JPH04239057A - Polyamide resin composition - Google Patents

Abstract

PURPOSE:To obtain the title compsn. excellent in sliding properties, mechanical properties, and heat resistance and useful for a sliding member by compounding a polyamide 46 resin with carbon fiber and an organopolysiloxane each in a specified amt. CONSTITUTION:The title compsn. comprises 94.7-38wt.% polyamide 46 resin, 5-50wt.% carbon fiber with a diameter of 0.1-30mum and a length of 0.1-20mum, pref. prepd. from polyacrylonitrile filament, and treated with a binder and a coupling agent, and 0.3-12wt.% organopolysiloxane (e.g. polydimethylsiloxane).

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 having excellent sliding properties, heat resistance and mechanical properties. More specifically, the present invention relates to a polyamide resin composition with excellent sliding properties suitable for electrical equipment parts, mechanical parts, and the like.

0002

[Prior Art] Polytetramethylene adipamide resin (hereinafter referred to as polyamide 46 resin) has excellent heat resistance, mechanical properties, and chemical resistance, and is superior to other engineering plastics. Due to its excellent self-lubricating properties, it is expected to be widely put into practical use as a sliding member for automobiles, electrical equipment, office automation equipment, etc. as a replacement for metals in response to the recent need for lighter equipment. Recently, the use of plastic sliding parts has expanded to include non-lubricated bearings that are subjected to severe loads and severe wear, pushers used under high ambient temperatures, and thin-walled sliding parts. As this field of application expands, the performance requirements for plastic sliding members are also becoming stricter. In general, when plastic is used for sliding parts such as bearings, it is necessary to have not only sliding properties such as a low coefficient of dynamic friction, high limit PV value, little wear, and no damage to the mating material, but also rigidity and creep resistance. It is desirable to use a material with excellent mechanical properties such as hardness and heat resistance such as heat distortion temperature and continuous use temperature.

Polyamide 46 resin has extremely good mechanical properties and heat resistance. However, polyamide 46 resin alone does not have the low friction and wear resistance required for the above parts.
It is difficult to fully satisfy all of the sliding characteristics such as the limit PV value and damage resistance to mating materials, and the material has the disadvantage that its mechanical strength at high temperatures is lower than that of metal materials. As a method for improving the drawbacks of polyamide 46 resin, it has been proposed to blend carbon fibers into polyamide 46 resin (Japanese Patent Application Laid-Open No. 188460/1983). However, with the material proposed in this proposal, although the deterioration of mechanical properties at high temperatures is improved, the effect of improving sliding properties, especially the coefficient of dynamic friction and the limit PV value, is not sufficient, and the coefficient of dynamic friction is not dependent on speed or load. It has the disadvantage of being very sensitive. As a method for improving such drawbacks, a method of adding carbon fiber and tetrafluoroethylene resin to polyamide resin is known, but sufficient effects cannot be obtained.

0004

[Problems to be Solved by the Invention] That is, although a polyamide resin composition composed of polyamide 46/carbon fiber has excellent heat resistance and mechanical properties, especially excellent mechanical properties at high temperatures, it has a low coefficient of dynamic friction. However, the present invention aims to improve these drawbacks, such as the coefficient of dynamic friction having a large dependence on the sliding speed and load, and the limit PV value not being at a sufficient level.

[0005]

[Means for Solving the Problem] As a result of intensive studies to improve the above-mentioned drawbacks, the present inventors have found that by blending carbon fiber and organopolysiloxane with polyamide resin, excellent heat resistance and mechanical properties can be achieved. , it is possible to obtain a polyamide resin composition that has a low dependence of wear coefficient, dynamic friction coefficient, and dynamic friction coefficient on sliding speed and load, and has a high critical PV value, and surprisingly, the damage to the mating material is also low. This discovery led to the completion of the present invention. That is, the present invention provides (A) polyamide 46 resin 94.7-3
8% by weight, (B) 5-50% by weight of carbon fiber, and (C) 0.3-12% by weight of organopolysiloxane.

(A) Nylon 4,6 used in the present invention
includes polytetramethylene adipamide obtained from tetramethylene diamine and adipic acid, and copolyamide having polytetramethylene adipamide units as a main component. In addition, other polyamides such as nylon 4
, 6 may be included as a copolymer component within a range that does not impair the properties of .

The copolymerization component is not particularly limited, and known amide-forming components can be used. Typical examples of copolymerization components include amino acids such as 6-aminocaproic acid, 11-aminoundecanoic acid, 12-aminoundecanoic acid, and para-aminomethylbenzoic acid; lactams such as ε-caprolactam and ω-lauryllactam; hexamethylene diamine , undecamethylene diamine, dodecamethylene diamine, 2,2,4-/2,4,4-trimethylhexamethylene diamine, 5-methylnonamethylene diamine, metaxylene diamine, paraxylene diamine, 1,3-
Bis(aminomethyl)cyclohexane, 1,4-bis(
aminomethyl)cyclohexane, 1-amino-3-aminomethyl-3,5,5-trimethylcyclohexane, bis(3-methyl-4-aminocyclohexyl)methane,
Diamines such as 2,2-bis(aminopropyl)piperazine and aminoethylpiperazine; adipic acid, suberic acid, azelaic acid, sebacic acid, dodecanedioic acid, terephthalic acid, isophthalic acid, 2-chloroterephthalic acid, 2
-Methylterephthalic acid, 5-methylisophthalic acid, 5-
Examples include dicarboxylic acids such as sodium sulfoisophthalic acid, hexahydroterephthalic acid, hexahydroisophthalic acid, and diglycolic acid.

[0008] Furthermore, nylon 4,6 used in the present invention
The manufacturing method is arbitrary. For example, JP-A-56-494
30, JP-A-56-149431, JP-A-58-83029, or JP-A-61-436
A method disclosed in Publication No. 31, etc., that is, a method in which a prepolymer with a small number of cyclic end groups is first produced under specific conditions, and then this is solid-phase polymerized in a steam atmosphere to prepare high viscosity nylon 4,6. , or 2-pyrrolidone or N-
Examples include a method of obtaining it by heating in a polar organic solvent such as methylpyrrolidone. There are no particular restrictions on the degree of polymerization of nylon 4,6, but in 96% sulfuric acid at 25°C,
Nylon 4,6 having a relative viscosity of 2.0 to 6.0 at 1 g/dl is preferably used.

The carbon fiber (B) is a carbon fiber obtained by firing polyacrylonitrile filament, rayon filament or petroleum pitch, and carbon fiber made from acrylonitrile filament is particularly preferred. These carbon fibers are preferably surface-treated by ozone or electrolytic oxidation, and treated with a binding agent such as an epoxy compound or a polyamide compound, and an aminosilane-based coupling agent. The fiber diameter is preferably in the range of 0.1-30μ, more preferably 1-20μ, and the fiber length is 0.1-20mm, preferably 0.5-10mm. The average fiber length of carbon fiber in the molded product is 50 to 3000
μ is preferable, more preferably 100 to 1000 μ,
Those having an aspect ratio of 10 to 100 are preferable.

As organopolysiloxane (C),
Examples include polydimethylsiloxane, polymethylphenylsiloxane, polymethylphenyldimethylsiloxane, and polydimethylsiloxane is preferred from the viewpoint of sliding properties. These organopolysiloxanes may be modified with hydroxyl groups, carboxyl groups, epoxy groups, amino groups, etc., if necessary. The organopolysiloxane has a kinematic viscosity of 100,000 centistokes or more, and more preferably a rubbery one, which can be sufficiently kneaded in an extruder or the like to a high blending amount during compounding, and is a more excellent object of the present invention. The effect of this can be obtained. Furthermore, the organosiloxane is incorporated into a polyamide resin, such as polyamide 66 or polyamide 6 resin, preferably from 30 to
A method of obtaining the composition of the present invention using a masterbatch containing 80% by weight is particularly preferred since it is excellent in workability during blending.

[0011] The blending ratio of each component in the composition of the present invention is as follows:
Polyamide 46 resin has excellent blending operability and provides even better physical properties, so polyamide 46 resin has a content of 94.7 to 94.7 in the resin composition.
38% by weight, preferably 91.5-45% by weight,
More preferably, it is 89 to 52% by weight. Carbon fiber(
B) is present in the resin composition in an amount of 5 to 50% by weight, preferably 8 to 50% by weight.
45% by weight, more preferably 10 to 40% by weight; if the amount of carbon fiber blended is less than 5% by weight, sufficient heat resistance, rigidity, and sliding properties will not be obtained, and if it exceeds 50% by weight, it will melt. The fluidity during molding is reduced, and the molding processability is poor. The amount of organopolysiloxane (C) blended is 0.3 to 12% by weight, preferably 0.5 to 10% by weight, more preferably 1 to 8% by weight, and less than 0.3% by weight is sufficient. Sliding properties cannot be obtained, and if the content exceeds 12% by weight, the mechanical properties and heat resistance are significantly deteriorated. The method of blending the resin composition of the present invention is not particularly limited, but examples include methods of mixing in a Henschel mixer, tumbler, etc., and then melt-mixing in a batch kneader, Banbury mixer, single-screw or twin-screw extruder. be able to.

In order to give the composition of the present invention even better mechanical strength, heat resistance and sliding properties, other inorganic or/and
and organic fillers may be added as required. As the inorganic filler, those well known as reinforcing fillers for rubber or plastics are used. The shape is not particularly limited as long as it is solid, and it can take the form of powder, fibrous powder, fibers, whiskers, balloons, etc., while maintaining the excellent low friction and wear resistance of the resin composition of the present invention. In order to obtain a sufficient reinforcing effect, a powder or whisker form is preferable.

[0013] Specific examples of such fillers include clay, calcined clay, talc, catalbo, silica, alumina, magnesium oxide, calcium silicate, asbestos,
Sodium aluminate, calcium aluminate, sodium aluminosilicate, magnesium silicate, aluminum hydroxide, calcium hydroxide, barium sulfate, potassium alum, sodium alum, iron alum, shirasu balloon, glass balloon, carbon black, coke please,
Zinc oxide, antimony trioxide, boric acid, borax, zinc borate,
Examples include metal powder, metal whiskers, potassium titanate whiskers, mica, graphite, titanium oxide, wollastonite, glass fiber, glass fiber powder, glass beads, calcium carbonate, zinc carbonate, hydrotalcite, iron oxide, and the like.

The aromatic polyamide fibers and the inorganic filler used in the present invention may be subjected to various surface treatments in order to further enhance the effects of the present invention. Moreover, these inorganic fillers can be used alone or in combination of two or more. Other lubricants such as molybdenum disulfide, pigments, flame retardants, anti-aging agents, stabilizers,
Antistatic agents and the like can be added. Since the resin composition of the present invention has excellent sliding properties, it can be used in various sliding parts such as pushers, bearings, scoops, slippers, guide rails, sealing materials, switch parts, gears, and cams. .

[0015]

[Examples] The present invention will be specifically explained below with reference to Examples, but the present invention is not limited to these Examples. The resin compositions obtained in Examples and Comparative Examples were evaluated by the following test method.

Test method (1) Tensile test: Measured at a tensile speed of 50 mm/min according to ASTM D-638. (2) Bending test: Measured at a bending speed of 15 mm/min in accordance with ASTM D-790. ■ Heat distortion temperature: 2 according to ASTM D-648
Measured at 64psi. ■ Friction and wear test: Using a Suzuki type friction and wear tester,
S45C steel was used as the mating material. The test piece has an outer diameter of 25.
Using a hollow cylindrical test piece with a diameter of 6 mm and an inner diameter of 20.0 mm,
A mating material with a similar shape was also used. Contact area is 2cm
It was 2. (a) Dynamic friction coefficient Load 10 kg (surface pressure 5 kg/cm2), circumferential speed 10 cm
The measurement was performed under the condition of /s. (b) Specific wear amount Measure the decrease in weight of the resin test piece after running for 20 km at a load of 2 kg and a circumferential speed of 50 cm/s, and use the following formula (1).
It was defined by the specific wear amount calculated from

[0017]

[Formula 1]
wear weight
Specific wear amount =──────────────────
─
Travel distance x contact pressure x contact area x density

(mm3 /kgf・km) (c)
Under the same conditions as the S45C wear amount (b), the weight loss amount of the S45C after running (
mg) was measured. (d) Speed dependence of dynamic friction coefficient Load 2 kg (surface pressure 1 kgf/cm2), circumferential speed 10,2
Measurements were made at 0, 30, 40, 50, and 60 cm/s. (e) Load dependence of dynamic friction coefficient Sliding speed 10 cm/s, load 10, 20, 30, 40
, 50, and 60 kg. (F) Limit PV value peripheral speed 100cm/s, load variable method

Examples 1 to 5, Comparative Examples 1 to 5 Relative viscosity 3.
70 (measured at 30°C, 97% sulfuric acid, concentration 10-2 g/ml), carbon fiber (Besphite HTA-C6-NR manufactured by Toho Rayon Co., Ltd.), polydimethylsiloxane (Toray Dow Corning) - BY16-140 (manufactured by Silicone Co., Ltd.) was mixed in a tumbler at the composition ratio shown in Tables 1 and 2, and then melted using a twin-screw extruder (manufactured by Ikegai Tekko Co., Ltd., "Ikegai PCM45-2"). Mixed and pelleted. Using this pellet, molding temperature 3
Various test pieces were obtained by injection molding under conditions of 00°C and a mold temperature of 80°C, and their physical properties were measured using the above test method.

Comparative Example 6 Powdered polytetrafluoroethylene (PTFE, manufactured by Asahi Glass Co., Ltd., "Fluon") was used instead of polydimethylsiloxane.
Samples were prepared and their physical properties were measured in the same manner as in Examples 1 to 5, except for using ``L169''). The obtained results are shown in Table 1~
4.

[0020]

[Table 1]

[0021]

[Table 2]

Table 3 Conditions for the dependence of dynamic friction coefficient on circumferential speed:
Load: 2kgf, mating material: S45C

Table 4
Load dependence of dynamic friction coefficient conditions: peripheral speed 10 cm/s, mating material: S45C

[0024]

Effects of the Invention The polyamide resin composition of the present invention has excellent sliding properties, mechanical properties, and heat resistance, and is useful for bearings, cams,
It exhibits good functionality when used in sliding members such as gears, sliding plates, and guide members. It can withstand use at high speeds and high loads, and is suitable as a metal substitute material.

Claims (1)

[Claims] Claim 1: (A) Polyamide 46 resin 94.7~
38% by weight, (B) 5 to 50% by weight of carbon fiber, and (
C) A polyamide resin composition comprising 0.3 to 12% by weight of organopolysiloxane.