JPH0598152A - Polyamide resin composition - Google Patents

Abstract

PURPOSE:To provide the subject composition excellent in thermal resistance, dimensional accuracy, moldability and dimensional stability and useful for automotive parts, etc., by compounding a specific crystalline copolyamide, a specific aliphatic polyamide, a specific polyolefin elastomer, etc., in a specified ratio. CONSTITUTION:The objective composition comprises (A) 98-30wt.% of a crystalline copolyamide comprising (i) 80-20wt.% of hexamethylene terephthalamide units and (ii) 20-80wt.% of hexamethylene adipamide units or caproamide units, (B) 0.5-50wt.% of an aliphatic polyamide having a methylene group number (amide group concentration) of >=5.5 per the amide group, and (C) 1.5-60wt.% of one or more kinds of elastomers components selected from a polyolefin elastomer and a dienic elastomer.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a polyamide resin composition having excellent mechanical properties, heat resistance and moldability, and particularly excellent toughness, heat resistance and dimensional accuracy.

More specifically, it has excellent toughness represented by elongation at break, and high heat resistance, high toughness, and high dimensional stability with little decrease in toughness even after long-term exposure to a high temperature environment. Concerning the polyamide resin composition having, a polyamide resin composition suitable for use in applications requiring the toughness of thin-walled parts such as automobile parts, electric parts, electric parts, particularly various electric parts in an automobile engine room. Regarding

[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 / electronics.

In recent years, especially in the use of automobile parts, the higher performance has led to a rise in temperature in the engine room, and there is an increasing demand for a material that can be used in a severe high temperature atmosphere. The melting point of 220 ° C.) and nylon 66 (melting point of 260 ° C.) have limitations in use at high temperatures, and there are problems such as poor dimensional accuracy due to water absorption.

Recently, as a polyamide resin usable at such a high temperature, Japanese Patent Laid-Open No. 155426/1984,
JP-A-62-156130 discloses a high melting point copolyamide resin containing terephthalic acid and / or isophthalic acid.

Since these polyamide resins have a high melting point and a high heat distortion temperature and thus have the potential to be used continuously at high temperatures, they are not only poor in moldability, but also compared with nylon 6 and nylon 66. However, there is a problem that it cannot be applied as a practical molded product as it is.

Further, Japanese Patent Application Laid-Open No. 61-283553 describes that impact resistance is improved by blending the above-mentioned high melting point copolyamide resin with a modified polyolefin. Although the technique certainly improves the impact resistance to some extent, the improvement in the toughness represented by the elongation at break is small, and further, the deterioration in the toughness after long-term use in a high temperature environment cannot be suppressed.

[0008]

As described above, according to the conventional techniques, it is difficult to obtain a polyamide resin composition having a small decrease in toughness in a high temperature atmosphere and excellent balance of rigidity and moldability. It was

Therefore, the present invention is excellent in mechanical properties and moldability, has a small decrease in toughness even when used in a high temperature atmosphere for a long time, is excellent in durability, and has a small dimensional change due to water absorption, particularly a thin-walled molded product. An object is to obtain a polyamide resin composition suitable for production.

[0010]

That is, the present invention is
(A) (a) Hexamethylene terephthalamide unit 80
To 20% by weight, and (b) 98 to 30% by weight of a crystalline copolyamide obtained by polymerizing 20 to 80% by weight of a hexamethyleneadipamide unit or a caproamide unit, (B) the number of methylene groups per amide group ( 0.5 to 50% by weight of aliphatic polyamide having an amide group concentration of 5.5 or more and (C) one or more elastomer components selected from polyolefin elastomers and diene elastomers 1.5
It is a polyamide resin composition containing about 60% by weight.

(A) (a) Hexamethylene terephthalamide unit used in the present invention 80 to 20% by weight and (b)
The crystalline copolyamide obtained by polymerizing 20 to 80% by weight of a hexamethylene adipamide unit or a caproamide unit is a copolyamide obtained by copolymerizing hexamethylene ammonium terephthalate and hexamethylene ammonium adipate (hereinafter, referred to as 6T / 66 copolyamide) or hexamethylene ammonium terephthalate and at least one selected from ε-caprolactam or 6-aminocaproic acid as a copolyamide (hereinafter referred to as 6T / 6 copolyamide), hexamethylene ammonium Examples thereof include a copolyamide obtained by copolymerizing terephthalate with hexamethylene ammonium adipate and ε-caprolactam or 6-aminocaproic acid. The copolymerization ratio is 80 to 20% for the component (a) and 20 for the component (b).
There is no particular limitation as long as it is 80% by weight. Above all, 6T /
66 = 80 to 20/20 to 80 (weight ratio), preferably 65 to 25/35 to 75, more preferably 59 to 30 /
41-70 or 6T / 6 = 80-20 / 20-20-80
The weight ratio is preferably 78 to 45/22 to 55, more preferably 78 to 60/22 to 40. If the amount of the component (a) is less than 20% by weight, the polymer melting point will be low and the heat resistance will be reduced, such being undesirable. Further, when the amount of the component (a) exceeds 80% by weight, the melting point of the polymer becomes high and the heat resistance is improved, but the processing temperature becomes high, so that the polymer is liable to be thermally decomposed, which is not preferable.

The degree of polymerization of these crystalline copolyamides is usually the relative viscosity when measured at 25 ° C. in a 1% concentrated sulfuric acid solution from the viewpoint of mechanical properties and moldability of the composition.
Those in the range of 1.5 to 5.0, preferably 2.0 to 3.5 are suitable.

The method for producing the crystalline copolyamide is not particularly limited, but the usual melt polymerization, a salt of hexamethylenediamine and terephthalic acid (6T salt), a salt of hexamethylenediamine and adipic acid (66 salt) or 6T salt and ε
-Caprolactam or 6-aminocaproic acid in an aqueous solution of at least one selected from 150 to 320
The prepolymer is heated at ℃ and solid-phase polymerized at a temperature not higher than the melting point, or a method of increasing the degree of polymerization by a melt extruder, 6T salt and 66 salt (or 6-aminocaproic acid) having a melting point not higher than the melting point are used. A method such as direct solid phase polymerization at temperature is simple and suitable.

Further, the crystalline copolyamide may be added with additives such as a viscosity modifier, a pigment, an oxidative deterioration inhibitor, and a heat-resistant agent as long as the characteristics thereof are not impaired.

The component (B) aliphatic polyamide used in the present invention is an aliphatic polyamide in which the number of methylene groups per amide group is 5.5 or more, and its main constituents are amino acids, lactams or diamines. It is a dicarboxylic acid.

Typical examples of the main constituents are as follows:
-Aminocaproic acid, 11-aminoundecanoic acid, 12
-Aminododecanoic acid, amino acids such as para-aminomethylbenzoic acid, lactams such as ε-caprolactam and ω-laurolactam, aliphatic diamines such as tetramethylenediamine, hexamethylenediamine, undecamethylenediamine and dodecamethylenediamine, adipic acid , Suberic acid, azelaic acid, sebacic acid, dodecanedioic acid, etc., and polyamide homopolymers or copolymers derived from these raw materials can be used alone or in the form of a mixture.

Aliphatic polyamides particularly useful in the present invention are:
Tetramethylene adipamide (nylon 46), polyhexamethylene sebacamide (nylon 610), polyhexamethylene dodecamide (nylon 612), polyundecamethylene adipamide (nylon 611), polyundecane amide (nylon 11) , Polydodecanamide (nylon 12) and the like.

The degree of polymerization of the aliphatic polyamide used here is not particularly limited, and one having a relative viscosity of 1.5 to 5.0 measured at 25 ° C. in a 1% concentrated sulfuric acid solution is arbitrarily selected. be able to.

The aliphatic polyamide has a number of methylene groups per amide group (amide group concentration) of 5.5 or more, preferably 5.8 or more, particularly preferably 6.0 or more,
If it is less than 5.5, not only is the toughness significantly reduced after being exposed to a high temperature environment for a long time, but also dimensional fluctuation due to water absorption becomes large, which is not preferable.

As the component (C) used in the present invention, one or more kinds of elastomer components selected from the polyolefin-based elastomers and the diene-based elastomers, there may be mentioned unmodified or modified polyolefin-based elastomers and diene-based elastomers. ..

Suitable unmodified polyolefin elastomers include α such as ethylene, propylene, bun-1, pentene-1, 4-methylpentene-1, isobutylene.
-Olefin, 1,4-hexadiene dicyclopentadiene, 2,5-norbornadiene, 5-ethylidene norbornene, 5-ethyl-2,5-norbornadiene, 5
The polyolefin obtained by radical-polymerizing at least 1 sort (s) of non-conjugated dienes, such as-(1'- probenyl) -2- norbornene, can be mentioned.

A suitable unmodified diene-based elastomer is an AB-type or AB-A'-type block copolymer elastic body composed of a vinyl-based aromatic hydrocarbon and a conjugated diene. And A'may be the same or different, and examples thereof include a thermoplastic homopolymer or copolymer derived from a vinyl aromatic hydrocarbon whose aromatic moiety may be monocyclic or polycyclic. Examples of group hydrocarbons include styrene, α-methylstyrene, vinyltoluene, vinylxylene, ethylvinylxylene,
Examples thereof include vinylnaphthalene and mixtures thereof. The intermediate polymer block B is composed of a conjugated diene hydrocarbon, and examples thereof include polymers derived from 1,3-butadiene, 2,3-dimethylbutadiene, isoprene, 1,3-pentadiene and a mixture thereof.
The block copolymer elastic material used in the present invention also includes the block copolymer intermediate polymer block B obtained by subjecting the block copolymer elastic body to a hydrogenation treatment.

Specific examples of suitable unmodified elastomers include ethylene / propylene copolymers, ethylene / butene-1 copolymers, ethylene / propylene / dicyclopentadiene copolymers, ethylene / propylene / 5-ethylidene-2. -Norbornene copolymer, unhydrogenated or hydrogenated polybutadiene, unhydrogenated or hydrogenated styrene / isoprene /
Examples thereof include styrene triblock copolymer, unhydrogenated or hydrogenated styrene / butadiene / styrene triblock copolymer.

As the modified elastomer, a monomer having at least one functional group selected from the group consisting of a carboxylic acid group, a carboxylic acid ester group, a carboxylic acid metal base, a carboxylic acid anhydride group, an imide group and the like is added to the unmodified elastomer. A modified elastomer obtained by introducing a component (hereinafter referred to as a functional group-containing component).

Examples of the functional group-containing component include acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid, crotonic acid, methylmaleic acid, methylfumaric acid,
Mesaconic acid, citraconic acid, glutaconic acid and metal salts of these carboxylic acids, methyl hydrogen maleate, methyl hydrogen itacone, methyl acrylate, ethyl acrylate,
Butyl acrylate, 2-ethylhexyl acrylate, hydroxyethyl acrylate, methyl methacrylate, 2-ethylhexyl methacrylate, hydroxyethyl methacrylate, aminoethyl methacrylate, dimethyl maleate, dimethyl itaconic acid, maleic anhydride , Itaconic anhydride, citraconic anhydride, endobicyclo-
(2,2,1) -5-heptene-2,3-dicarboxylic acid, endobicyclo- (2,2,1) -5-heptene-
2,3-dicarboxylic anhydride, maleimide, N-ethylmaleimide, N-butylmaleimide, N-phenylmaleimide, glycidyl acrylate, glycidyl methacrylate, glycidyl ethacrylate, glycidyl itaconate,
Glycidyl citrate and the like.

The method of introducing these functional group-containing components is not particularly limited, and it is possible to use a method such as copolymerization or graft introduction to the unmodified elastomer with a radical initiator. The amount of the functional group-containing component introduced is appropriately in the range of 0.001 to 40 mol%, preferably 0.01 to 35 mol%, based on the whole modified elastomer.

Specific examples of the modified elastomer particularly useful in the present invention include ethylene / acrylic acid copolymers and ethylene / acrylic acid copolymers.
Methacrylic acid copolymers and salts of some or all of the carboxylic acid moieties in these copolymers with sodium, lithium, potassium, zinc, calcium, ethylene / methyl acrylate copolymers, ethylene / acrylic acid Ethyl copolymer, ethylene / methyl methacrylate copolymer, ethylene / ethyl methacrylate copolymer, ethylene / ethyl acrylate-g-maleic anhydride copolymer,
("G" represents a graft, the same applies hereinafter), ethylene /
Methyl methacrylate-g-maleic anhydride copolymer, ethylene / ethyl acrylate-g-maleimide copolymer,
Ethylene / ethyl acrylate-g-N-phenylmaleimide copolymer and partially saponified products of these copolymers, ethylene / glycidyl methacrylate copolymer, ethylene / vinyl acetate / glycidyl methacrylate copolymer, ethylene / methyl methacrylate / Glycidyl methacrylate copolymer, ethylene / glycidyl acrylate copolymer, ethylene / vinyl acetate / glycidyl acrylate copolymer, ethylene / glycidyl ether copolymer, ethylene / propylene-g-maleic anhydride copolymer, ethylene / butene- 1-g-maleic anhydride copolymer, ethylene / propylene / 1,4-hexadiene-g-maleic anhydride copolymer, ethylene / propylene / dicyclopentadiene-g-maleic anhydride copolymer, ethylene / pro Len / 2,5-norbornadiene-g-maleic anhydride copolymer, ethylene / propylene-g-N-phenylmaleimide copolymer, ethylene / butene-1-g-N-phenylmaleimide copolymer, hydrogenated styrene / Butadiene / styrene-g-maleic anhydride copolymer, hydrogenated styrene / isoprene / styrene-g-
Maleic anhydride copolymer, ethylene / propylene-g-
Glycidyl methacrylate copolymer, ethylene / butene-
1-g-glycidyl methacrylate copolymer, ethylene /
Propylene / 1,4-hexadiene-g-glycidyl methacrylate copolymer, ethylene / propylene / dicyclopentadiene-g-glycidyl methacrylate copolymer,
Examples thereof include hydrogenated styrene / butadiene / styrene-g-glycidyl methacrylate copolymer.

The blending amount of the components (A) to (C) in the present invention is 98 to 30% by weight of the crystalline copolyamide (A), preferably 95 to 40% by weight, particularly preferably 90 to 50% by weight.
% By weight, (B) aliphatic polyamide 0.5 to 50% by weight,
Preferably 2-40% by weight, particularly preferably 5-30% by weight, (C) elastomer component 1.5-60% by weight, preferably 3-50% by weight, particularly preferably 5-45% by weight.
Is.

(A) The amount of the crystalline copolyamide compounded is 30
If it is less than wt%, the heat resistance is insufficient, and if it exceeds 98 wt%, the toughness is insufficient, which is not preferable. On the other hand, if the blending amount of the aliphatic polyamide (B) is less than 0.5% by weight, the toughness-improving effect is poor, and in particular, the toughness is extremely decreased after being exposed to a high temperature environment for a long time, which is not preferable. Also, (B)
If the blending amount of the aliphatic polyamide exceeds 50% by weight, not only the heat resistance decreases but also the dimensional fluctuation due to water absorption becomes large, which is not preferable. If the content of the component (C) is less than 1.5% by weight, the toughness improving effect is poor, and if it exceeds 60% by weight, the heat resistance is lowered, which is not preferable.

In the polyamide resin composition of the present invention, antioxidants, heat stabilizers such as copper iodide and potassium iodide, lubricants, crystal nucleating agents, and anti-ultraviolet rays are added to the extent that the effects of the present invention are not impaired. Conventional additives such as agents, colorants, flame retardants and small amounts of other polymers can be added.

The method for producing the composition of the present invention is not particularly limited, and after the crystalline copolyamide, the aliphatic polyamide, the elastomer component and other additives are dry blended using a ribbon blender, a Henschel mixer, a V blender or the like. , A Banbury mixer, a mixing roll, a single-screw or twin-screw extruder, a kneader, and the like. Of these, a typical method is melt kneading using a single-screw or twin-screw extruder having a sufficient kneading force.

The order of kneading is not particularly limited, and it is possible to knead the above-mentioned three mixtures at once, or it is possible to mix two components in advance and then mix the remaining one component.

In the polyamide resin composition of the present invention, it is important to add a specific aliphatic polyamide and a specific elastomer component in combination to the crystalline copolyamide, whereby synergistic effects are exhibited.

The polyamide resin composition produced by the above method can be molded into a shape having a thin portion having a thickness of 1 mm or less by a method such as injection molding, extrusion molding, blow molding, vacuum or pressure molding. The molded product is characterized in that the deterioration of toughness is extremely small even after being exposed to a high temperature environment for a long time.

[0035]

EXAMPLES The effects of the present invention will be further described below with reference to examples.

The aliphatic polyamide and elastomer components used in the examples are shown in Table 1.

[0037]

[Table 1]

Examples 1-13, Comparative Examples 1-11 6T / 66 copolyamides shown in Tables 2 and 3, Table 1
Aliphatic polyamides shown in Table 1, elastomer components and Table 2
And the additives shown in Table 3 were blended in the proportions shown in Tables 2 and 3, supplied to an extruder having a 30 mmφ twin screw set at 320 ° C., melt-kneaded into pellets.

After drying the obtained pellets, using a screw in-line type injection molding machine with a mold clamping pressure of 50 t set to 320 ° C., a JI of 1 mm thickness at a mold temperature of 40 ° C.
S-2 No. dumbbell test piece and thickness 1mm x width 80mm
× A thin plate test piece having a length of 80 mm was formed.

The JIS-2 dumbbell test pieces were heat-treated in a gear oven at 160 ° C. for 1000 hours, and the tensile properties were measured to evaluate the heat resistance.

Immediately after molding the thin plate test piece, the test piece was cooled to 35 ° C.
Water was left to stand in an environment of × 65% RH for 30 days to absorb water, and the water absorption and the dimension between reference points were measured to evaluate the water absorption and the dimensional accuracy.

The results are shown in Table 2 (Examples 1 to 13) and Table 3.
(Comparative Examples 1 to 11).

[0043]

[Table 2]

[0044]

[Table 3]

A molded article obtained from the polyamide resin composition of the present invention does not lose its excellent toughness even when exposed to a high temperature environment for a long time, has good heat resistance, and has small dimensional fluctuation due to water absorption. Are clear from Tables 2 and 3.

[0046]

EFFECTS OF THE INVENTION A molded product obtained from the polyamide resin composition of the present invention has excellent mechanical properties and heat resistance, particularly continuous use in a high temperature environment, and excellent dimensional accuracy.
In particular, it is useful for molded articles having a thin portion, such as various electrical components in automobile engine rooms.

Claims (1)

[Claims] 1. A crystalline copolyamide 98 to 80% by weight of (A) (a) hexamethylene terephthalamide unit and 20 to 80% by weight of (b) hexamethylene adipamide unit or caproamide unit. 30% by weight, (B) 0.5 to 50% by weight of an aliphatic polyamide having a number of methylene groups per amide group (amide group concentration) of 5.5 or more, and (C) a polyolefin-based elastomer or a diene-based elastomer. More than one type of elastomer component 1.5 ~
A polyamide resin composition containing 60% by weight.