JP2012018810A - Rubber coated wire and manufacturing method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rubber coated wire which can sufficiently prevent the deterioration in adhesion between an insulation layer and a sheath layer even when used underwater and has excellent flame retardancy, and also to provide a manufacturing method of the rubber coated wire.SOLUTION: A rubber coated wire 10 comprises: a core 2 including a conductor 1; and a rubber coating layer 3 coating the core 2. The rubber coating layer 3 has an insulation layer 3a and a sheath layer 3b which is arranged to cover the insulation layer 3a. The rubber coating layer 3 is obtained by sequentially extrusion-coating an unvulcanized insulation layer made of an insulation-layer forming composition which forms the insulation layer 3a and an unvulcanized sheath layer made of a sheath-layer forming composition which forms the sheath layer 3b, and then collectively vulcanizing both layers. The insulation-layer forming composition contains a vulcanizing agent and a resin containing ethylene propylene rubber. The sheath-layer forming composition contains the vulcanizing agent and a resin containing chloroprene rubber and ethylene propylene rubber. When assuming that the total mass of the rubber in the sheath-layer forming composition is 100 pts.mass, then the ethylene propylene rubber is mixed at a ratio of 15-42 pts.mass.

Description

  The present invention relates to a rubber-coated electric wire and a method for producing the same.

  Since chloroprene rubber is excellent in weather resistance, flame retardancy, oil resistance, and chemical resistance, it may be used as a sheath layer for rubber-coated wires. However, chloroprene rubber has a drawback of poor electrical insulation. For this reason, in a rubber-coated electric wire, in order to compensate for the disadvantages of chloroprene rubber, an inner layer of chloroprene rubber is made of ethylene propylene rubber (hereinafter referred to as “EP rubber”) having excellent electrical insulation. An insulating layer is disposed. In such a rubber-coated electric wire, it is important to improve the adhesion between the sheath layer and the insulating layer in order to prevent deterioration of electrical characteristics.

  As means for improving the adhesion between the sheath layer and the insulating layer inside the rubber-coated electric wire, one disclosed in Patent Document 1 below is known. In Patent Document 1 below, by applying process oil on an insulating layer covering a conductor and forming a sheath layer made of chloroprene rubber thereon, the adhesion between the insulating layer and the sheath layer is improved. Is disclosed.

Japanese Unexamined Patent Publication No. 7-85740 (paragraph 0004)

  However, the rubber-coated wire described in Patent Document 1 has the following problems.

  That is, in the above rubber-coated electric wire, when the rubber-coated electric wire is used in water, it cannot be said that the adhesion between the insulating layer and the sheath layer is still sufficient. For this reason, when a rubber-coated wire is used underwater as a cable for an underwater lamp, as the water depth increases, water enters between the insulating layer and the sheath layer from the end of the rubber-coated wire, and this water The sheath layer may be peeled from the insulating layer, and as a result, the electrical characteristics of the rubber-coated wire may be deteriorated.

  The rubber-coated wire is also required to have flame retardance from the viewpoint of preventing ignition due to heat generation.

  The present invention has been made in view of the above circumstances, and a rubber-coated electric wire that can sufficiently prevent a decrease in adhesion between an insulating layer and a sheath layer even when used in water and has excellent flame retardancy, and its manufacture It aims to provide a method.

  In order to solve the above-mentioned problems, the present inventor has conducted extensive research focusing on vulcanization treatment generally performed to improve elasticity and strength of chloroprene rubber and EP rubber. As a result, chloroprene rubber and EP rubber are There is a difference in the vulcanization speed, and the difference in the vulcanization speed makes it difficult for vulcanization to occur at the interface between the sheath layer made of chloroprene rubber and the insulating layer made of EP rubber. It was thought that the above-mentioned problem might occur because sufficient vulcanization could not be performed between the two. Therefore, as a result of further earnest research, the present inventors have found that the above problem can be solved by blending EP rubber in a predetermined ratio based on the total weight of chloroprene rubber and EP rubber in the sheath layer. The present invention has been completed.

  That is, the present invention includes a core portion including a conductor and a rubber coating layer covering the core portion, and the rubber coating layer covers the insulating layer disposed on the core portion side and the insulating layer. A non-vulcanized insulating layer made of an insulating layer forming composition for forming the insulating layer on the core part, and a rubber-coated electric wire having a sheath layer provided as described above, It is obtained by sequentially extruding and coating an unvulcanized sheath layer made of a composition for forming a sheath layer to form a sheath layer, and collectively vulcanizing the unvulcanized insulating layer and the unvulcanized sheath layer. The insulating layer forming composition contains a resin containing an EP rubber and a vulcanizing agent, and the sheath layer forming composition contains a resin containing a chloroprene rubber and an EP rubber and a vulcanizing agent, The chloroprenego in the composition for forming a sheath layer And the EP rubber on the total weight of the EP rubber is 100 parts by mass is rubber coated electric wire that is in a proportion of 15 to 42 parts by weight.

  Even if this rubber-coated electric wire is used in water, it is possible to sufficiently prevent a decrease in adhesion between the insulating layer and the sheath layer, and thus it is possible to sufficiently prevent delamination. The rubber-coated electric wire of the present invention also has excellent flame retardancy.

  About this reason, this inventor has guessed as follows. That is, when the total weight of chloroprene rubber and EP rubber in the composition for forming a sheath layer is 100 parts by mass, EP rubber is contained in a proportion of 15 to 42 parts by mass. When the forming composition is sequentially extrusion coated onto the core portion and batch-cured, the EP rubber in the sheath layer forming composition and the EP rubber in the insulating layer forming composition are chemically treated by vulcanization. To join. For this reason, the adhesion between the sheath layer and the insulating layer is improved, the rubber-coated electric wire is used in water, and even if water enters between the insulating layer and the sheath layer from the end of the rubber-coated electric wire, This water does not reach the point where the sheath layer is peeled off from the insulating layer. That is, according to the present invention, it is possible to sufficiently prevent delamination of the insulating layer and the sheath layer even when used in water. Further, in the present invention, the content of EP rubber in the rubber component contained in the composition for forming a sheath layer is suppressed to a low level, and chloroprene rubber excellent in flame retardancy remains in a high proportion in the composition for forming a sheath layer. Yes. As a result, the inventor presumes that the rubber-coated wire of the present invention has excellent flame retardancy.

  The present invention also includes a rubber coating layer forming step of forming a rubber coating layer that covers the core portion including the conductor, and the rubber coating layer covers the insulating layer disposed on the core portion side and the insulating layer. A non-vulcanized product comprising a composition for forming an insulating layer, wherein the rubber covering layer forming step forms the insulating layer on the core portion. An unvulcanized rubber-coated electric wire forming step of sequentially forming an unvulcanized rubber-coated electric wire by extruding and coating an insulating layer and an unvulcanized sheath layer made of a composition for forming a sheath layer to form the sheath layer; A vulcanization step of collectively vulcanizing the unvulcanized insulating layer and the unvulcanized sheath layer of the unvulcanized rubber-coated electric wire, and the vulcanization step includes the unvulcanized rubber-coated electric wire in a vulcanized tube. And an inert gas is introduced into the vulcanized pipe, and the inert gas is introduced. And vulcanizing the unvulcanized insulating layer and the unvulcanized sheath layer of the unvulcanized rubber-coated electric wire while pressurizing the unvulcanized rubber-coated electric wire, and the composition for forming an insulating layer comprises: A resin containing EP rubber and a vulcanizing agent, and the composition for forming a sheath layer contains a resin containing chloroprene rubber and EP rubber and a vulcanizing agent, and the composition in the composition for forming a sheath layer This is a method for producing a rubber-coated wire in which the EP rubber is blended at a ratio of 15 to 42 parts by mass when the total mass of the chloroprene rubber and the EP rubber is 100 parts by mass.

  According to this manufacturing method, even when used in water, it is possible to obtain a rubber-coated electric wire that can sufficiently prevent a decrease in adhesion between the insulating layer and the sheath layer and has excellent flame retardancy.

  ADVANTAGE OF THE INVENTION According to this invention, even if it uses it in water, the fall of the adhesiveness of an insulating layer and a sheath layer can fully be prevented, and the rubber-coated electric wire which has the outstanding flame retardance, and its manufacturing method are provided.

It is sectional drawing which shows one Embodiment of the rubber-coated electric wire of this invention.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to FIG.

[Rubber coated wire]
FIG. 1 is a cross-sectional view showing an embodiment of a rubber-coated wire according to the present invention. As shown in FIG. 1, the rubber-coated electric wire 10 includes a core portion 2 made of an internal conductor 1 and a rubber coating layer 3 that covers the core portion 2. Here, the rubber coating layer 3 has an insulating layer 3a disposed on the core portion 2 side and a sheath layer 3b provided so as to cover the insulating layer 3a.

  The rubber-coated wire 10 is obtained as follows.

[Rubber coating layer forming step]
First, a rubber coating layer 3 that covers the core portion 2 made of the internal conductor 1 is formed.

  Here, the inner conductor 1 may be composed of only one strand, or may be composed of a plurality of strands bundled together. Further, the inner conductor 1 is not particularly limited with respect to the conductor diameter, the material of the conductor, and the like, and can be appropriately determined according to the application.

  The rubber coating layer 3 is obtained as follows.

<Unvulcanized rubber covered wire forming process>
First, an unvulcanized insulating layer made of a composition for forming an insulating layer containing EP rubber and forming an insulating layer 3a on the core 2 and a composition for forming a sheath layer forming a sheath layer 3b containing chloroprene rubber. The unvulcanized sheath layer is sequentially extrusion coated to form an unvulcanized rubber-coated electric wire.

(Insulating layer forming composition)
The composition for forming an insulating layer contains a resin containing EP rubber and a vulcanizing agent.

  The content of EP rubber in the resin is preferably 40% by mass or more, and more preferably 100% by mass. The EP rubber may be either EPM (Ethylene-Propylene Methylene linkage) which is a copolymer of ethylene and propylene or EPDM (Ethylene-Propylene Diene Methylene linkage) which is a copolymer of ethylene, propylene and a non-conjugated diene monomer. . These may be used individually by 1 type, and 2 or more types may be mixed and used for them. As the non-conjugated diene monomer, for example, 1,4-hexadiene, dicyclopentadiene, 5-ethylidene-2-norbornene and the like can be used.

  The vulcanizing agent may be sulfur or an organic peroxide. As the organic peroxide, for example, an acyl peroxide can be used.

  In addition, the composition for insulating layer formation may contain additives, such as an inorganic filler, carbon black, a vulcanization accelerator, a lubricant, a softening agent, and an antioxidant, as needed.

(Sheath layer forming composition)
The composition for forming a sheath layer contains a resin containing chloroprene rubber and EP rubber and a vulcanizing agent.

  The content of chloroprene rubber and EP rubber in the resin is preferably 47% by mass or more, and more preferably 100% by mass.

  As the EP rubber, the same rubber as the EP rubber used in the composition for forming an insulating layer can be used.

  When the total mass of chloroprene rubber and EP rubber is 100 parts by mass, the EP rubber is blended at a rate of 15 to 42 parts by mass. When the EP rubber is blended at a ratio of less than 15 parts by mass, the adhesion between the insulating layer 3a and the sheath layer 3b is remarkably lowered, and when the rubber-coated wire 10 is used in water, the sheath layer 3b becomes the insulating layer 3a. Peels off, and the electrical properties deteriorate. On the other hand, when the EP rubber exceeds 42 parts by mass, flame retardancy and oil resistance are significantly reduced.

  It is preferable that EP rubber is 15-25 mass parts on the basis of 100 mass parts of total mass of chloroprene rubber and EP rubber.

  As the vulcanizing agent, a mixture of sulfur or an organic peroxide and a metal oxide is used.

  The composition for forming a sheath layer can be obtained, for example, by mixing a chloroprene rubber component containing chloroprene rubber and a vulcanizing agent and an EP rubber component containing EP rubber and a vulcanizing agent.

  The vulcanizing agent in the EP rubber component may be the same as the vulcanizing agent in the insulating layer forming composition.

  A metal oxide is usually used as a vulcanizing agent in the chloroprene rubber component. This is due to the following reason. That is, the metal oxide easily desorbs hydrogen chloride when vulcanizing chloroprene containing a chlorine atom in its molecular chain and easily captures hydrogen chloride as an acid acceptor. As the metal oxide, for example, zinc white or magnesium oxide can be used. The vulcanizing agent preferably has the same vulcanization rate (time) as the vulcanizing agent used in the insulating layer forming composition. In this case, the adhesion between the insulating layer 3a and the sheath layer 3b can be further improved by matching the vulcanization speed (time).

  In addition, the composition for forming a sheath layer may contain additives such as an inorganic filler, carbon black, a vulcanization accelerator, a lubricant, a softener, and an anti-aging agent as necessary.

<Vulcanization process>
Next, the unvulcanized insulating layer and the unvulcanized sheath layer of the unvulcanized rubber-coated electric wire are vulcanized together. Thus, the rubber coating layer 3 composed of the insulating layer 3a and the sheath layer 3b is formed.

  At this time, the unvulcanized rubber-coated electric wire is accommodated in the vulcanized tube, an inert gas is introduced into the vulcanized tube, and the unvulcanized rubber-coated electric wire is pressurized with the inert gas while being pressurized. The unvulcanized insulating layer and the unvulcanized sheath layer are vulcanized together.

  Examples of the inert gas include helium gas and nitrogen gas, and nitrogen gas is preferably used. Since the inert gas keeps the inside of the vulcanized tube in an inert atmosphere and sufficiently suppresses the oxidation of the unvulcanized insulating layer and the unvulcanized sheath layer, it can be continuously circulated in the vulcanized tube. preferable.

  The pressurization of the unvulcanized rubber-coated electric wire is usually performed at a pressure of 0.3 to 0.6 MPa.

  The temperature of vulcanization is usually selected in the range of 160 to 350 ° C., preferably in the range of 200 to 350 ° C., depending on the vulcanizing agent in the insulating layer forming composition and the sheath layer forming composition. The

  The vulcanization time is usually selected in the range of 1 to 40 minutes, preferably in the range of 1 to 15 minutes, depending on the vulcanizing agent in the insulating layer forming composition and the sheath layer forming composition. The

  Thus, the rubber-coated electric wire 10 is obtained.

  The rubber-coated electric wire 10 obtained as described above can sufficiently prevent a decrease in adhesion between the insulating layer and the sheath layer even when used in water and has excellent flame retardancy.

  The present invention is not limited to the above embodiment. For example, in the said embodiment, although the core part 2 consists of the internal conductor 1, the core part 2 may contain the internal conductor 1 and the insulator which coat | covers the internal conductor 1, and the core part 2 May include an inner conductor 1, an insulator covering the inner conductor 1, and a braid.

  Hereinafter, the content of the present invention will be described more specifically with reference to examples and comparative examples, but the present invention is not limited to the following examples.

(Examples 1-5 and Comparative Examples 1-4)
First, an internal conductor made of a stranded wire in which 12 strands having an outer diameter of 0.665 mm were twisted was prepared.

  A rubber coating layer was coated on the inner conductor as follows.

  That is, first, an insulating layer forming composition comprising an EP rubber component containing an EP rubber and a sulfur vulcanizing agent in the formulation shown in Table 1 was prepared.

  On the other hand, an EP rubber component containing an EP rubber and a vulcanizing agent made of sulfur, a chloroprene rubber component containing a chloroprene rubber and a vulcanizing agent made of a metal oxide, and kneaded with the formulation shown in Table 1, A composition for forming a sheath layer was obtained.

  Then, the insulating layer forming composition and the sheath layer forming composition are put into an extruder, and the unvulcanized insulating layer made of the insulating layer forming composition and the sheath layer forming composition are formed on the inner conductor. The unvulcanized sheath layer was sequentially extrusion coated to obtain an unvulcanized rubber-coated electric wire.

  Next, the unvulcanized rubber-coated electric wire was accommodated in a vulcanized tube having an inner diameter of 20 cm and a length of 20 m. Then, nitrogen gas was continuously introduced into the vulcanized tube, and the unvulcanized rubber-coated electric wire was pressurized with nitrogen gas at 0.35 MPa for 2 minutes at 345 ° C. (linear speed: 8 m / min). The insulating layer and the unvulcanized sheath layer were vulcanized together.

A rubber-coated wire was thus obtained.

  The following characteristics were evaluated for the rubber-coated wires of Examples 1 to 5 and Comparative Examples 1 to 4 obtained as described above.

[Characteristic evaluation]
(1) Adhesiveness between insulating layer and sheath layer in rubber coating layer A part of the rubber coating layer of the rubber-coated electric wire was cut out to obtain a test sample having a width of 10 mm and a length of 20 mm. And about this test sample, the adhesive force of the sheath layer with respect to an insulating layer was measured using the tensile tester. At this time, the measurement of the adhesive force was performed on a 10 mm portion of the test sample excluding 5 mm from both ends. The results are shown in Table 1. In addition, if the adhesion force is 0.75 kgf / cm width or more, it is “accepted”, and if the adhesion force is less than 0.75 kgf / cm width, it is determined to be unacceptable. In the case of failure, “×” is also written. In addition, the value of “0.75 kgf / cm or more” means an adhesion force in which peeling does not easily occur in a water pressure resistance test for rubber-coated wires.

(2) Flame retardancy Flame retardancy was evaluated by performing a 60-degree tilt test among the flame retardancy tests described in JISC3005. A Bunsen burner having a diameter of 10 mm was used as a heating source, and the flame was adjusted to an oxidation flame length of about 130 mm and a reduction flame length of about 35 mm. Industrial methane gas was used as the fuel. In the 60 degree inclination test, a cable with a length of 300 mm is supported with an inclination of about 60 degrees with respect to the horizontal, and the tip of the bunsen burner reducing flame is burned within 30 seconds at a position about 20 mm from the lower end of the cable. It was done by examining the extent of cable combustion after applying the flame gently. The pass / fail judgment was “pass” if no flame remained after 5 seconds had elapsed after the flame was removed, and “fail” if flame remained. The results are shown in Table 1. In Table 1, “◯” means pass and “x” means fail.

(3) Oil resistance Since the oil resistance is determined by the sheath layer in the rubber coating layer, a part of the sheath layer of the rubber coating layer is cut out from the rubber-coated electric wire into the No. 3 dumbbell shape defined in JISK6251. This was used as a test piece. This test piece was designated as No. JISK6251. Soaked in 2 oil (IRM902) and heated at 120 ° C. and left to stand. After 18 hours, the test piece was taken out of the oil, the oil on the surface of the test piece was wiped well, and the tensile strength was measured with a tensile tester. And the tensile strength of the comparative example 1 was made into 100%, and the residual rate of the tensile strength was computed about Examples 1-5 and Comparative Examples 2-4. And when this residual rate was 60% or more, it was set as "pass" as being excellent in oil resistance. Moreover, when the residual rate was less than 60%, it was set as "fail" because it was inferior in oil resistance. The results are shown in Table 1. In Table 1, “◯” means pass and “x” means fail.

  From the results shown in Table 1, the rubber-coated wires of Examples 1 to 5 are excellent in adhesion between the insulating layer and the sheath layer and sufficiently difficult as compared with the rubber-coated wires of Comparative Examples 1 to 4. It was found to have flammability.

  From this, it was confirmed that the rubber-coated wire of the present invention is excellent in flame retardancy. Moreover, since the rubber-coated electric wire of the present invention is excellent in adhesiveness, it is considered that the decrease in the adhesiveness between the insulating layer and the sheath layer can be sufficiently prevented even when used in water.

DESCRIPTION OF SYMBOLS 1 ... Internal conductor 2 ... Core part 3 ... Rubber coating layer 3a ... Insulating layer 3b ... Sheath layer 10 ... Rubber coating electric wire

Claims (2)

A core including a conductor;
A rubber coating layer covering the core portion;
The rubber covering layer is a rubber covered electric wire having an insulating layer disposed on the core portion side and a sheath layer provided so as to cover the insulating layer,
The rubber coating layer comprises an unvulcanized insulating layer made of an insulating layer forming composition for forming the insulating layer on the core portion, and an unvulcanized layer made of a sheath layer forming composition for forming the sheath layer. It is obtained by sequentially extruding and coating a sheath layer, and collectively vulcanizing the unvulcanized insulating layer and the unvulcanized sheath layer,
The insulating layer forming composition contains a resin containing ethylene propylene rubber and a vulcanizing agent,
The sheath layer forming composition contains a resin containing chloroprene rubber and ethylene propylene rubber and a vulcanizing agent,
A rubber-coated electric wire in which the ethylene-propylene rubber is blended at a ratio of 15 to 42 parts by mass when the total mass of the chloroprene rubber and the ethylene-propylene rubber in the composition for forming a sheath layer is 100 parts by mass. A rubber coating layer forming step of forming a rubber coating layer that covers the core portion including the conductor, wherein the rubber coating layer is disposed on the core portion side, and a sheath provided so as to cover the insulating layer A method for producing a rubber-coated electric wire having a layer,
The rubber coating layer forming step includes forming an unvulcanized insulating layer made of an insulating layer forming composition for forming the insulating layer and a sheath layer forming composition for forming the sheath layer on the core portion. An unvulcanized rubber-coated electric wire forming step of sequentially extruding and coating the vulcanized sheath layer to form an unvulcanized rubber-coated electric wire;
A vulcanization step of collectively vulcanizing the unvulcanized insulating layer and the unvulcanized sheath layer of the unvulcanized rubber-coated electric wire,
In the vulcanization step, the unvulcanized rubber-coated electric wire is accommodated in a vulcanized tube, an inert gas is introduced into the vulcanized tube, and the unvulcanized rubber-coated electric wire is pressurized with the inert gas. While vulcanizing the unvulcanized insulating layer and the unvulcanized sheath layer of the unvulcanized rubber-coated electric wire at once,
The insulating layer forming composition contains a resin containing ethylene propylene rubber and a vulcanizing agent,
The sheath layer forming composition contains a resin containing chloroprene rubber and ethylene propylene rubber and a vulcanizing agent,
Manufacture of a rubber-coated wire in which the ethylene propylene rubber is blended at a ratio of 15 to 42 parts by mass when the total mass of the chloroprene rubber and the ethylene propylene rubber in the sheath layer forming composition is 100 parts by mass. Method.

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