Polyester resin composition

Abstract

The present disclosure provides a polyester resin composition having excellent resistance to heat aging. Specifically, this polyester resin composition comprises a polyester resin (A) and a polyester resin (B), wherein the polyester resin (A) comprises one or more dicarboxylic acid components containing terephthalic acid as a main component and one or more diol components containing 1,4-butanediol as a main component and the polyester resin (B) comprises one or more dicarboxylic acid components containing 2,5-furandicarboxylic acid as a main component and one or more diol components containing ethylene glycol as a main component. The content of the polyester resin (A) is 50-95 parts by mass and the content of the polyester resin (B) is 5-50 parts by mass, per 100 parts by mass of the sum of the polyester resin (A) and the polyester resin (B).

Description

Polyester resin composition

[0001] The present disclosure relates to a polyester resin composition.

[0002] BACKGROUND ART Polyester resins have excellent injection moldability, mechanical properties, heat resistance, electrical properties, chemical resistance, and the like, and are therefore widely used in various parts such as automobile parts, machine parts, electric and electronic parts, and communication parts.

[0003] However, polyester resins are known to be prone to a decrease in mechanical strength due to thermal oxidative degradation at high temperatures, and therefore, in addition to the balance of general chemical and physical properties, they are also prone to a decrease in physical properties (thermal aging) when stored at high temperatures for long periods. Therefore, there is a demand for improved resistance to heat aging.

[0004] As a method for improving the thermal stability of polyester resins, for example, Patent Document 1 discloses a thermoplastic resin composition in which a polyhydric alcohol, a reinforcing agent, and a polymer toughening agent are added to a thermoplastic resin.

[0005] Furthermore, Patent Document 2 discloses a polyester resin composition obtained by blending a thermoplastic polyester resin with an epoxy compound, a hydroxyl group-containing resin, and a thermoplastic elastomer resin.

[0006] Japanese Patent Publication No. 2011-529991 Japanese Patent Publication No. 2020-84133

[0007] However, the thermoplastic resin composition disclosed in Patent Document 1 has problems in that it is significantly inferior in heat aging resistance and mechanical properties, and in that the content of hydroxyl group-containing compounds in a molded article decreases due to bleeding out of the polyhydric alcohol, resulting in poor heat aging resistance.

[0008] The polyester resin composition disclosed in Patent Document 2 has a problem in that the various components may be involved and cause complex reactions.

[0009] The resin compositions disclosed in Patent Documents 1 and 2 have heat aging resistance, but are not sufficient to meet recent demands for materials. For example, with regard to the engine compartment of an automobile, the environmental temperature in the engine compartment has risen in recent years due to increases in engine power and higher density of parts, and therefore further improvement in heat aging resistance is required.

[0010] An object of the present disclosure is to provide a polyester resin composition having excellent heat aging resistance.

[0011] As a result of extensive research to achieve the above object, the inventors discovered that a polyester resin composition containing two types of polyester resins containing specific components in a predetermined ratio can solve the above problem, and have thus completed the present disclosure.

[0012] The present disclosure encompasses, for example, the following subject matter: A polyester resin composition comprising a polyester resin (A) and a polyester resin (B), wherein the polyester resin (A) comprises a dicarboxylic acid component containing terephthalic acid as a main component and a diol component containing 1,4-butanediol as a main component, and the polyester resin (B) comprises a dicarboxylic acid component containing 2,5-furandicarboxylic acid as a main component and a diol component containing ethylene glycol as a main component, and the content of the polyester resin (A) is 50 to 95 parts by mass and the content of the polyester resin (B) is 5 to 50 parts by mass per 100 parts by mass of the total of the polyester resins (A) and (B).

[0013] The polyester resin composition of the present disclosure has excellent heat aging resistance.

[0014] Preferred embodiments of the present disclosure will be described in detail below. The following description of the components may be based on representative embodiments and specific examples, but the present disclosure is not limited to such embodiments.

[0015] In the present disclosure, the expressions "contain" and "comprise" also encompass the concepts of "consisting essentially of" and "consisting of."

[0016] In the numerical ranges described in stages in this disclosure, the upper or lower limit of a certain numerical range can be arbitrarily combined with the upper or lower limit of another numerical range. Furthermore, in the numerical ranges described in this disclosure, the upper or lower limit of the numerical range may be replaced with a value shown in an example or a value that can be unambiguously derived from the example. Furthermore, in this disclosure, a numerical value connected with "to" means a numerical range that includes the numbers before and after "to" as the upper and lower limits.

[0017] In the present disclosure, the term "major component" means a component that is typically present in an amount of more than 50 mol %.

[0018] In the present disclosure, "A and / or B" means "one of A and B" or "both A and B," and specifically means "A," "B," or "A and B."

[0019] In this disclosure, room temperature means a temperature within the range of 20°C to 25°C.

[0020] <Polyester Resin Composition> The polyester resin composition of the present disclosure has the following configurations (I) to (IV). (I) Contains polyester resin (A) and polyester resin (B). (II) The polyester resin (A) contains a dicarboxylic acid component containing terephthalic acid as a main component and a diol component containing 1,4-butanediol as a main component. (III) The polyester resin (B) is composed of a dicarboxylic acid component containing 2,5-furandicarboxylic acid as a main component and a diol component containing ethylene glycol as a main component. (IV) The content of polyester resin (A) is 50 to 95 parts by mass and the content of polyester resin (B) is 5 to 50 parts by mass per 100 parts by mass of the total of polyester resin (A) and polyester resin (B).

[0021] The polyester resin composition of the present disclosure has the above-described components (I) to (IV) and therefore has the property of excellent heat aging resistance.

[0022] Regarding the above-mentioned configuration (IV), when (i) the content of polyester resin (A) is less than 50 parts by mass and the content of polyester resin (B) is more than 50 parts by mass, and when (ii) the content of polyester resin (A) is more than 95 parts by mass and the content of polyester resin (B) is less than 5 parts by mass, relative to 100 parts by mass in total of polyester resin (A) and polyester resin (B), the heat aging resistance of the polyester resin composition is significantly reduced.

[0023] <Polyester Resin (A)> In one embodiment of the present disclosure, in the polyester resin (A), the content of terephthalic acid in the dicarboxylic acid component is usually more than 50 mol%, preferably 70 mol% or more, more preferably 80 mol% or more, still more preferably 90 mol% or more, even more preferably 95 mol% or more, still more preferably 99 mol% or more, particularly preferably 99.5 mol% or more, and most preferably 100 mol%, from the viewpoint of further improving the mechanical properties and heat resistance.

[0024] In one embodiment of the present disclosure, in the polyester resin (A), the content of 1,4-butanediol in the diol component is usually more than 50 mol%, preferably 70 mol% or more, more preferably 80 mol% or more, even more preferably 90 mol% or more, still more preferably 95 mol% or more, still more preferably 99 mol% or more, particularly preferably 99.5 mol% or more, and most preferably 100 mol% from the viewpoint of further improving mechanical properties and heat resistance.

[0025] In one embodiment of the present disclosure, the total content of the dicarboxylic acid component containing terephthalic acid as a main component and the diol component containing 1,4-butanediol as a main component in the polyester resin (A) is usually 75 mol% or more, preferably 80 mol% or more, more preferably 85 mol% or more, even more preferably 90 mol% or more, still more preferably 95 mol% or more, still more preferably 99 mol% or more, particularly preferably 99.5 mol% or more, and most preferably 100 mol%.

[0026] In one embodiment of the present disclosure, the dicarboxylic acid component in the polyester resin (A) may include, in addition to terephthalic acid, aromatic dicarboxylic acids such as isophthalic acid, phthalic acid, naphthalenedicarboxylic acid, 4,4'-dicarboxybiphenyl, and 5-sodium sulfoisophthalic acid; alicyclic dicarboxylic acids such as 1,4-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid, 2,5-norbornenedicarboxylic acid, and tetrahydrophthalic acid; and aliphatic dicarboxylic acids such as oxalic acid, malonic acid, succinic acid, adipic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, octadecanedioic acid, fumaric acid, maleic acid, itaconic acid, mesaconic acid, citraconic acid, and dimer acid. These dicarboxylic acid components other than terephthalic acid may be used alone or in combination of two or more.

[0027] The content of the dicarboxylic acid component other than the terephthalic acid in the polyester resin (A) is usually less than 50 mol%, preferably 30 mol% or less, more preferably 20 mol% or less, even more preferably 10 mol% or less, still more preferably 5 mol% or less, still more preferably 1 mol% or less, particularly preferably 0.5 mol% or less, and most preferably 0 mol%.

[0028] In one embodiment of the present disclosure, the diol component in the polyester resin (A) can include, in addition to 1,4-butanediol, for example, ethylene glycol, trimethylene glycol, 1,3-propylene glycol, tetramethylene glycol, neopentyl glycol, hexamethylene glycol, diethylene glycol, polyethylene glycol, cyclohexanedimethanol, 2,2-bis(2'-hydroxyethoxyphenyl)propane, etc. These diol components other than 1,4-butanediol can be used alone or in combination of two or more.

[0029] The content of the diol component other than 1,4-butanediol in the polyester resin (A) is usually less than 50 mol%, preferably 30 mol% or less, more preferably 20 mol% or less, even more preferably 10 mol% or less, still more preferably 5 mol% or less, still more preferably 1 mol% or less, particularly preferably 0.5 mol% or less, and most preferably 0 mol%.

[0030] In one embodiment of the present disclosure, the polyester resin (A) of the present disclosure is particularly preferably a polybutylene terephthalate resin (a homopolymer composed of terephthalic acid and 1,4-butanediol). In other words, the polyester resin (A) of the present disclosure is particularly preferably a homopolybutylene terephthalate resin. The homopolybutylene terephthalate resin typically contains 0 mol% of a copolymerization component. In another embodiment of the present disclosure, the polyester resin (A) of the present disclosure is particularly preferably a polybutylene terephthalate resin obtained by polycondensation of terephthalic acid and 1,4-butanediol.

[0031] In one embodiment of the present disclosure, the intrinsic viscosity of the polyester resin (A) is preferably 0.5 to 1.8 dl / g, more preferably 0.6 to 1.5 dl / g, and even more preferably 0.7 to 1.4 dl / g, from the viewpoint of further increasing durability and further improving processability in injection molding and the like.

[0032] Since hydrogen ions dissociated from the terminal carboxyl groups play a catalytic role in the hydrolysis reaction of polyesters, the hydrolysis reaction tends to accelerate as the amount of terminal carboxyl groups increases. Therefore, it is preferable that the amount of terminal carboxyl groups (acid value) of the polyester resin (A) is small. In one embodiment of the present disclosure, the amount of terminal carboxyl groups (acid value) of the polyester resin (A) is preferably 50 eq / ton or less, more preferably 40 eq / ton or less, and even more preferably 30 eq / ton or less.

[0033] The amount of terminal carboxyl groups (acid value) of the polyester resin (A) can be measured, for example, by dissolving a predetermined amount of the polyester resin (A) in benzyl alcohol and titrating the solution with a 0.01 mol / L benzyl alcohol solution of sodium hydroxide. As an indicator, for example, a phenolphthalein solution can be used.

[0034] <Polyester Resin (B)> In one embodiment of the present disclosure, in the polyester resin (B), the content of 2,5-furandicarboxylic acid in the dicarboxylic acid component is usually more than 50 mol%, preferably 70 mol% or more, more preferably 80 mol% or more, even more preferably 90 mol% or more, still more preferably 95 mol% or more, still more preferably 99 mol% or more, particularly preferably 99.5 mol% or more, and most preferably 100 mol%, from the viewpoint of further improving heat aging resistance.

[0035] In one embodiment of the present disclosure, in the polyester resin (B), the content of ethylene glycol in the diol component is usually more than 50 mol%, preferably 70 mol% or more, more preferably 80 mol% or more, even more preferably 90 mol% or more, still more preferably 95 mol% or more, still more preferably 99 mol% or more, particularly preferably 99.5 mol% or more, and most preferably 100 mol% from the viewpoint of further improving heat aging resistance.

[0036] In one embodiment of the present disclosure, the polyester resin (B) is particularly preferably a polyethylene furanoate resin (a homopolymer of 2,5-furandicarboxylic acid and ethylene glycol). In other words, the polyester resin (B) is particularly preferably a homopolyethylene furanoate resin. The homopolyethylene furanoate resin typically contains 0 mol % of a copolymerization component.

[0037] In another embodiment of the present disclosure, the polyester resin (B) is preferably a copolymerized polyethylene furanoate resin. The copolymerized polyethylene furanoate resin is a polyethylene furanoate resin copolymerized with a dicarboxylic acid component other than 2,5-furandicarboxylic acid and / or a diol component other than ethylene glycol.

[0038] In another embodiment of the present disclosure, when the polyester resin (B) is a copolymerized polyethylene furanoate resin, the content of polyethylene furanoate structural units in the total (100 mol%) of all structural units of the copolymerized polyethylene furanoate resin is preferably more than 50 mol%, more preferably 70 mol% or more, even more preferably 80 mol% or more, still more preferably 90 mol% or more, still more preferably 95 mol% or more, still more preferably 99 mol% or more, particularly preferably 99.5 mol% or more, and most preferably 99.9 mol% or more.

[0039] In another embodiment of the present disclosure, when the polyester resin (B) is a copolymerized polyethylene furanoate resin, the total amount of copolymerization of dicarboxylic acid components other than 2,5-furandicarboxylic acid and diol components other than ethylene glycol in the total (100 mol%) of all structural units of the copolymerized polyethylene furanoate resin is usually less than 50 mol%, preferably 30 mol% or less, more preferably 20 mol% or less, even more preferably 10 mol% or less, still more preferably 5 mol% or less, still more preferably 1 mol% or less, particularly preferably 0.5 mol% or less, and most preferably 0.1 mol% or less.

[0040] In another embodiment of the present disclosure, when the polyester resin (B) is a copolymerized polyethylene furanoate resin, examples of the dicarboxylic acid component other than 2,5-furandicarboxylic acid include aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, phthalic acid, naphthalenedicarboxylic acid, 4,4'-dicarboxybiphenyl, and 5-sodium sulfoisophthalic acid; alicyclic dicarboxylic acids such as 1,4-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid, 2,5-norbornenedicarboxylic acid, and tetrahydrophthalic acid; and aliphatic dicarboxylic acids such as oxalic acid, malonic acid, succinic acid, adipic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, octadecanedioic acid, fumaric acid, maleic acid, itaconic acid, mesaconic acid, citraconic acid, and dimer acid. These dicarboxylic acid components other than 2,5-furandicarboxylic acid can be used alone or in combination of two or more.

[0041] In another embodiment of the present disclosure, when the polyester resin (B) is a copolymerized polyethylene furanoate resin, examples of the diol component other than ethylene glycol include aliphatic glycols such as 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2-methyl-1,3-propanediol, 2-amino-2-ethyl-1,3-propanediol, 2-amino-2-methyl-1,3-propanediol, 1,10-decanediol, dimethyloltricyclodecane, diethylene glycol, and triethylene glycol; alicyclic glycols such as bisphenol A, bisphenol S, bisphenol C, bisphenol Z, bisphenol AP, ethylene oxide adducts or propylene oxide adducts of 4,4'-biphenol, 1,2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, and 1,4-cyclohexanedimethanol; polyethylene glycol, polypropylene glycol, and the like. These diol components other than ethylene glycol may be used either alone or in combination of two or more.

[0042] In one embodiment of the present disclosure, the intrinsic viscosity of the polyester resin (B) is preferably 0.3 to 1.8 dl / g, more preferably 0.4 to 1.5 dl / g, and even more preferably 0.5 to 1.4 dl / g, from the viewpoint of further increasing durability and further improving processability in injection molding and the like.

[0043] Since hydrogen ions dissociated from the terminal carboxyl groups play a catalytic role in the hydrolysis reaction of polyester, the hydrolysis reaction tends to accelerate as the amount of terminal carboxyl groups increases. Therefore, it is preferable that the amount of terminal carboxyl groups (acid value) of polyester resin (B) is small. In one embodiment of the present disclosure, the amount of terminal carboxyl groups (acid value) of polyester resin (B) is preferably 60 eq / ton or less, more preferably 50 eq / ton or less, and even more preferably 40 eq / ton or less.

[0044] The amount of terminal carboxyl groups (acid value) of the polyester resin (B) can be measured, for example, by dissolving a predetermined amount of the polyester resin (B) in benzyl alcohol and titrating the solution with a 0.01 mol / L benzyl alcohol solution of sodium hydroxide. As an indicator, for example, a phenolphthalein solution can be used.

[0045] Examples of the polymerization method for the polyester resin (A) and the polyester resin (B) include a transesterification method using a dicarboxylic acid component and a diol component as starting materials, a direct esterification method using a dicarboxylic acid component and a diol component as starting materials, etc. Examples of the polymerization catalyst that can be used include an Sb compound, a Ge compound, a Ti compound, an Al compound, etc.

[0046] In one embodiment of the present disclosure, relative to 100 parts by mass in total of the polyester resin (A) and the polyester resin (B), the content of the polyester resin (A) is preferably 55 to 93 parts by mass and the content of the polyester resin (B) is 7 to 45 parts by mass, more preferably the content of the polyester resin (A) is 60 to 92 parts by mass and the content of the polyester resin (B) is 8 to 40 parts by mass, and even more preferably the content of the polyester resin (A) is 65 to 91 parts by mass and the content of the polyester resin (B) is 9 to 35 parts by mass.

[0047] Although the reason why the polyester resin composition of the present disclosure, which contains polyester resin (A) and polyester resin (B), exhibits excellent heat aging resistance, is not clear, it is believed that the low molecular mobility and high polarity, etc., derived from the molecular skeleton of polyester resin (B), have an effect. This leads to low oxygen permeability, i.e., high gas barrier properties, which are believed to delay oxidative degradation of the resin in a high-temperature environment, thereby resulting in excellent heat aging resistance.

[0048] In one embodiment of the present disclosure, the total content ratio of the polyester resin (A) and the polyester resin (B) relative to the total mass of the polyester resin composition is preferably 60% by mass or more, 65% by mass or more, 70% by mass or more, 75% by mass or more, 80% by mass or more, 85% by mass or more, 90% by mass or more, 95% by mass or more, and 99% by mass or more, in that order.

[0049] In another embodiment of the present disclosure, the content ratio of polyethylene terephthalate relative to the total mass of the polyester resin composition is preferably less than 10% by mass, 5% by mass or less, 3% by mass or less, 1% by mass or less, 0.5% by mass or less, and 0.1% by mass or less, in that order.

[0050] In another embodiment of the present disclosure, the content ratio of polyphenylene ether relative to the total mass of the polyester resin composition is preferably less than 10% by mass, 5% by mass or less, 3% by mass or less, 1% by mass or less, 0.5% by mass or less, and 0.1% by mass or less, in that order.

[0051] In another embodiment of the present disclosure, the content ratio of polyphenylene sulfide relative to the total mass of the polyester resin composition is preferably less than 10% by mass, 5% by mass or less, 3% by mass or less, 1% by mass or less, 0.5% by mass or less, and 0.1% by mass or less, in that order.

[0052] In another embodiment of the present disclosure, the total content ratio of polyethylene terephthalate, polyphenylene ether, and polyphenylene sulfide relative to the total mass of the polyester resin composition is preferably less than 10% by mass, 5% by mass or less, 3% by mass or less, 1% by mass or less, 0.5% by mass or less, and 0.1% by mass or less, in that order.

[0053] In another embodiment of the present disclosure, it is particularly preferred that the polyester resin composition does not contain polyethylene terephthalate. In another embodiment of the present disclosure, it is particularly preferred that the content of polyethylene terephthalate relative to the total mass of the polyester resin composition is 0 mass%.

[0054] In another embodiment of the present disclosure, it is particularly preferred that the polyester resin composition does not contain polyphenylene ether. In another embodiment of the present disclosure, it is particularly preferred that the content of polyphenylene ether relative to the total mass of the polyester resin composition is 0 mass%.

[0055] In another embodiment of the present disclosure, it is particularly preferred that the polyester resin composition does not contain polyphenylene sulfide. In another embodiment of the present disclosure, it is particularly preferred that the content of polyphenylene sulfide relative to the total mass of the polyester resin composition is 0 mass%.

[0056] In another embodiment of the present disclosure, it is particularly preferred that the polyester resin composition does not contain polyethylene terephthalate, polyphenylene ether, or polyphenylene sulfide. In another embodiment of the present disclosure, it is particularly preferred that the total content of polyethylene terephthalate, polyphenylene ether, and polyphenylene sulfide relative to the total mass of the polyester resin composition is 0 mass%.

[0057] <Glass Fiber (C)> The polyester resin composition of the present disclosure may contain glass fiber (C). Examples of the glass fiber (C) include milled fiber glass fiber and chopped strand glass fiber. These glass fibers may be used alone or in combination of two or more. Among these glass fibers, chopped strand glass fiber is preferred from the viewpoint of further improving mechanical strength and heat resistance.

[0058] The cut length of the middle fiber glass fiber is usually 35 to 80 μm, and the length of the chopped strand glass fiber is usually 1 to 20 mm.

[0059] In one embodiment of the present disclosure, the cross-sectional shape of the glass fiber (C) is usually circular or non-circular. In one embodiment of the present disclosure, the glass fiber (C) having a circular cross-sectional shape usually has a number average fiber diameter of 4 to 20 μm and a number average fiber length of 3 to 6 mm. In one embodiment of the present disclosure, the glass fiber (C) having a non-circular cross-sectional shape may, for example, be a glass fiber having a substantially elliptical, substantially oval, or substantially cocoon-shaped cross section perpendicular to the longitudinal direction of the fiber length. In one embodiment of the present disclosure, the glass fiber (C) having a non-circular cross-sectional shape preferably has a flatness of 1.5 to 8. In the present disclosure, the flatness is the ratio of the major axis to the minor axis, where the length of the long side of the rectangle is the major axis and the length of the short side is the minor axis, assuming a rectangle with the smallest area circumscribing the cross section perpendicular to the longitudinal direction of the glass fiber. In one embodiment of the present disclosure, a glass fiber (C) having a minor axis of 1 to 20 μm and a major axis of 2 to 100 μm can be used.

[0060] In one embodiment of the present disclosure, the cross-sectional shape of the glass fiber (C) is preferably circular.

[0061] In one embodiment of the present disclosure, the number average fiber length of the glass fiber (C) is preferably 1 mm to 20 mm, more preferably 1.5 mm to 15 mm, and even more preferably 2 mm to 10 mm, from the viewpoint of further improving mechanical strength and heat resistance.

[0062] In one embodiment of the present disclosure, the number average fiber diameter of the glass fiber (C) is preferably 4 μm to 20 μm, more preferably 6 μm to 15 μm, and even more preferably 8 μm to 12 μm, from the viewpoint of further improving mechanical strength and heat resistance.

[0063] A wide variety of known commercially available products can be used as the glass fiber (C). Examples of commercially available glass fiber (C) include "ECS03T-120H" and "ECS03T-127H" manufactured by Nippon Electric Glass Co., Ltd., and "CS3J941S" manufactured by Nitto Boseki Co., Ltd. These commercially available products can be used alone or in combination of two or more.

[0064] In one embodiment of the present disclosure, the content of the glass fiber (C) in the polyester resin composition of the present disclosure is preferably 50 parts by mass or less, and more preferably 45 parts by mass or less, relative to 100 parts by mass of the total of the polyester resin (A) and the polyester resin (B), from the viewpoint of further improving the mechanical strength and heat resistance.

[0065] In another embodiment of the present disclosure, the total content ratio of the polyester resin (A), the polyester resin (B), and the glass fiber (C) relative to the total mass of the polyester resin composition of the present disclosure is preferably 80% by mass or more, 85% by mass or more, 90% by mass or more, 95% by mass or more, 97.5% by mass or more, 99% by mass or more, 99.5% by mass or more, and 99.9% by mass or more, in that order.

[0066] In one embodiment of the present disclosure, a molded article obtained from the polyester resin composition of the present disclosure has, after heat treatment at 200°C for 1000 hours, a flexural strength retention rate [(flexural strength after heat treatment at 200°C for 1000 hours / flexural strength before heat treatment at 200°C for 1000 hours) x 100] measured in accordance with ISO 178 of preferably 55% or more, more preferably 56% or more, and even more preferably 57% or more. A specific method for measuring the flexural strength retention rate will be described in the examples below.

[0067] In one embodiment of the present disclosure, the polyester resin composition of the present disclosure has a temperature difference between the melting point and the crystallization temperature during cooling, as measured by a differential scanning calorimeter (DSC), of preferably 30° C. or more and 45° C. or less, more preferably 31° C. or more and 40° C. or less. A specific method for measuring the temperature difference between the melting point and the crystallization temperature during cooling will be described in the examples described later.

[0068] <Optional Additives> The polyester resin composition of the present disclosure may contain additives to the extent that the effects of the present disclosure are not affected. Examples of additives include antioxidants, heat stabilizers, UV absorbers, antistatic agents, colorants, lubricants, plasticizers, mold release agents, crystallization accelerators, crystal nucleating agents, and epoxy compounds. Examples of colorants include dyes and pigments. The additives may be used alone or in combination of two or more.

[0069] <Molded Article> A wide variety of known methods can be used as a molding method for the molded article obtained by molding the resin composition of the present disclosure. Examples of molding methods include injection molding, extrusion molding, blow molding, etc. Among these molding methods, injection molding is preferred from the viewpoint of versatility.

[0070] <Method for producing polyester resin composition> The polyester resin composition of the present disclosure can be produced, for example, by blending the polyester resin (A) and the polyester resin (B), and, if necessary, the glass fiber (C) and additives, in any blending order so as to obtain predetermined blending amounts, and melt-kneading them.

[0071] As a method for melt-kneading, a wide variety of known single-screw extruders, twin-screw extruders, kneaders, Banbury mixers, rolls, etc., which are commonly used in this field, can be used. Among these, it is preferable to use a twin-screw extruder for melt-kneading.

[0072] The present disclosure provides the following subject matter: Item 1. A polyester resin composition comprising a polyester resin (A) and a polyester resin (B), wherein the polyester resin (A) comprises a dicarboxylic acid component containing terephthalic acid as a main component and a diol component containing 1,4-butanediol as a main component, and the polyester resin (B) comprises a dicarboxylic acid component containing 2,5-furandicarboxylic acid as a main component and a diol component containing ethylene glycol as a main component, and the content of the polyester resin (A) is 50 to 95 parts by mass and the content of the polyester resin (B) is 5 to 50 parts by mass per 100 parts by mass of the total of the polyester resins (A) and (B). Item 1. The polyester resin composition according to Item 1, wherein the content of terephthalic acid in the dicarboxylic acid component of the polyester resin (A) is usually more than 50 mol%, preferably 70 mol% or more, more preferably 80 mol% or more, even more preferably 90 mol% or more, even more preferably 95 mol% or more, still more preferably 99 mol% or more, particularly preferably 99.5 mol% or more, and most preferably 100 mol%. Item 3. The polyester resin composition according to Item 1 or 2, wherein the content of 1,4-butanediol in the diol component of the polyester resin (A) is usually more than 50 mol%, preferably 70 mol% or more, more preferably 80 mol% or more, even more preferably 90 mol% or more, even more preferably 95 mol% or more, still more preferably 99 mol% or more, particularly preferably 99.5 mol% or more, and most preferably 100 mol%. Item 4. Item 4. The polyester resin composition according to any one of Items 1 to 3, wherein the total content of the dicarboxylic acid component containing terephthalic acid as a main component and the diol component containing 1,4-butanediol as a main component in the polyester resin (A) is usually 75 mol% or more, preferably 80 mol% or more, more preferably 85 mol% or more, even more preferably 90 mol% or more, even more preferably 95 mol% or more, still more preferably 99 mol% or more, particularly preferably 99.5 mol% or more, and most preferably 100 mol%.Item 5. The polyester resin composition according to any one of Items 1 to 4, wherein the polyester resin (A) is a polybutylene terephthalate resin. Item 6. The polyester resin composition according to any one of Items 1 to 5, wherein the content of 2,5-furandicarboxylic acid in the dicarboxylic acid component of the polyester resin (B) is usually more than 50 mol%, preferably 70 mol% or more, more preferably 80 mol% or more, even more preferably 90 mol% or more, even more preferably 95 mol% or more, still more preferably 99 mol% or more, particularly preferably 99.5 mol% or more, and most preferably 100 mol%. Item 7. The polyester resin composition according to any one of Items 1 to 6, wherein the content of ethylene glycol in the diol component of the polyester resin (B) is usually more than 50 mol%, preferably 70 mol% or more, more preferably 80 mol% or more, even more preferably 90 mol% or more, even more preferably 95 mol% or more, still more preferably 99 mol% or more, particularly preferably 99.5 mol% or more, and most preferably 100 mol%. Item 8. Item 9. The polyester resin composition according to any one of Items 1 to 7, wherein the polyester resin (B) is a polyethylene furanoate resin. Item 10. The polyester resin composition according to any one of Items 1 to 8, wherein, relative to 100 parts by mass of the total of the polyester resin (A) and the polyester resin (B), the content of the polyester resin (A) is preferably 55 to 93 parts by mass and the content of the polyester resin (B) is 7 to 45 parts by mass, more preferably the content of the polyester resin (A) is 60 to 92 parts by mass and the content of the polyester resin (B) is 8 to 40 parts by mass, and even more preferably the content of the polyester resin (A) is 65 to 91 parts by mass and the content of the polyester resin (B) is 9 to 35 parts by mass. Item 10. Item 10. The polyester resin composition according to any one of items 1 to 9, wherein the total content of the polyester resin (A) and the polyester resin (B) is, relative to the total mass of the polyester resin composition, 60% by mass or more, 65% by mass or more, 70% by mass or more, 75% by mass or more, 80% by mass or more, 85% by mass or more, 90% by mass or more, 95% by mass or more, and 99% by mass or more.Item 11. The polyester resin composition according to any one of Items 1 to 10, wherein the content of the glass fiber (C) is 50 parts by mass or less per 100 parts by mass of the total of the polyester resin (A) and the polyester resin (B). Item 12. The polyester resin composition according to any one of Items 1 to 10, wherein the content of the glass fiber (C) is 45 parts by mass or less per 100 parts by mass of the total of the polyester resin (A) and the polyester resin (B). Item 13. The polyester resin composition according to Item 11 or 12, wherein the glass fiber (C) is preferably a milled fiber glass fiber or a chopped strand glass fiber, more preferably a chopped strand glass fiber. Item 14. The polyester resin composition according to any one of Items 11 to 13, wherein the number average fiber length of the glass fiber (C) is preferably 1 mm to 20 mm, more preferably 1.5 mm to 15 mm, and even more preferably 2 mm to 10 mm. Item 15. Item 16. The polyester resin composition according to any one of Items 11 to 15, wherein the total content of the polyester resin (A), the polyester resin (B), and the glass fiber (C) is preferably 80% by mass or more, 85% by mass or more, 90% by mass or more, 95% by mass or more, 97.5% by mass or more, 99% by mass or more, 99.5% by mass or more, and 99.9% by mass or more, relative to the total mass of the polyester resin composition. Item 17. Item 17. A molded article obtained from the polyester resin composition has a flexural strength retention measured in accordance with ISO 178 after heat treatment at 200°C for 1000 hours [(flexural strength after heat treatment / flexural strength before heat treatment) x 100] of 55% or more. The polyester resin composition according to any one of items 1 to 16.Item 18. The polyester resin composition according to any one of Items 1 to 16, wherein a molded article obtained from the polyester resin composition has, after heat treatment at 200°C for 1000 hours, a flexural strength retention rate [(flexural strength after heat treatment at 200°C for 1000 hours / flexural strength before heat treatment at 200°C for 1000 hours) x 100] measured in accordance with ISO 178 of preferably 55% or more, more preferably 56% or more, and even more preferably 57% or more. Item 19. The polyester resin composition according to any one of Items 1 to 18, wherein the temperature difference between the melting point and the crystallization temperature during cooling measured by a differential scanning calorimeter (DSC) is preferably 30°C or more and 45°C or less, more preferably 31°C or more and 40°C or less.

[0073] The present disclosure will be described in more detail below based on examples, but the present disclosure is not limited to the aspects of these examples. Measurement methods and evaluation methods in the examples and comparative examples are as follows. In the following examples and comparative examples, "room temperature" means a temperature within the range of 20°C to 25°C.

[0074] (Intrinsic Viscosity of Polyester Resin) 0.1 g of a sample was dissolved in 25 ml of a mixed solvent of phenol / tetrachloroethane (mass ratio = 6 / 4), and then the intrinsic viscosity (unit: dl / g) was measured at 30°C using an Ubbelohde viscometer.

[0075] (Mold Releasability) Pellets of the resin compositions obtained in the examples and comparative examples were molded into multipurpose test specimens (A-type, dumbbell-shaped tensile test specimens) in accordance with ISO 3167:93 using an injection molding machine ("J100ADS" manufactured by The Japan Steel Works, Ltd.). The width of the multipurpose test specimen was 10 mm and the thickness was 4 mm. Specific injection molding conditions were set as follows: injection speed = 60 mm / sec, dwell pressure = 60 MPa, injection and dwell time: 10 seconds, cooling time: 12 seconds, mold temperature: 90 ° C, cylinder temperature: 260 ° C. The mold releasability was evaluated based on whether the molded article could be released from the movable side of the mold during ejection (whether or not the molded article stuck to the mold).

[0076] (Heat Aging Resistance) As an index of heat aging resistance, molded articles were prepared from pellets of the resin compositions obtained in the examples and comparative examples, and the retention rate (%) of bending strength after heat treatment at 200°C for 1000 hours was measured.

[0077] Specifically, pellets of the resin compositions obtained in the examples and comparative examples were molded into multipurpose test specimens (A-type, dumbbell-shaped tensile test specimens) in accordance with ISO 3167:93 using an injection molding machine ("J100ADS" manufactured by Japan Steel Works, Ltd.). The width of the multipurpose test specimen was 10 mm and the thickness was 4 mm. Specific injection molding conditions were set as follows: injection speed = 60 mm / sec, dwell pressure = 60 MPa, injection and dwell time: 10 seconds, cooling time: 12 seconds, mold temperature: 90 ° C, cylinder temperature: 260 ° C. Next, according to the procedure detailed in ISO 2578, the molded product was heat-treated in a recirculating air oven ("Hot Air Circulation Dryer NH-401S" manufactured by Nagano Scientific Machinery Works, Ltd.) at 200 ° C for 1,000 hours, and then allowed to cool at room temperature for at least 24 hours. After cooling, the flexural strength (MPa) of the molded article was measured at room temperature, with a support distance of 64 mm, and at a speed of 2 mm / min in accordance with ISO 178 (2010). The flexural strength (MPa) of the molded article before the heat treatment was also measured under the same conditions in accordance with ISO 178 (2010). The ratio of the flexural strength measured in accordance with ISO 178 (2010) after heat treatment at 200°C for 1000 hours to the flexural strength measured in accordance with ISO 178 (2010) before heat treatment at 200°C for 1000 hours was defined as the flexural strength retention (%).

[0078] (Temperature Difference Between Melting Point and Crystallization Temperature During Cooling) Using a differential scanning calorimeter "X-DSC7000" manufactured by Hitachi High-Tech Science Corporation, 10.0 mg of pellets of the resin composition obtained in the Examples and Comparative Examples were placed in an aluminum pan and sealed with a lid. The endothermic peak in the thermogram obtained by heating from 20°C to 300°C at a heating rate of 20°C / min under a nitrogen atmosphere was taken as the melting point. The pellets were then completely melted by holding at 300°C for 2 minutes, and then cooled to 50°C at a rate of 20°C / min. The exothermic peak in the thermogram obtained was taken as the crystallization temperature during cooling. In this way, the temperature difference (°C) between the melting point and the crystallization temperature during cooling was determined.

[0079] (Examples 1 to 4 and Comparative Examples 1 to 5) <Raw Materials> [Polyester resin (A) containing a dicarboxylic acid component containing terephthalic acid as a main component and a diol component containing 1,4-butanediol as a main component] A-1: ​​Polybutylene terephthalate (homopolymer of terephthalic acid and 1,4-butanediol) (PBT, intrinsic viscosity = 1.02 dl / g, acid value = 25 eq / ton) [Polyester resin (B) containing a dicarboxylic acid component containing 2,5-furandicarboxylic acid as a main component and a diol component containing ethylene glycol as a main component] B-1: Polyethylene furanoate (homopolymer of 2,5-furandicarboxylic acid and ethylene glycol) (PEF, intrinsic viscosity = 0.61 dl / g, acid value = 15 eq / ton) [Other resins] Polyethylene terephthalate (PET, intrinsic viscosity = 0.62 dl / g, acid value = 25 eq / ton) Polyphenylene ether (PPE, glass transition temperature = 212°C) Polyphenylene sulfide (PPS, "GAC05" manufactured by GLION) [Glass fiber (C)] C-1: ECS03T-120H (manufactured by Nippon Electric Glass Co., Ltd.) (chopped strand glass fiber, number average fiber length 3 mm, number average fiber diameter 11 μm)

[0080] (Preparation of Polycondensation Catalyst Solution) <Preparation of Irganox 1222 Ethylene Glycol Solution> 2.0 L of ethylene glycol was added to a flask equipped with a nitrogen inlet tube and a condenser at room temperature and atmospheric pressure. Then, 200 g of Irganox 1222 (manufactured by BASF) was added as a phosphorus compound while stirring at 200 rpm under a nitrogen atmosphere. After adding another 2.0 L of ethylene glycol, the jacket temperature was changed to 196°C and the temperature was increased. Once the internal temperature reached 185°C or higher, the mixture was stirred under reflux for 60 minutes. Heating was then stopped, and the solution was immediately removed from the heat source. While maintaining the nitrogen atmosphere, the mixture was cooled to 120°C or lower within 30 minutes to prepare an Irganox 1222 ethylene glycol solution.

[0081] <Preparation of an aqueous solution of an aluminum compound> 5.0 L of pure water was added to a flask equipped with a condenser at room temperature and atmospheric pressure, and then 200 g of basic aluminum acetate was added as a slurry with pure water while stirring at 200 rpm. Further pure water was added to bring the total volume to 10.0 L, and the mixture was stirred at room temperature and atmospheric pressure for 12 hours. The jacket temperature was then set to 100.5°C and the temperature was raised. Once the internal temperature reached 95°C or higher, the mixture was stirred under reflux for 3 hours. The stirring was stopped, and the mixture was allowed to cool to room temperature, yielding an aqueous solution.

[0082] <Preparation of an ethylene glycol mixed solution of an aluminum compound> An equal volume of ethylene glycol was added to the aqueous aluminum compound solution obtained by the above method, and the mixture was stirred at room temperature for 30 minutes. The internal temperature was then controlled to 80 to 90°C, and the pressure was gradually reduced to 27 hPa while stirring for several hours. Water was distilled off from the system, and a 20 g / L ethylene glycol solution of an aluminum compound was obtained.

[0083] <(B-1) Preparation of Polyethylene Furanoate> 428.5 g (2.7 mol) of 2,5-furandicarboxylic acid and 219.5 g (3.5 mol) of ethylene glycol were charged into a 2 L stainless steel autoclave equipped with a stirrer, and the temperature was raised to 220°C. After that, the temperature was maintained at 220°C, and an esterification reaction was carried out for 150 minutes under a pressure of 0.25 MPa to obtain an oligomer mixture. The prepared Irganox 1222 ethylene glycol solution and the prepared aluminum compound ethylene glycol mixed solution were then added so that the Al content was 20 ppm and the phosphorus compound content was 58 ppm. Next, the temperature was raised to 250°C over 60 minutes, while the pressure of the reaction system was gradually reduced to 13.3 Pa (0.1 Torr), and a polyester polycondensation reaction was carried out at 250°C and 13.3 Pa for 60 minutes. After the pressure was released, the resin under slight pressure was extruded into cold water in the form of strands to be rapidly cooled, and then held in the cold water for 20 seconds. After that, the resin was cut into cylindrical pellets of polyethylene furanoate having a length of about 3 mm and a diameter of about 2 mm.

[0084] The above raw materials were dry-blended in the proportions (parts by mass) shown in Table 1 and melt-kneaded using a twin-screw extruder ("STS-35" manufactured by COPERION) to produce pellets of the polyester resin compositions of Examples 1 to 4 and Comparative Examples 1 to 5. The obtained pellets were injection-molded to produce molded articles, and the heat aging resistance was evaluated using the method described above. In addition, the temperature difference (°C) between the melting point and the crystallization temperature during cooling was measured using the obtained pellets using the method described above. The results are shown in Table 1.

[0085]

[0086] [Discussion of the Results in Table 1] The molded articles obtained by injection molding the polyester resin compositions obtained in Examples 1 to 4 all had flexural strength retention rates of 55% or more after heat treatment at 200°C for 1,000 hours, indicating excellent heat aging resistance. On the other hand, Comparative Examples 1 to 5 had low flexural strength retention rates after heat treatment at 200°C for 1,000 hours, indicating poor heat aging resistance. Furthermore, the results of Examples 1 to 4 show that as the content of polyethylene furanoate corresponding to polyester resin (B) increases, the flexural strength retention rate after heat treatment at 200°C for 1,000 hours increases, indicating that the higher the content of polyethylene furanoate in the polyester resin composition, the more improved the heat aging resistance.

[0087] In addition, the temperature difference (°C) between the melting point and the crystallization temperature during cooling is an index of crystallinity, and it is believed that the smaller the temperature difference, the faster the crystallization progresses, and therefore the higher the crystallinity. Generally, the higher the crystallinity, the lower the oxygen permeability (i.e., the higher the gas barrier property), and therefore the better the heat aging resistance. Therefore, it is believed that the smaller the temperature difference between the melting point and the crystallization temperature during cooling, the better the heat aging resistance.

[0088] Here, a comparison between Example 2 and Comparative Example 1 and a comparison between Comparative Example 2 and Comparative Example 3 shows that Example 2 and Comparative Example 1, which contain PBT, have a smaller temperature difference between the melting point and the crystallization temperature during cooling than Comparative Examples 2 and 3, which do not contain PBT. This suggests that the polyester resin composition containing PBT has better heat aging resistance than the polyester resin composition containing PET.

[0089] On the other hand, comparing Example 2 with Comparative Example 3, it was shown that Example 2, which contained PBT and PEF as the polyester resin, had a higher flexural strength retention rate than Comparative Example 3, which contained PET and PEF as the polyester resin. In contrast, comparing Comparative Examples 1 and 2, it was shown that Comparative Example 1, which contained only PBT as the polyester resin, had a lower flexural strength retention rate than Comparative Example 2, which contained only PET as the polyester resin.

[0090] This is thought to be because the melting point had a large effect when only PBT was included as the polyester resin (Comparative Example 1) and when only PET was included as the polyester resin (Comparative Example 2), and that Comparative Example 2, which contained only PET, which has a higher melting point than PBT, had improved heat aging resistance compared to Comparative Example 1. Based on this, the inventors predicted that similar results would be obtained in Example 2, which contained PBT and PEF as the polyester resin, and Comparative Example 3, which contained PET and PEF as the polyester resin.

[0091] However, the results showed that Example 2 had a higher flexural strength retention rate than Comparative Example 3, indicating excellent heat aging resistance. This indicates that the inclusion of PBT and PEF as a polyester resin provides the unexpected effect of excellent heat aging resistance.

[0092] According to the present disclosure, a polyester resin composition having excellent heat aging resistance can be provided. Therefore, the polyester resin composition of the present disclosure can be suitably used as a molding material for automobiles, a molding material for parts of electric and electronic products, etc.

Claims

1. A polyester resin composition comprising polyester resin (A) and polyester resin (B), wherein the polyester resin (A) comprises a dicarboxylic acid component containing terephthalic acid as a main component and a diol component containing 1,4-butanediol as a main component, and the polyester resin (B) comprises a dicarboxylic acid component containing 2,5-furandicarboxylic acid as a main component and a diol component containing ethylene glycol as a main component, and the content of the polyester resin (A) is 50 to 95 parts by mass and the content of the polyester resin (B) is 5 to 50 parts by mass per 100 parts by mass of the total of the polyester resins (A) and (B).

2. A polyester resin composition according to claim 1, wherein the content of glass fiber (C) is 50 parts by mass or less per 100 parts by mass of the total of the polyester resin (A) and the polyester resin (B).

3. A polyester resin composition according to claim 1 or 2, wherein a molded article obtained from the polyester resin composition has a flexural strength retention rate [(flexural strength after heat treatment / flexural strength before heat treatment) x 100] of 55% or more after heat treatment at 200°C for 1,000 hours, as measured in accordance with ISO 178.

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