as a side reaction inhibitor were added to a 5-L reactor equipped with a stirrer, thermometer, and distillation condenser. An esterification reaction was carried out for 90 minutes at 170-230°C and atmospheric pressure with stirring at 80 rpm, during which water and a portion of the ethylene glycol were distilled off. Next, aluminum acetate was added as a catalyst to achieve an aluminum content of 30 ppm relative to the amount of resin produced, and Irgamod 295 (manufactured by BASF) was added to achieve a phosphorus content of 74 ppm relative to the amount of resin produced. The temperature was raised from 220°C to 270°C over 60 minutes while stirring, while the pressure was slowly reduced. A polycondensation reaction was then carried out for 120 minutes at 270°C and a pressure of 10 Pa or less until the target stirring torque was reached. It was confirmed that 1200 g of PEF having a reduced viscosity of 0.76 dL / g was obtained.

[0040] Example 1 24 g of the PEF obtained in Production Example 1 and 6 g of polyethylene glycol having a number average molecular weight of 1000 (hereinafter abbreviated as PEG #1000) were added to an ampoule, and after reducing the pressure to 500 Pa or less, the mixture was heated at 240°C for 20 minutes and melting in the system was confirmed. Then, melt-kneading was carried out at a stirring speed of 100 rpm at 240 to 270°C for 100 minutes to obtain a copolymerized polyester ether shown in Table 1.

[0041] Example 2 A copolymerized polyester ether shown in Table 1 was obtained in the same manner as in Example 1, except that the amount of PEF was 18 g and the amount of PEG#1000 was 12 g.

[0042] (Example 3) A copolymerized polyester ether shown in Table 1 was obtained in the same manner as in Example 1, except that 27 g of PEF was used and 3 g of polyethylene glycol having a number average molecular weight of 2000 (hereinafter abbreviated as PEG#2000) was used instead of PEG#1000.

[0043] (Example 4) A copolymerized polyester ether shown in Table 1 was obtained in the same manner as in Example 1, except that 27 g of PEF was used and 3 g of polyethylene glycol having a number average molecular weight of 4000 (hereinafter abbreviated as PEG#4000) was used instead of PEG#1000.

[0044] (Production Example 2) Method for Producing PBF Into a 5-L reactor equipped with a stirrer, thermometer, and distillation condenser, 43 parts by mass of 2,5-furandicarboxylic acid (FDCA), 57 parts by mass of 1,4-butanediol (BD) (BD / FDCA molar ratio 2.3), and titanium tetrabutoxide as a catalyst were added so that the concentration was 120 ppm relative to the amount of resin produced. An esterification reaction was carried out for 90 minutes at 180-200°C while stirring at 80 rpm, and water and a portion of the BD were distilled off. Next, the temperature was raised from 200°C to 240°C over 60 minutes while stirring, while simultaneously slowly reducing the pressure. A polycondensation reaction was then carried out for 20 minutes at 240°C and 10 Pa or less until the target stirring torque was reached. It was confirmed that 500 g of PBF with a reduced viscosity of 1.05 dL / g was obtained.

[0045] Example 5 27 g of PBF obtained in Production Example 2 and 3 g of PEG #2000 were added to an ampoule, and the pressure was reduced to 500 Pa or less. After heating at 220°C for 20 minutes and confirming that the mixture had melted in the system, the mixture was melt-kneaded at a stirring speed of 100 rpm at 220 to 240°C for 100 minutes, to obtain the copolymerized polyester ethers shown in Table 1.

[0046] Comparative Example 1 Ecoflex C1200 manufactured by BASF was used as polybutylene adipate terephthalate (PBAT). It was confirmed that the reduced viscosity was 1.68 dL / g.

[0047] Comparative Example 2: FY201 manufactured by Anhui Fengyuan Group Co., Ltd. was used as polylactic acid (PLA). It was confirmed that the reduced viscosity was 1.17 dL / g.

[0048] Comparative Example 3 A copolymerized polyester ether shown in Table 1 was obtained in the same manner as in Example 3, except that the amount of PEF was 28.5 g and the amount of PEG#2000 was 1.5 g.

[0049] Comparative Example 4 A copolymerized polyester ether shown in Table 1 was obtained in the same manner as in Example 1, except that the amounts of PEF and PEG#1000 were changed to 28.5 g and 1.5 g, respectively.

[0050] Comparative Example 5 In Production Example 1, the polycondensation reaction time at 270° C. and 10 Pa or less was shortened to obtain the PEF shown in Table 1.

[0051] [Evaluation Method] (Reduced Viscosity ηsp / c) The reduced viscosity ηsp / c was measured using an Ubbelohde viscosity tube. A sample was dissolved in a mixed solvent of phenol / tetrachloroethane (mass ratio 6 / 4) to prepare a sample solution with a concentration of 0.4 g / dL. 10 mL of the sample solution or mixed solvent was placed in an Ubbelohde viscosity tube, and the flow time [seconds] was measured in a constant temperature bath at 30°C. The reduced viscosity ηsp / c [dL / g] was calculated using the following formula: ηsp / c = (t2 / t1-1) / 0.4 where t1 is the flow time [seconds] of the mixed solvent, and t2 is the flow time [seconds] of the sample solution.

[0052] (Melting Point) A differential scanning calorimeter "DSC7020" manufactured by Hitachi High-Tech Science Corporation was used. 5.0 mg of copolymerized polyester ether sample was added to an aluminum pan, the lid was pressed down and sealed, and the temperature was increased from 20°C to 300°C at 10°C / min and held at 300°C for 2 minutes to completely melt the sample. Next, the sample was cooled to -50°C at 50°C / min, held at -50°C for 2 minutes, and then heated again to 300°C at 2°C / min. The endothermic peak temperature of the thermogram curve obtained during the second heating was taken as the melting point.

[0053] (Preparation of Crystallized Film for Simple Composting Test) The copolymerized polyester ethers of the Examples and Comparative Examples were formed into films using a tabletop heat press "SA-302" manufactured by Tester Sangyo Co., Ltd. A 0.5 mm thick mold and a sample were placed between two Teflon (registered trademark) sheets, and the Teflon (registered trademark) sheets were sandwiched between two stainless steel plates and placed in a heat press. After melting at 240°C for 3 minutes, a load of 20 MPa was applied and the film was left to stand for 1 minute. Immediately after releasing the load, the resin was sandwiched between the Teflon (registered trademark) sheets and kept in a hot air dryer heated to 140°C for 120 minutes to promote crystallization of the film. However, in Example 5 and Comparative Example 2, in consideration of the crystallization temperature and crystallization rate of the resin, the crystallization treatment temperature was set to 110°C and the crystallization treatment time to 60 minutes. In Comparative Example 1, the resin crystallized quickly and had a glass transition point lower than room temperature, so crystallization was promoted even at room temperature, and therefore no crystallization treatment was carried out.

[0054] (Evaluation of moisture content in compost) 10 g of compost YK-12 manufactured by Yawata Bussan Co., Ltd., with a moisture content of 65%, was weighed into a bottomed glass tube with an inner diameter of 46 mm and a height of 108 mm, and left to stand for 24 hours in a hot air dryer heated to 60°C. The compost was weighed immediately after being removed from the hot air dryer, and the solid content of the compost was calculated by comparing the mass before and after drying. The mass loss in the dryer was considered to be moisture, and the moisture content was calculated by subtraction. Moisture content [%] = 100 - C2 / C1 × 100 Equation (1) Here, C1 is the mass of the compost before drying, and C2 is the mass of the compost after drying.

[0055] (Simple Compost Test) A crystallized film cut to a thickness of 10 mm x 10 mm was prepared, and 50 g of 65% moisture content compost YK-12 (manufactured by Yawata Bussan Co., Ltd.) and 20 g of pure water (enough to adjust the moisture content of the compost to 75%) were added to a lidless, bottomed glass tube with an inner diameter of 46 mm and a height of 108 mm. Two crystallized films were buried in the center of the compost, and the glass tube was placed in a thermo-hygrostat adjusted to a temperature of 58°C and a humidity of 95%. After 28 days (672 hours), the film was recovered, washed with pure water, and dried in a vacuum dryer at 30°C for 17 hours. The mass loss rate was calculated using the following formula: Mass Loss Rate [%] = 100 - M2 / M1 x 100 (Formula 2) where M1 is the mass of the film before placing, and M2 is the mass of the film after placing. Using Comparative Example 1, which is compostable, as a standard, if a mass loss rate higher than that of Comparative Example 1 was obtained, it was judged to be compostable (rating A), and if the mass loss rate was lower than that of Comparative Example 1, it was judged to be non-compostable (rating B).

[0056] The evaluation results are shown in Table 1.

[0057]

[0058] The copolymerized polyester ether of the present invention has biodegradability equal to or greater than that of PBAT, a typical existing biodegradable polymer, and can achieve a melting point equal to or greater than that of PLA, which is known for its high heat resistance among existing biodegradable polymers.

[0059] Example 6: 58 parts by mass of 2,5-furandicarboxylic acid (FDCA), 42 parts by mass of ethylene glycol (EG) (EG / FDCA molar ratio 1.8), and 0.3 mol% triethylamine as a side reaction inhibitor relative to the furandicarboxylic acid were added to a 2-L reactor equipped with a stirrer, thermometer, and distillation condenser. An esterification reaction was carried out for 90 minutes at 170 to 230°C while stirring at 80 rpm, and water and a portion of the ethylene glycol were distilled off. Next, PEG#2000 was added to a mass ratio of PEF / PEG#2000 = 90 / 10, and diantimony trioxide was added as a catalyst to provide 250 ppm of antimony element relative to the amount of resin produced. The temperature was raised from 220°C to 270°C over 60 minutes while stirring, while the pressure was slowly reduced. A polycondensation reaction was then carried out for 150 minutes at 270°C and 10 Pa or less until the target stirring torque was reached. It was confirmed that 500 g of the copolymerized polyester ether shown in Table 2 was obtained.

[0060] (Hydrolysis Resistance Test) A laboratory autoclave "LSX-500" manufactured by Tomy Seiko Co., Ltd. was used. The autoclave was filled with an evaluation sample and tap water, and the autoclave was sealed and held at 121°C for 10 hours. The reduced viscosity ηsp / c retention rate after that was calculated as a measure of hydrolysis resistance. Reduced viscosity ηsp / c retention rate (%) = [(ηsp / c2) / (ηsp / c1)] × 100, where ηsp / c1 is the ηsp / c of ​​the evaluation sample before the hydrolysis test, and ηsp / c2 is the ηsp / c of ​​the evaluation sample after the hydrolysis test.

[0061] (Thermal decomposition resistance test) A differential thermal and thermogravimetric simultaneous analyzer "DTG-60" manufactured by Shimadzu Corporation was used. Approximately 10 mg of sample was measured while heating from room temperature to 500°C at a rate of 10°C / min in a nitrogen atmosphere, and the temperature and sample weight were recorded. After calculating the weight retention, the temperature at which the weight retention was 95% was taken as the thermal decomposition temperature Td. Weight retention (%) = [(W1-W2) / W1] x 100, where W1 is the initial weight of the evaluation sample, and W2 is the weight of the evaluation sample at a certain temperature.

[0062] The above hydrolysis resistance test and thermal decomposition resistance test were also carried out on the polylactic acid of Comparative Example 2 and the PEF of Comparative Example 5. The evaluation results for each are shown in Table 2.

[0063]

[0064] It was found that the compostable copolymer polyester ether of the present invention has far superior hydrolysis resistance and a higher thermal decomposition temperature than PLA, a typical existing biodegradable polymer.

[0065] The polyester ether of the present invention is compostable and has excellent heat resistance and hydrolysis resistance, and therefore has high industrial utility, specifically, it can be applied to fibers, films, bottles, etc.

Claims

1. A copolymerized polyester ether composed of a polyester component primarily consisting of a dicarboxylic acid component and an aliphatic diol component, and a polyether component primarily consisting of polyethylene glycol, wherein the copolymerized polyester ether has a reduced viscosity of 0.5 to 2.0 dL / g, the main component of the dicarboxylic acid component is 2,5-furandicarboxylic acid, and the aliphatic diol component contains one or more components selected from the group consisting of ethylene glycol, 1,3-propanediol, and 1,4-butanediol.

2. The copolymer polyester ether according to claim 1, wherein the mass loss rate of the copolymer polyester ether film in the following simple composting test is higher than the mass loss rate of a polybutylene adipate terephthalate film. <Simple composting test> 50 g of Yawata Bussan Compost YK-12 and pure water (enough to give a moisture content of 75%) were placed in a bottomed glass tube with an inner diameter of 46 mm and a height of 108 mm, and the mixture was mixed uniformly. Two 10 mm square, 0.5 mm thick films were buried in the center of the tube and allowed to stand at a temperature of 58°C and a humidity of 95% RH for 672 hours. The mass loss rate was calculated from the mass of the films before and after standing using the following formula: Mass loss rate [%] = 100 - M2 / M1 × 100, where M1 is the mass of the film before standing and M2 is the mass of the film after standing. Polybutylene adipate terephthalate film: A film obtained by melt-forming polybutylene adipate terephthalate having a reduced viscosity of 1.68 dL / g and a terephthalic acid content of 51 mol% in the dicarboxylic acid component into a 0.5 mm thick film and rapidly cooling it. Copolymer polyester ether film: A film obtained by melt-forming the copolymer polyester ether into a 0.5 mm thick film at 240°C and then crystallizing it for 120 minutes in a hot air dryer heated to 140°C.

3. The copolymerized polyester ether according to claim 1, wherein the content of said 2,5-furandicarboxylic acid is 95 to 100 mol % of the total dicarboxylic acid component.

4. The copolymerized polyester ether of claim 1, wherein said aliphatic diol component comprises ethylene glycol.

5. The copolymerized polyester ether of claim 1, wherein said aliphatic diol component comprises 1,4-butanediol.

6. The copolymerized polyester ether according to claim 1, wherein the content of the polyethylene glycol is 7 to 50% by mass of the entire copolymerized polyester ether.

7. The copolymerized polyester ether according to claim 1, wherein the polyethylene glycol has a number average molecular weight of 500 to 5,000.

8. The copolymerized polyester ether according to claim 1, which has a melting point of 150°C or higher when measured by a differential scanning calorimeter, after being melted at 300°C, rapidly cooled to -50°C at a rate of 20°C / min, and then heated again to 300°C at a rate of 2°C / min.

9. The copolymerized polyester ether according to claim 1, which has a 5% weight loss temperature of 300°C or higher when heated from room temperature at a rate of 10°C / min in a nitrogen atmosphere using a thermogravimetric analyzer.

10. The copolymerized polyester ether according to claim 1, which has a reduced viscosity ηsp / c retention rate of 30% or more in a pressure cooker test at a test temperature of 121°C for a test time of 10 hours.

11. The copolymerized polyester ether according to claim 1, containing 100 to 500 ppm of elemental antimony.

12. A molded article, which is composed mainly of the copolymerized polyester ether according to any one of claims 1 to 11 and is in the form of a fiber, film, sheet, or bottle.

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