Flame-retardant polybutylene terephthalate resin composition and resin molded article

Abstract

To provide a flame-retardant polybutylene terephthalate resin composition which is excellent in flame retardancy, tracking resistance, hydrolysis resistance, and low warpage property, and has low melt viscosity.SOLUTION: A flame-retardant polybutylene terephthalate resin composition contains, with respect to 100 pts.mass of (A) a PBT resin, 10-120 pts.mass of (B) a fibrous inorganic compound, 30-80 pts.mass of (C) at least one selected from the group consisting of a predetermined phosphinate, a predetermined diphosphinate, and a polymer of them, 6-25 pts.mass of (D) a salt of a triazine-based compound, and a cyanuric acid or an isocyanuric acid, 10-25 pts.mass of (E) a thermoplastic polyester elastomer, 1-3 pts.mass of (F) a polycarbodiimide compound, 0-3 pts.mass of (G) a fluororesin, and 40-80 pts.mass of (H) a polymer or a copolymer including a repeating unit derived from an aromatic vinyl compound.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a flame-retardant polybutylene terephthalate resin composition and a resin molded article. [Background technology]

[0002] Polybutylene terephthalate resin (hereinafter referred to as "PBT resin") has excellent mechanical properties, electrical properties, heat resistance, weather resistance, water resistance, and chemical resistance, making it a useful engineering plastic. Furthermore, combining PBT resin with inorganic fillers such as glass fiber can improve heat resistance and mechanical strength. Therefore, PBT resin is often reinforced with inorganic fillers and is widely used in a variety of applications, including automotive parts and electrical and electronic components. In particular, in the automotive field, performance requirements for automotive parts are becoming increasingly sophisticated as electrification and product lifespans increase. For example, electric vehicle parts, such as high-voltage connectors, inlets, service plugs, battery components, motor insulators, and power module housings, require flame retardancy and tracking resistance to withstand fires and high voltages. In addition to low warpage for fitment and dimensional accuracy, improved properties such as hydrolysis resistance are also desired for durability.

[0003] In order to improve the tracking resistance of PBT resin, a PBT resin composition containing a phosphorus-based flame retardant and a nitrogen-containing compound in combination has been proposed (see Patent Document 1). Furthermore, since phosphorus-based flame retardants generally reduce hydrolysis resistance, resin compositions have been proposed that improve hydrolysis resistance by adding epoxy compounds or carbodiimides (see Patent Documents 2 and 3). Furthermore, a flame-retardant PBT resin composition containing modified polyester and / or styrene-based resin has been proposed to improve tracking resistance and low warpage (see Patent Document 4). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2011 / 148796 [Patent Document 2] Japanese Patent Application Publication No. 2019-44037 [Patent Document 3] Japanese Patent Application Laid-Open No. 2009-215347 [Patent Document 4] Japanese Patent Application Laid-Open No. 2007-091865 Summary of the Invention [Problem to be solved by the invention]

[0005] However, the resin compositions described in Patent Documents 1 to 4 have high melt viscosities and are not satisfactory in flame retardancy, tracking resistance, hydrolysis resistance, or low warpage. That is, conventional PBT resin compositions are not satisfactory in flame retardancy, tracking resistance, hydrolysis resistance, low melt viscosity, or low warpage, and further improvements are desired.

[0006] The present invention has been made in consideration of the above-mentioned conventional problems, and an object of the present invention is to provide a flame-retardant polybutylene terephthalate resin composition that is excellent in flame retardancy, tracking resistance, hydrolysis resistance, and low warpage, and that has a low melt viscosity, and a resin molded article obtained by molding the same. [Means for solving the problem]

[0007] One aspect of the present invention that solves the above problem is as follows.

[0008] (1) A flame-retardant polybutylene terephthalate resin composition comprising, relative to 100 parts by mass of (A) polybutylene terephthalate resin, 10 to 120 parts by mass of (B) a fibrous inorganic compound, 30 to 80 parts by mass of (C) at least one selected from the group consisting of a phosphinate salt represented by the following general formula (1) and a polymer thereof, and a diphosphinate salt represented by the following general formula (2) and a polymer thereof, (D) 6 to 25 parts by mass of a salt of a triazine compound with cyanuric acid or isocyanuric acid, (E) 10 to 25 parts by mass of a thermoplastic polyester elastomer, (F) 1 to 3 parts by mass of a polycarbodiimide compound, (G) 0 to 3 parts by mass of a fluororesin, and (H) 40 to 80 parts by mass of a styrene-based resin.

[0009] [ka] [In general formula (1) and general formula (2), R 1 , R 2 , R 3 and R 4 each independently represents an alkyl group, a cycloalkyl group, an aryl group, or an aralkyl group; R 5 represents an alkylene group, an alicyclic divalent group, or an aromatic divalent group. 1 and R 2 may be bonded to each other to form a ring with the adjacent phosphorus atom. a m+ represents a metal with a valence of m, where m is an integer of 2 to 4. b n+ represents a metal having a valence of n, where n is an integer of 2 to 4.

[0010] (2) The flame-retardant polybutylene terephthalate resin composition according to (1), wherein the phosphinate represented by the general formula (1), the polymer thereof, or the diphosphinate represented by the general formula (2) or the polymer thereof has a cumulative particle size (D95) measured in accordance with JIS8825 of 10 to 500 μm.

[0011] (3) The flame-retardant polybutylene terephthalate resin composition according to (1) or (2) above, wherein the polycarbodiimide compound (F) is an aromatic polycarbodiimide.

[0012] (4) A resin molded article obtained by molding the flame-retardant polybutylene terephthalate resin composition according to any one of (1) to (3) above. [Effects of the Invention]

[0013] According to the present invention, it is possible to provide a flame-retardant polybutylene terephthalate resin composition that is excellent in flame retardancy, tracking resistance, hydrolysis resistance, and low warpage, and that has a low melt viscosity, and a resin molded article obtained by molding the same. DETAILED DESCRIPTION OF THE INVENTION

[0014] <Polybutylene terephthalate resin composition> The flame-retardant polybutylene terephthalate resin composition (hereinafter also simply referred to as "PBT resin composition") of this embodiment is characterized by containing, relative to 100 parts by mass of (A) polybutylene terephthalate resin, 10 to 120 parts by mass of (B) a fibrous inorganic compound, 30 to 80 parts by mass of (C) at least one selected from the group consisting of a phosphinate salt represented by general formula (1) and a polymer thereof, and a diphosphinate salt represented by general formula (2) and a polymer thereof, (D) 6 to 25 parts by mass of a salt of a triazine compound and cyanuric acid or isocyanuric acid, (E) 10 to 25 parts by mass of a thermoplastic polyester elastomer, (F) 1 to 3 parts by mass of a polycarbodiimide compound, (G) 0 to 3 parts by mass of a fluororesin, and (H) 40 to 80 parts by mass of a styrene-based resin.

[0015] The PBT resin composition of the present embodiment contains, relative to 100 parts by mass of (A) PBT resin, predetermined amounts of (B) a fibrous inorganic compound, (C) at least one selected from the group consisting of a phosphinic acid salt represented by general formula (1), a polymer thereof, and a diphosphinic acid salt represented by general formula (2), and a polymer thereof (hereinafter also referred to as "(C) diphosphinic acid salt, etc."), (D) a triazine-based compound, a salt with cyanuric acid or isocyanuric acid, (E) a thermoplastic polyester elastomer, (F) a polycarbodiimide compound, (G) a fluororesin, and (H) a styrene-based resin (however, component (G) is an optional component), and thereby has excellent flame retardancy, tracking resistance, hydrolysis resistance, and low warpage, as well as a low melt viscosity. Each component will be described in detail below. In this specification, "(A) PBT resin" may be referred to as component (A), and the same applies to each of components (B) to (H).

[0016] [(A) Polybutylene terephthalate resin (PBT resin)] PBT resin is a resin obtained by polycondensation of a dicarboxylic acid component containing at least terephthalic acid or its ester-forming derivative (such as a C1-6 alkyl ester or acid halide) and a glycol component containing at least an alkylene glycol having four carbon atoms (1,4-butanediol) or its ester-forming derivative (such as an acetylated product). The PBT resin is not limited to homopolybutylene terephthalate, but may also be a copolymer containing 60 mol % or more (particularly 75 mol % to 95 mol %) of butylene terephthalate units.

[0017] The amount of terminal carboxyl groups in the PBT resin is not particularly limited as long as it does not impair the effects of the PBT resin composition of this embodiment. The amount of terminal carboxyl groups in the PBT resin is preferably 30 meq / kg or less, and more preferably 25 meq / kg or less.

[0018] The intrinsic viscosity (IV) of the PBT resin is preferably 0.69 to 1.00 dL / g. When a PBT resin having an intrinsic viscosity in this range is used, the resulting resin composition has a particularly low melt viscosity and excellent mechanical properties. Conversely, if the intrinsic viscosity is less than 0.69 dL / g, excellent mechanical properties and hydrolysis resistance may not be obtained, and if it exceeds 1.00 dL / g, the melt viscosity may become high. Furthermore, the intrinsic viscosity of a PBT resin having an intrinsic viscosity within the above range can be adjusted by blending PBT resins having different intrinsic viscosities. For example, a PBT resin having an intrinsic viscosity of 0.8 dL / g can be prepared by blending a PBT resin having an intrinsic viscosity of 0.9 dL / g with a PBT resin having an intrinsic viscosity of 0.7 dL / g. The intrinsic viscosity (IV) of a PBT resin can be measured, for example, in o-chlorophenol at 35°C.

[0019] In PBT resins, examples of dicarboxylic acid components (comonomer components) other than terephthalic acid and its ester-forming derivatives include C8-14 aromatic dicarboxylic acids such as isophthalic acid, phthalic acid, 2,6-naphthalenedicarboxylic acid, and 4,4'-dicarboxydiphenyl ether; C4-16 alkanedicarboxylic acids such as succinic acid, adipic acid, azelaic acid, and sebacic acid; C5-10 cycloalkanedicarboxylic acids such as cyclohexanedicarboxylic acid; and ester-forming derivatives of these dicarboxylic acid components (C1-6 alkyl ester derivatives, acid halides, etc.). These dicarboxylic acid components can be used alone or in combination of two or more.

[0020] Among these dicarboxylic acid components, C8-12 aromatic dicarboxylic acids such as isophthalic acid, and C6-12 alkanedicarboxylic acids such as adipic acid, azelaic acid, and sebacic acid are more preferred.

[0021] Examples of glycol components (comonomer components) other than 1,4-butanediol in PBT resins include C2-10 alkylene glycols such as ethylene glycol, propylene glycol, trimethylene glycol, 1,3-butylene glycol, hexamethylene glycol, neopentyl glycol, and 1,3-octanediol; polyoxyalkylene glycols such as diethylene glycol, triethylene glycol, and dipropylene glycol; alicyclic diols such as cyclohexanedimethanol and hydrogenated bisphenol A; aromatic diols such as bisphenol A and 4,4'-dihydroxybiphenyl; C2-4 alkylene oxide adducts of bisphenol A, such as an ethylene oxide 2-mol adduct of bisphenol A and a propylene oxide 3-mol adduct of bisphenol A; and ester-forming derivatives of these glycols (acetylated products, etc.). These glycol components can be used alone or in combination of two or more.

[0022] Among these glycol components, C2-6 alkylene glycols such as ethylene glycol and trimethylene glycol, polyoxyalkylene glycols such as diethylene glycol, and alicyclic diols such as cyclohexanedimethanol are more preferred.

[0023] Examples of comonomer components that can be used in addition to the dicarboxylic acid component and the glycol component include aromatic hydroxycarboxylic acids such as 4-hydroxybenzoic acid, 3-hydroxybenzoic acid, 6-hydroxy-2-naphthoic acid, and 4-carboxy-4'-hydroxybiphenyl; aliphatic hydroxycarboxylic acids such as glycolic acid and hydroxycaproic acid; C3-12 lactones such as propiolactone, butyrolactone, valerolactone, and caprolactone (e.g., ε-caprolactone); and ester-forming derivatives of these comonomer components (e.g., C1-6 alkyl ester derivatives, acid halides, and acetylated products).

[0024] [(B) Fibrous inorganic compound] In this embodiment, (B) the fibrous inorganic compound is used for the purpose of improving mechanical strength. Examples of the fibrous inorganic compound include mineral-derived fibers such as glass fiber, carbon fiber, zinc oxide fiber, titanium oxide fiber, wollastonite, silica fiber, silica-alumina fiber, zirconia fiber, boron nitride fiber, silicon nitride fiber, boron fiber, and potassium titanate fiber. Among these, glass fiber is preferred. These may be used alone or in combination of two or more.

[0025] When glass fibers are used, the type is not particularly limited, and for example, A glass, C glass, D glass, E glass, etc. can be used, but among these, it is preferable to use E glass (alkali-free glass).

[0026] In addition, the glass fibers are preferably used in the form of chopped strands (chopped glass fibers) obtained by bundling a large number of these fibers and cutting them to a predetermined length. The cut length of the chopped glass fibers is not particularly limited, and can be, for example, about 1 to 10 mm.

[0027] In this embodiment, the fibrous inorganic compound is contained in an amount of 10 to 120 parts by mass relative to 100 parts by mass of the PBT resin. If the amount is less than 10 parts by mass, the heat resistance and mechanical strength become insufficient, and if the amount is more than 120 parts by mass, the melt viscosity increases, the toughness decreases, and the appearance deteriorates. From the viewpoint of heat resistance and mechanical properties, the fibrous inorganic compound is contained in an amount of preferably 30 to 120 parts by mass, more preferably 50 to 115 parts by mass, and particularly preferably 80 to 110 parts by mass.

[0028] [(C) Phosphinates, diphosphinates, and their polymers] In the present embodiment, at least one selected from the group consisting of a phosphinate salt represented by the following general formula (1), a polymer thereof, and a diphosphinate salt represented by the following general formula (2) and a polymer thereof is used for the purpose of improving flame retardancy and tracking resistance.

[0029] [ka] [In general formula (1) and general formula (2), R 1 , R 2 , R 3 and R 4 each independently represents an alkyl group, a cycloalkyl group, an aryl group, or an aralkyl group; R 5 represents an alkylene group, an alicyclic divalent group, or an aromatic divalent group. 1 and R 2 may be bonded to each other to form a ring with the adjacent phosphorus atom. a m+ represents a metal with a valence of m, where m is an integer of 2 to 4. b n+ represents a metal having a valence of n, where n is an integer of 2 to 4.

[0030] R 1 ~R 4 Examples of the alkyl group represented by the formula (I) include linear or branched C1-6 alkyl groups such as methyl, ethyl, isopropyl, n-butyl, and t-butyl. Examples of the cycloalkyl group include C5-8 cycloalkyl groups such as cyclohexyl. Examples of the aryl group include C6-10 aryl groups such as phenyl. Examples of the aralkyl group include C6-10 aryl-C1-4 alkyl groups such as benzyl. Of these groups, alkyl groups (preferably C1-4 alkyl groups) and aryl groups (phenyl groups) are usually preferred.

[0031] R 1 and R 2 The ring formed by bonding with the adjacent phosphorus atom is a heterocycle having the phosphorus atom as a heteroatom constituting the ring (phosphorus atom-containing heterocycle), and typically includes a 4- to 20-membered heterocycle, preferably a 5- to 16-membered heterocycle. The phosphorus atom-containing heterocycle may also be a bicyclo ring. The phosphorus atom-containing heterocycle may have a substituent.

[0032] R 5Examples of the alkylene group represented by the formula (I) include linear or branched C alkylene groups which may have a substituent such as a C aryl group such as methylene, ethylene, phenylethylene, propylene, trimethylene, 1,4-butanediyl, 1,3-butanediyl, etc. Examples of the alicyclic divalent group include C alicyclic divalent groups such as cyclohexylene, cyclohexadimethylene, etc. Examples of aromatic divalent groups include C6-10 arylene groups which may have a substituent such as a C1-4 alkyl group such as a phenylene group or a tolylene group; C6-10 arylene diC1-4 alkylene groups which may have a C1-4 alkyl group such as a methyl group on the arene ring such as a xylylene group; and bisaryl groups which may have a C1-4 alkyl group such as a methyl group on the arene ring (for example, biphenylene groups; linear or branched C1-4 alkane-diC6-10 arylene groups such as metadiphenylene groups; divalent groups corresponding to C6-10 aryl ethers such as diphenyl ether; divalent groups corresponding to diC6-10 aryl ketones such as diphenyl ketone; and divalent groups corresponding to diC6-10 aryl sulfides such as diphenyl sulfide). 5 Among these, alkylene groups (particularly C1-6 alkylene groups, etc.) are preferred.

[0033] M a , M b Examples of the metal represented by include alkaline earth metals (magnesium, calcium, etc.), transition metals (iron, cobalt, nickel, copper, etc.), metals in Group 12 of the periodic table (zinc, etc.), and metals in Group 13 of the periodic table (aluminum, etc.). The metal salt may contain one of these metals or a combination of two or more of them. Of the metals, alkaline earth metals (magnesium, calcium, etc.) and metals in Group 13 of the periodic table (aluminum, etc.) are preferred.

[0034] M a , M b The valence of the metal represented by is divalent to tetravalent, more preferably divalent or trivalent.

[0035] Specific examples of the phosphinic acid represented by general formula (1) include dialkylphosphinic acid calcium salts (di-C alkylphosphinic acid calcium salts, etc.), such as dimethylphosphinic acid calcium, methylethylphosphinic acid calcium, and diethylphosphinic acid calcium; arylphosphinic acid calcium salts (mono- or di-C arylphosphinic acid calcium salts, etc.), such as phenylphosphinic acid calcium and diphenylphosphinic acid calcium; alkylarylphosphinic acid calcium salts (C alkyl-C arylphosphinic acid calcium salts, etc.), such as methylphenylphosphinic acid calcium; optionally substituted alkylenephosphinic acid calcium salts (C alkylenephosphinic acid calcium salts, etc.), such as 1-hydroxy-1H-phospholane-1-oxide calcium salt and 2-carboxy-1-hydroxy-1H-phospholane-1-oxide calcium salt; and aluminum salts corresponding to these calcium salts, as well as other metal salts.

[0036] Specific examples of the diphosphinate salt represented by general formula (2) include alkanebis(phosphinate) calcium salts such as ethane-1,2-bis(phosphinate) calcium salts [e.g., C1-10 alkanebis(phosphinate) calcium salts], alkanebis(alkylphosphinate) calcium salts such as ethane-1,2-bis(methylphosphinate) calcium salts [e.g., C1-10 alkanebis(C1-6 alkylphosphinate) calcium salts], Al salts corresponding to these Ca salts, and other metal salts.

[0037] Preferred phosphinic acids are metal salts represented by the above formula (1) or (2), particularly dialkylphosphinic acid metal salts (Ca salts, Al salts, etc.) and alkanebisphosphinic acid metal salts (Ca salts, Al salts, etc.).

[0038] In this embodiment, the cumulative particle size (D95) of (C) diphosphinate or the like measured according to JIS 8825 (hereinafter also referred to as "D95 particle size") is preferably 10 to 500 μm, more preferably 10 to 200 μm, and even more preferably 10 to 100 μm. If the D95 particle size is less than 10 μm, the hydrolysis resistance may decrease. If the D95 particle size is more than 500 μm, clogging may occur at the gate of the mold, which may result in a deterioration in the appearance of the molded article.

[0039] In this embodiment, the (C) phosphinate or the like is contained in an amount of 30 to 80 parts by mass relative to 100 parts by mass of the PBT resin. If the amount is less than 30 parts by mass, the flame retardancy becomes insufficient, and if the amount is more than 80 parts by mass, the mechanical properties and hydrolysis resistance decrease. The amount of at least one selected from the group consisting of a phosphinate represented by general formula (1), a polymer thereof, and a diphosphinate represented by general formula (2) and a polymer thereof is preferably 40 to 78 parts by mass, more preferably 42 to 60 parts by mass.

[0040] [(D) Salt of a triazine compound with cyanuric acid or isocyanuric acid] A salt of a triazine compound with cyanuric acid or isocyanuric acid serves as a flame retardant aid, and a preferred example of the salt is a salt of a triazine compound represented by the following general formula (3) with cyanuric acid or isocyanuric acid:

[0041] [ka] [In general formula (3), R 6 , R 7 are each independently a hydrogen atom, an amino group, an aryl group, or an oxyalkyl group having 1 to 3 carbon atoms, and R 6 , R 7 may be the same or different.

[0042] In this embodiment, it is particularly preferable to use melamine cyanurate among salts of the triazine compound represented by the general formula (3) above and cyanuric acid or isocyanuric acid.

[0043] The salt of the triazine compound with cyanuric acid or isocyanuric acid preferably has a cumulative particle size (D95) of 100 μm or less, more preferably 0.1 to 80 μm, and even more preferably 1 to 60 μm, as measured in accordance with JIS 8825. If the D95 particle size exceeds 100 μm, the melt viscosity may become high.

[0044] In this embodiment, the salt of a triazine compound and cyanuric acid or isocyanuric acid is contained in an amount of 6 to 25 parts by mass, and if it is less than 6 parts by mass, the flame retardancy becomes insufficient, and if it exceeds 25 parts by mass, it causes a decrease in mechanical properties such as strength and toughness. The salt of a triazine compound and cyanuric acid or isocyanuric acid is contained in an amount of preferably 7 to 20 parts by mass, and more preferably 8 to 18 parts by mass.

[0045] [(E) Thermoplastic polyester elastomer] Thermoplastic polyester elastomers are used to improve the toughness of resin compositions. Furthermore, compared to common olefin-based elastomers, such as copolymers of polyethylene or polypropylene as hard segments and polypropylene rubber as soft segments, or ethylene-vinyl acetate copolymers, thermoplastic polyester elastomers have superior flame retardancy. Thermoplastic polyester elastomers are generally block copolymers having a structure in which a hard polyester block (a hard block or hard segment such as an aromatic polyester) and a soft polyester block (a soft block or soft segment) are bonded via ester bonds. Thermoplastic polyester elastomers can be classified into two types, polyether type and polyester type, depending on the type of soft block. Either type can be used in the present embodiment.

[0046] The hard polyesters constituting the hard blocks can be obtained by polycondensation of dicarboxylic acids and diols, or polycondensation of hydroxycarboxylic acids, similar to PBT resins. Typically, aromatic polyesters are used that contain at least aromatic monomer components (such as the aromatic diols and their reactive derivatives exemplified in the PBT resin section above, the aromatic dicarboxylic acids and terephthalic acid exemplified in the PBT resin section above (including reactive derivatives of these aromatic dicarboxylic acids), and / or aromatic hydroxycarboxylic acids (such as hydroxybenzoic acid, hydroxynaphthoic acid, 4-carboxy-4'hydroxybiphenyl, and derivatives of these hydroxycarboxylic acids (e.g., alkyl-, alkoxy-, or halogen-substituted derivatives)). The aromatic monomer components can be used alone or in combination. If necessary, copolymerizable monomers (such as the copolymerizable monomers exemplified in the PBT resin section above, as well as 1,4-butanediol and terephthalic acid) can be used in combination with the aromatic polyesters.

[0047] The aromatic polyester may be one which uses at least an aromatic monomer component as a monomer component, and may be, for example, a wholly aromatic polyester (such as a polyester of an aromatic dicarboxylic acid and an aromatic diol, or a polyester of an aromatic oxycarboxylic acid), a polyester of an aromatic dicarboxylic acid and a non-aromatic diol (such as 1,4-butanediol, or an aliphatic diol or alicyclic diol exemplified in the section on PBT resin), a polyester of a non-aromatic dicarboxylic acid (such as an aliphatic dicarboxylic acid exemplified in the section on PBT resin) and an aromatic diol, or a polyester of an aromatic oxycarboxylic acid and a non-aromatic oxycarboxylic acid (such as an aliphatic oxycarboxylic acid such as glycolic acid or oxycaproic acid).

[0048] Among rigid polyesters, preferred are crystalline aromatic polyesters [for example, polyalkylene arylates (polyC2-4 alkylene arylates such as polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, and polybutylene naphthalate, and modified polyC2-4 alkylene arylates modified or copolymerized with 1 to 30 mol % (for example, 3 to 25 mol %, preferably about 5 to 20 mol %) of a copolymerization component (a copolymerizable monomer exemplified above such as isophthalic acid)], liquid crystal polyesters, and in particular, polybutylene terephthalate.

[0049] The soft polyester constituting the soft block of the polyester-type elastomer can be obtained by polycondensation of dicarboxylic acids and diols, or polycondensation of oxycarboxylic acids or lactones, as in the case of PBT resin. The soft polyester is sufficient as long as it is more flexible than the hard polyester constituting the hard block. Typically, polyesters using at least aliphatic monomer components (aliphatic diols (1,4-butanediol, the aliphatic diols and their reactive derivatives exemplified in the PBT resin section, etc.), aliphatic dicarboxylic acids (aliphatic dicarboxylic acids and their reactive derivatives exemplified in the PBT resin section, etc.), aliphatic oxycarboxylic acids (glycolic acid, oxycaproic acid, etc.), and lactones exemplified in the PBT resin section) can be used. If necessary, the aliphatic monomer components may be used in combination with copolymerizable monomers (typically non-aromatic monomer components, such as the alicyclic diols and alicyclic dicarboxylic acids exemplified in the PBT resin section, and their reactive derivatives).

[0050] Of the soft polyesters, amorphous polyesters, for example, aliphatic polyesters using aliphatic dicarboxylic acids and aliphatic diols, and polylactones (ring-opening polymers of the above lactones) are preferred.

[0051] The soft segment of the polyether elastomer must contain at least a polyether unit and can be composed of a polyether [e.g., an aliphatic polyether having a polyoxyalkylene unit (e.g., the polyoxyalkylene glycols exemplified in the section on PBT resin, preferably polyC2-6 alkylene glycol)] or a polyester using such a polyether. Among polyethers, polyC2-4 alkylene glycols such as polyoxyethylene glycol, polyoxypropylene glycol, and polyoxytetramethylene glycol are preferred. Polyesters using polyethers include polyesters of polyethers (e.g., polyoxyalkylene glycols) and dicarboxylic acids [usually non-aromatic dicarboxylic acids, e.g., the aliphatic or alicyclic dicarboxylic acids exemplified in the section on PBT resin, and their reactive derivatives].

[0052] Of these soft blocks, soft polyester blocks having at least one unit selected from polyether units (aliphatic polyether units, polyester units using aliphatic polyethers) and aliphatic polyester units are preferred.

[0053] Specific examples of thermoplastic polyester elastomers include polyester-type (i.e., polyester-polyester-type) thermoplastic elastomers (e.g., block copolymers of a hard segment composed of an aromatic crystalline polyester or liquid crystal polyester, such as poly(C2-4 alkylene arylate) (particularly a homopolymer having polybutylene terephthalate units, or a copolymer copolymerized with a comonomer component (e.g., ethylene glycol, isophthalic acid)), and a soft segment composed of an aliphatic polyester (e.g., a polyester of a C2-6 alkylene glycol and a C6-12 alkanedicarboxylic acid, such as polyethylene adipate or polybutylene adipate)), and polyether-type (i.e., polyester-polyether-type) thermoplastic elastomers (e.g., block copolymers of a hard segment composed of an aromatic crystalline polyester or liquid crystal polyester and a soft segment composed of a polyether, such as polyoxy C2-4 alkylene glycol, e.g., polytetramethylene ether glycol (e.g., a polyester of a polyoxyalkylene glycol and a dicarboxylic acid).

[0054] Among polyester elastomers, block copolymers of a hard polyalkylene arylate block and a soft polyester block composed of polycaprolactone, an aliphatic polyether having an oxyC2-6 alkylene unit (such as polyC2-6 alkylene glycol), or an aliphatic polyester are preferred. Thermoplastic polyester elastomers can be used alone or in combination.

[0055] In a thermoplastic elastomer, the mass ratio of the hard segment (or hard component) to the soft segment (or soft component) is usually about 10 / 90 to 90 / 10, preferably 20 / 80 to 80 / 20, and more preferably 30 / 70 to 70 / 30 (for example, 40 / 60 to 60 / 40).

[0056] For applications requiring flexibility, the thermoplastic polyester elastomer preferably has a flexural modulus of 1000 MPa or less, preferably in the range of about 50 to 400 MPa (particularly 100 to 300 MPa). In such applications, if the flexural modulus is too low, problems arise in handling during processing, while if it is too high, sufficient flexibility may not be obtained.

[0057] In the PBT resin composition of this embodiment, the thermoplastic polyester elastomer is contained in an amount of 10 to 25 parts by mass per 100 parts by mass of PBT resin, but if it is less than 10 parts by mass, the effect of improving toughness is low, and if it exceeds 25 parts by mass, the rigidity decreases and the composition becomes more susceptible to deformation. The thermoplastic polyester elastomer is contained in an amount of preferably 13 to 20 parts by mass, more preferably 15 to 18 parts by mass.

[0058] [(F) Polycarbodiimide compound] In this embodiment, a polycarbodiimide compound is used to improve hydrolysis resistance. The polycarbodiimide compound is a compound having at least two carbodiimide groups represented by (—N═C═N—) in the molecule. It can be synthesized by a commonly known method, for example, by subjecting various polyisocyanates (diisocyanates) to a decarboxylation condensation reaction at a temperature of about 70°C or higher using an organophosphorus compound or an organometallic compound as a catalyst, either without a solvent or in an inert solvent. Known methods for producing polycarbodiimide compounds include those described in U.S. Pat. No. 2,941,956, Japanese Patent Publication No. 47-33279, J. Org. Chem. 28, 2069-2075 (1963), and Chemical Review 1981, Vol. 81, No. 4, pp. 619-621.

[0059] Examples of organic diisocyanates that are synthesis raw materials in the production of polycarbodiimide compounds include aliphatic diisocyanates, alicyclic diisocyanates, aromatic diisocyanates, and mixtures thereof. Specific examples include hexamethylene diisocyanate, cyclohexane-1,4-diisocyanate, isophorone diisocyanate, dicyclohexylmethane-4,4′-diisocyanate, and methylcyclohexane diisocyanate.

[0060] In the case of polycarbodiimide compounds, the polymerization reaction can be stopped midway by cooling or the like to control the degree of polymerization to an appropriate level. In this case, the terminal isocyanate groups are formed. Furthermore, to control the degree of polymerization to an appropriate level, a method can be used in which all or part of the remaining terminal isocyanate groups are blocked using a compound that reacts with the terminal isocyanate of an aliphatic polycarbodiimide compound, such as a monoisocyanate. Controlling the degree of polymerization can improve compatibility with polymers and storage stability, which is preferable in terms of improving quality.

[0061] Examples of monoisocyanates that can be used to block the ends of such polycarbodiimide compounds and control the degree of polymerization include phenyl isocyanate, tolyl isocyanate, dimethylphenyl isocyanate, cyclohexyl isocyanate, and butyl isocyanate.

[0062] A preferred polycarbodiimide compound used in this embodiment has a number-average molecular weight of 1000 to 30000, preferably 2000 to 20000, and more preferably 3000 to 15000. If the number-average molecular weight is less than 1000, there is a risk that the heat resistance will be poor, and if it exceeds 30000, there is a risk that the effect of improving hydrolysis resistance will not be sufficiently obtained due to poor dispersion in the resin and reduced reactivity.

[0063] In addition, in view of the requirement for high hydrolysis resistance and heat resistance, aromatic polycarbodiimides containing aromatic components in the molecular chain skeleton are particularly preferably used, and examples thereof include aromatic dicarbodiimide compounds such as p-phenylene-bis-o-triylcarbodiimide, p-phenylene-bis-p-chlorophenylcarbodiimide, and ethylene-bis-diphenylcarbodiimide; poly(4,'-methylenebiscyclohexylcarbodiimide); poly(4,4'-diphenylmethanecarbodiimide); and poly(3,3'-dimethylaminomethyl). and aromatic polycarbodiimide compounds such as poly(4,4'-diphenylmethanecarbodiimide), poly(naphthylenecarbodiimide), poly(p-phenylenecarbodiimide), poly(m-phenylenecarbodiimide), poly(tolylcarbodiimide), poly(diisopropylphenylenecarbodiimide), poly(methyl-diisopropylphenylenecarbodiimide), poly(triethylphenylenecarbodiimide), and poly(triisopropylphenylenecarbodiimide).

[0064] Generally, when a thermoplastic aromatic polyester resin composition contains a carbodiimide compound, gas or odor may be generated during melt-kneading or molding. However, when the compounding amount is 0.5% by mass or more and 3.0% by mass or less, both superior hydrolysis resistance and suppression of isocyanate gas generation derived from the carbodiimide compound can be achieved, and superior hydrolysis resistance can be achieved while suppressing deterioration of the working environment. In the PBT resin composition of this embodiment, the polycarbodiimide compound is contained in an amount of 1 to 3 parts by mass, preferably 1.5 to 2.0 parts by mass, per 100 parts by mass of PBT resin.

[0065] [(G) Fluorine resin] In this embodiment, a fluororesin is an optional component used as an anti-dripping agent. Suitable fluororesins include homopolymers or copolymers of fluorine-containing monomers such as tetrafluoroethylene, chlorotrifluoroethylene, vinylidene fluoride, hexafluoropropylene, and perfluoroalkyl vinyl ether, as well as copolymers of the fluorine-containing monomers with copolymerizable monomers such as ethylene, propylene, and (meth)acrylate. These fluororesins can be used alone or in combination.

[0066] Examples of such fluororesins include homopolymers such as polytetrafluoroethylene, polychlorotrifluoroethylene, and polyvinylidene fluoride; Examples of copolymers include ethylene-hexafluoropropylene copolymer, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer, ethylene-tetrafluoroethylene copolymer, and ethylene-chlorotrifluoroethylene copolymer.

[0067] In the PBT resin composition of this embodiment, the amount of the fluororesin added is 0 to 3 parts by mass, preferably 0 to 2 parts by mass, and more preferably 0.8 to 1.5 parts by mass, relative to 100 parts by mass of the PBT resin.

[0068] [(H) Styrene-based resin] In this embodiment, the styrene resin is used for the purpose of improving warpage reduction. The styrene resin is a polymer or copolymer containing repeating units derived from an aromatic vinyl compound. Examples of the aromatic vinyl compound include styrene, α-alkyl-substituted styrene, and nuclear-alkyl-substituted styrene. In addition, examples of the monomer other than the aromatic vinyl compound in the styrene-based resin include acrylonitrile and methyl (meth)acrylate. The styrene-based resin may be modified with rubber, and examples of rubber include polybutadiene, styrene-butadiene copolymer, polyisoprene, and ethylene-propylene copolymer. In terms of rigidity and heat resistance, the rubber content of the rubber-modified styrene-based resin is preferably 30% or less, more preferably 20% or less, and particularly preferably 10% or less. The styrene-based resin may also be modified with epoxy. Specific examples of the above-mentioned styrene-based resin include polystyrene, rubber-modified polystyrene, ABS resin, MBS resin, AS resin, and ESBS resin, with AS resin being preferred from the viewpoint of heat resistance. Methyl (meth)acrylate refers to methyl acrylate or methyl methacrylate.

[0069] In the PBT resin composition of this embodiment, the styrene-based resin is contained in an amount of 40 to 80 parts by mass, preferably 45 to 60 parts by mass, and more preferably 48 to 58 parts by mass, per 100 parts by mass of the PBT resin. If the styrene-based resin is less than 40 parts by mass, the resulting molded article will not exhibit sufficient dimensional stability and low warpage. On the other hand, if the styrene-based resin is contained in an amount exceeding 80 parts by mass, molding problems such as reduced heat resistance, reduced flame retardancy, increased molding cycle time, poor mold releasability, and even reduced melt thermal stability will occur, which is undesirable.

[0070] <Resin molded products> The resin molded article of this embodiment is obtained by molding the above-described PBT resin composition. Therefore, like the PBT resin composition of this embodiment, the resin molded article of this embodiment has excellent flame retardancy, tracking resistance, hydrolysis resistance, and low warpage. Furthermore, the PBT resin composition of this embodiment has a low melt viscosity, making it easy to mold.

[0071] The method for producing a resin molded article using the PBT resin composition of the present embodiment is not particularly limited, and any known method can be used. For example, the PBT resin composition of the present embodiment can be fed into an extruder, melt-kneaded, and pelletized, and the pellets can be fed into an injection molding machine equipped with a predetermined mold and injection-molded to produce a resin molded article.

[0072] The resin molded article of this embodiment can be suitably used as a resin composition for molded articles that are exposed to high-temperature, high-humidity environments for long periods of time, such as in automobiles, trains, and the aviation industry. Molded articles made from this resin composition can be prevented from deteriorating due to hydrolysis even when used for long periods of time in sufficiently high-temperature, high-humidity environments, and further have excellent tracking resistance, flame retardancy, and low warpage, so they can be used for housings and connectors for parts that use high voltage, such as electric vehicle parts. [Example]

[0073] The present embodiment will be described in more detail below with reference to examples, but the present embodiment is not limited to the following examples.

[0074] [Examples 1 to 10, Comparative Examples 1 to 14] In each example and comparative example, components (A) to (H) were melt-mixed and extruded in the ratios (parts by mass) shown in Tables 1 to 3 using a 30 mm diameter twin-screw extruder (TEX30α, manufactured by The Japan Steel Works, Ltd.) at a cylinder temperature of 260°C at the raw material feed section and die tip, and 220 to 260°C between them, at a discharge rate of 15 kg / h and a screw rotation speed of 130 rpm, to obtain pellets of a PBT resin composition. Details of each component shown in Tables 1 to 3 are provided below. The particle size (D95) of components (C) and (D) was measured using a laser diffraction / scattering particle size distribution analyzer ("LA920" manufactured by Horiba, Ltd.) and water as a dispersion medium.

[0075] (A)PBT resin A1: Polybutylene terephthalate (intrinsic viscosity: 0.80 (dL / g)) manufactured by Polyplastics Co., Ltd. A2: Polybutylene terephthalate (intrinsic viscosity: 0.79 (dL / g)) manufactured by Polyplastics Co., Ltd. A3: Polybutylene terephthalate (intrinsic viscosity: 0.73 (dL / g)) manufactured by Polyplastics Co., Ltd. A4: Polybutylene terephthalate (intrinsic viscosity: 0.69 (dL / g)) manufactured by Polyplastics Co., Ltd.

[0076] (B) Fibrous inorganic compounds B1: Glass fiber ECS 03-T-187, manufactured by Nippon Electric Glass Co., Ltd.

[0077] (C) Phosphinates, etc. C1: Clariant Japan Co., Ltd., phosphorus-based flame retardant aluminum tri(diethylphosphinate) EXOLIT 1240, cumulative particle size (D95): 75 μm C2: Clariant Japan Co., Ltd., phosphorus-based flame retardant aluminum tri(diethylphosphinate) EXOLIT OP940, cumulative particle size (D95): 20 μm C3: Clariant Japan Co., Ltd., phosphorus-based flame retardant aluminum tri(diethylphosphinate) EXOLIT OP935, cumulative particle size (D95): 10 μm C4: Clariant Japan Co., Ltd., phosphorus-based flame retardant aluminum tri(diethylphosphinate) EXOLIT OP945, cumulative particle size (D95): 5 μm

[0078] (D) Salt of triazine and cyanuric acid D1: Melamine cyanurate MELAPUR MC50 manufactured by BASF Japan Ltd., cumulative particle size (D95): 50 μm D2: BASF Japan Ltd., melamine cyanurate, cumulative particle size (D95): 3 μm D3: BASF Japan Ltd., melamine cyanurate, cumulative particle size (D95): 60 μm

[0079] (E) Thermoplastic polyester elastomer, comparative polymer E1: Toyobo Co., Ltd., polyester elastomer Pelprene GP400, density: 1.14 g / cm 3 E2: Mitsui Chemicals, Inc., α-olefin copolymer Toughmer MP0610, density: 0.87 g / cm 3 E3: UNIC Corporation, ethylene ethyl acrylate copolymer NUC-6570, density: 0.93 g / cm 3 E4: Ethylene-glycidyl methacrylate copolymer Bondfast E, manufactured by Sumitomo Chemical Co., Ltd., density: 0.94 g / cm 3

[0080] (F) Polycarbodiimide compound F1: LANXESS, carbodiimide STABAXOL P200

[0081] (G) Fluorine resin G1: Polyflon MPA FA-500H, manufactured by Daikin Industries, Ltd.

[0082] (H) Styrene-based resin, comparative resin H1: Techno UMG Co., Ltd., acrylonitrile-styrene resin UMG AXS Resin AP-20 H2: Teijin Ltd., polycarbonate resin Panlite L1225L H3: Bell Polyester Products, copolymer PET resin, Bellpet IFG8L

[0083] (Other ingredients) Antioxidant: IRGANOX 245, manufactured by BASF Japan Ltd. Secondary antioxidant: ADEKA Corporation, Adekastab PEP-36 Lubricant: Riken Vitamin Co., Ltd., B-74

[0084] [Table 1]

[0085] [Table 2]

[0086] [Table 3]

[0087] [evaluation] The pellets obtained in each of the examples and comparative examples were evaluated as follows.

[0088] (1) Flammability Flame retardancy (V-0) was evaluated using five test pieces (thickness: 1.6 mm) according to the Underwriters Laboratories Subject 94 (UL94) method. Test pieces that met the V-0 standard were rated V-0, and those that did not were rated as failing. The evaluation results are shown in Tables 4 to 6.

[0089] (2) Tracking resistance In accordance with IEC 60112, 3rd Edition, the applied voltage (V: volts) at which tracking occurred on the test piece was measured using a 0.1 mass % ammonium chloride aqueous solution and a platinum electrode. The measurement results are shown in Tables 4 to 6. The maximum applied voltage was 600 V, and an applied voltage of 600 V can be said to have good tracking resistance.

[0090] (3) Tensile strength The tensile strength of the obtained pellets was measured in accordance with ISO527-1 and 2. The measurement results are shown in Tables 4 to 6. The mechanical strength can be said to be good when the tensile strength is 50 MPa or more when not reinforced with (B) fibrous inorganic compound, and 90 MPa or more when reinforced with (B) fibrous inorganic compound.

[0091] (4) Hydrolysis resistance After 50 hours of exposure in a pressure cooker tester at 121°C and 100% RH, the tensile strength (MPa) was measured in accordance with ISO 527-1, 2, and the strength retention rate was calculated from the tensile strength before treatment. The calculation results are shown in Tables 4 to 6. A strength retention rate of 70% or more can be said to have good hydrolysis resistance.

[0092] (5) Melt viscosity The obtained pellets were dried at 140°C for 3 hours, and then subjected to a shear rate of 1000 sec using a Capillograph 1B (manufactured by Toyo Seiki Seisakusho Co., Ltd.) in accordance with ISO 11443. -1The measurement results are shown in Tables 4 to 6. If the melt viscosity is 0.45 kPa·s or less, the melt viscosity is low and the fluidity when melted is good.

[0093] (6) Warpage evaluation of molded products The resulting pellets were dried at 140°C for 3 hours, and then molded into flat plate-shaped pieces measuring 80mm x 80mm x 1mm under the molding conditions described below. After conditioning for at least 24 hours in an environment of 23°C and 50% humidity, the maximum amount of warpage of the flat plate was measured using a height gauge. A maximum warpage of less than 3mm was evaluated as low warpage "A," and a maximum warpage of 3mm or more was evaluated as low warpage "B." The evaluation results are shown in Tables 4 to 6. Injection molding machine: FANUC ROBOSHOT α-100iA Cylinder temperature: 260℃ Injection speed: 1m / min Holding pressure: 70MPa Mold temperature: 65℃

[0094] [Table 4]

[0095] [Table 5]

[0096] [Table 6]

[0097] As can be seen from Tables 4 to 6, all of the evaluations were good in Examples 1 to 10. That is, it was shown that the PBT resin compositions of Examples 1 to 10 were excellent in flame retardancy, tracking resistance, hydrolysis resistance, and low warpage, and had low melt viscosity. On the other hand, in Comparative Examples 1 to 14, it was not possible to simultaneously obtain good results in all the evaluations. From the above, it can be seen that unless the components (A) to (H) are blended in the specified amounts, it is not possible to obtain good results in all of the flame retardancy, tracking resistance, hydrolysis resistance, fluidity when melted (low melt viscosity), and low warpage.

Claims

1. A flame-retardant polybutylene terephthalate resin composition comprising, relative to 100 parts by mass of (A) polybutylene terephthalate resin, 10 to 120 parts by mass of (B) a fibrous inorganic compound, 30 to 80 parts by mass of (C) at least one selected from the group consisting of a phosphinate salt represented by the following general formula (1), a polymer thereof, and a diphosphinate salt represented by the following general formula (2), and a polymer thereof, the diphosphinate salt having a cumulative particle size (D95) measured in accordance with JIS 8825 of 10 to 500 μm, (D) 6 to 25 parts by mass of a salt of a triazine compound with cyanuric acid or isocyanuric acid, (E) 10 to 20 parts by mass of a thermoplastic polyester elastomer, (F) 1 to 3 parts by mass of a polycarbodiimide compound, (G) 0 to 3 parts by mass of a fluororesin, and (H) 40 to 80 parts by mass of a styrene-based resin. 【Chemistry 1】 [In general formula (1) and general formula (2), R １ , R ２ , R ３ and R ４ each independently represents an alkyl group, a cycloalkyl group, an aryl group, or an aralkyl group; R ５ represents an alkylene group, an alicyclic divalent group, or an aromatic divalent group. １ and R ２ may be bonded to each other to form a ring together with the adjacent phosphorus atom. ｍ＋ represents a metal with a valence of m, where m is an integer of 2 to 4. ｎ＋ represents a metal having a valence of n, where n is an integer of 2 to 4.

2. 2. The flame-retardant polybutylene terephthalate resin composition according to claim 1, wherein the polycarbodiimide compound (F) is an aromatic polycarbodiimide.

3. A resin molded article obtained by molding the flame-retardant polybutylene terephthalate resin composition according to claim 1 or 2.

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