Liquid coloring composition, and polyester resin composition and method for manufacturing polyester resin molding

Abstract

To provide a liquid coloring composition that is excellent in dispersibility and storage stability of a coloring material which does not inhibit polymerization reaction when a polyester resin is produced, enables uniform bluing without color unevenness, and causes no color migration of the coloring material, and a liquid coloring composition which enables manufacture of a polyester resin molding.MEANS: A liquid coloring composition which is added when a polyester resin is polymerized contains a diol component (A), a surface active agent (B), and a dye (C), wherein the dye (C) has solubility to 100 mL of ethylene glycol at 25°C of 0.5 g or less.SELECTED DRAWING: None

Description

[Technical field]

[0001] An embodiment of the present invention relates to a liquid coloring composition used when obtaining a polyester resin by polymerization, and a method for producing a polyester resin composition and a polyester resin molded article. [Background technology]

[0002] Plastic molded products are easy to process and are therefore used in a wide range of fields, including electrical and electronic equipment parts, automobile parts, medical parts, food containers, etc. In particular, molded products using polyester resins (polyester resin molded products) have excellent chemical and physical properties and are therefore used in a wide range of applications, including food containers such as PET bottles, sanitary containers, polyester fibers, films and sheets, etc. In addition, efforts are being made to reuse polyester resins in order to reduce costs and the burden on the environment.

[0003] In addition, depending on the raw materials and polymerization conditions used in polymerization, the polyester resin may have a yellowish hue, and the polyester resin molded product using this may have an undesirable appearance depending on the application. Specifically, because the titanium catalyst has a fast reaction rate, the polyester resin obtained using the titanium catalyst has a yellowish hue compared to the polyester resin obtained using the conventional antimony catalyst.

[0004] Furthermore, for the purpose of imparting gas barrier properties to food packaging containers and beverage bottles made of polyester resin, for example, polyamide-MXD6 resin is sometimes used in combination. However, it is difficult to separate the polyamide-MXD6 resin from the polyester resin during chemical recycling of the polyester resin, and if this resin is mixed in during polymerization, the resulting polyester resin will have a yellowish appearance, which is a problem.

[0005] As a method for solving such a problem, Patent Document 1 discloses a technique for adding a phosphoric acid compound or a phosphorous acid compound during polymerization in order to prevent coloration. Patent Document 2 discloses a technique for obtaining a polyester with low yellowness by a polyester manufacturing method. Furthermore, for the purpose of improving color tone, a technique is described in which cobalt compounds such as cobalt acetate, cobalt nitrate, cobalt chloride, cobalt acetylacetonate, cobalt naphthenate, and hydrates thereof, as well as other inorganic and organic pigments, dyes, fluorescent whitening agents, etc. are used, and the method of adding these is described as a technique of adding them as a powder or dissolved in one of the polyester monomers during the polycondensation reaction, or as a powder or master batch after the polycondensation reaction is completed. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2006-335974 A [Patent Document 2] JP 2005-314515 A Summary of the Invention [Problem to be solved by the invention]

[0007] However, in these conventional methods, it is difficult to uniformly disperse the coloring material to be used as the bluing agent, which is in a powder or granular form, in the polyester resin composition, and the obtained molded product has problems in that the color adjustment is insufficient and color unevenness occurs. Furthermore, if a coloring material is simply dispersed in the raw material of polyester resin, the coloring material will not be uniformly dispersed due to poor compatibility, and the molded product obtained using the coloring material will have uneven coloring. Furthermore, when the masterbatch is added after the polycondensation reaction is completed, not only is it cost-increasing because separate measuring equipment and mixing equipment are required, but it also results in resin that has been degraded by the heat during the production of the masterbatch being contained in the molded product, resulting in deterioration of the mechanical properties.

[0008] Therefore, an object of the present invention is to provide a liquid coloring composition that is excellent in dispersibility of coloring materials and storage stability, does not inhibit the polymerization reaction when producing a polyester resin, can uniformly bluing without color unevenness, and can produce a polyester resin composition and a polyester resin molded article that are free of color migration of coloring materials. Another object of the present invention is to provide a method for producing the polyester resin composition and the polyester resin molded article. [Means for solving the problem]

[0009] The present inventors have conducted extensive research to solve the above problems and have completed the present invention. That is, the present invention includes the following embodiments, but the embodiments of the present invention are not limited to the following. One embodiment of the present invention is a liquid coloring composition used in obtaining a polyester resin by polymerization, The composition includes a diol component (A), a surfactant (B), and a dye (C), The dye (C) relates to a liquid coloring composition having a solubility of 0.5 g or less in 100 mL of ethylene glycol at 25°C. Another embodiment of the present invention includes a step of producing a polyester resin by polymerizing a dicarboxylic acid component (X) containing at least terephthalic acid and a diol component (Y) containing at least ethylene glycol in the presence of a polymerization catalyst (Z) and a liquid coloring composition, The liquid coloring composition comprises a diol component (A), a surfactant (B), and a dye (C), The present invention relates to a method for producing a polyester resin composition, wherein the dye (C) has a solubility of 0.5 g or less in 100 mL of ethylene glycol at 25°C. Another embodiment of the present invention is a process for producing a polyester resin composition by polymerizing a dicarboxylic acid component (X) containing at least terephthalic acid and a diol component (Y) containing at least ethylene glycol in the presence of a polymerization catalyst (Z) and a liquid coloring composition; and a step of molding the obtained polyester resin composition. The liquid coloring composition comprises a diol component (A), a surfactant (B), and a dye (C), The dye (C) has a solubility of 0.5 g or less in 100 mL of ethylene glycol at 25° C., and the method for producing a polyester resin molded product relates to this method. Effect of the Invention

[0010] According to an embodiment of the present invention, there can be provided a liquid coloring composition that has excellent dispersibility and storage stability of coloring materials, and that, when added during a polymerization reaction to obtain a polyester resin, does not inhibit the polymerization reaction of the polyester resin raw material, uniformly bluing without color unevenness, and is capable of producing a polyester resin composition and a polyester resin molded product that are free of color migration of the coloring material. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] The present invention will be described in detail below. Needless to say, other embodiments are also included in the scope of the present invention as long as they are consistent with the gist of the present invention. In addition, in this specification, a numerical range specified using "~" includes the numerical values ​​before and after "~" as the range of the lower and upper limits. In this specification, the "dicarboxylic acid component (X) containing at least terephthalic acid," the "diol component (Y) containing at least ethylene glycol," the "polyester resin composition," and the "polyester resin molded body" may be referred to as the "dicarboxylic acid component (X)," the "diol component (Y)," the "resin composition," and the "resin molded body," respectively. Here, "liquid" refers to being in a liquid state at 25°C. The term "main component" refers to the component that is present in the largest amount among the components. Unless otherwise noted, the various components appearing in this specification may be used independently as a single type or as a combination of two or more types.

[0012] <<Liquid Coloring Composition>> According to an embodiment of the present invention, the liquid coloring composition is a liquid coloring composition used when synthesizing a polyester resin, and includes a diol component (A), a surfactant (B), and a dye (C), and the dye (C) has a solubility of 0.5 g or less in 100 mL of ethylene glycol at 25° C. For example, the liquid coloring composition can be added to a polyester resin raw material when synthesizing a polyester resin. By using a liquid coloring composition containing a dye (C) as a coloring material and further containing a diol component (A) and a surfactant (B), it is possible to obtain a polyester resin composition which is excellent in dispersibility of the coloring material and storage stability, does not inhibit the polymerization reaction when obtaining a polyester resin by a polymerization process, can be blued without color unevenness, and is free from dye color migration.

[0013] <Diol component (A)> The diol component (A) acts as a dispersion medium for the dye (C). Diol is also called glycol and functions as one of the main raw materials that make up polyester resin. That is, when the dicarboxylic acid component (X) and the diol component (Y) are polymerized to produce a polyester resin, the diol component (A) in the liquid colored composition reacts with the dicarboxylic acid component (X) to form a polyester resin. By using the diol component (A), a liquid coloring composition is obtained that does not inhibit the polymerization reaction even when added during synthesis of a polyester resin raw material and can uniformly bluing the polyester resin.

[0014] The diol component (A) is not limited as long as it can be used as a raw material for polyester resins. Specific examples of the diol component (A) include aliphatic glycols such as ethylene glycol, diethylene glycol, triethylene glycol, 1,3-propylene glycol, 1,4-butylene glycol, and 1,4-cyclohexanedimethanol. Among these, from the viewpoint of suppressing color unevenness of the polyester resin, ethylene glycol, 1,3-propylene glycol, 1,4-butylene glycol, and 1,4-cyclohexanedimethanol are preferred, and from the viewpoint of dispersibility of the liquid colored composition, ethylene glycol is more preferred. Ethylene glycol, also known as 1,2-ethanediol, is a glycol and is one of the main raw materials for polyethylene terephthalate.

[0015] The diol component (A) preferably contains at least ethylene glycol, and more preferably contains ethylene glycol as a main component. The main component means that ethylene glycol is the component with the highest content among the components constituting the diol component (A).

[0016] From the viewpoint of uniformity of the mixed liquid during polyester resin polymerization, the melting point of the diol component (A) is preferably −30° C. to 50° C. This is preferable because uniform bluing can be achieved without color unevenness. The melting point of the diol component (A) can be measured using a differential scanning calorimeter.

[0017] The amount of the diol component (A) in the liquid coloring composition is preferably 30 to 90 mass %, more preferably 35 to 70 mass %, and even more preferably 40 to 50 mass %, based on the total mass of the liquid coloring composition, from the viewpoint of preventing precipitation of the dye.

[0018] The molecular weight of the diol component (A) in the liquid colored composition may be, for example, 1,000 or less, 500 or less, or 400 or less, and from the viewpoint of the physical properties of the resulting polyester resin, is preferably 300 or less, and more preferably 200 or less.

[0019] <Surfactant (B)> The surfactant (B) acts as a dispersant to disperse the dye (C) in the diol component (A). The surfactant has hydrophilic and lipophilic groups in its molecule, and reduces the interfacial tension by strong adsorption to the interface of immiscible substances and molecular orientation.

[0020] Surfactants are classified into those that dissociate into ions when dissolved in an aqueous solution and those that do not. Surfactants that dissociate are further divided into anionic surfactants and cationic surfactants according to the ionic nature of the surface-active moiety. There are also surfactants in which the surface-active moiety becomes an anion when the hydrogen ion concentration (pH) of the solution is high, and becomes a cation when the pH is low. These are called amphoteric surfactants. Surfactants that do not dissociate when dissolved in an aqueous solution are called nonionic surfactants.

[0021] The surfactant (B) is preferably a nonionic surfactant or an amphoteric surfactant, more preferably a nonionic surfactant. By using these surfactants, the dispersibility and storage stability of the dye (C) in the liquid coloring composition are superior, the polymerization of the polyester resin is not inhibited, and a liquid coloring composition capable of bluing without color unevenness can be obtained. Among the specific examples described below, the surfactant (B) is preferably at least one selected from the group consisting of poly(12-hydroxystearic acid)-polyethyleneimine copolymer, polyoxyethylene alkyl ether, polyoxyalkylene derivative, sorbitan fatty acid ester, alkyl betaine, and alkylamine oxide.

[0022] The amount of the surfactant (B) in the liquid coloring composition is preferably 0.1 to 50 parts by mass, more preferably 1 to 20 parts by mass, and even more preferably 2 to 10 parts by mass, per 100 parts by mass of the diol component (A), from the viewpoints of dispersibility of the dye (C) and not inhibiting the polymerization reaction of the polyester resin raw material.

[0023] [Nonionic surfactants] Examples of nonionic surfactants include polyoxyethylene alkyl ethers, polyoxyalkylene derivatives, sorbitan fatty acid esters, poly(12-hydroxystearic acid)-polyethyleneimine copolymers, polyoxyethylene sorbitan fatty acid esters, polyoxyethylene sorbitol fatty acid esters, glycerin fatty acid esters, polyoxyethylene fatty acid esters, polyoxyethylene hardened castor oil, polyoxyethylene alkylamines, and alkyl alkanolamides, and are not particularly limited. However, poly(12-hydroxystearic acid)-polyethyleneimine copolymers, polyoxyethylene alkyl ethers, polyoxyalkylene derivatives, and sorbitan fatty acid esters are preferred, and polyoxyalkylene derivatives are more preferred. By being as described above, the dispersibility and storage stability of the dye (C) in the liquid coloring composition is excellent, and the polymerization reaction of the polyester resin raw material is not inhibited, so it is preferred.

[0024] The HLB value of the nonionic surfactant (B) is preferably 15 or less, and more preferably 1 to 15, from the viewpoint of dispersibility of the dye (C).

[0025] The HLB (Hydrophile-Lipophile Balance) value is one of the parameters that indicate the hydrophilicity or hydrophobicity of a material, and the smaller the value, the higher the hydrophobicity, and the larger the value, the higher the hydrophilicity. There are various known methods for calculating the HLB value from a chemical structure, and various known methods for measuring it. In the embodiment of the present invention, the HLB value is calculated using the Griffin method. The Griffin method is a method for calculating the HLB value using the molecular structure and molecular weight of the target material, using the following formula. Formula: HLB value = 20 x (sum of molecular weights of hydrophilic parts) ÷ (molecular weight of material)

[0026] Specific examples of polyoxyethylene alkyl ethers include, but are not limited to, polyoxyethylene lauryl ether, polyoxyethylene cetyl ether, polyoxyethylene oleyl ether, polyoxyethylene myristyl ether, and polyoxyethylene octyldodecyl ether. Specific examples of polyoxyethylene alkyl ethers include Emulgen 109P (manufactured by Kao Corporation, liquid at 25° C., HLB value 13.6) and Emulgen 102KG (manufactured by Kao Corporation, liquid at 25° C., HLB value 6.3).

[0027] The polyoxyalkylene derivative may be, for example, an ether having a polyoxyalkylene structure (excluding compounds corresponding to polyoxyethylene alkyl ethers). Specific examples of the polyoxyalkylene derivative include, but are not limited to, polyoxyethylene alkylene alkyl ether, polyoxyethylene distyrenated phenyl ether, polyoxyethylene tribenzyl phenyl ether, polyoxyethylene polyoxypropylene glycol, polyoxyethylene glyceryl ether, and polyoxyethylene diglyceryl ether.

[0028] Specific examples of polyoxyalkylene derivatives include EMULGEN LS-114 (manufactured by Kao Corporation, liquid at 25° C., HLB value 14), EMULGEN B-66 (manufactured by Kao Corporation, liquid at 25° C., HLB value 13.2), ADEKA PLURONIC L-61 (manufactured by ADEKA Corporation, liquid at 25° C., HLB value 3), ADEKA PLURONIC L-43 (manufactured by ADEKA Corporation, liquid at 25° C., HLB value 12, ADEKA PLURONIC L-35 (manufactured by ADEKA Corporation, liquid at 25° C., HLB value 18.5), and the like.

[0029] Specific examples of sorbitan fatty acid esters include, but are not limited to, sorbitan monolaurate, sorbitan monopalmitate, sorbitan monostearate, sorbitan distearate, sorbitan tristearate, sorbitan monooleate, sorbitan trioleate, polyoxyethylene sorbitan monolaurate, polyoxyethylene monooleate, and polyoxyethylene monostearate. Specific examples of sorbitan fatty acid esters include Rheodol SP-O30-V (manufactured by Kao Corporation, liquid at 25°C, HLB value 1.8), Rheodol SP-L10 (manufactured by Kao Corporation, liquid at 25°C, HLB value 8.6), and Emazol L-120V (manufactured by Kao Corporation, liquid at 25°C, HLB value 16.7).

[0030] [Amphoteric surfactants] Examples of amphoteric surfactants include, but are not limited to, alkyl betaines and alkyl amine oxides.

[0031] Specific examples of alkyl betaines include, but are not limited to, lauryl betaine, stearyl betaine, and 2-alkyl-N-carboxymethyl-N-hydroxyethyl imidazolinium betaine. Specific examples of alkylbetaines include Anhithol 20BS (manufactured by Kao Corporation, liquid at 25° C.), Anhithol 20Y-B (manufactured by Kao Corporation, liquid at 25° C.), and the like.

[0032] A specific example of the alkylamine oxide is, but is not limited to, lauryl dimethylamine oxide. A specific example of the alkylamine oxide is Amphitol 20N (Kao Corporation, liquid at 25° C.).

[0033] The surfactant (B) is preferably a liquid at 25° C. because it has excellent compatibility with the diol component (A) and excellent dispersibility of the dye (C).

[0034] <Dye (C)> The dye (C) is a dye having a solubility of 0.5 g or less in 100 mL of ethylene glycol at 25° C. In an embodiment of the present invention, the dye (C) is used for bluing during the polymerization reaction of a polyester resin. For example, a dye that can lower b* expressed in the CIE1976 L*a*b* color system in a polyester resin composition obtained using the dye (C) than in a polyester resin composition obtained without using the dye (C) can be selected and used as the dye (C). Since the dye (C) has a solubility of 0.5 g or less in the ethylene glycol contained in the diol component (Y), the dye (C) does not inhibit the polymerization reaction of the polyester resin raw material containing the dicarboxylic acid component (X) and the diol component (Y), and the polyester resin is uniformly blued without color unevenness, and a polyester resin composition without color migration of the coloring material can be obtained.

[0035] From the viewpoint of suppressing color migration from the hydrophobic polyester resin composition, it is preferable that the dye (C) has low solubility in ethylene glycol, which is a hydrophilic component, and is therefore preferably hydrophobic, and has a solubility in ethylene glycol of 0.5 g or less, preferably 0.48 g or less, and more preferably 0.45 g or less. By using such a dye (C), it is possible to obtain a liquid coloring composition having superior dispersibility and storage stability, and a molded product with less color unevenness, as compared with inorganic and organic pigments. In addition, the dye (C) is more safe than cobalt blue, and more dispersible and more stable in the liquid coloring composition than inorganic pigments such as ultramarine or organic pigments such as phthalocyanine blue. Dyes and pigments can be identified, for example, according to the classification in the Color Index Generic Name (CI Name).

[0036] In addition, compared to using a dye having a solubility of more than 0.5 g in 100 mL of ethylene glycol at 25°C as a colorant and dissolving it in ethylene glycol to form a liquid colored composition, bleeding at temperatures during the polymerization reaction of the polyester resin raw material and during molding is suppressed, and color migration does not occur.

[0037] The bluing refers to a change in the hue of the obtained polyester resin composition or polyester resin molded product when viewed with the naked eye to a bluish hue. For example, it can be expressed as the b* value represented by the CIE1976L*a*b* color system being lower in the polyester resin composition obtained by adding dye (C) than in the polyester resin composition obtained without adding dye (C).

[0038] The solubility of a dye in 100 mL of ethylene glycol at 25°C is the upper limit of the amount of dye that can be dissolved in 100 mL of ethylene glycol at 25°C. It is the upper limit of the mass of the dye when no solids or crystals are observed when the dye is added to 100 mL of ethylene glycol at 25°C, stirred for 1 minute, and filtered through a cotton cloth with a mesh size of 5 μm.

[0039] The blending amount of the dye (C) in the liquid coloring composition is preferably 1 to 150 parts by mass, more preferably 2 to 130 parts by mass, and even more preferably 5 to 120 parts by mass, per 100 parts by mass of the diol component (A) from the viewpoint of dispersibility of the dye (C). Furthermore, from the viewpoint of storage stability of the dye (C), the blending amount of the dye (C) is preferably 5 to 100 parts by mass, and even more preferably 5 to 60 parts by mass, per 100 parts by mass of the diol component (A). By using such a liquid coloring composition, the composition can more effectively function as a bluing agent-containing composition, as a concentrated dye composition added during polymerization of a polyester resin.

[0040] The dye (C) is not particularly limited as long as it has a solubility of 0.5 g or less in 100 mL of ethylene glycol at 25° C., and can be selected according to the color tone of the polyester resin. Examples of the dye (C) include anthraquinone dyes, perinone dyes, azo dyes, thiazole dyes, oxazine dyes, phthalocyanine dyes, xanthene dyes, phthalocyanine dyes, quinoline dyes, azine dyes, indigoid dyes, xanthene dyes, azine dyes, acridine dyes, methine dyes, thiazole dyes, thiazine dyes, rhodamine dyes, and triarylmethane dyes. Among these, anthraquinone dyes or perinone dyes are preferred because they have a high bluing effect and excellent dispersibility in the liquid coloring composition.

[0041] Specific examples of anthraquinone or perinone dyes include Solvent Red 52, 117, 135, 169, 176, Disperse Red 5, Solvent Orange 63, 67, 68, 72, 78, Solvent Yellow 98, 103, 105, 113, 116, Disperse Yellow 54, 64, 160, Solvent Green 3, 20, 26, Solvent Blue 35, 36, 45, 59, 63, 78, 83, 94, 97, 104, 122, 132, and Solvent Violet 13, 31, 33, 36. Among these, from the viewpoint of the bluing effect, Solvent Red 52, 117, 135, 169, 176, Solvent Green 3, 20, 26, Solvent Blue 35, 36, 45, 59, 63, 78, 83, 94, 97, 104, 122, 132, and Solvent Violet 13, 31, 33, and 36 are preferred, and Solvent Red 135, Solvent Blue 35, 36, 45, 59, 63, 78, 83, 94, 97, 104, 122, 132, and Solvent Violet 13, 31, 33, and 36 are more preferred.

[0042] <Other additives> According to an embodiment of the present invention, the liquid coloring composition may contain any other polymer, antistatic agent, defoaming agent, dyeability improver, matting agent, fluorescent brightener, stabilizer, antioxidant, viscosity adjuster, and other additives. As the antioxidant, an aromatic amine-based or phenol-based antioxidant can be used, and as the stabilizer, a phosphorus-based, sulfur-based, or amine-based stabilizer such as phosphoric acid or a phosphoric acid ester-based stabilizer can be used.

[0043] In addition, it is preferable that the liquid coloring composition does not contain any organic solvent other than the diol component (A). This is a concept excluding the state where it is intentionally added, and indicates that it is substantially free of the organic solvent, and the other organic solvent may be 1 mass % or less, 0.5 mass % or less, or 0.1 mass % or less, based on the total mass of the liquid coloring composition, or may be 0 mass %.

[0044] The total amount of any components other than the diol component (A), the surfactant (B) and the dye (C) may be 10% by mass or less, 5% by mass or less, or 1% by mass or less, or may be 0% by mass, based on the total mass of the liquid coloring composition.

[0045] <Method for producing liquid colored composition> The method for producing the liquid colored composition in the embodiment of the present invention is not particularly limited, and for example, the liquid colored composition can be obtained by adding the diol component (A), the surfactant (B), the dye (C), and other additives as necessary, mixing them with a Henschel mixer, a tumbler, a disperser, or the like, and dispersing them with a Silverson mixer (manufactured by Silverson Corporation) or the like. As the dispersing device, any device such as a kneader, a roll mill, a ball mill, or a sand mill can be used in addition to the above. It is preferable to use a bead mill, a Silverson mixer, or a roll mill because of their excellent dispersibility. The liquid coloring composition is a dye dispersion in which the dye (C) is dispersed, and can be used as a bluing agent-containing composition.

[0046] <Polyester resin composition> The polyester resin composition is obtained by using a liquid coloring composition when producing a polyester resin by polymerizing a polyester resin raw material. By using the liquid coloring composition according to the embodiment of the present invention, it is possible to obtain a polyester resin composition that does not inhibit the polymerization reaction of a polyester resin raw material containing a dicarboxylic acid component (X) and a diol component (Y), uniformly bluing the polyester resin without color unevenness, and does not cause color migration of the coloring material. At this time, the diol component (A) in the liquid colored composition also undergoes a polymerization reaction as a diol component with the dicarboxylic acid component (X) to form a polyester resin, and therefore also functions as a polyester resin raw material. Therefore, the diol component (A) is preferably ethylene glycol, which is a component contained in the diol component (Y). The liquid coloring composition can be used by adding it to a reaction vessel for polymerization. The step of adding the liquid coloring composition may be performed before the start of polymerization or during the polymerization reaction.

[0047] That is, the polyester resin composition contains a polyester resin obtained by a polymerization reaction of a dicarboxylic acid component (X), a diol component (A), and a diol component (Y) in the presence of a polymerization catalyst (Z), a surfactant (B), and a dye (C).

[0048] <Dicarboxylic acid component (X)> The dicarboxylic acid component (X) is a dicarboxylic acid component containing at least terephthalic acid, and is a raw material for polyester resin. The dicarboxylic acid component (X) may contain terephthalic acid, for example, terephthalic acid, dimethyl terephthalate, diethyl terephthalate, dibutyl terephthalate, etc. As the dicarboxylic acid component (X), terephthalic acid is preferably the main component. The term "main component" means that the component having the highest content among the components constituting the dicarboxylic acid component (X) is terephthalic acid.

[0049] As the dicarboxylic acid component (X), a component obtained by synthesis from raw materials may be used, or a component obtained by depolymerizing a polyester resin by recycling or the like may be used. In an embodiment of the present invention, the liquid coloring composition is highly effective in bluing polyester resins evenly, so that even when a dicarboxylic acid component obtained by depolymerizing recycled polyester resins is used, a resin molded product with good color tone can be obtained.

[0050] <Diol component (Y)> The diol component (Y) is a diol component containing at least ethylene glycol, and is a raw material for a polyester resin. The diol component (Y) may contain ethylene glycol and a diol component other than ethylene glycol described in the diol component (A), such as diethylene glycol, triethylene glycol, or polyethylene glycol. The diol component (Y) is preferably composed mainly of ethylene glycol. However, the diol component (Y) does not include the diol component (A) contained in the liquid coloring composition. That is, in the production of the polyester resin, a liquid coloring composition containing the diol component (A) and a diol component (Y) are used separately from the liquid coloring composition, and the raw material of the polyester resin includes the diol component (A) and the diol component (Y) separately from the diol component (A). The diol component (Y) may contain the same diol as the diol contained in the diol component (A), may contain a diol different from the diol contained in the diol component (A), and may further contain both the same diol and a different diol. The term "main component" means that, among the components constituting the diol component (Y), ethylene glycol is the component having the highest content.

[0051] The diol component (Y) may be a component obtained by synthesis from raw materials, or a component obtained by depolymerizing a polyester resin through recycling. In an embodiment of the present invention, the liquid coloring composition is highly effective in bluing polyester resins evenly, so that even when a component obtained by depolymerizing a polyester resin through recycling or the like is used, a resin molded product having a good color tone can be obtained.

[0052] <Polymerization catalyst (Z)> The polymerization catalyst (Z) is a catalyst that promotes the polymerization reaction of the polyester resin raw material. There are no particular limitations on the polymerization of the polyester resin, and for example, polymerization catalysts that can be used include titanium-based catalysts such as titanium tetraalkoxide, tetrabutoxytitanium, and titanium oxide; tin-based catalysts such as dibutyltin oxide, tin acetate, zinc acetate, and tin disulfide; antimony-based catalysts such as antimony trioxide; germanium dioxide; and magnesium acetate.

[0053] According to an embodiment of the present invention, the liquid coloring composition has a high effect of uniformly bluing the polyester resin without color unevenness during the polymerization reaction of the polyester resin raw material, so that even when a titanium catalyst having a fast reaction rate is used, it is possible to obtain a resin molded product with a good color tone. In an embodiment of the present invention, for example, the polymerization catalyst (Z) is a titanium-based catalyst.

[0054] From the viewpoint of the physical properties of the resulting polyester resin, the blending amount of the polymerization catalyst (Z) is preferably 0.5% by mass or less, more preferably 0.2% by mass or less, based on 100% by mass of the total of the dicarboxylic acid component (X) and the diol component (Y). The blending amount of the polymerization catalyst (Z) is preferably 0.001% by mass or more, more preferably 0.05% by mass or more, based on 100% by mass of the total of the dicarboxylic acid component (X) and the diol component (Y).

[0055] <Other ingredients> In the embodiment of the present invention, the polyester resin composition may contain components other than those described above, so long as they do not inhibit the polymerization reaction of the polyester resin raw material and the bluing of the polyester resin. Other components may include any polymer, antistatic agent, antifoaming agent, dyeability improver, matte agent, fluorescent brightener, stabilizer, antioxidant, and other additives. As the antioxidant, an aromatic amine-based or phenol-based antioxidant can be used, and as the stabilizer, a phosphorus-based, sulfur-based, or amine-based stabilizer such as phosphoric acid or a phosphoric acid ester-based stabilizer can be used.

[0056] <Method of producing polyester resin composition> In an embodiment of the present invention, the polyester resin composition can be produced using a dicarboxylic acid component (X), a diol component (Y), a polymerization catalyst (Z), and a liquid coloring composition according to an embodiment of the present invention. The method for producing a polyester resin composition includes, for example, a step of producing a polyester resin composition by polymerizing a dicarboxylic acid component (X) containing at least terephthalic acid and a diol component (Y) containing at least ethylene glycol in the presence of a polymerization catalyst (Z) and a liquid coloring composition. This step may include adding the dicarboxylic acid component (X), the diol component (Y), the polymerization catalyst (Z), and the liquid coloring composition to a reaction vessel, respectively. The order in which the dicarboxylic acid component (X), the diol component (Y), the polymerization catalyst (Z), and the liquid coloring composition are added is not particularly limited. Two or more of these may be added at the same time. In this step, the diol component (A) also polymerizes with the dicarboxylic acid component (X). The liquid coloring composition may be added before the start of polymerization or during the polymerization reaction. Any optional components may be further used in the polymerization reaction.

[0057] The polymerization method for obtaining the polyester resin is not particularly limited, but for example, a method of producing a polyester resin by polycondensation reaction of the product obtained by esterification reaction or transesterification reaction of the dicarboxylic acid component (X) and the diol component (Y) is added to a reaction vessel, and then the liquid coloring composition according to the embodiment of the present invention is added, and then a polymerization catalyst (Z) is added, and the product obtained by esterification reaction or transesterification reaction of the dicarboxylic acid component (X) and the diol component (Y) is added. In this specification, these reactions may be referred to as polymerization reaction.

[0058] The polymerization reaction ratio of the polyester resin raw materials is preferably such that the molar ratio of dicarboxylic acid component (X):diol component (Y) is in the range of 1:1.03 to 1:2.5, more preferably 1:1.05 to 1:1.2. By being in the above range, a polyester resin molded product having excellent mechanical properties can be obtained.

[0059] In an embodiment of the present invention, at least one of the dicarboxylic acid component (X) containing at least terephthalic acid and the diol component (Y) containing at least ethylene glycol may be a component obtained by depolymerizing a polyester resin.

[0060] The blending amount of the liquid coloring composition is preferably 0.0001 to 1 mass%, more preferably 0.00015 to 0.5 mass%, and even more preferably 0.0002 to 0.5 mass%, relative to 100 mass% in total of the dicarboxylic acid component (X) and the diol component (Y), from the viewpoint of the physical properties and color uniformity of the resulting polyester.

[0061] From the viewpoint of the physical properties and color uniformity of the obtained polyester resin, the ratio of the diol component (Y) used in the polymerization reaction to the diol component (A) contained in the liquid coloring composition used in the polymerization reaction is preferably 0.0001 to 2 mass% of the diol component (A) relative to 100 mass% of the diol component (Y), more preferably 0.0002 to 1.5 mass%, and even more preferably 0.0005 to 1 mass%.

[0062] From the viewpoint of dispersibility of the dye (C) and physical properties of the resulting polyester resin, the ratio of the diol component (Y) used in the polymerization reaction to the surfactant (B) contained in the liquid coloring composition used in the polymerization reaction is preferably 0.000001 to 0.8 mass %, more preferably 0.000005 to 0.5 mass %, and even more preferably 0.00001 to 0.3 mass %, relative to 100 mass % of the diol component (Y).

[0063] From the viewpoint of bluing effect, the content of the dye (C) is preferably more than 0 ppm and not more than 10 ppm, more preferably not more than 5 ppm, and further preferably not more than 3 ppm, based on 100 mass % of the polyester resin composition.

[0064] The polymerization reaction temperature is not particularly limited, but is preferably in the range of 180°C to 280°C. When the polymerization reaction temperature is 180°C or higher, the productivity tends to be good, and when it is 280°C or lower, the decomposition of the resin and the by-production of volatile matter that causes odor tend to be suppressed. The lower limit of the polymerization reaction temperature is more preferably 200°C, and particularly preferably 220°C. The upper limit of the polymerization reaction temperature is more preferably 270°C. The degree of vacuum in the polymerization is preferably 0.5 kPa or higher. When it is 0.5 kPa or higher, the reactivity tends to be good, and the productivity is improved.

[0065] The polyester resin composition obtained can be in the form of pellets (cylindrical chips, etc.), powder, granules, or beads. The pellet form produced by a single screw extruder or twin screw extruder is preferred because of its strong kneading power and ease of subsequent molding.

[0066] <Polyester resin molding> The polyester resin molded article is a molded article using a polyester resin, and is obtained by molding the above-mentioned polyester resin composition. Specifically, for example, the polyester resin composition can be produced by melt-kneading the polyester resin composition and molding the mixture with a conventional molding machine, such as an injection molding machine, an extrusion molding machine, a rotational molding machine, etc., but is not limited thereto.

[0067] Examples of polyester resin molded articles include films, laminates, coatings, fibers, injection molded articles for food and daily necessities, compression injection molded articles, rotational molded articles, and extrusion molded articles. According to an embodiment of the present invention, the polyester resin molded body is uniformly blued without color unevenness, and therefore can be suitably used even in applications where a good appearance is particularly required when the product is seen by consumers during use.

[0068] <<Embodiments of the present invention>> The present invention includes, for example, the following embodiments: The embodiments of the present invention are not limited to the following. [1] A liquid coloring composition used in obtaining a polyester resin by polymerization, The composition includes a diol component (A), a surfactant (B), and a dye (C), The dye (C) is a liquid coloring composition having a solubility of 0.5 g or less in 100 mL of ethylene glycol at 25°C. [2] The liquid coloring composition according to [1], wherein the surfactant (B) is at least one of a nonionic surfactant and an amphoteric surfactant. [3] The liquid coloring composition according to [1] or [2], wherein the surfactant (B) is at least one selected from the group consisting of poly(12-hydroxystearic acid)-polyethyleneimine copolymers, polyoxyethylene alkyl ethers, polyoxyalkylene derivatives, sorbitan fatty acid esters, alkyl betaines, and alkyl amine oxides. [4] The liquid colored composition according to any one of [1] to [3], which contains 0.1 to 50 parts by mass of the surfactant (B) per 100 parts by mass of the diol component (A). [5] The liquid coloring composition according to any one of [1] to [4], wherein the dye (C) is an anthraquinone dye or a perinone dye. [6] A process for producing a polyester resin by polymerizing a dicarboxylic acid component (X) containing at least terephthalic acid and a diol component (Y) containing at least ethylene glycol in the presence of a polymerization catalyst (Z) and a liquid coloring composition, The liquid coloring composition comprises a diol component (A), a surfactant (B), and a dye (C), A method for producing a polyester resin composition, wherein the dye (C) has a solubility of 0.5 g or less in 100 mL of ethylene glycol at 25°C. [7] The method for producing a polyester resin composition according to [6], wherein the polymerization catalyst (Z) is a titanium-based catalyst. [8] The method for producing a polyester resin composition according to [6] or [7], wherein at least one of the dicarboxylic acid component (X) containing at least terephthalic acid and the diol component (Y) containing at least ethylene glycol is a component obtained by depolymerizing a polyester resin. [9] A step of producing a polyester resin composition by polymerizing a dicarboxylic acid component (X) containing at least terephthalic acid and a diol component (Y) containing at least ethylene glycol in the presence of a polymerization catalyst (Z) and a liquid coloring composition; and a step of molding the obtained polyester resin composition. The liquid coloring composition comprises a diol component (A), a surfactant (B), and a dye (C), A method for producing a polyester resin molded product, wherein the dye (C) has a solubility of 0.5 g or less in 100 mL of ethylene glycol at 25°C. EXAMPLES

[0069] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. In the examples, parts and % represent parts by mass and % by mass, respectively, unless otherwise specified. The blend amounts in the table are in parts by mass, calculated as non-volatile content. Note that blank spaces in the table indicate that no blend was made.

[0070] The materials used in the examples and comparative examples are shown below. <Diol component (A)> A1: Ethylene glycol (Maruzen Petrochemical Co., Ltd., melting point -13°C, molecular weight 62) A2: 1,3-propanediol (Tokyo Chemical Industry Co., Ltd., melting point -27°C, molecular weight 76) A3: 1,4-butanediol (manufactured by Mitsubishi Chemical Corporation, melting point 20°C, molecular weight 90) A4: 1,4-cyclohexanedimethanol (Tokyo Chemical Industry Co., Ltd., melting point 52°C, molecular weight 144) A5: Polyethylene glycol 400 (manufactured by Sanyo Chemical Industries, Ltd., melting point 7°C, molecular weight 400) The melting point is a value measured using a differential scanning calorimeter "DSC6200" (manufactured by Seiko Instruments Inc.) under conditions of a temperature range of -30 to 100°C and a heating rate of 10°C / min.

[0071] <Surfactant (B)> B1: Adeka Pluronic L-61 (ADEKA) B2: Adeka Pluronic L-43 (ADEKA) B3: Adeka Pluronic L-35 (ADEKA) B4: Poly(12-hydroxystearic acid)-polyethyleneimine copolymer B5: Emulgen 109P (Kao Corporation) B6: Leodor SP-O30-V (Kao Corporation) B7: Amphitol 20BS (Kao Corporation) B8: Amphitol 20N (Kao Corporation) B9: Ramtel PD-105 (Kao Corporation) B10: Kotamin 24P (Kao Corporation)

[0072] The structure and physical properties of the surfactant (B) are shown below. [Table 1]

[0073] <Dye (C)> C1: Macrolex Blue RR (dye: anthraquinone dye, Solvent Blue 97, manufactured by Lanxess, solubility in 100 mL of ethylene glycol at 25°C is 0.2 g) C2: Sumiplast Violet B (dye: anthraquinone dye, SolventViolet 13, manufactured by Sumika Chemtex Co., Ltd., solubility in 100 mL of ethylene glycol at 25°C is 0.45 g) C3: Diamond Resin Red HS (dye: perinone dye, Solvent Red 135, manufactured by Mitsubishi Chemical Corporation, solubility in 100 mL of ethylene glycol at 25°C is 0.2 g) C'1: Kayala Turquoise Blue GL (dye, Direct Blue 86, manufactured by Nippon Kayaku Co., Ltd., solubility in 100 mL of ethylene glycol at 25°C is 7 g)

[0074] <Pigment (D)> D1: Ultramarine No. 1500 (inorganic pigment, ultramarine, manufactured by Daiichi Chemical Industry Co., Ltd., solubility in 100 mL of ethylene glycol at 25°C is 0.4 g) D2: Lionol Blue FG7330 (organic pigment, phthalocyanine blue, manufactured by Toyo Color Co., Ltd., solubility in 100 mL of ethylene glycol at 25°C is 0.2 g)

[0075] <Plasticizer> DOP: Bis(2-ethylhexyl) phthalate

[0076] <Dicarboxylic acid component (X)> X1: Terephthalic acid synthesized from raw materials X2: Terephthalic acid obtained by depolymerizing polyester resin

[0077] <Diol component (Y)> Y1: Ethylene glycol synthesized from raw materials Y2: Ethylene glycol obtained by depolymerizing polyester resin

[0078] <Polymerization catalyst (Z)> Z1: Titanium oxide Z2: Antimony trioxide

[0079] [Example 1] (Production of liquid colored composition (T1)) 100 parts by mass of the diol component (A), 15 parts by mass of the surfactant (B1), and 120 parts by mass of the dye (C1) were mixed and dispersed in a bead mill to obtain a liquid colored composition (T1).

[0080] [Examples 2 to 33, Comparative Examples 1 and 2] (Production of liquid colored compositions (T2 to 35)) Liquid colored compositions (T2 to 35) were produced in the same manner as liquid colored composition (T1), except that the materials and blending amounts (parts by mass) were changed to those shown in Tables 2 to 5, respectively.

[0081] [Comparative Examples 3 and 4] (Production of liquid colored compositions (T36, 37)) Liquid coloring compositions (T36, 37) were produced in the same manner as liquid coloring composition (T1), except for changing the materials and amounts (parts by mass) shown in Table 5. However, the dispersibility and storage stability of the liquid coloring compositions were poor, and good liquid coloring compositions could not be obtained.

[0082] Evaluation of Liquid Colored Compositions The dispersibility and storage stability of the obtained liquid colored compositions were evaluated by the following methods. The results are shown in Tables 2 to 5.

[0083] (Dispersibility evaluation) The particle size at the cumulative volume percentage of 90% (D 90 ) was measured using a dynamic light scattering particle size distribution measuring device LB-550 (manufactured by Horiba, Ltd.) Evaluation was performed according to the following criteria. [Evaluation Criteria] ◎:D 90 is less than 10μm, which is very good 〇:D 90 is 10μm or more and less than 30μm, which is good △:D 90 is between 30μm and 50μm and is practically usable ×:D 90 is 50μm or more, which is not practical.

[0084] (Storage stability evaluation) The obtained liquid colored composition was allowed to stand for 30 days, and the separation and precipitation of the dye (C) in the liquid colored composition was visually confirmed and evaluated according to the following criteria. [Evaluation Criteria] ◎: No separation or sedimentation, very good 〇: There is some separation and settling, but it becomes uniform when stirred, and is good. △: Separation and sedimentation occur, but the mixture becomes uniform when stirred, making it usable. ×: Separation and sedimentation occurred, and the mixture was not uniform even after stirring. Not practical.

[0085] [Table 2]

[0086] [Table 3]

[0087] [Table 4]

[0088] [Table 5]

[0089] [Example 34] (Production of polyester resin composition) Into a reaction vessel equipped with a distillation column, 69 parts by mass of a dicarboxylic acid component (X1) (terephthalic acid obtained by synthesis from raw materials) and 30.5 parts by mass of a diol component (Y1) (ethylene glycol obtained by synthesis from raw materials) were added, and then 0.0002 parts by mass of a liquid coloring composition (T1) was added so that the content of the dye (C) was 1 ppm based on 100 parts by mass of the polyester resin composition, and further 0.5 parts by mass of a polymerization catalyst (Z1) was added. Next, the rotation speed of the stirring blade in the reaction vessel was kept at 200 rpm, and the temperature was raised to 265 ° C., and the temperature was maintained. After the esterification reaction was completed and water was no longer distilled from the reaction system, the temperature in the reaction system was set to 250 ° C., the reaction system was depressurized over about 40 minutes, the degree of vacuum was set to 0.5 kPa, and a condensation reaction was carried out while distilling the diol component from the reaction system. The viscosity of the reaction system increased with the reaction, and the stirring was stopped when the torque of the stirring blade showed a predetermined torque, the reaction system was returned to normal pressure, and the polyester resin composition was extruded from the nozzle in the form of a strand, cooled with water, and cut to obtain a pellet-shaped (diameter about 2.5 mm, length about 2.5 mm) polyester resin composition.

[0090] [Examples 35 to 69, Comparative Examples 6 and 7] Each polyester resin composition was produced in the same manner as in the polyester resin composition of Example 34, except that the materials and blending amounts (parts by mass) were changed to those shown in Table 6.

[0091] Evaluation of polyester resin composition The polymerization time, hue, color unevenness, and color migration of the obtained polyester resin composition were evaluated by the following methods. The results are shown in Table 6.

[0092] (Polymerization time evaluation) The ratio of the polymerization time (ii) required for the polyester resin composition obtained to the polymerization time (i) required for the polyester resin composition produced without adding the liquid coloring composition was calculated and evaluated using the following formula. Polymerization time ratio (%) = (b) / (a) x 100 [Evaluation Criteria] ◯: Polymerization time ratio is less than 120%, good △: Polymerization time ratio is 120% or more and less than 150%, and practical ×: Polymerization time ratio is 150% or more, and not practical.

[0093] (Hue evaluation) The obtained polyester resin composition and the polyester resin obtained without adding the liquid coloring composition were each molded into a 1 mm thick plate at 280°C using an injection molding machine, and the color difference Δb* in the CIE1976L*a*b* color system was calculated and evaluated using the following formula. Δb*=(chromaticity b* of polyester resin composition obtained without adding liquid coloring composition) - (Color b* of the polyester resin composition obtained in the examples or comparative examples) [Evaluation Criteria] 〇: Δb*<0, bluing is good ×: Δb*≧0, no bluing and defective

[0094] (Color unevenness evaluation) The obtained polyester resin composition was molded into 10 plates with a thickness of 1 mm at 280°C using an injection molding machine, and the hue of each was measured using the CIE1976 L*a*b* color system and evaluated based on the standard deviation of L*, a*, and b* and visually as shown below. [Evaluation Criteria] ○: The standard deviation of L*, a*, and b* is 0.5 or less. No uneven coloring on each plate, excellent △: The standard deviation of L*, a*, and b* is greater than 0.5 and less than 0.6. Each plate has no color unevenness and is practical to use. ×: The standard deviation of each of L*, a*, and b* is greater than 0.6 and is 0.7 or less. Each plate has uneven coloring, making it unusable.

[0095] (Color migration evaluation) The obtained polyester resin composition was molded into a plate having a thickness of 1 mm at 280° C. using an injection molding machine, and the obtained plate was heated to 80° C. and wiped with a cotton cloth, and the color of the cotton cloth was visually confirmed. [Evaluation Criteria] 〇: No coloring of cotton fabric, good condition ×: The cotton fabric is discolored and cannot be used.

[0096] (Mechanical properties) The obtained polyester resin pellets were blow molded at 280°C using a blow molding machine to produce 50 PET bottles with a thickness of 1 mm. An impact test was performed on 10 randomly selected PET bottles. Specifically, 80% of the PET bottles were filled with water and dropped from a height of 1 m. The evaluation criteria were as follows: [Evaluation Criteria] ⊚: No holes were observed in any of the 10 bottles, and less than 5 bottles were deformed. Good: No holes were found in any of the 10 bottles, but deformation was found in 5 to 10 bottles. △: All 10 bottles were deformed, and less than 2 bottles had holes. ×: All 10 bottles were deformed and two or more bottles had holes. [Table 6]

[0097] As shown in Table 6, the liquid coloring composition according to the embodiment of the present invention has excellent dispersibility and storage stability of the coloring material, and further, by using the liquid coloring composition, the polymerization reaction of the polyester resin raw material during the production of the polyester resin is not inhibited, and it is possible to uniformly blue the polyester resin without color unevenness, and it was confirmed that a polyester resin molded product without color migration of the coloring material can be obtained. It was confirmed that even when a titanium catalyst was used as the polymerization catalyst (Z), a polyester resin molded article having a good color tone could be formed. In addition, even if at least one of the dicarboxylic acid component (X) and the diol component (Y) is a compound obtained by depolymerizing a polyester resin, it was confirmed that the compound has excellent polymerization time evaluation, hue, color unevenness, and color migration properties, and can be effectively applied to the reuse of polyester resin.

[0098] In contrast, the liquid coloring composition of Comparative Example 1, in which dye (C) was dispersed in a plasticizer, was practical in terms of dispersibility and storage stability, but the polymerization time of the polyester resin composition was long and there was color unevenness, resulting in the composition being unsuitable for practical use. In addition, the liquid coloring composition of Comparative Example 2, which used a coloring material that dissolves in the raw material of polyester resin, i.e., a hydrophilic coloring material, experienced color transfer of the dye from the molded product, and as a result, it was not possible to practically use the polyester resin composition and its molded product for various applications, particularly those that may be used as beverage containers.

Claims

1. A liquid coloring composition used in obtaining a polyester resin by polymerization, A composition comprising a diol component (A), a surfactant (B), and a dye (C), The diol component (A) has a molecular weight of 1,000 or less, The dye (C) has a solubility of 0.5 g or less in 100 mL of ethylene glycol at 25° C. in a liquid coloring composition.

2. 2. The liquid colored composition according to claim 1, wherein the surfactant (B) is at least one of a nonionic surfactant and an amphoteric surfactant.

3. The liquid coloring composition according to claim 1, wherein the surfactant (B) is at least one selected from the group consisting of poly(12-hydroxystearic acid)-polyethyleneimine copolymers, polyoxyethylene alkyl ethers, polyoxyalkylene derivatives, sorbitan fatty acid esters, alkyl betaines, and alkyl amine oxides.

4. The liquid colored composition according to any one of claims 1 to 3, comprising 0.1 to 50 parts by mass of the surfactant (B) per 100 parts by mass of the diol component (A).

5. 4. The liquid colored composition according to claim 1, wherein the dye (C) is an anthraquinone dye or a perinone dye.

6. The liquid coloring composition according to any one of claims 1 to 3, comprising 1 to 150 parts by mass of the dye (C) per 100 parts by mass of the diol component (A).

7. This is used when a polyester resin is obtained by polymerization of a dicarboxylic acid component (X) containing at least terephthalic acid and a diol component (Y) containing at least ethylene glycol, 4. The liquid colored composition according to claim 1, wherein the diol component (A) contains at least ethylene glycol.

8. The method includes a step of polymerizing a dicarboxylic acid component (X) containing at least terephthalic acid and a diol component (Y) containing at least ethylene glycol in the presence of a polymerization catalyst (Z) and a liquid coloring composition to produce a polyester resin composition, The liquid coloring composition contains a diol component (A), a surfactant (B), and a dye (C), The diol component (A) has a molecular weight of 1,000 or less, The method for producing a polyester resin composition, wherein the dye (C) has a solubility of 0.5 g or less in 100 mL of ethylene glycol at 25°C.

9. The method for producing a polyester resin composition according to claim 8, wherein the diol component (A) contains at least ethylene glycol.

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