JPH11158372A - Polyamide resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject composition that has high heat distortion temperature, even when the mold temperature is low on molding and gives molded products of excellent resistances to chemicals and shocks with reduced variation in physical properties caused by water absorption and reduced thermal decomposition during the elevated temperature processing by using a specific crystalline partial aromatic polyamide together with a specific ethylenic polymer and a polyolefin. SOLUTION: This polyamide resin composition comprises (A) 65-85 pts.wt. of crystalline partial aromatic polyamide containing the recurring units of formulas I and II [n is 45-80 wt.%; m is 55-22 wt.%], (B) 10-35 pts.wt. of an ethylene- acrylic ester-maleic acid terpolymer and (C) 3-15 pts.wt. of a polyolefin. In the component A, the units of hexamethylene terephthalamide of formula I preferably occupies 50-60%, while the unit of hexamethylene adipamide does 50-40%. In the component B, the amount of acrylic ester to be copolymerized is preferably 5-15%. This composition is suitably used as a wire harness.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyamide resin composition comprising a crystalline partially aromatic polyamide resin containing an ethylene-acrylate-maleic anhydride copolymer and a polyolefin, and has excellent heat resistance.
In addition, it is possible to obtain molded products with little impact change, good weld elongation, chemical resistance, dimensions due to water absorption, and little change in physical properties, such as cylinder head covers, wire harness connectors, radiator tanks, air intake manifolds, ignition coil cases, etc. It can be widely used for automobile parts, various switch parts, electrical and electronic parts such as connectors, sockets, switches and the like, mechanical parts and building parts. However, among them, it is particularly preferably used for a wire harness connector.

[0002]

2. Description of the Related Art Conventionally, polyamide resins have been widely used in automobiles, electric / electronics, machinery, construction, etc. due to their excellent physical and chemical properties. At present, demands for polyamide resins are becoming more severe in pursuit of properties.
Particularly in automobiles and electric / electronic parts, requirements for heat resistance, low water absorption (there is little change in dimensions and physical properties due to water absorption), chemical resistance, impact resistance, and the like are becoming increasingly strong. For example, the use of partially aromatic polyamide, which is a high-melting polyamide with excellent heat resistance, has been studied, but partially aromatic polyamides are generally used aliphatic polyamides,
For example, it has a disadvantage that impact resistance is inferior to polycapramid (nylon 6) and polyhexamethylene adipamide (nylon 66).

[0003] As a method for improving the impact resistance, Japanese Patent Application Laid-Open No. 60-118735 discloses a method of adding a polyolefin modified with an acid anhydride and a peroxide and an unmodified polyolefin to a polyamide resin containing a partially aromatic polyamide. It is described that the impact resistance is improved. In this method, the crystalline partially aromatic polyamide has a high melting point, and
It is necessary to mold at a high temperature of 0 ° C or higher, and acid anhydride units that do not form a polymer main chain, such as a polyolefin modified with an acid anhydride and a peroxide, are liable to undergo thermal decomposition at a high temperature and have a weld extension. There is also the disadvantage of low degree.

As a method for improving the impact resistance of a partially aromatic polyamide, Japanese Patent Application Laid-Open (JP-A) No. 61-283653 discloses the addition of a maleic anhydride-containing ethylene copolymer. When used under practical conditions, the elastic modulus is significantly reduced due to the absorption of a small amount of water, and also has the disadvantage that the heat distortion temperature decreases.In order to improve the heat distortion temperature, There is a drawback that the surface temperature of the mold must be 100 ° C. or higher during molding.

[0005]

According to the present invention, the mold temperature at the time of molding is low (100 ° C. or less), the heat deformation temperature, which is a measure of heat resistance evaluation, is excellent, and the impact resistance, good weld elongation, and chemical resistance are high. A molded product with little change in dimensional and physical properties due to water absorption and water absorption, and with less thermal decomposition during high-temperature processing, and a molded product having a uniform overall physical property during the molding process That is the task.

[0006]

Means for Solving the Problems In order to solve the above problems, the present inventors have made intensive studies, studied, and studied, and as a result, have finally completed the present invention. That is, the present invention provides 65 to 85 parts by weight of a crystalline partially aromatic polyamide (A) comprising repeating units represented by the following general formulas (I) and (II), and an ethylene-acrylate-maleic anhydride copolymer (B ) 10
It is a polyamide molding composition characterized by containing -35 parts by weight and 3-15 parts by weight of polyolefin (C).

[0007]

Embedded image

[0008]

Embedded image (In the above general formula, n is 45 to 80% by weight, and m is 55 to 20% by weight.
Indicate weight%. )

The crystalline partially aromatic polyamide resin as the component A used in the present invention is a random copolymer of a combination of hexamethylene terephthalamide (6T) / hexamethylene adipamide (66). 45-8
0% by weight, preferably 47 to 70% by weight, particularly preferably 50 to 60% by weight, and 66 to 55 to 20% by weight, preferably 53 to 30% by weight, particularly preferably 50 to 50% by weight. It is at least 40% by weight. If the content of the 6T component is less than 45% by weight, the melting point, which is one measure of heat resistance, becomes low, the water absorption rate becomes high, and the water absorption size of the molded product increases, and the mechanical properties are unfavorably reduced. On the other hand, if it exceeds 80% by weight, the melting point becomes too high, and various problems occur during extrusion and molding, which is not preferable.

The relative viscosity and the concentration of the amino terminal group of the polyamide resin as the component A may be within the ranges usually used, that is, 2.1 to 3.5.
2. The amino terminal group concentration is about 30 to 70 × 10 ¹⁴ e
q / g, and is not particularly limited.

The ethylene-acrylic acid ester-maleic anhydride copolymer which is the component B used in the present invention, specifically, ethylene-methyl acrylate-maleic anhydride copolymer, ethylene-ethyl acrylate-anhydride Maleic acid copolymers, ethylene-propyl acrylate-maleic anhydride copolymers, and the like are acid-modified polyolefins produced by a high-pressure radical polymerization method or the like. The acid-modified polyolefin, which is usually used as an impact modifier of polyamide, is obtained by a method of adding a peroxide and an acid anhydride (eg, maleic anhydride) to the polyolefin. Ethylene used
Acrylic ester-maleic anhydride is a polymer in which maleic anhydride forms the main chain of a polymer, has better thermal stability at high temperature processing than the acid-modified polyolefin, and is less likely to be thermally decomposed. In particular, it is particularly suitable for processing at a high processing temperature of 300 ° C. or more, such as the crystalline partially aromatic polyamide resin used in the present invention.

The copolymerization amount of the acrylate in the component B is 3 to 35% by weight, preferably 4 to 25% by weight, and more preferably 5 to 15% by weight. If the acrylic acid ester copolymerization amount is less than 3% by weight, the effect of improving the impact resistance is small, while if it exceeds 35% by weight, heat resistance and rigidity are reduced, and unmodified polyolefin is added when unmodified polyolefin is added. Is also not preferred because the compatibility with

The content of the crystalline partially aromatic polyamide (A) and the ethylene-acrylate-maleic anhydride copolymer (B) is 65 to 85 parts by weight of the component A,
Preferably, it is 67 to 80 parts by weight, particularly 70 to 75 parts by weight. The B component is desirably 35 to 10 parts by weight, preferably 30 to 13 parts by weight, and particularly preferably 25 to 15 parts by weight. If the content of the component A is less than 65 parts by weight, heat resistance,
Rigidity and strength are undesirably reduced. On the other hand, if it exceeds 85 parts by weight, impact resistance is undesirably reduced.
When the content of the component B exceeds 35 parts by weight, heat resistance, rigidity, and strength are reduced. On the other hand, when the content is less than 10 parts by weight, improvement in impact characteristics is not sufficient, which is not preferable.

Specific examples of the polyolefin used in the present invention include polyethylene, polypropylene, ethylene-propylene copolymer and the like, and acid-modified products thereof. The content is 3 to 15 parts by weight, preferably 4 to 13 parts by weight, particularly preferably 5 to 10 parts by weight. If the content of the polyolefin is less than 3 parts by weight, the low water absorption property is deteriorated. On the other hand, if the content is more than 15 parts by weight, the compatibility with the polyamide resin becomes high, and the drawbacks that the weld elongation and the impact properties are deteriorated occur. Absent.

Further, the polyamide resin composition used in the present invention may contain additives usually used, for example, reinforcing agents, flame retardants, lubricants, release agents, heat stabilizers, weathering agents, slidability improving agents, dyes, Pigments, coupling agents and the like may be added.

The reinforcing agent includes a fibrous reinforcing agent and a particulate reinforcing agent. Specific examples of the fibrous reinforcing agent include glass fiber, carbon fiber, aramid fiber, potassium titanate whisker, and aluminum borate whisker. And fibrous silicates such as wollastonite acid. Further, specifically as a particle reinforcing agent, glass beads, silica,
Examples include talc, mica, calcium carbonate, wollastonite, kaolin, clay, magnesium oxide, and alumina oxide. These reinforcing agents may use a silane coupling agent such as an aminosilane coupling agent, an epoxy silane coupling agent, or a titanate-based silane coupling agent for improving the adhesiveness with the polyamide resin, that is, for improving the strength and the Izod impact strength. .

Red flame retardant may be used, and a combination of dibromopolystyrene and antimony trioxide may be used as a halogen type. A metal hydroxide such as magnesium hydroxide, hydrotalcite, or the like may be added as a stabilizer for these flame retardants.

Examples of the lubricant and release agent include metal salts of carboxylic acids such as calcium stearate, barium stearate, magnesium stearate, calcium montanate, and sodium montanate; high molecular substances of montanic acid;
Examples thereof include light amides such as ethylenebisstfurylamide and methylenebisstearylamide, waxes such as polyethylene wax, and polyethylene oxide. Examples of the crystal nucleating agent include talc, silica, wollastonite, clay, and graphite.

Examples of the heat stabilizer include a combination of copper halide and a metal halide of Group 1 of the periodic table, such as potassium iodide, hindered phenols, hindered amines, and sodium hypophosphite and organic phosphorus. Combinations and the like can be mentioned. Examples of the weathering agent include carbon black, benzophenone, triazole, imidazole, oxazole, and hindered amine (HALS). Examples of the slidability improver include high-molecular polyethylene, acid-modified high-molecular polyethylene, fluororesin powder, molybdenum disulfide silicon resin, oil zinc, and the like. What is necessary is just to add by weight%.

The resin composition of the present invention can be produced by kneading the above-mentioned components using a single-screw extruder, a twin-screw extruder, a kneader, a twin-screw roll or the like.
There is no particular limitation on the type of kneader used and the kneading conditions.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION The composition of the present invention obtained by the above method can be molded into various molded articles, and the molding method is a commonly used method such as an injection molding method and an extrusion molding method. And a blow molding method. Specifically, as molded products, in the electric and electronic fields, coil bobbins, motors, transformers, sealing materials,
Cases, connectors, switches, SMT compatible parts, boards, sockets, plug switches, terminal boards, printer parts, etc. In the automotive field, wire harness connectors, cooling water parts, engine parts, lamp sockets,
Examples include a coil bobbin, a sealing material case, a fuel injection pump part, and other applications in which existing nylon resins are difficult due to high-temperature mechanical properties, dimensions due to chemical-resistant water absorption, and changes in physical properties. Among them, it is particularly suitable for a wire harness connector, but the present invention is not limited to these uses.

[0022]

The present invention will be specifically described below with reference to examples. The evaluation of physical properties in the present invention was measured by the following methods. (1) Relative viscosity: Measured according to JIS K6810 (sulfuric acid solution). (2) Melting point: DSC (PERKIN-ELMER7 type)
8 to 10 mg of a sample was heated at a rate of 20 ° C./mi
n is the temperature at which the maximum value of the melting curve obtained by
And Samples 8 to 10 mg are heated at a rate of 20 ° C./mi
n and hold at T + 20 ° C. for 5 minutes, then at 20 ° C. /
After cooling to 30 ° C. at a temperature lowering rate of 5 min and holding for 5 minutes, it was heated again at a temperature increasing rate of 20 ° C./min, and T + 20 ° C.
Heat until The temperature showing the maximum value of the melting curve at this time was defined as the melting point (Tm). (3) Heat deformation temperature (4.6 kg / cm ² load): Measured according to ASTM D-648 with a molded product thickness of 3 mm. (4) Izod impact strength (with notch): ASTM D
It measured according to -256. (5) Tensile modulus: Measured according to ASTM D-638. (6) Tensile elastic modulus at the time of water absorption: An ASTM standard No. 1 dumbbell (thickness: 3 mm) was immersed in 23 ° C. water for 150 hours, and then measured according to ASTM D-638. (7) Weld portion elongation: Measured according to ASTM D-638 using an ASTM standard No. 1 dumbbell (3 mm) obtained by simultaneously injecting the resin so that the resin merges into the center.

Examples 1 to 7 and Comparative Examples 1 to 7 The same melting point of each component A (crystalline partially aromatic polyamide) as shown in Table 1 was measured using a coaxial 35φ twin screw extruder [TEX35, manufactured by Toshiba Corporation]. The cylinder temperature was set at a temperature 10-15 ° C higher. The screw rotation speed was fixed at 100 vpm. From the hopper side, the A component, the B component (ethylene-acrylate ester elastomer) shown in Table 2, the C component (polyolefin) shown in Table 3, and a release agent (calcium montanate 0.1) were used. 4PHR) and a heat stabilizer (Irganox B1171 0.5PHR). The strand discharged from the extruder nozzle was water-cooled and then cut (2.5φ × 2.5) with a cutter to obtain pellets for testing. After water cooling, the cut resin pellets were immediately dried with hot air at 130 ° C. for 3 hours to reduce the pellet moisture content to 0.1% or less. From the various resin pellets obtained, target test pieces were molded using a Toshiba IS-100 injection molding machine. Molding conditions: Cylinder temperature: Set to a temperature 10 to 15 ° C higher than the melting point of component A Mold surface temperature: Within the range of 60 to 70 ° C

[0024]

[Table 1]

[0025]

[Table 2]

[0026]

[Table 3]

Tables 4 to 6 show the results of measuring the physical properties of each of the obtained test pieces.

[0028]

[Table 4]

[0029]

[Table 5]

[0030]

[Table 6]

[0031]

As is clear from Table 4, in the crystalline partially aromatic polyamide (component A), 6T / 66 has excellent heat resistance (heat distortion temperature), but other polyamides have poor heat resistance. You can see that. Table 5 shows that the present invention (Examples 2 and 3) has good impact resistance and weld area elongation, but only the component A (Comparative Example 3) has impact resistance (Izod impact strength) and weld area elongation. It can be seen that if only the C component is blended to improve the impact resistance (Comparative Example 5), the impact resistance is greatly improved, but the weld elongation is not improved at all and decreases. Further, from Table 6, when the component C (polyolefin) was not added (Comparative Example 6)
It can be seen that the elastic modulus at the time of water absorption is greatly reduced, and that when a binary copolymer containing no maleic anhydride as the B component is used (Comparative Example 7), the weld characteristic elongation at the weld portion is low.
As described above, the composition of the present invention having such a configuration is excellent in heat resistance, impact resistance, weld elongation, tensile elasticity and chemical resistance, and can obtain a molded product having little change in physical properties and dimensions due to water absorption. It can greatly expand its applications and greatly contribute to the industry.

Claims (1)

[Claims] 1. A crystalline partially aromatic polyamide (A) comprising 65 to 85 parts by weight of a repeating unit represented by the following general formulas (I) and (II), and an ethylene-acrylate maleic anhydride copolymer (B) A) a polyamide resin composition comprising 10 to 35 parts by weight and 3 to 15 parts by weight of a polyolefin (C). Embedded image Embedded image (In the above general formula, n is 45 to 80% by weight, and m is 55 to 20% by weight.
Indicate weight%. )