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] Embodiments of the present invention relate to a polybutylene terephthalate resin composition and a molded article.

Background Art

[0002] Polybutylene terephthalate resin (hereinafter also referred to as "PBT resin") is excellent in mechanical properties, electrical properties, other physical properties, and chemical properties, and has good processability. Therefore, as an engineering plastic, it is used in a wide range of applications such as automotive parts and electrical and electronic parts. PBT resin is particularly used preferably in applications such as a case material for housing a substrate on which electronic components are mounted, an insert molded article containing a sensor case, a connector terminal, etc., and an actuator case for protecting gears, motors, etc. for the purpose of protecting against damage caused by external moisture, dust, or impact.

[0003] On the other hand, since PBT resin has an ester group in its molecule, it tends to undergo hydrolysis in a high-temperature and high-humidity environment, and physical properties such as toughness may decrease due to hydrolysis. Therefore, when its molded article is used in an environment with severe temperature changes such as in an engine room of an automobile or outdoors, improvement of hydrolysis resistance is desired.

[0004] As a method for improving the hydrolysis resistance of PBT resin, for example, it is known to add a carbodiimide compound. On the other hand, a carbodiimide compound may cause the generation of isocyanate gas 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 polyhydric 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 Problems to be Solved by the Invention

[0006] In addition to improving hydrolysis resistance, it is desirable that the polybutylene terephthalate resin composition has good fluidity during molding from the viewpoint of good moldability. Further, from the viewpoint of the control during the production or molding of the resin composition, it is desired that the fluidity of the resin composition during production or molding does not change significantly. An embodiment of the present invention is to provide a polybutylene terephthalate resin composition excellent in hydrolysis resistance and fluidity during molding, and in which changes in fluidity during production or molding of the resin composition are suppressed, and a molded article obtained using the same. Means for Solving the Problems

[0007] One embodiment of the present invention includes a polybutylene terephthalate resin (A) having an amount of terminal carboxyl groups of 25 meq / kg or less, and a cyclic carbodiimide compound (B), and with respect to 100 parts by mass of the polybutylene terephthalate resin (A), a polyhydric hydroxyl group-containing compound (C-1) which is a polyhydric alcohol or a partial ester thereof and has a hydroxyl value of 200 or more is less than 0.05 part by mass, and relates to 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).) Another embodiment of the present invention relates to a molded article obtained using the polybutylene terephthalate resin composition of the above embodiment. Effects of the Invention

[0008] According to an embodiment of the present invention, there can be provided a polybutylene terephthalate resin composition excellent in hydrolysis resistance and fluidity during molding, and in which changes in fluidity during the production or molding of the resin composition are suppressed, and a molded article obtained using the same.

Mode for Carrying Out the Invention

[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) is a resin obtained by polycondensing a dicarboxylic acid component containing at least terephthalic acid or its ester-forming derivative (such as an alkyl ester or acid halide of C 1-6 ), and a glycol component containing at least an alkylene glycol having 4 carbon atoms (1,4-butanediol) or its ester-forming derivative (such as an acetylated product). 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% or more and 95 mol% or less) of butylene terephthalate units. In addition, 1,4-butanediol and terephthalic acid or an alkyl terephthalate, which are raw materials of 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. From the viewpoints of adhesion to fillers and compatibility with additives, 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. The amount of terminal carboxyl groups in the PBT resin (A) is preferably, for example, 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, which 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. Also, PBT resins having different intrinsic viscosities can be blended to adjust the intrinsic viscosity. For example, a PBT resin with an intrinsic viscosity of 1.00 dL / g and a PBT resin with an intrinsic viscosity of 0.80 dL / g can be blended to prepare a PBT resin with an intrinsic viscosity of 0.85 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 aromatic dicarboxylic acids such as isophthalic acid, phthalic acid, 2,6-naphthalenedicarboxylic acid, 4,4'-dicarboxydiphenyl ether, etc. 8-14 alkanedicarboxylic acids such as succinic acid, adipic acid, azelaic acid, sebacic acid, etc. 4-16 cycloalkanedicarboxylic acids such as cyclohexanedicarboxylic acid, etc. 5-10 ester-forming derivatives of these dicarboxylic acid components (C 1-6Examples thereof include alkyl ester derivatives and acid halides. These dicarboxylic acid components can be used alone or in combination of two or more.

[0015] Among these dicarboxylic acid components, aromatic dicarboxylic acids such as isophthalic acid having C 8-12 and alkanedicarboxylic acids such as adipic acid, azelaic acid, and sebacic acid having C 6-12 are more preferred.

[0016] In the PBT resin (A), examples of the glycol component (comonomer component) other than 1,4-butanediol include C 2-10 alkylene glycols such as ethylene glycol, propylene glycol, trimethylene glycol, 1,3-butylene glycol, hexamethylene glycol, neopentyl glycol, and 1,3-octanediol; 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 2-4 alkylene oxide adducts of bisphenol A such as 2-mole ethylene oxide adduct of bisphenol A and 3-mole propylene oxide adduct of bisphenol A; or ester-forming derivatives (such as acetylated products) of these glycols. These glycol components can be used alone or in combination of two or more.

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

[0018] All of the polybutylene terephthalate copolymers copolymerized with the comonomer components described above can be suitably used as the PBT resin (A). Also, as the PBT resin (A), a homopolybutylene terephthalate polymer and a polybutylene terephthalate copolymer may be used in combination.

[0019] As the PBT resin (A), for example, recycled products may be used. As the PBT resin (A), for example, market-returned products can be used (material recycling). Also, PBT resins produced by depolymerizing 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, it is 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) can contain one or two 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 containing the carbon and nitrogen atoms of the carbodiimide group is preferably 8 or more, more preferably 10 or more. Also, the number of atoms directly constituting the cyclic structure is preferably 50 or less, more preferably 30 or less, still more preferably 20 or less, and even more preferably 15 or less. The number of atoms directly constituting the cyclic structure can 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 a carbodiimide group is preferably 1. The cyclic carbodiimide compound (B) may contain, for example, only one cyclic structure containing only one carbodiimide group, or two or more.

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

[0024]

Chemical formula

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

[0026] In L, the number of atoms directly constituting the cyclic structure together with the carbodiimide group is not particularly limited. For example, in L, the number of atoms directly constituting the cyclic structure together with the carbodiimide group is preferably 5 or more, more preferably 7 or more. Further, in L, the number of atoms directly constituting the cyclic structure together with the carbodiimide group is preferably 47 or less, more preferably 27 or less, still more preferably 17 or less, and even more preferably 12 or less. In L, the number of atoms directly constituting the 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 divalent to tetravalent aliphatic group having 1 to 20 carbon atoms, a divalent to tetravalent alicyclic group having 3 to 20 carbon atoms, a divalent 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 methylene group, ethylene group, propylene group, butylene group, pentylene group, hexylene group, heptylene group, octylene group, nonylene group, decylene group, dodecylene group, hexadecylene group, heptadecylene group, octadecylene group, nonadecylene group, and eicosylene group; alkanetriyl groups having 1 to 20 carbon atoms such as methanetriyl group, ethanetriyl group, propanetriyl group, butanetriyl group, pentanetriyl group, hexanetriyl group, heptanetriyl group, octanetriyl group, nonanetriyl group, decanetriyl group, dodecanetriyl group, hexadecanetriyl group, heptadecanetriyl group, and octadecanetriyl group; and alkanetetrayl groups having 1 to 20 carbon atoms such as methanetetrayl group, ethanetetrayl group, propanetetrayl group, butanetetrayl group, pentanetetrayl group, hexanetetrayl group, heptanetetrayl group, octanetetrayl group, nonanetetrayl group, decanetetrayl group, dodecanetetrayl group, hexadecanetetrayl group, and octadecanetetrayl group. Examples of the 2- to 4-valent alicyclic group having 3 to 20 carbon atoms include a cycloalkylene group, a cycloalkanetriyl group, and a cycloalkanetetrayl group.

[0029] Examples of the 2- to 4-valent aromatic group 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 an 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 include, for example, an 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 -O-X-O-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. Examples of the substituent when the phenylene group has a 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), * each indicates a bonding site with the nitrogen atom of the carbodiimide group.

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

[0034]

Chemical formula

[0035] In formula (3), * indicates the bonding site with the oxygen atom of formula (2) respectively. 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 (however, excluding the case where both A and B are hydrogen atoms), or A and B are bonded to each other, and may 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 and 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).

[0036]

Chemical formula

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

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

[0039] Specific examples of the cyclic carbodiimide compound include, for example, a compound represented by formula (1). In formula (1), 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 formula (1), 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, and Ar 3 and Ar 4 are each independently a substituted or unsubstituted phenylene group, and the like.

[0040] The cyclic carbodiimide compound (B) may be contained alone in the PBT resin composition, or a combination of two or more may be contained. 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 preferably 0.2 to 0.5 part by mass with respect to 100 parts by mass of the PBT resin.

[0041] When a cyclic carbodiimide compound is used, the viscosity of the resin may increase during injection molding, the fluidity may decrease, and a good molded product may not be obtained due to filling defects. From the viewpoint of improving hydrolysis resistance and making the viscosity during injection molding good, thereby obtaining good moldability, it is preferable that the intrinsic viscosity of the PBT resin (A) and the amount of carbodiimide groups per 1 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 Equation 1, a represents the amount of carbodiimide groups per kg of the PBT resin composition (meq / kg), and b represents the intrinsic viscosity (dL / g) of the PBT resin (A).

[0043] From the viewpoint of improving hydrolysis resistance, it is preferable that the PBT resin composition satisfies (-15.4 × b) + 19.3 ≤ a, and more preferably satisfies (-15.4 × b) + 20.3 ≤ a.

[0044] From the viewpoint of obtaining good fluidity during injection molding and thereby good moldability, it is preferable that the PBT resin composition satisfies a ≤ (-57.4 × b) + 59.3, and more preferably satisfies a ≤ (-57.4 × b) + 58.3.

[0045] [Other Components] The PBT resin composition can contain other components as needed. Examples of other components include hydroxyl group-containing compounds that are polyhydric alcohols or their partial esters, inorganic fillers, antioxidants, weather stabilizers, molecular weight regulators, ultraviolet absorbers, antistatic agents, dyes, pigments, lubricants, crystallization accelerators, crystal nucleating agents, near-infrared absorbers, flame retardants, flame retardant aids, organic fillers, colorants, etc., but are not limited thereto.

[0046] Examples of the hydroxyl group-containing compounds that are polyhydric alcohols or their partial esters include polyhydric hydroxyl group-containing compounds (C-1) having a hydroxyl value of 200 or more that are polyhydric alcohols or their partial esters (hereinafter also referred to as "polyhydric hydroxyl group-containing compounds (C-1)"), and hydroxyl group-containing compounds (C-2) having a hydroxyl value of 10 or more and less than 200 that are polyhydric alcohols or their partial esters (hereinafter also referred to as "hydroxyl group-containing compounds (C-2)").

[0047] The polyhydric hydroxyl 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 the value measured by the Japanese Oil Chemists' Society method 2.3.6.2-1996 (pyridine / acetic anhydride method) (Standard Oil Analysis Test Method established by the Japanese 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, various sorbitols, and the like.

[0050] In the polyhydric hydroxyl group-containing compound (C-1), examples of the fatty acid of 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 glycerin fatty acid esters or ethers obtained by addition polymerization of alkylene oxide to diglycerin. Specific examples of the glycerin fatty acid ester include, for example, 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, and the like. Examples of the ether obtained by addition polymerization of alkylene oxide to diglycerin include polyoxypropylene diglyceryl ether, polyoxyethylene diglyceryl ether, and the like.

[0052] From the perspective of fluidity, the PBT resin composition may contain a polyhydric hydroxyl group-containing compound (C-1). The PBT resin composition may contain the polyhydric hydroxyl group-containing compound (C-1) alone or in combination of two or more. The PBT resin composition may not contain the polyhydric hydroxyl group-containing compound (C-1).

[0053] From the perspective of suppressing changes in fluidity during the production or molding of the resin composition, the amount of the polyhydric hydroxyl group-containing compound (C-1) is preferably less than 0.05 parts by mass with respect to 100 parts by mass of the PBT resin. That is, the PBT resin composition preferably does not contain the polyhydric hydroxyl group-containing compound (C-1) or contains the polyhydric hydroxyl group-containing compound (C-1) in an amount less than 0.05 parts by mass with respect to 100 parts by mass of the 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 with respect to 100 parts by mass of the PBT resin. When the polyhydric hydroxyl group-containing compound (C-1) is contained in the PBT resin composition, its amount may be, for example, 0.010 parts by mass or more with respect to 100 parts by mass of the PBT resin composition. The polyhydric hydroxyl group-containing compound (C-1) may be contained, for example, in an amount of 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 with respect to 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, various sorbitols, and the like. In the hydroxyl group-containing compound (C-2), examples of the fatty acid of 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, diglycerin monostearate, glycerin stearic acid partial ester, diglycerin stearic acid partial ester, triglycerin stearic acid partial ester, oleic acid monoglyceride, propylene glycol monobehenate, propylene glycol monomontanate, pentaerythritol monooleate, sorbitan tristearate, sorbitan trioleate, and the like.

[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 the hydroxyl group-containing compound (C-2) alone or in combination of two or more. The PBT resin composition may not contain the hydroxyl group-containing compound (C-2). The amount of the hydroxyl group-containing compound (C-2) is preferably 0.01 to 5 parts by mass, more preferably 0.05 to 1 part by mass, based on 100 parts by mass of the PBT resin.

[0057] [Polybutylene terephthalate resin composition] The PBT resin composition of the embodiment is excellent in hydrolysis resistance, and can suppress, for example, a decrease in toughness after storage under high-temperature and high-humidity conditions. For example, the PBT resin composition preferably has a tensile fracture strain of 4% or more, more preferably 5% or more, after being treated under the conditions of 121°C and 100 Rh for 60 hours. The tensile fracture strain after being treated under the conditions of 121°C and 100 Rh for 60 hours 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 melt viscosity of the PBT resin composition at 260 °C, residence time of 9 minutes, and shear rate of 1000 sec in accordance with ISO11443 (hereinafter, also referred to as "melt viscosity at a residence time of 9 minutes") can be an index of the 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. -1 The melt viscosity at 260 °C, residence time of 9 minutes, and shear rate of 1000 sec in accordance with ISO11443 (hereinafter, also referred to as "melt viscosity at a residence time of 9 minutes") can be an index of the 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 fluidity during the production or molding of the resin composition. For example, the melt viscosity at 260 °C, residence time of 3.5 minutes, and shear rate of 1000 sec in accordance with ISO11443 (hereinafter, also referred to as "melt viscosity at a residence time of 3.5 minutes") and the melt viscosity at 260 °C, residence time of 9 minutes, and shear rate of 1000 sec in accordance with ISO11443 -1 The difference between the melt viscosity at 260 °C, residence time of 3.5 minutes, and shear rate of 1000 sec in accordance with ISO11443 (hereinafter, also referred to as "melt viscosity at a residence time of 3.5 minutes") and the melt viscosity at 260 °C, residence time of 9 minutes, and shear rate of 1000 sec in accordance with ISO11443 (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 the production or molding of the resin composition. From the viewpoint of suppressing changes in fluidity during the 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. -1 The difference between the melt viscosity at 260 °C, residence time of 3.5 minutes, and shear rate of 1000 sec in accordance with ISO11443 (hereinafter, also referred to as "melt viscosity at a residence time of 3.5 minutes") and the melt viscosity at 260 °C, residence time of 9 minutes, and shear rate of 1000 sec in accordance with ISO11443 (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 the production or molding of the resin composition. From the viewpoint of suppressing changes in fluidity during the 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 for producing polybutylene terephthalate resin composition] The method for producing the PBT resin composition is not particularly limited, and for example, a known method can be used. For example, a method of charging each component into an extruder, melt-kneading, and pelletizing can be mentioned.

[0061] [Molded article] The molded article of one embodiment of the present invention can be obtained using the above-described PBT resin composition.

[0062] As a method for obtaining a molded article using a PBT resin composition, there are no particular limitations, and known methods can be employed. For example, the PBT resin composition can be put into an extruder, melt-kneaded, extruded, and pelletized, and then these pellets can be put 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, for example, as a molded article that is exposed to a high-temperature and high-humidity environment for a long time, such as for applications in the automotive, railway, and aviation industries. For example, since it can prevent deterioration due to hydrolysis during use in a high-temperature and high-humidity environment, it can be used for connectors and the like.

[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 an amount of terminal carboxyl groups of 25 meq / kg or less and a cyclic carbodiimide compound (B), with respect to 100 parts by mass of the polybutylene terephthalate resin (A), the amount of the polyhydric hydroxyl group-containing compound (C-1) which is a polyhydric alcohol or its partial ester and has a hydroxyl value of 200 or more is less than 0.05 part by mass, 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 <1> above, which contains a hydroxyl group-containing compound (C-2) that is a polyhydric alcohol or its partial ester and has a hydroxyl value of 10 or more and less than 200. <3> The polybutylene terephthalate resin composition according to <1> or <2> above, containing 0.010 to 0.045 parts by mass of a polyhydric hydroxyl group-containing compound (C-1) having a hydroxyl value of 200 or more, which is the polyhydric alcohol or its partial ester, 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 <1> to <3> above.

Examples

[0065] Hereinafter, the present invention will be described more specifically by way of 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 each example and comparative example are shown in Tables 1 and 2 below. The unit of the content of each component in Tables 1 and 2 is parts by mass. The components shown in Tables 1 and 2 were melt-kneaded and extruded at a discharge rate of 15 kg / h and a screw rotation speed of 130 rpm using a 30 mmφ twin-screw extruder (TEX30C, manufactured by Japan Steel Works, Ltd.) with the raw material supply section at a cylinder temperature of 230°C and the intermediate section at 240 to 250°C to obtain pellets of the PBT resin composition.

[0067] The 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 content 13.1 meq / kg, manufactured by Polyplastics Co., Ltd.) A-5: PBT resin (intrinsic viscosity 0.822 dL / g, terminal carboxyl group content 12.8 meq / kg, manufactured by Polyplastics Co., Ltd.) A-6: PBT resin (intrinsic viscosity 0.878 dL / g, terminal carboxyl group content 12 meq / kg, manufactured by Polyplastics Co., Ltd.)

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

[0070] (3) Hydroxyl group-containing compound which is a polyhydric alcohol or its partial ester (hydroxyl group-containing compound) C-1: Glycerin mono 12-hydroxystearate (hydroxyl value 420, "Rikemal HC-100" manufactured by Riken Vitamin Co., Ltd.) C-2: Propylene glycol monobehenate (hydroxyl value 145, "Rikemal PB-100" manufactured by Riken Vitamin Co., Ltd.)

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

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

[0073] (1) Melt viscosity As an index of fluidity during injection molding, in accordance with ISO11443, at 260 °C, residence time 9 minutes, shear rate 1000 sec -1The melt viscosity (melt viscosity at a residence time of 9 minutes) was evaluated. Also, as an index of the change in fluidity during the production or molding of the resin composition, in accordance with ISO11443, at 260 °C, a residence time of 3.5 minutes, and a shear rate of 1000 sec -1 The melt viscosity at (hereinafter, also referred to as "melt viscosity at a residence time of 3.5 minutes" in Tables 1 and 2), and in accordance with ISO11443, at 260 °C, a residence time of 9 minutes, and a shear rate of 1000 sec -1 The difference from the melt viscosity at (the "melt viscosity at a residence time of 9 minutes") was evaluated.

[0074] Specifically, the melt viscosity at a residence time of 3.5 minutes and the melt viscosity at a residence time of 9 minutes were measured as follows. For the pellets of the PBT resin composition obtained above, in accordance with ISO11443, using a Capillograph 1B (manufactured by Toyo Seiki Seisakusho Co., Ltd.), with a furnace body temperature of 260 °C, a capillary φ1 mm × 20 mm L, and a shear rate of 1000 sec -1 The melt viscosity was measured under the 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. Also, in Tables 1 and 2, 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) (kPa·s) is shown using X and Y. Specifically, a difference between the melt viscosity at a residence time of 3.5 minutes and the melt viscosity at a residence time of 9 minutes of less than 0.025 kPa·s is shown as X, and 0.025 kPa·s or more is shown as Y.

[0076] (2) Tensile fracture strain after hydrothermal treatment To evaluate the hydrolysis resistance, the tensile fracture strain after the hydrothermal 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 produce a type 1A tensile test piece conforming to ISO3167. The obtained test piece was treated (hydrothermal treatment) for 60 hours under the conditions of 121 °C, 100% Rh, and 203 kPa using a pressure cooker (PCT) tester, and then the tensile fracture strain was measured in accordance with ISO527-1,2. A tensile fracture 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, 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 the change in fluidity during the production and molding of the resin composition, and the tensile fracture strain after the hydrothermal treatment evaluated as an index of hydrolysis resistance all showed good results. It can be seen that a PBT resin composition with excellent hydrolysis resistance and fluidity and suppressed changes in fluidity during the production and molding of the resin composition was obtained. Specifically, in 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 fracture strain after the hydrothermal treatment was 4% or more.

[0080] On the other hand, in Comparative Examples 1 and 2 that do not satisfy “(-15.4×b)+19.3≦a” of Formula 1, and in Comparative Example 5 in which a PBT resin having an end carboxyl group amount greater than 25 meq / kg was used, the value of the tensile fracture strain after the hydrothermal treatment was low. Further, in Comparative Examples 3 and 4 that do not satisfy “a≦(-57.4×b)+59.3” of Formula 1, the melt viscosities at a residence time of 9 minutes both increased. Further, in Comparative Example 6 in which a resin composition containing 0.06 part by mass of glycerol mono-12-hydroxystearate, which is a polyhydric hydroxyl group-containing compound (C-1) having a hydroxyl value of 200 or more and which is a polyhydric alcohol or a partial ester thereof, was used per 100 parts by mass of the 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 increased.

Claims

1. A polybutylene terephthalate resin (A) having an amount of terminal carboxyl groups of 25 meq / kg or less and a cyclic carbodiimide compound (B), wherein, based on 100 parts by mass of the polybutylene terephthalate resin (A), the amount of the polyhydric hydroxyl group-containing compound (C-1) which is a polyhydric alcohol or a partial ester thereof and has a hydroxyl value of 200 or more is less than 0.05 part by mass, 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 per 1 kg of the polybutylene terephthalate resin composition (meq / kg), and b represents the intrinsic viscosity (dL / g) of the polybutylene terephthalate resin (A) measured in o-chlorophenol at a temperature of 35°C.)

2. The polybutylene terephthalate resin composition according to Claim 1, comprising a polyhydric 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 hydroxyl group-containing compound (C-1) which is a polyhydric alcohol or a partial ester thereof and has 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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