Method for producing polyester resin molded product, and masterbatch

Abstract

Provided is a masterbatch of a polyester resin molded product, the masterbatch enabling a polyester resin having high quality and high productivity to be provided even if a recycled polyester resin is used. This masterbatch for facilitating solid-phase polymerization of a polyester resin contains a polyester resin (A) and an ester polycondensation catalyst (B). The polyester resin (A) is a resin that contains a specified quantity of a structural unit derived from ethylene glycol or the like and a structural unit derived from terephthalic acid or an ester-forming derivative thereof relative to 100 mol% of structural units derived from polyhydric alcohols. The ester polycondensation catalyst (B) is contained at a quantity of 5-60 mass%. A sheet having a thickness of 1 mm and formed from a product obtained by kneading polyester resin (A) / PET resin at a mass ratio of 1 / 1 at 280ºC has a haze value of 20% or less. A phosphorus-based catalyst or the like is used as the ester polycondensation catalyst (B).

Description

Method for producing polyester resin molded body and masterbatch

[0001] The present invention relates to a method for producing a polyester resin molded article, and also to a masterbatch having viscosity increasing properties for a polyester resin used in producing the polyester resin molded article.

[0002] Due to their excellent heat resistance and strength, polyester resins are used in a wide range of fields, including synthetic fibers, films, PET bottles, machine parts, automobile parts, containers, and electronic materials. There is a demand in the market for polyester resins with better physical properties, including recycled polyester resins, and various proposals have been made.

[0003] Patent Document 1 discloses a masterbatch method for producing polyester resins by reacting a linear saturated polyester, a binder masterbatch, and a catalyst masterbatch in specific ratios to increase the melt viscosity, thereby controlling the melt flow rate to a specific value or less and increasing the swell within a specific range. Patent Document 2 proposes a modifier for crystalline polyester resins, which includes an amorphous polyester resin (I) and a reactive compound (II) containing two or more glycidyl groups and / or isocyanate groups per molecule and having a weight-average molecular weight of 200 to 500,000. Patent Document 3 discloses a method for obtaining a PET resin layer having a crystalline portion of less than 15% and an amorphous portion of 85% or more through a specific production process by adding a chain extender to a PET resin having an intrinsic viscosity within a specific range. Patent Document 4 discloses a method in which used PET material from bottle collections is extruded into a twin-screw extruder under heating together with a sterically hindered hydroxyphenyl alkyl phosphonic acid ester or monoester, the extrudate is formed into granules, and the granules are then solid-state condensed in a tumble dryer under vacuum. This method significantly increases the intrinsic viscosity after solid-state polymerization. Patent Document 5 discloses a method in which polyethylene terephthalate (A) obtained by mixing terephthalic acid, isophthalic acid, and ethylene glycol, esterifying the mixture, and then polycondensing the resulting polyethylene terephthalate with trimethylolpropane (a polymerization accelerator) to obtain a polymerization accelerator-containing masterbatch. This masterbatch is then added to the polyethylene terephthalate (A) to obtain chip-like granules of modified polyethylene terephthalate containing 0.1 wt % of the polymerization accelerator, which is then solid-state polymerized for 11 hours to obtain a bottle.

[0004] International Publication No. 01 / 094443 JP 2006-45477 A JP 2012-66506 A International Publication No. 96 / 11978 JP 2005-2170 A

[0005] In Patent Document 4, an increase in molecular weight can be confirmed after solid-state polymerization of recycled PET resin. However, after extensive research, the present inventors found that there are problems with the viscosity reduction of recycled PET resin before solid-state polymerization, and there are also problems with productivity due to contamination of the equipment.

[0006] Addressing the problem of plastic waste has become a global issue, and highly productive technologies are desperately needed to further promote recycling. Furthermore, even for recycled products, there is a demand for polyester resin molded articles of excellent quality that satisfy moldability and color. In Example 1 of Patent Document 5, 7.4 ppm of acetaldehyde was detected. Because polyethylene terephthalate is used for beverage bottles and the like, there is a demand for high-quality polyester resin molded articles that can reduce the acetaldehyde content.

[0007] Although the above has been described with respect to the problems involved in recycling polyester resins, similar problems can arise in general for polyester resins whose physical properties are to be improved.

[0008] The present invention has been made in view of the above-mentioned problems, and aims to provide a method for producing polyester resin molded articles that can provide high-quality polyester resin molded articles with high productivity, even when recycled polyester resin is used, and a masterbatch of polyester resin to be used in the production method.

[0009] The present inventors have conducted extensive research and found that the problems of the present invention can be solved by the following aspect, leading to the completion of the present invention. [1]: A masterbatch for promoting solid-state polymerization of a polyester resin, comprising a polyester resin (A) and an ester polycondensation catalyst (B), wherein the polyester resin (A) is a resin containing 50 mol % or more of structural units derived from ethylene glycol and / or diethylene glycol relative to 100 mol % of structural units derived from a polyhydric alcohol, and containing structural units derived from terephthalic acid or an ester-forming derivative thereof and / or isophthalic acid or an ester-forming derivative thereof, wherein 5 to 60 mass % of the ester polycondensation catalyst (B) is contained in 100 mass % of the nonvolatile content of the masterbatch, and wherein a 1 mm-thick sheet formed from a 280°C kneaded mixture of the polyester resin (A) and polyethylene terephthalate resin in a 1 / 1 mass ratio has a haze of 20% or less, and wherein the ester polycondensation catalyst (B) is at least one selected from a phosphorus-based catalyst, a titanium-based catalyst, and an antimony-based catalyst. [2]: The masterbatch according to [1], wherein the ester polycondensation catalyst (B) is an acid catalyst and has an aromatic ring skeleton and / or an alicyclic skeleton, and wherein at least 1 part by mass of the ester polycondensation catalyst (B) is dissolved in 100 parts by mass of the polyester resin (A) at 250° C. [3]: The masterbatch according to [1] or [2], wherein the ester polycondensation catalyst (B) is selected from alkylphosphonic acid esters and alkylphosphonic acid monoesters. [4]: The masterbatch according to any one of [1] to [3], wherein the ester polycondensation catalyst (B) is a sterically hindered hydroxyphenyl alkyl phosphonic acid ester or a sterically hindered hydroxyphenyl alkyl phosphonic acid monoester. [5]: The masterbatch according to any one of [1] to [4], wherein the masterbatch is diluted with polyester resin (A) so that the ester polycondensation catalyst (B) is 1 part by mass per 100 parts by mass of polyester resin (A), and the molecular weight dispersity of the mixture obtained by solid-state polymerization of the mixture at 220°C for 10 hours is α, and the molecular weight dispersity is β, wherein β / α is 1.00 to 1.20.[6]: A method for producing a masterbatch comprising a polyester resin (A) and an ester polycondensation catalyst (B); a mixing step of adding at least the masterbatch to a polyester resin (C) to be modified and mixing the resulting mixture; and a molding step of solid-state polymerizing the resulting mixture simultaneously with or after the mixing step, and molding the resulting mixture after the solid-state polymerizing step; wherein the polyester resin (A) is a resin containing 50 mol % or more of structural units derived from ethylene glycol and / or diethylene glycol relative to 100 mol % of structural units derived from a polyhydric alcohol, and containing structural units derived from terephthalic acid or an ester-forming derivative thereof and / or isophthalic acid or an ester-forming derivative thereof; wherein the masterbatch contains 5 to 60 mass % of an ester polycondensation catalyst (B) relative to 100 mass % of nonvolatile content; and wherein a 1 mm thick sheet formed from a 280°C kneaded mixture of polyester resin (A) / polyethylene terephthalate resin in a mass ratio of 1 / 1 has a haze of 20% or less. A method for producing a polyester resin molded article, wherein the ester polycondensation catalyst (B) is at least one selected from the group consisting of phosphorus-based catalysts, titanium-based catalysts, and antimony-based catalysts. [7]: A method for producing a polyester resin molded article according to [6], wherein the ester polycondensation catalyst (B) is selected from an alkylphosphonic acid ester or an alkylphosphonic acid monoester. [8]: A method for producing a polyester resin molded article according to [6] or [7], wherein the ester polycondensation catalyst (B) is a sterically hindered hydroxyphenyl alkylphosphonic acid ester or a sterically hindered hydroxyphenyl alkylphosphonic acid monoester.

[0010] According to the present invention, there is provided an excellent effect of providing a method for producing a polyester resin molded body that can provide a polyester resin molded body of high quality and with high productivity, even when recycled polyester resin is used, and a masterbatch of a polyester resin to be used in the production method.

[0011] An example of an embodiment to which the present disclosure is applied will be described below. However, the present disclosure is not limited to this embodiment, and other embodiments may also fall within the scope of the present disclosure as long as they conform to the spirit of the present disclosure. Furthermore, the numerical values ​​"A to B" specified in this specification refer to a range that satisfies numerical value A and a value greater than numerical value A, and numerical value B and a value smaller than numerical value B. Note that the numerical values ​​specified in this specification are values ​​obtained by the methods disclosed in the embodiments or examples. Furthermore, the term "sheet" in this specification is synonymous with "film" or "plate." Unless otherwise noted, the various components appearing in this specification may be used independently, either singly or in combination of two or more types.

[0012] 1. Polyester Resin Molded Body The polyester resin molded body according to this embodiment (hereinafter also referred to as the present molded body) is obtained by adding at least a masterbatch for promoting solid-state polymerization (described below) (hereinafter also referred to as the present masterbatch) to the polyester resin (C) to be modified, and then subjecting the mixture to a polymerization and molding process using solid-state polymerization. The present molded body can be any molded product molded according to the intended use, and examples include films, sheets, plates, net-like bodies, containers, cylindrical bodies, filaments, and fibers such as nonwoven fabrics and woven fabrics. The surface of the molded body may be smooth, uneven, or have a complex shape. The present masterbatch is a resin composition in which an ester polycondensation catalyst (B) for polycondensation is dispersed at a high concentration. The present masterbatch is mixed with the polyester resin (C) as the main component at a specified ratio to modify the polyester resin (C).

[0013] Polyester resin products are molded using various molding methods, including uniaxial molding and biaxial molding. However, recycled polyester resin has inferior physical properties compared to virgin polyester resin, which significantly reduces productivity. Furthermore, the reduced quality of recycled polyester resin limits its range of use.

[0014] On the other hand, according to the present invention, even when a recycled polyester resin is used as the polyester resin (C) to be modified, a high-quality polyester resin molded product can be obtained with high productivity. The main reason for this is the use of the masterbatch of the present disclosure. Each component will be described in detail below.

[0015] 1-1. Polyester Resin (C) The polyester resin (C) is the resin that is the main component of the present molded body and is the resin to be modified. The polyester resin (C) may be amorphous or crystalline. The polyester resin (C) may also be linear or branched. In this specification, the term "main component" refers to a component that accounts for 70% by mass or more of 100% by mass of the nonvolatile content of the composition, preferably 80% by mass or more, more preferably 90% by mass or more, and even more preferably 95% by mass or more. The polyester resin (C) may be one type or a mixture of two or more types.

[0016] Typical examples of the polyester resin (C) include polyester resins derived from polyhydric alcohols such as diols and polycarboxylic acids such as dicarboxylic acids or ester-forming derivatives thereof, polyester resins derived from polyhydric alcohols such as diols and polyhydroxycarboxylic acids such as hydroxycarboxylic acids or ester-forming derivatives thereof, and mixtures thereof.

[0017] The ester-forming derivatives of polycarboxylic acids include lower alkyl esters and acid halides of dicarboxylic acids. Examples of lower alkyl esters of dicarboxylic acids include methyl esters, ethyl esters, hydroxyethyl esters, and hydroxybutyl esters. Specific examples of dicarboxylic acid halides include acid chlorides, acid bromides, and acid iodides. Furthermore, polyhydric alcohols are alcohols having two or more hydroxyl groups in the molecule, and examples thereof include alcohols having a structure in which one hydroxyl group is substituted on each of two or more carbon atoms of a chain aliphatic hydrocarbon, a cyclic aliphatic hydrocarbon, an aromatic hydrocarbon, or a hydrocarbon compound formed by combining these.

[0018] Examples of the diol component include various diols, such as aliphatic diols such as ethylene glycol, diethylene glycol, propanediol, butanediol, 2-methyl-1,3-propanediol, neopentyl glycol, and hexanediol, saturated alicyclic primary diols such as 1,4-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, decahydronaphthalenedimethanol, decahydronaphthalenediethanol, norbornanedimethanol, norbornanediethanol, tricyclodecanedimethanol, tricyclodecaneethanol, tetracyclododecanedimethanol, tetracyclododecanediethanol, decalindimethanol, and decalindiethanol, and 2,6-dihydroxy-9-oxabicyclo[3,3,1]nonane, 3,9-bis(2-hydroxy-1,1-dimethylethyl)-2,4,8,10-tetraoxaspiro[5, Examples include saturated heterocyclic primary diols containing cyclic ethers such as 5-undecane (spiroglycol), 5-methylol-5-ethyl-2-(1,1-dimethyl-2-hydroxyethyl)-1,3-dioxane, and isosorbide; alicyclic diols such as cyclohexanediol, bicyclohexyl-4,4'-diol, 2,2-bis(4-hydroxycyclohexylpropane), 2,2-bis(4-(2-hydroxyethoxy)cyclohexyl)propane, cyclopentanediol, 3-methyl-1,2-cyclopentadiol, 4-cyclopentene-1,3-diol, and adamantanediol; and aromatic diols such as bisphenol A, bisphenol S, styrene glycol, 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene, and 9,9'-bis(4-hydroxyphenyl)fluorene. Examples of tri- or higher functional polyhydric alcohols include glycerin, trimethylolpropane, and pentaerythritol.

[0019] Examples of the dicarboxylic acid or its ester-forming derivative include aliphatic dicarboxylic acids such as adipic acid, sebacic acid, azelaic acid, dodecanedicarboxylic acid, glutaric acid, and succinic acid; aromatic dicarboxylic acids such as terephthalic acid, naphthalenedicarboxylic acid, and isophthalic acid; alicyclic dicarboxylic acids such as 1,4-cyclohexanedicarboxylic acid; and ester-forming derivatives thereof. Examples of trifunctional or higher polyvalent carboxylic acids include trimellitic acid, trimesic acid, pyromellitic acid, trimellitic anhydride, phthalic anhydride, p-hydroxybenzoic acid, and trimellitic acid monopotassium salt.

[0020] Examples of the hydroxycarboxylic acid include lactic acid, hydroxybutyric acid, and polycaprolactone.

[0021] Specific examples of the polyester resin (C) include polyethylene terephthalate (PET), polyethylene (terephthalate / isophthalate) (I-PET), glycol-modified polyethylene terephthalate (PET-G), polybutylene terephthalate (PBT), polylactic acid (PLA), polyglycolic acid (PGA), polyethylene adipate (PEA), polyhydroxyalkanoate (PHA), polytrimethylene terephthalate (PTT), polyethylene naphthalate (PEN), polybutylene naphthalate (PBN), polybutylene adipate terephthalate (PBAT), polybutylene succinate (PBS), and polylactic acid (PLA). Polyethylene terephthalate (PET) is preferred because of its excellent transparency and ease of molding processability.

[0022] The polyester resin (C) may be a virgin polyester resin or a recycled polyester resin. According to this production method, the polyester resin (C) can be modified to have a high molecular weight and a uniformly increased melt viscosity. Therefore, this method is particularly suitable for recycled polyester resins with reduced molecular weight. Furthermore, this method is suitable for modifying polyester resins according to needs, regardless of the type of polyester resin. From the viewpoint of obtaining a higher quality polyester resin molded product, the polyester resin (C) is preferably a linear polyester resin.

[0023] The intrinsic viscosity (IV) of the polyester resin (C) is not particularly limited, but the lower the intrinsic viscosity (IV), the longer the polymerization time must be set. Considering the cost based on the production time, the resin preferably has an intrinsic viscosity of 0.4 dL / g or more, more preferably 0.6 dL / g or more, and even more preferably 0.7 dL / g or more. There is no upper limit, but from the viewpoint of improving the properties of the polyester resin (C), 1.2 dL / g or less is preferred. In this specification, the intrinsic viscosity and melt viscosity refer to values ​​determined from the examples described below.

[0024] The amount of the masterbatch for promoting solid-state polymerization of the present disclosure added to the polyester resin (C) is not particularly limited and can be appropriately designed depending on the application. For example, the amount is preferably 0.2 to 20 parts by mass, more preferably 0.5 to 15 parts by mass, and even more preferably 1 to 10 parts by mass, per 100 parts by mass of the polyester resin (C).

[0025] A polyester resin molded article can be obtained from a mixture of only polyester resin (C) and the masterbatch. Alternatively, a polyester resin molded article can be obtained from a mixture of polyester resin (C), the masterbatch, and any other optional components. Examples of optional additives include resins other than polyester resin (C) and the masterbatch, catalysts, chain extenders, antioxidants, antistatic agents, surfactants, flame retardants, UV absorbers, fillers, and lubricants, provided they do not deviate from the spirit of the present disclosure.

[0026] 2. Masterbatch The masterbatch of the present disclosure is a masterbatch for promoting solid-state polymerization of a polyester resin. The masterbatch contains a polyester resin (A) and an ester polycondensation catalyst (B). From the viewpoint of obtaining a higher quality polyester resin molded product, the masterbatch preferably contains 50% by mass or more of the polyester resin (A) and the ester polycondensation catalyst (B) per 100% by mass of the masterbatch, more preferably 60% by mass or more, and even more preferably 70% by mass or more. The masterbatch may contain 100% by mass of the polyester resin (A) and the ester polycondensation catalyst (B). The ester polycondensation catalyst (B) is a catalyst for promoting solid-state polymerization of the polyester resin (C).

[0027] The polyester resin (A) contains 50 mol% or more of structural units derived from ethylene glycol and / or diethylene glycol per 100 mol% of structural units derived from a polyhydric alcohol, and also contains structural units derived from terephthalic acid or its ester-forming derivatives and / or isophthalic acid or its ester-forming derivatives. The masterbatch contains 10 to 50 mass% of an ester polycondensation catalyst (B) per 100 mass% of the nonvolatile content of the masterbatch. The lower limit of the ester polycondensation catalyst (B) per 100 mass% of the nonvolatile content of the masterbatch is preferably 12 mass%, and the upper limit is more preferably 40 mass%, and even more preferably 30 mass%. Furthermore, the haze of a 1 mm-thick sheet formed from a 280°C kneaded mixture of polyester resin (A) / polyethylene terephthalate resin (PET resin) in a 1 / 1 mass ratio is 20% or less. The ester polycondensation catalyst (B) is at least one selected from phosphorus-based catalysts, titanium-based catalysts, and antimony-based catalysts.

[0028] This masterbatch provides a method for producing polyester resin molded articles that can produce high-quality polyester resins with high productivity, even when recycled polyester resin is used as the polyester resin (C) to be modified. After extensive research, the inventors surprisingly found that by adjusting the concentration of the ester polycondensation catalyst (B) in the masterbatch to 10 to 50% by mass, it is possible to reduce acetaldehyde after solid-state polymerization of polyester resin pellets. The primary reason for this is believed to be that increasing the concentration of the ester polycondensation catalyst (B) in the masterbatch allows the ester polycondensation catalyst (B) to be uniformly dispersed in the polyester resin (C). Uniform dispersion is believed to prevent localized polycondensation in the subsequent solid-state polymerization step, resulting in the production of high-quality polyester resins. Each component is described in detail below. Each component can be used independently, either alone or in combination of two or more.

[0029] 2-1. Polyester Resin (A) The polyester resin (A) is a resin that functions as a dispersion medium for dispersing the ester polycondensation catalyst (B) in the masterbatch, and plays a role in efficiently homogenizing the ester polycondensation catalyst (B) when kneaded with the polyester resin (C) to be modified.

[0030] It is important to use a resin that satisfies the following conditions as the polyester resin (A). That is, it is important to use a resin in which the haze of a 1 mm thick sheet formed from a 280 ° C kneaded mixture of polyester resin (A) / polyethylene terephthalate resin at a mass ratio of 1 / 1 is 20% or less. By using a polyester resin (A) that satisfies this condition, compatibility with polyester resin (C) is improved, productivity is increased when kneaded with the polyester resin (C) to be modified and solid-state polymerization is performed, and a high-quality polyester resin molded product can be obtained. A more preferred range is a haze of 20% or less, more preferably 15% or less, and particularly preferably 10% or less, in a 1 mm thick sheet formed from a 280 ° C kneaded mixture of polyester resin (A) / polyethylene terephthalate resin at a mass ratio of 1 / 1.

[0031] A polyester resin (A) having a haze of 20% or less in a 1 mm thick sheet formed from a 280°C kneaded mixture of polyester resin (A) / polyethylene terephthalate resin in a 1 / 1 mass ratio can be achieved by using a resin that is highly compatible with polyethylene terephthalate resin. As described below, an example of such a method is to increase the content of terephthalic acid or its ester-forming derivative. Another effective method is to increase the dispersion of polyester resin (A) in polyethylene terephthalate. Note that the polyethylene terephthalate resin referred to in this specification refers to a resin obtained by polycondensation of terephthalic acid and ethylene glycol.

[0032] The polyester resin (A) is a polyester resin containing 50 mol% or more of structural units derived from ethylene glycol and / or diethylene glycol per 100 mol% of structural units derived from a polyhydric alcohol, and also containing structural units derived from terephthalic acid or its ester-forming derivatives and / or isophthalic acid or its ester-forming derivatives. Such a polyester resin can be obtained by using at least terephthalic acid or its ester-forming derivatives and / or isophthalic acid or its ester-forming derivatives as the polycarboxylic acid or its ester-forming derivative, and adjusting the amount of ethylene glycol and / or diethylene glycol charged per 100 mol% of the polyhydric alcohol during polymerization. The term "polyhydric alcohol" refers to a polyol, a compound having two or more hydroxyl groups.

[0033] The structural units derived from ethylene glycol and / or diethylene glycol are more preferably 55 mol% or more, and even more preferably 60 mol% or more, relative to 100 mol% of the structural units derived from the polyhydric alcohol. By containing 50 mol% or more of structural units derived from ethylene glycol, excellent compatibility with the polyester resin (C) is achieved. The upper limit is not limited and may be 100 mol%. More preferably, the polyester resin contains 50 mol% or more of structural units derived from ethylene glycol and structural units derived from terephthalic acid or an ester-forming derivative thereof.

[0034] In the polyester resin (A), structural units derived from terephthalic acid or its ester-forming derivatives and / or isophthalic acid or its ester-forming derivatives are preferably 50 mol% or more, more preferably 60 mol% or more, relative to 100 mol% of structural units derived from polycarboxylic acids or their ester-forming derivatives. By containing 50 mol% or more of structural units derived from terephthalic acid or its ester-forming derivatives, compatibility with the polyester resin (C) is improved. The upper limit is not limited and may be 100 mol%.

[0035] The other polymerization components used in the polycondensation of polyester resin (A) are not particularly limited. Suitable examples of polycarboxylic acids or ester-forming derivatives thereof include aromatic dicarboxylic acids such as isophthalic acid, phthalic acid, naphthalene-1,4- or 2,6-dicarboxylic acid, diphenyl ether-4,4'-dicarboxylic acid, diphenyl dicarboxylic acids, and diphenoxyethane diethane dicarboxylic acids, aliphatic dicarboxylic acids such as adipic acid, sebacic acid, azelaic acid, and decane-1,10-dicarboxylic acid, and alicyclic dicarboxylic acids such as cyclohexane dicarboxylic acid.

[0036] Suitable examples of polyhydric alcohols that can be used include aliphatic glycols such as propylene glycol, trimethylene glycol, tetramethylene glycol, diethylene glycol, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, hexamethylene glycol, dodecamethylene glycol, and neopentyl glycol; alicyclic glycols such as cyclohexanedimethanol; 2,2-bis(4'-β-hydroxyethoxyphenyl)propane; and other aromatic diols.

[0037] Examples of the polyester resin (A) include polyethylene terephthalate (PET), polyethylene (terephthalate / isophthalate) (I-PET), polyethylene (terephthalate / adipate), polyethylene (terephthalate / sebacate), polyethylene (terephthalate / decanedicarboxylate), polyethylene (terephthalate / naphthalate), and poly(ethylene / butylene) terephthalate. Also suitable is PET-G, which is made amorphous by polycondensation of terephthalic acid, ethylene glycol, and 1,4-cyclohexanediol. Particularly suitable examples of the polyester resin (A) include PET, PET-G, and I-PET.

[0038] The intrinsic viscosity (IV) of the polyester resin (A) is not limited, but from the viewpoints of processability and suppressing a decrease in IV before solid-state polymerization when added to the polyester resin (C), it is preferably 0.55 dL / g or more, more preferably 0.6 dL / g or more, and even more preferably 0.7 dL / g or more. The upper limit is not particularly limited, but in view of ease of availability, it is preferably 1.2 dL / g or less.

[0039] The flow initiation temperature of the polyester resin (A) is not limited, but is, for example, 180° C. or higher and 260° C. or lower. From the viewpoint of distributability of the masterbatch into the polyester resin (C), a temperature of 200 to 255° C. is preferred. The weight average molecular weight of the polyester resin (A) is not particularly limited as long as the flow initiation temperature is within the above range.

[0040] From the viewpoint of improving the distributability of the masterbatch to the polyester resin (C) when the masterbatch is added to the polyester resin (C) to be modified, the melt mass-flow rate (MFR) of the polyester resin (A) is preferably 5 to 100 g / 10 min, more preferably 10 to 50 g / 10 min.

[0041] The content of polyester resin (A) in 100% by mass of the nonvolatile content of the masterbatch can be set to 40 to 95% by mass, which provides better processability during masterbatch production.

[0042] The acid value of the polyester resin (A) is preferably 0.5 to 35 mg / KOHg, and more preferably 0.5 to 10 mg / KOHg, from the viewpoint of reducing yellowing of the polyester resin (C) after solid-state polymerization.

[0043] The weight average molecular weight of the polyester resin (A) can be, for example, 6,000 to 200,000.

[0044] 2-2. Ester polycondensation catalyst (B) Furthermore, the ester polycondensation catalyst (B) is at least one selected from phosphorus-based catalysts, titanium-based catalysts, and antimony-based catalysts. This masterbatch is a resin composition in which the ester polycondensation catalyst (B) is dispersed at a high concentration, and is mixed with the polyester resin (C), which is the main component, at a specified ratio to modify the polyester resin (C).

[0045] As a result of extensive research, the present inventors have found that by setting the content of the ester polycondensation catalyst (B) to 10 to 50 mass% based on 100 mass% of the nonvolatile content of the masterbatch and using at least one catalyst selected from a phosphorus-based catalyst, a titanium-based catalyst, and an antimony-based catalyst, the molecular weight of the polyester resin (C) to be modified can be increased in a shorter time than conventional methods. From the viewpoint of improving processability, the content of the ester polycondensation catalyst (B) based on 100 mass% of the nonvolatile content of the masterbatch is preferably 45 mass% or less, more preferably 40 mass% or less, and even more preferably 30 mass% or less. Furthermore, from the viewpoint of enhancing the polymerization-promoting effect of the masterbatch during solid-state polymerization, the lower limit is more preferably 7 mass%, even more preferably 10 mass%, and particularly preferably 12 mass%.

[0046] A suitable example of the ester polycondensation catalyst (B) is an acid catalyst having an aromatic ring skeleton and / or an alicyclic skeleton, and further dissolving at least 1 part by mass in 100 parts by mass of the polyester resin (A) at 250°C. The solubility can be confirmed by the method in the Examples described later. By having an aromatic ring skeleton and / or an alicyclic skeleton in the ester polycondensation catalyst (B), compatibility with the polyester resin (A) in the masterbatch can be improved. Furthermore, compatibility with the polyester resin (C) to be modified can be improved.

[0047] Examples of aromatic ring skeletons include carbocyclic skeletons, heterocyclic skeletons, and compounds combining these. The number of ring carbon atoms in the aromatic ring skeleton is preferably 3 to 20, more preferably 4 to 16, 5 to 14, or 6 to 10. Examples of aromatic ring skeletons include a benzene ring skeleton, a naphthalene ring skeleton, and an anthracene ring skeleton. Examples of alicyclic skeletons include alicyclic hydrocarbon skeletons having 5 to 20 carbon atoms, such as a cyclopentane skeleton, a cyclohexane skeleton, a cyclooctane skeleton, a cyclodecane skeleton, an admantane skeleton, a norbornane skeleton, a dicyclopentane skeleton, and a tricyclodecane skeleton. Heterocycles such as morpholine may also be used.

[0048] In order to prevent aggregation of the ester polycondensation catalyst (B) itself, it is preferred that the aromatic ring skeleton and / or alicyclic skeleton have a substituent such as an isobutyl group, a sec-butyl group, or a tert-butyl group.

[0049] Examples of phosphorus-based catalysts include phosphoric acids such as phosphoric acid, trimethyl phosphate, triethyl phosphate, triphenyl phosphate, and acidic methyl phosphate, and their alkyl esters and phenyl esters; phosphorous acids such as phosphorous acid, trimethyl phosphite, and triethyl phosphite, and their alkyl esters and phenyl esters; methylphosphonic acid, phenylphosphonic acid, benzylphosphonic acid, and phosphonic acids such as methylphosphonic acid methyl ester, phenylphosphonic acid ethyl ester, and benzylphosphonic acid phenyl ester, and their alkyl esters and phenyl esters. From the viewpoint of the molecular weight increasing effect, alkylphosphonic acid esters or alkylphosphonic acid monoesters are preferred, and sterically hindered hydroxyphenyl alkylphosphonic acid esters or sterically hindered hydroxyphenyl alkylphosphonic acid monoesters are more preferred.

[0050] A suitable example of the sterically hindered hydroxyphenyl alkylphosphonic acid ester or monoester is represented by the general formula (1). Note that the term "ester" as used herein also includes salts containing an ester group, as will be described later. In the formula, n is 1 to 6; １is an isopropyl group, a tert-butyl group, a cyclohexyl group, or a group in which 1 to 3 hydrogen atoms of a cyclohexyl group are each independently substituted with an alkyl group having 1 to 4 carbon atoms, and R ２ is a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, a cyclohexyl group, or a group in which 1 to 3 hydrogen atoms of a cyclohexyl group are each independently substituted with an alkyl group having 1 to 4 carbon atoms, and R ３ is a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, a phenyl group or a naphthyl group which may have a substituent, and the substituent is an alkyl group having 1 to 4 carbon atoms; R ４ is a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, a phenyl group or a naphthyl group which may have a substituent, and the substituent is an alkyl group having 1 to 4 carbon atoms, or represents M ｒ＋ is a metal cation with a valence of r, where r is 1 to 3.

[0051] In general formula (1), the alkyl group having 1 to 20 carbon atoms is a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, or the like, and may be linear or branched. Of these, an alkyl group having 2 to 4 carbon atoms is more preferred. Furthermore, the alkyl group having 1 to 4 carbon atoms substituted with a cyclohexyl group preferably has 1 to 3 substituents, and particularly preferably has 1 or 2 substituents, and is a branched or unbranched alkyl radical. Examples of the alkyl group having 1 to 4 carbon atoms substituted with a cyclohexyl group include cyclopentyl, methylcyclopentyl, dimethylcyclopentyl, cyclohexyl, methylcyclohexyl, dimethylcyclohexyl, trimethylcyclohexyl, and tert-butylcyclohexyl. Furthermore, the phenyl group or naphthyl group optionally having an alkyl group having 1 to 4 carbon atoms as a substituent preferably has 1 to 3 substituents, and particularly preferably has 1 or 2 substituents. Preferred examples of the cation include o-methylphenyl, m-methylphenyl, p-methylphenyl, 2,3-dimethylphenyl, 2,4-dimethylphenyl, 2,5-dimethylphenyl, 2,6-dimethylphenyl, 3,4-dimethylphenyl, and 3,5-dimethylphenyl. 2-methyl-6-ethylphenyl, 4-tert-butylphenyl, 2-ethylphenyl, 2,6-diethylphenyl, 1-methylnaphthyl, 2-methylnaphthyl, 4-methylnaphthyl, 1,6-dimethylnaphthyl, and 4-tert-butylnaphthyl. The monovalent to trivalent metal cation is preferably an alkali metal cation, an alkaline earth metal cation, a heavy metal cation, or an aluminum cation. Preferred examples include Na ＋ , K. ＋ , Mg ２＋ , Ca ２＋ , Ba ２＋ , Zn ２＋ , Al ３＋ Among these, Ca ２＋ is preferred. １ or R ２ It is particularly preferred that R １ and R ２is a tert-butyl group. n is preferably 1 or 2, and particularly preferably 1.

[0052] Suitable examples of the general formula (1) include the following compounds: In the following compounds, t-Bu represents a tertiary butyl group, and Et represents an ethyl group.

[0053] Examples of titanium catalysts include titanium complexes, titanium alkoxides such as tetra-i-propyl titanate, tetra-n-butyl titanate, and tetra-n-butyl titanate tetramer, titanium oxide, and titanium acetylacetonate.

[0054] Examples of antimony catalysts include antimony oxides such as antimony trioxide and antimony pentoxide, antimony carboxylic acids such as antimony acetate, antimony oxalate and antimony potassium tartrate, and antimony alkoxides such as antimony tri-n-butoxide and antimony triethoxide.

[0055] 2-3. Other Components The masterbatch may contain optional components other than the polyester resin (A) and the ester polycondensation catalyst (B). Examples include resins other than those mentioned above, chain extenders, antioxidants, antistatic agents, surfactants, flame retardants, UV absorbers, and fillers. While extending the solid-state polymerization time increases the intrinsic viscosity of the polyester resin (C), it tends to worsen the degree of yellowing. Through extensive research, the inventors have found that using the ester polycondensation catalyst (B) in combination with an antioxidant is highly effective in preventing yellowing while maintaining high catalytic activity. Examples of antioxidants include phenolic antioxidants, phosphorus-based antioxidants, amine-based antioxidants, and sulfur-based antioxidants. However, phosphorus-based antioxidants are preferred for suppressing oxidative degradation of the ester polymerization catalyst (B) at high temperatures. When an antioxidant is contained, from the viewpoint of improving the heat resistance of the final molded body, the effective content of the antioxidant in 100% by mass of the masterbatch is preferably 0.01 to 3% by mass, and more preferably 0.02 to 1% by mass.

[0056] The polyester resin (A) used in this masterbatch is one that has a haze of 20% or less when formed into a 1 mm thick sheet from a 280°C kneaded mixture of polyester resin (A) / polyethylene terephthalate resin in a mass ratio of 1 / 1.

[0057] Since the distributivity of the masterbatch can be improved and the molecular weight of the polyester resin (C) can be uniformly increased, the MFR of the masterbatch is more preferably 5 to 100 g / 10 min, and even more preferably 10 to 50 g / 10 min. The MFR in the present disclosure is a value measured in accordance with JIS K-7210-1:2014.

[0058] In the present masterbatch, the molecular weight of the polyester resin (A) may be increased when the polyester resin (A) and the ester polycondensation catalyst (B) are kneaded together.

[0059] By using this masterbatch, it is possible to provide high-quality polyester resin molded articles that suppress gelation and crosslinking and side reactions while shortening polymerization time compared to conventional methods. When the masterbatch is diluted with polyester resin (A) so that the ester polycondensation catalyst (B) is 1 part by mass per 100 parts by mass of polyester resin (A), the molecular weight dispersity of the resulting mixture is α, and the molecular weight dispersity of the resulting mixture after solid-state polymerization at 220°C for 10 hours is β, the ratio β / α is preferably 1.00 to 1.20. The upper limit of β / α is more preferably 1.15, and even more preferably 1.10. The molecular weight dispersity refers to the ratio Mw / Mn, or the weight-average molecular weight Mw of the mixture to the number-average molecular weight Mn.

[0060] 2-5. Method for Producing Masterbatch An example of a method for producing the masterbatch will be described below, but the method for producing the masterbatch is not limited to this method.

[0061] The polyester resin (A) and the ester polycondensation catalyst (B) are weighed out and placed in a masterbatch manufacturing device where they are kneaded. Examples of masterbatch manufacturing devices include a single-screw extruder, a twin-screw extruder, and a kneader-ruder. The processing temperature is generally around 10°C to 40°C above the melting point of the polyester resin (C).

[0062] After kneading, the mixture can be extruded from a masterbatch production device such as a die, cooled with water, and then cut into pellets to obtain a masterbatch. In addition to pelletization, the mixture may also be pulverized to form a powder.

[0063] 3. Method for Producing a Polyester Resin (C) Molded Product The method for producing a polyester resin molded product includes a mixing step of adding at least the masterbatch to a polyester resin (C) to be modified and mixing the resulting mixture, and a solid-state polymerization step performed simultaneously with or after the mixing step.

[0064] In the mixing step, the masterbatch is mixed to be homogeneous at a temperature 0 to 30°C higher than the flow initiation temperature of the polyester resin (C). The mixing time is not particularly limited as long as the masterbatch can be mixed homogeneously. For example, it is 1 to 20 minutes. The polyester resin pellets before solid-state polymerization are dissolved in phenol / 1,1,2,2-tetrachloroethane = 1 / 1, and the IV is measured according to JIS K7367-5 using an automatic viscosity measuring device "SS-600-L2" manufactured by Shibayama Scientific Instruments Manufacturing Co., Ltd., to obtain the IV value before solid-state polymerization (IV ｘ ) and the IV value of the polyester resin (C) before processing used as a raw material (IV ０ ) can be calculated. Ratio IV ｘ / IV ０ is preferably 0.8 or more, more preferably 0.85 or more, and even more preferably 0.90 or more. ｘ / IV ０ The upper limit of is not particularly limited, but is usually 1.00.

[0065] In the solid-state polymerization process, the polycondensation process is carried out in the solid phase under vacuum conditions or with high-temperature nitrogen flow at a temperature 5 to 30°C lower than the flow initiation temperature of the polyester resin (C). To obtain a product with even lower molecular weight dispersity, the polycondensation process is carried out in the solid phase at a temperature lower than the flow initiation temperature, for example, 30 to 70°C lower, as long as it does not fall below the glass transition temperature. For example, recycled PET resin and masterbatch are pelletized at 280°C using a twin-screw extruder, and then solid-state polymerized in a tumble dryer at 220°C under a vacuum of about 1 mbar for 5 to 10 hours. Solid-state polymerization increases the molecular weight of the polyester resin (C) and thickens it. The polyester resin pellets after solid-state polymerization are dissolved in phenol / 1,1,2,2-tetrachloroethane (1 / 1), and the IV is measured according to JIS K7367-5 using an automatic viscosity measuring device "SS-600-L2" manufactured by Shibayama Scientific Instruments Co., Ltd., to measure the IV value after solid-state polymerization (IVy). The ratio IV of IVy to IVx mentioned above is ｙ / IV ｘ is preferably 1.05 or more, more preferably 1.10 or more, and even more preferably 1.15 or more. ｙ / IV ｘ The upper limit of is not particularly limited, but is usually about 1.20.

[0066] The solid-state polymerization time can be shortened compared to a method in which the ester polycondensation catalyst (B) is directly added to the polyester resin (C) in powder or pellet form without using a masterbatch. This is believed to be due to the uniform dispersion of the polycondensation catalyst (B) in the polyester resin (C), which suppresses localized thickening. Furthermore, the presence of the polyester resin (A) is believed to improve the compatibility between the ester polycondensation catalyst (B) and the polyester resin (C). This is believed to promote the reaction between the ester polycondensation catalyst (B) and the polyester resin (C) in the solid-state polymerization step, thereby accelerating thickening of the polyester resin (C). As a result, a high-quality polyester resin can be obtained. Furthermore, productivity can be significantly improved.

[0067] The degree of increase in melt viscosity of the polyester resin (C) is preferably 5 to 40%, more preferably 7 to 30%, and even more preferably 10 to 25% relative to the melt viscosity of the polyester resin (C) before processing. When the rate of increase in melt viscosity is within the above range, the physical properties of the polyester resin (C) can be improved without affecting moldability.

[0068] Furthermore, according to the present method for producing a polyester resin molded product, the amount of acetaldehyde (AA) generated during the production process of the polyester resin molded product can be significantly improved. This is thought to be because the molecular weight of the polyester resin increases, and decomposition products of the low-molecular-weight polyester resin that generate acetaldehyde are not generated.

[0069] The thickened polyester resin (C) can be molded into various shapes by known methods, such as single-screw extrusion, twin-screw extrusion, injection molding, and blow molding.

[0070] The present disclosure will be described in more detail below based on examples, but the present disclosure is not limited to these examples. Unless otherwise specified, in the examples, "parts" and "%" represent "parts by mass" and "% by mass", respectively.

[0071] [a] Masterbatch a-1 Polyester resin (A) etc. The polyester resin (A) etc. used in the examples and comparative examples are shown below. A-1: MA2101 (manufactured by Unitika Ltd., PET) A-2: PIFG30 (manufactured by Bell Polyester Products, I-PET) A-3: GN001 (manufactured by Eastman Chemical Company, PET-G) A-4: Synthesis Example 1 (PET) A-5: Synthesis Example 2 (PET) A-6: Synthesis Example 3 (PET) A-7: Synthesis Example 4 (PET) A-8: Synthesis Example 5 (PET) A-9: GN5011 (manufactured by Eastman Chemical Company, PET-G) A-10: SA8639-P (manufactured by Unitika Ltd., PET) A-11: Recycled PET from film (PET) A-12: SA863JP (manufactured by Mitsui Chemicals, Inc., PET) A'-13: 300FP (manufactured by WinTech Polymer, PBT) A'-14: DN011 (manufactured by Eastman Chemical Company, PCT) A'-15: Synthesis Example 6 (PBT) A'-16: Synthesis Example 7 (PET-G)

[0072] a-2. Synthesis Examples of Polyester Resin (A) and the Like <Polyester Resin (A-4): Synthesis Example 1> 100 parts by mass of dimethyl terephthalate, 57.5 parts by mass of ethylene glycol, 0.06 parts by mass of magnesium acetate, and 0.03 parts by mass of antimony trioxide were melted at 150°C under a nitrogen atmosphere. The mixture was then heated to 230°C over 3 hours with stirring, and the methanol was distilled off to terminate the transesterification reaction. After completion of the transesterification reaction, an ethylene glycol solution (pH 5.0) prepared by dissolving 0.019 parts by mass of phosphoric acid and 0.027 parts by mass of sodium dihydrogen phosphate dihydrate in 0.5 parts by mass of ethylene glycol was added to the reaction mixture. The polymerization reaction was then carried out at a final temperature of 285°C and a vacuum of 0.1 Torr, yielding a polyester resin with an intrinsic viscosity of 0.55 dl / g. The resulting polyester resin was then dried at 160°C for 5 hours and crystallized. Next, solid-phase polymerization was carried out at 220°C under a vacuum of 0.3 Torr for 6 hours to obtain a polyester resin (A-4) having an intrinsic viscosity of 0.87 dl / g and a melting point of 255°C.

[0073] <Polyester Resin (A-5): Synthesis Example 2> 100 parts by mass of dimethyl terephthalate, 54.7 parts by mass of ethylene glycol, 6.0 parts by mass of cyclohexanedimethanol glycol, 0.06 parts by mass of magnesium acetate, and 0.03 parts by mass of antimony trioxide were melted at 150°C under a nitrogen atmosphere. The mixture was then heated to 230°C over 3 hours with stirring, and the methanol was distilled off to terminate the transesterification reaction. After the transesterification reaction was completed, an ethylene glycol solution (pH 5.0) containing 0.019 parts by mass of phosphoric acid and 0.027 parts by mass of sodium dihydrogen phosphate dihydrate dissolved in 0.5 parts by mass of ethylene glycol was added to the reaction mixture. The polymerization reaction was then carried out at a final temperature of 285°C and a vacuum of 0.1 Torr, yielding a polyester resin with an intrinsic viscosity of 0.54 dl / g. The resulting polyester resin was then dried at 160°C for 5 hours and crystallized. Subsequently, solid-phase polymerization was carried out at 220°C under a vacuum of 0.3 Torr for 6 hours to obtain a polyester resin (A-5) having an intrinsic viscosity of 0.86 dl / g and a melting point of 240°C.

[0074] <Polyester Resin (A-6): Synthesis Example 3> 100 parts by mass of dimethyl terephthalate, 51.8 parts by mass of ethylene glycol, 12.1 parts by mass of cyclohexanedimethanol glycol, 0.06 parts by mass of magnesium acetate, and 0.03 parts by mass of antimony trioxide were melted at 150°C under a nitrogen atmosphere. The mixture was then heated to 230°C over 3 hours with stirring, and the methanol was distilled off to terminate the transesterification reaction. After the transesterification reaction was completed, an ethylene glycol solution (pH 5.0) containing 0.019 parts by mass of phosphoric acid and 0.027 parts by mass of sodium dihydrogen phosphate dihydrate dissolved in 0.5 parts by mass of ethylene glycol was added to the reaction mixture. The polymerization reaction was then carried out at a final temperature of 285°C and a vacuum of 0.1 Torr, yielding a polyester resin with an intrinsic viscosity of 0.54 dl / g. The resulting polyester resin was then dried at 160°C for 5 hours and crystallized. Subsequently, solid-phase polymerization was carried out at 220°C under a vacuum of 0.3 Torr for 6 hours to obtain a polyester resin (A-6) having an intrinsic viscosity of 0.86 dl / g and a melting point of 228°C.

[0075] <Polyester Resin (A-7): Synthesis Example 4> 100 parts by mass of dimethyl terephthalate, 57.5 parts by mass of ethylene glycol, 12.1 parts by mass of cyclohexanedimethanol glycol, 0.06 parts by mass of magnesium acetate, and 0.05 parts by mass of titanium lactate ammonium salt were melted at 150°C under a nitrogen atmosphere. The mixture was then heated to 230°C over 3 hours with stirring, and the methanol was distilled off to terminate the transesterification reaction. After the transesterification reaction was completed, an ethylene glycol solution (pH 5.0) containing 0.019 parts by mass of phosphoric acid and 0.027 parts by mass of sodium dihydrogen phosphate dihydrate dissolved in 0.5 parts by mass of ethylene glycol was added to the reaction mixture. The polymerization reaction was then carried out at a final temperature of 285°C and a vacuum of 0.1 Torr, yielding a polyester resin with an intrinsic viscosity of 0.53 dl / g. The resulting polyester resin was then dried at 160°C for 5 hours and crystallized. Subsequently, solid-phase polymerization was carried out at 220°C under a vacuum of 0.3 Torr for 8 hours to obtain a polyester resin (A-7) having an intrinsic viscosity of 0.85 dl / g and a melting point of 255°C.

[0076] <Polyester Resin (A-8): Synthesis Example 5> 100 parts by mass of dimethyl terephthalate, 54.9 parts by mass of ethylene glycol, 16.3 parts by mass of neopentyl glycol, and 0.04 parts by mass of tetrabutyl titanate were added, and a transesterification reaction was carried out for 2 hours at 170 to 220°C. After completion of the transesterification reaction, the reaction system was heated from 220°C to 270°C, while the pressure inside the system was slowly reduced to 500 Pa over 60 minutes. A polycondensation reaction was then carried out for 55 minutes at 130 Pa or less, yielding a polyester resin (A-8) having an intrinsic viscosity of 0.51 dl / g and a flow initiation temperature of 170°C.

[0077] <Polyester Resin (A'-15): Synthesis Example 6> 100 parts by mass of dimethyl terephthalate, 83.5 parts by mass of butylene glycol, 0.06 parts by mass of magnesium acetate, and 0.03 parts by mass of antimony trioxide were melted at 150°C under a nitrogen atmosphere. The mixture was then heated to 230°C over 3 hours with stirring, and the methanol was distilled off to terminate the transesterification reaction. After the transesterification reaction was completed, an ethylene glycol solution (pH 5.0) containing 0.019 parts by mass of phosphoric acid and 0.027 parts by mass of sodium dihydrogen phosphate dihydrate dissolved in 0.5 parts by mass of ethylene glycol was added to the reaction mixture. The polymerization reaction was then carried out at a final temperature of 285°C and a vacuum of 0.1 Torr, yielding a polyester resin with an intrinsic viscosity of 0.53 dl / g. The resulting polyester resin was dried at 140°C for 5 hours and crystallized. Subsequently, solid-phase polymerization was carried out at 200°C under a vacuum of 0.3 Torr for 8 hours to obtain a polyester resin (A'-15) having an intrinsic viscosity of 0.80 dl / g and a melting point of 234°C.

[0078] <Polyester Resin (A'-16): Synthesis Example 7> 100 parts by mass of dimethyl terephthalate, 28.7 parts by mass of ethylene glycol, 67.6 parts by mass of cyclohexanedimethanol glycol, 0.06 parts by mass of magnesium acetate, and 0.03 parts by mass of antimony trioxide were melted at 150°C under a nitrogen atmosphere. The mixture was then heated to 230°C over 3 hours with stirring, and the methanol was distilled off to terminate the transesterification reaction. After the transesterification reaction was completed, an ethylene glycol solution (pH 5.0) containing 0.019 parts by mass of phosphoric acid and 0.027 parts by mass of sodium dihydrogen phosphate dihydrate dissolved in 0.5 parts by mass of ethylene glycol was added to the reaction mixture. The polymerization reaction was then carried out at a final temperature of 285°C and a vacuum of 0.1 Torr, yielding a polyester resin with an intrinsic viscosity of 0.53 dl / g. The resulting polyester resin was dried at 160°C for 5 hours and crystallized. Subsequently, solid-phase polymerization was carried out at 220°C under a vacuum of 0.3 Torr for 8 hours to obtain a polyester resin (A'-16) having an intrinsic viscosity of 0.85 dl / g and a melting point of 255°C.

[0079] a-3. Haze evaluation of polyester resin (A) etc. Polyester resin (A) etc. and polyethylene terephthalate resin (PET resin, flow initiation temperature 255°C, IV 0.84) were mixed at a mass ratio of 1 / 1 and 280°C, and injected into a mold at a mold temperature of 20°C using an injection molding machine (manufactured by Toshiba Machine Co., Ltd.) with an injection pressure of 60t to form a sheet with a thickness of 1 mm. The haze of the obtained sheet was measured using a Haze Guard Plus (manufactured by Gardner) in accordance with JIS K7136:2000. Haze (H ｘ The evaluation criteria for the above were as follows: +++: H ｘ ≦10 ++: 10<H ｘ ≦15+:15<H ｘ ≦20 NG: 20<H ｘ

[0080] Table 1 shows the intrinsic viscosity (IV), flow initiation temperature, sheet haze, etc. of polyester resins (A) etc. Also shown is the content (mol%) of structural units derived from ethylene glycol and / or diethylene glycol in 100 mol% of structural units derived from polyhydric alcohols constituting polyester resins (A) etc., and the content (mol%) of structural units derived from terephthalic acid or its ester-forming derivatives (hereinafter also referred to as terephthalic acid, etc.) and / or isophthalic acid or its ester-forming derivatives (hereinafter also referred to as isophthalic acid, etc.) in 100 mol% of structural units derived from polycarboxylic acids or their ester-forming derivatives (hereinafter also referred to as polycarboxylic acids, etc.) constituting polyester resins (A). These were determined by measuring the polyester resins (A) by gas chromatography mass spectrometry (GC / MS).

[0081]

[0082] a-4. Ester polycondensation catalyst (B) and antioxidant The ester polycondensation catalyst (B) (hereinafter also referred to as catalyst (B)) and antioxidant used in the examples and comparative examples are shown below. B-1: Irganox 1222 (manufactured by BASF, diethyl [[3,5-bis(1,1-dimethylethyl)-4-hydroxyphenyl]methyl]phosphonate) B-2: Irganox 1425 (manufactured by BASF, calcium diethyl bis[[[3,5-bis(1,1-dimethylethyl)-4-hydroxyphenyl]methyl]phosphonate] B-3: diethyl hydroxyphenylmethylenephosphonate B-4: 2,6-dimethylbenzenesulfonic acid (manufactured by Kishida Chemical Co., Ltd.) B-5: antimony trioxide (manufactured by Nihon Seiko Co., Ltd.) B-6: SPC-124 (manufactured by Sakai Chemical Co., Ltd., titanium-based catalyst) Antioxidants D-1: Irgafos 168 (manufactured by BASF, phosphorus-based antioxidant) D-2: Irganox B225 (manufactured by BASF, phosphorus-based / phenolic acid

[0083] The solubility of the ester polycondensation catalyst (B) is shown in Table 2. 1 part by mass of the ester polycondensation catalyst (B) was added to 100 parts by mass of the polyester resin (A), and the mixture was heated to 250°C while stirring with a mechanical stirrer. If the ester polycondensation catalyst (B) could not be visually confirmed, it was determined that the catalyst had dissolved in the polyester resin (A). ○ indicates that the catalyst dissolved, and × indicates that the catalyst did not dissolve. The results are shown in Table 2.

[0084] a-5. Production of Masterbatch (Example 1-1) 90 parts of polyester resin (A-1) and 10 parts of catalyst (B-1) were weighed out and mixed in a co-rotating twin-screw extruder "TEX-54α3" (L / D = 52.5, discharge rate: 350 kg / hr, 3 vent holes) manufactured by The Japan Steel Works, Ltd. The mixture was then extruded at 260°C through the vent holes while being suctioned and degassed under high vacuum, and cut with a pelletizer to obtain a masterbatch according to Example 1-1.

[0085] (Examples 1-2 to 1-23, Comparative Examples X-1 to X-5) Masterbatches according to Examples 1-2 to 1-23 and Comparative Examples X-1 to X-5 were obtained in the same manner as in Example 1-1, except that the materials and blending amounts (parts by mass) were changed to those shown in Tables 3A and 3B, respectively.

[0086] a-6. Evaluation of Masterbatch Processability The masterbatches of the Examples and the like were produced continuously for 1 hour using a twin-screw extruder, and strand breakage was confirmed, and productivity (processability) was evaluated according to the following criteria. The results are shown in Tables 3A and 3B. Strand breakage refers to the state in which the strand breaks and becomes unable to be pulled. +++: No strand breakage occurred. ++: Strand breakage occurred 1 or more times but not more than 5 times. +: Strand breakage occurred more than 5 times but not more than 10 times. NG: Not applicable to any of the above evaluations. Or the masterbatch could not be produced.

[0087] a-7. Evaluation of the Increase Rate of Molecular Weight Dispersity The master batch of each Example and Comparative Example was diluted with polyester resin (A) so that the ester polycondensation catalyst (B) was 1 part by mass per 100 parts by mass of polyester resin (A), to obtain a mixture. The molecular weight dispersity α of the obtained mixture was determined. The mixture was then solid-state polymerized at 220°C for 10 hours, and the molecular weight dispersity β after solid-state polymerization was determined. These results and the value of β / α are shown in Tables 3A and 3B. The number-average molecular weight Mn and weight-average molecular weight Mw were measured by gel permeation chromatography (GPC) using a Shodex GPC LF-404 column, with the sample solution filtered through a membrane filter after dissolving recycled PET pellets in a 10 mmol / L sodium trifluoroacetate / hexafluoroisopropanol (HFIP) mixed solution as the solvent. Mn and Mw are values ​​relative to the molecular weight of standard polystyrene.

[0088]

[0089]

[0090] The masterbatches containing 5 to 60% by mass of the ester polycondensation catalyst (B) exhibited excellent processability in both the Examples and Comparative Examples. Furthermore, it was confirmed that the increase rate β / α of the molecular weight dispersity in the masterbatches of the Examples was 1 to 1.2.

[0091] [b] Polyester Resin Pellets b-1. Polyester Resin (C) The polyester resins (C) used in the Examples and Comparative Examples are shown below. C-1: IV: 0.77, PET C-2: IV: 0.64, PET C-3: IV: 1.11, PET C-4: IV: 0.41, PET C-5: IV: 0.80, PIFG-5 (I-PET, manufactured by Bell Polyester Products Co., Ltd.) C-6: IV: 0.80, PIFG-30 (I-PET, manufactured by Bell Polyester Products Co., Ltd.) C-7: IV: 0.97, PIFG-5H (I-PET, manufactured by Bell Polyester Products Co., Ltd.) C-8: IV: 0.85, Clapet KS710-BS (PET, manufactured by Kuraray Co., Ltd.) C-9: IV: 0.75, GN071 (PET-G, manufactured by Eastman Chemical Co.) C-10: IV: 0.67, GN401 (manufactured by Eastman Chemical Company, PET-G) C-11: IV: 0.72, TX1001 (manufactured by Eastman Chemical Company, copolymeric polyester resin) C-12: IV: 0.67, TX1801 (manufactured by Eastman Chemical Company, copolymeric polyester resin)

[0092] b-2. Preparation of polyester resin pellets [Reference Example 1] 100 parts of flake-shaped PET resin (IV: 0.77 dl / g) derived from beverage bottles was extruded using a single-screw extruder (Dalmage screw) with a screw diameter of 40 mm manufactured by Nippon Placon Co., Ltd. at a screw rotation speed of 90 rpm, a processing temperature of 270°C, and a discharge rate of 20 kg / h to prepare polyester resin pellets according to Reference Example 1.

[0093] Example 2-1 A mixture of 100 parts of PET flake resin (IV: 0.77 dl / g) derived from beverage bottles and 2 parts of the masterbatch according to Example 1-1 was tumbled and extruded in a single-screw extruder (Dalmage screw) having a screw diameter of 40 mm manufactured by Nippon Placon Co., Ltd. at a screw rotation speed of 90 rpm, a processing temperature of 270°C, a discharge rate of 20 kg / h, and a residence time in the extruder of 1 minute to produce polyester resin pellets (1) according to Example 2-1.

[0094] Examples 2-2 to 2-27, Comparative Examples Y-1 to Y-9 Polyester resin pellets were obtained in the same manner as in Example 2-1, except that the materials and blending amounts (parts by mass) were changed to those shown in Tables 4A, 4B, and 5, respectively.

[0095] [Comparative Examples Y-11 and Y-12] Polyester resin pellets were obtained in the same manner as in Example 2-1, except that a powdery ester polycondensation catalyst (B) was used instead of the master batch, and the materials and blending amounts (parts by mass) were changed to those shown in Table 5.

[0096]

[0097]

[0098]

[0099] b-3. Evaluation of polyester resin pellets <Intrinsic viscosity (IV) before solid-state polymerization> The polyester resin pellets before solid-state polymerization of each Example and Comparative Example were dissolved in phenol / 1,1,2,2-tetrachloroethane = 1 / 1, and the IV was measured according to JIS K7367-5 using an automatic viscosity measuring device "SS-600-L2" manufactured by Shibayama Scientific Instruments Co., Ltd. The IV value (IV ｘ ) and the IV value of the PET flake resin derived from beverage bottles before processing (IV ０ ) ratio IV ｘ / IV ０ The PET flake resin derived from beverage bottles before processing is the polyester resin used as the raw material in Example 2-1, and the IV value of the raw material resin used as polyester resin (C) is IV ０ ++++: 0.95≦IV ｘ / IV ０ +++: 0.90≦IV ｘ / IV ０ <0.95++: 0.85≦IV ｘ / IV ０ <0.90+: 0.80≦IV ｘ / IV ０ <0.85 NG: IV ｘ / IV ０ <0.80

[0100] <Evaluation of Increase in Intrinsic Viscosity (IV) After Solid-State Polymerization> Solid-state polymerization was carried out using polyester resin pellets from each Example and Comparative Example. The solid-state polymerization conditions were 220°C, a degree of vacuum of 0.3 Torr, and 10 hours and 20 hours (the same conditions were used for the following evaluations). Thereafter, the resulting reaction product was dissolved in a phenol / 1,1,2,2-tetrachloroethane = 1 / 1 solution, and the intrinsic viscosity (IV) of the polyester resin pellets was measured in accordance with JIS K7367-5 using an automatic viscosity measuring device "SS-600-L2" manufactured by Shibayama Scientific Instruments Co., Ltd. ｙ The IV of each example and comparative example was measured. ｙ , IV ｘ The increase in intrinsic viscosity from IV was evaluated according to the following criteria: ++++: 1.15≦IV ｙ / IV ｘ +++: 1.10≦IV ｙ / IV ｘ <1.15++: 1.08≦IV ｙ / IV ｘ <1.10+: 1.05≦IV ｙ / IV ｘ <1.08 NG: IV ｙ / IV ｘ <1.05

[0101] <Evaluation of Acetaldehyde (AA) Amount> (Water Extraction Method) The polyester resin pellets of each Example and Comparative Example were subjected to solid-state polymerization. After solid-state polymerization, each polyester resin pellet was freeze-pulverized and sieved through a 1 μm or smaller sieve, after which 0.2 g was weighed. 5 mL of pure water was added to the pellets and the mixture was shaken. Next, 1 mL of the aqueous layer was mixed with 1 mL of DNPH (2,4-dinitrophenylhydrazine) solution to prepare a test solution. The test solution was introduced into HPLC, and the peak area value of the DNPH-decomposed aldehyde was determined. Quantitation was performed using a standard solution prepared by derivatizing a 15 μg / mL acetaldehyde / acetonitrile solution with DNPH. The evaluation criteria are as follows: ++++: Less than 0.5 ppm. +++: 0.5 ppm or more, less than 1 ppm. ++: 1 ppm or more, less than 2 ppm. +: 2 ppm or more, less than 3 ppm. NG: 3ppm or more.

[0102] (Total Dissolution Method) After solid-state polymerization, each polyester resin pellet from each Example and Comparative Example was crushed and weighed out at 1.0 g. 5 mL of hexafluoroisopropanol (HFIP) was added to the pellet, and the pellet was left to stand overnight at room temperature to completely dissolve the sample. Next, a solution of DNPH (2,4-dinitrophenylhydrazine) in acetonitrile was added and subjected to ultrasonic dispersion treatment. The soluble portion was recovered, and the residue was washed several times with the DNPH in acetonitrile solution and then adjusted to a constant volume of 25 mL. The test solution was introduced into an HPLC, and the peak area value of the DNPH-decomposed aldehyde was determined. Quantitative analysis was performed using a standard solution prepared by derivatizing a 15 μg / mL acetaldehyde / acetonitrile solution with DNPH. The evaluation criteria are as follows: ++++: Less than 0.5 ppm. +++: 0.5 ppm or more, less than 1 ppm. ++: 1 ppm or more, less than 2 ppm. +: 2 ppm or more and less than 3 ppm. NG: 3 ppm or more.

[0103] <Yellowness Index (YI Value)> The polyester resin pellets after solid-state polymerization of each Example and Comparative Example were injection molded at 270°C using an injection molding machine (IS-100F, manufactured by Toshiba Machine Co., Ltd.) to prepare rectangular parallelepiped test pieces measuring 30 mm length x 40 mm width x 3 mm height. Then, using an AU Color COLOR 7x imaging spectrophotometer manufactured by Kurabo Industries, Ltd., the L value (lightness), a value, and b value of the test pieces were measured using a D-65(10) standard light source, and the YI value was calculated according to JIS K7373 to measure the yellowness index. The evaluation criteria were as follows: ++++: 0≦YI<5 +++: 5≦YI<10 ++: 10≦YI<15 +: 15≦YI<20 NG: 20≦YI

[0104]

[0105]

[0106] Comparative Examples Y-7 and Y-8, which do not use a masterbatch, are IV before solid-state polymerization. ０It was confirmed that the decrease in IVx relative to the amount of polyester resin (C) was large. This is thought to be due to the lack of a masterbatch, which poses challenges in uniform dispersion in the polyester resin (C). On the other hand, even when a masterbatch was used, Comparative Examples Y-1 to Y-3, which do not have structural units derived from ethylene glycol as the polyester resin (A), exhibited broad Mw / Mn, and high-quality polyester resin molded articles were not obtained. It is thought that the large amount of low-molecular-weight components also contributed to the large AA value. Furthermore, although the IVx before solid-state polymerization was good, the increase in IVy after solid-state polymerization was small, and high-quality polyester resin molded articles were not obtained. Furthermore, even in polyester resins containing structural units derived from terephthalic acid or its ester-forming derivatives, when the haze of a 1-mm-thick sheet formed from a 280°C blend of polyester resin / polyethylene terephthalate resin in a 1 / 1 mass ratio exceeded 20%, it was confirmed that the increase in IVy after solid-state polymerization was small and the AA value was high, as shown in Comparative Example Y-2.

[0107] [c] Manufacturing of PET bottles c-1. Manufacturing method The polyester resin pellets after solid-state polymerization of each Example and Comparative Example were blow molded at 280°C using a blow molding machine to produce 50 PET bottles for each Example and Comparative Example. The thickness of the PET bottles was 1 mm.

[0108] c-2. Evaluation <Blow moldability> With regard to the blow moldability of the PET bottles obtained in the examples, etc., bottles in which the thickness of the longitudinally stretched portion was uniformly 1 mm were considered to be good products, and the yield of good products was evaluated according to the following criteria: ++++: The yield of good products was 100%. +++: The yield of good products was 95% or more and less than 100%. ++: The yield of good products was 90% or more and less than 95%. +: The yield of good products was 85% or more and less than 90%. NG: The yield of good products was less than 85%.

[0109] <Drop Strength> An impact test was conducted on 10 randomly selected PET bottles from the non-defective bottles obtained in the Examples and the like. Specifically, 80% of the PET bottles were filled with water and dropped from a height of 1 m. The evaluation criteria were as follows: ++++: No holes or deformation were observed in any of the 10 bottles. +++: No holes were observed in any of the 10 bottles, but less than 5 bottles were deformed. ++: No holes were observed in any of the 10 bottles, but 5 to less than 10 bottles were deformed. +: Deformation was observed in all 10 bottles, and less than 2 bottles had holes. NG: Deformation was observed in all 10 bottles, and 2 or more bottles had holes.

[0110]

[0111]

[0112] [Industrial Applicability] The present molded article manufacturing method has excellent moldability and can provide high-quality molded articles using general-purpose processing methods, making it suitable for recycling used plastic products such as used PET bottles and fibers, or plastic products generated during production processes. Furthermore, because the present molded articles have excellent quality, they can be suitably used as high-performance resin materials in a wide range of applications, including fibers, films, sheets, foams, containers, electronic materials, building materials, automotive parts, and various industrial parts and products.

[0113] This application claims priority based on Japanese Patent Application No. 2022-114385, filed on July 15, 2022, the disclosure of which is incorporated herein by reference in its entirety.

Claims

1. A masterbatch for accelerating the solid-phase polymerization of polyester resins, It contains a polyester resin (A) and an ester polycondensation catalyst (B), Polyester resin (A) is a resin that contains 50 mol% or more of structural units derived from ethylene glycol and / or diethylene glycol per 100 mol% of structural units derived from polyhydric alcohols, and also contains structural units derived from terephthalic acid or its ester-forming derivative and / or isophthalic acid or its ester-forming derivative. The masterbatch contains 5 to 60% by mass of ester polycondensation catalyst (B) in 100% by mass of nonvolatile content. A sheet with a thickness of 1 mm formed from a 280°C mixture of polyester resin (A) and polyethylene terephthalate resin in a mass ratio of 1 / 1 has a haze of 20% or less. The ester polycondensation catalyst (B) is at least one selected from phosphorus-based catalysts, titanium-based catalysts, and antimony-based catalysts. However, this excludes masterbatches used to promote the solid-phase polymerization of polyethylene terephthalate, in which the polyester resin (A) contains 50 mol% or more of structural units derived from ethylene glycol per 100 mol% of structural units derived from polyhydric alcohol, and also contains structural units derived from terephthalic acid or its ester-forming derivative, and the masterbatch contains 10 to 30% by mass of ester polycondensation catalyst (B) in 100% by mass of nonvolatile content of the masterbatch, and has an intrinsic viscosity of 0.6 to 1.2 dl / g. Masterbatch.

2. Ester polycondensation catalyst (B) is an acid catalyst and has an aromatic ring skeleton and / or an alicyclic skeleton. The masterbatch according to claim 1, characterized in that at least 1 part by mass of an ester polycondensation catalyst (B) is dissolved in 100 parts by mass of a polyester resin (A) at 250°C.

3. The masterbatch according to claim 1 or 2, characterized in that the ester polycondensation catalyst (B) is selected from alkylphosphonic acid esters or alkylphosphonic acid monoesters.

4. The masterbatch according to claim 1 or 2, characterized in that the ester polycondensation catalyst (B) is a sterically hindered hydroxyphenylalkylphosphonic acid ester or a sterically hindered hydroxyphenylalkylphosphonic acid monoester.

5. The masterbatch according to claim 1 or 2, characterized in that when the masterbatch is diluted with polyester resin (A) to such an extent that the amount of ester polycondensation catalyst (B) is 1 part by mass per 100 parts by mass of polyester resin (A), the molecular weight dispersion of the mixture is α, and the molecular weight dispersion of the mixture after solid-phase polymerization at 220°C for 10 hours is β, then β / α is 1.00 to 1.

20.

6. A step of obtaining a masterbatch containing a polyester resin (A) and an ester polycondensation catalyst (B), A mixing step of adding at least the masterbatch to the polyester resin (C) to be modified and mixing it, A step of solid-phase polymerization performed simultaneously with or after the mixing step, This includes a molding step in which the product is formed after solid-phase polymerization. Polyester resin (A) is a resin that contains 50 mol% or more of structural units derived from ethylene glycol and / or diethylene glycol per 100 mol% of structural units derived from polyhydric alcohols, and also contains structural units derived from terephthalic acid or its ester-forming derivative and / or isophthalic acid or its ester-forming derivative. The masterbatch contains 5 to 60% by mass of ester polycondensation catalyst (B) in 100% by mass of nonvolatile content. A sheet with a thickness of 1 mm formed from a 280°C mixture of polyester resin (A) and polyethylene terephthalate resin in a mass ratio of 1 / 1 has a haze of 20% or less. A method for producing a polyester resin molded article, wherein the ester polycondensation catalyst (B) is at least one selected from a phosphorus-based catalyst, a titanium-based catalyst, and an antimony-based catalyst.

7. The method for producing a polyester resin molded article according to claim 6, characterized in that the ester polycondensation catalyst (B) is selected from alkylphosphonic acid esters or alkylphosphonic acid monoesters.

8. A method for producing a polyester resin molded article according to claim 6 or 7, characterized in that the ester polycondensation catalyst (B) is a sterically hindered hydroxyphenylalkylphosphonic acid ester or a sterically hindered hydroxyphenylalkylphosphonic acid monoester.