Polybutylene terephthalate resin composition

Abstract

To provide a polybutylene terephthalate resin composition which has excellent hydrolysis resistance, flowability, and low warpage.SOLUTION: A polybutylene terephthalate resin composition contains at least (A) 100 pts.mass of a polybutylene terephthalate resin having an amount of terminal carboxyl groups of 1-9 meq / kg or less, (B) a carbodiimide compound, and (C) 10-200 pts.mass of a dimensional accuracy improver, in which an amount of carbodiimide functional groups of the carbodiimide compound is 5-40 equivalents with respect to the amount of the terminal carboxyl groups, and a value obtained by subtracting the amount of the terminal carboxyl groups of the polybutylene terephthalate resin from the amount of the carbodiimide functional groups of the carbodiimide compound is 30 meq / PBT kg or more.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a polybutylene terephthalate resin composition having excellent hydrolysis resistance, flowability, and low warpage. [Background technology]

[0002] Polybutylene terephthalate resin has excellent mechanical properties, electrical properties, heat resistance, weather resistance, water resistance, chemical resistance and solvent resistance, and is therefore widely used as an engineering plastic for a variety of applications, including automotive parts and electrical and electronic parts.

[0003] However, polybutylene terephthalate resin has a problem with hydrolysis resistance because the main chain is formed by ester bonds, and does not necessarily have sufficient durability when used in high-temperature and high-humidity environments.

[0004] In addition, since polybutylene terephthalate resin is a crystalline resin, anisotropy of shrinkage occurs due to orientation during injection molding, and molded products are prone to warping. Note that anisotropy of shrinkage caused by orientation is more likely to occur when the polybutylene terephthalate resin contains a fibrous filler.

[0005] Therefore, studies have been conducted to improve the hydrolysis resistance and low warpage of polybutylene terephthalate resin compositions from the viewpoint of materials. For example, Patent Document 1 discloses a polybutylene terephthalate resin composition in which a carbodiimide compound, a polycarbonate resin, and / or a polyethylene terephthalate resin are blended with a polybutylene terephthalate resin containing a fibrous filler.

[0006] According to Patent Document 1, the resin composition described therein is excellent in low warpage and heat shock resistance, and is also excellent in tensile strength retention rate (hydrolysis resistance) after a pressure cooker test. However, the resin composition described in Patent Document 1 has an issue of viscosity increase due to the reaction between the polybutylene terephthalate resin and the carbodiimide compound. In addition, the hydrolysis resistance is not at a sufficient level to meet the increasingly sophisticated requirements of recent years.

[0007] Incidentally, it is also known to blend a flow improver into polybutylene terephthalate resin in order to improve the flowability of the resin composition during molding. For example, Patent Document 2 discloses a polybutylene terephthalate resin composition having excellent flowability, which is obtained by blending a glycerin fatty acid ester into polybutylene terephthalate resin, but this document does not disclose any technology for improving hydrolysis resistance. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] WO2009 / 150833 publication [Patent Document 2] WO2009 / 050859 publication Summary of the Invention [Problem to be solved by the invention]

[0009] Conventionally, there has been a limit to the improvement of hydrolysis resistance by adding a carbodiimide compound, and even if a certain amount or more of the carbodiimide compound is added to the terminal carboxyl groups of the polybutylene terephthalate resin, the degree of the effect reaches a plateau, and further improvement in the effect cannot be expected.

[0010] The present invention has been made to solve such problems, and an object of the present invention is to provide a polybutylene terephthalate resin composition having excellent hydrolysis resistance, fluidity, and low warpage. [Means for solving the problem]

[0011] The inventors have achieved the object of the present invention by:

[0012] 1. A polybutylene terephthalate resin composition comprising at least (A) a polybutylene terephthalate resin (PBT) having a terminal carboxyl group amount of 1 to 9 meq / kg, (B) a carbodiimide compound, and (C) a dimensional accuracy improving agent, wherein the carbodiimide functional group amount of the (B) carbodiimide compound is 5 to 40 equivalents per equivalent of the terminal carboxyl group amount of the (A) polybutylene terephthalate resin, and the value obtained by subtracting the terminal carboxyl group amount of the (A) polybutylene terephthalate resin from the carbodiimide functional group amount of the (B) carbodiimide compound is 30 meq / PBT kg or more, and the (C) dimensional accuracy improving agent is comprised of (C-1) an alloy resin for improving dimensional accuracy and (C-2) a filler for improving dimensional accuracy, and the (C) dimensional accuracy improving agent is contained in an amount of 10 to 200 parts by mass per 100 parts by mass of the (A) polybutylene terephthalate resin. 2. The polybutylene terephthalate resin composition according to 1 above, which has a tensile strength retention rate of 80% or more in a thermal cycle test in accordance with USCAR-2 (5.6.2 Temperature / Humidity Cycling) Class 5. 3. The polybutylene terephthalate resin composition according to 1 or 2 above, having a melt viscosity of 0.3 kPa·s or less as measured at 260°C in accordance with ISO 11443. 4. The polybutylene terephthalate resin composition according to any one of 1 to 3 above, which contains (D) a polyvalent hydroxyl group-containing compound. Effect of the Invention

[0013] According to the present invention, a polybutylene terephthalate resin composition having excellent hydrolysis resistance, flowability, and low warpage can be obtained. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] Hereinafter, the embodiments of the present invention will be described in detail, but the present invention is not limited to the following embodiments.

[0015] <Polybutylene terephthalate resin composition> The polybutylene terephthalate resin composition of the present invention is a polybutylene terephthalate resin composition containing at least (A) a polybutylene terephthalate resin (PBT) having a terminal carboxyl group amount of 1 to 9 meq / kg, (B) a carbodiimide compound, and (C) a dimensional accuracy improving agent, wherein the carbodiimide functional group amount of the (B) carbodiimide compound is 5 to 40 equivalents per equivalent of the terminal carboxyl group amount of the (A) polybutylene terephthalate resin, and the value obtained by subtracting the terminal carboxyl group amount of the (A) polybutylene terephthalate resin from the carbodiimide functional group amount of the (B) carbodiimide compound is 30 meq / PBT kg or more, and the (C) dimensional accuracy improving agent is composed of (C-1) an alloy resin for improving dimensional accuracy and (C-2) a filler for improving dimensional accuracy, and the (C) dimensional accuracy improving agent is contained in an amount of 10 to 200 parts by mass per 100 parts by mass of the (A) polybutylene terephthalate resin.

[0016] The present invention has discovered that when the amount of terminal carboxyl groups in a polybutylene terephthalate resin is as small as 9 meq / kg or less, the improvement in hydrolysis resistance does not plateau but is significantly improved by adding a carbodiimide compound in a large excess relative to the amount of terminal carboxyl groups.

[0017] <(A) Polybutylene terephthalate resin> The polybutylene terephthalate resin (A) of the present invention is a thermoplastic resin having, as at least polymerization components, terephthalic acid (terephthalic acid or its ester-forming derivative) and an alkylene glycol having 4 carbon atoms (1,4-butanediol) or its ester-forming derivative. The polybutylene terephthalate resin (A) has a terminal carboxyl group amount of 1 to 9 meq / kg.

[0018] Examples of the base resin (A) polybutylene terephthalate resin (hereinafter also referred to as PBT resin) include homopolyesters (polybutylene terephthalate) consisting of repeating units derived from butylene terephthalate, and copolyesters (butylene terephthalate copolymers or polybutylene terephthalate copolyesters) having repeating units derived from butylene terephthalate as the main component and repeating units derived from copolymerizable monomers in the ratio described below.

[0019] Examples of the copolymerizable monomer in the copolyester (butylene terephthalate copolymer or modified PBT resin) (hereinafter, sometimes simply referred to as copolymerizable monomer) include dicarboxylic acid components other than terephthalic acid, diols other than 1,4-butanediol, oxycarboxylic acid components, lactone components, etc. The copolymerizable monomers can be used alone or in combination of two or more.

[0020] Dicarboxylic acids (or dicarboxylic acid components or dicarboxylic acids) include aliphatic dicarboxylic acids (e.g., succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedicarboxylic acid, dodecanedicarboxylic acid, hexadecanedicarboxylic acid, dimer acid, etc. 4~40 Dicarboxylic acids, preferably C 4~14 dicarboxylic acid), alicyclic dicarboxylic acid components (e.g., hexahydrophthalic acid, hexahydroisophthalic acid, hexahydroterephthalic acid, himic acid, etc. 8~12 dicarboxylic acids), aromatic dicarboxylic acid components other than terephthalic acid (e.g., phthalic acid, isophthalic acid, naphthalenedicarboxylic acids such as 2,6-naphthalenedicarboxylic acid, 4,4'-diphenyldicarboxylic acid, 4,4'-diphenoxyetherdicarboxylic acid, 4,4'-diphenyletherdicarboxylic acid, 4,4'-diphenylmethanedicarboxylic acid, 4,4'-diphenylketonedicarboxylic acid, etc. 8~16 dicarboxylic acids), or their reactive derivatives (e.g., lower alkyl esters (C phthalic acid or isophthalic acid such as dimethylphthalic acid, dimethylisophthalic acid (DMI) 1~4Examples of the derivatives include those capable of forming esters, such as alkyl esters, acid chlorides, and acid anhydrides.

[0021] Furthermore, if necessary, polyvalent carboxylic acids such as trimellitic acid and pyromellitic acid or ester-forming derivatives thereof (alcohol esters, etc.) may be used in combination. By using such polyfunctional compounds in combination, a branched polybutylene terephthalate resin can also be obtained.

[0022] The diol (or diol component or diols) may, for example, be an aliphatic alkanediol other than 1,4-butanediol [for example, an alkanediol (e.g., ethylene glycol, trimethylene glycol, propylene glycol, neopentyl glycol, hexanediol (1,6-hexanediol, etc.), octanediol (1,3-octanediol, 1,8-octanediol, etc.), decanediol, or other lower alkanediol, preferably a linear or branched C 2~12 Alkanediols, more preferably linear or branched C 2~10 Alkanediols, etc.; (poly)oxyalkylene glycols (e.g., multiple oxyC 2~4 Glycols having alkylene units (e.g., diethylene glycol, dipropylene glycol, ditetramethylene glycol, triethylene glycol, tripropylene glycol, polytetramethylene glycol, etc.), alicyclic diols (e.g., 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, hydrogenated bisphenol A, etc.), aromatic diols (e.g., dihydroxy C such as hydroquinone, resorcinol, naphthalenediol, etc.), 6~14 arenes; biphenols (4,4'-dihydroxybiphenyl, etc.); bisphenols; xylylene glycol, etc.), and reactive derivatives thereof (eg, ester-forming derivatives such as alkyl, alkoxy or halogen substituted derivatives).

[0023] Furthermore, if necessary, polyols such as glycerin, trimethylolpropane, trimethylolethane, pentaerythritol, or ester-forming derivatives thereof may be used in combination. By using such polyfunctional compounds in combination, a branched polybutylene terephthalate resin can also be obtained.

[0024] Bisphenols include bis(hydroxyaryl)C such as bis(4-hydroxyphenyl)methane (bisphenol F), 1,1-bis(4-hydroxyphenyl)ethane (bisphenol AD), 1,1-bis(4-hydroxyphenyl)propane, 2,2-bis(4-hydroxyphenyl)propane (bisphenol A), 2,2-bis(4-hydroxy-3-methylphenyl)propane, 2,2-bis(4-hydroxyphenyl)butane, 2,2-bis(4-hydroxyphenyl)-3-methylbutane, 2,2-bis(4-hydroxyphenyl)hexane, and 2,2-bis(4-hydroxyphenyl)-4-methylpentane. 1~6 Alkanes, bis(hydroxyaryl)C such as 1,1-bis(4-hydroxyphenyl)cyclopentane and 1,1-bis(4-hydroxyphenyl)cyclohexane 4~10 Examples of the alkylene oxide adducts include cycloalkanes, 4,4'-dihydroxydiphenyl ether, 4,4'-dihydroxydiphenyl sulfone, 4,4'-dihydroxydiphenyl sulfide, 4,4'-dihydroxydiphenyl ketone, and alkylene oxide adducts thereof. Examples of the alkylene oxide adducts include C-type alkylene oxides of bisphenols (e.g., bisphenol A, bisphenol AD, and bisphenol F). 2~3 Alkylene oxide adducts, for example, 2,2-bis[4-(2-hydroxyethoxy)phenyl]propane, diethoxylated bisphenol A (EBPA), 2,2-bis[4-(2-hydroxypropoxy)phenyl]propane, dipropoxylated bisphenol A, and the like.

[0025] Alkylene oxide (ethylene oxide, propylene oxide, etc.) 2~3The number of moles of alkylene oxide added is about 1 to 10 moles, and preferably about 1 to 5 moles, per hydroxy group.

[0026] Examples of oxycarboxylic acids (or oxycarboxylic acid components or oxycarboxylic acids) include oxycarboxylic acids such as oxybenzoic acid, oxynaphthoic acid, hydroxyphenylacetic acid, glycolic acid, and oxycaproic acid, and derivatives thereof. Examples of lactones include C lactones such as propiolactone, butyrolactone, valerolactone, and caprolactone (e.g., ε-caprolactone). 3~12 Lactones and the like are included.

[0027] Among these copolymerizable monomers, diols [C 2~6 Alkylene glycol (straight-chain or branched-chain alkylene glycols such as ethylene glycol, trimethylene glycol, propylene glycol, and hexanediol), polyoxy C having 2 to 4 repeating oxyalkylene units 2~4 Alkylene glycols (diethylene glycol, etc.), bisphenols (bisphenols or their alkylene oxide adducts, etc.)], dicarboxylic acids [C 6~12 Aliphatic dicarboxylic acids (adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, etc.), asymmetric aromatic dicarboxylic acids in which a carboxyl group is substituted at an asymmetric position on an arene ring, 1,4-cyclohexanedimethanol, etc., can be mentioned.

[0028] The (A) polybutylene terephthalate resin is preferably a homopolyester (polybutylene terephthalate) and / or a copolymer (polybutylene terephthalate copolyester). The (A) polybutylene terephthalate resin may be a copolyester having a copolymerizable monomer ratio (modification amount) of usually 45 mol% or less (e.g., about 0 mol% to 45 mol%), preferably 35 mol% or less (e.g., about 0 mol% to 35 mol%), and more preferably 30 mol% or less (e.g., about 0 mol% to 30 mol%).

[0029] In the copolymer, the proportion of the copolymerizable monomer can be selected, for example, from the range of about 0.01 mol% or more and about 30 mol% or less, and is usually about 1 mol% or more and about 30 mol% or less, preferably about 3 mol% or more and about 25 mol% or less, and more preferably about 5 mol% or more and about 20 mol% or less.

[0030] Furthermore, when a homopolyester (polybutylene terephthalate) and a copolymer (copolyester) are used in combination, the ratio of the homopolyester to the copolyester is in a range in which the ratio of the copolymerizable monomer is 0.1 mol % or more and 30 mol % or less (preferably, approximately 1 mol % or more and 25 mol % or less, and more preferably, approximately 5 mol % or more and 25 mol % or less) relative to the total monomers, and can usually be selected from the range of the former / latter=99 / 1 to 1 / 99 (mass ratio), preferably 95 / 5 to 5 / 95 (mass ratio), and more preferably about 90 / 10 to 10 / 90 (mass ratio).

[0031] The amount of terminal carboxyl groups in the polybutylene terephthalate resin (A) is 1 to 9 meq / kg, more preferably 2 to 8 meq / kg, and even more preferably 3 to 6 meq / kg.

[0032] In order to make the amount of terminal carboxyl groups fall within this range, a high molecular weight polymer having fewer terminal groups of polybutylene terephthalate resin may be used, or a melt polymerized product having an IV of about 0.1 to 0.8 dl / g may be polymerized by solid-phase polymerization. When using solid-phase polymerization, it is desirable to treat at a low temperature for a long time because a high treatment temperature increases the number of terminal carboxyl groups, but if the temperature is too low, the polymerization rate is low and productivity is poor, so the temperature can be adjusted, for example, at 120 to 220°C, preferably 140 to 200°C, and more preferably 150 to 190°C under reduced pressure or in an inert gas atmosphere.

[0033] In the case of using batch polymerization, if the resin discharge time after polymerization is long, the number of terminal carboxyl groups increases due to thermal decomposition, so it is possible to use one in which the number of terminal carboxyl groups discharged in the early stages is small.

[0034] The intrinsic viscosity (IV) of the polybutylene terephthalate resin (A) is preferably 0.6 dL / g or more, and more preferably 0.7 dL / g or more. The intrinsic viscosity is preferably 1.3 dL / g or less, and more preferably 1.2 dL / g or less. By blending polybutylene terephthalate resins (A) having different intrinsic viscosities, for example, by blending polybutylene terephthalate resins having intrinsic viscosities of 1.5 dL / g and 0.5 dL / g, an intrinsic viscosity of 0.6 to 1.3 dL / g or less may be realized.

[0035] The intrinsic viscosity (IV) can be measured in o-chlorophenol at a temperature of 35° C. By using a polybutylene terephthalate resin having an intrinsic viscosity in this range, it is easy to efficiently impart sufficient hydrolysis resistance and reduce the melt viscosity.

[0036] The polybutylene terephthalate resin (A) may be a commercially available product, or may be produced by copolymerizing (polycondensing) terephthalic acid or a reactive derivative thereof with 1,4-butanediol and, if necessary, a copolymerizable monomer by a conventional method such as ester exchange or direct esterification.

[0037] <(B) Carbodiimide compound> The carbodiimide compound (B) used in the present invention is a compound having a carbodiimide group (-N=C=N-) in the molecule. As the carbodiimide compound, any of an aliphatic carbodiimide compound having an aliphatic main chain, an alicyclic carbodiimide compound having an alicyclic main chain, and an aromatic carbodiimide compound having an aromatic main chain can be used, but the use of an aromatic carbodiimide compound is preferred in terms of hydrolysis resistance.

[0038] Examples of the aliphatic carbodiimide compound include diisopropylcarbodiimide, dioctyldecylcarbodiimide, di-tert-butylcarbodiimide, 1-ethyl-3-tert-butylcarbodiimide, 1-(2-butyl)-3-ethylcarbodiimide, 1,3-di-(2-butyl)carbodiimide, poly(diisopropylcarbodiimide), etc. Examples of the alicyclic carbodiimide compound include dicyclohexylcarbodiimide, poly(diisopropylcarbodiimide), etc.

[0039] Examples of the aromatic carbodiimide compound include diphenylcarbodiimide, di-2,6-dimethylphenylcarbodiimide, di-2,6-diethylphenylcarbodiimide, di-2,6-diisopropylphenylcarbodiimide, di-2,6-ditert-butylphenylcarbodiimide, N-triyl-N'-phenylcarbodiimide, N-(2,6-diisopropyl-4-phenoxyphenyl)-N-tert-butylcarbodiimide, N,N-bis[3-isocyanato-2,4,6-tris(1-methylethyl)phenyl] N-cyclohexyl-N-(4-(dimethylamino)naphthyl)carbodiimide, di-o-tolylcarbodiimide, di-p-tolylcarbodiimide, di-p-nitrophenylcarbodiimide, di-p-aminophenylcarbodiimide, di-p-hydroxyphenylcarbodiimide, di-p-chlorophenylcarbodiimide, di-p-methoxyphenylcarbodiimide, di-3,4-dichlorophenylcarbodiimide, di-2,5-dichlorophenylcarbodiimide, di-o-chlorophenylcarbodiimide Mono- or dicarbodiimide compounds of diimide, di-2,4,6-trimethylphenylcarbodiimide, di-2,4,6-triisopropylphenylcarbodiimide, di-2,4,6-triisobutylphenylcarbodiimide, p-phenylene-bis-di-o-triylcarbodiimide, p-phenylene-bis-dicyclohexylcarbodiimide, p-phenylene-bis-di-p-chlorophenylcarbodiimide, ethylene-bis-diphenylcarbodiimide, and poly(4,4'-diphenylmethanecarbodiimide), poly (p-phenylenecarbodiimide), poly(m-phenylenecarbodiimide), poly(3,3'-dimethyl-4,4'-diphenylmethanecarbodiimide), poly(naphthylenecarbodiimide), poly(1,3-diisopropylphenylenecarbodiimide), poly(1-methyl-3,5-diisopropylphenylenecarbodiimide), poly(1,3,5-triethylphenylenecarbodiimide), poly(diisopropylphenylenecarbodiimide) and poly(triisopropylphenylenecarbodiimide). The above carbodiimide compounds can be used in combination of two or more kinds.

[0040] Among these, di-2,6-dimethylphenylcarbodiimide, poly(4,4'-diphenylmethanecarbodiimide), poly(phenylenecarbodiimide) and poly(triisopropylphenylenecarbodiimide) are particularly preferably used.

[0041] In addition, it is preferable to use the (B) carbodiimide compound having a number average molecular weight of 2000 or more. By using the (B) carbodiimide compound having a number average molecular weight of 2000 or more, it is possible to improve the hydrolysis resistance of the polybutylene terephthalate resin composition for a long period of time. Furthermore, it is advantageous in that the generation of gas and odor can be reduced even when the polybutylene terephthalate resin composition has a long residence time during melt-kneading or molding.

[0042] The amount of the carbodiimide compound (B) in the polybutylene terephthalate resin composition is preferably such that the amount of the carbodiimide functional group is 5 to 40 equivalents when the amount of the terminal carboxyl group in the polybutylene terephthalate resin (A) is taken as 1 equivalent.

[0043] A more preferable blending amount is, when the amount of the terminal carboxyl group in the polybutylene terephthalate resin (A) is taken as 1 equivalent, the amount of the carbodiimide functional group is 6 to 35 equivalents, and most preferably 10 to 30 equivalents. Within this range, a polybutylene terephthalate resin composition excellent in flowability during molding and mechanical properties after molding can be obtained.

[0044] The amount obtained by subtracting the amount of terminal carboxyl groups in the polybutylene terephthalate resin (A) from the amount of functional groups in the carbodiimide compound (B) is 30 meq / PBT kg or more, more preferably 50 meq / PBT kg or more, and even more preferably 70 meq / PBT kg or more. Note that this value is calculated from the amount of each functional group based on 1 kg of PBT.

[0045] The amount of carbodiimide functional groups means the amount of carbodiimide functional groups in a carbodiimide compound in a resin composition, and the carbodiimide equivalent means the amount of carbodiimide functional groups contained in a carbodiimide compound.

[0046] <(C) Dimensional accuracy improving agent> In the polybutylene terephthalate resin composition of the present invention, in order to suppress warpage of a molded article made of the resin composition, a dimensional accuracy improving agent (C) consisting of (C-1) an alloy resin for improving dimensional accuracy and / or (C-2) a filler for improving dimensional accuracy is added.

[0047] As the (C-1) alloy resin for improving dimensional accuracy, a resin that not only has a small shrinkage rate and / or linear expansion coefficient during molding or heat treatment, but also has a processing temperature close to that of the (A) polybutylene terephthalate resin and has good compatibility can be preferably used.

[0048] Examples of such alloy resins for improving dimensional accuracy (C-1) include polyamide resins, vinyl resins, acrylic resins, polyurethane resins, polyketone resins, polyphenylene sulfide resins, polyether ether ketone resins, polycarbonate resins, styrene resins (polystyrene resins, acrylonitrile-styrene copolymers, acrylonitrile-butadiene-styrene copolymers, styrene-butadiene copolymers, styrene-butadiene-styrene copolymers, styrene-isoprene-styrene copolymers, styrene-ethylene-butadiene-styrene copolymers, etc.), polyarylate resins, polysulfone resins, polyethersulfone resins, etc. Examples of the elastomer include sulfone resin, phenoxy resin, polyphenylene ether resin, polyetherimide resin, polyamideimide resin, polyacetal resin, unsaturated polyester resin, urea resin, polyester resin other than polybutylene terephthalate (polyethylene terephthalate resin, polypropylene terephthalate resin, polybutylene naphthalate resin, polyethylene naphthalate resin, polylactic acid resin, etc.), polyolefin resin, olefin-based elastomer, core-shell-based elastomer, diene-based elastomer, polyester-based elastomer, urethane-based elastomer, silicone-based elastomer, and combinations thereof.

[0049] Among these, amorphous thermoplastic resins such as polyethylene terephthalate resin, polycarbonate resin, polyphenylene ether resin, and styrene-based resin are particularly preferred because they have a small shrinkage rate and anisotropy of the molded product, which makes it easy to obtain the effect of reducing warpage, and also have the effect of suppressing the bleed-out of liquid additives contained in the polybutylene terephthalate resin composition.

[0050] In addition, when polyolefin resins or olefin-based elastomers (such as ethylene ethyl acrylate copolymers) are added to polybutylene terephthalate resin compositions, the decrease in tracking resistance is small, so that it is also preferable to add these in applications where tracking resistance is particularly required. In order to improve the affinity between these resins and polybutylene terephthalate resin, a known compatibilizer may be used in combination.

[0051] The amount of the (C-1) alloy resin for improving dimensional accuracy added is 0 to 100 parts by mass, and may be 5 to 90 parts by mass or 10 to 80 parts by mass, per 100 parts by mass of the (A) polybutylene terephthalate resin.

[0052] However, depending on the compatibility with the (A) polybutylene terephthalate resin, adding a large amount may not provide a good dispersion state, and may deteriorate the mechanical properties of the composition due to agglomerates or phase delamination. Therefore, the content of the (C-1) alloy resin for improving dimensional accuracy is preferably 40 mass % or less, more preferably 35 mass % or less, even more preferably 30 mass % or less, and particularly preferably 25 mass % or less, based on the entire polybutylene terephthalate resin composition of the present invention.

[0053] As the filler for improving dimensional accuracy (C-2), any of organic fillers, inorganic fillers, metallic fillers, and combinations thereof can be used, but inorganic fillers and metallic fillers, which have small shrinkage rates and linear expansion coefficients in the processing temperature range and use temperature range of the resin molded product, are preferred. In addition, in molded products used as insulating members combined with metal members, it is particularly preferred to use inorganic fillers in order to ensure insulation.

[0054] (C-2) The shape of the filler for improving dimensional accuracy may be any of fibrous fillers, plate-like fillers, spherical fillers, powder fillers, curved fillers, irregular fillers, and combinations thereof, but in order to reduce warpage, it is preferable to use fillers with small anisotropy. It is more preferable to use fillers with an aspect ratio close to 1, such as plate-like fillers, spherical fillers, and powder fillers.

[0055] On the other hand, when a fibrous filler such as glass fiber is used, the effect of improving mechanical properties such as tensile strength is large, but the anisotropy of the shrinkage rate, which causes warping, tends to become large due to the orientation of the fibrous filler, so the fibrous filler used as the dimensional accuracy improving filler (C-2) in the present invention is one with a small aspect ratio, such as a short fiber such as milled fiber or whisker with a ratio of fiber length to fiber diameter of 100 or less (preferably 2 to 30) or a non-circular cross-sectional fiber with a flat shape such as a cocoon shape, oval shape, or elliptical shape (the ratio of the long diameter to the short diameter of the cross section is 1.3 to 10, preferably 1.5 to 5). The ratios of these fiber lengths and fiber diameters (including the long diameter and short diameter of the cross section) may be calculated using the values ​​in the catalogs and specifications disclosed by the manufacturers of the fibrous fillers.

[0056] Specific examples of plate-like fillers include plate-like talc, mica, glass flakes, metal pieces, and combinations thereof. Specific examples of spherical fillers include glass beads, glass balloons, spherical silica, and combinations thereof. Examples of powdery fillers include glass powder, talc powder, quartz powder, kaolin, clay, diatomaceous earth, wollastonite, silicon carbide, silicon nitride, metal powder, powders of inorganic acid metal salts (calcium carbonate, zinc borate, calcium borate, zinc stannate, calcium sulfate, barium sulfate, etc.), powders of metal oxides (magnesium oxide, iron oxide, titanium oxide, zinc oxide, alumina, etc.), powders of metal hydroxides (aluminum hydroxide, magnesium hydroxide, zirconium hydroxide, alumina hydrate (boehmite), etc.), powders of metal sulfides (zinc sulfide, molybdenum sulfide, tungsten sulfide, etc.), and combinations thereof.

[0057] In addition, in the case of molded articles used in combination with metal members, the content of free inorganic acid contained in these dimensional accuracy improving fillers (C-2) is preferably 0.5 mass % or less from the viewpoint of metal corrosiveness.

[0058] The size of the (C-2) dimensional accuracy improving filler can be appropriately selected in consideration of the balance between the warpage reduction effect and the mechanical properties, flowability, etc. For example, as talc, talc having a volume average particle size of 1 to 10 μm or compressed fine powder talc having a bulk density of 0.4 to 1.5 can be suitably used, and as mica, mica having a volume average particle size of 10 to 60 μm can be suitably used.

[0059] These (C-2) fillers for improving dimensional accuracy may be surface-treated (surface-coated) with an inorganic compound and / or an organic compound. Preferred examples of the inorganic compound used for the surface treatment include inorganic oxides and hydroxides of aluminum, silicon, zirconium, cerium, etc., such as aluminum hydroxide, alumina, silica, zirconia, zirconium hydroxide, zirconia hydrate, cerium oxide, cerium oxide hydrate, and cerium hydroxide.

[0060] These inorganic compounds may be hydrates. Among these, aluminum hydroxide and silica are preferred, and when silica is used, it is particularly preferred that it is a silica hydrate represented by SiO2·nH2O.

[0061] As the organic compound used in the surface treatment, an epoxy compound or an amine compound is preferable, and examples of more preferable compounds include epoxy compounds such as bisphenol A type epoxy and novolac type epoxy, and amine compounds such as monoethanolamine, diethanolamine, triethanolamine, and dichlorohexylamine.

[0062] The amount of the filler for improving dimensional accuracy (C-2) added is 0 to 100 parts by mass, and may be 5 to 90 parts by mass or 10 to 80 parts by mass, relative to 100 parts by mass of the polybutylene terephthalate resin (A). The amount of the filler for improving dimensional accuracy (C-2) added can be appropriately selected in consideration of the balance between the warpage reduction effect and the mechanical properties, flowability, etc.

[0063] The amount of the (C) dimensional accuracy improving agent, which is composed of the above-mentioned (C-1) alloy resin for improving dimensional accuracy and / or (C-2) filler for improving dimensional accuracy, added is 10 to 200 parts by mass, or may be 20 to 180 parts by mass, or 30 to 150 parts by mass, as the total of the (C-1) alloy resin for improving dimensional accuracy and the (C-2) filler for improving dimensional accuracy, per 100 parts by mass of the (A) polybutylene terephthalate resin.

[0064] <(D) Polyhydric Hydroxyl Group-Containing Compound> In the present invention, it is also preferable to add (D) a polyhydric hydroxyl group-containing compound. The polyhydroxyl group-containing compound (D) is a compound having two or more hydroxyl groups in one molecule. The polyhydroxyl group-containing compound (D) preferably has a hydroxyl value of 200 to 1,000.

[0065] The polyhydroxyl group-containing compound (D) also enhances the fluidity of the polybutylene terephthalate resin composition. By using the polyhydroxyl group-containing compound (D), the fluidity of the polybutylene terephthalate resin composition during melting can be efficiently improved while maintaining the properties of the polybutylene terephthalate resin (A) at a high level.

[0066] The fluidity of the polybutylene terephthalate resin composition is determined in accordance with ISO11443, with 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 measured at is preferably 0.3 kPa·s or less, more preferably 0.25 kPa·s or less, and even more preferably 0.2 kPa·s or less (eg, 0.18 kPa·s or less).

[0067] The polyhydric hydroxyl group-containing compound (D) may be one produced by a conventionally known method, or a commercially available product may be used.

[0068] The hydroxyl value of the (D) polyhydric hydroxyl group-containing compound is preferably 100 or more. The hydroxyl value is more preferably 200 or more, and even more preferably 250 or more. When the hydroxyl value is 100 or more, the effect of improving the fluidity tends to be enhanced, and the effect of improving hydrolysis resistance can also be obtained.

[0069] On the other hand, if the hydroxyl value is too large, the reaction with (A) polybutylene terephthalate proceeds excessively, which may reduce the molecular weight of (A) polybutylene terephthalate resin, thereby impairing excellent properties such as mechanical properties, heat resistance, and chemical resistance. The hydroxyl value is preferably 1000 or less, and more preferably 500 or less.

[0070] The content of the polyhydric hydroxyl group-containing compound (D) in the polybutylene terephthalate resin composition is preferably 0.05 parts by mass or more and 5 parts by mass or less, more preferably 0.1 parts by mass or more and 4 parts by mass or less, and even more preferably 0.5 parts by mass or more and 3 parts by mass or less, relative to 100 parts by mass of the polybutylene terephthalate resin (A).

[0071] As the polyhydric hydroxyl group-containing compound (D) of the present invention, it is preferable to use an ether obtained by addition polymerization of an alkylene oxide to a glycerin fatty acid ester or a diglycerin. The ether obtained by addition polymerization of an alkylene oxide to a glycerin fatty acid ester or a diglycerin will be described below.

[0072] Glycerol fatty acid esters are esters composed of glycerol and / or its dehydration condensate and fatty acid. Among glycerol fatty acid esters, those obtained using fatty acids having 12 or more carbon atoms are preferred.

[0073] Examples of fatty acids having 12 or more carbon atoms include lauric acid, oleic acid, palmitic acid, stearic acid, 12-hydroxystearic acid, behenic acid, montanic acid, etc. Fatty acids having 12 to 32 carbon atoms are preferred, and fatty acids having 12 to 22 carbon atoms are particularly preferred.

[0074] Specifically, lauric acid, stearic acid, 12-hydroxystearic acid, or behenic acid is particularly preferred. By using a fatty acid having 12 or more carbon atoms, the heat resistance of the resin tends to be sufficiently maintained, which is preferred. If the number of carbon atoms is 32 or less, the effect of improving the flowability is high, which is preferred.

[0075] Preferred examples of glycerol fatty acid esters include glycerol monostearate, glycerol monobehenate, diglycerol monostearate, triglycerol monostearate, triglycerol stearic acid partial ester, tetraglycerol stearic acid partial ester, decaglycerol lauric acid partial ester, and glycerol mono 12-hydroxystearate.

[0076] Examples of ethers obtained by addition polymerization of alkylene oxide to diglycerin include polyoxypropylene diglyceryl ether obtained by addition polymerization of propylene oxide to diglycerin, and polyoxyethylene diglyceryl ether obtained by addition polymerization of ethylene oxide to diglycerin. Among these ethers, the use of polyoxyethylene diglyceryl ether is particularly preferred in the present invention.

[0077] <Other ingredients> The polybutylene terephthalate resin composition of the present invention may contain other resins and conventionally known additives such as flame retardants, flame retardant assistants, reinforcing fillers, antioxidants, heat stabilizers, ultraviolet absorbers, antistatic agents, colorants such as dyes and pigments, lubricants, plasticizers, crystal nucleating agents, etc. In the present invention, it may be preferable to contain a transesterification catalyst and a transesterification terminator as other components.

[0078] When the composition contains an ester exchange reaction catalyst, the reaction between the polybutylene terephthalate resin (A) and the polyhydroxyl group-containing compound (D) is accelerated. When the reaction between the polybutylene terephthalate resin (A) and the polyhydroxyl group-containing compound (D) is slow and it takes a long time to reach the desired fluidity, the use of the ester exchange reaction catalyst can quickly achieve the desired fluidity.

[0079] The transesterification catalyst is not particularly limited, and for example, a metal compound can be used as the transesterification catalyst. Among them, titanium compounds, tin compounds, and antimony compounds are preferably used.

[0080] Specific examples of titanium compounds include inorganic titanium compounds such as titanium oxide, titanium alcoholates such as tetramethyl titanate, tetraisopropyl titanate, and tetrabutyl titanate, and titanium phenolates such as tetraphenyl titanate.Specific examples of tin compounds include dibutyltin oxide, hexaethyl ditin oxide, didodecyl tin oxide, triethyltin hydroxide, tributyltin acetate, dibutyltin diacetate, diphenyltin dilaurate, monobutyltin trichloride, methylstannoic acid, ethylstannoic acid, and butylstannoic acid.Specific examples of antimony compounds include antimony trioxide.Among these, the use of tetrabutyl titanate, tributyltin acetate, and antimony trioxide is particularly preferred.

[0081] In addition, if the transesterification reaction proceeds too far, the physical properties of the molded article obtained by molding the resin composition may be deteriorated. By adding a transesterification reaction terminator after the transesterification reaction, it is possible to adjust the fluidity to a desired level without causing problems such as deterioration of physical properties.

[0082] As the transesterification reaction terminator, a phosphorus compound can be preferably used. The type and amount of the phosphorus compound are not particularly limited, and can be appropriately adjusted depending on conditions such as the type of compound contained in the composition of the present invention.

[0083] The phosphorus compound that can be used is not particularly limited, and examples thereof include phosphine-based, phosphinite-based, phosphonite-based, phosphite-based, phosphinamide-based, phosphonasdiamide-based, phosphorus triamide-based, phosphoramidite-based, phosphorodiamidite-based, phosphine oxide-based, phosphinate-based, phosphonate-based, phosphate-based, phosphinic amide-based, phosphonodiamidate-based, phosphoramide-based, phosphoramidate-based, phosphorodiamidate-based, phosphine imide-based, and phosphine sulfide-based phosphorus compounds. Phosphorus compounds also include those that form salts with metals.

[0084] <Hydrolysis resistance> It is preferable that a molded article made of the polybutylene terephthalate resin composition of the present invention has a tensile strength retention of 80% or more in a thermal cycle test in accordance with USCAR-2 (5.6.2 Temperature / Humidity Cycling) Class 5, and has a melt viscosity of 0.3 kPa s or less as measured at 260°C according to ISO 11443.

[0085] USCAR-2 is a test condition stipulated by North American automobile standards, and Class 5 refers to 40 cycles of environmental test conditions, with one cycle being -40°C (0.5 hours), -80 to 90°C, 80 to 100% RH (4 hours), and 175°C (1.5 hours). The polybutylene terephthalate resin composition of the present invention is at a level that allows it to be used sufficiently even in a Class 5 temperature environment.

[0086] The tensile strength retention rate can be calculated in accordance with ISO527-1 and 2 by measuring the tensile strength before and after the test.

[0087] <Method of producing polybutylene terephthalate resin composition> The method for preparing the polybutylene terephthalate resin composition of the present invention is not particularly limited, and generally known equipment and methods for preparing resin compositions can be used. For example, the necessary components are mixed and kneaded using a single-screw or twin-screw extruder or other melt kneading equipment, and prepared into pellets for molding.

[0088] In addition, a plurality of extruders or other melt kneading devices may be used. All components may be fed simultaneously from a hopper, or some components may be fed from a side feed port. Here, the extruder cylinder temperature is preferably set so that the resin temperature in the extruder is 240 to 350°C. More preferably, it is 270 to 330°C.

[0089] If the temperature is lower than 240°C, the reaction between the (A) polybutylene terephthalate resin and the (B) carbodiimide compound and / or the (D) polyvalent hydroxyl group-containing compound may be insufficient, resulting in insufficient hydrolysis resistance of the polybutylene terephthalate resin composition, or insufficient kneading due to high viscosity of the molten material, making it difficult to obtain a polybutylene terephthalate resin composition having uniform properties. On the other hand, if the temperature exceeds 350°C, the (A) polybutylene terephthalate resin may be easily decomposed, resulting in insufficient mechanical properties and hydrolysis resistance of the polybutylene terephthalate resin composition.

[0090] In addition, when producing the polybutylene terephthalate resin composition of the present invention, (A) polybutylene terephthalate resin and (D) polyvalent hydroxyl group-containing compound may be melt-kneaded first, and then (B) carbodiimide compound and (C) dimensional accuracy improver and transesterification reaction terminator may be added. In this case, (B) carbodiimide compound is added in a state where the melt viscosity of (A) polybutylene terephthalate resin is reduced, so that uniform melt-kneading can be efficiently performed.

[0091] As a method for adding the (B) carbodiimide compound etc. later, it may be added from a side feed port, or it may be produced by melt-kneading (A) polybutylene terephthalate resin and (D) polyhydroxyl group-containing compound to form pellets, and then re-melting and kneading the pellets with (B) the carbodiimide compound and (C) the dimensional accuracy improving agent and / or the transesterification reaction terminator.

[0092] Conversely, if (A) polybutylene terephthalate resin and (B) carbodiimide compound are first melt-kneaded and then (D) polyhydroxyl group-containing compound or the like is added, the viscosity of the polybutylene terephthalate resin (A) will increase due to the reaction between the polybutylene terephthalate resin (A) and the carbodiimide compound (B), preventing sufficient melt-kneading with the polyhydroxyl group-containing compound (D). Furthermore, heat generation due to shear will increase, which may lead to thermal decomposition of the polybutylene terephthalate resin (A).

[0093] Similarly, when a reinforcing filler is added, if the (A) polybutylene terephthalate resin and the (D) polyhydroxyl group-containing compound are first melt-kneaded and then the reinforcing filler is added, the viscosity of the (A) polybutylene terephthalate resin is reduced in advance, which reduces breakage of the reinforcing filler due to shear and prevents impairment of the mechanical properties. Therefore, when a reinforcing filler is used, it is particularly preferable to first melt-knead the (A) polybutylene terephthalate resin and the (D) polyhydroxyl group-containing compound.

[0094] Furthermore, in the case of (B) a carbodiimide compound and a reinforcing filler, if the reinforcing filler is added first, the reaction between the (A) polybutylene terephthalate resin and the surface treatment agent for the reinforcing filler is not inhibited, and the interfacial adhesion between the (A) polybutylene terephthalate resin and the reinforcing filler becomes stronger, which is preferable in that it makes it easier to improve mechanical properties.

[0095] The (B) carbodiimide compound can also be compounded as a masterbatch with a resin as a matrix, and the use of a masterbatch is often easier in terms of practical handling. A masterbatch made of polybutylene terephthalate resin is preferably used, but a masterbatch prepared with other resins may also be used. In the case of a masterbatch made of polybutylene terephthalate resin, the amount of the masterbatch may be adjusted to be within a predetermined range. EXAMPLES

[0096] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these. Evaluations were carried out in an atmosphere of 23°C and 55% RH unless otherwise specified. The compounds listed in Tables 1 to 3 are as follows.

[0097] <Material> (A) Polybutylene terephthalate resin (PBT resin) A-1: Polybutylene terephthalate resin (intrinsic viscosity = 1.14 dL / g, terminal carboxyl group amount = 4 meq / kg, manufactured by Polyplastics Co., Ltd.) A-2: Polybutylene terephthalate resin (intrinsic viscosity = 1.14 dL / g, terminal carboxyl group amount = 9 meq / kg, manufactured by Polyplastics Co., Ltd.) A-3: Polybutylene terephthalate resin (intrinsic viscosity = 0.95 dL / g, terminal carboxyl group amount = 9 meq / kg, manufactured by Polyplastics Co., Ltd.) A-4: Polybutylene terephthalate resin (intrinsic viscosity = 1.13 dL / g, terminal carboxyl group amount = 12 meq / kg, manufactured by Polyplastics Co., Ltd.) A-5: Polybutylene terephthalate resin (intrinsic viscosity = 0.84 dL / g, terminal carboxyl group amount = 15 meq / kg, manufactured by Polyplastics Co., Ltd.)

[0098] (B) Carbodiimide compound B-1: Stavaxol P100, carbodiimide equivalent: 3625 meq / kg (aromatic carbodiimide compound manufactured by LANXESS KK)

[0099] (C) Dimensional accuracy improver C-1: Alloy resin for improving dimensional accuracy C-1-1: AS resin (manufactured by Ningbo LG Yongxing Chemical Co., Ltd., acrylonitrile-styrene resin 80HF) C-1-2: PC resin (Teijin polycarbonate resin Panlite L-1225W) C-1-3: PET resin (Teijin, polyethylene terephthalate resin TRN-8550FF) C-1-4: EEA copolymer (NUC, NUC-6570) C-2: Filler for improving dimensional accuracy C-2-1: Talc (Matsumura Sangyo Co., Ltd., Crown Talc PP) C-2-2: Glass flakes (Microglass Fleka REFG-301, manufactured by Nippon Sheet Glass Co., Ltd.) C-2-3: Flat cross-section glass fiber (manufactured by Nittobo, CSG3PA830 (oval cross-section glass fiber with long diameter 28 μm, short diameter 7 μm (long diameter ÷ short diameter ratio = 4), average fiber length 3 mm)

[0100] (D) Polyhydric Hydroxyl Group-Containing Compound D-1: Glyceryl hydroxystearate (hydroxyl value 480, manufactured by Riken Vitamin Co., Ltd., Rikemal HC100) The hydroxyl value of the polyhydroxyl-containing compound (D) was measured in accordance with Japan Oil Chemists' Society 2.3.6.2-1996 Hydroxyl Value (Pyridine-Acetic Anhydride Method).

[0101] (others) Circular cross-section glass fiber: Nippon Electric Glass Co., Ltd., ECS03T-127 (average fiber diameter 13 μm, average fiber length 3 mm) Antioxidant: Phenolic antioxidant (BASF, Irganox 1010) Lubricant: Diglycerol tetrabehenate (Riken Vitamin Co., Ltd., Rikemal B74) Alkaline compound: Potassium acetate (Wako Pure Chemical Industries, Ltd.)

[0102] <Examples 1 to 17 and Comparative Examples 1 to 6> (A) polybutylene terephthalate resin, (B) carbodiimide compound, (C) dimensional accuracy improving agent, (D) polyhydric hydroxyl group-containing compound, and other components were weighed and dry-blended according to the composition shown in Tables 1 to 3, and melt-kneaded in a twin-screw extruder (TEX-30 manufactured by Japan Steel Works, Ltd.) at a cylinder temperature of 300°C, a screw rotation speed of 130 rpm, and an extrusion rate of 12 kg / h. The discharged strand-shaped molten resin was cooled and cut by a pelletizer to obtain a pellet-shaped sample of the resin composition. Next, the following various evaluations were performed using the pellets.

[0103] [Equivalent ratio of carbodiimide functional group amount to terminal carboxyl group amount] The amount of terminal carboxyl groups was determined by dissolving a ground sample of the obtained pellets in benzyl alcohol at 215°C for 10 minutes, and then titrating with a 0.01 N aqueous sodium hydroxide solution. The measurement results for the amount of terminal carboxyl groups and the equivalent ratio of the amount of carbodiimide functional groups to be mixed are shown in Tables 1 to 3. Equivalent ratio of carbodiimide functional group amount to terminal carboxyl group amount= Carbodiimide functional group amount / terminal carboxyl group amount

[0104] [Amount of carbodiimide functional groups minus amount of terminal carboxyl groups] The amount of terminal carboxyl groups in the polybutylene terephthalate resin minus the amount of carbodiimide functional groups in the carbodiimide compound was calculated by subtracting the amount of terminal carboxyl groups in 1 kg of polybutylene terephthalate resin from the amount of carbodiimide functional groups mixed per 1 kg of polybutylene terephthalate resin, as shown in the following formula. The values ​​are shown in Tables 1 to 3. Amount of carbodiimide functional groups minus terminal carboxyl groups = Amount of carbodiimide functional groups mixed per 1 kg of polybutylene terephthalate resin - Amount of terminal carboxyl groups contained in 1 kg of polybutylene terephthalate resin (meq / PBT kg)

[0105] [Hydrolysis resistance (tensile strength retention rate 1)] The pellets obtained were dried at 140°C for 3 hours, and then injection molded into ISO3167 tensile test pieces at a resin temperature of 260°C, a mold temperature of 80°C, an injection time of 15 seconds, and a cooling time of 15 seconds. The test pieces were subjected to treatment for 100 hours under conditions of 121°C and 100% RH in a pressure cooker tester, and the tensile strength was measured according to ISO527-1,2. The tensile strength retention rate was evaluated as follows: 90% or more, ◎; 80% or more but less than 90%, ○; and less than 80%. The results are shown in Tables 1 to 3. Tensile strength retention rate (unit: %) = (tensile strength after treatment / tensile strength before treatment) x 100

[0106] [Hydrolysis resistance (tensile strength retention rate 2)] The pellets obtained were dried at 140°C for 3 hours, and then injection molded into ISO3167 tensile test pieces at a resin temperature of 260°C, a mold temperature of 80°C, an injection time of 15 seconds, and a cooling time of 15 seconds. The test pieces were subjected to 40 cycles of environmental test conditions of -40°C (0.5 hours) -85°C, 85%RH (4 hours) -175°C (1.5 hours) in accordance with USCAR-2 (5.6.2 Temperature / Humidity Cycling) Class 5, and the tensile strength was measured before and after the thermal cycle test in accordance with ISO527-1,2. The tensile strength retention rate was evaluated as 90% or more, as ◎, as 80% or more but less than 90%, and as ×, respectively, as calculated based on the following formula. The results are shown in Tables 1 to 3. Tensile strength retention rate (unit: %) = (tensile strength after treatment / tensile strength before treatment) x 100

[0107] [Fluidity (melt viscosity)] The pellets obtained were dried at 140°C for 3 hours, and then, in accordance with ISO11443, they were subjected to a furnace temperature of 260°C, a capillary diameter of 1 mm x 20 mmL, and a shear rate of 1000 sec using a Capillograph 1B (manufactured by Toyo Seiki Seisakusho Co., Ltd.). -1 The measured values ​​were evaluated as follows: 0.2 kPa or less: ⊚, more than 0.2 kPa but not more than 0.3 kPa: ◯, and more than 0.3 kPa: ×. The results are shown in Tables 1 to 3.

[0108] [Low warpage] The pellets obtained were dried at 140°C for 3 hours, and then injection molded into flat test pieces measuring 120mm x 120mm x 2mm at a cylinder temperature of 260°C, a mold temperature of 60°C, and a holding pressure of 60MPa. The flat test pieces obtained were left to stand for 24 hours at 23°C and 50% RH, then placed on a platen, and the height coordinates were measured for a total of nine points, including the four corners and center of the upper surface, and the center of each side (four points), using a Mitutoyo CNC image measuring device, and the amount of warping of the molded product was calculated from the difference between the highest and lowest points. The amount of warping was evaluated as ◎ when the amount of warping was 5mm or less, ○ when it was 10mm or less, and × when it was more than 10mm. The results are shown in Tables 1 to 3.

[0109] [Table 1]

[0110] [Table 2]

[0111] [Table 3]

[0112] From the results of the Examples and Comparative Examples, it was confirmed that according to the present invention, a polybutylene terephthalate resin composition having excellent hydrolysis resistance, flowability, and low warpage can be obtained.

Claims

1. A polybutylene terephthalate resin composition containing at least (A) a polybutylene terephthalate resin (PBT) having a terminal carboxyl group amount of 1 to 9 meq / kg, (B) a carbodiimide compound, and (C) a dimensional accuracy improving agent, wherein the carbodiimide functional group amount of the carbodiimide compound (B) is 5 to 40 equivalents per equivalent of the terminal carboxyl group amount of the polybutylene terephthalate resin (A), and the value obtained by subtracting the terminal carboxyl group amount of the polybutylene terephthalate resin (A) from the carbodiimide functional group amount of the carbodiimide compound (B) is 30 meq / PBT kg or more, and the (C) ) A dimensional accuracy improving agent is composed of (C-1) an alloy resin for improving dimensional accuracy and / or (C-2) a filler for improving dimensional accuracy, the (C) dimensional accuracy improving agent contains the (C-1) alloy resin for improving dimensional accuracy, the (C-1) alloy resin for improving dimensional accuracy is at least one selected from the group consisting of polycarbonate resin, polyphenylene ether resin, styrene-based resin, polyolefin resin, and olefin-based elastomer, and the polybutylene terephthalate resin composition contains 10 to 200 parts by mass of the (C) dimensional accuracy improving agent per 100 parts by mass of the (A) polybutylene terephthalate resin.

2. 2. The polybutylene terephthalate resin composition according to claim 1, which has a tensile strength retention rate of 80% or more in a thermal cycle test in accordance with USCAR-2 (5.6.2 Temperature / Humidity Cycling) Class 5.

3. 3. The polybutylene terephthalate resin composition according to claim 1 or 2, which has a melt viscosity of 0.3 kPa·s or less as measured at 260° C. in accordance with ISO 11443.

4. The polybutylene terephthalate resin composition according to any one of claims 1 to 3, further comprising (D) a polyvalent hydroxyl group-containing compound.

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