JPH11181083A - Polyamide resin for connector, resin composition and connector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polyamide resin and a resin composition having excellent mechanical properties, heat-resistance, moldability and dimensional stability, causing little lowering of rigidity even by using in a high humidity atmosphere over a long period and suitable as a molded article such as an automobile harness connector having a thin-walled part. SOLUTION: This polyamide resin for connector is composed of (a) 75-50 mol.% of hexamethylene terephthalamide unit and (b) 25-50 mol.% of an aliphatic polyamide unit having a carbon atom number (amide group concentration) of Z8 per one amide group and has the following characteristics. (A) The melting point is >=300 deg.C and <325 deg.C and (B) the glass transition point in saturated water-absorbed state is >=40 deg.C determined by viscoelasticity measurement and the position of at least one peak of the loss elastic coefficient among plural peaks of the coefficient is >=80 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a polyamide resin composition having excellent mechanical properties, heat resistance, moisture resistance and moldability, and particularly having excellent rigidity and dimensional stability when placed in a high humidity environment. More specifically, it maintains the excellent toughness characteristic of polyamide resin, and has high heat resistance, high moisture resistance, and high dimensional stability with extremely small decrease in rigidity even after long-term exposure in a high humidity environment. The present invention relates to a polyamide resin and a composition thereof, which are preferably used for a connector used mainly in an engine room of an automobile and a composition thereof.

[0002]

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, in harness connectors used in automobile parts, particularly in engine rooms, harsh operating environments such as temperature rise and high humidity in engine rooms have been accompanied by higher performance and higher output of engine performance. There is an increasing demand for a material that can maintain a high binding function and connection function even below. In response to such advanced requirements, widely used nylon 6, nylon 66
Resins have problems such as a reduction in rigidity due to water absorption, which impairs the connection function, a large dimensional change, and poor dimensional stability.

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-3-201375 describe terephthalic acid and / or
Alternatively, a high melting point copolyamide resin containing isophthalic acid is disclosed. 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 high rigidity and dimensional stability even in a high humidity environment. Molding processability such as foreign matter likely to be caused by gelling or carbonization of polymer when manufacturing molded products, or gas burning or mold contamination likely to occur due to volatile gas generation due to partial decomposition. Is significantly impaired,
There is a problem that it is not enough to produce a practical molded product with high productivity as it is.

JP-A-61-283653 describes that the impact resistance is improved by blending a modified polyolefin with the above-mentioned high-melting point copolyamide resin. Although the impact resistance is improved to some extent by this technique, the initial rigidity is low, and the decrease in the rigidity after use for a long time in a high humidity use environment cannot be suppressed.

[0006]

As described above, in the prior art, the rigidity decrease in a high humidity atmosphere is small, and
It has been difficult to obtain a polyamide resin or a composition using the same with excellent balance of heat resistance, toughness and moldability.

Accordingly, the present invention is excellent in mechanical properties, heat resistance, moldability, and dimensional stability, has a small decrease in rigidity even when used for a long time in a high humidity atmosphere, has excellent stability in melt retention, and has excellent water absorption. It is an object of the present invention to obtain a polyamide resin and a resin composition suitable for the production of an automobile harness connector molded product having a small dimensional change due to the above, particularly having a thin portion.

[0008]

That is, the present invention provides:
1. "(A) hexamethylene terephthalamide unit 75
-50% by mole and (b) 25-50% by mole of an aliphatic polyamide unit having 8 or more carbon atoms per one amide group (amide group concentration), and the properties thereof are within the following ranges. Characteristic polyamide resin for connectors. (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) hexamethylene terephthalamide unit 75
Ｂ50 mol%, (b ′) 45 to 20 mol% of aliphatic polyamide units which have not less than 8 carbon atoms (amide group concentration) per amide group and are not defined in the following component (c), and c) A polyamide resin for a connector comprising 5 to 15 mol% of at least one structural unit selected from undecaneamide units, dodecaneamide units and caproamide units, and further having the following characteristics: . (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. 3. The polyamide resin for a connector according to the above 1 or 2, wherein the aliphatic polyamide unit of the component (b) or the component (b ′) is hexamethylene sebacamide. 4. The polyamide resin for a connector according to the above 1 or 2, wherein the aliphatic polyamide unit of the component (b) or the component (c) is undecaneamide or dodecaneamide. 5. The polyamide resin for a connector according to the above item 2, wherein the polyamide unit of the component (c) is a caproamide unit. 6. The polyamide resin for a connector according to the above item 2, wherein the polyamide unit of the component (c) is a dodecaneamide unit. 7. The polyamide resin for a connector according to the above item 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. 8. The polyamide resin for a connector according to the above item 2, wherein the aliphatic polyamide unit of the component (b ') is hexamethylene sebacamide and the polyamide unit of the component (c) is a dodecaneamide unit. "The polyamide resin for a connector according to any one of the above items 1 to 8, wherein the connector is for an automobile."

10. "(A) (a) hexamethylene terephthalamide units of 75 to 50 mol% and (b) 25 to 50 mol% of aliphatic polyamide units having 8 or more carbon atoms per one amide group (amide group concentration), Furthermore, polyamide resins 99 to 80 whose properties are in the following ranges:
A polyamide resin composition for a connector comprising 1% to 20% by weight of a modified polyolefin modified with a carboxylic acid and / or a derivative thereof (B). (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. 10. "(A ') (a) 75 to 50 mol% of hexamethylene terephthalamide unit, (b') the number of carbon atoms per one amide group (amide group concentration) is 8 or more, and the following component (c) Undefined aliphatic polyamide unit 45
And (c) 5 to 15 mol% of at least one structural unit selected from undecaneamide units, dodecaneamide units and caproamide units,
Further, the polyamide resin 99 whose properties are within the following ranges:
A polyamide resin composition for a connector, which comprises 80 to 80% by weight and (B) 1 to 20% by weight of a modified polyolefin modified with a carboxylic acid and / or a derivative thereof. (B) Melting point: 300 ° C. or more and less than 325 ° C. (b) The glass transition point at the time of saturated water absorption determined by viscoelasticity measurement is 40 ° C. or more, and at least one of a plurality of peak values of the loss elastic coefficient observed. At 80 ° C
that's all. "

12. "Homopolymer of α-olefin wherein modified polyolefin of component (B) contains at least one selected from carboxylic acid groups, carboxylic acid anhydride groups, carboxylic acid ester groups, and carboxylic acid metal bases in the polymer molecular chain. 12. The polyamide resin composition for a connector according to the above item 10 or 11, which is a copolymer. ""The connector is for an automobile.
A polyamide resin composition for any of the connectors. 14. 14. "A connector obtained by injection-molding the polyamide resin described in any of the above items 1 to 9." It is intended to provide "a connector obtained by injection molding the polyamide resin composition according to any one of the above items 10 to 13."

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, the first polyamide resin (A) specified in claims 1 and 10 includes (a) 75 to 50 mol% of hexamethylene terephthalamide unit and (b) one amide group. 25-50 mol% of aliphatic polyamide units having 8 or more carbon atoms (amide group concentration) per unit
Wherein the second polyamide resin (A ') specified in claims 2 and 11 comprises (a) 75 to 50 mol% of hexamethylene terephthalamide units and (b') the number of carbon atoms per amide group. (Amide group concentration) 45 to 20 mol% of aliphatic polyamide units having 8 or more (c) at least one structural unit 5-1 selected from undecaneamide units, dodecaneamide units and caproamide units
What consists of 5 mol% is used.

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

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 the 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 25 to 50 mol%, respectively, preferably 70 to 55 mol% and 30 to 45 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, viscoelastic behavior, and viscoelastic behavior upon water absorption is obtained. This is because when used as a connector for an automobile, it is possible to exhibit preferable performances such as little reduction in rigidity in a high humidity atmosphere and excellent balance between heat resistance, toughness, and moldability. In particular, it is important that a glass transition point of 40 ° C. or higher is maintained during water absorption, and a segment having a loss elastic modulus peak of 80 ° C. or higher.
In addition, by using a component having a lower amide group concentration as a copolymer component than a conventionally known high-melting point copolyamide resin containing terephthalic acid and / or isophthalic acid, it is possible to prevent foreign matters from entering a molded article, gas burning, and the like. The molding problems have been greatly improved.

If the copolymerization amount of the component (a) is larger than the above range, the melting point of the produced polyamide resin 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) or the component (b ') is larger than the above range, the melting point is lowered, and the required heat resistance cannot be maintained. It is not preferable because the water absorption increases and the rigidity at the time of water absorption decreases. 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 in this case, and the required heat resistance cannot be maintained. It is not preferable because the fluidity of the resulting polyamide resin is reduced.

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.

In the present invention, (B) a modified polyolefin modified with a carboxylic acid and / or a derivative thereof, which is appropriately used as necessary, is blended as a composition for further improving properties. Such a component is a polyolefin containing, in its molecule, a functional group having an affinity for a polyamide resin, particularly a carboxylic acid group, a carboxylic acid anhydride group, a carboxylic acid ester group, or a carboxylic acid metal base. And α-olefin homopolymers or copolymers containing at least one member selected from the group consisting of:

Specific examples of α-olefin homopolymers or copolymers include homopolymers such as polyethylene, polypropylene, polybutene-1, polypentene-1, and polymethylpentene; ethylene, propylene, butene-1, pentene-1,4 -Methylpentene-
1, hexene-1, octene-1, α-olefins such as isobutylene, 1,4-hexadienedicyclopentadiene, 2,5-norbornadiene, 5-ethylidene norbornene, 5-ethyl-2,5-norbornadiene,
Examples include polyolefins obtained by radical polymerization of at least one non-conjugated diene such as 5- (1′-probenyl) -2-norbornene using a normal metal catalyst or a metallocene-based high-performance catalyst.

The diene elastomer is an AB or ABA 'type block copolymer elastic body composed of a vinyl aromatic hydrocarbon and a conjugated diene, and the terminal blocks A and A' are They may be the same or different, and include a thermoplastic homopolymer or copolymer derived from a vinyl aromatic hydrocarbon in which the aromatic portion may be monocyclic or polycyclic. Examples include styrene, α-methylstyrene, vinyltoluene,
Examples include vinyl xylene, ethyl vinyl xylene, vinyl naphthalene, and mixtures thereof. The intermediate polymer block B is made of a conjugated diene-based hydrocarbon, and examples thereof include 1,3-butadiene, 2,3-dimethylbutadiene, isoprene, 1,3-pentadiene, and a polymer derived from a mixture thereof. In the present invention,
Also included are those obtained by subjecting the intermediate polymer block B of the block copolymer to a hydrogenation treatment.

Specific examples of the polyolefin copolymer include ethylene / propylene copolymer, ethylene / butene-1 copolymer, ethylene / hexene-1 copolymer, ethylene / propylene / dicyclopentadiene copolymer, ethylene / propylene / 5 -Ethylidene-2-norbornene copolymer, unhydrogenated or hydrogenated polybutadiene, unhydrogenated or hydrogenated styrene / isoprene / styrene triblock copolymer, unhydrogenated or hydrogenated styrene / butadiene /
Styrene triblock copolymer and the like can be mentioned.

The functional groups that modify these polyolefins include carboxylic acid groups, carboxylic acid anhydride groups, carboxylic acid ester groups, carboxylic acid metal base carboxylic acid imide groups,
Carboxamide groups and the like, examples of compounds containing these functional groups include acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid, crotonic acid,
Methyl maleic acid, methyl fumaric acid, mesaconic acid, citraconic acid, glutaconic acid and metal salts of these carboxylic acids, methyl hydrogen maleate, methyl hydrogen itaconate, methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate , Hydroxyethyl acrylate, methyl methacrylate, methacrylic acid 2
-Ethylhexyl, hydroxyethyl methacrylate,
Aminoethyl methacrylate, dimethyl maleate, dimethyl itaconate, 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-phenyl Maleimide, glycidyl acrylate, glycidyl methacrylate, glycidyl ethacrylate, glycidyl itaconate, glycidyl citraconic acid and the like.

The method for introducing these functional group-containing components is not particularly limited, and a method such as copolymerization or graft-introduction to an unmodified polyolefin using a radical initiator can be used. The amount of the functional group-containing component introduced is 0.001 to 40 mol%, preferably 0.01 to 35 mol%, based on the whole olefin monomer in the modified polyolefin.
Suitably it is in the range of mol%.

Specific examples of the modified polyolefins particularly useful in the present invention include maleic anhydride-modified polyethylene, maleic anhydride-modified polypropylene, ethylene / acrylic acid copolymer, ethylene / methacrylic acid copolymer, and copolymers in these copolymers. Some or all of the carboxylic acid portion is converted to a salt with sodium, lithium, potassium, zinc, or calcium, ethylene / methyl acrylate copolymer, ethylene / ethyl acrylate copolymer, ethylene / methyl methacrylate copolymer 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, Styrene / ethyl acrylate -g-N
Phenylmaleimide copolymers 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 / propylene / 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-
Examples include g-glycidyl methacrylate copolymer, ethylene / propylene / dicyclopentadiene-g-glycidyl methacrylate copolymer, hydrogenated styrene / butadiene / styrene-g-glycidyl methacrylate copolymer, and the like.

In the present invention, the blending amount of the modified polyolefin of the component (B) is in the range of 1 to 20% by weight, and the preferred range is 3 to 10% by weight.

The polyamide resin composition obtained here contains an antioxidant, a heat stabilizer such as copper iodide and potassium iodide, a lubricant, a crystal nucleating agent, as long as its properties are not impaired.
Conventional additives such as UV inhibitors, colorants, flame retardants and small amounts of other polymers can be added.

The method for producing the present composition is not particularly limited, and the polyamide resin, the modified polyolefin and other additives of the present invention are dry-blended using a ribbon blender, a Henschel mixer, a V blender, and the like, and then mixed with a Banbury mixer, A method of melt-kneading using a roll, a single-screw or twin-screw extruder, a kneader or the like can be used. Above all, a typical method is melt kneading using a single-screw or twin-screw extruder having a sufficient kneading force.

The polyamide resin and the resin composition obtained by the present invention are excellent in mechanical properties, heat resistance, moldability, and dimensional stability, and have a small decrease in rigidity even when used for a long time in a high humidity atmosphere. It is excellent in properties, has a small dimensional change due to water absorption, and is particularly suitable for producing an automobile harness connector molded product having a thin portion, and the obtained connector molded product has high practical value.

[0032]

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 Examples and Comparative Examples were measured by the following methods. Melting point: Using an RDC220 differential working calorimeter manufactured by Seiko Instruments Inc., the temperature was once increased at a heating rate of 40 ° C./min, held at an endothermic peak temperature plus 20 ° C. for 5 minutes, and then kept at 20 ° C./min. After cooling down to 100 ° C at a speed of 2 minutes
The peak value measured at a heating rate of 0 ° 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-shaped test piece was cut out therefrom and manufactured by Toyo Baldwin's Leo Vibron DDV.
Using II-EA at a frequency of 110 Hz and a heating rate of 2 ° C. /
It was measured under the condition of minutes. 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: ASTM D638 Flexural modulus: According to ASTM D790, the flexural modulus at absolute dryness and at atmospheric equilibrium water absorption was measured.・ Practical water absorption characteristics: maximum value 55 mm, height 13 mm,
The connector shown in FIG. 1 having a depth of 37 mm and a thickness of 1 mm was formed by injection molding, and this was placed as shown in FIG. 1 (B), and a weight of 50 g was placed on the connector.
The degree of deformation of the molded article after standing for 100 hours at 95 ° C. and 95% RH was observed. The criteria are as follows. ○: No deformation △: Small deformation X: Large deformation

Stability during melt retention: In the molded product obtained by molding the above connector, the cylinder temperature of the injection molding machine was set to the melting point of the polyamide resin plus 30 ° C., and the resin was retained in the cylinder for 15 minutes and then molded. The number of foreign substances and the occurrence behavior of gas burning were visually observed and used as indices of stability during melt retention. The criteria are as follows. ：: The number of foreign substances is 1 or less, no gas burn. Δ: The number of foreign substances is 1 to 2 and gas burn is small. X: The number of foreign substances is 3 or more, gas burn is large.

Example 1 Hexamethylene terephthalate (6T salt), hexamethylene diammonium terephthalate (6T salt) prepared to be 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. Various test pieces were obtained by injection molding of this polyamide resin, and the properties were measured. As shown in Table 1, the polyamide resin had excellent rigidity and dimensional stability even when absorbing water, and was used as a connector material. It turned out to be useful.

[0038]

[Table 1]

Comparative Example 1 Polymerization, molding and characteristic evaluation were 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 results are shown in Table 1. The polyamide resin obtained here was particularly low in rigidity at the time of water absorption, and had insufficient heat stability and was not practical.

Comparative Example 2 Example 2 was repeated except that the raw material mixture ratio was changed so that the composition of the resulting polyamide was 25 mol% of hexamethylene terephthalamide units, 50 mol% of hexamethylene sebacamide units and 25 mol% of caproamide units. Polymerization, molding, and property evaluation were performed in exactly the same manner as in Example 1. The results are shown in Table 1. The polyamide resin obtained here had low rigidity at the time of water absorption and was not practical.

Comparative Example 3 Except that the raw material mixing ratio was changed so that the composition of the polyamide to be formed was 65 mol% of hexamethylene terephthalamide units, 25 mol% of hexamethylene isophthalamide units and 10 mol% of hexamethylene adipamide units. Polymerization, molding, and property evaluation were performed in exactly the same manner as in Example 1. The results are shown in Table 1. The polyamide resin obtained here had insufficient melt heat stability and was not practical.

Examples 2 to 5 Polymerization, molding and evaluation of properties were performed in exactly the same manner as in 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 results are as shown in Table 1. The polyamide resin obtained here was also excellent in rigidity and dimensional stability when absorbing water.

Examples 6 to 9 Melt kneading of the polyamide resin obtained in Examples 1 to 5 and polyethylene and / or polypropylene modified with maleic anhydride using a twin-screw extruder in a mixing ratio shown in Table 2. After that, injection molding and characteristic evaluation were sequentially performed. As shown in Table 2, the results were all compositions having excellent properties.

[0044]

[Table 2]

[0045]

The polyamide resin and the resin composition obtained by the present invention have excellent mechanical properties, heat resistance, moldability, and dimensional stability, and have a small decrease in rigidity even when used for a long time in a high humidity atmosphere. It is excellent in durability, has a small dimensional change due to water absorption, and is particularly suitable for producing a molded article of an automobile harness connector having a thin portion, and the obtained molded article of the connector is of high practical value.

[Brief description of the drawings]

FIG. 1 is a schematic view of a connector molded product produced in an example, (A) is a plan view, and (B) is a front view.

Claims (15)

[Claims] (1) From 75 to 50 mol% of (a) hexamethylene terephthalamide unit and from 25 to 50 mol% of (b) an aliphatic polyamide unit having 8 or more carbon atoms per one amide group (amide group concentration). A polyamide resin for a connector, the characteristics of which are in the following range. (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 hexamethylene terephthalamide units, (b ′) the number of carbon atoms per one amide group (amide group concentration) is 8 or more, and the following component (c): 45 to 45 undefined aliphatic polyamide units
20 mol%, and (c) 5 to 15 mol% of at least one structural unit selected from undecane amide units, dodecane amide units and caproamide units, and the characteristics thereof are within the following ranges. Polyamide resin for connectors. (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 for a connector according to claim 1, wherein the aliphatic polyamide unit of the component (b) or the component (b ′) is hexamethylene sebacamide. 4. The polyamide resin for a connector according to claim 1, wherein the aliphatic polyamide unit of the component (b) or the component (c) is undecaneamide or dodecaneamide. 5. The polyamide resin for a connector according to claim 2, wherein the polyamide unit of component (c) is a caproamide unit. 6. The polyamide resin for a connector according to claim 2, wherein the polyamide unit of component (c) is a dodecaneamide unit. 7. The polyamide resin for a connector 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. 8. The polyamide resin for a connector 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 dodecaneamide unit. 9. The connector according to claim 1, wherein the connector is for an automobile.
8 Any polyamide resin for connectors. 10. (A) 75 to 50 mol% of (a) hexamethylene terephthalamide unit and (b) amide group 1
(B) a carboxylic acid comprising 99 to 80% by weight of a polyamide resin having 25 to 50 mol% of an aliphatic polyamide unit having 8 or more carbon atoms (amide group concentration) per unit and having the following characteristics: A polyamide resin composition for a connector comprising 1 to 20% by weight of a modified polyolefin modified with a derivative thereof. (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. 11. (A ′) (a) 75 to 50 mol% of hexamethylene terephthalamide unit, (b ′) amide group 1
The number of carbon atoms per unit (amide group concentration) is 8 or more, and 45 to 20 mol% of an aliphatic polyamide unit not defined in the following component (c); and (c) undecaneamide unit, dodecaneamide unit and caproamide unit 5 to 15 mol% of at least one structural unit selected from
And 99% to 80% by weight of a polyamide resin having the following properties and (B) a modified polyolefin modified with a carboxylic acid and / or a derivative thereof:
A polyamide resin composition for a connector comprising about 20% by weight. (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. 12. The modified polyolefin of the component (B) is at least one selected from a carboxylic acid group, a carboxylic acid anhydride group, a carboxylic acid ester group and a carboxylic acid metal base.
The polyamide resin composition for a connector according to claim 10 or 11, which is a homopolymer or a copolymer of an α-olefin containing a seed in a polymer molecular chain. 13. The connector according to claim 1, wherein the connector is for an automobile.
A polyamide resin composition for a connector according to any one of 0 to 12. 14. A connector obtained by injection-molding the polyamide resin according to claim 1. Description: 15. A connector obtained by injection molding the polyamide resin composition according to claim 10.