JP6146338B2 - Electric wire / cable manufacturing method - Google Patents

Description

The present invention relates to the production how the wires and cables.

  Insulation wire / cable coating materials include vulcanization methods such as fluidized bed method, hot air crosslinking method, electron beam irradiation method, molten salt method, pressurized steam method, high-frequency vulcanization method, lead, There is a batch vulcanization method in which polymethylpentene (TPX: registered trademark) or the like is coated, wound on a drum, and then vulcanized in a can. These vulcanization methods are selected and applied according to the thickness, shape, structure, length, type of coating material, etc. of the object. There are advantages and disadvantages in terms of performance, product performance, etc.

  Among the continuous vulcanization methods, the fluidized bed method and the hot air cross-linking method are methods of heating and vulcanizing an object to be vulcanized through a pipe heated to a high temperature under normal pressure. The former has glass beads, but has the disadvantage that the heat transfer characteristics to the object to be vulcanized are inferior and the manufacturing speed is slow because air heat transfer is the main component.

  The electron beam irradiation method has a limitation on the penetration thickness into the material depending on the intensity of the electron beam, and is generally more suitable for manufacturing a thin insulated wire than a thick product. Furthermore, since the extrusion process and the irradiation process are separate processes, it is necessary to take up the drum once. In that case, the unvulcanized coating material is subject to deformation, so the insulating material is difficult to deform at room temperature. It is limited to.

  The molten salt method of vulcanizing an inorganic salt (for example, TOREC: a mixture of potassium nitrate, sodium nitrate, and sodium nitrite) in a molten high-temperature liquid can be vulcanized under both normal pressure and pressure, but the salt is heated. -It takes a long time to melt, or it needs to be heated for a long time in order to prevent it from being cooled and solidified once melted, and requires a large amount of electric power. Furthermore, after vulcanization, it is necessary to wash the salt adhering to the vulcanized object with water, and this water treatment is necessary.

  The pressurized steam method has a high production speed as a vulcanization method for a long vulcanization object, and is often used for vulcanization of electric wires, cables and the like. There is not much problem with an insulated wire, but since a high pressure is applied during vulcanization, a cable has problems of deformation of the rubber coating layer itself, deformation due to a recess in the core of the rubber coating layer, and deformation of the insulator itself.

  In order to avoid this problem, there is a can vulcanization method in which the temperature is somewhat low and high pressure is not applied.

  However, in this method, immediately after extrusion, in order to suppress the deformation of the rubber material that occurs during drum winding before vulcanizing the can, after extrusion, lead, polymethylpentene (TPX: registered trademark), etc. are once coated and vulcanized, This involves a troublesome process such as peeling them, and requires a long time for production. Moreover, even if the coating for suppressing deformation is performed, since the suppression is insufficient, there is a step of repairing the deformation after crosslinking, and there is a problem that the manufacturing cost is high. Furthermore, the covering process applicable to the deformation suppression of the round cable cannot be applied to the case of the flat cable, and the deformation repairing process after the bridge has been indispensable.

  On the other hand, superheated steam is steam heated to 100 ° C. or higher under atmospheric pressure, and has existed for a long time, but has only been applied as power rather than heat. Recently, application to the field of food preparation has been reviewed, and microwave ovens with superheated steam have been marketed by various manufacturers.

  In Patent Documents 1 to 3, it is proposed to vulcanize rubber or thermoplastic resin using superheated steam.

Superheated steam has the following characteristics.
(1) Since the heat capacity is larger than that of heated air, the object to be heated can be heated rapidly, and the heating time can be shortened.
(2) It has a constant-pressure specific heat of about twice that of heated air and has excellent heating capacity.
(3) Since it has latent heat energy, its enthalpy is larger than that of heated air.
(4) Heat transfer by air is limited to convection heat transfer, but superheated steam has good thermal efficiency due to “composite heat transfer action” that transfers heat by radiant heat and condensation heat transfer in addition to convective heat transfer.
(5) Since the amount of water per unit volume is smaller than that of saturated water vapor, it has both wet heat and dry heat properties.

  There are two methods for generating superheated steam: electric heater and electromagnetic induction heating. The superheated steam condenses when it hits an object of 100 ° C. or less, water droplets are generated on this surface, and it re-evaporates due to the presence of the superheated steam. As a result of stagnation for a while, a certain time is required until the temperature rises to 100 ° C. or higher.

  As a well-known example of applying superheated steam to the manufacture of insulated wires and cables, it is possible to coat polymers and rubber materials extruded at a temperature of 80 ° C or higher by continuous heating and vulcanization with superheated steam under pressure. It is possible to prevent the material from foaming and to heat and vulcanize insulated wires / cables continuously by using superheated steam as a heat medium under low pressure (0.2 MPa or more) without deforming the insulator. There is a sulfur method (see Patent Document 4).

JP 2001-239528 A Japanese Patent Laid-Open No. 2001-323085 Japanese Patent Laid-Open No. 2004-50615 JP 2011-5852 A

  However, in the method described in Patent Document 4, since it is continuously heated and vulcanized with superheated steam under pressure (0.2 MPa or more), there is room for improvement in terms of the deformation rate of the rubber coating layer by the crosslinking treatment. there were. In addition, in the method of applying a covering material such as lead or TPX in order to suppress deformation of the rubber coating layer as in conventional can vulcanization, there is a step of winding the rubber before cross-linking onto the drum. It was necessary to improve the deformation rate of the rubber coating layer at the time.

Therefore, an object of the present invention is to reduce the manufacturing cost and to form a rubber coating layer during crosslinking and a rubber during drum winding without coating a material for suppressing deformation of the rubber material immediately after extrusion. the deformation of the covering layer is to provide a manufacturing how the suppressible wires and cables.

To achieve the above object, according to the present invention, the following wires and cables manufacturing how is provided.

[1] including a step of coating a rubber material on a core material by an extruder to obtain a coating, and a step of crosslinking the coated rubber material by passing the coating through a crosslinking facility connected to the extruder. The method for producing an electric wire / cable is characterized in that the cross-linking step is performed by supplying superheated steam of 100 to 180 ° C. and normal pressure to less than 0.2 MPa to the cross-linking facility.
[2] The method for manufacturing an electric wire / cable according to [1], wherein the crosslinking step is performed for longer than 3 minutes.
[3] The method for producing an electric wire / cable according to [1] or [2], wherein the cross-linking step is performed by supplying superheated steam at normal pressure.
[4] The method for manufacturing an electric wire / cable according to any one of [1] to [3], wherein in the step of crosslinking, the crosslinking facility is heated from the outside .

According to the present invention, it is possible to reduce the manufacturing cost, and without covering the material for suppressing the deformation of the rubber material immediately after the extrusion, the deformation of the rubber coating layer at the time of crosslinking and the rubber coating layer at the time of winding the drum producing how the suppressible wire and cable deformation is provided.

It is a cross-sectional view of the cable which concerns on the reference form of this invention. It is a figure which shows the outline of the process of the manufacturing method of the electric wire and cable which concerns on embodiment of this invention. It is a figure which shows the outline of the process of the manufacturing method of the electric wire and cable which concerns on other embodiment of this invention.

  A preferred embodiment of the present invention will be described below in detail with reference to the accompanying drawings.

FIG. 1 is a cross-sectional view of a cable according to a reference embodiment of the present invention. For example, an electric wire 10 in which an insulator 2 made of EPR (ethylene propylene rubber) or the like is coated on a conductor 1 made of copper is formed, three wires 10 are twisted, and a sheath 3 made of polychloroprene or the like is formed on the outer periphery thereof. Is covered to form the cable 100.

[Manufacturing method of electric wire / cable]
FIG. 2 is a diagram showing an outline of the steps of the method of manufacturing the electric wire / cable according to the embodiment of the present invention, and mainly shows the step of bridging the rubber material constituting the insulator and the sheath of the electric wire 10 and the cable 100. It is a thing.

  The method of manufacturing an electric wire / cable according to an embodiment of the present invention includes a step of coating a rubber material on a core material by an extruder to obtain a coating, and passing the coating through a crosslinking facility connected to the extruder, Cross-linking the coated rubber material, and the cross-linking step is carried out by supplying superheated steam at 100 ° C. or higher and lower than 180 ° C. and from normal pressure to less than 0.2 MPa to the cross-linking facility. Features.

  First, the rubber material is extruded from the extruder 20 to the die 21, and the core material 23 such as a conductor or an electric wire is fed from the core feeder 22 so as to pass through the die 21, and the rubber material is extruded onto the core material 23. Is done. Thereafter, the coating is sequentially passed through a splice box 24 and a superheated steam bridge facility 25. Superheated steam is supplied from the superheated steam supply device 26 in the superheated steam crosslinking facility 25 to crosslink the extruded coating material. The product 30 (the electric wire 10 and the cable 100) after the crosslinking is cooled through the water-cooled tube 27, passes through the water seal 28, and is wound around the product winder 29.

  The superheated steam supplied from the superheated steam supply device 26 to the superheated steam bridge facility 25 is supplied from at least one location of the superheated steam bridge facility 25. In FIG. 2, it supplies from three places, the entrance part of the superheated steam bridge | crosslinking facility 25, an intermediate part, and an exit part. In addition, a pressure regulating valve 31 is connected to the superheated steam bridge facility 25, and the pressure regulating valve 31 holds the pressure in the superheated steam bridge facility 25 from normal pressure (about 0.1 MPa) to less than 0.2 MPa. Is done. Preferably, the pressure is maintained from normal pressure to 0.17 MPa or less, more preferably from normal pressure to 0.15 MPa or less, and even more preferably from normal pressure to 0.13 MPa or less. Retained. Most preferably, it is maintained at normal pressure.

  The superheated steam is heated from normal pressure to less than 0.2 MPa, and most preferably under normal pressure, so that no high pressure is applied during crosslinking, and the rubber material covered with the cable is not deformed. In addition, as described in the background art, since the object to be heated can be heated rapidly, the rubber material coated on the cable can be cross-linked in a short time. It is possible to suppress deformation due to its own weight.

  The temperature in the crosslinking equipment 25 is preferably maintained at 100 ° C. or more and less than 180 ° C., more preferably 140 ° C. or more and less than 180 ° C., most preferably 150 in consideration of productivity and thermal degradation of the rubber material. It is preferable to hold at a temperature not lower than 180 ° C. and lower than 180 ° C.

  In consideration of the thickness of the coating material (about 1 to 10 mm), the crosslinking time is preferably longer than 3 minutes. It is more preferably from 3.5 minutes to 10 minutes, further preferably from 4 minutes to 8 minutes, and most preferably from 4 minutes to 6 minutes. However, a material having a different crosslinking system such as silane crosslinking or a product having a thick coating material may require further crosslinking time, and the specific crosslinking time is not limited to this range.

  FIG. 3 is a diagram showing an outline of the steps of a method of manufacturing an electric wire / cable according to another embodiment of the present invention, which is basically the same as FIG. 2, but heated to the outer periphery of the superheated steam bridge facility 25. An external heater 32 is provided as an apparatus, and superheated steam from the superheated steam supply device 26 is supplied from two locations, an inlet portion and an intermediate portion of the superheated steam bridge facility 25.

  In the above, the wire / cable coating material is extruded from the extruder 20 and coated on the core material 23 with the die 21, and in the superheated steam bridging equipment 25, the superheated steam of less than 0.2 MPa is heated from normal pressure. It is continuously heated as a medium, and the coating material is crosslinked.

  When the extrusion temperature in the extruder 20 is 80 ° C. or higher, the superheated steam is touched with the coating material in the superheated steam crosslinking facility 25, is cooled, becomes water, and can be kept for a short time as much as possible. . As a result, the time during which the temperature rise of the covering material remains at 100 ° C. can be minimized.

  In addition, by heating the coating material with atmospheric superheated steam less than 0.2 MPa, deformation of the material at the time of crosslinking can be prevented.

  When the superheated steam comes into contact with the object to be heated, it has the property of dew condensation (steam liquefaction) and the temperature tends to stay at 100 ° C. Therefore, by extruding the material at a temperature of 80 ° C. or higher, the stagnation time at 100 ° C. due to dew condensation of superheated steam can be shortened. As a result, the progress of crosslinking can be accelerated. In addition, at 80 ° C. or lower, the stagnation time at 100 ° C. becomes longer, and the progress of the crosslinking becomes slower, so that the productivity is inferior.

  The superheated steam has a property of returning to 100 ° C. with time, and when the superheated steam crosslinking facility 25 is long, there is a risk of causing a temperature drop on the way. In order to prevent this, the following method is taken.

  One is a method for increasing the supply amount of superheated steam, and the second is a method for preventing a decrease in temperature by providing superheated steam not only at one place but also at a plurality of places as shown in FIGS. The third is a method of heating a part of the crosslinking equipment from the outside with a heating device (heater or the like) as shown in FIG.

  Although it depends on the size structure of the electric wire / cable, by combining these alone or in combination, it is possible to prevent the temperature inside the crosslinking facility from being lowered, and the crosslinking reaction of the coating material can proceed smoothly.

  Since the superheated steam is most preferably used under normal pressure, the superheated steam supply device 26 does not need to be pressurized and equipment costs can be reduced.

  It is desirable to attach a guide roll or the like to the bottom of the superheated steam crosslinking facility 25 in order to prevent deformation and scratches on the uncrosslinked coating material.

  Rubber materials include natural rubber (NR), isoprene rubber (IR), butyl rubber (IIR), ethylene / propylene rubber (EPR), ethylene / propylene / diene terpolymer (EPDM), butadiene rubber (BR), and styrene butadiene rubber. (SBR), acrylonitrile butadiene rubber (NBR), polychloroprene rubber (CR), chlorinated polyethylene (CPE), chlorosulfonated polyethylene (CSM), fluoro rubber (FKM), acrylic rubber (ACM), epichlorohydrin rubber ( Examples thereof include rubber materials such as ECO), silicone rubber (VMQ), and various liquid rubbers. These may be added with general compounding agents such as a crosslinking agent, a plasticizer, a lubricant, a filler, a flame retardant and a colorant.

  The target products are electric wires (insulated electric wires) and cables, but there are solid extrusion moldings and hoses including irregular shapes as deformations. The latter two are particularly suitable for a structure including a type in which a linear metal wire, metal, or natural / synthetic polymer yarn is knitted inside.

  The molding temperature of the extruder 20 is preferably 80 ° C. or higher and 100 ° C. or lower. If the extrusion temperature is higher than this, pre-crosslinking before cross-linking with superheated steam proceeds too much, resulting in a partial increase in viscosity and appearance defects such as “crushing” and “blowing”.

  Although not shown, before and after the extruder 20, necessary equipment such as a core wire, a core feeding machine, an accumulator thereof, a product winder, an outer diameter measuring instrument, and an accumulator can be provided.

[Wire / Cable]
The electric wire and cable which concern on the reference form of this invention are manufactured by the said manufacturing method which concerns on embodiment of this invention .

The wire / cable coating layer (rubber material) according to the reference embodiment of the present invention is a load test (40 ° C., 700 g / cm ² for 24 hours) using a heat deformation tester based on ASTM D621 (compression creep test method). The compression deformation rate (permanent deformation) at the time of drum winding is 3% or less. In a preferred reference embodiment, the compression deformation rate is 2.5% or less, in a more preferred reference embodiment, the compression deformation rate is 2% or less, and in a more preferred reference embodiment, the compression deformation rate is 1 and at .5% or less, in a most preferred reference embodiment, the pressure change rate is 1% or less. Moreover, the thickness deformation rate at the time of bridge | crosslinking of the said coating layer is also 3% or less. In a preferred reference form, the thickness deformation rate is 2.5% or less, in a more preferred reference form, the thickness deformation rate is 2% or less, and in a most preferred reference form, the thickness deformation rate is 1 .5% or less.

  Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited thereto.

  A cable 100 having the structure shown in FIG. 1 was produced by the following method.

Here, the size of each part of the cable 100 (electric wire 10: 3 pieces × 22 mm 2) is as follows.
Conductor configuration (outer diameter / number of strands / strand diameter): 7 mm / 20 strands / 0.45 mm
Insulator thickness: 1.2mm
Sheath thickness: 2.7 mm
Finished outer diameter: 26mm

  The insulator was obtained by extrusion-coating sulfur vulcanized EPR (each color of red, white, and black) to a predetermined thickness on a conductor and then crosslinking with superheated steam.

  After twisting these three, the sheath material containing polychloroprene shown in Table 1 was extrusion coated at a speed of 5 m / min and 10 m / min by a 90 mm vent type extruder.

  Next, crosslinking was performed under the conditions shown in Table 2 to obtain a cable product (3 PNCT: 3 types of EP rubber-insulated chloroprene cabtyre cable).

  The thickness of the sheath material of the cable before and after cross-linking was compared to evaluate the deformation rate during cross-linking. Also, the sheath material of the cable immediately before winding of the drum (winding machine 29) is collected, cut into a thickness of 2 mm from the surface, and processed into a sheet of 10 mm × 10 mm × 2 mm, and compressed when winding the drum It used for the measurement of a deformation rate.

  Table 2 shows production conditions and evaluation results of Examples 1 to 3 and Comparative Examples 1 to 2 and lead can vulcanized standard products.

  The deformation rate at the time of cross-linking and drum winding was set to a standard value ≦ 3%, and other than that, it was compared with the value of the product obtained under the standard conditions of lead can vulcanization, and comprehensive judgment was made.

  The evaluation method of each characteristic is as follows.

(1) Thickness deformation rate during crosslinking:
The cross section of the sheath of the cable before and after crosslinking was observed with a microscope, and the change in sheath thickness was measured. The same applies to lead can vulcanized standard products. The thickness deformation rate was calculated by the following formula.

  Thickness deformation rate (%) = [{Sheath thickness before crosslinking−Sheath thickness after crosslinking} / {Sheath thickness before crosslinking}] × 100

(2) Compression deformation rate during drum winding:
Based on ASTM D621 (compression creep test method), the sample was loaded for 24 hours under conditions of 40 ° C. and 700 g / cm ^{2 using} a “heat deformation tester”, and then the load was removed and the room was 23 ° C. and 50 RH%. The sheet thickness after storage for 24 hours was measured, and the compression deformation rate (permanent deformation) with respect to the initial sheet thickness was evaluated. The temperature condition (40 ° C.) was selected from the on-site temperature in summer. Further, the surface pressure condition (700 g / cm ² ) was estimated from the load applied to the lowermost cable in a state where all the product cables were wound around the drum and the area when the cable diameter was deformed by 10%. The compression deformation rate was calculated by the following formula.

  Compression deformation rate (%) = [{initial sheet thickness−sheet thickness after 24 hours of unloading} / {initial sheet thickness}] × 100

(3) Manufacturing cost:
The manufacturing cost is equivalent to the manufacturing cost of lead can vulcanized standard products x (failed), less than 10% cost reduction rate △ (passed), 10% or more cost reduction rate ○ (passed).

  In Examples 1 to 3, the sheath material (CR-1, CR-2) is a standard polychloroprene rubber, and after extrusion coating, is crosslinked with superheated steam adjusted to 150 ° C. under a pressure close to normal pressure. Therefore, the thickness deformation rate after passing through the bridge equipment and the compression deformation rate when winding the drum satisfy the standard value (≦ 3%), and the manufacturing cost is higher than the product obtained by conventional lead can vulcanization. Are better. Therefore, all of Examples 1 to 3 passed the comprehensive judgment.

  On the other hand, since the comparative example 1 does not perform the superheated steam treatment, it does not have any deformation resistance at the time of winding the drum, and the deformation rate is as extremely high as 22.3%. Therefore, the comprehensive judgment was unacceptable.

  Moreover, since the pressure of the superheated steam is 0.2 MPa in Comparative Example 2, the uncrosslinked sheath material is deformed (deformation rate: 3.2%). Moreover, since it is the equipment of a pressurization specification, a manufacturing cost will also become high compared with the case of normal pressure use. Furthermore, since the deformation rate is 3% or more and a deformation repair cost is required, the manufacturing cost increases. Therefore, the comprehensive judgment was unacceptable.

  Since the conventional lead can vulcanized standard product does not include a crosslinking step before winding the drum, the sheath material itself has no deformation resistance and the deformation rate is 20.8%. Moreover, since the manufacturing cost is the same as before, it is x (failed). Therefore, the comprehensive judgment was unacceptable.

  From the above, after extruding the rubber material, it is cross-linked with superheated steam at 100 ° C. or higher and lower than 180 ° C. and from atmospheric pressure to less than 0.2 MPa, so that there is no deformation during the cross-linking, and no deformation due to its own weight when winding the drum. A cable having deformation resistance and a low manufacturing cost can be obtained.

  In the above embodiments, the cable sheath material has been described. However, the present invention can be applied to various products in addition to the sheath material, for example, solid extrusions including different shapes, and hoses.

DESCRIPTION OF SYMBOLS 1: Conductor, 2: Insulator, 3: Sheath 10: Electric wire, 100: Cable 20: Extruder, 21: Die, 22: Core delivery machine 23: Core material, 24: Splice box 25: Superheated steam bridge equipment (superheat Steam vulcanization pipe)
26: superheated steam supply device 27: water cooling pipe, 28: water seal, 29: winder 30: product after crosslinking, 31: pressure regulating valve, 32: external heater

Claims (4)

  A step of coating a rubber material on a core material by an extruder to obtain a coating; and a step of cross-linking the coated rubber material by passing the coating through a crosslinking facility connected to the extruder. The electric wire / cable manufacturing method is characterized in that the step of performing is performed by supplying superheated steam at 100 ° C. or higher and lower than 180 ° C. to normal pressure to less than 0.2 MPa.   The method of manufacturing an electric wire / cable according to claim 1, wherein the cross-linking step is performed for longer than 3 minutes. Wherein the step of crosslinking, wire and cable manufacturing method according to claim 1 or claim 2 superheated steam at atmospheric pressure, characterized in that the performed supplied.   The method of manufacturing an electric wire / cable according to any one of claims 1 to 3, wherein in the cross-linking step, the cross-linking facility is heated from the outside.

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