Thermoplastic resin composition, molded body, method for producing thermoplastic resin composition, and method for producing molded body

Abstract

This thermoplastic resin composition contains a modified maleic anhydride-styrene copolymer (A), near-infrared absorbing metal oxide particles (B), and a thermoplastic resin (C). The blending amount of the modified maleic anhydride-styrene copolymer (A) is 20-150 mass parts per 100 mass parts of the near-infrared absorbing metal oxide particles (B), and the number of near-infrared absorbing metal oxide particles (B) exceeding 2 μm is 50 or fewer in a square 200 μm field of view observed under a microscope.

Description

Thermoplastic resin composition, molded article, method for producing thermoplastic resin composition, and method for producing molded article

[0001] The present invention relates to a thermoplastic resin composition, a molded article, a method for producing a thermoplastic resin composition, and a method for producing a molded article, and in particular to a thermoplastic resin composition containing near-infrared absorbing metal oxide particles. This application claims priority based on Japanese Patent Application No. 2024-109064, filed in Japan on July 5, 2024, the contents of which are incorporated herein by reference.

[0002] Resin products that have the property of absorbing light in the near-infrared wavelength range and generating heat include fibers, clothing made from such fibers, and films. To impart this property to these products, a material that absorbs near-infrared rays must be applied to the surface of the product or dispersed within it. From the standpoint of durability, it is preferable to disperse the material within the product, but the state of dispersion can affect the property and processability.

[0003] As conventional near-infrared absorbing materials, for example, tungsten oxide microparticles and composite tungsten oxide microparticles have been disclosed as materials with high transmittance for light in the visible light region and low transmittance for light in the near-infrared region, and fibers and the like incorporating such near-infrared absorbing materials have also been disclosed (Patent Document 1).

[0004] Furthermore, a conventional method for producing a thermoplastic resin composition containing a near-infrared absorbing material includes a step of kneading composite particles containing a dispersant and fine particles such as tungsten-based oxide coated with the dispersant, a compatibilizer, and polyethylene, wherein the dispersant for the composite particles contains a polar group-containing resin, and the compatibilizer is a polar group-containing polyolefin (Patent Documents 2 and 3). These disclosures state that by treating the fine particles with a dispersant containing a polar group-containing resin and then kneading using a polar group-containing polyolefin as a compatibilizer, the dispersibility of the fine particles such as composite tungsten-based oxide in polyethylene or polypropylene and the processability for film formation are improved.

[0005] Patent No. 7226321 Patent No. 7190877 Patent No. 7190878

[0006] However, in Patent Document 1, the near-infrared absorbing material and the thermoplastic resin are simply melt-kneaded, and therefore the dispersibility of the near-infrared absorbing material is not sufficient, which causes problems such as poor processing stability in spinning and film formation due to secondary aggregation and an increase in the haze value of the film.

[0007] In addition, in Patent Documents 2 and 3, because polyethylene or polypropylene is non-polar, the affinity between polyethylene or polypropylene and the dispersant and compatibilizer is low, and the dispersibility of the fine particles during kneading is not sufficient. In particular, high dispersibility is required when melt-molding fibers using the thermoplastic resin composition, but it is difficult to achieve dispersibility sufficient to fiberize the thermoplastic resin composition using the above-mentioned production method. In addition, because the heat resistance of the above-mentioned compatibilizer is low, adding a polar group-containing polyolefin to a high-melting point thermoplastic resin such as polyethylene terephthalate or polyamide may deteriorate processability.

[0008] The present invention aims to provide a particle-containing thermoplastic resin composition, a molded article, a method for producing a particle-containing thermoplastic resin composition, and a molded article, which can improve dispersibility to achieve excellent near-infrared absorption in molded articles, and can also improve processability while suppressing the occurrence of problems and defects during molding.

[0009] As a result of extensive research, the present inventors have discovered that adding a modified maleic anhydride-styrene copolymer to a thermoplastic resin composition containing near-infrared absorbing metal oxide particles results in: (a) the modified maleic anhydride-styrene copolymer possesses both the hydrophilic properties derived from maleic anhydride and the hydrophobic properties derived from styrene, thereby improving the affinity between the hydrophilic moieties and the near-infrared absorbing metal oxide particles, and also improving the affinity between the hydrophobic moieties and the thermoplastic resin; and (b) bonding of other compounds to the modified moieties of the modified maleic anhydride unit structure gives the copolymer a comb-like structure, thereby maintaining the interparticle distance of the near-infrared absorbing metal oxide particles in the thermoplastic resin composition. This improves the dispersibility and stability of the near-infrared absorbing metal oxide in the thermoplastic resin composition. Furthermore, the present inventors have discovered that this improves processability while suppressing the occurrence of problems such as thread breakage and defects when molding fibers, films, and the like, and also enables the realization of excellent optical properties in molded fiber structures and film products.

[0010] That is, the present invention provides the following configuration: [1] A thermoplastic resin composition containing a modified maleic anhydride-styrene copolymer (A), near-infrared absorbing metal oxide particles (B), and a thermoplastic resin (C), wherein the amount of the modified maleic anhydride-styrene copolymer (A) blended per 100 parts by mass of the near-infrared absorbing metal oxide particles (B) is 20 to 150 parts by mass, and the number of particles of the near-infrared absorbing metal oxide particles (B) exceeding 2 μm is 50 or less within a square 200 μm visual field observed under a microscope.

[0011] [2] The thermoplastic resin composition according to [1], wherein the weight average molecular weight of the modified maleic anhydride-styrene copolymer (A) is 1,000 to 20,000.

[0012] [3] The thermoplastic resin composition according to [1], wherein the near-infrared absorbing metal oxide particles (B) are surface-modified with a dispersant (b) having a polar group, and at least a portion of the modified maleic anhydride-styrene copolymer (A) is bonded to the near-infrared absorbing metal oxide particles (B) via the dispersant (b).

[0013] [4] The thermoplastic resin composition according to [1], wherein the near-infrared absorbing metal oxide particles (B) are one or more selected from the group consisting of cesium tungsten oxide, indium tin oxide, and antimony tin oxide.

[0014] [5] The thermoplastic resin composition according to [1], characterized in that the thermoplastic resin (C) is one or more selected from the group consisting of polyester-based resins, polyamide-based resins, and polyurethane-based resins.

[0015] [6] A molded article which is a melt-molded product of the thermoplastic resin composition according to [1] or [2].

[0016] [7] A method for producing a thermoplastic resin composition, comprising a step of mixing a modified maleic anhydride-styrene copolymer (A), near-infrared absorbing metal oxide particles (B), and a thermoplastic resin (C), and melt-kneading the mixture at a temperature equal to or higher than the melting point of the thermoplastic resin (C), wherein the amount of the modified maleic anhydride-styrene copolymer (A) blended per 100 parts by mass of the near-infrared absorbing metal oxide particles (B) is 20 parts by mass to 150 parts by mass, and the number of near-infrared absorbing metal oxide particles (B) exceeding 2 μm is 50 or less within a square 200 μm visual field observed under a microscope.

[0017] [8] The method for producing the thermoplastic resin composition according to [7], comprising a step of preparing an aqueous dispersion of the near-infrared absorbing metal oxide particles (B), and mixing the modified maleic anhydride-styrene copolymer (A), the aqueous dispersion of the near-infrared absorbing metal oxide particles (B), and a thermoplastic resin (C).

[0018] [9] The method for producing a thermoplastic resin composition according to [7], wherein the weight average molecular weight of the modified maleic anhydride-styrene copolymer (A) is 1,000 to 20,000.

[0019]

[10] The method for producing a thermoplastic resin composition according to [7], wherein the modified maleic anhydride-styrene copolymer (A) has a pH of 5 to 9 when made into a 10% by mass aqueous solution.

[0020]

[11] The method for producing a thermoplastic resin composition according to [7], wherein the near-infrared absorbing metal oxide particles (B) are surface-modified with a dispersant (b) having a polar group, and at least a portion of the modified maleic anhydride-styrene copolymer (A) is bonded to the near-infrared absorbing metal oxide particles (B) via the dispersant (b).

[0021]

[12] The method for producing a thermoplastic resin composition according to [7], wherein the near-infrared absorbing metal oxide particles (B) are one or more selected from the group consisting of cesium tungsten oxide, indium tin oxide, and antimony tin oxide.

[0022]

[13] The method for producing a thermoplastic resin composition according to [7], wherein the thermoplastic resin (C) is one or more selected from the group consisting of polyester-based resins, polyamide-based resins, and polyurethane-based resins.

[0023]

[14] A method for producing a molded article, comprising a step of melt-molding a thermoplastic resin composition obtained by the method according to [7].

[0024] According to the present invention, it is possible to improve dispersibility and realize excellent near-infrared absorptivity of a molded product, and also to improve processability while suppressing the occurrence of problems and defects during molding.

[0025] Fig. 1 is a diagram showing an optical microscope image when the dispersion state of the thermoplastic resin composition obtained in Example 3 was evaluated. Fig. 2 is a diagram showing an optical microscope image when the dispersion state of the thermoplastic resin composition obtained in Comparative Example 3 was evaluated.

[0026] An example of the present invention will be described below, but the scope of the present invention is not limited to the embodiment described here, and various modifications can be made without departing from the spirit of the present invention. Furthermore, when multiple upper and lower limit values ​​are listed for a specific parameter, any of these upper and lower limit values ​​can be combined to form a suitable numerical range.

[0027] <Thermoplastic Resin Composition> The thermoplastic resin composition of the present embodiment is a thermoplastic resin composition containing a modified maleic anhydride-styrene copolymer (A), near-infrared absorbing metal oxide particles (B), and a thermoplastic resin (C), in which the blending amount of the modified maleic anhydride-styrene copolymer (A) per 100 parts by mass of the near-infrared absorbing metal oxide particles (B) is 20 parts by mass to 150 parts by mass, and the number of near-infrared absorbing metal oxide particles (B) exceeding 2 μm is 50 or less within a square 200 μm visual field observed with a microscope.

[0028] (Modified maleic anhydride-styrene copolymer (A)) The modified maleic anhydride-styrene copolymer (A) is not particularly limited as long as it is a copolymer of modified maleic anhydride and styrene. The modified maleic anhydride-styrene copolymer (A) may have one type of modified maleic anhydride as a unit structure, or may have two or more types of modified maleic anhydride. Furthermore, the thermoplastic resin composition may contain a copolymer of maleic anhydride and styrene (hereinafter also referred to as "unmodified maleic anhydride-styrene copolymer"), provided that it contains the modified maleic anhydride-styrene copolymer (A).

[0029] In this embodiment, the amount of the modified maleic anhydride-styrene copolymer (A) blended relative to 100 parts by mass of the near-infrared absorbing metal oxide particles (B) is 20 to 150 parts by mass, preferably 25 to 130 parts by mass, and more preferably 30 to 110 parts by mass. By blending the amount of the modified maleic anhydride-styrene copolymer (A) of 20 to 150 parts by mass relative to 100 parts by mass of the near-infrared absorbing metal oxide particles (B), the modified maleic anhydride-styrene copolymer (A) can be present at a high concentration at the interface between the near-infrared absorbing metal oxide particles (B) and the thermoplastic resin (C), which increases the affinity between the near-infrared absorbing metal oxide particles (B) and the thermoplastic resin (C) and improves dispersibility.

[0030] The weight average molecular weight of the modified maleic anhydride-styrene copolymer (A) is preferably 1,000 to 20,000, more preferably 1,500 to 15,000, and even more preferably 2,000 to 10,000. When the weight average molecular weight of the modified maleic anhydride-styrene copolymer (A) is 1,000 to 20,000, the dispersibility of the near infrared absorbing metal oxide particles (B) in the thermoplastic resin (C) can be further improved.

[0031] The modified maleic anhydride-styrene copolymer (A) is not particularly limited as long as the carboxylic acid groups of the maleic acid-styrene copolymer are modified with a modifying agent, but the maleic acid-styrene copolymer may be one in which some or all of the carboxylic acid groups are modified with a modifying agent.

[0032] The modifying agent is not particularly limited, but examples thereof include compounds having a hydroxyl group, an amino group, an epoxy group, etc. Furthermore, one type of compound may be used as the modifying agent, or two or more types of compounds may be used as the modifying agent.

[0033] Specific examples of the modified maleic anhydride-styrene copolymer (A) include DISPERBYK-2010, DISPERBYK-2012, DISPERBYK-2013, DISPERBYK-2015, DISPERBYK-190, BYKJET-1951, and BYKJET-9152 manufactured by BYK Japan KK Of these, DISPERBYK-2012, DISPERBYK-2013, DISPERBYK-2015, and DISPERBYK-190 are preferred because they have high solubility in water at room temperature.

[0034] (Near-infrared absorbing metal oxide particles (B)) The near-infrared absorbing metal oxide particles (B) are not particularly limited as long as they are oxide particles that absorb light with wavelengths in the near-infrared region. It is preferred that the near-infrared absorbing metal oxide particles (B) are surface-modified with a dispersant (b) having a polar group, and that at least a portion of the modified maleic anhydride-styrene copolymer (A) is bonded to the near-infrared absorbing metal oxide particles (B) via the dispersant (b). The dispersant (b) having a polar group is added to the particles during production of the near-infrared absorbing metal oxide particles (B) from the perspective of dispersibility, but has low affinity with the thermoplastic resin (C) and can be a cause of secondary aggregation during melt molding of the thermoplastic resin composition. In this embodiment, when the near-infrared absorbing metal oxide particles (B) are surface-modified with a dispersant (b) having a polar group, the affinity with the thermoplastic resin (C) can be improved by bonding the dispersant (b) to at least a part of the modified maleic anhydride-styrene copolymer (A), thereby suppressing secondary aggregation of the near-infrared absorbing metal oxide particles (B) and improving dispersibility.

[0035] Examples of the dispersant (b) having a polar group include compounds having one or more groups selected from an amino group, a hydroxyl group, a carboxyl group, and an epoxy group. Specific examples of the dispersant (b) include SOLSPERSE 3000, SOLSPERSE 9000, SOLSPERSE 11200, SOLSPERSE 56000, etc. manufactured by Lubrizol Japan; DISPERBYK-101, DISPERBYK-164, DISPERBYK-181, DISPERBYK-184, etc. manufactured by BYK Japan; ALFON UC-3000, ALFON UF-5022, ALFON UG-4010, ALFON UG-4070, etc. manufactured by Toagosei Co., Ltd.; and AJISPER PB-711, AJISPER PB-821, AJISPER PB-822, etc. manufactured by Ajinomoto Fine-Techno Co., Ltd.

[0036] Specific examples of the near-infrared absorbing metal oxide particles (B) include one or more selected from the group consisting of cesium tungsten oxide (CWO), indium tin oxide (ITO), and antimony tin oxide (ATO). Among these, cesium tungsten oxide is preferred from the viewpoint of near-infrared absorbing performance.

[0037] In this embodiment, within a square 200 μm field of view observed under a microscope, the number of near-infrared absorbing metal oxide particles (B) exceeding 2 μm in size is 50 or less, preferably 30 or less, and more preferably 10 or less. By ensuring that the number of near-infrared absorbing metal oxide particles (B) exceeding 2 μm within the above field of view is 50 or less, processability such as spinnability, transparency of molded articles, and near-infrared absorbency can be improved. Furthermore, although the content of near-infrared absorbing metal oxide particles (B) is limited depending on the specifications of the thermoplastic resin composition, high near-infrared absorbency can be exhibited even when the content of near-infrared absorbing metal oxide particles (B) is low.

[0038] The average primary particle size of the near-infrared absorbing metal oxide particles (B) is not particularly limited, but is preferably 10 nm to 200 nm, more preferably 20 nm to 150 nm, and even more preferably 30 nm to 120 nm. By making the average primary particle size of the near-infrared absorbing metal oxide particles (B) 30 nm to 120 nm, a good balance between near-infrared absorbency and dispersibility can be achieved.

[0039] (Thermoplastic resin (C)) The thermoplastic resin (C) is not particularly limited as long as it is a resin having thermoplastic properties. Specific examples of the thermoplastic resin (C) include one or more types selected from the group consisting of polyester-based resins, polyamide-based resins, and polyurethane-based resins.

[0040] Examples of polyester resins include polyethylene terephthalate, polybutylene terephthalate, polytrimethylene terephthalate, polytetramethylene terephthalate, polycyclohexanedimethylene terephthalate, polyethylene-2,6-naphthalenedicarboxylate, polylactic acid, etc. Furthermore, these polyesters may be copolymers in which an alcohol component such as butanediol or a dicarboxylic acid such as isophthalic acid is copolymerized as a third component, or a mixture of these various polyesters may also be used.

[0041] Examples of polyamide-based resins include aliphatic polyamides such as polyamide 6, polyamide 66, polyamide 610, polyamide 10, polyamide 1010, polyamide 11, polyamide 12, and polyamide 6-12, and copolymers thereof; and semi-aromatic polyamides synthesized from aromatic dicarboxylic acids and aliphatic diamines.

[0042] Examples of polyurethane resins include ether-based polyurethane resins and ester-based polyurethane resins. Any ether-based polyurethane resin may be used as long as it has an ether bond in the molecule, and a resin obtained from a polymer diol having an ether bond and an organic diisocyanate may be used as raw materials. Any ester-based polyurethane resin may be used as long as it has an ester bond in the molecule, and a resin obtained from a polymer diol having an ester bond and an organic diisocyanate may be used as raw materials.

[0043] Methods for determining resin decomposition of the thermoplastic resin composition of this embodiment include, for example, intrinsic viscosity (IV), melt flow rate (MFR), and melt volume rate (MVR). Of these, polyester-based resins are expressed by intrinsic viscosity (IV). The retention of IV (intrinsic viscosity) measured according to the following formula (1) in accordance with JIS K7390 is preferably 70% or more, and more preferably 80% or more. An IV retention of 70% or more can prevent problems such as molding difficulties and deterioration of the physical properties of molded products. IV retention (%) = measured IV value of thermoplastic resin composition / IV of polyethylene terephthalate × 100% ... formula (1)

[0044] <Molded Article> The molded article according to this embodiment is a melt-molded product of the thermoplastic resin composition. The molded article is not particularly limited, but examples thereof include fibers, films, and fiber structures.

[0045] (Fibers) The fibers of this embodiment can be obtained, for example, by melt-spinning the thermoplastic resin composition. The fibers may be obtained by mixing a masterbatch composed of the thermoplastic resin composition with another thermoplastic resin to obtain a thermoplastic resin composition, and then melt-spinning the thermoplastic resin composition.

[0046] The fibers contain a modified maleic anhydride-styrene copolymer (A), near-infrared absorbing metal oxide particles (B), and a thermoplastic resin (C). The types and contents of the components constituting the fibers can be the same as those of the thermoplastic resin composition described above. Furthermore, the fibers may contain one or more other components, provided that they contain the modified maleic anhydride-styrene copolymer (A), near-infrared absorbing metal oxide particles (B), and a thermoplastic resin (C).

[0047] (Film) The film of the present embodiment is obtained by forming the above-described thermoplastic resin composition into a film. The film may be obtained by mixing a masterbatch composed of the above-described thermoplastic resin composition with another thermoplastic resin to obtain a thermoplastic resin composition, and then forming the thermoplastic resin composition into a film.

[0048] The film contains a modified maleic anhydride-styrene copolymer (A), near-infrared absorbing metal oxide particles (B), and a thermoplastic resin (C). The types and contents of the components constituting the film can be the same as those of the thermoplastic resin composition described above. Furthermore, the film may contain one or more other components, provided that it contains the modified maleic anhydride-styrene copolymer (A), near-infrared absorbing metal oxide particles (B), and a thermoplastic resin (C).

[0049] (Fiber Structure) The fiber structure of this embodiment is partially or entirely composed of the above-mentioned fibers. Examples of the fiber structure include cloth, felt, and sheet-like materials.

[0050] <Method for producing thermoplastic resin composition> The method for producing a thermoplastic resin composition according to this embodiment is a method for producing a thermoplastic resin composition, comprising the steps of mixing a modified maleic anhydride-styrene copolymer (A), near-infrared absorbing metal oxide particles (B), and a thermoplastic resin (C), and melt-kneading the mixture at a temperature equal to or higher than the melting point of the thermoplastic resin (C), wherein the amount of the modified maleic anhydride-styrene copolymer (A) blended per 100 parts by mass of the near-infrared absorbing metal oxide particles (B) is 20 parts by mass to 150 parts by mass, and the number of near-infrared absorbing metal oxide particles (B) exceeding 2 μm is 50 or less within a square 200 μm visual field observed under a microscope.

[0051] In the above step, a mixture of modified maleic anhydride-styrene copolymer (A), near-infrared absorbing metal oxide particles (B), and thermoplastic resin (C) is melt-kneaded at a temperature equal to or higher than the melting point of thermoplastic resin (C). By melt-kneading the mixture at a temperature equal to or higher than the melting point of thermoplastic resin (C), the dispersibility of near-infrared absorbing metal oxide particles (B) in the thermoplastic resin composition can be improved. When thermoplastic resin (C) is composed of multiple types of thermoplastic resins, it is preferable to select a thermoplastic resin with the highest melting point from the multiple types of thermoplastic resins and melt-knead the resins at a temperature equal to or higher than that melting point.

[0052] The method for melt-kneading the mixture is not particularly limited as long as it can be melt-kneaded while adjusting the temperature, and can be carried out using a known device such as a twin-screw extruder.

[0053] The modified maleic anhydride-styrene copolymer (A) used in the above step preferably has a weight-average molecular weight of 1,000 to 20,000, more preferably 1,500 to 15,000, and even more preferably 2,000 to 10,000. When the weight-average molecular weight of the modified maleic anhydride-styrene copolymer (A) is 1,000 to 20,000, gas generation due to volatilization during processing is suppressed, and the amount remaining in the thermoplastic resin composition is increased, thereby improving heat resistance and also suppressing an increase in viscosity, thereby improving productivity.

[0054] The modified maleic anhydride-styrene copolymer (A) is not particularly limited, and may have one type of amine-modified maleic anhydride or two or more types of amine-modified maleic anhydride as a unit structure. When the modified maleic anhydride-styrene copolymer (A) has two types of amine-modified maleic anhydride as unit structures, for example, it may be a copolymer in which two types of amines are grafted to form a maleimide skeleton. Specific examples of the modified maleic anhydride-styrene copolymer (A) that can be used include those with the same structures as above.

[0055] In the above process, the modified maleic anhydride-styrene copolymer (A) may be added to a melt kneader together with the near-infrared absorbing metal oxide particles (B) and the thermoplastic resin (C), or may be mixed with the near-infrared absorbing metal oxide particles (B) and then added to the melt kneader together with the thermoplastic resin (C). From the viewpoint of improving dispersibility, it is preferable to mix the modified maleic anhydride-styrene copolymer (A) with the near-infrared absorbing metal oxide particles (B) and then add the mixed solution together with the thermoplastic resin (C) to the melt kneader. Furthermore, the pH of the modified maleic anhydride-styrene copolymer (A) when made into a 10% by mass aqueous solution is preferably 5 to 9, more preferably 5.5 to 8.5. By making the pH of the modified maleic anhydride-styrene copolymer (A) 5 to 9 when made into a 10% by mass aqueous solution, hydrolysis of the thermoplastic resin during processing can be suppressed.

[0056] Specific examples of the near-infrared absorbing metal oxide particles (B) used in the above step include one or more selected from the group consisting of cesium tungsten oxide (CWO), indium tin oxide (ITO), and antimony tin oxide (ATO). Among these, cesium tungsten oxide is preferred from the viewpoint of near-infrared absorbing performance.

[0057] In the above process, the near-infrared absorbing metal oxide particles (B) may be mixed in the form of a powder or an aqueous dispersion. When the near-infrared absorbing metal oxide particles (B) are mixed in the form of a powder, the presence of the modified maleic anhydride-styrene copolymer (A) can sufficiently improve dispersibility. When the near-infrared absorbing metal oxide particles (B) are mixed in the form of an aqueous dispersion, an aqueous dispersion of the near-infrared absorbing metal oxide particles (B) is prepared, and the modified maleic anhydride-styrene copolymer (A), the aqueous dispersion of the near-infrared absorbing metal oxide particles (B), and the thermoplastic resin (C) are mixed. This can further promote dispersibility. The content of the near-infrared absorbing metal oxide particles (B) in the aqueous dispersion is preferably 10% by mass to 60% by mass, more preferably 20% by mass to 40% by mass.

[0058] The near-infrared absorbing metal oxide particles (B) are surface-modified with a dispersant (b) having a polar group, and may be further treated with a modified maleic anhydride-styrene copolymer (A) in the above step. That is, at least a portion of the modified maleic anhydride-styrene copolymer (A) may be bonded to the near-infrared absorbing metal oxide particles (B) via the dispersant (b). Specific examples of the dispersant (b) having a polar group may have the same configuration as described above.

[0059] The thermoplastic resin (C) may be one or more types selected from the group consisting of polyester-based resins, polyamide-based resins, and polyurethane-based resins. It is preferable to melt-knead at a temperature equal to or higher than the melting point of the thermoplastic resin (C). When the thermoplastic resin (C) is a plurality of types selected from the group consisting of polyester-based resins, polyamide-based resins, and polyurethane-based resins, it is preferable to select the thermoplastic resin with the highest melting point among the thermoplastic resins and melt-knead at a temperature equal to or higher than that melting point, and more preferably melt-knead at a temperature within the range of melting point + 20°C to melting point + 50°C.

[0060] <Method for Producing Molded Article> The method for producing a molded article according to this embodiment includes a step of melt-molding the thermoplastic resin composition obtained by the above-described manufacturing method. When melt-molding fibers as a molded article, the thermoplastic resin composition obtained by the above-described manufacturing method can be melt-spun. A commonly used melt spinning apparatus can be used for melt spinning. Alternatively, fibers may be obtained by mixing a masterbatch composed of the above-described thermoplastic resin composition with another thermoplastic resin to obtain a thermoplastic resin composition, which may then be melt-spun. When melt-molding a film as a molded article, the thermoplastic resin composition obtained by the above-described manufacturing method is formed into a film. The film forming method is not particularly limited, and examples include a heat press method, a single-layer or multi-layer inflation method, and a T-die method. Alternatively, a film may be obtained by mixing a masterbatch composed of the above-described thermoplastic resin composition with another thermoplastic resin to obtain a thermoplastic resin composition, which may then be formed into a film.

[0061] The thermoplastic resin composition and molded article according to this embodiment can be produced by the above-described method for producing a thermoplastic resin composition and method for producing a molded article.

[0062] The present invention will now be described in more detail with reference to examples, but the present invention is not limited to the following examples.

[0063] <<Experiment A: Preparation and Evaluation of Near-Infrared Absorbing Thermoplastic Resin Film>> (Example 1) 49.33 parts by mass of polyamide 11 (Rilsan (registered trademark) BMNO, manufactured by ARKEMA) which is a thermoplastic resin, and a dispersant-treated cesium tungsten oxide aqueous dispersion (YMW-D20, manufactured by Sumitomo Metal Mining Co., Ltd.) were used. ０．３３ WO ３ 2.5 parts by mass of PEG-1000 (20% by mass) and 0.17 parts by mass of a dispersant DISPERBYK-2013 (manufactured by BYK Japan, modified maleic anhydride-styrene copolymer, weight average molecular weight 5200, pH 6.05, non-volatile content 100%) were kneaded in a Labo Plastomill to obtain the thermoplastic resin composition of Example 1. This thermoplastic resin composition was formed into a film using a heat press to obtain near-infrared absorbing thermoplastic resin film 1 having a thickness of 110 μm and containing 1.0 wt % of CWO (also referred to as CsWO).

[0064] Example 2: 47.66 parts by mass of thermoplastic resin polyamide 11 (Rilsan (registered trademark) BMNO, manufactured by ARKEMA), cesium tungsten oxide powder treated with a dispersant (YMDS-874, manufactured by Sumitomo Metal Mining Co., Ltd.), and ０．３３ WO ３ 2.17 parts by mass of PEG-1000 (23% by mass) and 0.17 parts by mass of a dispersant DISPERBYK-2013 (manufactured by BYK Japan, modified maleic anhydride-styrene copolymer, weight average molecular weight 5200, pH 6.05, non-volatile content 100%) were kneaded in a Laboplastomill to obtain a thermoplastic resin composition of Example 2. This thermoplastic resin composition was formed into a film using a heat press machine to obtain a near-infrared absorbing thermoplastic resin film 2 containing 1.0 wt% of CWO and having a thickness of 110 μm.

[0065] Comparative Example 1: 47.83 parts by mass of polyamide 11 (Rilsan (registered trademark) BMNO, manufactured by ARKEMA) which is a thermoplastic resin, cesium tungsten oxide powder (YMDS-874, manufactured by Sumitomo Metal Mining Co., Ltd.) treated with a dispersant, and ０．３３ WO ３2.17 parts by mass of a copolymer of 1.0 wt % CWO and ...

[0066] Comparative Example 2: 47.41 parts by mass of thermoplastic resin polyamide 11 (Rilsan (registered trademark) BMNO, manufactured by ARKEMA), cesium tungsten oxide aqueous dispersion treated with a dispersant (YMW-D20, manufactured by Sumitomo Metal Mining Co., Ltd.), and ０．３３ WO ３ 2.5 parts by mass of PEG-1000 (20% by mass) and 0.09 parts by mass of a dispersant DISPERBYK-2013 (manufactured by BYK Japan, modified maleic anhydride-styrene copolymer, weight average molecular weight 5200, pH 6.05, non-volatile content 100%) were kneaded in a Laboplastomill to obtain a thermoplastic resin composition of Comparative Example 2. This thermoplastic resin composition was formed into a film using a heat press machine to obtain a near-infrared absorbing thermoplastic resin film 4 containing 1.0 wt% of CWO and having a thickness of 110 μm.

[0067] Reference Example 1 50 parts by mass of polyamide 11 (Rilsan (registered trademark) BMNO, manufactured by ARKEMA) which is a thermoplastic resin was kneaded in a Laboplastomill to obtain a thermoplastic resin composition of Reference Example 1. This thermoplastic resin composition was formed into a film using a heat press machine to obtain a thermoplastic resin film 5 having a thickness of 110 μm.

[0068] <Evaluation> [Dispersion state] The thermoplastic resin compositions obtained in the examples and comparative examples were sandwiched between two glass slides using a hot plate to produce films of 100 μm or less. Using an optical microscope (Nikon Solutions, ECLIPSE LV100 model) in a transmission mode, the number of near-infrared absorbing metal oxide particles exceeding a predetermined particle size in the film was counted. At an observation magnification of 200, if the number of particles exceeding 2 μm in a square 200 μm field of view was 10 or less, it was evaluated as very good (◎); if it was more than 10 and 50 or less, it was evaluated as good (◯); and if it was more than 50, it was evaluated as poor (×). [Evaluation criteria] 10 or less particles exceeding 2 μm: very good (◎); more than 10 and 50 or less particles exceeding 2 μm: good (◯); more than 50 particles exceeding 2 μm: poor (×).

[0069] [Haze Measurement (1)] Using a haze meter (manufactured by Nippon Denshoku Industries Co., Ltd., NDH70002II type), the haze of the films obtained in the examples and comparative examples was measured in accordance with JIS K7361. When the haze difference from the thermoplastic resin (haze value 2.35%) to which near-infrared absorbing metal oxide particles were not added was less than 1.0%, it was evaluated as very good (◎), when it was 1.0% or more and 5.0% or less, it was evaluated as good (◯), and when it was more than 5.0%, it was evaluated as poor (×). [Evaluation Criteria] Haze difference less than 1.0%... very good (◎) Haze difference 1.0% or more and 5.0% or less... good (◯) Haze difference more than 5.0%... poor (×)

[0070] The evaluation results of the above examples and comparative examples are shown in Table 1.

[0071]

[0072] From the results in Table 1 above, in Examples 1 and 2, the blending amount of the modified maleic anhydride-styrene copolymer (A) per 100 parts by mass of the near-infrared absorbing metal oxide particles (B) was in the range of 20 to 150 parts by mass, and the number of CWO particles exceeding 2 μm was 50 or less within a square 200 μm field of view observed with an electron microscope. Therefore, it was found that the dispersibility of the CWO particles in the thermoplastic resin composition was excellent, and the haze difference of the obtained near-infrared absorbing thermoplastic resin film was small and the transparency was excellent. Furthermore, in Example 1, when a thermoplastic resin composition was prepared using an aqueous dispersion of the near-infrared absorbing metal oxide particles (B), the dispersibility of the near-infrared absorbing metal oxide particles (B) in the thermoplastic resin composition was excellent, and the haze difference of the obtained near-infrared absorbing thermoplastic resin film was small and the transparency was excellent, compared to Example 2, which used a powder of the near-infrared absorbing metal oxide particles (B).

[0073] On the other hand, in Comparative Example 1, the modified maleic anhydride-styrene copolymer (A) was not contained in the thermoplastic resin composition, and the dispersibility of the near-infrared absorbing metal oxide particles (B) was poor. Furthermore, the haze difference of the obtained near-infrared absorbing thermoplastic resin film was large, and the transparency was poor. In Comparative Example 2, the blending amount of the modified maleic anhydride-styrene copolymer (A) per 100 parts by mass of the near-infrared absorbing metal oxide particles (B) was less than 20 parts by mass, and although the haze difference of the obtained near-infrared absorbing thermoplastic resin film was small, the dispersibility of the near-infrared absorbing metal oxide particles (B) was poor.

[0074] <<Experiment B: Evaluation of Fiber and Knitted Fabric>> (Example 3) <Preparation of CWO Masterbatch> 90 parts by mass of polyethylene terephthalate (manufactured by Mitsui Chemicals, Inc., J125S, IV value 0.76), which is a thermoplastic resin, and cesium tungsten oxide aqueous dispersion (manufactured by Sumitomo Metal Mining Co., Ltd., YMW-D20, Cs ０．３３ WO ３25 parts by mass of the hydroxybenzoate (20% by mass) and 5 parts by mass of a dispersant DISPERBYK-2013 (manufactured by BYK Japan, modified maleic anhydride-styrene copolymer, weight average molecular weight 5200, pH 6.05, non-volatile content 100%) were melt-kneaded in an 18 mmφ twin-screw extruder (set temperature 280°C, mesh filter with a capture particle size of 20 μm). The obtained thermoplastic resin composition was pelletized to obtain a masterbatch (1).

[0075] <Spinning> Using a multifilament melt spinning apparatus, 210 parts by mass of masterbatch (1) (equivalent to 10.5 parts by mass of CWO) and 840 parts by mass of polyethylene terephthalate (J125S, manufactured by Mitsui Chemicals, Inc.) were used as spinning raw materials, and spinning was carried out for 1 hour at a spinning temperature of 280°C, an extrusion rate of 1 kg / h, and a take-up speed of 1000 m / min, to obtain a near-infrared absorbing multifilament fiber containing 1.0 wt% CWO.

[0076] <Preparation of knitted fabric> The near-infrared absorbing multifilament fiber was used to knit a knitted fabric with a gauge of 30 and a basis weight of 150 g / m using a cylindrical knitting machine. ２ A knitted fabric was produced.

[0077] Example 4 Preparation of a CWO Masterbatch A CWO masterbatch was prepared by dispersing 90 parts by mass of polyethylene terephthalate (J125S, manufactured by Mitsui Chemicals, Inc., IV value 0.76) which is a thermoplastic resin, cesium tungsten oxide aqueous dispersion (YMW-D20, manufactured by Sumitomo Metal Mining Co., Ltd., Cs ０．３３ WO ３ 25 parts by mass of a copolymer of 2,2'-dimethylaminopropanediol (20% by mass) and 10 parts by mass of a dispersant DISPERBYK-2012 (manufactured by BYK Japan, modified maleic anhydride-styrene copolymer, weight average molecular weight 3100, pH = 5.62, non-volatile content 40%) were melt-kneaded in an 18 mmφ twin-screw extruder (set temperature 250°C, mesh filter with a capture particle size of 20 μm). The obtained thermoplastic resin composition was pelletized to obtain a masterbatch (2).

[0078] <Spinning and Production of Knitted Fabric> Near-infrared absorbing multifilament fibers containing 1.0 wt % of CWO and a knitted fabric were produced in the same manner as in Example 1.

[0079] (Example 5) <Preparation of CWO Masterbatch> 91.7 parts by mass of polyamide 6 (1015B, manufactured by UBE) which is a thermoplastic resin, and a dispersant-treated cesium tungsten oxide aqueous dispersion (YMW-D20, manufactured by Sumitomo Metal Mining Co., Ltd.) were used. ０．３３ WO ３ 25 parts by mass of 1.0% by weight of CWO, and 3.3 parts by mass of a dispersant, DISPERBYK-2013 (manufactured by BYK Japan, modified maleic anhydride-styrene copolymer, weight average molecular weight 5200, pH 6.05, non-volatile content 100%), were melt-kneaded in an 18 mmφ twin-screw extruder (set temperature 250°C, mesh filter with a capture particle size of 20 μm). The obtained thermoplastic resin composition was pelletized to obtain a masterbatch (3). <Spinning and production of knitted fabric> Near-infrared absorbing multifilament fibers containing 1.0% by weight of CWO and knitted fabric were produced by the same method as in Example 1.

[0080] Example 6 Preparation of a CWO Masterbatch A CWO masterbatch was prepared by dispersing 90 parts by mass of a thermoplastic resin polylactic acid (TE-2000C, manufactured by Unitika Ltd.), a dispersant-treated cesium tungsten oxide aqueous dispersion (YMW-D20, Cs, manufactured by Sumitomo Metal Mining Co., Ltd.), and a tungsten oxide aqueous dispersion (YMW-D20, Cs, manufactured by Sumitomo Metal Mining Co., Ltd.). ０．３３ WO ３ 25 parts by mass of the hydroxybenzoate (20% by mass) and 5 parts by mass of a dispersant DISPERBYK-2013 (manufactured by BYK Japan, modified maleic anhydride-styrene copolymer, weight average molecular weight 5200, pH 6.05, non-volatile content 100%) were melt-kneaded in an 18 mmφ twin-screw extruder (set temperature 200°C, mesh filter with a capture particle size of 20 μm). The obtained thermoplastic resin composition was pelletized to obtain a masterbatch (4).

[0081] <Spinning and Production of Knitted Fabric> Near-infrared absorbing multifilament fibers containing 1.0 wt % of CWO and a knitted fabric were produced in the same manner as in Example 1.

[0082] (Example 7) <Preparation of CWO Masterbatch> 91.7 parts by mass of polyamide 11 (manufactured by ARKEMA, Rilsan (registered trademark), BMNO) which is a thermoplastic resin, cesium tungsten oxide aqueous dispersion treated with a dispersant (manufactured by Sumitomo Metal Mining Co., Ltd., YMW-D20, Cs ０．３３ WO３ 25 parts by mass of the hydroxybenzoate (20% by mass) and 3.3 parts by mass of a dispersant DISPERBYK-2013 (manufactured by BYK Japan, modified maleic anhydride-styrene copolymer, weight average molecular weight 5200, pH 6.05, non-volatile content 100%) were melt-kneaded in an 18 mmφ twin-screw extruder (set temperature 230°C, mesh filter with a capture particle size of 20 μm). The obtained thermoplastic resin composition was pelletized to obtain a masterbatch (5).

[0083] <Spinning and Production of Knitted Fabric> Near-infrared absorbing multifilament fibers containing 1.0 wt % of CWO and a knitted fabric were produced in the same manner as in Example 1.

[0084] (Example 8) <Preparation of CWO Masterbatch> 91.7 parts by mass of polyamide 6 (1015B, manufactured by UBE) which is a thermoplastic resin, and a dispersant-treated cesium tungsten oxide aqueous dispersion (YMW-D20, Cs, manufactured by Sumitomo Metal Mining Co., Ltd.) were used. ０．３３ WO ３ 25 parts by mass of 1.0% by weight of CWO, and 8.3 parts by mass of dispersant DISPERBYK-190 (manufactured by BYK Japan, modified maleic anhydride-styrene copolymer, weight average molecular weight 3900, pH 5.58, non-volatile content 40%) were melt-kneaded in an 18 mmφ twin-screw extruder (set temperature 250°C, mesh filter with capture particle diameter of 20 μm). The obtained thermoplastic resin composition was pelletized to obtain masterbatch (6). <Spinning and production of knitted fabric> Near-infrared absorbing multifilament fibers containing 1.0% by weight of CWO and knitted fabric were produced by the same method as in Example 1.

[0085] (Example 9) <Preparation of ATO Masterbatch> 80 parts by mass of thermoplastic resin polyamide 11 (ARKEMA, Rilsan (registered trademark) BMNO), 16.7 parts by mass of dispersant-treated antimony tin oxide aqueous dispersion (Tokushiki, 9387SN, ATO 30% by mass), and 3.3 parts by mass of dispersant DISPERBYK-2013 (BYK Japan, modified maleic anhydride-styrene copolymer, weight average molecular weight 5200, pH 6.05, non-volatile content 100%) were melt-kneaded in an 18 mmφ twin-screw extruder (set temperature 280 ° C., mesh filter with a capture particle size of 20 μm). The obtained thermoplastic resin composition was pelletized to obtain a masterbatch (7).

[0086] <Spinning and Production of Knitted Fabric> Near-infrared absorbing multifilament fibers containing 1.0% by weight of ATO and a knitted fabric were produced in the same manner as in Example 1.

[0087] Comparative Example 3 Preparation of CWO Masterbatch A CWO masterbatch was prepared by mixing 95 parts by mass of polyethylene terephthalate (J125S, manufactured by Mitsui Chemicals, Inc., IV value 0.76) which is a thermoplastic resin, and cesium tungsten oxide aqueous dispersion (YMW-D20, manufactured by Sumitomo Metal Mining Co., Ltd.) which had been treated with a dispersant. ０．３３ WO ３ 25 parts by mass of the 20% (20% by mass) acrylic resin composition was melt-kneaded in an 18 mmφ twin-screw extruder (set temperature 280°C, mesh filter with a capture particle size of 20 μm). The resulting thermoplastic resin composition was pelletized to obtain masterbatch (8). The resulting masterbatch (8) was evaluated for its dispersion state and was found to be poor (×), so spinnability and knitted fabric were not evaluated.

[0088] Comparative Example 4 Preparation of CWO Masterbatch 91.7 parts by mass of polyethylene terephthalate (manufactured by Mitsui Chemicals, Inc., J125S, IV value 0.76), which is a thermoplastic resin, and a dispersant-treated cesium tungsten oxide aqueous dispersion (manufactured by Sumitomo Metal Mining Co., Ltd., YMW-D20, Cs ０．３３ WO ３25 parts by mass of the hydroxybenzoate (20% by mass) and 3.3 parts by mass of a dispersant DISPERBYK-102 (manufactured by BYK Japan, phosphate ester, weight average molecular weight 2200, pH 1.53, non-volatile content 100%) were melt-kneaded in an 18 mmφ twin-screw extruder (set temperature 280°C, mesh filter with a capture particle size of 20 μm). The obtained thermoplastic resin composition was pelletized to obtain a masterbatch (9).

[0089] <Spinning, Fabric Preparation, and Spectroscopic Property Evaluation> In the same manner as in Example 1, an infrared absorbing multifilament fiber containing 1.0 wt % of CWO and a knitted fabric were produced.

[0090] Comparative Example 5 Preparation of CWO Masterbatch A CWO masterbatch was prepared by dispersing 90 parts by mass of polyethylene terephthalate (J125S, manufactured by Mitsui Chemicals, Inc., IV value 0.76) which is a thermoplastic resin, cesium tungsten oxide aqueous dispersion (YMW-D20, manufactured by Sumitomo Metal Mining Co., Ltd., Cs ０．３３ WO ３ 25 parts by mass of a copolymer of 20% by mass of PEG-1000 (20% by mass) and 5 parts by mass of a dispersant SY GLYSTER CRS-75 (manufactured by Sakamoto Pharmaceutical Co., Ltd., polyglycerol fatty acid ester, weight average molecular weight 5900, pH 9.28, non-volatile content 100%) were melt-kneaded in an 18 mmφ twin-screw extruder (set temperature 280°C, mesh filter with a capture particle size of 20 μm). The obtained thermoplastic resin composition was pelletized to obtain masterbatch (10). The obtained masterbatch (10) was evaluated for dispersion state and was found to be poor (×), so spinnability and knitted fabric evaluation were not performed.

[0091] Comparative Example 6 Preparation of CWO Masterbatch 91.7 parts by mass of polyamide 6 (1015B, manufactured by UBE) which is a thermoplastic resin, and a dispersant-treated cesium tungsten oxide aqueous dispersion (YMW-D20, manufactured by Sumitomo Metal Mining Co., Ltd.) were used. ０．３３ WO ３25 parts by mass of 20% by mass of PEG-140 (20% by mass) and 3.3 parts by mass of dispersant DISPERBYK-185 (manufactured by BYK Japan, modified polyurethane, pH 8.58, non-volatile content over 90%) were melt-kneaded in an 18 mmφ twin-screw extruder (set temperature 280°C, mesh filter with a capture particle size of 20 μm). The obtained thermoplastic resin composition was pelletized to obtain masterbatch (11). The obtained masterbatch (11) was evaluated for its dispersion state and was given an "X" rating, so spinnability and knitted fabric evaluation were not performed.

[0092] Comparative Example 7 Preparation of CWO Masterbatch 91.7 parts by mass of polyamide 6 (1015B, manufactured by UBE) which is a thermoplastic resin, and a dispersant-treated cesium tungsten oxide aqueous dispersion (YMW-D20, manufactured by Sumitomo Metal Mining Co., Ltd.) were used. ０．３３ WO ３ 25 parts by mass of a cellulose acetate copolymer (20% by mass) and 3.3 parts by mass of a dispersant DISPERBYK-2055 (manufactured by BYK Japan, modified acrylate, pH = 9.95, non-volatile content 100%) were melt-kneaded in an 18 mmφ twin-screw extruder (set temperature 280°C, mesh filter with a capture particle size of 20 μm). The obtained thermoplastic resin composition was pelletized to obtain masterbatch (12). The obtained masterbatch (12) was evaluated for dispersion state and was found to be poor (×), so spinnability and knitted fabric evaluation were not performed.

[0093] Comparative Example 8 Preparation of CWO Masterbatch 91.7 parts by mass of polyamide 6 (1015B, manufactured by UBE) which is a thermoplastic resin, and a dispersant-treated cesium tungsten oxide aqueous dispersion (YMW-D20, manufactured by Sumitomo Metal Mining Co., Ltd.) were used. ０．３３ WO ３25 parts by mass of a cellulose acetate copolymer (20% by mass) and 3.3 parts by mass of a dispersant, Admer (registered trademark) QE-800 (manufactured by Mitsui Chemicals, Inc., maleic anhydride-modified polyolefin, non-volatile content 100%), were melt-kneaded in an 18 mmφ twin-screw extruder (set temperature 250°C, mesh filter with a capture particle diameter of 20 μm). The obtained thermoplastic resin composition was pelletized to obtain masterbatch (13). The obtained masterbatch (13) was evaluated for dispersion state and was found to be poor (×), so spinnability and knitted fabric evaluation were not performed.

[0094] Comparative Example 9 <Preparation of CWO Masterbatch> 56 parts by mass of a thermoplastic resin polyamide 6 (1015B, manufactured by UBE Co., Ltd.), a dispersant-treated cesium tungsten oxide aqueous dispersion (YMW-D20, Cs, manufactured by Sumitomo Metal Mining Co., Ltd.), and a tungsten oxide aqueous dispersion (YMW-D20, Cs, manufactured by Sumitomo Metal Mining Co., Ltd.) were mixed. ０．３３ WO ３ 25 parts by mass of a cellulose acetate copolymer (20% by mass) and 39 parts by mass of a dispersant, Admer (registered trademark) QE-800 (manufactured by Mitsui Chemicals, Inc., maleic anhydride-modified polyolein, non-volatile content 100%), were melt-kneaded in an 18 mmφ twin-screw extruder (set temperature 250°C, mesh filter with a capture particle diameter of 20 μm). The obtained thermoplastic resin composition was pelletized to obtain masterbatch (14). The obtained masterbatch (14) was evaluated for dispersion state and was found to be poor (×), so spinnability and knitted fabric evaluation were not performed.

[0095] (Reference Example 2) <Spinning> Using a multifilament melt spinning apparatus, a thermoplastic resin polyethylene terephthalate (Mitsui Chemicals, Inc., J125S, IV value 0.76) was used as a spinning raw material, and spinning was carried out for 1 hour at a spinning temperature of 280°C, an extrusion rate of 1 kg / h, and a take-up speed of 1000 m / min, to obtain a 150 denier 24 filament multifilament fiber.

[0096] <Production of knitted fabric> The above multifilament fibers were used to knit a knitted fabric with a gauge of 30 and a basis weight of 110 g / m using a cylindrical knitting machine. ２ A knitted fabric was produced.

[0097] <Evaluation> [Dispersion State] The thermoplastic resin compositions obtained in the Examples and Comparative Examples were sandwiched between two glass slides using a hot plate to produce a film with a thickness of 100 μm or less. Using an optical microscope (Nikon Solutions, ECLIPSE LV100 model) in a transmission mode, the number of near-infrared absorbing metal oxide particles exceeding a predetermined particle size in the film was counted. At an observation magnification of 200, if the number of particles exceeding 2 μm in a square 200 μm field of view was 10 or less, it was evaluated as very good (◎); if it was more than 10 and 50 or less, it was evaluated as good (◯); and if it was more than 50, it was evaluated as poor (×). [Evaluation Criteria] If the number of particles exceeding 2 μm was 10 or less... very good (◎); if the number of particles exceeding 2 μm was more than 10 and 50 or less... good (◯); if the number of particles exceeding 2 μm was more than 50... poor (×).

[0098] [Haze Measurement (2)] A 10% by mass aqueous solution of the modified maleic anhydride-styrene copolymer (A) used in the Examples and Comparative Examples was prepared, and the haze of the aqueous solution was measured using a haze meter (manufactured by Nippon Denshoku Industries Co., Ltd., NDH70002II type) in accordance with JIS K7361. In addition, the solubility of each dispersant in water was confirmed visually. The results are shown in Table 2.

[0099]

[0100] <Spinnability> The master batches obtained in the examples and comparative examples were mixed with a natural resin to which no oxide particles had been added at a predetermined ratio to obtain a compound containing 1% by mass of oxide particles. The obtained compound was melt-spun and then drawn to obtain fibers. If the dispersibility was poor, the material would be trapped by the nozzle mesh, the monitored pressure would increase, and thread breakage would occur. A case in which there was no thread breakage in one hour and the monitored pressure increase rate was 5% or less was evaluated as very good (◎); a case in which there was no thread breakage in one hour and the monitored pressure increase rate was more than 5% but not more than 15% was evaluated as good (◯); and a case in which there was thread breakage or there was no thread breakage and the monitored pressure increase rate was more than 15% was evaluated as poor (×). [Evaluation criteria] No thread breakage and monitored pressure increase rate of 5% or less: very good (◎); no thread breakage and monitored pressure increase rate of more than 5% but not more than 15%: good (◯); and a case in which there was thread breakage or there was no thread breakage and the monitored pressure increase rate was more than 15%: poor (×).

[0101] <IV Value Measurement> The IV value (intrinsic viscosity) of each sample was measured in accordance with JIS K7390 for masterbatches containing polyethylene terephthalate, a thermoplastic resin, in the examples and comparative examples. A low IV value can cause problems such as difficulty in molding and deterioration of the physical properties of molded products. An IV retention of 80% or more was evaluated as very good (◎), an IV retention of 70% or more but less than 80% was evaluated as good (◯), and an IV retention of less than 70% was evaluated as poor (×). The retention was calculated according to formula (1). IV retention (%) = Measured IV value of each sample / IV value of polyethylene terephthalate × 100% ... formula (1) [Evaluation criteria] IV retention of 80% or more: very good (◎) IV retention of 70% or more but less than 80%: good (◯) IV retention of less than 70%: poor (×)

[0102] <Measurement of near-infrared transmittance> The knitted fabrics obtained in the examples and comparative examples were measured for transmittance of light with wavelengths of 1000 nm to 2000 nm in the near-infrared region using an ultraviolet-visible-near-infrared spectrophotometer (manufactured by JASCO Corporation, V-770 model), and the average value was calculated.

[0103] The evaluation results of the above Examples and Comparative Examples are shown in Table 3.

[0104]

[0105] From the results in Table 2 above, in Examples 3 to 9, the blending amount of the modified maleic anhydride-styrene copolymer (A) per 100 parts by mass of the near-infrared absorbing metal oxide particles (B) was in the range of 20 to 150 parts by mass, and the number of near-infrared absorbing metal oxide particles (B) exceeding 2 μm within a square 200 μm field of view observed with an electron microscope was 50 or less, indicating excellent dispersibility of the near-infrared absorbing metal oxide particles (B) in the thermoplastic resin composition and excellent spinnability. Furthermore, in Examples 3 to 8, in which CWO particles were used as the near-infrared absorbing metal oxide particles (B), the near-infrared transmittance was 12.4% to 28.5%, indicating excellent near-infrared absorbency of the knitted fabric.

[0106] Fig. 1 shows an optical microscope image of the thermoplastic resin composition obtained in Example 3 when the dispersion state was evaluated. As shown in Fig. 1, in the thermoplastic resin composition obtained in Example 3, only a few particles of near-infrared absorbing metal oxide particles (B) exceeding 2 µm in size were observed within a square 200 µm field of view.

[0107] Furthermore, it was found that the near-infrared transmittance of the knitted fabrics obtained in Examples 3 and 4 was lower than that of Comparative Example 4, in which a phosphate ester was used as a dispersant. This is presumably due to the excellent dispersibility of the near-infrared absorbing metal oxide particles (B) in the fibers.

[0108] On the other hand, in Comparative Example 3, the modified maleic anhydride-styrene copolymer (A) was not contained in the thermoplastic resin composition, and the dispersibility of the near-infrared absorbing metal oxide particles (B) was poor. An optical microscope image of the thermoplastic resin composition obtained in Comparative Example 3, when the dispersion state was evaluated, is shown in Figure 2. As shown in Figure 2, in the thermoplastic resin composition obtained in Comparative Example 3, many particles of near-infrared absorbing metal oxide particles (B) exceeding 2 µm were confirmed within the same field of view.

[0109] In Comparative Examples 5 to 9, a dispersant other than the modified maleic anhydride-styrene copolymer (A) was contained in the thermoplastic resin composition, and the dispersibility of the near-infrared absorbing metal oxide particles (B) in the thermoplastic resin composition was poor. In Comparative Example 4, a phosphate ester was contained in the thermoplastic resin composition as a dispersant, and the IV retention rate was poorer than in Examples 3 and 4. This is presumably because the pH of the phosphate ester was 1.53, which was lower than 5, and thus hydrolysis was promoted in the thermoplastic resin composition, resulting in a decrease in viscosity.

Claims

1. A thermoplastic resin composition comprising a modified maleic anhydride-styrene copolymer (A), near-infrared absorbing metal oxide particles (B), and a thermoplastic resin (C), wherein the amount of the modified maleic anhydride-styrene copolymer (A) blended per 100 parts by mass of the near-infrared absorbing metal oxide particles (B) is 20 to 150 parts by mass, and the number of near-infrared absorbing metal oxide particles (B) exceeding 2 μm is 50 or less within a square 200 μm visual field observed under a microscope.

2. The thermoplastic resin composition according to claim 1, wherein the weight-average molecular weight of the modified maleic anhydride-styrene copolymer (A) is 1,000 to 20,000.

3. The thermoplastic resin composition according to claim 1, wherein the near-infrared absorbing metal oxide particles (B) are surface-modified with a dispersant (b) having a polar group, and at least a portion of the modified maleic anhydride-styrene copolymer (A) is bonded to the near-infrared absorbing metal oxide particles (B) via the dispersant (b).

4. The thermoplastic resin composition according to claim 1, wherein the near-infrared absorbing metal oxide particles (B) are one or more selected from the group consisting of cesium tungsten oxide, indium tin oxide, and antimony tin oxide.

5. The thermoplastic resin composition according to claim 1, wherein the thermoplastic resin (C) is one or more resins selected from the group consisting of polyester resins, polyamide resins, and polyurethane resins.

6. A molded article which is a melt-molded product of the thermoplastic resin composition according to claim 1 or 2.

7. A method for producing a thermoplastic resin composition, comprising the steps of mixing a modified maleic anhydride-styrene copolymer (A), near-infrared absorbing metal oxide particles (B), and a thermoplastic resin (C), and melt-kneading the mixture at a temperature equal to or higher than the melting point of the thermoplastic resin (C), wherein the amount of the modified maleic anhydride-styrene copolymer (A) per 100 parts by mass of the near-infrared absorbing metal oxide particles (B) is 20 to 150 parts by mass, and the number of near-infrared absorbing metal oxide particles (B) exceeding 2 μm is 50 or less within a square 200 μm field of view observed under a microscope.

8. A method for producing a thermoplastic resin composition according to claim 7, comprising the step of preparing an aqueous dispersion of the near-infrared absorbing metal oxide particles (B), and mixing the modified maleic anhydride-styrene copolymer (A), the aqueous dispersion of the near-infrared absorbing metal oxide particles (B), and a thermoplastic resin (C).

9. The method for producing a thermoplastic resin composition according to claim 7, wherein the weight average molecular weight of the modified maleic anhydride-styrene copolymer (A) is 1,000 to 20,000.

10. The method for producing a thermoplastic resin composition according to claim 7, wherein the modified maleic anhydride-styrene copolymer (A) has a pH of 5 to 9 when made into a 10% by mass aqueous solution.

11. The method for producing a thermoplastic resin composition according to claim 7, wherein the near-infrared absorbing metal oxide particles (B) are surface-modified with a dispersant (b) having a polar group, and at least a portion of the modified maleic anhydride-styrene copolymer (A) is bonded to the near-infrared absorbing metal oxide particles (B) via the dispersant (b).

12. The method for producing a thermoplastic resin composition according to claim 7, wherein the near-infrared absorbing metal oxide particles (B) are one or more selected from the group consisting of cesium tungsten oxide, indium tin oxide, and antimony tin oxide.

13. The method for producing a thermoplastic resin composition according to claim 7, wherein the thermoplastic resin (C) is one or more types selected from the group consisting of polyester-based resins, polyamide-based resins, and polyurethane-based resins.

14. A method for producing a molded article, comprising the step of melt-molding the thermoplastic resin composition obtained by the method of claim 7.

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