Molded body containing recycled polyester-based resin

Abstract

The present invention addresses the problem of providing a molded body that contains a recycled polyester-based resin, the molded body having excellent strength and reduced whitening. Provided is a molded body obtained by molding a resin composition containing a recycled polyester-based resin, wherein the haze of a solution of the molded body is 1.50% or more, and the haze of the molded body is 7.5 or less.

Description

Molded body containing recycled polyester resin

[0001] The present invention relates to a molded article containing a recycled polyester resin.

[0002] In recent years, there has been a demand for resin recycling from the viewpoints of resource reuse and environmental protection. However, polyester-based resins have a problem in that their melt viscosity decreases each time they are recycled, resulting in a deterioration in strength. As a technique for solving this problem, a technique of adding a chain extender (sometimes referred to as a "viscosity modifier" or "melt viscosity improver: MVI") is known (for example, Patent Documents 1 to 3).

[0003] Furthermore, a technique called solid-state polymerization (SSP) is also known as a technique for increasing the melt viscosity of polyester-based resins (for example, Patent Document 4).

[0004] International Publication No. 2004 / 039887 International Publication No. 2004 / 041934 International Publication No. 2007 / 040041 Japanese Patent Application Laid-Open No. 2016-053138

[0005] However, the above-mentioned conventional techniques are not sufficient from the viewpoint of preventing whitening of molded articles, and there is room for further improvement.

[0006] One embodiment of the present invention has been made in consideration of the above-mentioned problems, and its object is to provide a molded body containing a recycled polyester-based resin, which has excellent strength and reduced whitening.

[0007] The present inventors have conducted extensive research to solve the above problems and have completed the present invention.

[0008] That is, a molded article according to one embodiment of the present invention is a molded article obtained by molding a resin composition containing a recycled polyester resin, and the haze of a solution of the molded article is 1.50% or more, and the haze of the molded article is 7.5 or less. Here, the haze of the solution of the molded article is a value measured by carrying out the following steps (1) to (2) in order; (1) dissolving the resin composition in hexafluoro-2-propanol to obtain a solution having a resin composition concentration of 0.05 g / mL; (2) measuring the haze of the solution of the molded article obtained using a haze meter whose zero point has been adjusted with the hexafluoro-2-propanol; The haze of the molded article is a value obtained by measurement using the haze meter.

[0009] Furthermore, a whitening inhibitor for polyester resins according to one embodiment of the present invention includes a polymer (A) obtained by polymerizing a monomer mixture (A) containing (a) 10% by weight to 60% by weight of an epoxy group-containing monomer and (b) 40% by weight to 90% by weight of an epoxy group-free monomer.

[0010] Furthermore, a method for producing a molded article according to one embodiment of the present invention includes the steps of preparing a recycled polyester resin composition and molding the recycled polyester resin composition, wherein the step of preparing the recycled polyester resin composition includes the steps of melt-kneading a whitening inhibitor for polyester resins and a polyester resin to prepare pellets containing the whitening inhibitor for polyester resins and the polyester resin, and performing solid-state polymerization using the pellets, and the whitening inhibitor for polyester resins includes a polymer (A) obtained by polymerizing a monomer mixture (A) containing (a) 10 parts by weight to 60 parts by weight of an epoxy group-containing monomer, and (b) 40 parts by weight to 90 parts by weight of a non-epoxy group-containing monomer.

[0011] According to one embodiment of the present invention, it is possible to provide a molded article containing a recycled polyester resin, which has excellent strength and reduced whitening.

[0012] An embodiment of the present invention will be described below, but the present invention is not limited thereto. The present invention is not limited to the respective configurations described below, and various modifications are possible within the scope of the claims. Furthermore, embodiments or examples obtained by combining the technical means disclosed in different embodiments or examples are also included in the technical scope of the present invention. Furthermore, new technical features can be formed by combining the technical means disclosed in each embodiment. All academic literature and patent documents described in this specification are incorporated herein by reference. Furthermore, unless otherwise specified in this specification, the term "A to B" representing a numerical range means "greater than or equal to A (including and greater than A) and less than or equal to B (including and less than B)."

[0013] [1. Molded Product] A molded product according to one embodiment of the present invention is a molded product obtained by molding a resin composition containing a recycled polyester resin, wherein the haze of a solution of the molded product is 1.50% or more and the haze of the molded product is 7.5 or less. Here, the haze of the solution of the molded product is a value measured by carrying out the following steps (1) to (2) in order: (1) dissolving the resin composition in hexafluoro-2-propanol to obtain a solution having a resin composition concentration of 0.05 g / mL; (2) measuring the haze of the solution of the molded product using a haze meter whose zero point has been adjusted with the hexafluoro-2-propanol; The haze of the molded product is a value obtained by measurement using the haze meter.

[0014] In this specification, a "molded body according to one embodiment of the present invention" may be referred to as "the present molded body." In this specification, a "resin composition containing a recycled polyester-based resin" may be referred to as a "recycled polyester-based resin composition" or simply as a "resin composition." The resin composition that is the raw material of the present molded body can also be said to be a resin composition according to one embodiment of the present invention. In this specification, a "resin composition according to one embodiment of the present invention" may be referred to as "the present resin composition."

[0015] The molded article has the advantages of being excellent in strength and having reduced whitening.

[0016] The molded article contains a recycled polyester resin. Therefore, one embodiment of the present invention can significantly reduce the amount of plastic waste generated and the amount of plastic used in manufacturing. As a result, one embodiment of the present invention can contribute to the achievement of Sustainable Development Goals (SDGs), such as Goal 12, "Ensure sustainable consumption and production patterns."

[0017] [1-1. Resin composition] The present molded article is obtained by molding a resin composition containing a recycled polyester resin. It can also be said that the present molded article contains a resin composition containing a recycled polyester resin.

[0018] (1-1-1. Recycled polyester resin) In this specification, the term "recycled polyester resin" refers to a polyester resin obtained by recycling the following (i) and / or (ii): (i) a polyester resin composition and / or a molded article that was once manufactured as a polyester resin composition and / or a molded article, and then used and / or discarded; (ii) a discarded polyester resin composition and / or a discarded molded article that is discharged during the production process of a polyester resin composition and / or a molded article.

[0019] On the other hand, in this specification, a polyester resin that has never been commercialized may be referred to as a “virgin polyester resin.” In this specification, the term “recycled polyester resin” also includes a mixture obtained by mixing a “virgin polyester resin” with a recycled polyester resin.

[0020] In this specification, "X resin obtained by recycling" may also be referred to as "recycled [X resin]."

[0021] The method for recycling polyester resins is not particularly limited, but known methods can be used, such as chemical recycling, material recycling, and thermal recycling.

[0022] The polyester resin may be an aromatic polyester having a structure in which an aromatic dicarboxylic acid or its ester derivative component and a diol component such as an aliphatic diol or an alicyclic diol are linked by an ester reaction, or may be one obtained by polycondensation of the aromatic dicarboxylic acid or its ester derivative component and the diol component such as an aliphatic diol or an alicyclic diol by a known method.

[0023] The aromatic dicarboxylic acid is not particularly limited, and examples thereof include phthalic acid, terephthalic acid, isophthalic acid, orthophthalic acid, 1,5-naphthalenedicarboxylic acid, 2,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 2,2'-biphenyldicarboxylic acid, 3,3'-biphenyldicarboxylic acid, 4,4'-biphenyldicarboxylic acid, 4,4'-diphenylethercarboxylic acid, 4,4'-diphenyletherdicarboxylic acid, 4,4'-diphenylmethanedicarboxylic acid, 4,4'-diphenylsulfonedicarboxylic acid, 4,4'-diphenylisopropylidenedicarboxylic acid, 1,2-bis(phenoxy)ethane-4,4'-dicarboxylic acid, bis(4,4-carboxyphenyl)methane, anthracenedicarboxylic acids (e.g., 2,5-anthracenedicarboxylic acid, 2,6-anthracenedicarboxylic acid, etc.), 4,4'-p-terphenylenedicarboxylic acid, and 2,5-pyridinedicarboxylic acid. The aromatic dicarboxylic acid may be used alone or in combination of two or more kinds.

[0024] The aliphatic diol is not particularly limited, and examples thereof include ethylene glycol, propylene glycol, butylene glycol, hexylene glycol, neopentyl glycol, 2-methyl-1,3-propanediol, diethylene glycol, triethylene glycol, 1,5-pentanediol, 1,6-hexanediol, decamethylene glycol, bisphenol A ethylene oxide addition diol, polyethylene oxide glycol, polypropylene oxide glycol, etc. Examples of alicyclic diols include 1,4-cyclohexanedimethanol, 4,4-dicyclohexylhydroxymethane, 4,4'-dicyclohexylhydroxypropane, etc. As the diol component, only one type may be used, or two or more types may be used in combination.

[0025] The polyester resin may be a polymer formed by copolymerizing an aromatic dicarboxylic acid or its ester derivative component as a main component, an aliphatic diol, and another dicarboxylic acid or its ester derivative component or diol. Examples of the other dicarboxylic acid include alicyclic dicarboxylic acids such as 1,4-cyclohexanedicarboxylic acid and 4,4'-dicyclohexyldicarboxylic acid.

[0026] The polyester resin may have a structural component derived from a tri- or higher functional monomer such as glycerin, trimethylolpropane, pentaerythritol, trimellitic acid, or pyromellitic acid.

[0027] Specific examples of recycled polyester resins include, but are not limited to, recycled polyethylene terephthalate, recycled polypropylene terephthalate, recycled polybutylene terephthalate, recycled polyethylene-2,6-naphthalate, recycled polybutylene naphthalate, recycled poly-1,4-cyclohexylene dimethylene terephthalate, recycled polyethylene-1,2-bis(phenoxy)ethane-4,4'-dicarboxylate, recycled polyethylene isophthalate / terephthalate, recycled polybutylene terephthalate / isophthalate, recycled polybutylene terephthalate / decanedicarboxylate, recycled polycyclohexanedimethylene terephthalate / isophthalate, recycled polyester / polyether, and recycled glycol-modified polyethylene terephthalate. Glycol-modified polyethylene terephthalate refers to a copolymer of terephthalic acid, ethylene glycol, and a glycol component other than ethylene glycol.

[0028] From the viewpoint of moldability and mechanical properties, the polyester-based resin preferably contains one or more selected from the group consisting of recycled [polypropylene terephthalate], recycled [polybutylene terephthalate], recycled [polyethylene-2,6-naphthalate], recycled [polybutylene naphthalate], recycled [poly-1,4-cyclohexylene dimethylene terephthalate], and recycled [polyester / polyether], and may consist of only one or more selected from this group; and more preferably contains one or more selected from the group consisting of recycled [polyethylene terephthalate] and recycled [polybutylene terephthalate], and may consist of only one or more selected from this group.

[0029] The recycled polyester resin may be a recycled polymer alloy obtained by recycling a polymer alloy obtained from a mixture of multiple polymers containing a polyester resin. Examples of recycled polymer alloys include recycled polycarbonate / polyethylene terephthalate, recycled polyethylene terephthalate / glycol-modified polyethylene terephthalate, and recycled polyethylene terephthalate / copolymerized polyethylene terephthalate. In other words, the recycled polyester resin may contain one or more materials selected from the group consisting of recycled polycarbonate / polyethylene terephthalate, recycled polyethylene terephthalate / glycol-modified polyethylene terephthalate, and recycled polyethylene terephthalate / copolymerized polyethylene terephthalate, or may consist solely of one or more materials selected from this group. This configuration has the advantage of being easily available. Copolymerized polyethylene terephthalate refers to a resin in which a component (a third component) other than the two components constituting polyethylene terephthalate is copolymerized.

[0030] (1-1-2. Whitening inhibitor) The present molded article is preferably molded using a whitening inhibitor. In other words, the resin composition preferably contains a whitening inhibitor. By molding using a whitening inhibitor, (i) the melt viscosity of the resin composition can be improved, and the strength of the molded article made from the resin composition can be increased, and (ii) whitening of the molded article containing the recycled polyester resin can be suppressed.

[0031] The whitening inhibitor is not particularly limited. For example, a whitening inhibitor for polyester resins having the following composition is preferably used: a whitening inhibitor for polyester resins containing a polymer (A) obtained by polymerizing a monomer mixture (A) containing: (a) 10 parts by weight to 60 parts by weight of an epoxy group-containing alkyl (meth)acrylate, and (b) 40 parts by weight to 90 parts by weight of an epoxy group-free alkyl (meth)acrylate.

[0032] As the whitening inhibitor, for example, a whitening inhibitor for polyester resins according to one embodiment of the present invention described in the section [2. Whitening inhibitor] below, for example, a whitening inhibitor for polyester resins having the following configuration, can also be suitably used: a whitening inhibitor for polyester resins comprising a polymer (A) obtained by polymerizing a monomer mixture (A) containing (a) 10% by weight to 60% by weight of an epoxy group-containing monomer, and (b) 40% by weight to 90% by weight of an epoxy group-free monomer.

[0033] (Polymer (A)) In this specification, "(a) epoxy group-containing monomer" may be referred to as "component (a)," and "(b) epoxy group-free monomer" may be referred to as "component (b)."

[0034] In this specification, the term "(a) epoxy group-containing monomer" refers to a monomer containing an epoxy group.

[0035] The epoxy group has good reactivity with the terminal functional group of the recycled polyester resin, and therefore, the whitening inhibitor preferably contains (a) an epoxy group-containing monomer.

[0036] A case where the resin composition contains a whitening inhibitor will be described. In this case, during the production process of a resin composition containing a recycled polyester resin and a whitening inhibitor (for example, during melt-kneading of the recycled polyester resin and the whitening inhibitor), a reactive functional group (e.g., an epoxy group) in the polymer (A) contained in the whitening inhibitor can react with a terminal functional group (e.g., a hydroxyl group or a carboxyl group) of the recycled polyester resin. This reaction can elongate the molecular chain of the recycled polyester resin; this mechanism improves the melt viscosity of the resin composition and improves the strength of the molded article. Furthermore, when the whitening inhibitor contains the above-mentioned polymer (A), the dispersibility of the whitening inhibitor in the resin composition can be improved. It is presumed that this suppresses whitening of the molded article. However, the present invention is not limited to these mechanisms and presumptions.

[0037] The epoxy group-containing monomer (a) is not particularly limited. In one embodiment of the present invention, the epoxy group-containing monomer is preferably an epoxy group-containing alkyl (meth)acrylate. The following description will focus on the epoxy group-containing alkyl (meth)acrylate as component (a).

[0038] Examples of component (a) include, but are not limited to, glycidyl acrylate, glycidyl methacrylate, 4-hydroxybutyl acrylate glycidyl ether, 3,4-epoxycyclohexyl (meth)acrylate, allyl glycidyl ether, β-methylglycidyl (meth)acrylate, etc. As component (a), only one type may be used, or two or more types may be used in combination.

[0039] From the viewpoint of polymerization productivity, the component (a) preferably contains (i) one or more selected from the group consisting of glycidyl acrylate, glycidyl methacrylate, 4-hydroxybutyl acrylate glycidyl ether, 3,4-epoxycyclohexyl (meth)acrylate, and β-methylglycidyl (meth)acrylate, and may consist of only one or more selected from this group, and more preferably contains (ii) one or more selected from the group consisting of glycidyl acrylate, glycidyl methacrylate, 4-hydroxybutyl acrylate glycidyl ether, and 3,4-epoxycyclohexyl (meth)acrylate. (iii) It is more preferable that the composition contains one or more selected from the group consisting of glycidyl acrylate, glycidyl methacrylate, and 4-hydroxybutyl acrylate glycidyl ether, and may consist of one or more selected from the group; (iv) It is particularly preferable that the composition contains one or more selected from the group consisting of glycidyl acrylate and glycidyl methacrylate, and may consist of one or more selected from the group; and (v) It is most preferable that the composition contains glycidyl methacrylate, and may consist of glycidyl methacrylate alone.

[0040] The content of component (a) in the monomer mixture (A) is not particularly limited, but is preferably 10 to 60% by weight based on 100% by weight of the monomer mixture (A). The upper limit may be 55, 50, 45, or 40% by weight, and the lower limit may be 15, 20, 25, or 30% by weight. When the content of component (a) is within the above range, the effect of improving the melt viscosity of the resin composition can be improved. As a result, the moldability and strength of the molded article are advantageously excellent. In this specification, "excellent moldability of the molded article" means that the thickness distribution of the molded article is more uniform.

[0041] In this specification, "(b) epoxy group-free monomer" refers to a monomer other than "(a) epoxy group-containing monomer", that is, a monomer that does not contain an epoxy group.

[0042] Component (b) is preferably an alkyl(meth)acrylate that does not have a reactive functional group (for example, an alkyl(meth)acrylate that does not contain an epoxy group). Specific examples of alkyl(meth)acrylates that do not have a reactive functional group include alkyl(meth)acrylates that have an alkyl group having 1 to 22 carbon atoms, such as methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, octyl (meth)acrylate, dodecyl (meth)acrylate, stearyl (meth)acrylate, and behenyl (meth)acrylate.

[0043] As the component (b), only one of the above-mentioned monomers may be used, or two or more of them may be used in combination.

[0044] The number of carbon atoms in the alkyl group in component (b) is not particularly limited, but from the viewpoint of polymerizability, it is preferably 22 or less. Furthermore, from the viewpoint of compatibility with recycled polyester resins, the number of carbon atoms in the alkyl group in component (b) is more preferably 12 or less, even more preferably 8 or less, and particularly preferably 1 to 4.

[0045] From the viewpoint of dispersibility of the whitening inhibitor, component (b) preferably contains one or more selected from the group consisting of epoxy group-free alkyl methacrylates, and may consist of only one or more selected from this group; (ii) more preferably contains one or more selected from the group consisting of methyl methacrylate, ethyl methacrylate, propyl methacrylate, and butyl methacrylate, and may consist of only one or more selected from this group; (iii) still more preferably contains one or more selected from the group consisting of methyl methacrylate and butyl methacrylate, and may consist of only one or more selected from this group; and (iv) most preferably contains methyl methacrylate, and may consist of only methyl methacrylate.

[0046] The content of component (b) in the monomer mixture (A) is not particularly limited, but is preferably 40 to 90% by weight based on 100% by weight of the monomer mixture (A). The upper limit may be 85, 80, 75, or 70% by weight, and the lower limit may be 45, 50, 55, or 60% by weight. A content of component (b) within the above range has the advantage of improving the dispersibility of the whitening inhibitor within the resin composition. As a result, there is also the advantage that whitening of the resulting molded article is further suppressed.

[0047] It is preferable that the monomer mixture (A) further contains (c) a vinyl monomer other than the components (a) and (b) that is copolymerizable with the components (a) and (b). In this specification, "(c) a vinyl monomer other than the components (a) and (b) that is copolymerizable with the components (a) and (b)" may be referred to as "component (c)."

[0048] Examples of the component (c) include, but are not limited to, one or more selected from the group consisting of vinyl cyanide compounds, aromatic vinyl compounds, (meth)acrylic acid, and the like.

[0049] Examples of the vinyl cyanide compound include acrylonitrile and methacrylonitrile.

[0050] The aromatic vinyl compound is not particularly limited, but examples thereof include styrene, vinyltoluene, α-methylstyrene, 4-methylstyrene, 3-methylstyrene, 4-methoxystyrene, 4-ethylstyrene, 4-ethoxystyrene, 3,4-dimethylstyrene, 2-chlorostyrene, 3-chlorostyrene, 4-chloro-3-methylstyrene, 3-(tert-butyl)styrene, 2,4-dichlorostyrene, 2,6-dichlorostyrene, and 1-vinylnaphthalene.

[0051] As the component (c), only one of the above-mentioned monomers may be used, or two or more of them may be used in combination.

[0052] From the viewpoint of polymerization productivity, the component (c) preferably contains (i) one or more selected from the group consisting of 4-methylstyrene, 3-methylstyrene, α-methylstyrene, and styrene, and may consist of only one or more selected from this group; (ii) more preferably contains one or more selected from the group consisting of 4-methylstyrene, α-methylstyrene, and styrene, and may consist of only one or more selected from this group; (iii) further preferably contains one or more selected from the group consisting of α-methylstyrene and styrene, and may consist of only one or more selected from this group; and (iv) most preferably contains styrene, and may consist of only styrene.

[0053] On the other hand, since a molded article with reduced whitening can be provided, the content of aromatic vinyl compounds (particularly styrene) in the monomer mixture (A) is preferably as low as possible. The content of aromatic vinyl compounds in 100% by weight of the monomer mixture (A) is preferably 10% by weight or less, more preferably 5% by weight or less, even more preferably 3% by weight or less, and particularly preferably 1% by weight or less. It is most preferable that the content of aromatic vinyl compounds in 100% by weight of the monomer mixture (A) is 0% by weight, i.e., it is most preferable that the monomer mixture (A) does not contain an aromatic vinyl compound. Since a molded article with further reduced whitening can be provided, the content of styrene in 100% by weight of the monomer mixture (A) is preferably 10% by weight or less, more preferably 5% by weight or less, even more preferably 3% by weight or less, and particularly preferably 1% by weight or less. It is most preferable that the content of styrene in 100% by weight of the monomer mixture (A) is 0% by weight, that is, it is most preferable that the monomer mixture (A) does not contain styrene.

[0054] The content of component (c) in the monomer mixture (A) is not particularly limited, but is preferably 0 to 10% by weight relative to 100% by weight of the monomer mixture (A). The upper limit may be 8% by weight or 5% by weight, and the lower limit may be 2% by weight or 4% by weight. If the content of component (c) is within the above range, there is an advantage in that productivity is improved.

[0055] From the viewpoint of balancing the thermal stability and productivity of the whitening inhibitor and improving the melt viscosity of the resin composition, the number average molecular weight of the polymer (A) is preferably in the range of 2,000 to 6,000. The lower limit of the number average molecular weight of the polymer (A) is more preferably 3,000 or more, and may be 4,000 or more. The upper limit of the number average molecular weight of the polymer (A) is more preferably 5,500 or less, more preferably 5,000 or less, even more preferably 4,500 or less, particularly preferably 4,000 or less, and may be 3,500 or less. The number average molecular weight of the polymer (A) can be adjusted by using a chain transfer agent during polymerization of the polymer (A). In other words, to obtain a polymer (A) having a number average molecular weight within the above-mentioned range, it is preferable to use a chain transfer agent during polymerization of the polymer (A). The number average molecular weight of the polymer (A) can be measured by gel permeation chromatography (GPC) and calculated in terms of polystyrene equivalent molecular weight. The method for measuring the number average molecular weight of the polymer (A) will be described in detail in the Examples below.

[0056] The polymer (A) preferably has an average of 2 to 15 reactive functional groups per molecule of the polymer (A). The lower limit may be 3 or more. The upper limit may be 13 or less, 11 or less, 9 or less, or 8 or less. When the number of reactive functional groups in the polymer (A) is within the above range, the melt viscosity of the resin composition can be suitably improved without gelation occurring or impairing the mechanical properties, heat resistance, rheological properties, etc. of the molded article.

[0057] The polymer (A) is preferably a non-rubber polymer. A non-rubber polymer refers to a polymer that does not have a crosslinked structure between molecular chains of the polymer. When the polymer (A) is a non-rubber polymer, the reaction between the reactive functional group (e.g., epoxy group) of the polymer (A) and the terminal functional group of the recycled polyester resin proceeds more efficiently, which is advantageous in that the melt viscosity of the resin composition is easily improved.

[0058] (Method for Producing Polymer (A)) The polymerization method for the polymer (A) may be any known method, and is not particularly limited. For example, bulk polymerization, solution polymerization, suspension polymerization, emulsion polymerization, etc. may be employed, with emulsion polymerization being preferred.

[0059] The polymer (A) is preferably a polymer obtained by emulsion polymerization. In other words, the production of the whitening inhibitor preferably includes a step of obtaining the polymer (A) by emulsion polymerization. In this specification, "emulsion polymerization" means carrying out a polymerization reaction in the presence of an emulsifier, which will be described later. Furthermore, during the emulsion polymerization, the emulsifier may react to produce a salt derived from the emulsifier. Therefore, when the polymer (A) is a polymer obtained by emulsion polymerization, the polymer (A) may contain the emulsifier, which will be described later, and / or a salt derived from the emulsifier. In other words, a polymer containing the emulsifier, which will be described later, and / or a salt derived from the emulsifier can also be considered a polymer obtained by emulsion polymerization.

[0060] When producing the polymer (A), it is preferable to carry out polymerization in the presence of a chain transfer agent in order to control the molecular weight. In other words, it is preferable that the monomer mixture (A) contains a chain transfer agent.

[0061] The chain transfer agent is not particularly limited, but examples thereof include primary mercaptan chain transfer agents such as n-butyl mercaptan, n-octyl mercaptan, n-hexadecyl mercaptan, n-dodecyl mercaptan, and n-tetradecyl mercaptan; secondary mercaptan chain transfer agents such as sec-butyl mercaptan and sec-dodecyl mercaptan; tertiary mercaptan chain transfer agents such as t-dodecyl mercaptan; mercaptan compounds; thioglycolic acid esters such as 2-ethylhexyl thioglycolate, ethylene glycol dithioglycolate, trimethylolpropane tris(thioglycolate), and pentaerythritol tetrakis(thioglycolate); thiophenol; tetraethylthiuram disulfide; pentane phenyl ethane; acrolein; methacrolein; allyl alcohol; carbon tetrachloride; ethylene bromide; styrene oligomers such as α-methylstyrene dimer; and terpinolene. The chain transfer agent may be used alone or in combination of two or more. The amount of the chain transfer agent used may be appropriately determined depending on the desired number average molecular weight of the polymer (A).

[0062] The emulsifier (dispersant) that can be used in emulsion polymerization is not particularly limited, and examples thereof include anionic surfactants, nonionic surfactants, cationic surfactants, and amphoteric surfactants. Dispersants such as polyvinyl alcohol, alkyl-substituted cellulose, polyvinylpyrrolidone, and polyacrylic acid derivatives may also be used. The emulsifier (dispersant) may be used alone or in combination of two or more.

[0063] When emulsion polymerization is employed, a thermally decomposable initiator can be used as the radical polymerization initiator, such as known initiators such as 2,2'-azobisisobutyronitrile, hydrogen peroxide, potassium persulfate, and ammonium persulfate.

[0064] A redox initiator can also be used as the radical polymerization initiator. The redox initiator is an initiator obtained by combining (a) a peroxide, such as an organic peroxide or an inorganic peroxide, with (b) optionally a reducing agent, such as sodium formaldehyde sulfoxylate or glucose, and optionally a transition metal salt, such as iron (II) sulfate, and optionally a chelating agent, such as disodium ethylenediaminetetraacetate, and optionally a phosphorus-containing compound, such as sodium pyrophosphate. Examples of the organic peroxide include t-butylperoxyisopropyl carbonate, paramenthane hydroperoxide, cumene hydroperoxide, dicumyl peroxide, t-butyl hydroperoxide, di-t-butyl peroxide, and t-hexyl peroxide. Examples of the inorganic peroxide include hydrogen peroxide, potassium persulfate, and ammonium persulfate.

[0065] When a redox initiator is used, polymerization can be carried out even at a low temperature where the peroxide does not substantially decompose thermally, and the polymerization temperature can be set over a wide range. Therefore, it is preferable to use a redox initiator. Among redox initiators, redox initiators using organic peroxides such as cumene hydroperoxide, dicumyl peroxide, paramenthane hydroperoxide, and t-butyl hydroperoxide as the peroxide are preferred. The amount of the initiator used, and when a redox initiator is used, the amounts of the reducing agent, transition metal salt, chelating agent, etc. used can be within known ranges.

[0066] In the polymerization of the polymer (A), a known surfactant may also be used.

[0067] When the polymer (A) is produced by emulsion polymerization, a latex containing the polymer (A) (e.g., an aqueous latex) can be obtained. The polymer (A) can be obtained by separating the polymer (A) from the latex containing the polymer (A). The obtained polymer (A) can be used as a whitening inhibitor. The method for separating the polymer (A) from the latex containing the polymer (A) is not particularly limited, and examples include salting out the polymer (A) using an acid and a metal salt, and precipitating the polymer (A) using an organic solvent. The polymer (A) separated from the latex containing the polymer (A) may be washed and further dried. A powder of the polymer (A) (also referred to as "powder") can be obtained by separating the polymer (A) from the latex containing the polymer (A), washing it, and further drying it. Alternatively, a powder of the polymer (A) can be obtained by spray-drying the latex containing the polymer (A). The powder of the polymer (A) obtained in this manner can be used as a whitening inhibitor.

[0068] (Polymer (B)) The whitening inhibitor may or may not contain polymer (B) in addition to polymer (A). The polymer component in the whitening inhibitor may be composed of only polymer (A), may be composed of only polymer (A) and polymer (B), or may be composed of polymer (A), polymer (B) and polymers other than these.

[0069] A case where the whitening inhibitor contains a polymer (A) and a polymer (B) (hereinafter also referred to as "Case A") will be described. In Case A, it is preferable to polymerize the polymer (A) and then polymerize the polymer (B) in the presence of the polymer (A). In Case A, when the polymer (A) is obtained, for example, by emulsion polymerization, it is particularly preferable to produce (polymerize) the polymer (A) and then produce (polymerize) the polymer (B) in a latex containing the polymer (A). When the polymer (B) is produced (polymerized) in a latex containing the polymer (A), a composite consisting of the polymer (A) and the polymer (B) (or containing the polymer (A) and the polymer (B)) can be obtained. In the composite, the polymer (B) can cover a portion of the polymer (A). Therefore, in the composite, the polymer (A) can be referred to as the core portion and the polymer (B) as the shell portion. The composite can have a core-shell structure having the polymer (A) as the core portion and the polymer (B) as the shell portion. In other words, when producing (polymerizing) polymer (B) in a latex containing polymer (A), a composite consisting of polymer (A) and polymer (B) can be obtained, in which polymer (A) forms a core and polymer (B) forms a shell, i.e., a composite having a core-shell structure. In the composite, polymer (B) may cover the entire polymer (A) or may be impregnated into the particulate polymer (A).

[0070] When the whitening inhibitor contains the polymer (A) and the polymer (B) and the composite made of the polymer (A) and the polymer (B) has a core-shell structure in which the polymer (A) forms the core and the polymer (B) forms the shell, there is an advantage in that productivity is improved.

[0071] The polymer (B) is not particularly limited. The composition of the structural units of the polymer (B) may be the same as or different from the composition of the structural units of the polymer (A). In other words, the composition of the monomer mixture (B) may be the same as or different from the composition of the monomer mixture (A).

[0072] The polymer (B) is preferably a polymer obtained by polymerizing a monomer mixture (B) containing (a) 10 to 60% by weight of an epoxy group-containing monomer and (b) 40 to 90% by weight of an epoxy group-free monomer. The polymer (B) preferably further contains (c) 0 to 10% by weight of a vinyl monomer other than the components (a) and (b) that is copolymerizable with the components (a) and (b).

[0073] The number average molecular weight of polymer (B) is preferably different from that of polymer (A). The number average molecular weight of polymer (B) is more preferably larger than that of polymer (A). This configuration increases the softening point of the polymer (composite), making it less likely for problems such as sticking to occur. As a result, there is an advantage in that productivity is improved.

[0074] It is preferable that polymer (B) is a non-rubber polymer. This configuration has the advantage that the reaction between the reactive functional group of polymer (B) and the terminal functional group of the recycled polyester resin proceeds more efficiently, making it easier to improve the melt viscosity of the resin composition. In case A, (i) it is preferable that polymer (A) is a non-rubber polymer or polymer (B) is a non-rubber polymer, and it is more preferable that both polymer (A) and polymer (B) are non-rubber polymers (for example, the entire complex is a non-rubber polymer).

[0075] The following describes a case where the whitening inhibitor contains a polymer (A) and a polymer (B), and the composite made of the polymer (A) and the polymer (B) has a core-shell structure in which the polymer (A) forms the core and the polymer (B) forms the shell (hereinafter also referred to as "Case B"). In Cases A and B, the ratio of the weight of the polymer (A) to the weight of the polymer (B) in the composite (weight of polymer (A) / weight of polymer (B)) is not particularly limited, but is preferably 20 / 80 to 80 / 20, more preferably 30 / 70 to 70 / 30, even more preferably 35 / 65 to 65 / 35, and particularly preferably 40 / 60 to 60 / 40. When the weight ratio of the polymer (A) to the polymer (B) in the composite is within the above range, there is an advantage in that productivity is improved.

[0076] In Case B, the number average molecular weight of the polymer (A) is not particularly limited, but is preferably 2,000 to 5,000, more preferably 2,000 to 4,000, even more preferably 2,500 to 4,000, and particularly preferably 2,500 to 3,500. This configuration has the advantage of improving the balance between improving melt viscosity and suppressing whitening. In Cases A and B, the number average molecular weight of the polymer (B) is not particularly limited, but is preferably 3,000 to 6,000, more preferably 3,000 to 5,000, even more preferably 3,500 to 5,000, and particularly preferably 3,500 to 4,500. This configuration has the advantage of improving productivity.

[0077] The polymer (B) preferably has an average of 2 to 15 reactive functional groups per molecule of the polymer (B). The lower limit may be 3 or more. The upper limit may be 13 or less, 11 or less, or 9 or less. When the number of reactive functional groups in the polymer (B) is within the above range, gelation does not occur and the melt viscosity of the resin composition can be suitably improved without impairing the mechanical properties, heat resistance, rheological properties, etc. of the molded article.

[0078] The polymer (A) and the polymer (B) may differ in one or more properties selected from the group consisting of the composition of the structural units, the number average molecular weight, the average number of reactive functional groups per molecule, and the epoxy equivalent.

[0079] (Method for Producing Polymer (B)) The polymerization method for the polymer (B) can be any known method and is not particularly limited. For example, bulk polymerization, solution polymerization, suspension polymerization, emulsion polymerization, etc. can be employed, with emulsion polymerization being preferred. When producing the polymer (B), it is preferable to carry out polymerization in the presence of a chain transfer agent in order to control the molecular weight. In other words, the monomer mixture (B) preferably contains a chain transfer agent.

[0080] Regarding the polymer (B), the descriptions in the section on [polymer (A)] can be appropriately cited for matters other than those mentioned above. For example, with regard to the types and contents of the components (a), (b), and (c) contained in the monomer mixture (B), the preferred embodiments for the polymer (A) (monomer mixture (A)) are also preferred for the polymer (B) (monomer mixture (B)).

[0081] The whitening inhibitor preferably contains a smaller amount of polymers having a molecular weight of 1000 or less. The smaller the amount of polymers having a molecular weight of 1000 or less in the whitening inhibitor, the more advantageously it can be used in food applications.

[0082] The content of the polymer having a molecular weight of 1000 or less in the whitening inhibitor is not particularly limited, but is preferably 4.00 wt% or less, more preferably 3.00 wt% or less, even more preferably 2.00 wt% or less, and particularly preferably 1.00 wt% or less, based on 100 wt% of the whitening inhibitor. This configuration has the advantage of being suitable for use in food products. The lower limit of the content of the polymer having a molecular weight of 1000 or less in the whitening inhibitor is 0.00 wt%, i.e., the whitening inhibitor does not need to contain a polymer having a molecular weight of 1000 or less.

[0083] The whitening inhibitor preferably contains a smaller amount of polymer (A) having a molecular weight of 1000 or less. The amount of polymer (A) having a molecular weight of 1000 or less in the whitening inhibitor is not particularly limited, but is preferably 4.00% by weight or less, more preferably 3.00% by weight or less, even more preferably 2.00% by weight or less, and particularly preferably 1.00% by weight or less, based on 100% by weight of the whitening inhibitor. This configuration has the advantage of being suitable for use in food products. The lower limit of the amount of polymer (A) having a molecular weight of 1000 or less in the whitening inhibitor is 0.00% by weight, i.e., the whitening inhibitor does not need to contain polymer (A) having a molecular weight of 1000 or less.

[0084] In Case A, the whitening inhibitor preferably contains a smaller amount of polymer (B) having a molecular weight of 1000 or less. In Case A, the amount of polymer (B) having a molecular weight of 1000 or less in the whitening inhibitor is not particularly limited, but is preferably 4.00% by weight or less, more preferably 3.00% by weight or less, even more preferably 2.00% by weight or less, and particularly preferably 1.00% by weight or less, based on 100% by weight of the whitening inhibitor. This configuration has the advantage of being suitable for food applications. In Case A, the lower limit of the amount of polymer (B) having a molecular weight of 1000 or less in the whitening inhibitor is 0.00% by weight, i.e., the whitening inhibitor does not need to contain polymer (B) having a molecular weight of 1000 or less.

[0085] The content of the whitening inhibitor in the resin composition is not particularly limited. The content of the whitening inhibitor in the resin composition is preferably 0.1 wt % to 10.0 wt % based on 100 wt % of the resin composition. The lower limit of the content is more preferably 0.2 wt % or more. The upper limit of the content may be 8.0 wt % or less, 6.0 wt % or less, or 4.0 wt % or less. When the content of the whitening inhibitor in the resin composition is within the above range, there is an advantage in that a good balance between improvement in melt viscosity and whitening inhibition is achieved.

[0086] In the resin composition, the recycled polyester resin and the whitening inhibitor may react. More specifically, in the resin composition, the reactive functional group (e.g., an epoxy group) of the reactive functional group-containing unit in the polymer (A) contained in the whitening inhibitor may react with a terminal functional group (e.g., a hydroxyl group or a carboxyl group) of the recycled polyester resin. As a result of this reaction, a resin having structural units derived from the recycled polyester resin and structural units derived from the whitening inhibitor may be formed. Therefore, in the resin composition, (i) at least a portion of the recycled polyester resin may react with the whitening inhibitor to exist as structural units derived from the recycled polyester resin, (ii) at least a portion of the whitening inhibitor may react with the recycled polyester resin to exist as structural units derived from the whitening inhibitor, and (iii) in the structural units derived from the whitening inhibitor, for example, the epoxy group of the polymer (A) may exist in a covalently bonded state to the terminal of the structural unit derived from the recycled polyester resin. In this specification, the phrase "a resin composition containing a recycled polyester resin and a whitening inhibitor" also includes cases where the recycled polyester resin and the whitening inhibitor are present in the resin composition as structural units derived from the recycled polyester resin and structural units derived from the whitening inhibitor, respectively.

[0087] (1-1-3. Other Resins) The resin composition may or may not further contain a resin other than the recycled polyester-based resin. The resin other than the recycled polyester-based resin is not particularly limited, but examples thereof include virgin polyester-based resin, polyethylene, polypropylene, polyvinyl chloride, polystyrene, polyvinyl acetate, polyurethane, polytetrafluoroethylene, ABS resin, AS resin, acrylic resin, polyacetal, polycarbonate, modified polyphenylene ether, polyamide, and cyclic polyolefin.

[0088] The content of the resin other than the recycled polyester resin in the resin composition is not particularly limited, but may be, for example, 0 to 60 parts by weight per 100 parts by weight of the recycled polyester resin. The upper limit of the content may be 50 parts by weight or less, 40 parts by weight or less, 30 parts by weight or less, 20 parts by weight or less, 10 parts by weight or less, 5 parts by weight or less, or 1 part by weight or less.

[0089] In the present resin composition, the content of resins other than polyester-based resins including recycled polyester-based resins and virgin polyester-based resins is not particularly limited. In the present resin composition, the content of resins other than polyester-based resins relative to 100 parts by weight of polyester-based resins, i.e., 100 parts by weight of the total amount of recycled polyester-based resins and virgin polyester-based resins, may be 0 to 60 parts by weight. The upper limit of the content may be 50 parts by weight or less, 40 parts by weight or less, 30 parts by weight or less, 20 parts by weight or less, 10 parts by weight or less, 5 parts by weight or less, or 1 part by weight or less.

[0090] (1-1-4. Other Additives) The present molded article may be molded using other additives. In other words, the present resin composition may contain other additives. The other additives are not particularly limited, but examples thereof include flame retardants, flame retardant aids, anti-dripping agents, reinforcing agents, fillers, antioxidants, pigments, dyes, conductivity imparting agents, hydrolysis inhibitors, thickeners, plasticizers, lubricants, ultraviolet absorbers, antistatic agents, flow improvers, mold release agents, compatibilizers, and heat stabilizers.

[0091] (1-1-5. Method for producing resin composition) The method for producing the resin composition is not particularly limited, and general methods for producing resin compositions can be applied. For example, the resin composition can be obtained by mixing raw materials (e.g., recycled polyester resin and whitening inhibitor) using a Henschel mixer or a tumbler mixer, and then melt-kneading the resulting mixture. For the melt-kneading, a kneader such as a single-screw or twin-screw extruder, a Banbury mixer, a pressure kneader, or a mixing roll can be used. Pellets made of the resin composition can be produced by such melt-kneading.

[0092] (1-1-6. Physical Properties of Resin Composition) The higher the melt viscosity (IV value) of a resin composition, the more excellent the strength of a molded article that can be provided by the resin composition. In other words, it is preferable that the melt viscosity (IV value) of the resin composition is high. The method for measuring the melt viscosity (IV value) of a resin composition will be described in detail in the Examples below.

[0093] The smaller the MFR of a resin composition, the stronger a molded article can be provided from the resin composition. In other words, it is preferable that the resin composition has a small MFR.

[0094] The melt flow rate (MFR) of the resin composition is preferably 3.7 g / 10 min to 30.0 g / 10 min, more preferably 3.7 g / 10 min to 29.5 g / 10 min, more preferably 3.7 g / 10 min to 29.0 g / 10 min, more preferably 3.7 g / 10 min to 28.5 g / 10 min, even more preferably 3.7 g / 10 min to 28.0 g / 10 min, and particularly preferably 3.7 g / 10 min to 27.5 g / 10 min. When the melt flow rate (MFR) of the resin composition is within the above-mentioned range, the molded article has the advantage of excellent strength. The method for measuring the MFR of the resin composition will be explained in detail in the Examples below.

[0095] A technique known as solid-state polymerization (SSP) is known as a method for improving the melt viscosity (IV value) of recycled polyester resins. Molded articles obtained by molding a resin composition obtained by solid-state polymerization using recycled polyester resins as raw materials have the advantage that they do not whiten at all, or even if they whiten, the degree of whitening is very small. However, solid-state polymerization requires a large amount of energy because it is carried out for a long period of time under vacuum and high temperature. The haze of a solution obtained by dissolving a molded article obtained from a resin composition obtained by solid-state polymerization using recycled polyester resins as raw materials is, for example, about 1.0%. On the other hand, the haze of a solution obtained by dissolving a molded article obtained from this resin composition is, for example, 1.50% or more. In other words, if the haze of the solution obtained by dissolving a molded article is 1.50% or more, the molded article can be considered not to be a molded article obtained from a resin composition obtained by solid-state polymerization. In one embodiment of the present invention, the haze of the solution obtained by dissolving a molded article may be 2.00% or more, 2.50% or more, or 3.00% or more.

[0096] [1-2. Manufacturing method of molded article] The manufacturing method of the molded article, in other words, the molding method of the resin composition, is not particularly limited. As the manufacturing method of the molded article (the molding method of the resin composition), for example, injection molding, extrusion molding, blow molding, calendar molding, inflation molding, rotational molding, press molding, etc. can be used. Among these, blow molding is preferred. In other words, the molded article according to one embodiment of the present invention is preferably a molded article obtained by blow molding the present resin composition.

[0097] In this specification, the blow molding method may be a molding method in which only blow molding is performed using a resin composition, or a molding method performed in combination with other molding methods (e.g., injection molding, extrusion molding, calendar molding, etc.). As a molding method performed in combination with other molding methods, a two-step blow molding method is preferred. The two-step blow molding method is a molding method in which a resin composition is injection molded to obtain an injection-molded article in a first step, and then the injection-molded article is blow-molded in a second step.

[0098] [1-3. Physical Properties of Molded Articles] The degree of whitening of a molded article can be evaluated by the difference in L value (ΔL) between before and after tensioning a film (molded article) obtained by molding a resin composition into a film. Specifically, the resin composition is molded into a film, and a tensile test is performed on the resulting film (molded article). The smaller the difference in L value (ΔL) between before and after tensioning, the less whitening the molded article obtained using the resin composition will be. For example, in blow molding of a resin composition or an injection-molded article, the resin composition or the injection-molded article is molded while being stretched. The stretching of the film (molded article) in the tensile test can be said to simulate the stretching during blow molding of the resin composition or the injection-molded article. Therefore, the smaller the ΔL of the film (molded article), the less whitening the blow-molded article (e.g., a bottle-shaped article) obtained by blow molding will be.

[0099] In one embodiment of the present invention, ΔL is preferably 9.5 or less, more preferably 9.0 or less, more preferably 8.0 or less, more preferably 7.0 or less, even more preferably 6.0 or less, and particularly preferably 5.0 or less. The lower limit is not particularly limited, and is most preferably 0, but may be 1.0, 1.5, or 2.0. ΔL being in the above range means that whitening of the molded article is suppressed. The method for measuring ΔL of the film (molded article) will be explained in detail in the Examples below.

[0100] The haze of the present molded article is preferably 7.5 or less, more preferably 6.5 or less, more preferably 5.5 or less, more preferably 5.0 or less, even more preferably 4.5 or less, and particularly preferably 4.0 or less. The lower limit of the haze of the molded article is not particularly limited, and is, for example, 1.0. The haze of the molded article in the above range means that the molded article has high transparency. The method for measuring the haze of the molded article will be explained in detail in the Examples below.

[0101] The total light transmittance (TT) of the present molded product is preferably 80.0% or more, more preferably 80.5% or more, more preferably 81.0% or more, more preferably 81.5% or more, even more preferably 82.0% or more, and particularly preferably 82.5% or more. The upper limit of the total light transmittance (TT) of the molded product is not particularly limited, and is, for example, 100%. The total light transmittance (TT) of the molded product in the above range means that the molded product has high transparency. The method for measuring the total light transmittance (TT) of the molded product will be explained in detail in the Examples below.

[0102] The buckling strength of the molded article is preferably 200, more preferably 250, even more preferably 300, and particularly preferably 350. If the buckling strength of the molded article is within the above range, there is an advantage that the range of applications in which the molded article can be used is broadened. The method for measuring the buckling strength of the molded article will be described in detail in the Examples below.

[0103] [1-4. Shape of Molded Article] The shape of the present molded article is not particularly limited. Molded articles of various shapes can be obtained by using the resin composition and the various molding methods described above. Examples of the shape of the present molded article include a bottle shape, a sheet shape, a film shape, and a rod shape. Among these, the present molded article is preferably a bottle shape, more preferably a blow-molded article (molded article) obtained by blow molding, and particularly preferably a bottle-shaped blow-molded article (bottle-shaped molded article) obtained by blow molding.

[0104] 2. Whitening Inhibitor One embodiment of the present invention provides a whitening inhibitor.

[0105] While conventional viscosity modifiers improve the melt viscosity of resin compositions to a certain extent by mixing the viscosity modifier with a matrix resin (e.g., a polyester-based resin), they have the problem of whitening of molded articles produced by molding the resulting resin compositions. To address this problem, efforts have been made to make the refractive index of the matrix resin and the refractive index of the polymer, which is the main component of the viscosity modifier, as similar as possible. For example, when the matrix resin is a polyester-based resin, a technique has been developed in which a monomer mixture containing a certain amount of styrene in addition to a reactive functional group-containing monomer is used during polymerization of the polymer. The resin compositions obtained in this manner have a certain degree of transparency because the refractive index of the polyester-based resin is similar to that of the polymer. However, even when such resin compositions are used, the problem of whitening of molded articles still exists.

[0106] An additional object of one embodiment of the present invention is to provide a novel whitening inhibitor for polyester-based resins, which can provide a polyester-based resin composition that can provide a molded article having excellent strength and reduced whitening.

[0107] The present inventors have conducted extensive research, regardless of refractive index, in order to obtain a molded article with reduced whitening. As a result, the present inventors have independently and surprisingly obtained the novel finding that a whitening inhibitor containing a polymer (A) according to one embodiment of the present invention obtained by polymerizing a monomer mixture (A) containing specific amounts of each of the components (a), (b), and (c), or a monomer mixture (A) containing specific amounts of each of the components (a) and (b), can provide a molded article with reduced whitening.

[0108] That is, according to one embodiment of the present invention, it is possible to provide a polyester-based resin composition capable of providing a molded article having excellent strength and reduced whitening, and a whitening inhibitor for polyester-based resins.

[0109] [2-1. Whitening inhibitor for polyester-based resin] A whitening inhibitor for polyester-based resin according to one embodiment of the present invention comprises a polymer (A) obtained by polymerizing a monomer mixture (A) containing (a) 10% by weight to 60% by weight of an epoxy group-containing monomer and (b) 40% by weight to 90% by weight of a non-epoxy group-containing monomer.

[0110] In this specification, the "whitening inhibitor for polyester resins" may be simply referred to as the "whitening inhibitor."

[0111] The whitening inhibitor according to one embodiment of the present invention has the above-described structure, and therefore has the advantage of being able to provide a polyester resin composition that can provide a molded article having excellent strength and reduced whitening. It can also be said that the whitening inhibitor according to one embodiment of the present invention has the above-described structure, and therefore can provide a molded article having excellent strength and reduced whitening.

[0112] Specific embodiments of the whitening inhibitor are the same as those described above in the section (1-1-2. Whitening inhibitor), and therefore the description is incorporated herein by reference and will not be repeated here. The embodiments described as preferred embodiments in the section (1-1-2. Whitening inhibitor) are also preferred embodiments in this section (2-1. Whitening inhibitor for polyester resin).

[0113] Furthermore, when the description in the above section (1-1-2. Whitening inhibitor) is used as an explanation for this section [2-1. Whitening inhibitor for polyester-based resin], the "recycled polyester-based resin" in the above section (1-1-2. Whitening inhibitor) may be read as "polyester-based resin" in the explanation of this section [2-1. Whitening inhibitor for polyester-based resin], and the "resin composition" in the above section (1-1-2. Whitening inhibitor) may be read as "polyester-based resin composition" in the explanation of this section [2-1. Whitening inhibitor for polyester-based resin].

[0114] [2-2. Polyester Resin Composition] A polyester resin composition according to one embodiment of the present invention contains the whitening inhibitor according to one embodiment of the present invention described in the above section [2-1. Whitening inhibitor for polyester resin], i.e., the whitening inhibitor described in the above section (1-1-2. Whitening inhibitor), and a polyester resin.

[0115] The polyester resin composition according to one embodiment of the present invention has the above-described structure, and therefore has the advantage of being able to provide a molded article that is excellent in strength and exhibits reduced whitening.

[0116] The whitening inhibitor according to one embodiment of the present invention can react not only with recycled polyester resins as described above, but also with virgin polyester resins. Specifically, the reactive functional group (e.g., epoxy group) in the polymer (A) contained in the whitening inhibitor can react with a terminal functional group (e.g., hydroxyl group or carboxyl group) of the polyester resin. This reaction can elongate the molecular chain of the virgin polyester resin. That is, the whitening inhibitor according to one embodiment of the present invention can react with all polyester resins, regardless of whether they are recycled or virgin (unused), and can elongate the molecular chain of the polyester resin. Therefore, by mixing the whitening inhibitor according to one embodiment of the present invention with a polyester resin to form a polyester resin composition, (i) the melt viscosity of the polyester resin composition can be improved, thereby increasing the strength of a molded article made from the polyester resin composition, and (ii) whitening of a molded article containing the polyester resin can be suppressed.

[0117] (2-2-1. Polyester-Based Resins) Specific examples of polyester-based resins are not particularly limited, but include, for example, polyethylene terephthalate, polypropylene terephthalate, polybutylene terephthalate, polyethylene-2,6-naphthalate, polybutylene naphthalate, poly-1,4-cyclohexylene dimethylene terephthalate, polyethylene-1,2-bis(phenoxy)ethane-4,4'-dicarboxylate, polyethylene isophthalate / terephthalate, polybutylene terephthalate / isophthalate, polybutylene terephthalate / decanedicarboxylate, polycyclohexanedimethylene terephthalate / isophthalate, polyester / polyether, glycol-modified polyethylene terephthalate, etc. Glycol-modified polyethylene terephthalate refers to a copolymer of terephthalic acid, ethylene glycol, and a glycol component other than ethylene glycol.

[0118] From the viewpoint of moldability and mechanical properties, the polyester-based resin preferably contains (i) one or more selected from the group consisting of polypropylene terephthalate, polybutylene terephthalate, polyethylene-2,6-naphthalate, polybutylene naphthalate, poly-1,4-cyclohexylene dimethylene terephthalate, and polyester / polyether, and may consist of only one or more selected from this group, or more preferably contains (ii) one or more selected from the group consisting of polyethylene terephthalate and polybutylene terephthalate, and may consist of only one or more selected from this group.

[0119] As the polyester-based resin, a polymer alloy obtained from a mixture of multiple polymers containing a polyester-based resin may be used. Examples of the polymer alloy include polycarbonate / polyethylene terephthalate, polyethylene terephthalate / glycol-modified polyethylene terephthalate, and polyethylene terephthalate / copolymerized polyethylene terephthalate. In other words, the polyester-based resin may contain one or more selected from the group consisting of polycarbonate / polyethylene terephthalate, polyethylene terephthalate / glycol-modified polyethylene terephthalate, and polyethylene terephthalate / copolymerized polyethylene terephthalate, or may consist solely of one or more selected from this group. Copolymerized polyethylene terephthalate refers to a resin in which a component (third component) other than the components (two components) constituting polyethylene terephthalate is copolymerized.

[0120] Other aspects of the polyester resin than those described above are the same as those described in the above section (1-1-1. Recycled polyester resin), and therefore the description is incorporated herein by reference and will not be repeated here. In particular, the aspects described in the above section (1-1-1. Recycled polyester resin) other than the recycled aspect can be regarded as aspects related to polyester resin and can be incorporated as appropriate. The aspects described as preferred aspects in the above section (1-1-1. Recycled polyester resin) are also preferred aspects in this section (2-2-1. Polyester resin).

[0121] Conventionally, when the following (i) and (ii) are recycled, the resulting melt viscosity tends to decrease due to moisture and / or heat in the recycling process.

[0122] (i) A polyester resin composition and / or a molded article that has been once manufactured as a polyester resin composition and / or a molded article and then used and / or discarded; (ii) A discarded polyester resin composition and / or a discarded molded article that is discharged during the production process of a polyester resin composition and / or a molded article.

[0123] In other words, recycled polyester resins tend to have lower melt viscosities than virgin products. Therefore, conventionally, recycled polyester resins have tended to have limited applications for reuse due to their low melt viscosities. Furthermore, a technique for improving the melt viscosity of a resin composition containing recycled polyester resins to a certain extent by adding a viscosity modifier to the recycled polyester resin has also been known. However, molded articles obtained from resin compositions containing conventional viscosity modifiers have had the problem of whitening. Therefore, the whitening of the resulting molded articles has tended to limit the applications for reuse of recycled polyester resins. However, a whitening inhibitor according to one embodiment of the present invention has the advantages of being able to improve the melt viscosity of the resulting resin composition by mixing with a recycled polyester resin and providing a molded article with reduced whitening. Therefore, one embodiment of the present invention has the advantage of greatly expanding the applications of recycled polyester resins, particularly in applications requiring strength and high transparency (e.g., alcoholic beverage bottles, beverage bottles, etc.).

[0124] When the polyester-based resin includes a recycled polyester-based resin, one embodiment of the present invention can significantly reduce the amount of plastic waste generated and the amount of plastic used in production, thereby contributing to the achievement of the Sustainable Development Goals (SDGs), such as Goal 12 "Ensure sustainable consumption and production patterns."

[0125] In a polyester-based resin composition according to one embodiment of the present invention, the content of the whitening inhibitor is not particularly limited. In a polyester-based resin composition according to one embodiment of the present invention, the content of the whitening inhibitor is preferably 0.1% by weight to 10.0% by weight, based on 100% by weight of the polyester-based resin composition. The lower limit of the content is more preferably 0.2% by weight or more. The upper limit of the content may be 8.0% by weight or less, 6.0% by weight or less, or 4.0% by weight or less. When the content of the whitening inhibitor in the polyester-based resin composition is within the above range, there is an advantage in that a good balance between improvement in melt viscosity and whitening inhibition is achieved.

[0126] The polyester-based resin composition according to one embodiment of the present invention may be a masterbatch containing 10.0 to 90.0 wt % of a whitening inhibitor relative to 100 wt % of the resin composition. It can also be said that a polyester-based resin composition containing 10.0 to 90.0 wt % of a whitening inhibitor relative to 100 wt % of the polyester-based resin composition can be used as a masterbatch. When the polyester-based resin composition according to one embodiment of the present invention is used as a masterbatch, the content of the whitening inhibitor in the polyester-based resin composition is preferably 10.0 to 90.0 wt % relative to 100 wt % of the polyester-based resin composition. The lower limit of the content is more preferably 20.0 wt % or more. The upper limit of the content may be 80.0 wt % or less. When the content of the whitening inhibitor in the polyester-based resin composition is within the above range, there is an advantage in that the dispersibility of the whitening inhibitor in the polyester-based resin is improved when used as a masterbatch.

[0127] The method for producing the masterbatch is not particularly limited, and examples thereof include a melt-kneading method and a dry blending method, with the melt-kneading method being particularly preferred.

[0128] (2-2-2. Other Resins) The polyester resin composition according to one embodiment of the present invention may or may not further contain a resin other than the polyester resin. Specific examples of resins other than the polyester resin are the same as those described in the section (1-1-3. Other Resins) above, and therefore, the description therein is incorporated by reference and will not be repeated here.

[0129] The content of the resin other than the polyester resin in the polyester resin composition according to one embodiment of the present invention is not particularly limited, but may be, for example, 0 to 60 parts by weight relative to 100 parts by weight of the polyester resin. The upper limit of the content may be 50 parts by weight or less, 40 parts by weight or less, 30 parts by weight or less, 20 parts by weight or less, 10 parts by weight or less, 5 parts by weight or less, or 1 part by weight or less.

[0130] (2-2-3. Other Additives) The polyester resin composition according to one embodiment of the present invention may contain other additives. Specific examples of the other additives are the same as those described in the above section (1-1-4. Other Additives), and therefore, the description therein is incorporated by reference and will not be repeated here.

[0131] (2-2-4. Method for producing resin composition) The method for producing the polyester-based resin composition according to one embodiment of the present invention is not particularly limited, and a general method for producing a resin composition can be applied. For example, the method described in the above section (1-1-5. Method for producing resin composition) can be adopted, except that a polyester-based resin (recycled polyester-based resin and / or virgin polyester-based resin) is used instead of the recycled polyester-based resin.

[0132] (2-2-5. Physical Properties of Polyester-Based Resin Composition) The whitening inhibitor according to one embodiment of the present invention can provide a polyester-based resin composition that can provide a molded article having excellent strength and reduced whitening. Furthermore, the polyester-based resin composition according to one embodiment of the present invention (a resin composition containing the whitening inhibitor according to one embodiment of the present invention and a polyester-based resin) can provide a molded article having excellent strength and reduced whitening.

[0133] The higher the melt viscosity (IV value) of a polyester-based resin composition, the more excellent the strength of the molded article that can be provided by the resin composition. In other words, the whitening inhibitor according to one embodiment of the present invention can provide a resin composition having a higher melt viscosity (IV value) than a resin or resin composition not containing the whitening inhibitor and / or a resin composition containing a conventional viscosity modifier. The polyester-based resin composition according to one embodiment of the present invention has the advantage of having a higher melt viscosity (IV value) than a resin or resin composition not containing the whitening inhibitor according to one embodiment of the present invention and / or a resin composition containing a conventional viscosity modifier. A method for measuring the melt viscosity (IV value) of a polyester-based resin composition will be described in detail in the Examples below.

[0134] The smaller the MFR of a polyester-based resin composition, the stronger the molded article the resin composition can provide. In other words, the whitening inhibitor according to one embodiment of the present invention can provide a resin composition having a smaller MFR than a resin or resin composition not containing the whitening inhibitor and / or a resin composition containing a conventional viscosity modifier. The polyester-based resin composition according to one embodiment of the present invention has the advantage of having a smaller MFR than a resin or resin composition not containing the whitening inhibitor according to one embodiment of the present invention and / or a resin composition containing a conventional viscosity modifier. The method for measuring the MFR of a polyester-based resin composition will be described in detail in the Examples below.

[0135] [2-3. Molded article] A molded article according to one embodiment of the present invention is a molded article obtained by molding the polyester resin composition according to one embodiment of the present invention described in the above section [2-2. Polyester resin composition]. The molded article according to one embodiment of the present invention can also be said to be a molded article containing the polyester resin composition according to one embodiment of the present invention described in the above section [2-2. Polyester resin composition].

[0136] The molded article according to one embodiment of the present invention has the above-described structure, and therefore has the advantages of being excellent in strength and being less susceptible to whitening.

[0137] (2-3-1. Method for producing molded article) The method for producing a molded article according to one embodiment of the present invention, in other words, the method for molding a polyester resin composition according to one embodiment of the present invention, is not particularly limited. The method for producing a molded article may be the same as the method described in the above section [1-2. Method for producing molded article]. Therefore, the description in the above section [1-2. Method for producing molded article] is incorporated by reference, and a description thereof will be omitted here. The molded article according to one embodiment of the present invention is preferably a molded article obtained by blow molding the polyester resin composition according to one embodiment of the present invention described in the above section [2-2. Polyester resin composition].

[0138] (2-3-2. Physical Properties of Molded Articles) The degree of whitening of a molded article can be evaluated by the difference in L value (ΔL) before and after tensioning of a film (molded article) obtained by molding a resin composition into a film. Specifically, the resin composition is molded into a film, and a tensile test is performed on the resulting film (molded article). The smaller the difference in L value (ΔL) before and after tensioning, the more likely the resin composition is to provide a molded article with reduced whitening. For example, in blow molding of a resin composition or an injection-molded article, the resin composition or injection-molded article is molded while being stretched. The stretching of a film (molded article) in a tensile test can be said to simulate the stretching during blow molding of a resin composition or an injection-molded article. Therefore, the smaller the ΔL of the film (molded article), the more likely it is that whitening of a blow-molded article (e.g., a bottle-shaped molded article) obtained by blow molding will be reduced. The film (molded article) according to one embodiment of the present invention has the advantage of a smaller ΔL compared to films (molded articles) obtained from resin compositions containing conventional viscosity modifiers. In other words, the present whitening inhibitor and the present resin composition have the advantage of being able to provide a film (molded article) with a smaller ΔL compared to resin compositions containing conventional viscosity improvers.

[0139] ΔL is the same as that explained in the above section [1-3. Physical properties of molded body], so that the explanation therefor will be omitted here. The preferred numerical range for ΔL explained in the above section [1-3. Physical properties of molded body] can also be said to be the preferred numerical range for ΔL in this section (2-3-2. Physical properties of molded body).

[0140] The haze, total light transmittance (TT), and bending strength of the molded article according to one embodiment of the present invention are the same as those described in the above section [1-3. Physical properties of molded article], and therefore the description is incorporated herein by reference and will not be repeated here. The preferred numerical ranges for the haze, total light transmittance (TT), and bending strength of the molded article described in the above section [1-3. Physical properties of molded article] can also be said to be preferred numerical ranges for the haze, total light transmittance (TT), and bending strength of the molded article in this section (2-3-2. Physical properties of molded article).

[0141] (2-3-3. Shape of molded body) The shape of the molded body according to one embodiment of the present invention is not particularly limited. The shape of the molded body according to one embodiment of the present invention may be, for example, any of the shapes described in the above section [1-4. Shape of molded body]. Therefore, the description in the above section [1-4. Shape of molded body] can be used as appropriate for the shape of the molded body according to one embodiment of the present invention. The aspects described as preferred aspects in the above section [1-4. Shape of molded body] are also preferred aspects in this section (2-3-3. Shape of molded body).

[0142] 3. Method for Producing Recycled Polyester Resin Composition One embodiment of the present invention provides a method for producing a recycled polyester resin composition.

[0143] Polyester-based resins have a problem in that their melt viscosity decreases each time they are recycled, resulting in a deterioration in strength. Solid-state polymerization (hereinafter sometimes referred to as "SSP"), which is known as a technique for increasing the melt viscosity of polyester-based resins, requires long-term implementation under high temperature and reduced pressure (vacuum), and has problems such as high power consumption, environmental impact, and high production costs.

[0144] On the other hand, the addition of a conventional viscosity modifier, a known technique for increasing the melt viscosity of polyester resins, improves the melt viscosity of the resin composition to a certain extent by mixing the matrix resin (polyester resin) with the viscosity modifier, but suffers from the problem of whitening of the molded article obtained by molding the resulting resin composition. To address this problem, efforts have been made to make the refractive index of the matrix resin and the refractive index of the polymer, which is the main component of the viscosity modifier, as similar as possible. For example, when the matrix resin is a polyester resin, a technique has been developed in which a monomer mixture containing a certain amount of styrene in addition to a reactive functional group-containing monomer is used during polymerization of the polymer. The resin composition obtained in this manner has a certain degree of transparency because the refractive index of the polyester resin is similar to that of the polymer. However, even when such a resin composition is used, the problem of whitening of the molded article still exists.

[0145] An additional object of one embodiment of the present invention is to provide a novel method for producing a recycled polyester resin composition that utilizes SSP while reducing the environmental impact and production costs.

[0146] The present inventors have conducted extensive research, regardless of refractive index, to obtain molded articles with reduced whitening. As a result, the present inventors have independently and surprisingly discovered that a whitening inhibitor containing a polymer (A) according to one embodiment of the present invention obtained by polymerizing a monomer mixture (A) containing specific amounts of each of the components (a), (b), and (c), or a monomer mixture (A) containing specific amounts of each of the components (a) and (b), can provide molded articles with reduced whitening. Furthermore, when SSP was performed using pellets obtained by melt-kneading such a whitening inhibitor and a polyester resin, the inventors discovered that the time required to increase the melt viscosity to a target value could be significantly shortened.

[0147] That is, according to one embodiment of the present invention, it is possible to provide a novel method for producing a recycled polyester resin composition that utilizes SSP while reducing the environmental impact and production costs.

[0148] [3-1. Method for producing recycled polyester resin composition] A method for producing a recycled polyester resin composition according to one embodiment of the present invention includes the steps of melt-kneading a whitening inhibitor for polyester resins and a polyester resin to prepare pellets containing the whitening inhibitor for polyester resins and the polyester resin, and performing solid-state polymerization using the pellets, wherein the whitening inhibitor for polyester resins includes a polymer (A) obtained by polymerizing a monomer mixture (A) containing (a) 10 parts by weight to 60 parts by weight of an epoxy group-containing monomer, and (b) 40 parts by weight to 90 parts by weight of a non-epoxy group-containing monomer.

[0149] In this specification, the "step of melt-kneading a whitening inhibitor for polyester-based resins and a polyester-based resin to prepare pellets containing the whitening inhibitor for polyester-based resins and the polyester-based resin" may be referred to as "step I," and the "step of performing solid-state polymerization using the pellets" may be referred to as "step II." Furthermore, the "whitening inhibitor for polyester-based resins" may be simply referred to as the "whitening inhibitor," and the "pellets containing the whitening inhibitor for polyester-based resins and the polyester-based resin" may be simply referred to as the "pellets."

[0150] (3-1-1. Step I) (3-1-1-1. Whitening inhibitor) In one embodiment of the present invention, the whitening inhibitor comprises a polymer (A) obtained by polymerizing a monomer mixture (A) containing (a) 10% by weight to 60% by weight of an epoxy group-containing monomer, and (b) 40% by weight to 90% by weight of an epoxy group-free monomer.

[0151] Because the whitening inhibitor has the above-described structure, it has the advantage that, when melt-kneaded with a polyester-based resin, the melt viscosity of the polyester-based resin increases, thereby providing pellets that can provide molded articles with excellent strength and reduced whitening. Therefore, in an SSP using pellets with increased melt viscosity, the time required to increase the melt viscosity to the target value can be shortened. Furthermore, because the whitening inhibitor has the above-described structure, it can also be said that a molded article with excellent strength and reduced whitening can be provided.

[0152] In the process of preparing pellets containing a polyester resin and a whitening inhibitor (e.g., during melt-kneading of the polyester resin and the whitening inhibitor), the reactive functional group (e.g., epoxy group) in the polymer (A) contained in the whitening inhibitor can react with a terminal functional group (e.g., hydroxyl group or carboxyl group) of the polyester resin. This reaction can elongate the molecular chain of the polyester resin; this mechanism increases the melt viscosity of the pellet. Furthermore, because the melt viscosity of the pellet is increased, the time required to increase the melt viscosity to the target value during SSP using the pellet can be shortened. Furthermore, by including the aforementioned polymer (A) in the whitening inhibitor, the dispersibility of the whitening inhibitor in the pellet and in the recycled polyester resin composition after SSP can be improved. It is presumed that this suppresses whitening of the molded body. However, the present invention is not limited to these mechanisms and presumptions.

[0153] The content of component (a) (epoxy group-containing monomer (a)) in the monomer mixture (A) is not particularly limited, but is preferably 10 to 60% by weight relative to 100% by weight of the monomer mixture (A). The upper limit of the content may be 55, 50, 45, or 40% by weight, and the lower limit of the content may be 15, 20, 25, or 30% by weight. When the content of component (a) is within the above range, the effect of improving the melt viscosity of the pellets can be improved. As a result, in SSP using the pellets, the time required to increase the melt viscosity to the target value can be shortened. Furthermore, molded articles obtained using the recycled polyester resin composition obtained after SSP have the advantage of being superior in strength.

[0154] The content of component (b) (epoxy group-free monomer (b)) in the monomer mixture (A) is not particularly limited, but is preferably 40 to 90% by weight relative to 100% by weight of the monomer mixture (A). The upper limit of the content may be 85, 80, 75, or 70% by weight, and the lower limit of the content may be 45, 50, 55, or 60% by weight. When the content of component (b) is within the above range, there is an advantage that the dispersibility of the whitening inhibitor in the pellets and in the recycled polyester resin composition after SSP can be improved. As a result, there is also an advantage that whitening of the resulting molded article can be further suppressed.

[0155] Other aspects of the whitening inhibitor than those described above are the same as those described in the above section (1-1-2. Whitening inhibitor), and therefore the description therein is incorporated by reference and will not be repeated here. The aspects described as preferred aspects in the above section (1-1-2. Whitening inhibitor) are also preferred aspects in this section (3-1-1-1. Whitening inhibitor).

[0156] Furthermore, when the description in the above section (1-1-2. Whitening inhibitor) is used as an explanation for this section (3-1-1-1. Whitening inhibitor), the "recycled polyester-based resin" in the above section (1-1-2. Whitening inhibitor) may be read as "polyester-based resin" in the explanation of this section (3-1-1-1. Whitening inhibitor).

[0157] (3-1-1-2. Polyester Resin) Specific examples of polyester resins are the same as those described above in (2-2-1. Polyester Resin), and therefore, the description is incorporated herein by reference and will not be repeated here. The specific examples described as preferred examples in (2-2-1. Polyester Resin) above are also preferred examples in this (3-1-1-2. Polyester Resin) section.

[0158] Furthermore, aspects of polyester-based resins other than the specific examples of polyester-based resins may be the same as those described in the above section (1-1-1. Recycled polyester-based resins), and therefore that description is incorporated herein by reference, and further description is omitted here. In particular, of the aspects described in the above section (1-1-1. Recycled polyester-based resins), aspects other than being recycled can be regarded as aspects of polyester-based resins and can be incorporated as appropriate. The aspects described as preferred aspects in the above section (1-1-1. Recycled polyester-based resins) can also be preferred aspects in this section (3-1-1-2. Polyester-based resins).

[0159] The polyester-based resin preferably contains the following (i), (ii) and / or (iii): (i) a polyester-based resin composition and / or a molded article that has been once manufactured as a polyester-based resin composition and / or a molded article and then used and / or discarded, (ii) a discarded polyester-based resin composition and / or a discarded molded article that is discharged during the manufacturing process of the polyester-based resin composition and / or a molded article, and (iii) a polyester-based resin obtained by recycling the above (i) and (ii).

[0160] Examples of (i) include crushed materials (flakes, etc.) obtained by recovering, washing and crushing used and / or discarded polyester resin compositions and / or molded articles.

[0161] Examples of (iii) include polyester resin compositions and / or molded articles produced by recycling materials using (i) and / or (ii) as raw materials.

[0162] When the polyester-based resin contains the polyester-based resin described above, one embodiment of the present invention can significantly reduce the amount of plastic waste generated and the amount of plastic used in production, thereby contributing to the achievement of Sustainable Development Goals (SDGs) such as Goal 12, "Ensure sustainable consumption and production patterns."

[0163] On the other hand, a polyester resin that has never been commercialized may be referred to herein as a “virgin polyester resin.” In one embodiment of the present invention, the polyester resin used also includes a mixture obtained by mixing the “virgin polyester resin” with the above-mentioned (i), (ii), and / or (iii).

[0164] Conventionally, when the above (i) and (ii) are recycled, the resulting melt viscosity tends to decrease due to moisture and / or heat during the recycling process. Furthermore, the polyester resin (iii) itself may be a resin whose melt viscosity has already been reduced. Therefore, conventionally, recycled polyester resins have tended to have limited applications due to their low melt viscosity.

[0165] According to a method for producing a recycled polyester resin composition according to one embodiment of the present invention, in step I, by mixing the whitening inhibitor with the polyester resin, it is possible to prepare pellets that have an increased melt viscosity and that reduce whitening when the resulting recycled polyester resin composition is molded into a molded article. Then, by using such pellets to perform SSP in step II, it is possible to shorten the time required to increase the melt viscosity to a target value, thereby reducing the environmental impact and production costs, and producing a recycled polyester resin with a high melt viscosity.

[0166] Therefore, one embodiment of the present invention has the advantage that it can greatly expand the applications of recycled polyester resins with respect to their reuse, and in particular can greatly contribute to their expansion into applications requiring strength and high transparency (e.g., alcoholic beverage bottles, beverage bottles, etc.).

[0167] (3-1-1-3. Preparation of Pellets) In step I, the whitening inhibitor for polyester resins and the polyester resin are melt-kneaded to prepare pellets containing the whitening inhibitor for polyester resins and the polyester resin.

[0168] The content of the whitening inhibitor in the pellets obtained in step I is not particularly limited, but is preferably 0.1 wt % to 10.0 wt % relative to 100 wt % of the pellets. The lower limit of the content is more preferably 0.2 wt % or more. The upper limit of the content may be 8.0 wt % or less, 6.0 wt % or less, or 4.0 wt % or less. When the content of the whitening inhibitor in the pellets is within the above range, there is an advantage in that a good balance is achieved between improving the melt viscosity and suppressing whitening.

[0169] In preparing the pellets, a masterbatch containing preferably 10.0 wt % to 90.0 wt % of the whitening inhibitor relative to 100 wt % of the polyester-based resin composition may be used. When using such a masterbatch, the lower limit of the content of the whitening inhibitor in the masterbatch is more preferably 20.0 wt % or more relative to 100 wt % of the polyester-based resin composition. The upper limit of the content may be 80.0 wt % or less. When the content of the whitening inhibitor in the masterbatch is within the above range, there is an advantage in that the dispersibility of the whitening inhibitor in the polyester-based resin is improved.

[0170] The method for producing the masterbatch is not particularly limited, and examples thereof include a melt-kneading method and a dry blending method, with the melt-kneading method being particularly preferred.

[0171] A resin other than the polyester-based resin may be further contained in Step I. Specific examples of the resin other than the polyester-based resin are the same as those described above in the section (1-1-3. Other Resins), and therefore, the description therein is incorporated by reference and will not be described here.

[0172] The content of the resin other than the polyester resin in the pellets obtained in step I is not particularly limited, but may be, for example, 0 to 60 parts by weight relative to 100 parts by weight of the polyester resin. The upper limit of the content may be any of 50 parts by weight or less, 40 parts by weight or less, 30 parts by weight or less, 20 parts by weight or less, 10 parts by weight or less, 5 parts by weight or less, and 1 part by weight or less.

[0173] Other additives may be added in step I. Specific examples of other additives are the same as those described above in the section (1-1-4. Other additives), and therefore, the description therein is incorporated by reference and will not be described here.

[0174] In step I, the method for melt-kneading the whitening inhibitor and polyester-based resin is not particularly limited, and a general method for producing a resin composition can be applied. For example, the polyester-based resin composition can be obtained by mixing the polyester-based resin and the whitening inhibitor using a Henschel mixer or a tumbler mixer, and then melt-kneading the resulting mixture. For the melt-kneading, a kneader such as a single-screw or twin-screw extruder, a Banbury mixer, a pressure kneader, or a mixing roll can be used. Pellets can be produced by such melt-kneading.

[0175] The higher the melt viscosity (IV value) of the pellets, the shorter the time required to increase the melt viscosity of the recycled polyester resin composition to the target value in step II of SSP. Furthermore, the whitening inhibitor can provide pellets with a higher melt viscosity (IV value) than pellets containing no whitening inhibitor and / or pellets containing a conventional viscosity improver. The method for measuring the melt viscosity (IV value) of the resin composition will be described in detail in the Examples below.

[0176] Furthermore, the smaller the MFR of the pellets, the more excellent the strength of the molded article can be obtained from the recycled polyester resin composition obtained by SSP using the pellets. In other words, the whitening inhibitor can provide a recycled polyester resin composition with a smaller MFR than when the whitening inhibitor is not contained and / or when a conventional viscosity improver is contained. The method for measuring the MFR of the resin composition will be described in detail in the Examples below.

[0177] (3-1-2. Step II) Step II is a step of carrying out solid-state polymerization using the pellets prepared in Step I. The method of solid-state polymerization is not particularly limited, and a reactor and reaction conditions suitable for solid-state polymerization can be appropriately selected.

[0178] Step II may include, for example, a crystallization step in which the pellets are dried and crystallized, a temperature ramp step in which the crystallized pellets are further heated, and a polymerization step in which solid-state polymerization is carried out.

[0179] The crystallization step is a step of drying and crystallizing the pellets, for example, by heating the pellets to 120°C to 150°C under a predetermined pressure. The order of drying and crystallization is not particularly limited, and either may be performed first, or drying and crystallization may be performed simultaneously. Furthermore, even when drying and crystallization are performed simultaneously, the entire drying process and the entire crystallization process may be performed simultaneously, or either may be started and / or completed first. The time for which drying and crystallization are performed is also not particularly limited, and is, for example, 1.0 hour to 5.0 hours.

[0180] The temperature-raising step is a step of further raising the temperature of the crystallized pellets. The temperature-raising step is preferably carried out under a predetermined pressure, for example. The temperature-raising step is preferably carried out by raising the temperature of the pellets to a temperature of, for example, 150°C to 230°C. The time from the start to the end of the temperature-raising step is not particularly limited, and is, for example, 1.0 hour to 5.0 hours. In the temperature-raising step, gas can be removed.

[0181] The solid-state polymerization is preferably carried out under a predetermined pressure in an inert gas such as nitrogen gas, and is usually carried out at a temperature in the range of 200°C to 250°C, more preferably 220°C to 240°C.

[0182] Step II may further comprise a preheating step of preheating the pellets prior to the crystallization step.

[0183] In the recycled polyester resin composition obtained by the method for producing a recycled polyester resin composition according to one embodiment of the present invention, the content of the whitening inhibitor is not particularly limited, but is preferably 0.1 to 10.0% by weight based on 100% by weight of the recycled polyester resin composition. The lower limit is more preferably 0.2% by weight or more. The upper limit may be 8.0% by weight or less, 6.0% by weight or less, or 4.0% by weight or less. If the content of the whitening inhibitor in the pellets is within the above range, there is an advantage in that a good balance between improved melt viscosity and whitening inhibition is achieved.

[0184] The higher the melt viscosity (IV value) of the recycled polyester resin composition, the more excellent the strength of the molded article that can be provided by the recycled polyester resin composition.

[0185] Furthermore, the smaller the MFR of the recycled polyester resin composition, the more excellent the strength of the molded article that can be provided by the recycled polyester resin composition. The MFR of the recycled polyester resin composition is preferably 3.7 to 30.0, more preferably 5.0 to 25.0, and even more preferably 10.0 to 20.0.

[0186] [3-2. Method for producing molded article] A method for producing a molded article according to one embodiment of the present invention includes a step of molding the recycled polyester resin composition obtained by the method described in the above section [3-1. Method for producing recycled polyester resin composition].

[0187] The method for producing a molded article according to one embodiment of the present invention has the above-described configuration, and therefore has the advantage of being able to produce a molded article that is excellent in strength and has reduced whitening.

[0188] The molding method is not particularly limited, and may be the same as the manufacturing method described in the above section [1-2. Manufacturing method of molded body]. Therefore, the description in the above section [1-2. Manufacturing method of molded body] is incorporated by reference, and the description will be omitted here. In one embodiment of the present invention, the molding step is preferably a blow molding step.

[0189] The blow molding method has already been explained in the above section [1-2. Method for producing molded body], so the explanation therefor will be omitted here by referencing that explanation.

[0190] [3-3. Physical Properties of Molded Articles] The degree of whitening of a molded article obtained by a molded article production method according to one embodiment of the present invention can be evaluated by the difference in L value (ΔL) between before and after tension of a film (molded article) obtained by molding a recycled polyester resin composition into a film. Specifically, the recycled polyester resin composition is molded into a film, and a tensile test is performed on the resulting film (molded article). The smaller the difference in L value (ΔL) between before and after tension, the more likely it is that the recycled polyester resin composition will provide a molded article with reduced whitening. For example, in blow molding of a resin composition or an injection-molded article, the resin composition or the injection-molded article is molded while being stretched. The stretching of the film (molded article) in the tensile test can be said to simulate the stretching during blow molding of the resin composition or the injection-molded article. Therefore, the smaller the ΔL of the film (molded article), the more likely it is that whitening of the blow-molded article (e.g., a bottle-shaped molded article) obtained by blow molding will be reduced. The film (molded article) according to one embodiment of the present invention has the advantage of a smaller ΔL compared to films (molded articles) obtained from conventional recycled polyester resin compositions containing viscosity modifiers. In other words, the whitening inhibitor and recycled polyester resin composition have the advantage of being able to provide a film (molded article) with a smaller ΔL compared to a resin composition containing a conventional viscosity improver.

[0191] ΔL is the same as that explained in the above section [1-3. Physical properties of molded body], so that explanation is omitted here. The preferred numerical range for ΔL explained in the above section [1-3. Physical properties of molded body] can also be said to be the preferred numerical range for ΔL in this section [3-3. Physical properties of molded body].

[0192] The haze, total light transmittance (TT), and bending strength of the molded body obtained by the molded body manufacturing method according to one embodiment of the present invention are the same as those described in the above section [1-3. Physical properties of molded body], and therefore the description therein is incorporated by reference and will not be repeated here. The preferred numerical ranges for the haze, total light transmittance (TT), and bending strength of the molded body described in the above section [1-3. Physical properties of molded body] can also be said to be preferred numerical ranges for the haze, total light transmittance (TT), and bending strength of the molded body in this section [3-3. Physical properties of molded body].

[0193] The shape of the molded body according to one embodiment of the present invention is not particularly limited. The shape of the molded body according to one embodiment of the present invention may be, for example, any of the shapes described in the above section [1-4. Shape of molded body]. Therefore, the description in the above section [1-4. Shape of molded body] can be appropriately applied to the shape of the molded body according to one embodiment of the present invention. The aspects described as preferred aspects in the above section [1-4. Shape of molded body] are also preferred aspects in this section (2-3-3. Shape of molded body).

[0194] 4. Method for Producing Molded Article A method for producing a molded article according to one embodiment of the present invention comprises the steps of preparing a recycled polyester resin composition and molding the recycled polyester resin composition, wherein the step of preparing the recycled polyester resin composition comprises the steps of melt-kneading a whitening inhibitor for polyester resins and a polyester resin to prepare pellets containing the whitening inhibitor for polyester resins and the polyester resin, and performing solid-state polymerization using the pellets, wherein the whitening inhibitor for polyester resins comprises a polymer (A) obtained by polymerizing a monomer mixture (A) containing (a) 10 parts by weight to 60 parts by weight of an epoxy group-containing monomer, and (b) 40 parts by weight to 90 parts by weight of a non-epoxy group-containing monomer.

[0195] The method for producing a molded article according to one embodiment of the present invention has the above-described configuration, and therefore has the advantage of being able to provide a molded article that is excellent in strength and has reduced whitening.

[0196] (4-1. Recycled Polyester Resin Composition) The recycled polyester resin composition used in the method for producing a molded article according to one embodiment of the present invention may be a resin composition containing a recycled polyester resin, and may be, for example, the resin composition described in the above section [1-1. Resin Composition]. Furthermore, the recycled polyester resin composition used in the method for producing a molded article according to one embodiment of the present invention may be a recycled polyester resin composition obtained by the method described in the above section [3. Method for producing a recycled polyester resin composition]. Therefore, the descriptions in the above sections [1-1. Resin Composition] and [3. Method for producing a recycled polyester resin composition] can be used as appropriate for specific aspects of the recycled polyester resin composition used in the method for producing a molded article according to one embodiment of the present invention. The aspects described as preferred aspects in the above sections [1-1. Resin Composition] and [3. Method for producing a recycled polyester resin composition] may also be preferred aspects in this section (4-1. Recycled Polyester Resin Composition).

[0197] (4-2. Whitening Inhibitor) The whitening inhibitor used in the method for producing a molded body according to one embodiment of the present invention may be (i) a whitening inhibitor described in the above section (1-1-2. Whitening Inhibitor), (ii) a whitening inhibitor described in the above section (2. Whitening Inhibitor), or (iii) a whitening inhibitor described in the above section (3-1-1-1. Whitening Inhibitor). Therefore, for specific aspects of the whitening inhibitor used in the method for producing a molded body according to one embodiment of the present invention, the descriptions in the above section (1-1-2. Whitening Inhibitor), the above section (2. Whitening Inhibitor), and the above section (3-1-1-1. Whitening Inhibitor) can be used as appropriate. The descriptions in the above section (1-1-2. Whitening Inhibitor) and the above section (2. The embodiments described as preferred embodiments in the section (4-1-1-1. Whitening inhibitor) above and the section (3-1-1-1. Whitening inhibitor) above may also be preferred embodiments in this section (4-2. Whitening inhibitor).

[0198] (4-3. Step of preparing recycled polyester resin composition) A method for producing a molded article according to one embodiment of the present invention includes a step of preparing a recycled polyester resin composition. The step of preparing a recycled polyester resin composition may include, for example, the method for producing a recycled polyester resin composition according to one embodiment of the present invention described in the above section [3. Method for producing recycled polyester resin composition] as one step. Therefore, the description in the above section [3. Method for producing recycled polyester resin composition] can be used as appropriate for specific aspects of the step of preparing a recycled polyester resin composition in a method for producing a molded article according to one embodiment of the present invention. The aspects described as preferred aspects in the above section [3. Method for producing recycled polyester resin composition] may also be preferred aspects in this section (4-2. Step of preparing recycled polyester resin composition).

[0199] The process for preparing the recycled polyester-based resin composition includes a process for melt-kneading a whitening inhibitor for polyester-based resins and a polyester-based resin to prepare pellets containing the whitening inhibitor for polyester-based resins and the polyester-based resin, and a process for performing solid-state polymerization using the pellets.

[0200] The "step of melt-kneading a whitening inhibitor for polyester-based resins and a polyester-based resin to prepare pellets containing the whitening inhibitor for polyester-based resins and the polyester-based resin" may be, for example, Step I described in the above section (3-1-1. Step I). Therefore, the description in the above section (3-1-1. Step I) can be used as appropriate for specific aspects of the "step of melt-kneading a whitening inhibitor for polyester-based resins and a polyester-based resin to prepare pellets containing the whitening inhibitor for polyester-based resins and the polyester-based resin" in the method for producing a molded product according to one embodiment of the present invention. The aspects described as preferred aspects in the above section (3-1-1. Step I) may also be preferred aspects of the "step of melt-kneading a whitening inhibitor for polyester-based resins and a polyester-based resin to prepare pellets containing the whitening inhibitor for polyester-based resins and the polyester-based resin" in the method for producing a molded product according to one embodiment of the present invention.

[0201] The "step of carrying out solid-state polymerization using the pellets" may be, for example, Step II described in the above section (3-1-2. Step II). Therefore, the description in the above section (3-1-2. Step II) can be used as appropriate for specific aspects of the "step of carrying out solid-state polymerization using the pellets" in the method for producing a molded body according to one embodiment of the present invention. The aspects described as preferred aspects in the above section (3-1-2. Step II) may also be preferred aspects of the "step of carrying out solid-state polymerization using the pellets" in the method for producing a molded body according to one embodiment of the present invention.

[0202] (4-4. Step of molding recycled polyester resin composition) In the method for producing a molded article according to one embodiment of the present invention, the method for molding the recycled polyester resin composition is not particularly limited. In the method for producing a molded article according to one embodiment of the present invention, the method for molding the recycled polyester resin composition, in other words, the method for producing a molded article, can be the method described in the above [1-2. Method for producing a molded article]. Therefore, for specific aspects of the "step of molding a recycled polyester resin composition" in the method for producing a molded article according to one embodiment of the present invention, the description in the above [1-2. Method for producing a molded article] can be used as appropriate. The aspects described as preferred aspects in the above [1-2. Method for producing a molded article] can also be preferred aspects in the "step of molding a recycled polyester resin composition" in the method for producing a molded article according to one embodiment of the present invention.

[0203] [5. Uses] (i) A whitening inhibitor for polyester resin according to one embodiment of the present invention, for example, as described in the above section [2. Whitening inhibitor], (ii) a polyester resin composition according to one embodiment of the present invention, for example, as described in the above section [2. Whitening inhibitor], (iii) a recycled polyester resin composition obtained by one embodiment of the present invention, for example, obtained by the production method described in the above section [3. Production method of recycled polyester resin composition], and (iv) a recycled polyester resin composition according to one embodiment of the present invention, for example, as described in the above section [1. Molded article] and / or [2. Whitening inhibitor], and / or as described in the above section [3. The molded article according to one embodiment of the present invention, obtained by the manufacturing method described in the section "Method for manufacturing a recycled polyester resin composition," is suitable for use in the following applications, but is not particularly limited thereto: automotive applications such as cylinder head covers, engine covers, intake manifolds, radiator tanks, oil pans, accelerator pedals, canisters, fuel tubes, air brake tubes, exhaust gas tubes, hydrogen injectors, ducts, industrial fasteners, and door mirror stays; coil bobbins, connectors, gears, sockets, switches, electric blanket coated wires, optical fiber cable coating materials, and electric work tools. Examples of suitable applications include electrical and electronic applications such as tools and wire ties, mechanical applications such as hydraulic and pneumatic connectors and tubes, bearings, covers and housings, bearings, pressure-resistant hoses, and cable ties, building materials such as curtain rail parts, aluminum sash corners, door rollers, handrails, curtain rollers, and door handles, sports and leisure applications such as sports shoe soles, ski and snowboard equipment, reels, and diving snorkels, packaging materials and containers such as shrink packaging films, food packaging films, alcoholic beverage bottles, beverage bottles, and pesticide bottles, and medical applications such as toothbrushes, chair legs and armrests, and sutures. The molded product is preferably a bottle.

[0204] An embodiment of the present invention may have the following configuration.

[0205] [1] A molded article obtained by molding a resin composition containing a recycled polyester resin, wherein the haze of a solution of the molded article is 1.50% or more and the haze of the molded article is 7.5 or less. Here, the haze of the solution of the molded article is a value measured by carrying out the following steps (1) to (2) in order: (1) dissolving the resin composition in hexafluoro-2-propanol to obtain a solution having a resin composition concentration of 0.05 g / mL; (2) measuring the haze of the solution of the molded article using a haze meter whose zero point has been adjusted with the hexafluoro-2-propanol; The haze of the molded article is a value obtained by measurement using the haze meter.

[0206] [2] The molded article according to [1], wherein the resin composition has a melt flow rate (MFR) of 3.7 g / 10 min to 30.0 g / 10 min. Here, the MFR is a value determined by measurement in accordance with JIS K 7210-1 under conditions of drying at 130°C for 8 hours, a temperature of 270°C, and a load of 2.16 kg.

[0207] [3] The molded body according to [1] or [2], wherein the total light transmittance (TT) of the molded body is 80.0% or more. Here, the total light transmittance (TT) of the molded body is a value obtained by measurement using a haze meter.

[0208] [4] The molded article according to any one of [1] to [3], wherein the recycled polyester resin comprises one or more selected from the group consisting of recycled [polycarbonate / polyethylene terephthalate], recycled [polyethylene terephthalate / glycol-modified polyethylene terephthalate], and recycled [polyethylene terephthalate / copolymerized polyethylene terephthalate].

[0209] [5] The molded article according to any one of [1] to [4], wherein the molded article is in a bottle shape.

[0210] [6] The molded article according to any one of [1] to [5], wherein the resin composition further contains a whitening inhibitor for polyester-based resins, and the whitening inhibitor for polyester-based resins contains a polymer (A) obtained by polymerizing a monomer mixture (A) containing (a) 10% by weight to 60% by weight of an epoxy group-containing monomer, and (b) 40% by weight to 90% by weight of an epoxy group-free monomer.

[0211] [7] The molded article according to [6], wherein the monomer mixture (A) further contains (c) 0% by weight to 10% by weight of a vinyl monomer other than the component (a) and the component (b) that is copolymerizable with the component (a) and the component (b).

[0212] [8] The molded article according to [6] or [7], wherein the (b) epoxy group-free monomer is an epoxy group-free alkyl methacrylate.

[0213] [9] The molded article according to any one of [6] to [8], wherein the number average molecular weight of the polymer (A) is 2,000 to 6,000.

[0214]

[10] The molded article according to any one of [6] to [9], wherein the polymer (A) has an average of 2 to 8 reactive functional groups per molecule of the polymer (A).

[0215]

[11] The molded article according to any one of [6] to

[10] , wherein the whitening inhibitor for polyester-based resins does not contain the polymer (A) having a molecular weight of 1000 or less, or contains the polymer (A) having a molecular weight of 1000 or less in an amount of 4.00% by weight or less relative to 100% by weight of the whitening inhibitor for polyester-based resins.

[0216]

[12] The molded article according to any one of [6] to

[11] , wherein the whitening inhibitor for polyester resins further contains a polymer (B), and the composite made of the polymer (A) and the polymer (B) has a core-shell structure in which the polymer (A) forms a core and the polymer (B) forms a shell, and the ratio of the weight of the polymer (A) to the weight of the polymer (B) in the composite (weight of the polymer (A) / weight of the polymer (B)) is 20 / 80 to 80 / 20.

[0217]

[13] The molded article according to

[12] , wherein in the composite, the number average molecular weight of the polymer (A) is 2,000 to 5,000, and the number average molecular weight of the polymer (B) is 3,000 to 6,000.

[0218]

[14] The molded article according to any one of [6] to

[13] , wherein the polymer (A) is a polymer obtained by emulsion polymerization.

[0219]

[15] A whitening inhibitor for polyester resins, comprising a polymer (A) obtained by polymerizing a monomer mixture (A) comprising: (a) 10% by weight to 60% by weight of an epoxy group-containing monomer; and (b) 40% by weight to 90% by weight of an epoxy group-free monomer.

[0220]

[16] A method for producing a molded product, comprising: a step of preparing a recycled polyester resin composition; and a step of molding the recycled polyester resin composition, wherein the step of preparing the recycled polyester resin composition comprises a step of melt-kneading a whitening inhibitor for polyester resins and a polyester resin to prepare pellets containing the whitening inhibitor for polyester resins and the polyester resin, and a step of performing solid-state polymerization using the pellets, wherein the whitening inhibitor for polyester resins comprises a polymer (A) obtained by polymerizing a monomer mixture (A) containing: (a) 10 parts by weight to 60 parts by weight of an epoxy group-containing monomer, and (b) 40 parts by weight to 90 parts by weight of an epoxy group-free monomer.

[0221]

[17] The method for producing a molded article according to

[16] , wherein the recycled polyester resin composition has an MFR of 3.7 to 30.0.

[0222] An embodiment of the present invention may have the following configuration.

[0223] [A1] A whitening inhibitor for polyester resins, comprising a polymer (A) obtained by polymerizing a monomer mixture (A) containing (a) 10% by weight to 60% by weight of an epoxy group-containing monomer and (b) 40% by weight to 90% by weight of an epoxy group-free monomer.

[0224] [A2] The whitening inhibitor for polyester-based resins according to [A1], wherein the monomer mixture (A) further contains (c) 0 to 10% by weight of a vinyl monomer other than (a) and (b) that is copolymerizable with (a) and (b).

[0225] [A3] The whitening inhibitor for polyester resins according to [A1] or [A2], wherein the (b) epoxy group-free monomer is an epoxy group-free alkyl methacrylate.

[0226] [A4] The whitening inhibitor for polyester resins according to any one of [A1] to [A3], wherein the number average molecular weight of the polymer (A) is 2,000 to 6,000.

[0227] [A5] The whitening inhibitor for polyester-based resins according to any one of [A1] to [A4], wherein the polymer (A) has an average of 2 to 8 reactive functional groups per molecule of the polymer (A).

[0228] [A6] The whitening inhibitor for polyester-based resins according to any one of [A1] to [A5], wherein the whitening inhibitor for polyester-based resins does not contain the polymer (A) having a number average molecular weight of 1000 or less, or contains the polymer (A) having a number average molecular weight of 1000 or less in an amount of 4.00% by weight or less, based on 100% by weight of the whitening inhibitor for polyester-based resins.

[0229] [A7] The whitening inhibitor for polyester-based resins according to any one of [A1] to [A6], further comprising a polymer (B), a composite comprising the polymer (A) and the polymer (B) has a core-shell structure in which the polymer (A) forms a core and the polymer (B) forms a shell, and the ratio of the weight of the polymer (A) to the weight of the polymer (B) in the composite (weight of the polymer (A) / weight of the polymer (B)) is 20 / 80 to 80 / 20.

[0230] [A8] The whitening inhibitor for polyester-based resins according to [A7], wherein in the composite, the number average molecular weight of the polymer (A) is 2,000 to 5,000, and the number average molecular weight of the polymer (B) is 3,000 to 6,000.

[0231] [A9] A polyester-based resin composition comprising the whitening inhibitor for polyester-based resins according to any one of [A1] to [A8] and a polyester-based resin.

[0232] [A10] The polyester-based resin composition according to [A9], wherein the polyester-based resin composition contains 0.1 wt % to 10.0 wt % of the whitening inhibitor for polyester-based resins, based on 100 wt % of the polyester-based resin composition.

[0233] [A11] The polyester-based resin composition according to [A9], wherein the polyester-based resin composition contains 10.0 wt % to 90.0 wt % of the whitening inhibitor for polyester-based resins relative to 100 wt % of the polyester-based resin composition, and is a masterbatch.

[0234] [A12] The polyester resin composition according to any one of [A9] to [A11], which contains a recycled polyester resin.

[0235] [A13] The polyester-based resin composition according to any one of [A9] to [A12], wherein the polyester-based resin comprises one or more selected from the group consisting of polycarbonate / polyethylene terephthalate, polyethylene terephthalate / glycol-modified polyethylene terephthalate, and polyethylene terephthalate / copolymerized polyethylene terephthalate.

[0236] [A14] A molded article obtained by molding the polyester resin composition according to any one of [A9] to [A13].

[0237] [A15] A molded article obtained by blow molding the polyester resin composition according to any one of [A9] to [A13].

[0238] An embodiment of the present invention may have the following configuration.

[0239] [B1] A method for producing a recycled polyester-based resin composition, comprising: a step of melt-kneading a whitening inhibitor for polyester-based resins and a polyester-based resin to prepare pellets containing the whitening inhibitor for polyester-based resins and the polyester-based resin; and a step of performing solid-state polymerization using the pellets, wherein the whitening inhibitor for polyester-based resins comprises a polymer (A) obtained by polymerizing a monomer mixture (A) containing: (a) 10 parts by weight to 60 parts by weight of an epoxy group-containing monomer, and (b) 40 parts by weight to 90 parts by weight of an epoxy group-free monomer.

[0240] [B2] The method for producing a recycled polyester resin composition according to [B1], wherein the monomer mixture (A) further contains (c) 0 to 10% by weight of a vinyl monomer other than (a) and (b) that is copolymerizable with (a) and (b).

[0241] [B3] The production method according to [B1] or [B2], wherein the (b) epoxy group-free monomer is an epoxy group-free alkyl methacrylate.

[0242] [B4] The production method according to any one of [B1] to [B3], wherein the number average molecular weight of the polymer (A) is 2,000 to 6,000.

[0243] [B5] The method according to any one of [B1] to [B4], wherein the polymer (A) has an average of 2 to 15 reactive functional groups per molecule of the polymer (A).

[0244] [B6] The method according to any one of [B1] to [B5], wherein the whitening inhibitor for polyester-based resins does not contain the polymer (A) having a number average molecular weight of 1,000 or less, or contains the polymer (A) having a number average molecular weight of 1,000 or less in an amount of 4.00% by weight or less relative to 100% by weight of the whitening inhibitor for polyester-based resins.

[0245] [B7] The method for producing a polyester resin according to any one of [B1] to [B6], wherein the whitening inhibitor for polyester resin further contains a polymer (B), and the composite comprising the polymer (A) and the polymer (B) has a core-shell structure in which the polymer (A) forms a core and the polymer (B) forms a shell, and the ratio of the weight of the polymer (A) to the weight of the polymer (B) in the composite (weight of the polymer (A) / weight of the polymer (B)) is 20 / 80 to 80 / 20.

[0246] [B8] The method according to [B7], wherein in the composite, the number average molecular weight of the polymer (A) is 2,000 to 5,000, and the number average molecular weight of the polymer (B) is 3,000 to 6,000.

[0247] [B9] The manufacturing method according to any one of [B1] to [B8], wherein the whitening inhibitor for polyester resins is contained in an amount of 0.1 to 10.0% by weight based on 100% by weight of the recycled polyester resin composition.

[0248] [B10] The method according to any one of [B1] to [B9], wherein the recycled polyester resin composition has an MFR of 3.7 to 30.0.

[0249] [B11] The manufacturing method according to any one of [B1] to [B10], wherein the polyester-based resin comprises at least one selected from the group consisting of polycarbonate / polyethylene terephthalate, polyethylene terephthalate / glycol-modified polyethylene terephthalate, and polyethylene terephthalate / copolymerized polyethylene terephthalate.

[0250] [B12] A method for producing a molded article, comprising a step of molding the recycled polyester resin composition obtained by the production method according to any one of [B1] to [B11].

[0251] [B13] The manufacturing method according to [B12], wherein the molding step is a blow molding step.

[0252] An embodiment of the present invention may have the following configuration.

[0253] [C1] A molded body obtained by molding a resin composition containing a recycled polyester resin, wherein the haze of a solution of the molded body is 1.50% or more, and the haze of the molded body is 7.5 or less. Here, the haze of the solution of the molded body is a value measured by carrying out the following steps (1) to (2) in order: (1) dissolving the resin composition in hexafluoro-2-propanol to obtain a solution having a resin composition concentration of 0.05 g / mL; (2) measuring the haze of the solution of the molded body using a haze meter whose zero point has been adjusted with the hexafluoro-2-propanol; The haze of the molded body is a value obtained by measurement using the haze meter.

[0254] [C2] The molded article according to [C1], wherein the resin composition has a melt flow rate (MFR) of 3.7 g / 10 min to 30.0 g / 10 min. Here, the MFR is a value determined by measurement in accordance with JIS K 7210-1 under conditions of drying at 130°C for 8 hours, a temperature of 270°C, and a load of 2.16 kg.

[0255] [C3] The molded body according to [C1] or [C2], wherein the total light transmittance (TT) of the molded body is 80% or more. Here, the total light transmittance (TT) of the molded body is a value obtained by measurement using a haze meter.

[0256] [C4] The molded article according to any one of [C1] to [C3], wherein the recycled polyester resin comprises one or more selected from the group consisting of recycled [polycarbonate / polyethylene terephthalate], recycled [polyethylene terephthalate / glycol-modified polyethylene terephthalate], and recycled [polyethylene terephthalate / copolymerized polyethylene terephthalate].

[0257] [C5] The molded article according to any one of [C1] to [C4], wherein the molded article is in the shape of a bottle.

[0258] The present invention will be described in more detail with reference to the following examples and comparative examples. However, the present invention is not limited to these examples, and examples obtained by appropriately combining the technical means disclosed in each example are also included in the scope of the present invention.

[0259] [Measurement and Evaluation Methods] 1. Particle diameter of polymer or composite The particle diameter of the polymer or composite was measured using a Microtrac UPA (manufactured by Nikkiso Co., Ltd.) and obtained by calculating the volume average particle diameter.

[0260] 2. Polymerization Conversion Rate The polymerization conversion rate was defined as the ratio (%) of the actual solid content to the solid content at the ideal conversion rate.

[0261] 3. Number Average Molecular Weight The number average molecular weights of polymer (A) and polymer (B) were calculated by GPC measurement. The GPC device used was a device manufactured by Tosoh Corporation. The analysis conditions were as follows: Column 1 (low molecular weight column) 1st column: TSKgel SuperH5000 2nd column: TSKgel SuperH4000 3rd column: TSKgel SuperH3000 4th column: TSKgel SuperH2000 Column 2 (high molecular weight column) 1st column: TSKgel SuperHZM-H 2nd column: TSKgel SuperHZM-H Injection method: Syringe metering Loop volume: 100 μL Pre-suction volume: 150 μL Air volume: 3.5 μL Automatic wash volume: 1.0 mL Syringe speed Sampling speed: 10 μL / s Washing speed: 100 μL / s Metering speed: 5 μL / s Sample flow rate: 0.350 mL / min Reference flow rate ratio: 1x Flow rate increase / decrease control: Disabled Flow rate increase rate: 0.35 mL / min Flow rate decrease rate: 0.35 mL / min Pressure limits Column 1 Upper sample pressure limit: 12.0 MPa Lower sample pressure limit: 0.2 MPa Upper reference pressure limit: 25.0 MPa Lower reference pressure limit: 0.2 MPa Column 2 Upper sample pressure limit: 25.0 MPa Lower sample pressure limit: 0.2 MPa Upper reference pressure limit: 12.0 MPa Lower reference pressure limit: 0.2 MPa Flow rate Column 1 Sample flow rate: 0.600 mL / min Reference flow rate ratio: 1 / 2 Column 2 Sample flow rate: 0.350 mL / min Reference flow rate ratio: 1x Flow rate increase / decrease control: Disabled Flow rate increase / decrease rate: 0.35 mL / min / min Flow rate decrease rate: 0.35 mL / min / min Pressure limits Column 1 Upper sample pressure limit: 12.0 MPa Lower sample pressure limit: 0.2 MPa Upper limit of reference pressure: 25.0 MPa Lower limit of reference pressure: 0.2 MPa Peak detection conditions RI Detection sensitivity (front side): 3.000 mV / min Detection sensitivity (rear side): 3.000 mV / min Base judgment value: 1.000 mV / min Exclusion area: 10.000 mVs Exclusion height: 0.000 mVHalf-width exclusion: 0.000 s UV / EXT detection sensitivity (front): 3.000 mV / min Detection sensitivity (rear): 3.000 mV / min Base judgment value: 1.000 mV / min Exclusion area: 10.000 mVs Exclusion height: 0.000 mV Half-width exclusion: 0.000 s Polystyrene was used as the reference substance. That is, using polystyrene with a known number average molecular weight, GPC was performed under the above-mentioned conditions to obtain a calibration curve. Thereafter, GPC was performed under the above-mentioned conditions for the samples (polymer (A) and polymer (B)), and the number average molecular weight of each sample was calculated from the calibration curve.

[0262] 4. Melt Viscosity (IV Value) of Resin Composition (Recycled Polyester Resin Composition or Polyester Resin Composition) The IV value of the resin composition was measured in accordance with JIS K 7367-5.

[0263] 5. Melt flow rate (MFR) of polyester resin, pellets, and resin composition (recycled polyester resin composition or polyester resin composition) The melt flow rate (MFR) of the polyester resin, pellets, and resin composition was measured in accordance with JIS K 7210-1 under the conditions of drying at 130°C for 8 hours, a temperature of 270°C, and a load of 2.16 kg.

[0264] 6. ΔL of Film (Molded Article) The ΔL of the resin compositions of each Example, Comparative Example, and Reference Example was measured by the following method: (1) Pellets of the resin composition were heated to 270°C using an extruder equipped with a T-die (LABO PLASTOMILL, manufactured by Toyo Seiki Seisaku-sho, Ltd.) to mold a film having a thickness of 200 μm; (2) The obtained film was punched into a dumbbell-shaped No. 2 shape according to JIS K 6251 to obtain a dumbbell; (3) The L value of the obtained dumbbell was measured using a colorimetric color difference meter (Color Meter ZE6000, manufactured by Nippon Denshoku Industries Co., Ltd.), and the obtained value was defined as the L value before tension; (4) The dumbbell was punched into a No. 2 shape according to JIS K 6251 to obtain a dumbbell; In accordance with 7113, the film was stretched to 8.5 times its original size at 95°C and 1000 mm / min using a tensile tester (Shimadzu, AG-2000E); (5) The L value of the stretched dumbbell was measured using the colorimeter, and the obtained value was used as the L value after stretching; (6) The L value before stretching was subtracted from the L value after stretching, and the obtained difference was used as the ΔL of the film (molded product).

[0265] 7. Haze of Solution Obtained by Dissolving Molded Body (1) The molded body was dissolved in hexafluoro-2-propanol (HFIP) to obtain a solution having a solid concentration of 0.05 g / mL; (2) The haze and total light transmittance of the obtained solution of the molded body were measured using a haze meter (Nippon Denshoku Industries Co., Ltd., Haze Meter NDH4000) zero-adjusted with HFIP.

[0266] 8. L Value of Molded Article The L value of the molded article was measured using a color difference meter (Color Meter ZE6000, manufactured by Nippon Denshoku Industries Co., Ltd.).

[0267] 9. Haze of Molded Article The haze of the molded article was measured using a haze meter (NDH4000, manufactured by Nippon Denshoku Industries Co., Ltd.).

[0268] 10. Total Light Transmittance (TT) of Molded Article The total light transmittance (TT) of a molded article was measured using a haze meter (NDH4000, manufactured by Nippon Denshoku Industries Co., Ltd.).

[0269] 11. Bending Strength Using a molded body as a sample, measurement was carried out using a compression tester (MCT-1150, manufactured by AND Co., Ltd.) at a descending speed of 50 mm / min.

[0270] 12. Wall Thickness of Bottle (Molded Product) The wall thickness of the bottle (molded product) at various distances vertically upward from the bottom of the bottle (molded product) was measured using a magnetic thickness meter (MAGNA MIKE, manufactured by OLYMPUS).

[0271] 13. Powder productivity 2.5 g of powder was spread on a SUS plate to the same thickness within an area of ​​2 cm x 5 cm. Next, another SUS plate of the same type was placed on top of the SUS plate to sandwich the powder. A 5 kg weight was then placed on top and the plate was heated in an oven at 70°C for 2 hours. After natural cooling, the SUS plate was turned vertically and the weight percentage of the powder remaining attached to the SUS plate was measured. The evaluation criteria are as follows, with a higher number indicating better powder productivity: 2 (good): less than 20% by weight; 1 (pass): 20% to 50% by weight; 0 (poor): more than 50% by weight.

[0272] [Whitening inhibitor] (Example A1) (Production of polymer (A)) 180 parts by weight of purified water, 1.5 parts by weight of sodium formaldehyde sulfoxylate, 0.0075 parts by weight of EDTA, 0.3 parts by weight of ferrous sulfate heptahydrate, and 0.1 parts by weight of sodium polyoxyethylene lauryl ether phosphate were added to a reactor. While stirring the mixture in the reactor, the temperature inside the reactor was increased to 75°C, and nitrogen was bubbled through the mixture for 30 minutes.

[0273] Thereafter, a monomer mixture (A) consisting of 35 parts by weight of methyl methacrylate (MMA) as component (b), 15 parts by weight of glycidyl methacrylate (GMA) as component (a), and 2 parts by weight of n-octyl mercaptan as a chain transfer agent was added to the reactor over 150 minutes. Furthermore, during the addition of the monomer mixture (A) (150 minutes), 0.1 parts by weight of t-butyl hydroperoxide as a polymerization initiator was added to the reactor over 150 minutes. Furthermore, 80 minutes after the addition of the monomer mixture (A), 0.2 parts by weight of polyoxyethylene lauryl ether sodium phosphate as an anionic surfactant was added all at once to the reactor. The mixture was then allowed to react until the polymerization conversion rate reached 90%, and then allowed to react for an additional 30 minutes after the polymerization conversion rate reached 90%. Through these operations, polymer (A) was obtained.

[0274] (Production of Polymer (B) (Production of Composite Having Core-Shell Structure)) Next, a monomer mixture (B) consisting of 35 parts by weight of MMA, 15 parts by weight of GMA, and 1.5 parts by weight of n-octyl mercaptan was added to the reactor containing the polymer (A). During the addition of the monomer mixture (B), 0.1 parts by weight of t-butyl hydroperoxide, a polymerization initiator, was added to the reactor. Furthermore, during the addition of the monomer mixture (B), 0.2 parts by weight of polyoxyethylene lauryl ether sodium phosphate, an anionic surfactant, was added to the reactor as needed. Thereafter, the reaction was continued until the polymerization conversion rate reached 98%, and from the point at which the polymerization conversion rate reached 98%, the reaction was continued for an additional 30 minutes. Through this operation, polymer (B) was obtained.

[0275] Finally, a latex containing a composite of polymer (A) and polymer (B) having a particle size of 1100 angstroms was obtained, and the final polymerization conversion was 98%.

[0276] In the composite obtained by the above-described production method, the polymer (A) can be considered to form the core portion, and the polymer (B) can be considered to form the shell portion, i.e., the composite can be considered to have a core-shell structure.

[0277] The obtained latex contained two types of number average molecular weights (Mn), and the number average molecular weight of polymer (A) (core component) was 3,000, and the number average molecular weight of polymer (B) (shell component) was 4,000. The average number of epoxy groups in polymer (A) (core component) was 5, and the average number of epoxy groups in polymer (B) (shell component) was 6, resulting in an average number of epoxy groups per polymer molecule of 5.5.

[0278] To recover the composite particles as a powder from the latex, the obtained latex was quickly added to a 5% aqueous calcium chloride solution while stirring. The temperature of the mixture was maintained at 70°C using steam. The temperature of the mixture was then raised to 85°C to dehydrate the aggregates of composite particles. The obtained aggregates were dried to obtain a composite powder. The powder was then sieved through an 18-mesh screen, and the powder that passed through the 18-mesh screen was obtained as a whitening inhibitor.

[0279] (Example A2) A polymer (A) was produced in the same manner as in Example A1, except that the monomer mixture (A) in Example A1 was changed to a monomer mixture (A) consisting of 35 parts by weight of MMA, 15 parts by weight of GMA, and 1.5 parts by weight of n-octyl mercaptan. In Example A2, no polymer (B) was produced. In Example A2, a latex containing polymer (A) was finally obtained. Then, in the same manner as in Example A1, particles of polymer (A) were recovered as powder from the latex, and the obtained powder was used as a whitening inhibitor.

[0280] (Example A3) Polymer (A) was produced by the same method as in Example A1. In Example A3, polymer (B) was not produced. In Example A3, a latex containing polymer (A) was finally obtained. Then, by the same method as in Example A1, particles of polymer (A) were recovered as powder from the latex, and the obtained powder was used as a whitening inhibitor.

[0281] (Example A4) Polymer (A) was produced in the same manner as in Example A1, except that the monomer mixture (A) in Example A1 was changed to a monomer mixture (A) consisting of 42.5 parts by weight of MMA, 7.5 parts by weight of GMA, and 2 parts by weight of n-octyl mercaptan. In Example A4, polymer (B) was not produced. In Example A4, a latex containing polymer (A) was finally obtained. Then, particles of polymer (A) were recovered as powder from the latex in the same manner as in Example A1, and the obtained powder was used as a whitening inhibitor.

[0282] Comparative Example A1: A latex containing a composite was obtained by the same procedure as in Example A1, except that (i) in the monomer mixture (A), 35 parts by weight of MMA was changed to 70 parts by weight of styrene (St), and 2 parts by weight of n-octyl mercaptan was changed to 1 part by weight, and (ii) in the monomer mixture (B), 40 parts by weight of MMA was changed to 20 parts by weight of St, 10 parts by weight of GMA was changed to 1 part by weight, and the amount of n-octyl mercaptan was changed to 0 parts by weight (i.e., not used). The composite in the obtained latex had a number average molecular weight of 9,900 for polymer (A) and 120,000 for polymer (B), an average number of epoxy groups per polymer (A) molecule was 9, and an average number of epoxy groups per polymer (B) molecule was unknown. Thereafter, a powder of the complex was obtained from the latex in the same manner as in Example A1, and used as a whitening inhibitor.

[0283] For the whitening inhibitors of Examples A1 to A4 and Comparative Example A1, the parts by weight of each of the polymers (A) and (B), the number average molecular weight, the number of reactive functional groups per molecule, and the amount (% by weight) of component (a) relative to 100% by weight of the polymer or composite are shown in Table 1. Powder productivity was also evaluated. The results are shown in Table 1.

[0284] [Resin composition] (Raw materials) Polyester resin: virgin polyester resin (MA-8334P, manufactured by Unitika Ltd.) After being subjected to a thermal history in the following manner, the virgin polyester resin was used to produce a resin composition: the virgin polyester resin alone was melt-kneaded at 270°C using a twin-screw extruder (manufactured by Leistritz, 35 mm, L / D=17), and the melt-kneaded product extruded from a die was cut.

[0285] Whitening inhibitor: The whitening inhibitors of Examples A1 to A4 and Comparative Example A1 were melt-kneaded at 270°C using a twin-screw extruder (LABO PLASTOMILL, Brabender, 19 mm, L / D = 20, manufactured by Toyo Seiki Seisaku-sho, Ltd.), and the molten mixture extruded from a die was cut. Pellets of the whitening inhibitor were obtained by this operation. The obtained pellets of the whitening inhibitor were used in the production of a resin composition.

[0286] (Examples A5 to A8, Comparative Example A2, and Reference Example A) For each Example A, Comparative Example A, and Reference Example A, the polyester resin and whitening inhibitor listed in Table 2 were fed to a twin-screw extruder (manufactured by Leistritz, 35 mm, L / D = 17) in the amounts listed in Table 2. The mixture was melt-kneaded at 270°C in the extruder, and the molten mixture extruded from the die was cut. Pellets of the resin composition were obtained by this operation.

[0287] The melt viscosity (IV value) and MFR of the pellets of the resin compositions obtained in each Example A, Comparative Example A, and Reference Example A, or the pellets of Reference Example A, were measured by the methods described above. The ΔL of the films (molded articles) of the resin compositions obtained in each Example A, Comparative Example A, and Reference Example A was also measured by the methods described above. The results are shown in Table 2. The amount (wt %) of component (a) when the entire resin composition is taken as 100 wt % is shown in the section "Component (a) (wt %)."

[0288] [Molded body] (Raw materials) Polyester resin: recycled polyester resin (rPET FG Resins).

[0289] Whitening inhibitor: The whitening inhibitors of Example A1 and Comparative Example A1 were melt-kneaded at 270°C using a twin-screw extruder (LABO PLASTOMILL, Brabender, 19 mm, L / D = 20, manufactured by Toyo Seiki Seisaku-sho, Ltd.), and the melt-kneaded product extruded from a die was cut. By this operation, pellets of the whitening inhibitor were obtained. The obtained pellets of the whitening inhibitor were used to produce a molded product.

[0290] (Examples A9, A10, Comparative Example A3, and Reference Example A2) (Production of Resin Composition) For each of Examples A, Comparative Example A, and Reference Example A, the polyester resin and whitening inhibitor listed in Table 3 were fed to a twin-screw extruder (manufactured by Leistritz, 35 mm, L / D = 17) in the amounts listed in Table 3. The mixture was melt-kneaded at 270°C in the extruder, and the molten mixture extruded from the die was cut. Pellets of the resin composition were obtained by this operation.

[0291] Reference Example A3 The resin composition of Reference Example A3 was obtained by charging recycled polyester resin pellets into a batch-type SSP reactor and carrying out solid-state polymerization at 230°C.

[0292] The melt viscosity (IV value) and MFR of the pellets of the resin compositions obtained in each Example A, Comparative Example A, and Reference Example A2, as well as the pellets of Reference Example A3, were measured and evaluated by the methods described above. Furthermore, the ΔL of the films (molded articles) of the resin compositions obtained in each Example A, Comparative Example A, and Reference Example A was measured by the methods described above. The results are shown in Table 3.

[0293] (Production of Bottle (Molded Article)) The pellets of the resin compositions obtained in each Example A, Comparative Example A, and Reference Example A were injection molded at a molding temperature of 280°C using an injection molding machine (Nissei Plastic Industrial Co., Ltd., FNX-140, screw Φ45) to obtain a preform molded article. The obtained preform molded article was blow molded at a surface temperature of about 100°C using a blow molding machine (Frontier Co., Ltd., FXT-1R) to obtain a bottle-shaped molded article with a volume of 500 ml.

[0294] The bottle (molded article) obtained in each Example A, Comparative Example A, and Reference Example A was measured for its L value, haze, total light transmittance (TT), wall thickness (distance from the bottom), and buckling strength using the methods described above. The results are shown in Table 4. Furthermore, for the bottle (molded article) obtained in each Example A and Comparative Example A, the L value of Reference Example A2, which did not contain a whitening inhibitor, was subtracted from the L value of each Example A and Comparative Example A, and the resulting difference (value) was designated as ΔL for each Example A and Comparative Example A, and is shown in Table 4. Furthermore, the haze of the solution was measured for each bottle (molded article) obtained in each Example A and Reference Example A3.

[0295] [Recycled Polyester Resin Composition] (Raw Materials) Polyester resin: Recycled PET bottle flakes, which are crushed recycled PET bottles, were used.

[0296] Whitening inhibitor: The whitening inhibitors of Example A1 and Comparative Example A1 were melt-kneaded at 270°C using a twin-screw extruder (LABO PLASTOMILL, Brabender, 19 mm, L / D = 20, manufactured by Toyo Seiki Seisaku-sho, Ltd.), and the melt-kneaded product extruded from a die was cut. By this operation, pellets of the whitening inhibitor were obtained. The obtained pellets of the whitening inhibitor were used in the following Example B and Comparative Example B.

[0297] (Examples B1 to B4 and Comparative Examples B1 to B4) For each Example B and each Comparative Example B, the polyester resin (recycled PET bottle flakes) and the whitening inhibitor shown in Table 5 were fed to a twin-screw extruder (manufactured by Leistritz, 35 mm, L / D = 17) in the amounts shown in Table 5. The mixture was melt-kneaded at 270°C in the extruder, and the melt-kneaded product extruded from a die was cut. Pellets of the resin composition were obtained by this operation.

[0298] The pellets thus obtained were subjected to SSP until the melt viscosity (IV value) reached 0.84, thereby producing a recycled polyester resin composition.

[0299] Specifically, the pellets were placed in a rotary reactor and stirred while being heated to allow the reaction to proceed. Heating was carried out in the following order from (i) to (vii) at the temperatures and for the times shown in Table 6, through steps (i) to (vii). After the reaction, the pellets were removed as they were.

[0300] The melt viscosity (IV value), MFR, and ΔL were measured by the above-mentioned methods for the recycled PET bottle flakes, pellets containing the whitening inhibitor for polyester resins and the polyester resin, and the recycled polyester resin composition after the SSP process used in each Example B and Comparative Example B. These measurement results and the SSP polymerization time until the IV value reached 0.84 in the SSP are shown in Table 5.

[0301] As shown in Table 5, when the whitening inhibitor obtained in Comparative Example A1 was used instead of the whitening inhibitor obtained in Example A1, it was necessary to add about 1 wt % of the whitening inhibitor to increase the IV value of the pellets above the IV value of the recycled PET bottle flakes. Furthermore, the ΔL of the recycled polyester resin compositions of Examples B1 to B3 obtained using the whitening inhibitor obtained in Example A1 was significantly smaller than the ΔL of the recycled polyester resin compositions of Comparative Examples B2 to B4 obtained using the whitening inhibitor obtained in Comparative Example A1 instead of the whitening inhibitor obtained in Example A1.

[0302] (Production of Bottle (Molded Article)) The recycled polyester resin composition obtained in Example B1 was injection molded at a molding temperature of 280°C using an injection molding machine (manufactured by Nissei Plastic Industrial Co., Ltd., FNX-140, screw Φ45) to obtain a preform molded article. The obtained preform molded article was blow molded at a surface temperature of about 100°C using a blow molding machine (manufactured by Frontier Co., Ltd., FXT-1R) to obtain a 500 ml bottle (molded article).

[0303] Furthermore, a bottle (molded article) was obtained by the method described above using a recycled polyester resin composition obtained by the same method as in Example B, but using the whitening inhibitor obtained in Comparative Example A1 instead of the whitening inhibitor obtained in Example A1. The bottle (molded article) obtained from the recycled polyester resin composition obtained in Example B1 had a smaller degree of whitening than the bottle (molded article) obtained from the recycled polyester resin composition obtained by the same method as in Example B, but using the whitening inhibitor obtained in Comparative Example A1 instead of the whitening inhibitor obtained in Example A1.

[0304] According to one embodiment of the present invention, a molded article containing a recycled polyester resin can be provided, which has excellent strength and reduced whitening. Also, according to one embodiment of the present invention, a whitening inhibitor for polyester resin can be provided, which can provide a polyester resin composition that can provide a molded article having excellent strength and reduced whitening. Therefore, one embodiment of the present invention is suitable for use in automotive applications such as cylinder head covers, engine covers, intake manifolds, radiator tanks, oil pans, accelerator pedals, canisters, fuel tubes, air brake tubes, exhaust gas tubes, hydrogen injectors, ducts, industrial fasteners, and door mirror stays; electrical and electronic applications such as coil bobbins, connectors, gears, sockets, switches, electric blanket coated wires, optical fiber cable coatings, power tools, and wire ties; mechanical applications such as hydraulic and pneumatic connectors and tubes, bearings, covers and housings, bearings, pressure-resistant hoses, and cable ties; building materials such as curtain rail parts, aluminum sash corners, door rollers, handrails, curtain rollers, and door handles; sports and leisure applications such as sports shoe soles, ski and snowboard equipment, reels, and diving snorkels; packaging materials and containers such as shrink packaging films, food packaging films, alcoholic beverage bottles, beverage bottles, and pesticide bottles; toothbrushes, chair legs and armrests; and medical applications such as sutures.

Claims

1. A molded body obtained by molding a resin composition containing a recycled polyester resin, wherein the haze of a solution of the molded body is 1.50% or more, and the haze of the molded body is 7.5 or less. Here, the haze of the solution of the molded body is a value measured by carrying out the following (1) to (2) in order; (1) dissolving the resin composition in hexafluoro-2-propanol to obtain a solution having a concentration of the resin composition of 0.05 g / mL; (2) using a haze meter that has been zero-adjusted with the hexafluoro-2-propanol, the haze of the solution of the obtained molded body is measured; The haze of the molded body is a value obtained by measurement using the haze meter.

2. The molded article according to claim 1, wherein the melt flow rate (MFR) of the resin composition is 3.7 g / 10 min to 30.0 g / 10 min., wherein the MFR is a value determined by measurement in accordance with JIS K 7210-1 under conditions of drying at 130°C for 8 hr, temperature at 270°C, and load of 2.16 kg.

3. The molded body according to claim 1, wherein the molded body has a total light transmittance (TT) of 80.0% or more. Here, the total light transmittance (TT) of the molded body is a value obtained by measurement using a haze meter.

4. The molded body described in claim 1, wherein the recycled polyester-based resin comprises one or more selected from the group consisting of recycled [polycarbonate / polyethylene terephthalate], recycled [polyethylene terephthalate / glycol-modified polyethylene terephthalate], and recycled [polyethylene terephthalate / copolymerized polyethylene terephthalate].

5. The molded article according to any one of claims 1 to 4, wherein the molded article is in the shape of a bottle.

6. The molded article according to claim 1, wherein the resin composition further comprises a whitening inhibitor for polyester-based resins, the whitening inhibitor for polyester-based resins comprising a polymer (A) obtained by polymerizing a monomer mixture (A) comprising (a) 10% by weight to 60% by weight of an epoxy group-containing monomer, and (b) 40% by weight to 90% by weight of a non-epoxy group-containing monomer.

7. The molded article according to claim 6, wherein said monomer mixture (A) further contains (c) 0 to 10% by weight of a vinyl monomer other than said component (a) and said component (b) which is copolymerizable with said component (a) and said component (b).

8. The molded article according to claim 6 or 7, wherein the epoxy group-free monomer (b) is an epoxy group-free alkyl methacrylate.

9. The molded article according to claim 6 or 7, wherein the number average molecular weight of the polymer (A) is 2,000 to 6,000.

10. The molded article according to claim 6 or 7, wherein the polymer (A) has an average of 2 to 8 reactive functional groups per molecule of the polymer (A).

11. The molded body described in claim 6 or 7, wherein the whitening inhibitor for polyester-based resins does not contain the polymer (A) having a molecular weight of 1,000 or less, or contains 4.00 weight% or less of the polymer (A) having a molecular weight of 1,000 or less, based on 100 weight% of the whitening inhibitor for polyester-based resins.

12. The molded body according to claim 6 or 7, wherein the whitening inhibitor for polyester resin further contains a polymer (B), a composite consisting of the polymer (A) and the polymer (B) has a core-shell structure in which the polymer (A) forms a core and the polymer (B) forms a shell, and a ratio of the weight of the polymer (A) to the weight of the polymer (B) in the composite (weight of the polymer (A) / weight of the polymer (B)) is 20 / 80 to 80 / 20.

13. The molded article according to claim 12, wherein in the composite, the number average molecular weight of the polymer (A) is 2,000 to 5,000, and the number average molecular weight of the polymer (B) is 3,000 to 6,000.

14. A whitening inhibitor for polyester resins, comprising a polymer (A) obtained by polymerizing a monomer mixture (A) containing: (a) 10% by weight to 60% by weight of an epoxy group-containing monomer; and (b) 40% by weight to 90% by weight of an epoxy group-free monomer.

15. A method for producing a molded product, comprising: preparing a recycled polyester resin composition; and molding the recycled polyester resin composition, wherein the process for preparing the recycled polyester resin composition comprises: melt-kneading a whitening inhibitor for polyester resin and a polyester resin to prepare pellets containing the whitening inhibitor for polyester resin and the polyester resin; and performing solid-state polymerization using the pellets, wherein the whitening inhibitor for polyester resin comprises a polymer (A) obtained by polymerizing a monomer mixture (A) containing: (a) 10 parts by weight to 60 parts by weight of an epoxy group-containing monomer, and (b) 40 parts by weight to 90 parts by weight of a non-epoxy group-containing monomer.

16. The method for producing a molded article according to claim 15, wherein the recycled polyester resin composition has an MFR of 3.7 to 30.0.

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