JP5172761B2 - Polybutylene terephthalate resin composition and fuel tube - Google Patents

Description

  The present invention relates to a polybutylene terephthalate resin composition having flexibility, ductility, excellent toughness including hydrolysis at low temperatures, hydrolysis resistance, organic chemical resistance, ozone resistance, and a molded article using the same. (For example, a fuel tube having a multilayer structure).

  Polybutylene terephthalate resin is excellent in mechanical properties, electrical properties, heat resistance, weather resistance, water resistance, chemical resistance and solvent resistance. As the field of use expands, the required performance has been diversified. For example, it is desired to further improve flexibility, low temperature impact resistance, hydrolysis resistance and the like while maintaining the heat resistance and organic chemical resistance as engineering plastics.

  Japanese Patent Application Laid-Open No. 56-161442 (Patent Document 1) discloses a thermoplastic resin such as polybutylene terephthalate resin as a polyester resin composition having excellent mechanical properties and chemical resistance (alcohol-resistant gasoline resistance). A resin composition containing 0.01 to 5 parts by weight of a carbodiimide compound, 0.01 to 50 parts by weight of an epoxy compound and 5 to 100 parts by weight of a reinforcing filler with respect to 100 parts by weight of polyester is disclosed. In JP-A-1-174557 (Patent Document 2), in order to improve hydrolysis resistance, molding fluidity, etc., 0.005 to 10 parts by weight of an epoxy compound and a carbodiimide compound with respect to 100 parts by weight of an aromatic polyester. An aromatic polyester resin composition containing 0.005 to 5 parts by weight is disclosed.

  JP-A-60-219255 (Patent Document 3) discloses a thermoplastic polyester resin, a butadiene-based graft copolymer, a halogen-free epoxy compound and a carbodiimide compound in order to improve impact resistance and hydrolysis resistance. A polyester resin composition containing is disclosed.

  However, the resin compositions described in these documents cannot satisfy all the characteristics of toughness (impact resistance), hydrolysis resistance, and chemical resistance. For example, in the invention according to Patent Document 3, although the hydrolysis resistance of polybutylene terephthalate resin can be improved and the impact strength can be improved, the butadiene-based graft copolymer is inferior in chemical resistance. It is difficult to apply to parts that come into contact with liquid or vapor.

  However, in the field where materials belonging to the category of rubber and elastomer are suitably used from the viewpoint of flexibility, there is an increasing need to use them outdoors or at high temperatures or in contact with organic solvents. Therefore, there is a need for the development of materials that have flexibility and ductility, and that can satisfy the properties of toughness, hydrolysis resistance, organic chemical resistance, ozone resistance, etc. in a well-balanced manner even at low temperatures. It is necessary.

  JP 2006-272630 A (Patent Document 4) relates to a fuel hose excellent in low temperature characteristics, flexibility and hydrolysis resistance, and has a tubular inner layer and a fuel low-permeability layer formed on the outer peripheral surface of the inner layer. And an outer layer formed on the outer peripheral surface of the low-permeability layer, the inner layer is made of a polyester-based resin softened by alloying or copolymerization of an elastomer component, and the low-permeability layer is made of polybutylene naphthalate and poly A polybutylene terephthalate-based thermoplastic elastomer composed of at least one polyester resin of butylene terephthalate, and the outer layer having at least one of polytetramethylene glycol and dimer acid as a copolymerization component, and a styrene-isobutylene block copolymer A three-layer fuel hose composed of a blend polymer is disclosed. That. Japanese Patent Application Laid-Open No. 2007-261078 (Patent Document 5) relates to a fuel hose excellent in low temperature property, flexibility, hydrolysis resistance, weather resistance and ozone resistance, and has the same tubular inner layer and low fuel permeation as described above. The outer layer formed on the outer peripheral surface of the low-permeability layer was selected from the group consisting of polybutylene terephthalate, polymer fine particles having a core-shell structure, ethylene acrylic rubber (AEM), and a styrene-isobutylene copolymer. A three-layer fuel hose made of a blend polymer blended with at least one is disclosed. However, the compositions described in these documents (particularly the resin composition constituting the outer layer of the fuel hose) have hydrolysis resistance and weather resistance, adhesion to other layers during multilayer tube extrusion, There is a need for further improvements in solubility.

JP 56-161452 (Claims) JP-A-1-174557 (Claims) JP-A-60-219255 (Claims) JP 2006-272630 A (Claims) JP 2007-261078 A (Claims)

  Accordingly, an object of the present invention is to provide a polybutylene terephthalate resin composition having flexibility, ductility and impact resistance, and having greatly improved hydrolysis resistance, weather resistance, and compatibility, and a molded article using the composition. (Fuel tube etc.) is to be provided.

  Another object of the present invention is to provide a polybutylene terephthalate resin composition excellent in toughness, hydrolysis resistance, organic chemical resistance, ozone resistance and the like including at low temperatures, and a molded article (fuel tube) using this composition. Etc.).

  Still another object of the present invention is to provide a polybutylene terephthalate resin composition useful for forming an outer layer of a fuel tube, particularly a multilayered fuel tube, and a molded article (such as a fuel tube) using the composition. There is.

  As a result of intensive studies to achieve the above-mentioned problems, the present inventors combined an elastomer component having a polybutylene terephthalate unit highly compatible with a polybutylene terephthalate homopolymer and / or a polybutylene terephthalate copolymer. The combination of an acrylic core-shell polymer that does not contain a butadiene component, an aromatic carbodiimide compound, and an antioxidant has found that it has flexibility and ductility, and can greatly improve hydrolysis resistance, weather resistance, and compatibility. The present invention has been completed.

  That is, the polybutylene terephthalate resin composition of the present invention comprises (A) a polybutylene terephthalate homopolymer and / or a polybutylene terephthalate copolymer and a polyester elastomer, and (B) a core-shell type. An elastomer, (C) an aromatic polycarbodiimide compound, and (D) an antioxidant. In this composition, (A) the polybutylene terephthalate resin comprises (A1) a polybutylene terephthalate homopolymer and / or a polybutylene terephthalate copolymer and (A2) a polyester elastomer. The former / the latter = 30/70 to 70. / 30 weight ratio may be included. The polyester elastomer may be a polybutylene terephthalate thermoplastic elastomer, and may contain 20 to 90% by weight of polybutylene terephthalate as a hard segment. The (B) core-shell type elastomer can be composed of an acrylic core-shell type elastomer that does not contain a diene component. (D) The antioxidant may be a hindered phenol antioxidant or a combination of a hindered phenol antioxidant and a thioether antioxidant. The proportion of each component of the composition is as follows: (A) 10 to 80 parts by weight of the core-shell type elastomer and (C) 0.01 to 5 parts of the aromatic polycarbodiimide compound with respect to 100 parts by weight of the polybutylene terephthalate resin. It may be 0.01 to 5 parts by weight and (D) an antioxidant. More specifically, the resin composition comprises (A) (A1) a polybutylene terephthalate homopolymer and / or polybutylene terephthalate copolymer, and (A2) a hard segment composed of polybutylene terephthalate and an aliphatic group. Polyester composed of a polyester elastomer (such as a polybutylene terephthalate thermoplastic elastomer) containing at least one soft segment selected from polyester and polyalkylene glycol in a weight ratio of the former / the latter = 20/80 to 90/10 (B) 10-80 parts by weight of a core-shell type elastomer not containing a butadiene component, (C) 0.01-5 parts by weight of an aromatic polycarbodiimide compound, and (D) an antioxidant with respect to 100 parts by weight of a butylene terephthalate resin. May contain 0.01-5 parts by weight Yes. The resin composition may have a flexural modulus of 600 MPa or less as defined in ISO178. As is clear from the above, it is preferable that the resin composition does not substantially contain a diene component (for example, a polydiene component such as polybutadiene).

  Since the resin composition of the present invention has flexibility and ductility and is excellent in properties such as hydrolysis resistance, weather resistance, and compatibility, it can be suitably applied to a fuel tube (or fuel hose). Therefore, the resin composition may be a resin composition for a fuel tube. This fuel tube (or fuel hose) is a single-layer or multi-layer fuel tube extruded into a hollow cylinder, and at least one layer is composed of the polybutylene terephthalate resin composition. The fuel tube may be a multi-layered fuel tube composed of an inner layer, a barrier layer, and an outermost layer. In such a fuel tube, at least one layer may be composed of the polybutylene terephthalate resin composition. For example, the outermost layer of the fuel tube may be composed of the polybutylene terephthalate resin composition.

  In this specification, “(B) core-shell type elastomer” and “polyester elastomer” are used separately, and “(B) core-shell type elastomer” does not include “polyester elastomer”.

  The resin composition of the present invention comprises (A) (A1) a polybutylene terephthalate homopolymer and / or polybutylene terephthalate copolymer, and (A2) a polyester elastomer, and (B) a core shell. Type elastomer, (C) aromatic polycarbodiimide compound, and (D) antioxidant, so that it has flexibility, ductility and impact resistance, and can greatly improve hydrolysis resistance, weather resistance, and compatibility. In addition, toughness including hydrolysis at low temperatures, hydrolysis resistance, organic chemical resistance, and ozone resistance can be greatly improved. Therefore, it can be used stably over a long period of time even in an environment where it comes into contact with an organic solvent such as fuel or its vapor, and is useful as a composition for forming a fuel tube.

  (A) Polybutylene terephthalate resin (PBT resin) is (A1) polybutylene terephthalate homopolymer (PBT homopolymer) and / or polybutylene terephthalate copolymer (PBT copolymer) and a polyester elastomer (for example, And an elastomer such as a polybutylene terephthalate thermoplastic elastomer (PBT elastomer). (A1) The PBT homopolymer or PBT copolymer contains at least a dicarboxylic acid component containing at least terephthalic acid or an ester-forming derivative thereof (lower alcohol ester such as methyl ester, acid chloride, acid anhydride, etc.) and at least 4 carbon atoms. Obtained by polycondensation with a glycol component containing an alkylene glycol (1,4-butanediol) or an ester-forming derivative thereof.

The polybutylene terephthalate copolymer is obtained by converting a part of at least one of the terephthalic acid component and the 1,4-butanediol component (for example, about 1 to 30 mol%, particularly about 3 to 25 mol%) into a copolymerizable monomer. Dimers, for example, dicarboxylic acid components (asymmetric benzene dicarboxylic acids such as phthalic acid and isophthalic acid, aromatic polyvalent carboxylic acids such as naphthalenedicarboxylic acid and pyromellitic acid, aliphatic C _4-12 dicarboxylic acids such as adipic acid, cycloaliphatic such as cyclic _{C 8-12} dicarboxylic acids), the diol component (ethylene glycol, propylene glycol, 1,4-butenediol, neopentyl glycol, 1,5-pentanediol, such as 1,6-hexanediol _{C 2- 10} alkylene glycol or alkene glycol, diethylene glycol and the like of the (poly) Oki Alkylene glycol, 1,4-cyclohexanediol, _{C 5-12} cycloalkane diols such as 1,4-cyclohexanedimethanol, bis (4-hydroxyphenyl) diphenyl, bis _{(hydroxyaryl) C 1-6} alkane [bis (4- Hydroxyphenyl) methane, bis (4-hydroxyphenyl) propane, etc.], bis (hydroxyaryl) C _4-10 cycloalkane, bis (hydroxyaryl) ether, bis (hydroxyaryl) sulfone, bis (hydroxyaryl) sulfide, bis Examples thereof include polymers substituted with bisphenols such as (hydroxyaryl) ketones or alkylene oxide adducts thereof. If necessary, an oxycarboxylic acid (such as oxybenzoic acid or oxynaphthoic acid) or a lactone (such as a C _3-12 lactone such as ε-caprolactone) may be copolymerized. Furthermore, if necessary, a polyfunctional compound, for example, a polyvalent carboxylic acid such as trimellitic acid, or a polyol such as glycerin, trimethylolpropane, trimethylolethane, or pentaerythritol may be used in combination. The homopolymers and copolymers may be used alone or in combination. A preferred resin is a highly crystalline resin, for example, a polybutylene terephthalate alone or a copolymer having a copolymerizable monomer content of about 0 to 10 mol% based on the whole monomer, particularly a polybutylene terephthalate alone It is a polymer (homopolybutylene terephthalate resin).

  (A1) The PBT polymer uses o-chlorophenol as a solvent and has an intrinsic viscosity measured at 35 ° C. of 0.6 to 1.4 dl / g, preferably about 0.7 to 1.2 dl / g. Is advantageous. If the intrinsic viscosity is less than 0.6 dl / g, the amount of gas generated from polybutylene terephthalate resin such as tetrahydrofuran cannot be sufficiently reduced, and if it exceeds 1.4 dl / g, the molding fluidity is lowered. From the viewpoint of improving the hydrolysis resistance, it is preferable to select a resin having a high intrinsic viscosity within the allowable fluidity range.

  (A2) The type of the polyester elastomer is not particularly limited, but usually includes polybutylene terephthalate as a hard segment and a soft segment. That is, a PBT elastomer is preferable. By adding an elastomer component having a polybutylene terephthalate unit, flexibility, ductility and low-temperature impact resistance can be imparted, and compatibility with the PBT polymer can be improved.

The hard segment only needs to have a polybutylene terephthalate skeleton (PBT skeleton). As the dicarboxylic acid component forming the hard segment, terephthalic acid and its ester derivative (terephthalic acid component) are used to constitute the hard segment. 1,4-butanediol is used as the diol component. A part of the terephthalic acid component of the hard segment may be substituted with a copolymerizable monomer (such as isophthalic acid or naphthalenedicarboxylic acid) similar to the polybutylene terephthalate copolymer. Further, a part of 1,4-butanediol constituting the hard segment is a copolymerizable monomer (C _2-10 alkylene glycol, (poly) oxyalkylene glycol, C) similar to the polybutylene terephthalate copolymer. _5-12 cycloalkanediol, bisphenols or their alkylene oxide adducts, etc.). The hard segment is usually composed of a crystalline PBT skeleton and is usually a short-chain ester skeleton.

  In the polyester elastomer, as the soft segment, at least one soft segment selected from an aliphatic polyester and a polyether can be used, and a polyester containing a polyether unit may be used.

Polyester type soft segments include dicarboxylic acids (aliphatic C _4-12 dicarboxylic acids such as adipic acid) and diols (C _2-10 alkylene glycol such as 1,4-butanediol, polyethylene such as diethylene glycol) A polycondensate with an aliphatic diol such as oxyalkylene glycol), a polycondensate of oxycarboxylic acid or a ring-opening polymer of a lactone (C _3-12 lactone such as ε-caprolactone). The polyester type soft segment is usually an amorphous polyester. Specific examples of the polyester as the soft segment include polyesters of C _2-6 alkylene glycol such as caprolactone polymer, polyethylene adipate, polybutylene adipate and C _6-12 alkanedicarboxylic acid. The number average molecular weight of the polyester can be selected from the range of about 200 to 15000, and may usually be about 200 to 10000 (for example, 300 to 8000).

As the polyether type soft segment, polyalkylene glycol (poly _C2-4 alkylene glycol such as polyoxyethylene glycol, polyoxypropylene glycol and polyoxytetramethylene glycol), particularly polyoxytetramethylene glycol is preferable. The number average molecular weight of the polyether can be selected from the range of about 200 to 10000, and may usually be about 200 to 6000 (for example, 300 to 5000).

  The soft segment is a polyester having a polyether unit, for example, the polyether such as a copolymer of the aliphatic polyester and the polyether (polyether-polyester), polyoxyalkylene glycol (polyoxytetramethylene glycol, etc.) And a polyester of an aliphatic dicarboxylic acid and the like.

  (A2) In the polyester elastomer, the weight ratio of the hard segment and the soft segment is the former / the latter = 20/80 to 90/10, preferably 30/70 to 85/15, more preferably 40/60 to 80/20. (For example, about 45/55 to 70/30) may be sufficient.

  Further, in (A) PBT resin, the weight ratio of (A1) PBT homopolymer and / or PBT copolymer and (A2) polyester elastomer is the content of each component type and PBT skeleton (or unit). The former / the latter can be selected from the range of about 20/80 to 80/20 (for example, 25/75 to 75/25), and usually 30/70 to 70/30 (for example, 33/67 to 67/33), preferably about 40/60 to 60/40. If the content of the PBT elastomer component is excessively large, the characteristics of the PBT resin composition cannot be sufficiently obtained, and the weather resistance, chemical resistance, heat resistance and the like are deteriorated. If the content is excessively small, flexibility and ductility are obtained. And low temperature impact resistance is also reduced. Note that (A) PBT resin alone is often difficult to achieve a balance with other properties such as weather resistance, and even if the content of the polyester elastomer component is considered to be small, It is difficult to achieve the elastic modulus.

  (B) A core-shell type elastomer may comprise either a core layer or a shell layer with a rubber component (soft component) and the other component with a hard component. The core-shell type elastomer usually has a multilayer structure including a core layer made of a rubber component and a shell layer made of a hard resin (such as a glassy resin) that covers or encloses the core layer. There are many cases.

  Examples of rubber components include polymers of unsaturated bond-containing monomers [acrylic rubber, diene rubber (diene elastomer), olefin rubber (ethylene-propylene rubber, etc.), fluorine rubber (vinylidene fluoride-perfluoro). Propene copolymer, etc.)], silicon rubber (silicon elastomer), urethane rubber and the like. Preferred elastomers do not contain a diene component (eg, a butadiene component). Therefore, the rubber component is an elastomer that does not contain a diene component (butadiene component or diene rubber), preferably an acrylic rubber, and in some cases, a copolymer obtained by copolymerizing / grafting silicon rubber may be used. it can. A diene rubber (diene elastomer) may be used as long as it is a hydrogenated rubber, for example, a hydrogenated nitrile rubber. A preferred core-shell type elastomer is an acrylic core-shell type elastomer.

The acrylic rubber of the core layer can be obtained by polymerization of an acrylate ester and a small amount of a crosslinkable monomer. Examples of the acrylic ester include C _1-12 alkyl acrylates such as methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, isobutyl acrylate, hexyl acrylate, 2-ethylhexyl acrylate, and lauryl acrylate. Among these acrylic acid esters, C _2-8 alkyl acrylates (particularly alkyl acrylates containing at least butyl acrylate) such as ethyl acrylate, butyl acrylate, and 2-ethylhexyl acrylate are preferable. These acrylic acid esters may be used alone or in combination of two or more.

  Crosslinkable monomers include alkylene poly (meth) acrylates such as butylene di (meth) acrylate; ethylene glycol di (meth) acrylate, butylene glycol di (meth) acrylate, poly (or oligo) ethylene glycol di (meth) acrylate (diethylene glycol) Di (meth) acrylate, triethylene glycol di (meth) acrylate, etc.), glycerin tri (meth) acrylate, trimethylolethane tri (meth) acrylate, trimethylolpropane di (meth) acrylate, trimethylolpropane tri (meth) acrylate , Pentaerythritol di (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol tetra (meth) acrylate, dipentaeryth Polyfunctional vinyl compounds having vinyl groups such as vinyl (meth) acrylate and divinylbenzene, allyl (meth) acrylates, such as polyfunctional (meth) acrylates having a plurality of (meth) acryloyl groups such as lithol hexa (meth) acrylate And polyfunctional allyl compounds having a plurality of allyl groups such as diallyl malate, diallyl fumarate, diallyl itaconate, monoallyl malate, monoallyl fumarate, triallyl cyanurate, and the like. As the crosslinkable monomer, for example, a hydrolytic condensable compound [for example, a (meth) acryloyloxyalkyltrialkoxysilane such as a silane coupling agent having a (meth) acryloyl group (3-trimethoxysilylpropyl (meth) acrylate, etc. ) Etc.] can also be used. Examples of typical crosslinkable monomers include butylene diacrylate. These crosslinkable monomers can be used alone or in combination of two or more.

  The amount of the crosslinkable monomer used is, for example, about 0.1 to 10 parts by weight (for example, 0.1 to 5 parts by weight, preferably 0.2 to 3 parts by weight) with respect to 100 parts by weight of the whole monomer. There may be.

  Silicon rubber is, for example, dimethylpolysiloxane chain, methylvinylpolysiloxane chain, methylphenylpolysiloxane chain, copolymer chain of these siloxane units [dimethylsiloxane-methylvinylsiloxane copolymer chain, dimethylsiloxane-methylphenyl. Siloxane copolymer chain, dimethylsiloxane-methyl (3,3,3-trifluoropropyl) siloxane copolymer chain, dimethylsiloxane-methylvinylsiloxane-methylphenylsiloxane copolymer chain, etc.]. Both ends of the silicone rubber may be, for example, a trimethylsilyl group. Silicon rubber is obtained by polymerization of an organosiloxane monomer. Examples of the organosiloxane monomers include hexamethyltricyclosiloxane, octamethylcyclosiloxane, decamethylpentacyclosiloxane, dodecamethylhexacyclosiloxane, trimethyltriphenylsiloxane, tetramethylphenylcyclotetrasiloxane, and octaphenylcyclotetra. Examples thereof include siloxane.

  The glass transition temperature of the rubber component is, for example, less than 0 ° C. (for example, −10 ° C. or less), preferably −20 ° C. or less (for example, about −180 to −25 ° C.), more preferably −30 ° C. or less (for example, -150 to -40 ° C).

The shell layer can usually be composed of a hard resin component (or glassy resin component), and can usually be composed of a vinyl polymer (such as a vinyl copolymer). Vinyl polymers (vinyl copolymers) are aromatic vinyl monomers (such as styrene and α-methylstyrene), vinyl cyanide monomers (such as (meth) acrylonitrile), methacrylic acid ester-based monomers. It can be composed of a monomer or a copolymer of at least one monomer selected from acrylate monomers. Examples of the methacrylic acid ester monomer include alkyl methacrylate (for example, C _1-20 alkyl methacrylate such as methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, hexyl methacrylate, 2-ethylhexyl methacrylate, preferably C _1- Examples thereof include ₁₀ alkyl methacrylates, more preferably C _1-6 alkyl methacrylates, aryl methacrylates (such as phenyl methacrylate), and cycloalkyl methacrylates (such as cyclohexyl methacrylate). Examples of the acrylate monomer include the acrylate ester of the core layer. In many cases, the vinyl polymer is a polymer having at least one selected from methacrylic monomers and aromatic vinyl monomers [particularly, at least methyl methacrylate, etc.] as a polymerization component. The vinyl polymer constituting the shell layer may be a copolymer with the same crosslinkable monomer as described above.

  The glass transition temperature of the shell layer is, for example, 30 ° C. or higher (for example, about 30 to 300 ° C.), preferably 50 ° C. or higher (for example, about 60 to 250 ° C.), more preferably 70 ° C. or higher (for example, 80 to 200). (Degree C).

  In the core-shell type polymer, the weight ratio of the core layer to the shell layer is the former / the latter = 95/5 to 5/95 (for example, 95/5 to 30/70), preferably 90/10 to 10/90 (for example, 85/15 to 50/50).

  The average particle diameter of the core-shell type polymer (core-shell type polymer particles) can be selected from a range of about 0.05 to 10 μm, for example, and may be, for example, 0.05 to 5 μm, preferably about 0.1 to 3 μm. .

  The rubber layer and the shell layer of the core-shell type elastomer are usually bonded by a graft bond. If necessary, this graft bond is obtained by adding a graft crossing agent that reacts with the shell layer to the polymerization component of the core layer (rubber layer) to give a reactive group to the rubber layer and then forming the shell layer. . Examples of the grafting agent include silicon-based rubbers such as organosiloxanes having vinyl bonds and / or thiol groups (for example, (meth) acryloyloxysiloxane, vinylsiloxane). Moreover, it is preferable that the core-shell type elastomer which does not contain a butadiene component does not melt | dissolve in a toluene: isooctane = 1: 1 (volume ratio) mixed solution at room temperature (about 20-25 degreeC) from a chemical-resistant point.

  The amount of the (B) core-shell type elastomer used is 10 to 80 parts by weight (eg 15 to 80 parts by weight), preferably 20 to 80 parts by weight (eg 30 to 30 parts by weight) with respect to 100 parts by weight of the (A) PBT resin. 80 parts by weight). If the amount of the core-shell type elastomer used is too small, it is difficult to improve impact resistance and flexibility. Note that (B) the core-shell type elastomer is incompatible with the (A) PBT resin component, so if the amount of the core-shell type elastomer used is too large, agglomeration occurs and sufficient impact resistance and flexibility are sufficiently obtained. Not only can it not be improved, it can also make it worse.

  The core-shell type polymer may be one prepared by a conventional method (emulsion polymerization method, seed polymerization method, micro suspension polymerization method, suspension polymerization method, etc.), or a commercially available product may be used. For example, the core-shell type polymer can be obtained from Rohm and Haas Japan Co., Ltd. as “Paraloid EXL-2314”.

  (C) An aromatic polycarbodiimide compound is a compound having a carbodiimide group (—N═C═N—) in the molecule and containing an aromatic component in its skeleton. It is difficult to improve hydrolysis resistance of a carbodiimide compound whose skeleton is only an aliphatic component.

  (C) As an aromatic carbodiimide compound, for example, at least one selected from unsubstituted or substituted groups (alkyl groups, nitro groups, amino groups (or N-substituted amino groups), hydroxyl groups, alkoxy groups, halogen atoms, etc. Poly (diphenylalkanecarbodiimide) [for example, poly (4,4′-diphenylmethanecarbodiimide), poly (3,5′-dimethyl-4,4′-biphenylmethanecarbodiimide), poly (3,5 '-Dimethyl-4,4'-diphenylmethanecarbodiimide)], poly (arylene carbodiimide) having no substituent or the above substituents [for example, poly (p-phenylene carbodiimide), poly (m-phenylene carbodiimide), poly (naphthy Lencarbodiimide), poly (1,3-diisopropyl) Le phenylene carbodiimide), poly (1-methyl-3,5-diisopropyl phenylene carbodiimide), poly (1,3,5-triethyl phenylene carbodiimide) and poly (triisopropyl phenylene carbodiimide) and the like] and the like. These aromatic polycarbodiimide compounds can be used alone or in combination of two or more.

  Of these aromatic polycarbodiimide compounds, poly (4,4'-diphenylmethanecarbodiimide), poly (phenylenecarbodiimide) and poly (triisopropylphenylenecarbodiimide) are preferably used.

  The number average molecular weight of the polycarbodiimide compound is about 1,000 to 30,000, preferably about 2,000 to 25,000. If the number average molecular weight is too small, the heat resistance may be inferior. If it is too large, the resin may not be sufficiently dispersed and the hydrolysis resistance may not be sufficiently improved.

  The amount of the (C) aromatic polycarbodiimide compound used is 0.01 to 5 parts by weight (for example, 0.05 to 5 parts by weight), preferably 0.1 to 100 parts by weight of the (A) PBT resin. The amount is about 3 parts by weight (for example, 0.2 to 2 parts by weight), more preferably about 0.3 to 1.5 parts by weight (for example, 0.3 to 1 part by weight). (C) If the amount of the aromatic polycarbodiimide compound used is too small, it is difficult to obtain high hydrolysis resistance, and if it is too large, the fluidity is reduced, and gel components and carbides are produced during compounding and molding. It tends to occur.

  (D) Antioxidants include hindered phenols, thioethers, hindered amines, phosphorus antioxidants, and the like.

Hindered phenolic antioxidants include monocyclic hindered phenol compounds, polycyclic hindered phenol compounds linked by a hydrocarbon group or a group containing a sulfur atom, hindered phenol compounds having an ester group or an amide group, etc. It may be. Examples of the hindered phenol antioxidant include 2,6-di-t-butyl-p-cresol, C _2-10 alkylene bis (t-butylphenol) [for example, 2,2′-methylene bis (4-methyl). -6-tert-butylphenol), 4,4'-methylenebis (2,6-di-tert-butylphenol)], tris (di-tert-butyl-hydroxybenzyl) benzene [for example, 1,3,5-trimethyl -2,4,6-tris (3,5-di-t-butyl-4-hydroxybenzyl) benzene etc.], C _2-10 alkanediol-bis [(di-t-butyl-hydroxyphenyl) propionate [e.g. 1,6-hexanediol-bis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], etc.], di- or tri- Carboxymethyl _{C 2-4} alkanediol - bis (t-butyl - hydroxyphenyl) propionate [e.g., triethylene glycol - bis [3- (3-t-butyl-5-methyl-4-hydroxyphenyl) propionate], etc.], C _3-8 alkanetriol-bis [(di-t-butyl-hydroxyphenyl) propionate, C _4-8 alkanetetraol tetrakis [(di-t-butyl-hydroxyphenyl) propionate] [eg pentaerythritol tetrakis [3 -(3,5-di-t-butyl-4-hydroxyphenyl) propionate], etc.], long-chain alkyl (di-t-butylphenyl) propionate [e.g. n-octadecyl-3- (4 ', 5'- Di-t-butylphenyl) propionate, stearyl-2- (3 , 5-di-t-butyl-4-hydroxyphenyl) propionate], 2-t-butyl-6- (3-t-butyl-5-methyl-2-hydroxybenzyl) -4-methylphenyl acrylate, 4 , 4'-thiobis (3-methyl-6-t-butylphenol) and the like. These phenolic antioxidants can be used alone or in combination of two or more. Examples of phenolic antioxidants include tetrakis [methylene-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate] methane, triethylene glycol bis [3- (3-t-butyl-4- Hydroxy-5-methylphenyl) propionate] and the like are preferably used.

Examples of the thioether-based antioxidant include dilong chain alkylthiodipropionate (dilaurylthiodipropionate, ditridecylthiodipropionate, etc.), tetrakis [methylene-3- (long chain alkylthio) propionate] alkane (for example, , Tetrakis [methylene-3- (dodecylthio) propionate] methane, etc.). Examples of the long chain alkyl group include a linear or branched C _8-20 alkyl group.

  Examples of hindered amine antioxidants include 4-methoxy-2,2,6,6-tetramethylpiperidine, 4-benzoyloxy-2,2,6,6-tetramethylpiperidine, bis- (2,2, 6,6-tetramethyl-4-piperidyl) oxalate, bis- (2,2,6,6-tetramethyl-4-piperidyl) adipate, bis- (2,2,6,6-tetramethyl-4-piperidyl) ) Terephthalate, 1,2-bis (2,2,6,6-tetramethyl-4-piperidyloxy) ethane, phenyl-1-naphthylamine, phenyl-2-naphthylamine, N, N'-diphenyl-1,4- Examples thereof include phenylenediamine and N-phenyl-N′-cyclohexyl-1,4-phenylenediamine.

  Examples of phosphorus antioxidants include triisodecyl phosphite, triphenyl phosphite, diphenylisodecyl phosphite, 2,2-methylenebis (4,6-di-t-butylphenyl) octyl phosphite, and tris (2 , 4-di-t-butylphenyl) phosphite, tris (2-t-butylphenyl) phosphite, bis (2-t-butylphenyl) phenylphosphite, tris [2- (1,1-dimethylpropyl) -Phenyl] phosphite, tris (2-t-butyl-4-phenylphenyl) phosphite, tetrakis (2,4-di-t-butylphenyl) -4,4'-biphenylenediphosphonite, and the like.

  Furthermore, examples of the antioxidant include hydroquinone antioxidants (for example, 2,5-di-t-butylhydroquinone) and quinoline antioxidants (for example, 6-ethoxy-2,2,4-trimethyl-1). , 2-dihydroquinoline etc.).

  These antioxidants can be used alone or in combination of two or more. Among these antioxidants, from the viewpoint of suppressing discoloration and hydrolyzability, (D) the antioxidant is preferably a hindered phenol antioxidant, and a hindered phenol antioxidant and a thioether antioxidant. When combined with the above, the above-described effect is more efficiently expressed. (D) The antioxidant is also important for improving the heat resistance stability of the polyester elastomer. In addition, when using a hindered phenolic antioxidant and a thioether type antioxidant together, the weight ratio of both can be selected from the range of about 90 / 10-10 / 90 (for example, 80 / 20-20 / 80). It is desirable to adjust so that the addition amount of the thioether antioxidant is small. The weight ratio between the two may be about 90/10 to 60/40 (for example, 80/20 to 70/30).

  (D) The addition amount of the whole antioxidant is 0.01 to 5 parts by weight (for example, 0.1 to 3 parts by weight), preferably 0.5 to 3 parts per 100 parts by weight of (A) PBT resin. It is about part by weight (for example, 0.5 to 2 parts by weight), more preferably about 0.7 to 2.5 parts by weight (for example, 0.8 to 2.3 parts by weight). If the amount added is too small, it is not effective, and if it is too large, there is a concern about bleeding out from the molded product.

In the resin composition of the present invention, if necessary, an epoxy compound, particularly a polyfunctional epoxy compound (for example, an epoxy resin such as a glycidyl ether type epoxy resin or a glycidyl ester type epoxy resin, a vinyl copolymer having a glycidyl group, etc.) Etc. may be added. Examples of the polyfunctional epoxy compound include aromatic epoxy resins (bisphenol type epoxy resin, novolac type epoxy resin, etc.), and examples of vinyl copolymers include (meth) acrylic acid glycidyl ester copolymers, Olefin- (meth) acrylic acid glycidyl ester copolymer such as (meth) acrylic acid C _1-4 alkyl ester- (meth) acrylic acid glycidyl ester copolymer, ethylene- (meth) acrylic acid glycidyl ester copolymer, Examples include olefin- (meth) acrylic acid C _1-4 alkyl ester- (meth) acrylic acid glycidyl ester copolymers. An epoxy compound can be used individually or in combination of 2 or more types. Even if the usage-amount of an epoxy compound is 0.1-20 weight part (for example, 0.5-15 weight part) with respect to 100 weight part of (A) PBT resin, Preferably it is about 1-10 weight part. Good.

  An organic or inorganic filler may be added to the resin composition of the present invention. Examples of the inorganic filler include powder (calcium carbonate, highly dispersible silicate, alumina, aluminum hydroxide, talc, clay, mica, glass flake, glass powder, glass beads, quartz powder, silica sand, wollastonite. Carbon black, barium sulfate, calcined gypsum, silicon carbide, boron nitride, silicon nitride, etc.), plate-like bodies (inorganic compounds thereof), fibers (glass fibers, carbon fibers, etc.) and the like. The fillers may be used alone or in combination of two or more.

  In addition, the resin composition of the present invention includes known additives that are added to thermoplastic resins and thermosetting resins as necessary, for example, heat stabilizers other than the above-mentioned antioxidants, ultraviolet absorbers, and the like. Add stabilizers, antistatic agents, colorants such as dyes and pigments, lubricants, plasticizers and crystallization accelerators, crystal nucleating agents, fillers, flame retardants, etc. to the extent that they do not impair toughness and flexibility. Good.

  The resin composition of the present invention has flexibility and high impact resistance. The resin composition of the present invention may have a flexural modulus specified by ISO178 of about 100 to 1000 MPa, particularly 600 MPa or less, preferably 200 to 550 MPa, and more preferably about 250 to 500 MPa. Furthermore, in the PBT resin composition for the outermost layer, the nominal strain by the tensile test measured by the measuring method described in ISO527-1, 2 is preferably 200% or more.

  The resin composition of the present invention can be easily prepared in the same manner as the conventional method for preparing a resin composition. For example, (1) all components constituting the composition are mixed, and the mixture is supplied to an extruder and melt kneaded. (2) A part of the components constituting the composition is supplied from the main feed port of the extruder, and the remaining components are supplied from the side feed port and melt-kneaded to obtain a pellet-like composition. A method of obtaining a product, (3) a method of preparing pellets having different compositions once using a melt-kneading means such as melt extrusion, mixing these pellets and adjusting to a predetermined composition, and the like can be employed.

  The resin composition of the present invention is also excellent in moldability, and various molded products can be molded using a conventional method such as an injection molding machine, an extrusion molding machine, or a blow molding machine.

  The resin composition of the present invention has flexibility, ductility, and impact resistance, and is improved in hydrolysis resistance, weather resistance, and compatibility. Moreover, it has high toughness, organic chemical resistance, and ozone resistance even at low temperatures. In particular, it has high chemical resistance against organic solvents such as gasoline fuel and its vapor. Therefore, the PBT resin composition of the present invention is useful for forming at least one layer in a fuel tube (or fuel hose, fuel pipe) having a single layer or multilayer structure extruded into a hollow cylinder. The fuel tube (or fuel hose, fuel pipe) may have a multilayer structure including an inner layer, a barrier layer, and an outermost layer. It is also possible to provide a four-layer structure by interposing an intermediate layer composed of the inner layer PBT resin composition between the barrier layer and the outermost layer. For example, an intermediate layer (intermediate layer composed of a PBT resin composition) may be interposed between the inner layer and the barrier layer and / or between the barrier layer and the outermost layer. Furthermore, if necessary, an adhesive layer may be interposed between the layers, but the adhesive layer is not always necessary.

  The inner layer is formed of, for example, a polyalkylene arylate resin in which an elastomer component is alloyed or copolymerized (polyalkylene arylate, for example, polyalkylene terephthalate such as polybutylene terephthalate, polyalkylene naphthalate such as polyethylene naphthalate or polybutylene naphthalate). Phthalate, etc .; these polyalkylene arylate copolymers, etc.). For example, the inner layer is composed of 20 to 40 parts by weight of (B) elastomer component (such as the core-shell type elastomer) and (C) aromatic carbodiimide compound with respect to 100 parts by weight of the polyalkylene arylate resin (such as the polybutylene terephthalate resin). You may comprise by the resin composition containing 0.01-5 weight part.

  The barrier layer (low transmission layer) is a polyalkylene arylate resin (crystalline polyalkylene arylate, for example, polyalkylene terephthalate such as polybutylene terephthalate, polyalkylene naphthalate such as polyethylene naphthalate, polybutylene naphthalate, etc .; Alkylene arylate copolymer, etc.). For example, the barrier layer may be composed of a resin composition containing 0.01 to 5 parts by weight of (C) an aromatic polycarbodiimide compound with respect to 100 parts by weight of a polyalkylene arylate resin (such as the PBT resin). . For the PBT resin and the like, it is also preferable to use a polybutylene terephthalate homopolymer and / or a polybutylene terephthalate copolymer alone from the viewpoint of barrier properties.

  The resin composition of the present invention may be applied to any of the inner layer, the barrier layer, and the outermost layer in a fuel tube (or fuel hose, fuel pipe) having a multilayer structure. It is preferable to do this.

  In a tube (such as a fuel tube) having a multilayer structure, the thickness and bending elastic modulus of each layer are not particularly limited, and the above-mentioned Patent Documents 4 and 5 can be referred to. For example, the inner layer may have a thickness of 0.01 to 0.5 mm, the barrier layer may have a thickness of 0.01 to 1 mm, and the outermost layer may have a thickness of about 0.1 to 3 mm. If the thickness of each layer is too thin, it is difficult to fully exhibit the function of each layer, and if it is too thick, the weight increases. The inner diameter of the tube may be, for example, about 3 to 60 mm (for example, 4 to 50 mm), preferably about 4 to 40 mm (for example, 4 to 30 mm). Further, the outer diameter of the tube may be, for example, about 5 to 50 mm (for example, 6 to 45 mm), preferably about 7 to 40 mm (for example, 8 to 32 mm). If the inner diameter of the tube is too small, the flow rate of the fuel will be restricted and the rigidity of the tube will be too high, and if it is too large, the overall rigidity will decrease and the weight will increase. Tends to be complicated.

  Moreover, the bending elastic modulus of the material used for each layer may be about 300 to 2000 MPa for the inner layer, preferably 1000 to 2000 MPa, about 1000 to 3000 MPa for the barrier layer, and about 100 to 10,000 MPa for the outermost layer.

  The tube can be formed by an extrusion method (co-extrusion method for a fuel tube having a multilayer structure) or the like. If necessary, a tube having a straight shape (straight tube) or a bellows structure can be formed using a corrugator using a vacuum sizing method or the like. For a multilayer tube, for example, a single-layer structure tube is produced using the above inner layer material using an extruder, and a barrier layer (intermediate layer) and an outermost layer are sequentially formed on the outer peripheral surface of the tube using an extruder. Alternatively, it may be produced by spirally winding an extrusion molding or a tape-like extrusion molding. In this method, if necessary, the surface of a previously formed layer may be roughened by blasting or the like, or may be laminated by applying an adhesive.

  Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited to these examples. The following characteristics were evaluated as follows.

Examples 1-4 and Comparative Examples 1-5
In Examples and Comparative Examples, a resin composition for a fuel tube was prepared using the following materials, and the outermost layer of the fuel tube was formed. In Comparative Example 3, compounding was difficult and could not be used for the test.

(A) PBT resin (A-1) Polybutylene terephthalate (manufactured by Wintech Polymer Co., Ltd., intrinsic viscosity 0.9 dl / g)
Polyester elastomer component (A-2) PBT elastomer (ether type) ("Perprene GP400" manufactured by Toyobo Co., Ltd.)
(A-3) PBT elastomer (ester type) (“Perprene S1002” manufactured by Toyobo Co., Ltd.)
(B) Core-shell type elastomer Acrylic core-shell type polymer: “Paraloid EXL-2314” manufactured by Rohm and Haas Japan Co., Ltd.
(C) Carbodiimide compound Aromatic polycarbodiimide; “STABAKZOL P” manufactured by Rhein Chemie Japan
(D) Antioxidant (D1) Hindered phenolic antioxidant; “Irganox 1010” manufactured by Ciba
(D2) Thioether antioxidant; “ADEKA STAB AO412S” manufactured by ADEKA
These components were used in proportions shown in the table, and were melt-kneaded and pelletized with a twin-screw extruder (manufactured by Nippon Steel Works). Moreover, the test piece was produced by injection molding or punching from a film.

[Tensile elongation]
Evaluation was made according to ISO527-1,2, and the elongation was measured up to 200% in terms of tensile nominal strain.

[Bending elastic modulus]
Evaluation was performed in accordance with ISO178.

[Charpy impact strength]
Based on ISO179 / 1eA, it evaluated at 23 degreeC and -40 degreeC. In addition, the measurement at -40 degreeC prepared the -40 degreeC refrigerator near the measuring device, took out after fully cooling a test piece, and measured immediately. In the evaluation of Charpy impact strength, “◯” indicates ductile fracture and “×” indicates brittle fracture.

[Hydrolysis Life (PCT)]
An ASTM No. 4 dumbbell mold was punched out of a film having a thickness of 0.3 mm to prepare a sample, which was then subjected to a hydrolysis treatment in a pressure cooker test (121 ° C. × 2 atm). The test piece after 48 hours treatment was taken out and subjected to a 180 ° C. bending test to evaluate the presence or absence of cracks. The thing which did not have a crack was made into "(circle)", and the thing with a crack was made into "x".

[Heat aging resistance (HA)]
The film test piece was subjected to a heat aging treatment at 120 ° C. After processing for 1000 hours, a 180 ° C. bending test was performed to evaluate the presence or absence of cracks. The thing which did not have a crack was made into "(circle)", and the thing with a crack was made into "x".

[Weatherability]
As the ozone resistance, the film test piece was pulled in a 60% strain state and left in a 50 pphm ozone generator (40 ° C.), and the occurrence of cracks after 1000 hours was observed. Further, the xenon resistance of the film test piece was pulled in a 60% strain state, left in a weathering tester equipped with a xenon lamp for 1000 hours, and the occurrence of cracks was observed. Those with no cracks were marked with “◯”, and those with cracks were marked with “x”.

[Extrudability]
The extrudability of the tube was evaluated as follows. That is, the extrudability of a multilayer tube composed of four layers of an outermost layer, an intermediate layer, a barrier layer and an inner layer was evaluated. That is, a PBT resin composition in which 26 parts by weight of (B) core-shell type elastomer is blended with 100 parts by weight of (A-1) PBT homopolymer in the inner layer and intermediate layer, and a PBT homopolymer (Wintech polymer in the barrier layer) Co., Ltd., with an intrinsic viscosity of 1.1 dl / g) and the resin composition shown in Table 1 as the outermost layer of the tube, and co-extrusion molding with an extruder (multilayer extruder manufactured by Plastic Engineering Laboratory Co., Ltd.) The four-layer tube of Examples 1 to 4 and Comparative Example 1 was produced. Extrudability was judged by the roundness and appearance of each layer. The thing without abnormality was set as "(circle)".

  The composition of Comparative Example 1 had a high elastic modulus, and the composition of Comparative Example 2 was brittle fractured by low temperature impact. Further, for the composition of Comparative Example 3, it was difficult to prepare the resin composition itself. Therefore, in these comparative examples 1 to 3, the extrudability of the tube was not evaluated. Although the compositions of Comparative Examples 4 and 5 met the specifications of the predetermined physical properties in a short period, the properties over a long period were poor, and thus the extrudability was not evaluated in the same manner.

  In Examples 1 to 4 where the extrudability was evaluated, there was no problem in extrudability.

  The results are shown in Table 1 (in the table, the ratio of each component (A) to (D) of the resin composition indicates parts by weight).

Example 5
The inner layer PBT resin composition, the barrier layer PBT resin composition, and the outermost layer PBT resin composition are each melt-kneaded using an extruder (extruder: multilayer extruder manufactured by Plastics Engineering Laboratory) and co-extruded. By molding, a fuel tube (inner diameter: 12 mm, outer diameter: 14.2 mm) having a three-layer structure including an inner layer having a thickness of 300 μm, a barrier layer having a thickness of 500 μm, and an outermost layer having a thickness of 300 μm was produced.

  In addition, the PBT resin composition for the inner layer is (B) 25 parts by weight of the core-shell type elastomer, (C) 0.4 parts by weight of the aromatic polycarbodiimide compound, and (D) with respect to 100 parts by weight of the (A-1) PBT resin. 1) parts by weight of antioxidant [0.6 parts by weight of (D-1) and 0.4 parts by weight of (D-2)], and the PBT resin composition for the barrier layer is PBT resin (A-1) 100 1 part by weight of (C) aromatic polycarbodiimide compound with respect to parts by weight, and the PBT resin composition for the outermost layer comprises (A) 100 parts by weight of PBT resin [(A-1) 56 parts by weight and (A-2 ) 44 parts by weight] (B) 44 parts by weight of the core-shell type elastomer, (C) 0.6 parts by weight of the aromatic polycarbodiimide compound, (D) 1.1 parts by weight of the antioxidant [(D-1) 0.7 parts by weight and (D-2) 0.4 parts by weight].

Example 6
A multilayer tube was produced in the same manner as in Example 5 except that a polybutylene naphthalate (PBN) resin composition (Toyobo Co., Ltd. “Perprene EN2000”) was used for the barrier layer.

Comparative Example 6
A multilayer tube was produced in the same manner as in Example 5 except that an ether type PBT elastomer (“Perprene P150B” manufactured by Toyobo Co., Ltd., A-4) was used as the outer layer material.

Comparative Example 7
A multilayer tube was produced in the same manner as in Example 6 except that a polyester type PBT elastomer resin composition (“Perprene S3001” manufactured by Toyobo Co., Ltd., A-5) was used as the outer layer material.

[Evaluation of fuel tube characteristics]
About the multilayer tube of the 3 layer structure obtained in Examples 5-6 and Comparative Examples 6-7, the fuel tube characteristic was evaluated as follows.

[Fuel permeation]
As an evaluation test gasoline, Fuel C (toluene / isooctane = 50/50 (volume%)) mixed fuel (FC / E10) in which 10 parts by volume of ethanol was mixed with 100 parts by volume was sealed in a hose with both ends sealed. Enclose and let stand at 40 ° C for 1000 hours to stabilize, then discharge the contents (mixed fuel) and re-fill with new mixed fuel (FC / E10), then leave it in the predetermined temperature cycle environment The fuel permeation amount was measured every 24 hours. This operation was repeated three times, and the maximum value among the three measured values was defined as the fuel permeation amount per test [[mg / test) = (mg / 24Hr)]. Moreover, the fuel permeation amount of 10 mg / test or less was set as “◯”.

[Hydrolysis resistance (pressure cooker test)]
The fuel tube was allowed to stand for 48 hours under conditions of a temperature of 121 ° C., 2 atmospheres, and a humidity of 100%, and then bent at 180 ° to confirm the presence or absence of cracks. The tube in which no crack was generated was indicated as “◯”, and the tube in which a crack was generated was indicated as “x”.

[Flexibility (flexibility)]
Using a fuel tube, the stress required to bend the tube by 10 mm was measured under the conditions of a distance between fulcrums of 100 mm and a test speed of 100 mm / min in accordance with a three-point bending test described in JIS K7171.

  Note that the bending stress measured in this test is an index of bending workability. It means that the smaller the bending stress is, the more flexible and easy to bend, and it is usually judged that the flexibility is excellent when the bending stress is 60 N or less. In the table, the case where the bending stress is 60 N or less is indicated by “◯”.

[Low temperature flexibility]
The fuel tube was cooled at −40 ° C. for 4 hours, and then immediately bent to 180 ° to check for cracks. The tube in which no crack was generated was indicated as “◯”, and the tube in which a crack was generated was indicated as “x”.

[Sour gasoline resistance]
A simulated modified gasoline in which 5% by weight of lauroyl peroxide (LPO) was mixed with Fuel C (toluene / isooctane = 50/50 (volume%)) was prepared. Then, metal pipes are press-fitted into both ends of a 10 m long fuel tube, and the simulated modified gasoline is circulated at 60 ° C. for 8 hours at a pressure of 0.3 MPa through a pressure regulator, and then 16 hours. Enclosed. After performing this operation as one cycle for 10 cycles, the fuel tube was sampled, bent at 180 °, the bent portion was halved, and the inner surface state was visually observed. As a result, the tube with no cracks and other abnormalities was evaluated as “◯”, and the tube with cracks or cracks as “×” was evaluated for sour gasoline resistance.

[Peeling property (peeling resistance)]
A burst property test was performed, and the state between the layers of the fracture sample was observed. The case where the adhesive force was strong and could not be peeled off, or the case where peeling did not occur at the interface between layers was indicated as “◯”, and the case where peeling occurred at the interlayer interface was indicated as “x”.

[Heat aging resistance]
Evaluate the heat aging resistance by leaving the tube in an environment of 135 ° C for 500 hours, bending it to 180 °, and marking the tube with no abnormalities such as cracks as "○" and the tube with cracks or cracks as "X". It was.

[Weatherability]
As one of the weather resistance indicators, ozone resistance was evaluated. After leaving the sample in an ozone environment of 50 pphm in an atmosphere of 40 ° C, the tube was bent at 180 ° and the tube with no abnormalities such as cracks was marked as “O”, and the tube with cracks or cracks as “x”. Was evaluated.

[Weatherability]
As one of the weather resistance indicators, xenon resistance was evaluated based on ASTM D2565. After the sample was left to stand, the weather resistance was evaluated by bending the tube at 180 ° and assigning “○” to the tube in which no abnormality such as cracks occurred and “×” to the tube in which crack or crack occurred.

  The results are shown in Table 2.

  The PBT resin composition of the present invention can be used for various molding applications, and is particularly useful for forming a layer constituting a fuel tube (or fuel hose, fuel pipe). The fuel tube is useful for transporting various fuels, for example, fuel components (liquid fuel, gaseous fuel, etc.) such as propane, gasoline, alcohol mixed gasoline, etc., such as automobiles, aircrafts, two-wheeled vehicles, tractors, tillers, etc. It can be used as a fuel-related equipment member of the vehicle and peripheral equipment members (fuel transfer parts).

Claims (5)

A fuel tube having a multilayer structure that is extruded into a hollow cylindrical shape and is composed of an inner layer, a barrier layer, and an outermost layer,
The inner layer is composed of (a) a polyalkylene arylate resin composition containing (b) 20 to 40 parts by weight of a core-shell type elastomer with respect to 100 parts by weight of a polyalkylene arylate resin,
The barrier layer is composed of a polyalkylene arylate resin composition containing a polyalkylene arylate resin, and
The outermost layer is composed of ( A1 ) a polybutylene terephthalate homopolymer and / or a polybutylene terephthalate copolymer, and (A2) a polyester elastomer containing polybutylene terephthalate as a hard segment in a proportion of 20 to 90% by weight. (A) 10 to 80 parts by weight of the core-shell type elastomer, (C) 0.01 to 5 parts by weight of an aromatic polycarbodiimide compound, and (D) an antioxidant with respect to 100 parts by weight of the polybutylene terephthalate resin. The polybutylene terephthalate resin composition containing 0.01 to 5 parts by weight , and the weight ratio of (A1) polybutylene terephthalate homopolymer and / or polybutylene terephthalate copolymer and (A2) polyester elastomer However, the former / the latter = 30/70 to 70/30 Tube. (B) core-shell type elastomer and (B) core-shell elastomer of claim 1 Symbol mounting the fuel tube is an acrylic core-shell elastomer free from a diene component. (A1) and polybutylene terephthalate homopolymer and / or polybutylene terephthalate copolymer, (A2) weight ratio of the polyester elastomer, according to claim 1 or 2, wherein the former / the latter = 40 / 60-60 / 40 Fuel tube . (D) The fuel according to any one of claims 1 to 3 , wherein the antioxidant is composed of a hindered phenol-based antioxidant or a combination of a hindered phenol-based antioxidant and a thioether-based antioxidant. Tube . The fuel tube according to any one of claims 1 to 4 , wherein the flexural modulus defined by ISO 178 is 600 MPa or less.