Flexible cable

Abstract

A flexible cable includes an outer sheath at an outermost portion. The outer sheath includes an inner layer made of an elastomer containing polypropylene resin, and an outer layer surrounding the inner layer and made of polypropylene resin.

Claims

1. A flexible cable comprising an outer sheath at an outermost portion, wherein the outer sheath includes: an inner layer made of an elastomer containing polypropylene resin, and an outer layer surrounding the inner layer and made of polypropylene resin, wherein the outer layer has a large number of cracks in a surface of the outer layer.

2. The flexible cable according to claim 1, wherein the outer layer has a layer thickness of more than 0 m and less than or equal to 100 m.

3. The flexible cable according to claim 2, wherein the outer layer is fusion-bonded with the inner layer.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The foregoing and other exemplary purposes, aspects and advantages will be better understood from the following detailed description of the invention with reference to the drawings, in which:

(2) FIGURE is a cross-sectional view of a flexible cable according to an embodiment of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT

(3) Referring now to the drawings, and more particularly to FIGURE, there is shown exemplary embodiments of the methods and structures according to the present invention.

(4) An embodiment of the present invention is described below in accordance with the appended drawing.

(5) As illustrated in FIGURE, a flexible cable 100 according to an embodiment of the present invention includes, for example, a strand 102 obtained by stranding multiple core wires 101 up, a first tape 103 wound around the strand 102, a braid shield 104 disposed around the first tape 103, a second tape 105 wound around the braid shield 104, and an outer sheath 106 disposed around the second tape 105.

(6) The flexible cable 100 according to the embodiment of the present invention includes an outer sheath 106 at least at the outermost layer. The outer sheath 106 has a double layer structure including an inner layer 107, made of an elastomer containing polypropylene resin, and an outer layer 108, disposed around the inner layer 107 and made of polypropylene resin.

(7) Examples of an elastomer containing polypropylene resin include Rabalon (registered trade mark), which is a compound of styrene-based rubber and polypropylene resin. Rabalon is a material having flexibility as high as the flexibility of a material such as polyurethane resin, silicone rubber, a compound of styrene-based rubber and polystyrene resin, or plasticized polyvinyl chloride. Moreover, Rabalon is a material having thermal resistance as high as the thermal resistance of silicone rubber, a compound of styrene-based rubber and polypropylene resin, or a compound of styrene-based rubber and polystyrene resin. Thus, using the inner layer 107 made of Rabalon can reliably provide the outer sheath 106 with flexibility and thermal resistance.

(8) Rabalon, however, is a material having slidability as low as the slidability of a material such as polyurethane resin, silicone rubber, a compound of styrene-based rubber and polypropylene resin, or a compound of styrene-based rubber and polystyrene resin. Thus, when only the inner layer 107 made of Rabalon is used as an outer sheath, a human operator feels unsmoothness while manually handling the flexible cable because the outer sheath has a sticky surface. Thus, in the flexible cable 100 according to the embodiment of the present invention, a thin outer layer 108 made of polypropylene resin, which is a material having high thermal resistance and high slidability, is disposed around the inner layer 107 made of Rabalon to coat the inner layer 107.

(9) Desirably, the outer layer 108 has a large number of cracks 109 in its surface. If the outer layer 108 has a large number of cracks 109 in its surface, the outer sheath 106 can have a smaller friction coefficient since the area over which the outer sheath 106 is brought into contact with other object is reduced. Thus, a human operator is less likely to feel unsmoothness while manually handling the flexible cable 100.

(10) Desirably, the outer layer 108 has a layer thickness of more than 0 m and less than or equal to 100 m, more desirably, more than 0 m and less than or equal to 50 m. The reason why the layer thickness of the outer layer 108 of more than 0 m and less than or equal to 100 m is desirable is described as follows. If the layer thickness of the outer layer 108 exceeds 100 m, the outer sheath 106 is more likely to have a protuberance (crease) as a result of the flexible cable 100 being bent. Thus, the outer sheath 106 is more likely to be easily foldable at a particular portion and may be broken at the portion. The reason why the layer thickness of the outer layer 108 of more than 0 m and less than or equal to 50 m is more desirable is because, a large number of cracks 109 are more likely to naturally occur in the surface of the outer layer 108 as the outer layer 108 has a smaller layer thickness.

(11) Desirably, the outer layer 108 is fusion-bonded with the inner layer 107. By concurrently performing tube extrusion of the outer layer 108 and the inner layer 107 to surround the second tape 105, the outer layer 108 can be fusion-bonded with the inner layer 107 using the extrusion heat. When the outer layer 108 is fusion-bonded with the inner layer 107, the outer layer 108 is brought into close contact with the inner layer 107. Thus, the outer layer 108 is not separated from the inner layer 107 even when a large number of cracks 109 occur in the surface of the outer layer 108. Thus, the outer layer 108 can reliably fulfill its function.

(12) As described above, the flexible cable 100 according to an embodiment of the present invention includes the outer sheath 106 having an unsticky surface while having high flexibility and high thermal resistance as a whole. Thus, a human operator is less likely to feel unsmoothness while manually handling the flexible cable 100 and the outer sheath 106 is less likely to be damaged while being sterilized using an autoclave.

(13) Although the invention has been described with respect to specific exemplary embodiments for complete and clear disclosure, the appended claims are not to be thus limited but are to be construed as embodying all modifications and alternative constructions that may occur to one skilled in the art which fairly fall within the basic teaching herein set forth.

(14) Further, it is noted that Applicant's intent is to encompass equivalents of all claim elements, even if amended later during prosecution.