JP2007207642A - Non-halogen-based insulation wire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a non-halogen based insulation wire having superior flexibility, wear and tear resistance, flame resistance, oil resistance, and electrical insulation or the like, and furthermore, a superior heat resistant lifetime. <P>SOLUTION: The non-halogen based insulation wire is made by covering a resin composition containing a sulfur system antioxidant, a hindered phenol system antioxidant, a metal hydroxide, and zinc oxide in polyethylene or ethylene system copolymer on a conductor, and the resin composition covered is cross-linked. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a non-halogen insulated wire, and more specifically, it is coated with a non-halogen insulating material having excellent heat resistance, flexibility, flame retardancy, wear resistance, and electrical insulation, and is highly sophisticated like in an engine room of an automobile. The present invention relates to a non-halogen insulated electric wire that is suitably used for a portion requiring a heat resistant life.

  Insulation materials for insulated wires used in wire harnesses in automobile engine rooms have not only high heat resistance life but also excellent flexibility, wear resistance, flame resistance, heat resistance, oil resistance, electrical insulation, etc. Required. Therefore, conventionally, insulated wires using polyvinyl chloride (PVC) or flame retardant polyethylene cross-linked by a method of irradiating with ionizing radiation such as an accelerated electron beam have been widely used, and depending on the required heat-resistant life, etc. It has been used properly.

  In recent years, in the field of wire harnesses, it has been desired to reduce the amount of halogen-based substances such as polyvinyl chloride in order to reduce the environmental load. Therefore, there is an increasing demand for electric wires insulated with non-halogen flame retardant materials such as polypropylene and cross-linked polyethylene (non-halogen insulated wires).

  As non-halogen insulated wires, conductors are already made of insulating materials in which a metal hydrate flame retardant such as magnesium hydroxide is blended with an ethylene copolymer such as polyethylene, ethylene vinyl acetate copolymer or ethylene ethyl acrylate. There has been proposed an electric wire manufactured by extrusion coating on an upper surface, followed by irradiation with an accelerated electron beam and crosslinking (Japanese Patent Publication No. 7-54645).

As this non-halogen insulated wire, a wire having a heat-resistant life (Arrhenius method) of 120 ° C. × 10000 hours has already been put into practical use. As the performance and functionality of automobiles are improved, the heat-resistant life is further improved. There is a growing demand for non-halogen insulated wires having a heat resistance of 150 ° C. × 10,000 hours, and it is desired to develop a non-halogen insulating material having a heat-resistant life of about 150 ° C. × 10,000 hours. However, at present, those having a heat-resistant life exceeding 120 ° C. have not been put into practical use.
Japanese Patent Publication No. 7-54645

  The present invention provides a non-halogen insulated wire having excellent flexibility, wear resistance, flame resistance, oil resistance, electrical insulation, etc., as well as a conventional non-halogen insulated wire, and further having a superior heat-resistant life. Is the subject.

  As a result of diligent investigations on this problem, the inventor of the present invention uses polyethylene or an ethylene copolymer as a base resin, and uses a resin composition containing a metal hydroxide, an antioxidant and zinc oxide as an insulating material, which is used as a conductor. A non-halogen insulated electric wire coated on and coated with a base resin of the coated resin composition, wherein the antioxidant contains both a sulfur-based antioxidant and a hindered phenol-based antioxidant The present invention was completed by finding that a heat-resistant life exceeding 120 ° C. × 10,000 hours can be obtained.

  That is, the present invention relates to a resin composition comprising a base resin mainly composed of polyethylene and / or an ethylene copolymer and containing a sulfur antioxidant, a hindered phenol antioxidant, a metal hydroxide and zinc oxide. A non-halogen insulated electric wire (Claim 1) is provided, wherein the base resin is crosslinked.

  Examples of the base resin such as polyethylene and ethylene copolymer include high density polyethylene, linear low density polyethylene, low density polyethylene, ultra low density polyethylene, ethylene vinyl acetate copolymer, ethylene methyl acrylate copolymer, ethylene ethyl. Examples include acrylate copolymers, ethylene methyl methacrylate copolymers, ethylene butyl acrylate copolymers, and the like. These can be used singly or in a blend of a plurality of types, or can be blended with other single resin components, for example, thermoplastic elastomers such as ethylene-based elastomers. . Here, the main component means that the blending amount is the largest.

  The present invention is characterized in that the resin composition coated on the conductor contains both a hindered phenolic antioxidant and a sulfurous antioxidant. By containing both, the heat-resistant lifetime exceeding 120 degreeC x 10000 hours is ensured.

  The heat-resistant life at 120 ° C. × 10000 hours is a value measured by the Arrhenius method according to JIS standards and JASO standards. This method is used for evaluating the heat resistance of automobile wires. For example, the insulator is accelerated and deteriorated in a gear oven at 200 ° C., 180 ° C., and 160 ° C., and the elongation of the insulator is 100% at each temperature. This is a value obtained by linearly extrapolating the temperature at which the elongation is 100% due to aging for 10,000 hours from the lifetimes at the three temperatures, with the time decreased to The value of the heat-resistant life in this specification indicates a value measured by the Arrhenius method unless otherwise specified.

  In Patent Document 1, an insulated wire is described in which a polyolefin is coated with a metal hydroxide, zinc oxide, a hydroxybenzoyl isocyanurate compound, a resin composition containing a sulfur-containing ester compound, and crosslinked. Since this insulated wire does not contain a hindered phenolic antioxidant, it does not have a heat resistant life exceeding 120 ° C. × 10000 hours.

  As the hindered phenol-based antioxidant, pentaerythrityl tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], octadecyl-3- (3,5-di-t- Butyl-4-hydroxyphenyl) propionate, 1,3,5-trimethyl-2,4,6-tris (3,5-di-tert-butyl-4-hydroxybenzyl) benzene, N, N′-hexamethylenebis Known hindered phenolic antioxidants such as (3,5-di-t-butyl-4-hydroxy-hydrocinnamamide) can be used.

  The blending amount of the hindered phenol antioxidant is preferably 1 to 10 parts by weight with respect to 100 parts by weight of the base resin (polyethylene or ethylene copolymer) (hereinafter, the blending amount is 100 parts by weight of the base resin). Relative to parts by weight). If it is less than 1 part by weight, the heat-resistant life tends to be insufficient, and if it exceeds 10 parts by weight, problems such as hindered phenol antioxidant bleeding on the insulator surface tend to occur.

  Examples of sulfur-based antioxidants include thioether-based antioxidants such as dilauryl thiodipropionate and pentaerythritol-tetrakis- (β-lauryl thiopropionate), 2-mercaptobekazimidazole, and 2-mercaptobenzimidazole. Examples thereof include zinc salts and mercaptobenzthiazole.

  Among the sulfur-based antioxidants, 2-mercaptobenzimidazole and / or its derivatives are preferable. By using 2-mercaptobenzimidazole and / or a derivative thereof, a higher heat resistance life can be obtained. Claim 2 corresponds to this preferable mode. In particular, when aluminum hydroxide is used as the metal hydroxide, a heat resistant life of about 150 ° C. × 10000 hours or more can be achieved.

  As a compounding quantity of a sulfur type antioxidant, 1 weight part-20 weight part are preferable. If it is less than 1 part by weight, the heat resistance is insufficient, and if it exceeds 20 parts by weight, the effect of improving the heat resistance is saturated and disadvantageous in terms of cost.

  Examples of the metal hydroxide contained in the resin composition forming the insulating coating include aluminum hydroxide and magnesium hydroxide. In particular, the use of aluminum hydroxide is preferable because a higher heat-resistant life can be obtained. Claim 3 corresponds to this preferable mode.

  As the metal hydroxide, by using aluminum hydroxide combined with boehmite, a higher heat-resistant life can be obtained, and it is also preferable from the viewpoint of electrical insulation. Claim 4 corresponds to this preferred embodiment.

  The aluminum hydroxide combined with boehmite is not a mixture of boehmite and aluminum hydroxide, but refers to a mixture of boehmite in aluminum hydroxide in the process of making boehmite from aluminum hydroxide as a raw material. Aluminum hydroxide combined with boehmite is produced, for example, by hydrothermal treatment of aluminum hydroxide, and is suitable as a flame retardant because the dehydration start temperature is 10 to 50 ° C. higher than the starting aluminum hydroxide.

  The hydrothermal treatment is usually performed by heating aluminum hydroxide in a steam atmosphere at 150 ° C. or higher for a predetermined time using a pressure vessel such as an autoclave. Hydrothermal treatment may be performed by mixing aluminum hydroxide and water (wet hydrothermal treatment) or may be performed without mixing water (dry hydrothermal treatment).

  The higher the boehmite complex rate, the higher the dehydration temperature, while the total dehydration amount decreases. Accordingly, the composite ratio of boehmite may be appropriately changed in consideration of the molding temperature of the resin composition to be added, but is usually 5 to 70% by weight and more preferably 10 to 20% by weight. The composite ratio of boehmite can be controlled by changing the heating temperature, treatment time, or water ratio (in the case of wet hydrothermal treatment, the weight ratio of aluminum hydroxide to water). Aluminum hydroxide combined with boehmite is described in JP-A No. 2003-292819.

  The metal hydroxide such as aluminum hydroxide and magnesium hydroxide is preferably surface-treated with a fatty acid, a fatty acid metal salt, a silane coupling agent, a titanate coupling agent or the like. In particular, surface treatment of boehmite-complexed aluminum hydroxide with a fatty acid, a silane coupling agent, or the like further improves the wear resistance and flame retardancy of the electric wire, which is particularly preferable. Claim 5 corresponds to this particularly preferable aspect.

  Examples of the surface treatment agent include fatty acids such as stearic acid, vinyl silane, acrylic silane, amino silane, epoxy silane, and the like. Regarding the surface treatment method, a dry method such as a spray method or an aqueous dispersion of a fatty acid salt or acryl silane is used. The wet method of processing and drying can be used, and they are properly used according to the required characteristics.

  The amount of metal hydroxide blended cannot be generally specified within the range of the optimum blending amount depending on the size of the cable, the conductor, and the structure of the insulator, but if it is set to about 30 to 200 parts by weight, it is required for the electric wire for automobiles. Sufficient flame resistance is obtained. If it is 30 parts by weight or less, the flame retardancy may be insufficient, and if it exceeds 200 parts by weight, the extrudability tends to decrease, and the flame retarding effect is saturated.

  Zinc oxide is an essential component in order to ensure a heat resistant life exceeding 120 ° C. × 10000 hours. As this zinc oxide, those having a primary particle size of 0.05 to 5 μm are preferably used, and the blending amount is preferably 1 to 20 parts by weight. If the amount is less than 1 part by weight, a sufficient heat-resistant life may not be obtained. On the other hand, if the amount exceeds 20 parts by weight, the effect of improving heat resistance is saturated, which is disadvantageous in terms of cost.

  In the said resin composition, other compounding agents can be mix | blended in the range which does not impair the effect of this invention other than the compounding agent as described above as needed. Other compounding agents include known compounding chemicals such as reactive polymers having functional groups such as maleic anhydride-modified polymers and epoxy-modified polymers, lubricants, UV absorbers, heavy metal deactivators, stabilizers, and colorants. It can be illustrated.

  In the resin composition for coating the electric wire of the present invention, the above-described constituent components are melt-mixed using a known mixer such as an open roll mixer, a Banbury mixer, a pressure kneader, a single-screw or twin-screw extruder, and the like. It can be manufactured by the method. This resin composition is coated on a conductor by a method using a known melt extruder to form an insulating coating layer. Examples of the conductor include an electric wire made of copper or a copper alloy.

  The base polymer in the resin composition of the coating layer thus formed exhibits excellent properties such as abrasion resistance and other mechanical strength and heat resistance due to crosslinking. Crosslinking can be performed by irradiation with ionizing radiation such as an accelerated electron beam or gamma ray, or chemical crosslinking by heating after adding an organic peroxide. Among them, the method of irradiating with an accelerated electron beam is preferable from the viewpoint of crosslinking speed. The acceleration voltage is appropriately set depending on the thickness of the insulator, and 300 kV to 2 MeV can correspond to the size of the automobile electric wire. If the irradiation dose is set in the range of 30 to 500 kGy, a sufficient degree of crosslinking can be obtained.

  Moreover, the silane bridge | crosslinking by an organosilane compound is also applicable to the resin composition of a coating layer. Silane crosslinking is preferred because of low cost and increased product economics. The resin composition in this case is a “silane cross-linking batch” in which an organic silane compound is pre-grafted to a base resin using a radical generator such as an organic peroxide, and an antioxidant and zinc oxide are blended therein. The first flame retardant / catalyst batch that contains aluminum hydroxide, silane cross-linking catalyst, etc. in the base resin can be manufactured first, and these can be manufactured by dry blending just before the extrusion process. This method is most effective for electric wires. Applicable to.

  The non-halogen insulated wire of the present invention has excellent flexibility, wear resistance, flame resistance, oil resistance, electrical insulation and the like similar to conventional non-halogen insulated wires, and further excellent heat resistance life, that is, 120 ° C. × It has an excellent heat resistance life exceeding 10,000 hours. In particular, the sulfur-based antioxidant which is a component of the resin composition forming the insulating coating is 2-mercaptobenzimidazole and / or a derivative thereof, the metal hydroxide is a composite of aluminum hydroxide and boehmite. What is aluminum hydroxide can obtain a high heat-resistant life of about 150 ° C. × 10000 hours.

  Next, the best mode for carrying out the present invention will be described in more detail using examples and comparative examples. In addition, this invention is not limited to the form of this Example, The change to another form is also possible unless the meaning of this invention is impaired.

(Manufacture of resin composition pellets)
In accordance with the formulation shown in Table 1 and Table 2, using a 10 liter pressure kneader, the mixture was melted and mixed at 150 ° C., the mixture was discharged, and through the feeder ruder, Examples 1 to 7 and Comparative Examples 1 to 3 Resin composition pellets were obtained. In addition, all compounding quantities are represented by a weight part.

(Manufacture of insulated wires)
Using a single screw extruder of 50 mmφ and L / D = 24, a test wire was manufactured by coating a resin composition on a conductor at an extruder set temperature: 160 ° C. and an extrusion linear velocity: 10 m / min. Then, electron beam irradiation bridge | crosslinking was performed and the insulated wire was obtained. The conductor of the test wires, using a tin-plated annealed copper twisted wire of nominal cross-sectional area of 8 mm ² and 20 mm ^2, the insulator coating thickness was set to 0.9mm and 1.1mm respectively. Electron beam irradiation crosslinking was performed at 2 MeV and 150 kGy.

(Evaluation of insulated wires)
Insulated wires are evaluated in accordance with JASO standards (JASO D608 “Heat-resistant heat-resistant low-voltage wires for automobiles”), mechanical properties (insulator tensile strength, elongation), withstand voltage test, oil resistance test, heat resistance, low temperature winding test, wear A test, a flame retardant test, an insulation resistance test, and a heat resistant life evaluation were performed. Each test condition is described below. Incidentally, flame retardancy tests, nominal cross-sectional area of the conductor is carried out on the wire of 8 mm ² and 20 mm ^2, other evaluations, nominal cross-sectional area of the conductor is performed only for wire 8 mm ^2.

1. Mechanical properties (insulator tensile strength, elongation)
Prepare a pipe-shaped test piece from which the conductor has been removed from the insulated wire sample, and use an Instron tensile tester to conduct a test at a distance between marked lines of 50 mm and a tensile speed of 200 mm / min. It was measured.

2. Withstand voltage test After immersion in water for 5 hours, the voltage was stepped up to AC 1 kV, applied for 1 minute, and the presence or absence of dielectric breakdown was confirmed.

3. Oil resistance test After being immersed in 50 ° C oil for 20 hours and bent, the voltage was stepped up to AC 1 kV, applied for 1 minute, and the presence or absence of dielectric breakdown was confirmed.

4). Heat test The heat test was conducted on the following two items.
-Heat resistance I: After heating and bending at 180 ° C for 240 hours, the voltage was stepped up to AC 1 kV and applied for 1 minute, and the presence or absence of dielectric breakdown was confirmed.
-Heat resistance II: Wrapped six times around a cylinder twice the self diameter, held at 240 ° C for 30 minutes, confirmed that there was no cracking or melting, and passed the one without dielectric breakdown.

5). Low temperature winding test After standing at -45 ° C for 3 hours, wound around a mandrel, exposed the conductor due to low temperature breakdown of the insulator, and stepped up the voltage to AC1kV and applied for 1 minute to confirm that there was no breakdown. Those without destruction were considered acceptable.

6). Abrasion test (scraping test)
For the wear resistance, a test was performed using a wear resistance tester shown in FIG. 1 under the conditions of a load of 7 N, a stroke of 50 mm, and 30 cycles / minute to obtain the number of cycles of scrape wear.

7). Flame Retardancy Test Wire samples with a nominal cross-sectional area of 8 mm ² and 20 mm ² are fixed horizontally, exposed to flame for 10 seconds, and then removed to evaluate the fire spread state of the wires. The case where the fire was extinguished within 30 seconds was regarded as acceptable.

8). Insulation Resistance Test After immersing an electric wire having a nominal cross-sectional area of 8 mm ² in 70 ° C. water for 2 hours, the resistivity of the insulator coating was measured at DC 100 to 500V.

9. Heat-resistant life evaluation Heat-resistant life is evaluated by accelerating degradation of an insulator in a gear oven at 200 ° C, 180 ° C, and 160 ° C, and the time at which the elongation of the insulator is reduced to 100% at each temperature is the lifetime at that temperature. The temperature at which the elongation becomes 100% by aging for 10,000 hours from the lifetime of the three temperatures was obtained by a method of linear extrapolation.

  The results of each evaluation test are shown together in the lower part of Tables 1 and 2.

The contents of the components used in Tables 1 and 2 are shown below.
(* 1) Ethyl acrylate content 23 wt%, MFR = 0.5
(* 2) Average particle diameter: 1.1 μm, BET specific surface area: 5.0 m ² / g, ex.) Shower Denko Co., Ltd.
(* 3) Average particle size: 1.1 μm, BET specific surface area: 5.0 m ² / g, stearic acid treatment Example: Showa Denko Co., Ltd.
(* 4) Average particle size 3.0 μm, dehydration start temperature 260 ° C., stearic acid treatment (* 5) Average particle size 3.0 μm, dehydration start temperature 260 ° C., aminosilane treatment (* 6) Average particle size 1.6 μm, BET specific surface area 4.5 m ² / g, stearic acid treatment Example: Kyowa Chemical Industry Co., Ltd. Kisuma 5A
(* 7) Pentaerythrityl tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate]
(* 8) Pentaerythritol-tetrakis- (β-laurylthiopropionate)
(* 9) 2-mercaptobenzimidazole

  When a resin composition containing appropriate amounts of aluminum hydroxide or magnesium hydroxide, hindered phenol-based antioxidant, sulfur-based antioxidant, and zinc oxide is used (Examples 1 to 4), the estimated life time of 10,000 hours Has a high heat resistance life exceeding 130 ° C. On the other hand, Comparative Examples 1 and 2 are examples in which no zinc oxide is contained, and Comparative Examples 1 and 3 are examples in which no sulfur-based antioxidant is contained. Is very low, well below 120 ° C.

  Among Examples 1 to 4, Examples 1 to 3 using aluminum hydroxide have higher heat-resistant lifetime than Example 4 using magnesium hydroxide, and the estimated lifetime for 10,000 hours exceeds 136 ° C. Yes. From this result, it is clear that aluminum hydroxide is superior to magnesium hydroxide as the metal hydroxide.

  In Examples 1-3, Example 3 which uses 2-mercaptobenzimidazole as a sulfur type antioxidant from Examples 1 and 2 has shown the high heat-resistant lifetime. It has been shown that 2-mercaptobenzimidazole is preferred as the sulfur-based antioxidant.

In Examples 5-7 in which boehmite composite type aluminum hydroxide is used as aluminum hydroxide, the heat resistant life is higher than that in Example 3. From this result, it is shown that boehmite composite aluminum hydroxide is particularly preferable among metal hydroxides in order to obtain a high heat-resistant life. Furthermore, in Examples 1-3, when an electric wire with a nominal cross-sectional area of 8 mm ² is used, the flame retardancy is acceptable, but when an electric wire with a nominal cross-sectional area of 20 mm ² is used, it is not acceptable and the flame retardant is not acceptable. It has been shown that the sex test results depend on the size of the wire. However, in Examples 5 to 7, even when an electric wire having a nominal cross-sectional area of 20 mm ² is used, the flame retardancy is acceptable. From this result, it is shown that when the boehmite composite type aluminum hydroxide is used, an excellent flame retardancy evaluation result can be obtained regardless of the size (thickness) of the evaluated electric wire.

It is a schematic diagram which shows the abrasion resistance tester used in an Example.

Claims (5)

  A resin composition containing a sulfur-based antioxidant, a hindered phenol-based antioxidant, a metal hydroxide and zinc oxide on a base resin mainly composed of polyethylene and / or an ethylene-based copolymer on a conductor. A non-halogen insulated wire, characterized in that it is coated and the base resin is crosslinked.   The non-halogen insulated wire according to claim 1, wherein the sulfur-based antioxidant is 2-mercaptobenzimidazole and / or a derivative thereof.   The non-halogen insulated wire according to claim 1 or 2, wherein the metal hydroxide is aluminum hydroxide.   The non-halogen insulated wire according to claim 3, wherein the metal hydroxide is aluminum hydroxide combined with boehmite. The halogen-free insulated wire according to claim 4, wherein the aluminum hydroxide combined with boehmite is surface-treated with a fatty acid or a silane coupling agent.

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