JPH1036679A - Resin composition for sliding member and molding made therefrom - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a resin composition which can give a sliding member which is lightweight and has a suitable coefficient of dynamic friction and improved strengths, abrasion resistance and slidability by mixing potassium titanate whiskers with carbon fibers, a polytetrafluoroethylene, and a thermoplastic resin. SOLUTION: This composition is obtained by mixing a thermoplastic resin with 15-30 pts.wt. potassium titanate whiskers having an average fiber diameter of 0.1-2μm and an average fiber length of 5-100μm and an aspect ratio of 10 or above, 15-35 pts.wt. carbon fibers having a tensile modulus of 3,500,000kgf/cm<2> or above, a fiber diameter of about 10μm and a fiber length of 0.5-6mm, and 5-15 pts.wt. polytetrafluoroethylene having a mean particle diameter of 50μm or below.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a resin composition for a sliding member.

[0002]

2. Description of the Related Art An ultrasonic motor generates a traveling wave on a stator by means of a piezoelectric material and causes the traveling wave to act on a rotor pressed against the stator.
The rotor is rotated. Generally, the rotor is made of aluminum, and a slider is bonded to a surface of the rotor in contact with the stator so that traveling waves can effectively act on the rotor, so that appropriate friction is generated between the two.

[0003] As a slider member used in such an ultrasonic motor, Japanese Patent Application Laid-Open No. 63-265574 uses a fluorocarbon polymer such as polytetrafluoroethylene (PTFE), and uses an aromatic polyamide fiber or carbon fiber. It has been proposed to use a plastic member containing the following fibers. In addition, Japanese Patent Laid-Open No. 1-1
JP 07675 proposes to use a resin such as a polyimide, a phenol resin, or a liquid crystalline polymer in addition to the fluorocarbon polymer. Japanese Patent Application Laid-Open No. 1-248975 proposes to use a friction material containing a fluorinated resin as a main component and dispersedly filled with whiskers such as calcium whisker.

A conventional slider member uses a resin composition containing a fluororesin such as polytetrafluoroethylene. Therefore, injection molding is generally difficult. For example, in a conventional slider member, a resin composition (which cannot be injection-molded) in which Econol E101 which is an aromatic polyester resin is filled in polytetrafluoroethylene (PTFE) is formed into a sheet having a thickness of 0.2 to 0.5 mm. The processed product is punched into the slider shape shown in the drawing and bonded to an Amir rotor with an adhesive such as epoxy resin to generate an appropriate frictional force between the stator and the aluminum rotor, and It had wear properties. For this reason, processing is troublesome, and it is difficult to reduce the weight of the rotor portion.

Japanese Patent Laid-Open Publication No. 1-10066 discloses a slider member which is formed by injection molding a resin containing whiskers such as potassium titanate.
Since no fluororesin such as polytetrafluoroethylene is contained, there is a problem that the sliding property is poor.

Accordingly, the present invention provides a resin composition which can be easily molded by injection molding, is lightweight and has high strength, has a suitable dynamic friction coefficient as a sliding member, and has excellent wear resistance. It is an object of the present invention to provide a molded article.

[0007]

That is, the present invention relates to a method for producing a whisker of potassium titanate in an amount of 15 to 30 parts by weight,
5 to 35 parts by weight, polytetrafluoroethylene 5 to 15
The present invention relates to a resin composition for a sliding member including a part by weight and the remainder being a thermoplastic resin, and a molded article using the same.

The resin composition for a sliding member of the present invention can be particularly preferably used as a material for a rotor or a slider of an ultrasonic motor. When using the resin composition for a sliding member of the present invention as a rotor material of an ultrasonic motor,
The whole can be composed of the resin composition of the present invention. Further, the slider portion can be made of the resin composition of the present invention.

[0009]

DETAILED DESCRIPTION OF THE INVENTION The resin usable in the present invention is not particularly limited, but engineering plastics, especially polyphenylene sulfide, polyether sulfone, polyether imide, liquid crystal, etc. Heat-resistant engineering plastics such as polymers, polyetheretherketone, polyetherketone, polyamideimide, and polyimide are suitable, and among them, polyphenylenesulfide is most practical at present.

As potassium titanate whiskers, commercially available average fiber diameter of 0.1 to 2 μm and average fiber length of 5 to 100
μm can be used as it is, and those having an aspect ratio (average fiber length / average fiber diameter) of 10 or more are desirable from the viewpoint of the reinforcing effect. Potassium titanate whiskers have a Mohs hardness of 4 and a mating material (using a relatively soft metal such as phosphor bronze as a stator), in addition to the strength and flexural modulus improvement effects of whiskers (single crystal fibers). It is not harmful, and is effective in generating a frictional force for following the traveling wave generated in the stator. In addition, because of the micro-reinforced fibers (typically, the average fiber diameter is 0.3 μm and the average fiber length is 15 μm), there is also a function of making the surface of the molded article very smooth (improving the mold transferability). .

The reason for limiting the blending amount to 15 to 30 parts by weight is that if the amount is less than 15 parts by weight, the flexural modulus is improved, the frictional force is maintained, and the surface smoothness of the molded product is maintained (the surface of the molded product is used in combination with carbon fibers) The effect is reduced, while 30
Exceeding the parts by weight, the necessary amount of carbon fiber, which has a large effect of improving flexural modulus and abrasion resistance, and PTFE, which has a large effect of preventing abrasion powder, is added while maintaining the fluidity during injection molding. This is because it becomes difficult to do so.

[0012] As a carbon fiber, the effect of improving the bending elastic modulus
Large tensile modulus of 3.5 million kgf / cm^TwoMore ammunition
Carbon fiber is desirable, but the tensile modulus is 2.4 million kgf /
cm ^TwoThe above high strength carbon fibers can be used satisfactorily.
You.

Conventionally, the PAN system was good in performance,
Recently, pitch systems can be used satisfactorily. Commercially available products usually have a fiber diameter of about 10 μm, and the fiber length is 0.5 to 6 mm, especially 6 mm, due to the reinforcing effect and processability (extrusion molding during pellet production and injection molding during sliding member production). General and excellent in performance.

The compounding amount is suitably from 15 to 35 parts by weight. If the amount is less than 15 parts by weight, it is difficult to bring the flexural modulus of the resin composition to 150,000 kgf / cm ² or more. If the number is more than the above, the workability, especially the extrudability during the production of pellets, is poor, and the smoothness of the sliding surface of the molded article during injection molding is undesirably impaired.

The polytetrafluoroethylene powder preferably has an average particle size of 50 μm or less,
Fine powder of 0 μm or less is desirable. Polytetrafluoroethylene has the function of improving the abrasion resistance (by reducing the generation of friction powder) of the resin composition by improving the slidability (lubricity) with the partner material (phosphor bronze). The compounding amount is suitably from 5 to 15 parts by weight. If the amount is less than 5 parts by weight, the effect is small. If the amount exceeds 15 parts by weight, not only the flexural modulus of the resin composition but also the strength (particularly impact strength) ) Has been found to be uneconomical, and the PTFE itself is rather expensive.

To produce the resin composition of the present invention, a thermoplastic resin, potassium titanate whisker, carbon fiber, and polytetrafluoroethylene powder are weighed in predetermined amounts,
In general, a method of uniformly mixing with a blender such as a tumbler mixer, kneading with a melt kneader such as an extruder, and then pelletizing.

Further, the resin composition of the present invention can be injection-molded very efficiently by setting a cylinder temperature, a mold temperature, an injection pressure, and an injection time of an injection molding machine according to a thermoplastic resin to be used. Is possible.

In the resin composition of the present invention, potassium titanate whisker or a part of carbon fiber is mixed with talc, mica, or talc so long as the basic physical properties and moldability are not impaired.
It is also possible to replace it with an inorganic filler such as graphite, and of course, it is also possible to mix a coloring agent such as carbon black or a heat stabilizer suitable for the thermoplastic resin used.

The resin composition of the present invention can be easily molded by injection molding, and is lightweight and has high strength. Further, it is a resin composition having a suitable dynamic friction coefficient as a sliding member and having excellent wear resistance. Furthermore, the resin composition of the present invention exhibits excellent strength and slidability even under high humidity conditions.

[0020]

The following examples are provided to further illustrate the present invention.
I will do it.Examples 1 to 5 and Comparative Examples 1 to 3 FORTRON W205 (PPS: Polyplastics)
Co., Ltd.), TISMOD102 (potassium titanate fiber)
Wei: Otsuka Chemical Co., Ltd.), Vesfight HTA-C6-N
R (carbon fiber: Toho Rayon Co., Ltd.), Fluon L15
0J (polytetrafluoroethylene: Asahi Glass Co., Ltd.)
After weighing according to the composition shown in Table 1, mixed with a blender,
Using a 45mm extruder, mix at a cylinder temperature of 300 ° C.
While kneading and extruding, it was pelletized with a cutter. The obtained pe
Let the cylinder temperature 300 ° C, mold temperature 130 ° C,
Injection pressure 1200kgf / cm^Two, 600kgf /
cm ^TwoThe rotor was injection molded.

Incidentally, in order to examine the basic physical properties of the same material, the following test pieces were molded under the same conditions as above using a metal mold for measuring physical properties, and various physical properties were measured. Table 1 shows the results. Specific gravity: Measured with an ASTM D792 Izod impact piece Flexural modulus: ASTM D790 Sliding characteristics: Suzuki friction and wear tester (manufactured by Toyo Baldwin Co.) Counterpart material: phosphor bronze (JIS C 5341), surface pressure 1
0 kgf / cm ² , peripheral speed 30 cm / sec, traveling distance 10 km

[0022]

[Table 1]

A rotor produced by injection molding the resin composition of each composition shown in Table 1 was incorporated into an ultrasonic motor in which the rotor 3 and the slider 3a shown in the drawing were integrated, and a motor test was performed by actual machine tests. Was evaluated. In the ultrasonic motor, a piezoelectric body 2 is adhered to a stator 1, and when a driving signal is applied to the piezoelectric body 2, a traveling wave is generated in the stator. Further, the rotor 3 is pressed against the stator 1 by a spring material 4 and is rotated by a traveling wave of the stator.

Test results show that when the thermoplastic resin of Comparative Example 1 exceeds 60 parts by weight and the flexural modulus is less than 13 kgf / cm ² , the motor rotates, but the current value is high and the efficiency is poor. On the other hand, a resin composition comprising 15 to 30 parts by weight of potassium titanate whiskers, 15 to 35 parts by weight of carbon fiber, and 5 to 15 parts by weight of polytetrafluoroethylene powder as shown in Examples 1 to 5, and the balance being a thermoplastic resin Has a flexural modulus of elasticity of 13 kgf / cm ² or more,
The drive current value of the motor was not so different from the current product, and the efficiency was good.

In particular, the rotor prepared from Example 5 had a small current value, good motor efficiency, no generation of wear powder after 500 hours of operation, and no wear of the stator.

On the other hand, the polytetrafluoroethylene of Comparative Example 2 containing less than 5 parts by weight of the polytetrafluoroethylene and the potassium titanate whisker of Comparative Example 3 containing less than 15 parts by weight of the polytetrafluoroethylene were less than the former after 100 hours of operation. It was found that a large amount of abrasion powder was generated and the stator abrasion (damage) was large, and the latter was also large in stator abrasion and poor in practicality.

From these facts, the motor characteristics are greatly related to the bending elastic modulus of the rotor, and considering the durability of the ultrasonic motor, it is considered that the resin composition for sliding members within the scope of the present invention is appropriate. Can be concluded.

Example 6 In the same manner as in Examples 1 to 5, Ultem 1010 (polyetherimide: GE), TISMO D102 (potassium titanate fiber: Otsuka Chemical Co., Ltd.), Vesphite H
TA-C6-NR (carbon fiber: Toho Rayon Co., Ltd.),
Fluon L150J (polytetrafluoroethylene: Asahi Glass Co., Ltd.) was blended as shown in Table 2 to produce pellets with a kneading extruder having a cylinder temperature of 340 ° C.

The obtained pellets were heated at a cylinder temperature of 370.
° C, mold temperature 140 ° C, injection pressure 1200kg / c
A rotor and a test piece for measuring physical properties were injection molded at m ² and a holding pressure of 600 kgf / cm ² .

Table 2 shows the measured physical properties of the same material.

[0031]

[Table 2]

The rotor injection-molded with this composition was tested on an actual machine, and the motor characteristics were measured. As a result, good motor characteristics were obtained.

[Brief description of the drawings]

FIG. 1 is a perspective view in which a part of a synthetic resin rotor for an ultrasonic motor is broken.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Stator 3 ... Rotor 3a ... Slider

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification number Agency reference number FI Technical display location (C08L 101/00 27:18) (72) Inventor Shinji Sagara Okura-gun, Oraku-gun, Gunma Prefecture Kurakake 1508-2 Kurakake Daiichi Industrial Park Fukoku Gunma Plant Co., Ltd. (72) Inventor Eiji Akiyu Kuraku 1508-2 Kurakake Daiichi Industrial Park Fukuk Gunma Plant Co., Ltd.

Claims (3)

[Claims] 1. A potassium titanate whisker 15 to 30.
A resin composition for a sliding member, comprising parts by weight, 15 to 35 parts by weight of carbon fiber, and 5 to 15 parts by weight of polytetrafluoroethylene, and the balance being a thermoplastic resin. 2. The sliding member according to claim 1, wherein the thermoplastic resin is polyphenylene sulfide, polyether sulfone, polyether imide, liquid crystal polymer, polyether ether ketone, polyether ketone, polyamide imide, or polyimide. Resin composition. 3. A molded article obtained by molding using the resin composition for a sliding member according to claim 1 or 2.