JP2553093B2 - Polyamide resin composition for power transmission parts - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a polyamide resin composition for power transmission parts, particularly good moldability, excellent heat resistance, low friction coefficient and high mechanical strength. The present invention relates to a polyamide resin composition useful as a molding material for a power-transmitting component such as a gear material and a bearing material that gives wear to a molded article and is subject to wear.

(Prior Art and Problems Thereof) Nylon resin, casting nylon, polyacetal resin and the like are known as plastic materials used for power transmission parts with sliding friction such as gear materials and bearing materials.

However, plastic materials used for this type of application have high softening temperature to withstand the heat generated by sliding friction, high tensile strength, and high elongation impact value, as well as particularly for dynamic shearing load. It has excellent mechanical properties such as high fatigue limit to withstand, and the coefficient of friction is low throughout the whole regardless of the magnitude of friction speed and the temperature of the friction surface, so the machine can be operated lightly and heat generation on the friction surface is minimal. It is necessary to satisfy the following requirements: good friction characteristics, small wear and deformation of the friction surface, excellent thermal stability at high temperatures, thermoplasticity, good flowability and easy molding. It

However, for this kind of general-purpose plastic material, nylon resin, casting nylon, polyacetal resin, etc. have been put on the market as described above and have been generally used, but these do not sufficiently have the above-mentioned properties, The coefficient of friction is not sufficiently small. In particular, nylon resins and casting nylons are small at room temperature, but have the drawback of rapidly increasing friction as the temperature rises.

Therefore, for this type of resin, the addition of mineral type anti-friction agents such as molybdenum disulfide, graphite, etc. or Teflon resin showing a low coefficient of friction has been added, but the addition of mineral type anti-friction agents is too hard. Since it is buried in the material plastic, it has no effect, and the addition of the Teflon resin has the drawback that it cannot withstand a large load because the Teflon resin has a low strength. In addition, oil-filled plastics, in which finely divided lubricant oil is dispersed in fabric plastics, are also on the market, but this lubricant loses its lubrication effect during long-term use, and wear progresses. There is a drawback that.

In addition, in the above various compositions, the lubricant and the base plastic do not adhere to each other or are compatible with each other, and the mechanical strength of the lubricant cannot be expected. However, a long-life low-friction plastic material capable of withstanding a high load has not been obtained at present because of the drawback that it is significantly impaired.

Further, as a method of modifying a polyolefin resin with a polyamide resin to make them compatible with each other, a method using an ionomer resin modified with methacrylic acid (Japanese Patent Publication No. 42-12546), alkoxysilane modification with methacrylsilane, and further glycidide A method of compatibilizing polyolefin by glycididoxy modification using xysilane (Japanese Patent Publication No. 55-20
No. 500) is disclosed, and all of them are intended to improve impact resistance, but they have little effect on low friction and have a drawback that the strength of nylon resin is remarkably lowered.

(Means for Solving the Problems) The present invention relates to a polyamide resin composition for power transmission parts, which solves such disadvantages.
0 parts by weight, 0 to 10 parts by weight of polyolefin resin, 2 to 20 parts by weight of aminosiloxy modified polyolefin resin, and 0.04 to 2 parts by weight of silica fine powder are mixed and kneaded by heating.

That is, the present inventor has conducted various studies on the development of a polyamide resin composition that provides a molded article for a power transmission part having excellent heat resistance, a small friction coefficient, and a large mechanical strength, and as a result, a polyamide resin and a polyolefin resin that are originally incompatible with each other. When aminosiloxy modified polyolefin resin is added to and kneaded by heating, the amino group in the aminosiloxy modified polyolefin resin becomes a functional group and the polyamide resin and aminosiloxy modified polyolefin resin are compatible with each other, and the polyolefin resin and the aminosiloxy modified polyolefin resin are mixed. Since it is also compatible, the results show that the strength is not much lower than that of the polyamide resin, the impact resistance is improved, and a composition having low friction is obtained, and the type of each component used here, The present invention was completed by conducting research on the amount added.

The polyamide resin as a main material constituting the polyamide resin composition for power transmission components of the present invention (hereinafter referred to as the composition of the present invention) is commercially available as nylon-6, nylon 6-6, nylon 4-6. However, it is preferable to use nylon 6-6 and nylon 4-6, which have relatively high melting points and excellent thermal stability.

The polyolefin resin blended with this polyamide resin includes low density polyethylene, high density polyethylene,
An ethylene-propylene copolymer and the like are exemplified, but this may be a mixture thereof. This polyolefin resin may not be added depending on the amount of the aminosiloxy-modified polyolefin resin to be described later, but if it is 10 parts by weight or more with respect to 100 parts by weight of the above-mentioned polyamide resin, a molded article made from this composition Since the strength and softening temperature are lowered, and the aminosiloxy-modified polyolefin resin is not compatible with each other, it is necessary to set the amount to 10 parts by weight or less, and it is preferable to set the amount to half or less of the aminosiloxy-modified polyolefin resin, but particularly preferably 3 parts by weight or more, 5
It is preferable that the amount is not more than parts by weight.

Next, the aminosiloxy-modified polyolefin resin constituting the composition of the present invention is a method of copolymerizing low-density polyethylene and vinylalkoxysilane (US Pat. No. 3,
No. 075,948), and an alkoxy produced by a method of reacting polyvinyl alcohol with γ-methacryloxypropyltrialkoxysilane on polyolefin in the presence of an organic peroxide by heating (see Japanese Patent Publication No. 48-1171). It can be obtained by adding aminoalkoxysilane to a silane-modified polyolefin resin and heating it.

The composition of the present invention, instead of using this aminosiloxy-modified polyolefin resin, an alkoxysilane-modified polyolefin resin and an aminoalkoxysilane are added to the above-mentioned polyamide resin or a mixture of a polyamide resin and a polyolefin resin, and at the time of heating and kneading. The alkoxysilane-modified polyolefin resin may be reacted with an aminoalkoxysilane to form an aminosiloxy-modified polyolefin resin.

Regarding this alkoxysilane-modified polyolefin resin, alkoxysilane-modified polyethylene resin LINKRON HF700 (trade name of Mitsubishi Petrochemical Co., Ltd.) and alkoxysilane-modified polypropylene LINKRON XPM800H (same as above) are available.
As aminoalkoxysilane, N-β (aminoethyl) -γ-aminopropyltrimethoxysilane ・ KBM603
(Trade name, manufactured by Shin-Etsu Chemical Co., Ltd.), γ-aminopropyltriethoxysilane, KBE903 (same as above).

The above-mentioned reaction between the alkoxysilane-modified polyolefin resin and the aminoalkoxysilane is easily carried out by the moisture evaporated from the hygroscopic polyamide resin, but since the alkoxysilane-modified polyolefin resin has self-crosslinking property, this reaction system 2 to 10 parts by weight with respect to 100 parts by weight of alkoxysilane-modified polyolefin resin, that is, 0.04 with respect to 100 parts by weight of polyamide resin.
When ~ 2 parts by weight of silica fine powder is added, amino-modification reaction is promoted through this silica fine powder to prevent self-crosslinking, and further, an auxiliary effect is given, and liquid aminoalkoxysilane is previously added. The convenience of the mixing operation is also given that the fine silica powder can be absorbed.

Since the aminosiloxy-modified polyolefin resin or the alkoxysilane-modified polyolefin resin for synthesizing the aminosiloxy-modified polyolefin resin is required to be compatible with the above-mentioned polyolefin resin, when the polyolefin resin is polyethylene, the aminosiloxy-modified polyolefin resin is modified. Polyethylene, alkoxysilane modified polyethylene,
The polyolefin resin is an ethylene-propylene copolymer,
In the case of polypropylene, it is preferable to use aminosiloxy modified polypropylene or alkoxysilane modified polypropylene.

When the amount of the aminosiloxy-modified polyolefin resin is 2 parts by weight or less with respect to 100 parts by weight of the polyamide resin, the effect of low friction and the effect of compatibility with the polyolefin resin are lost, and when it is 20 parts by weight or more, the strength and the softening temperature are increased. Therefore, it is required to be in the range of 2 to 20 parts by weight, and the preferable range is 5 to 15 parts by weight.

The composition of the present invention comprises a polyamide resin, an aminosiloxy-modified polyolefin resin and silica fine powder, or a polyamide resin, an alkoxysilane-modified polyolefin resin and an aminoalkoxysilane-absorbed silica fine powder. Can be obtained by mixing and heating and kneading a predetermined amount of the mixture, but this heating does not allow uniform kneading at 220 ° C. or lower, and aminosiloxy modification does not occur. Oxidation, aminoalkoxysilane, and polyolefin self-crosslinking
It is recommended that the temperature be in the range of 220 to 300 ° C.

This kneading device is preferably a closed system to prevent evaporation of aminoalkoxysilane during heating, and after completion of kneading, alcohol produced by the reaction between the alkoxysilane-modified polyolefin resin and aminoalkoxysilane is discharged. Since it is necessary, it is suitable to use a twin-screw or more extruder with a vent.

In addition, the composition of the present invention, for the purpose of increasing the rigidity of the molded product obtained from this, to improve the static strength,
To this, glass powder, inorganic powder such as titanium powder potassium whiskers, it is optional to add a fibrous material, but the addition amount of these is within the range not to lose the flexibility and moldability of the composition. Therefore, 100 parts by weight or less, and preferably 10 to 30 parts by weight, relative to 100 parts by weight of the composition.

The composition of the present invention thus obtained, polyamide resin and aminosiloxy modified polyolefin resin, further because the polyolefin resin is compatible, excellent heat resistance, small friction coefficient, mechanical strength It is useful as a molding material for large-sized molded products, especially for power transmission parts with friction such as gear materials and bearing materials. Further, it has good thermal stability and long residence time in the molding machine. However, there is an advantage that it can be molded by a plunger type injection molding machine which is inexpensive and suitable for small-scale production.

(Examples) Hereinafter, specific embodiments of the present invention will be described with reference to synthesis examples, examples, and comparative examples. In each example, "part" represents "part by weight", and the physical property values in the examples are as follows. It is measured by the following test method.

[Test method] Mechanical strength: 1) Tensile strength The strength at normal temperature (23 ° C) and 100 ° C was measured using a JIS No. 2 test piece at a tensile speed of 10 mm / min.

2) Impact strength 7 mm wide, 10 mm thick, 90 mm long test piece (No. 5 test piece)
The Charpy impact value was measured according to the test method of JIS K 7111 (Annex 3).

・ Heat resistance: 1) Thermal deformation temperature Thermal deformation temperature at bending stress of 18.6 kg / cm ² (JIS K 7
207).

2) Pyrolysis temperature When 50mg of sample was put in a thermobalance and heated at a rate of 10 ° C / min in a nitrogen stream of 300cc / min, the sample was thermally decomposed, decomposed gas was generated, and the weight rapidly The temperature is shown to start decreasing.

Friction (coefficient of kinetic friction): Using a Taber type friction tester (Toyo Baldwin Co., Ltd. Suzuki type wear tester), a disc-shaped test piece with a diameter of 50 mm and a thickness of 6 mm was used, and a cross-sectional area of 2 cm in a static state ² cylindrical steel friction pieces
Press with a load of 50 kgf, rotate the test piece to increase the friction speed in stages, and measure the temperature rising by friction heat with a thermocouple embedded in the friction piece, the temperature of the friction surface is 60 ° C, 120 ° C, 200 ° C
The friction coefficient at that time was measured with a torque meter.

・ Practical test on spur gears: M1 × 50 sheets made of the test material, 10mm thick spur gears with a diameter of 20
It is attached coaxially to a 0 mm pulley, and a weight of 10 kg is hung on the pulley with a wire (stationary torque 1.0 kgf-m). A spur gear of the same size made of steel that meshes with this test gear is attached to the worm gear reducer (reduction ratio 1 / 50) to move the weight up and down by reciprocating rotation, stop the brake when the weight stops at the lowest point, apply an impact force to the test gear, and attach this impact force to the test gear Measured as a torque with a strain gauge attached to the shaft (in the experimental device, the impact torque when stopped was 4 times that at rest, 4 kgf-m), and this reciprocating motion was repeated to operate by breaking or deforming the gear. The number of times until it became impossible was measured.

・ Practical test using worm gear: M1 x 50 sheets made of the test material, thickness of 10 mm, β = 3 ° 30 'Worm gear and steel (S45C) 1-worm shaft As with a spur gear, a static torque of 1.0 kgf-m in grease lubrication and 0.5 kgf-m in unlubricated dry condition was applied to the worm gear by a weight, and the worm was reciprocated at 1,000 rpm. Raise and lower the weight (braking torque at stop is 3 kgf-m
And 1.5 kgf-m), the number of times the worm gear is cycled until it becomes inoperable due to breakage or deformation of the worm gear is measured. The shaft temperature increased.

[Synthesis example] Alkoxysilane-modified polyethylene LINKRON HF70
Extruder is mixed with 100 parts of 0 (previously mentioned), 5 parts of Aerosil # 380 (trade name of Nippon Aerosil Co., Ltd.), a silica fine powder in which 10 parts of γ-aminopropyltriethoxysilane KBE903 (previously described) is absorbed. And knead at 220 ℃, and 107 parts aminosiloxy modified polyethylene (10% modification) and silica fine powder 5
A mixture with parts was obtained.

[Examples 1 to 8 and Comparative Examples 1 to 11] For Examples 1 to 8 and Comparative Examples 1 to 10, the respective compositions having the formulations shown in Tables 1A and 2A were injected at an injection pressure of 200 to 400.
Test pieces were prepared by injection using a plunger type injection molding machine of kg / cm ² . In Comparative Example 11, a MC nylon round bar (manufactured by Nippon Polypenco Co., Ltd.) was cut as a casting nylon to prepare a test piece.

When the above measurement was performed for each test piece,
The results shown in the table and Table 2B were obtained.

 The details of each component used are as follows.

[Details of Ingredients] Polyamide resin: Nylon resin 6-6 2020U (trade name by Ube Industries, in the table, nylon 66) Nylon resin 4-6 TS300 (trade name by DSM, Netherlands, table, Nylon 46) -Polyolefin resin: High-density polyethylene Novatec JP200 (trade name of Mitsubishi Kasei Co., Ltd.) Ethylene propylene copolymer-Aminosiloxy-modified polyolefin resin: Aminosiloxy-modified polyethylene resin obtained in Synthesis Example and silica fine (107: 5) mixture with powder ・ Alkoxysilane-modified polyolefin resin: Alkoxysilane-modified polyethylene ・ Linklon HF70
0 (previous) Alkoxysilane-modified polypropylene Wrinklon XP
M800H (previously) -Aminoalkoxysilane: γ-aminopropyltriethoxysilane-KBE903 (previously) N-β (aminoethyl) -γ-aminopropyltrimethoxysilane-KBM603 (previously) -Silica fine powder ... Aerosil 360 (Nippon Aerosil Co., Ltd. product name) Potassium titanate whiskers ... Tismo (Otsuka Chemical Co., Ltd. product name) -Calcium carbonate ... SB Whiten (Shiraishi Calcium Co., Ltd. product name) -γ-glycididoxypropylmethoxysilane ... KBM403
(Product name manufactured by Shin-Etsu Chemical Co., Ltd.)-Ionomer resin ... Himilan 1652 (Product name manufactured by Mitsui Polychemicals Co., Ltd.)-Teflon powder ... CFC L169 (Product name manufactured by Asahi Fluoro Co.)-Acetal resin ... Duracon M90 (Product manufactured by Polyplastics Co., Ltd.) Name)

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Claims (1)

(57) [Claims] 1. A method comprising mixing 100 parts by weight of a polyamide resin, 0 to 10 parts by weight of a polyolefin resin, 2 to 20 parts by weight of an aminosiloxy-modified polyolefin resin, and 0.04 to 2 parts by weight of silica fine powder and heating and kneading the mixture. A polyamide resin composition for power transmission parts.