Pellets, injection molded products, and extruded products

Abstract

To provide pellets containing PBSSe with excellent blocking resistance. [Solution] A pellet containing PBSSe having as its main constituent units a constituent unit derived from succinic acid, a constituent unit derived from sebacic acid, and a constituent unit derived from 1,4-butanediol, wherein the Raman spectrum measured from the pellet is 1680-1780 cm⁻¹ -1 The spectrum in the wavenumber range is 1718±5cm². -1 The first wavenumber range, and 1732±5cm -1 In a Raman spectrum fitted using a Lorentz function with two peaks each having a peak top in the second wavenumber range, the intensity of the peak in the first wavenumber range I 01 And the peak intensity I in the second wavenumber range 02 The intensity ratio (I 01 / I 02 Pellets in which the ratio is 1.7 or higher.

Description

[Technical Field]

[0001] This invention relates to pellets containing polybutylene succinate sebacate (sometimes referred to as "PBSSe"), and to injection-molded and extruded articles obtained using these pellets. More specifically, it relates to pellets containing PBSSe that are suitable for injection molding and extrusion molding, and to injection-molded and extruded articles obtained using resin pellets containing these pellets. [Background technology]

[0002] In modern society, paper, plastics, aluminum foil, and other materials are used in a wide range of applications, including packaging materials for various foods, pharmaceuticals, general merchandise, liquids, powders, and solids, as well as agricultural and construction materials. Plastics, in particular, excel in strength, water resistance, moldability, transparency, and cost, and are widely used as bags and containers. Plastics currently used in these applications include polyethylene, polypropylene, polystyrene, polyvinyl chloride, and polyethylene terephthalate. However, molded products made from the above-mentioned plastics do not biodegrade or hydrolyze in the natural environment, or their decomposition rate is extremely slow. As a result, if buried after use, they may remain in the soil, or if dumped, they may spoil the landscape. Furthermore, even when incinerated, they have problems such as generating harmful gases and damaging incinerators.

[0003] To address these challenges, numerous studies and developments have been conducted on biodegradable resins that are broken down into carbon dioxide and water by microorganisms in soil or water. Representative examples of biodegradable resins include aliphatic polyester resins such as polylactic acid, PBS, and polybutylene succinate adipate (PBSA), and aromatic-aliphatic copolymer polyester resins such as polybutylene adipate terephthalate (PBAT).

[0004] Patent Documents 1 and 2 disclose polybutylene succinate sebacate (PBSSe), obtained from an aliphatic diol such as 1,4-butanediol, succinic acid, and sebacic acid, as an example of a polyester resin used as a biodegradable resin in a biodegradable resin composition. The present inventors have focused on PBSSe as a resin that can achieve both excellent biodegradability and excellent mechanical properties and moldability at a high level among biodegradable resins. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2022-157778 [Patent Document 2] Japanese Patent Publication No. 2023-55686 [Patent Document 3] Japanese Patent Publication No. 2024-049583 [Overview of the project] [Problems that the invention aims to solve]

[0006] However, our investigations have shown that when manufacturing molded products using pellets containing PBSSe, a phenomenon called "blocking" sometimes occurs when heat and / or load is applied to the pellets during the drying process or the supply process to the molding machine, causing the pellet particles to fuse together and aggregate (hereinafter referred to as "blocking"). This is thought to be due to the relatively low melting point of PBSSe, which is around 80-105°C. Blocking can hinder the stable supply of pellets to the molding machine. One aspect of the present invention aims to solve the above problems, and provides a supply material for injection molding, extrusion molding, etc., that has good blocking resistance and can stably supply to the molding machine. The present invention aims to provide pellets containing PBSSe. Another aspect of the present invention aims to provide biodegradable injection-molded or extruded articles that can be stably manufactured. [Means for solving the problem]

[0007] The gist of this invention is as follows: [1] A pellet comprising polybutylene succinate sebacate having as its main constituent units a constituent unit derived from succinic acid, a constituent unit derived from sebacic acid, and a constituent unit derived from 1,4-butanediol, The Raman spectrum measured from the aforementioned pellets shows values ​​between 1680 and 1780 cm⁻¹. -1 The spectrum in the wavenumber range is 1718±5cm². -1 The first wavenumber range, and 1732±5cm -1 In a Raman spectrum fitted using a Lorentz function with two peaks each having a peak top in the second wavenumber range, the intensity of the peak in the first wavenumber range I 01 And the peak intensity I in the second wavenumber range 02 The intensity ratio (I 01 / I 02 Pellets in which the ratio is 1.7 or higher. [2] The pellet according to [1], wherein the strength ratio is 3.4 or less. [3] The pellet according to [1] or [2], wherein the strength ratio is 1.9 or greater. [4] The pellet according to any one of [1] to [3], wherein the content of a cyclic dimer consisting of succinic acid and 1,4-butanediol in the pellet is 4000 ppm by mass or less. [5] The pellet according to any one of [1] to [4], wherein the intrinsic viscosity (IV) of the pellet is 1.2 dL / g or more and 2.2 dL / g or less. [6] A pellet according to any one of [1] to [5], wherein the molar ratio of constituent units derived from succinic acid to constituent units derived from sebacic acid (constituent units derived from succinic acid / constituent units derived from sebacic acid) is 70 / 30 to 95 / 5. [7] The pellet according to [6], wherein the molar ratio is 80 / 20 to 90 / 10. [8] The pellet according to any one of [1] to [7], wherein the total number of moles of the constituent units derived from succinic acid, the constituent units derived from sebaciic acid, and the constituent units derived from 1,4-butanediol in the polybutylene succinate sebacate is 80 mol% or more of the total number of moles of the constituent units constituting the polybutylene succinate sebacate. [9] The pellet according to any one of [1] to [8], wherein the content of polybutylene succinate sebacate in the pellet is 80% by mass or more.

[10] An injection-molded resin pellet containing at least one of the pellets described in [1] to [9].

[11] An extruded resin pellet product comprising at least one of the pellets described in [1] to [9]. [Effects of the Invention]

[0008] According to one aspect of the present invention, pellets containing PBSSe, which have good blocking resistance and can be stably supplied to a molding machine, can be obtained as a feed material for injection molding, extrusion molding, etc. Furthermore, according to another aspect of the present invention, biodegradable injection-molded or extruded articles containing PBSSe, which can be manufactured more stably, can be obtained. [Brief explanation of the drawing]

[0009] [Figure 1] This is a Raman chart (Lorentz-fitted Raman Spectrum) showing the results obtained by fitting the Raman spectrum measured from a pellet containing PBSSe using the Lorentz function, according to Example 1. [Modes for carrying out the invention]

[0010] The embodiments of the present invention will be described below, but the present invention is not limited to the following embodiments. It is not a fixed formula, but rather can be implemented with various modifications within the scope of its essence. In this specification, "mass %" and "weight %" are synonymous, "mass ppm" and "weight ppm" are synonymous, and "parts by mass" and "parts by weight" are synonymous. In this specification, expressions representing numerical ranges, such as "XX or more", "YY or less", and "XX to YY", mean numerical ranges including the endpoints XX and YY, unless otherwise specified. When numerical ranges are described stepwise, any combination of the upper and lower limits of each numerical range is also disclosed. Further, in this specification, descriptions such as "at least one selected from the group consisting of XX, YY, and ZZ" mean any one of XX, YY, ZZ, the combination of XX and YY, the combination of XX and ZZ, the combination of YY and ZZ, or the combination of XX, YY, and ZZ.

[0011] The inventors further studied to solve the problem of improving the blocking resistance of pellets containing PBSSe. In the process, the inventors found that the Raman spectrum measured from the pellets of PBSSe changes depending on the production conditions of the pellets. Specifically, the peak intensity attributed to the C=O stretching of the succinic acid unit of PBSSe appearing in the wavenumber range of 1732 ± 5 cm -1 (hereinafter also referred to as the "second wavenumber range") with respect to the peak intensity attributed to the C=O stretching of the succinic acid unit of PBSSe appearing in the wavenumber range of 1718 ± 5 cm -1 (hereinafter also referred to as the "first wavenumber range") is significantly larger in the pellets produced through the slow cooling process than in the pellets produced without going through the slow cooling process, and found that pellets with the intensity ratio of 1.7 or more may have excellent blocking resistance, thus arriving at the present invention.

[0012] In other words, a pellet according to one aspect of the present invention contains polybutylene succinate sebacate having as its main constituent units a constituent unit derived from succinic acid, a constituent unit derived from sebacic acid, and a constituent unit derived from 1,4-butanediol. The Raman spectrum measured from the pellet is 1680-1780 cm⁻¹. -1 The spectrum in the wavenumber range is 1718±5cm². -1 The first wavenumber range, and 1732±5cm -1 In a Raman spectrum fitted using a Lorentz function with two peaks each having a peak top in the second wavenumber range, the intensity of the peak in the first wavenumber range I 01 And the peak intensity I in the second wavenumber range 02 The intensity ratio (I 01 / I 02 The intensity ratio is 1.7 or higher, preferably 1.9 or higher, more preferably 2.2 or higher, and also preferably 3.4 or lower. The range of the intensity ratio is preferably 1.7 or higher and 3.4 or lower, more preferably 1.9 or higher and 3.4 or lower, and particularly preferably 2.2 or higher and 3.2 or lower. The inventors speculate that the reason the pellets according to this embodiment exhibit excellent blocking resistance is because the strength ratio is 1.7 or higher. In the course of further investigation, the inventors observed the changes in the intensity of the peaks observed in the first wavenumber range and the peaks observed in the second wavenumber range in the Raman spectrum when PBSSe was heated to transition from a crystalline state to an amorphous state. As a result, they found that as the temperature increased, the intensity of the peaks observed in the first wavenumber range decreased, while the intensity of the peaks observed in the second wavenumber range increased. Furthermore, in the Raman spectrum of PBSSe, the peaks appearing in the first wavenumber range and the second wavenumber range are attributed to the C=O in the succinic acid units of PBSSe. From this, it is presumed that the peak observed in the first wavenumber range is attributed to the C=O expansion and contraction in the succinic acid units of crystalline PBSSe, and the peak observed in the second wavenumber range is attributed to the C=O expansion and contraction in the succinic acid units of amorphous PBSSe. Therefore, the intensity ratio (I 01 / I 02 ) is considered to be an indicator showing the ratio of crystalline PBSSe and amorphous PBSSe in a pellet containing PBSSe. And, I 01 / I 02 However, pellets with a value of 1.7 or higher have a crystalline and amorphous state of PBSSe within the pellet. It is believed that the optimized balance with the state makes blocking less likely to occur even when heated or pressurized. As a result, the pellets containing PBSSe according to the present invention are thought to exhibit excellent blocking resistance. Consequently, these pellets can be stably used in injection molding and extrusion molding, contributing to the even more stable production of injection molded and extruded products. Furthermore, pellets with a strength ratio of 1.7 to 3.4 exhibit excellent blocking resistance and more reliably prevent the generation of fine powder. In other words, pellets containing PBSSe may chip during transport or molding due to friction between the pellets themselves or between the pellets and the walls of the molding equipment, generating fine powder. Such fine powder can lead to problems such as clogging of the pellet inlet of the extruder or molding machine, variations in the amount of pellets supplied, and a decrease in the production cycle due to the need for cleaning as the extruder or molding machine becomes contaminated. However, pellets containing PBSSe with a strength ratio of 1.7 to 3.4 exhibit excellent blocking resistance and suppress the generation of fine powder. As a result, these pellets can be stably used for injection molding and extrusion molding, and because they do not easily contaminate the extruder or molding machine, they contribute to the more stable and efficient production of injection molded and extruded products.

[0013] The reason why pellets with a strength ratio of 1.7 to 3.4 can achieve a high level of both blocking resistance and prevention of fine powder generation is, as mentioned above, the strength ratio (I 01 / I 02 ) is considered to be an indicator showing the ratio of crystalline PBSSe and amorphous PBSSe in a pellet containing PBSSe, 01 / I 02 However, pellets within the aforementioned specific numerical range are thought to have a more optimized balance between the crystalline and amorphous states of PBSSe within the pellet. As a result, blocking is less likely to occur even when heated or pressurized, and the embrittlement of the pellet surface is suppressed, making it less likely for fine powder to be generated due to friction between pellets or between pellets and the molding device. Consequently, pellets containing PBSSe according to the present invention are thought to achieve a high level of both blocking resistance and prevention of fine powder generation.

[0014] The method for measuring the spectrum of a pellet containing PBSSe according to this embodiment by Raman spectroscopy is not particularly limited, but it is preferable to measure it in accordance with, for example, Japanese Industrial Standard (JIS) K0317:2010 (General Rules for Raman Spectroscopic Analysis). More specifically, for example, the Raman spectrum of the pellet according to this disclosure can be measured using the following Raman spectrometer and under the following conditions. Raman spectrometer: "RAMAN touch" (product name, manufactured by Nanophoton Corporation) Measurement conditions • Measurement mode: Point • Laser wavelength: 532nm • Laser output: 20mW (Neutral-reducing filter opening: 210 / 255) • Diffraction grating: 1200 gr / mm • Pinhole: 50 μm • Exposure time: 10 seconds • Total number of times: 3 • Objective lens: 100x ·Measurement temperature: 25℃

[0015] The Raman spectrum obtained using the above Raman spectrometer and measurement conditions shows a value of 1718±5 cm² attributable to the C=O stretching in the succinic acid unit of PBSSe. -1 The peak of the Raman scattering intensity has a peak top in the first wavenumber range and is 1732±5 cm. -1 The Raman scattering intensity peak has its peak top in the second wavenumber range and consists of two components, as shown in the following equation (1). Fitting is performed using the Lorentz function. In equation (1) below, A represents the peak intensity and w represents the peak width at half maximum. X0 represents the peak position, which in this disclosure is 1718 ± 5 cm. -1 , and 1732±5cm -1 This is the result.

[0016]

number

[0017] Then, in the obtained fitted Raman spectrum (Lorentz-fitted Raman Spectrum), the peak intensity I in the first wavenumber range 01 and the peak intensity I in the second wavenumber range 02 The intensity ratio (I 01 / I 02 Specifically, the peak of the first wavenumber range obtained by fitting (i.e., X0 = 1718 ± 5 cm) is determined. -1 The ratio (A1 / A2) of the intensity A (hereinafter also referred to as "A1") obtained by the above formula (1) relating to the second wavenumber range, and the intensity A (hereinafter also referred to as "A2") obtained by the above formula (1) relating to the peak in the second wavenumber range, is I 01 / I 02 It corresponds to this.

[0018] <Polybutylene succinate sebacate (PBSSe)> The PBSSe according to the present invention is a polyester having as its main constituent units a constituent unit derived from succinic acid, a constituent unit derived from sebacic acid, and a constituent unit derived from 1,4-butanediol. Specifically, for example, the PBSSe according to one aspect of the present invention has as its main constituent units a constituent unit derived from succinic acid represented by the following structural formula (1), a constituent unit derived from sebacic acid represented by the following structural formula (2), and a constituent unit derived from 1,4-butanediol represented by the following structural formula (3). -OC-CH2-CH2-CO- (1) -OC-(CH2)8-CO- (2) -O-(CH2)4-O- (3)

[0019] Furthermore, "constituent units derived from succinic acid" refers to the constituent units corresponding to succinic acid, that is, the constituent units formed by the reaction of the two carboxyl groups present in succinic acid. Similarly, "constituent units derived from sebacic acid" refers to the constituent units corresponding to sebacic acid, that is, the constituent units formed by the reaction of the two carboxyl groups present in sebacic acid. Moreover, "constituent units derived from 1,4-butanediol" refers to the constituent units corresponding to 1,4-butanediol, that is, the constituent units formed by the reaction of the two hydroxyl groups present in 1,4-butanediol. Furthermore, in this specification, the constituent units of PBSSe may be referred to as compound units for the compounds from which each constituent unit is derived. Specifically, for example, a constituent unit derived from succinic acid may be referred to as a "succinic acid unit," a constituent unit derived from sebacic acid as a "sebacic acid unit," a constituent unit derived from 1,4-butanediol as a "1,4-butanediol unit," a constituent unit derived from a carboxylic acid as a "carboxylic acid unit," and a constituent unit derived from a diol as a "diol unit."

[0020] Furthermore, "main constituent unit" usually means that the constituent unit makes up 80 mol% or more of the total number of moles of constituent units of PBSSe. Specifically, in the PBSSe according to this embodiment, the total number of moles of succinic acid units, sebacic acid units, and 1,4-butanediol units is 80 mol% of the total number of moles of constituent units of PBSSe. That concludes the explanation. Furthermore, the PBSSe according to this embodiment may be a polyester in which the total number of moles of succinic acid units, sebacic acid units, and 1,4-butanediol units is 90% or more of the total number of moles of constituent units constituting PBSSe, and may be 95% or more of the total number of moles of constituent units constituting PBSSe, and furthermore, in which no constituent units other than succinic acid units, sebacic acid units, and 1,4-butanediol units are included at all, that is, it may be a polyester consisting only of succinic acid units, sebacic acid units, and 1,4-butanediol units, in which the total number of moles of succinic acid units, sebacic acid units, and 1,4-butanediol units is 100 mol% of the total number of moles of constituent units constituting PBSSe. In this specification, when counting the number of moles of constituent units in PBSSe, the smallest ester unit constituting PBSSe is defined as 1 mole.

[0021] The total ratio of succinic acid units and sebacic acid units in PBSSe is preferably 80 mol% or more, more preferably 85 mol% or more, even more preferably 90 mol% or more, and may be 100 mol% relative to the total dicarboxylic acid units of PBSSe. That is, based on the total number of moles of dicarboxylic acid units in PBSSe, the ratio of the total number of moles of succinic acid units and sebacic acid units is preferably 80 to 100 mol%, particularly preferably 85 to 100 mol%, and more preferably 90 to 100 mol%. By having the ratio of the total number of moles of succinic acid units and sebacic acid units relative to the total number of moles of dicarboxylic acid units in PBSSe within the above range, it is possible to obtain PBSSe with superior biodegradability and mechanical properties.

[0022] The ratio of succinic acid units to sebacic acid units in PBSSe is preferably such that the proportion of succinic acid units is 70 mol% or more, particularly preferably 80 mol% or more, and may be 95 mol% or less, preferably 90 mol% or less, and even more preferably 89 mol% or less, based on the total number of moles of succinic acid units and sebacic acid units. In other words, the molar ratio of succinic acid units to sebacic acid units in PBSSe is preferably succinic acid units / sebacic acid units = 70 / 30 to 95 / 5, particularly preferably 70 / 30 to 90 / 10, more preferably 80 / 20 to 90 / 10, and especially preferably 80 / 20 to 89 / 11. By having the molar ratio of succinic acid units to sebacic acid units within the above range, PBSSe with superior biodegradability and mechanical properties can be obtained.

[0023] Other dicarboxylic acids that can constitute the dicarboxylic acid unit in PBSSe are not particularly limited, but include, for example, aliphatic dicarboxylic acids such as oxalic acid, malonic acid, succinic anhydride, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, undecadicarboxylic acid, dodecadicarboxylic acid, and dimer acid; aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid, and diphenyldicarboxylic acid; and alicyclic dicarboxylic acids such as cyclohexanedicarboxylic acid. These can be used individually or as a mixture of two or more in addition to the above succinic acid. Furthermore, succinic acid, adipic acid, and sebacic acid can be derived from plant materials.

[0024] The proportion of 1,4-butanediol units in PBSSe is preferably 80 mol% or more, more preferably 85 mol% or more, even more preferably 90 mol% or more, even more preferably 95 mol% or more, and may also be 100 mol% relative to the total number of diol units in PBSSe. That is, based on the total number of moles of diol units in PBSSe, the proportion of 1,4-butanediol units is preferably 80 to 100 mol%, more preferably 85 to 100 mol%, even more preferably 90 to 100 mol%, and even more preferably 95 to 100 mol%. Since the proportion of 1,4-butanediol units is within the above range, PBSSe with superior heat resistance and mechanical properties can be obtained.

[0025] Diols other than 1,4-butaneol that can constitute the diol unit in PBSSe include alkylenediols 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; oxyalkylenediols such as diethylene glycol, polyethylene glycol, polypropylene glycol, and polytetramethylene ether glycol; and cycloalkylenediols such as 1,2-cyclohexanediol, 1,4-cyclohexanediol, 1,2-cyclohexanedimethanol, and 1,4-cyclohexanedimethanol. These can be used individually or as a mixture of two or more in addition to the above-mentioned 1,4-butaneol. Furthermore, ethylene glycol, 1,3-propanediol, and 1,4-butanediol can be derived from plant materials.

[0026] PBSSe may have other constitutional units (hereinafter also referred to as "other constitutional units") in addition to the dicarboxylic acid units and the diol units. Examples of copolymerization components that can constitute other constitutional units include, for example, oxycarboxylic 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, fumaric acid, etc.), esters and lactones of the oxycarboxylic acids, polymers of the oxycarboxylic acids, etc., polyhydric alcohols having three or more functional groups (such as glycerin, trimethylolpropane, pentaerythritol, etc.), and at least one component selected from the group consisting of polycarboxylic acids having three or more functional groups or their anhydrides (such as propanetricarboxylic acid, pyromellitic acid, trimellitic acid, benzophenonetetracarboxylic acid, and their anhydrides, etc.).

[0027] Among them, by introducing a constitutional unit derived from at least one polyfunctional compound having three or more functional groups selected from the group consisting of oxycarboxylic acids having three or more functional groups, alcohols having three or more functional groups, and carboxylic acids having three or more functional groups into PBSSe, it is possible to adjust in the direction of increasing the intrinsic viscosity of PBSSe described later. As the above polyfunctional compound having three or more functional groups, oxycarboxylic acids such as malic acid, citric acid, fumaric acid, and polyhydric alcohols having three or more functional groups such as glycerin and trimethylolpropane are preferable, and particularly, malic acid and trimethylolpropane are preferably used.

[0028] As the above polyfunctional compound unit having three or more functional groups, it is preferably 0.001 to 5 mol% with respect to all the dicarboxylic acid units in PBSSe, and particularly preferably 0.05 to 0.5 mol%. By setting the ratio of the polyfunctional compound unit having three or more functional groups in PBSSe within the above range, it is possible to more reliably prevent the formation of gels (unmelted substances) in the polyester while adjusting the intrinsic viscosity of PBSSe within a preferable range as follows.

[0029] <Physical properties of PBSSe> The intrinsic viscosity (IV) of PBSSe is preferably 1.2 dL / g or more, particularly preferably 1.4 dL / g. Also, it is preferably 2.2 dL / g or less, particularly preferably 2.0 dL / g or less. That is, the intrinsic viscosity of PBSSe is preferably 1.2 dL / g or more and 2.2 dL / g or less, particularly preferably 1.4 dL / g or more and 2.0 dL / g or less. By setting the intrinsic viscosity of PBSSe within the above range, the mechanical strength of the molded product can be further increased, and the viscosity during melting can be adjusted to an appropriate range. As a result, high-quality injection-molded products and extrusion-molded products can be manufactured more easily. Note that the intrinsic viscosity depends on the molecular weight of PBSSe, and the higher the molecular weight, the higher the intrinsic viscosity can be.

[0030] The intrinsic viscosity can be measured, for example, in accordance with JIS K7367-1:2002 (ISO 1628-1:1998). Specifically, for example, using an Ubbelohde viscometer, and using a mixed solvent of phenol / tetrachloroethane (mass ratio 1:1) as the solvent, at a temperature of 30 °C, measure the dropping seconds of a PBSSe solution with a concentration of 0.5 g / dL and the dropping seconds of only the mixed solvent, and the intrinsic viscosity can be obtained from the following formula (2). IV = ((1 + 4K H η sp ) 0.5 -1) / (2K H C) ··· (2) However, in formula (2), η SP = η / η0 - 1, where η is the dropping seconds of the sample solution, η0 is the dropping seconds of the solvent, C is the sample solution concentration (g / dL), and K H is the Huggins constant. K H adopts 0.33.

[0031] <Pellets containing PBSSe> There are no particular restrictions on the shape and size of the pellets containing PBSSe, and it is preferable that they have a shape and size suitable for being subjected to known plastic processing methods such as injection molding and extrusion molding. Specific examples of the shape include, for example, cylindrical, elliptical columnar, prismatic, disc-shaped, spherical, and the like. Also, as for the size, the size of the pellets may generally be the commonly used size. Specifically, for example, those having a diameter or one side of about 0.7 to 12 mm can be mentioned. Further, when the pellets containing PBSSe are subjected to the solvent contact step described later, from the viewpoint of the extraction efficiency of the cyclic dimer by the solvent contact step, etc., it is preferable that the mass of one particle of the pellets is 1 to 50 mg, particularly preferably 3 to 40 mg, and even more preferably 5 to 30 mg.

[0032] <Cyclic dimer in pellets containing PBSSe> In the pellets containing PBSSe, it is preferable that the content of the cyclic dimer is 4000 mass ppm or less, particularly preferably 3500 mass ppm or less, more preferably 3000 mass ppm or less, even more preferably 2000 mass ppm or less, and even more preferably 1500 mass ppm or less. By setting the content of the cyclic dimer in the pellets to the above specific amount or less, the blocking resistance of the pellets can be further improved. Here, the cyclic dimer is a compound that is by-produced when a part of the polyester obtained by reacting a dicarboxylic acid component mainly composed of succinic acid and a diol component mainly composed of 1,4-butanediol is cyclized, and refers to the cyclic dimer composed of succinic acid and 1,4-butanediol. Such a cyclic dimer can be represented, for example, by the following structural formula (4).

[0033] [Chemical formula]

[0034] There is no particular lower limit to the content of cyclic dimers in pellets containing PBSSe, and it may be 0 ppm by mass. However, setting the cyclic dimer content to 0 ppm by mass may lead to an increase in the number of steps required to remove cyclic dimers from synthesized PBSSe, and the need for larger equipment for such removal. From the viewpoint of reducing environmental impact, it is preferable to set the content to 1 ppm by mass or more, particularly preferably 50 ppm by mass or more, and even more preferably 100 ppm by mass or more. Therefore, the cyclic dimer content in pellets containing PBSSe is preferably 1 to 4000 ppm by mass, particularly preferably 50 to 3500 ppm by mass, even more preferably 100 to 3000 ppm by mass, even more preferably 100 to 2000 ppm by mass, and even more preferably 100 to 1500 ppm by mass. The method for quantifying cyclic dimers in lett is not particularly limited, but one example is the use of an absolute calibration curve. Specific methods will be explained in the examples. Furthermore, the method for adjusting the cyclic dimer content in pellets containing PBSSe will be described later.

[0035] The pellets containing PBSSe can contain other components in addition to PBSSe. As one of the other components, for example, a release agent can be mentioned. Examples of the release agent include those commonly used in injection molding and extrusion molding. Specifically, for example, ester compounds of polyhydric alcohols and long-chain aliphatic carboxylic acids (for example, ester compounds of stearic acid or montanic acid and ethylene glycol, glycerin, or pentaerythritol), amide compounds of long-chain aliphatic carboxylic acids (for example, stearic acid or montanic acid, etc.) and stearylamine or ethylenediamine, silicone compounds, etc. can be mentioned. As the blending ratio of the release agent, in order to prevent blocking of the pellets due to excessive bleeding of the release agent onto the pellet surface and improve the releasability of the molded product, based on the pellets containing PBSSe, 0.001 to 1% by mass is preferable, and 0.005 to 0.8% by mass is particularly preferable. Also, within a range not impairing the object of the present invention, additives can be contained as other components. Examples of the additives include reinforcing materials such as talc, kaolin, mica, clay, bentonite, sericite, basic magnesium carbonate, aluminum hydroxide, glass flakes, glass fibers, carbon fibers, asbestos fibers, rock wool, calcium carbonate, silica sand, wollastonite, barium sulfate, glass beads, titanium oxide, etc., non-plate-shaped fillers, or antioxidants (phosphorus-based, sulfur-based, etc.), ultraviolet absorbers, heat stabilizers (hindered phenol-based, etc.), transesterification inhibitors, lubricants, antistatic agents, colorants including dyes and pigments, flame retardants (halogen-based, phosphorus-based, etc.), flame retardant aids (antimony compounds represented by antimony trioxide, zirconium oxide, molybdenum oxide, etc.), antibacterial agents, etc. Furthermore, as one of the other components, it may contain other resins other than PBSSe. In this case, as the content ratio of the other resin in the pellets, 20% by mass or less is preferable, 10% by mass or less is more preferable, 5% by mass or less is particularly preferable with respect to PBSSe in the pellets, and also 0% by mass, that is, the resin component in the pellets can be only PBSSe.

[0036] <Method for producing pellets containing PBSSe> Pellets containing PBSSe can be manufactured, for example, by following steps 1 to 4 below, or steps 1 to 5 below. (Step 1) A dicarboxylic acid component comprising at least one selected from the group consisting of succinic acid and its ester-forming derivatives, and at least one selected from the group consisting of sebacic acid and its ester-forming derivatives, and a diol component comprising at least 1,4-butanediol are mixed in a predetermined proportion under stirring to obtain a raw material slurry. (Step 2) Following Step 1 above, the raw material slurry is heated under normal pressure or under pressure to undergo an esterification reaction to obtain a PBSSe low polymer. (Step 3) Following Step 2 above, the obtained low polymer is gradually subjected to reduced pressure and heated to carry out a melt polycondensation reaction under a polycondensation catalyst. (Step 4) Following Step 3 above, the molten PBSSe is extruded into strands and cut into pellets to obtain pellets containing PBSSe. (Step 5) If necessary, 01 / I 02 Control, or I 01 / I 02 Processing is performed to control the content of cyclic dimers and other related factors. Furthermore, a process of wind separation and sieving of pellets may be performed between step 4 and step 5, and / or after step 5.

[0037] An example of step 2 above for obtaining the PBSSe low polymer is, for example, using a single esterification reactor or a multi-stage reactor in which multiple esterification reactors are connected in series, while removing the water and excess diol components produced in the reaction from the system, the esterification reaction rate (the proportion of all carboxyl groups of the starting material dicarboxylic acid component that react with the diol component and are esterified) One method involves continuing the process until the polymer content reaches 90% or more, in order to obtain a low polymer of PBSSe.

[0038] An example of step 3, in which a melt polycondensation reaction is carried out, is a multi-stage reactor consisting of, for example, a single melt polycondensation tank or multiple melt polycondensation tanks connected in series, with the first stage being a fully mixed reactor equipped with stirring blades, and the second and third stages being horizontal plug-flow reactors equipped with stirring blades, while distilling the diol produced out of the system under reduced pressure.

[0039] The PBSSe polycondensation catalyst may be added to the reaction system at any stage of the mixing and preparation of the dicarboxylic acid component and the diol component, at any stage of the process of forming the PBSSe low polymer, or at an early stage of the melt polycondensation process. In this case, one or more conventionally known metal compounds such as antimony, germanium, and titanium may be used as the PBSSe polycondensation catalyst.

[0040] Furthermore, in steps 1 and 2 above, which involve the formation of a low polymer of PBSSe, and in step 3 above, which involves melt polycondensation, antioxidants and basic compounds can be added to suppress side reactions such as thermal decomposition and dimerization of diols.Specific examples of antioxidants include, for example, Irganox 1330 (manufactured by BASF) and Irganox 1010 (manufactured by BASF), and examples of basic compounds include, for example, tertiary amines such as triethylamine, tri-n-butylamine, and benzyldimethylamine, quaternary ammonium hydroxides such as tetraethylammonium hydroxide, tetra-n-butylammonium hydroxide, and trimethylbenzylammonium hydroxide, lithium carbonate, sodium carbonate, sodium hydroxide, potassium carbonate, and sodium acetate.

[0041] Examples of the above step 4, which involves cutting the synthesized PBSSe into pellets, include the strand cutting method, in which molten PBSSe is extruded from the nozzle hole of a die head using a gear pump or extruder and then cut with a cutter while being cooled with water or the cooled and solidified strand is cut; and the underwater hot cutting method, in which molten PBSSe is extruded into water from the nozzle hole and immediately cut.

[0042] <Intensity ratio (I01 / I 02 ) How to adjust > I related to the above step 5 01 / I 02 This section explains the adjustment (control) of the system. Pellets containing PBSSe 01 / I 02 For example, this can be adjusted by adjusting the temperature and time added to the pellet containing PBSSe in a step in which the PBSSe synthesized by solution polycondensation in step 3 above is extruded in strand form from a die into a cooling liquid and held at a predetermined temperature for a predetermined time (hereinafter also referred to as the "slow cooling step"), or in a step that combines the slow cooling step with a step of immersing in a solvent adjusted to a predetermined temperature for a predetermined time (hereinafter also referred to as the "solvent contact step").

[0043] <Slow cooling process> The slow cooling process can be performed before or during step 4. Specifically, the PBSSe extruded from the die into a cooling liquid adjusted to a predetermined temperature is kept in the cooling liquid in a strand for a predetermined time. After that, it is cut to form pellets. Alternatively, the PBSSe extruded from the die into a cooling liquid adjusted to a predetermined temperature is cut in the cooling liquid to form pellets (process Step 4) The pellet is held in the cooling liquid for a predetermined time.

[0044] By slowly cooling fused PBSSe, the orientation of the molecules in the fused PBSSe is promoted, making it possible to appropriately develop the crystalline structure of PBSSe. Here, if fused PBSSe is extruded, for example, into a room temperature (25°C) environment, P As BSSe is rapidly cooled, the molecules of PBSSe are fixed in a randomly oriented state, 01 / I 02 It becomes difficult to achieve a value of 1.7 or higher.

[0045] Here, the temperature of the cooling liquid used to extrude the molten PBSSe into strands is preferably 35 to 65°C, particularly preferably 40 to 60°C, and even more preferably 45 to 55°C. The time for holding PBSSe within the above temperature range is I 01 / I 02 While there are no particular restrictions as long as it can be 1.1 or higher, it is preferable to set it to, for example, 0.1 to 10 minutes, more preferably 0.5 to 5 minutes, and even more preferably 1 to 3 minutes. When the holding time is extended within the above temperature range of the pellet containing PBSSe, 01 / I 02 The value of is generally large. Note that if the temperature of the cooling liquid is set higher within the above range, adjustments such as shortening the holding time may be necessary to achieve the desired I 01 / I 02 This can be done as appropriate depending on the value.

[0046] Furthermore, the type of cooling liquid is not particularly limited as long as it does not react with or dissolve PBSSe during the above temperature range and holding time. Examples of such cooling liquids include water.

[0047] Furthermore, pellets that have undergone a process of being kept in water (hot water) at a temperature exceeding the above temperature range for a predetermined time as a cooling liquid, for reasons that are not clear, 01 / I 02 The value may exceed 3.4. This means that the proportion of crystalline PBSSe in the pellet becomes too high. As a result, such pellets, with their excessive crystalline content, have a brittle surface and can easily generate fine powder due to friction between pellets or with the molding equipment.

[0048] <Solvent Contact Process> It is preferable to carry out a solvent contact step following the slow cooling step described above. This step reduces the content of cyclic dimers in the pellets and 01 / I 02This process contributes to further adjustment of the value, and by going through this process, the content of cyclic dimers in the pellet can be adjusted to a smaller value within the aforementioned range, and I 01 / I 02 It is possible to adjust this to a higher value, preferably within the range of 1.7 to 3.4, which is 1.7 or higher. This step involves contacting the pellets obtained through the slow cooling step described above with a solvent capable of dissolving the cyclic dimer, which has been adjusted to a predetermined temperature, for a predetermined time. By going through this step, at least a portion of the cyclic dimer in the pellets can be removed, and the content of the cyclic dimer in the pellets can be adjusted to 4000 ppm by mass or less, and I 01 / I 02 This can be adjusted to a higher value within the range of 1.7 to 3.4. In other words, the inventors hypothesize that the cyclic dimer in the pellet is a component that inhibits the crystallization of PBSSe. By forming a macroscopic crystalline structure of PBSSe in the slow cooling step, I 01 / I 02 Pellets with a ratio of 1.7 or higher can be obtained. Furthermore, by subjecting these pellets to the solvent contact step described above, the cyclic dimers can be removed from the pellets, reducing the cyclic dimer content to 4000 ppm or less, and it is presumed that a microcrystalline structure of PBSSe can be more easily formed in the pellets. Here, in the solvent contact step, the pellets are held at a predetermined temperature for a predetermined time, so in a state where the crystallization inhibiting component (cyclic dimer) is low, the orientation of PBSSe molecules in the pellets progresses further, and I 01 / I 02 It is believed that pellets with a higher value of 1.7 or more, preferably within the range of 1.7 to 3.4, can be obtained. Furthermore, even if only the solvent contact process is performed without the slow cooling process, 01 / I 02It is difficult to achieve a value of 1.7 or higher. In other words, in order to develop the microcrystalline structure of PBSSe by removing the cyclic dimer in the solvent contact process, it is necessary to perform a slow cooling process prior to the solvent contact process to form the macrocrystalline structure of PBSSe in the pellet. It is thought that...

[0049] The solvent used in this process is preferably one that does not substantially dissolve PBSSe even when in contact with the pellet at a predetermined temperature and for a predetermined time, while on the other hand, it can dissolve the cyclic dimer well. Examples of such solvents include C1 to C4 alcohols (methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, etc.). Alternatively, it may be an aqueous solution of at least one alcohol selected from the group consisting of these alcohols. The concentration of the alcohol in such an aqueous alcohol solution is not particularly limited, but for example, from the viewpoint of good solubility of the cyclic dimer, it is preferably 10% by mass or more and less than 100% by mass based on the aqueous alcohol solution.

[0050] Furthermore, the solvent temperature in the solvent contact step is preferably 65°C or lower, particularly preferably 60°C or lower, and even more preferably 55°C or lower, so as not to excessively increase the crystallinity of PBSSe. As a lower limit, from the viewpoint of better extracting the cyclic dimer and appropriately oriented the molecules of PBSSe, it is preferably 35°C or higher, particularly preferably 40°C or higher, and even more preferably 45°C or higher. In other words, the solvent temperature range in the solvent contact step is preferably 35 to 65°C, particularly preferably 40 to 60°C, and even more preferably 45 to 55°C. Furthermore, as for the processing time, from the viewpoint of better extracting the cyclic dimer and appropriately oriented the molecules of PBS, it is preferably 0.1 to 10 hours, particularly preferably 0.5 to 8 hours, and even more preferably 1 to 5 hours.

[0051] Specific methods for the solvent contact process described above include, for example, the methods described in i) and ii) below. i) A method in which pellets obtained through a slow cooling process and a solvent are placed in a processing tank, and after contacting them at the predetermined temperature range and for the predetermined time, the pellets are recovered from the processing tank; ii) A method of continuously supplying pellets obtained through a slow cooling process to a processing tank, while flowing a solvent adjusted to the above-mentioned predetermined temperature range in parallel or countercurrent flow relative to the flow of pellets, allowing the pellets to be processed and the solvent to come into contact for a predetermined time, and then continuously recovering the processed pellets. The specific methods and apparatus used in this process are not particularly limited, but the method and apparatus described in Patent Document 3, which can continuously adjust the content of cyclic dimers in pellets, can be suitably used.

[0052] <Application> As described above, I 01 / I 02 However, pellets containing PBSSe with a ratio of at least 1.7 and preferably with a cyclic dimer content of 4000 ppm by mass or less are less prone to pellet blocking when subjected to injection molding or extrusion molding. As a result, the supply stability to the molding machine is not hindered during molding, and molded products can be manufactured stably. 01 / I 02 However, pellets containing PBSSe, which have a concentration of at least 1.7 to 3.4 and preferably a cyclic dimer content of 4000 ppm by mass or less, are less prone to pellet blocking when subjected to injection molding or extrusion molding, and can better prevent the generation of fine powder through contact between pellets or between pellets and molding equipment. As a result, the supply stability to the molding machine during molding is not hindered, and contamination of the molding machine and extruder by fine powder is also prevented. Therefore, molded products (injection molded products, extruded products, etc.) can be manufactured stably and productively. Thus, the pellets according to this disclosure are extremely useful as pellets for injection molding and extrusion molding to obtain biodegradable molded products. <Molded products (injection molded products, extruded products)> Resin pellets for obtaining injection molded or extruded products are pellets containing PBSSe. It may consist of only these. Here, two or more types of PBSSe pellets containing succinic acid units, sebacic acid units, and 1,4-butanediol units in different molar ratios can also be mixed to form resin pellets.

[0053] Injection molded articles and extruded articles of resin pellets containing PBSSe as relating to this disclosure are obtained by molding using resin pellets containing PBSSe as relating to this disclosure by injection molding or extrusion molding. The molded shape can be any shape that can be molded by injection molding or extrusion molding. There are no limitations on the use of injection-molded or extruded products. Examples of injection-molded products include cutlery and various containers (cups, cosmetic containers, food containers, detergent containers, bleach containers, etc.). Examples of extruded products include packaging materials (packaging films) and agricultural films (agricultural mulch films). [Examples]

[0054] The present invention will be described in more detail below with reference to examples, but the present invention is not limited in any way to the following examples unless it exceeds the gist of the invention. The measurement methods for the physical properties and evaluation items used in the following examples are as follows.

[0055] <Intrinsic viscosity (IV) dL / g> The following procedure was used with an Ubbelohde viscometer: A mixed solvent of phenol / tetrachloroethane (mass ratio 1 / 1) was used, and the number of seconds for dropping a 0.5 g / dL polymer solution and the solvent alone was measured at a temperature of 30°C. The result was then calculated using the following formula (3). IV = ((1 + 4K H η sp ) 0.5 -1) / (2K H C) ... (3) However, in formula (3), η SP=(η / η0 - 1), where η is the number of seconds for the sample solution to drop, η0 is the number of seconds for the solvent to drop, C is the sample solution concentration (g / dL), and K H is the Huggins constant. K H adopted a value of 0.33.

[0056] <Content of cyclic dimer of PBSSe> Precisely weigh 0.5 g of the pellet, add 10 mL of chloroform, dissolve it at room temperature, then slowly drop 30 mL of an ethanol / water mixture (volume ratio 4 / 1) while stirring to precipitate the polymer component. After 15 minutes, stop stirring and perform static separation for 90 minutes. Next, collect 2 mL of the supernatant, evaporate it to dryness, add 2 mL of acetonitrile to dissolve it. After filtering through a 0.45 μm diameter filter, use high performance liquid chromatography (trade name: Prominence, manufactured by Shimadzu Corporation). Start with a mobile phase of acetonitrile / water (volume ratio = 4 / 6), and continuously change the composition to acetonitrile / water (volume ratio = 9 / 1) by the high pressure gradient method for elution. The column was analyzed using an octadecylsilylated silica gel (ODS) column (trade name: CAPCELL PAK C-18 TYPE MGII, silica gel particle size: 5 μm, inner diameter: 4.6 mm, length: 150 mm; manufactured by Osaka Soda Co., Ltd.). Also, a UV detector was used as the detector, and the detection wavelengths were 210 nm and 254 nm. The obtained results were quantified using an absolute calibration curve method with a pure cyclic dimer product. And it was expressed in mass ppm relative to the pellet.

[0057] Note that the pure cyclic dimer product was obtained as follows. That is, a PBS pellet obtained by polymerizing succinic acid and 1,4-butanediol was stirred in acetone at a temperature of 50 °C for 12 hours to extract the oligomer component. After the extraction was completed, the pellet was filtered off, and acetone was evaporated from the acetone solution from which the oligomer component had been extracted to obtain a solid. This solid was dissolved in acetone at a temperature of 50 °C to form a saturated solution, and then slowly cooled to room temperature (25 °C) to perform a recrystallization operation to precipitate needle-like precipitates (crystals). Next, discard the supernatant, and for the said crystals The crystals were collected. The obtained crystals were further subjected to the above recrystallization operation several times for purification. These crystals were analyzed by 1H-NMR analysis and high-performance liquid chromatography analysis to confirm that they were cyclic dimers formed from succinic acid and 1 ,4-butanediol.

[0058] <Raman band intensity ratio (I 01 / I 02 )> Using "RAMAN touch" (trade name, manufactured by Nanophoton Co., Ltd.) as a Raman spectrometer, the Raman spectrum of the pellet was measured. The measurement conditions were as follows. <Measurement conditions> <Measurement mode: Point · Laser wavelength: 532 nm · Laser output: 20 mW (opening degree of the attenuation filter: 210 / 255) · Diffraction grating: 1200 gr / mm · Pinhole: 50 μm · Exposure time: 10 seconds · Number of integrations: 3 times · Objective lens: 100 times · Measurement temperature: 25 °C

[0059] Regarding the obtained Raman spectrum, the peak of the Raman scattering intensity having a peak top in the first wavenumber range of 1718 ± 5 cm -1 , and the peak of the Raman scattering intensity having a peak top in the second wavenumber range of 1732 ± 5 cm -1 were fitted using the Lorentz function shown in the above formula (1). In the obtained Lorentz-fitted Raman spectrum, the intensity ratio (I 01 ) between the peak intensity I in the first wavenumber range and the peak intensity I 02 in the second wavenumber range was determined. Specifically, the peak in the first wavenumber range obtained by fitting (i.e., X0 = 1718 ± 5 cm 01 / I 02 ) was obtained. Specifically, the peak in the first wavenumber range obtained by fitting (i.e., X0 = 1718 ± 5 cm -1The intensity A in the above formula (1) related to (hereinafter also referred to as "A1"), and the ratio (A1 / A2) of the intensity A in the above formula (1) related to the peak in the second wavenumber range (that is, X0 = 1732 ± 5 cm -1 ), from which I / I 01 was calculated. In this example, the average value of three measurements was calculated. Specifically, three measurement samples were taken from the pellet to be measured, and for each measurement sample, the above Raman spectrum measurement, fitting, and calculation of I 02 / I 01 were performed. The average value of I 02 / I 01 for each measurement sample was calculated, and the I 02 / I 01 / I 02 of each example and each comparative example was used.

[0060] <Melting Point> Using a thermal analysis system (product name: DSC3; manufactured by Mettler Toledo), the endothermic peak temperature when the temperature was raised from room temperature to 200 °C at a rate of 10 °C / min was measured and taken as the melting point of the pellet.

[0061] <Heat Fusion Test> Put 20 g of pellets into a cylindrical container made of stainless steel (SUS) with an inner diameter of 20 mm, and place a weight on the surface of the pellet layer in the cylindrical container so that a pressure of 180 g per square centimeter is evenly applied. This cylindrical container was heated to a temperature of the melting point of the pellet - 15 °C and placed in an inert oven with nitrogen flowing at a flow rate of 20 liters / min for 30 minutes, then taken out and returned to room temperature (25 °C). Then, the pellets were taken out of the cylindrical container, and the fusion condition of the pellets was visually observed. The evaluation criteria were as follows, and a rank of B or above was considered qualified. Rank A: There was no fusion between the pellets at all, and no blocking occurred, which was the best state. Rank B: There were 5 - 10 small lumps, but they could be easily broken when gently prodded with a finger, and no blocking occurred. Rank C: The pellets were fused together, forming clumps of 10 or more pellets, indicating that blocking had occurred.

[0062] <Measurement of fine powder amount> 100g of pellets were sieved through a 0.71mm mesh sieve to remove fine powder, and the mass of the remaining pellets was measured. Next, the remaining pellets were placed in a stainless steel (SUS) cylindrical container with an inner diameter of 100mm and a height of 200mm, and shaken for 10 minutes at a shaking speed of 100 times / min and an amplitude of 40mm using a small shaker (product name: NR-3, manufactured by TAITEC). After that, all the contents of the cylindrical container were collected and sieved through a 0.71mm mesh sieve to separate the fine powder generated by the shaking. The mass of the obtained fine powder was measured. The amount of fine powder generated (ppm) was then calculated from the mass of the total pellets before shaking and the mass of the generated fine powder. The smaller this value, the less fine powder is generated, and the fewer problems such as clogging and variations in supply volume there will be. The evaluation criteria were as follows, and a rank of B or higher was considered acceptable. Rank A: 500 ppm or less. Rank B: Over 500 ppm and under 1000 ppm. Rank C: Over 1000 ppm.

[0063] (Example 1) [Preparation of catalyst for polycondensation] 100 parts by mass of magnesium acetate tetrahydrate were placed in a glass pear-shaped flask equipped with a stirring device, and 1500 parts by mass of anhydrous ethanol (purity 99% or higher) were added. Then, 65.3 parts by mass of ethyl acid phosphate (mixture mass ratio of monoester and diester: 45:55) was added, and the mixture was stirred at 23°C. After 15 minutes, it was confirmed that the magnesium acetate was completely dissolved, and then 122 parts by mass of tetra-n-butyl titanate was added. Stirring was continued for another 10 minutes to obtain a homogeneous mixed solution. This mixed solution was concentrated under reduced pressure using an evaporator in an oil bath at 60°C. After 1 hour, most of the ethanol had evaporated, yielding a translucent, viscous liquid. The oil bath temperature was further increased to 80°C, and the solution was further concentrated under reduced pressure of 5 Torr to obtain a viscous liquid. This liquid catalyst was dissolved in 1,4-butanediol to prepare a catalyst solution with a titanium atom content of 1.0% by mass.

[0064] [Manufacturing of pellets containing PBSSe] A slurry was prepared by continuously supplying 57.8 parts by mass of succinic acid, 12.3 parts by mass of sebacic acid, 64.4 parts by mass of 1,4-butanediol, and 0.125 parts by mass of trimethylolpropane to a slurry preparation tank, stirring, and mixing. The slurry was then continuously supplied to an esterification reaction tank, and the esterification reaction was carried out continuously at an internal temperature of 230°C and a pressure of 101 kPa to obtain a PBSSe low polymer with an esterification rate of 92%.

[0065] The obtained PBSSe low polymer was continuously supplied to the first stage polycondensation reactor, and 0.60 parts by mass of the previously prepared catalyst solution was continuously added to the PBSSe low polymer. The reaction was carried out continuously under reduced pressure of 2.0 kPa at a temperature of 240°C with an average residence time of 2 hours. Next, the resulting reaction product was continuously supplied to the second stage polycondensation reactor, and a melt polycondensation reaction was carried out under reduced pressure of 0.4 kPa at a temperature of 240°C with an average residence time of 2 hours. Subsequently, the reaction was carried out in the third stage polycondensation reactor at a temperature of 240°C and a pressure of 0.13 kPa with an average residence time of 2 hours. After that, the molten PBSSe was extruded in strand form from an outlet at the bottom of the polycondensation reactor into hot water adjusted to a temperature of 35°C, forming flat, cocoon-shaped pellets with a mass of approximately 15 mg per pellet. The pellets were then held in the hot water for 1 minute while a linear velocity was applied to the hot water. Subsequently, the pellets were recovered from the hot water and dried. Thus, pellets containing PBSSe according to Example 1 were obtained. The molar ratio of constituent units derived from succinic acid to constituent units derived from sebacic acid (constituent units derived from succinic acid / constituent units derived from sebacic acid) of the obtained pellets was 89 / 11. The intrinsic viscosity and strength ratio (I) of the obtained PBSSe-containing pellets were determined according to the method described above. 01 / I 02 The content of cyclic dimers was measured. In addition, a heat fusion test and the amount of fine powder generated were measured according to the method described above. Figure 1 shows the Raman spectrum measured from the pellet according to this embodiment, and the fitted Raman spectrum obtained by fitting with two peaks having peak tops in the first wavenumber range and the second wavenumber range. In Figure 1, P is the Raman spectrum measured from the pellet, P01 and P02 are Raman spectra obtained by curve fitting using the Lorentz function to the peaks in the first wavenumber range and the second wavenumber range, respectively, and PS is the spectrum obtained by combining the waveform related to P01 and the waveform related to P02.

[0066] (Example 2) 25 parts by mass of pellets containing PBSSe prepared in Example 1 and a mixture of 40 parts by mass of ethanol and 60 parts by mass of water were continuously supplied to a treatment tank and contacted at a temperature of 60°C for 4 hours (solvent contact step). The pellets that underwent this solvent contact step were dried under a nitrogen atmosphere at a temperature of 70°C. The pellets thus obtained were dried according to the method described above, determining their intrinsic viscosity and strength ratio (I 01 / I 02 The content of cyclic dimers was measured. In addition, a heat fusion test and the amount of fine powder generated were measured according to the method described above.

[0067] (Example 3) 25 parts by mass of pellets containing PBSSe prepared in Example 1 and a mixture of 80 parts by mass of ethanol and 20 parts by mass of water were continuously supplied to a treatment tank and contacted at a temperature of 60°C for 4 hours (solvent contact step). The pellets that underwent this solvent contact step were dried under a nitrogen atmosphere at a temperature of 70°C. The pellets thus obtained were subjected to the intrinsic viscosity and strength ratio (I) according to the method described above. 01 / I 02 The content of cyclic dimers was measured. In addition, a heat fusion test and the amount of fine powder generated were measured according to the method described above.

[0068] (Example 4) Pellets containing PBSSe were prepared in the same manner as in Example 1, except that the raw materials continuously supplied to the slurry preparation tank were changed to 50.0 parts by mass of succinic acid, 21.4 parts by mass of sebacic acid, 62.0 parts by mass of 1,4-butanediol, and 0.125 parts by mass of trimethylolpropane. The molar ratio of constituent units derived from succinic acid to constituent units derived from sebacic acid (constituent units derived from succinic acid / constituent units derived from sebacic acid) of the obtained pellets was 80 / 20. The intrinsic viscosity and strength ratio (I) of the pellets thus obtained were determined according to the method described above. 01 / I 02 The content of cyclic dimers was measured. In addition, a heat fusion test and the amount of fine powder generated were measured according to the method described above.

[0069] (Example 5) 25 parts by mass of pellets containing PBSSe prepared in Example 4 and a mixture of 40 parts by mass of ethanol and 60 parts by mass of water were continuously supplied to a processing tank and contacted at a temperature of 60°C for 4 hours (solvent contact step). The pellets that underwent this solvent contact step were dried under a nitrogen atmosphere at a temperature of 70°C. The pellets thus obtained were subjected to the method described above to determine their intrinsic viscosity and strength ratio (I 01 / I 02 The content of cyclic dimers was measured. In addition, a heat fusion test and the amount of fine powder generated were measured according to the method described above.

[0070] (Example 6) 25 parts by mass of pellets containing PBSSe prepared in Example 4 and a mixture of 80 parts by mass of ethanol and 20 parts by mass of water were continuously supplied to a treatment tank and contacted at a temperature of 60°C for 4 hours (solvent contact step). The pellets that underwent this solvent contact step were dried under a nitrogen atmosphere at a temperature of 70°C. The pellets thus obtained were subjected to the method described above to determine their intrinsic viscosity and strength ratio (I 01 / I 02 ), the content of cyclic dimers was measured. Furthermore, according to the method described above, A heat fusion test was conducted, and the amount of fine powder generated was measured.

[0071] (Example 7) 25 parts by mass of pellets containing PBSSe prepared in Example 1 and a mixture of 40 parts by mass of ethanol and 60 parts by mass of water were continuously supplied to a treatment tank and contacted at a temperature of 70°C for 4 hours (hot water contact step). The pellets that underwent this hot water contact step were dried under a nitrogen atmosphere at a temperature of 70°C. The pellets thus obtained were subjected to the method described above to determine their intrinsic viscosity and strength ratio (I 01 / I 02 The content of cyclic dimers was measured. In addition, a heat fusion test and the amount of fine powder generated were measured according to the method described above.

[0072] (Comparative Example 1) In Example 1, after polymerization of PBSSe, the molten PBSSe was extracted in strand form from an outlet at the bottom of the polycondensation reaction vessel, and the solidified strands were cut and pelletized while being water-cooled (rapidly cooled) at a temperature of 20°C. These pellets were dried in a nitrogen atmosphere at a temperature of 70°C. The intrinsic viscosity and strength ratio (I) of the pellets thus obtained were determined according to the method described above. 01 / I 02 The content of cyclic dimers was measured. In addition, a heat fusion test and the amount of fine powder generated were measured according to the method described above.

[0073] (Comparative Example 2) 25 parts by mass of pellets containing PBSSe prepared in Comparative Example 1 and a mixture of 40 parts by mass of ethanol and 60 parts by mass of water were continuously supplied to a treatment tank and contacted at a temperature of 70°C for 4 hours (hot water contact step). The pellets that underwent this hot water contact step were dried under a nitrogen atmosphere at a temperature of 70°C. The pellets thus obtained were subjected to the intrinsic viscosity and strength ratio (I) according to the method described above. 01 / I 02 The content of cyclic dimers was measured. In addition, a heat fusion test and the amount of fine powder generated were measured according to the method described above. Table 1 shows the measurement results of PBSSe pellets for Examples 1-7 and Comparative Examples 1-2.

[0074] [Table 1]

[0075] From Table 1, the intensity ratio of the Raman band (I 01 / I 02 Pellets containing PBSSe with a value of 1.7 or higher exhibit excellent blocking resistance, and also, 01 / I 02However, it can be seen that pellets containing PBSSe with a value within the range of 1.7 to 3.4 exhibit excellent blocking resistance and suppress the generation of fine powder. Furthermore, this allows for stable supply to injection molding machines and extrusion molding machines, and enables the stable production of injection molded and extruded molded products by providing pellets containing PBSSe. Thus, according to one aspect of the present invention, pellets containing PBSSe that have good blocking resistance and can be stably supplied to a molding machine can be obtained as a feed material for injection molding, extrusion molding, etc. Furthermore, biodegradable injection molded or extruded molded articles that can be manufactured more stably can be obtained. Furthermore, according to another aspect of the present invention, pellets containing PBSSe, which have excellent blocking resistance and suppress the generation of fine powder, can be obtained as a feed material for injection molding, extrusion molding, etc. Moreover, since such pellets are less prone to blocking and do not generate fine powder, they can be stably supplied to the molding machine, and contamination of the extruder and molding machine by fine powder can be prevented, thus enabling the production of biodegradable injection-molded or extruded articles that can be manufactured stably and productively.

Claims

1. A pellet containing polybutylene succinate sebacate having as its main constituent units a constituent unit derived from succinic acid, a constituent unit derived from sebacic acid, and a constituent unit derived from 1,4-butanediol, The Raman spectrum measured from the aforementioned pellets shows values ​​of 1680–1780 cm⁻¹. －１ The spectrum in the wavenumber range is 1718±5 cm⁻¹. －１ The first wavenumber range, and 1732±5 cm －１ In a Raman spectrum fitted using a Lorentz function with two peaks each having a peak top in the second wavenumber range, the intensity of the peak in the first wavenumber range I ０１ And the peak intensity I in the second wavenumber range ０２ The intensity ratio (I ０１ / I ０２ Pellets in which the ratio is 1.7 or higher.

2. The pellet according to claim 1, wherein the strength ratio is 3.4 or less.

3. The pellet according to claim 1, wherein the strength ratio is 1.9 or more.

4. The pellet according to claim 1, wherein the content of a cyclic dimer consisting of succinic acid and 1,4-butanediol in the pellet is 4,000 ppm by mass or less.

5. The pellet according to claim 1, wherein the intrinsic viscosity (IV) of the pellet is 1.2 dL / g or more and 2.2 dL / g or less.

6. The pellet according to claim 1, wherein the molar ratio of constituent units derived from succinic acid to constituent units derived from sebacic acid (constituent units derived from succinic acid / constituent units derived from sebacic acid) is 70 / 30 to 95 / 5.

7. The pellet according to claim 6, wherein the molar ratio is 80 / 20 to 90 / 10.

8. The pellet according to claim 1, wherein the total number of moles of the constituent units derived from succinic acid, the constituent units derived from sebaciic acid, and the constituent units derived from 1,4-butanediol in the polybutylene succinate sebacate is 80 mol% or more of the total number of moles of the constituent units constituting the polybutylene succinate sebacate.

9. The pellet according to claim 1, wherein the content of polybutylene succinate sebacate in the pellet is 80% by mass or more.

10. An injection-molded resin pellet article comprising at least one of the pellets described in any of claims 1 to 9.

11. An extruded resin pellet article comprising at least one of the pellets described in any of claims 1 to 9.

Images