JP7608382B2 - Cable manufacturing method - Google Patents

Description

The present invention relates to a method for manufacturing a cable. More specifically, the present invention relates to a method for manufacturing a cable used , for example , for connecting a personal computer to a smartphone or for connecting a smartphone to an outlet provided in a wall or the like.

Conventionally, cables having connectors (connection terminals) at both ends have been known as cables used for connecting electronic devices to each other or for connecting an electronic device to a wall outlet or the like (for example, Patent Document 1). The cables are usually configured by covering the outer periphery of a core material made of a linear conductor with a resin composition containing a thermoplastic resin.

Such cables are usually of a portable length (e.g., about 50 cm to 200 cm).
The insulating film is formed to have a

JP 2019-75313 A

When the cable formed as described above is stored in a bag or the like and carried, the cable is usually stored in a wound state.
However, the cable generally cannot maintain its wound state and tends to unfold inside a bag or the like.
That is, there is a problem in that it is difficult to use when stored.

From the standpoint of maintaining the wound state, it is also possible to configure the cable so that it has a spiral (helical) winding tendency when not pulled, like the cable connecting the telephone body and handset of a landline telephone.
However, when a cable is configured to have a spiral winding tendency as described above, when connecting electronic devices to each other or to an outlet on a wall or the like, simply grabbing both ends of the cable with one hand and pulling them apart will result in the cable becoming unreliable.
It is difficult to stretch the cable to a certain length, and it is also impossible to maintain the stretched state, making connection work difficult.
Therefore, such a configuration has the problem of being difficult to use.

However, for a cable that is easy to use both when storing and using,
It is difficult to say that sufficient consideration has been given to this issue yet.

Therefore, an object of the present invention is to provide a method for manufacturing a cable that can provide a cable that is easy to use both when stored and when in use.

After careful consideration, the inventors discovered that a cable manufactured by wrapping the cable around a cylindrical body and heating it for a predetermined period of time while maintaining the temperature within a predetermined range is easy to use both during storage and during use, and thus arrived at the present invention.

That is, the method for producing a cable according to the present invention comprises the steps of:
a winding step of winding a cable, in which an outer periphery of a core material made of a linear conductor is covered with a resin composition containing polyvinyl chloride and an outermost layer is formed of the resin composition, around a cylindrical body;
a heating step of heating the cable wound around the cylindrical body for 60 minutes or more while maintaining the temperature within a range of 79° C. to 121° C.;
and a cooling step of cooling the heated cable to a temperature within a range of 9°C to 36°C while the cable is wound around the cylindrical body ,
The cable is used to connect a smartphone.

According to the present invention, it is possible to provide a method for manufacturing a cable that can provide a cable that is easy to use both when stored and when in use.

FIG. 2 is a flow diagram of a method for manufacturing a cable according to an embodiment of the present invention.

One embodiment of the present invention is described below.

As shown in FIG. 1, the method for producing a cable according to the present embodiment includes the following steps:
A winding step (S1) of winding a cable in which the outer periphery of a core material made of a linear conductor is covered with a resin composition containing polyvinyl chloride and the outermost layer is formed of the resin composition, around a cylindrical body.
and,
a heating step (S2) of heating the cable wound around the cylindrical body for 60 minutes or more while maintaining the temperature within a range of 79° C. or more and 121° C. or less;
and a cooling step (S3) of cooling the heated cable to a temperature within a range of 9°C to 36°C while the cable is wound around the cylindrical body.
Hereinafter, the method for producing a cable according to this embodiment will be described step by step.

(Winding process S1)
In the winding step S1, the cable is wound around the cylindrical body. It is preferable that the cable is wound around the cylindrical body without any gaps (so that the width between the cables when wound around the cylindrical body (hereinafter, also referred to as the pitch width) is 0 mm).
In the winding step S1, it is preferable to use a cylindrical body having an outer diameter of 1.5 cm or more and 20 cm or less.

The cross-sectional shape of the cylindrical body is appropriately selected according to the shape of the curl to be given to the cable. The shape of the curl may be a circle, a regular polygon (for example, a square, a regular hexagon, or a regular octagon).
However, a circular shape is usually preferable. That is, the cross-sectional shape of the cylindrical body is preferably a circular shape.

The conductor of the core material is, for example, a copper wire, etc. The core material may be made of a single conductor or a plurality of conductors.
When the core material is made of a plurality of conductors, the core material may be made by twisting the plurality of conductors together.
Furthermore, the outer periphery of each of the plurality of conductors may be covered with a resin composition containing polyvinyl chloride resin.
By twisting a plurality of conductors together to form the core material, the core material has excellent flexibility.

When used as a cable for connecting electronic devices to each other or between an electronic device and a wall outlet or the like, the cable preferably has a thickness of 3.0 mm or more and 5.0 mm or less.
The thickness of the cable can be measured using a micro gauge.
Specifically, the thickness is measured at any five points in the extending direction of the cable using a microgauge, and the arithmetic average of these measured values is calculated.

When used as a cable for connecting electronic devices to each other or between an electronic device and a wall outlet or the like, the thickness of the core material is preferably 2.3 mm or more and 4.8 mm or less.
When the cross-sectional shape of the core material is circular, the thickness of the core material means the diameter (outer diameter) of the circle,
When the cross-sectional shape of the core material is a regular polygon (for example, a square, a regular hexagon, or a regular octagon), the thickness of the core material means the diameter (outer diameter) of a circumscribing circle that circumscribes the regular polygon.
The cross section refers to a cross section obtained by cutting the cable in a direction perpendicular to the extending direction.

In the cable according to the present embodiment, the thickness of the coating made of the resin composition is 0.2 mm or more.
It is preferable that the thickness is 0.7 mm or less.
The coating thickness means a value obtained by subtracting the thickness of the core material from the maximum length of the cable in cross section and dividing the value by two.
The coating thickness can be measured using a microgauge.
Specifically, the thickness of the coating is measured at any 10 points on each cross section cut at any 5 points in the extension direction of the cable using a microgauge, and the thickness can be determined by arithmetically averaging these measured values.
In addition, when the cable is used as a cable for connecting electronic devices to each other or between an electronic device and an outlet provided on a wall or the like, the length of the cable (the straight-line distance when stretched out in a straight line) is, for example, within a range of 50 cm or more and 200 cm or less (0.5 m or more and 2 m or less).

The resin composition may contain, in addition to polyvinyl chloride, a plasticizer, a stabilizer, a filler, a color powder, and the like.
The plasticizer includes phthalate esters, such as dioctyl phthalate (DOP), dibutyl phthalate (DBP), etc. The plasticizer reduces the flow viscosity of the resin composition when heated during molding to facilitate processing, and after being made into a cable, imparts flexibility and rubber elasticity to the cable, thereby making the cable excellent in extensibility.
The stabilizer is tribasic lead sulfate ( _{3PbO.PbSO4.H
2O} ) and the like.
The filler may, for example, be calcium carbonate.
The color powder may include titanium oxide.
The resin composition may further contain a lubricant.
The lubricant may be dibasic lead stearate (2PbO.Pb.Stearate) or the like.
The resin composition comprises the plasticizer, the stabilizer, a filler, and
When color powder is included, the plasticizer is preferably contained in an amount of 10 parts by mass or more and 100 parts by mass or less, the stabilizer is preferably contained in an amount of 1 part by mass or more and 10 parts by mass or less, the filler is preferably contained in an amount of 33 parts by mass or more and 43 parts by mass or less, and the color powder is preferably contained in an amount of 0.5 parts by mass or more and 1.
It is preferable that the content is 0 parts by mass or less.
In addition, when the resin composition further contains the lubricant, it is preferable that the resin composition contains 0.5 parts by mass or more and 5 parts by mass or less of the lubricant per 100 parts by mass of the polyvinyl chloride.

The outer periphery of the core material can be covered with the resin composition containing polyvinyl chloride by any of various known methods, including, for example, melt extrusion molding.
Melt extrusion molding can be performed using a general melt extrusion molding device, for example, an apparatus including a delivery section that sends out the core material in a wound state downstream, an extrusion section arranged downstream of the delivery section to coat the outer periphery of the sent-out core material with the molten resin composition and extrude the core material coated with the resin composition (hereinafter also referred to as the coated core material) downstream, a cooling section arranged downstream of the extrusion section to cool and solidify the resin composition of the coated core material, and a winding section arranged downstream of the cooling section to wind up the coated core material (i.e., cable) after the resin composition has solidified.

(Heating step S2)
In the heating step S2, the cable wound around the cylindrical body is heated to a temperature of 79° C. to 121° C.
It is important to heat for 60 minutes or longer while maintaining the temperature within the following range.
The heating step S2 can be carried out using a general heating furnace.
By heating for 60 minutes or more while maintaining the temperature within the range of 79°C or more and 121°C or less, and then cooling to 9°C or more and 36°C or less in the cooling step S3 described below, the cable with a spiral curl can be relatively easily stretched to a certain length by simply grasping both ends of the cable with hands and pulling them apart, and the stretched state can be relatively easily maintained.
Furthermore, when the stretched state is wound into a spiral shape, the spiral shape can be relatively well maintained.
This improves ease of use during storage and use.
The heating temperature in the heating step S2 is preferably 89° C. or higher and 121° C. or lower.

While maintaining the temperature within the range of 79°C to 121°C, heat for 60 minutes or more, then
The present inventors consider the reason why the above-mentioned effects are achieved by cooling to 36° C. or less as follows.
In other words, when the cable is wrapped around the cylindrical body and heated for 60 minutes or more while maintaining a temperature within the range of 79°C or more and 121°C or less, and then cooled to 9°C or more and 36°C or less, the wrapped cable solidifies in a moderately shrunken state on the inside (the side in contact with the cylindrical body) and in a moderately stretched state on the outside (the side not in contact with the cylindrical body), and it is believed that the cable has acquired a winding tendency that makes it easier to maintain the wound state when in a wound state and easier to maintain the stretched state when in a stretched state.
As a result, it is believed that by simply grabbing both ends of a cable that has developed a spiral tendency and pulling them apart, the cable can be relatively easily stretched to a certain length, and the stretched state can be relatively well maintained; further, when the cable is wound up into a spiral shape from the stretched state, the spiral shape can be relatively well maintained.

In addition, the upper limit of heating time is set as follows, because if the heating time is too long, the energy efficiency will decrease.
Preferably, it is 240 minutes.

(Cooling process S3)
In the cooling step S3, the heated cable is wound around the cylindrical body and cooled to a temperature of 9° C. or higher for 3 hours.
The mixture is cooled to a temperature within a range of 6° C. or less. The temperature range is preferably from 14° C. to 31° C., and more preferably from 19° C. to 26° C.
The time required for cooling to a temperature in the range of 9° C. or more and 36° C. or less is preferably 20 minutes or more and 40 minutes or less.
In addition, when the heating step S2 is performed in a heating furnace, the cooling step S3 is performed, for example, by naturally cooling the heated cable to a temperature in the heating furnace within a range of 9° C. to 36° C., or by cooling the heated cable to a predetermined temperature (for example, 39° C. to
After the mixture is naturally cooled to a temperature of 51° C., it is removed from the heating furnace and further naturally cooled to a temperature in the range of 9° C. to 36° C. in an open atmosphere.
In addition, when a cylinder having an outer diameter of 1.5 cm or more and 20 cm or less is used, after the cooling process S3, the maximum length of the wound portion of the cable (hereinafter also referred to as the winding diameter) is in the range of 2.3 cm or more and 30 cm or less.

The cable manufacturing method according to the present invention is not limited to the above-described embodiment.
Furthermore, the cable manufacturing method according to the present invention is not limited to the above-mentioned effects and advantages. The cable manufacturing method according to the present invention can be modified in various ways without departing from the gist of the present invention.

The present invention will now be described in more detail with reference to examples. The following examples are provided to further explain the present invention in detail, and are not intended to limit the scope of the present invention.

[Tensile test]
Specimens for tensile testing were obtained as follows.
First, three cables (cable A, cable B, and cable C) each having a length of approximately 1 m (1 m ± 1 cm) and each having a core material made of a conductor (multiple conductors (copper wires) coated with a resin composition on the outer periphery) coated with a resin containing polyvinyl chloride were spirally wound with a pitch width of 0 mm around a cylindrical tube (diameter (outer diameter) 3.8 cm × height 200 cm) to obtain a tube with the cables wrapped around it (hereinafter also referred to as a tube with cables).
Next, these cylinders with cables (the cylinder with cable A wound around it, the cylinder with cable B wound around it, and the cylinder with cable C wound around it) were placed in a heating furnace and treated at 120±1°C for 60 minutes.
Next, these cylindrical bodies with cables were naturally cooled to room temperature (23±2° C.) in a heating furnace to obtain specimens for tensile tests. The maximum length of one turn (hereinafter also referred to as the winding diameter) of each cable obtained by winding the cable around a cylindrical body with a diameter (outer diameter) of 3.8 cm and heating the cable was 5.5±1.5 cm.
Cable A, Cable B, and Cable C all had a circular cross-sectional shape.
In addition, in cable A, the thickness (outer diameter) of the core material was 3.2 mm and the thickness of the coating was 0.4 mm, in cable B, the thickness (outer diameter) of the core material was 3.3 mm and the thickness of the coating was 0.4 mm, and in cable C, the thickness (outer diameter) of the core material was 4 mm and the thickness of the coating was 0.4 mm .
The coating thickness of each of the cables A to C was measured according to the method described in the embodiment section above.
The cable thicknesses of Cables A to C were measured according to the method described in the embodiment section above.
Three specimens for each cable (total of nine specimens) were prepared for the tensile test.
Then, a tensile test was carried out on each specimen (a total of nine specimens) according to the following procedure.

(1) One end of the specimen is fixed to the top plate of a fixture having a top plate.
(2) With the specimen hanging down from the top plate, the length from the fixing point on one end of the specimen to the tip of the other end of the specimen (length L1 before attachment of the weight) is measured.
(3) Attach a 100 g weight to the other end of the specimen and leave it for 60 minutes.
(4) Remove the 100 g weight from the other end of the specimen.
(5) Measure the length from the fixed point on one end of the specimen to the tip of the other end of the specimen (length L2 after the weight is attached).

The results of the tensile test for cable A are shown in Table 1 as Examples 1 to 3, for cable B as Examples 4 to 6, and for cable C as Example 7.
These are shown in Table 3 as 1 to 9.
In order to compare with the tensile test results of the cables according to Examples 1 to 9, three samples of each of Cable A, Cable B, and Cable C that had not been subjected to the above-mentioned heat treatment were prepared (a total of nine samples), and tensile tests were performed according to the above-mentioned procedure.
The results of the cable A are shown in Table 1 as Comparative Examples 1 to 3, the cable B as Comparative Examples 7 to 9, and the cable C as Comparative Examples 13 to 14.
5, as shown in Table 3.
Furthermore, in order to compare with the results of the tensile test of the cable prepared as described above, cable A
Each of Cable A, Cable B, and Cable C was spirally wound around a cylindrical body (diameter (outer diameter) 1 cm × height 200 cm) with a pitch width of 0 mm, and then treated in a heating furnace at 120±1°C for 40 minutes.Then, they were naturally cooled to room temperature (23±2°C) in the heating furnace, thereby producing three spiral-shaped specimens for tensile tests connecting the telephone body and handset (9 specimens in total), and tensile tests were performed according to the procedure described above.
The results are shown in Table 1 as Comparative Examples 4 to 6 for Cable A, in Table 2 as Comparative Examples 10 to 12 for Cable B, and in Table 3 as Comparative Example 16 for Cable C.
The results are shown in Table 3 as ~18.

From Tables 1 to 3, the cable A (Examples 1 to 3), cable B (Example 4)
Cables A (Comparative Examples 1 to 3), Cables B (Comparative Examples 7 to 9), and Cable C (Comparative Examples 1 to 6) were not subjected to a heat treatment.
3 to 15), it can be seen that the length L2 after the weight is attached is shorter, making it possible to store it more compactly.
In addition, the cables A, B, and C according to the respective examples all have a spiral shape.
Furthermore, it can be seen that the length L2 after the weight is attached is sufficient compared to cable C (Comparative Examples 16 to 18).

[Evaluation of maintenance of winding state]
Before carrying out the tensile test, the specimens according to Examples 1 to 9 were evaluated for their ability to maintain the wound state.
The maintenance of the wound state was evaluated according to the following procedure.

(1) With the specimen in a stretched state, both ends are fixed while maintaining that state.
(2) Keep the specimen with both ends fixed for 24 hours.
(3) The specimen, which has been released from the fixed state at both ends, is placed on a flat plate with a diameter of 5.5 ± 1.5 cm.
The specimen is wound so that it has a shape of multiple connected circles (spiral shape).
(4) Repeat steps (1) to (3) five times, and measure the length of the longest part of one turn (hereinafter also referred to as the winding diameter) 10 minutes after each cycle.
(5) In all five cycles, the length of the longest part of one turn (winding diameter) was 5.5±1.
If the difference is within 5 cm, it is determined that the wound state is maintained.

The results are shown in Table 4 below.

According to the above procedure, the specimens according to Examples 1 to 9 were evaluated for their ability to maintain the wound state. As a result, for all specimens, the length of the longest part of one turn (winding diameter) was within the above numerical range (
It was found that the rolling distance was within 5.5±1.5 cm. In other words, it was found that all of the specimens according to Examples 1 to 9 were able to maintain the rolling state (see Table 4).
In contrast, cables A according to comparative examples 1 to 3, cables B according to comparative examples 7 to 9, and
For the cables C according to the comparative examples 13 to 15, the diameter was 5.5±1.5 cm on a flat plate.
I tried to roll it so that it would form multiple connected m circles, but it spread out and I couldn't roll it like that.
Furthermore, Cable A according to Comparative Examples 4 to 6, Cable B according to Comparative Examples 10 to 12, and Cable C according to Comparative Examples 16 to 18 had a strong tendency to wind around a diameter of 1.5 cm, and could only be wound with a winding diameter far below the above-mentioned numerical range (5.5±1.5 cm).

[Evaluation of maintenance of wound state after tensile test]
After the tensile test was carried out as described above, the cables according to Examples 1 to 9 were evaluated for their ability to maintain the wound state.
The maintenance of the wound state of each cable after the tensile test was evaluated by placing each cable after the tensile test on a flat plate, winding it into a shape of multiple circles with a diameter of 5.5±1.5 cm connected together (spiral shape), and measuring the length of the longest part of one turn (winding diameter) after 10 minutes.
The wound state was determined to be maintained when the length of the longest part of one turn (wound diameter) was within the range of 5.5±1.5 cm.
The results are shown in Table 5 below.

From Table 5, it can be seen that the winding diameter of all of the cables according to Examples 1 to 9 was within the range of 5.5±1.5 cm even after the tensile test, and the wound state was able to be maintained.

From the above results of the tensile test and the evaluation of the maintenance of the wound state, it can be seen that a cable having a core material whose outer circumference is coated with a resin composition containing polyvinyl chloride and whose outermost layer is constituted by the resin composition is wound around a cylindrical body, heated at an appropriate temperature for an appropriate period of time, and then cooled to room temperature, resulting in a cable that is easy to use both during storage and during use.

[Effect of heat treatment conditions on cable properties]
The effects of heat treatment conditions on the characteristics of three cables (Cable A, Cable B, and Cable C) were investigated, each of which has a core material made of a conductor (copper wire) (several conductors (copper wires) twisted together, each of which is coated with a resin composition) and is coated with a resin containing polyvinyl chloride.
The specimens used were cylindrical bodies having a diameter (outer diameter) of 3.8 cm and a height of 200 cm, with each of the above cables wound in a spiral shape with a pitch width of 0 mm around the outer circumference of the cylindrical bodies.
The heat treatment conditions are: in a heating furnace, temperature 30±1°C to 240±1°C, 10 to 210°C
The condition was that the samples would be processed separately.
After heating, each cable was cooled naturally in the heating furnace to room temperature (23±2° C.).
For each heat-treated specimen, the above-mentioned tensile test and evaluation of the maintenance of the wound state were carried out, and the evaluation was made according to the following criteria.

○ The length L2 after the weight is attached is in the range of 70 cm or more and 90 cm or less, and in the evaluation of the maintenance of the wound state, it is within the range of 5.5±1.5 cm for all five cycles.
x Either the length L2 after the weight is attached or the evaluation of the maintenance of the wound state does not meet the above criteria.

The results for Cable A are shown in Table 6 below, the results for Cable B are shown in Table 7 below, and the results for Cable C are shown in Table 8 below.

From Tables 6 to 8, it can be seen that for Cable A, Cable B, and Cable C,
It was found that by heating at a temperature of ±1°C or more and 120±1°C or less for 60 minutes or more, it was possible to obtain a cable with an evaluation result of ◯.
In addition, when the heating temperature was 30±1° C. and 60±1° C., the length L2 after the weight was attached exceeded the upper limit of the evaluation criteria of 90 cm.
Even when treated at 0±1° C. for 10 minutes and 30 minutes, the length L2 after the weight was attached exceeded the upper limit of the evaluation criteria of 90 cm, and the result was x.
In addition, when the temperature was 150±1°C to 240±1°C, the length after the weight was attached L
The length of cable 2 was less than the lower limit of the evaluation criteria, 70 cm, and was therefore rated as x. When treated at a temperature of 150±1°C to 240±1°C, part of the resin composition was melted, and the wrapped cables stuck together.
From these results, it was found that after a cable in which the outer circumference of a core material was covered with a resin composition containing polyvinyl chloride was wound around a cylindrical body and heated at a temperature of 89°C to 121°C for 60 minutes or more,
It was found that by cooling to room temperature, a cable that is easy to use during storage and use can be obtained.
Table 9 below shows the results of evaluation of the winding state maintenance of Cable A after heating at 90±1° C. for 60 to 210 minutes (the winding state maintenance in the above-mentioned 5 cycles). Table 10 shows the results of evaluation of the winding state maintenance of Cable B after heating at 90±1° C. for 60 to 210 minutes. Table 11 shows the results of evaluation of the winding state maintenance of Cable C after heating at 90±1° C. for 60 to 210 minutes. Table 12 shows the results of evaluation of the winding state maintenance of Cable A after heating at 120±1° C. for 60 to 210 minutes. Table 13 shows the results of evaluation of the winding state maintenance of Cable B after heating at 120±1° C. for 60 to 210 minutes.
The results are shown in Table 1, which shows the evaluation of the maintenance of the wound state of Cable C after heating at ±1° C. for 60 to 210 minutes.

[Effect of winding diameter on cable winding condition]
In order to examine the effect of the maximum length of the wound portion of the cable (winding diameter) on the winding state of the cable, samples for evaluating the maintenance of the winding state were obtained as follows.
First, two cables (Cable A, Cable B) each having a length of approximately 2 m (2 m ± 1 cm) and each having a core material made of a conductor (multiple conductors (copper wires) coated with a resin composition on the outer periphery) coated with a resin containing polyvinyl chloride were spirally wound with a pitch width of 0 mm around a cylindrical tube (diameter (outer diameter) 6.3 cm × height 200 cm) to obtain a tube with the cable wound thereon (hereinafter referred to as the tube with cable).
Next, these cylinders with the cables (the cylinder with cable A wound around it and the cylinder with cable B wound around it) were placed in a heating furnace and treated at 120° C.±1° C. for 60 minutes.
Next, these cylinders with the cables were naturally cooled to room temperature in a heating furnace to obtain specimens for evaluating the maintenance of the wound state. The maximum length of one turn (winding diameter) of each cable obtained by winding it around a cylinder with a diameter (outer diameter) of 6.3 cm and heat-treating it was 9.5±1.5 cm.
Both Cable A and Cable B had a circular cross-sectional shape.
In addition, in cable A, the thickness (outer diameter) of the core material was 3.5 mm, and the thickness of the coating was 0.35 mm, and in cable B, the thickness (outer diameter) of the core material was 3.9 mm, and the thickness of the coating was 0.35 mm .
The coating thickness of cables A and B was measured according to the method described in the embodiment section above.
The cable thicknesses of the cables A and B were measured according to the method described in the embodiment section above.

The maintenance of the wound state was evaluated for each cable after the tensile test.
In detail, after the tensile test, each cable was placed on a flat plate and subjected to a tensile test with a diameter of 9.5 ± 1.5 cm.
The wire was wound into a spiral shape with multiple 1.0 mm circles connected together, and 10 minutes later, the length of the longest part of one turn (winding diameter) was measured.
The wound state was determined to be maintained when the length of the longest part of one turn (wound diameter) was within the range of 9.5±1.5 cm.
The results are shown in Table 15 below.

From Table 15, it was found that the winding diameter of both Cable A and Cable B was within the range of 9.5±1.5 cm even after the tensile test, and the wound state was maintained, that is, the wound state was maintained regardless of the size of the winding diameter.

[Maintenance of the winding state of the cable when heated at a temperature of 80±1° C.]
Three samples of Cable B were obtained by heating at 80±1°C in the same manner as described in the tensile test section, except that the treatment temperature in the heating furnace was 80±1°C.
Then, for each cable after the tensile test, the maintenance of the wound state was evaluated. More specifically, each cable after the tensile test was placed on a flat plate and wound in a size of 5.5 cm±1.
The test was performed by winding the material into a spiral shape with multiple 5 cm circles connected together, and measuring the length of the longest part of one turn (winding diameter) 10 minutes later.
The wound state was determined to be maintained when the length of the longest part of one turn (wound diameter) was within the range of 5.5±1.5 cm.
The results are shown in Table 16 below.

From Table 16, it can be seen that the winding diameter of Cable B was within the range of 5.5±1.5 cm even after the tensile test, and the wound state was maintained. In other words, it was possible to obtain a cable that could maintain its wound state even when the heating temperature was 80° C.

S1 winding process, S2 heating process, S3 cooling process.

Claims (2)

a winding step of winding a cable, in which an outer periphery of a core material made of a linear conductor is covered with a resin composition containing polyvinyl chloride and an outermost layer is formed of the resin composition, around a cylindrical body;
a heating step of heating the cable wound around the cylindrical body for 60 minutes or more while maintaining the temperature within a range of 79° C. to 121° C.;
and a cooling step of cooling the heated cable to a temperature within a range of 9°C to 36°C while the cable is wound around the cylindrical body,
The cable has a winding diameter of 5.5±1.5 cm;
The cable is used to connect a smartphone.
How the cable is manufactured. The method for producing a cable according to claim 1 , wherein the coating thickness of the resin composition is 0.2 mm or more and 0.7 mm or less.