JP6905415B2 - Flat cable - Google Patents

Description

The present invention relates to a flat cable.

As a conventional flat cable, for example, Patent Document 1 discloses a vinyl insulated vinyl sheathed cable flat (VVF).

Japanese Unexamined Patent Publication No. 2011-228161

For a flat cable such as the above-mentioned VVF in which a plurality of insulated wires are arranged side by side and covered with a sheath at once, it is desired that the sheath removal workability is excellent and the sheath is not easily scratched. There is.

As described in Patent Document 1, a sheath made of a foamed resin is superior in stripperability to a sheath made of a resin containing no air bubbles. Further, if the sheath is made of foamed resin, it is easy to shred even if there is a connected portion without being cut by a cutter or the like as described later. Therefore, it can be said that the sheath made of foamed resin is easy to remove. However, the sheath made of foamed resin is liable to be scratched on the surface of the sheath and its vicinity when it receives an impact from the outside or rubs against the outside such as the ground during transportation or laying. Deep scratches may occur depending on the size of the bubbles. In addition, by pulling the flat cable, scratches may develop due to air bubbles and the sheath may be damaged.

Therefore, one of the purposes of the present invention is to provide a flat cable which is excellent in workability for removing the sheath and in which the sheath is not easily scratched.

The flat cable of the present disclosure is
A flat cable having a plurality of insulated wires having an insulating layer on the outer circumference of a conductor and a sheath portion that collectively covers the outer circumferences of the plurality of insulated wires.
The sheath portion is
The plurality of insulated wires are covered side by side, and a foamed region made of foamed resin and a foamed region are formed.
It covers the outer periphery of the foamed region and includes a solid region made of a non-foamed resin or a non-foamed resin.

The above-mentioned flat cable has excellent workability for removing the sheath, and the sheath is not easily scratched.

It is schematic cross-sectional view which shows an example of the flat cable of Embodiment 1. FIG. It is the schematic sectional drawing which shows an example of the flat cable of Embodiment 2. It is the schematic sectional drawing which shows an example of the flat cable of Embodiment 3.

[Explanation of Embodiments of the Present Invention]
First, embodiments of the present invention will be listed and described.
(1) The flat cable according to one aspect of the present invention is
A flat cable having a plurality of insulated wires having an insulating layer on the outer circumference of a conductor and a sheath portion that collectively covers the outer circumferences of the plurality of insulated wires.
The sheath portion is
The plurality of insulated wires are covered side by side, and a foamed region made of foamed resin and a foamed region are formed.
It covers the outer periphery of the foamed region and includes a solid region made of a non-foamed resin or a non-foamed resin.

Since the above-mentioned flat cable includes a foamed region in the sheath portion, it is excellent in workability for removing the sheath portion. Here, when cutting into the sheath portion with a cutter or the like, the cut wire is provided so as to sandwich the insulated wire from above and below within the range parallel to the parallel direction of the insulated wire and not in contact with the insulated wire in the sheath portion. By pulling one end side of the sheath portion, the operator tears off the uncut portion that is connected without being cut by a cutter or the like in the sheath portion, and removes one end side of the sheath portion. Since the above flat cable contains a foamed region in the sheath portion, it is easy to cut with a cutter or the like when removing the sheath portion, and even if there is a non-cutting portion that is not directly cut by the cutter or the like, it is not cut. Since air bubbles are included in the portion, the sheath portion can be easily torn off. Moreover, since the above-mentioned flat cable has a solid region having excellent rigidity as compared with the foamed region, the solid region arranged on the surface side of the sheath portion even if it receives an external impact or rubbing with the outside. It is hard to be scratched by itself. Further, since the solid region does not substantially contain air bubbles, even if the solid region is pulled in a scratched state, the scratches are unlikely to propagate to the foamed region inside, and the foamed region is also unlikely to be scratched. Therefore, the above-mentioned flat cable can easily prevent the sheath portion from being damaged.

(2) As an example of the above flat cable,
The solid region may include a thick portion locally thick in the circumferential direction of the sheath portion.

In the above embodiment, since the solid region is locally thick, it is easier to cut the sheath portion as compared with the case where the entire solid region is uniformly thick, and the sheath portion is easily torn, and the removal workability of the sheath portion is excellent. Further, in the above-described form, the thick portion can be a portion that is less likely to be scratched, and the sheath portion is less likely to be scratched.

(3) As an example of the flat cable of (2) above,
Examples of the solid region include a form in which the thick portion is provided at a position corresponding to the adjacent insulated electric wires in the foamed region.

In the above form, the sheath portion is excellent in removal workability, and as will be described later, a thick portion is provided at a position where it easily rubs against the outside, so that the sheath portion is not easily scratched by rubbing with the outside.

(4) As an example of the above flat cable,
In the solid region, the thickness of the lateral portions located on both sides of the plurality of insulated wires in parallel is larger than the thickness of the intermediate portion existing at a position corresponding to the adjacent insulated wires in the foamed region. A thin form can be mentioned.

Most of the above-mentioned lateral parts are included in non-cutting parts that are not cut by the above-mentioned cutter or the like. In the above form, since the thickness of the side portion is thin, although it is a non-cut portion, it is easy to shred and the sheath portion is excellent in removal workability. Further, typically, the outer peripheral surface of the above-mentioned intermediate portion is formed by a flat surface, and the outer peripheral surface of the above-mentioned lateral portion is formed by a semicircular curved surface. The curved side portion is less likely to rub against the outside than the flat intermediate portion, and is less likely to be scratched even if the thickness is thin. Since the middle part is relatively thick, it is hard to be scratched by rubbing with the outside. Therefore, the above-mentioned form is excellent in the workability of removing the sheath portion, and is less likely to be scratched over the entire solid region.

(5) As an example of the above flat cable,
The average thickness of the solid region may be 5% or more and 20% or less of the average thickness of the foamed region. The method for measuring the thickness will be described later.

In the above form, when the average thickness of the solid region satisfies the above-mentioned specific range, it is hard to be scratched, it is easy to cut, and the uncut portion is also easy to shred, so that the workability of removing the sheath portion is also excellent.

(6) As an example of the above flat cable,
Examples thereof include a form in which the solid region and the outer region located near the surface of the flat cable in the foamed region are different in color.

In the above form, even if the sheath portion is scratched, it can be easily grasped whether or not the scratch extends to the foamed region. Therefore, the above-mentioned form is excellent in the workability of removing the sheath portion, and even if it is scratched, it is easy to grasp the degree of the scratch on the surface of the sheath portion and its vicinity.

(7) As an example of the flat cable of (6) above,
Examples of the solid region include a form containing a pigment.

In the above form, it is easy to visually distinguish the solid region and the foamed region by coloring with a pigment, and it is easy to grasp the degree of the above-mentioned scratches more easily and more accurately.

(8) As an example of the above flat cable,
The outer region located near the surface of the flat cable in the foamed region may include bubbles smaller than the bubbles contained in the inner region located near the insulated wire in the foamed region.
The "bubble size" here means that the above-mentioned cross section is observed with a scanning electron microscope (SEM), the area of each bubble existing in the measurement region taken from this observation image is obtained, and each bubble is used. Let the diameter of the circle corresponding to the area of each bubble be the size of each bubble. The details of the measurement method will be described later.

In the above form, since the bubbles contained in the outer region close to the cable surface in the foamed region are small, even if the solid region is scratched when it receives an external impact or rubs against the outside, the scratches are present. Is hard to spread inside the foamed area, and the foamed area is hard to be scratched. Further, in the above form, since the bubbles contained in the inner region close to the insulated wire in the foamed region are large, it is easy to cut. Therefore, the above-mentioned form is excellent in the workability of removing the sheath portion from the viewpoint of ease of cutting, and the sheath portion is less likely to be scratched.

(9) As an example of the flat cable of (8) above,
The size of the bubbles contained in the outer region may be 50 μm or less.

In the above form, all the bubbles contained in the outer region are 50 μm or less, and even if there are scratches in the solid region, the scratches are less likely to grow inside the foamed region, and the foamed region is less likely to be scratched. Therefore, in the above form, the workability of removing the sheath portion is excellent, and the sheath portion is less likely to be scratched.

(10) As an example of the flat cable of (8) or (9) above,
Examples thereof include a form in which the abundance ratio of bubbles per unit area in the outer region is 100 cells / mm ² or more and 600 cells / mm ^{2 or less.}

In the above form, the abundance ratio of bubbles in the outer region satisfies the above specific range. Therefore, the above-mentioned form is excellent in workability for removing the sheath portion because it is easy to cut and has some flexibility and is easy for an operator to handle. Moreover, in the above-mentioned form, even if there is a scratch in the solid region, the scratch is less likely to grow inside the foamed region, and the sheath portion is less likely to be scratched.

(11) As an example of any one of the above (8) to (10) flat cables,
Examples thereof include a form in which the size of bubbles contained in the inner region is 10 μm or more and 100 μm or less.

Further, in the above form, since the size of the bubbles contained in the inner region satisfies the above-mentioned specific range, it is easy to cut, and it has some flexibility and is easy for the operator to handle. Excellent removal workability. Further, in the above embodiment, since the size of the bubbles contained in the inner region directly covering the insulated wire satisfies the above-mentioned specific range, for example, the operator draws the above-mentioned flat cable before removing the sheath portion. However, it is easy to properly hold the insulated wire by preventing the insulated wire from twisting in the sheath portion and the adjacent insulated wires from rubbing against each other.

(12) As an example of the flat cable according to (8) or (11) above,
Examples thereof include a form in which the abundance ratio of bubbles per unit area in the inner region is 30 cells / mm ² or more and 300 cells / mm ^{2 or less.}

Further, in the above form, since the abundance ratio of air bubbles in the inner region satisfies the above-mentioned specific range, it is easy to cut, and it has some flexibility and is easy for the operator to handle. Excellent in sex. Further, in the above-described embodiment, since the abundance ratio of air bubbles contained in the inner region directly covering the insulated wire satisfies the above-mentioned specific range, it is easy to prevent the above-mentioned twisting and rubbing and appropriately hold the insulated wire. ..

(13) As an example of the above flat cable,
Further, a ground wire connected to the sheath portion is provided.
Examples of the ground wire include a grounding conductor and a coating layer covering the grounding conductor.

The above form can be used as a flat cable with a ground that is excellent in workability for removing the sheath portion and is less likely to be scratched on the sheath portion.

(14) As an example of the flat cable of (13) above,
The ground wire may be connected to one end side of the plurality of insulated wires in the parallel direction.

Further, in the above form, the ground wire can be easily separated from the sheath portion.

(15) As an example of the flat cable according to (13) or (14) above,
The coating layer is provided directly above the grounding conductor, and covers at least a part of the outer periphery of the inner coating layer and the inner coating layer made of foamed resin, and the outer coating layer made of non-foamed resin or non-foamed resin. A form including the above can be mentioned.

Further, the above-mentioned form is excellent in flexibility because it includes an inner coating layer made of a foamed resin, and it is easy to separate the ground wire from the sheath portion. Further, since the outer coating layer made of non-foamed resin or non-foamed resin has higher rigidity than the inner coating layer, the surface of the ground wire and its vicinity are scratched by an external impact or rubbing with the outside. hard. In addition, since the above-mentioned form includes a coating layer having a two-layer structure, it is also excellent in insulating properties.

(16) As an example of the flat cable of (15) above,
The inner coating layer and the outer coating layer may have different colors.

Further, in the above form, even if the outer coating layer is scratched, it is possible to easily grasp whether or not the scratch has reached the inner coating layer, and it is easy to grasp the degree of the scratch on the coating layer.

(17) As an example of the flat cable according to (15) or (16) above,
Examples of the inner coating layer include a form in which the inner coating layer is continuously formed in the foamed region.

Further, the above-mentioned form is integrally molded from the foamed region of the sheath portion to the inner coating layer of the ground wire by a continuous foamed resin. Therefore, in the above embodiment, the ground wire is difficult to come off from the sheath portion before the sheath portion and the ground wire are separated, and when the ground wire is separated from the sheath portion, the connecting portion between the sheath portion and the ground wire is made of foamed resin. Therefore, it is easy to separate.

(18) As an example of any one of the above (15) to (17) flat cables,
Examples of the outer coating layer include a form in which the outer coating layer is continuously formed in the solid region.

Further, in the above form, not only the sheath portion but also the entire cable including the ground wire is made of a highly rigid material such as non-foamed resin or non-foamed resin on the surface and its vicinity, so that the entire cable is less likely to be scratched. ..

(19) As an example of the above flat cable,
At least a part of the conductor may be made of copper or a copper alloy.

Further, in the above form, since the conductor of the insulated wire has excellent conductivity, it can be suitably used for electrical wiring.

(20) As an example of the flat cable of (19) above,
Examples of the conductor include a conductor wire made of aluminum or an aluminum alloy and a composite wire covering at least a part of the outer periphery of the conductor wire and having a copper coating portion made of copper or a copper alloy.

Further, the above-mentioned form can be reduced in weight.

(21) As an example of the above flat cable,
At least one of the foamed resin and the non-foamed resin or the non-foamed resin may contain polyvinyl chloride.

Further, in the above form, since at least a part of the sheath portion is made of a material having excellent durability and fatigue resistance, the sheath portion is less likely to be scratched.

(22) As an example of the above flat cable,
At least one of the foamed resin and the non-foamed resin or the non-foamed resin may contain polyethylene.

Further, the above-mentioned form can reduce the environmental load caused by the sheath portion.

(23) As an example of the flat cable of (22) above,
Examples thereof include a form containing a flame retardant in addition to the polyethylene.

Further, the above form is also excellent in flame retardancy.

[Details of Embodiments of the present invention]
Hereinafter, the flat cable according to the embodiment of the present invention will be specifically described with reference to the drawings. The same reference numerals in the figures indicate the same names. 1 to 3 are cross-sectional views of the flat cable 1 cut along a plane orthogonal to the axial direction (longitudinal direction) thereof. The flat cable 1 is schematically shown in FIGS. 1 to 3, and the size (thickness, diameter, etc.) of each element may differ from the actual dimensions.

[Embodiment]
(overview)
As shown in FIG. 1, the flat cable 1 of the embodiment includes a plurality of insulated wires 2 having an insulating layer 25 on the outer periphery of the conductor 20, and a sheath portion 3 that collectively covers the outer periphery of the plurality of insulated wires 2. To be equipped. In FIG. 1 and the like, a plurality of (two in FIG. 1 and the like) insulated wires 2 are in contact with each other and arranged side by side, and the outer periphery thereof is collectively covered with a sheath portion 3, and the cross section has a flat shape such as a race track shape. An example is a flat cable 1 formed in. The flat cable 1 typically corresponds to a cable called a 600V flat vinyl insulated vinyl sheath cable, a 600V flat polyethylene insulated polyethylene sheath cable, or the like.

The flat cable 1 of the embodiment has a multi-layer structure in which the sheath portion 3 includes a foamed region 30 made of a foamed resin and a solid region 33 which covers the outer periphery of the foamed region 30 and is made of a non-foamed resin or a non-foamed resin. In addition to the flat cable 1A of the first embodiment shown in FIG. 1, as in the flat cable 1B of the second embodiment shown in FIG. 2, a form including a ground wire 5 connected to the sheath portion 3 and the like can be mentioned. ..

Hereinafter, each configuration of the flat cable 1 will be described in detail.
(Insulated wire)
Each insulated wire 2 includes a conductor 20 mainly made of a wire made of a conductive material and an insulating layer 25 made of an electrically insulating material. Examples of the conductive material include copper (pure copper, the same shall apply hereinafter), copper alloy, aluminum (pure aluminum, the same shall apply hereinafter), and an aluminum alloy. As the conductor 20, a single wire or a stranded wire made of the above conductive material can be used. In FIGS. 1 and 2, an insulated wire 2A including a single conductor 20 is illustrated. Examples of the electrically insulating material include resins having insulation, flexibility, heat resistance, and water resistance such as polyvinyl chloride (PVC) and polyethylene (PE). The outer shape of the conductor 20 and the outer shape of the insulated wire 2 are typically circular.

It can be mentioned that at least a part of the conductor 20 is made of copper or a copper alloy. Copper and copper alloys generally have high conductivity, and the insulated wire 2 provided with a conductor 20 containing copper or a copper alloy has excellent conductivity and can be suitably used for electrical wiring. For example, the conductor 20 made of copper is a single wire or a stranded wire of an electric annealed copper wire (an example of a copper wire) conforming to or equivalent to JIS C 3102 (1984), and has a predetermined conductor cross-sectional area and wire diameter. You can use what you have.

In the insulated wire 2C provided in the flat cable 1C of the third embodiment shown in FIG. 3, the conductor 20 covers the conductor wire 21 made of aluminum or an aluminum alloy and the outer periphery of the conductor wire 21 and is made of copper or a copper alloy. Includes a composite wire with a copper coating 22. Aluminum and its alloys have lower conductivity than copper and copper alloys, but are lighter. Therefore, the insulated wire 2C including the composite wire in the conductor 20 can be suitably used as a lightweight electric wiring while ensuring good conductivity by the copper coating portion 22. When the conductor wire 21 is made of aluminum, it is excellent in conductivity and flexibility such as bending, and when it is made of an aluminum alloy, it is excellent in strength and the like. As the aluminum alloy, those having various compositions can be used. For example, an aluminum alloy containing Fe in a specific range described in JP-A-2010-067591 can be used. When the copper coating portion 22 is made of copper, it is excellent in conductivity and flexibility such as bending, and when it is made of a copper alloy, it is excellent in strength and the like. In the insulated wire 2C shown in FIG. 3, the case where the conductor 20 includes a single-wire composite wire is shown, but the conductor 20 may include a stranded wire of the composite wire. In the cross section of the composite wire, the area ratio of the copper coating portion 22 to the entire composite wire can be appropriately selected. The larger the area ratio, the larger the copper component and the better the conductivity, and the smaller the area ratio, the larger the aluminum component and the weight can be reduced. The area ratio may be, for example, 10% or more and 30% or less.

The insulating layer 25 is formed by extruding the above-mentioned electrically insulating material to the outer circumference of the conductor 20 and covering the outer circumference of the conductor 20 with a predetermined thickness. The insulating layer 25 can be colored so that each insulated wire 2 can be visually identified (eg, one is black, the other is white, etc.).

As each insulated wire 2, known ones can be used. Further, in FIG. 1 and the like, the number of the insulated wires 2 is two, but it can be three or more.

(Sheath part)
<Overview>
The sheath portion 3 is formed by arranging a plurality of insulated electric wires 2 so that their axes are parallel to each other, extruding a raw material forming the sheath portion 3 around them, and covering the outer periphery thereof with a predetermined thickness. NS. The sheath portion 3 includes a foamed region 30 made of foamed resin as an inner region that directly covers a plurality of insulated wires 2 arranged side by side, and a non-foamed resin or unfoamed region as an outer region including the surface of the flat cable 1. A solid region 33 made of resin is provided.

<Expanded area>
In FIG. 1 and the like, the foamed region 30 covers the electric wire group along the outline of the electric wire group in which the adjacent insulated electric wires 2 and 2 are substantially in line contact with each other, and the outer shape thereof is different from the outline of the electric wire group. The case where it is molded into (race track shape) is illustrated. In this case, the foamed region 30 does not substantially have a portion sandwiched between the adjacent insulated wires 2 and 2, which can be formed by covering each insulated wire 2 over the entire circumference in the circumferential direction. .. However, as shown in FIG. 1, the foamed region 30 is a portion facing each other in the contour lines of the adjacent insulated wires 2 and 2 between the adjacent insulated wires 2 and 2 (in FIG. 1, both insulated wires 2 and 2 approach each other). It has an intervening region surrounded by an inner semicircular portion located in the direction) and common circumscribed wires L1 and L1 of both insulated wires 2 and 2. The foamed region 30 includes this intervening region and an annular racetrack-shaped region that covers the intervening region and the region formed by the plurality of insulated electric wires 2.

≪Constituent materials≫
The foamed resin is a resin containing a plurality of bubbles. The foaming region 30 can be formed, for example, by using a raw material containing a base resin and a foaming agent (which produces gas by heating) as an extrusion raw material. As the foaming agent, known ones can be used. Further, a master batch containing a foaming agent (see Patent Document 1) can be used. In addition, the raw materials may include various additives such as plasticizers, stabilizers, fillers, lubricants, antioxidants, light stabilizers, and modifiers.

Examples of the base resin of the foamed resin include polyvinyl chloride (PVC). PVC is excellent in durability, fatigue resistance, flame retardancy, etc., and by using it as a constituent material of the sheath portion 3 such as the foamed region 30 and the solid region 33, the sheath portion 3 is less likely to be scratched or the sheath portion is not easily scratched. 3 is excellent in flame retardancy. When the insulating layer 25 of the insulated wire 2 is also made of PVC, it can be a flat cable 1 having excellent durability, fatigue resistance, and flame retardancy.

Alternatively, the base resin of the foamed resin may contain polyethylene (PE). Since PE can reduce the environmental load, it can reduce the environmental load caused by the sheath portion 3 by using it as a constituent material of the sheath portion 3 such as the foamed region 30 and the solid region 33. When a material containing a flame retardant in addition to PE is used as a constituent material of the sheath portion 3, it is excellent in flame retardancy. When the insulating layer 25 of the insulated wire 2 is also made of PE and further contains a flame retardant, the flat cable 1 can be suitably used as a so-called eco-cable. Known flame retardants can be used.

≪Presence state of bubbles≫
This item will be described on the premise of the cross section of the flat cable 1. The measuring method such as the size of bubbles, the abundance ratio of bubbles, and the occupancy ratio of bubbles of a specific size will be described later.

By adjusting the manufacturing conditions and the like as described later, the size and abundance ratio of bubbles in the foamed region 30 can be adjusted. Here, when the sheath portion 3 is removed, a range that does not come into contact with the insulated wire 2 in the sheath portion 3, that is, a range that does not reach the common circumscribed lines L1 and L1 of the plurality of insulated wires 2 is cut with a cutter or the like. Therefore, for example, in the foamed region 30, if the above-mentioned cut portion to be cut contains relatively coarse bubbles, it is easy to cut. Further, when the sheath portion 3 contains relatively large bubbles, the sheath portion 3 has some flexibility and is easy for the operator to handle. On the other hand, since the non-cut portion that is not cut includes a portion that contacts the insulated wire 2, if relatively minute air bubbles are included, the operator may draw the flat cable 1 around before removing the sheath portion 3. Further, it is easy to properly hold the insulated wire 2 by preventing the insulated wire 2 from twisting in the sheath portion 3 and the adjacent insulated wires 2 and 2 from rubbing against each other. Moreover, since it contains minute bubbles, the sheath portion 3 can be easily torn off when the sheath portion 3 is removed. On the other hand, if the region on the cable surface side of the foamed region 30 contains relatively small bubbles, even if the solid region 33 is scratched, the scratches are prevented from extending to the inside of the foamed region 30. Easy to do.

For example, like the flat cable 1A shown in FIG. 1, the outer region 32o located closer to the surface of the flat cable 1A in the foamed region 30 is included in the inner region 32i located closer to the insulated wire 2 in the foamed region 30. Examples thereof include a form containing a bubble po smaller than the bubble pi (pi> po). In FIG. 1, an example is illustrated in which the outer region 32o is a region from the surface of the foamed region ₃₀ to 15% of the average thickness t 30 of the foamed region 30, and the inner region 32i is the rest. Since the outer region 32o contains minute air bubbles po, the solid region 33 is scratched when the flat cable 1 receives an external impact or rubs against the outside, and the scratches are formed on the foamed region 30. It is easy to prevent it from extending to the inside, and the foamed region 30 is not easily scratched. In particular, if the size of the bubble po contained in the outer region 32o is 50 μm or less, that is, if all the bubble po contained in the outer region 32o is a minute bubble of 50 μm or less, the foamed region 30 is more scratched. hard. When all the bubbles po are 45 μm or less, 40 μm or less, and 30 μm or less, scratches are more difficult to occur. On the other hand, if all the bubbles po are 5 μm or more, further 8 μm or more, and 10 μm or more, it is easy to cut as described above. If the outer region 32o contains coarse bubbles of more than 50 μm, it is easier to cut. However, the smaller the number of such coarse bubbles, the more preferably the occupancy ratio of the bubbles po of 50 μm or less is 80% or more, the above-mentioned scratches occur. It is hard to stick and is preferable.

_{The average thickness t 30} of the foamed region 30 is the contour line of two insulated wires 2 and 2 located at each end in the parallel direction among the plurality of insulated wires 2 arranged side by side (both insulated wires in FIG. 1). The average thickness of the annular race track-shaped region that covers the outer circumference of the region formed by the outer semicircular portion (2, 2 located in the direction away from each other) and a part of the common circumscribed wires L1 and L1 of the plurality of insulated wires 2. Satoshi. The average thickness of the racetrack-shaped region is such that a total of 10 measurement points are taken at equal intervals in the range between the region facing the common circumscribed line L1 and the common circumscribed line L1 at the outer edge of the foamed region 30. The average thickness at these measurement points can be mentioned.

As described above, the outer region 32o is less likely to be scratched when the number of bubbles is small to some extent, and is easily cut when the outer region 32o is contained in large amounts. For example, the abundance ratio of bubbles per unit area in the outer region 32o is 100 cells / mm ² or more and 600 cells / mm ² or less. If the outer region 32o ^{contains bubbles at a rate of 100 cells / mm 2} or more, there are many bubbles and it is easy to cut. The larger the abundance ratio, the easier it is to cut, and the abundance ratio can be 150 pieces / mm ² or more, further 200 pieces / mm ² or more, and the like. If the outer region 32o ^{contains bubbles at a rate of 600 cells / mm 2} or less, the number of bubbles is not too large, and the foamed region 30 can be made less likely to be scratched. The smaller the abundance ratio, the less likely it is to be scratched, and the abundance ratio can be 550 pieces / mm ² or less, further 500 pieces / mm ² or less, and the like. If the abundance ratio (pieces / mm ² ) of the above-mentioned bubbles in the outer region 32o satisfies the above-mentioned range and the occupancy ratio (%) of the bubbles po of 50 μm or less is 80% or more, it is easy to cut and is scratched. hard.

The size of the bubble pi contained in the inner region 32i near the insulated wire 2 is, for example, 10 μm or more and 100 μm or less (however, po <pi). The larger the bubble pi contained in the inner region 32i, the easier it is to cut, the easier it is to shred at the uncut portion, and the more flexible it is. It is mentioned that the above-mentioned bubble pi is included. The smaller the bubble pi contained in the inner region 32i, particularly the region close to the insulated wire 2, the easier it is to hold the insulated wire 2 appropriately, and the inner region 32i may contain bubble pi of 95 μm or less, 90 μm or less, and 80 μm or less. Can be mentioned.

Since it is easier to cut if the inner region 32i, particularly the cutting portion cut by a cutter or the like, contains coarse bubbles of more than 100 μm, such coarse bubbles may be included. However, if there are too many coarse bubbles in the inner region 32i, it is difficult to properly hold the insulated wire 2. For example, if the size of all the bubbles contained in the inner region 32i is 100 μm or less, the insulated wire 2 can be easily held properly, and as described above, it can be easily cut and shredded.

The inner region 32i is easier to cut when it contains a large amount of air bubbles, is easier to shred at the non-cut portion, and is also excellent in flexibility. On the other hand, the inner region 32i can easily hold the insulated wire 2 properly when the number of bubbles is small to some extent. For example, the abundance ratio of bubbles per unit area in the inner region 32i is 30 cells / mm ² or more and 300 cells / mm ² or less. When the inner region 32i, preferably the above-mentioned cut portion, ^{contains bubbles at a ratio of 30 cells / mm 2} or more, there are many bubbles, it is easy to cut, and it is excellent in flexibility. The larger the abundance ratio, the easier it is to cut and the more excellent the flexibility, and the abundance ratio can be 40 pieces / mm ² or more, further 50 pieces / mm ² or more, and the like. If air bubbles are contained in the inner region 32i, preferably at a position close to the insulated wire 2 at ^{a ratio of 300 cells / mm 2} or less, the number of air bubbles is not too large, and it is easy to properly hold the insulated wire 2 before removing the sheath portion 3. The smaller the abundance ratio, the easier it is to appropriately hold the insulated wire 2, and the abundance ratio can be 290 pieces / mm ² or less, further 280 pieces / mm ² or less, and the like. In the inner region 32i, if the abundance ratio (pieces / mm ² ) of the bubbles satisfies the above range and all the bubbles are 10 μm or more and 100 μm or less, it is easier to cut and the insulated wire 2 is easily held properly.

≪Measurement method≫
The size of the bubbles is measured as follows.
Take three or more cross sections of the flat cable 1 at intervals of 5 m or more in the longitudinal direction of the flat cable 1. Each cross section is observed with a scanning electron microscope, and a measurement area of a certain size (for example, about 500 μm × 500 μm or ^{about 0.25 mm 2} ) is taken from the inner region 32i and the outer region 32o in the observation image. .. All the bubbles existing in the measurement area (here, those cut into open pores) are extracted to obtain the cross-sectional area, and the diameter of a circle having an area equal to the cross-sectional area of each bubble is defined as the size of each bubble. do. Extraction of air bubbles, measurement of cross-sectional area, and the like can be easily performed by using an image processing device.

Using the above measurement results, the "occupancy ratio (%) of bubbles of 50 μm or less" is "the total cross-sectional area of bubbles of 50 μm or less with respect to _{the total cross-sectional area of all bubbles existing in one measurement region.} The ratio of S _{50 = (S 50} / S _all ) × 100 (%) ”.
"Abundance ratio of bubbles per unit area" means "ratio of the number N of all bubbles existing in one measurement area or the number N of bubbles of a specific size to the area S of one measurement area". = N / S ”.
_{Obtain the above-mentioned occupancy ratio (S 50} / S _all ) × 100 and abundance ratio N / S of each measurement area taken from the above three cross sections, and use the average value of the values of the three measurement areas. Can be mentioned.
"The size of the bubbles contained in the outer region is 50 μm or less" means that the maximum diameter of the bubbles in each measurement region taken from the above three cross sections is 50 μm or less.
"The size of the bubbles contained in the inner region is 10 μm or more and 100 μm or less" means that all the bubbles in each measurement region taken from the above three cross sections are 10 μm or more and 100 μm or less.

<Solid area>
Since the solid region 33 does not substantially contain air bubbles, the solid region 33 is excellent in rigidity as compared with the foamed region 30 containing a plurality of air bubbles. The flat cable 1 provided with the solid region 33 forms the cable surface as well as being able to prevent the foamed region 30 from being scratched even when it receives an impact from the outside or rubbing against the outside (eg, the ground). The solid area 33 itself is not easily scratched.

≪Constituent materials≫
The solid region 33 includes a form in which the foaming agent is omitted from the raw material of the foaming region 30 described above, that is, a non-foaming resin containing no foaming agent (eg, PVC, PE, etc.). In this case, the interface 330 between the solid region 33 and the foamed region 30 is provided. Even if the sheath portion 3 is scratched, it is easy to grasp whether the scratch reaches the formation range of the solid region 33 or the foamed region 30 by checking whether or not the interface 330 is exposed. Alternatively, the solid region 33 is substantially foamed by using a raw material containing a base resin and a foaming agent (which may be the same as the raw material of the foaming region 30) and adjusting the thickness thereof, cooling conditions after extrusion, and the like. Examples thereof include a form made of a non-foamed resin (eg, PVC, PE, etc.). In this case, the solid region 33 and the foamed region 30 are distinguished by a region in which bubbles are substantially absent and a region in which bubbles are present.

≪Color≫
The solid region 33 may have a different color from the outer region (for example, the above-mentioned outer region 32o) located near the surface of the flat cable 1 in the foamed region 30. The color of the solid region 33 and the color of the entire foamed region 30 may be different from each other. Since the colors of the two are different, even if the sheath portion 3 is scratched, it can be easily determined whether or not the scratch reaches the foaming region 30. The sheath portion 3 is usually used in a state where the one end side of the flat cable 1 in the longitudinal direction is removed and the other end side remains to hold the insulated wire 2. Therefore, when there is a scratch reaching the foamed region 30, if the scratch is in the removed portion in the sheath portion 3, it may be left as it is, but if it is in the remaining portion in the sheath portion 3, the scratched portion is appropriately repaired. Can be mentioned.

In the form in which the solid region 33 is made of a non-foaming resin, for example, the non-foaming resin contains a pigment, and the foaming resin forming the foaming region 30 does not contain a pigment or contains a pigment having a different color, so that the solid region 33 is a solid region. The color of 33 and the color of the foamed region 30 can be easily different. The color of the solid region 33 can be appropriately selected.

In the form in which the solid region 33 is made of unfoamed resin, the solid region 33 has substantially no air bubbles, and the foamed region 30 has air bubbles, so that the transparency and the like of the two regions are different. It may be distinguishable. In this case, it is easy to grasp the degree of scratches as described above. When the same raw material as the foamed region 30 is used to form the solid region 33 made of unfoamed resin, the unfoamed resin contains a pigment, and the foamed resin forming the foamed region 30 does not contain a pigment or a pigment having a different color. By including it, the color of the solid region 33 and the color of the foamed region 30 can be easily made different. In this case, the interface 330 can be easily confirmed between the solid region 33 and the foamed region 30 due to the difference in color.

≪Thickness≫
As shown in FIG. 3, the solid region 33 covers the entire circumference of the foamed region 30, and the thickness thereof is typically uniform in the circumferential direction of the foamed region 30. In this case, the solid region 33 forms a racetrack-shaped annular body. The average thickness _{t 33} of the solid region 33, for example, 5% to 20% or more of the average thickness _{t 30} of the above-mentioned foamed region 30. When the average thickness t ₃₃ of the solid region 33 satisfies the above range, the solid region 33 is not too thin and is not easily scratched, the foamed region 30 can be protected, and when it is not too thick, it is easy to cut and the non-cut portion. Is easy to shred. The average thickness _{t 33} of the solid region 33 may be a 18% or less than 8% of the average thickness _{t 30} of the foam region 30. The average thickness t ₃₃ of the solid region 33 is above the interface 330, or bubbles seek distance from the boundary of the substantially non-existent region and the region in which bubbles are present to the outer edge of the solid area 33, and the average Can be mentioned. 10 or more measurement points may be taken at equal intervals in the circumferential direction of the solid region 33.

Alternatively, the solid region 33 may be in a form having a partially different thickness. For example, like the sheath portion 3A shown in FIG. 1, the solid region 33 includes a thick portion 335 locally thick in the circumferential direction of the sheath portion 3A. The thick portion 335 is typically a portion thicker than _{the average thickness t 33 of the solid region 33 described above.} The thick portion 335 can be a portion that is not easily scratched by the above-mentioned external impact or rubbing with the outside. Further, when the thick portion 335 is provided, the strength and rigidity of the sheath portion 3A may be increased even if the solid region 33 has a relatively thin portion. For example, if the thick-walled portions 335 and 335 are provided at opposite positions as shown in FIG. 1, it is easy to increase the resistance to an impact in the direction of penetrating both the thick-walled portions 335 and 335 (vertical direction in FIG. 1). Further, by locally providing the thick portion 335, the sheath portion 3 can be easily cut and the sheath portion 3 can be easily torn apart as compared with the case where the entire solid region 33 is uniformly thick, and the sheath portion 3 can be removed. Excellent in sex. The number and formation positions of the thick portion 335 shown in FIG. 1 are examples and can be changed as appropriate.

When the thick portion 335, 335 is provided at a position where the solid region 33 corresponds to the adjacent insulated wires 2 and 2 in the foamed region 30, this position is easily rubbed with the outside as described later, but is scratched. hard. In addition, this form can also be expected to have the following effects. The position corresponding to the adjacent insulated wires 2 and 2 in the foamed region 30 is, for example, a position covering the contour line of the adjacent insulated wires 2 and 2 and the intervening region surrounded by the common circumscribed lines L1 and L1. Can be mentioned.
(1) When the portion corresponding to the above-mentioned insulated wires 2 and 2 in the solid region 33 is cut with a cutter or the like when the sheath portion 3A is removed, the thick portion 335 pressed by the cutter or the like locally localizes the foamed region 30. It is considered that the stress is locally applied by pressing the cable. It is expected that this stress makes it easier for the above-mentioned intervening region, which is a non-cutting portion, to be broken in the foamed region 30, and to be easily torn.
(2) On the surface of the solid region 33, the portion corresponding to the above-mentioned insulated wires 2 and 2 is a flat surface as described later, so that a portion where a product name, a serial number, etc. are printed, an embossing process, or the like is added. May be used as. If the thick portion 335 is engraved, the engraving can be performed to a sufficient depth, and the engraving can be easily maintained for a long period of time. Engraving is harder to erase for a long time than printing.

The solid region 33 may include a thick portion 335 and a relatively thin thin portion. The thin portion is typically a portion thinner than _{the average thickness t 33 of the solid region 33 described above.} As an example of providing a thin portion, in the solid region 33, the thickness ts of the lateral portions located on both sides of the plurality of insulated wires 2 groups arranged in parallel corresponded between the adjacent insulated wires 2 and 2 in the foamed region 30. It can be mentioned that it is thinner than the thickness of the intermediate portion existing at the position (thickness t _{335 of the thick portion 335 in FIG. 1).} Most of the lateral portions are included in non-cutting portions that are not cut by a cutter or the like when the sheath portion 3A is removed, but since the thickness ts of the lateral portions is thin, it is easy to shred. Further, in this form, the solid region 33 as a whole is not easily scratched for the following reasons. In the solid region 33, the outer peripheral surface of the intermediate portion is typically formed by a flat surface parallel to the straight line Lc connecting the centers of the adjacent insulated wires 2 and 2. The outer peripheral surface of the lateral portion (the left and right regions in FIG. 1) is formed by a semicircular curved surface. It can be said that such an intermediate portion is a portion that is more likely to rub against the outside than the lateral portion, and conversely, the lateral portion is a portion that is less likely to rub. Therefore, even if the thickness ts of the side portion is thin, it is unlikely to be scratched due to rubbing with the outside. Since the middle part is relatively thick, it is hard to be scratched by rubbing with the outside. If the intermediate portion is the thick portion 335 described above, it is more difficult to be scratched.

_{The thickness t 335} of the thick portion 335 described above is, for example, about 100% or more and 200% or less _{of the average thickness t 33} of the solid region 33 described above. The thickness of the thin portion and the thickness ts of the side portion may be, for example, about 10% or more and 80% or less _{of the average thickness t 33 of the solid region 33 described above.} FIG. 1 illustrates a case where the thickness of the portion of the solid region 33 excluding the thick portion 335 is substantially the same, and the thickness ts of the side portion is substantially equal to the average thickness t _33. It can be made even thinner as virtually indicated by the dotted line.

<Manufacturing method>
In the flat cable 1 of the embodiment, basically, a plurality of insulated electric wires 2 are prepared, a raw material forming a sheath portion 3 is extruded on the outer periphery thereof by an extruder, and the extruded material is introduced into a water tank to be cooled. It can be manufactured by. The extruder includes, for example, an inner extrusion die that forms a foamed region 30 on the outer periphery of the insulated wire 2, an outer extrusion die that forms a solid region 33 on the outer periphery of the foamed region 30, and a nipple that guides the insulated wire 2. Things are available. The raw material of the foamed region 30 and the raw material of the solid region 33 may be extruded at the same time. The thickness t ₃₃₅ and the forming position of the thick portion 335, preset and thickness of the side portion, by using a die having a shape suitable for this setting condition, the thick portion 335 and thin side parts It is possible to mold the form to be provided. As the extruder, a known structure can be used. For the above-mentioned basic steps, a known production method used for producing VVF can be referred to.

In particular, in order to adjust the size of bubbles, the position and number of bubbles of a specific size, etc., for example, it takes 0.3 seconds or more to introduce the extruded material from the extruder into the water tank. It may be 4 seconds or less. By setting the time to introduction as described above to 4 seconds or less, it is easy to cool the extruded material quickly, and it is easy to shorten the time for the foaming agent in the raw material to be decomposed and the bubbles to grow large. As a result, it is easy to reduce the bubbles as a whole. In particular, it is easy to manufacture a flat cable 1A in which minute bubbles are present in the outer region 32o near the surface of the extruded material. On the other hand, by setting the time until introduction described above to 0.3 seconds or more, the extruded material can be maintained at the external environmental temperature to some extent. Therefore, it is easy to increase the number of bubbles existing in the inner region 32i located inside the extruded material to some extent.

When the solid region 33 is made of unfoamed resin, for example, the surface of the extruded material and its vicinity (the region where the solid region 33 is formed) are substantially adjusted by adjusting the time until the solid region 33 is introduced into the above-mentioned water tank. It is possible to foam to some extent in the inner region (foamed region 30) without foaming. When the solid region 33 made of unfoamed resin is formed by using the same raw material as the foamed region 30, the above-mentioned outer extrusion die may be omitted. When using an unfoamed resin containing a pigment, it is preferable to use an outer extrusion die.

In addition, the time until introduction into the above-mentioned water tank may be adjusted according to the type of the base resin (temperature in the molten state), the content of the foaming agent, and the like.

<Main effect>
In the flat cable 1 of the embodiment, the sheath portion 3 includes a foamed region 30 and a solid region 33. Due to the foamed region 30, when removing a part of the sheath portion 3, the flat cable 1 is easy to cut with a cutter or the like, and it is easy to cut off a non-cut portion that is not directly cut by a cutter or the like. Excellent removal workability. Moreover, the solid region 33 makes it possible for the flat cable 1 to prevent the solid region 33 itself from being scratched as well as the foamed region 30. Even when the foamed region 30 does not have the outer region 32o containing minute air bubbles po, the solid region 33 makes it difficult to be scratched. If a thick portion 335 is provided as in the flat cable 1A of the first embodiment, scratches can be made less likely to occur. When the above-mentioned lateral portion is made relatively thin, the uncut portion of the solid region 33 can be easily torn off, and the removal workability of the sheath portion 3 is excellent.

If minute air bubbles po are present in the outer region 32o of the foamed region 30 as in the sheath portion 3A, even if the solid region 33 is scratched, the scratches are unlikely to propagate to the foamed region 30. If the bubble pi contained in the inner region 32i has the above-mentioned specific size, it is easy to cut, it is easy to shred at the non-cut portion, it is also excellent in flexibility, and the removal workability of the sheath portion 3 is excellent. Further, the insulated wire 2 can be appropriately held.

(Ground wire)
<Structure>
The flat cable 1 of the embodiment may include a ground wire 5 as shown in FIG. The ground wire 5 includes a grounding conductor 50 and a coating layer 55 covering the grounding conductor 50. Typically, the ground wire 5 is compatible with or equivalent to a 600V vinyl insulated wire (IV), a 600V polyethylene insulated wire (IE), or the like. The flat cable 1B provided with the ground wire 5 can be used in applications requiring grounding. The ground wire 5 can be separated from the insulated wire 2 by tearing off the connecting portion with the sheath portion 3.

As the grounding conductor 50, typically, a single wire or a stranded wire of the electric annealed copper wire described in the above-mentioned section of the insulated wire, which has a predetermined conductor cross-sectional area and wire diameter can be used. FIG. 2 illustrates a grounding wire 5 including a single-wire grounding conductor 50.

The coating layer 55 is formed by extruding an electrically insulating material such as PVC or PE described in the above-mentioned section of the insulated wire to the outer periphery of the grounding conductor 50 and covering the outer periphery of the grounding conductor 50 with a predetermined thickness. Will be done. The outer shape of the grounding conductor 50 and the outer shape of the grounding wire 5 are typically circular.

The coating layer 55 may have a multi-layer structure as shown in FIG. 2 in addition to the single-layer structure (not shown). The ground wire 5 provided in the flat cable 1B shown in FIG. 2 includes a coating layer 55 having a two-layer structure. The coating layer 55 includes an inner coating layer 52 provided directly above the grounding conductor 50, and an outer coating layer 53 covering at least a part of the outer periphery of the inner coating layer 52. The constituent material of the inner coating layer 52 and the constituent material of the outer coating layer 53 can be different or have different colors. For example, the inner coating layer 52 may be made of a foamed resin, the outer coating layer 53 may be made of a non-foamed resin or a non-foamed resin, or both layers 52 and 53 may be made of a different kind of non-foamed resin. Can be mentioned. Further, for example, the inner coating layer 52 and the outer coating layer 53 may have different colors. When the inner coating layer 52 made of foamed resin is provided, the flexibility is excellent, the ground wire 5 can be easily separated from the sheath portion 3 before the sheath portion 3 is removed, and the workability is excellent. When the outer coating layer 53 made of a non-foamed resin or a non-foamed resin is provided, the rigidity is excellent as described in the section of the solid region, and the surface of the ground wire 5 and its vicinity due to an external impact or rubbing with the outside. Is not easily scratched. Further, since the ground wire 5 includes a coating layer 55 having a two-layer structure, the ground wire 5 is also excellent in insulating properties. Further, if the colors of the two layers 52 and 53 are different, even if the outer coating layer 53 is scratched, if the color of the inner coating layer 52 is not visible, it is visually apparent that the scratches do not reach the inner coating layer 52. Easy to check. When the color of the sheath portion 3B and the color of the coating layer 55 (particularly the outer coating layer 53) are different, the separation workability is excellent. The color of the outer coating layer 53 can be appropriately selected (for example, green). For details of the foamed resin, the non-foamed resin, and the non-foamed resin, refer to the section of the foamed region and the section of the solid region.

The ground wire 5 may be connected to one end side of a plurality of insulated wires 2 in the parallel direction at the sheath portion 3. In this case, the connection portion of the ground wire 5 in the sheath portion 3 can be easily made small (thin) as shown in FIG. 2, and the ground wire 5 can be easily separated from the sheath portion 3.

When the coating layer 55 has a two-layer structure, the inner coating layer 52 is a foamed resin, and the outer coating layer 53 is a non-foamed resin or a non-foamed resin as described above, for example, the inner coating layer 52 is a foamed resin in the sheath portion 3B. It can be formed continuously in the foamed region 30 made of. In this case, the foamed resin forming the foamed region 30 of the sheath portion 3B integrally forms the foamed region 30 to the inner coating layer 52 of the ground wire 5. Since the connection portion of the sheath portion 3B with the ground wire 5 is also integrally molded by the foamed resin, the ground wire 5 before being separated from the sheath portion 3B is unlikely to come off from the sheath portion 3B. At the time of separation, since the connecting portion is made of foamed resin, it is easy to shred and can be easily separated. As shown in FIG. 2, the thickness of the connecting portion (here, the size in the direction orthogonal to the straight line Lc (FIG. 1)) is sufficiently larger than the maximum thickness (same) of the sheath portion 3B and the outer diameter of the ground wire 5. The smaller the size, the easier it is to separate. Further, the outer coating layer 53 can be continuously formed in the sheath portion 3B in the solid region 33 made of a non-foaming resin or a non-foaming resin. In this case, the entire flat cable 1B including the ground wire 5 is less likely to be scratched by an external impact or rubbing against the outside as described above. Further, since the surface of the flat cable 1B and its vicinity are made of a uniform material, the appearance is also excellent. Even when the outer coating layer 53 and the solid region 33 are continuous, the colors of the outer coating layer 53 and the solid region 33 can be different depending on the presence or absence of a pigment or the like. FIG. 2 illustrates a case where the outer coating layer 53 and the solid region 33 are continuous and have different colors. The thicknesses of the inner coating layer 52 and the outer coating layer 53 may be selected according to the insulating characteristics and the like.

<Manufacturing method>
In the above-mentioned form in which the coating layer 55 having a two-layer structure and the sheath portion 3B are continuous, for example, an inner extrusion die that forms a foamed region 30 and an inner coating layer 52 on the outer periphery of the insulated wire 2 and the outer periphery of the grounding conductor 50, respectively. An extruder including an outer extrusion die for forming a solid region 33 and an outer coating layer 53 on the outer periphery of the foamed region 30 and the outer periphery of the inner coating layer 52, and a nipple for guiding the insulating electric wire 2 and the grounding conductor 50, respectively. Can be manufactured by using. The above-mentioned extruded die has a shape capable of forming a connecting portion. The raw materials of the foamed region 30 and the inner coating layer 52 and the raw materials of the solid region 33 and the outer coating layer 53 may be extruded at the same time. For other conditions, it is advisable to refer to the section of the manufacturing method described in the first embodiment described above.

<Main effect>
Since the flat cable 1B of the second embodiment includes the grounding wire 5, it can be used for electrical wiring for applications requiring grounding. The ground wire 5 can be easily separated from the sheath portion 3 before the sheath portion 3 is removed, and the workability before the removal of the sheath portion 3 is also excellent. In this example, since the foamed region 30 of the sheath portion 3B and the inner coating layer 52 of the grounding wire 5 are continuous, the grounding wire 5 is hard to come off during transportation before separation and is easy for the operator to handle.

(Use)
The flat cable 1 of the embodiment can be used for electrical wiring such as low-voltage indoor electrical wiring. In the form provided with the ground wire 5, it can be used for electrical wiring of electric machinery and equipment (air conditioner, electric water heater, IH cooking heater, etc.) that require grounding.

The present invention is not limited to these examples, and is indicated by the scope of claims, and is intended to include all modifications within the meaning and scope equivalent to the scope of claims.
For example, in the flat cable 1B shown in FIG. 2, the thick portion 335 may be omitted, or the flat cable 1C shown in FIG. 3 may be provided with the thick portion 335 and the ground wire 5.

1,1A, 1B, 1C Flat cable 2,2A, 2C Insulated wire 20 Conductor 21 Conductor wire 22 Copper coating 25 Insulation layer 3,3A, 3B Sheath 30 Foaming area 32i Inner area 32o Outer area 33 Solid area 330 Interface 335 Thick part 5 Grounding wire 50 Grounding conductor 55 Coating layer 52 Inner coating layer 53 Outer coating layer Lc Straight line connecting the center of the insulated wire L1 Common external wire pi, po Bubbles

Claims (12)

A flat cable having a plurality of insulated wires having an insulating layer on the outer circumference of a conductor and a sheath portion that collectively covers the outer circumferences of the plurality of insulated wires.
The sheath portion is
The plurality of insulated wires are covered side by side, and a foamed region made of foamed resin and a foamed region are formed.
It said covering the outer periphery of the bubble-generating region, and a solid region viewed free made of non-foamed resin or unfoamed resin,
The solid region includes a thick portion locally thick in the circumferential direction of the sheath portion.
The thick portion is provided at a position corresponding to the adjacent insulated electric wires in the foamed region.
Flat cable. In the solid region, the thickness of the lateral portions located on both sides of the plurality of insulated wires in parallel is larger than the thickness of the intermediate portion existing at a position corresponding to the adjacent insulated wires in the foamed region. The flat cable according to claim 1. A flat cable having a plurality of insulated wires having an insulating layer on the outer circumference of a conductor and a sheath portion that collectively covers the outer circumferences of the plurality of insulated wires.
The sheath portion is
The plurality of insulated wires are covered side by side, and a foamed region made of foamed resin and a foamed region are formed.
It said covering the outer periphery of the bubble-generating region, and a solid region viewed free made of non-foamed resin or unfoamed resin,
In the solid region, the thickness of the lateral portions located on both sides of the plurality of insulated wires in parallel is larger than the thickness of the intermediate portion existing at a position corresponding to the adjacent insulated wires in the foamed region. thin,
Flat cable. The flat cable according to claim 3 , wherein the solid region includes a thick portion locally thick in the circumferential direction of the sheath portion. The flat cable according to any one of claims 1 to 4 , wherein the solid region and the outer region located near the surface of the flat cable in the foamed region have different colors. A flat cable having a plurality of insulated wires having an insulating layer on the outer circumference of a conductor and a sheath portion that collectively covers the outer circumferences of the plurality of insulated wires.
The sheath portion is
The plurality of insulated wires are covered side by side, and a foamed region made of foamed resin and a foamed region are formed.
It said covering the outer periphery of the bubble-generating region, and a solid region viewed free made of non-foamed resin or unfoamed resin,
The solid region and the outer region located closer to the surface of the flat cable in the foamed region are different in color.
Flat cable. The flat cable according to claim 6 , wherein the solid region includes a thick portion locally thick in the circumferential direction of the sheath portion. The flat cable according to any one of claims 5 to 7 , wherein the solid region contains a pigment. The flat cable according to any one of claims 1 to 8 , wherein the average thickness of the solid region is 5% or more and 20% or less of the average thickness of the foamed region. Any of claims 1 to 9 , wherein the outer region located near the surface of the flat cable in the foamed region includes bubbles smaller than the bubbles contained in the inner region located near the insulated wire in the foamed region. The flat cable described in item 1. The flat cable according to claim 10 , wherein the size of the bubbles contained in the outer region is 50 μm or less. The flat cable according to claim 10 or 11 , wherein the abundance ratio of bubbles per unit area in the outer region is 100 cells / mm ² or more and 600 cells / mm ² or less.

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