JPH0410683B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a flame-retardant insulated wire, and particularly to a flame-retardant insulated wire that has both high electrical insulation properties and high flame retardancy. Polyolefin resins generally have excellent electrical insulation properties, but have the drawback of being flammable. In recent years, for example, UL has been used for wiring wires for electrical equipment, etc.
There is a tendency for high flame retardancy such as standard VW-1 to be required, and for this purpose, flame-retardant polyolefin resin compositions are generally made by blending a large amount of flame retardants such as halogenated flame retardants with polyolefin resin. is being used as an insulator. However, with such flame retardant methods, the electrical insulation properties, especially the voltage resistance properties, of the polyolefin resin deteriorate significantly, so it is difficult to achieve both high voltage resistance properties and high flame retardancy, such as in high voltage lead wires for televisions. There were problems with the required uses. Therefore, the insulator is made of two layers, and the inner insulator layer is made of polyolefin such as cross-linked polyethylene or polypropylene, which has excellent electrical properties, and the outer sheath layer is made of a highly flame-retardant composition. Two-layer insulated wires with separate functions have been devised. However, even when a conventional highly flame-retardant composition is used as the outer sheath layer, there is a problem that the inner insulator layer melts and sag, and the combustion continues for a long time, which does not meet the standards. The cause of this is
After the outer sheath layer burns out, no cinders are formed and the internal insulating layer is exposed, or even if cinders are formed, they are not strong enough and cracks occur in the cinders, causing the internal insulating layer to ignite. This is to do so. Or, the melted internal insulating layer seeped out and ignited, or the cinders were not strong enough to withstand the weight of the melted internal insulating layer, causing the internal insulating layer to sag. Due to the above-mentioned disadvantages of high-voltage electric wires for wiring electrical equipment, various inventions and ideas have been proposed, but none with sufficient characteristics have been found. The present inventors have conducted various studies based on the viewpoint that an outer sheath layer that forms a carbonized layer that has higher strength after combustion and is less prone to cracking can provide more reliable flame retardancy. In an insulated wire (see Fig. 1) comprising an internal insulating layer 2 coated on the inner insulating layer 2 and an outer sheath layer 3 covering the outer periphery of the inner insulating layer 2, the internal insulating layer is of a crosslinked or non-crosslinked type. Consisting of a polyolefin resin composition, the outer sheath layer has (a) a chlorine content of 30 to 45% by weight and a crystallinity of 10%;
For 100 parts by weight of the following chlorinated polyethylene resin, (b) 5 to 50 parts by weight of zinc borate, (c) General formula (However, R and R' are a hydrogen element, an organic group having a carbon, nitrogen, oxygen, silicon, phosphorus, or sulfur skeleton such as an alkyl group, a halogenated alkyl group, a carbonyl group, or a glycidyl group, and X is a bromine element or (d) aluminum silicate, magnesium silicate, or a compound of alumina and magnesium; Crosslinked or non-crosslinked chlorinated polyethylene containing 5 to 30 parts by weight of an inorganic filler as a main ingredient, (e) 5 to 70 parts by weight of antimony trioxide, and (f) 3 to 50 parts by weight of a lead compound stabilizer. It has been discovered that an insulated wire made of a resin composition has unprecedentedly excellent flame retardancy. In the present invention, (f) the lead compound stabilizer includes:
Even with a small amount of dibasic lead phthalate, it shows the best results in combustion shell formation. This has favorable consequences for the mechanical properties of the composition. In addition, clay, talc, hydrotalcite, and the like are easily available as the inorganic filler (d) mainly consisting of aluminum silicate, magnesium silicate, or a compound of alumina and magnesia. Next, the reason for setting the chlorine content of the chlorinated polyethylene resin (a) to 30 to 45% by weight and the crystallinity to 10% by weight or less is that the chlorine content is less than 30% by weight or
This is because if a wire with a crystallinity of more than 10% by weight is used, the strength of the cinders formed by combustion will not be sufficient, causing a problem with the flame retardancy of the wire.
On the other hand, if the chlorine content exceeds 45% by weight, the heat aging resistance of the chlorinated polyethylene used decreases, which is undesirable. Chlorinated polyethylene with a chlorine content within this range includes polyethylene, EPR, ethylene-vinyl acetate copolymer, and ethylene-ethyl acrylate copolymer, as long as the chlorine content in the entire base polymer is 30% or more. It is also possible to blend polyolefins such as polyvinyl chloride and halogen-containing polymers such as vinyl chloride-ethylene copolymers within 20% by weight. Furthermore, for each combination drug, the above (b)
5 to 50 parts by weight of zinc borate, 1 to 50 parts by weight of the above (c) bisphenol A derivative, 5 to 30 parts by weight of the above (d) inorganic filler, and the above (e) antimony trioxide. 5 to 70 parts by weight, and 3 to 50 parts by weight of the lead compound stabilizer (f) above.
The reason for using parts by weight is that if the amount is less than these ranges, the strength of the cinders formed by combustion will not be sufficient, causing a problem in the flame retardancy of the electric wire. On the other hand, if the amount exceeds this range, no improvement in the effect will be observed, and on the contrary, there will be a drawback that the mechanical strength will decrease. In addition, the said zinc borate mentioned here refers to the single compound or the mixture of three compounds described in the chemical encyclopedia Vol. 8 pages 603-604 (published by Kyoritsu Shuppan Co., Ltd. in 1960). The sheath material used in the present invention may contain compounding agents such as crosslinking agents, crosslinking aids, anti-aging agents, ultraviolet absorbers, plasticizers, fillers, stabilizers, lubricants, colorants, etc. within the usual range. The wire can be crosslinked by means such as radiation crosslinking using ionizing radiation, chemical crosslinking, or silane crosslinking, thereby improving the heat resistance of the electric wire. Further, the polyolefin resin used as the insulating layer includes polyethylene, polypropylene,
polybutene-1, poly4-methylpentene-1,
Resin compositions based on one or more blends of ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, ethylene-propylene copolymer, or ethylene-propylene-diene terpolymer, etc. However, the heat resistance of the wire can be improved by crosslinking with means such as radiation crosslinking using ionizing radiation, chemical crosslinking, or silane crosslinking. In addition, in the case of high-voltage lead wire applications for television, it is necessary to pass the high-voltage cut-through test of the UL.Subject 758 standard, but in this case, the test is conducted in a high-temperature atmosphere of 105°C, so mechanical properties may be affected. The crystal melting point is
It is preferable to use a resin having a temperature of 105° C. or higher for the insulator. In other words, polyethylene with a density of 0.93 or higher is a resin that is relatively easy to crosslink and has a crystalline melting point of 105°C or higher, and its use provides desirable characteristics for high-voltage lead wires for televisions. . Examples of the present invention will be described in detail below in comparison with comparative examples. Examples 1 to 16, Comparative Examples 1 to 8 A 40 mmφ extruder (L/
D22) at a die temperature of 205°C.
S4002E (density 0.935, MFR 0.20) was extruded and coated to a thickness of 0.76 mm, and this was crosslinked by irradiating 40 Mrad of 1 MeV electron beam. On the other hand, roll-mixed sheet-like compositions were obtained at the composition ratios shown in Table 1, and pelletized to obtain pellet-like compositions. (The temperature of the material during rolling was approximately 140°C.) Next, this pellet was extruded and coated on the cross-linked polyethylene insulated wire to a thickness of 0.95 mm, and then a 1 MeV electron beam was applied to it for 10 Mrad.
A completed insulated wire was obtained by irradiation and crosslinking. Each insulated wire thus obtained was subjected to a flame retardant test (UL.
Subj 758 VW-1) and UL.Subj.758 High Voltage Wire Standard for Television Receivers Section 1 (1969) high voltage cut-through tests were conducted. In addition, since high-voltage electric wires are generally molded and require high-temperature mechanical strength, the high-temperature mechanical strength was evaluated and the gel fraction was measured by a V-bending test at 160°C. These test results are shown in Table-2. First, regarding flame retardancy, Examples 1 and 2 using the chlorinated polyethylene of the present invention formed a strong combustion shell without exposing the internal insulating layer after combustion. Therefore, the fire was extinguished immediately after removing the flame from the burner. On the other hand, in Comparative Examples 1 and 2 in which crystalline chlorinated polyethylene was used, vertical cracks occurred in the combustion shells because the combustion shells were not sufficiently formed. As a result, the internal insulator melts and drips and ignites, resulting in a long afterflame time.
It exceeded 60 seconds (according to UL.VW-1 test standard, the afterflame time must not exceed 60 seconds). Chlorine content of about 36
% of vinyl chloride grafted ethylene-vinyl acetate copolymer, a similar combustion phenomenon occurred and the afterflame time exceeded 60 seconds.
Moreover, the good flame retardance of the present invention is demonstrated by Examples 3, 4,
5, 6, and 7, the bisphenol A derivatives were mixed from Fireguard 3000 to Fireguard 2000, Epicote 1001, and NK ester.
Even if the inorganic filler is changed to BPE-200 or the inorganic filler is changed from tallow to clay or hydrotalcite, there is no change. On the other hand, regarding the amount of compounding agents,
As is clear from Comparative Examples 3, 4, 5, 6, and 7, combustion occurred even if the amounts of dibasic lead phthalate, zinc borate, bisphenol A derivative, inorganic filler, and antimony trioxide were reduced. The shell formation became insufficient and the afterflame time exceeded 60 seconds. In addition, Example 9, Example 11, Example 8 of Example 12, Example
13 and Example 11, Example 14 and Example 11, and Example
As is clear from the comparison between Example 16 and Example 11, dibasic lead phthalate, zinc borate, Fire Guard
3000, increasing the amount of Mistron vapor talc or antimony trioxide does not lead to a significant improvement in afterflame time. Furthermore, as is clear from the comparison between Example 10 and Example 1, when dibasic lead phthalate is replaced with tribasic lead sulfate, although it passes the VW-1 test, the afterflame time becomes slightly longer. . That is, from the above, it can be seen that the chlorinated polyethylene of the present invention and these compounding agents are all essential components for flame retardancy of insulated wires. Next, regarding high-pressure cut-through resistance, all the samples whose outer sheath layer was made of a chlorinated polyethylene resin composition passed the high-pressure cut-through property. On the other hand, in the case of Comparative Example 8 using a vinyl chloride grafted ethylene-vinyl acetate copolymer, it did not pass the high-pressure cut-through test. The reason for this is that, as shown in the gel fraction results, in Comparative Example 8, the degree of crosslinking was low, and the total coating thickness became thinner due to thermal deformation of the outer sheath layer, resulting in a decrease in withstand voltage characteristics. Ru. The same can be said about the high temperature V-bending test results. In both the Examples and Comparative Examples using chlorinated polyethylene, no cracks occurred in the outer sheath layer in the severe high-temperature deformation test, but when vinyl chloride grafted ethylene-vinyl acetate copolymer was used, the outer sheath layer did not crack. A crack appeared. The reason for this is thought to be that in the case of the vinyl chloride grafted ethylene-vinyl acetate copolymer, the degree of crosslinking is insufficient, which is reflected in the mechanical strength at high temperatures. As described above, when chlorinated polyethylene is used, it has excellent high temperature cut-through resistance and mechanical strength at high temperatures, and this is due to the high crosslinking efficiency of chlorinated polyethylene. In other words, in the case of an insulated wire with an outer sheath layer made of a chlorinated polyethylene resin composition, it is not only economically advantageous to be able to reduce the amount of irradiation or the amount of crosslinking agent added, but also because of the increase in the amount of irradiation or crosslinking agent. It also has the advantage of preventing dehydrochloric acid reaction and deterioration of heat aging properties.
That is, the present invention can be said to have developed an insulated wire with excellent high pressure resistance and molding resistance because it imparts excellent flame retardancy using chlorinated polyethylene having excellent crosslinking properties. Therefore, the industrial value of the present invention is extremely high.

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【table】 [Brief explanation of drawings]

FIG. 1 is a sectional view of an electric wire according to an embodiment of the present invention. 1...Conductor, 2...Inner insulator layer, 3...Outer sheath layer.

Claims (1)

[Scope of Claims] 1. An insulated wire comprising an internal insulating layer coated on a conductor and an external sheath layer covering the outer periphery of the internal insulating layer, wherein the internal insulating layer is made of crosslinked or non-crosslinked polyolefin. Consisting of a resin composition, the outer sheath layer has (a) a chlorine content of 30 to 45% by weight;
Chlorinated polyethylene resin with crystallinity of 10% or less
(b) 5 to 50 parts by weight of zinc borate per 100 parts by weight;
(c) General formula (However, R and R' are a hydrogen element, an organic group having a carbon, nitrogen, oxygen, silicon, phosphorus, or sulfur skeleton such as an alkyl group, a halogenated alkyl group, a carbonyl group, or a glycidyl group, and X is a bromine element or (d) aluminum silicate, magnesium silicate, or a compound of alumina and magnesia; 5 to 30 parts by weight of the main inorganic filler, (e) 5 to 70 parts by weight of antimony trioxide, and (f) lead compound stabilizer 3
1. A flame-retardant insulated wire comprising a cross-linked or non-cross-linked chlorinated polyethylene resin composition containing ~50 parts by weight. 2. The flame-retardant insulated wire according to claim 1, wherein the lead compound stabilizer (f) is dibasic lead phthalate. 3. The flame-retardant insulated wire according to claim 1, wherein the internal insulating layer is made of a crosslinked polyolefin resin composition. 4. The flame-retardant insulated wire according to claim 3, wherein the polyolefin resin constituting the internal insulating layer is polyethylene having a density of 0.93 or more. 5. The flame-retardant insulated wire according to claim 1, wherein the outer sheath layer is made of a cross-linked chlorinated polyethylene resin composition.