JPH087663A - Flat cable - Google Patents

Abstract

(57) [Summary] [Structure] A plurality of rectangular conductors (1) are sandwiched by two laminated films (5) consisting of an insulating plastic layer (3) and a polyvinyl chloride layer (2), In the flat cable, wherein the ratio of the total thickness t ₁ of the vinyl chloride layer (2) to the thickness t ₂ of the rectangular conductor (1) is t ₂ / t ₁ ≧ 1.0, the polyvinyl chloride A flat cable in which the weight average polymerization degree of polyvinyl chloride constituting the layer (2) is 850 or less. [Effect] It is possible to provide a flat cable having good sliding and bending characteristics even if the thickness is thin.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to various communication devices, copying machines,
The present invention relates to a flat cable used for wiring home appliances, computers, word processors, automobiles and the like.

[0002]

2. Description of the Related Art As shown in FIG. 3, a general flat cable has a plurality of flat angles formed by a laminated film 5 in which an insulating plastic layer 3 and a thermoplastic layer 2 are laminated via an adhesive layer 4. It has a structure in which the conductor 1 is sandwiched.

In order to manufacture a flat cable, first,
For example, a laminated film 5 is obtained by laminating an insulating plastic layer 3 made of polyethylene terephthalate and a thermoplastic layer 2 made of polyvinyl chloride via an adhesive layer 4. Then, as shown in FIG. 2, the laminated film 5 is arranged on the upper and lower surfaces of the plurality of rectangular conductors 1 arranged at a predetermined interval so that the thermoplastic layers 2 of the flat conductors 1 face each other. Then, as shown in FIG. 5, these are heated and pressure bonded by a heating roll 9 to form a flat cable. Here, when the insulating plastic layer 3 and the thermoplastic layer 2 have good adhesiveness, a laminated film 5 without an adhesive layer 4 between these layers may be used.

The flat cable is thin in thickness and rich in flexibility, and therefore, for example, a steering roll connector (SR) which is a component of an automobile airbag system.
Used as an electric wire for wiring in C).

[0005]

By the way, for use in the above-mentioned applications, the flat cable has durability (sliding bending property) that does not break even if repeatedly subjected to sliding bending.
Is required. On the other hand, in recent years, in order to further reduce the space of the wiring portion, the flat cable is required to be thin. To make the flat cable thin, it is sufficient to make the laminated film 5 thin, but there is a problem in that the sliding bending characteristic is significantly impaired and the life is extremely shortened only by making it thin.

The present inventor has obtained the following knowledge from various test results of various flat cables in order to develop a thin flat cable having good sliding and bending characteristics. That is, in the case where the thermoplastic layer 2 is the polyvinyl chloride layer 2 made of polyvinyl chloride, the voids 6 (generated between the rectangular conductors 1 are generated rather than the rigidity reduction due to the thinning of the polyvinyl chloride layer 2 which is conventionally known). (See FIG. 4) affects the deterioration of the sliding and bending characteristics. When the polyvinyl chloride layer 2 is thinned, the voids 6 are generated especially when the total thickness t ₁ of the polyvinyl chloride layer 2 and the thickness t _{2 of the} rectangular conductor 1 are increased.
When and satisfy t ₂ ≧ t ₁ , it becomes remarkable. It is considered that this is because it is difficult for the polyvinyl chloride layer 2 to absorb the difference between the portion where the rectangular conductor 1 is present and the portion where it is not present.

The present invention has been made as a result of extensive studies in view of the above problems of the prior art. An object of the present invention is to provide a flat cable having good sliding and bending characteristics even when the thickness of the flat cable is reduced. And

[0008]

As a result of further diligent research, the present inventor has found that the above object can be achieved by using polyvinyl chloride having a weight average degree of polymerization of 850 or less.

The reason why the weight average degree of polymerization of polyvinyl chloride constituting the polyvinyl chloride layer 2 in the flat cable of the present invention is limited to 850 or less is as follows.
Generally, polyvinyl chloride has a drawback that it has poor flowability and is hard to be softened when it is heated and pressed by the heating roll 9. This defect is caused by the thickness t of the polyvinyl chloride layer 2.
_When the thickness of the polyvinyl chloride layer 2 is increased so that the ratio of 1 to the thickness t ₂ of the rectangular conductor 1 is t ₂ / t ₁ <1.0 as shown in FIG. It doesn't matter. However, as shown the polyvinyl chloride layer 2 thinly Figure 4 t ₂ / t
_{When 1} ≧ 1.0, when the weight average polymerization degree of polyvinyl chloride exceeds 850, polyvinyl chloride cannot flow into the space between the rectangular conductors 1 and voids 6 are formed between the rectangular conductors 1. Because it will be.

In the flat cable of the present invention,
The weight average degree of polymerization of polyvinyl chloride constituting the polyvinyl chloride layer 2 is preferably 600 or more, more preferably 700 or more. This is because if the weight average polymerization degree of polyvinyl chloride is not less than the above value, it becomes easy to form a film of polyvinyl chloride.

In the flat cable of the present invention, polyvinyl chloride may be added with additives such as a plasticizer, a flame retardant, an antiaging agent and a lubricant, if necessary.

In the flat cable of the present invention, the material of the insulating plastic layer 3 is polyethylene terephthalate (PET) or polyethylene naphthalate (P).
EN) and the like, polyesters, polyethylene, polypropylene, vinyl chloride resins, polyamides, vinylidene chloride copolymers and the like which are commonly used can be used.

Further, as the flat conductor 1 of the flat cable, tough pitch copper, tin-plated copper, nickel-plated copper or the like is preferably used.

[0014]

In the flat cable of the present invention, the polyvinyl chloride constituting the polyvinyl chloride layer 2 has a weight average degree of polymerization of 8 or less.
Since it is 50 or less, the total thickness t of the polyvinyl chloride layer 2 is t.
₁ and the ratio of the thickness t ₂ of the rectangular conductor 1 is t ₂ / t ₁ ≧
Even when the polyvinyl chloride layer 2 is thinned to 1.0, it is possible to prevent the voids 6 from being generated between the rectangular conductors 1.

[0015]

【Example】

(Embodiment 1) FIG. 1 is a cross-sectional view of the flat cable of this embodiment in a direction orthogonal to the longitudinal direction. This flat cable has a structure in which four flat rectangular conductors 1 positioned substantially parallel to each other at an interval of 1 mm are sandwiched between laminated films 5.
The laminated film 5 comprises an insulating plastic layer 3 made of a polyester film having a thickness of 50 μm and a thickness of 3 μm.
Adhesive layer 4 made of thermosetting polyester adhesive
And a polyvinyl chloride layer 2 made of polyvinyl chloride having a thickness of 60 μm and a weight average degree of polymerization of 700, which are laminated by a usual method. In addition, the rectangular conductor 1 has a width of 1.5.
It is a copper conductor having a thickness of 150 mm and a thickness of 150 μm.

An example of a method for manufacturing this flat cable will be described with reference to FIGS. 2 and 5. As shown in FIG. 2, two laminated films 5 are arranged so that the polyvinyl chloride layers 2 face each other, and the four rectangular conductors 1 positioned substantially parallel to each other at 1 mm intervals are connected to the polyvinyl chloride layer. A laminated body composed of the rectangular conductor 1 and the laminated film 5 was sandwiched between the two. As shown in FIG. 5, the laminate thus obtained was passed between heating rolls 9 heated to 170 ° C. and thermocompression bonded to produce a flat cable of this example.

The sliding bending repetition test of the flat cable of this example and the cross-sectional area of the void 6 between the rectangular conductors 1 were measured as follows. The respective results are shown in Table 1.

(Sliding and Bending Repeat Test) As shown in FIG. 6, a center portion of a flat cable having a length of 70 cm was curved into a U shape having a radius of curvature of 15 mm, and one end A was fixed.
Then, the other end B is 20 mm at a speed of 100 reciprocations per minute.
Move up and down. In this way, the number of reciprocations until at least one of the flat conductors 1 of the flat cable was broken was measured.

(Measurement of cross-sectional area of void between flat conductors) A photograph of a cross section of the obtained flat cable orthogonal to the longitudinal direction was taken, and the cross-sectional area of the void 6 existing between the flat conductors 1 was measured.

Example 2 A flat cable similar to that of Example 1 was produced except that the weight average polymerization degree of polyvinyl chloride was 800. Repeated sliding and bending tests of the obtained flat cable and the cross-sectional area of the voids 6 between the rectangular conductors 1 were measured in the same manner as in Example 1. The results are shown in Table 1.

Example 3 A flat cable was produced in the same manner as in Examples 1 and 2 except that the weight average polymerization degree of polyvinyl chloride was 600. Repeated sliding and bending tests of the obtained flat cable and the cross-sectional area of the void 6 between the rectangular conductors 1 were measured in the same manner as in Examples 1 and 2. The results are shown in Table 1.

(Example 4) Flat cables similar to those in Examples 1 to 3 were produced except that the weight average polymerization degree of polyvinyl chloride was 850. Repeated sliding and bending tests of the obtained flat cable and the cross-sectional area of the void 6 between the rectangular conductors 1 were measured in the same manner as in Examples 1 to 3. The respective results are shown in Table 1.

(Examples 5 to 8) The flat rectangular conductor 1 has a thickness of 20.
Four types of flat cables similar to those in Examples 1 to 4 were manufactured except that the thickness was 0 μm. Repeated sliding and bending tests of the obtained flat cable and the cross-sectional area of voids between the rectangular conductors 1 were measured in the same manner as in Examples 1 to 4. The results are shown in Table 1.

(Comparative Example 1) A flat cable was produced in the same manner as in Example except that the weight average polymerization degree of polyvinyl chloride was 1,000. Repeated sliding and bending tests of the obtained flat cable and the size of the void 6 between the rectangular conductors 1 were measured in the same manner as in the example. The results are shown in Table 1.

(Comparative Example 2) A flat cable similar to that of the example was manufactured except that the weight average polymerization degree of polyvinyl chloride was 860. Repeated sliding and bending tests of the obtained flat cable and the size of the void 6 between the rectangular conductors 1 were measured in the same manner as in the example. The results are shown in Table 1.

Comparative Examples 3 to 4 The rectangular conductor 1 has a thickness of 20.
Two kinds of flat cables similar to Comparative Examples 1 and 2 except that the thickness was 0 μm were produced. Repeated sliding and bending tests of the obtained flat cable and cross-sectional areas of voids between the rectangular conductors 1 were measured in the same manner as in Comparative Examples 1 and 2. The results are shown in Table 1.

[0027]

[Table 1]

(Results) From the results shown in Table 1, in the flat cables of Examples 1 to 8, the rectangular conductor 1 was not broken even after repeating sliding and bending 10 million times or more. On the other hand, the flat cables of Comparative Examples 1 to 4 are far smaller than those of the Examples in the number of repeated sliding of 461,000 times, 157,000 times, 237,000 times and 92,000,000 times. The rectangular conductor 1 was broken by repeated bending. When a cross section of the rectangular conductor 1 perpendicular to the longitudinal direction was observed, as shown in FIG.
In, the polyvinyl chloride layer 2 completely filled the space between the rectangular conductors 1, and no void was observed. On the other hand, as shown in FIG. 4, in Comparative Examples 1 to 4, the cross-sectional areas are 0.035 respectively.
mm ^2, 0.015mm ^2, 0.070mm ² and 0.035 mm ² approximately of the gap 6 was observed.

[0029]

As described above, in the flat cable of the present invention, the weight average polymerization degree of the polyvinyl chloride constituting the polyvinyl chloride layer 2 is set to 850 or less, so that the thickness t ₁ of the polyvinyl chloride layer 2 is And the thickness t _{2 of the} rectangular conductor 1
Even when the polyvinyl chloride layer 2 is thinned so that the ratio of t ₂ / t ₁ ≧ 1.0, it is possible to prevent the formation of the voids 6 between the rectangular conductors 1. Therefore, according to the present invention, it is possible to provide a flat cable having good sliding and bending characteristics even if it is thin.

[Brief description of drawings]

FIG. 1 is a sectional view showing a flat cable of an embodiment.

FIG. 2 is a cross-sectional view showing one step in manufacturing a flat cable.

FIG. 3 is a cross-sectional view showing a conventional flat cable.

FIG. 4 is a cross-sectional view showing a flat cable of a comparative example.

FIG. 5 is a process drawing for explaining a method for manufacturing a flat cable.

FIG. 6 is a schematic diagram for explaining a method of a repeated sliding and bending test of a flat cable.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Flat conductor 2 Thermoplastic plastic layer, polyvinyl chloride layer 3 Insulating plastic layer 4 Adhesive layer 5 Laminated film 6 Gap 7 Conductor bobbin 8 Film roll 9 Heating roll 10 Winding roll

Claims (1)

[Claims] 1. A plurality of rectangular conductors (1) are sandwiched by two laminated films (5) consisting of an insulating plastic layer (3) and a polyvinyl chloride layer (2), and the polyvinyl chloride layer ( In the flat cable in which the ratio of the total thickness t ₁ of 2) to the thickness t ₂ of the rectangular conductor (1) is t ₂ / t ₁ ≧ 1.0, the polyvinyl chloride layer (2) The weight average polymerization degree of polyvinyl chloride constituting
A flat cable characterized by being 50 or less.