Resin composition and molded article

Abstract

To provide a resin composition having excellent light resistance and weather resistance, and a molding formed from the resin composition.SOLUTION: A resin composition comprises a polyester resin, an ultraviolet absorber, and a release agent with a melting point of 90-150°C, the ultraviolet absorber comprising a structure represented by the formula (1), and with a molecular weight of 600 or less.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to resin compositions and molded articles, and more particularly to resin compositions comprising polyester resin. [Background technology]

[0002] Conventionally, resin compositions using polyester resins that offer excellent light resistance and weather resistance have been investigated. For example, Patent Document 1 discloses a light-resistant thermoplastic resin composition comprising a thermoplastic resin (A) consisting of 5 to 100% by mass of polyester resin (A1) and 0 to 95% by mass of a thermoplastic resin other than polyester resin (A2), an ultraviolet absorber (B), and an NR-type or N-CH3-type hindered amine-based light stabilizer (C), wherein the content of the ultraviolet absorber (B) is 0.1 to 1.5 parts by mass and the content of the hindered amine-based light stabilizer (C) is 0.1 to 1.5 parts by mass per 100 parts by mass of the thermoplastic resin (A). Furthermore, Patent Document 2 describes a thermoplastic polyester resin and a xenon arc weatherometer operating according to SAE J1885 that measured 601.6 kJ / m³ 2 Disclosed is a UV-stabilized molding composition comprising a UV-stabilizing system combined with a polyester resin, which, when exposed to irradiation, achieves a color difference of less than approximately 2.25 when calculated in CIELab units under the light source "D-65" according to ASTM standard D-2244, and which is sufficient to retain at least approximately 7.5% surface gloss after irradiation, wherein the UV-stabilizing system comprises: (i) a UV absorber; (ii) a hindered amine light stabilizer; and (iii) an antioxidant. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2020-152901 [Patent Document 2] Japanese Patent Application Publication No. 11-323100 [Overview of the project] [Problems that the invention aims to solve]

[0004] As mentioned above, resin compositions with excellent light resistance and weather resistance are being investigated, but further development of new materials is expected. The present invention aims to solve these problems and to provide a resin composition with excellent light resistance and weather resistance, and a molded article formed from the resin composition. [Means for solving the problem]

[0005] Based on the above-mentioned problems, the inventors conducted research and found that by adding a release agent with a melting point of 90 to 150°C to a polyester resin in addition to a predetermined ultraviolet absorber, a resin composition with outstanding light resistance and weather resistance can be obtained at a level that cannot be achieved by simply adding an ultraviolet absorber. Specifically, the above problem was solved by the following means. <1> A resin composition comprising a polyester resin, an ultraviolet absorber, and a mold release agent having a melting point of 90 to 150°C, wherein the ultraviolet absorber comprises a structure represented by the following formula (1) and has a molecular weight of 600 or less. Formula (1) [ka] <2> The polyester resin includes polybutylene terephthalate resin. <1> The resin composition described above. <3> Furthermore, it contains a light stabilizer, <1> or <2> The resin composition described above. <4> The aforementioned light stabilizer includes a hindered amine-based light stabilizer. <3> The resin composition described above. <5> The content of the mold release agent is 0.01 to 1.0 parts by mass per 100 parts by mass of polyester resin. <1> ~ <4> A resin composition as described in any one of the following. <6> For forming molded products for outdoor use, <1> ~ <5> A resin composition as described in any one of the following. <7> <1> ~ <6> A molded article formed from any one of the resin compositions described in that one. [Effects of the Invention]

[0006] The present invention makes it possible to provide a resin composition with excellent light resistance and weather resistance, and a molded article formed from the resin composition. [Modes for carrying out the invention]

[0007] The following describes in detail embodiments for carrying out the present invention (hereinafter simply referred to as "this embodiment"). Note that the following embodiment is illustrative for explaining the present invention, and the present invention is not limited to this embodiment. In this specification, "~" is used to mean that the numbers before and after it are included as the lower and upper limits, respectively. In this specification, all physical properties and characteristic values ​​shall be those at 23°C unless otherwise specified. In this specification, when groups (atomic groups) are not specified as substituted or unsubstituted, the notation includes both groups (atomic groups) with and without substituents. For example, "alkyl group" includes not only unsubstituted alkyl groups but also substituted alkyl groups. In this specification, when notation is not specified as substituted or unsubstituted, unsubstituted is preferred. If the measurement methods, etc., described in the standards shown herein differ from year to year, unless otherwise specified, the standards as of January 1, 2021 shall apply.

[0008] The resin composition of this embodiment comprises a polyester resin, an ultraviolet absorber, and a mold release agent having a melting point of 90 to 150°C, wherein the ultraviolet absorber comprises a structure represented by the following formula (1) and has a molecular weight of 600 or less. Formula (1) [ka] By adopting such a configuration, a resin composition excellent in light resistance and weather resistance can be obtained. In particular, the light resistance after being exposed to light irradiation at a high temperature for a long time is unexpectedly improved by the addition of a predetermined mold release agent. When forming a resin composition containing a polyester resin using a mold, it is common practice to incorporate a mold release agent to improve the mold release property from the mold. However, as a result of investigations by the present inventor, it was found that when a mold release agent having a low melting point is incorporated into a molded article used outdoors or the like, the mold release agent will seep into the surface of the molded article due to sunlight irradiation. Therefore, in the present embodiment, by using a mold release agent having a melting point of 90°C or higher, it has been successfully possible to effectively suppress the mold release agent from melting and seeping into the surface of the molded article. On the other hand, it was found that if the melting point of the mold release agent is too high, the mold release agent will not sufficiently fulfill its function as a mold release agent for the polyester resin. In the present embodiment, by using a mold release agent having a melting point of 150°C or lower, even when molding using a mold, the mold release agent can effectively exhibit its original mold release effect. Furthermore, in the present embodiment, surprisingly, by using a mold release agent having a predetermined melting point, the light resistance (Δ color difference) after being exposed to light irradiation at a high temperature for a long time could be reduced. This is presumably because in the case of a mold release agent having a specific melting point, the probability of the mold release agent being present on the surface of the molded body becomes high, which contributes to preventing discoloration. Also, it is presumed that the mold release agent on the surface is difficult to be removed and the effect continues for a long time.

[0009] <Polyester resin> The resin composition of the present embodiment contains a polyester resin. As the polyester resin, known thermoplastic polyester resins can be used, and polyethylene terephthalate resins and polybutylene terephthalate resins are preferable, and it is more preferable to contain at least polybutylene terephthalate resin. The polybutylene terephthalate resin used in the resin composition of this embodiment is a polyester resin having a structure in which terephthalic acid units and 1,4-butanediol units are ester-bonded. In addition to the polybutylene terephthalate resin (homopolymer), it includes polybutylene terephthalate copolymers containing other copolymerization components other than terephthalic acid units and 1,4-butanediol units, and mixtures of homopolymers and polybutylene terephthalate copolymers.

[0010] The polybutylene terephthalate resin may contain one or more dicarboxylic acid units other than terephthalic acid. Specific examples of other dicarboxylic acids include aromatic dicarboxylic acids such as isophthalic acid, orthophthalic acid, 1,5-naphthalenedicarboxylic acid, 2,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, biphenyl-2,2'-dicarboxylic acid, biphenyl-3,3'-dicarboxylic acid, biphenyl-4,4'-dicarboxylic acid, bis(4,4'-carboxyphenyl)methane, anthracenedicarboxylic acid, 4,4'-diphenyletherdicarboxylic acid, etc.; alicyclic dicarboxylic acids such as 1,4-cyclohexanedicarboxylic acid, 4,4'-dicyclohexyldicarboxylic acid, etc.; and aliphatic dicarboxylic acids such as adipic acid, sebacic acid, azelaic acid, dimer acid, etc. The polybutylene terephthalate resin used in this embodiment preferably occupies 80 mol% or more of all dicarboxylic acid units with terephthalic acid units, and more preferably occupies 90 mol% or more.

[0011] As the diol unit, it may contain one or more other diol units in addition to 1,4-butanediol. Other specific examples of diol units include aliphatic or alicyclic diols with 2 to 20 carbon atoms, and bisphenol derivatives. Specific examples include ethylene glycol, propylene glycol, 1,5-pentanediol, 1,6-hexanediol, neopentyl glycol, decamethylene glycol, cyclohexanedimethylol, 4,4'-dicyclohexylhydroxymethane, 4,4'-dicyclohexylhydroxypropane, and ethylene oxide addition diols of bisphenol A. In addition to the bifunctional monomers mentioned above, small amounts of trifunctional monomers such as trimellitic acid, trimesic acid, pyromellitic acid, pentaerythritol, and trimethylolpropane can be used to introduce branched structures, and small amounts of monofunctional compounds such as fatty acids can be used to adjust molecular weight. In this embodiment, the polybutylene terephthalate resin preferably contains 1,4-butanediol units accounting for 80 mol% or more of the total diol units, and more preferably 90 mol% or more.

[0012] As described above, the polybutylene terephthalate resin is preferably a polybutylene terephthalate homopolymer obtained by polycondensation of terephthalic acid and 1,4-butanediol. Alternatively, it may be a polybutylene terephthalate copolymer containing one or more dicarboxylic acids other than terephthalic acid as the carboxylic acid unit and / or one or more diols other than 1,4-butanediol as the diol unit. When the polybutylene terephthalate resin is a polybutylene terephthalate resin modified by copolymerization, specific preferred copolymers include polyester ether resins copolymerized with polyalkylene glycols, particularly polytetramethylene glycol, dimer acid copolymerized polybutylene terephthalate resins, and isophthalic acid copolymerized polybutylene terephthalate resins. Among these, it is preferable to use a polyester ether resin copolymerized with polytetramethylene glycol. These copolymers refer to those with a copolymerization amount of 1 mol% or more and less than 50 mol% of the total segments of the polybutylene terephthalate resin. In particular, the copolymerization amount is preferably 2 mol% or more and less than 50 mol%, more preferably 3 to 40 mol%, and even more preferably 5 to 20 mol%. Such copolymerization ratios tend to improve fluidity, toughness, and tracking resistance, and are therefore preferable.

[0013] The amount of terminal carboxyl groups in polybutylene terephthalate resin can be appropriately selected and determined, but is usually 60 eq / ton or less, preferably 50 eq / ton or less, and more preferably 30 eq / ton or less. Keeping it below the above upper limit tends to improve alkali resistance and hydrolysis resistance. There is no specific lower limit for the amount of terminal carboxyl groups, but considering the productivity of polybutylene terephthalate resin production, it is usually 10 eq / ton or more.

[0014] The amount of terminal carboxyl groups in polybutylene terephthalate resin is measured by dissolving 0.5 g of polybutylene terephthalate resin in 25 mL of benzyl alcohol and titrating it with a 0.01 mol / L benzyl alcohol solution of sodium hydroxide. The amount of terminal carboxyl groups can be adjusted by any conventionally known method, such as adjusting polymerization conditions like the raw material ratio, polymerization temperature, and reduced pressure method during polymerization, or by reacting with a chelating agent.

[0015] The intrinsic viscosity of the polybutylene terephthalate resin is preferably 0.5 to 2 dL / g. From the viewpoint of moldability and mechanical properties, an intrinsic viscosity in the range of 0.6 to 1.5 dL / g is more preferable. Setting the intrinsic viscosity to 0.5 dL / g or higher tends to further improve the mechanical strength of the resulting resin composition. Conversely, setting it to 2 dL / g or lower tends to further improve the fluidity of the resin composition and thus improve moldability. The intrinsic viscosity of polybutylene terephthalate resin is measured at 30°C in a 1:1 (mass ratio) mixed solvent of tetrachloroethane and phenol. The intrinsic viscosity of the polybutylene terephthalate resin is preferably 0.5 to 2 dL / g. From the viewpoint of moldability and mechanical properties, an intrinsic viscosity in the range of 0.6 to 1.5 dL / g is more preferable. Setting the intrinsic viscosity to 0.5 dL / g or higher tends to further improve the mechanical strength of the resulting resin composition. Conversely, setting it to 2 dL / g or lower tends to further improve the fluidity of the resin composition and thus improve moldability. The intrinsic viscosity of polybutylene terephthalate resin is measured using an Ubbelohde viscometer at 30°C in a 1:1 (mass ratio) mixed solvent with tetrachloroethanephenol.

[0016] Polybutylene terephthalate resin can be produced by melt polymerization of a dicarboxylic acid component mainly composed of terephthalic acid or ester derivatives thereof, and a diol component mainly composed of 1,4-butanediol, in a batch or continuous manner. Furthermore, after producing a low molecular weight polybutylene terephthalate resin by melt polymerization, the degree of polymerization (or molecular weight) can be increased to a desired value by further solid-phase polymerization under a nitrogen atmosphere or reduced pressure. The polybutylene terephthalate resin is preferably obtained by a manufacturing method in which a dicarboxylic acid component mainly composed of terephthalic acid and a diol component mainly composed of 1,4-butanediol are continuously melt-polycondensed.

[0017] The catalyst used in carrying out the esterification reaction may be one of the conventionally known ones, such as titanium compounds, tin compounds, magnesium compounds, and calcium compounds. Among these, titanium compounds are particularly preferred. Specific examples of titanium compounds as esterification catalysts include titanium alcoholates such as tetramethyl titanate, tetraisopropyl titanate, and tetrabutyl titanate, and titanium phenolates such as tetraphenyl titanate.

[0018] The polyester resin content in the resin composition of this embodiment is preferably 70% by mass or more, more preferably 80% by mass or more, even more preferably 90% by mass or more, and even more preferably 95% by mass or more. Achieving a content above the lower limit tends to further improve chemical resistance. Furthermore, the polyester resin content is such that all components other than the specific mold release agent and specific ultraviolet absorber are polyester resin. The resin composition of this embodiment may contain only one type of polyester resin, or it may contain two or more types. When it contains two or more types, it is preferable that the total amount is within the above range.

[0019] <Release agents with a melting point of 90-150°C> The resin composition of this embodiment contains a release agent (hereinafter sometimes referred to as "specific release agent") having a melting point of 90 to 150°C. In this embodiment, the inclusion of the specific release agent effectively suppresses bleed-out and further improves light resistance.

[0020] The melting point of the specified release agent is preferably 95°C or higher, more preferably 100°C or higher, even more preferably 105°C or higher, even more preferably 110°C or higher, and even more preferably 120°C or higher. Setting it above the lower limit tends to further improve the suppression of release agent bleed-out on the surface of the molded product. Furthermore, the melting point of the specified release agent is preferably 148°C or lower, and more preferably 146°C or lower. Setting it below the upper limit tends to further improve molding stability as the release agent is more easily dissolved onto the surface of the molded product during molding. When the resin composition of this embodiment contains two or more specific release agents, it is preferable that the melting points of both agents are within the aforementioned melting point range. The melting point of the specific release agent used in this embodiment refers to the melting point determined by differential scanning calorimetry (DSC), and specifically refers to the peak temperature (°C) of the main melting peak. More precisely, it refers to the peak top temperature (°C) of the endothermic main peak detected when the temperature is raised from 30°C to the expected melting point + 40°C at a rate of 20°C / min.

[0021] Examples of specific release agents include higher fatty acid metal salts, aliphatic carboxylic acids, esters of aliphatic carboxylic acids and alcohols, aliphatic hydrocarbon compounds, polysiloxane-based silicone oils, and waxes, with waxes being preferred.

[0022] As a mold release agent, reference can be given to the description in paragraph 0023 of Japanese Patent Publication No. 2018-203964, the descriptions in paragraphs 0092 to 0106 of Japanese Patent Publication No. 2021-121685, and the descriptions in paragraphs 0047 to 0051 of Japanese Patent Publication No. 2020-172580, the contents of which are incorporated herein by reference.

[0023] The wax is preferably at least one of polyolefin wax, ketone wax, amide wax, ester wax, and paraffin wax, with polyolefin wax and / or amide wax being more preferred.

[0024] Examples of polyolefin waxes include low molecular weight polyethylene, low molecular weight polyethylene copolymers, or modified polyethylene waxes obtained by introducing polar groups through oxidative or acid modification. Furthermore, incorporating modified polyethylene wax, which has been introduced by oxidative or acid modification, in an amount of 1 to 10% by mass of the polyolefin wax can improve dispersibility in the polyamide resin and is therefore more preferable. An example of polyolefin wax is Mitsui High Wax 100P (product name), manufactured by Mitsui Chemicals, Inc.

[0025] Amide waxes are monoamides and / or bisamides of fatty acids. Examples of fatty acid monoamides include oleamide, erucamide, stearamide, palmitamide, and lauamide, while examples of fatty acid bisamides include methylenebisstearate, ethylenebisoleamide, and ethylenebislaurateamide.

[0026] The content of the specific release agent in the resin composition of this embodiment is preferably 0.01 parts by mass or more, more preferably 0.05 parts by mass or more, even more preferably 0.08 parts by mass or more, even more preferably 0.10 parts by mass or more, and even more preferably 0.15 parts by mass or more, per 100 parts by mass of polyester resin. Setting the content above the lower limit tends to further improve molding stability due to improved release properties. The upper limit of the content of the specific release agent is preferably 1.0 part by mass or less, more preferably 0.7 parts by mass or less, even more preferably 0.5 parts by mass or less, even more preferably 0.3 parts by mass or less, and even more preferably 0.25 parts by mass or less, per 100 parts by mass of polyester resin. Setting the content below the upper limit tends to further improve the gas suppression effect during injection molding. The resin composition of this embodiment may contain only one type of specific release agent, or it may contain two or more types. When it contains two or more types, it is preferable that the total amount is within the above range.

[0027] The resin composition of this embodiment may or may not contain a release agent having a melting point of less than 90°C. Preferably, the resin composition of this embodiment is substantially free of a release agent having a melting point of less than 90°C. Substantially free means that the content of a release agent having a melting point of less than 90°C is 10% by mass or less of the content of the specific release agent contained in the resin composition of this embodiment, preferably 5% by mass or less, more preferably 3% by mass or less, even more preferably 1% by mass or less, even more preferably 0.1% by mass or less, and even more preferably 0.01% by mass or less. The resin composition of this embodiment may or may not contain a release agent having a melting point above 150°C. Preferably, the resin composition of this embodiment is substantially free of a release agent having a melting point above 150°C. Substantially free means that the content of a release agent having a melting point above 150°C is 10% by mass or less of the content of the specific release agent contained in the resin composition of this embodiment, preferably 5% by mass or less, more preferably 3% by mass or less, even more preferably 1% by mass or less, even more preferably 0.1% by mass or less, and even more preferably 0.01% by mass or less.

[0028] <UV absorber> The resin composition of this embodiment contains an ultraviolet absorber. The ultraviolet absorber used in this embodiment contains a structure represented by the following formula (1) and has a molecular weight of 600 or less. Hereinafter, such an ultraviolet absorber may be referred to as a "specific ultraviolet absorber". Formula (1) [ka] In this embodiment, the inclusion of a specific ultraviolet absorber enhances the lightfastness and weather resistance of the resin composition and molded product. In particular, it effectively reduces the color difference after weather resistance testing of the resin composition and molded product.

[0029] The molecular weight of the specified ultraviolet absorber is 600 or less. By using an ultraviolet absorber with a molecular weight of 600 or less, segregation occurs on the surface of the molded product, further improving its ultraviolet absorption. The molecular weight of the specified ultraviolet absorber is preferably 550 or less, more preferably 500 or less, even more preferably 450 or less, even more preferably 400 or less, and even more preferably 350 or less. The lower limit of the molecular weight of the specified ultraviolet absorber is preferably 200 or more.

[0030] The aforementioned specific ultraviolet absorber is preferably an ultraviolet absorber represented by the following formula (UV). Formula (UV) [ka] (In formula (UV), R 1 R is an alkyl group having 4 to 20 carbon atoms. 2 (This is a hydrogen atom or an organic group.) R 1 The alkyl group is a linear, branched, or cyclic alkyl group, with linear or branched alkyl groups being preferred, and branched alkyl groups being more preferred. R 1 The number of carbon atoms is preferably 5 or more, more preferably 6 or more, more preferably 7 or more, more preferably 18 or less, more preferably 16 or less, even more preferably 14 or less, even more preferably 12 or less, even more preferably 10 or less, and even more preferably 8. R 1 The alkyl group is particularly preferably a tert-octyl group. R 2 It is preferably an organic group containing a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, or a benzotriazole ring, more preferably a hydrogen atom or a methyl group, and even more preferably a hydrogen atom.

[0031] The content of the specific ultraviolet absorber in the resin composition of this embodiment is preferably 0.01 parts by mass or more, more preferably 0.05 parts by mass or more, even more preferably 0.08 parts by mass or more, even more preferably 0.10 parts by mass or more, and even more preferably 0.15 parts by mass or more, per 100 parts by mass of polyester resin. Setting the content above the lower limit tends to further improve the stabilization effect of color difference due to ultraviolet absorption. Furthermore, the upper limit of the content of the ultraviolet absorber is preferably 1.0 part by mass or less, more preferably 0.7 parts by mass or less, even more preferably 0.5 parts by mass or less, even more preferably 0.3 parts by mass or less, and even more preferably 0.25 parts by mass or less, per 100 parts by mass of polyester resin. Setting the content below the upper limit tends to further improve the gas suppression effect during injection molding. The resin composition of this embodiment may contain only one type of specific ultraviolet absorber, or it may contain two or more types. When it contains two or more types, it is preferable that the total amount is within the above range.

[0032] The resin composition of this embodiment may or may not contain ultraviolet absorbers other than the specified ultraviolet absorber. Preferably, the resin composition of this embodiment is substantially free of ultraviolet absorbers other than the specified ultraviolet absorber. Substantially free means that the content of ultraviolet absorbers other than the specified ultraviolet absorber is 10% by mass or less of the content of the specified ultraviolet absorber contained in the resin composition of this embodiment, preferably 5% by mass or less, more preferably 3% by mass or less, even more preferably 1% by mass or less, even more preferably 0.1% by mass or less, and even more preferably 0.01% by mass or less.

[0033] In the resin composition of this embodiment, the mass ratio of the specific ultraviolet absorber to the specific mold release agent is preferably 0.1 or more, more preferably 0.5 or more, even more preferably 0.7 or more, even more preferably 0.8 or more, and also preferably 2.0 or less, more preferably 1.5 or less, even more preferably 1.3 or less, and even more preferably 1.2 or less. By using such a ratio, the effects of the present invention tend to be exhibited more effectively.

[0034] <Light stabilizer> The resin composition of this embodiment preferably contains a light stabilizer. The inclusion of a light stabilizer tends to further improve long-term light resistance and weather resistance. In particular, the light stabilizer scavenges radicals, contributing to light resistance and weather resistance. Examples of light stabilizers include hindered phenol-based light stabilizers and hindered amine-based light stabilizers. Among these, hindered amine-based compounds are preferred.

[0035] The hindered amine-based light stabilizer used in this embodiment may be any of the NH type, N-Me type, or N-OR type shown below, but the NH type is preferred. Hindered amine-based light stabilizers preferably contain 1 to 5 of one or more of the following structures in a single molecule, more preferably 1 to 4, even more preferably 1 to 3, and even more preferably 2. [ka] Here, R is an organic group. x is an alkyl group having 1 to 5 carbon atoms, preferably a methyl group; m is an integer from 0 to 4, preferably 0 or 1, and more preferably 0; and * is the bonding position with other sites. R is preferably an organic group having 1 to 10 carbon atoms, and more preferably a methyl group.

[0036] The hindered amine light stabilizer used in this embodiment preferably has the following structure A. In this embodiment, a hindered amine light stabilizer having 1 to 3 of the following structure A in one molecule is particularly preferred, and a hindered amine light stabilizer having 2 of the following structure A is more preferred. Structure A [ka] (In structure A above, * indicates the location of connection with other parts.)

[0037] The molecular weight of the hindered amine-based light stabilizer used in this embodiment is preferably 200 or more, more preferably 300 or more, even more preferably 400 or more, and even more preferably 450 or more. Setting it above the lower limit tends to further improve the gas suppression effect during injection molding. Furthermore, the molecular weight of the hindered amine-based light stabilizer is preferably 5000 or less, more preferably 1000 or less, even more preferably 800 or less, even more preferably 700 or less, and even more preferably 600 or less. Setting it below the upper limit tends to further improve the effect of capturing radicals generated during resin decomposition due to ultraviolet absorption, as it is more likely to segregate on the surface of the molded product.

[0038] Specific examples of hindered amine light stabilizers include ADEKA's ADEKA Stab LA-52, LA-57, LA-63P, LA-68, LA-72, LA-77Y, LA-77G, LA-81, LA-82, LA-87, LA-402AF, LA-40MP, LA-40Si, and CSC's Chimassorb119, Tinuvin622, Tinuvin123, Tinuvin770DF, etc.

[0039] In addition to the above, the descriptions in paragraphs 0046-0057 of Japanese Patent Publication No. 2018-070722, paragraphs 0030-0037 of Japanese Patent Publication No. 2019-056035, and paragraphs 0066-0078 of International Publication No. 2017 / 038949 can also be considered as light stabilizers, and these contents are incorporated herein by reference.

[0040] If the resin composition of this embodiment contains a light stabilizer, its content is preferably 0.001 parts by mass or more, more preferably 0.005 parts by mass or more, even more preferably 0.01 parts by mass or more, even more preferably 0.05 parts by mass or more, and even more preferably 0.08 parts by mass or more, per 100 parts by mass of polyester resin. Setting the content above the lower limit tends to further improve the color difference stabilization effect of the light stabilizer. Furthermore, the upper limit of the light stabilizer content is preferably 5.0 parts by mass or less, more preferably 2.0 parts by mass or less, even more preferably 1.0 part by mass or less, even more preferably 0.5 parts by mass or less, and even more preferably 0.2 parts by mass or less, per 100 parts by mass of polyester resin. Setting the content below the upper limit tends to further improve the gas suppression effect during injection molding. The resin composition of this embodiment may contain only one type of light stabilizer, or it may contain two or more types. When it contains two or more types, it is preferable that the total amount is within the above range.

[0041] In the resin composition of this embodiment, the mass ratio of the specific ultraviolet absorber to the light stabilizer is preferably 0.1 or more, more preferably 0.3 or more, even more preferably 0.4 or more, and also preferably 1.0 or less, more preferably 0.7 or less, and even more preferably 0.6 or less, with respect to 1 part of the specific ultraviolet absorber. By using such a ratio, the effects of the present invention tend to be exhibited more effectively.

[0042] <Heat stabilizer> The resin composition of this embodiment may also contain a heat stabilizer. Examples of heat stabilizers include phenolic compounds, amine compounds, phosphorus compounds, and sulfur compounds, with sulfur compounds being preferred. For specific examples of heat stabilizers, refer to paragraphs 0046-0057 of Japanese Patent Publication No. 2018-070722, paragraphs 0030-0037 of Japanese Patent Publication No. 2019-056035, and paragraphs 0066-0078 of International Publication No. 2017 / 038949, the contents of which are incorporated herein by reference.

[0043] If the resin composition of this embodiment contains a heat stabilizer, its content is preferably 0.01 parts by mass or more, more preferably 0.05 parts by mass or more, even more preferably 0.08 parts by mass or more, even more preferably 0.10 parts by mass or more, and even more preferably 0.15 parts by mass or more, per 100 parts by mass of polyester resin. Setting the content above the lower limit tends to further improve the effect of maintaining material properties in heat resistance tests. Furthermore, the upper limit of the heat stabilizer content is preferably 1.0 part by mass or less, more preferably 0.7 parts by mass or less, even more preferably 0.5 parts by mass or less, even more preferably 0.3 parts by mass or less, and even more preferably 0.25 parts by mass or less, per 100 parts by mass of polyester resin. Setting the content below the upper limit tends to more effectively maintain the material properties inherent in the composition. The resin composition of this embodiment may contain only one type of heat stabilizer, or it may contain two or more types. When it contains two or more types, it is preferable that the total amount is within the above range.

[0044] In the resin composition of this embodiment, the mass ratio of the specific ultraviolet absorber to the heat stabilizer is preferably 0.1 or more, more preferably 0.5 or more, even more preferably 0.7 or more, even more preferably 0.8 or more, and also preferably 2.0 or less, more preferably 1.5 or less, even more preferably 1.3 or less, and even more preferably 1.2 or less. By using such a ratio, the effects of the present invention tend to be exhibited more effectively.

[0045] <Other ingredients> The resin composition of this embodiment may contain other components as needed, as long as they do not significantly impair the desired physical properties. Examples of other components include various resin additives. The other components may be present individually, or two or more in any combination and ratio. Specifically, these include nucleating agents, pigments, dyes, flame retardants, flame retardant additives, fillers, antistatic agents, antifogging agents, antiblocking agents, flow improvers, plasticizers, dispersants, and antibacterial agents. The resin composition of this embodiment comprises a polyester resin, a specific ultraviolet absorber, a specific mold release agent, and other components added as needed, with a total content of 100% by mass. Furthermore, in the resin composition of this embodiment, the total of the polyester resin, specific ultraviolet absorber, and specific release agent preferably accounts for 94% by mass or more, more preferably 96% by mass or more, and even more preferably 98% by mass or more. Furthermore, in the resin composition of this embodiment, the total of the polyester resin, specific ultraviolet absorber, specific mold release agent, light stabilizer (preferably a hindered amine-based light stabilizer), and heat stabilizer preferably accounts for 95% by mass or more, more preferably 97% by mass or more, and even more preferably 98% by mass or more.

[0046] <Method for producing resin compositions> The resin composition of this embodiment can be manufactured by conventional methods for preparing resin compositions. Typically, each component and various additives, which may be added as desired, are thoroughly mixed together and then melt-kneaded in a single-screw or twin-screw extruder. Alternatively, the resin composition of this embodiment can be prepared by melt-kneading the components without pre-mixing them, or by pre-mixing only some of them, and supplying them to the extruder using a feeder. Some components, such as dyes, may be melt-kneaded with a thermoplastic resin to prepare a masterbatch, and then the remaining components may be added to this and melt-kneaded. Furthermore, when using inorganic fillers, it is also preferable to supply them from a side feeder located midway through the extruder cylinder. The heating temperature during melt kneading can usually be appropriately selected from the range of 220 to 300°C. If the temperature is too high, decomposition gas is likely to be generated, which may cause opacity. Therefore, it is desirable to select a screw configuration considering shear heating, etc. To suppress decomposition during kneading and during the subsequent molding process, it is desirable to use an antioxidant or a heat stabilizer.

[0047] <Physical properties of the resin composition> The resin composition of this embodiment preferably has excellent light resistance. Specifically, the resin composition of this embodiment is formed into a test piece with a length of 60 mm, a width of 60 mm, and a thickness of 1.5 mm, and at 120°C and an integrated illuminance of 51 KJ / m 2 (Based on a wavelength of 275 nm), when subjected to a 600-hour test treatment, the difference in the color difference Δb value before and after (Δb value = b value after treatment - b value before treatment) is preferably less than 20, and more preferably less than 15. Although the ideal lower limit value of the difference in the Δb value is 0, 0.1 or more is practical. The resin composition of this embodiment also preferably has excellent weather resistance. Specifically, the resin composition of this embodiment is formed into a test piece with a length of 60 mm, a width of 60 mm, and a thickness of 1.5 mm, and when subjected to a 400-hour test treatment according to the weather resistance test standard SAE J1960, the difference in the color difference Δb value before and after (Δb value = b value after treatment - b value before treatment) is preferably less than 4. Although the ideal lower limit value of the difference in the Δb value is 0, 0.1 or more is practical.

[0048] <Method for manufacturing a molded product> The resin composition of this embodiment is molded according to a known method. The method for manufacturing a molded product is not particularly limited, and any molding method generally adopted for resin compositions can be arbitrarily adopted. Examples include injection molding method, ultra-high-speed injection molding method, injection compression molding method, two-color molding method, hollow molding methods such as gas assist, molding method using a heat-insulating mold, molding method using a rapid heating mold, foam molding (including supercritical fluid), insert molding, IMC (in-mold coating molding) molding method, extrusion molding method, sheet molding method, thermoforming method, rotational molding method, lamination molding method, press molding method, blow molding method, etc. Among them, the injection molding method is preferred. Details of the injection molding method can be found in paragraphs 0113 to 0116 of Japanese Patent No. 6183822, and these contents are incorporated herein by reference. Furthermore, the mold temperature during injection molding or other mold molding processes is preferably 70 to 90°C. In particular, it is preferable to mold at a mold temperature 70 to 30°C lower than the melting point of the specific release agent.

[0049] <Application> The resin composition of this embodiment is used as a molded article formed from the resin composition. The applications of the resin composition or molded article are not particularly limited, but are preferably used in electrical and electronic equipment / components, office automation equipment / components, information terminal equipment / components, machine parts, home appliances, vehicle parts (automobile interior and exterior), building materials, various containers, leisure goods and miscellaneous goods, lighting equipment, etc. In particular, the resin composition or molded article of this embodiment is suitable for use outdoors. Examples of outdoor applications include delivery boxes, mailboxes, automobile exterior parts, surveillance camera housings, and exterior parts for flying objects such as drones. [Examples]

[0050] The present invention will be described in more detail below with reference to examples. The materials, amounts used, proportions, processing content, and processing procedures shown in the following examples can be modified as appropriate, as long as they do not depart from the spirit of the present invention. Therefore, the scope of the present invention is not limited to the specific examples shown below. If the measuring instruments used in the examples are difficult to obtain due to discontinuation or other reasons, measurements can be taken using other instruments with equivalent performance.

[0051] 1. Raw materials The components shown in Table 1 below were used. [Table 1]

[0052] The structure of the Adeka stub LA-31 is as follows: [ka] The structure of the SEESORB709 is as follows: [ka]

[0053] The structure of the Tinuvin 770 DF is as follows: [ka]

[0054] 2. Examples 1-3, Comparative Examples 1-7 <Pellet manufacturing> Each component shown in Table 1 was uniformly mixed in the proportions (parts by mass) shown in Table 2 or Table 3 using a tumbler mixer. The resin composition was then melt-kneaded using a twin-screw extruder (TEX30α, manufactured by Japan Steel Works, Ltd.) under conditions of a cylinder temperature of 260°C and a screw rotation speed of 200 rpm. The mixture was rapidly cooled in a water bath and pelletized using a pelletizer to obtain pellets of the resin composition.

[0055] <Manufacturing of test specimens> Using the obtained pellets, molded products (60mm long, 60mm wide, 1.5mm thick) were produced using a NEX80-9E injection molding machine manufactured by Nissei Plastic Industrial Co., Ltd., with a cylinder temperature of 250°C and a mold temperature controller set to 80°C. The initial hue (visual evaluation), bleed characteristics, lightfastness, and weather resistance of the obtained molded products were evaluated.

[0056] <Initial hue> The molded products obtained as described above were visually inspected. Those that appeared pale yellow indicate that their appearance was inferior from the beginning. The inspection was conducted by five experts and the decision was made by majority vote.

[0057] <Evaluation of bleed characteristics (bleeding confirmed at 120°C)> The molded product obtained above was placed horizontally in a hot air dryer and subjected to a test treatment at a setting of 120°C for 120 hours. After heat treatment, the molded product was removed and allowed to stand until it reached room temperature. The surface of the molded product (the top surface where it was placed) was wiped with a cloth, and the bleed characteristics of the mold release agent component were visually judged according to the following four-stage criteria. Products similar to Comparative Example 7 were evaluated as "C," and the decision was made by majority vote after confirmation by five experts. A: No liquid droplets on the molded product surface, and no traces left on the area wiped with a cloth. B: No liquid droplets on the molded product surface, and slight traces remain where the cloth was wiped. C: No liquid droplets on the molded product surface, and clear marks remain where the cloth was used for wiping. D: Liquid droplets are present on the surface of the molded product.

[0058] <Evaluation of lightfastness (120°C lightfastness (color difference))> The molded product obtained as described above was placed vertically in a lightfastness tester, set to 120°C and with an accumulated illuminance of 51 kJ / m². 2 The molded product was subjected to a 600-hour test treatment at a wavelength of 275 nm. After treatment, the molded product was removed and allowed to stand at room temperature. The surface of the molded product (irradiated surface) was evaluated using a colorimeter (Konica Minolta SPECTRO PHOTOMETER CM-3600d, SCI method), and the color difference Δb value (Δb value = b value after treatment - b value before treatment) was calculated. Visual inspection was performed according to the following three criteria. A: Δb value less than 15 B: Δb value of 15 or greater, and less than 20. C: Δb value of 20 or higher

[0059] <Evaluation of weather resistance (color difference)> The molded products obtained above were placed vertically in a weathering tester (ATRUS ci4000) and subjected to a 400-hour test treatment according to the prescribed test standard (SAE J1960). After treatment, the molded products were removed and allowed to stand at room temperature. The surface (irradiated surface) of the molded products was evaluated using a color difference meter (Konica Minolta SPECTRO PHOTOMETER CM-3600d, SCI method), and the color difference Δb value (Δb value = b value after treatment - b value before treatment) was calculated. Visual inspection was performed according to the following two-stage criteria. A: Δb value less than 4 B: Δb value of 4 or higher

[0060] <Overall Rating> For each example and comparative example, a score was calculated according to the following criteria. Initial hue: White 1 point, other colors (pale yellow, etc.) 0 points Breeding characteristics: A rating (1 point), other ratings (0 points) Lightfastness: A rating (1 point), other ratings (0 points) Weather resistance: A rating (1 point), other ratings (0 points) Based on the calculated scores, the evaluation was as follows: A: 4 points B: 3 points C: 2 points D: 1 point E: 0 points

[0061] [Table 2]

[0062] [Table 3]

[0063] As is clear from the above results, molded articles obtained from the resin composition of the present invention exhibited excellent light resistance and weather resistance. In particular, in the present invention, light resistance (120°C light resistance (color difference)) after prolonged exposure to light irradiation at high temperatures was improved by the use of a predetermined mold release agent. The contribution of the mold release agent to light resistance was an unexpected effect.

Claims

1. It comprises a polyester resin, an ultraviolet absorber, and a mold release agent having a melting point of 90 to 150°C. The polyester resin comprises polybutylene terephthalate resin, The aforementioned UV absorber comprises a structure represented by the following formula (1) and has a molecular weight of 600 or less, in a resin composition, A resin composition in which the polyester resin content is 70% by mass or more in the resin composition. Formula (1) 【Chemistry 1】

2. Furthermore, the resin composition according to claim 1, further comprising a light stabilizer.

3. The resin composition according to claim 2, wherein the light stabilizer comprises a hindered amine-based light stabilizer.

4. The resin composition according to any one of claims 1 to 3, wherein the content of the mold release agent is 0.01 to 1.0 parts by mass per 100 parts by mass of polyester resin.

5. The resin composition according to any one of claims 1 to 4, wherein the total of the polyester resin, the ultraviolet absorber, and the mold release agent accounts for 94% by mass or more of the resin composition.

6. A resin composition according to any one of claims 1 to 5, for forming molded articles for outdoor use.

7. A molded article formed from the resin composition according to any one of claims 1 to 6.

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