JPH073149A - Polyamide resin composition - Google Patents

Abstract

PURPOSE:To obtain the composition excellent in heat resistance, fluidity, moldability, mechanical properties, dimensional accuracy and wear resistance. CONSTITUTION:The composition is prepared by mixing 100 pts.wt. polyamide with 1-200 pts.wt. graphite having a fixed carbon content of 80% or greater, a degree of crystallinity of 65% or greater, and a mean particle diameter in the range of 1-20mum.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention has excellent heat resistance, moldability,
The present invention relates to a polyamide resin composition having mechanical properties and capable of giving a molded article having particularly excellent dimensional accuracy and abrasion resistance.

[0002]

2. Description of the Related Art Polyamides have been widely used in the fields of automobiles, electric and electronic fields, etc. by utilizing their excellent properties as engineering plastics.

Polyamide resin has excellent wear resistance and is often used for sliding members such as gears and cams.

As a means for further improving the wear resistance of polyamide, it has been known that the addition of inorganic substances such as molybdenum disulfide and natural graphite, polyethylene, and polytetrafluoroethylene powder and fibers are effective ( USP285
537), which is put to practical use.

Further, it is known to add graphite and / or carbon black to polyamide as a means for imparting conductivity (JP-A-52-42295 and JP-A-52-45091).

[0006]

However, the method of adding polyethylene or polytetrafluoroethylene cannot be expected to improve the dimensional accuracy, and the method of adding an inorganic material is toughness even if heat resistance and dimensional accuracy are improved. In reality, there is no material that truly meets the needs, such as a decrease in the value.

Further, even if general graphite or carbon black is added for the purpose of imparting conductivity, the dimensional accuracy and abrasion resistance of polyamide cannot be improved.

Accordingly, the present invention solves the above problems and provides a polyamide resin composition which has heat resistance, moldability and mechanical properties, and which can give a molded article having particularly excellent dimensional accuracy and abrasion resistance. Is an issue.

[0009]

In view of the above situation, the present inventors have arrived at the present invention as a result of earnestly examining means for solving the above problems.

That is, the present invention relates to (A) polyamide 1
A polyamide resin containing (B) 1 to 200 parts by weight of graphite having fixed carbon of 80% or more, crystallinity of 65% or more, and an average particle size of 1 to 20 μm with respect to 00 parts by weight. A composition is provided.

Examples of polyamides used in the present invention include ring-opening polymerization products of cyclic lactams, polycondensation products of aminocarboxylic acids, and polycondensation products of dicarboxylic acids and diamines. Specific examples include nylon 6 and nylon. 66, nylon 46, nylon 610, nylon 612, nylon 1
1, aliphatic polyamide such as nylon 12, poly (meta-xylene adipamide) (hereinafter abbreviated as MXD.6), poly (hexamethylene terefluamide) (hereinafter abbreviated as 6T), poly (hexamethylene isophthalamide) ) (Hereinafter abbreviated as 6I), poly (tetramethylene isophthalamide) (hereinafter abbreviated as 4I), and other aliphatic-aromatic polyamides, and copolymers and mixtures thereof. Particularly suitable polyamides for the present invention include nylon 6, nylon 66, nylon 6/66 copolymer, and nylon 66 / 6T copolymer.

The degree of polymerization of the polyamide used here is not particularly limited, but the relative viscosity measured at 25 ° C. in 98% sulfuric acid concentration 1% at 25 ° C. according to JIS K6810 is 1.7 or more from the viewpoint of polymerization stability, and the workability is From the point, 4.5 or less, particularly 2.0 or more and 4.0 or less, further 2.0 or more 3.
It is preferably 5 or less. Polymerization method of the polyamide used in the present invention is not particularly limited, melt polymerization, interfacial polymerization,
Solution polymerization, bulk polymerization, solid phase polymerization, and a combination of these methods can be used. For example,
In the polymerization of nylon 66 / 6T, a method in which a low-order condensate is melt-polymerized and the degree of polymerization is increased can also be used.

As the graphite used in the present invention, it is necessary to use graphite having a fixed carbon content of 80% or more, a crystallinity of 65% or more and an average particle size of 1 to 20 μm. Fixed carbon is 80% or more, preferably 94% or more,
It is more preferably 98% or more, and particularly preferably 99% or more. If the fixed carbon content is less than 80%, the amount of wear during sliding will be large and the effect of improving wear resistance will be poor, such being undesirable.

The crystallinity is 65% or more, preferably 80%
Above, more preferably 80-95%, especially 82-94%
Is preferred. If it is less than 65%, the coefficient of kinetic friction during sliding becomes large and the effect of improving wear resistance becomes small, which is not preferable. The impact resistance of the obtained polyamide resin composition is
When the crystallinity is in the range of 65% or more, the lower the crystallinity is, the higher the impact resistance is generally. The average particle size of the graphite is 1 to
It is necessary to be 20 μm, preferably 2 to 10 μm. If the average particle diameter is less than 1 μm, aggregation occurs and the dispersion becomes poor, and if it exceeds 20 μm, the mechanical properties are deteriorated, which is not preferable. The graphite can be roughly classified into natural graphite and artificial graphite. In the present invention, for example, petroleum coke or coal coke is used as a raw material, to which tar pitch and the like are added, and primary firing is performed at about 800 ° C. And about 2400 more
It is particularly preferable to use artificial graphite manufactured by a method of heating to ~ 3000 ° C to graphitize.

The fixed carbon of graphite is measured by about 10 g of graphite powder.
In a crucible, accurately weigh the graphite (A), burn it in a furnace set at 815 ° C., cool it to room temperature, and then weigh the weight (B) of the combustion residue and calculate it by the following formula. It is a thing.

Fixed carbon (%) = (B) / (A) × 100 Further, the crystallinity (P) of graphite is expressed by a percentage of the crystal array degree (P ₁ ) in the following Warren's empirical formula (1). , D ₀ = 3.354 * P ₁ +3.44 (1-P ₁ ) ... (1) d ₀ : average interlayer spacing (angstrom) of the graphite crystal (C ₀ ) = 2 × d _The crystallinity (P) is calculated by the equation (2) where ₀ is set.

P (%) = (6.88−C ₀ ) /0.173 (2) Here, the average interlayer spacing (d ₀ ) of the graphite crystals is obtained by an X-ray diffraction method, and specifically, graphite 20mm powder
It is a value measured by a reflection method using an X-ray diffractometer manufactured by Rigaku Denki Co., Ltd. as a standard sample and packed in an 18 mm × 2 mm aluminum sample holder.

The amount of graphite added is in the range of 1 to 200 parts by weight, preferably 3 to 100 parts by weight, particularly preferably 5 to 80 parts by weight, based on 100 parts by weight of polyamide. If the addition amount is less than 1 part by weight, the effect of improving the wear resistance cannot be expected, and if it exceeds 200 parts by weight, not only the appearance of the molded article is deteriorated but also the mechanical properties are deteriorated, which is not preferable in any case.

The surface of the above graphite used in the present invention may be treated with a known coupling agent (for example, silane coupling agent, titanate coupling agent, etc.).

Further, it is preferable to use a reinforcing agent and a filler together in the composition of the present invention. Examples of the reinforcing agent and the filler are glass fiber, carbon fiber, aromatic polyamide fiber,
Potassium titanate fiber, gypsum fiber, brass fiber, stainless fiber, steel fiber, ceramic fiber, boron whisker fiber, asbestos fiber, mica, talc, silica,
Examples include fibrous, powdery, granular or plate-like inorganic and organic fillers such as calcium carbonate, glass beads, glass flakes, glass microspheres, clay, wollastonite, titanium oxide and molybdenum disulfide. To be In particular, the addition of glass fiber or molybdenum disulfide is effective for improving wear resistance. Further, as these fillers and reinforcing agents, those treated with a coupling agent such as a silane type or a titanate type or other surface treating agent may be used.

When a filler is added, the addition amount is not more than 200 parts by weight, preferably 5 to 150 parts by weight, and preferably 10 to 100 parts by weight, relative to 100 parts by weight of the polyamide resin composition according to claim 1. Particularly preferred.

Further, the polyamide resin composition of the present invention contains an antioxidant and a heat stabilizer (eg, hindered phenol, hydroquinone, phosphite and substitution products thereof) within a range not impairing the object of the present invention. , Copper iodide,
Potassium iodide, etc.), weathering stabilizer (resorcinol type, salicylate type, benzotriazole type, benzophenone type, hindered amine type, etc.), mold release agent and lubricant (montanic acid and its salt, its ester) , That h
Fester, stearyl alcohol, stearamide, various bisamides, bisurea and polyethylene wax), pigments (cadmium sulfide, phthalocyanine, carbon black, etc.), and dyes (nigrosine, etc.), other polymers (other polyamides, Polyester, polycarbonate, polyphenylene ether, polyphenylene sulfide, liquid crystal polymer, polyether sulfone, AB
S resin, SAN resin, polystyrene, acrylic resin, polyethylene, polypropylene, ethylene / α-olefin copolymer, ionomer resin, SBS, SEBS, etc.) can be added.

The polyamide resin composition of the present invention is preferably produced by melt kneading, and known methods can be used for melt kneading. For example, using a Banbury mixer, a rubber roll machine, a kneader, a single-screw or twin-screw extruder, and the like, the composition can be melt-kneaded at a temperature of 200 to 400 ° C.

The polyamide resin composition of the present invention thus obtained has excellent heat resistance, moldability, mechanical properties and surface appearance by ordinary molding methods such as injection molding, extrusion molding, blow molding, etc. It can be processed into three-dimensional molded products, sheets, containers, pipes, etc. that have mechanical properties with low directional property, such as switches, micro slide switches, DIP switches, switch housings,
Lamp sockets, binding bands, connectors, connector housings, connector shells, IC sockets, coil bobbins, bobbin covers, relays, relay boxes, capacitor cases, internal parts of motors, small motors. -Case, gear cam, dancing pulley, spacer,
Insulator, fastener, buckle, wire clip, bicycle wheel, caster, helmet,
Terminal block, power tool housing, starter insulation, spoiler, canister, radiator tank, chamber tank, reservoir tank, fuse box, air cleaner case , Air conditioner fan, terminal housing, wheel cover, intake and exhaust pipes, bearing retainer, cylinder head cover, inte
Electrical / electronic-related parts such as Kumani folder, water pipe impeller, clutch release, speaker diaphragm, heat-resistant container, microwave oven parts, rice cooker parts, printer-ribbon guide, automobiles, etc. It is effective for vehicle-related parts, household / office electrical product parts, computer-related parts, facsimile / copier-related parts, machine-related parts, and other various applications.

[0025]

The present invention will be described in more detail with reference to the following examples. The properties in the examples and comparative examples were measured by the following methods.

1) Limit PV value Using a square plate having a size of 30 × 30 × 3.2 (thickness) mm and steel as a mating material, and using a thrust wear tester (Suzuki wear tester), P = 0 to 0 100 kgf / cm ² , V =
A wear test was performed in the range of 0 to 23 m / min to determine the limit PV value.

2) Linear expansion coefficient It was measured according to ASTM D-696.

3) Izod impact strength It was measured according to ASTM D-256. Examples 1 to 4 and Comparative Examples 1 to 3 After dry-blending the compositions shown in Table 1, the cylinder temperature was set to each polyamide melting point + 10 ° C.
Melt kneading was performed using an mφ twin-screw extruder to obtain pellets.
These pellets have a cylinder temperature of melting point + 15 ° C., a mold temperature of 80 ° C., a square plate of 30 × 30 × 3.2 (thickness) mm and an Izod of 12.5 × 12.5 × 3.2 (thickness) mm.
Impact test pieces were injection molded. The results of these evaluations are summarized in Table 1.

[0029]

[Table 1]

The methods of Examples 1 to 4 all had excellent wear characteristics, dimensional accuracy and impact resistance.

On the other hand, the fixed carbon and the one whose crystallinity was out of the scope of the present invention (Comparative Example 1) were inferior in abrasion resistance, and the one to which graphite was not added (Comparative Example 2) was impact resistant. Although excellent in wearability, it was inferior in wear characteristics and dimensional accuracy. Further, in the case of adding graphite in an amount of more than 200 parts by weight (Comparative Example 3),
It was extremely inferior in impact resistance.

[0032]

EFFECT OF THE INVENTION The polyamide resin composition of the present invention gives a molded article having particularly excellent dimensional accuracy and abrasion resistance without impairing the excellent heat resistance, fluidity, moldability and mechanical properties of polyamide. Therefore, it is a material suitable for various other applications such as electrical / electronic-related equipment, precision machinery-related equipment, office equipment, automobile / vehicle-related equipment, and the like.

Claims (2)

[Claims] 1. To 100 parts by weight of (A) polyamide, (B) graphite having fixed carbon of 80% or more, crystallinity of 65% or more, and an average particle diameter of 1 to 20 μm.
A polyamide resin composition containing 200 parts by weight. 2. The polyamide resin composition 1 according to claim 1.
A polyamide resin composition which further comprises 200 parts by weight or less of a filler with respect to 00 parts by weight.