JPH11286606A - Polyamide resin composition for component of cooling water system of engine and molding made therefrom - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a composition excellent in mechanical properties, heat resistance, moldability, dimensional stability, and chemical resistance and desirable for use for a component of the cooling water system of an automobile engine by mixing two specified polyamide resins with an inorganic filler in a specified ratio. SOLUTION: 20-150 pts.wt. inorganic filler is mixed with 100 pts.wt. polyamide resin comprising 99-50 wt.% polyamide resin comprising 75-50 mol.% hexamethylene terephthalamide units and 25-50 mol.% units selected among undecanoamide units and dodecanoamide units, having a melting point of 300 to below 325 deg.C and having a plurality of peak values of loss elastic moduli at least one of which stands at a position of 80 deg.C or higher and 1-50 wt.% polyhexamethyleneadipamide and/or polycapramide. The inorganic filler is desirably a glass fiber.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

More specifically, it has high water resistance by mainly containing a semi-aromatic polyamide unit having a specific structure and a high polyamide unit having a specific range of amide group concentration, and has high water resistance, such as a radiator tank part and a water pump part. The present invention relates to a polyamide resin composition suitably used for parts used in a car engine room under contact with cooling water.

[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 a severe use environment such as a temperature rise in an engine room. In response to such advanced demands, nylon 6 and nylon 66 resins, which are used for general purposes, change their dimensions due to reduced rigidity due to water absorption, and contact with high-temperature engine cooling water for a long time. Therefore, there is a problem that deterioration of the polymer material is 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 used as engine cooling water. There are advantages.

[0006]

However, due to its high melting point, when producing a molded article by a melt molding method, foreign substances presumed to be caused by gelling or carbonization of a polymer are liable to be mixed in, or volatile gas due to partial decomposition is produced. Molding processability is significantly impaired, such as gas burning and mold contamination likely to occur due to the occurrence, and it is said that the stability for producing practical molded products with good productivity is insufficient as it is. There was a problem.

As described above, according to the conventional technology, the material properties are less reduced even under long-term contact with the high-temperature automotive engine cooling water, the chemical resistance is high, and the heat resistance is high.
It has been difficult to obtain a polyamide resin material having excellent balance between toughness and moldability.

Accordingly, 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, 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.

[0009]

Means for Solving the Problems To solve the above problems, the present invention provides: "(A) 75 to 50 mol% of (a) hexamethylene terephthalamide unit and (b) 25 to 50 mol% of at least one structural unit selected from undecaneamide unit and dodecaneamide unit, B) Polyamide resin 99 that satisfies the properties of (b)
It is characterized by comprising 100 parts by weight of a polyamide resin comprising 50% by weight and (B) 1 to 50% by weight of polyhexamethylene adipamide and / or polycaproamide, and (C) 20 to 150 parts by weight of an inorganic filler. Polyamide resin composition for engine cooling water system components. (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
Above ", 2. "(A) (a) 75 to 50 mol% of hexamethylene terephthalamide unit, (b) 20 to 45 mol% of at least one structural unit selected from undecanamide unit and dodecane amide unit, and (c) hexamethylene A polyamide resin 9 comprising isophthalamide units of 5 to 25 mol% and further satisfying the following characteristics (a) and (b):
100 parts by weight of a polyamide resin comprising 9 to 50% by weight and (B) 1 to 50% by weight of polyhexamethylene adipamide and / or polycaproamide; and (C) 20 to 150 parts by weight of an inorganic filler. A polyamide resin composition for an engine cooling water system component, characterized in that: (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
Above ", 3. (3) The polyamide resin composition for an engine cooling water system component according to the above (1) or (2), wherein the polyamide resin matrix further satisfies the following characteristics (c). 75% retention of polymer relative viscosity
Above. ” 4. The polyamide resin composition for an engine cooling water system component according to any one of the above 1 to 3, wherein the component (B) is hexamethylene adipamide. "The above 1 to 3, wherein the component (B) is polycaproamide.
5. A polyamide resin composition for an engine cooling water system component according to any one of the above, "(C) The inorganic filler is glass fiber.
6. The polyamide resin composition for an engine cooling water component according to any one of 5. 7. The polyamide resin composition for an engine cooling water system component according to any one of claims 1 to 6, wherein the engine is an automobile engine. An engine cooling water system component obtained by melt-molding the polyamide resin according to any one of claims 1 to 7.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, as the polyamide resin (A), at least one selected from (a) 75 to 50 mol% of hexamethylene terephthalamide unit and (b) undecaneamide unit and dodecaneamide unit is used. Or (a) hexamethylene terephthalamide units of from 75 to 5 mol%
0 mol%, (b) 20 to 45 mol% of at least one structural unit selected from undecane amide units and dodecane amide units, and (c) 5 to 25 mol% of hexamethylene isophthalamide units are used. You.

The (a) hexamethylene terephthalamide unit constituting the polyamide resin (A) is a unit synthesized from hexamethylene diamine and a derivative of terephthalic acid or an ester or acid halide thereof. (B)
Specific examples of the raw material that gives the amide unit of the component include 12
-Aminododecanoic acid, ω-laurolactam, 11-aminoundecanoic acid, and the like. (C) The hexamethylene isophthalamide unit is a unit synthesized from hexamethylene diamine and a derivative such as isophthalic acid or its ester or acid halide.

The polyamide resin (A) contains the components (a) and (b) in the proportions of 75 to 50 and 25 to 50 mol%, respectively, preferably in the proportions of 70 to 55 and 30 to 45 mol%, respectively. Or the components (a), (b) and (c) are respectively 75 to 50, 20 to 45 and 5 to 25
Mol%, preferably 70 to 55, 20 to 4 respectively.
It must be a copolymer containing 0, 5 to 20 mol%.

The reason is that by using a copolymerized polyamide which is obtained by polymerizing the above-mentioned specific copolymerization component in a very limited copolymerization ratio and has a specific melting point and viscoelastic behavior upon water absorption, it is possible to obtain a copolymer having a high resistance to water. It has chemical properties (especially antifreeze liquid resistance), and when used as a cooling water system part for automobile engines, polymer deterioration is small even under long-term contact with antifreeze at high temperatures, and strength, heat resistance, and moldability are low. This is because preferable performances such as excellent balance can be exhibited.

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 (for example, more than 325 ° C.), and the deterioration at the time of melting becomes conspicuous, so that the probability of foreign substances entering the molded article increases. It is not preferable because the molding processability is impaired, for example, when a molded article is burned or gas is burned. Conversely, when the amount is less than the above range, the viscoelastic properties at the time of water absorption are unfavorably reduced. If the copolymerization amount of the component (b) is larger than the above range, the melting point is lowered, and the required heat resistance cannot be maintained. Therefore, if it is less than the above range, water absorption increases, and It is not preferable because the rigidity is reduced.
In the case where the component (c) is introduced, if the copolymerization amount is larger than the above range, it is preferable because the molded product suffers from gas burning due to an increase in melt viscosity and the solidification during molding is significantly slowed, thereby impairing moldability. Absent.

The degree of polymerization of the polyamide resin (A) of the present invention is not particularly limited, but the relative viscosity measured at 25 ° C. in a 1% concentrated sulfuric acid solution from the viewpoint of mechanical properties and moldability. But usually 1.5 to 5.0, preferably 1.
Those having a range of from 8 to 3.5, particularly preferably from 2.0 to 2.8, are suitable. Further, in the polyamide resin (A) of the present invention, amide components not defined in (a), (b) and (c) are used as long as the desired properties of the present invention are not impaired.
A small amount, for example, 5 mol% or less can be contained.

The method for producing the polyamide resin (A) of the present invention is not particularly limited, but may be a conventional pressure melt polymerization, for example, hexamethylene diammonium terephthalate (6).
T salt) and a mixture of ω-laurolactam and water from 20 to
A normal melt polymerization method in which a heat reaction is performed under a steam pressure of 60 kg / cm ² and then melt polymerization is performed while releasing water in the system, or a raw material mixture is heated at 200 to 350 ° C. to form a prepolymer once. And a method of increasing the degree of polymerization of the prepolymer by a melt extruder.

The polyamide resin (A) of the present invention may contain additives such as commonly used viscosity modifiers, pigments such as monocarboxylic acids, polycarboxylic acids, monoamines and polyamines, as long as their properties are not impaired. , Phosphorous acid, metal phosphites, hypophosphorous acid, metal hypophosphites, coloring inhibitors, heat stabilizers and the like may be added.

The polyhexamethylene adipamide (nylon 66) and polycaproamide (nylon 6) used as the component (B) in the present invention are measured at 25 ° C. in a 1% concentrated sulfuric acid solution synthesized by an ordinary method. While those having a relative viscosity of 2.0 to 5.0 can be used, the relative viscosity is preferably 2.1 to 4.5, and particularly preferably 2.2 to 3.5.
Are preferred. Further, the nylon 66 and the nylon 6 include a copolymer containing a small amount (for example, 10% by weight or less) of another polyamide-forming component. In the present invention, the polyamide of the component (B) contributes to the improvement of the fluidity and the molding cycle at the time of molding, and the amount of the polyamide is 1% by weight based on the total of the components (A) and (B). %, The effect is insufficient. On the other hand, if the addition amount exceeds 50% by weight, it becomes difficult to maintain rigidity in a high-humidity atmosphere, which is the main object of the present invention. is there.

The inorganic filler used as the component (C) 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, potassium oxide 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 , Sericite, kaolin, mica, clay, pyrophyllite, bentonite, asbestos, talc, silicates such as alumina silicate, alumina, silicon oxide, magnesium oxide, zirconium oxide, titanium oxide, metal compounds such as iron oxide, 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. It is also possible to use more than one kind in combination.

Among these fillers, glass fibers are particularly preferably used in the present invention. Glass fibers are glass fibers having an average fiber length of 5 to 15 μm,
The fiber length is not particularly limited. Usually, a glass fiber with a strand length of 3 mm, which is highly extrudable and kneading workable, can be used.
Glass fibers of 0 to 500 μm can also be used as raw materials 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 20 to 150 with respect to 100 parts by weight of the total amount of the polyamide resin.
Parts by weight, preferably in the range of 40 to 100 parts by weight,
The range is more preferably from 45 to 80 parts by weight. In addition, these fillers are isocyanate compounds, acrylic compounds,
Pretreatment with a coupling agent such as an organic silane-based compound, an organic titanate-based compound, an organic borane-based compound, or an epoxy compound before use is preferable in terms of obtaining more excellent mechanical strength.

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 It is effective in improving mechanical strength, toughness, and the like. Specific examples of such compounds include epoxy group-containing alkoxysilane compounds such as γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, and β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane. , Γ-mercaptopropyltrimethoxysilane, mercapto group-containing alkoxysilane compounds such as γ-mercaptopropyltriethoxysilane, γ-ureidopropyltriethoxysilane, γ-ureidopropyltrimethoxysilane, γ- (2-ureidoethyl) amino Ureido group-containing alkoxysilane compounds such as propyltrimethoxysilane, γ-isocyanatopropyltriethoxysilane, γ-isocyanatopropyltrimethoxysilane, γ-isocyanatopropylmethyldimethoxysilane, γ- Socia isocyanatopropyl methyldiethoxysilane, .gamma.-isocyanatopropyl ethyl dimethoxy silane, .gamma.-isocyanatopropyl ethyldiethoxysilane, isocyanato group-containing alkoxysilane compounds such as .gamma.-isocyanatopropyl trichlorosilane, .gamma. (2
Amino-containing alkoxysilane compounds such as -aminoethyl) aminopropylmethyldimethoxysilane, γ- (2-aminoethyl) aminopropyltrimethoxysilane, γ-aminopropyltrimethoxysilane, γ-hydroxypropyltrimethoxysilane, γ- Hydroxy group-containing alkoxysilane compounds such as hydroxypropyltriethoxysilane and the like.

Further, the nylon resin composition of the present invention includes a crystal 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, and colorants 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 90 to 340 ° 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 Hereinafter, the effects of the present invention will be further described with reference to examples, but the present invention is not limited to these examples. In addition, various characteristics described in the examples and comparative examples were measured by the following methods.

Melting point: RD manufactured by Seiko Electronics Co., Ltd.
Using a C220 type differential working calorimeter, the temperature was once increased at a heating rate of 40 ° C./min, maintained at an endothermic peak temperature plus 20 ° C. for 5 minutes, and then lowered to 100 ° C. at a rate of 20 ° C./min. Thereafter, the peak value measured at a heating rate of 20 ° C./min was defined as the melting point.

Viscoelastic behavior: A polyamide resin sample is melt-pressed to form a sheet having a thickness of about 0.2 mm, and a 2 × 50 mm strip test piece is 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. Also, the highest temperature of the loss elastic coefficient 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: The flexural modulus was measured according to ASTM D790.

Antifreeze resistance of the polymer: The initial of the above tensile test piece and 1: 1 mixture of automobile antifreeze and water
The relative viscosity of the sulfuric acid solution after treatment at 30 ° C. for 300 hours 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) adjusted to 65 mol% of hexamethylene terephthalamide units and 35 mol% of dodecaneamide units,
A mixture of ω-laurolactam and water (solid raw material concentration 6
(0% by weight) was charged into a pressure polymerization reactor, the temperature was increased with stirring, and the mixture was reacted at a steam pressure of 35 kg / cm ² for 3.5 hours, and then the reaction mixture was discharged from the lower discharge port of the polymerization reactor and collected. Relative viscosity of sulfuric acid solution of the obtained polyamide prepolymer (1%
Concentration) was 1.40. 220 ° C under vacuum
The properties were evaluated as a polyamide having a relative viscosity of 2.3 by solid-phase polymerization for / 10 hours, and 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 Reference Example 1 except that the raw material of the copolymerized polyamide described in Reference Example 1 was changed to hexamethylenediammonium adipate. The properties of the polyamide obtained here are as shown in Table 1, which was used in Comparative Example 1 described later.

Comparative Reference Example 2 Polymerization was carried out in exactly the same manner as in Reference Example 1 except that the raw material of the copolymerized polyamide described in Reference Example 1 was changed to hexamethylene diammonium isophthalate. The properties of the polyamide obtained here are as shown in Table 1, which was used in Comparative Example 2 described later.

Reference Examples 2 to 4 Polymerization was carried out in exactly the same manner as in Reference Example 1, except 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 7 and Comparative Examples 1 and 2 After the polyamide resin and the glass fibers obtained in the reference examples described above were dry-blended at the compounding ratio shown in Table 1, 40 m
m to the hopper of the single-screw extruder, cylinder temperature 30
Melt kneading was performed at 5 to 330 ° C. and a screw rotation speed of 100 rpm 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. On the other hand, the composition of Comparative Example 1 was inferior in antifreeze resistance, and the composition of Comparative Example 2 was remarkably slow in solidification at the time of injection molding, was insufficient in moldability, and was of low practical value.

[0036]

[Table 1]

[0037]

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,
It is suitably used for parts used under contact with cooling water in an automobile engine room such as a water pump part such as a valve, and a molded product obtained by melt-molding the composition has a high practical value. is there.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI F01P 11/04 F01P 11/04 B F28F 21/06 F28F 21/06

Claims (8)

[Claims] 1. A composition comprising (A) 75 to 50 mol% of (a) hexamethylene terephthalamide unit and (b) 25 to 50 mol% of at least one structural unit selected from undecaneamide unit and dodecaneamide unit. And 100% by weight of a polyamide resin comprising 99 to 50% by weight of a polyamide resin satisfying the following characteristics (A) and (B) and 1 to 50% by weight of (B) polyhexamethylene adipamide and / or polycaproamide. And (C) 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, (b) 20 to 45 mol% of at least one structural unit selected from undecaneamide unit and dodecaneamide unit, and c) 99 to 50% by weight of a polyamide resin which comprises 5 to 25 mol% of hexamethylene isophthalamide units and satisfies the following characteristics (A) and (B); and (B) polyhexamethylene adipamide and / or polycarbonate A polyamide resin composition for an engine cooling water system component, comprising 100 parts by weight of a polyamide resin comprising 1 to 50% by weight of proamide and (C) 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 composition for an engine cooling water system component according to claim 1, wherein the polyamide resin matrix further satisfies the following property (c). (C) The retention of the relative viscosity of the polymer when subjected to a treatment at 130 ° C./300 hours under contact with an automobile antifreeze solution is 75%
that's all 4. The polyamide resin composition for an engine cooling water system component according to claim 1, wherein the component (B) is hexamethylene adipamide. 5. The polyamide resin composition according to claim 1, wherein the component (B) is polycaproamide. 6. The polyamide resin composition for an engine cooling water system component according to claim 1, wherein the inorganic filler (C) is glass fiber. 7. The polyamide resin composition according to claim 1, wherein the engine is an automobile engine. 8. An engine cooling water system part obtained by melt-molding the polyamide resin according to claim 1.