JP2012015066A - Insulated wire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an insulated wire which has an insulating layer containing crosslinked acrylic rubber and which is excellent in flame retardance and heat resistance, favorable in characteristics of cold resistance or the like, and inexpensive.SOLUTION: An insulated wire in which an outside of a conductor is covered by an insulating layer containing crosslinked acrylic rubber is constituted by that the insulating layer contains surface-treated magnesium hydroxide in which a surface of magnesium hydroxide is treated with an organic polymeric surface treatment agent.

Description

  The present invention relates to an insulated wire, and more particularly, to an insulated wire having flame resistance and excellent heat resistance.

  Various properties such as mechanical properties, flame retardancy, heat resistance, and cold resistance are required for members and insulating materials used in automobiles, electrical / electronic devices, and the like. Conventionally, as these insulating materials, a polyvinyl chloride compound or a compound containing a halogen-based flame retardant containing a bromine atom or a chlorine atom in a molecule has been mainly used.

  When such an insulating material is discarded by incineration, a large amount of corrosive gas may be generated. Therefore, a halogen-free flame retardant material that does not generate corrosive gas has been proposed. For example, Patent Document 1 discloses an insulated wire in which an insulating layer is formed of a composition in which polyolefin is mixed with acrylic rubber as a non-halogen flame retardant material in a specially-priced range and silica powder is added.

JP 2009-269979 A

  However, the flame retardancy is insufficient with only acrylic rubber and polyolefin as described in Patent Document 1. Further, when a flame retardant is added to the insulating layer, if the dispersibility of the flame retardant is poor, physical properties such as cold resistance will be inferior.

  The problem to be solved by the present invention is to solve the above-mentioned problems, and in an insulated wire having an insulating layer containing a crosslinked acrylic rubber excellent in heat resistance, flame retardancy is good and cold resistance An object of the present invention is to provide an insulated wire having excellent characteristics such as the above.

  In order to solve the above problems, the insulated wire of the present invention is an insulated wire in which the conductor is covered with an insulating layer containing a crosslinked acrylic rubber, and the insulating layer has an organic polymer surface treatment on the surface of magnesium hydroxide. The gist is to contain surface-treated magnesium hydroxide surface-treated with an agent.

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

  In the insulated wire, the organic polymer surface treatment agent is any one or more selected from the group consisting of polyethylene, polypropylene, ethylene-ethyl acrylate copolymer, ethylene-vinyl acetate copolymer, and derivatives thereof. It is preferable to contain.

  The said insulated wire WHEREIN: As for the said surface treatment magnesium hydroxide, it is preferable that content of the said surface treatment agent with respect to the total amount of the said magnesium hydroxide and the said surface treatment agent is 0.1-10 mass%.

  The insulated wire of the present invention is excellent in flame retardancy because the insulating layer contains surface-treated magnesium hydroxide surface-treated with an organic polymer surface treating agent as a flame retardant. Furthermore, surface-treated magnesium hydroxide is less expensive than polyolefin resin, powdered silica, etc., and there is no risk of increased costs.

  In addition, the present invention uses surface-treated magnesium hydroxide surface-treated with an organic polymer surface treating agent when an insulating layer composition composed of acrylic rubber and a flame retardant is mixed to form an insulating layer. Therefore, the dispersibility in the acrylic rubber is excellent. Since the dispersibility of the flame retardant in the insulating layer composition is good, an insulated wire excellent in properties such as cold resistance can be obtained.

  Furthermore, since the dispersibility of the flame retardant is good in the present invention, when mixing the composition of the insulating layer, the load when mixing with a mixer or the like is reduced, and the temperature rise 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.

  Hereinafter, embodiments of the present invention will be described in detail. The insulated wire of this invention has a conductor and the insulating layer which coat | covers the circumference | surroundings of this conductor. The insulating layer contains cross-linked acrylic rubber and surface-treated magnesium hydroxide having a surface treated with an organic polymer surface treating agent as a flame retardant.

  The content of the surface-treated magnesium hydroxide in the insulating layer is usually in the range of 0.05 to 200 parts by mass with respect to 100 parts by mass of the crosslinked acrylic rubber. The content of the surface-treated magnesium hydroxide is preferably 0.1 to 100 parts by mass, more preferably 0.5 to 95 parts by mass. When the content of the surface-treated magnesium hydroxide in the insulating layer is less than 0.1 parts by mass, flame retardancy may be deteriorated, and when it exceeds 100 parts by mass, dispersibility may be deteriorated.

  The insulation layer containing crosslinked acrylic rubber is coated around the conductor using an insulation layer composition containing acrylic rubber and a flame retardant and added with a crosslinking agent (sulfurizing agent) if necessary, and then the insulated wire is heated. The acrylic rubber is cross-linked by treating with a cross-linking means such as cross-linking the insulating layer.

  The acrylic rubber used in the insulating layer composition is an elastic body mainly composed of an acrylate ester. Examples of the acrylic rubber include those obtained by copolymerizing ethyl acrylate as a main component and other monomers such as butyl acrylate and acrylonitrile and a comonomer for crosslinking. Examples of the comonomer for performing the crosslinking include halogen-containing compounds such as 2-chloroethyl vinyl ether, epoxy compounds such as glycidyl acrylate and allyl glycidyl ether, and diene compounds such as ethylidene norbornene.

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

  The magnesium hydroxide usually 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 is likely to occur, and the mechanical properties of the composition may be reduced. If the average particle size of magnesium hydroxide exceeds 20 μm, the appearance of the insulating layer may be poor.

  As the surface treatment agent for the surface treated magnesium hydroxide, an organic polymer surface treatment agent is used. Surface-treated magnesium hydroxide surface-treated with an organic polymer surface treatment agent has excellent dispersibility in acrylic rubber.

  The organic polymer 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, mutual copolymers, 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.

  Examples of the polyethylene include low density polyethylene, ultra-low density polyethylene, linear low density polyethylene, high density polyethylene, and metallocene polymerized polyethylene. Examples of the polypropylene include an atactic structure, a syndiotactic structure, a metallocene polymerized polypropylene, a homopolymer, and a copolymerized polypropylene.

  The addition amount of the surface treatment agent in the surface-treated magnesium hydroxide is usually 0.001 to 20% by mass, preferably 0.1 to 10% by mass, with respect to the total amount of magnesium hydroxide and the surface treatment agent. More preferably, it is 0.2-8 mass%. When the addition amount of the surface treatment agent is small, the dispersibility of the composition of the insulating layer to which the surface-treated magnesium hydroxide is added is improved, and the effect of improving cold resistance and productivity tends to be lowered. If the amount of the surface treatment agent added is too large, the dispersibility of the composition of the insulating layer does not change so much, and there is little influence on the effect of improving cold resistance, productivity, etc., but the cost may increase. .

  The surface treatment agent may be modified with a modifying agent. Examples of the modification of the surface treatment agent include acid modification by introducing a carboxyl group (acid) using an unsaturated carboxylic acid or a derivative thereof as a modifying agent. When the surface treatment agent is acid-modified, the surface of the magnesium hydroxide and the surface treatment agent become easy to conform. Specific examples of the modifier include maleic acid and fumaric acid as the unsaturated carboxylic acid, and examples of derivatives thereof include maleic anhydride (MAH), maleic acid monoester, maleic acid diester and the like. Of these, maleic acid and maleic anhydride are preferred. These modifiers may be used alone or in combination of two or more.

  Examples of the modification method for introducing an acid into the surface treatment agent include graft polymerization and a direct method. The amount of modification is usually about 0.1 to 20% by weight, preferably 0.2 to 10% by weight, based on the polymer (resin component) of the surface treatment agent, as the amount used of the modifier. More preferably, it is 0.2-5 mass%. When the amount of modification is small, the effect of increasing the affinity between magnesium hydroxide and the surface treatment agent tends to be small, and when the amount of modification is large, the surface treatment agent may self-polymerize, and the effect of increasing the affinity with magnesium hydroxide Tends to be small.

  The surface treatment method for treating the surface of magnesium hydroxide with a surface treatment agent is not particularly limited, and various treatment methods can be used. As a surface treatment method of magnesium hydroxide, for example, a surface treatment is performed by mixing a surface treatment agent afterwards with magnesium hydroxide synthesized in advance to a predetermined particle diameter, or a surface treatment agent at the same time when magnesium hydroxide is synthesized. And a method of performing surface treatment by adding.

  The surface treatment method for magnesium hydroxide may be a wet method using a solvent or a dry treatment method using no solvent. Solvents used for wet processing of the flame retardant include aliphatic hydrocarbons such as pentane, hexane, and heptane, and aromatic hydrocarbons such as benzene, toluene, and xylene. Further, the surface treatment of magnesium hydroxide is carried out by adding a surface treatment agent to untreated magnesium hydroxide and base resin at the time of preparing the flame retardant resin composition, and simultaneously kneading the composition. A method of performing processing may be used.

  In addition to the acrylic rubber and the surface-treated magnesium hydroxide, a crosslinking agent can be added to the insulating layer composition. Moreover, you may add various additives etc. to the insulating layer composition in the range which does not impair the characteristic of an insulating layer. Examples of such additives include general pigments, fillers, antioxidants, anti-aging agents and the like that are used as wire covering materials.

  The insulating layer composition can contain a crosslinking agent for crosslinking the acrylic rubber. The crosslinking agent can be appropriately selected according to the type of crosslinking monomer constituting the acrylic rubber, the crosslinking conditions, and the like. Examples of the type of the crosslinking agent include radical generators such as organic peroxides, compounds such as metal soaps, amines, thiols, thiocarbamates, and organic carboxylic acids. Similarly, the blending amount of the crosslinking agent can be appropriately determined. In general, the crosslinking agent is preferably added in an amount of 0.01 to 10% by mass with respect to the total amount of the acrylic rubber and the crosslinking agent.

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

  Hereinafter, the manufacturing method of said insulated wire is demonstrated. Insulated wires are prepared by kneading the composition constituting the insulating layer, such as acrylic rubber, flame retardant, and crosslinking agent, and extruding the conductor around the conductor to insulate the conductor to form the insulating layer. It can be obtained by crosslinking the acrylic rubber of the insulating layer by means.

  As the kneading method, for example, a Banbury mixer, a pressure kneader, a kneading extruder, a biaxial kneading extruder, a method of melting and kneading with a normal kneading machine such as a roll, and the like can be used. The kneading is preferably performed at about 50 to 60 ° C. by water cooling or the like.

  In order to extrude the insulating layer around the conductor, a wire extrusion molding machine or the like used for manufacturing a normal insulated wire can be used. The conductor used for an insulated wire can utilize what is used for a normal insulated wire. Moreover, the diameter of the conductor of an insulated wire, 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 insulating layer may be a single layer or may be composed of two or more layers.

  The insulated wire of 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, applications requiring such high heat resistance include 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 1-7]
Acrylic rubbers 1-4 having the composition shown in Table 1, PE5% coated magnesium hydroxide, and a crosslinking agent were mixed at room temperature using a Banbury mixer. Thereafter, using an extrusion molding machine, an insulating layer was formed by extruding and coating the outer periphery of an annealed copper strand wire (cross-sectional area 0.5 mm ² ) of seven annealed copper wires in a thickness of 0.2 mm. Thereafter, heat treatment was performed at 200 ° C. for 4 hours to complete the crosslinking, and the insulated wires of Examples 1 to 7 were obtained. The obtained insulated wire was evaluated by performing a cold resistance test and a combustion test. The results are also shown in Table 1. In addition, each component of Table 1, the cold resistance test method, and the combustion test method are as follows.

[Ingredients in Tables 1 and 2]
Acrylic rubber 1: 4200 manufactured by Denki Kagaku
Acrylic rubber 2: Nippon Zeon, Nipol AR14
Acrylic rubber 3: Unimatec, A-5098
Acrylic rubber 4: Unimatec PA-422
PE 5% coated magnesium hydroxide Magnesium hydroxide: crystal growth method, average particle size 1.0 μm
Surface treatment agent: Polyethylene, made by Mitsui Chemicals, 800P
Use amount of surface treatment agent: 5% by mass with respect to the total amount of polyethylene and magnesium hydroxide
Crosslinking agent: manufactured by NOF Corporation, 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.

[Flammability test method]
In accordance with ISO 6722, a 45 degree inclined combustion test was performed.

[Comparative Examples 1-7]
As shown in Table 2, an insulated wire was obtained in the same manner as in the example except that the PE 5% coated magnesium hydroxide of Examples 1 to 7 was changed to polypropylene (manufactured by Nippon Polypro Co., Ltd., EC7). The obtained insulated wire was subjected to cold resistance and flammability tests in the same manner as in the Examples. The results are also shown in Table 2.

  As shown in Table 1, the insulated wires of Examples 1 to 7 all had good cold resistance of the wires, and the results of the combustion test were acceptable. On the other hand, as shown in Table 2, the insulated wires of Comparative Examples 1 to 7 failed in the result of the combustion test.

Claims (4)

  In the insulated wire in which the periphery of the conductor is covered with an insulating layer containing a crosslinked acrylic rubber, the insulating layer contains surface-treated magnesium hydroxide whose surface is treated with an organic polymer surface treatment agent. An insulated wire characterized by that.   The insulated wire according to claim 1, wherein a content of the surface-treated magnesium hydroxide in the insulating layer is 0.1 to 100 parts by mass with respect to 100 parts by mass of the crosslinked acrylic rubber component.   The organic polymer surface treatment agent contains at least one selected from the group consisting of polyethylene, polypropylene, ethylene-ethyl acrylate copolymer, ethylene-vinyl acetate copolymer, and derivatives thereof. The insulated wire according to claim 1 or 2, characterized by the above.   The surface-treated magnesium hydroxide has a content of the surface treatment agent with respect to a total amount of the magnesium hydroxide and the surface treatment agent of 0.1 to 10% by mass. An insulated wire given in any 1 paragraph.