Polybutylene terephthalate resin composition used in automotive connectors and automotive connectors made therefrom

Abstract

To provide a polybutylene terephthalate resin composition and a connector made therefrom that have good mechanical strength and good flame retardancy even under low temperature conditions. [Solution] The polybutylene terephthalate resin composition used in the automotive connector of the present invention comprises a polybutylene terephthalate resin (A), a flame retardant (B), a flame retardant additive (C), an elastomer (D), and glass fiber (E).

Description

Technical Field

[0001] The present invention relates to a polybutylene terephthalate resin composition used for automotive connectors and an automotive connector made of the same.

Background Art

[0002] In order to address environmental issues such as reducing CO2 emissions, the electrification of automobiles (electric vehicles, hybrid vehicles, fuel cell vehicles) is progressing. Since these automobiles generally use high-voltage electrical circuits, there is a risk of electric fires. In particular, plug-in hybrid vehicles, which are a type of electric vehicle or hybrid vehicle, are assumed to be charged at home, so they require the same fire resistance as household appliances. Common fire resistance standards for household appliances include IEC60335-1, etc. According to this standard, components through which a current exceeding 0.2 A flows and are used in devices that operate without people's attention (such as refrigerators, washing machines, etc.) are required to have high fire resistance characteristics. Therefore, resins used for electrical parts such as automotive connectors, switches, relays, and electric wires are not only required to have high electrical properties (insulation, tracking resistance), but also fire resistance against electric fires, that is, flame retardancy. In addition, automotive connectors are also required to have high mechanical properties (strength, impact strength, modulus of elasticity) from the perspectives of waterproofness and ensuring reliability during the insertion and extraction of terminals and locks.

[0003] In recent years, signal connectors sometimes use connectors with narrow terminal widths (e.g., 0.5 mm) to connect to various sensors, while connectors with terminal widths of, for example, 9.5 mm or wider locking sections are sometimes used for batteries and drive motors to prevent them from coming loose even when using high currents. Therefore, because the thickness of automotive connectors varies depending on where they are used, they are required to have sufficient flame retardancy even when thin-walled (e.g., 0.75 mm). Thus, while it was possible to make connectors flame-retardant by studying the formulation of various flame retardants into the resin (polybutylene terephthalate resin or polyamide resin) used in automotive connectors, it was difficult to obtain the desired mechanical properties (especially toughness).

[0004] Furthermore, while automobiles are used in a wide range of climates, from warm to cold, there is a risk of breakage of the locking or lance portion of connectors when inserting, fastening, or removing them during production, repair, etc., particularly in cold regions. Therefore, there is a need for resin compositions for automotive connector parts that are less prone to lance breakage even under low-temperature conditions.

[0005] For example, Patent Document 1 discloses a resin composition containing a polyester thermoplastic elastomer, including a polyester-ether type polyester thermoplastic elastomer having a specific weight-average molecular weight, in order to improve mechanical strength and bending strain at low temperatures. Patent Document 2 discloses a resin composition containing a polybutylene terephthalate resin containing polytetramethylene glycol having a specific molecular weight as a copolymer component. Patent Document 3 discloses a resin composition containing a polybutylene terephthalate resin and polypropylene, which is a polyolefin resin. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2007-291277 [Patent Document 2] Japanese Patent Application Publication No. 10-046011 [Patent Document 3] Japanese Patent Application Publication No. 06-295761 [Overview of the project] [Problems that the invention aims to solve]

[0007] According to the inventors' research, while flame retardancy was possible when a flame retardant was added to a conventional polybutylene terephthalate resin composition, it was found that under low-temperature conditions, the mechanical strength decreased and cracking occurred more easily.

[0008] The present invention has been made in view of the above, and aims to provide a polybutylene terephthalate resin composition for use in automotive connectors that has good mechanical strength and good flame retardancy even under low temperature conditions, and an automotive connector made therefrom. [Means for solving the problem]

[0009] As a result of diligent research, the inventors have discovered that an automotive connector made of a polybutylene terephthalate resin composition containing a polybutylene terephthalate resin having a specific weight-average molecular weight, a flame retardant, a flame retardant additive, an elastomer, and glass fibers has good mechanical strength and good flame retardancy even under low-temperature conditions, and have completed the present invention. Specifically, the present invention is configured as follows [1] to

[11] .

[0010] [1] A polybutylene terephthalate resin composition for use in automotive connectors, comprising a polybutylene terephthalate resin (A), a flame retardant (B), a flame retardant additive (C), an elastomer (D), and glass fibers (E), wherein the content of the flame retardant additive (C) is 6 to 11 parts by mass per 100 parts by mass of the polybutylene terephthalate resin (A), the content of the elastomer (D) is 7 to 30 parts by mass per 100 parts by mass of the polybutylene terephthalate resin (A), and the content of the glass fibers (E) is 15 to 40 parts by mass per 100 parts by mass of the polybutylene terephthalate resin (A), and the weight-average molecular weight of the polybutylene terephthalate resin (A) in the resin composition, as measured by gel permeation chromatography, is 60,000 or more. [2] The polybutylene terephthalate resin composition according to [1], wherein the ratio of the total mass of the elastomer (D) and the glass fiber (E) to the mass of the polybutylene terephthalate resin (A) is 0.2 to 0.6. [3] The polybutylene terephthalate resin composition according to [1] or [2], wherein the flame retardant (B) is a brominated flame retardant. [4] The polybutylene terephthalate resin composition according to any one of [1] to [3], wherein the elastomer (D) is an olefin-based elastomer. An automotive connector comprising a polybutylene terephthalate resin composition as described in any of [5][1] to [4]. [6] The automotive connector described in [5], having a tensile strength of 80 MPa or more. [7] The automotive connector described in [5], wherein the flexural modulus is 8000 MPa or less. [8] The automotive connector described in [5], having a terminal width of 0.5 mm or more and 9.5 mm or less. [9] The automotive connector described in [5], which has a rated current of 0.2A or more.

[10] A waterproof automotive connector as described in [5].

[11] The automotive connector described in [5], for use in electric vehicles, hybrid vehicles and fuel cell vehicles. [Effects of the Invention]

[0011] According to the present invention, it is possible to provide a polybutylene terephthalate resin composition used for an automotive connector having good mechanical strength and good flame retardancy even under low temperature conditions, and a connector made of the same.

Brief Description of the Drawings

[0012] [Figure 1] FIG. 1 is an overall view of an automotive connector according to an embodiment of the present invention. [Figure 2] (a) of FIG. 2 is a front view of an automotive connector according to an embodiment of the present invention, and (b) of FIG. 2 is a cross-sectional view taken along line A-A' of the automotive connector according to an embodiment of the present invention.

Mode for Carrying Out the Invention

[0013] Hereinafter, specific embodiments of the present invention will be described in detail. Note that the present invention is not limited to the following embodiments, and can be appropriately changed without changing the gist of the present invention.

[0014] [Polybutylene Terephthalate Resin Composition Used for Automotive Connector] The polybutylene terephthalate resin composition (hereinafter, also simply referred to as "polybutylene terephthalate resin composition") used for an automotive connector according to an embodiment of the present invention contains a polybutylene terephthalate resin (A), a flame retardant (B), a flame retardant aid (C), an elastomer (D), and glass fiber (E).

[0015] <Polybutylene Terephthalate Resin (A)> Polybutylene terephthalate resin is a resin obtained by polycondensing a dicarboxylic acid component containing at least terephthalic acid or its ester-forming derivative (C1-C6 alkyl ester, acid halide, etc.) and a glycol component containing at least an alkylene glycol having 4 carbon atoms (1,4-butanediol) or its ester-forming derivative (acetyl化物, etc.). The polybutylene terephthalate resin used in the present invention is not limited to a homopolybutylene terephthalate resin, and may also be a copolymer containing 60 mol% or more (particularly 75 mol% or more and 95 mol% or less) of butylene terephthalate units.

[0016] Examples of dicarboxylic acid components (comonomer components) 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. C8-C 14 ; C4-16 alkanedicarboxylic acids such as succinic acid, adipic acid, azelaic acid, sebacic acid, etc.; C5-C 10 cycloalkanedicarboxylic acids such as cyclohexanedicarboxylic acid; ester-forming derivatives of these dicarboxylic acid components (C1-C6 alkyl ester derivatives, acid halides, etc.) are included. These dicarboxylic acid components may be used alone or in combination of two or more.

[0017] Among these dicarboxylic acid components, aromatic dicarboxylic acids such as isophthalic acid, etc. C8-C 12 and C6-C 12 alkanedicarboxylic acids such as adipic acid, azelaic acid, sebacic acid, etc. are preferred.

[0018] Examples of glycol components other than 1,4-butanediol (or their ester-forming derivatives) include aliphatic alkanediols such as ethylene glycol, trimethylene glycol, propylene glycol, 1,4-butanediol, neopentyl glycol, 1,6-hexanediol, 1,3-octanediol, 1,8-octanediol, and decanediol; (poly)oxyalkylene glycols such as diethylene glycol, dipropylene glycol, ditetramethylene glycol, triethylene glycol, tripropylene glycol, and polytetramethylene glycol; alicyclic diols such as 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, and hydrogenated bisphenol A; aromatic diols such as hydroquinone, resorcinol, and naphthalenediol; biphenols such as 4,4'-dihydroxybiphenyl; bisphenols such as xylylene glycol; and ester-forming derivatives such as alkyl, alkoxy, or halogen-substituted derivatives.

[0019] Furthermore, polyols such as glycerin, trimethylolpropane, trimethylolethane, and pentaerythritol, or their ester-forming derivatives, may be used in combination. Branched polybutylene terephthalate resins can also be obtained by using such polyfunctional compounds in combination.

[0020] In one embodiment of the present invention, the polybutylene terephthalate resin has a weight-average molecular weight (Mw) of 60,000 or more in the resin composition, as measured by gel permeation chromatography. By using a polybutylene terephthalate resin having a weight-average molecular weight (Mw) of 60,000 or more in the resin composition, it is possible to obtain a molded product (hereinafter also referred to as "automotive connector") that has good mechanical strength and good flame retardancy.

[0021] Furthermore, the weight-average molecular weight (Mw) is preferably between 60,000 and 90,000, and more preferably between 60,000 and 85,000. By setting the weight-average molecular weight in the resin composition within the above range, it is possible to more effectively reduce the breakage of the connector joints and lance portions under low-temperature conditions. In this specification, the weight-average molecular weight (Mw) is a value measured by gel permeation chromatography (GPC) and converted using a calibration curve created with standard polystyrene.

[0022] The amount of terminal carboxyl groups in the polybutylene terephthalate resin is not particularly limited, but is preferably 1 to 30 meq / kg, more preferably 2 to 19 meq / kg, and even more preferably 3 to 15 meq / kg. By setting the amount of terminal carboxyl groups within the above range, hydrolysis resistance can be imparted to the polybutylene terephthalate resin composition.

[0023] The intrinsic viscosity (IV) of the polybutylene terephthalate resin is not particularly limited, but is preferably between 0.81 dL / g and 1.2 dL / g, and more preferably between 0.82 dL / g and 1.0 dL / g. By using a polybutylene terephthalate resin with an intrinsic viscosity within the above range, a polybutylene terephthalate resin composition with excellent hydrolysis resistance and moldability can be obtained. Furthermore, the intrinsic viscosity can be adjusted by blending polybutylene terephthalate resins having different intrinsic viscosities. The intrinsic viscosity of the polybutylene terephthalate resin can be measured, for example, using an Ubbelohde viscometer in o-chlorophenol at a temperature of 35°C.

[0024] In the present invention, the polybutylene terephthalate resin may be a commercially available product (for example, Duranex® PBT manufactured by Polyplastics Co., Ltd.) or one produced by copolymerization (polycondensation) using conventional methods (for example, transesterification, direct esterification, etc.).

[0025] <Flame retardant (B)> Known flame retardants can be used. Examples of flame retardants include halogenated flame retardants (halogenated aromatic compounds, etc.), phosphorus-based flame retardants (nitrogen-containing phosphate compounds, phosphate esters, etc.), inorganic flame retardants (metal hydroxides, etc.), nitrogen-based flame retardants (guanidine, triazine, melamine and their derivatives, etc.), silicon-containing flame retardants, etc. Among these, halogenated flame retardants are preferred in order to ensure flame retardancy, and among halogenated flame retardants, brominated flame retardants are preferred.

[0026] Examples of brominated flame retardants include brominated acrylate polymers, brominated styrene polymers, brominated polycarbonate polymers, brominated epoxy compounds, brominated bisphenol-type phenoxy resins, brominated polyaryl ether compounds, brominated aromatic imide compounds, brominated bisaryl compounds, and brominated tri(aryloxy)triazine compounds. Among these, brominated acrylate polymers (such as polymers of pentabromobenzyl acrylate, tetrabromobenzyl acrylate, tribromobenzyl acrylate, or mixtures thereof) or brominated epoxy compounds (such as tetrabromobisphenol A-type epoxy compounds) are preferred. These brominated flame retardants may be used individually or in combination of two or more types.

[0027] The flame retardant content is preferably 10 to 40 parts by mass, and more preferably 15 to 30 parts by mass, per 100 parts by mass of polybutylene terephthalate resin. By setting the flame retardant content within the above range, sufficient flame retardancy and moldability can be imparted to automotive connectors made from polybutylene terephthalate resin compositions. However, if the flame retardant content exceeds 40 parts by mass, mold corrosion and the generation of foreign matter are more likely to occur.

[0028] <Flame retardant additive (C)> Known flame retardants can be used. Examples of flame retardants include aromatic compounds (phenolic resins, aniline resins, polyphenylene oxide resins, aromatic epoxy resins (bisphenol-type epoxy resins, novolac-type epoxy resins, etc.), phenoxy resins, polyphenylene sulfide resins, polycarbonate resins, polyarylate resins, aromatic polyamide resins, aromatic polyester resins (for example, aromatic polyester resins that may be liquid crystalline), aromatic polyesteramide resins (for example, aromatic polyesteramide resins that may be liquid crystalline), etc.), phosphorus-containing compounds (phosphorus-containing compounds that do not belong to organic or inorganic salts such as organic phosphinic acids), antimony-containing compounds, molybdenum-containing compounds (molybdenum oxide, etc.), tungsten-containing compounds (tungsten oxide, etc.) These include stainless steel, bismuth-containing compounds (bismuth oxide, etc.), tin-containing compounds (tin oxide, etc.), iron-containing compounds (iron oxide, etc.), copper-containing compounds (copper oxide, etc.), silicon-containing compounds [(poly)organosiloxanes (silicone resins such as polydimethylsiloxane and polymethylphenylsiloxane, silicone oils, polysilsesquioxane, etc.), layered silicates (smectite-based layered silicates such as montmorillonite, Li-type fluoroteniolite, Na-type fluoroteniolite, Li-type tetrasilicon fluorimica, Na-type tetrasilicon fluorimica, etc., swellable synthetic fluorimica, vermulite, halloysite, etc.)], sulfur-containing compounds (organosulfonic acid compounds, metal salts of perfluoroalkanesulfonic acid, sulfamic acid compounds or their salts, etc.). Among these, when used in combination with brominated flame retardants, antimony-containing compounds are preferred from the viewpoint of further improving flame retardancy. These flame retardant additives may be used individually or in combination of two or more types.

[0029] Examples of antimony-containing compounds include antimony oxides (antimony trioxide, antimony tetroxide, antimony pentoxide, etc.) and antimonate salts (alkali metal salts such as sodium antimonate, alkaline earth metal salts such as magnesium antimonate, ammonium antimonate, etc.). Among these, antimony trioxide is preferred. These antimony-containing compounds may be used individually or in combination of two or more.

[0030] Antimony-containing compounds may, if necessary, be surface-treated with surface treatment agents such as epoxy compounds, silane compounds, isocyanate compounds, and / or titanate compounds.

[0031] Furthermore, the content of the flame retardant additive is 6 to 11 parts by mass, preferably 6.5 to 10.5 parts by mass, per 100 parts by mass of polybutylene terephthalate resin. By setting the content of the flame retardant additive within the above range, it is less likely that mechanical stress will cause the connector joints and lance portions to become the starting point for fracture, thereby reducing the likelihood of them breaking.

[0032] <Elastomer (D)> Known elastomers can be used. Examples of elastomers include thermoplastic elastomers, thermosetting elastomers, and core-shell elastomers. Of these, thermoplastic elastomers are preferred from the viewpoint of mechanical strength. Examples of thermoplastic elastomers include olefin-based elastomers, diene-based elastomers, styrene-based elastomers, and polyester-based elastomers. Of these, olefin-based elastomers are preferred from the viewpoint of hydrolysis resistance.

[0033] Examples of olefin-based elastomers include copolymers containing at least one unit selected from ethylene-propylene copolymer, ethylene-butene copolymer, ethylene-octene copolymer, ethylene-propylene-diene copolymer, ethylene-propylene-butene copolymer, ethylene-vinyl acetate copolymer, ethylene-propylene copolymer, and ethylene-propylene-diene copolymer; copolymers of olefins and (meth)acrylic monomers such as ethylene-ethyl acrylate copolymer and ethylene-glycidyl methacrylate copolymer; and modified olefin resins [for example, acid-modified olefin resins obtained by modifying olefin resins (olefins alone or copolymers) with acid components (for example, α,β-unsaturated carboxylic acids ((meth)acrylic acid, maleic acid, fumaric acid, itaconic acid, citraconic acid, nadic acid, etc.) and / or their acid anhydrides, etc.)]. Among these, ethylene-ethyl acrylate copolymer is preferred. These olefin-based elastomers may be used individually or in combination of two or more types.

[0034] Polyester elastomers can be classified into polyether-type ester elastomers and polyester-type ester elastomers. Examples of polyether-type ester elastomers include polyester elastomers in which aromatic polyester is used as the hard segment and polyester consisting of an oxyalkylene glycol polymer and a dicarboxylic acid is used as the soft segment. The aromatic polyester units in the hard segment are preferably polycondensates of dicarboxylic acid compounds and dihydroxy compounds, polycondensates of oxycarboxylic acid compounds, or polycondensates of these three-component compounds. For example, polybutylene terephthalate can be used as the hard segment. For example, compounds obtained by polycondensation of polyalkylene ether and dicarboxylic acid can be used as the soft segment, and examples of these include ester compounds of polyoxytetramethylene glycol derived from tetrahydrofuran.

[0035] Examples of polyester-type ester elastomers include polyester elastomers in which aromatic polyester is used as the hard segment and amorphous polyester is used as the soft segment. The aromatic polyester units in the hard segment are the same as those in the polyether type described above. Examples of the soft segment include ring-opening polymers of lactones (polylactones) or aliphatic polyesters derived from aliphatic dicarboxylic acids and aliphatic diols.

[0036] The elastomer content is 7 to 30 parts by mass per 100 parts by mass of polybutylene terephthalate resin. By setting the elastomer content within the above range, an automotive connector with good mechanical strength and good flame retardancy can be obtained.

[0037] Furthermore, the elastomer content is more preferably 7 to 25 parts by mass, and even more preferably 7 to 20 parts by mass, per 100 parts by mass of polybutylene terephthalate resin. By setting the elastomer content within the above range, sufficient toughness and flame retardancy can be more effectively imparted to automotive connectors. If the elastomer content is higher than the above range, the flame retardancy will decrease, and if it is lower than the above range, sufficient toughness cannot be obtained.

[0038] <Glass fiber (E)> In this specification, "glass fiber" means a fibrous material cut perpendicular to the length direction. Examples of glass fibers include A glass, C glass, D glass, E glass, AR glass, ECR glass, M glass, NE glass, and S glass. The type of glass used as raw material is not particularly limited, but in terms of quality, E glass, low-dielectric glass with low alkaline earth components (CaO, MgO) in its composition, and corrosion-resistant glass containing zirconium are preferred.

[0039] The glass fibers preferably have a number-average fiber diameter of 3 to 25 μm, and more preferably 5 to 17 μm.

[0040] Furthermore, the form of the glass fibers may be any of the following: glass roving made by continuously winding single fibers or bundles of multiple single fibers; chopped strands (glass fibers with a number-average fiber length of 1 to 10 mm) cut to a length of 1 to 10 mm; or milled fibers (glass fibers with a number-average fiber length of 10 to 500 μm) crushed to a length of approximately 10 to 500 μm. These may be used individually or in combination of two or more types.

[0041] In one embodiment of the present invention, the glass fiber content is 15 to 40 parts by mass, preferably 15 to 37 parts by mass, per 100 parts by mass of polybutylene terephthalate resin. By setting the glass fiber content within the above range, an automotive connector having the desired mechanical strength can be obtained. Furthermore, from the viewpoint of fluidity and impact resistance, the glass fiber content is preferably 10 to 20% by mass of the total mass of the polybutylene terephthalate resin composition.

[0042] Furthermore, the ratio of the total mass of the elastomer and glass fiber to the mass of the polybutylene terephthalate resin is preferably 0.2 to 0.6, and more preferably 0.2 to 0.5. By setting this ratio within the above range, an automotive connector with good mechanical strength and good flame retardancy can be obtained.

[0043] <Other additives> Furthermore, the polybutylene terephthalate resin composition according to one embodiment of the present invention may contain, in any proportion, a lubricant (such as pentaerythritol tetrastearate), a dripping inhibitor (such as polytetrafluoroethylene), a colorant (such as carbon black), and an antioxidant (such as a hindered phenol-based antioxidant).

[0044] Furthermore, known stabilizers (ultraviolet absorbers, light stabilizers, etc.), mold release agents, flame retardants and flame retardant aids other than those mentioned above, crystallization nucleating agents, lubricants, plasticizers, etc. may be added as needed.

[0045] <Method for producing polybutylene terephthalate resin composition> Polybutylene terephthalate resin compositions can be produced by melt-kneading 100 parts by weight of polybutylene terephthalate resin with a flame retardant, a flame retardant additive, an elastomer, glass fibers, and any other additives using a twin-screw continuous extruder mixer, a twin-screw paddle extruder, a vented twin-screw extruder, etc.

[0046] A polybutylene terephthalate resin composition according to one embodiment of the present invention can be used to obtain automotive connectors with a lance width of 0.5 to 4.0 mm. It can also be used to obtain automotive connectors with a terminal width of 0.5 mm to 9.5 mm, and is particularly useful for connectors with a terminal width of 0.64 mm to 6.3 mm.

[0047] [Automotive connectors] Figure 1 shows the shape (overall view) of an automotive connector according to one embodiment of the present invention. The shape of the connector is not particularly limited and can be selected according to the application. Examples of the shape of the connector include (omitted) square, (omitted) rectangular, (omitted) spherical, (omitted) elliptical, etc. Examples of applications for the connector include automobiles (for example, for automobiles with a rated current of 0.2A or more), electric vehicle engines, motors, batteries, power control units, E-Axles (electric axles), Lidar, sensors, etc. Waterproof or non-waterproof connectors, connectors with a double locking structure, etc. can also be used depending on the application.

[0048] Figure 2(a) is a front view of the connector 10 shown in Figure 1. Figure 2(b) is a cross-sectional view of the connector 10 shown in Figure 1 along line A-A', showing a cross-section of the terminal insertion opening 11 as an example. As shown in Figure 2(b), a lance 12 is formed inside the terminal insertion opening 11. Figure 2(b) shows an automotive connector with a lance width of 4.0 mm, but is not limited to this. The present invention can be used in automotive connectors with a lance width of 0.5 to 4.0 mm. Furthermore, the present invention can provide automotive connectors with a terminal width of 0.5 mm or more and 9.5 mm or less. In particular, it can be used in automotive connectors with a terminal width of 0.64 mm or more and 6.3 mm or less.

[0049] Furthermore, the tensile breaking strength of the automotive connector according to one embodiment of the present invention at 23°C is 78 MPa or higher, and more preferably 80 MPa or higher. A tensile breaking strength of 78 MPa or higher allows for sufficient terminal retention force and reduces the risk of lance damage when the wire is pulled, thereby maintaining the product function of the connector. The tensile breaking strength and tensile breaking strain can be measured, for example, using a universal testing machine, such as the Autograph (manufactured by Shimadzu Corporation).

[0050] Furthermore, the flexural modulus of the connector according to one embodiment of the present invention is 8000 MPa or less at 23°C, and more preferably 7000 MPa or less. A flexural modulus of 8000 MPa or less enables stable production because the insertion force required when inserting terminals during connector manufacturing does not become excessively high. The flexural modulus can be measured, for example, using the universal testing machine Autograph described above.

[0051] In particular, during production and repair in cold regions, the lance portion of a connector may break when inserting or removing terminals. This is due to a combination of factors, including the impact resistance and toughness of the connector at low temperatures, and it is difficult to predict whether or not the lance portion of the connector will break based on a single characteristic such as tensile fracture strain alone. Therefore, by using a polybutylene terephthalate resin composition that provides mechanical properties such as good low-temperature lance characteristics, terminal retention force (tensile fracture strength), and terminal insertion force (flexural modulus) in addition to flame retardancy, it is possible to realize automotive connectors with high electrical safety and reliability. [Examples]

[0052] The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.

[0053] [Method for producing polybutylene terephthalate resin composition] A container was filled with 100 parts by mass of polybutylene terephthalate resin. Flame retardant, flame retardant additive, elastomer, glass fiber, and additives were mixed in the amounts shown in Table 1. The mixture was then melt-kneaded and extruded using a twin-screw extruder (TEX30, manufactured by Japan Steel Works Ltd.) with a 30 mm diameter screw, under conditions of a cylinder temperature of 260°C and a screw rotation speed of 130 rpm, to obtain a pellet-shaped polybutylene terephthalate (PBT) resin composition. The units of the values ​​in Table 1 are parts by mass.

[0054] The constituent components of the polybutylene terephthalate resin composition shown in Table 1 are as follows:

[0055] <Polybutylene terephthalate resin (A)> (A-1) Polybutylene terephthalate resin (Manufactured by Polyplastics, Inc., weight-average molecular weight (Mw) 84000, terminal carboxyl group content 9 meq / kg) (A-2) Polybutylene terephthalate resin (Manufactured by Polyplastics, Inc., weight-average molecular weight (Mw) 69000, terminal carboxyl group content 12 meq / kg) (A-3) Polybutylene terephthalate resin (Manufactured by Polyplastics, Inc., weight-average molecular weight (Mw) 58000, terminal carboxyl group content 20 meq / kg)

[0056] <Flame retardant (B)> (B-1) Pentabromobenzyl polyacrylate (FR-1025, manufactured by ICL JAPAN) (B-2) Tetrabromobisphenol A type epoxy resin (CXB-1500C, manufactured by Yushin Polymer Co., Ltd.)

[0057] <Flame retardant additive (C)> (C-1) Antimony trioxide (PATOX-M, manufactured by Nippon Seikou Co., Ltd.)

[0058] <Elastomer (D)> (D-1) Ethylene-ethyl acrylate copolymer (NUC-6570, manufactured by ENEOS NUC Corporation) (D-2) Ethylene-glycidyl methacrylate copolymer (Bondfast 7L, manufactured by Sumitomo Chemical Co., Ltd.) (D-3) Polyester elastomer (Perprene GP400, manufactured by Toyobo Co., Ltd.)

[0059] <Glass fiber (E)> (E-1) Glass fiber (ECS03 T-187, manufactured by Nippon Electric Glass Co., Ltd.)

[0060] <Other additives> Dripping prevention agent (F-1) Polytetrafluoroethylene (Polyflon® MPA FA-500H, manufactured by Daikin Industries, Ltd.) Antioxidants (G-1) Hindered phenol antioxidant (IRGANOX® 1010, manufactured by BASF) Lubricant (H-1) Pentaerythritol stearate (Unistar H476, manufactured by NOF Corporation) <Coloring agents> (I-1) Carbon Black (MA600B, manufactured by Mitsubishi Chemical Corporation)

[0061] [evaluation] For polybutylene terephthalate resin compositions 1 to 19, low-temperature lance breakage evaluation, terminal insertion force evaluation, terminal retention force evaluation, flame retardancy evaluation, tensile fracture strength evaluation, tensile fracture strain evaluation, and flexural modulus evaluation were performed as described below. In addition, the weight-average molecular weight (Mw) and melt viscosity were measured for polybutylene terephthalate resin compositions 1 to 19 as described below. The results of each evaluation and measurement are shown in Table 1. In Table 1, "PBT" means "polybutylene terephthalate".

[0062] <Lance breakage evaluation at low temperatures> Polybutylene terephthalate resin compositions 1 to 19 shown in Table 1 were used to injection-molde connectors of the shape shown in Figure 1 using an injection molding machine (ROBOSHOT S-2000i 100B, manufactured by FANUC) under the conditions of a cylinder temperature of 260°C, a mold temperature of 80°C, and an injection speed of 90 mm / second. The number of lance breaks was measured when a terminal with a terminal width of 2.3 mm was attached to the resulting connector 20 times at -20°C. A number of lance breaks of 5 or less was considered a pass (○).

[0063] <Evaluation of terminal insertion force> The strength of terminal insertion into the connector manufactured using the method described above was measured, referencing the automotive standard (JASO D616, Section 6.6) issued by the Japan Society of Automotive Engineers of Japan. A strength of less than 30N during terminal insertion was considered acceptable (○).

[0064] <Terminal retention force evaluation> Referring to JASO D616 Section 6.7, the strength of the terminals when pulled from the connector made using the method described above was measured at the time of removal or breakage, and a strength of 100N or more was considered acceptable (○).

[0065] <Flame retardancy evaluation> Flame retardancy (V-0: total burning time of 5 test specimens less than 50 seconds) was tested using five test specimens (thickness: 0.75 mm, made of the PBT resin composition shown in Table 1) in accordance with the Subject 94 (UL94) method of Underwriters Laboratories. Those that met the V-0 certification criteria were deemed to have passed (○).

[0066] <Tensile breaking strength evaluation> Polybutylene terephthalate resin compositions 1 to 19 were dried at 140°C for 3 hours, and then placed in an injection molding machine (ROBOSHOT α-100iA, FANUC) and injected under conditions of cylinder temperature 260°C and mold temperature 80°C to obtain Type 1A test specimens in accordance with ISO 3167. Using these test specimens, the tensile breaking strength (MPa) was measured using a universal testing machine, Autograph (Shimadzu Corporation), in accordance with ISO 527-1,2.

[0067] <Tensile fracture strain evaluation> Type 1A specimens were prepared in the same manner as for evaluating tensile fracture strength, and the tensile fracture strain (%) was measured using the same Autograph universal testing machine.

[0068] <Evaluation of flexural modulus> The flexural modulus (MPa) of polybutylene terephthalate resin compositions 1 to 19 was measured using the above-mentioned universal testing machine, Autograph, in accordance with ISO 178, with Type 1A test specimens molded for the evaluation of tensile fracture strength.

[0069] <Measurement of weight-average molecular weight> Polybutylene terephthalate resin compositions 1 to 19 were dissolved in a hexafluoroisopropanol / chloroform = 1 / 1 solvent to prepare measurement solutions for polybutylene terephthalate resin compositions 1 to 19. Then, the weight-average molecular weight (Mw) of polybutylene terephthalate resin compositions 1 to 19 was measured under the following conditions. Equipment: High-performance liquid chromatograph "HLC-8320GPC" (manufactured by Tosoh Corporation) Column: "TSKgel Super HZM-M" (manufactured by Tosoh Corporation) Sample concentration: 1 mg / mL Concentration eluent: Chloroform Flow rate: 0.35ml / min Detection device: UV / (254nm) Measurement temperature: 40℃ Reference material: Standard polystyrene (manufactured by Polymer Laboratories, Mw: 377400~580)

[0070] <Measurement of melt viscosity> After drying the polybutylene terephthalate resin composition at 140°C for 3 hours, the composition was subjected to a shearing test in accordance with ISO 11443 using a capillary rheometer "Capillograph® 1B" (manufactured by Toyo Seiki Seisakusho Co., Ltd.) with a furnace temperature of 260°C, a capillary diameter of φ1 mm × 20 mm L, and a shearing rate of 1000 sec. -1 The measurements were taken under the following conditions.

[0071] [Table 1]

[0072] As shown in Table 1, it was found that an automotive connector made of a polybutylene terephthalate resin composition can be provided that has good mechanical strength and good flame retardancy even under low temperature conditions. [Industrial applicability]

[0073] The polybutylene terephthalate resin composition of the present invention is particularly effective for automotive connectors that have good mechanical strength and good flame retardancy even under low temperature conditions, as it can be used in parts used at low temperatures. [Explanation of symbols]

[0074] 10 connectors 11 Terminal insertion slot 12 Lance

Claims

1. Polybutylene terephthalate resin (A), Flame retardant (B), Flame retardant additive (C), Elastomer (D) and A polybutylene terephthalate resin composition comprising glass fiber (E), The content of the flame retardant additive (C) is 6 to 11 parts by mass per 100 parts by mass of the polybutylene terephthalate resin (A), The content of the elastomer (D) is 7 to 30 parts by mass per 100 parts by mass of the polybutylene terephthalate resin (A), The content of the glass fiber (E) is 15 to 40 parts by mass per 100 parts by mass of the polybutylene terephthalate resin (A), The weight-average molecular weight of the polybutylene terephthalate resin (A) in the resin composition, as measured by gel permeation chromatography, is 60,000 or more. A polybutylene terephthalate resin composition used in automotive connectors.

2. The polybutylene terephthalate resin composition according to claim 1, wherein the ratio of the total mass of the elastomer (D) and the glass fiber (E) to the mass of the polybutylene terephthalate resin (A) is 0.2 to 0.

6.

3. The polybutylene terephthalate resin composition according to claim 1 or 2, wherein the flame retardant (B) is a brominated flame retardant.

4. The polybutylene terephthalate resin composition according to claim 1 or 2, wherein the elastomer (D) is an olefin-based elastomer.

5. An automotive connector comprising the polybutylene terephthalate resin composition according to claim 1 or 2.

6. The automotive connector according to claim 5, wherein the tensile strength is 80 MPa or more.

7. The automotive connector according to claim 5, wherein the flexural modulus is 8000 MPa or less.

8. The automotive connector according to claim 5, wherein the terminal width is 0.5 mm or more and 9.5 mm or less.

9. The automotive connector according to claim 5, wherein the rated current is 0.2A or more and is for automotive use.

10. The automotive connector according to claim 5, which is of the waterproof type.

11. The automotive connector according to claim 5, for use in electric vehicles, hybrid vehicles, and fuel cell vehicles.

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