Thermoplastic polyester elastomer resin composition and molded object

Abstract

Provided is a thermoplastic polyester elastomer resin composition having excellent weather resistance. This thermoplastic polyester elastomer resin composition comprises a thermoplastic polyester elastomer and a light shielding agent and further comprises at least one selected from the group consisting of a UV absorber, a light stabilizer, and a thickener, wherein the thermoplastic polyester elastomer does not contain either or both of a structural unit derived from 1,4-cyclohexanedimethanol and a structural unit derived from a hydrogenated dimer diol. In a 50 μm thick single layer film of the thermoplastic polyester elastomer resin composition, the ratio of light transmittance at wavelengths of 380 nm and 600 nm (380 nm / 600 nm) is less than 0.80, and the light transmittance at 600 nm is 70% or less.

Description

Thermoplastic polyester elastomer resin composition and molded article

[0001] The present invention relates to a thermoplastic polyester elastomer resin composition and a molded article using the resin composition, and more particularly to a thermoplastic polyester elastomer resin composition excellent in weather resistance and a molded article using the resin composition.

[0002] Thermoplastic polyester elastomers have properties such as flexibility, resilience, low-temperature characteristics, and flexural fatigue resistance, and particularly excellent heat resistance and oil resistance. Compared with other thermoplastic elastomers, thermoplastic polyester elastomers have stable mechanical properties such as tensile strength and flexural fatigue resistance from the low-temperature range to the high-temperature range, and are suitable for applications that can be used in both low-temperature and high-temperature environments. In addition, since thermoplastic polyester elastomers can be molded by various processes such as injection molding, extrusion molding, blow molding, compression molding, and calender molding, they are used in a wide range of applications such as automotive parts, electrical and electronic parts, fibers, sheets and films, bottles and containers.

[0003] There are various molded articles using thermoplastic polyester elastomer resin compositions. Since they are used in various environments such as being directly exposed to sunlight, rain, and wind, it has been required that they do not discolor or deteriorate in physical properties in such environments. For example, Patent Document 1 discloses a thermoplastic polyester elastomer resin composition comprising a thermoplastic polyester elastomer, a thickening agent, an ultraviolet absorber, and a light stabilizer. Patent Document 2 discloses a thermoplastic polyester elastomer resin composition comprising a thermoplastic polyester elastomer, a phosphorus-based flame retardant, and a hindered amine radical scavenger.

[0004] International Publication No. 2019 / 004120 pamphlet International Publication No. 2018 / 155411 pamphlet

[0005] Conventionally, attempts have been made to suppress discoloration and deterioration of physical properties of thermoplastic polyester elastomer resin compositions using UV absorbers and light stabilizers, but these have not been sufficiently effective. For example, in applications subject to repeated fatigue, prolonged exposure to ultraviolet light significantly reduces mechanical properties such as flexural fatigue resistance and tensile strength, which has been a problem. However, from the perspective of maintaining product performance, it has been desirable to suppress the deterioration of mechanical properties.

[0006] The object of the present invention is to provide a thermoplastic polyester elastomer resin composition that has excellent weather resistance, for example, that can suppress discoloration and deterioration of mechanical properties even when exposed to light including ultraviolet rays for a long period of time.

[0007] The present invention, which has been able to solve the above problems, has the following configuration: [1] A thermoplastic polyester elastomer resin composition comprising a thermoplastic polyester elastomer and a light shielding agent, further comprising one or more selected from the group consisting of an ultraviolet absorber, a light stabilizer and a thickener, wherein the thermoplastic polyester elastomer does not contain either or both of the constituent units derived from 1,4-cyclohexanedimethanol and the constituent units derived from hydrogenated dimergol, and the light transmittance ratio (380 nm / 600 nm) at wavelengths of 380 nm and 600 nm in a single layer film of the thermoplastic polyester elastomer resin composition with a thickness of 50 μm is less than 0.80, and the light transmittance at 600 nm is 70% or less.

[0008] [2] The thermoplastic polyester elastomer resin composition according to [1], wherein the acid value is 25 eq / ton or less. [3] The thermoplastic polyester elastomer resin composition according to [1] or [2], wherein the light shielding agent is carbon black. [4] The thermoplastic polyester elastomer resin composition according to [1] or [2], wherein the light shielding agent is zinc oxide. [5] The thermoplastic polyester elastomer resin composition according to any one of [1] to [4], comprising less than 3 parts by mass in total of the ultraviolet absorber and the light stabilizer per 100 parts by mass of the thermoplastic polyester elastomer. [6] The thermoplastic polyester elastomer resin composition according to [3], comprising 0.1 to 20 parts by mass of the carbon black per 100 parts by mass of the thermoplastic polyester elastomer. [7] The thermoplastic polyester elastomer resin composition according to [4], comprising 0.1 to 15 parts by mass of zinc oxide per 100 parts by mass of the thermoplastic polyester elastomer. [8] A thermoplastic polyester elastomer resin composition according to any one of [1] to [7], characterized in that the retention rate of tensile strength at break after a 600-hr weathering test is 80% or more. [9] A thermoplastic polyester elastomer resin composition according to any one of [1] to [8], characterized in that the retention rate of bending fatigue cycles after a 600-hr weathering test is 4% or more.

[10] A molded article made from the thermoplastic polyester elastomer resin composition according to any one of [1] to [9].

[0009] According to the present invention, a thermoplastic polyester elastomer resin composition having excellent weather resistance can be provided. Furthermore, due to the above effect, molded articles using the resin composition of the present invention can suppress discoloration and deterioration of mechanical properties even when exposed to light, including ultraviolet rays, for a long period of time.

[0010] The thermoplastic polyester elastomer resin composition of this disclosure (hereinafter sometimes simply referred to as "resin composition") comprises a thermoplastic polyester elastomer and a light-shielding agent, and further comprises one or more selected from the group consisting of ultraviolet absorbers, light stabilizers, and thickeners, wherein the light transmittance ratio (380 nm / 600 nm) at wavelengths of 380 nm and 600 nm in a 50 μm thick single-layer film of the resin composition is less than 0.80, and the light transmittance at 600 nm is 70% or less. In this disclosure, weather resistance may mean durability under environmental conditions including ultraviolet light. Durability may refer to discoloration and mechanical properties of the resin composition. Mechanical properties may mean tensile strength at break (sometimes referred to as tensile strength) and flexural fatigue resistance, and preferably also include elongation and fatigue properties. In preferred embodiments of this disclosure, weather resistance may further include hydrolysis resistance.

[0011] The reason for using the light transmittance ratio of light transmittance at a wavelength of 380 nm to light transmittance at a wavelength of 600 nm is as follows: In order to suppress discoloration and deterioration of the mechanical properties of the resin composition, it is necessary to improve weather resistance to light, especially ultraviolet light. However, it is not possible to address the entire wavelength range of ultraviolet light with ultraviolet absorbers alone, and thus discoloration and deterioration of the mechanical properties of the resin composition cannot be suppressed. For example, ultraviolet absorbers with ultraviolet absorption peaks in the short-wavelength ultraviolet region (UV-C: 290 nm or less) or the medium-wavelength ultraviolet region (UV-B: 290 to 320 nm) cannot sufficiently absorb ultraviolet light around 380 nm, and therefore cannot suppress the photodegradation of the resin composition. Furthermore, even with ultraviolet absorbers corresponding to the long-wavelength region (UV-A: 320 to 400 nm), the ultraviolet absorption peak is 340 to 360 nm, so they cannot sufficiently absorb ultraviolet light around 380 nm, and therefore cannot suppress the photodegradation of the resin composition. For this reason, this disclosure focuses on the wavelength of 380 nm, which is particularly difficult to block among ultraviolet light. Furthermore, ultraviolet light around 380 nm belongs to the longer wavelength range of UV-A, and is thought to penetrate deeper into molded products, causing cumulative photodegradation and affecting the long-term durability of mechanical properties. Therefore, blocking ultraviolet light around 380 nm is considered an important point in suppressing photodegradation of thermoplastic polyester elastomer resin compositions. The reason for setting the wavelength at 600 nm as the reference value is that it was selected as a wavelength that is not affected by differences in the composition of the thermoplastic polyester elastomer constituting the resin composition.

[0012] The inventors have found that if the ratio of light transmittance at a wavelength of 380 nm to light transmittance at a wavelength of 600 nm (380 nm / 600 nm) is less than 0.80, and the light transmittance at a wavelength of 600 nm is 70% or less, then discoloration and deterioration of mechanical properties of the resin composition can be suppressed even when exposed to light including ultraviolet light for a long period of time. Furthermore, molded articles using the resin composition of this disclosure not only suppress discoloration, but also have excellent properties such as tensile strength, flexibility, rebound elasticity, and bending fatigue resistance, and preferably have excellent resistance to moisture and heat and oil.

[0013] The thermoplastic polyester elastomer resin composition of this disclosure has a light transmittance ratio (380 nm / 600 nm) of less than 0.80 at wavelengths of 380 nm and 600 nm in a single-layer film with a thickness of 50 μm. If the light transmittance ratio (380 nm / 600 nm) is 0.80 or higher, the resin composition may deteriorate due to light (especially ultraviolet light), i.e., it may become more susceptible to yellowing (discoloration) or its mechanical properties may decrease. When mechanical properties decrease, it may lead to product damage even when external forces are applied within a range that would not cause problems with the original mechanical properties of the resin composition. In particular, the durability performance during repeated fatigue may decrease, and the service life may decrease. The light transmittance ratio (380 nm / 600 nm) is preferably 0.75 or less, more preferably 0.50 or less, even more preferably 0.30 or less, even more preferably 0.12 or less, and most preferably 0.07 or less.

[0014] Furthermore, the light transmittance at the above wavelength of 600 nm is 70% or less. If the light transmittance exceeds 70%, problems such as discoloration of the resin composition and a decrease in mechanical properties will occur, similar to the above light transmittance ratio. The light transmittance at the wavelength of 600 nm is preferably 60% or less, more preferably 50% or less, even more preferably 40% or less, and even more preferably 35% or less.

[0015] In a preferred embodiment of this disclosure, the transmittance at a wavelength of 380 nm is preferably 25% or less, more preferably 20% or less, and even more preferably 15% or less. A lower light transmittance at a wavelength of 380 nm is preferable because it suppresses discoloration and deterioration of mechanical properties of the resin composition.

[0016] [Thermoplastic Polyester Elastomer] The thermoplastic polyester elastomer contained in the resin composition is a copolymer of hard segments and soft segments. The hard segments and soft segments may be bonded by a chain extender such as an isocyanate compound, or each constituent unit of the hard segments and soft segments may be directly bonded by ester bonds and / or carbonate bonds.

[0017] The hard segment is made of polyester, and the polyester is composed of an aromatic dicarboxylic acid or its ester-forming derivative (sometimes called an acid component) and a diol or its ester-forming derivative (sometimes called a diol component). As the aromatic dicarboxylic acid, at least one selected from the group consisting of terephthalic acid and naphthalenedicarboxylic acid is preferred. As the naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid is preferred. As the ester-forming derivative, for example, dimethyl terephthalate, which is a dimethyl ester of terephthalic acid, is an example. Other dicarboxylic acids (other acid components) other than the aromatic dicarboxylic acid may also be included. Examples of other acid components include aromatic dicarboxylic acids other than terephthalic acid and naphthalenedicarboxylic acid (other aromatic dicarboxylic acids), aliphatic dicarboxylic acids, and alicyclic dicarboxylic acids. Examples of other aromatic dicarboxylic acids include diphenyldicarboxylic acid, isophthalic acid, and 5-sodium sulfisoisophthalic acid. Examples of aliphatic dicarboxylic acids include succinic acid, glutaric acid, adipic acid, azelaic acid, sebacic acid, and dodecanedioic acid. Examples of alicyclic dicarboxylic acids include cyclohexanedicarboxylic acid and tetrahydrophthalic anhydride.

[0018] The total amount of terephthalic acid and / or naphthalenedicarboxylic acid in the total dicarboxylic acids constituting the hard segment is preferably 60 mol% or more, more preferably 65 mol% or more, even more preferably 70 mol% or more, and may be 100 mol%. The remainder may consist of the other acidic components mentioned above.

[0019] The diol component is preferably a glycol, more preferably an aliphatic diol. The aliphatic diol is not particularly limited, but for example, alkylene glycols having 2 to 8 carbon atoms are desirable. Suitable examples of aliphatic diols include ethylene glycol, 1,3-propylene glycol, 1,4-butanediol, pentanediol, and 1,6-hexanediol, with 1,4-butanediol being more preferred. These may be used individually or in combination of two or more.

[0020] The constituent units of the polyester described above are preferably those derived from butylene terephthalate (derived from terephthalic acid and 1,4-butanediol) and / or those derived from butylene naphthalate (derived from 2,6-naphthalenedicarboxylic acid and 1,4-butanediol), with those derived from butylene terephthalate being more preferred. These constituent units are effective in improving the physical properties and moldability of the thermoplastic polyester elastomer resin composition and are also preferred from the viewpoint of cost performance.

[0021] The soft segment is a component that imparts flexibility to the elastomer, and is preferably at least one selected from the group consisting of aliphatic polyethers, aliphatic polyesters, and aliphatic polycarbonates, and more preferably an aliphatic polyether. The compounds exemplified below may be used alone or in combination of two or more.

[0022] Examples of aliphatic polyethers include poly(ethylene oxide) glycol, poly(propylene oxide) glycol, poly(tetramethylene oxide) glycol, poly(hexamethylene oxide) glycol, poly(trimethylene oxide) glycol, copolymers of ethylene oxide and propylene oxide, ethylene oxide adducts of poly(propylene oxide) glycol, and copolymers of ethylene oxide and tetrahydrofuran. Among these, poly(tetramethylene oxide) glycol and ethylene oxide adducts of poly(propylene oxide) glycol are preferred, and poly(tetramethylene oxide) glycol is more preferred, considering flexibility, long-term durability such as long-term heat aging resistance, hydrolysis resistance, and flexural fatigue resistance, and chemical stability.

[0023] Examples of aliphatic polyesters include poly(ε-caprolactone), polyenanthractone, polycapryloractone, and polybutylene adipate. Among these, poly(ε-caprolactone) and polybutylene adipate are preferred when considering flexibility, durability, and chemical stability.

[0024] The aliphatic polycarbonate is preferably a polycarbonate diol derived from an aliphatic diol having 2 to 12 carbon atoms. Examples of diols used as raw materials include ethylene glycol, 1,3-propylene glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,8-octanediol, 2,2-dimethyl-1,3-propanediol, 3-methyl-1,5-pentanediol, 2,4-diethyl-1,5-pentanediol, 1,9-nonanediol, and 2-methyl-1,8-octanediol. Among these, aliphatic diols having 5 to 12 carbon atoms are preferred considering the flexibility, durability, and chemical stability of the thermoplastic polyester elastomer.

[0025] In this disclosure, it is also preferable to select the soft segment considering its low-temperature properties. For example, as an aliphatic polycarbonate diol that constitutes the soft segment and has good low-temperature properties, it is preferable to have a low melting point (e.g., 70°C or lower) and a low glass transition temperature (e.g., around -70°C). An aliphatic polycarbonate diol made of 1,6-hexanediol used to form the soft segment of a thermoplastic polyester elastomer has a low glass transition temperature of around -60°C and a melting point of around 50°C, thus having good low-temperature properties. Furthermore, an aliphatic polycarbonate diol obtained by copolymerizing an appropriate amount of, for example, 3-methyl-1,5-pentanediol with an aliphatic polycarbonate diol has a slightly higher glass transition temperature than the original aliphatic polycarbonate diol, but its melting point is lower or it becomes amorphous, thus corresponding to an aliphatic polycarbonate diol with good low-temperature properties. For example, an aliphatic polycarbonate diol composed of 1,9-nonanediol and 2-methyl-1,8-octanediol has a sufficiently low melting point of around 30°C and a glass transition temperature of around -70°C, making it an aliphatic polycarbonate diol with good low-temperature properties.

[0026] The average molecular weight of at least one component selected from the group consisting of aliphatic polyethers, aliphatic polyesters, and aliphatic polycarbonates that constitute the soft segment, preferably poly(tetramethylene oxide) glycol, is preferably 500 to 4000, more preferably 600 to 3000, and even more preferably 800 to 2500. If the number average molecular weight is too low, it may be difficult to exhibit elastomer properties. If the number average molecular weight is too high, the compatibility with the hard segment component decreases, and it may become difficult to copolymerize it in a block-like structure, for example.

[0027] Considering weather resistance, the thermoplastic polyester elastomer used in this disclosure is preferably a copolymer mainly composed of terephthalic acid, 1,4-butanediol, and poly(tetramethylene oxide) glycol. In one embodiment, the thermoplastic polyester elastomer is preferably a block copolymer having a polyester hard segment composed of terephthalic acid and 1,4-butanediol and a polyether soft segment composed of poly(tetramethylene oxide) glycol. Among the dicarboxylic acid components constituting the thermoplastic polyester elastomer, terephthalic acid is preferably 40 mol% or more, more preferably 70 mol% or more, even more preferably 80 mol% or more, particularly preferably 90 mol% or more, and may be 100 mol%. Among the glycol components constituting the thermoplastic polyester elastomer, the total of 1,4-butanediol and poly(tetramethylene oxide) glycol is preferably 40 mol% or more, more preferably 70 mol% or more, even more preferably 80 mol% or more, particularly preferably 90 mol% or more, and may be 100 mol%.

[0028] Furthermore, the thermoplastic polyester elastomer of this disclosure does not contain either or both of the constituent units derived from 1,4-cyclohexanedimethanol and / or hydrogenated dimer ol. Preferably, it does not contain either the constituent units derived from 1,4-cyclohexanedimethanol or hydrogenated dimer ol.

[0029] In thermoplastic polyester elastomers, the mass ratio of hard segments to soft segments (hard segments:soft segments) is preferably 10:90 to 95:5, more preferably 15:85 to 90:10. If the soft segment ratio is excessively low, flexibility, elasticity, impact resistance, and processability may be insufficient. On the other hand, if the soft segment ratio is excessively high, heat resistance and abrasion resistance may decrease. Considering the balance between tensile strength and flexural fatigue after weathering tests in particular, the mass ratio (hard segments:soft segments) is even more preferably 20:80 to 85:15, and most preferably 25:75 to 75:25. If there are too few hard segments, heat resistance may be insufficient, and tensile strength may decrease, especially after weathering tests. On the other hand, if there are too many hard segments, flexibility may decrease, and flexural fatigue may worsen, especially after weathering tests. In one embodiment, for applications where heat resistance and wear resistance are particularly required, the mass ratio (hard segment:soft segment) may be preferably 50:50 to 95:5, and more preferably 50:50 to 60:40.

[0030] The reduced viscosity of thermoplastic polyester elastomer is preferably 0.5 to 4.0 dl / g, more preferably 1.0 to 3.5 dl / g, considering fluidity, moldability, heat aging resistance, hydrolysis resistance, mechanical properties, and chemical resistance. The reduced viscosity is measured, for example, with phenol / tetrachloroethane = 60 / 40 as the solvent at a concentration of 0.23 g / dL at 30°C.

[0031] Light-shielding agent The thermoplastic polyester elastomer resin composition of this disclosure further comprises a light-shielding agent. In this disclosure, a light-shielding agent is a substance that has the property of reflecting light on its surface (sometimes called light reflectivity) and / or absorbing and dissipating light within the substance (sometimes called light absorption). A light-reflective light-shielding agent may have the property of absorbing light of a specific wavelength in addition to reflecting light. A light-absorbing light-shielding agent may have the property of reflecting light of a specific wavelength in addition to absorbing light. As a result of the inventors' studies, it has been found that when a light-shielding agent having the above properties is incorporated into a resin composition, a light-shielding effect is obtained not only for short-wavelength and medium-wavelength ultraviolet light but also for the long-wavelength region, and in particular, photodegradation of the resin composition due to ultraviolet light around 380 nm can be suppressed, and optical properties can also be controlled for wavelengths in the visible light and near-infrared regions other than ultraviolet light. Because light is blocked by the light-shielding agent contained in the resin composition, photodegradation of the resin composition due to light (especially ultraviolet light, the same applies hereinafter) can be suppressed. It is preferable to use an inorganic material as the light-shielding agent. A typical example of an absorbent light-shielding agent is carbon black, which is particularly preferred due to its excellent dispersibility in resins. Typical examples of light-reflecting light-shielding agents include magnesium oxide, aluminum oxide, silicon oxide, calcium oxide, titanium oxide (rutile and anatase types), chromium oxide (trivalent), iron oxide, zinc oxide, silica, diatomaceous earth, barium ferrite, strontium ferrite, beryllium oxide, magnesium hydroxide, aluminum hydroxide, basic compounds or hydroxides of basic magnesium carbonate, or magnesium carbonate, calcium carbonate, barium carbonate, calcium sulfite, dolomite, dawsonite carbonates, and calcium sulfate. ()Sulfites such as sodium, barium sulfate, calcium sulfite, and basic magnesium sulfate, sodium silicate, magnesium silicate, aluminum silicate, potassium silicate, calcium silicate, talc, clay, mica, montmorillonite, glass balloons, glass beads, bentonite silicates, kaolin (clay), perlite, molybdenum sulfide, potassium titanate, lead zirconate titanate, zinc borate, aluminum borate, barium metaborate, calcium borate, sodium borate, etc. are preferred, and zinc oxide is more preferred.One or more types of light-shielding agents may be used in combination. The light-shielding agents should be selected appropriately depending on the application and desired effect, but since metal light-shielding agents themselves may cause resin degradation, it is preferable to use stable inorganic materials such as oxides or carbonates, or non-metallic materials such as carbon black. In this disclosure, either a light-reflective light-shielding agent or a light-absorbing light-shielding agent may be used, or both may be used in combination.

[0032] In one embodiment, the content of the light-shielding agent in the resin composition is preferably adjusted considering the light transmittance ratio (380 nm / 600 nm) and the light transmittance at a wavelength of 600 nm. For example, the content of the light-absorbing light-shielding agent in the resin composition is preferably 0.1 to 20 parts by mass, more preferably 0.2 to 15 parts by mass, even more preferably 0.25 to 12 parts by mass, and particularly preferably 0.3 to 10 parts by mass, per 100 parts by mass of thermoplastic polyester elastomer. Considering higher dispersibility and flexural fatigue resistance, the upper limit is preferably less than 10 parts by mass, more preferably 6 parts by mass or less, and particularly preferably 2 parts by mass or less. Also, for example, the content of the light-reflective light-shielding agent in the resin composition is preferably 0.1 to 20 parts by mass, more preferably 0.1 to 15 parts by mass, even more preferably 0.25 to 12 parts by mass, and particularly preferably 0.3 to 10 parts by mass, per 100 parts by mass of thermoplastic polyester elastomer. Excessive content may lead to poor dispersion, poor filling, and even decomposition of the resin composition and a decrease in flexural fatigue resistance.

[0033] The UV absorber, light stabilizer, and thickener resin composition further includes at least one selected from the group consisting of UV absorbers, light stabilizers, and thickeners. By including these in combination with a light shielding agent, it is possible to maintain long-term weather resistance and mechanical strength, or improve hydrolysis resistance. For example, if the amount of light shielding agent is too high, problems may occur in the manufacturing process (hereinafter referred to as productivity), such as mesh clogging or contamination of the product with aggregated foreign matter, and a decrease in strength may occur. On the other hand, reducing the amount of light shielding agent can suppress mesh clogging and improve productivity, but the light-blocking effect will also be reduced. Therefore, in one embodiment, it is preferable to use a light shielding agent in combination with a UV absorber and / or a light stabilizer (hereinafter sometimes referred to as UV absorber / light stabilizer). This allows for an excellent light degradation prevention effect even when the amount of light shielding agent is reduced, and further balances weather resistance and mechanical properties. Either the UV absorber or the light stabilizer may be used alone, or they may be used in combination. In one embodiment, the resin composition may contain a thickener regardless of the presence or absence of a UV absorber / light stabilizer. By incorporating a thickener, an increase in molecular weight and a reduction in acid value can be obtained through the reaction of end groups, which in particular improves hydrolysis resistance and contributes to the long-term maintenance of weather resistance and mechanical properties. Thus, the above additives can be selected according to their effects, but when combined with a light shielding agent, a synergistic effect can be achieved, resulting in an even higher level of both weather resistance and mechanical properties. In one embodiment, a thickener and a UV absorber / light stabilizer may be used in combination, or only a thickener may be used, or only a UV absorber / light stabilizer may be used.

[0034] UV absorbers and light stabilizers have different mechanisms of action, but both are effective in preventing photodegradation caused by ultraviolet light. UV absorbers primarily absorb and neutralize ultraviolet light, while light stabilizers are mainly responsible for radical scavenging and deactivating excited states. When both are used together, a synergistic effect allows for long-term weather resistance to external environmental factors such as sunlight, temperature changes, humidity, and rainwater.

[0035] The ultraviolet absorber may be a substance that has absorption ability in the ultraviolet region (UVA: 320-400 nm, UVB: 280-320 nm, UVC: 200-280 nm), but preferably one that has an absorption peak in the UVA region, and especially preferably one that has an absorption peak in ultraviolet light around 380 nm, is effective in reducing transmittance. This complementarily absorbs light around 380 nm, which cannot be sufficiently blocked by light shielding agents alone, and more effectively suppresses photodegradation inside the resin. Known compounds that can be used as ultraviolet absorbers include benzophenone-based, benzotriazole-based, triazine-based, cyanoacrylate-based, salicylate-based, oxanilide-based, and nickel-based compounds. Among these, considering the stability at the processing temperature of the resin composition and compatibility with the resin, at least one selected from the group consisting of benzophenone-based ultraviolet absorbers, benzotriazole-based ultraviolet absorbers, and triazine-based ultraviolet absorbers is preferred.

[0036] Examples of benzophenone-based UV absorbers include 2,2'-dihydroxy-4-methoxybenzophenone, 2-hydroxy-4-n-octoxybenzophenone, 2-hydroxy-4-i-octoxybenzophenone, 2-hydroxy-4-dodecyloxybenzophenone, 2-hydroxy-4-octadecyloxybenzophenone, 2,4-di-t-butylphenyl-3,5-di-t-butyl-4-hydroxybenzoate, 2,5-bis-[5'-t-butylbenzoxazolyl-(2)]-thiophene, and bis(5-benzoyl-4-hydroxy-2-methoxyphenyl)methane.

[0037] Examples of benzotriazole-based UV absorbers include 2-(2'-hydroxy-5'-methylphenyl)benzotriazole, 2-(2'-hydroxy-3',5'-di-t-amyl-phenyl)benzotriazole, 2-[2'-hydroxy-3',5'-bis(α,α-dimethylbenzylphenyl)benzotriazole, 2-(2'-hydroxy-3'-t-butyl-5'-methylphenyl)-5-chlorobenzotriazole, 2-[2-hydroxy-3,5-bis(α,α-dimethylbenzyl)phenyl]-2H-benzotriazole, 2-[2'-hydrooxy-5'-methyl-3'-(3'',4'',5'',6''-tetrahydrophthalimidomethyl)phenyl]benzotriazole, 2-(2'-hydroxy-5'-t-octylphenyl)benzotriazole, and 2-(2'-hydroxy-3',5'-di-t-butylphenyl)-5-chlorobenzotriazole.

[0038] Examples of triazine-based UV absorbers include 2-(4,6-diphenyl-1,3,5-triazine-2-yl)-5-(hexyloxy)phenol and 2,4,6-tris(4-butoxy2-hydroxyphenyl)-1,3,5-triazine. Examples of cyanoacrylate-based UV absorbers include ethyl-2-cyano-3,3-diphenyl acrylate, 2'-ethylhexyl-2-cyano-3,3-diphenyl acrylate, ethyl-2-cyano-3-(3',4'-methylenedioxyphenyl)-2-acrylate, 2'-ethylhexyl-2-cyano-3-(3'',4''-methylenedioxyphenyl)-2-acrylate, dodecyl-2-cyano-3-(3',4'-methylenedioxyphenyl)-2-acrylate, methyl-2-cyano-3,3-diphenyl acrylate, ethyl-2-cyano-3,3-ditril acrylate, and ethyl-2-cyano-3,3-dinaphthyl acrylate.

[0039] Examples of salicylate-based UV absorbers include phenyl salicylate and p-t-butylphenyl salicylate.

[0040] Oxanilide-based ultraviolet absorbers include a mixture of 85 to 90% of 2-ethoxy-5-t-butyl-2'-ethyloxalic acid-bis-anilide and 10 to 15% of 2-ethoxy-5-t-butyl-2'-ethyl-4'-t-butyl oxalic acid-bis-anilide, and 2-ethoxy-2'-ethyloxazalic acid bisanilide is exemplified.

[0041] Nickel-based ultraviolet absorbers are exemplified by bis(3,5-di-t-butyl-4-hydroxybenzyl phosphoric acid monoethyl ester) nickel salt.

[0042] In addition to the above, various known ultraviolet absorbers (including commercially available products) can be used. The ultraviolet absorber can be used alone or in combination of two or more. In one embodiment, it is preferable to use ultraviolet absorbers having different absorption wavelength ranges in combination, because the light deterioration prevention effect can be exerted over a wider wavelength range.

[0043] A light stabilizer is a substance having an action of capturing free radicals generated in a resin, and is preferable because it can suppress the deterioration of the resin caused by a photoexcitation reaction for a long period. In one embodiment, as the light stabilizer, a hindered amine light stabilizer (HALS) is preferable. Also, the hindered amine light stabilizer may be either a low-base type such as a tertiary amine type (N-CH ３ ) or an N-alkoxy type (NO-Alkyl), or a high-base type of a secondary amine type (N-H). In one embodiment, since the low-base type of HALS has a low basicity, it is less likely to be affected (inactivated) by acidic substances that may be present in the resin, and may exhibit stable performance for a long period. Also, from the viewpoint of suppressing adverse effects on the resin, a non-basic light stabilizer may be used. Hereinafter, specific examples are shown, but they may be used alone or in combination of two or more, and HALS may be a commercially available product.

[0044] Specific examples of low-basic HALS include 1,2,2,6,6-pentamethyl-4-piperidyl stearate, bis(1,2,2,6,6-pentamethyl-4-piperidyl) sebacate, bis(1-octoxy-2,2,6,6-tetramethyl-4-piperidyl) sebacate, tetrakis(1,2,2,6,6-pentamethyl-4-piperidyl)-1,2,3,4-butanetetracarboxylate, bis(1,2,2,6,6-pentamethyl-4-piperidyl)-di(tridecyl)-1,2,3,4-butanetetracarboxylate, and bis(1,2,2,4,4-pentamethyl-4-piperidyl)- Examples include 2-butyl-2-(3,5-di-t-butyl-4-hydroxybenzyl)malonate, 1-(2-hydroxyethyl)-2,2,6,6-tetramethyl-4-piperidinol / diethyl succinate polycondensate, 1,5,8,12-tetrakis[2,4-bis(N-butyl-N-(1,2,2,6,6-pentamethyl-4-piperidyl)amino)-s-triazine-6-yl]-1,5,8,12-tetraazadodecane, and 1,6,11-tris[2,4-bis(N-butyl-N-(1,2,2,6,6-pentamethyl-4-piperidyl)amino)-s-triazine-6-yl]aminoundecane.

[0045] Specific examples of high-basicity types of HALS include 2,2,6,6-tetramethyl-4-piperidyl stearate, 2,2,6,6-tetramethyl-4-piperidyl benzoate, bis(2,2,6,6-tetramethyl-4-piperidyl) sebacate, tetrakis(2,2,6,6-tetramethyl-4-piperidyl)-1,2,3,4-butanetetracarboxylate, bis(2,2,6,6-tetramethyl-4-piperidyl)·di(tridecyl)-1,2,3,4-butanetetracarboxylate, 1,6-bis(2,2,6,6-tetramethyl-4-piperidylamino)hexane / 2,4-dichloro-6-morpholino-s-triazine polycondensate, 1,6-bis(2,2,6,6-tetramethyl-4-piperidylamino)hexane / 2,4-dichloro-6-tert-octylamino-s-triazine polycondensate, 1,5,8,12-tetrakis[2,4-bis(N-butyl-N-(2,2,6,6-tetramethyl-4-piperidyl)amino)-s-triazin-6-yl]-1,5,8,12-tetraazadodecane, and 1,6,11-tris[2,4-bis(N-butyl-N-(2,2,6,6-tetramethyl-4-piperidyl)amino)-s-triazin-6-yl]aminoundecane.

[0046] In one embodiment, when a light-shielding agent and an ultraviolet absorber / light stabilizer are used in combination, considering the balance between productivity and weather resistance, for example, the upper limit of the light-absorbing light-shielding agent is preferably less than 2 parts by mass, more preferably 1.5 parts by mass or less, still more preferably 1.0 part by mass or less, and even more preferably 0.5 part by mass or less, based on 100 parts by mass of the thermoplastic polyester elastomer. Also, the upper limit of the light-reflective light-shielding agent is preferably 10 parts by mass or less, more preferably 9 parts by mass or less, and still more preferably 7 parts by mass or less. In one embodiment, when the light-shielding agent is used in combination with an ultraviolet absorber and / or a light stabilizer, within the above content range, it can maintain excellent weather resistance while improving mechanical properties such as the flexural fatigue resistance of the resin composition, and further solve productivity problems such as mesh clogging.

[0047] The total content of the UV absorber / light stabilizer is preferably 0.1 to 4.0 parts by mass, more preferably 0.2 to 3.5 parts by mass, and even more preferably 0.3 to 3.0 parts by mass, per 100 parts by mass of thermoplastic polyester elastomer. From the viewpoint of suppressing the bleed-out phenomenon, it is preferably less than 3.0 parts by mass, and more preferably 0.4 to 2.5 parts by mass. If the total content of the UV absorber / light stabilizer is too low, sufficient effects may not be obtained. If the total content of the UV absorber / light stabilizer is too high, problems may arise due to the bleed-out phenomenon, such as the UV absorber / light stabilizer rising to the surface of the resin composition and causing mold contamination and other machine base contamination.

[0048] The molecular weight of the UV absorber / light stabilizer is preferably 200 or more, more preferably 300 or more, and even more preferably 400 or more. If the molecular weight is too low, a bleed-out phenomenon may occur, which can cause poor appearance and reduced effectiveness of the resin composition (especially molded articles using the resin composition). The melting point of the UV absorber / light stabilizer is preferably 20°C or more, more preferably 30°C or more, and even more preferably 35°C or more, considering the ease of handling during processing of the resin composition and molded articles.

[0049] Terminal Acid Value In one embodiment, the resin composition of the present disclosure may also have a low terminal acid value in order to suppress the deterioration of mechanical properties due to hydrolysis over the long term. The terminal acid value is preferably 25 eq / ton or less, more preferably 20 eq / ton or less, even more preferably 15 eq / ton or less, even more preferably 10 eq / ton or less, and most preferably 0 eq / ton. A lower acid value is effective in improving hydrolysis resistance. A lower acid value is also preferable because it allows mechanical properties such as strength to be maintained over a long period of time. The acid value of the present disclosure is a value measured by the method described in the examples.

[0050] Thickening Agent In one embodiment, the thickening agent is effective in adjusting the viscosity and end acid value of thermoplastic polyester elastomers (especially resin compositions). The type and amount of thickening agent can be adjusted, for example, according to the molding method, to achieve the desired viscosity and acid value. The thickening agent is preferably a reactive compound that can react with the end groups of the thermoplastic polyester elastomer, such as hydroxyl groups, and more preferably a carbodiimide compound and / or an epoxy compound. The carbodiimide compound is a compound having at least one, preferably two or more, carbodiimide groups (-N=C=N-) in one molecule, and polymeric polycarbodiimides are particularly preferred. In one embodiment, from the viewpoint of weather resistance and compatibility, examples include aliphatic polycarbodiimides, alicyclic polycarbodiimides, aromatic polycarbodiimides, and copolymers thereof. Preferably, it is an aliphatic polycarbodiimide compound or an alicyclic polycarbodiimide compound. Preferred examples of carbodiimide compounds include diphenylcarbodiimide, dicyclohexylcarbodiimide, di-2,6-dimethylphenylcarbodiimide, diisopropylcarbodiimide, dioctyldecylcarbodiimide, di-o-toluylcarbodiimide, di-p-toluylcarbodiimide, di-p-nitrophenylcarbodiimide, di-p-aminophenylcarbodiimide, di-p-hydroxyphenylcarbodiimide, di-p-chlorophenylcarbodiimide, di-o-chlorophenylcarbodiimide, di-3,4-dichlorophenylcarbodiimide, di-2,5-dichlorophenylcarbodiimide, and p-phenylene-bis-o-toluylcarbodiimide. Ilcarbodiimide, p-phenylene-bis-dicyclohexylcarbodiimide, p-phenylene-bis-di-p-chlorophenylcarbodiimide, 2,6,2',6'-tetraisopropyldiphenylcarbodiimide, hexamethylene-bis-cyclohexylcarbodiimide, ethylene-bis-diphenylcarbodiimide, ethylene-bis-dicyclohexylcarbodiimide, N,N'-di-o-toluylcarbodiimide, N,N'-diphenylcarbodiimide, N,N'-dioctyldecylcarbodiimide, N,N'-di-2,6-dimethylphenylcarbodiimide, N-toluyl-N'-cyclohexylcarbodiimide, N,N'-di-2,6-diisopropylphenylcarbodiimide, N,N'-di-2,6-di-tert-butylphenylcarbodiimide, N-toluyl-N'-phenylcarbodiimide, N,N'-di-p-nitrophenylcarbodiimide, N,N'-di-p-aminophenylcarbodiimide, N,N'-di-p-hydroxyphenylcarbodiimide, N,N'-di-cyclohexylcarbodiimide, N,N'-di-p-toluylcarbodiimide, N,N'-benzylcarbodiimide, N-o tadecyl-N'-phenylcarbodiimide, N-benzyl-N'-phenylcarbodiimide, N-octadecyl-N'-toluylcarbodiimide, N-cyclohexyl-N'-toluylcarbodiimide, N-phenyl-N'-toluylcarbodiimide, N-benzyl-N'-toluylcarbodiimide, N,N'-di-o-ethylphenylcarbodiimide, N,N'-di-p-ethylphenylcarbodiimide, N,N'-di-o-isopropylphenylcarbodiimide, N, N'-di-p-isopropylphenylcarbodiimide, N,N'-di-o-isobutylphenylcarbodiimide, N,N'-di-p-isobutylphenylcarbodiimide, N,N'-di-2,6-diethylphenylcarbodiimide, N,N'-di-2-ethyl-6-isopropylphenylcarbodiimide, N,N'-di-2-isobutyl-6-isopropylphenylcarbodiimide, N,N'-di-2,4,6-trimethylphenylcarbodiimide, N,N'-di-2,4 Mono or dicarbodiimide compounds such as 6-triisopropylphenylcarbodiimide and N,N'-di-2,4,6-triisobutylphenylcarbodiimide; poly(1,6-hexamethylenecarbodiimide), poly(4,4'-methylenebiscyclohexylcarbodiimide), poly(1,3-cyclohexylenecarbodiimide), poly(1,4-cyclohexylenecarbodiimide), poly(4,4'-diphenylmethanecarbodiimide), poly(3,3'-dimethyl-4,Examples of polycarbodiimides include 4'-diphenylmethanecarbodiimide, poly(naphthylenecarbodiimide), poly(p-phenylenecarbodiimide), poly(m-phenylenecarbodiimide), poly(toluylcarbodiimide), poly(diisopropylcarbodiimide), poly(methyl-diisopropylphenylenecarbodiimide), poly(triethylphenylenecarbodiimide), and poly(triisopropylphenylenecarbodiimide). Among these, preferred are N,N'-di-2,6-diisopropylphenylcarbodiimide, 2,6,2',6'-tetraisopropyldiphenylcarbodiimide, and polycarbodiimide; more preferably poly(1,6-hexamethylenecarbodiimide), poly(4,4'-methylenebiscyclohexylcarbodiimide), poly(1,3-cyclohexylenecarbodiimide), poly(1,4-cyclohexylenecarbodiimide), poly(4,4'-diphenylmethanecarbodiimide), and poly(3,3'-dimethyl-4,4'-diphenylmethane). Polycarbodiimides such as carbodiimide, poly(naphthylenecarbodiimide), poly(p-phenylenecarbodiimide), poly(m-phenylenecarbodiimide), poly(toluylcarbodiimide), poly(diisopropylcarbodiimide), poly(methyl-diisopropylphenylenecarbodiimide), poly(triethylphenylenecarbodiimide), and poly(triisopropylphenylenecarbodiimide) are used, with poly(1,4-cyclohexylenecarbodiimide) and poly(triisopropylphenylenecarbodiimide) being particularly preferred.

[0051] Epoxy compounds are preferably epoxy compounds having at least one epoxy group, preferably two or more, in one molecule. Examples include aliphatic epoxy compounds, alicyclic epoxy compounds, aromatic epoxy compounds and their hydrogenated compounds, and aromatic or heterocyclic epoxy compounds. Examples of aliphatic epoxy compounds include ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, butanediol diglycidyl ether, neopentyl glycol diglycidyl ether, hexanediol diglycidyl ether, glycerin diglycidyl ether, trimethylolpropane triglycidyl ether, and diglycerin tetraglycidyl ether. Examples of alicyclic epoxy compounds include dicyclopentadiene dioxide, epoxycyclohexene carboxylic acid ethylene glycol diester, 3,4-epoxycyclohexenylmethyl-3'-4'-epoxycyclohexene carboxylate, and 1,2:8,9-diepoxylimonene. Examples of aromatic epoxy compounds and their hydrogenated compounds include aromatic epoxy compounds and their hydrogenated compounds obtained by the reaction of polyphenol compounds such as hydroquinone, resorcinol, bisphenol A, bisphenol F, 4,4'-dihydroxybiphenyl, tetrabromobisphenol A, 2,2-bis(4-hydroxyphenyl)-1,1,1,3,3,3-hexafluoropropane, and glycidyl ether of 1,6-dihydroxynaphthalene with epichlorohydrin. Examples of aromatic or heterocyclic epoxy compounds include diglycidyl phthalates and triglycidyl isocyanurates. Other preferred compounds include those having an epoxy group at the end of a silicone oil and compounds having an epoxy group with an alkoxysilane.

[0052] The amount of thickener is preferably 7 parts by mass or less, more preferably 5 parts by mass or less, and even more preferably 4 parts by mass or less, per 100 parts by mass of thermoplastic polyester elastomer, taking into consideration the balance between the moldability during manufacturing, the mechanical properties such as the flexural fatigue resistance of the resin composition (and molded article), and the acid value. If the amount is too high, the thickening effect will be excessive, which may adversely affect the moldability and mechanical properties of the molded article, or cause mold contamination.

[0053] In one embodiment, the resin composition according to the present disclosure includes a thermoplastic polyester elastomer, a light shielding agent, and at least one selected from the group consisting of an ultraviolet absorber, a light stabilizer, and a thickener, wherein the total content of these main components is preferably 80% by mass or more, more preferably 85% by mass or more, and even more preferably 90% by mass or more of the entire resin composition. If no other additives are included, these main components may be 100% by mass. The remainder may be other additives as exemplified below, to the extent that they do not impair the effects of the present disclosure.

[0054] Other Additives The resin composition of this disclosure may contain one or more known additives as needed, to the extent that it does not impair its effects. Specifically, examples of additives include: stabilizers such as antioxidants and metal deactivators; functional agents such as flame retardants, antistatic agents, antibacterial agents, and fluorescent whitening agents; and colorants and processing aids such as lubricants, coupling agents, and organic and inorganic pigments. Among these, antioxidants are preferably added to suppress oxidative degradation during thermoforming and product use. General-purpose types such as hindered phenols, phosphorus, sulfur, and aromatic amines can be used as antioxidants.

[0055] In one embodiment, the resin composition of the present disclosure preferably achieves both excellent weather resistance and good mechanical properties. In particular, it is desirable to have the following physical properties. In one embodiment, as an indicator of excellent weather resistance, the resin composition of the present disclosure preferably maintains high mechanical properties even after accelerated weathering tests. For example, the following properties are considered for long-term use outdoors.

[0056] Tensile Strength Retention Rate The resin composition of this disclosure exhibits suppressed reduction in tensile strength even after prolonged exposure to ultraviolet light. In one embodiment, the retention rate of tensile strength at break after a 600-hour weathering test is preferably 80% or more, more preferably 85% or more, even more preferably 90% or more, and even more preferably 94% or more.

[0057] The resin composition of this disclosure exhibits suppressed reduction in bending fatigue even after prolonged exposure to ultraviolet light. In one embodiment, the retention rate of bending fatigue after similar tests is preferably 4% or more, more preferably 10% or more, and even more preferably 15% or more.

[0058] Moldability (Melt Flow Rate) In one embodiment, in order to ensure good fluidity (moldability) in injection molding and the like, the melt flow rate of the resin composition (according to JIS K7210; 230°C, 2.16 kg load) is preferably 2 to 15 g / 10 min, more preferably 3 to 12 g / 10 min.

[0059] Method for Manufacturing the Resin Composition The thermoplastic polyester elastomer resin composition of this disclosure can be manufactured by conventionally known methods. In one embodiment, the manufacturing of the resin composition of this disclosure may be carried out in two steps: the manufacture of a thermoplastic polyester elastomer (base polymer) and the manufacture of a resin composition (compound) in which various additives are blended therewith.

[0060] The production of thermoplastic polyester elastomers (base polymers) Methods for producing the base polymer include melt polymerization, solution polymerization, and solid-phase polymerization. Examples of preferred methods include, but are not limited to, (i) a method in which a dicarboxylic acid diester, an excess amount of low molecular weight glycol, and a soft segment component are transesterified in the presence of a catalyst, followed by polycondensation; (ii) a method in which a dicarboxylic acid, an excess amount of glycol, and a soft segment component are esterified in the presence of a catalyst, followed by polycondensation; (iii) a method in which hard segment polyesters are synthesized in advance, and soft segment components are added and randomized by transesterification; (iv) a method in which hard segments and soft segments are linked with a chain linker; and (v) a method in which, when poly(ε-caprolactone) is used as the soft segment, ε-caprolactone monomers are added to the hard segment. Known catalysts such as phosphorus-based, imidazole-based, antimony-based, germanium-based, and titanium-based catalysts can be used. Various additives may be added during or after production as needed. In one embodiment, the method for adjusting the acid value of the resin composition is not particularly limited, and may include controlling polymerization conditions to reduce the acid value of the thermoplastic polyester elastomer itself to 25 eq / ton or less, or adding a thickening agent to a composition with an acid value exceeding 25 eq / ton to reduce it to 25 eq / ton or less.

[0061] Manufacturing of Resin Composition (Compounding) Next, the elastomer (base polymer) obtained above is mixed with a light-shielding agent and one or more additives selected from the group consisting of ultraviolet absorbers, light stabilizers, and thickeners, as well as other additives added as needed, and then melt-kneaded to obtain the final resin composition. In one embodiment, a thermoplastic polyester elastomer, a light-shielding agent, and additives such as ultraviolet absorbers are melt-kneaded and then cooled and solidified into an arbitrary shape such as pellets. In one embodiment, a conventional thermoplastic resin mixing device such as a single-screw or twin-screw extruder or a kneader-type heater can be used for melt-kneading. In one embodiment, it is desirable to uniformly disperse fillers such as light-shielding agents using a masterbatch or side feed. In one embodiment, after melt-kneading, the molten resin extruded from the die hole can be pelletized by a strand-cut method or a hot-cut method. In one embodiment, if the acid value of the base polymer is high, a thickener can be added in this compounding process and reacted to adjust the final acid value to 25 eq / ton or less.

[0062] The thermoplastic polyester elastomer resin composition disclosed herein has excellent weather resistance, and in a more preferred embodiment, it can improve hydrolysis resistance and eliminate manufacturing process problems such as mesh clogging and mold contamination during extrusion, thereby improving productivity. As a result, molded articles using the resin composition disclosed herein also have excellent weather resistance and are particularly suitable for applications requiring weather resistance.

[0063] Molded articles and their applications: Molded articles using the resin composition of this disclosure include a wide range of components and products used in various fields, such as automotive parts, electrical and electronic components, fibers, sheets, films, bottles, and containers. The resin composition of this disclosure may be used as part of the entire molded article or as a component of a part of it. The method for manufacturing a molded article using the resin composition of this disclosure is not particularly limited, and a molded article of a desired shape can be produced by various known methods. Examples include injection molding, blow molding, extrusion molding, foam molding, distorted molding, calendering, die molding, and various other molding methods, with injection molding being preferred.

[0064] This application claims the benefit of priority under Japanese Application No. 2024-158985, filed on 13 September 2024. The entire specification of Japanese Application No. 2024-158985 is incorporated herein by reference.

[0065] The present invention will be described in more detail below with reference to examples, but the present invention is not limited by the following examples, and it is certainly possible to implement it with appropriate modifications within the scope that is consistent with the spirit of the preceding and following descriptions, and all such modifications are included within the technical scope of the present invention.

[0066] Raw Materials Used The main raw materials used in this example are as follows: [Thermoplastic Polyester Elastomer (A)] (A-1) Thermoplastic polyester elastomer (A-1) was synthesized using dimethyl terephthalate, 1,4-butanediol, and poly(tetramethylene oxide) glycol with a number average molecular weight of 1000 as raw materials, with a soft segment component content of 40.9 parts by mass.

[0067] (A-2) Thermoplastic polyester elastomer (A-2) was synthesized using dimethyl terephthalate, 1,4-butanediol, and poly(tetramethylene oxide) glycol with a number average molecular weight of 1500 as raw materials, with a soft segment component content of 47.1 parts by mass.

[0068] (A-3) Thermoplastic polyester elastomer The thermoplastic polyester elastomer synthesized in (A-2) was made highly viscous by solid-phase polymerization to obtain thermoplastic polyester elastomer (A-3).

[0069] [UV absorbers / light stabilizers (B)] (B-1) UV absorber (UVA) Benzotriazole-based UV absorber (manufactured by Double Bond Chemical, CHISORB234, molecular weight 448, melting point 137-141°C) (B-2) Light stabilizer (HALS) Hindered amine-based light stabilizer (>N-H type) (manufactured by BASF, KIMASORB 944FDL, molecular weight 2000-3100, melting point 100-135°C) (B-3) Light stabilizer (HALS) Hindered amine-based light stabilizer (>NO-Alkyl type) (manufactured by Double Bond Chemical, CHISORB622SF, molecular weight 3100-4000, melting point 50-70°C)

[0070] [Light-blocking agent (C)] (C-1) Carbon black (manufactured by Nippon Pigment Co., Ltd., EX-3236, polyethylene-based masterbatch with 40% carbon black content) Note that the amount (parts by mass) of "(C-1) Carbon Black" in the table refers to the carbon black in the masterbatch. (C-2) Zinc oxide (manufactured by Sakai Chemical Industry Co., Ltd., zinc oxide type 2)

[0071] [Thickening agents] Liquid epoxy compounds: Bis-F type difunctional epoxy compounds Powdered epoxy compounds: Trifunctional epoxy compounds containing a triazine skeleton Carbodiimide compounds: Aliphatic polycarbodiimide compounds

[0072] [Catalyst] Phosphorus-based compound: Triphenylphosphine imidazole-based compound: Cureazole 2PZL-T (Shikoku Chemicals Co., Ltd. product)

[0073] Preparation of Resin Composition [Resin Composition] Each of the above raw materials was supplied to a twin-screw type melt mixer in the ratios shown in the table and mixed. The cylinder temperature during mixing was set to 240°C. The obtained pellet-shaped thermoplastic polyester elastomer resin composition was used as a sample for the following evaluation. The results are shown in the table.

[0074] Evaluation Method [Terminal Acid Value] The sample was dissolved in deuterated chloroform / deuterated hexafluoroisopropanol / triethylamine (88 / 10 / 2 [volume ratio]), and 1H-NMR analysis was performed using a BRUKER AVANCE NEO 600 NMR spectrometer. The resin composition was determined from the integral ratio and expressed in molar percent. In addition, the amount of carboxylic acid groups (eq / ton) was calculated based on the resin composition of the sample using the following formula: Amount of terminal carboxylic acid groups (eq / ton) = (Σ(P / 100) × Q) × 10 ６ / (Σ(R / 100×Z)) P = Content of terminal and carboxylic acid group-containing components (mol%) Q = Number of carboxylic acid groups in one molecule of terminal and carboxylic acid group-containing component R = Content of each component (mol%) Z = Molecular weight of each component

[0075] [Hydrolysis Resistance] Using an injection molding machine, the sample was molded into a 2 mm thick x 100 mm x 100 mm flat plate at a temperature setting of 230°C. Then, a dumbbell-shaped test piece (Type 3) was punched out perpendicular to the flat plate. The obtained test piece was immersed in boiling water at 100°C, and the time it took for the elongation retention rate at break to become 50% of the initial elongation was observed and used as an indicator of hydrolysis resistance. Tensile tests were performed using Tensilon, and the obtained test piece was stretched at a speed of 500 mm per minute. The tensile elongation at break (%) was defined as the time it took for the elongation retention rate at break to become 50%, with less than 600 hours being evaluated as × (fail) and 600 hours or more as ○ (pass).

[0076] [Machine Contamination] When molding a sample into a 2mm thick x 100mm x 100mm flat plate using an injection molding machine at a temperature setting of 230°C, the presence or absence of contamination on the mold was visually checked after 50 consecutive moldings. If no contamination was visible on the mold, it was evaluated as ○ (pass), and if contamination was visible, it was evaluated as × (fail).

[0077] [Extrusion Productivity] Using a twin-screw type melting and mixing machine, the cylinder temperature was set to 240°C, and the venting condition and / or mesh clogging before the die were visually checked when the raw material was melted and mixed to form pellets. ○ (Pass) was indicated when no venting or mesh clogging was visible, and × (Fail) was indicated when it was visible.

[0078] [Light transmittance] [Light transmittance ratio] The sample was fed into a single-screw extruder and extruded into a 50 μm thick film using a T-die at a set temperature of 230°C. The transmittance (%) of the obtained film at wavelengths of 380 nm and 600 nm was measured using a UV-Vis spectrophotometer (Shimadzu Corporation, SolidSpec-3700). The light transmittance ratio (380 nm / 600 nm) was calculated based on the measured values.

[0079] [Strength Retention Rate] [ΔE] Using an injection molding machine, the sample was molded into a flat plate (2 mm thick × 100 mm × 100 mm) at a temperature setting of 230°C. Then, it was divided into three perpendicular sections to cut out rectangular flat plates (2 mm thick × 100 mm × 33 mm). The cut test pieces were subjected to a 600-hr weather resistance test using a Super Xenon Weather Meter SX75 (manufactured by Suga Test Instruments Co., Ltd.), and then punched out into dumbbell-shaped test pieces (Type 3). Using the obtained dumbbell-shaped test pieces (Type 3), the tensile strength retention rate (strength retention rate) and color difference (ΔE) at break were determined. The weather resistance test conditions were: irradiation temperature (BPT) 63°C, humidity 50% RH, and irradiation intensity (300-400 nm) 180 W / m ２ There was no rainfall. Tensile strength at break was measured using Tensilon. The obtained test specimen was stretched at a speed of 500 mm per minute, and the stress at which the test specimen broke was defined as the tensile strength at break (MPa). Strength retention rate = (Tensile strength at break after weathering test / Tensile strength at break before weathering test) × 100% Color difference (ΔE) was measured using a precision spectrophotometer TC-1500SX (manufactured by Tokyo Denshoku), and the change in color before and after the weathering test was calculated using the test specimen before the weathering test as the reference. Excellent: ΔE is 20 or less Good: ΔE is greater than 20 and 30 or less Unacceptable: ΔE is greater than 30

[0080] [Bending Cycle Retention Rate] Using a Dematia bending crack tester (BE-102, manufactured by Tester Industries Co., Ltd.), the following specified test specimens were subjected to repeated bending at a rate of 300 cycles / min with the chuck spacing set to 70 mm and 30 mm in a 100°C atmosphere, and the number of cycles until fracture was investigated. Bending fatigue resistance was evaluated by the retention rate of bending fatigue cycles before and after the weathering test. Bending Cycle Retention Rate = (Bending fatigue cycles after weathering test / Bending fatigue cycles before weathering test) × 100% The test specimen used was an injection-molded product (width 20 mm, length 100 mm, thickness 3.6 mm, with a groove of R2.4 along the entire 20 mm width in the central part of the length direction) manufactured at a cylinder temperature of 230°C. The weathering test conditions were irradiation temperature (BPT) 63°C, humidity 50% RH, and irradiation intensity (300-400 nm) 180 W / m ２ There has been no rainfall.

[0081] [Overall Weather Resistance] Overall weather resistance was evaluated based on hydrolysis resistance, strength retention rate, ΔE, and flexural fatigue resistance from the above tests. Excellent: Hydrolysis resistance ○ rating, strength retention rate of 80% or more, ΔE of 20 or less, and flexural fatigue retention rate of 10% or more. Good: Hydrolysis resistance ○ rating, strength retention rate of 80% or more, ΔE of 20 or less, and flexural fatigue retention rate of 4% or more but less than 10%. Acceptable: Hydrolysis resistance × rating, but all other evaluations satisfy the above Excellent or Good criteria. Unacceptable: Strength retention rate less than 80%, ΔE greater than 30, and flexural fatigue retention rate less than 4%.

[0082]

[0083]

[0084] Examples 1 to 20 used carbon black as a light shielding agent and showed good weather resistance. In particular, Examples 6 to 20, which used carbon black in combination with a UV absorber / light stabilizer, received excellent evaluations for strength retention, flexural fatigue resistance, and ΔE, showing particularly outstanding weather resistance. On the other hand, in Example 4, where the carbon black content was excessive, mesh clogging occurred, and in Examples 3 and 4, flexibility decreased, and the number of flexural fatigue cycles fell below 1 million. Furthermore, in Examples 12 to 15, bleed-out occurred due to the excessive addition of UV absorber / light stabilizer, and mold fouling was observed. These examples showed excellent weather resistance but poor productivity.

[0085]

[0086] Examples 21 to 27 used zinc oxide as a light shielding agent, and all showed good weather resistance. In particular, Examples 24 to 27, which used zinc oxide in combination with an ultraviolet absorber / light stabilizer, received excellent evaluations for strength retention rate, ΔE, and flexural fatigue resistance after weathering tests, showing particularly excellent weather resistance. However, in Example 27, which had an excessive zinc oxide content, mesh clogging occurred during manufacturing, and hydrolysis resistance decreased due to an increase in acid value, thus failing to satisfy the preferred embodiment of this disclosure.

[0087]

[0088] Examples 28-30 and 33 were comparative examples that did not contain a light-shielding agent, and their light transmittance and light transmittance ratio did not satisfy the criteria of this disclosure, and discoloration and a decrease in strength retention were observed. Examples 31, 32, and 34 had excessive terminal acid value, resulting in poor hydrolysis resistance, and did not satisfy the preferred embodiments of this disclosure.

[0089] As described above, the thermoplastic polyester elastomer resin composition disclosed herein has excellent weather resistance and is therefore suitable for a wide range of products, from industrial goods such as automotive parts and electrical equipment to everyday goods such as films, sheets, bottles, and containers. In particular, it can be applied to a wide range of applications that are directly exposed to light, including outdoor use.

Claims

1. A thermoplastic polyester elastomer resin composition comprising a thermoplastic polyester elastomer and a light-shielding agent, further comprising one or more selected from the group consisting of an ultraviolet absorber, a light stabilizer, and a thickener, wherein the thermoplastic polyester elastomer does not contain either or both of the constituent units derived from 1,4-cyclohexanedimethanol and / or the constituent units derived from hydrogenated dimerol, and the light transmittance ratio (380 nm / 600 nm) at wavelengths of 380 nm and 600 nm in a single layer film of the thermoplastic polyester elastomer resin composition with a thickness of 50 μm is less than 0.80, and the light transmittance at 600 nm is 70% or less.

2. The thermoplastic polyester elastomer resin composition according to claim 1, wherein the acid value is 25 eq / ton or less.

3. The thermoplastic polyester elastomer resin composition according to claim 1, wherein the light-shielding agent is carbon black.

4. The thermoplastic polyester elastomer resin composition according to claim 1, wherein the light-shielding agent is zinc oxide.

5. The thermoplastic polyester elastomer resin composition according to claim 1, comprising less than 3 parts by mass of the ultraviolet absorber and the light stabilizer in total with respect to 100 parts by mass of the thermoplastic polyester elastomer.

6. The thermoplastic polyester elastomer resin composition according to claim 3, comprising 0.1 to 20 parts by mass of carbon black per 100 parts by mass of the thermoplastic polyester elastomer.

7. The thermoplastic polyester elastomer resin composition according to claim 4, comprising 0.1 to 15 parts by mass of zinc oxide per 100 parts by mass of the thermoplastic polyester elastomer.

8. The thermoplastic polyester elastomer resin composition according to claim 1, wherein the retention rate of tensile strength at break after a 600-hr weathering test is 80% or more.

9. The thermoplastic polyester elastomer resin composition according to claim 1, wherein the retention rate of bending fatigue cycles after a 600-hr weathering test is 4% or more.

10. A molded article comprising the thermoplastic polyester elastomer resin composition according to any one of claims 1 to 9.

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