JPH10265666A - Polyamide resin composition and self-tapping component made therefrom - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a resin composition having improved face impact resistance and self-tapping properties as well as the mechanical properties (e.g. rigidity) and heat resistance inherent in the constituent polyamide resin by melt-kneading a composition comprising the polyamide resin, glass fibers and an acid-modified elastomer in a specified ratio. SOLUTION: This composition is prepared by melt-kneading a composition comprising 28-78 wt.% polyamide resin, 20-70 wt.% glass fibers and 2-6 wt.% acid-modified elastomer and can give a molding having self-tapping properties including a return torque >=15 kg.cm and a return torque/failure torque >=0.5. The polyamide resin used is particularly desirably nylon 6 or nylon 66. The glass fibers are desirably ones having a means particle diameter of 3-11 μm and an aspect ratio of 250-500 when measured before the melt kneading. The composition can be desirably used for housing components of electric tools and casing components of machine components.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a polyamide resin composition having excellent mechanical properties, particularly excellent surface impact and self-tapping properties, and which can be suitably used for housing parts of electric tools and casing parts of mechanical parts. Things.

[0002]

2. Description of the Related Art Polyamide resin is an engineering plastic having excellent mechanical properties, heat resistance, chemical resistance and the like, and is widely used as an injection molding material for parts of automobiles, home appliances, office equipment, machines and the like. . However, there is a problem that the impact resistance is not sufficient for use as a housing part of a power tool or a casing part of a machine part.

Hitherto, as a method of improving the impact resistance of a polyamide resin, a method of blending an elastomer component with a polyamide resin has been proposed. For example,
Nos. 54-4743, 55-44108 and 58-23850
Japanese Patent Application Publication No. JP-A-2005-115, discloses a resin composition in which an olefin copolymer grafted with an α, β-unsaturated carboxylic acid compound represented by maleic anhydride is blended with a polyamide resin. JP-A-59-56451 discloses that a hydrogenated polymer of a conjugated diene or a copolymer of a hydrogenated copolymer of a conjugated diene and a vinyl hydrocarbon and a maleic anhydride is blended into a polyamide resin. Disclosed resin compositions. However, in these methods, when the blending amount of the elastomer component is increased, the impact resistance of the polyamide resin is sufficiently improved, but the rigidity and heat resistance are significantly reduced. On the other hand, when the blending amount of the elastomer component is reduced, there is a problem that the rigidity and heat resistance are maintained, but the impact resistance is not improved.

[0004]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned problems and improves the surface impact and self-tapping properties while maintaining the mechanical properties such as rigidity and heat resistance inherent in polyamide resin. It is intended to provide a polyamide resin composition.

[0005]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems, and as a result, blended a glass fiber having a specific fiber diameter and an aspect ratio with an acid-modified elastomer in a polyamide resin. By doing so, the inventors have found that the above object can be achieved, and have reached the present invention.

That is, the gist of the present invention is as follows. (1) A composition comprising 28 to 78% by weight of a polyamide resin, 20 to 70% by weight of glass fiber, and 2 to 6% by weight of an acid-modified elastomer (however, the whole composition is 100% by weight) is melt-kneaded. And a self-tapping property having the following characteristics. Return torque ≧ 15 kg · cm Return torque / fracture torque ≧ 0.5 (2) A component having a cell tapping property using the polyamide resin composition described in (1) above.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.

The polyamide resin in the present invention includes homopolyamide and copolyamide obtained by polymerization of lactam or aminocarboxylic acid and polycondensation of diamine and carboxylic acid, and mixtures thereof. Specifically, homopolymers such as nylon 6, nylon 11, nylon 12, nylon 66, nylon 610, nylon 612,
Or a copolymer or a mixture containing two or more of these components.
Is particularly preferred.

[0009] The relative viscosity of polyamide resin
It is preferably in the range of 1.5 to 4.0 as a value obtained by using 96% by weight concentrated sulfuric acid at a temperature of 25 ° C. and a concentration of 1 g / dl.
If the relative viscosity is less than 1.5, the mechanical strength of a molded product is reduced. On the other hand, if the relative viscosity exceeds 4.0, the moldability of the resin composition rapidly decreases, which is not preferable.

The glass fiber in the present invention is preferably a glass fiber before melt-kneading, having an average diameter of 3 to 11 μm and an aspect ratio (average length / average diameter) of 250 to 500. . Average diameter of glass fiber is 3μm
If it is less than 10 μm or more than 11 μm, a polyamide resin composition having improved surface impact properties and self-tapping properties cannot be obtained. When the aspect ratio is less than 250, the mechanical strength of the molded article is not sufficient, while when the aspect ratio exceeds 500, the moldability is reduced. Further, the average length of the glass fiber before melt-kneading is not particularly limited as long as the above-mentioned aspect ratio is satisfied, but usually the glass fiber is in the range of 0.75 to 5.5 mm.

It is necessary that the amount of the above glass fibers is in the range of 20 to 70% by weight. 20% by weight
If it is less than 30, the impact strength is not improved. On the other hand,
If it exceeds 70% by weight, the moldability is significantly reduced.

The acid-modified elastomer used in the present invention is used for the purpose of improving impact resistance. Specifically, a polyolefin comprising at least one of ethylene, propylene and butene is converted to an unsaturated carboxylic acid or a derivative thereof. Or an XYX block copolymer composed of a vinyl aromatic compound polymer block X and an olefin compound polymer block Y or an XY block copolymer modified with an unsaturated carboxylic acid or a derivative thereof, or Is used.

At this time, when modifying the polyolefin, the XYX block copolymer or the XY block copolymer with an unsaturated carboxylic acid or a derivative thereof, any of a random copolymerization method and a graft polymerization method can be used. Good.

Specific examples of the above-mentioned vinyl aromatic compound polymer block X include styrene, α-methylstyrene,
Examples include homopolymers of vinyl xylene, ethyl vinyl xylene, and vinyl naphthalene or copolymers thereof.

The olefin compound polymer block Y is a polymer of a conjugated diene compound such as butadiene, isoprene, 1,3-pentadiene, 2,3-dimethylbutadiene or a part of the unsaturated site thereof. Or a hydrogenated polymer, specifically, butadiene polymer, isoprene polymer, 1,3-pentadiene polymer, 2,3-dimethylbutadiene polymer, ethylene /
Examples include butylene polymers, ethylene / propylene polymers or mixtures thereof.

Further, specific examples of the above-mentioned unsaturated carboxylic acids or derivatives thereof include unsaturated mono- or dicarboxylic acids such as acrylic acid, methacrylic acid, maleic acid and fumaric acid, and amides, esters and metal salt compounds thereof. And acid anhydrides, which may be used alone or in combination of two or more.

Specific examples of the acid-modified elastomer include a maleic anhydride-modified ethylene-propylene copolymer, a maleic anhydride-modified ethylene-butene copolymer, a maleic anhydride-modified styrene-isoprene block copolymer, and a maleic anhydride-modified copolymer. Styrene-butadiene block copolymer, maleic anhydride-modified styrene-isoprene-styrene block copolymer, maleic anhydride-modified styrene-butadiene-styrene block copolymer, maleic anhydride-modified styrene-ethylene / butylene-styrene block copolymer And a maleic anhydride-modified styrene-ethylene / propylene-styrene block copolymer.

The compounding amount of the above acid-modified elastomer is 2
It needs to be in the range of ６6% by weight. When the amount is less than 2% by weight, the impact resistance is not improved. On the other hand, if the amount exceeds 6% by weight, the cell tapping property is not improved.

The polyamide resin composition of the present invention comprises the above polyamide resin, glass fiber and acid-modified elastomer.
Is melt-kneaded within the scope of the present invention, when a 12.7 mm thick prismatic molded product using this composition, the self-tapping property obtained by the method described below may have the above characteristics. is necessary.

Here, the self-tapping property means that a screw (self-tapping screw) is screwed to a boss portion or a hole of a molded product without using a female screw. The return torque is a force for loosening the screw, and the greater the return torque, the stronger the screwing. Further, the breaking torque is a force at which a molded product breaks when screwed, and the larger the breaking torque, the stronger the tightening.

Next, a method for producing the resin composition of the present invention will be described. In the present invention, the method of blending the polyamide resin, glass fiber and acid-modified elastomer is not particularly limited, as long as each component is uniformly dispersed. Specifically, a glass fiber and an acid-modified elastomer are added to a polyamide resin, uniformly blended by a tumbler or a Henschel mixer, and then pelletized by an extruder and molded.

When pelletizing with an extruder, usually,
A method is employed in which the polyamide resin, glass fiber, and acid-modified elastomer are supplied collectively from the first supply port and melt-kneaded. Further, a method is also employed in which the polyamide resin and the acid-modified elastomer are supplied from the first supply port and melt-kneaded, and then the glass fibers are supplied from the second supply port and further melt-kneaded.

As a method for molding the polyamide resin composition of the present invention, an injection molding method is generally applied. By this method, a housing part (FIG. 1) of a power tool and a casing part of a mechanical part are produced. Can be.

Further, the polyamide resin composition of the present invention may contain a pigment, a heat stabilizer, an antioxidant, a weathering agent, a flame retardant, a plasticizer, a release agent, and a glass fiber as long as its properties are not significantly impaired. Can also be added.

As the heat stabilizer and the antioxidant, for example, hindered phenols, phosphorus compounds, hindered amines, sulfur compounds, copper compounds and the like are used. As the weathering agent, for example, benzophenones, benzotriazoles and the like are used. As the flame retardant, for example, a phosphorus-based flame retardant or a halogen-based flame retardant is used.

Further, as a reinforcing material, for example, clay, talc, calcium carbonate, zinc carbonate, wollastonite, silica, alumina, magnesium oxide, calcium silicate, sodium aluminate, calcium aluminate,
Sodium aluminosilicate, magnesium silicate, aluminum hydroxide, calcium hydroxide, barium sulfate, potassium bright bun, sodium bright bun, iron bright bun, glass balloon, carbon black, zinc oxide, antimony trioxide,
Boric acid, borax, zinc borate, zeolite, hydrotalside, metal fibers, metal whiskers, ceramic whiskers, potassium titanate whiskers, boron nitride,
Mica, graphite, carbon fiber and the like are used.

[0027]

Next, the present invention will be described more specifically with reference to examples. In addition, the measuring method of the physical property value in an Example and a comparative example is as follows. (a) Flexural strength, flexural modulus and flexural rupture strain Measured according to ASTM-D790 using a 3.2 mm thick test specimen. (b) Tensile Rupture Strength and Tensile Rupture Elongation A test piece having a thickness of 3.2 mm was measured based on ASTM-D638. (c) Izod impact strength A 3.2 mm thick notched test piece was used and measured according to ASTM-D256. (d) Surface impact fracture height The height at which cracks and cracks occur when a 300 g steel ball was dropped was determined based on the Dupont falling ball impact test method. (e) Self-tapping property Drill a prepared hole of 4.6 mmφ into a 12.7 mm thick prismatic product, tighten the M5 type 1 tapping screw with a torque of 30 kg · cm, and leave it at 23 ° C and 50% RH for 24 hours. The return torque of
It was measured with a torque driver (manufactured by Tonichi Seisakusho). Similarly, tighten an M5 type 1 tapping screw into a drilled pilot hole of 4.6 mmφ to make it idle (torque torque).
Was measured with a torque driver (manufactured by Tonichi Seisakusho).
The self-tapping property is better as the return torque and the ratio of the return torque / breaking torque are larger.

Example 1 Nylon 6 resin having a relative viscosity of 2.5 (A1030-BRL, manufactured by Unitika Ltd.) 66% by weight as a polyamide resin, average diameter 10 μm
Glass fiber with an aspect ratio of 300 (made by Nippon Electric Glass Co., Ltd.
T249-GH) 30% by weight, and 6% by weight of maleic anhydride-modified ethylene-butene copolymer (Tuffmer MA8510, manufactured by Mitsui Petrochemical Industries, Ltd.) as an acid-modified elastomer were mixed in a blender, and the cylinder temperature was reduced to 250 ° C. Set inner diameter 35mm
After melt-kneading with a twin screw extruder (PCM-30, manufactured by Ikegai Iron Works Co., Ltd.), the mixture was extruded into strands, pelletized, and vacuum-dried. The pellets were supplied to an injection molding machine (IS-80, manufactured by Toshiba Machine Co., Ltd.) in which the cylinder temperature was set to 250 ° C. to prepare various test pieces, which were subjected to a physical property test.

Example 2 Various test pieces were prepared in the same manner as in Example 1 except that the mixing ratios of the materials were as shown in Table 1, and subjected to physical property tests.

Example 3 Instead of a nylon 6 resin having a relative viscosity of 2.5, a relative viscosity was used.
2.7 nylon 66 resin (DuPont, Zytel 101)
Various test pieces were prepared in the same manner as in Example 1 except for using, and subjected to physical property tests.

Example 4 Various test pieces were prepared in the same manner as in Example 3 except that the mixing ratios of the materials were as shown in Table 1, and subjected to physical property tests.

Comparative Example 1 A glass fiber (T289, manufactured by Nippon Electric Glass Co., Ltd., having an average diameter of 13 μm and an aspect ratio of 230) was used in the same manner as in Example 1 except that the compounding ratio of the materials was as shown in Table 1. To prepare various test pieces, which were subjected to physical property tests. Since the average diameter of the glass fiber was out of the range of the present invention, the molded article using this composition was inferior in return torque and return torque / fracture torque.

Comparative Example 2 Various test pieces were prepared in the same manner as in Example 1 except that the mixing ratios of the materials were as shown in Table 1, and subjected to physical properties tests. The molded article using this composition was inferior in the values of the return torque and the return torque / breaking torque because the amount of the acid-modified elastomer was out of the range of the present invention.

Table 1 shows the results of Examples 1-4 and Comparative Examples 1-2.

[0035]

[Table 1]

[0036]

According to the present invention, it is possible to obtain a polyamide resin composition having significantly improved surface impact properties and self-tapping properties and excellent mechanical properties such as bending strength and tensile breaking strength.

[Brief description of the drawings]

FIG. 1 is a part of a housing part of a power tool.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Yoshiteru Nagai 31-3 Uji Hinojiri, Uji City, Kyoto Prefecture Unitika Uji Plastic Factory

Claims (3)

[Claims] 1. A composition comprising 28 to 78% by weight of a polyamide resin, 20 to 70% by weight of glass fiber and 2 to 6% by weight of an acid-modified elastomer (100% by weight of the whole composition is melted). A polyamide resin composition obtained by kneading and having the following properties of self-tapping property. Return torque ≧ 15kg ・ cm Return torque / breaking torque ≧ 0.5 2. The glass fiber before melt-kneading has an average diameter of 3
~ 11μm, aspect ratio (average length / average diameter)
The polyamide resin composition according to claim 1, which has a molecular weight of 250 to 500. 3. A component having cell tapping properties, comprising the polyamide resin composition according to claim 1 or 2.