Polybutylene terephthalate resin composition, and molded article

Abstract

To provide a polybutylene terephthalate resin composition which is excellent in hydrolysis resistance and flowability, and suppresses change in flowability in manufacture and molding of a resin composition, and a molded article obtained using the same.SOLUTION: A polybutylene terephthalate resin composition contains a polybutylene terephthalate resin (A) having a terminal carboxyl group amount of 25 meq / kg or less, and a cyclic carbodiimide compound (B), where a polyvalent-hydroxyl-group-containing compound (C-1) having a hydroxyl value which is polyhydric or its partial ester of 200 or more is less than 0.05 pts.mass with respect to 100 pts.mass of the polybutylene terephthalate resin (A), and satisfies the following expression 1. Expression 1: (-15.4×b)+19.3≤a≤(-57.4×b)+59.3. In the expression 1, a represents a carbodiimide group amount (meq / kg) per 1 kg of the polybutylene terephthalate resin composition, and b represents intrinsic viscosity (dL / g) of the polybutylene terephthalate resin (A).SELECTED DRAWING: None

Description

[Technical field]

[0001] An embodiment of the present invention relates to a polybutylene terephthalate resin composition and a molded article. [Background technology]

[0002] Polybutylene terephthalate resin (hereinafter also referred to as "PBT resin") has excellent mechanical properties, electrical properties, other physical properties, and chemical properties, and is also easy to process, and therefore is used as an engineering plastic in a wide range of applications, such as automobile parts and electrical and electronic parts. In particular, PBT resin is preferably used in applications such as cases that house substrates on which electronic parts are mounted, insert molded products that contain sensor cases and connector terminals, and actuator cases that protect gears and motors, in order to protect against damage caused by moisture, dust, or impact from the outside.

[0003] On the other hand, since PBT resin has ester groups in its molecules, it is prone to hydrolysis in hot and humid environments, which can cause a decrease in physical properties such as toughness. For this reason, when molded products are used in environments with severe temperature changes, such as inside the engine compartment of a car or outdoors, it is desirable to improve hydrolysis resistance.

[0004] As a method for improving the hydrolysis resistance of PBT resin, for example, the addition of a carbodiimide compound is known. On the other hand, the carbodiimide compound may cause isocyanate gas generation during molding. Patent Document 1 describes that a resin composition containing an aromatic polyester resin, a cyclic carbodiimide compound having at least two carbodiimide rings each having only one carbodiimide group in one ring, and a polyvalent hydroxyl group-containing compound having a hydroxyl value of 200 or more is excellent in hydrolysis resistance and fluidity, and can suppress the generation of isocyanate gas during molding. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] International Publication No. 2013 / 146625 Summary of the Invention [Problem to be solved by the invention]

[0006] In addition to improving hydrolysis resistance, it is desirable for the polybutylene terephthalate resin composition to have good flowability during molding from the viewpoint of good moldability. Also, from the viewpoint of management during production and molding of the resin composition, it is desirable that the flowability during production and molding of the resin composition does not change significantly. An object of an embodiment of the present invention is to provide a polybutylene terephthalate resin composition that is excellent in hydrolysis resistance and fluidity during molding, and in which changes in fluidity during production and molding of the resin composition are suppressed, and a molded article obtained using the same. [Means for solving the problem]

[0007] One embodiment of the present invention relates to a polybutylene terephthalate resin composition comprising a polybutylene terephthalate resin (A) having a terminal carboxyl group amount of 25 meq / kg or less and a cyclic carbodiimide compound (B), in which a polyhydric alcohol or a partial ester thereof having a hydroxyl value of 200 or more and a polyhydric hydroxyl group-containing compound (C-1) is less than 0.05 part by mass per 100 parts by mass of the polybutylene terephthalate resin (A), and which satisfies the following formula 1: (-15.4×b)+19.3≦a≦(-57.4×b)+59.3 Equation 1 (In formula 1, a represents the amount of carbodiimide groups (meq / kg) per 1 kg of the polybutylene terephthalate resin composition, and b represents the intrinsic viscosity (dL / g) of the polybutylene terephthalate resin (A).) Another embodiment of the present invention relates to a molded article obtained using the polybutylene terephthalate resin composition of the above embodiment. Effect of the Invention

[0008] According to an embodiment of the present invention, it is possible to provide a polybutylene terephthalate resin composition that has excellent hydrolysis resistance and fluidity during molding, and in which changes in fluidity during production and molding of the resin composition are suppressed, and a molded article obtained using the same. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Preferred embodiments of the present invention will be described below, but the present invention is not limited to the following embodiments.

[0010] <Polybutylene terephthalate resin composition> The polybutylene terephthalate resin composition according to an embodiment of the present invention contains at least a polybutylene terephthalate resin (A) and a cyclic carbodiimide compound (B).

[0011] [Polybutylene terephthalate resin (A)] The PBT resin (A) contains at least terephthalic acid or its ester-forming derivative (C 1-6 It is a resin obtained by polycondensation of a dicarboxylic acid component containing an alkylene glycol having at least 4 carbon atoms (such as an alkyl ester or acid halide of the alkylene glycol) and a glycol component containing an alkylene glycol having at least 4 carbon atoms (such as an acetylated product) or an ester-forming derivative thereof. The PBT resin (A) is not limited to a homopolybutylene terephthalate resin, and may be a copolymer containing 60 mol % or more (particularly 75 mol % to 95 mol %) of butylene terephthalate units. Furthermore, 1,4-butanediol and terephthalic acid or terephthalic acid alkyl ester, which are the raw materials for the PBT resin (A), may be derived from either fossil resources or biomass resources. The PBT resin (A) can be used alone or in combination of two or more.

[0012] The amount of terminal carboxyl groups in the PBT resin (A) is preferably 25 meq / kg or less, more preferably 20 meq / kg or less, and even more preferably 15 meq / kg or less, from the viewpoint of hydrolysis resistance. The amount of terminal carboxyl groups in the PBT resin (A) is preferably 2 meq / kg or more, and more preferably 3 meq / kg or more, from the viewpoint of adhesion to fillers and the like and compatibility with additives. The amount of terminal carboxyl groups in the PBT resin (A) is, for example, preferably 2 to 25 meq / kg, more preferably 3 to 20 meq / kg, and even more preferably 3 to 15 meq / kg.

[0013] The intrinsic viscosity (IV) of the PBT resin (A) is preferably a value that satisfies formula 1. Formula 1 will be described later. The intrinsic viscosity (IV) of the PBT resin (A) is preferably 0.6 to 1.2 dL / g, more preferably 0.7 to 0.9 dL / g, and even more preferably 0.7 to 0.85 dL / g. The intrinsic viscosity can also be adjusted by blending PBT resins having different intrinsic viscosities. For example, a PBT resin having an intrinsic viscosity of 0.85 dL / g can be prepared by blending a PBT resin having an intrinsic viscosity of 1.00 dL / g with a PBT resin having an intrinsic viscosity of 0.80 dL / g. The intrinsic viscosity (IV) of the PBT resin (A) can be measured, for example, in o-chlorophenol at a temperature of 35°C.

[0014] In the PBT resin (A), examples of the dicarboxylic acid component (comonomer component) other than terephthalic acid and its ester-forming derivatives include C terephthalic acid, phthalic acid, 2,6-naphthalenedicarboxylic acid, 4,4'-dicarboxydiphenyl ether, etc. 8-14 Aromatic dicarboxylic acids; succinic acid, adipic acid, azelaic acid, sebacic acid, etc. 4-16 Alkanedicarboxylic acids such as cyclohexanedicarboxylic acid, etc. 5-10 Cycloalkanedicarboxylic acids; ester-forming derivatives of these dicarboxylic acid moieties (C 1-6These dicarboxylic acid components can be used alone or in combination of two or more.

[0015] Among these dicarboxylic acid components, C 8-12 Aromatic dicarboxylic acids such as adipic acid, azelaic acid, and sebacic acid 6-12 The alkanedicarboxylic acids of the formula (I) are more preferred.

[0016] In the PBT resin (A), examples of glycol components (comonomer components) other than 1,4-butanediol include C glycols such as ethylene glycol, propylene glycol, trimethylene glycol, 1,3-butylene glycol, hexamethylene glycol, neopentyl glycol, and 1,3-octanediol. 2-10 alkylene glycols; polyoxyalkylene glycols such as diethylene glycol, triethylene glycol, and dipropylene glycol; alicyclic diols such as cyclohexanedimethanol and hydrogenated bisphenol A; aromatic diols such as bisphenol A and 4,4'-dihydroxybiphenyl; C diols of bisphenol A such as 2-mol ethylene oxide adduct of bisphenol A and 3-mol propylene oxide adduct of bisphenol A 2-4 or ester-forming derivatives of these glycols (acetylated products, etc.). These glycol components can be used alone or in combination of two or more.

[0017] Among these glycol components, C ethylene glycol, trimethylene glycol, etc. 2-6More preferred are alkylene glycols such as 1,2-dimethylphenyl, polyoxyalkylene glycols such as diethylene glycol, and alicyclic diols such as cyclohexanedimethanol. Examples of comonomer components that can be used in addition to the dicarboxylic acid component and the glycol component include aromatic hydroxycarboxylic acids such as 4-hydroxybenzoic acid, 3-hydroxybenzoic acid, 6-hydroxy-2-naphthoic acid, and 4-carboxy-4'-hydroxybiphenyl; aliphatic hydroxycarboxylic acids such as glycolic acid and hydroxycaproic acid; C hydroxycarboxylic acids such as propiolactone, butyrolactone, valerolactone, and caprolactone (ε-caprolactone, etc.); 3-12 Lactones; ester-forming derivatives of these comonomer components (C 1-6 Examples of the alkyl ester derivatives, acid halides, acetylated derivatives, etc. of the above-mentioned compounds include the above-mentioned compounds.

[0018] Any of the polybutylene terephthalate copolymers obtained by copolymerizing the comonomer components described above can be suitably used as the PBT resin (A). In addition, a homopolybutylene terephthalate polymer and a polybutylene terephthalate copolymer may be used in combination as the PBT resin (A).

[0019] As the PBT resin (A), for example, a recycled product may be used. As the PBT resin (A), for example, market collected products can be used (material recycling). In addition, PBT resins produced by decomposing 1,4-butanediol, terephthalic acid, etc. from PBT resin waste to the monomer level (chemical recycling) and polycondensing the obtained raw materials can also be used.

[0020] [Cyclic carbodiimide compound (B)] In the present disclosure, the cyclic carbodiimide compound (B) is a compound containing a carbodiimide group present in a cyclic structure, more specifically, a compound containing a cyclic structure formed by linking two nitrogen atoms of the carbodiimide group with a linking group.

[0021] The cyclic carbodiimide compound (B) may contain one or more cyclic structures containing a carbodiimide group. The number of atoms directly constituting the cyclic structure containing a carbodiimide group is not particularly limited. For example, the number of atoms directly constituting the cyclic structure, including the carbon and nitrogen atoms of the carbodiimide group, is preferably 8 or more, more preferably 10 or more. The number of atoms directly constituting the cyclic structure is preferably 50 or less, more preferably 30 or less, even more preferably 20 or less, and even more preferably 15 or less. The number of atoms directly constituting the cyclic structure may be, for example, 8 to 50, 8 to 30, 10 to 20, or 10 to 15.

[0022] The number of carbodiimide groups in the cyclic structure containing the carbodiimide group is preferably 1. The cyclic carbodiimide compound (B) may contain, for example, only one cyclic structure containing only one carbodiimide group, or may contain two or more cyclic structures containing only one carbodiimide group.

[0023] The cyclic carbodiimide compound (B) can be represented, for example, by the following formula (1).

[0024] [ka]

[0025] In formula (1), L represents a linking group. L may include, for example, an aliphatic group, an alicyclic group, and / or an aromatic group. L may include a heteroatom, and may include a structure in which, for example, aliphatic groups, alicyclic groups, and / or aromatic groups are linked by a heteroatom. Examples of heteroatoms include an oxygen atom, a nitrogen atom, a sulfur atom, and a phosphorus atom. L may be linear or may include a branched structure. L may include a cyclic structure. For example, L may further have a second cyclic structure containing one or more atoms of the atoms directly constituting the main chain of L, and for example, such a second cyclic structure may further include a carbodiimide group.

[0026] In L, the number of atoms directly constituting a cyclic structure together with the carbodiimide group is not particularly limited. For example, in L, the number of atoms directly constituting a cyclic structure together with the carbodiimide group is preferably 5 or more, more preferably 7 or more. In addition, in L, the number of atoms directly constituting a cyclic structure together with the carbodiimide group is preferably 47 or less, more preferably 27 or less, even more preferably 17 or less, and even more preferably 12 or less. In L, the number of atoms directly constituting a cyclic structure together with the carbodiimide group may be, for example, 5 to 47, 5 to 27, 7 to 17, or 7 to 12.

[0027] L may include, for example, a di- to tetravalent aliphatic group having 1 to 20 carbon atoms, a di- to tetravalent alicyclic group having 3 to 20 carbon atoms, a di- to tetravalent aromatic group having 5 to 15 carbon atoms, or a combination thereof.

[0028] Examples of the divalent to tetravalent aliphatic group having 1 to 20 carbon atoms include alkylene groups having 1 to 20 carbon atoms, such as a methylene group, an ethylene group, a propylene group, a butylene group, a pentylene group, a hexylene group, a heptylene group, an octylene group, a nonylene group, a decylene group, a dodecylene group, a hexadecylene group, a heptadecylene group, an octadecylene group, a nonadecylene group, and an eicosylene group; a methanetriyl group, an ethanetriyl group, a propanetriyl group, a butanetriyl group, a pentanetriyl group, a hexanetriyl group, a heptanetriyl group, an octanetriyl group, a nonanetriyl group, a decatriyl group, a cyclohex ... and alkanetriyl groups having 1 to 20 carbon atoms, such as a methanetetrayl group, an ethanetetrayl group, a propanetetrayl group, a butanetetrayl group, a pentanetetrayl group, a hexanetetrayl group, a heptanetetrayl group, an octanetetrayl group, a nonanetetrayl group, a decanetetrayl group, a dodecanetetrayl group, a hexadecanetetrayl group, and an octadecanetetrayl group. Examples of the divalent to tetravalent alicyclic group having 3 to 20 carbon atoms include a cycloalkylene group, a cycloalkanetriyl group, and a cycloalkanetetrayl group.

[0029] Examples of divalent to tetravalent aromatic groups having 5 to 15 carbon atoms include arylene groups such as a phenylene group and a naphthalenediyl group; arenetriyl groups such as a benzenetriyl group and a naphthalenetriyl group; and arenetetrayl groups such as a benzenetetrayl group and a naphthalenetetrayl group.

[0030] In formula (1), L preferably contains one or more selected from the group consisting of a substituted or unsubstituted arylene group such as a substituted or unsubstituted phenylene group, a heteroatom such as an oxygen atom, and a substituted or unsubstituted alkylene group. L may contain, for example, a substituted or unsubstituted arylene group such as a substituted or unsubstituted phenylene group, a heteroatom such as an oxygen atom, and a substituted or unsubstituted alkylene group.

[0031] For example, L may be a linking group represented by the following formula (2). *-Ar 1 -OXO-Ar 2 -* (2)

[0032] In formula (2), Ar 1 and Ar 2 are each independently an arylene group, and may be, for example, a substituted or unsubstituted phenylene group. When the phenylene group has a substituent, examples of the substituent include an alkyl group having 1 to 20 carbon atoms. X is a divalent linking group, and examples of X include a substituted or unsubstituted alkylene group. In formula (2), * indicates a bonding site with a nitrogen atom of a carbodiimide group.

[0033] When X is an unsubstituted alkylene group, X can be, for example, -(CH2) n n is preferably 1 to 6, more preferably 1 to 4, and may be 2, for example. When X is an alkylene group having a substituent, examples of X include a group represented by the following formula (3).

[0034] [ka]

[0035] In formula (3), * indicates a bonding site with the oxygen atom of formula (2). In formula (3), p and q are each preferably an integer of 1 to 3, more preferably 1 or 2, and may be, for example, 1. A and B are each independently a substituent or a hydrogen atom (excluding the case where A and B are both hydrogen atoms), or A and B may be bonded to each other to form a cyclic structure together with the carbon atom to which A and B are bonded. Examples of the substituent include an alkyl group having 1 to 20 carbon atoms. When A and B are bonded to each other to form a cyclic structure together with the carbon atom to which A and B are bonded, for example, X may be a group represented by the following formula (4), etc.

[0036] [ka]

[0037] In formula (4), * indicates a bonding site with the oxygen atom of formula (2). M is a group formed by mutual bonding of A and B of formula (3), and both ends of M form a ring structure together with the carbon atoms to which they are bonded. M may be, for example, a group represented by the following formula (5), etc.

[0038] *-(CH2) r -O-Ar 3 -N=C=N-Ar 4 -O-(CH2) s -* (5) In formula (5), * denotes an end of M and indicates a bonding site with a carbon atom. Each of r and s is preferably an integer of 1 to 3, more preferably 1 or 2, and may be, for example, 1. Ar 3 and Ar 4are each independently an arylene group, and may be, for example, a substituted or unsubstituted phenylene group. When the phenylene group has a substituent, examples of the substituent include an alkyl group having 1 to 20 carbon atoms.

[0039] A specific example of the cyclic carbodiimide compound is a compound represented by formula (1), in which L is a linking group represented by formula (2), and Ar 1 and Ar 2 are each independently a substituted or unsubstituted phenylene group, and X is -(CH2)2-; a compound represented by formula (1), in which L is a linking group represented by formula (2), and Ar 1 and Ar 2 are each independently a substituted or unsubstituted phenylene group, X is a linking group represented by formula (4), p and q are each 1, M is a group represented by formula (5), r and s are each 1, Ar 3 and Ar 4 are each independently a substituted or unsubstituted phenylene group.

[0040] The cyclic carbodiimide compound (B) may be contained in the PBT resin composition either alone or in combination of two or more kinds. In the PBT resin composition, the amount of the cyclic carbodiimide compound (B) is preferably 0.1 to 5 parts by mass, more preferably 0.2 to 1 part by mass, and more preferably 0.2 to 0.5 parts by mass, relative to 100 parts by mass of the PBT resin.

[0041] When a cyclic carbodiimide compound is used, the viscosity of the resin increases during injection molding, the flowability decreases, and there are cases where good molded products cannot be obtained due to poor filling. From the viewpoint of improving hydrolysis resistance and of improving the viscosity during injection molding and thereby obtaining good moldability, it is preferable that the intrinsic viscosity of the PBT resin (A) and the amount of carbodiimide groups per kg of the PBT resin composition satisfy the following formula 1. (-15.4×b)+19.3≦a≦(-57.4×b)+59.3 Equation 1

[0042] In formula 1, a represents the amount of carbodiimide groups (meq / kg) per 1 kg of the PBT resin composition, and b represents the intrinsic viscosity (dL / g) of the PBT resin (A).

[0043] From the viewpoint of improving hydrolysis resistance, the PBT resin composition preferably satisfies (-15.4 x b) + 19.3 ≦ a, and more preferably satisfies (-15.4 x b) + 20.3 ≦ a.

[0044] From the viewpoint of achieving good fluidity during injection molding and thereby good moldability, the PBT resin composition preferably satisfies a≦(−57.4×b)+59.3, and more preferably satisfies a≦(−57.4×b)+58.3.

[0045] [Other ingredients] The PBT resin composition may contain other components as necessary, such as, for example, a hydroxyl-containing compound which is a polyhydric alcohol or a partial ester thereof, an inorganic filler, an antioxidant, a weather stabilizer, a molecular weight regulator, an ultraviolet absorber, an antistatic agent, a dye, a pigment, a lubricant, a crystallization accelerator, a crystal nucleating agent, a near-infrared absorber, a flame retardant, a flame retardant assistant, an organic filler, and a colorant, but is not limited thereto.

[0046] Examples of the hydroxyl group-containing compound which is a polyhydric alcohol or a partial ester thereof include a polyhydric alcohol or a partial ester thereof, which has a hydroxyl group value of 200 or more, and a hydroxyl group-containing compound (C-1) (hereinafter also referred to as "polyhydric hydroxyl group-containing compound (C-1)"); and a hydroxyl group-containing compound (C-2) (hereinafter also referred to as "hydroxyl group-containing compound (C-2)") which is a polyhydric alcohol or a partial ester thereof, which has a hydroxyl group value of 10 or more and less than 200.

[0047] The polyhydroxyl group-containing compound (C-1) is a compound having two or more hydroxyl groups in one molecule and a hydroxyl value of 200 or more.

[0048] In this specification, the hydroxyl value refers to one measured according to Japan Oil Chemists' Society Method 2.3.6.2-1996 (pyridine-acetic anhydride method) (Standard Test Method for Analysis of Fats, Oils and Related Materials established by Japan Oil Chemists' Society).

[0049] In the polyhydric hydroxyl group-containing compound (C-1), examples of the polyhydric alcohol include ethylene glycol, propylene glycol, 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol, diethylene glycol, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, trimethylolmethane, pentaerythritol, dipentaerythritol, tripentaerythritol, and various sorbitols.

[0050] In the polyhydric hydroxyl group-containing compound (C-1), examples of the fatty acid that is the partial ester of the polyhydric alcohol include fatty acids having 12 or more carbon atoms, such as lauric acid, oleic acid, palmitic acid, stearic acid, 12-hydroxystearic acid, behenic acid, and montanic acid.

[0051] Examples of the polyhydric hydroxyl group-containing compound (C-1) include ethers obtained by addition polymerization of alkylene oxide to glycerin fatty acid esters or diglycerin. Specific examples of glycerin fatty acid esters include glycerin monostearate, glycerin monobehenate, diglycerin monostearate, triglycerin monostearate, triglycerin stearic acid partial ester, tetraglycerin stearic acid partial ester, decaglycerin lauric acid partial ester, glycerin mono 12-hydroxystearate, etc. Examples of ethers obtained by addition polymerization of alkylene oxide to diglycerin include polyoxypropylene diglyceryl ether, polyoxyethylene diglyceryl ether, etc.

[0052] From the viewpoint of flowability, the PBT resin composition may contain a polyvalent hydroxyl group-containing compound (C-1). The PBT resin composition may contain one type of polyvalent hydroxyl group-containing compound (C-1) alone or two or more types in combination. The PBT resin composition may not contain a polyvalent hydroxyl group-containing compound (C-1).

[0053] From the viewpoint of suppressing changes in flowability during production or molding of the resin composition, the amount of polyvalent hydroxyl group-containing compound (C-1) is preferably less than 0.05 parts by mass relative to 100 parts by mass of PBT resin. In other words, it is preferable that the PBT resin composition does not contain a polyvalent hydroxyl group-containing compound (C-1) or contains the polyvalent hydroxyl group-containing compound (C-1) in an amount of less than 0.05 parts by mass relative to 100 parts by mass of PBT resin. The amount of the polyhydric hydroxyl group-containing compound (C-1) is more preferably 0.045 parts by mass or less, and even more preferably 0.040 parts by mass or less, based on 100 parts by mass of the PBT resin. When the polyhydric hydroxyl group-containing compound (C-1) is contained in the PBT resin composition, the amount of the polyhydric hydroxyl group-containing compound (C-1) may be, for example, 0.010 parts by mass or more and less than 0.05 parts by mass, 0.010 to 0.045 parts by mass, or 0.010 to 0.040 parts by mass, per 100 parts by mass of the PBT resin.

[0054] The "hydroxyl group-containing compound (C-2)" is a compound having one or more hydroxyl groups in one molecule and a hydroxyl value of 10 or more and less than 200.

[0055] Examples of the polyhydric alcohol in the hydroxyl group-containing compound (C-2) include ethylene glycol, propylene glycol, 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol, diethylene glycol, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, trimethylolmethane, pentaerythritol, dipentaerythritol, tripentaerythritol, and various sorbitols. In the hydroxyl group-containing compound (C-2), examples of the fatty acid that is the partial ester of the polyhydric alcohol include fatty acids having 12 or more carbon atoms, such as lauric acid, oleic acid, palmitic acid, stearic acid, 12-hydroxystearic acid, behenic acid, and montanic acid. Examples of the hydroxyl group-containing compound (C-2) include ethylene glycol monostearate, ethylene glycol monobehenate, ethylene glycol monomontanate, diglycerol monostearate, glycerol stearate partial ester, diglycerol stearate partial ester, triglycerol stearate partial ester, oleic acid monoglyceride, propylene glycol monobehenate, propylene glycol monomontanate, pentaerythritol monooleate, sorbitan tristearate, and sorbitan trioleate.

[0056] From the viewpoint of fluidity, the PBT resin composition may contain a hydroxyl group-containing compound (C-2). The PBT resin composition may contain one type of hydroxyl group-containing compound (C-2) alone or two or more types in combination. The PBT resin composition may not contain a hydroxyl group-containing compound (C-2). The amount of the hydroxyl group-containing compound (C-2) is, for example, preferably from 0.01 to 5 parts by mass, and more preferably from 0.05 to 1 part by mass, relative to 100 parts by mass of the PBT resin.

[0057] [Polybutylene terephthalate resin composition] The PBT resin composition of the embodiment has excellent hydrolysis resistance, and can suppress the decrease in toughness after storage under high temperature and high humidity conditions. For example, the PBT resin composition has a tensile breaking strain of preferably 4% or more, more preferably 5% or more, after 60 hours of treatment under conditions of 121°C and 100Rh. The tensile breaking strain after 60 hours of treatment under conditions of 121°C and 100Rh can be measured by the method described in the examples.

[0058] The PBT resin composition of the embodiment can achieve good fluidity during injection molding. For example, the PBT resin composition is subjected to injection molding at 260°C, a residence time of 9 minutes, and a shear rate of 1000 sec according to ISO11443. -1 The melt viscosity at a residence time of 9 minutes (hereinafter also referred to as "melt viscosity at a residence time of 9 minutes") can be an index of fluidity during injection molding. From the viewpoint of good fluidity during injection molding, the melt viscosity at a residence time of 9 minutes is preferably 0.25 kPa s or less, and more preferably 0.22 kPa s or less. The melt viscosity at a residence time of 9 minutes can be measured by the method described in the Examples.

[0059] The PBT resin composition of the embodiment can suppress changes in flowability during production and molding of the resin composition. For example, the PBT resin composition can be molded at 260°C, a residence time of 3.5 minutes, and a shear rate of 1000 sec according to ISO11443. -1 The melt viscosity at 260°C, residence time 9 minutes, shear rate 1000 sec. -1 The difference between the melt viscosity at a residence time of 3.5 minutes and the melt viscosity at a residence time of 9 minutes (melt viscosity at a residence time of 3.5 minutes - melt viscosity at a residence time of 9 minutes) can be an index of changes in fluidity during production or molding of the resin composition. From the viewpoint of suppressing changes in fluidity during production or molding of the resin composition, the difference between the melt viscosity at a residence time of 3.5 minutes and the melt viscosity at a residence time of 9 minutes is preferably 0.025 kPa s or less, and more preferably 0.015 kPa s or less. The melt viscosity at a residence time of 3.5 minutes and the melt viscosity at a residence time of 9 minutes can each be measured by the method described in the Examples.

[0060] [Method of producing polybutylene terephthalate resin composition] The method for producing the PBT resin composition is not particularly limited, and any known method can be used, for example, a method in which each component is put into an extruder, melt-kneaded, and pelletized.

[0061] <Molded products> A molded article according to one embodiment of the present invention can be obtained by using the above-mentioned PBT resin composition.

[0062] The method for obtaining a molded article using the PBT resin composition is not particularly limited, and a known method can be adopted. For example, the PBT resin composition can be fed into an extruder, melt-kneaded, extruded, and pelletized, and the pellets can be fed into an injection molding machine equipped with a predetermined mold and injection molded to produce the molded article.

[0063] The molded article of the present embodiment can be suitably used as a molded article that is exposed to high temperature and high humidity environments for a long period of time, for example, in automobiles, trains, the aviation industry, etc. For example, since deterioration due to hydrolysis caused by use in a high temperature and high humidity environment can be prevented, it can be used for connectors, etc.

[0064] The embodiments of the present invention include the following, but the present invention is not limited to the following embodiments. <1> A polybutylene terephthalate resin (A) having a terminal carboxyl group amount of 25 meq / kg or less and a cyclic carbodiimide compound (B), the amount of a polyhydric alcohol or a partial ester thereof having a hydroxyl value of 200 or more and a polyhydric hydroxyl group-containing compound (C-1) is less than 0.05 parts by mass relative to 100 parts by mass of the polybutylene terephthalate resin (A); A polybutylene terephthalate resin composition satisfying the following formula 1: (-15.4×b)+19.3≦a≦(-57.4×b)+59.3 Equation 1 (In formula 1, a represents the amount of carbodiimide groups (meq / kg) per 1 kg of the polybutylene terephthalate resin composition, and b represents the intrinsic viscosity (dL / g) of the polybutylene terephthalate resin (A).) <2> The above-mentioned contains a hydroxyl group-containing compound (C-2) which is a polyhydric alcohol or a partial ester thereof and has a hydroxyl value of 10 or more and less than 200. <1> The polybutylene terephthalate resin composition according to claim 1. <3> The polyhydric alcohol or its partial ester is a polyhydric alcohol or a polyhydroxyl group-containing compound (C-1) having a hydroxyl value of 200 or more, and the polyhydric alcohol or its partial ester is contained in an amount of 0.010 to 0.045 parts by mass per 100 parts by mass of the polybutylene terephthalate resin (A). <1> or <2> The polybutylene terephthalate resin composition according to claim 1. <4> The above <1> ~ <3> A molded article obtained by using the polybutylene terephthalate resin composition according to any one of claims 1 to 5. EXAMPLES

[0065] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples.

[0066] <Production of polybutylene terephthalate resin composition> The compositions of the PBT resin compositions of the respective Examples and Comparative Examples are shown in the following Tables 1 and 2. The content of each component in Tables 1 and 2 is expressed in parts by mass. The components shown in Tables 1 and 2 were melt-kneaded and extruded in the ratios (parts by mass) shown in Tables 1 and 2 using a 30 mmφ twin-screw extruder (TEX30C, manufactured by Japan Steel Works, Ltd.) with a cylinder temperature of 230°C in the raw material supply section and 240 to 250°C in between, at a discharge rate of 15 kg / h and a screw rotation speed of 130 rpm, to obtain pellets of a PBT resin composition.

[0067] Details of each component in Tables 1 and 2 are as follows:

[0068] (1) PBT resin A-1: PBT resin manufactured by Polyplastics Co., Ltd. (intrinsic viscosity 0.676 dL / g, terminal carboxyl group amount 15 meq / kg) A-2: PBT resin (intrinsic viscosity 0.733 dL / g, terminal carboxyl group amount 14.1 meq / kg, manufactured by Polyplastics Co., Ltd.) A-3: PBT resin (intrinsic viscosity 0.733 dL / g, terminal carboxyl group amount 30 meq / kg, manufactured by Polyplastics Co., Ltd.) A-4: PBT resin (intrinsic viscosity 0.797 dL / g, terminal carboxyl group amount 13.1 meq / kg, manufactured by Polyplastics Co., Ltd.) A-5: PBT resin (intrinsic viscosity 0.822 dL / g, terminal carboxyl group amount 12.8 meq / kg, manufactured by Polyplastics Co., Ltd.) A-6: PBT resin (intrinsic viscosity 0.878 dL / g, terminal carboxyl group amount 12 meq / kg, manufactured by Polyplastics Co., Ltd.)

[0069] (2) Cyclic carbodiimide compounds B: Cyclic carbodiimide compound ("Carbodista TCC-NP" manufactured by Teijin Limited)

[0070] (3) Hydroxyl-containing compounds which are polyhydric alcohols or their partial esters (hydroxyl-containing compounds) C-1: Glycerin mono-12-hydroxystearate (hydroxyl value 420, Riken Vitamin Co., Ltd. "Rikemal HC-100") C-2: Propylene glycol monobehenate (hydroxyl value 145, Riken Vitamin Co., Ltd. "Rikemal PB-100")

[0071] In Tables 1 and 2, "a (meq / kg)" represents the amount of carbodiimide groups (meq / kg) per 1 kg of PBT resin composition, "b (dL / g)" represents the intrinsic viscosity (dL / g) of the PBT resin, and "c (meq / kg)" represents the amount of terminal carboxyl groups (meq / kg) of the PBT resin.

[0072] <Evaluation> The obtained PBT resin composition pellets were used for the following evaluations.

[0073] (1) Melt Viscosity As an index of fluidity during injection molding, the following conditions were met: 260°C, residence time 9 minutes, shear rate 1000 sec., in accordance with ISO11443. -1The melt viscosity at 260°C, residence time 3.5 minutes, shear rate 1000 sec was evaluated as an index of the change in fluidity during the production and molding of the resin composition. -1 (hereinafter and in Tables 1 and 2, this is also referred to as "melt viscosity at 3.5 minutes residence time") and the melt viscosity at 260°C, residence time 9 minutes, shear rate 1000 sec in accordance with ISO11443. -1 The difference between the melt viscosity at 9 min. residence time and the melt viscosity at 9 min. residence time was evaluated.

[0074] Specifically, the melt viscosity at a residence time of 3.5 minutes and at a residence time of 9 minutes were measured as follows: The pellets of the PBT resin composition obtained above were measured in accordance with ISO11443 using a Capillograph 1B (manufactured by Toyo Seiki Seisakusho Co., Ltd.) at a furnace temperature of 260°C, a capillary diameter of 1 mm x 20 mmL, and a shear rate of 1000 sec -1 The melt viscosity was measured under conditions of a residence time of 3.5 minutes and 9 minutes.

[0075] Tables 1 and 2 show the melt viscosity (kPa·s) at a residence time of 9 minutes. In addition, in Tables 1 and 2, the difference in melt viscosity between a residence time of 3.5 minutes and a residence time of 9 minutes (melt viscosity at a residence time of 3.5 minutes - melt viscosity at a residence time of 9 minutes) (kPa s) is shown using X and Y. Specifically, when the difference in melt viscosity between a residence time of 3.5 minutes and a residence time of 9 minutes is less than 0.025 kPa s, it is shown as X, and when it is 0.025 kPa s or more, it is shown as Y.

[0076] (2) Tensile fracture strain after heat and moisture treatment To evaluate hydrolysis resistance, the tensile breaking strain after wet heat treatment was measured. Specifically, the pellets of the PBT resin composition obtained above were dried at 140°C for 3 hours, and then injection molded at a cylinder temperature of 260°C and a mold temperature of 80°C to prepare 1A type tensile test pieces in accordance with ISO3167. The obtained test pieces were treated (wet heat treatment) for 60 hours under conditions of 121°C, 100% Rh, and 203 kPa using a pressure cooker (PCT) tester, and then the tensile breaking strain was measured in accordance with ISO527-1,2. A tensile breaking strain of 4% or more is considered to have good hydrolysis resistance.

[0077] [Table 1]

[0078] [Table 2]

[0079] As shown in Table 1, in Examples 1 to 8, good results were shown in the melt viscosity at a residence time of 9 minutes evaluated as an index of fluidity during molding, the difference between the melt viscosity at a residence time of 3.5 minutes and the melt viscosity at a residence time of 9 minutes evaluated as an index of change in fluidity during production and molding of the resin composition, and the tensile break strain after moist heat treatment evaluated as an index of hydrolysis resistance, and it can be seen that a PBT resin composition was obtained that was excellent in hydrolysis resistance and fluidity and in which changes in fluidity during production and molding of the resin composition were suppressed. Specifically, in all of Examples 1 to 8, the melt viscosity at a residence time of 9 minutes was 0.25 kPa·s or less, the difference between the melt viscosity at a residence time of 3.5 minutes and the melt viscosity at a residence time of 9 minutes was less than 0.025 kPa·s, and the tensile break strain after moist heat treatment was 4% or more.

[0080] In contrast, in Comparative Examples 1 and 2, which do not satisfy the formula 1 of "(-15.4 x b) + 19.3 ≦ a", and Comparative Example 5, in which a PBT resin having a terminal carboxyl group amount of more than 25 meq / kg was used, the tensile breaking strain after wet heat treatment was low. In Comparative Examples 3 and 4, which do not satisfy the formula 1 of "a ≦ (-57.4 x b) + 59.3", the melt viscosity at a residence time of 9 minutes was high. In Comparative Example 6, in which a resin composition was used in which glycerin mono-12-hydroxystearate, which is a polyhydric alcohol or its partial ester and is a polyhydric hydroxyl group-containing compound (C-1) having a hydroxyl value of 200 or more, was contained in an amount of 0.06 parts by mass per 100 parts by mass of PBT resin, the difference between the melt viscosity at a residence time of 3.5 minutes and the melt viscosity at a residence time of 9 minutes was large.

Claims

1. The present invention comprises a polybutylene terephthalate resin (A) having a terminal carboxyl group amount of 25 meq / kg or less, and a cyclic carbodiimide compound (B), the amount of a polyhydric alcohol or a partial ester thereof having a hydroxyl value of 200 or more and a polyhydric hydroxyl group-containing compound (C-1) is less than 0.05 parts by mass relative to 100 parts by mass of the polybutylene terephthalate resin (A); A polybutylene terephthalate resin composition satisfying the following formula 1. (-15.4×b)+19.3≦a≦(-57.4×b)+59.3 Formula 1 (In formula 1, a represents the amount of carbodiimide groups (meq / kg) per 1 kg of the polybutylene terephthalate resin composition, and b represents the intrinsic viscosity (dL / g) of the polybutylene terephthalate resin (A).)

2. The polybutylene terephthalate resin composition according to claim 1, comprising a hydroxyl group-containing compound (C-2) which is a polyhydric alcohol or a partial ester thereof and has a hydroxyl value of 10 or more and less than 200.

3. The polybutylene terephthalate resin composition according to claim 1, comprising 0.010 to 0.045 parts by mass of the polyhydric alcohol or a partial ester thereof having a hydroxyl value of 200 or more, based on 100 parts by mass of the polybutylene terephthalate resin (A).

4. A molded article obtained by using the polybutylene terephthalate resin composition according to any one of claims 1 to 3.

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