JPS5973807A - Insulated electric article - Google Patents

Abstract

Electrical insulation comprises (1) an inner layer of a cross-linked polymer, e.g. an ethylene/tetrafluoroethylene copolymer, an ethylene/chlorotrifluoroethylene polymer or a vinylidene fluoride polymer, and (2) an outer layer of an aromatic polymer having a glass transition temperature of at least 100 DEG C, e.g. a polyether ether ketone, a polyether ketone or a polyether sulfone. Such insulation combines excellent properties under normal service conditions with low smoke evolution on burning, and is therefore particularly useful for aircraft wire and cable.

Description

[Detailed description of the invention] FIELD OF THE INVENTION This invention relates to insulated electrical articles.

Electrical insulation must satisfy various electrical and physical requirements during normal use. In addition, for many purposes insulation must meet testing requirements to ensure that the insulation does not emit significant amounts of toxic substances or fumes when exposed to high temperatures such as fire. It won't happen. These requirements are particularly stringent for electrical cables used in aircraft and similar equipment. The term "cable" is used to include a single electrically insulated elongated conductor called a "wire," and a "cable" is used to include a number of separate elongated conductors, each individually insulated. and articles comprising a plurality of elongate conductors physically joined together and individually electrically insulated by an insulating material, such as ribbon cables.

Fluorocarbon polymers, especially ethylene/tetrafluoroethylene (ETFE) copolymers such as Tefzel, are widely used in electrical insulation, especially for aircraft wire. When crosslinked, they exhibit an excellent combination of physical and electrical properties, especially under normal use conditions. In this connection, reference is made to U.S. Patent No. 3,580,82
No. 9, No. 3,738.923, No. 3,763,222
No. 3.840.619, No. 3,894,118, No. 3.911.192, No. 3,947.525,
No. 3.970.770, No. 3,985,716, No. 3.995,091, No. 4゜031.167, No. 4
, 155.823, 41121.001 and 4.176.027. Other polymers used in electrical insulation include other olefin polymers (homopolymers and copolymers) and various high melting point aromatic polymers.

It has been found that an effectively produced insulation with improved properties is obtained when having an inner layer of cross-linked melt-extruded olefin polymer coated with a layer of melt-extruded olefin polymer having a glass transition temperature of at least 100°C. Ta. Thus, the present invention provides a melt-formed, preferably melt-extruded insulating layer comprising: ia) a conductor; (bl) a first organic polymer component, preferably in contact with the conductor, which is a cross-linked olefin polymer, in particular an ETFE copolymer; , a second organic polymer component, preferably in contact with the intra-IcI insulating layer, which is a substantially linear aromatic polymer having a glass transition temperature of at least 100°C, preferably at least 130°C. An insulated electrical article, particularly an electrical wire or cable, is provided, preferably having a melt-extruded outer insulation layer.

The olefinic polymer forming the inner insulating layer is at least 138 MPa (20,000 P, S, 1.), preferably at least 207 MPa (30,000 P, S.

1,), especially at least 276MPA (40,000P.

It has a tensile modulus (Young's modulus) of S, I, ). This makes it possible to minimize wrinkles when the article, for example in the form of a wire, is bent.

The insulation of the articles of the present invention provides a useful combination of physical and electrical properties. The outer insulation layer provides excellent resistance to physical abuse. The inner insulating layer is more flexible than the outer insulating layer and therefore provides a more flexible insulation than an insulation consisting solely of aromatic polymers for a given dielectric strength. Furthermore, while aromatic polymers often have poor stress crack resistance which significantly reduces dielectric strength, olefinic polymers do not have this disadvantage. Therefore, the inner jacket is 1. even in environments where the outer jacket is subject to stress cracking. Provides continuous insulation.

The term "olefin polymer" is defined herein as a polymer of one or more unsubstituted and/or substituted olefins. When the polymer comprises substituted olefins as monomers or comonomers, the olefins are preferably polar monomers, especially fluorine-containing monomers (e.g. tetrafluoroethylene) or carboxylic acid esters, especially alkyl acrylates (e.g. methyl or ethyl acrylate). Or a vinyl ester (eg vinyl acetate). The olefin is preferably a fluorocarbon polymer, as explained below.

As stated above, the invention is limited to articles in which the olefin polymer is crosslinked, preferably radiation crosslinked.

Particularly useful properties are obtained when the inner insulating layer is made of a crosslinked fluorocarbon layer. It has been discovered that the combination of an inner insulating layer of a crosslinked hydrocarbon polymer and an outer insulating layer of an aromatic polymer provides an unexpected reduction in smoke production under standard test conditions. By using the present invention,
It is possible to produce electrical wires with a Dm value of 50 or less, preferably 35 or less in the smoke generation test according to ASTM E662-79 (flame method). Note that Dm is the maximum specific optical density.

The term "fluorocarbon polymer" is used to denote a polymer or polymer mixture containing 10% or more, preferably 25% or more, by weight of fluorine. The fluorocarbon polymer is one type of fluorine-containing polymer, a mixture of two or more types of fluorine-containing polymers, or a mixture of one or more types of fluorine-containing polymer and one or more types of non-fluorine-containing polymer. It may be. In one preferred type, the fluorocarbon polymer contains at least 50% by weight, especially less (both 75% by weight) of one or more thermoplastic crystalline polymers containing at least 25% by weight of fluorine.
, in particular at least 85% by weight. One type of crystalline polymer is preferred here. In addition to the crystalline fluorine-containing polymer, the fluoropolymer may include, for example, a fluorine-containing elastomer and/or a polyolefin, preferably a crystalline polyolefin. Fluorine-containing polymers are generally homopolymers or copolymers of one or more fluorine-containing olefinically unsaturated monomers, or copolymers of one or more of the above monomers and one or more olefins. It is. Fluorocarbon polymers usually have a melting point of at least 150°C, often at least 250°C (e.g., 35°C).
(reaches 0℃). The melting point of a crystalline polymer is defined as the temperature at which crystallinity is no longer present in the polymer (or in the main crystalline component of the mixture when a mixture of crystalline polymers is used). The polymer components before crosslinking are
It is preferable to have a viscosity of 105 voids or less at a temperature above the melting point and not exceeding 60°C. Preferred fluorocarbon polymers are copolymers of ethylene, tetrafluoroethylene and optionally one or more comonomers (ETF
(known as E-polymer), specifically 35-60
A copolymer comprising mol % ethylene, 35 to 60 mol % tetrafluoroethylene and not more than 10 mol % of one or more comonomers. Other polymers that may be used include copolymers of ethylene and chlorotrifluoroethylene, polyvinylidene fluoride, copolymers of vinylidene fluoride with one or both of hexafluoropropylene and tetrafluoroethylene, or with hexafluoroinbutylene, and tetrafluoroethylene. and hexafluoropropylene copolymers.

One or both of the inner and outer insulation layers may optionally contain suitable additives such as pigments, antioxidants, heat stabilizers, acid acceptors, and processing aids.

Aromatic polymers used in the present invention are well known to those skilled in the art. United States Patent No. 3°025.60
No. 5, No. 3,354.129, No. 3,441.538
No. 3.442,538, No. 3.446.654, No. 3.658.938, No. 3.838.097,
No. 3.847,867, No. 3,953,400, No. 3,956,240, No. 4.107, 1.47, No. 4゜108.837, No. 4,111.908, Fourth
, No. 177.175, No. 4,293.670, No. 4,
320.224 and 3,446.654 and British Patent Nos. 971.227, 1,369,2
No. 10 and No. 1,599,106.

Such polymers include polyketones, polyetherketones, polyetheretherketones, polyethersulfones, polyetherketone/sulfone copolymers and polyetherimides. Blends of different polymers can also be used. Preferred aromatic polymers have a melting point of at least 250°C, especially at least 300°C, having a melting point of at least 250°C, especially at least 300°C.
is a divalent aromatic group and Q is -0-l-5-1-so
, -co-1-NH-CO-, or -COO-1 or "Ar" is a polyvalent group, and Q represents. The Q group is preferably bonded directly to the aromatic carbon atom of the Ar group. ] It consists essentially of the units shown in .

In other types of aromatic polymers, aromatic polymers have the formula: %formula% [where E is a dihydric phenol residue and E' is an electron-withdrawing group in the ortho or para position to the valence bond. Represents an aromatic compound residue with E and E' are bonded to the 10-group via an aromatic carbon atom. ] This is a crystalline polyarylene ether having repeating units shown in the following. Preferably, E has the formula: %Formula%() [wherein k is a divalent group, X is 0 or 1, Y is a halogen atom, an alkyl group containing 1 to 4 carbon atoms, and 1 to
a group selected from alkoxy groups containing 4 carbon atoms, y
is 0, 1.2.3 or 4, Y is a halogen atom, 1 to 4
2 represents 0.1.2.3 or 4; [E' is the formula: C In the formula, R represents a sulfone group, a carbonyl group, a vinyl group, a sulfoxide group, an azo group, a saturated fluorocarbon group, an organic sulfine oxide group, or an ethylidene group. ] It is indicated by. Preferred polysulfones herein consist essentially of one of the repeating units eg γ.

The insulating articles of the present invention can be manufactured using conventional techniques. The inner insulating layer is typically in contact with the conductor, and the inner and outer insulating layers constitute the total insulation of the article, although other insulating layers may be present. The olefin polymer is preferably radiation crosslinked, and crosslinking may occur before or after the aromatic polymer (which is generally not radiation crosslinked) is added. In electrical cables, the inner insulation layer typically has a thickness of 3 to 15 mils, e.g.
Preferably 101.6-177.8 μm (4-7 mil)
has an annular cross section with a thickness of . Alternatively, the cable may comprise multiple conductors, each with an inner insulating layer surrounding the conductors, and the conductors may be bound together and further insulated by an outer insulating layer.

The present invention will be explained in more detail by the following examples. Examples 1.2.3 and 8 are comparative examples.

EXAMPLE On each side, a 20 AWG strand (19/32) conductor was extrusion coated with an inner insulation layer having the composition and thickness shown in the table. With the exception of Examples 1 and 2, the inner insulating layer was then extrusion coated with an outer insulating layer having the composition and thickness indicated. As shown in the table, in some examples the coated conductor was exposed to a dose of about 10 M lucid to crosslink the inner coating. In these examples −
During one irradiation, an appropriate amount of irradiation crosslinker was included in the inner coating. The outer coating was substantially unaffected by this irradiation. The coated conductor was annealed at 180° C. for 1 hour. The resulting cable sample was tested using ASTM E662~
Tested according to the method of 79 (Flame Method). The table shows the minimum transmittance, the transmittance after 10 minutes,
Minimum transmittance arrival time and maximum optical density (
Dm).

The various polymers used in the examples are described below.

Tefzel 2 B O is an ethylene/
Al in tetrafluoroethylene copolymer.

Halar3 Q □ is an ethylene/chlorotrifluoroethylene copolymer manufactured by Allied Chemical.

Kynar 450 is a polyfluorinated vinylidene manufactured by Pennwald.

PEEK is a polyetheretherketone manufactured by ICI.

Ultem is a polyetherimide manufactured by General Electric.

Victrex 200 P is a polyether sulfone manufactured by ICI.

PEEK, [Jltem and P E S (i) is a substantially bilinear aromatic polymer.

Claims (1)

Claims: (11(a) a conductor; fb) a melt-formed insulating layer comprising a first organic polymer component that is a crosslinked olefin polymer; and fc) a substantially an insulating electrical article comprising a second organic polymer component which is a linear aromatic polymer and having a melt-formed outer insulating layer in contact with an inner insulating layer. (2) The article according to item 1, wherein the olefin polymer contains 25% by weight or more of fluorine. (3) The article of claim 1, wherein the olefin polymer comprises at least 75% by weight of a thermoplastic crystalline polymer containing at least 25% by weight of fluorine. (4) The article according to any one of paragraphs 1 to 3, wherein the olefin polymer consists essentially of any of ethylene/tetrafluoroethylene copolymer, ethylene/chlorotrifluoroethylene copolymer, or vinylidene fluoride polymer. (5) The article according to any one of items 1 to 4, wherein the olefin polymer has a melting point of at least 250°C. (6) the aromatic polymer has a glass transition temperature of at least 130°C and/or at least 250°C;
6. The article according to any one of items 1 to 5, which is a crystalline polymer having a melting point of . (7) The aromatic polymer has the general formula: % formula % [wherein Ar is a polyvalent aromatic group, Q is the formula 0-1-5-
-502-1- Represents CO--NH, CO-. The Q group is preferably bonded directly to an aromatic carbon atom. ] The article according to any one of Items 1 to 6 shown below. (8) The aromatic polymer has the general formula: % formula % [In the formula, E is a dihydric phenol residue, and E' is an aromatic residue having an electron-withdrawing group at the ortho or para position with respect to the valence bond. represents. E and E are bonded to the 10-group via an aromatic carbon atom. 7. The article according to any one of items 1 to 6, which is a crystalline polyarylene ether consisting of repeating units represented by the following. (9) E is the formula: %formula%) [wherein k is a divalent group, X is 0 or 1, Y is a halogen atom, an alkyl group containing 1 to 4 carbon atoms, or 1 to
an alkoxy group containing 4 carbon atoms, y is O or 1-
Y represents a halogen atom, an alkyl group containing 1 to 4 carbon atoms, or an alkoxy group containing 1 to 4 carbon atoms, and 2 represents an integer of 0 or 1 to 4. ] A group represented by [wherein R' is a sulfone group, a carbonyl group, a vinyl group,
Represents a sulfoxide group, an azo group, a saturated carbon silide group, an organic phosphine oxyto group, or a methylidene group. ] The article according to item 8, which is a group represented by the following. aαy and 2 are Q, x is 1, R′ is a sulfonic group, and K is a hydrogen atom, an alkyl group containing 1 to 4 carbon atoms, a halogen-substituted alkyl group containing 6 to 10 carbon atoms, an aryl group, alkylaryl group or aralkyl group containing 6 to 10 carbon atoms, or a halogen-substituted aryl group, alkylaryl group or aralkyl group containing 6 to 10 carbon atoms. The article according to item 9, wherein the aromatic polymer is a group represented by the formula: [wherein xSm and n are O or 1, and when P is an integer from 1 to 4, and when P is greater than 1, m is 1 and X is 0.] Any of the first to sixth terms consisting essentially of the repeating unit shown in The article described in (121) is an electrical wire or cable, and the inner insulating layer is a melt-extruded layer contact-coated with a conductor, and the outer insulating layer is a melt-extruded layer contact-coated with an inner insulating layer.
Articles listed in any of the paragraphs. [131 The inner insulating layer has an annular cross section with a wall thickness of 76.2 to 254 Pm, and the outer insulating layer has an annular cross section with a wall thickness of 76.2 to 381 Pm. The twelfth insulating layer has a wall thickness of 101.6 to 177.8 μm, and an outer insulating layer has a wall thickness of 101.6 to 177.8 μm.
The article according to any one of items 1 to 13. 15. An article according to any one of claims 12 to 14, which is a cable comprising a number of conductors covered by an inner insulation layer with an annular cross-section and bound together by an outer insulation layer.