Electricity: conductors and insulators – Conduits – cables or conductors – Insulated
Reexamination Certificate
2001-07-18
2003-09-30
Reichard, Dean A. (Department: 2831)
Electricity: conductors and insulators
Conduits, cables or conductors
Insulated
C428S372000, C428S375000, C428S379000, C428S383000, C428S389000
Reexamination Certificate
active
06627819
ABSTRACT:
FIELD
The present invention relates to an insulated wire.
BACKGROUND
Insulated wires (electric wires), which are used for inner wiring of electric/electronic equipment, are required to have various characteristics, including fire retardancy, tensile properties, heat resistance, and the like. As the covering material used for these wiring materials, a polyfvinyl chloride) (PVC) compound, a polyolefin compound wherein a halogen-series fire-retardant additive containing bromine atoms or chlorine atoms in the molecule is mixed, and a crosslinked product thereof, have been mainly used.
Recently, there are presented various problems, which occur when insulated wires having such covering materials are discarded without being treated properly. For example, when they are buried, the plasticizer or the heavy metal stabilizer mixed in the covering material is oozed out; and when they are burned, a lot of corrosive gas is produced.
Therefore, techniques wherein wiring materials are covered with a halogen-free fire-retardant material that is free from any risk of oozing out of toxic plasticizers or heavy metals, or generation of a halogen-series gas or the like, are keenly investigated.
The properties required for insulated wires that can be used in electric/electronic equipment (i.e., fire retardancy, tensile properties, heat resistance, and the like) are stipulated in UL Standard (Reference Standard for Electrical Wires, Cables, and Flexible Cords), JIS, etc. Among these required properties, fire retardancy and tensile properties are known for not showing good compatibility with each other (i.e., achieving excellent fire retardancy and excellent tensile properties simultaneously is not easy).
When it is necessary to attain fire retardancy and tensile properties compatibly in an insulated wire coated with a halogen-free fire retardant material, a method can be used that employs, as a coating material, a composition to which red phosphorus has been blended as an auxiliary flame retardant, in addition to a metal hydrate as a flame retardant. However, in the wiring of electric/electronic equipment currently in use, insulated wires are often printed in their surfaces, or coated with materials colored in several colors, so that the types and the connection portions of the insulated wires can be distinguished from each other. Therefore, if red phosphorus is blended to such a coating material, there arise problems that the coating material can no longer be colored in a desired color (e.g. white), due to the color development of red phosphorus, and that printing on the surface of the insulated wire can no longer be recognized.
In recent years, as a method that avoids using red phosphorus, there has been proposed a method wherein a conductor is coated with a crosslinked product of a composition produced by blending a large amount of a metal hydrate, which has been subjected to surface treatment with a silane coupling agent, to an ethylene-series copolymer in which the contents of polar groups, such as vinyl acetate and acrylic ester, have been increased.
The crosslinking of the composition that is coated on the conductor, attained by the electron beam crosslinking method or the chemical crosslinking method, as is also performed in the aforementioned conventional method, has been generally used to improve the heat resistance property. In particular, in order to produce an insulated wire that satisfies strict heat-aging test standards, such as UL 125° C. (after kept at 158° C.×168 hours, the tensile strength retained of the insulating material of a wire being 70% or more, and the tensile elongation retained of the insulating material of a wire being 65% or more) or UL 150° C. (after kept at 180° C.×168 hours, the tensile strength retained of the insulating material of a wire being 70% or more, and the tensile elongation retained of the insulating material of a wire being 65% or more), a method has been employed wherein, in addition to crosslinking the composition, the heat resistance of the composition is improved, by the additive effects brought about by use of a radical chain inhibitor (such as an amine-series antioxidant, a phenol-series antioxidant, or the like) in combination with a peroxide-decomposing agent (such as a sulfur-series antioxidant, a phosphorus-series antioxidant, or the like). Similarly, in the case of a fire retardant insulated wire coated with a crosslinked product of a composition produced by blending a halogen-series flame retardant to a polyolefin, a method of producing such an insulated wire, in most cases, uses a radical chain inhibitor together with a peroxide-decomposing agent, such that the resulting insulated wire satisfies the aforementioned heat aging test standards, such as UL 125° C. and UL 150° C.
However, in the case of the halogen-free fire retardant insulating wire coated with a crosslinked product of a composition produced by blending a large amount of a metal hydrate, which has been subjected to surface treatment with a silane coupling agent, to an ethylene-series copolymer, in which the contents of polar groups, such as vinyl acetate and acrylic ester, have been increased, if a radical chain inhibitor and a peroxide-decomposing agent are used in combination therein, as is the case with the aforementioned fire retardant insulated wire coated with the crosslinked product of a composition produced by blending a halogen-series flame retardant to a polyolefin, the resulting insulated wire cannot satisfy the heat aging test standards of UL 150° C., although it can meet the heat aging test standards of UL 125° C.
SUMMARY
The present invention is an insulated wire, in which a conductor is coated with a crosslinked product of a composition that comprises 150 to 300 parts by weight of a metal hydrate, 1 to 6 parts by weight of a phenol-series antioxidant and 12 to 30 parts by weight of a thioether-series antioxidant, to 100 parts by weight of a base resin containing ethylene/vinyl acetate copolymer, and the content of vinyl acetate in the base resin is 40 wt % or more.
Other and further features, and advantages of the invention will appear more fully from the following description.
DETAILED DESCRIPTION
According to the present invention, the following insulated wire is provided.
(1) An insulated wire, in which a conductor is coated with a crosslinked product of a composition that comprises in a proportion, 100 parts by weight of a base resin containing ethylene/vinyl acetate copolymer, 150 to 300 parts by weight of a metal hydrate, 1 to 6 parts by weight of a phenol-series antioxidant, and 12 to 30 parts by weight of a thioether-series antioxidant, and the content of vinyl acetate in the base resin being 40 wt % or more.
(2) The insulated wire described in the aforementioned (1), wherein the composition further contains no more than 12 parts by weight of a benzoimidazole-series antioxidant per 100 parts by weight of the base resin.
(3) The insulated wire described in the aforementioned (1) or (2), wherein the composition contains an ethylene/acryl rubber in the base resin, with the amount no more than 30 wt % of the base resin.
(4) The insulated wire described in the aforementioned (1), (2) or (3), wherein the metal hydrate has been surface-treated with a silane coupling agent.
(5) The insulated wire described in any one of the aforementioned (1) to (4), wherein the metal hydrate is magnesium hydroxide.
(6) The insulated wire described in any one of the aforementioned (1) to (5), wherein 20 wt % or more of the ethylene/vinyl acetate copolymer is an ethylene/vinyl acetate copolymer of a structure in which three or more vinyl acetate component, as a component of the copolymer, are continuously linked.
Each of the components contained in a composition that is used for coating a conductor and thereby forming an insulating material, in the present invention, will be described hereinafter.
First, a base resin in the present invention and each components contained thereof will be described.
The base resin in the present invention essentially includes (a) ethyle
Hashimoto Dai
Iwata Kouji
Nishiguchi Masaki
Saito Kiyoshi
Knobbe Martens Olson & Bear LLP
Lee Jinhee J
Reichard Dean A.
The Furukawa Electric Co. Ltd.
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