JPH05239345A - Polyamide resin composition - Google Patents

Abstract

PURPOSE:To obtain the subject new composition having excellent rigidity, heat- resistance and sliding characteristic and useful as a sliding member such as bearing and gear by compounding a nylon 46 resin with graphite whisker at a specific ratio. CONSTITUTION:The objective composition is produced by compounding (A) 100 pts.wt. of a nylon 46 resin with (B) 5-100 pts.wt. of graphite whisker and, as necessary, (C) <=40 pts.wt. of a lubricant (preferably molybdenum disulfide). The component A is preferably produced e.g. by preparing a prepolymer having low cyclic terminal group content from tetramethylenediamine, adipic acid, etc., and subjecting the prepolymer to solid-phase polymerization in steam atmosphere. The component B preferably has an average fiber diameter of <=2mum, an average fiber length of 50-100mum and an aspect ratio (average fiber length/ average fiber diameter) of >=10.

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 excellent in low friction and abrasion resistance, heat resistance and rigidity, which is suitable for sliding members. More specifically, a polyamide resin composition containing 100 parts by weight of nylon 46 resin (a), 5 to 100 parts by weight of graphite whiskers (b), and 40 parts by weight or less of a lubricant (c) if necessary. Regarding Polyamide resin composition of the present invention, by a molding method such as injection molding and extrusion molding,
It is used as a useful molded product in the fields of automobiles, machinery, electricity, and the like.

[0002]

2. Description of the Related Art Nylon 46 resin composed of tetramethylenediamine and adipic acid or a functional derivative thereof is a known polyamide. For example, Japanese Patent Publication Sho 60-
Japanese Patent No. 8248 and Japanese Patent Publication No. 60-28843 disclose methods for producing nylon 46 resin. It is also known that this nylon 46 resin has excellent properties as engineering plastics, particularly excellent heat resistance. For example, its melting point is 295 ° C., which is higher than 260 ° C. of nylon 66 and higher than 285 ° C. of polyphenylene sulfide. In addition, the crystallinity and the crystallization rate are fast, and the heat distortion temperature is 28
It belongs to the highest value among engineering plastics at 5 ° C (4.5 kg / cm ² load). Further tensile strength,
Excellent mechanical strength such as bending strength, sliding characteristics, and fatigue resistance.

In recent years, plastic sliding members have expanded their fields of application into fields such as bearings that are subject to severe wear under severe weight, bushings used under high ambient temperature conditions, and thin sliding parts. Therefore, the requirements for plastic sliding members are becoming stricter. Generally, when plastic is applied to sliding parts such as bearings, in addition to the sliding characteristics that the dynamic coefficient of friction is small, the PV value is high, the amount of wear is small, and the mating material is not damaged, rigidity and creep resistance are also high. It is desirable to use a material having excellent mechanical properties such as, and also excellent heat resistance such as heat distortion temperature and continuous use temperature. The above-mentioned limit PV value is the product of the surface pressure (P) and the friction velocity (V) when the resin begins to melt or significantly wear in the friction and wear test. The higher this value, the higher the load and the speed. It can withstand use under harsh conditions.

Nylon 46 resin has extremely good mechanical properties and heat resistance among polyamide resins. On the other hand, in order to further improve the above properties of the nylon 46 resin, a method of adding glass fiber or the like is used. When such a resin composition is used as a bearing material, the glass fiber is microscopically exposed on the bearing sliding surface. However, it has a drawback of so-called "galling" in which the mating material is worn, and there is a drawback that not only the amount of wear increases but also the coefficient of friction increases. In addition, a molded product made of a resin composition containing glass fiber has a large anisotropy, and thus has a problem in dimensional accuracy. Further, in the case of small parts, thin-walled parts, and parts that include acute-angled parts, the flow of glass fibers is insufficient, the content of the fibers is less than in other parts, and a sufficient reinforcing effect cannot be obtained. Insufficient rigidity. In this way, it is difficult to achieve both high rigidity and heat resistance required for sliding parts and sliding characteristics such as low friction and wear resistance, and excellent sliding characteristics while maintaining high rigidity and heat resistance. A new resin composition having the above has been desired.

[0005]

In view of such circumstances, an object of the present invention is to provide a composition of nylon 46 resin having excellent sliding properties while further improving high rigidity and heat resistance. .. Another object of the present invention is to provide a resin composition that can be used as a molded article useful in the fields of automobiles, machines, electricity, etc. by injection molding, extrusion molding and the like.

[0006]

As a result of intensive studies to solve the above problems, the present inventors have added a specific amount of graphite whiskers and a specific amount of lubricant to nylon 46 resin. The present inventors have found that the resulting polyamide resin composition solves all the problems of the present invention, and arrived at the present invention. That is, the gist of the present invention is a polyamide resin obtained by blending 5 to 100 parts by weight of graphite whiskers (b) and 40 parts by weight or less of a lubricant (c) with 100 parts by weight of nylon 46 resin (a). In the composition.

Nylon 46 used as component (a) in the present invention
The resin refers to a mixture of tetramethylenediamine, adipic acid and a polyamide having a polyamide as a main constituent unit or a polyamide containing nylon 46 resin as a main component. It is also possible to replace part of the adipic acid component or tetramethylenediamine component constituting the nylon 46 resin of the present invention with another copolymerization component.

There is no particular limitation on the copolymerization component or the component constituting the other polyamide, and a known amide group-forming component can be used. Typical examples of the amide group-forming component include amino acids such as 6-aminocaproic acid, 11-aminoundecanoic acid, 12-aminododecanoic acid and paraaminomethylbenzoic acid, lactams such as ε-caprolactam and ω-lauryllactam, and hexamethylenediamine. , Undecamethylenediamine, dodecamethylenediamine, 2,2,4 / 2,4,4-trimethylhexamethylenediamine, 5-methylnonamethylenediamine, metaxylylenediamine, paraxylylenediamine, 1,3-bis ( Aminomethyl) cyclohexane,
1,4-bis (aminomethyl) cyclohexane, 1-amino-3-aminomethyl-3,5,5-trimethylcyclohexane, bis (3-methyl-4-aminocyclohexyl) methane, 2,2-bis (4- Aminocyclohexyl) propane, bis (aminopropyl) piperazine, bis (aminoethyl) piperazine and other diamines, adipic acid, speric acid, azelaic acid, dodecanoic acid, terephthalic acid, isophthalic acid, 2-chloroterephthalic acid, 2-
Examples thereof include dicarboxylic acids such as methylterephthalic acid, 5-methylisophthalic acid, 5-sodiumsulfoisophthalic acid, hexahydroterephthalic acid, hexahydroisophthalic acid, and diglycolic acid.

The content of such a copolymerization component is preferably less than 20 mol%. If it exceeds this range, the heat resistance of the nylon 46 resin is lowered, which is not preferable. Further, the content of the other polyamide to be mixed is preferably less than 50% by weight. If it exceeds this range, the heat resistance of the nylon 46 resin is lowered, which is not preferable.

The method for producing the nylon 46 resin used in the present invention is arbitrary. For example, JP-B-60-28843, JP-B-60-8248, and JP-A-58-830.
29 and JP-A-61-43631, that is, a prepolymer having a small amount of cyclic end groups is first produced under specific conditions and then solid-state polymerized in a steam atmosphere or the like to obtain a high viscosity. It is particularly preferable to use the one obtained by the method for preparing the nylon 46 resin, or the one obtained by the method of heating in a polar organic solvent such as 2-pyrrolidone or N-methylpyrrolidone.

The degree of polymerization of the nylon 46 resin used in the present invention is not particularly limited, but 96% sulfuric acid is used, and the relative viscosity when measured at a concentration of 1 g / dl and 25 ° C. is 1.
Nylon 46 resin in the range of 5 to 5.5, more preferably 2.0 to 4.5 is preferable. When the relative viscosity exceeds 5.5, not only the fluidity of the composition deteriorates, but also the dispersion of mechanical and thermal properties increases, which is not preferable. If the relative viscosity is lower than 1.5, the mechanical strength of the composition tends to be low.

The graphite whiskers (b) used in the present invention have an average fiber diameter of 2 μm or less and an average fiber length of 5
It is preferable that the average fiber length / average fiber diameter (hereinafter, referred to as aspect ratio) is 10 to 100 μm. As such a graphite whisker, for example, a trade name “GRASKER” (manufactured by Nikkiso Co., Ltd.)
Can be used as is. This is a high strength whisker having an average fiber diameter of 0.3 to 1.0 μm, an average fiber length of 5 to 100 μm and an aspect ratio of 10 to 150. The graphite whiskers may be used without surface treatment, but are surface-treated with a surface treatment agent such as a silane coupling agent or a titanate coupling agent in order to improve the interfacial adhesion strength with nylon 46 resin. May be

The amount of graphite whiskers blended is such that nylon 46 resin (a) is used in view of the reinforcing effect of nylon 46 resin (a), especially the improvement of rigidity, creep resistance and heat distortion temperature, and further improvement of the limiting PV value. 5 to 100 parts by weight, preferably 10 to 80 parts by weight, relative to 100 parts by weight,
It is more preferably in the range of 20 to 60 parts by weight. If the blending amount is less than 5 parts by weight, the mechanical strength and sliding characteristics cannot be sufficiently improved, and even if it is used in excess of 100 parts by weight, the mechanical strength is improved relative to the amount used in excess of 100 parts by weight. No effect is observed, it is difficult to granulate the composition as a molding material, and the appearance of the molded product tends to deteriorate.

The lubricant (c) used in the present invention includes silicone compounds, molybdenum disulfide, graphite,
Examples thereof include fluororesins. Of these, molybdenum disulfide is preferred. These are appropriately selected according to the purpose,
The required amount can be blended. The amount of lubricant used is 40 parts by weight or less per 100 parts by weight of nylon 46 resin (a),
It is preferably 1 to 20 parts by weight, more preferably 1 to 10 parts by weight. If it exceeds 40 parts by weight, the rigidity, heat resistance and surface appearance are deteriorated.

The method for preparing the polyamide resin composition of the present invention is not particularly limited. For example, it is mixed by a Henschel mixer, a tumbler, etc., and further melt-kneaded by a batch kneader, a Banbury mixer, a single-screw or twin-screw extruder. Can be mentioned.

To the polyamide resin composition of the present invention, a pigment, a heat stabilizer, an antioxidant, a weather resistance agent, a flame retardant, a plasticizer, a release agent, an antistatic agent, etc. are added as long as the characteristics are not significantly impaired. It is possible. Examples of such heat stabilizers and antioxidants include hindered phenols, phosphorus compounds, amine compounds, sulfur compounds, copper compounds, compounds of alkali metal or alkaline earth metal and halogen, or a mixture thereof. Among them, the copper compound is most effective. Examples of such copper compounds include copper iodide, copper bromide, copper chloride and the like. Further, the combined use of a hindered phenol, a phosphorus compound, an amine compound, a sulfur compound, a compound of an alkali metal or an alkaline earth metal and a halogen is particularly effective. Additives such as these heat stabilizers, antioxidants and weathering agents are generally added during melt kneading.

Further, the resin molded product of the present invention may be blended with other polymers, if necessary. Such polymers include polybutadiene, butadiene-styrene copolymer, acrylic rubber, ethylene-propylene copolymer, ethylene-propylene-diene copolymer, natural rubber, chlorinated butyl rubber, chlorinated polyethylene, styrene-butadiene block copolymer. Copolymers, elastomers such as butadiene-styrene radial tereblock copolymers, styrene-maleic anhydride copolymers, styrene-phenylmaleimide copolymers, polyethylene, polypropylene,
Butadiene-acrylonitrile copolymer, polyvinyl chloride, polyethylene terephthalate, polybutylene terephthalate, polyacetal, polyvinylidene fluoride, polysulfone, polyphenylene sulfide, polyether sulfone, phenoxy resin, polyphenylene ether, polymethyl methacrylate, polyether ketone,
Examples include polycarbonate and polyarylate.

Since the polyamide resin composition of the present invention has excellent mechanical strength, heat resistance and excellent sliding characteristics, it has a pusher, bearing, sleeve, slipping, guide rail, sealant, switch part, gear. It can be used for various sliding parts such as cams and cams. Examples of the method for molding these various sliding parts from the polyamide resin composition of the present invention include injection molding and extrusion molding.

[0019]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited thereto.

The measuring methods used for evaluation of the following examples and comparative examples are as follows. (Bending Strength and Bending Elastic Modulus) Bending strength and bending elastic modulus were measured based on ASTM D790 using a 1/8 inch thick bending test piece. (Heat Deformation Temperature) The heat deformation temperature (HD
T) was measured. The measurement was performed based on ASTM D648. The load was 18.6 kg / cm ² . (Friction and Wear Test) A Suzuki type friction and wear tester was used for the friction and wear test, cylindrical steel was used as the mating material, and friction speed (V) was 30 cm / sec and load (P) was 10 kg / cm ^2.
The coefficient of kinetic friction was determined under the condition. Continuous operation under the above conditions,
The specific amount of wear was the amount of wear per unit weight and unit weight when the friction distance reached 10 km. The relative material specific wear amount was defined in the same manner. The limit PV value is a friction speed of 30 cm /
The load was changed while keeping sec constant, and the time when melting or significant wear occurred was determined. (Appearance of molded product) Roughness and luster of the injection molded test piece were observed.

(Examples 1 to 6) Nylon 46 resin (Unitika "F5000", relative viscosity 2.80) and graphite whiskers (Nikkiso "Grasker GWM-"
B ”) and molybdenum disulfide (“ Mori Powder PA ”manufactured by Sumiko Lubrication Co., Ltd.) are mixed according to the formulation shown in Table 1, and then twin-screw extruder (“ P ”manufactured by Ikegai Iron & Steel Co., Ltd.).
CM45 ") was melt-mixed at a cylinder temperature of 300 ° C and pelletized. Test pieces were molded from the pellets using injection molding (“MST125 / 75 type molding machine” manufactured by Mitsubishi Heavy Industries, Ltd.), and the physical properties thereof were evaluated by the above test methods. As a result, it was found that the resin compositions of Examples 1 to 6 had the excellent mechanical strength, heat resistance, and excellent sliding properties that were the objects of the present invention.

(Comparative Examples 1 to 3) Nylon 46 resins, graphite whiskers and molybdenum disulfide shown in Examples 1 to 6 were used to prepare resin compositions at the composition ratios shown in Table 2, and their physical properties were evaluated. Evaluation was performed in the same manner as in Examples 1 to 6.

[0023]

[Table 1]

[0024]

[Table 2]

Comparative Example 1 is a composition in which the content of graphite whiskers is within the range of the present invention, and the rigidity, heat resistance,
Both the limit PV values as sliding characteristics are not sufficient. Comparative Example 2 was a composition in which the content of graphite whiskers exceeded the range of the present invention, and the surface of the molded product was rough, and it was not glossy and was defective. Comparative Example 3 is a composition in which the additive specified in the present invention is not added to nylon 46 resin, but this does not give the desired physical properties in rigidity, heat resistance and sliding properties. Comparative Examples 4 to 5 are nylon 46 resin, graphite whiskers, molybdenum disulfide, and nylon 66 (“Maranyl A12” manufactured by Unitika Ltd.).
5 ”), nylon 6 (“ A1030B ”manufactured by Unitika Ltd.)
RL ") was used to prepare a resin composition in the composition ratio shown in Table 2, and its physical properties were evaluated by the same methods as in Examples 1 to 6. Comparative Example 4 is an example in which Nylon 66, which is a polyamide resin outside the scope of the present invention, was used in place of the Nylon 46 resin in Example 2, and compared with Example 2, the heat resistance and sliding characteristics were limited. The PV value is greatly inferior. Comparative Example 5 is an example in which nylon 6 which is a polyamide resin outside the scope of the present invention is used in place of the nylon 46 resin in Example 2, and compared with Example 2, the limit PV as heat resistance and sliding characteristics is The value is greatly inferior. Comparative Example 6 is Examples 1-6.
Nylon 46 resin and molybdenum disulfide used in the above are used as fibers other than graphite whiskers with a diameter of 13
Using chopped strand glass fibers (“T-277P” manufactured by Nippon Electric Glass Co., Ltd.) having an average length of 3 mm, which were made from strands of continuous long fibers of μm, the composition ratio fat composition shown in Table 2 was prepared. Then, the physical properties were evaluated in the same manner as in Examples 1 to 6. In Comparative Example 6 using glass fiber, which is an additive outside the scope of the present invention, the rigidity and heat resistance have the target values, but the dynamic friction coefficient, the specific wear amount, the specific wear amount of the mating material, etc. Is inferior in sliding property, and the surface of the molded product is rough, and it is not glossy and has a poor appearance, so that it is unsuitable for use as a material for sliding parts.

[0026]

As shown in the above examples, the polyamide resin composition of the present invention has excellent rigidity and heat resistance of nylon 46 resin by blending a specific amount of graphite whiskers and a specific amount of lubricant. And sliding properties are remarkably improved. The polyamide resin composition of the present invention has excellent rigidity, heat resistance, and excellent sliding characteristics, and is therefore useful for various applications centering on sliding members, particularly bearings, switches, gears, etc. It is possible to provide various parts of, and its industrial utility value is extremely large.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI Technical display part // (C08L 77/06 83:04) (C08L 77/06 27:12) (72) Inventor Shinichiro Katahira 23, Uji Kozakura, Uji, Kyoto Prefecture Unitika Central Research Institute (72) Inventor, Megumi Ogasa 23, Uji Kozakura, Uji City Kyoto Prefecture Central Unit, Central Research Institute

Claims (1)

[Claims] 1. A polyamide resin composition comprising 100 parts by weight of nylon 46 resin (a), 5 to 100 parts by weight of graphite whiskers (b) and, if necessary, 40 parts by weight or less of a lubricant (c). ..