JP5133496B2 - Polyamide resin composition and fuel tank parts - Google Patents

Description

  The present invention relates to a polyamide resin composition and a fuel tank component using the same. More specifically, the present invention relates to a resin composition and a fuel tank component that have excellent fuel permeation resistance and adhesion to a polyolefin resin, and are highly reliable for safety required for automotive parts.

Conventionally, for safety and environmental measures, it has been required to reduce the volatilization amount of the fuel from the wall of the fuel tank or the accessory parts such as accessory parts. For example, in the automobile field, the fuel tank body of an automobile is manufactured from metal or resin, but in the case of a resin fuel tank, a method of sulfonating the resin (SO) in order to reduce the amount of fuel permeated from the tank body. ₃ treatment (see Patent Document 1), fluorine treatment method (F ₂ treatment), hollow molded product having a multilayer structure with a barrier resin (see Patent Document 2), polyamide in a continuous matrix phase of polyethylene, etc. A method of dispersing the barrier resin in the form of flakes (see Patent Document 3) has been developed.

  However, even if the permeation amount of the fuel from the fuel tank main body is reduced by the above method or the like, actually, from various parts attached to the fuel tank (for example, valves and the like, hereinafter referred to as “fuel tank parts”). This is an obstacle to reducing the amount of volatilization from the entire fuel part. This is because various parts attached to the fuel tank are usually made of high-density polyethylene, which is the same material as the outer wall of the fuel tank, in order to obtain sufficient adhesion strength with the fuel tank. This is because the fuel permeability is poor.

Therefore, it has been studied to form various parts attached to the fuel tank using a polyamide resin excellent in fuel permeation resistance and a composition containing the resin and a polyolefin resin such as polyethylene. (See Patent Documents 4 and 5.)
More specifically, a composition in which a polyamide resin is present as a dispersed phase in a polyolefin which is a matrix phase (continuous phase) is used for parts such as valves attached to a fuel tank (Patent Document 6). And a fuel component (see Patent Document 8) obtained by fusing a crystalline polyamide resin having a high amino terminal concentration and a modified polyolefin.
However, conventionally, aliphatic polyamides such as nylon 6 and nylon 12 have been used in such a technique. Although they have a relatively high adhesion (fusion property) to the polyolefin resin part in the fuel tank body and fuel tank parts, the fuel permeability resistance is still insufficient.
The present inventors thought that the use of a highly aromatic polyamide as a polyamide resin can improve the fuel permeation resistance. However, a highly aromatic polyamide generally adheres to a polyolefin resin. The property (fusion property) is low.
Japanese Patent Publication No.46-23914 Japanese Patent Publication No. 55-49989 Japanese Patent Publication No. 60-14695 JP 2002-138917 A JP 2003-336556 A JP 2001-302910 A JP 2002-275313 A JP 2002-370551 A

  The present invention is intended to solve the above-described problems, and provides a fuel tank component that is required for automobile parts, has high safety reliability, and has excellent fuel permeation resistance and a method for manufacturing the same. It is to be.

As a result of diligent studies to solve the above problems, the present inventors firstly have a fuel tank part (A) containing an aromatic polyamide resin capable of realizing high fuel permeation resistance, and a fuel tank. It was considered effective to have a polyolefin resin part (B) exhibiting high adhesiveness (fusibility).
In addition, the inventors of the present invention have a high fusing property with the polyolefin resin part (B) as a material for the aromatic polyamide resin-containing part (A) in the fuel tank part, and realize high fuel permeation resistance. A possible polyamide resin composition was studied.
As a result, it contains an appropriate amount of the polyolefin-based resin (b) together with the aromatic polyamide resin (a), and in addition, has a high compatibility with the aromatic polyamide (a) and contains the aromatic polyamide resin-containing portion (A). The inventors have found that desired physical properties can be obtained by containing an appropriate amount of a polyamide resin (c) having a low melting point, which can improve the fusing property with the polyolefin resin part (B), and have reached the present invention.
That is, the present invention includes a polyolefin resin (b) of 50 to 100 parts by weight and a melting point measured by DSC with respect to 100 parts by weight of a polyamide resin (a) containing 30 mol% or more of a repeating unit derived from an aromatic monomer. Is a polyamide resin composition comprising 2-30 parts by weight of a polyamide resin (c) of less than 230 ° C., wherein the polyamide resin (a) has a melting point of 230 ° C. or higher and 320 ° C. or lower as measured by DSC and a, and a polyolefin resin (b) is state, and are not modified with an acid anhydride, and, with the polyamide resin composition was formed by using part (a), the polyolefin resin (d) which is used for heat sealing a portion formed (B) by using a fuel tank component polyamide resin composition, and by using the polyamide resin composition It resides in made fuel tank parts.

The polyamide resin composition of the present invention has excellent fuel permeation resistance and excellent heat fusion with polyolefin resins such as polyethylene, and is suitable as various parts attached to resin fuel tanks such as automobiles. Can be used.
Moreover, the fuel tank component with high reliability with respect to the safety | security requested | required of the components for motor vehicles can be obtained by forming using the composition provided with the said characteristic.

Hereinafter, the present invention will be described in detail.
In the present invention, the “melting point measured by DSC” is a value measured in a differential scanning calorimetry at a heating rate of 10 ° C./min and under a nitrogen atmosphere.
The polyamide resin composition of the present invention has a polyamide resin (a) (hereinafter sometimes referred to as “aromatic polyamide resin (a)”) 100 weights containing 30 mol% or more of a repeating unit derived from an aromatic monomer. Part of the polyolefin resin (b), and a polyamide resin (c) having a melting point measured by DSC of less than 230 ° C. (hereinafter referred to as “low melting point polyamide resin (c)”). ) A composition comprising 2 to 30 parts by weight , wherein the polyamide resin (a) has a melting point measured by DSC of 230 ° C. or higher and 320 ° C. or lower, and the polyolefin resin (b) It is a polyamide resin composition which is modified with an acid anhydride .
The polyamide resin (a) used in the present invention is a polyamide mainly composed of amino acids, lactams or diamines and dicarboxylic acids, and is a polyamide resin containing 30 mol% or more of repeating units derived from aromatic monomers. is there.
The aromatic monomer in the present invention is a monomer containing an aromatic group in the compound, for example, amino acids such as paraaminomethylbenzoic acid, diamines such as metaxylylenediamine and paraxylylenediamine, terephthalic acid, isophthalic acid And dicarboxylic acids such as 2-chloroterephthalic acid, 2-methylterephthalic acid, 5-methylisophthalic acid, 5-sodium sulfoisophthalic acid, 2,6-naphthalenedicarboxylic acid, hexahydroterephthalic acid, hexahydroisophthalic acid, etc. It is done.
Non-aromatic monomers include 6-aminocaproic acid, 11-aminoundecanoic acid, amino acid of 12-aminododecanoic acid, lactams such as ε-caprolactam and ω-laurolactam, tetramethylenediamine, hexamethylenediamine, 2 -Methylpentamethylenediamine, nonamethylenediamine, undecamethylenediamine, dodecamethylenediamine, 2,2,4- / 2,4,4-trimethylhexamethylenediamine, 5-methylnonamethylenediamine, 1,3-bis ( Aminomethyl) cyclohexane, 1,4-bis (aminomethyl) cyclohexane, 1-amino-3-aminomethyl-3,5,5-trimethylcyclohexane, bis (4-aminocyclohexyl) methane, bis (3-methyl-4) -Aminocyclohexyl) methane, 2, Aliphatic and alicyclic diamines such as 2-bis (4-aminocyclohexyl) propane, and aliphatic and alicyclic dicarboxylic acids such as adipic acid, peric acid, azelaic acid, sebacic acid, dodecanedioic acid, etc. Can be mentioned.
The aromatic polyamide resin (a) in the present invention can be obtained by appropriately selecting various monomers typified by the above compound and polymerizing by a known method. Examples of such polyamide resins include polycaproamide / polyhexamethylene terephthalamide copolymer (nylon 6 / 6T), polyhexamethylene adipamide / polyhexamethylene terephthalamide copolymer (nylon 66 / 6T), polyhexamethylene azide Pamide / polyhexamethylene isophthalamide copolymer (nylon 66 / 6I), polyhexamethylene terephthalamide / polyhexamethylene isophthalamide copolymer (nylon 6T / 6I), polyhexamethylene terephthalamide / polydodecanamide copolymer (nylon 6T / 12) ), Polyhexamethylene adipamide / polyhexamethylene terephthalamide / polyhexamethylene isophthalamide copolymer (nylon 66 / 6T / 6I), polymetaxyl Adipamide (nylon MXD6), polymetaxylylene adipamide / polyparaxylylene adipamide copolymer (nylon MXD6 / PXD6), polymetaxylylene adipamide / polymetaxylylene isophthalamide copolymer (nylon MXD6 / MXDI), polyhexa Examples include, but are not limited to, methylene terephthalamide / poly-2-methylpentamethylene terephthalamide copolymer (nylon 6T / M5T) and polynonamethylene terephthalamide (nylon 9T). Polyamide resins represented by the above resins may be used alone or in combination of two or more.
From the viewpoint of fuel permeation resistance in the polyamide resin composition of the present invention, the polyamide resin (a) has high aromaticity (that is, of the repeating units derived from aromatic monomers among the repeating units constituting the polymer). Those having a high ratio are preferred. Specifically, in the polyamide resin (a), the repeating unit derived from the aromatic monomer is preferably 30 mol% or more, more preferably 40 mol% or more, and more preferably 50 mol% or more. Further preferred.
Generally, the higher the aromaticity of the polyamide resin (a), the higher the melting point and the molding processing temperature. The aromatic polyamide resin (a) of the present invention is a composition for heat-sealing with the resin (d) in the case of multicolor injection molding or insert molding with the polyolefin resin (d), for example, as will be described later. The melting point measured by DSC is 320 ° C. or less because it is easy to melt the whole . The lower limit of the melting point is 230 ° C.
More preferably, the aromatic polyamide (a) of the present invention is polymetaxylylene adipamide (nylon MXD6), polymetaxylylene adipamide / polyparaxylylene adipamide copolymer (nylon MXD6 / PXD6), and polymer. Taxylylene adipamide / polymetaxylylene isophthalamide copolymer (nylon MXD6 / MXDI) and the like, particularly preferably a polyamide using metaxylylenediamine and adipic acid, or metaxylylenediamine and paraxylylenediamine A polyamide comprising a mixture and adipic acid. More specifically, it is a polyamide obtained from adipic acid and a mixed xylylenediamine comprising 55 to 100 mol% of metaxylylenediamine and 45 to 0 mol% of paraxylylenediamine.
When the amount of metaxylylenediamine in the mixed xylylenediamine is less than 55 mol%, the resulting polyamide resin has a very high melting point, which may increase the molding temperature of the composition. Considering the decomposition reaction of the amide bond in the low-melting-point polyamide resin (c) described later, it is not preferable that the molding process temperature of the composition is too high. Therefore, metaxylylenediamine in the mixed xylylenediamine is 55 mol% or more. It is preferable that The amount of metaxylylenediamine is more preferably 70 mol% or more, and particularly preferably 100 mol%.
Also, when the amount of paraxylylenediamine in the mixed xylylenediamine exceeds 45 mol%, the melting point of the obtained polyamide resin becomes very high, and the molding processing temperature of the composition may be increased. The amount of paraxylylenediamine in the mixed xylylenediamine is preferably relatively large from the viewpoint of improving moldability by improving the crystallization speed, and relatively small from the viewpoint of heat fusion with polyolefin resin. Is preferred.
In addition, the aromatic polyamide resin (a) used in the present invention preferably has a number average molecular weight calculated from the number of terminal groups of about 10,000 to 40,000, more preferably about 14,000 to 22,000. When the polyamide resin having a number average molecular weight of less than 10,000 is used, the resulting member may not have the strength required for automobile parts. Moreover, when exceeding 40,000, since melt viscosity is high, it may become difficult to obtain the target member by injection molding.

In the present invention, the polyolefin resin (b) is made of polyethylene, polypropylene, ethylene-olefin copolymer, or one or more polymers selected from the above polymers as a hard segment, and EPDM, EPR, SEBS, SBS, etc. are soft. It is an acid anhydride such as resin as a segment. Specifically, for example, linear low-density polyethylene resin (L-LDPE), low-density polyethylene resin (LDPE), high-density polyethylene resin (HDPE), polypropylene, polyolefin-based thermoplastic elastomer, polyolefin-based thermoplastic vulcanizate, or the like these those acid denatured. These may be used only in one type, but may be used in combination of two or more types. Preferred as the polyolefin resin (b) in the present invention, modified linear low density polyethylene resin (L-LDPE), low density polyethylene resin (LDPE), high density polyethylene resin (HDPE), polypropylene emissions, but anhydride Particularly preferred is a high-density polyethylene resin (HDPE) modified with an acid anhydride.

  The polyamide resin composition in the present invention contains 50 to 100 parts by weight of the polyolefin resin (b) with respect to 100 parts by weight of the aromatic polyamide resin (a). When the polyolefin resin is less than 50 parts by weight, the heat fusion strength with the polyolefin resin (d) constituting the fuel tank part is low, and high reliability for safety required for automobile parts cannot be obtained. . On the other hand, when the polyolefin resin (b) exceeds 100 parts by weight, the fuel permeation resistance becomes insufficient, and the volatilization amount of the fuel cannot be reduced.

The fusing property in the present invention is represented by the heat fusing strength. The high heat fusion strength means that the tensile adhesion strength is 8 MPa or more in an adhesion test according to ASTM described in Examples described later. More preferably, it is 10 MPa or more.
If it is 8 MPa or more in the test, the thermal fusion strength is high, and by using such a material, a fuel tank part that is required for automobile parts and has high reliability for safety can be obtained. In addition, an acid-modified polyethylene resin is generally known as a partner material to be heat-sealed with a polyamide resin composition. However, in the present invention, the partner material is not limited to an acid-modified polyethylene resin, Even in the modified polyethylene resin, the effect of heat fusion can be sufficiently obtained.

In the present invention, the polyamide (c) having a melting point measured by DSC of less than 230 ° C. (that is, a low melting point polyamide resin (c)) is a polyamide resin using a generally known monomer, If melting | fusing point satisfy | fills the said conditions, there will be no restriction | limiting in particular, It consists of diamine and dicarboxylic acid, or is formed using a lactam or an amino acid.
In order to control the melting point below 230 ° C., for example, a method using a molecule having a relatively long methylene chain as a monomer, a method using a molecule having a strong asymmetry, low linearity, and a bulky molecule can be cited. It is done.
As for the molecular structure of the polymer, there is a tendency that the melting point is lowered (crystallinity is lowered) by copolymerizing a molecule having strong asymmetry, low linearity, and bulky molecules (for example, isophthalic acid). As the ratio of such a molecule (monomer) is increased, the melting point gradually decreases to become an amorphous polyamide, but the low melting point polyamide resin (c) of the present invention is an amorphous polyamide. There may be.
What is necessary is just to manufacture a desired low melting point polyamide resin (c), selecting from these methods, or combining suitably as needed.
As a monomer used for the low melting point polyamide resin (c), for example, specific examples of diamine include tetramethylene diamine, hexamethylene diamine, octamethylene diamine, nonamethylene diamine, undecamethylene diamine, dodecamethylene diamine, metaxylylene diamine. , Paraxylylenediamine, 1,3-bis (aminomethyl) cyclohexane, 1,4-bis (aminomethyl) cyclohexane and the like. Specific examples of the dicarboxylic acid include adipic acid, heptanedicarboxylic acid, and octanedicarboxylic acid. Nonanedicarboxylic acid, undecanedicarboxylic acid, dodecanedicarboxylic acid, terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid and the like.
Specific examples of the lactam include α-pyrrolidone, ε-caprolactam, ω-laurolactam, ε-enantolactam, and the like. Specific examples of the aminocarboxylic acid include 6-aminocaproic acid, 7-aminoheptanoic acid, 11 -Aminoundecanoic acid, 12-aminododecanoic acid, etc. are mentioned.
These monomers may be used alone or in combination of two or more.
A desired low-melting-point polyamide resin (c) can be obtained by appropriately selecting a monomer from diamines, dicarboxylic acids, lactams, and the like typified by the above monomer, and polymerizing the monomer.
Preferable examples of the low melting point polyamide resin (c) include aliphatic polyamides such as polyamide 6 and polyamide 12, which are obtained by polymerization of lactam. As the polyamide resin composed of diamine and dicarboxylic acid, if it is an aliphatic polyamide, for example, polyamide 610 composed of hexamethylenediamine and sebacic acid, polyamide 612 composed of hexamethylenediamine and dodecanedioic acid, etc., the methylene chain is relatively long. A polyamide resin is mentioned.
Particularly preferable examples of the low melting point polyamide resin (c) include polyamide 6 and polyamide 12.
The low melting point polyamide resin (c) in the present invention preferably has a number average molecular weight calculated from the number of terminal groups of about 10,000 to 40,000, more preferably about 14,000 to 22,000. When the polyamide resin having a number average molecular weight of less than 10,000 is used, the resulting member may not have the strength required for automobile parts, for example. Moreover, when exceeding 40,000, since melt viscosity is high, it may become difficult to obtain the target member by injection molding.

In the present invention, 50 to 100 parts by weight of the polyolefin resin (b) and 2 to 30 parts of the polyamide (c) having a melting point of less than 230 ° C. measured by DSC with respect to 100 parts by weight of the aromatic polyamide resin (a). It is characterized by containing parts by weight.
When the low-melting-point polyamide resin (c) is less than 2 parts by weight, for example, the heat fusion strength between the polyamide resin composition of the present invention and the polyolefin resin (d) constituting the fuel tank part is low. The high reliability required for safety cannot be obtained. Moreover, when this resin exceeds 30 weight part, fuel-permeation resistance becomes inadequate and the volatilization amount of a fuel cannot be reduced.

The polyamide resin composition according to the present invention is excellent in fuel permeation resistance.
Specifically, in accordance with JIS-Z 0208, a vapor phase cup method using a mixed solution containing 90 vol% of toluene: isooctane = 1: 1 solution (volume ratio) and 10 vol% of ethanol is performed in an atmosphere of 60 ° C. The fuel permeation resistance is preferably 10.0 (g · mm / m ² · day) or less, more preferably 5.0 (g · mm / m ² · day) or less. By using a polyamide resin composition having fuel permeability resistance in the above range, a resin fuel tank part having excellent fuel permeability resistance can be obtained.

The polyamide resin composition of the present invention may contain a filler (filler) as long as the characteristics of the present invention are not impaired. There is no restriction | limiting in particular in the kind of filler, A well-known thing is employable. For example, calcium carbonate, mica, kaolin, wollastonite, aluminum hydroxide, potassium titanate whisker, aluminum borate, glass fiber, glass beads, glass flake, carbon fiber and the like can be mentioned.
Further, if necessary, one or more additives such as a flame retardant, an antistatic agent, a lubricant, a plasticizer, a stabilizer against deterioration due to oxidation, heat, and ultraviolet rays, a colorant, and the like can be used.

The fuel tank component of the present invention has the above-described part (A) formed using the polyamide resin composition of the present invention and a part (B) formed using the polyolefin resin (d), They are characterized by the fact that they are heat-sealed.
Examples of the polyolefin resin (d) include polyethylene and polypropylene, which may be acid-modified or epoxy-modified.
Among these, polyethylene is preferable, and specific examples include linear low density polyethylene resin (L-LDPE), low density polyethylene resin (LDPE), and high density polyethylene resin (HDPE). Particularly preferred is a high density polyethylene resin having a density of 0.93 to 0.96 in ASTM (D1505).
The polyolefin resin (d) of the present invention is also a filler, antioxidant, heat stabilizer, light stabilizer, flame retardant, lubricant, antistatic agent, pigment, etc. Various additives may be contained.

  The fuel tank parts are prepared in advance by separately molding a member made of the polyamide resin composition of the present invention and a member made of the polyolefin resin (d) and welding them by a hot plate welding method or the like. Is also possible. However, from the viewpoint of the degree of freedom of the shape of the obtained molded product, productivity, and cost, after molding one member by injection molding, the other resin or resin composition is overmolded (insert molding method, many methods). Color molding method) can be preferably employed. Other specific examples of welding methods include vibration welding methods, injection welding methods such as die slide injection (DSI), die rotary injection (DRI) and two-color molding, ultrasonic welding methods, spin welding methods, hot plate welding methods, Examples thereof include a hot wire welding method, a laser welding method, and a high frequency induction heating welding method.

  The fuel tank component of the present invention has excellent adhesion (welding) property to the tank body, and is preferable for, for example, a hose connector, a cut-off valve, a fuel pump casing, an inlet pipe and the like associated with a gasoline tank for automobiles. Can be used.

  Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples, but the present invention is not limited thereto. In addition, the physical-property measurement of the molded article in an Example and a comparative example was performed as follows.

[Evaluation of adhesion (fusion) property]
Using a polyamide resin composition (primary material) having the composition shown in Tables 1 and 2, molding a size of half the size of the dumbbell for No. 1 tensile test having a thickness of 3.2 mm according to ASTM D-638 in the major axis direction. The product was molded at a cylinder temperature of 260 ° C and a mold temperature of 50 ° C.
Next, the molded product is mounted on a test mold cavity, and unmodified high-density polyethylene resin (Novatech HJ560 manufactured by Nippon Polychem Co., Ltd.) (secondary material) is used to make “α-100iA” manufactured by FANUC. To obtain an adhesive strength test piece according to ASTM D-638.
The molding conditions were a cylinder temperature of 260 ° C., a mold temperature of 80 ° C., an injection speed of 30 mm / second, a holding pressure of 250 kg / cm ² (5 seconds), 150 kg / cm ² (5 seconds), and a cooling time of 8 seconds.
Evaluation measured the maximum tensile strength of the test piece shape | molded by the said method according to ASTMD-638. The central portion of the tension dumbbell formed by the above method becomes a heat-sealed joint surface.

[Fuel permeability measurement]
About the polyamide-type resin composition of the composition shown in Table 1 and Table 2, it measured by the cup method according to JIS-Z0208. As a test solution, a toluene: isooctane = 1: 1 solution (volume ratio) of a polyamide resin composition was prepared, and a mixed solution containing 90 vol% of the toluene: isooctane = 1: 1 solution (volume ratio) and 10 vol% of ethanol was prepared. Used to investigate fuel permeability in the gas phase.
The measurement was performed at 60 ° C. The fuel permeability of the resin composite part was determined by measuring the fuel permeability of this resin composition.

[Production of Resin Composition of Example 1]
As polyamide resin (a), 100 parts by weight of a polyamide resin (N-MXD6: nylon 6000 manufactured by Mitsubishi Gas Chemical Co., Ltd., number average molecular weight 15,000) obtained from 100 mol% of metaxylylenediamine and adipic acid, Acid-modified high-density polyethylene (manufactured by Mitsui Chemicals, Ltd. HE040, specific gravity: 0.95, melting point: 125 ° C., MFR: 1.6 g / 10 min (190 ° C.)) as polyolefin resin (b), 80 parts by weight, low As a melting point polyamide resin (c), 20 parts by weight of polyamide 12 (Grillamid L20G manufactured by EMS-CHEMIE) was kneaded, extruded and cut by a twin screw extruder (TEM35B) at a cylinder temperature of 270 ° C. to obtain pellets.

[Examples 2 to 4, Comparative Examples 1 to 5]
Pellets were produced in the same manner as in Example 1 except that the composition ratios described in Table 1 or Table 2 were used. The PA6 (nylon 6) used in Example 2 is Novamid 1007J manufactured by Mitsubishi Chemical Corporation, and the PA66 (nylon 66) used in Comparative Example 1 is Amilan CM3001-N manufactured by Toray Industries, Inc. It is.
In Tables 1 and 2, the units (a) to (c) are parts by weight, the unit of tensile adhesive strength is MPa, and the unit of fuel permeability is g · mm / m ² · day.

From Table 1, in Examples 1-4, it was judged that the fuel permeability of the polyamide-based resin composition was extremely low, and the fuel tank parts had excellent fuel permeability.
In addition, since the test piece molded according to ASTM has excellent adhesion strength between the polyamide resin composition and the polyethylene part, it is possible to obtain a fuel tank part with high reliability for safety required for automobile parts. I was able to judge.

According to Table 2, the polyamide resin compositions in Comparative Examples 1, 2, and 5 were excellent in fuel permeation resistance but low in adhesive strength, so that the fuel with high reliability required for safety required for automobile parts is shown. It was judged that tank parts could not be obtained.
Further, in Comparative Examples 3 and 4, although the adhesive strength between the polyamide resin composition and polyethylene is excellent, it can be determined that the fuel permeation resistance is poor and the volatilization amount of fuel in the fuel tank parts cannot be reduced. It was.

Claims (7)

Polyolefin resin (b) 50 to 100 parts by weight and melting point measured by DSC of less than 230 ° C. with respect to 100 parts by weight of polyamide resin (a) containing 30 mol% or more repeating units derived from aromatic monomers A polyamide resin composition comprising 2 to 30 parts by weight of a polyamide resin (c), wherein the polyamide resin (a) has a melting point measured by DSC of 230 ° C. or higher and 320 ° C. or lower, and a polyolefin. system resin (b) it is state, and are not modified with an acid anhydride, and the formed portion by using the polyamide resin composition (a), was formed by using the polyolefin resin (d) portion A polyamide resin composition for fuel tank parts, which is used for heat-sealing (B) . The polyamide resin (a) is obtained by polycondensing a mixed xylylenediamine comprising 55 to 100 mol% of metaxylylenediamine and 45 to 0 mol% of paraxylylenediamine and 45 to 0 mol% of adipic acid, Item 2. A polyamide resin composition according to Item 1. 3. The polyolefin resin (b) according to claim 1 or 2, wherein at least one selected from a linear low density polyethylene resin, a low density polyethylene resin, a high density polyethylene resin, and polypropylene is modified with an acid anhydride. Polyamide resin composition. The polyamide resin composition according to any one of claims 1 to 3, wherein the polyamide resin (c) having a melting point of less than 230 ° C as measured by DSC is polyamide 6 and / or polyamide 12. It has at least a part (A) formed using the polyamide resin composition according to any one of claims 1 to 4 and a part (B) formed using a polyolefin resin (d). These are fuel tank parts that are heat-sealed. The fuel tank component according to claim 5, which is formed by multicolor injection molding or insert molding using at least the polyamide resin composition according to any one of claims 1 to 4 and the polyolefin resin (d). The fuel tank component according to claim 5 or 6, wherein the polyolefin resin (d) is high-density polyethylene.