JPS6363766B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a control cable consisting of an outer tube and an inner cable inserted into the outer tube. More specifically, the control cable significantly improves the lubricity, abrasion resistance, bending elasticity, and thermal deformation temperature of the coating layer provided on the inner cable of the control cable or the liner interposed between the inner cable and the outer tube. Regarding cables. The outer tube of the control cable is, for example, a flexible one made by spirally winding at least one metal wire, one made of plastic or rubber, or one in which the metal spiral tube is covered with plastic or rubber. It consists of The inner cable is made of one metal wire or a combination of several metal wires twisted together. The control cable configured in this way can rotate or actuate in the axial direction within the outer tube of the inner cable (e.g. push/pull operation), and can also perform simultaneous rotation and actuation in the axial direction to remotely control passive devices. It has the effect of Such control cables are widely used, for example, for remotely controlling various devices such as transmissions, brakes, clutches, etc. in automobiles, motorcycles, bicycles, etc. Therefore, in order to operate the control cable smoothly, it is necessary to reduce the frictional resistance between the inner surface of the outer tube and the inner cable as much as possible, and for this reason, it has traditionally been necessary to use materials such as high-density polyethylene or polyacetal on the inner cable. Often, a synthetic resin coating layer is provided, or a similar synthetic resin liner is interposed between the outer tube and the inner cable. On the other hand, control cables for low-pollution vehicles, which have become a serious issue in recent years, are required to be able to operate smoothly at all times, even at temperatures as low as -40℃ and as high as 145℃. In addition, the coating layer and liner have sufficient abrasion resistance and lubricity to withstand the aforementioned rotation and axial movement of the inner cable within the outer tube, which is the original function of the control cable. must be maintained. In particular, it is required to have sufficient abrasion resistance to withstand repeated use over a long period of time under high loads, and to have lubricity to allow the inner cable to operate smoothly. However, the coating layer or liner made of high-density polyethylene becomes unusable at about 100℃ due to its low softening point, and the coating layer or liner made of polyacetal has low friction, abrasion, and bending properties at temperatures above 120℃. They have poor elasticity and cannot be said to be satisfactory as coating layers or liners for high-performance control cables. However, as a result of intensive research in order to provide a completely new coating layer or liner for control cables that can eliminate the above-mentioned drawbacks, the inventors have developed polybutylene terephthalate (hereinafter referred to as PBT).
A coating layer formed from a composition obtained by mixing POM) and polyoxymethylene (hereinafter referred to as POM) is provided on the inner cable, or a liner formed from the composition is provided between the outer tube and the inner cable. When interposed, the above-mentioned drawbacks are eliminated, and not only heat resistance and cold resistance, but also abrasion resistance, slipperiness, and bending elasticity are significantly improved, and the product operates smoothly even under repeated use over a long period of time under high loads. The present inventors have discovered a new fact that it is possible to provide a control cable that can perform the same functions, and have completed the present invention. The mixing ratio of PBT and POM is PBT by weight:
POM=2:8~8:2, especially 6:5~5:5
is preferred. When PBT is less than the above range,
It is not desirable because it does not have sufficient heat resistance and cold resistance, which are the characteristics of PBT, and its abrasion resistance deteriorates.
When the PBT content exceeds the above range, the rigidity, which is a characteristic of POM, and especially the surface hardness of the resin decreases, resulting in poor friction and wear resistance. Hereinafter, the control cable of the present invention will be explained using the drawings. FIG. 1 is a partially cutaway side view showing one embodiment of the control cable of the present invention, and FIG. 2 is a partially cutaway side view showing another embodiment of the control cable of the present invention. In Figures 1 and 2, 1 is a flexible outer tube made of spirally wound flat steel wire, 2 is an inner cable inserted into the outer tube 1, and the inner cable 2 is made of several metal wires. It is made by twisting strands of wire. In the embodiment of FIG. 1, on the surface of the inner cable 2,
A coating layer 3 made of a composition of PBT and POM is provided. In another embodiment shown in FIG. 2, the coating layer 3 is provided between the outer tube 1 and the inner cable 2
A liner 4 having a similar composition is provided. Furthermore, any means may be used to form the coating layer 3 or the liner 4 using the obtained composition, but it is preferable to use an extruder in terms of work efficiency. sell. The coating layer 3 or liner 4 thus formed
The thickness of the tube may be approximately 0.3 mm or more and may be appropriately selected within a range that allows the inner cable 2 to rotate or slide within the outer tube 1. Next, the control cable of the present invention will be explained with reference to Examples and Comparative Examples. Examples 1 to 3 and Comparative Examples 1 to 2 PBT (polybutylene terephthalate manufactured by Mitsubishi Chemical Industries, Ltd.) and POM (polyoxymethylene manufactured by Polyplastics Co., Ltd.) were uniformly mixed in the proportions shown in Table 1. Then, a composition used in the present invention and a comparative composition were prepared.

[Table] The following tests were conducted using each of the compositions thus obtained. Heat Deformability The compositions prepared in Examples 1 to 3 and Comparative Examples 1 to 2 were molded into sample (5) shown in Figure 3 using a vertical injection molding machine (RN type) at a pressure of 5 kg/ ^cm2 . Created. Using this sample, the heat distortion temperature was examined according to the method specified in ASTM D-648 (18.6°C).
The results are shown in Table 2. Bending elasticity Using the same sample as that used in the thermal deformability test, the bending elasticity was examined according to the method specified in ASTM D-790. The results are shown in Table 2. Friction resistance and abrasion resistance Samples were prepared by molding the compositions prepared in Examples 1 to 3 and Comparative Examples 1 to 2 into a ring shape with an inner diameter of 20.0 mm and an outer diameter of 25.6 mm. Using a Suzuki friction and wear tester (EFME) manufactured by Co., Ltd., the sample was tested at a linear velocity of 30 cm/sec and a pressure of 5.
The coefficient of friction (at room temperature) was measured by rotating a metal (S45C) piece at Kg/cm ² . In addition, for the wear coefficient (at room temperature), a 160 mesh stainless steel net was used as the metal piece. The results are shown in Table 2.

[Table] As is clear from Table 2, used in the present invention
A molded article made from a composition of PBT and POM
It combines the heat resistance and durability of PBT with the abrasion resistance of POM. Next, the compositions prepared in Examples 1 to 3 and Comparative Examples 1 to 2 were extruded using an extruder to obtain liners having an inner diameter of 3.7 mm and an outer diameter of 5.6 mm.
Next, an inner cable (length 1300 mm) made of 3 mm double-twisted galvanized steel wire is inserted into the liner, and then the entire cable is passed through an outer pipe (length 1000 mm) with an outer diameter of 10 mm to form the control cable shown in Figure 2. I got it. The durability of each control cable obtained was examined. The results are shown in Table 3. The durability test was carried out by bending each control cable in a constant temperature bath controlled at 120℃ with a radius of 250mm.
The inner cable was bent into a shape, a 50 kg weight was suspended from one end of the inner cable, the other end of the inner cable was pulled and relaxed at a rate of 50 times per minute with a stroke of 27 mm for 8 hours, and then removed from the thermostatic oven and left at room temperature. tension and relaxation under the same conditions.
The test was repeated for 16 hours by alternately repeating this test at 120° C. and at room temperature. The evaluation was expressed by the η value calculated by the following formula. η (%)=W/F×100 In the formula, F is frictional resistance and W is load.

[Table] As is clear from Table 3, the control cable of the present invention shows a slight decrease in η value and has excellent durability. on the other hand,
In the case of PBT alone, the η value decreases rapidly,
After 1 million cycles, it was 70-75% and could not be used as a control cable. Also
In the case of POM alone, it was 65-70% after 1 million cycles, almost the same as PBT, and could not be used as a control cable. In the above embodiments, a control cable in which a liner was interposed between the outer pipe and the inner cable was explained, but a coating layer (PBT:POM=50:50) could be provided on the inner cable instead of the liner. When a similar durability test was conducted on the control cable, the η value was 87% after repeated tension and relaxation 1 million times, indicating excellent durability.

[Brief explanation of drawings]

Fig. 1 is a partially cutaway side view showing one embodiment of the control cable of the present invention, Fig. 2 is a partially cutaway side view showing another embodiment of the control cable of the present invention, and Fig. 3 shows thermal deformability and bending. FIG. 3 is a longitudinal cross-sectional view of a sample used in an elasticity test. Reference numbers in the drawings: 1: outer pipe, 2: inner cable, 3: covering layer, 4: liner, 5: sample for bending elasticity test.

Claims (1)

[Scope of Claims] 1. In a control cable consisting of an outer tube and an inner cable inserted into the outer tube, the inner cable is coated with a coating layer formed from a composition made of a mixture of polybutylene terephthalate and polyoxymethylene. A control cable comprising a liner provided thereon or formed from the composition described above and interposed between the outer tube and the inner cable. 2. The control cable according to claim 1, wherein the weight ratio of the polybutylene terephthalate to polyoxymethylene is 2:8 to 8:2.