Polyester resin composition, polyester injection-molded article, polyester extrusion-molded article, polyester foam, polyester container, polyester bottle, polyester tableware, and polyester feeding bottle

Abstract

A polyester resin composition including 97.0 mass% to 99.9 mass% of a polyester resin (A) and 0.1 mass % to 3.0 mass% of a polycarbodiimide (B), wherein dicarboxylic acid constituent units in the polyester resin (A) include terephthalic acid units and / or 2,6-napthalene dicarboxylic acid units, 5 mol% to 90 mol% of the diol constituent units in the polyester resin (A) are units derived from a diol having a cyclic acetal skeleton represented by formula (1) or formula (2), 0 mol% to 90 mol% of the diol constituent units being units derived from an alicyclic diol, and the polycarbodiimide (B) having two or more carbodiimide groups in each molecule thereof. (In formula (1), R1 and R2 each independently represent a C1-10 aliphatic group, a C3-10 alicyclic group, or a C6-10 aromatic group.) (In formula (2), R1 is the same as in formula (1), and R3 represents a C1-10 aliphatic group, a C3-10 alicyclic group, or a C6-10 aromatic group.)

Description

Polyester resin composition, polyester injection molded articles, polyester extruded articles, polyester foam, polyester containers, polyester bottles, polyester tableware, and polyester baby bottles.

[0001] The present invention relates to polyester resin compositions, polyester injection molded articles, polyester extruded articles, polyester foams, polyester containers, polyester bottles, polyester tableware, and polyester baby bottles.

[0002] Aromatic saturated polyester resins, particularly polyethylene terephthalate (hereinafter sometimes referred to as "PET"), are resins that offer a good balance of mechanical properties, solvent resistance, fragrance retention, weather resistance, and recyclability, and are widely used, mainly in applications such as bottles and films. However, PET has drawbacks in terms of crystallinity and heat resistance. Specifically, regarding crystallinity, PET has high crystallinity, so when attempting to manufacture thick molded articles or sheets, crystallization causes whitening and loss of transparency. Furthermore, regarding heat resistance, the glass transition temperature of PET is around 80°C, making it unsuitable for applications requiring high heat resistance and transparency, such as products used in automobiles, packaging materials for import and export, food packaging materials for retort processing or microwave heating, and baby bottles and tableware that undergo heat sterilization.

[0003] For this reason, conventionally, low-crystallinity polyester resins such as modified PET partially copolymerized with 1,4-cyclohexanedimethanol and modified PET partially modified with isophthalic acid have been used for applications requiring transparency. However, while modified PET partially copolymerized with 1,4-cyclohexanedimethanol and modified PET partially modified with isophthalic acid offer improved transparency compared to PET, their glass transition temperatures are around 80°C, resulting in poor heat resistance.

[0004] Furthermore, in fields requiring heat resistance, polyester resins such as polyethylene 2,6-naphthalate (hereinafter sometimes referred to as "PEN") and poly(1,4-cyclohexanedimethylene terephthalate), which have high glass transition temperatures, have been used. However, although PEN and poly(1,4-cyclohexanedimethylene terephthalate) also have improved heat resistance, they have high crystallinity and poor transparency.

[0005] On the other hand, polyester resins containing diols with a cyclic acetal skeleton have been proposed as polyester resins that have high transparency while improving the heat resistance of PET and PEN (see, for example, Patent Document 1). Such polyester resins can be used in applications where transparency and heat resistance are required.

[0006] Japanese Patent Publication No. 2017-105873

[0007] However, while the polyester resin described in Patent Document 1 has sufficient heat resistance to maintain its shape when heated for a long time in an oven or with hot water, it suffers from the problem of embrittlement. Considering applications where high impact resistance is required even after heat treatment, there is still room for improvement. The present invention has been made in view of the problems of the above-mentioned prior art, and its purpose is to provide a polyester resin composition that is excellent in heat resistance, transparency, and impact resistance, and that is less prone to embrittlement after heat treatment.

[0008] As a result of diligent research, the inventors of the present invention have found that a polyester resin composition containing a polyester resin having a predetermined composition and a predetermined amount of polycarbodiimide exhibits excellent heat resistance, transparency, and impact resistance, and is less prone to embrittlement after heat treatment, thus completing the present invention.

[0009] In other words, the present invention encompasses the following embodiments: [1] A polyester resin composition comprising 97.0% by mass or more and 99.9% by mass or less of a polyester resin (A) and 0.1% by mass or more and 3.0% by mass or less of a polycarbodiimide (B), wherein the dicarboxylic acid constituent units in the polyester resin (A) include terephthalic acid units and / or 2,6-naphthalenedicarboxylic acid units, 5 mol% or more and 90 mol% or less of the diol constituent units in the polyester resin (A) are units derived from a diol having a cyclic acetal skeleton represented by the following formula (1) or formula (2), and 0 mol% or more and 90 mol% or less of the diol constituent units are units derived from an alicyclic diol, and the polycarbodiimide (B) has two or more carbodiimide groups in its molecule. (In formula (1), R １ and R ２ Each of these independently represents an aliphatic group with 1 to 10 carbon atoms, an alicyclic group with 3 to 10 carbon atoms, or an aromatic group with 6 to 10 carbon atoms. (In formula (2), R １ The same applies as described above, R ３(wherein represents an aliphatic group having 1 to 10 carbon atoms, an alicyclic group having 3 to 10 carbon atoms, or an aromatic group having 6 to 10 carbon atoms.) [2] The polyester resin composition according to [1], wherein the diol having a cyclic acetal skeleton is 3,9-bis(1,1-dimethyl-2-hydroxyethyl)-2,4,8,10-tetraoxaspiro[5.5]undecane. [3] The polyester resin composition according to [1], wherein the alicyclic diol is 1,4-cyclohexanedimethanol. [4] A polyester injection molded article comprising the polyester resin composition according to any one of [1] to [3]. [5] A polyester extruded article comprising the polyester resin composition according to any one of [1] to [3]. [6] A polyester foam comprising the polyester resin composition according to any one of [1] to [3]. [7] A polyester container comprising the polyester resin composition according to any one of [1] to [3]. [8] A polyester bottle comprising the polyester resin composition according to any one of [1] to [3]. [9] Polyester tableware comprising the polyester resin composition described in any of [1] to [3].

[10] Polyester baby bottle comprising the polyester resin composition described in any of [1] to [3].

[0010] The polyester resin composition of the present invention exhibits excellent heat resistance, transparency, and impact resistance, and is less prone to embrittlement after heat treatment.

[0011] The following describes in detail embodiments for carrying out the present invention (hereinafter simply referred to as "this embodiment"). This embodiment is illustrative for explaining the present invention and is not intended to limit the present invention to the following content. The present invention can be implemented by modifying it as appropriate within the scope of its gist.

[0012] <Polyester Resin Composition> The polyester resin composition of this embodiment comprises 97.0% by mass or more and 99.9% by mass or less of polyester resin (A), and 0.1% by mass or more and 3.0% by mass or less of polycarbodiimide (B), wherein the dicarboxylic acid constituent units in the polyester resin (A) include terephthalic acid units and / or 2,6-naphthalenedicarboxylic acid units, 5 mol% or more and 90 mol% or less of the diol constituent units in the polyester resin (A) are units derived from a diol having a cyclic acetal skeleton represented by the following formula (1) or formula (2), and 0 mol% or more and 90 mol% or less of the diol constituent units are units derived from an alicyclic diol, and the polycarbodiimide (B) has two or more carbodiimide groups in its molecule. (In formula (1), R １ and R ２ Each of these independently represents an aliphatic group with 1 to 10 carbon atoms, an alicyclic group with 3 to 10 carbon atoms, or an aromatic group with 6 to 10 carbon atoms. (In formula (2), R １ The same applies as described above, R ３ (This represents an aliphatic group with 1 to 10 carbon atoms, an alicyclic group with 3 to 10 carbon atoms, or an aromatic group with 6 to 10 carbon atoms.)

[0013] As the polyester resin composition of this embodiment is constructed as described above, it exhibits excellent heat resistance, transparency, and impact resistance, and is less prone to embrittlement after heat treatment. Therefore, it can be suitably used in products used in automobiles, packaging materials for import and export, food packaging materials for retort processing and microwave heating, containers such as baby bottles and tableware that undergo heat sterilization, and applications requiring high heat resistance. The following describes each component contained in the polyester resin composition of this embodiment.

[0014] [Polyester resin (A)] As described above, polyester resin (A) has predetermined dicarboxylic acid constituent units and diol constituent units, and is contained in an amount of 97.0% by mass or more and 99.9% by mass or less based on 100% by mass of the polyester resin composition.

[0015] (Diol structural unit) The diol structural unit in the polyester resin (A) contains, based on 100 mol% of the diol structural unit, 5 mol% or more and 90 mol% or less of the unit derived from the diol having a cyclic acetal skeleton represented by the above formula (1) or formula (2), and contains 0 mol% or more and 90 mol% or less of the unit derived from the alicyclic diol. Thus, the unit derived from the alicyclic diol in this embodiment is an arbitrary structural unit that may not be contained in the polyester resin (A).

[0016] (Unit derived from diol having a cyclic acetal skeleton) In the above formulas (1) and (2), R １ and R ２ are each independently an aliphatic group having 1 to 10 carbon atoms, an alicyclic group having 3 to 10 carbon atoms, or an aromatic group having 6 to 10 carbon atoms, and preferably represent a methylene group, an ethylene group, a propylene group, a butylene group or a structural isomer thereof, for example, an isopropylene group, an isobutylene group. R ３ is an aliphatic group having 1 to 10 carbon atoms, an alicyclic group having 3 to 10 carbon atoms, or an aromatic group having 6 to 10 carbon atoms, and preferably represents a methyl group, an ethyl group, a propyl group, a butyl group, or a structural isomer thereof, for example, an isopropylene group, an isobutylene group. As the diol having a cyclic acetal skeleton represented by the above formula (1), 3,9-bis(1,1-dimethyl-2-hydroxyethyl)-2,4,8,10-tetraoxaspiro[5.5]undecane is particularly preferable, and as the diol having a cyclic acetal skeleton represented by the above formula (2), 5-methylol-5-ethyl-2-(1,1-dimethyl-2-hydroxyethyl)-1,3-dioxane is particularly preferable.

[0017] (Units derived from alicyclic diols) The alicyclic diol units in the diol constituent units of polyester resin (A) are not particularly limited, but examples include units derived from diols such as 1,3-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, 1,2-decahydronaphthalenedimethanol, 1,3-decahydronaphthalenedimethanol, 1,4-decahydronaphthalenedimethanol, 1,5-decahydronaphthalenedimethanol, 1,6-decahydronaphthalenedimethanol, 2,7-decahydronaphthalenedimethanol, tetralinedimethanol, norbornenedimethanol, tricyclodecanedimethanol, and pentacyclododecanedimethanol. Units derived from 1,4-cyclohexanedimethanol, norbornenedimethanol, tricyclodecanedimethanol, and 2,6-decahydronaphthalenedimethanol are preferred, and units derived from 1,4-cyclohexanedimethanol are particularly preferred.

[0018] (Other Diol Constituent Units) The diol constituent units of this embodiment may include other diol constituent units other than diol units having a cyclic acetal skeleton and alicyclic diol units. The content of other diol constituent units can be 0 mol% or more and 95 mol% or less relative to 100 mol% of diol constituent units. Other diol constituent units include aliphatic diols such as ethylene glycol, trimethylene glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, diethylene glycol, propylene glycol, and neopentyl glycol; polyether compounds such as polyethylene glycol, polypropylene glycol, and polybutylene glycol; bisphenols such as 4,4'-(1-methylethylidene)bisphenol, methylenebisphenol (bisphenol F), 4,4'-cyclohexylidenebisphenol (bisphenol Z), and 4,4'-sulfonylbisphenol (bisphenol S); alkylene oxide adducts of the bisphenols; aromatic dihydroxy compounds such as hydroquinone, resorcinol, 4,4'-dihydroxybiphenyl, 4,4'-dihydroxydiphenyl ether, and 4,4'-dihydroxydiphenylbenzophenone; and diol-derived units such as alkylene oxide adducts of the aromatic dihydroxy compounds. Considering the mechanical strength, heat resistance, and availability of polyester resin, if other diol constituent units are present, they are preferably derived from ethylene glycol.

[0019] (Dicarboxylic acid constituent units) The dicarboxylic acid constituent units in the polyester resin (A) include terephthalic acid units and / or 2,6-naphthalenedicarboxylic acid units. Terephthalic acid units refer to units derived from terephthalic acid, and 2,6-naphthalenedicarboxylic acid units refer to units derived from 2,6-naphthalenedicarboxylic acid. In addition, the dicarboxylic acid constituent units may include other dicarboxylic acid constituent units to the extent that they do not impair the purpose of this embodiment. Other dicarboxylic acid constituent units include, but are not limited to, units derived from aliphatic dicarboxylic acids such as succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, decanedicarboxylic acid, dodecanedicarboxylic acid, cyclohexanedicarboxylic acid, decalindicarboxylic acid, norbornanedicarboxylic acid, tricyclodecanedicarboxylic acid, pentacyclododecanedicarboxylic acid, 3,9-bis(1,1-dimethyl-2-carboxyethyl)-2,4,8,10-tetraoxaspiro[5.5]undecane, and 5-carboxy-5-ethyl-2-(1,1-dimethyl-2-carboxyethyl)-1,3-dioxane; and units derived from aromatic dicarboxylic acids such as isophthalic acid, phthalic acid, 2-methylterephthalic acid, 1,4-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid, biphenyldicarboxylic acid, and tetralindicarboxylic acid. In this embodiment, from the viewpoint of sufficiently improving the balance of physical properties such as transparency, heat resistance, impact resistance, and mechanical strength of the polyester resin (A), it is preferable that the terephthalic acid units and / or 2,6-naphthalenedicarboxylic acid units are contained in an amount of 80 mol% to 100 mol%, more preferably 90 mol% to 100 mol%, and particularly preferably 100 mol% per 100 mol% of dicarboxylic acid constituent units.

[0020] Polyester resin (A) contains 5 mol% to 90 mol% of units derived from the cyclic acetal skeleton diol mentioned above, relative to 100 mol% of the total diol constituent units. This reduces crystallinity and increases the glass transition temperature, resulting in high transparency and high heat resistance. Polyester resin (A) has a better balance of transparency and heat resistance compared to other polyester resins, such as those in which 100 mol% of the diol constituent units are derived from ethylene glycol and 1,4-cyclohexanedimethanol, as well as PET, polybutylene terephthalate, and polylactic acid. From a similar viewpoint, polyester resin (A) preferably contains 15 mol% to 80 mol%, more preferably 20 mol% to 70 mol%, of units derived from the cyclic acetal skeleton diol mentioned above.

[0021] The polyester resin (A) contains units derived from the above-mentioned alicyclic diol in an amount of 0 mol% to 90 mol% relative to 100 mol% of the total diol constituent units. In this embodiment, from the viewpoint of further improving the impact resistance of the polyester resin (A), it is preferable that the polyester resin (A) contains units derived from alicyclic diol in an amount of 10 mol% to 90 mol%, and more preferably 15 mol% to 90 mol%.

[0022] In this embodiment, from the viewpoint of impact resistance, a polyester resin (A) is provided in which 15 mol% to 50 mol% of the diol constituent units in the polyester resin (A) are derived from diols having a cyclic acetal skeleton, and 15 mol% to 85 mol% are derived from alicyclic diols.

[0023] In this embodiment, considering the balance of transparency, heat resistance, impact resistance, mechanical strength, etc., it is preferable that 100 mol% of the dicarboxylic acid constituent units in polyester resin (A) are terephthalic acid units and / or 2,6-naphthalenedicarboxylic acid, and that 5 mol% to 90 mol% of the diol constituent units are units derived from 3,9-bis(1,1-dimethyl-2-hydroxyethyl)-2,4,8,10-tetraoxaspiro[5.5]undecane, 0 mol% to 90 mol% of units derived from 1,4-cyclohexanedimethanol, and 0 mol% to 90 mol% of units derived from ethylene glycol. From a similar viewpoint, it is particularly preferable that 100 mol% of the dicarboxylic acid constituent units in the polyester resin (A) are terephthalic acid units and / or 2,6-naphthalenedicarboxylic acid units, and that 15 mol% to 50 mol% of the diol constituent units are units derived from 3,9-bis(1,1-dimethyl-2-hydroxyethyl)-2,4,8,10-tetraoxaspiro[5.5]undecane, 15 mol% to 85 mol% are units derived from 1,4-cyclohexanedimethanol, and 0 mol% to 70 mol% are units derived from ethylene glycol.

[0024] (Other constituent units) The polyester resin (A) may contain monoalcohol units such as butyl alcohol, hexyl alcohol, and octyl alcohol, trivalent or higher polyhydric alcohol units such as trimethylolpropane, glycerin, 1,3,5-pentanetriol, and pentaerythritol, monocarboxylic acid units such as benzoic acid, propionic acid, and butyric acid, polycarboxylic acid units such as trimellitic acid and pyromellitic acid, and oxyacid units such as glycolic acid, lactic acid, hydroxybutyric acid, 2-hydroxyisobutyric acid, and hydroxybenzoic acid, to the extent that the purpose of this embodiment is not impaired.

[0025] The method for producing the polyester resin of this embodiment is not particularly limited, and conventionally known methods can be applied. Examples include melt polymerization methods such as transesterification and direct esterification, or solution polymerization. Conventionally known stabilizers such as transesterification catalysts, esterification catalysts, etherification inhibitors, heat stabilizers, and light stabilizers, as well as polymerization regulators, can also be used.

[0026] [Polycarbodiimide (B)] The polycarbodiimide (B) in this embodiment is not particularly limited as long as it has two or more carbodiimide groups in its molecule, and various known types can be used. For example, aromatic polycarbodiimides and aliphatic polycarbodiimides, which will be described later, can be used.

[0027] Aromatic polycarbodiimides are compounds in which a carbodiimide group is directly bonded to an aromatic ring, and are not particularly limited, but can be synthesized, for example, by a decarboxylation condensation reaction of diisocyanates using a carbodiimide catalyst such as an organophosphorus compound or an organometallic compound. Specific examples of the diisocyanates include, but are not limited to, 1,5-naphthalene diisocyanate, 4,4'-diphenylmethane diisocyanate, 4,4'-diphenyldimethylmethane diisocyanate, 1,3-phenylene diisocyanate, 1,4-phenylene diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 3,3',5,5'-tetraisopropylbiphenyl-4,4'-diisocyanate, and 1,3,5-triisopropylbenzene-2,4-diisocyanate. These may be used individually or in combination of two or more. Of these, 4,4'-diphenylmethanediisocyanate and 1,3,5-triisopropylbenzene-2,4-diisocyanate are preferred from the viewpoint of stability.

[0028] Aliphatic polycarbodiimides are compounds in which a carbodiimide group is bonded to a carbon atom other than an aromatic ring, and are not particularly limited, but can be similarly synthesized by a decarboxylation condensation reaction of diisocyanates using a carbodiimide catalyst such as an organophosphorus compound or an organometallic compound. Specific examples of the diisocyanate include, but are not limited to, hexamethylene diisocyanate, cyclohexane-1,4-diisocyanate, isophorone diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, methylcyclohexane diisocyanate, 1,3-bis(isocyanatomethyl)cyclohexane, xylylene diisocyanate, and tetramethylxylylene diisocyanate. These may be used individually or in combination of two or more. Of these, 4,4'-dicyclohexylmethane diisocyanate is preferred from the viewpoint of stability.

[0029] Aromatic polycarbodiimides or aliphatic polycarbodiimides can be encapsulated and their degree of polymerization adjusted by reacting them with monofunctional compounds that are reactive with the isocyanate group at the diisocyanate terminus used in synthesis. Specific examples of such compounds include, but are not limited to, monoisocyanates such as phenyl isocyanate, tolyl isocyanate, isopropylphenyl isocyanate, and cyclohexyl isocyanate; alcohols such as methanol, isopropyl alcohol, phenol, and polyethylene glycol monomethyl ether; amines such as butylamine, diethylamine, and cyclohexylamine; and carboxylic acids such as propionic acid and benzoic acid.

[0030] The degree of polymerization of polycarbodiimide (B) is preferably 2 to 50, and more preferably 5 to 30, from the viewpoint of improving the impact resistance of the polyester resin composition and suppressing embrittlement after heat treatment. From the viewpoint of further improving the impact resistance of the polyester resin composition and further suppressing embrittlement after heat treatment, it is particularly preferable to use an aliphatic polycarbodiimide consisting of 4,4'-dicyclohexylmethane diisocyanate with a degree of polymerization of 5 to 30 as polycarbodiimide (B).

[0031] Polycarbodiimide (B) may be one type alone or two or more types in combination from among aromatic polycarbodiimides and aliphatic polycarbodiimides. In this embodiment, it is preferable to use aliphatic polycarbodiimides from the viewpoint of stability and the reactivity of the carbodiimide group.

[0032] (Mechanism of Action) The mechanism of action of the polyester resin composition of this embodiment will be explained here, but this explanation is based on speculation and is not intended to limit the mechanism of action to the following. That is, as mentioned above, polyester resin (A) exhibits excellent performance in terms of heat resistance, transparency and impact resistance, but in the polyester resin composition of this embodiment, polycarbodiimide (B) extends or branches the molecular chains of polyester resin (A), thereby not only obtaining a good balance of physical properties of heat resistance, transparency and impact resistance, but also making this balance of physical properties particularly good. In other words, the action of polycarbodiimide (B), in combination with the performance of polyester resin (A), ensures good heat resistance and transparency, while particularly improving impact resistance and significantly suppressing embrittlement after heat treatment. From the above viewpoint, the content of polyester resin (A) per 100% by mass of the polyester resin composition is 97.0% by mass or more and the content of polycarbodiimide (B) is 3.0% by mass or less. If the polyester resin (A) content is less than 97.0% by mass, it becomes difficult to ensure a balance between heat resistance, transparency, and impact resistance. If the polycarbodiimide (B) content exceeds 3.0% by mass, impact resistance becomes insufficient due to aggregates, degraded products, gels, etc. caused by polycarbodiimide (B), and embrittlement after heat treatment becomes extremely likely. Therefore, it is important that the polyester resin composition of this embodiment contains 97.0% by mass or more and 99.9% by mass or less of polyester resin (A), and 0.1% by mass or more and 3.0% by mass or less of polycarbodiimide (B). From the above viewpoint, the polyester resin (A) content in the polyester resin composition is preferably 98.0% by mass or more and 99.9% by mass or less, and more preferably 99.0% by mass or more and 99.9% by mass or less. Similarly, the content of polycarbodiimide (B) in the polyester resin composition is preferably 0.1% by mass or more and 2.0% by mass or less, more preferably 0.1% by mass or more and 1.0% by mass or less, and even more preferably 0.2% by mass or more and 1.0% by mass or less.

[0033] The method for adding polycarbodiimide (B) and optional components described later to polyester resin (A) is not particularly limited, but melt kneading by extruder is preferred. In this case, a masterbatch may be prepared by melt kneading a high concentration of polycarbodiimide, and then diluted to the desired concentration for use during molding.

[0034] [Optional Components] The polyester resin composition of this embodiment may further contain optional components other than polyester resin (A) and polycarbodiimide (B). Such optional components are not limited to the following, but may include various additives and molding aids such as antioxidants, light stabilizers, ultraviolet absorbers, plasticizers, fillers, matting agents, drying regulators, antistatic agents, anti-settling agents, surfactants, flow improvers, drying oils, waxes, fillers, colorants, reinforcing agents, surface smoothing agents, leveling agents, and curing reaction accelerators. In addition, the optional components may include resins and oligomers such as polyolefin resins, polyester resins other than polyester resin (A), polyamide resins, polycarbonate resins, acrylonitrile resins, vinyl chloride resins, vinyl acetate resins, polyacrylic acid resins, polymethacrylic acid resins, polystyrene, ABS resins, polyimide resins, and AS resins. While there are no particular limitations on the content of optional components, from the viewpoint of ensuring good heat resistance and transparency, improving impact resistance, and effectively suppressing embrittlement after heat treatment, it is preferable that the content be 2.9% by mass or less, more preferably 1.0% by mass or less, and particularly preferable that it be 0.5% by mass or less, based on 100% by mass of the polyester resin composition.

[0035] [Physical Properties] The glass transition temperature of the polyester resin (A) is preferably 95°C or higher, more preferably 110°C or higher, and still more preferably 130°C or higher. When the glass transition temperature is within the above range, the polyester resin composition of the present embodiment tends to have better heat resistance. Therefore, it can be used in applications that require high heat resistance, which were not possible with conventional PET or modified PET partially copolymerized with 1,4-cyclohexanedimethanol and isophthalic acid. For example, it can be used in automobiles and ship cabins passing through the equator (said to reach 70 - 80°C), and is thus suitably used for automobile interiors, air fresheners used inside automobiles, containers for eye drops, etc., and packaging materials used for import and export such as blister packs. It can also be suitably used in applications that require high-temperature treatment, such as food packaging materials for microwave heating or retort processing, and containers such as baby bottles and tableware for heat sterilization treatment. The above glass transition temperature can be measured based on the method described in the examples below. Also, the glass transition temperature can be adjusted to the above preferred range by appropriately selecting, for example, the dicarboxylic acid structural unit and the diol structural unit in the polyester resin (A) based on the above-described preferred embodiments.

[0036] Also, the heat quantity of the crystallization exothermic peak during cooling of the polyester resin (A) is preferably 5 J / g or less, more preferably 3 J / g or less. When the crystallization exothermic peak during cooling is within the above range, the polyester resin composition of the present embodiment tends to have lower crystallinity and can be suitably used in applications that require high transparency. The heat quantity of the crystallization peak during cooling can be measured based on the method described in the examples below. Also, the heat quantity of the crystallization peak during cooling can be adjusted to the above preferred range by appropriately selecting, for example, the dicarboxylic acid structural unit and the diol structural unit in the polyester resin (A) based on the above-described preferred embodiments.

[0037] The haze of a 3.2 mm thick test piece obtained by injection molding the polyester resin composition of this embodiment is preferably 4% or less, and more preferably 3% or less. When the haze is within the above range, the polyester resin composition of this embodiment tends to exhibit higher transparency. The haze can be measured based on the method described in the examples later. Furthermore, the haze can be adjusted to the above-mentioned preferred range by, for example, appropriately selecting the dicarboxylic acid constituent units and diol constituent units in the polyester resin (A) based on the preferred embodiment described above.

[0038] In an Izod test conducted using a 4J hammer after immersing 10 test pieces, each 63.5 mm long, 12.7 mm wide, and 3.2 mm thick, without notches, obtained by injection molding the polyester resin composition of this embodiment, in hot water at 50 to 100°C for 24 hours, the number of fractured test pieces is preferably 2 or less, and more preferably 1 or less. When the number of fractured pieces falls within the above range, the polyester resin composition of this embodiment tends to exhibit sufficient impact resistance for practical use in many applications. The above number of fractured pieces can be measured based on the method described in the examples later. Furthermore, the number of fractured pieces can be adjusted to the above-mentioned preferred range by, for example, appropriately selecting the dicarboxylic acid constituent units and diol constituent units in the polyester resin (A) based on the preferred embodiment described above.

[0039] The polyester resin composition of this embodiment can be further given UV barrier properties by adjusting the proportion of 2,6-naphthalenedicarboxylic acid units in the dicarboxylic acid constituent units of the polyester resin (A). Specifically, when 0.1 mol% to 100 mol% of the dicarboxylic acid constituent units are 2,6-naphthalenedicarboxylic acid units, the polyester resin composition of this embodiment tends to have good UV barrier properties. From a similar viewpoint, it is particularly preferable that 90 mol% to 100 mol% of the dicarboxylic acid constituent units in the polyester resin (A) are 2,6-naphthalenedicarboxylic acid units.

[0040] The polyester resin composition of the present embodiment can further contain thermoplastic resins such as polyethylene terephthalate and polybutylene terephthalate as polyester resins other than the polyester resin (A) within a range that does not inhibit the object. Also in this case, the polyester resin composition can be prepared by melt-kneading the polyester resin (A), the polycarbodiimide (B), and the thermoplastic resin.

[0041] <Use of the polyester resin composition> The polyester resin composition of the present embodiment can be used for various applications. For example, it can be used for injection molded articles, sheets, films, extruded molded articles such as pipes, bottles, foams, adhesives, adhesives, paints, etc. More specifically, the injection molded article may be an insert molded article or a two-color molded article. The sheet may be single-layer or multi-layer, the film may be single-layer or multi-layer, and may be un-stretched, stretched in one direction, or stretched in two directions, and may be laminated on a steel plate or the like. The film may be formed by inflation molding. The bottle may be a direct blow bottle or an injection blow bottle, and may be injection molded. The foam may be a bead foam or an extruded foam. In particular, it can be suitably used for applications that require high heat resistance, such as products used inside automobiles, packaging materials for import and export, food packaging materials that are retort-treated or heated in a microwave oven, containers such as baby bottles and tableware that are heat-sterilized, etc. It can also be suitably used for packaging materials such as containers that require UV barrier properties. That is, the polyester-based injection molded article, polyester-based extruded molded article, polyester-based foam, polyester-based container, polyester-based bottle, polyester-based tableware, and polyester-based baby bottle of the present embodiment can each be said to contain the polyester resin composition of the present embodiment. These are not particularly limited as long as they contain the polyester resin composition of the present embodiment, and can be in various known forms according to each application.

[0042] Hereinafter, the present embodiment will be described in more detail with reference to examples, but the scope of the present embodiment is not limited by these examples.

[0043] [Evaluation Method] The evaluation method for the polyester resin and polyester resin composition in this example was as follows: (1) Ratio of diol units having a cyclic acetal skeleton and alicyclic diol units The ratio of units derived from diols having a cyclic acetal skeleton and units derived from alicyclic diols in the polyester resin was: １ The temperature was calculated by 1H-NMR measurement. The measurement instrument was a Bruker BioSpin K.K. Ascend™ 500. Deuterated chloroform was used as the solvent. (2) Glass transition temperature and exothermic peak during cooling The glass transition temperature (Tgm) of the polyester resin was measured using a Shimadzu Corporation scanning calorimeter (model: DSC / TA-50WS). Approximately 10 mg of the sample was placed in an unsealed aluminum container and measured in a nitrogen gas (30 mL / min) stream at a heating rate of 20°C / min. The temperature at which the baseline of the DSC curve changed by half before and after the transition was defined as the glass transition temperature. The exothermic peak during cooling was measured by holding the glass transition temperature at 280°C for 1 minute and then cooling it at a rate of 10°C / min. The area of ​​the exothermic peak that appeared was measured from the area of ​​the exothermic peak. (3) Haze The haze was measured in accordance with JIS-K-7105 and ASTM D1003. Specifically, a 50 mm diameter, 3.2 mm thick disc obtained by injection molding of a polyester resin composition was conditioned for 48 hours and then measured in an atmosphere of 23°C and 50% relative humidity. A haze value measuring device (model: COH-300A) manufactured by Nippon Denshoku Industries Co., Ltd. was used as the measuring device. (4) Impact resistance Impact resistance was evaluated by the Izod test in accordance with JIS K7110. Specifically, 10 test pieces, 63.5 mm in length, 12.7 mm in width, 3.2 mm in thickness, and without notches, obtained by injection molding of a polyester resin composition, were immersed in hot water at 50°C, 60°C, or 100°C for 24 hours, and then tested using a 4 J hammer in an atmosphere of 23°C and 50% relative humidity, and the number of pieces that broke was measured. The Izod impact tester manufactured by Ueshima Seisakusho Co., Ltd. was used as the testing machine.

[0044] [Production Examples 1-3] [Synthesis of Polyester Resins (PEs-1, PEs-2, and PEs-3)] A 30 L polyester production apparatus equipped with a packed column, partial condenser, total condenser, cold trap, stirrer, heating device, and nitrogen inlet pipe was charged with the raw material monomers listed in Table 1. 0.005 mol% of tetra-n-butoxytitanium and 0.02 mol% of potassium acetate were added to the dicarboxylic acid component, and the temperature was raised to 225°C under a nitrogen atmosphere to carry out a transesterification reaction. After the reaction conversion rate of the dicarboxylic acid component was 90% or more, 0.025 mol% of germanium dioxide and 0.05 mol% of triethyl phosphate were added to the dicarboxylic acid component, and the temperature was gradually increased and the pressure reduced until polycondensation was finally carried out at 280°C and 0.1 kPa or less. The reaction was terminated when an appropriate melt viscosity was reached, and polyester resins PEs-1, PEs-2, and PEs-3 were synthesized, respectively.

[0045]

[0046] The meanings of the abbreviations in Table 1 are as follows: DMT: Dimethyl terephthalate NDCM: 2,6-Naphthalenedicarboxylate EG: Ethylene glycol SPG: 3,9-Bis(1,1-dimethyl-2-hydroxyethyl)-2,4,8,10-Tetraoxaspiro[5.5]undecane CHDM: 1,4-Cyclohexanedimethanol

[0047] [Polycarbodiimide] As the polycarbodiimide, we used Carbodilite HMV-15CA (an aliphatic polycarbodiimide consisting of 4,4'-dicyclohexylmethane diisocyanate, degree of polymerization 15) manufactured by Nisshinbo Chemical Co., Ltd.

[0048] [Example 1] (Preparation of compounded pellets) Using a twin-screw compounding extruder (manufactured by Toshiba Machine Co., Ltd., model: TEM26SX, screw diameter: 26 mmφ, L / D: 48), the polyester resin and polycarbodiimide synthesized in Production Example 1 were dry-blended in a ratio of 99.9 / 0.1 mass% and fed from the hopper. The strands were extruded under the conditions of cylinder temperature 180-260°C, die temperature 260°C, screw rotation speed 75 rpm, and discharge rate 15 kg / h. After water cooling, the material was pelletized to obtain polyester resin / polycarbodiimide compounded pellets.

[0049] (Injection molding of compounded pellets) Next, the obtained compounded pellets were injection molded. An injection molding machine manufactured by Japan Steel Works, Ltd., model: J85AD, was used for injection molding, and the molding was performed under conditions of cylinder temperature 245 to 280°C and mold temperature 15 to 50°C. Haze measurements and Izod tests were performed on the molded test pieces after immersion in 100°C hot water for 24 hours. The results are shown in Table 2.

[0050] [Examples 2-10] Test specimens were prepared in the same manner as in Example 1, except that the mixing ratio of the polyester resin and polycarbodiimide used and the hot water immersion temperature were changed as shown in Table 2, and then evaluated. The results are shown in Table 2.

[0051] [Comparative Examples 1-6] Test specimens were prepared in the same manner as in Example 1, except that the mixing ratio of the polyester resin and polycarbodiimide used and the hot water immersion temperature were changed as shown in Table 3, and then evaluated. The results are shown in Table 3.

[0052]

[0053]

[0054] The polyester resin compositions of Examples 1 to 10 showed significantly improved impact resistance after hot water immersion compared to the polyester resin compositions of Comparative Examples 1 to 6.

[0055] This application is based on Japanese Patent Application No. 2019-084202 filed on April 25, 2019, the contents of which are incorporated herein by reference.

[0056] The polyester resin composition of the present invention exhibits excellent heat resistance, transparency, and impact resistance, making it suitable for use in products used in automobiles, packaging materials for import and export, food packaging materials for retort processing and microwave heating, containers such as baby bottles and tableware that undergo heat sterilization, and applications requiring high heat resistance. The industrial significance of the present invention is therefore great.

Claims

A polyester resin composition comprising: 97.0% by mass or more and 99.9% by mass or less of a polyester resin (A); and 0.1% by mass or more and 3.0% by mass or less of a polycarbodiimide (B), wherein a dicarboxylic acid constituent unit in the polyester resin (A) comprises at least one of a terephthalic acid unit a 2,6-naphthalenedicarboxylic acid unit,5% by mol or more and 90% by mol or less of a diol constituent unit in the polyester resin (A) is a unit derived from a diol having a cyclic acetal skeleton represented by the following formula (1) or formula (2), and 0% by mol or more and 90% by mol or less of the diol constituent unit is a unit derived from an alicyclic diol, and the polycarbodiimide (B) has two or more carbodiimide groups in one molecule thereof:wherein R1 and R2 each independently represent an aliphatic group having 1 to 10 carbon atoms, an alicyclic group having 3 or more and 10 or less carbon atoms, or an aromatic group having 6 or more and 10 or less carbon atoms, and  wherein R1 is as defined above; and R3 represents an aliphatic group having 1 or more and 10 or less carbon atoms, an alicyclic group having 3 or more and 10 or less carbon atoms, or an aromatic group having 6 or more and 10 or less carbon atoms.The polyester resin composition according to claim 1, wherein the diol having the cyclic acetal skeleton is 3,9-bis(1,1-dimethyl-2-hydroxyethyl)-2,4,8,10-tetraoxaspiro [5.5] undecane. The polyester resin composition according to claim 1, wherein the alicyclic diol is 1,4-cyclohexanedimethanol.A polyester-based injection-molded article comprising the polyester resin composition according to any one of claims 1 to 3.A polyester-based extruded article comprising the polyester resin composition according to any one of claims 1 to 3. A polyester-based foam comprising the polyester resin composition according to any one of claims 1 to 3. A polyester-based container comprising the polyester resin composition according to any one of claims 1 to 3. A polyester-based bottle comprising the polyester resin composition according to any one of claims 1 to 3. A polyester-based tableware comprising the polyester resin composition according to any one of claims 1 to 3. A polyester-based nursing bottle comprising the polyester resin composition according to any one of claims 1 to 3.

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