JPH11181279A - Polyamide resin composition for part for cooling water for engine, and molding product - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject composition excellent in mechanical characteristics, heat resistance, moldability and chemical resistance, and useful for parts for cooling water for an engine of an automobile, such as a radiator tank part and a water pump part by including a specific polyamide resin and an inorganic filler in a specified proportion. SOLUTION: This polyamide resin composition comprises (A) 100 pts.wt. polyamide resin consisting of (i) 75-50 mol.% hexamethyleneterephthalamide unit and (ii) 50-25 mol.% 18C aliphatic polyamide unit per amide group (preferably hexamethylenesebacamide or the like), and having 300-325 deg.C melting point, >=40 deg.C glass transition point under the saturated condition by water absorption obtained by a viscoelastic measurement, and one or more positions of peaks at >=80 deg.C in plural peak values of loss modulus and (B) 20-150 pts.wt. inorganic filler such as a glass fiber having 5-15 μm average fiber diameter.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polymer having excellent mechanical properties, heat resistance, moldability and chemical resistance, especially when exposed to high temperature contact conditions with antifreeze used for automobile engine cooling water. The present invention relates to a polyamide resin composition which has little material deterioration and excellent strength and dimensional stability.

More specifically, it contains a semi-aromatic polyamide unit having a specific structure and a high-grade polyamide unit having a specific range of amide group concentration and has high water resistance, and is used in an automobile engine room such as a radiator tank part or a water pump part. The present invention relates to a polyamide resin composition suitably used for parts used in contact with cooling water in the inside.

[0003]

2. Description of the Related Art Polyamide resins represented by nylon 6 and nylon 66 have excellent properties as engineering plastics, and are widely used in various industrial fields such as automobiles, electric and electronic devices.

In recent years, with respect to automobile parts, particularly resin parts used in an engine room, the temperature of engine cooling water rises due to higher performance and higher output of engine performance.
Further, there is an increasing demand for a material capable of maintaining functions such as high strength and dimensional stability even under severe use environment such as temperature rise in an engine room. In response to such advanced demands, nylon 6 and nylon 66 resins, which are used for general purposes, are reduced in rigidity due to water absorption, in particular, the dimensions are changed, and contact with high-temperature cooling water for a long time is required. There has been a problem that deterioration of the polymer material may be accelerated.

Recently, as a polyamide resin which can be used even in such a severe use environment, Japanese Patent Application Laid-Open No. 59-1554 is disclosed.
No. 26, JP-A-62-156130 and JP-A-3-7761 disclose a high melting point copolyamide resin containing terephthalic acid and / or isophthalic acid. These polyamide resins have a high melting point and at the same time suppress the water absorption by the introduction of aromatic dicarboxylic acid units, and can exhibit excellent mechanical properties and dimensional stability even under contact with antifreeze, but on the other hand, because of their high melting points When manufacturing a molded product by melt molding, foreign substances likely to be caused by gelation or carbonization of the polymer are likely to be mixed in, or gas burning and mold contamination likely to be caused by generation of volatile gas due to partial decomposition are likely to occur However, there has been a problem that the moldability is significantly impaired, and the stability is insufficient for producing a practical molded product with high productivity as it is.

[0006]

As described above, the prior art has high chemical resistance with little deterioration in material properties even under long-term contact with high-temperature automotive engine cooling water, and has high heat resistance. It has been difficult to obtain a polyamide resin-based material having excellent balance between toughness and moldability.

Therefore, the present invention has high chemical resistance with little deterioration in material properties even under long-term contact with high-temperature automotive engine cooling water, and has mechanical properties, heat resistance, moldability,
Obtains a polyamide resin composition having excellent dimensional stability and stability during melt retention, and particularly suitable for parts used in a car engine room under contact with cooling water, such as radiator tank parts and water pump parts. That is the task.

[0008]

Means for Solving the Problems That is, the present invention provides: "(A) 75 to 50 mol% of (a) hexamethylene terephthalamide units and (b) 50 to 25 mol% of aliphatic polyamide units having 8 or more carbon atoms (amide group concentration) per amide group. A polyamide resin composition for an engine cooling water system component, comprising 100 parts by weight of a polyamide resin having properties within the following ranges and (B) 20 to 150 parts by weight of an inorganic filler. 300 ° C. or more and less than 325 ° C. (b) The glass transition point at the time of saturated water absorption obtained from the viscoelasticity measurement is 40 ° C. or more, and at least one of the peak values of the plurality of loss elastic coefficients observed is 80 ° C.
Above ", 2. "(A ') 75 to 50 mol% of (a) hexamethylene terephthalamide unit and (b') the number of carbon atoms per one amide group (amide group concentration) is 8 or more, and it is defined as the following component (c). Aliphatic polyamide units 45 to 45
20 mol% (c) 100 parts by weight of a polyamide resin comprising 5 to 15 mol% of at least one structural unit selected from undecane amide units, dodecane amide units and caproamide units, and further having the following characteristics: And (B) a polyamide resin composition for an engine cooling water system component, comprising 20 to 150 parts by weight of an inorganic filler. (B) Melting point: 300 ° C. or more and less than 325 ° C. (b) A glass transition point at the time of saturated water absorption determined from viscoelasticity measurement of 40 ° C. or more, and at least one peak among a plurality of peak values of loss elastic modulus observed. At 80 ° C
that's all",

3. "(A) The polyamide resin composition for an engine cooling water system component according to the above 1 or 2, wherein the polyamide resin further satisfies the following requirements. (C) 130 ° C./300 hours under contact with an automobile antifreeze solution 85% retention of polymer relative viscosity after treatment
Above. ” 4. The polyamide resin composition for an engine cooling water component according to any one of the above items 1 to 3, wherein the aliphatic polyamide unit of the component (b) or the component (b ′) is hexamethylene sebacamide. 5. The polyamide resin composition for an engine cooling water system component according to any one of the above items 1 to 3, wherein the aliphatic polyamide unit of the component (b) or the component (c) is undecaneamide or dodecaneamide. 6. The polyamide resin composition for an engine cooling water system component according to the above 2 or 3, wherein the polyamide unit of the component (c) is a caproamide unit. 4. The polyamide resin composition for an engine cooling water system component according to the above item 2 or 3, wherein the polyamide unit of the component (c) is a dodecaneamide unit.

[0010] 8. (2) or (3) wherein the aliphatic polyamide unit of the component (b ′) is hexamethylene sebacamide and the polyamide unit of the component (c) is a caproamide unit.
The polyamide resin composition for an engine cooling water system component according to the above. 9. "The polyamide resin composition for an engine cooling water component according to the above item 2 or 3, wherein the aliphatic polyamide unit of the component (b ') is hexamethylene sebacamide and the polyamide unit of the component (c) is a dodecaneamide unit." , 10. "(1) above wherein the inorganic filler is glass fiber
9. The polyamide resin composition for an engine cooling water system component according to any one of 9. 10. "(B) The polyamide resin composition for an engine cooling water system component according to the above item 9, wherein the amount of glass fiber added is in the range of 40 to 100 parts by weight relative to 100 parts by weight of the polyamide resin (A ')". 12. "The above 1 to 11 wherein the engine is a car engine
Any of the polyamide resin compositions for cooling water-based components. 13. It is intended to provide an "engine cooling water system component obtained by melt-molding the polyamide resin described in any one of the above 1 to 12."

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, the first polyamide resin (A) specified in claim 1 includes (a) 75 to 50 mol% of hexamethylene terephthalamide unit and (b) one amide group. Aliphatic polyamide unit having 8 or more carbon atoms (amide group concentration) 50 to 25 mol%
The second polyamide resin (A ') specified in claim 2, wherein (a) 75 to 50 mol% of hexamethylene terephthalamide units, (b') the number of carbon atoms per amide group (amide group) (Concentration) of at least 8 to 45 mol% of aliphatic polyamide units and (c) 5 to 15 mol% of at least one structural unit selected from undecanamide units, dodecaneamide units and caproamide units. used.

The (a) hexamethylene terephthalamide unit constituting the polyamide resin (A) or (A ') is a unit synthesized from hexamethylene diamine and a derivative of terephthalic acid or an ester or acid halide thereof.

Specific examples of the raw material for providing an aliphatic polyamide unit having 8 or more carbon atoms (amide group concentration) per amide group of component (b) include hexamethylene diammonium sebacate and hexamethylene diammonium. Decanoate, hexamethylene diammonium undecanoate, hexamethylene diammonium dodecanoate, 12-aminododecanoic acid, ω-laurolactam, 1
1-aminoundecanoic acid and the like can be mentioned.
As specific examples of the component (b ′), from the specific examples of the component (b), 2-aminododecanoic acid, ω-laurolactam,
Compounds other than 11-aminoundecanoic acid can be mentioned. The component (c) is a unit derived from a raw material such as 12-aminododecanoic acid, ω-laurolactam, 11-aminoundecanoic acid, ε-aminocaproic acid, and ε-caprolactam.

The polyamide constituents are (a) and (b)
In the case of a two-component system comprising the components, the components (a) and (b) are added in proportions of 75 to 50 mol% and 50 to 25 mol%, respectively, preferably 70 to 55 mol% and 45 to 30 mol%, respectively.
In the case of a three-component system comprising the components (a), (b ') and (c), the components (a), (b') and (c) are 75 to 50, 45 to 45, respectively. 20 and 5-1
5 mol%, preferably 70 to 55, 40 to 3 respectively
It is necessary in the present invention that the copolymer be contained in a proportion of 0, 5 to 10 mol%.

This is because a copolymerized polyamide obtained by polymerizing the above specific copolymerization component in a very limited copolymerization ratio and having a specific melting point and a viscoelastic behavior upon water absorption has a high chemical resistance ( (Especially antifreeze liquid resistance), and when used as automotive engine cooling water system parts, polymer deterioration is small even under long-term contact with antifreeze at high temperature,
In addition, it is possible to exhibit favorable performance such as excellent balance of strength, heat resistance, and moldability.

If the copolymerization amount of the component (a) is larger than the above range, the melting point of the polyamide resin to be formed becomes high, and the molding processability is impaired, for example, deterioration at the time of melting at the time of molding process becomes unfavorable. Conversely, if the amount is less than the above range, the mechanical strength decreases, which is not preferable. If the copolymerization amount of the component (b) or the component (b ') is larger than the above range, the melting point is lowered, and the required heat resistance cannot be maintained. Increase
It is not preferable because the strength decreases under long-term contact with antifreeze. In the case of a three-component system, if the copolymerization amount of the component (c) is larger than the above range, the melting point also decreases and the required heat resistance cannot be maintained, which is not preferable. It is not preferable because the fluidity of the resulting polyamide resin is reduced and the moldability is impaired.

Although the degree of polymerization of the polyamide resin of the present invention is not particularly limited, the relative viscosity measured at 25 ° C. in a 1% concentrated sulfuric acid solution from the viewpoint of mechanical properties and moldability is usually 1.5-5.0, preferably 1.8-
Those having a value in the range of 3.5, particularly preferably in the range of 2.0 to 2.8 are suitable. In the polyamide resin (A) of the present invention, an amide component not defined in (a) and (b) is used.
In the polyamide resin (A '), (a)
An amide component not defined by (b ') and (c) may be contained in a small amount, for example, 5 mol% or less, as long as the effects of the present invention are not impaired.

Although the method for producing the polyamide resin of the present invention is not particularly limited, ordinary pressure melt polymerization, for example, hexamethylene diammonium terephthalate (6T salt)
And hexamethylene diammonium sebacate (610
Salt) and ε-caprolactam in an aqueous solution of 20-6.
A conventional melt polymerization method in which a heat reaction is performed under a steam pressure of 0 kg / cm ² and then melt polymerization is performed while releasing water in the system, or a raw material aqueous solution is heated at 200 to 350 ° C. to form a prepolymer once. Is further solid-phase polymerized at a temperature equal to or lower than the melting point, or a method of increasing the degree of polymerization with a melt extruder.

The polyamide resin of the present invention may contain additives such as a viscosity modifier, a pigment, an anti-coloring agent and a heat-resistant agent, as long as the properties are not impaired.

The inorganic filler used as the component (B) of the polyamide resin composition of the present invention may be a fibrous / non-fibrous inorganic reinforcing material. Fibrous filler such as fiber, carbon fiber, potassium whisker, titanate whisker, zinc oxide whisker, aluminum borate whisker, aramid fiber, alumina fiber, silicon carbide fiber, ceramic fiber, asbestos fiber, masonry fiber, metal fiber, etc., walasteinite, zeolite , Silicates such as sericite, kaolin, mica, clay, pyrophyllite, bentonite, asbestos, talc, alumina silicate, metal compounds such as alumina, silicon oxide, magnesium oxide, zirconium oxide, titanium oxide, iron oxide, and calcium carbonate , Magnesium carbonate, dolomite and other carbonates, Calcium acid, sulfates such as barium sulfate, magnesium hydroxide, calcium hydroxide,
Examples include hydroxides such as aluminum hydroxide, glass beads, ceramic beads, non-fibrous fillers such as boron nitride, silicon carbide and silica, which may be hollow, and furthermore, two kinds of these fillers. These can be used together. Among these fillers, glass fibers are particularly preferably used in the present invention.
The glass fibers are glass fibers having an average fiber diameter of 5 to 15 μm, and the fiber length is not particularly limited. Usually, a glass fiber having a strand length of 3 mm having a high extrusion kneading workability can be used. However, a glass fiber having a strand length of 1 mm or more and a glass fiber having a fiber length of 20 to 500 μm can also be used as a raw material as a mixture. When two or more types of glass fibers having different strand lengths are used in combination, it is also a preferable method to use glass fibers having different average diameters of 2 μm or more.

The content of the filler in the resin composition of the present invention is in the range of 40 to 100 parts by weight, more preferably 45 to 80 parts by weight, per 100 parts by weight of the nylon resin.
In addition, when these fillers are pre-treated with a coupling agent such as an isocyanate compound, an organic silane compound, an organic titanate compound, an organic borane compound, or an epoxy compound, more excellent mechanical strength can be obtained. Preferred in meaning.

The addition of an alkoxysilane having at least one functional group selected from an epoxy group, an amino group, an isocyanate group, a hydroxyl group, a mercapto group and a ureide group to the nylon resin composition of the present invention is performed by mechanical Strength,
It is effective in improving toughness and the like. Specific examples of such compounds include γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane,
epoxy group-containing alkoxysilane compounds such as β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane, γ
-Mercapto group-containing alkoxysilane compounds such as mercaptopropyltriethoxysilane; ureide group-containing such as γ-ureidopropyltriethoxysilane, γ-ureidopropyltrimethoxysilane, γ- (2-ureidoethyl) aminopropyltrimethoxysilane Alkoxysilane compound, γ-isocyanatopropyltriethoxysilane, γ-isocyanatopropyltrimethoxysilane, γ-isocyanatopropylmethyldimethoxysilane, γ-isocyanatopropylmethyldiethoxysilane, γ-isocyanatopropylethyldimethoxysilane, isocyanato group-containing alkoxysilane compounds such as γ-isocyanatopropylethyldiethoxysilane and γ-isocyanatopropyltrichlorosilane;
Amino-containing alkoxysilane compounds such as -aminoethyl) aminopropylmethyldimethoxysilane, γ- (2-aminoethyl) aminopropyltrimethoxysilane, γ-aminopropyltrimethoxysilane, γ-hydroxypropyltrimethoxysilane, γ- Examples include a hydroxyl group-containing alkoxysilane compound such as hydroxypropyltriethoxysilane.

Further, the nylon resin composition of the present invention includes a nucleating agent such as talc, kaolin, an organic phosphorus compound, polyetheretherketone, a coloring inhibitor such as hypophosphite, a hindered phenol, a hindered amine and the like. Additives such as antioxidants, heat stabilizers, lubricants, UV inhibitors, colorants, etc. can be added.

The method for preparing the nylon resin composition of the present invention is not limited to a specific method. As a specific and efficient example, a mixture of a raw material such as a nylon resin and a filler such as glass fiber is mixed with a monoaxial or biaxial mixture. It is supplied to a known melt kneader such as an extruder, a Banbury mixer, a kneader and a mixing roll, and is supplied according to the melting point of the nylon resin used.
A method of melting and kneading at a temperature of 50 to 330 ° C. can be used.

The polyamide resin composition obtained by the present invention is excellent in mechanical properties, heat resistance, moldability, dimensional stability, and chemical resistance, and is used for radiator tanks such as automotive engine cooling water system parts, particularly, radiator tank tops and bases. Suitable for parts used in the automotive engine room under contact with cooling water, such as parts, coolant reserve tanks, water pipes, water pump housings, water pump impellers, and water pump parts such as valves. The molded product obtained by melt-molding the product is of high practical value.

[0026]

EXAMPLES The effects of the present invention will be further described with reference to examples, but the present invention is not limited to these examples.

The properties described in the examples and comparative examples were measured by the following methods. Melting point: Using an RDC220 type differential operation calorimeter manufactured by Ko Denshi Kogyo Co., Ltd., the temperature was once increased at a heating rate of 40 ° C./min, and maintained at an endothermic peak temperature plus 20 ° C. for 5 minutes, and then at 20 ° C./min. 20 minutes after cooling down to 100 ° C
The peak value measured at a heating rate of ° C./min was defined as the melting point.

Viscoelastic behavior: A polyamide resin sample was melt-pressed to form a sheet having a thickness of about 0.2 mm, and a 2 × 50 mm strip test piece was cut out from the sheet.
Toyo Baldwin's Leo Vibron DDV-II-
The measurement was performed using EA under the conditions of a frequency of 110 Hz and a heating rate of 2 ° C./min. The peak temperature of the loss elastic modulus corresponding to α-dispersion was defined as the glass transition point. In addition, the peak temperature of the highest temperature of the loss elastic modulus observed by splitting specifically at the time of water absorption is shown as the high temperature side peak at the time of water absorption.

Tensile strength: According to ASTM D638,
130 in an initial and 1: 1 mixture of car antifreeze and water
The tensile strength after the treatment at 1000C / 1000 hours was measured. Flexural modulus: ASTM D790 Antifreeze resistance of polymer: 130 ° C./30 at the initial stage of the tensile test specimen and in a 1: 1 mixture of automobile antifreeze and water
After the treatment for 0 hour, the relative viscosity of sulfuric acid was measured, and the retention was used as an index of the antifreeze resistance of the polymer.

REFERENCE EXAMPLE 1 Hexamethylene diammonium terephthalate (6T salt), hexamethylene diphthalate prepared to have 65 mol% of hexamethylene terephthalamide unit, 30 mol% of hexamethylene sebacamide unit and 5 mol% of dodecaneamide unit Mixed aqueous solution of ammonium sebacate (610 salt) and ω laurolactam (solid raw material concentration 60% by weight)
Was charged into a pressure polymerization vessel, and the temperature was increased while stirring.
After reacting at kg / cm2 for 3.5 hours, the reaction mixture was discharged from the lower outlet of the polymerization vessel and collected. The relative viscosity (1% concentration) of the sulfuric acid solution of the obtained polyamide prepolymer was 1.4.
It was 5. This was subjected to solid-phase polymerization at 220 ° C. for 10 hours under vacuum to evaluate its properties as a polyamide having a relative viscosity of 2.4. The properties were as shown in Table 1. This polyamide resin was used in Examples described later.

Comparative Reference Example 1 Polymerization was carried out in exactly the same manner as in Example 1 except that the raw material hexamethylene sebacate was changed to the same amount of hexamethylene adipate. The properties of the polyamide obtained here are as shown in Table 1, and this was used in Comparative Examples described later.

COMPARATIVE REFERENCE EXAMPLE 2 Except that the raw material mixing ratio was changed so that the composition of the polyamide to be formed was 25 mol% of hexamethylene terephthalamide unit, 50 mol% of hexamethylene sebacamide unit and 25 mol% of caproamide unit. The polymerization was carried out exactly as in Example 1. The properties of the polyamide obtained here are as shown in Table 1, and this was used in Comparative Examples described later.

Reference Examples 2 to 4 Polymerization was carried out in exactly the same manner as in Reference Example 1, except that the mixing ratio of the raw materials was changed so that the resulting polyamide resin had the composition shown in Table 1. The properties of the obtained polyamide are as shown in Table 1, which was used in Examples described later.

Examples 1 to 6 and Comparative Examples 1 and 2 After the polyamide resin and the glass fiber obtained in the reference example described above were dry-blended at the compounding ratio shown in Table 1, they were mixed with each other.
Supplied to the hopper of mmφ single screw extruder, cylinder temperature 305-330 ° C, screw rotation speed 100rpm
Was melt-kneaded under the conditions described above to obtain a glass fiber reinforced composition. This composition was injection-molded to obtain various test pieces, and the properties were evaluated. The results are summarized in Table 1. Each of the compositions of the present invention was a composition having excellent properties such as high antifreeze resistance.

[0035]

[Table 1]

[0036]

The polyamide resin composition obtained by the present invention has excellent mechanical properties, heat resistance, moldability, dimensional stability, and chemical resistance, and is suitable for use in automotive engine cooling water system parts, particularly for radiator tank tops and bases. Radiator tank parts, coolant reserve tank, water pipe, water pump housing, water pump impeller,
A molded product obtained by melt-molding the composition, which is suitably used for parts used in a car engine room under contact with cooling water, such as a water pump component such as a valve, is of high practical value. .

Claims (13)

[Claims] 1. An aliphatic polyamide unit having (A) (a) 75 to 50 mol% of hexamethylene terephthalamide units and (b) an aliphatic polyamide unit having 8 or more carbon atoms (amide group concentration) per amide group. A polyamide resin composition for an engine cooling water system component, comprising 100 parts by weight of a polyamide resin having the following characteristics in terms of mole% and (B) 20 to 150 parts by weight of an inorganic filler. (B) Melting point: 300 ° C. or more and less than 325 ° C. (b) A glass transition point at the time of saturated water absorption determined from viscoelasticity measurement of 40 ° C. or more, and at least one peak among a plurality of peak values of loss elastic modulus observed. At 80 ° C
that's all 2. (A ') 75 to 50 mol% of (a) hexamethylene terephthalamide unit and (b') the number of carbon atoms per one amide group (amide group concentration) is 8 or more;
And 45 to 20 mol% of an aliphatic polyamide unit which is not defined in the following component (c), and (c) 5 to 15 mol% of at least one structural unit selected from undecane amide units, dodecane amide units and caproamide units,
Further, the polyamide resin 10 whose properties are within the following ranges:
A polyamide resin composition for an engine cooling water system component comprising 0 parts by weight and (B) 20 to 150 parts by weight of an inorganic filler. (B) Melting point: 300 ° C. or more and less than 325 ° C. (b) A glass transition point at the time of saturated water absorption determined from viscoelasticity measurement of 40 ° C. or more, and at least one peak among a plurality of peak values of loss elastic modulus observed. At 80 ° C
that's all 3. The polyamide resin (A) or (A ′) further satisfies the following requirements.
The polyamide resin composition for an engine cooling water system component according to the above. (C) 85% retention of relative viscosity of polymer when treated at 130 ° C./300 hours under contact with automobile antifreeze
that's all 4. The polyamide resin composition according to claim 1, wherein the aliphatic polyamide unit of the component (b) or the component (b ′) is hexamethylene sebacamide. 5. The polyamide resin composition for an engine cooling water system component according to claim 1, wherein the aliphatic polyamide unit of the component (b) or the component (c) is undecaneamide or dodecaneamide. 6. The polyamide resin composition for an engine cooling water system component according to claim 2, wherein the polyamide unit of the component (c) is a caproamide unit. 7. The polyamide resin composition for an engine cooling water system component according to claim 2, wherein the polyamide unit of the component (c) is a dodecaneamide unit. 8. The polyamide resin for an engine cooling water system component according to claim 2, wherein the aliphatic polyamide unit of the component (b ′) is hexamethylene sebacamide, and the polyamide unit of the component (c) is a caproamide unit. Composition. 9. The component (b ′) wherein the aliphatic polyamide unit is hexamethylene sebacamide and the component (c) the polyamide unit is a dodecaneamide unit.
The polyamide resin composition for an engine cooling water system component according to the above. 10. The polyamide resin composition for an engine cooling water system component according to claim 1, wherein the inorganic filler (B) is glass fiber. (B) the amount of glass fiber added is:
4 parts per 100 parts by weight of the polyamide resin (A ')
The polyamide resin composition for an engine cooling water system component according to claim 9, which is in a range of 0 to 100 parts by weight. 12. The polyamide resin composition for a cooling water system component according to claim 1, wherein the engine is an automobile engine. 13. An engine cooling water system component obtained by melt-molding the polyamide resin according to claim 1.