JPH01279963A - Polyamide resin composition - Google Patents

Abstract

PURPOSE:To provide a resin composition excellent in sliding characteristics, strength, heat resistance, melt flow characteristics, etc., by incorporating aromatic polyamide fibers, polytetrafluoroethylene, and a high-density polyethylene each in a specified amount into a polyamide. CONSTITUTION:100pts.wt. polyamide (A) (e.g., nylon 4 or 6) is mixed with 1-80pts.wt. aromatic polyamide fibers (B), 3-80pts.wt. polytetrafluoroethylene (C), and 1-20pts.wt. high-density polyethylene (D) to give a polyamide resin composition. This composition has a low frictional force to metal, and both low wearability and low capability of causing wear of metal in sliding contact therewith. Therefore, it is useful for various applications mainly as sliding members, such as parts of a small mechanism and, in particular, it is suitably used as the raw material for various parts, such as bearings, switches, and gears.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a polyamide resin composition suitable for sliding members, and more specifically, it has low frictional force against metals, self-abrasive properties, and abrasion resistance of mating metals. The present invention relates to a polyamide resin composition suitable for sliding members, which has low physical properties, excellent mechanical properties, heat resistance, and fluidity when melted.

(Prior art) Polyamides have been used as useful resins for a long time, and among them, polytetramethylene adipamide resin (hereinafter referred to as nylon 4.6) has excellent heat resistance, toughness, and chemical resistance. Therefore, it is expected that it will be put into practical use as a structural material for various purposes.

In particular, since it has significantly superior self-lubricating properties compared to other engineering resins, it is expected to be put to practical use in sliding parts such as bearing parts, gear parts, and mechanical parts that require wear resistance.

Recently, the use of plastic sliding parts has expanded to areas such as bearing links that are unlubricated and subject to severe loads and severe wear, bushings used under conditions of high ambient temperature, and thin-walled sliding parts. With the expansion of this field of application, the performance requirements for plastic sliding members are also becoming stricter.

Generally, when using plastic for sliding parts such as bearings, in addition to the sliding properties of a small coefficient of dynamic friction, a high limit Pv value, a small amount of wear, and no damage to the mating material, plastics are required to have rigidity and durability. It is desirable to use a material with excellent mechanical properties such as creep resistance and heat resistance such as heat distortion temperature and continuous use temperature.

Polyamide resins, especially nylon 4.6, have very good mechanical properties and heat resistance.

However, the current situation is that nylon 4.6 alone cannot fully satisfy the sliding properties such as low friction and wear resistance required of the above-mentioned sliding parts.

As a method for improving the sliding properties of the above nylon 4.6,
For example, a method has been proposed in which nylon 4.6 is blended with polytetrafluoroethylene and potassium titanate whiskers (Japanese Patent Laid-Open No. 185747/1983).

However, in recent years, parts have become smaller and thinner as devices become more sophisticated, and demand for particularly thin sliding parts is increasing. For example, although nylon 4.6 has improved sliding properties due to the above-mentioned improvements, it can improve the miniaturization and thinning of molded parts, and the fluidity of molten resin may be inferior to other polyamides.
Nylon 4.614 has better fluidity than it can be said to be sufficient.
Fat compositions are desired.

-M is a hydrocarbon such as paraffin or polyethylene wax for the purpose of imparting fluidity to the molten resin.

Metal soaps such as lead stearate and calcium stearate, long chain carboxylic acids such as stearic acid, amide compounds such as valmitic acid amide and ethylene bis stearyl amide,
Methods of adding ester compounds such as stearic acid monoglyceride and cetyl valmitate, alcohols such as mannitol and stearyl alcohol, and methods of adding polymers such as polyethylene, polypropylene, and polyethylene oxide are widely known.

However, when low molecular weight compounds such as hydrocarbons, metal soaps, long-chain carboxylic acids, amide compounds, ester compounds, alcohols, etc. are added, the surface appearance tends to deteriorate and mechanical properties tend to deteriorate.

Furthermore, when polymers such as polyethylene and polypropylene are used, problems arise such as phase separation due to poor compatibility with nylon, deterioration of mechanical properties, and deterioration of heat resistance. Furthermore, the thermal decomposition temperature of polyethylene oxide is approximately 200°C.
Therefore, it cannot be used for nylon whose molding temperature exceeds 200°C.

(Problems to be Solved by the Invention) The present inventors have developed a resin composition that improves the sliding properties of polyamide and also improves the fluidity of a molten resin in order to improve the miniaturization and thinning of molded parts. As a result of intensive studies to develop this product, we found that by blending polyamide with aromatic polyamide fibers and high-density polyethylene, we achieved excellent sliding properties, i.e., mechanical properties, without causing a decrease in mechanical properties or heat resistance. , has not only heat resistance but also no phase separation of polyethylene and fluidity of molten resin.
It was discovered that a resin composition capable of providing a sliding component with a thin wall thickness can be obtained, and the present invention was achieved based on this knowledge.

(Means for Solving the Problems) That is, the present invention uses 1 to 80 parts by weight of aromatic polyamide fibers, 3 to 80 parts by weight of polytetrafluoroethylene (hereinafter referred to as PTFE), and furthermore, 100 parts by weight of polyamide. 1 density polyethylene (hereinafter referred to as HDPE)
20 parts by weight of the resin composition.

Examples of polyamide include nylon 6, nylon 66, nylon 12. Nylon 11. Although nylon 612 or the like can be used, nylon 4.6 is preferable in terms of heat resistance, mechanical properties, etc.

The above nylon 4.6 has the following formula %formula% It is a polyamide consisting essentially of turned structural units.

Regarding the manufacturing method of this nylon 4.6,
No. 14930, No. 56-149431, No. 58-83
Examples include methods described in Japanese Patent Publication No. 029 and Japanese Patent Publication No. 60-28043. Moreover, in order to obtain the resin composition of the present invention, at least 1.5. Preferably 2.5~
It is advantageous to use nylon 4.6, which has a relative viscosity (η,,Q, measured at 30° C. in 197% sulfuric acid at a concentration of 10−2 g/ml) of 5.0.

The aromatic polyamide fiber used in the present invention is so-called -
It is a fiber called ``aramid fiber'', such as ``Kevlar J'', ``Nomex'', !L (manufactured by DuPont),
"Technora", "Cornetx", (manufactured by Ontaisha)
, "Allen Riki" (manufactured by Akzo), etc. are commercially available.
The available aromatic polyamide fiber used in the present invention is preferably used in the form of short fibers, and the fiber diameter is not particularly limited, but is preferably 30 μm or less, more preferably 15 LLm or less. If the fiber length exceeds 61, the fluidity of the molten resin and the granulation properties using an extruder will deteriorate, so it is not preferable, and it is advantageous to use a fiber length of 3 or less.

The amount of the aromatic polyamide fiber added is polyamide 10
1 to 80 parts by weight, preferably 1.5 to 0 parts by weight
The amount is 50 parts by weight, more preferably 2 to 30 parts by weight, particularly preferably 3 to 20 parts by weight.

If the amount of aromatic polyamide fiber added is less than 1 part by weight, no improvement in mechanical strength or heat resistance can be expected, and little improvement in self-wear when sliding with metal; conversely, if the amount added is less than 1 part by weight, If the amount exceeds 1 part, the method of the present invention cannot improve fluidity.

The PTFE used in the present invention is preferably in powder form, and its average particle size is preferably 15 μm or less, more preferably 1oLLvs or less. There is no particular restriction on the lower limit of the average particle size; if the average particle size exceeds 15 μm, the surface of a molded article made from the composition of the present invention will become coarse and dense, which is undesirable. The amount of PTFE added depends on the addition effect, mechanical From the viewpoint of strength and dispersibility, 3 to 80 parts by weight, preferably 5 to 5 parts by weight.
It is 0 parts by weight. If the amount of PTFE added is less than 3 parts by weight, the improvement in the coefficient of dynamic friction is insufficient. On the other hand, if the amount of PTFH added exceeds 80 parts by weight, the mechanical strength decreases and the amount of self-wear during sliding with metal increases, which is not preferable.

The amount of H leaves ε used in the present invention is 1 to 20 parts by weight, preferably 3 to IO parts by weight. The amount of HDPH added is 1
If it is less than 20 parts by weight, no effect of improving fluidity will be observed, and if it exceeds 20 parts by weight, the rigidity and heat resistance will be significantly reduced, and delamination of the injection molded product will be observed.

The method for blending the resin composition of the present invention is not particularly limited, but for example, mixing with a Henschel mixer, tumbler, etc., and then melt-mixing with a batch niegoo, Pan Bali mixer, single screw or twin screw extruder. can be mentioned.

Other inorganic and/or organic fillers may be added as necessary to provide the compositions of the present invention with even better mechanical strength, heat resistance, and sliding properties.

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, fiber, whisker, balloon, etc., but the resin composition of the present invention can have excellent low friction and wear resistance. In order to obtain a sufficient reinforcing effect, a powder or whisker form is preferable.

Specific examples of such fillers include clay, calcined clay, talc, catalytic acid, silica, alumina, magnesium oxide, calcium silicate, asbestos, sodium aluminate, calcium aluminate, sodium aluminosilicate, magnesium silicate, and water. Aluminum oxide, calcium hydroxide.

Barium sulfate, potassium light bread, sodium light bread,
Iron bread, whitebait balloon, glass balloon, carbon black, coke please, zinc oxide, antimony trioxide, boric acid, borax, zinc borate, metal powder, metal whisker, mica, graphite, titanium oxide, wollastonite, carbon fiber, Glass fiber, glass fiber powder, glass peas, calcium carbonate, zinc carbonate, hydrotalcite,
Examples include iron oxide.

The aromatic polyamide fibers and the above-mentioned 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, and these inorganic fillers may be used alone or in combination. More than one species can be used together.

The method of blending the filler is not particularly limited, and examples include the same blending method as aromatic polyamide fiber, PTFE, and HOPE.

Furthermore, depending on the required performance, other known polymers such as polybutadiene, butadiene-styrene copolymer, acrylic rubber, ethylene-propylene polymer, EPDM
, modified EPDM, styrene-butadiene block polymer, styrene-butadiene-styrene block polymer, styrene-butadiene-styrene radial teleblock polymer, polypropylene, butadiene-acrylonitrile copolymer, polyvinyl chloride, polycarbonate, PET
, PBT, polyacetal, polyamide, polyester, epoxy resin, polyvinylidene fluoride, polysulfone, ethylene-vinyl acetate copolymer, polyisoprene,
Natural rubber, chlorinated butyl rubber, chlorinated polyethylene, p
ps F#4 fat, polyetheretherketone, ppo
Y fat, styrene-methyl methacrylate copolymer, styrene-maleic anhydride copolymer, rubber modified PP (J P
The resin composition of the present invention may be blended as appropriate with a styrene-maleimide copolymer, a rubber-modified styrene-maleimide copolymer, or the like.

These polymers can be used alone or in combination of two or more.

Other lubricants such as molybdenum disulfide and silicone oil, pigments, flame retardants, anti-aging agents, stabilizers,
Antistatic agents and the like can be added.

The resin composition of the present invention has excellent sliding properties, so it can be used in bushings, bearings, scoops, slippers, etc.
We can provide various sliding parts such as guide rails, sealing materials, switch parts, gears, and cams.

(Examples) Hereinafter, the present invention will be specifically explained 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 ■Tensile test: Measured according to ASTM D 638 at a tensile speed of 50 mm/min.

■Bending test: Measured at a bending speed of 15 IllZ minutes according to ASTM D 790.

■Heat distortion temperature: 2 according to ASTM D 648
■Friction and wear test measured at 64 psi: A Suzumoto type friction and wear tester was used, and aluminum material was used as the mating material. The outer diameter of the test piece is 25.6mm.
A hollow cylindrical test piece with an inner diameter of 20.0 VO+ was used, and a counterpart material of the same shape was also used.

(a) Dynamic friction coefficient load 10Kg 1 surface pressure 5Kg/cm"), rotation speed 6
Measurement was performed under the condition of 0 rpm.

(b) Amount of wear: 20,000 rotations at a load of 10 and a rotational speed of 30 rpm (
The decrease in the weight of the test piece after traveling on a running road of 1.4 Kml L was measured and defined as the specific wear amount calculated from the following formula +11.

Formula (1) % Formula % Measured by the length of the spirally molded product (referred to as slab flow length). The measurement conditions are as follows.

Molding temperature: 320″C (Example 8 was 290′Cl
Mold temperature 80 °C Molded product wall thickness 2.0 ma+ Injection pressure 600 Kg/cm" Injection speed 30 cm"/sec Examples 1 to 6 Relative viscosity 3.70 (30'C in 197% sulfuric acid, concentration 1
Powdered polytetrafluoroethylene (PTFE) with an average particle size of 5 μm
, manufactured by Asahi Glass Co., Ltd., "Fluon L1 &9J", aromatic polyamide fiber A (manufactured by Yojinsha, r Technora T-3221)
, fiber length 1 mm, fiber diameter 12 μl11), and high-density polyethylene (HDPE, Mitsui Petrochemical Co., Ltd., RHIZEX 3300F J) were mixed in a tumbler at the composition ratio shown in Table 1, and then biaxially extruded. The pellets were melted and mixed using a machine (manufactured by Ikegai Tekko Co., Ltd., "Ikegai PCM45 II J") and made into pellets.
Various test pieces were obtained by injection molding under conditions of 0°C and mold temperature of 80'C, and their physical properties were measured using the above test method.

As a result, as shown in Table 1, the resin compositions of Examples 1 to 6 had excellent mechanical strength, heat resistance, and sliding properties as well as good fluidity when melted, which is the objective of the present invention. It can be seen that it is something like this.

Example 7 Nylon 4.6, PTFE, shown in Examples 1 to 6
HDPE, and aromatic polyamide fiber B (manufactured by Ryotaisha,
"Conex 1. Fiber length 0.6mm, fiber diameter 14μ
ff1) in the composition ratio shown in Table 1, Example 1
It was pelletized in the same manner as in 6 to 6, and its physical properties were measured. As a result, as shown in Table 1, this resin composition also had excellent mechanical strength similar to Examples 1 to 6.

It can be seen that it has not only heat resistance and sliding properties but also good fluidity when melted, which is the objective of the present invention.

Example 8 The same procedure as Example 1 was carried out except that nylon 66 was used instead of nylon 4.6.

Comparative Examples 1 to 5 Nylon 4.6, PTFE, aromatic polyamide fiber and IDPE shown in Examples were mixed in the proportions shown in Table 1, pelletized in the same manner as in Examples, and the physical properties were measured. did. The results are shown in Table 2.

Comparative Example 1 is an example of a composition that does not contain HDPE, and the fluidity of the molten resin is insufficient.

In Comparative Example 2, the content of HOPE exceeds the range of the present invention, and the mechanical strength and heat resistance of Comparative Example 2 are significantly lowered, and the surface of the molded product undergoes delamination, which is not preferable.

Comparative Example 3 is an example of a composition that does not contain PTFE,
The dynamic friction coefficient and the specific wear amount of resin and metal are large, which is undesirable.

Comparative Example 4 is an example that does not contain aromatic polyamide fibers, and has poor tensile strength and heat resistance. Furthermore, HDPE is undesirable because it causes delamination on the surface of the molded product.

In Comparative Example 5, the content of aromatic polyamide fibers exceeds the range of the present invention, which is undesirable because it increases the coefficient of dynamic friction and the specific wear amount of the metal.Furthermore, the fluidity of the molten resin is poor The desired fluidity of the molten resin cannot be improved.

Comparative Example 6 In Comparative Example 6, polypropylene (manufactured by Mitsui Petrochemical Co., Ltd., [i'J300J) was used instead of HDPE in Example 2, and the effect of improving the fluidity of the molten resin was small. The coefficient is high and undesirable.

Comparative Example 7 In Comparative Example 7, low-density polyethylene (Yukalon YK-30J, manufactured by Mitsubishi Yuka) was used in place of HDPH in Example 2, which was undesirable due to a large decrease in mechanical strength and heat resistance. .

(Effects of the Invention) As shown in the above examples, the resin composition of the present invention is obtained by adding a specific amount of aromatic polyamide fiber and a specific amount of polytetrafluoroethylene to a polyamide resin, and further adding a specific amount of polytetrafluoroethylene to a polyamide resin. By adding density polyethylene to the composition, the composition has good mechanical strength, heat resistance, and sliding properties, and also has excellent fluidity of the molten resin.

The resin composition of the present invention has excellent mechanical strength, heat resistance, and sliding properties, and also exhibits excellent fluidity when melted, so it is suitable for various applications centered on sliding members such as small mechanical parts. It is useful, especially for providing various parts such as bearings, switches, gears, etc. It is expected that small mechanical parts will become smaller and thinner in the future, and there is a demand for resin compositions that can produce such small and thin-walled molded products. This provides a suitable material.

Patent applicant: Japan Synthetic Rubber Co., Ltd.

Claims (1)

[Claims] (1) For 100 parts by weight of polyamide, (a) 1 to 80 parts by weight of aromatic polyamide fiber, (b) 3 to 80 parts by weight of polytetrafluoroethylene, and (c) 1 to 20 parts by weight of high-density polyethylene are blended. A polyamide resin composition characterized by: