JP2012227109A - Insulation wire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an insulation wire which includes an insulation layer containing crosslinked silicone rubber, and has excellent cold resistance and abrasion resistance while suppressing reduction of a variety of physical property due to poor appearance of the insulation layer caused by foaming in crosslinking reaction.SOLUTION: In the insulation wire in which the surroundings of a conductor are covered with an insulating layer containing a crosslinked silicone rubber, the insulation layer includes a mica powder and surface treatment magnesium hydroxide formed by making a magnesium hydroxide surface-treated by a surface treatment agent composed of organic polymer.

Description

  The present invention relates to an insulated wire, and more particularly to an insulated wire that is suitably used in a vehicle such as an automobile.

  Insulating materials for insulated wires used in vehicles such as automobiles are required to have various characteristics such as mechanical characteristics, flame retardancy, heat resistance, and cold resistance. Conventionally, as this type of insulating material, a material containing halogen such as a compound containing a vinyl chloride resin or a halogen-based flame retardant is often used.

  Since this type of insulating material contains halogen, corrosive gas may be generated when discarded by incineration. Therefore, there is an attempt to use an insulating material that does not contain a halogen from the viewpoint of environmental protection.

  For example, Patent Document 1 describes that a non-halogen insulating material in which aluminum hydroxide is blended with uncrosslinked silicone rubber is used as an insulating material for an insulated wire. Since this non-halogenous insulating material contains uncrosslinked silicone rubber, it is necessary to crosslink the uncrosslinked silicone rubber by heating after coating the outer periphery of the conductor.

Japanese Patent No. 3555101

  However, in the insulating material described in Patent Document 1, the crystal water of aluminum hydroxide is released by heating when the uncrosslinked silicone rubber is cross-linked, and dehydration occurs, and the generated water foams the insulating material. There is. When the insulating material is foamed, the insulating layer becomes defective in appearance, and various physical properties may be deteriorated. In addition, since a rubber material (silicone rubber) is used, there is a problem that the insulating layer is softer and more easily worn than, for example, when vinyl chloride resin is used.

  The problem to be solved by the present invention is an insulated wire having an insulating layer containing a crosslinked silicone rubber, which suppresses deterioration of various physical properties due to poor appearance of the insulating layer caused by foaming at the time of crosslinking, as well as cold resistance and wear resistance. An object of the present invention is to provide an insulated wire that is excellent in performance.

  In order to solve the above problems, an insulated wire according to the present invention is an insulated wire in which the conductor is covered with an insulating layer containing a crosslinked silicone rubber, and the insulating layer is hydroxylated by a surface treatment agent made of an organic polymer. The gist of the present invention is that it contains surface-treated magnesium hydroxide and mica powder that have been surface-treated with magnesium.

  At this time, it is desirable that the average particle size of the mica powder is 50 μm or less. Moreover, it is desirable that the content of mica powder is in the range of 0.1 to 100 parts by mass with respect to 100 parts by mass of the crosslinked silicone rubber.

  And it is preferable that content in the insulating layer of surface treatment magnesium hydroxide exists in the range of 0.1-100 mass parts with respect to 100 mass parts of crosslinked silicone rubber.

  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. Preferably there is.

  At this time, it is preferable that the coating amount to the magnesium hydroxide of the surface treatment agent which consists of organic polymers exists in the range of 0.1-10 mass% as a ratio which occupies for the whole surface treatment magnesium hydroxide.

  In the insulated wire of the present invention, the mica powder is preferably a surface-treated mica powder that has been surface-treated with a silane coupling agent.

  In the insulated wire, the amount of the silane coupling agent used for the surface treatment of the surface-treated mica powder is in the range of 0.1 to 10% by mass with respect to the total amount of the mica powder and the silane coupling agent. It is preferable.

  The insulated wire according to the present invention contains a surface-treated magnesium hydroxide and a mica powder in which magnesium hydroxide is surface-treated with a surface treatment agent made of an organic polymer in an insulating layer containing a crosslinked silicone rubber.

  Magnesium hydroxide is not dehydrated like aluminum hydroxide when heated during crosslinking of the silicone rubber. That is, the temperature at which magnesium hydroxide is dehydrated is higher than the temperature at which aluminum hydroxide is dehydrated, and there is no fear of dehydration at the temperature of heat crosslinking of silicone rubber, unlike aluminum hydroxide. Therefore, according to the insulated wire according to the present invention, an appearance defect of the insulating layer due to dehydration of magnesium hydroxide does not occur, and a good appearance can be obtained. Thereby, the fall of various physical properties is suppressed.

  Further, since magnesium hydroxide is surface-treated with a surface treatment agent made of an organic polymer, it is excellent in dispersibility of magnesium hydroxide in silicone rubber. Thereby, it is excellent in cold resistance. Thus, when the dispersibility of magnesium hydroxide is good, the load at the time of kneading silicone rubber and magnesium hydroxide becomes small, and the temperature rise at the time of kneading can be suppressed. As a result, it is possible to use a material that is sensitive to temperature rise, and the effect that the width of a material that can be used as an insulated wire is widened can be obtained.

  Further, by using mica powder together with magnesium hydroxide, it is possible to suppress a decrease in wear resistance when a rubber material is used for the insulating layer while maintaining flame retardancy.

  At this time, when the average particle size of the mica powder is 50 μm or less, the wear resistance is further improved. Moreover, when the content of mica powder is within a specific range, it is easy to improve the wear resistance.

  When the surface-treated mica powder whose surface is treated with a silane coupling agent is used, the adhesion and dispersibility with respect to the silicone rubber are improved, and the cold resistance, wear resistance and the like are improved.

  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 contains a crosslinked silicone rubber, magnesium hydroxide as a flame retardant, and mica powder. Magnesium hydroxide is surface-treated with a surface treatment agent made of an organic polymer.

  This insulating layer is formed using the rubber composition for insulating layers containing uncrosslinked silicone rubber. 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, a 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.

  Magnesium hydroxide is synthesized from seawater by crystal growth method, synthetic magnesium hydroxide such as one synthesized by reaction of magnesium chloride and calcium hydroxide, or natural magnesium hydroxide obtained by pulverizing naturally produced minerals. be able to.

  The average particle size of magnesium hydroxide is preferably in the range of 0.1 to 20 μm. If the average particle size of the magnesium hydroxide is within this range, the mechanical properties of the insulating layer are hardly affected. For example, when the average particle diameter of magnesium hydroxide is less than 0.1 μm, secondary aggregation of the magnesium hydroxide particles tends to occur. When the dispersibility of the magnesium hydroxide particles in the insulating layer is lowered, the mechanical properties of the insulating layer are likely to be lowered. In addition, a decrease in cold resistance is likely to occur. For example, when the average particle diameter of magnesium hydroxide exceeds 20 μm, the appearance of the insulating layer may be deteriorated. The average particle size of magnesium hydroxide is preferably 0.2 to 10 μm, more preferably 0.5 to 5 μm.

  The organic polymer as the surface treatment agent 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.

  The coating amount of the surface treatment agent on magnesium hydroxide (addition amount of the surface treatment agent) is preferably in the range of 0.1 to 10% by mass as a proportion of the entire surface treatment magnesium hydroxide. 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 content of the surface-treated magnesium hydroxide is preferably in the range of 0.1 to 100 parts by mass with respect to 100 parts by mass of the crosslinked rubber. 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 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 may be deteriorated.

  Mica powder is obtained from natural minerals. Mica powder has the effect of toughening the coating. Mica powder contains silicon oxide, aluminum oxide, iron oxide and the like as components. The ratio of silicon oxide in the mica powder is not particularly limited, but is preferably 50% by mass or more. More preferably, it is 55 mass% or more. When the ratio of silicon oxide in the mica powder is high, the adhesion with the silicone rubber is improved and the wear resistance is improved.

  The average particle size of the mica powder is preferably 50 μm or less. When the average particle size of the mica powder is 50 μm or less, the wear resistance is particularly excellent. More preferably, it is 45 micrometers or less, More preferably, it is 40 micrometers or less. On the other hand, the lower limit of the average particle size of the mica powder is not particularly limited, but is preferably 0.1 μm or more, more preferably 0.5 μm or more, and still more preferably 1 from the viewpoint of excellent handleability. 0.0 μm or more.

  The mica powder content is preferably in the range of 0.1 to 100 parts by mass with respect to 100 parts by mass of the crosslinked silicone rubber. More preferably, it exists in the range of 1-95 mass parts, More preferably, it exists in the range of 5-90 mass parts. When the content of mica powder is within a specific range, it is easy to improve wear resistance. When the content of mica powder is less than 0.1 parts by mass, the effect of increasing the wear resistance is likely to be reduced. In addition, kneading with silicone rubber tends to take time. On the other hand, when the content of mica powder exceeds 100 parts by mass, the impact on wear resistance is small, but the elongation at break may be deteriorated. In this case, cold resistance may be affected.

  Wear resistance is improved by blending mica powder with silicone rubber. This is because mica powder that is harder to scrape than silicone rubber is used. When the mica powder falls off from the rubber composition, wear of the rubber composition occurs. Mica powder has an affinity for silicone rubber because it contains a silicon oxide component. For this reason, the mica powder has excellent adhesion to the silicone rubber. This makes it difficult for the mica powder to fall off the rubber composition. In the present invention, the wear resistance is improved by skillfully utilizing that the rubber material as a base is silicone rubber and using mica powder having an affinity therefor as a reinforcing material. Even a composition using such a soft rubber material can be applied to a covering material for an insulated wire by enhancing wear resistance.

  Examples of mica powder include C60M (average particle size 150 μm), C100M (average particle size 65 μm), CS-35 (average particle size 35 μm), CS-25 (average particle size 25 μm), etc., manufactured by Seishin Enterprise Co., Ltd. it can.

  As the mica powder, it is preferable to use a surface-treated mica powder whose surface is surface-treated with a silane coupling agent. When the surface of the mica powder is surface-treated with a silane coupling agent, the dispersibility with respect to the silicone rubber is improved, and the adhesive force with the silicone rubber is improved. As a result, characteristics such as cold resistance and wear resistance of the insulated wire can be further improved.

  Silane coupling agents are hydrolyzed that react with organic functional groups having substituents that bind to organic materials such as vinyl, glycidoxy, methacryl, amino, and mercapto groups in one molecule and inorganic materials such as chlorine or alkoxy groups. Has a sex group. Examples of the silane coupling agent include vinyltrimethoxysilane (KBM-1003), 3-glycidoxypropyltrimethoxysilane (KBM-403), 3-methacryloxypropyltrimethoxysilane (KBM-503), 3-amino Examples thereof include propyltrimethoxysilane (KBM-903), 3-mercaptopropyltrimethoxysilane (KBM-803), bis (triethoxysilylpropyl) tetrasulfide (KBE-846), and the like. The names in parentheses are trade names of Shin-Etsu Chemical Co., Ltd. These may be used alone or in combination of two or more.

  As the silane coupling agent, those having an organic functional group capable of radical polymerization such as vinyl group and methacryl group are preferably used. In order to crosslink the silicone rubber, a radically polymerizable crosslinking agent is added to the composition of the insulating layer. A radically polymerizable silane coupling agent can be expected to partially bond with the crosslinking agent to further strengthen the bond.

  The amount of the silane coupling agent used for the surface treatment of the surface-treated mica powder is preferably in the range of 0.1 to 10% by mass with respect to the total amount of the mica powder and the silane coupling agent. More preferably, the usage-amount of a silane coupling agent exists in the range of 0.5-8 mass%. If the amount of the silane coupling agent used is less than 0.1% by mass, the effect of improving the wear resistance may be reduced, and if it exceeds 10% by mass, the mica particles may aggregate.

  The surface treatment method of the mica powder with a silane coupling agent is not particularly limited, and a surface treatment method such as a general inorganic filler can be used. Specifically, the treatment can be performed by adding mica powder and a silane coupling agent to various mixing apparatuses and mixing them.

  In the rubber composition for the insulating layer, the uncrosslinked silicone rubber can be crosslinked by heating or the like, but may be crosslinked using a crosslinking agent (vulcanizing agent).

  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.

  The insulating layer may contain various additives in addition to the crosslinked silicone rubber, surface-treated magnesium hydroxide, and mica powder 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, a rubber composition for an insulating layer for forming an insulating layer is prepared. Next, the prepared rubber composition is extruded around the conductor to form a coating layer containing uncrosslinked rubber around the conductor. Next, the uncrosslinked rubber of the coating layer is crosslinked by crosslinking means such as heating. Thereby, the insulated wire by which the circumference | surroundings of the conductor were coat | covered with the insulating layer containing crosslinked rubber can be manufactured. The insulated wire according to the present invention can also be formed by coating a rubber composition for an insulating layer around a conductor to form a coating layer, and crosslinking the uncrosslinked rubber of the coating layer by a crosslinking means such as heating. Can be manufactured.

  The rubber composition for the insulating layer can be prepared by kneading uncrosslinked silicone rubber, magnesium hydroxide, mica powder, and various additives such as a crosslinking agent blended as necessary. . When kneading the components of the rubber 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 extruding the rubber composition for the insulating layer, an electric wire extruding machine or the like used for manufacturing a normal insulated wire 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 insulated wire according to the present invention having the above-described configuration contains a surface-treated magnesium hydroxide and mica powder obtained by surface-treating magnesium hydroxide with a surface treatment agent made of an organic polymer in an insulating layer containing a crosslinked silicone rubber. ing.

  Magnesium hydroxide is not dehydrated like aluminum hydroxide when heated during crosslinking of the silicone rubber. That is, the temperature at which magnesium hydroxide is dehydrated is higher than the temperature at which aluminum hydroxide is dehydrated, and there is no fear of dehydration at the temperature of heat crosslinking of silicone rubber, unlike aluminum hydroxide. Therefore, according to the insulated wire according to the present invention, an appearance defect of the insulating layer due to dehydration of magnesium hydroxide does not occur, and a good appearance can be obtained. Thereby, the fall of various physical properties is suppressed.

  Further, since magnesium hydroxide is surface-treated with a surface treatment agent made of an organic polymer, it is excellent in dispersibility of magnesium hydroxide in silicone rubber. Thereby, it is excellent in cold resistance. Thus, when the dispersibility of magnesium hydroxide is good, the load at the time of kneading silicone rubber and magnesium hydroxide becomes small, and the temperature rise at the time of kneading can be suppressed. As a result, it is possible to use a material that is sensitive to temperature rise, and the effect that the width of a material that can be used as an insulated wire is widened can be obtained.

Further, by using mica powder together with magnesium hydroxide, it is possible to suppress a decrease in wear resistance when a rubber material is used for the insulating layer while maintaining flame retardancy. The addition of mica powder improves the chemical resistance of the crosslinked silicone rubber.

  By using surface-treated mica powder that has been surface-treated with a silane coupling agent, the adhesion and dispersibility between silicone rubber and mica powder can be improved, and the cold resistance and wear resistance of insulated wires can be improved. Improve. Further, by using the surface-treated mica powder, the chemical resistance improving effect of the crosslinked silicone rubber is further improved.

  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 was comprised from the single layer insulation layer, you may comprise the insulated wire of this invention from two or more layers of insulation layers.

  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 11 and Examples 12 to 20]
Insulation including uncrosslinked silicone rubber, magnesium hydroxide and mica powder by mixing each component so as to have the composition shown in Table 1 (Examples 1 to 11) and Table 2 (Examples 12 to 20) A rubber composition for the layer was prepared. Next, an uncrosslinked rubber is extruded by extruding a rubber composition for an insulating layer on the outer periphery of a conductor (cross-sectional area 0.5 mm ² ) of an annealed copper twisted wire obtained by twisting 7 annealed copper wires using an extruder. A coating layer containing was formed. Next, the uncrosslinked rubber was crosslinked by heat-treating the coating layer under the conditions of 200 ° C. × 4 hours. Thereby, the insulated wire of Examples 1-11 and Examples 12-20 was obtained.

[Comparative Examples 1-7]
By mixing each component so as to have the composition shown in Table 3, a composition for an insulating layer containing uncrosslinked silicone rubber and aluminum hydroxide was prepared. Subsequently, the insulated wire of Comparative Examples 1-7 was obtained like the Example.

  About the insulated wire of Examples 1-11, Examples 12-20, and Comparative Examples 1-7, the cold resistance test, the external appearance observation of the wire, and the abrasion resistance test were done and evaluated. The results are shown in Tables 1 to 3. In addition, each component composition of Table 1-3, a test method, and evaluation are as follows.

[Ingredients in Tables 1 to 3]
Silicone rubber 1: manufactured by Shin-Etsu Chemical Co., Ltd., 931 (composition: dimethylsiloxane)
Silicone rubber 2: manufactured by Shin-Etsu Chemical Co., Ltd., 541 (composition: dimethylsiloxane)
Silicone rubber 3: manufactured by Toshiba Corporation, 2267 (composition: dimethylsiloxane)
Silicone rubber 4: manufactured by Toshiba Corporation, 2277 (composition: dimethylsiloxane)
PE 5% coated magnesium hydroxide Magnesium hydroxide: crystal growth method, average particle size 1.0 μm
Surface treatment agent: Polyethylene (Mitsui Chemicals, 800P)
Use amount of surface treatment agent: 5% by mass of the total amount of polyethylene and magnesium hydroxide
-Mica powder 1: manufactured by Seishin Enterprise Co., Ltd., CS-35, average particle size 35 μm
-Mica powder 2: C100M, average particle size 65 μm, manufactured by Seishin Enterprise Co., Ltd.
・ Surface treatment mica powder 1
Mica powder: manufactured by Seishin Enterprise Co., Ltd., CS-35, average particle size 35 μm
Silane coupling agent: Shin-Etsu Chemical Co., Ltd., KBM-903
Amount of silane coupling agent used: 1% by mass of the total amount of mica powder and silane coupling agent
・ Surface treatment mica powder 2
Mica powder: manufactured by Seishin Enterprise Co., C100m, average particle size 65μm
Silane coupling agent: Shin-Etsu Chemical Co., Ltd., KBM-503
Amount of silane coupling agent used: 1% by mass of the total amount of mica powder and silane coupling agent
Crosslinking agent: manufactured by NOF Corporation, perhexyl D (di-t-hexyl peroxide)
Aluminum hydroxide: Heidilite H42 manufactured by Showa Denko

[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.

[Evaluation of wire appearance]
The case where unevenness and roughness were not observed on the surface of the insulated wire was evaluated as “good”, and the case where unevenness and roughness were observed on the surface of the insulated wire was rated as “bad”.

[Abrasion resistance test method]
The test was conducted by the blade reciprocation method in accordance with the automobile technical standard “JASO D618”. That is, the insulated wire of an Example and a comparative example was cut out to the length of 750 mm, and it was set as the test piece. Then, at a room temperature of 23 ± 5 ° C., the blade is reciprocated at a speed of 50 mm / min with a length of 10 mm or more in the axial direction with respect to the coating material (insulating layer) of the test piece, and the number of reciprocations until contact with the conductor Was measured. At this time, the load applied to the blade was 7N. About the number of times, the thing of 200 times or more was made into the pass "(circle)", and the thing less than 200 times was made into the disqualified "x". In addition, “◎” is particularly excellent when the number of times is 300 times or more.

  As shown in Tables 1 and 2, it was confirmed that all of the insulated wires of Examples 1 to 20 had good appearance and cold resistance and excellent wear resistance. In particular, when the average particle diameter of the mica powder was 50 μm or less, it was confirmed that the wear resistance was further improved.

  On the other hand, as shown in Table 3, the insulated wires of Comparative Examples 1 to 7 were foamed on the surface of the insulating layer and had poor appearance. In addition, the cold resistance and wear resistance of the insulated wires of Comparative Examples 1 to 7 are lower than those of the Examples as compared to the cold resistance and wear resistance of the corresponding insulated wires of Examples 1 to 7, respectively. It was.

  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 (8)

In an insulated wire whose conductor is covered with an insulating layer containing a crosslinked silicone rubber,
An insulated wire, wherein the insulating layer contains surface-treated magnesium hydroxide obtained by surface-treating magnesium hydroxide with a surface treatment agent made of an organic polymer and mica powder.   2. The insulated wire according to claim 1, wherein the mica powder has an average particle size of 50 μm or less.   The insulated wire according to claim 1 or 2, wherein a content of the mica powder is in a range of 0.1 to 100 parts by mass with respect to 100 parts by mass of the crosslinked silicone rubber.   The content of the surface-treated magnesium hydroxide is in the range of 0.1 to 100 parts by mass with respect to 100 parts by mass of the crosslinked silicone rubber. Insulated wires.   The organic polymer as the surface treatment agent is at least one selected from polyethylene, polypropylene, ethylene-ethyl acrylate copolymer, ethylene-vinyl acetate copolymer, and derivatives thereof. Item 5. The insulated wire according to any one of Items 1 to 4. The amount of the surface treatment agent coated on magnesium hydroxide is in the range of 0.1 to 10% by mass as a proportion of the entire surface treated magnesium hydroxide. The insulated wire of Claim 1.   The insulated wire according to any one of claims 1 to 6, wherein the mica powder is a surface-treated mica powder that has been surface-treated with a silane coupling agent. The amount of the silane coupling agent used for the surface treatment of the surface-treated mica powder is in the range of 0.1 to 10% by mass with respect to the total amount of the mica powder and the silane coupling agent. The insulated wire according to claim 7.