JPH11105097A - Tube and control cable for car using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a tube having excellent mechanical strength and excellent heat resistance exceeding 180 deg.C and capable of being produced by a thermoplastic extrusion method excellent in productivity, and a control cable for a car using the same as an outer casing. SOLUTION: A tube is obtained by the extrusion molding of a compsn. prepared by mixing 2-10 pts.wt. of a tetrafluoroethylene micropowder with 100 pts.wt. of a copolymer based on ethylene and tetrafluoroethylene and, as the tetrafluoroethylene micropowder, low mol.wt. polytetrafluoroethylene particles with an average particle size of 50 μm or less are used. A control cable for a car uses the above mentioned tube as an outer casing.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a tube which has both excellent mechanical strength and excellent heat resistance exceeding 180 ° C., and which can be produced by a thermoplastic extrusion method which is excellent in productivity. The present invention relates to an automobile control cable using this tube as an outer casing.

[0002]

2. Description of the Related Art Conventionally, ethylene-tetrafluoroethylene has been used as an insulating material for electric wiring used in applications requiring mechanical strength and heat resistance, such as in an engine room of an automobile. Although a polymer (ETFE) is used, it is desired to further improve the heat resistance of ETFE with the increase in the temperature due to the compactness of the engine room of the automobile and the high performance and high output of the engine. .

As methods for improving the heat resistance of ETFE, there are known methods for changing the structure of the polymer itself, such as changing the copolymerization ratio of ETFE and copolymerizing a third component. Also, JP-A-59-1001
No. 41, Japanese Patent Application Laid-Open No. 7-14431 or Japanese Patent Application Laid-Open
No. -14667 discloses a method in which ETFE is mixed with a rubber having excellent heat resistance, for example, a fluororubber and crosslinked. According to the above publication, excellent heat resistance exceeding 180 ° C. is obtained.

In an engine room of an automobile, a control cable including a cable as a core material and an outer casing tube as a sheath material is used in addition to electric wiring. The tubes that make up the outer casing of this automotive control cable are required to have not only heat resistance, but also excellent mechanical strength that will not be worn out even by severe contact with the cable, and that have excellent inner surface slipperiness. From being
Conventionally, polytetrafluoroethylene copolymer (PT
FE) mixed with carbon fiber or polyamide-imide resin powder and molded.

[0005]

However, in the above-mentioned technology for improving the heat resistance of ETFE, the mechanical strength such as abrasion resistance is sacrificed. There was a problem that the cost increased due to the increase in the number.

Further, a tube as an outer casing of an automobile control cable formed by mixing PTFE with carbon fiber or polyamide-imide resin powder cannot be lengthened because the manufacturing process is batch production, and the cost is reduced. There was a problem of rising.

The present invention has been made on the basis of the above points, and the object is to combine excellent mechanical strength with excellent heat resistance exceeding 180 ° C. and excellent productivity. An object of the present invention is to provide a tube that can be manufactured by a thermoplastic extrusion method and a control cable for an automobile using the tube as an outer casing.

[0008]

In order to achieve the above-mentioned object, a tube according to the present invention comprises at least 2 parts by weight of tetrafluoroethylene micropowder with respect to 100 parts by weight of a copolymer mainly composed of ethylene and tetrafluoroethylene. It is characterized in that a composition obtained by mixing 10 parts by weight or less is extruded. At this time, it is conceivable to use low molecular weight polytetrafluoroethylene particles having an average particle diameter of 50 μm or less as the tetrafluoroethylene micropowder. An automobile control cable according to another aspect of the present invention is characterized in that the above tube is used as an outer casing.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Known copolymers mainly composed of ethylene and tetrafluoroethylene include binary copolymers having various polymerization ratios and multipolymers copolymerized with other fluorine-containing monomers. And any of them may be used.

[0010] Tetrafluoroethylene micropowder is mainly used to improve the heat resistance and mechanical strength (particularly, abrasion resistance) of the obtained tube, and mainly comprises ethylene and tetrafluoroethylene. 2 parts by weight or more and 10 parts by weight or less with respect to 100 parts by weight of the copolymer. If the mixing amount is less than 2 parts by weight, the effect of improving the heat resistance will not be exhibited, and if it exceeds 10 parts by weight, the mechanical strength (particularly, elongation) and appearance will decrease.

[0011] Examples of the tetrafluoroethylene micropowder include low molecular weight polytetrafluoroethylene particles. Although various particle diameters are known, in the present invention, the average particle diameter is preferably 50 μm or less, more preferably 0.1 μm or more and 20 μm or more.
Particles of a low molecular weight polytetrafluoroethylene having a size of not more than μm are used. If the average particle diameter exceeds 50 μm, the kneading operation becomes extremely difficult because the particles are not uniformly dispersed in a copolymer mainly composed of ethylene and tetrafluoroethylene. Those having an average particle diameter of 0.1 μm or more and 20 μm or less are easily dispersed and kneaded uniformly in a copolymer mainly composed of ethylene and tetrafluoroethylene, and the obtained tube has a remarkably high mechanical strength. It is particularly preferable for improvement.

In the present invention, in addition to the above components,
Fluorine rubber may be further mixed. Fluororubber has a function of assisting the mixing of a copolymer mainly composed of ethylene and tetrafluoroethylene and a tetrafluoroethylene micropowder. Coalescing 1
It is preferable that the amount is about 0.1 part by weight or more and 5 parts by weight or less based on 00 parts by weight. As the fluorine rubber, vinylidene fluoride based, tetrafluoroethylene-propylene based, etc.
Any conventionally known one can be used, and a vinylidene fluoride copolymer plastic having a low melting point is also included in this. The fluororubber may be used as a masterbatch base for tetrafluoroethylene micropowder, or may simply be allowed to coexist when mixing the tetrafluoroethylene micropowder.

Various known additives such as fillers and pigments are added to each of the constituent materials described above, preferably at a processing temperature of 20%.
After appropriately mixing an additive that does not cause decomposition or foaming at a temperature of 0 ° C. or more and 400 ° C. or less as necessary, an internal mixer, a single-screw kneader, a known kneader such as a twin-screw kneader is used. The resulting composition is extruded using a known extruder to complete the tube of the present invention. At this time, heat resistance can be further improved by performing crosslinking by a known method.

[0014]

EXAMPLES Examples of the present invention will be described below together with comparative examples. As a copolymer mainly composed of ethylene and tetrafluoroethylene, ETFE (trade name: Tefzel 750, manufactured by Mitsui DuPont Fluorochemicals Co., Ltd.) is used. As a tetrafluoroethylene micropowder, an average particle diameter is 3 μm. Low molecular weight polytetrafluoroethylene particles were used.

In Examples 1 to 3 and Comparative Examples 1 and 2, the blended materials shown in Table 1 were sufficiently kneaded with a twin-screw kneader, and the resulting composition was pelletized. ,
It is supplied to a 50 mmφ extruder with L / D = 24 and has an inner diameter of 4.degree.
A tube having a diameter of 5 mm and an outer diameter of 6.5 mm was extruded.

In Example 4, among the blended materials shown in Table 1, first, vinylidene fluoride-based fluororubber and low molecular weight polytetrafluoroethylene particles were kneaded with a roll,
Thereafter, the mixture was mixed with ETFE and kneaded sufficiently with a single-shaft kneader equipped with a mixing zone. Next, after pelletizing the obtained composition, it is supplied to a 50 mmφ extruder with L / D = 24, and the inner diameter is 4.5 mm and the outer diameter is 6.5 at a temperature of 310 ° C. cylinder and 350 ° C. head. A 5 mm tube was extruded.

In Comparative Example 3, the compounded materials shown in Table 1 were put into a preforming mold and pressed to produce a preformed body.
It is fed to a 0 mm extruder, and has an inner diameter of 4.5 mm and an outer diameter of 6.
A 5 mm tube was extruded. Next, the obtained tube was introduced into a heating furnace maintained at 500 ° C. to perform firing.

Here, a total of seven kinds of tube samples (Examples 1 to 4 and Comparative Examples 1 to 3) obtained as described above were used as mechanical strength (tensile strength and elongation,
Abrasion resistance), heat resistance and appearance. The results are shown in Table 1.

The evaluation method is as follows. Mechanical strength Tensile strength and elongation were measured in accordance with JIS C 3005 (1986). Tetirafluoroethylene-hexafluoropropylene copolymer (FEP) with heat resistance of 200 ° C
The tensile strength is 20 MPa or more and the elongation is 20
0% or more was regarded as a pass line. Wear resistance is JASO
The minimum abrasion resistance was measured according to the blade reciprocation method (load 1060 g) of the abrasion resistance test of D608-92. The larger the numerical value (the number of times), the stronger the resistance of edges and the like, which is preferable.

Heat resistance Each sample was left in a thermostat kept at 232 ° C. and then taken out, and the residual tensile strength and elongation were measured. Then, the number of days when the residual tensile strength was less than 50% or the elongation was less than 50% was measured. The longer the number (days),
Excellent heat resistance is preferable.

Appearance The appearance of each sample was visually checked, and a sample having irregularities on the surface was indicated as "poor".

[0022]

[Table 1]

As is clear from Table 1, the tubes of Examples 1 to 4 in which a predetermined amount of low-molecular-weight polytetrafluoroethylene particles were mixed with ETFE, the low-molecular-weight polytetrafluoroethylene particles were completely mixed. Both the heat resistance and the mechanical strength (abrasion resistance) are remarkably improved as compared with the tube of Comparative Example 1 having no heat resistance. Above all, in Example 4 in which vinylidene fluoride-based fluororubber was further mixed, the mechanical strength also improved the tensile strength in addition to the wear resistance. The effect of improving the abrasion resistance is such an effect that it cannot be considered at all when an inorganic filler or the like usually used for the purpose of improving the heat resistance is added.

Comparative Example 2 shows an example in which low molecular weight polytetrafluoroethylene particles are mixed, but the amount exceeds the upper limit (10 parts by weight) of the preferred range of the present invention. Poor strength (elongation) and appearance.

Comparative Example 3 shows an example of a tube conventionally used as an outer casing of a control cable for an automobile. All of the examples according to the present embodiment are equal to or more than Comparative Example 3. It shows the characteristic of. Considering that the tube of Comparative Example 3 cannot be elongated for batch production, the tube according to the present example can be elongated by a thermoplastic extrusion method.
It can be said that a tube showing the same or better characteristics at a lower cost than the tube of Comparative Example 3 can be obtained.

[0026]

As described in detail above, the tube of the present invention has both excellent mechanical strength and excellent heat resistance exceeding 180 ° C., and can be manufactured at low cost because it can be manufactured by a thermoplastic extrusion method. . Therefore, for example, it is suitable as a protective material for electric wiring used in an engine room of an automobile or an outer casing of a control cable.

Claims (3)

[Claims] An extruded composition comprising 100 parts by weight of a copolymer mainly composed of ethylene and tetrafluoroethylene and 2 to 10 parts by weight of tetrafluoroethylene micropowder mixed. Features tube. 2. The tube according to claim 1, wherein low molecular weight polytetrafluoroethylene particles having an average particle diameter of 50 μm or less are used as the tetrafluoroethylene micropowder. 3. A control cable for an automobile, wherein the tube according to claim 1 or 2 is used as an outer casing.