JP5601180B2 - Insulated wire - Google Patents

Description

  The present invention relates to an insulated wire, and more particularly to an insulated wire excellent in heat resistance suitable for automobiles, electrical / electronic devices, and the like.

  As insulation materials for insulated wires used in automobiles, electrical / electronic devices, etc., compounds containing a polyvinyl chloride compound and a halogen-based flame retardant containing a bromine atom or a chlorine atom in the molecule have been mainly used. Such a material containing a halogen atom may generate a large amount of corrosive gas when discarded by incineration. For this reason, a non-halogen flame retardant material that does not generate corrosive gas has been proposed.

  Further, for example, high heat resistance may be required for an insulated wire for automobiles. As what requires such high heat resistance, the insulated wire etc. which are arranged in the engine room of a motor vehicle, for example are mentioned.

  As a heat-resistant insulated wire, for example, an insulated wire formed by forming a first layer made of a composition containing acrylic rubber on a conductor and a second layer made of a fluororesin as an insulating layer is known (patent) Reference 1).

JP 2009-272100 A

  However, the heat-resistant insulated wire described in Patent Document 1 is not sufficient in flame retardancy and heat resistance. Moreover, if the insulating layer of an insulated wire is comprised only with a fluororesin, there exists a problem that cost is high.

  The problem to be solved by the present invention is to provide an insulated wire that is low in cost and excellent in flame retardancy and heat resistance.

  In order to solve the above problems, an insulated wire according to the present invention is an insulated wire in which the periphery of a conductor is covered with at least two insulating layers containing a crosslinked rubber, and the inner layer is an insulating layer containing a crosslinked silicone rubber. The gist is that the outer layer is an insulating layer containing a cross-linked fluororubber.

  In the above insulated wire, the thickness of the inner layer is preferably ½ or more of the thickness of the entire insulating layer.

  In the insulated wire, it is preferable that at least one of the inner layer and the outer layer contains surface-treated magnesium hydroxide surface-treated with a surface treatment agent made of an organic polymer as a flame retardant.

  In the insulated wire, the insulating layer containing the surface-treated magnesium hydroxide as a flame retardant is preferably the outer layer.

  The said insulated wire WHEREIN: It is preferable that content in the said insulating layer of the said surface treatment magnesium hydroxide exists in the range of 0.1-100 mass parts with respect to 100 mass parts of said crosslinked rubber.

  In the insulated wire, the organic polymer as the surface treatment agent for the surface-treated magnesium hydroxide is selected from polyethylene, polypropylene, an ethylene-ethyl acrylate copolymer, an ethylene-vinyl acetate copolymer, and derivatives thereof. One or more types are preferred.

  In the insulated wire, the coating amount on the magnesium hydroxide of the surface treatment agent made of the organic polymer may be in the range of 0.1 to 10% by mass as a proportion of the entire surface treatment magnesium hydroxide. preferable.

  In the insulated wire according to the present invention, the periphery of the conductor is covered with at least two insulating layers containing a crosslinked rubber, the inner layer is an insulating layer containing a crosslinked silicone rubber, and the outer layer is an insulating layer containing a crosslinked fluororubber. Therefore, it is excellent in flame retardancy and heat resistance. In addition, the cost of the material can be reduced as compared with the case where the insulating layer is made of only a fluororesin.

  In the insulated wire, when the thickness of the inner layer is 1/2 or more of the thickness of the entire insulating layer, the cost of the material can be further reduced.

  In the insulated wire, when at least one of the inner layer and the outer layer contains a surface-treated magnesium hydroxide surface-treated with a surface treatment agent made of an organic polymer as a flame retardant, the flame resistance is further improved. Excellent.

  Next, an embodiment of the present invention will be described in detail.

  The insulated wire according to the present invention has a conductor and an insulating layer covering the periphery of the conductor. The insulating layer is composed of two insulating layers, an inner layer covering the periphery of the conductor and an outer layer covering the periphery of the inner layer. The inner layer is an insulating layer containing a crosslinked silicone rubber, and the outer layer is an insulating layer containing a crosslinked fluororubber. The insulating layer containing the cross-linked fluororubber of the outer layer is exposed on the surface as the outermost layer of the insulated wire.

  The thickness of the inner layer and the thickness of the outer layer are not particularly limited. As described in Patent Document 1, the insulating layer containing the crosslinked silicone rubber as the inner layer has higher heat resistance than the insulating layer containing the crosslinked acrylic rubber as conventionally known. That is, the inner layer has sufficiently higher heat resistance than the conventional one. For this reason, even if the thickness of the inner layer is increased, sufficient heat resistance can be ensured. From this viewpoint, the thickness of the insulating layer containing the crosslinked silicone rubber as the inner layer can be set to 1/2 or more of the thickness of the entire insulating layer. Even if comprised in this way, the insulated wire which concerns on this invention is excellent in heat resistance. Further, with such a configuration, the thickness of the insulating layer including the cross-linked fluororubber that is the outer layer can be reduced, so that the material cost can be reduced. The thickness of the inner layer is more preferably 55% or more of the total thickness of the insulating layer, and still more preferably 60% or more of the total thickness of the insulating layer.

  The insulated wire according to the present invention preferably contains a specific flame retardant in at least one of the inner layer and the outer layer. Thereby, the insulated wire which concerns on this invention is further excellent in a flame retardance. The insulating layer containing a specific flame retardant may be an inner layer, an outer layer, or both an inner layer and an outer layer. The insulating layer containing a specific flame retardant is preferably an outer layer from the viewpoint of improving flame retardancy.

  A specific flame retardant is surface-treated magnesium hydroxide that has been surface-treated with a surface treatment agent made of an organic polymer.

  The content of the surface-treated magnesium hydroxide in the insulating layer is preferably in the range of 0.1 to 100 parts by mass with respect to 100 parts by mass of the crosslinked rubber contained in the insulating layer. The content of the surface-treated magnesium hydroxide is more preferably 0.5 to 95 parts by mass. If the content of the surface-treated magnesium hydroxide in the insulating layer is less than 0.1 parts by mass, the flame retardancy of the insulating layer may be deteriorated, and if it exceeds 100 parts by mass, the heat resistance of the insulating layer is deteriorated. There is a fear.

  When the inner layer contains surface-treated magnesium hydroxide, the content of surface-treated magnesium hydroxide in the inner layer relative to the crosslinked rubber in the inner layer containing the crosslinked silicone rubber When the surface-treated magnesium hydroxide is contained in the outer layer, it is represented as the content of the surface-treated magnesium hydroxide in the outer layer relative to the crosslinked rubber in the outer layer containing the crosslinked fluororubber.

  Pre-surface treated magnesium hydroxide used for surface-treated magnesium hydroxide is synthesized from seawater by a crystal growth method, synthesized by reaction of magnesium chloride and calcium hydroxide, etc., or produced naturally. Natural magnesium hydroxide or the like obtained by pulverizing the mineral to be used can be used.

  The untreated magnesium hydroxide before the surface treatment has an average particle size of 0.1 to 20 μm, preferably 0.2 to 10 μm, more preferably 0.5 to 5 μm. If the average particle size of magnesium hydroxide is less than 0.1 μm, secondary aggregation tends to occur, and the mechanical properties of the insulating layer may be reduced. Moreover, when the average particle diameter of magnesium hydroxide exceeds 20 μm, the appearance of the insulating layer may be deteriorated.

  The organic polymer as a surface treatment agent used for the surface treatment of magnesium hydroxide is preferably a hydrocarbon resin such as a paraffin resin or an olefin resin. Specific examples of the hydrocarbon resin include homopolymers of α-olefins such as 1-heptene, 1-octene, 1-nonene, and 1-decene, or interpolymers, or mixtures thereof, polypropylene (PP ), Polyethylene (PE), ethylene-ethyl acrylate copolymer (EEA), ethylene-vinyl acetate copolymer (EVA), and derivatives thereof. The surface treating agent should just contain 1 or more types of the said resin at least.

  The organic polymer as the surface treatment agent may be modified. As the modifier, an unsaturated carboxylic acid or a derivative thereof can be used. Specific examples of the unsaturated carboxylic acid include maleic acid and fumaric acid. Examples of the derivative of unsaturated carboxylic acid include maleic anhydride (MAH), maleic acid monoester, maleic acid diester and the like. Of these, maleic acid and maleic anhydride are preferred. These organic polymer modifiers as the surface treatment agent may be used alone or in combination of two or more.

  Examples of a method for introducing an acid into an organic polymer as a surface treatment agent include a graft method and a direct method. The amount of acid modification is 0.1 to 20% by mass, preferably 0.2 to 10% by mass, and more preferably 0.2 to 5% by mass of the organic polymer as the surface treatment agent.

  The surface treatment method using a surface treatment agent for magnesium hydroxide is not particularly limited. As the surface treatment method of magnesium hydroxide, for example, the surface treatment may be performed on magnesium hydroxide having a predetermined particle diameter, or at the same time as synthesis. Moreover, as a processing method, the wet process using a solvent may be sufficient and the dry process which does not use a solvent may be sufficient. In the wet treatment, examples of suitable solvents include aliphatic solvents such as pentane, hexane, and heptane, and aromatic solvents such as benzene, toluene, and xylene. Moreover, when preparing the composition of an insulating layer, you may knead | mix a surface treating agent simultaneously with materials, such as another rubber raw material.

  In the surface-treated magnesium hydroxide, the coating amount (addition amount of the surface-treating agent) of the surface-treating agent made of an organic polymer to the magnesium hydroxide is 0.1 to 10 mass as a proportion of the entire surface-treated magnesium hydroxide. % Is preferable. If the coating amount of the surface treatment agent made of an organic polymer is less than 0.1% by mass, the dispersion may be poor, and if it exceeds 10% by mass, aggregation may occur.

  The insulating layer may contain various additives in addition to the crosslinked rubber and the specific flame retardant as long as the properties of the insulating layer are not impaired. As such an additive, the common additive used for the insulating layer of an insulated wire can be mentioned. Specifically, other flame retardants, crosslinking agents, fillers, antioxidants, anti-aging agents, pigments and the like can be mentioned.

  The insulated wire according to the present invention can be manufactured, for example, as follows. That is, first, an inner layer composition for forming the inner layer and an outer layer composition for forming the outer layer are prepared. Next, two layers of the prepared inner layer composition and outer layer composition are extruded around the conductor to form a two-layer coating layer containing uncrosslinked rubber around the conductor. Next, the uncrosslinked rubber of these coating layers is crosslinked by a crosslinking means such as heating. Thereby, the insulated wire by which the circumference | surroundings of the conductor were coat | covered with the two-layered insulating layer containing crosslinked rubber can be manufactured.

  Further, the insulated wire according to the present invention is formed by coating the inner layer composition around the conductor to form an inner coating layer, and coating the outer layer composition around the inner coating layer to coat the outer coating. It can also be produced by forming a layer and crosslinking the uncrosslinked rubber of these coating layers by a crosslinking means such as heating.

  The inner layer composition is a composition containing uncrosslinked silicone rubber, and the outer layer composition is a composition containing uncrosslinked fluororubber. The composition for the inner layer or the composition for the outer layer can be prepared by kneading uncrosslinked rubber with various additives such as a flame retardant and a crosslinking agent blended as necessary. When kneading the components of the composition, for example, a conventional kneader such as a Banbury mixer, a pressure kneader, a kneading extruder, a biaxial kneading extruder, or a roll can be used.

  For the extrusion molding of the inner layer composition and the outer layer composition, an electric wire extrusion molding machine or the like used in the production of ordinary insulated wires can be used. What is used for a normal insulated wire can be utilized for a conductor. For example, a single wire conductor or a stranded wire conductor made of a copper-based material or an aluminum-based material can be used. Moreover, the diameter of a conductor, the thickness of an insulating layer, etc. are not specifically limited, According to the use etc. of an insulated wire, it can determine suitably.

  The uncrosslinked silicone rubber may be either a millable type (heat-crosslinked type) that becomes an elastic body by kneading a cross-linking agent and then heat-crosslinked, or a liquid rubber type that is liquid before cross-linking. The liquid rubber type silicone rubber includes a room temperature crosslinking type (RTV) capable of crosslinking near room temperature and a low temperature crosslinking type (LTV) capable of crosslinking when heated near 100 ° C. after mixing.

  As the uncrosslinked silicone rubber used in the inner layer composition, millable silicone rubber is preferable. Millable silicone rubber has the advantage that it is easy to mix during kneading and has excellent workability because the crosslinking temperature is relatively high at 180 ° C. or higher and has good stability. On the other hand, since the liquid rubber type silicone rubber has a low crosslinking temperature of about 120 ° C., it is necessary to suppress heat generation at the time of kneading with low stability, and there is a risk that the temperature management and the like may become troublesome. is there. Millable silicone rubber is a commercially available rubber compound that contains linear organopolysiloxane as the main raw material (raw rubber) and contains reinforcing filler, filler, dispersion accelerator, and other additives. May be.

  Uncrosslinked fluororubber becomes an elastic body by heat-crosslinking using a crosslinking agent as required. Examples of fluororubber include vinylidene fluoride / trifluorinated ethylene chloride copolymer, vinylidene fluoride / hexafluoropropylene copolymer, vinylidene fluoride / hexafluoropropylene / tetrafluoroethylene terpolymer. , Tetrafluoroethylene / propylene rubber, tetrafluoroethylene / propylene / vinylidene fluoride rubber, and the like.

  The crosslinking agent can be appropriately selected depending on the type of uncrosslinked rubber, the crosslinking conditions, and the like. Examples of the crosslinking agent include radical generators such as organic peroxides, compounds such as metal soaps, amines, thiols, thiocarbamates, and organic carboxylic acids. As the crosslinking agent, an organic peroxide or the like is preferable from the viewpoint of improving the crosslinking rate.

  Examples of the organic peroxide include dialkyl peroxides such as dihexyl peroxide, dicumyl peroxide, t-butylcumyl peroxide, and 2,5-dimethyl-2,5-bis (t-butylperoxy) hexane. Examples thereof include peroxyketals such as oxide and n-butyl 4,4-di (t-butyl peroxide) valerate.

  The amount of the crosslinking agent can be determined as appropriate. It is preferable to mix | blend the compounding quantity of a crosslinking agent in 0.01-10 mass% with respect to the total amount of uncrosslinked rubber | gum and a crosslinking agent, for example.

  In the insulated wire according to the present invention having the above-described configuration, the conductor is covered with at least two insulating layers including a crosslinked rubber, the inner layer is an insulating layer including a crosslinked silicone rubber, and the outer layer is an insulating layer including a crosslinked fluororubber. By being a layer, it is excellent in flame retardancy and heat resistance. In addition, the cost of the material can be reduced as compared with the case where the insulating layer is made of only a fluororesin.

  In the insulated wire according to the present invention, the outer layer exposed on the surface is an insulating layer containing crosslinked fluororubber, and the insulating layer containing the crosslinked silicone rubber as the inner layer is covered with the outer layer. When these insulating layers are formed, the layer containing uncrosslinked silicone rubber having high tackiness is covered with a layer containing uncrosslinked fluororubber having low tackiness. For this reason, the adhesiveness of the uncrosslinked silicone rubber is not a problem before the rubber is crosslinked. That is, the layer exposed on the surface when the insulating layer is formed is a layer containing uncrosslinked fluororubber with low adhesiveness, and therefore the handling property before crosslinking of the rubber is not deteriorated and the handling property is excellent. Therefore, at the time of forming the insulating layer, it is not necessary to crosslink the uncrosslinked rubber, for example, on-line immediately after forming the layer containing the uncrosslinked rubber.

  In the present invention, magnesium hydroxide is used as a flame retardant added to the insulating layer. Since the dehydration temperature of magnesium hydroxide is higher than the temperature when silicone rubber or fluororubber used for the insulating layer is cross-linked, foaming of the insulating layer due to dehydration of magnesium hydroxide may occur when silicone rubber or fluororubber is cross-linked. Absent. For this reason, the external appearance defect of an insulating layer does not generate | occur | produce and a favorable external appearance is obtained. Further, there is no possibility that various physical properties such as wear resistance are deteriorated due to the influence of the appearance. Also, since magnesium hydroxide has a higher dehydration temperature than aluminum hydroxide, it crosslinks the insulating layer rubber without causing foaming of the insulating layer at a higher temperature than conventional insulated wires using aluminum hydroxide as a flame retardant. Therefore, the rubber of the insulating layer can be reliably cross-linked. Thereby, the physical property of a desired insulating layer can be obtained reliably.

  In the present invention, the magnesium hydroxide used as a flame retardant added to the insulating layer is a surface-treated magnesium hydroxide that has been surface-treated with a surface treatment agent made of an organic polymer. Excellent dispersibility. That is, since the dispersibility of the magnesium hydroxide in the rubber does not deteriorate, there is little possibility that the cold resistance is deteriorated by the addition of the magnesium hydroxide. Therefore, the insulated wire according to the present invention can exhibit excellent cold resistance. Further, the surface-treated magnesium hydroxide is easily mixed with the rubber component. For this reason, the load at the time of kneading | mixing the composition for inner layers or the composition for outer layers is small, and the temperature rise at the time of kneading | mixing can be suppressed. Therefore, it is possible to use a material that is sensitive to a temperature rise, and the effect that the width of a material that can be used as an insulated wire is widened can be obtained.

  Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the gist of the present invention. For example, although the insulated wire of the said aspect comprised the coating layer from two insulating layers, the insulated wire of this invention may comprise a coating layer from three or more insulating layers. In that case, at least the layer exposed on the surface as the outermost layer may be an insulating layer containing a crosslinked fluororubber, and the insulating layer containing a crosslinked silicone rubber may be formed so as not to be located in the outermost layer. When the insulating layer is composed of three or more layers, the flame retardant may be contained in any layer.

  The insulated wire according to the present invention can be used for insulated wires used in automobiles, electronic / electrical equipment. It is particularly suitable as an insulated wire for applications that require high heat resistance and flame resistance. For example, in an insulated electric wire for automobiles, such high heat resistance is required for high voltage and large current applications such as a power cable connecting an engine and a battery of a hybrid vehicle or an electric vehicle.

  Examples of the present invention and comparative examples are shown below.

[Examples 1 to 9]
Each component was mixed so that it might become a compounding composition shown in Table 1, and the composition for inner layers containing an uncrosslinked silicone rubber was prepared. Moreover, the composition for outer layers containing uncrosslinked fluororubber was prepared by mixing each component so that it might become a compounding composition shown in Table 1. FIG. Next, an inner layer composition and an outer layer composition having the thicknesses shown in Table 1 are formed on the outer periphery of an annealed copper twisted wire conductor (cross-sectional area 0.5 mm ² ) obtained by twisting seven annealed copper wires using an extruder. Was extruded to form a two-layer coating layer containing uncrosslinked rubber. Next, the uncrosslinked rubber was crosslinked by heat-treating the coating layer under conditions of 200 ° C. × 4 hours. Thereby, the insulated wire of Examples 1-9 was obtained.

[Comparative Examples 1-6]
Each component was mixed so that it might become a compounding composition shown in Table 2, and the composition for inner layers containing an uncrosslinked acrylic rubber was prepared. Moreover, the composition for outer layers containing an uncrosslinked fluororubber was prepared by mixing each component so that it might become a compounding composition shown in Table 2. FIG. Subsequently, the insulated wire of Comparative Examples 1-6 was obtained like the Example.

  About the insulated wire of Examples 1-9 and Comparative Examples 1-6, the cold resistance test, the flame retardance test, and the heat resistance test were done and evaluated. The results are shown in Tables 1 and 2. In addition, each component composition of Table 1 and Table 2, a test method, and evaluation are as follows.

[Ingredients in Tables 1 and 2]
・ Silicone rubber 1 [manufactured by Shin-Etsu Chemical Co., Ltd., trade name “931”]
・ Silicone rubber 2 [made by Shin-Etsu Chemical Co., Ltd., trade name “541”]
・ Fluoro rubber 1 [Asahi Glass Co., Ltd., trade name "150E"]
・ Fluoro rubber 2 [Asahi Glass Co., Ltd., trade name "150L"]
・ Acrylic rubber 1 [Product name "4200", manufactured by Electrochemical Co., Ltd.]
・ Acrylic rubber 2 [manufactured by Nippon Zeon, trade name “Nipol AR14”]
・ Fluoro rubber 3 [Daikin, trade name “G801”]
・ Fluoro rubber 4 [Daikin, trade name “G901”]
-PE 5% coated water mug [surface treated magnesium hydroxide, surface treatment agent: polyethylene, surface treatment amount: 5% by mass]
As the surface-treated magnesium hydroxide, magnesium hydroxide having an average particle diameter of 1.0 μm by a crystal growth method was used. Moreover, the product name "800P" by Mitsui Chemicals, Inc. was used for the surface treatment agent polyethylene. The surface treatment amount is mass% with respect to the total amount of polyethylene and magnesium hydroxide.
・ Crosslinking agent [Nippon Yushi Co., Ltd., trade name “Perhexyl D” (di-t-hexyl peroxide)]

[Cold resistance test method]
This was performed in accordance with JIS C3055. That is, the produced insulated wire was cut into a length of 38 mm to obtain a test piece. The test piece was mounted on a cold resistance tester, cooled to a predetermined temperature, hit with a hitting tool, and the state after hitting the test piece was observed. Using five test pieces, the temperature at which all five test pieces were broken was defined as the cold resistant temperature.

[Flame retardancy test method]
In accordance with JIS 6722, a 45 degree inclined flame retardant test was conducted. As a result of the test, the case where the fire was extinguished in 70 seconds or less was regarded as acceptable (O), and the case where the fire was not extinguished in 70 seconds or less was regarded as unacceptable (x).

[Heat resistance test method]
The wire coating was peeled off, the conductor was pulled, and the insulation coating was removed about 100 mm in length to obtain a test piece. The test piece was subjected to a deterioration test at 200 ° C. for 10 days, and then a tensile test was performed. A case where the residual elongation rate was 50% or more was evaluated as acceptable (◯), and a case where the residual elongation was less than 50% was determined as unacceptable (x).

  As shown in Table 1, the insulated wires of Examples 1 to 9 were all excellent in cold resistance, flame retardancy, and heat resistance of the wires, and were confirmed to be excellent in flexibility, flame retardancy, and heat resistance. . On the other hand, the insulated wire of Comparative Examples 1-6 is inferior to cold resistance compared with the thing of an Example. Moreover, it was confirmed that it is inferior to a flame retardance and heat resistance.

  Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the gist of the present invention.

Claims (7)

Surrounding the conductor is an insulated wire that is coated with an insulating layer of at least two layers comprising a cross-linked rubber, the inner layer is an insulating layer comprising a crosslinked silicone rubber, the outer layer is Ri insulating layer der comprising a crosslinked fluorine rubber,
At least one of the inner layer and the outer layer contains, as a flame retardant, surface-treated magnesium hydroxide that has been surface-treated with a surface treatment agent made of an organic polymer,
The organic polymer as the surface treating agent for the surface treated magnesium hydroxide is at least one selected from polyethylene, polypropylene, ethylene-ethyl acrylate copolymer, ethylene-vinyl acetate copolymer, and derivatives thereof. An insulated wire characterized by that.   The insulated wire according to claim 1, wherein the inner layer has a thickness of ½ or more of the thickness of the entire insulating layer. The insulated wire according to claim 1 or 2 , wherein the insulating layer containing the surface-treated magnesium hydroxide as a flame retardant is the outer layer. The content of the surface-treated magnesium hydroxide in the insulating layer is in the range of 0.1 to 100 parts by mass with respect to 100 parts by mass of the crosslinked rubber . The insulated wire according to item 1 . The coating amount on the magnesium hydroxide of the surface treatment agent made of the organic polymer is in the range of 0.1 to 10% by mass as a proportion of the entire surface treatment magnesium hydroxide. The insulated wire according to any one of 1 to 4 . The insulated wire according to any one of claims 1 to 5, wherein the uncrosslinked fluororubber constituting the crosslinked fluororubber is tetrafluoroethylene / propylene rubber. The magnesium hydroxide before the surface treatment constituting the surface-treated magnesium hydroxide is a synthetic magnesium hydroxide synthesized from seawater by a crystal growth method or a reaction between magnesium chloride and calcium hydroxide. The insulated wire according to any one of claims 1 to 6.