JPH07116343B2 - Resin composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION a. Field of Industrial Application The present invention relates to a resin composition suitable for a sliding member, which is excellent in low friction and abrasion resistance, and also has excellent heat resistance and rigidity.

b. Conventional technology Polytetramethylene adipamide resin (Nylon 4,6
Has excellent heat resistance, toughness, and chemical resistance, and is expected to be put to practical use as a structural material in various applications. In particular, since it is extremely excellent in self-lubricating property as compared with other engineering resins, it is expected to be put into practical use as sliding parts such as bearing parts, gear parts, and mechanical parts requiring abrasion resistance.

Recently, plastic sliding members have expanded their applications to fields such as bearings that are non-lubricated and subject to severe wear under severe loads, pushers used under high ambient temperature conditions, and thin sliding parts. Therefore, with the expansion of this field of application, the performance requirements for plastic sliding members are becoming severe.

Generally, when plastic is applied to sliding parts such as bearings, in addition to the sliding characteristics that the dynamic friction coefficient is small, the limit PV value is high, the amount of wear is small, and the mating material is not damaged, it also has rigidity and creep resistance. It is desirable to use a material having excellent mechanical properties such as heat resistance and 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.
Withstands high speed and harsh conditions.

Nylon 4 and 6 have extremely good mechanical properties and heat resistance among polyamide resins.

c. Problems to be Solved by the Invention However, nylon 4 and 6 alone cannot sufficiently satisfy the sliding characteristics such as low friction and abrasion resistance required for the above sliding parts. At present, improvement of sliding characteristics has been desired.

The present inventors have conducted extensive studies to improve the sliding characteristics of nylon 4 and 6, and as a result, by blending nylon 4 and 6 with powdered polytetrafluoroethylene (PTFE) having a specific average particle diameter. It was found that the low friction property and the wear resistance were remarkably improved, and the present invention was accomplished based on such findings.

d. Means for Solving the Problems In the present invention, 40 to 2 parts by weight of powdery polytetrafluoroethylene (PTFE) having an average particle diameter of 15 μm or less is used with respect to 60 to 98 parts by weight of polytetramethylene adipamide. The present invention provides a resin composition containing the same.

The nylon 4,6 is a formula _{NH- (CH 2) 4 -NH-} CO- (CH 2) a polyamide consisting essentially of recurring structural units represented by the ₄ -CO.

For the production method of these nylons 4 and 6, see JP-A-56-14930.
No. 56-149431, No. 58-83029, Showa 60-288
The method described in No. 43 etc. can be mentioned.
To obtain the resin composition of the present invention, nylon 4 having a relative viscosity of at least 1.5, preferably _{2.5 to 5.0} (η _reL ; 30 ° C., 97% sulfuric acid, concentration: 10 ⁻² g / ml). It is advantageous to use 6,6.

The powdery PTFE used in the present invention has an average particle size of 15 μm or less,
It is preferably 10 μm or less. There is no particular lower limit to the average particle size. If the average particle size of PTFE exceeds 15 μm,
The surface of the molded article produced from the composition of the present invention becomes coarse and dense, which is not preferable.

The compounding amount of PTFE is 2 to 40% by weight, preferably 5 to 3% in the composition with nylon 4 and 6 from the viewpoint of addition effect and rigidity dispersibility.
It is 0% by weight. If the compounding amount of PTFE is less than 2% by weight, the effect of improving the dynamic friction coefficient and the specific wear amount is insufficient, and the limiting PV value cannot be sufficiently improved. On the other hand, if the compounding amount exceeds 40% by weight. It is not preferable because the mechanical strength and the heat distortion temperature tend to decrease.

The compounding method of PTFE is not particularly limited, and examples thereof include a method of mixing with a Henschel mixer, a tumbler and the like, and further a method of melt mixing with a batch kneader, a Banbury mixer, a single or twin screw extruder. Further, as another method, a method of directly molding while melt mixing in an injection molding machine is also possible.

When a filler is further added to the composition of the present invention, a resin composition having more excellent rigidity, high limiting PV value and heat distortion temperature can be obtained.

As the inorganic filler, those known as reinforcing fillers for rubber or plastics are used. The shape is not particularly limited as long as it is a solid, and may be in the form of powder, fibrous powder, fiber, whiskers, balloons, etc., while maintaining excellent low friction properties and abrasion resistance of the resin composition of the present invention. In order to obtain a sufficient reinforcing effect, a powdery or whisker-like one is preferable. Specific examples of the filler include clay, calcined clay, talc, catalbot, silica, alumina, magnesium oxide, calcium silicate,
Asbestos, sodium aluminate, calcium aluminate, sodium aluminosilicate, magnesium silicate, aluminum hydroxide, calcium hydroxide, barium sulphate, potassium alum, sodium amyvan, ironmeiban, silas balloon, glass balloon, carbon black , Coke breeze, zinc oxide, antimony trioxide, boric acid, borax,
Zinc borate, metal powder, metal whiskers, mica, graphite, titanium oxide, potassium titanate whiskers, carbon fiber, glass fiber, glass fiber powder, glass beads, calcium carbonate, zinc carbonate, hydrotalcite, iron oxide and the like. . Among these, titanates are particularly preferable, and whiskers thereof are particularly preferable, and potassium titanate whiskers are particularly preferable from the viewpoint of the balance of sliding characteristics and reinforcing effect. Glass fiber is not very preferable in terms of sliding specificity. The filler may be subjected to various surface treatments in order to further enhance the effects of the present invention. Moreover, these are used by 1 type (s) or 2 or more types.

The content of the filler in the resin composition is the resin composition of the present invention.
The amount is usually 60 parts by weight or less, preferably 5 to 60 parts by weight, and more preferably 10 to 40 parts by weight with respect to 100 parts by weight. Within this range, the purpose of adding the filler is achieved.

The mixing method of the filler is not particularly limited, and
A compounding method similar to that of PTFE can be mentioned.

Depending on the required performance, other known polymers such as polybutadiene, butadiene-styrene copolymer, acrylic rubber, ethylene-propylene polymer, EPD
M, styrene-butadiene block polymer, styrene-
Butadiene-styrene block polymer, styrene-butadiene-styrene radial tereblock polymer, polypropylene, butadiene-acrylonitrile copolymer, polyvinyl chloride, polycarbonate, PET, PBT, polyacetal, epoxy resin, polyvinylidene fluoride, polysulfone, ethylene- Vinyl acetate copolymer, polyisoprene, natural rubber, chlorinated butyl rubber, chlorinated polyethylene, PPS resin, polyether ether ketone, PPO resin,
Styrene-methyl methacrylate copolymer, styrene-maleic anhydride copolymer, rubber modified PPO resin, styrene-
A maleimide-based copolymer, a rubber-modified styrene-maleimide-based copolymer, etc. and the resin composition of the present invention may be appropriately blended and used.

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, antioxidants, stabilizers, etc.
Antistatic agents and the like can be added.

The resin composition of the present invention has excellent sliding properties, and therefore has a pushing, a bearing, a scoop, a slipping,
Various sliding parts such as guide rails, sealing materials, switch parts, gears, cams can be provided.

e. Examples Hereinafter, the present invention will be described in detail 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 methods.

Test method Tensile strength: ASTM D638 Tensile speed 50mm / min Heat distortion temperature (HDT): ASTM D648 Load 18.6Kg For friction and wear test, use Suzuki type friction and wear tester, and use cylindrical steel as mating material. , Friction speed (V) 30cm /
The coefficient of dynamic friction was determined under the conditions of second and load (P) of 10 kg / cm ² .

The specific amount of wear was defined as the amount of wear per unit weight and unit weight when the friction distance reached 10 Km under continuous operation under the above conditions. The relative material specific wear amount was defined in the same manner.

The limit PV value was determined by changing the load with a constant friction speed of 30 cm / sec and determining the time when melting or significant wear occurred.

Examples 1 to 4 Nylon 4,6 having a relative viscosity of 3.56 (measured in 97% sulfuric acid at 30 ° C. and a concentration of 10 ⁻² g / ml) and powdered polytetrafluoroethylene having an average particle diameter of 4 μm [Asahi Glass Co., Ltd. L169 ], Table-1
The compounding recipe shown in 1 was mixed in a tumbler, and then melt-mixed and pelletized by using an extruder. The pellets were molded under the conditions of a molding temperature of 300 ° C. and a mold temperature of 80 ° C., and their physical properties were evaluated by the above-mentioned test methods.

As a result, the resin compositions of Examples 1 to 4 had the sliding characteristics, heat resistance, and rigidity that were the objects of the present invention.

Examples 5 to 8 With respect to 100 parts by weight of the resin compositions of Examples 1 to 4, 20 aminosilane-treated potassium titanate whiskers (Otsuka Chemical Co., Ltd., Tismo D101, average fiber length 14 μm, aspect ratio 14) were used. The physical properties of the molded product when mixed by weight are
The results are shown in Table 1 as Examples 5-8.

With the addition of potassium titanate whiskers Examples 1-
The resin composition of No. 4 has improved tensile strength and heat distortion temperature while maintaining its excellent low friction property and low abrasion property, and has a limit.
It can be seen that the PV value becomes high.

Comparative Examples 1 to 3 A resin composition obtained by blending each component according to the formulation shown in Table 2 was pelletized and injection-molded in the same manner as in Examples to prepare test pieces, and their physical properties were evaluated. evaluated. The results are shown in Table-2.

As a result, Comparative Example 1 shows the physical properties of nylon 4 and 6 alone, and although the rigidity and heat resistance are slightly superior to those of Examples 1 to 4, the dynamic friction coefficient, the specific wear amount, and the mating material ratio. A large amount of wear. Also, the limit PV value is significantly inferior to that of the example.

Further, Comparative Examples 2 and 3 show physical properties of molded articles of resin compositions in which the compounding ratio of each component is outside the range of the present invention.
Comparing the results with Examples 1 to 4, when the compounding amount of PTFE is less than 2% by weight, the intended improvement of the sliding characteristics is insufficient, while when it exceeds 40% by weight, the rigidity is lowered. This is extremely unfavorable.

Comparative Examples 4 to 7 Nylon 6 and Nylon 6,6 were used in place of Nylon 4,6, and pelletized and injection molded in the same manner as in Examples according to the formulation shown in Table 2 to prepare test pieces,
The physical properties were evaluated. The results are shown in Table-2.

In Comparative Examples 4 and 6, when only PTFE was mixed, Comparative Example 5 and
No. 7 shows physical properties when potassium titanate whiskers were further added as a filler.

As a result, in each comparative example, Example 3 using nylon 4 and 6 was used.
Compared with Example 7, the relative wear amount of the mating material is slightly reduced, but other sliding characteristics are passed and the mechanical strength is also reduced. Especially, the decrease of the limit PV value is remarkable, nylon 4,
It is understood that good sliding characteristics can be obtained only by using 6.

Comparative Examples 8 to 11 According to the formulation shown in Table 3, pelletization and injection molding were performed in the same manner as in Examples to prepare test pieces, and their physical properties were evaluated. The results are shown in Table-3.

As a result, Comparative Examples 8 and 9 are inferior to Example 1 in heat resistance and limit PV value. Comparative Examples 10 and 11
The same is true when compared with Example 2.

f. Effects of the invention As shown in the above examples, the resin composition of the present invention,
By blending a specific amount of powdered PTFE having a specific average particle diameter, the excellent sliding properties of nylon are further improved. Further, as shown in Examples 5 to 8, when potassium titanate whiskers are used together, a resin composition having a high limit PV value and mechanical strength in addition to low friction and abrasion resistance can be obtained.

Furthermore, sliding members used under particularly severe conditions are generally required to have a limit PV value of 2000 Kg / cm ² · cm / sec or more, but as shown in Comparative Examples 4 to 7, ,Nylon
When other aliphatic polyamides such as nylon 6 and nylon 6,6 were used in place of 4,6, the required physical properties were not satisfied, which was about 1400 to 2000.

However, the resin composition of the present invention can obtain a limiting PV value of about 1800 to 2600 by using nylon 4 and 6, and can be sufficiently used even under severe conditions.

INDUSTRIAL APPLICABILITY The resin composition of the present invention has excellent sliding properties, and also has excellent heat resistance, toughness, and chemical resistance, and thus is useful for various applications centering on sliding members, and particularly for bearings. , We can provide various parts such as switches, gears,
Its industrial utility value is extremely high.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Fumio Kurihara 2-11-24 Tsukiji, Chuo-ku, Tokyo Inside Nippon Synthetic Rubber Co., Ltd. (72) Shinichi Kimura 2-11-24 Tsukiji, Chuo-ku, Tokyo Within Japan Synthetic Rubber Co., Ltd. (56) Reference JP-A-59-75948 (JP, A) JP-A-48-93862 (JP, A) JP-A-60-44544 (JP, A) JP-A-60- 258251 (JP, A)

Claims (1)

[Claims] 1. Improving sliding properties, characterized by containing 40 to 2 parts by weight of powdered polytetrafluoroethylene having an average particle diameter of 15 μm or less with respect to 60 to 98 parts by weight of polytetramethylene adipamide. Resin composition.