Polyester resins, molded bodies, preforms, polyester bottles and mechanically recycled polyester resins

Abstract

Provided is a polyester resin characterized by containing a polyester containing a diol unit and a dicarboxylic acid unit as a main component, the shoulder peak-related parameter S represented by the following formula (1) derived from a differential molecular weight distribution curve of the polyester resin being more than 0.130 and 0.197 or less. (In the above formula (1), M is the molecular weight of the polyester resin, f(LogM) represents the differential molecular weight distribution curve of the polyester resin, and g(LogM) represents a first function connecting data at LogM of 3.40 and 3.75 in f(LogM).)

Description

Technical Field

[0001] This invention relates to polyester resin, molded articles made from the polyester resin, preforms, polyester bottles, and mechanically recycled polyester resin. Background Technology

[0002] Polyester resin is a thermoplastic resin with excellent properties such as mechanical stability, chemical stability, transparency, and heat resistance. From the viewpoint of reducing environmental impact, there are known methods for regenerating such polyester resin through solid-state polymerization and mechanically recycling it (e.g., Patent Document 1).

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2000-219728 Summary of the Invention

[0006] The problem the invention aims to solve

[0007] However, if the above-mentioned technology is used to repeatedly perform mechanical recycling of polyester resin, problems such as increased yellowing and deterioration of the color tone will occur.

[0008] The object of the present invention is to provide a polyester resin with excellent color tone.

[0009] Solution for solving the problem

[0010] [1] According to embodiment 1 of the present invention, a polyester resin is provided, characterized in that it comprises a polyester containing diol units and dicarboxylic acid units as the main component, wherein the polyester resin uses a shoulder peak related parameter S derived from the differential molecular weight distribution curve obtained by GPC as shown in equation (1) below, which is greater than 0.130 and less than 0.197.

[0011]

[0012] In the above formula (1), M is the molecular weight of polyester resin, f(LogM) represents the differential molecular weight distribution curve of polyester resin, and g(LogM) represents a linear function connecting the data of the two points in f(LogM) where LogM is 3.40 and 3.75.

[0013] [2] According to embodiment 2 of the present invention, the polyester resin of embodiment 1 is provided, characterized in that the polydispersity index Mw / Mn determined by GPC is 2.315 or more and less than 2.500.

[0014] [3] According to Embodiment 3 of the present invention, a polyester resin is provided, characterized in that it comprises a polyester containing diol units and dicarboxylic acid units as a main component, the polyester resin comprising a cyclic oligomer containing the diol units and the dicarboxylic acid units, wherein the ratio (C5 / CT) of the peak area of ​​the pentamer oligomer (C5) in the cyclic oligomer, as determined by liquid chromatography, is 0.068 or more and less than 0.090.

[0015] [4] According to embodiment 4 of the present invention, the polyester resin of embodiment 3 is provided, characterized in that the ratio (C6 / CT) of the peak area of ​​the hexamer oligomer (C6) in the cyclic oligomer, as determined by liquid chromatography, is 0.0482 or more and less than 0.0620.

[0016] [5] According to embodiment 5 of the present invention, a polyester resin according to embodiment 3 or 4 is provided, characterized in that the ratio (C7 / CT) of the peak area of ​​the heptameric oligomer (C7) in the cyclic oligomer, as determined by liquid chromatography, is 0.0225 or more and less than 0.0330.

[0017] [6] According to Embodiment 6 of the present invention, a polyester resin is provided, characterized in that it comprises a polyester containing diol units and dicarboxylic acid units as a main component, wherein the polyester resin is used... 1 The peak area of ​​7.43–7.55 ppm as determined by H-NMR (A 7.5 ) relative to the peak area derived from all dicarboxylic acids (A acid The ratio of (A) 7.5 / A acid () Less than 0.00060.

[0018] [7] According to embodiment 7 of the present invention, the polyester resin of embodiment 6 is provided, characterized in that it uses... 1 The peak area of ​​7.75–7.86 ppm as determined by H-NMR (A 7.8 ) relative to the peak area derived from all dicarboxylic acids (A acid The ratio of (A) 7.8 / A acid (less than 0.00030)

[0019] [8] According to embodiment 8 of the present invention, a molded body is provided, which is made of any one of the polyester resins of embodiments 1 to 7.

[0020] [9] According to embodiment 9 of the present invention, a preform is provided, which is made of polyester resin according to any one of embodiments 1 to 7.

[0021]

[10] According to embodiment 10 of the present invention, a polyester bottle is provided, which is made of any one of the polyester resins of embodiments 1 to 7.

[0022]

[11] According to embodiment 11 of the present invention, a polyester resin according to any one of embodiments 1 to 7 is provided, characterized in that the polyester resin is a mechanically recycled polyester resin.

[0023] The effects of the invention

[0024] According to the present invention, polyester resins with excellent hue can be provided. Attached Figure Description

[0025] Figure 1 This is a flowchart illustrating an example of a method for manufacturing polyester resin according to an embodiment of the present invention.

[0026] Figure 2A This is a graph showing the measurement results of the 1H-NMR spectrum in Example 1.

[0027] Figure 2B This is a graph showing the measurement results of the 1H-NMR spectrum in Comparative Example 6.

[0028] Figure 2C This indicates the original (virgin) isophthalic acid copolymer polyethylene terephthalate resin. 1 A graph showing the results of H-NMR spectral measurements.

[0029] Figure 3 (a) is a graph showing the measurement results of the differential molecular weight distribution curve in Example 1. Figure 3 (b) is Figure 3 Enlarged view of (a).

[0030] Figure 4 (a) is a graph showing the determination results of the differential molecular weight distribution curve in Comparative Example 6. Figure 4 (b) is Figure 4 Enlarged view of (a). Detailed Implementation

[0031] <<First Implementation>>

[0032] The polyester resin in the first embodiment is characterized in that it comprises a polyester containing diol units and dicarboxylic acid units as the main component, and the polyester resin is used such that the shoulder peak correlation parameter S derived from the differential molecular weight distribution curve shown in equation (1) below obtained by GPC is greater than 0.130 and less than 0.197.

[0033]

[0034] It should be noted that in the above formula (1), M is the molecular weight of polyester resin, f(LogM) represents the differential molecular weight distribution curve of polyester resin, and g(LogM) represents a linear function connecting the data of the two points where LogM is 3.40 and 3.75 in f(LogM).

[0035] The polyester contained in the polyester resin can include aromatic polyesters, fully aromatic polyesters, polycarbonate, and aliphatic polyesters, among which aromatic polyesters are preferred. Aromatic polyesters contain diol units and dicarboxylic acid units. Examples of diol compounds used to form the diol units include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, diethylene glycol, 1,6-hexanediol, cyclohexanediol, and ethylene oxide adducts of bisphenol A, among which ethylene glycol is preferred. Examples of dicarboxylic acid compounds used to form the dicarboxylic acid units include aromatic dicarboxylic acids and their derivatives such as terephthalic acid, isophthalic acid, phthalic acid, naphthalenedicarboxylic acid, and furanyl dicarboxylic acid, among which terephthalic acid is preferred. Specific examples of polyesters include polyethylene terephthalate, polyethylene terephthalate, polyethylene butylene terephthalate, polyethylene naphthalate, and polyethylene furanate, among which polyethylene terephthalate, as a copolymer of ethylene glycol and terephthalic acid, is preferred. The aforementioned polyesters are not limited to those derived from petroleum feedstocks; they can also be derived from plant-based feedstocks, and furthermore, they can be polyesters obtained by recycling these petroleum- or plant-based feedstocks. Furthermore, the aforementioned polyesters can be used alone or in combination.

[0036] The content of terephthalate units in polyethylene terephthalate is preferably 70 mol% or more, and more preferably 90 mol% or more, relative to all monomer units.

[0037] Polyethylene terephthalate may contain units composed of dicarboxylic acids other than terephthalic acid that can copolymerize with ethylene glycol and terephthalic acid in all its monomer units. Examples of dicarboxylic acids other than terephthalic acid include malonic acid, succinic acid, glutaric acid, adipic acid, octanoic acid, sebacic acid, dodecanoic acid, eicosanoic acid, pimelic acid, azelaic acid, methylmalonic acid and ethylmalonic acid, adamantane dicarboxylic acid, norbornene dicarboxylic acid, cyclohexane dicarboxylic acid, decahydronaphthalene dicarboxylic acid, isophthalic acid, phthalic acid, 1,4-naphthalene dicarboxylic acid, 1,5-naphthalene dicarboxylic acid, 2,6-naphthalene dicarboxylic acid, 1,8-naphthalene dicarboxylic acid, 4,4'-diphenyl dicarboxylic acid, 4,4'-diphenyl ether dicarboxylic acid, sodium isophthalate-5-sulfonate, phenylindanic acid, anthracene dicarboxylic acid, phenanthrene dicarboxylic acid, 9,9'-bis(4-carboxyphenyl)fluoreneic acid, 2,5-furan dicarboxylic acid and their ester derivatives, among which isophthalic acid is preferred. The content of units composed of dicarboxylic acids other than terephthalic acid is preferably 30 mol% or less, more preferably 10 mol% or less, relative to all monomer units.

[0038] Polyethylene terephthalate may contain units composed of diols other than terephthalic acid that are capable of copolymerizing with ethylene glycol and terephthalic acid in all its monomer units. Examples of such diols other than ethylene glycol include 1,2-propanediol, 1,3-propanediol, butanediol, 2-methyl-1,3-propanediol, hexanediol, neopentyl glycol, cyclohexanediethanol, cyclohexanediethanol, decahydronaphthalenediethanol, decahydronaphthalenediethanol, norbornanediethanol, norbornanediethanol, tricyclodecanediethanol, tricyclodecanediethanol, tetracyclododecanediethanol, tetracyclododecanediethanol, decahydronaphthalenediethanol, and 5-hydroxymethyl-5-ethyl-2-(1,1-dimethyl-2-hydroxyethyl)- The monomers include 1,3-dioxane, cyclohexanediol, dicyclohexyl-4,4'-diol, 2,2-bis(4-hydroxycyclohexylpropane), 2,2-bis(4-(2-hydroxyethoxy)cyclohexyl)propane, cyclopentanediol, 3-methyl-1,2-cyclopentanediol, 4-cyclopenten-1,3-diol, adamantanediol, p-xylenediol, bisphenol A, bisphenol S, styrenediol, trimethylolpropane, pentaerythritol, diethylene glycol, triethylene glycol, and bis(β-hydroxyethyl) terephthalate (BHET), among others, with diethylene glycol being preferred. The content of units composed of diols other than ethylene glycol is preferably 30 mol% or less relative to all monomer units, more preferably 10 mol% or less.

[0039] Polyethylene terephthalate may also contain other components such as additives. For example, it can be formulated with one or more of various additives such as plasticizers, light stabilizers, antioxidants, UV absorbers, flame retardants, colorants, pigments, fillers, mold release agents, antistatic agents, fragrances, foaming agents, and antibacterial / antifungal agents.

[0040] The polyester content in the polyester resin is preferably 99% by weight or more, and more preferably 99.5% by weight or more.

[0041] Although not specifically limited, the polyester resin in this embodiment may contain cyclic oligomers comprising diol units and dicarboxylic acid units. Such cyclic oligomers are byproducts of the polymerization reaction between the aforementioned diol and dicarboxylic acid compounds. The polyester resin in this embodiment contains trimer oligomers (cyclic trimers; CT) and pentamer oligomers (C5) as cyclic oligomers. For example, the trimer oligomer (CT) contained in a polyester resin containing polyethylene terephthalate as the polyester is composed of three structural units of polyethylene terephthalate.

[0042] The content of cyclic oligomers in the polyester resin is preferably 1% by weight or less, more preferably 0.5% by weight or less.

[0043] In polyester resin, the shoulder peak correlation parameter S, derived from the differential molecular weight distribution curve obtained by GPC and shown in equation (1) below, is greater than 0.130 and less than 0.197, preferably greater than 0.145 and less than 0.196.

[0044]

[0045] It should be noted that in equation (1) above, M is the molecular weight of the polyester resin, f(LogM) represents the differential molecular weight distribution curve of the polyester resin, and g(LogM) represents a linear function connecting the data points of LogM at 3.40 and 3.75 in f(LogM). Furthermore, the vertical axis of the differential molecular weight distribution curve is dw / dLogM, obtained by differentiating LogM with respect to the concentration fraction w (%). By ensuring that the shoulder peak correlation parameter S of the polyester resin in this embodiment is within the above-mentioned range, the yellow tint is suppressed, resulting in excellent color tone, and furthermore, excellent molding stability.

[0046] In polyester resins, the polydispersity index (Mw / Mn) measured using GPC is preferably 2.315 or higher and less than 2.500, more preferably 2.320 or higher and less than 2.490. By ensuring that the polydispersity index (Mw / Mn) is within the above range, the polyester resin can be made to have superior color tone and molding stability.

[0047] While not specifically limited, polyester resins may contain pentamer oligomers (C5) as cyclic oligomers. In polyester resins, the ratio (C5 / CT) of the peak area of ​​the pentamer oligomer (C5) to the peak area of ​​the trimer oligomer (CT) as determined by liquid chromatography is preferably 0.068 or higher and less than 0.090, more preferably 0.070 or higher and less than 0.088. By ensuring that the ratio (C5 / CT) of the peak area of ​​the pentamer oligomer (C5) to the peak area of ​​the trimer oligomer (CT) is within the above range, the polyester resin can be made to have superior color tone and molding stability. It should be noted that when performing the determination using liquid chromatography, a UV / Vis detector or a diode array detector (DAD) is preferably used as the detector. The same applies when determining the ratio of the peak areas of the hexamer and heptamer oligomers, which will be described later.

[0048] While not specifically limited, polyester resins may contain hexamethylene oligomers (C6) as cyclic oligomers. In the polyester resin, the ratio (C6 / CT) of the peak area of ​​the hexamethylene oligomer (C6) to the peak area of ​​the trimer oligomer (CT), as determined by liquid chromatography, is preferably 0.0482 or higher and less than 0.0620, more preferably 0.0485 or higher and less than 0.0600. By maintaining the peak area ratio (C6 / CT) within the above range, the polyester resin can be made to have superior color tone and molding stability.

[0049] While not specifically limited, polyester resins may contain heptameric oligomers (C7) as cyclic oligomers. In the polyester resin, the ratio (C7 / CT) of the peak area of ​​the heptameric oligomer (C7) to the peak area of ​​the trimer oligomer (CT) in the cyclic oligomers, as determined by liquid chromatography, is preferably 0.0225 or more and less than 0.0330, more preferably 0.0230 or more and less than 0.0320. By ensuring the peak area ratio (C7 / CT) is within the above range, the polyester resin can be made to have superior color tone and molding stability.

[0050] In polyester resin, use 1 The peak area of ​​7.43–7.55 ppm as determined by H-NMR (A 7.5 ) relative to the peak area derived from all dicarboxylic acids (A acid The ratio of (A) 7.5 / A acid Preferably less than 0.00060, more preferably less than 0.00040. It should be noted that peaks originating from dicarboxylic acids exist in the ranges of 7.60~7.75ppm, 7.90~8.55ppm, and 8.75~8.90ppm, and the peak area (A) of all dicarboxylic acids is... acid(A) refers to the total peak area present across all these ranges. This is calculated by considering the peak area (A) of 7.43–7.55 ppm. 7.5 ) relative to the peak area derived from all dicarboxylic acids (A acid The ratio of (A) 7.5 / A acid Within the above range, polyester resins can be made to have better color tone and molding stability.

[0051] In polyester resin, use 1 The peak area of ​​7.75–7.85 ppm as determined by H-NMR (A 7.8 ) relative to the peak area derived from all dicarboxylic acids (A acid The ratio of (A) 7.8 / A acid Preferably less than 0.00030, more preferably less than 0.00020. This is achieved by reducing the peak area (A) to 7.75~7.85 ppm. 7.8 ) relative to the peak area derived from all dicarboxylic acids (A acid The ratio of (A) 7.8 / A acid Within the above range, polyester resins can be made to have better color tone and molding stability.

[0052] In this embodiment, the intrinsic viscosity (IV) of the polyester resin is preferably 0.60~1.40 dL / g, more preferably 0.70~1.00 dL / g.

[0053] The color b of the polyester resin in this embodiment * The particle size of the granules after solid-phase polymerization is preferably 15.0 or less, and more preferably 10.0 or less.

[0054] In this embodiment, the cold crystallization peak temperature Tc1 of the polyester resin is preferably 149°C or higher and 162°C or lower, more preferably 149°C or higher and 153°C or lower. By setting the cold crystallization peak temperature Tc1 of the polyester resin to the lower limit or above, the polyester resin can be made to have better molding stability. However, if the cold crystallization peak temperature Tc1 of the polyester resin exceeds the upper limit, it is difficult to impart heat resistance when molding the polyester resin into polyester bottles, etc.

[0055] Figure 1 This is a flowchart illustrating an example of a method for manufacturing the polyester resin in this embodiment. For example... Figure 1 As shown, the polyester resin in this embodiment can be manufactured by performing a thermal process control treatment on the polyester containing diol units and dicarboxylic acid units, which includes a first melt extrusion step, a second melt extrusion step, a crystallization step, and a solid-state polymerization step.

[0056] First, in the first melt extrusion step, the granular polyester obtained by polymerizing the aforementioned diol compound and dicarboxylic acid is melt-extruded in a dehumidifying dryer set to 150°C until the moisture content is below 50 ppm. The molten resin is then air-cooled to produce granules. The extruder is not particularly limited; examples include single-screw extruders, twin-screw extruders, and multi-screw extruders, but a twin-screw extruder is preferred. The extrusion temperature when using a twin-screw extruder is preferably 0-60°C higher than the melting point of the polyester, particularly 260-310°C for polyethylene terephthalate, and more preferably 265-300°C. The screw speed of the twin-screw extruder is preferably 50-800 rpm, more preferably 70-400 rpm. The discharge rate of the twin-screw extruder is preferably 5-30000 kg / h, more preferably 10-10000 kg / h.

[0057] Next, in the second melt extrusion step, the granules obtained in the first melt extrusion step are melt extruded again, and the discharged molten resin is air-cooled to form granules. There are no particular limitations on the extruder; examples include single-screw extruders, twin-screw extruders, and multi-screw extruders, among which a twin-screw extruder is preferred. Furthermore, the extruder used is preferably equipped with a vacuum exhaust device capable of reducing pressure to below atmospheric pressure. In the second melt extrusion step, when using a twin-screw extruder equipped with a vacuum exhaust device, the melt extrusion conditions are preferably set to the same conditions as in the first melt extrusion step, except that the pressure is below a vacuum level of 100 Torr.

[0058] Next, in the crystallization process, the granules obtained in the second melt extrusion process are heated to crystallize the resin. The heating temperature is preferably 100-170°C, more preferably 130-150°C. Heating is preferably carried out under a pressure of 200 Torr or less, under a nitrogen gas flow, or a combination thereof. The heating time is preferably 0.5-6 hours, more preferably 2-5 hours.

[0059] Next, in the solid-state polymerization step, the crystallized granules are heated to carry out solid-state polymerization of the resin. Solid-state polymerization is preferably carried out under a pressure of 200 Torr or less, under a nitrogen gas flow, or a combination thereof. The solid-state polymerization temperature is preferably 200–230°C, more preferably 205–225°C. The heating time is preferably 2–24 hours, more preferably 6–20 hours.

[0060] As described above, the polyester resin of this embodiment can be obtained by subjecting the polyester to one or more thermal process control treatments consisting of a first melt extrusion step, a second melt extrusion step, a crystallization step, and a solid-state polymerization step. The number of thermal process control treatments is preferably 1 to 3 times, based on so-called original polyester that has never been recycled (0 times).

[0061] It should be noted that the method for manufacturing the polyester resin in this embodiment is not particularly limited to the above. For example, the polyester used as a polyester bottle or the like can be mechanically recycled to control the thermal process and obtain the polyester resin (mechanically recycled polyester resin) in this embodiment. As the polyester used in mechanical recycling, for example, polyester bottles made from virgin polyester or polyester bottles manufactured by performing one or more mechanical recycling processes can be used.

[0062] The polyester resin in this embodiment is suitable for processing into preforms and molded bodies such as polyester bottles. Preforms can be manufactured by injection molding the polyester resin. Alternatively, polyester bottles can be manufactured by stretch blow molding such preforms. Molded bodies manufactured using the polyester resin in this embodiment have excellent color.

[0063] As described above, the polyester resin in this embodiment is a material prior to processing into a molded body. Therefore, the ratio of the peak area of ​​the pentameric oligomer, hexameric oligomer, and heptamer oligomer to the peak area of ​​the trimer oligomer (CT), as determined by liquid chromatography (C5 / CT, C6 / CT, C7 / CT), is used... 1 The ratios of peak areas at 7.43–7.55 ppm and 7.75–7.85 ppm relative to the peak areas derived from all dicarboxylic acids, the shoulder peak correlation parameter S, and the polydispersity index Mw / Mn (hereinafter collectively referred to as "thermal history parameters") determined by H-NMR cannot be determined based on the state of the molded body. The molded body in Figure 1 The flowchart shown represents the state between the first melt extrusion step and the second melt extrusion step. Therefore, in order to compare the polyester resin constituting the molded body with the polyester resin in this embodiment, it is necessary to perform the second melt extrusion treatment, crystallization treatment, and solid-state polymerization treatment on the molded body, evaluate the obtained granules, and determine whether the thermal history parameters are within a specific range.

[0064] It should be noted that when the molded body undergoes a second melt extrusion treatment, crystallization treatment, and solid-state polymerization treatment, an additional thermal history control treatment is applied to the polyester resin before molding to apply a thermal history. Therefore, if the thermal history parameters evaluated after performing the second melt extrusion treatment, crystallization treatment, and solid-state polymerization treatment on a certain molded body are values ​​near the upper and lower limits of a specific range specified in this embodiment, it is preferable to evaluate whether the thermal history parameters of the polyester resin before molding are included within the specific range by the following steps.

[0065] First, the thermal history parameters of the granules obtained by performing a second melt extrusion treatment, crystallization treatment, and solid-state polymerization treatment on the molded body are recorded as thermal history parameters after one adjustment. Next, the granules undergo thermal history control treatment, and the resulting thermal history parameters are recorded as thermal history parameters after two adjustments. Then, the granules undergo multiple thermal history control treatments as needed, and the thermal history parameters after three adjustments are recorded. By obtaining the correlation between the number of adjustments and the thermal history parameters and extrapolating, the thermal history parameters equivalent to zero adjustments are obtained. By evaluating the thermal history parameters equivalent to zero adjustments, it can be confirmed whether the thermal history parameters of the polyester resin before molding are within a specific range.

[0066] <<Second Implementation Method>>

[0067] The polyester resin in the second embodiment comprises a polyester containing diol units and dicarboxylic acid units as the main component, and the ratio (C5 / CT) of the peak area of ​​the pentamer oligomer (C5) to the peak area of ​​the trimer oligomer (CT) in the cyclic oligomer, as determined by liquid chromatography, is 0.068 or more and less than 0.090.

[0068] The polyester contained in the polyester resin can be the same polyester as in the first embodiment. The polyester content in the polyester resin is preferably 99% by weight or more, more preferably 99.5% by weight or more.

[0069] The polyester resin in this embodiment comprises a cyclic oligomer containing diol units and dicarboxylic acid units. The polyester resin in this embodiment comprises a trimer oligomer (CT) and a pentamer oligomer (C5) as cyclic oligomers.

[0070] The content of cyclic oligomers in the polyester resin is preferably 1% by weight or less, more preferably 0.5% by weight or less.

[0071] In the polyester resin of this embodiment, the ratio (C5 / CT) of the peak area of ​​the pentamer oligomer (C5) to the peak area of ​​the trimer oligomer (CT) in the cyclic oligomers, as determined by liquid chromatography, is 0.068 or higher and less than 0.090, preferably 0.070 or higher and less than 0.088. By ensuring that the ratio (C5 / CT) of the peak area of ​​the pentamer oligomer (C5) to the peak area of ​​the trimer oligomer (CT) is within the above-mentioned range, the polyester resin of this embodiment exhibits suppressed yellow tones, excellent color tone, and excellent molding stability.

[0072] While not specifically limited, polyester resins may contain hexamethylene oligomers (C6) as cyclic oligomers. In the polyester resin, the ratio (C6 / CT) of the peak area of ​​the hexamethylene oligomer (C6) to the peak area of ​​the trimer oligomer (CT), as determined by liquid chromatography, is preferably 0.0482 or higher and less than 0.0620, more preferably 0.0485 or higher and less than 0.0600. By maintaining the peak area ratio (C6 / CT) within the above range, the polyester resin can be made to have superior color tone and molding stability.

[0073] While not specifically limited, polyester resins may contain heptameric oligomers (C7) as cyclic oligomers. In the polyester resin, the ratio (C7 / CT) of the peak area of ​​the heptameric oligomer (C7) to the peak area of ​​the trimer oligomer (CT) in the cyclic oligomers, as determined by liquid chromatography, is preferably 0.0225 or more and less than 0.0330, more preferably 0.0230 or more and less than 0.0320. By ensuring the peak area ratio (C7 / CT) is within the above range, the polyester resin can be made to have superior color tone and molding stability.

[0074] In polyester resin, use 1 The peak area of ​​7.43–7.55 ppm as determined by H-NMR (A 7.5 ) relative to the peak area derived from all dicarboxylic acids (A acid The ratio of (A) 7.5 / A acid Preferably less than 0.00060, more preferably less than 0.00040. This is achieved by reducing the peak area (A) to 7.43~7.55 ppm. 7.5 ) relative to the peak area derived from all dicarboxylic acids (A acid The ratio of (A) 7.5 / A acid Within the above range, polyester resins can be made to have better color tone and molding stability.

[0075] In polyester resin, use 1The peak area of ​​7.75–7.85 ppm as determined by H-NMR (A 7.8 ) relative to the peak area derived from all dicarboxylic acids (A acid The ratio of (A) 7.8 / A acid Preferably less than 0.00030, more preferably less than 0.00020. This is achieved by reducing the peak area (A) to 7.75~7.85 ppm. 7.8 ) relative to the peak area derived from all dicarboxylic acids (A acid The ratio of (A) 7.8 / A acid Within the above range, polyester resins can be made to have better color tone and molding stability.

[0076] In polyester resins, the shoulder peak correlation parameter S, derived from the differential molecular weight distribution curve obtained by GPC and shown in equation (1) above, is preferably greater than 0.130 and less than 0.197, more preferably greater than 0.145 and less than 0.196. By making the shoulder peak correlation parameter S within the above range, the polyester resin can be made to have better color tone and molding stability.

[0077] In polyester resins, the polydispersity index (Mw / Mn) measured using GPC is preferably 2.315 or higher and less than 2.500, more preferably 2.320 or higher and less than 2.490. By ensuring that the polydispersity index (Mw / Mn) is within the above range, the polyester resin can be made to have superior color tone and molding stability.

[0078] The intrinsic viscosity (IV) and color b of the polyester resin in this embodiment * The cold crystallization peak temperature Tc1 can be the same as in the first embodiment.

[0079] The polyester resin in this embodiment can be manufactured using the same method as in the first embodiment. That is, as... Figure 1 As shown, the polyester resin in this embodiment can be manufactured by subjecting the polyester containing diol units and dicarboxylic acid units to a thermal process control treatment comprising a first melt extrusion step, a second melt extrusion step, a crystallization step, and a solid-state polymerization step. Alternatively, the polyester resin can be manufactured by mechanically recycling polyester used as polyester bottles, etc.

[0080] The polyester resin in this embodiment is suitable for processing into preforms and molded bodies such as polyester bottles. Preforms can be manufactured by injection molding the polyester resin. Alternatively, polyester bottles can be manufactured by stretch blow molding such preforms. Molded bodies manufactured using the polyester resin in this embodiment have excellent color.

[0081] As described above, the polyester resin in this embodiment is a material used before the molding process, therefore the thermal history parameters cannot be determined based on the state of the molded body. The molded body in Figure 1 The flowchart shown represents the state between the first melt extrusion step and the second melt extrusion step. Therefore, in order to compare the polyester resin constituting the molded article with the polyester resin in this embodiment, the molded article needs to undergo the second melt extrusion treatment, crystallization treatment, and solid-state polymerization treatment, and the resulting granules need to be evaluated to determine whether the thermal history parameters are within a specific range. The determination of whether the thermal history parameters of the polyester resin before molding are within the specific range can be performed using the same method as in the first embodiment.

[0082] <<Third Implementation Method>>

[0083] The polyester resin in the third embodiment is characterized in that it comprises a polyester containing diol units and dicarboxylic acid units as the main component, and the use of said polyester resin... 1 The peak area of ​​7.43–7.55 ppm as determined by H-NMR (A 7.5 ) relative to the peak area derived from all dicarboxylic acids (A acid The ratio of (A) 7.5 / A acid () Less than 0.00060.

[0084] The polyester contained in the polyester resin can be the same polyester used in the first and second embodiments. The polyester content in the polyester resin is preferably 99% by weight or more, more preferably 99.5% by weight or more.

[0085] Although not specifically limited, the polyester resin in this embodiment may contain cyclic oligomers comprising diol units and dicarboxylic acid units. The content of cyclic oligomers in the polyester resin is preferably 1% by weight or less, more preferably 0.5% by weight or less.

[0086] In polyester resin, use 1 The peak area of ​​7.43–7.55 ppm as determined by H-NMR (A 7.5 ) relative to the peak area derived from all dicarboxylic acids (A acid The ratio of (A) 7.5 / A acid The peak area (A) is less than 0.00060, preferably less than 0.00040. In this embodiment, the polyester resin achieves a peak area (A) of 7.43~7.55 ppm. 7.5 ) relative to the peak area derived from all dicarboxylic acids (A acid The ratio of (A) 7.5 / A acidWithin the above range, the yellow tint is suppressed, resulting in excellent color tone. In addition, the molding stability is also excellent.

[0087] In polyester resin, use 1 The peak area of ​​7.75–7.85 ppm as determined by H-NMR (A 7.8 ) relative to the peak area derived from all dicarboxylic acids (A acid The ratio of (A) 7.8 / A acid Preferably less than 0.00030, more preferably less than 0.00020. This is achieved by reducing the peak area (A) to 7.75~7.85 ppm. 7.8 ) relative to the peak area derived from all dicarboxylic acids (A acid The ratio of (A) 7.8 / A acid Within the above range, polyester resins can be made to have better color tone and molding stability.

[0088] In the polyester resin of this embodiment, the ratio (C5 / CT) of the peak area of ​​the pentamer oligomer (C5) to the peak area of ​​the trimer oligomer (CT) in the cyclic oligomers, as determined by liquid chromatography, is preferably 0.068 or more and less than 0.090, more preferably 0.070 or more and less than 0.088. By ensuring that the ratio (C5 / CT) of the peak area of ​​the pentamer oligomer (C5) to the peak area of ​​the trimer oligomer (CT) is within the above range, the polyester resin can be made to have superior color tone and molding stability.

[0089] While not specifically limited, polyester resins may contain hexamethylene oligomers (C6) as cyclic oligomers. In the polyester resin, the ratio (C6 / CT) of the peak area of ​​the hexamethylene oligomer (C6) to the peak area of ​​the trimer oligomer (CT), as determined by liquid chromatography, is preferably 0.0482 or higher and less than 0.0620, more preferably 0.0485 or higher and less than 0.0600. By maintaining the peak area ratio (C6 / CT) within the above range, the polyester resin can be made to have superior color tone and molding stability.

[0090] While not specifically limited, polyester resins may contain heptameric oligomers (C7) as cyclic oligomers. In the polyester resin, the ratio (C7 / CT) of the peak area of ​​the heptameric oligomer (C7) to the peak area of ​​the trimer oligomer (CT) in the cyclic oligomers, as determined by liquid chromatography, is preferably 0.0225 or more and less than 0.0330, more preferably 0.0230 or more and less than 0.0320. By ensuring the peak area ratio (C7 / CT) is within the above range, the polyester resin can be made to have superior color tone and molding stability.

[0091] In polyester resins, the shoulder peak correlation parameter S, derived from the differential molecular weight distribution curve obtained by GPC and shown in equation (1) above, is preferably greater than 0.130 and less than 0.197, more preferably greater than 0.145 and less than 0.196. By making the shoulder peak correlation parameter S within the above range, the polyester resin can be made to have better color tone and molding stability.

[0092] In polyester resins, the polydispersity index (Mw / Mn) measured using GPC is preferably 2.315 or higher and less than 2.500, more preferably 2.320 or higher and less than 2.490. By ensuring that the polydispersity index (Mw / Mn) is within the above range, the polyester resin can be made to have superior color tone and molding stability.

[0093] The intrinsic viscosity (IV) and color b of the polyester resin in this embodiment * The cold crystallization peak temperature Tc1 can be the same as in the first and second embodiments.

[0094] The polyester resin in this embodiment can be manufactured using the same method as in the first and second embodiments. That is, as... Figure 1 As shown, the polyester resin in this embodiment can be manufactured by subjecting the polyester containing diol units and dicarboxylic acid units to a thermal process control treatment comprising a first melt extrusion step, a second melt extrusion step, a crystallization step, and a solid-state polymerization step. Alternatively, the polyester resin can be manufactured by mechanically recycling polyester used as polyester bottles, etc.

[0095] The polyester resin in this embodiment is suitable for processing into preforms and molded bodies such as polyester bottles. Preforms can be manufactured by injection molding the polyester resin. Alternatively, polyester bottles can be manufactured by stretch blow molding such preforms. Molded bodies manufactured using the polyester resin in this embodiment have excellent color.

[0096] As described above, the polyester resin in this embodiment is a material used before the molding process, therefore the thermal history parameters cannot be determined based on the state of the molded body. The molded body in Figure 1 The flowchart shown represents the state between the first melt extrusion step and the second melt extrusion step. Therefore, in order to compare the polyester resin constituting the molded article with the polyester resin in this embodiment, the molded article needs to undergo the second melt extrusion treatment, crystallization treatment, and solid-state polymerization treatment, and the resulting granules need to be evaluated to determine whether the thermal history parameters are within a specific range. The determination of whether the thermal history parameters of the polyester resin before molding are within the specific range can be performed using the same method as in the first and second embodiments.

[0097] Example

[0098] Next, specific examples will be given to illustrate the present invention, but the present invention is not limited thereto.

[0099] <Example 1>

[0100] [Preparation of PET resin granules and preforms]

[0101] Prepare 30 kg of granules of ethylene terephthalate copolymer resin (manufactured by Shinko Synthetic Fiber Co., Ltd., 1.8 mol% isophthalic acid copolymerization, IV=0.83) and dry it using a hopper dryer at 150°C for 5 hours. Next, feed the granules into a twin-screw extruder (manufactured by Toshiba Machine Co., Ltd., TEM26SS) and melt extrude at an extrusion temperature of 290°C, a screw speed of 100 rpm, and a discharge rate of 10 kg / h. The molten resin discharged from the extruder in a filament is conveyed by a belt conveyor while being air-cooled, and then granulated using a granulator (first melt extrusion process). Then, feed the granules back into the twin-screw extruder and melt extrude them under the same conditions as above, except that a vacuum vent (9 Torr), to obtain granules (second melt extrusion process).

[0102] 15 kg of the obtained granules were crystallized by heating them at 150°C and 1 Torr for 5 hours using a stirred vacuum dryer (Dalton, 45 MV). Then, the crystallized granules were subjected to solid-state polymerization by heating them at 225°C and 1 Torr for 13 hours using the same stirred vacuum dryer to obtain PET resin granules. During both the crystallization and solid-state polymerization processes, the stirring blades of the stirred vacuum dryer were set to a speed of 20 rpm. A portion of the obtained PET resin granules was fed into an injection molding machine, with the barrel and hot runner temperatures set to 300°C, the mold temperature set to 15°C, and the molding cycle set to 32 seconds, to produce 25 g preforms for 500 mL bottles. The PET resin granules and bottle preforms were evaluated according to the following steps. The results are shown in Table 2.

[0103] [Cyclic oligomer content]

[0104] Weigh 0.2 g of PET resin granules and bottle preforms, and add 1 mL of a mixed solvent of 1,1,1,3,3,3-hexafluoro-2-propanol and chloroform (weight ratio 1 / 1) to completely dissolve them. Add 4 mL of chloroform to the solution, then slowly add 5 mL of acetonitrile, and let stand for 3 hours to allow the PET polymer to precipitate. Take 1 mL of the supernatant from this suspension, filter it through a 0.20 μm membrane filter, and analyze the filtrate using high-performance liquid chromatography (HPLC). An Agilent Technologies 1200 series detector was used as the analytical apparatus. The analytical conditions were as follows: an Agilent Technologies 1290 Infinity diode array detector (G4212A) was used as the detector, with the detection wavelength set to 254 nm and the reference wavelength set to 500 nm. An Agilent Technologies ZORBAX Eclipse Plus C18 column (Rapid Resolution HD 2.1 × 150 mm 1.8 Micron) was used, with the column temperature set to 40 °C. Furthermore, for the mobile phase, a 0.05% by weight aqueous phosphoric acid solution was used as solution I, and acetonitrile was used as solution II. The flow rate was set to 0.6 mL / min, and the flow was carried out under the gradient conditions shown in Table 1 below. Additionally, the injection volume was set to 2 μL. Regarding the cyclic oligomers in the granules, the peak areas of the trimers and the pentamers to heptamers (CT, C5, C6, C7) were calculated, and the C5 / CT, C6 / CT, and C7 / CT ratios were determined.

[0105] [Table 1]

[0106]

[0107] [NMR process-related peaks]

[0108] PET resin granules were dissolved in a mixed solvent of deuterated trifluoroacetic acid and deuterated chloroform (8 / 2 volume ratio), and the NMR was determined using an NMR apparatus (JEOL, 400SS). 1 From the H-NMR spectra, the peak areas originating from all dicarboxylic acids were determined (A1, A2, A3, A4, and A5). acid The area of ​​peak 1 related to the NMR process (A) 7.5 The area of ​​peak 2 related to the NMR process (A) 7.8 ), calculate A 7.5 / A acid and A 7.8 / A acidHere, the peaks derived from all dicarboxylic acids refer to the total peak area in the ranges of 7.60–7.75 ppm, 7.90–8.55 ppm, and 8.75–8.90 ppm. NMR history-related peak 1 refers to the peak area in the range of 7.43–7.55 ppm, and NMR history-related peak 2 refers to the peak area in the range of 7.75–7.85 ppm. Figure 2A This refers to the example in Example 1. 1 A graph showing the results of H-NMR spectral measurements. Figure 2B This indicates that in comparison example 6 1 The graph shows the results of the H-NMR spectrum determination. Additionally, for reference, the same determination was performed on the original isophthalic acid copolymer polyethylene terephthalate resin without thermal history control treatment. 1 H-NMR spectrum. Figure 2C This refers to the original isophthalic acid copolymer polyethylene terephthalate resin. 1 A graph showing the results of H-NMR spectral measurements.

[0109] [Polydispersity index (Mw / Mn) and shoulder correlation parameter S]

[0110] Differential molecular weight distribution curves were determined using a high-efficiency GPC apparatus (Tosoh, HLC-8320GPC) to calculate the polydispersity index (Mw / Mn). As a sample, a solution was prepared by dissolving PET resin granules in a mixture of 1,1,1,3,3,3-hexafluoro-2-propanol and chloroform (volume ratio 1 / 49). Chloroform was used as the mobile phase, and a TSKgel SuperMultipore HZ-M column manufactured by Tosoh Corporation was used. The measurement temperature was set to 40°C. Standard polystyrene (Tosoh, PStQuickMP-M) was used as the molecular weight standard. Furthermore, the shoulder-peak correlation parameter S shown in equation (1) above was determined from the differential molecular weight distribution curve. The vertical axis of the differential molecular weight distribution curve is dw / dLogM, obtained by differentiating the concentration fraction w (%) by LogM. Figure 3 (a) is a graph showing the measurement results of the differential molecular weight distribution curve in Example 1. Figure 3 (b) is Figure 3 An enlarged view of (a). Additionally, Figure 4 (a) is a graph showing the determination results of the differential molecular weight distribution curve in Comparative Example 6. Figure 4 (b) is Figure 4 Enlarged view of (a).

[0111] [b * value]

[0112] The b-values ​​of PET resin granules and preforms were measured using an SM color computer (manufactured by Suga Test Instruments Co., Ltd.). * Value. b * The smaller the value, the better the hue.

[0113] [Cold crystallization peak temperature Tc1]

[0114] Five mg of PET resin granules were used as a sample, and the cold crystallization peak temperature Tc1 was determined using a differential scanning calorimeter (PerkinElmer, Diamond DSC). A higher cold crystallization peak temperature indicates better molding stability of the PET resin granules. The measurement conditions were set as described below.

[0115] Step 1: Keep at 20℃ for 5 minutes

[0116] Step 2: Increase the temperature from 20℃ to 290℃ at a rate of 10℃ / minute.

[0117] Step 3: Keep at 290℃ for 5 minutes

[0118] Step 4: Cool from 290℃ to 20℃ at a rate of 300℃ / minute.

[0119] Step 5: Keep at 20°C for 10 minutes

[0120] Step 6: Increase the temperature from 20°C to 290°C at a rate of 10°C / minute.

[0121] Tc1 is determined from the peak temperature (°C) of the cold crystallization peak in step 6.

[0122] [Intrinsic Viscosity Recovery ΔIV]

[0123] PET resin granules were fed into a twin-screw extruder (Toshiba Machine Co., Ltd., TEM26SS) and melt-extruded at an extrusion temperature of 290°C, a screw speed of 100 rpm, and a discharge rate of 10 kg / h. The molten resin discharged from the extruder in a filament was conveyed by a belt conveyor while being air-cooled and granulated using a granulator. This granule was then fed back into the twin-screw extruder and melt-extruded under the same conditions as above, except that a vacuum exhaust port (9 Torr) was used, yielding granule A. Granule A was vacuum-dried at 120°C for 2 hours, and 0.3 g was weighed and added to a mixed solvent of 1,1,2,2-tetrachloroethane and phenol (weight ratio 1 / 1) to adjust the concentration to 1.00 g / dL. The solution was stirred at 120°C for 20 minutes until completely dissolved. The dissolved solution was cooled to room temperature, and the relative viscosity was determined using a relative viscometer (Malvern Panalytical, Viscotec Y501C) set to 30°C. The intrinsic viscosity A of granule A was then determined.

[0124] Next, for the aforementioned granules A, crystallization was performed by heating at 1 Torr and 150°C for 5 hours using a stirred vacuum dryer (Dalton, 45MV). Then, using the same stirred vacuum dryer, the crystallized granules were heated at 1 Torr and 225°C for 13 hours for solid-state polymerization to obtain granules B. For granules B, the relative viscosity was calculated using the same steps as for granules A, determining the intrinsic viscosity B. Using intrinsic viscosity A and intrinsic viscosity B, the intrinsic viscosity recovery ΔIV [dL / g] was calculated based on the following formula. A higher intrinsic viscosity recovery ΔIV indicates a higher solid-state polymerization efficiency for recycling and reusing molded products obtained from PET resin granules, and a more suitable PET resin granule for recycling.

[0125] Intrinsic viscosity recovery ΔIV = Intrinsic viscosity B - Intrinsic viscosity A

[0126] It should be noted that granule A is obtained by performing a first melt extrusion process and a second melt extrusion process on PET resin granules. Therefore, granule A is equivalent to granules manufactured by recycling and extruding molded products obtained from PET resin granules (after the first melt extrusion process) (after the second melt extrusion process). On the other hand, granule B is granules obtained by crystallizing and solid-state polymerization of granule A. Therefore, it is equivalent to granules obtained by mechanically recycling molded products obtained from PET resin granules.

[0127] <Example 2>

[0128] The PET resin granules of Example 1 were subjected to a first melt extrusion treatment, a second melt extrusion treatment, a crystallization treatment, and a solid-state polymerization treatment, respectively, and the PET resin granules were obtained in the same manner as in Example 1, and were evaluated in the same manner. That is, the PET resin granules of Example 2 were obtained by subjecting the original granules to a total of two thermal process control treatments.

[0129] <Example 3>

[0130] The number of thermal process control treatments on the granules was set to a total of three times. Otherwise, PET resin granules were obtained in the same manner as in Example 1 and evaluated in the same manner.

[0131] <Comparative Examples 1-7>

[0132] The number of thermal process control treatments on the granules was set to a total of 4 to 10 times. Otherwise, PET resin granules were obtained in the same manner as in Example 1, and were evaluated in the same manner. In Comparative Examples 2 and 7, the obtained PET resin granules were used to further manufacture preforms, and the preforms were evaluated in the same manner as in Example 1.

[0133] <Reference Example>

[0134] The granules of isophthalic acid copolymer polyethylene terephthalate resin that have never undergone thermal process control treatment were evaluated in the same manner as in Example 1. Furthermore, preforms obtained using granules that have not undergone thermal process control treatment were evaluated in the same manner as in Example 1.

[0135] [Table 2]

[0136]

[0137] As shown in Table 2, the PET resin granules of Examples 1-3 and the preforms obtained by molding them with the shoulder peak related parameter S exceeding 0.130 and below 0.197 have the following properties: * The low Tc1 value suppresses the yellow tint and results in an excellent color tone. Furthermore, the PET resin granules and preforms of Examples 1-3 have high Tc1 values, thus exhibiting excellent molding stability. On the other hand, the PET resin granules of Comparative Examples 1-7, with a shoulder peak correlation parameter S of 0.130 or less, and the preforms obtained by molding them, exhibit poor color tone and molding stability.

[0138] Furthermore, the PET resin granules of Examples 1-3, whose peak area ratio (C5 / CT) of the pentamer oligomer (C5) to the peak area of ​​the trimer oligomer (CT) in the cyclic oligomers, as determined by liquid chromatography, is 0.068 or higher and less than 0.090, and the preforms obtained by molding them, are also included. *With a low C5 / CT value, the yellow tint is suppressed, resulting in an excellent color tone. On the other hand, the PET resin granules of Comparative Examples 1 to 7, with a C5 / CT value of 0.090 or higher, and the preforms obtained by molding them, exhibit poor color tone and molding stability.

[0139] Additionally, using 1 The peak area of ​​7.43–7.55 ppm as determined by H-NMR (A 7.5 ) relative to the peak area derived from all dicarboxylic acids (A acid The ratio of (A) 7.5 / A acid The PET resin granules of Examples 1-3 with a value less than 0.00060 and the preforms obtained by molding them therefrom * With a low value, the yellow tint is suppressed, resulting in an excellent color tone. On the other hand, A 7.5 / A acid The PET resin granules of Comparative Examples 1 to 7 with a value of 0.00060 or higher, and the preforms obtained by molding them, have poor color tone and molding stability.

Claims

1. A polyester resin, characterized in that, It contains polyesters with diol and dicarboxylic acid units as the main component. The polyester resin used is derived from the differential molecular weight distribution curve obtained by GPC, and the shoulder peak correlation parameter S shown in equation (1) below exceeds 0.130 and is less than 0.

197. In equation (1), M is the molecular weight of polyester resin, f(LogM) represents the differential molecular weight distribution curve of polyester resin, and g(LogM) represents a linear function connecting the data of the two points where LogM is 3.40 and 3.75 in f(LogM).

2. The polyester resin according to claim 1, characterized in that, The polydispersity index Mw / Mn, as determined by GPC, is greater than 2.315 and less than 2.

500.

3. A polyester resin, characterized in that, It contains polyesters with diol and dicarboxylic acid units as the main component. The polyester resin comprises a cyclic oligomer containing the diol unit and the dicarboxylic acid unit. The ratio of the peak area of ​​the pentamer C5 to the peak area of ​​the trimer C5 in the cyclic oligomers, as determined by liquid chromatography, i.e., C5 / CT, is greater than 0.068 and less than 0.

090.

4. The polyester resin according to claim 3, characterized in that, The ratio of the peak area of ​​the hexamer C6 to the peak area of ​​the trimer CT in the cyclic oligomers, as determined by liquid chromatography, i.e., C6 / CT, is greater than 0.0482 and less than 0.0620.

5. The polyester resin according to claim 3 or 4, characterized in that, The ratio of the peak area of ​​the heptameric oligomer C7 to the peak area of ​​the trimer oligomer CT, as determined by liquid chromatography, i.e., C7 / CT, is greater than 0.0225 and less than 0.0330.

6. A polyester resin, characterized in that, It contains polyesters with diol and dicarboxylic acid units as the main component. The use of the polyester resin 1 The peak area A at 7.43–7.55 ppm as determined by H-NMR 7.5 Relative to the peak area A derived from all dicarboxylic acids acid The ratio is A 7.5 / A acid Less than 0.00060.

7. The polyester resin according to claim 6, characterized in that, use 1 The peak area A at 7.75–7.86 ppm as determined by H-NMR 7.8 Relative to the peak area A derived from all dicarboxylic acids acid The ratio is A 7.8 / A acid Less than 0.00030.

8. A molded article made of any one of the polyester resins claimed in claims 1 to 7.

9. A preform made of the polyester resin according to any one of claims 1 to 7.

10. A polyester bottle made of any one of claims 1 to 7.

11. The polyester resin according to any one of claims 1 to 7, characterized in that, The polyester resin is a mechanically recycled polyester resin.

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