JPH0782476A - Polyamide resin composition - Google Patents

Abstract

(57) [Summary] [Object] To provide a polyamide resin composition capable of giving a molded product having a low sliding friction coefficient, a low amount of rough wear, and a sufficiently high fatigue limit against continuous load such as repeated fatigue. [Structure] (A) 85 to 95 parts by weight of polyamide resin and (B) 5 to 15 parts by weight of wollastonite to 100 parts by weight in total, (C) unsaturated glycidyl compound or unsaturated carboxylic acid and / or unsaturated Modified styrene-based copolymer modified with saturated dicarboxylic acid anhydride 3 to 10 parts by weight, and (D) unsaturated glycidyl compound or unsaturated carboxylic acid and / or weight average molecular weight modified with unsaturated dicarboxylic acid anhydride A polyamide resin composition containing 0.5 to 5 parts by weight of modified high-density polyethylene of 0.5 to 400,000 and at least one of (C) and (D) being modified with an unsaturated glycidyl compound.

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 for sliding parts, and more specifically, it provides a sliding part having a low coefficient of sliding friction, a small amount of roughness and wear, and a low performance deterioration due to repeated fatigue. To obtain such a reinforced polyamide resin composition.

[0002]

2. Description of the Related Art Polyamide is widely used for sliding parts such as gears and cam bearings because it has excellent mechanical properties and wear resistance. Plastic materials used for this type of application have low sliding friction coefficient, low roughness and wear, and excellent mechanical properties such as high fatigue limit to withstand continuous loads such as repeated fatigue. High It is necessary to satisfy that molding is easy.

However, conventionally used polyamide resins and the like do not sufficiently have the above characteristics,
In particular, there are problems that the amount of rough wear cannot be suppressed to a low level and that the fatigue limit for withstanding continuous loads such as repeated fatigue is not sufficient.

For this reason, polyamide resins mixed with Teflon resin, silicone oil, mineral oil, high-density polyethylene, etc. are commercially available for the purpose of lowering the friction coefficient, but these additives are polyamide resins. Since they are not compatible with each other or do not bond at the interface, the amount of rough wear is still large, and the fatigue limit for withstanding continuous loads such as repeated fatigue is insufficient.

On the other hand, another polyamide resin composition proposed by adding a mixture of ethylene / propylene / 1,4-hexadiene and ethylene / maleic anhydride to a polyamide resin (JP-A-51-143061) is proposed. As a result of improved impact resistance, the fatigue limit for withstanding continuous loads such as repeated fatigue is somewhat improved, but the amount of rough wear is not reduced.

[0006]

The present invention solves the above-mentioned problems of the prior art, and can provide a molded article having a low sliding friction coefficient, a rough wear amount, and a sufficiently high fatigue limit against a continuous load such as repeated fatigue. It is an object to provide a polyamide resin composition.

[0007]

Means for Solving the Problems In the present invention which was able to solve the above-mentioned problems, the polyamide resin composition comprises (A) polyamide resin of 85 to 95 parts by weight and (B) wollastonite of 5 to 15 parts by weight. For 100 parts by weight in total,
(C) 1 to 30 parts by weight of a modified styrenic copolymer modified with an unsaturated glycidyl compound or an unsaturated carboxylic acid and / or an unsaturated dicarboxylic acid anhydride, and (D) an unsaturated glycidyl compound or an unsaturated carboxylic acid Acid and /
Alternatively, modified high density polyethylene having a weight average molecular weight of 5 to 400,000 modified with an unsaturated dicarboxylic acid anhydride is 0.5 to
It is contained in an amount of 10 parts by weight, and the gist is that at least one of (C) and (D) is modified with an unsaturated glycidyl compound.

[0008]

In the present invention, one or more types of polyamides such as nylon 6, 6, 6, 6, 10, 11, 12 and the like known as polyamide resins can be used in a non-limiting manner, and the proper amount of the polyamide is 85-85. 95 parts by weight. The (B) wollastonite used in the present invention is an inorganic filler, and commercially available products can be used. The preferable amount of wollastonite used is 5 to 15 parts by weight, and the total amount with the polyamide is 100 parts by weight. When the wollastonite is less than 5 parts by weight, the mechanical properties and thermal properties are insufficient, while when it exceeds 15 parts by weight, it is difficult to obtain a molded product having a good surface and the abrasion resistance is impaired. A more preferable amount of use is 5 to 10 parts by weight.

In the polyamide resin composition of the present invention, in addition to the above polyamide and wollastonite, at least one is modified with an unsaturated glycidyl compound, a modified styrene copolymer (C) and a modified high density polyethylene (D). Is included as an essential component. These components contribute to the improvement of friction characteristics and fatigue limit.

The styrene copolymer is a styrene block copolymer having a known S (styrene) -B (butadiene) -S type symmetric block structure. S and B
Are polymer blocks, and the central block B is
Polyisoprene may be used, but polybutadiene is preferred. In addition, it is recommended that a part of double bonds in polybutadiene be saturated alkyl groups (ethylene chains) by hydrogenation (SEBS). Both end blocks S are
It shows a polymer block of aromatic hydrocarbon, and is preferably a block made of polystyrene. The molecular weight of the terminal block S is 4000 to 115000, more preferably 500.
0 to 15,000, the molecular weight of the central block B is 20,000
˜45,000, more preferably 25,000 to 10,000
It is preferably 0.

Such hydrogenated styrenic block copolymers can be easily obtained on the market, for example, "Clayton G1650" and "Clayton G165" from Shell Chemical.
1 ”,“ Clayton G1657 ”and the like are commercially available.

The high-density polyethylene before modification in the present invention means a molecular weight of 5 to 400,000 and a density of 0.94 kg / cm.
Means ² or more high density polyethylene. If the molecular weight is less than 50,000, the wear resistance of the resulting molded article will be insufficient,
When the molecular weight exceeds 400,000, molding becomes difficult, which is not preferable. The high-density polyethylene used in the present invention is another monomer within a range that does not impair its properties, for example, α-olefins such as propylene, butene-1, pentene, 4-methylpentene-1, hexene, octene and decene. Dienes such as butadiene and isoprene, cycloolefins such as cyclopentene, cyclohexene and cyclopentadiene, and acrylates such as methyl acrylate, ethyl acrylate and butyl acrylate may be copolymerized.

Examples of unsaturated glycidyl compounds for modifying these styrene-based copolymers and high-density polyethylene include glycidyl methacrylate, glycidyl acrylate, acryl glycidyl ether, and glycidyl itaconate. Of these, glycidyl methacrylate is preferred. . Examples of the unsaturated carboxylic acid or unsaturated dicarboxylic acid anhydride include unsaturated carboxylic acids such as acrylic acid, methacrylic acid, crotonic acid and oleic acid, and unsaturated acids such as maleic anhydride, itaconic anhydride and citraconic anhydride. Examples thereof include dicarboxylic acids, and one or more of these can be used. Maleic anhydride is particularly preferable. For the purposes of the present invention, unsaturated glycidyl compounds are preferred, and it is necessary that at least one of the styrene copolymer and the high-density polyethylene is modified with the unsaturated glycidyl compound.

The modification reaction of the styrene-based copolymer or high-density polyethylene with the unsaturated glycidyl compound or unsaturated carboxylic acid anhydride and / or unsaturated carboxylic acid is carried out during polymerization. In the presence of a product, the above is mixed with a styrene-based copolymer or high-density polyethylene, and the mixture is mixed with an extruder, a mixer, or the like at 100 to 2
It can be carried out by kneading at 50 ° C. for 1 to 10 minutes. The unsaturated glycidyl compound is preferably copolymerized, and the unsaturated acid is preferably graft modified. The amount of the compound was 0. 0, based on the styrene copolymer or the high-density polyethylene.
1 to 10 parts by weight is preferable. It is considered that the reason why the modification with the unsaturated glycidyl compound is effective is not clear, or that the glycidyl group can react both at the carboxyl group terminal and the amino group terminal of the polyamide resin, so that the binding property is improved.

The modified styrenic copolymer (C) is (A)
The polyamide resin and (B) wollastonite are added in an amount of 1 to 30 parts by weight based on 100 parts by weight in total. If it is less than 1 part by weight, no improvement in repeated fatigue properties is observed, and if it is more than 30 parts by weight, the amount of rough wear increases. Further, the amount of the modified high-density polyethylene (D) to be blended is (A) +
(B) = 0.5 to 10 parts by weight with respect to 100 parts by weight. If the amount is less than 0.5 parts by weight, the wear resistance of the molded product is insufficient, and if the content exceeds 10 parts by weight, mechanical properties such as rigidity of the molded product deteriorate and heat resistance also decreases. Not preferable.

In the resin composition of the present invention, in order to further improve the sliding characteristics, that is, the friction and wear characteristics of a molded product, in addition to the above four components, carbon fiber, fluororesin powder, and Additives such as molybdenum sulfide and glass beads can be added. Also, the mechanical properties of the molded product,
In order to improve electrical properties, fillers such as calcium carbonate and barium sulfate, whiskers such as potassium titanate,
A conductivity-improving filler such as carbon black or metal powder can be added within a range that does not impair the sliding characteristics of the resin molded product. Further, within a range that does not impair the sliding properties of the resin molded product, a deterioration inhibitor against oxygen, heat, ultraviolet rays, etc., a stabilizer, a lubricant, a plasticizer, a flame retardant, an antistatic agent, a colorant, a release agent, etc. You may add.

The resin composition in the present invention is produced by kneading the components using a device such as a single-screw extruder, a twin-screw extruder, a kneader or a twin-screw roll. There are no particular restrictions on the type of kneading machine used or the kneading conditions.

[0018]

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. In addition, each physical property of the polyamide resin molded articles obtained in each of the following examples was measured based on the following test methods.

Slip-friction resistance: S-45C steel (friction area 1.
6 cm ² ), friction speed 10 cm / s, load 40 k
Friction coefficient μ when continuously operated for 1 hour under the condition of g / cm ²
I asked. Grain wear resistance: Using a Taber Mammo tester, H-18 was used as the theory of wear, and the amount of wear mg of the resin molded product after 1000 rotations was determined.

Repeated Fatigue Property: A flexural fatigue tester shown in FIG. 1 was prepared, and a resin molded product as a sample (10 mm width 1 m
The number of cycles until abnormalities (wrinkles, whitening, cracks, etc.) occurred in the appearance of (m thickness) was measured. The stroke between chucks is 68 mm (maximum 70 mm, minimum 2 mm).

Examples 1 to 3, Comparative Examples 1 to 6 Nylon 6 (RV = 2.5) was used as the polyamide resin.
SEBS1 (styrene content 20%) and SEBS2 (styrene content 40%) as styrene-based copolymers before modification
Further, as the high density polyethylene before modification, polyethylene having a weight average molecular weight of 140,000 was used. Modification of styrene copolymer and high-density polyethylene is carried out by using 2,5-dimethyl-2,5-di (t-butylperoxy) hexane as a peroxide (Perhexin 25B, manufactured by NOF CORPORATION).
0.3% by weight and 3% by weight of glycidyl methacrylate or 1% by weight of maleic anhydride were added and melt-mixed at 240 ° C. for 3 minutes to obtain a modified product.

PEGMA is a modified product having a weight average molecular weight of about 100,000 obtained by copolymerizing 5% by weight of glycidyl methacrylate with ethylene. Predetermined amounts of the respective components shown in Tables 1 and 2 were blended using a 30 mm twin-screw extruder to produce pellets. Cylinder temperature is 265
℃ was made. The obtained pellet was vacuum dried at 70 ° C. for 16 hours. The pellets were molded into test pieces by an injection molding machine adjusted to a cylinder temperature of 265 ° C. and a mold temperature of 80 ° C., and the evaluation results are shown in Tables 1 and 2.

[0023]

[Table 1]

[0024]

[Table 2]

[0025]

EFFECTS OF THE INVENTION The polyamide resin composition of the present invention has a low coefficient of sliding friction, a small amount of roughness and wear, and little deterioration in performance due to repeated fatigue. Therefore, the polyamide resin composition is suitable for dynamic applications such as gears, cams and bearings. Very useful as a material.

[Brief description of drawings]

FIG. 1 is a schematic explanatory diagram of a measuring device for evaluating repeated fatigue characteristics.

Claims (1)

[Claims] 1. A total of 10 parts of (A) 85 to 95 parts by weight of polyamide resin and (B) 5 to 15 parts by weight of wollastonite.
1 to 30 parts by weight of (C) an unsaturated glycidyl compound or a modified styrene copolymer modified with an unsaturated carboxylic acid and / or an unsaturated dicarboxylic acid anhydride, and (D) an unsaturated compound. It contains 0.5 to 10 parts by weight of a modified high-density polyethylene having a weight average molecular weight of 5 to 400,000 modified with a glycidyl compound or an unsaturated carboxylic acid and / or an unsaturated dicarboxylic acid anhydride. At least one of D) is modified with an unsaturated glycidyl compound, wherein the polyamide resin composition is characterized.