JPH0376737A - Water running-preventive composition and water running-preventive cable manufactured therewith - Google Patents

Abstract

PURPOSE:To enable the crosslinking at a high efficiency and improve the adhesion of a crosslinked product with a stranded conductor by compounding a specific org. polymer, an org. peroxide crosslinker, and an org. polyfunctional compd. CONSTITUTION:The title composition comprises 100 pts.wt. org. polymer having a melt index of 50 or higher and comprising an ethylene-vinyl acetate copolymer contg. 10-50wt.% vinyl acetate and/or ethylene-ethyl acrylate copolymer contg. 10-50wt.% ethyl acrylate; 0.5-5 pts.wt. org. peroxide crosslinker (e.g. dicumyl peroxide); and 0.1-10 pts.wt. org. polyfunctional compd. having at least two reactive C-C double bonds in the molecule and a mol.wt. of 50-100,000 (e.g. triallyl isocyanurate).

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a highly crosslinkable water running prevention composition and a water running prevention cable in which the spaces between stranded conductors are filled with a crosslinked composition thereof.

[Conventional technology]

Conventionally, compositions for preventing water running have been based on high melt index ethylene-vinyl acetate copolymer or ethylene-ethyl acrylate copolymer to facilitate filling between twisted 41I bodies in cable manufacturing. and
Therefore, a crosslinkable composition with a low melt viscosity is used, and after filling, the entire cable is heated and crosslinked with an organic peroxide (for example, Japanese Patent Publication No. 34205/1983, Japanese Patent Publication No. 60/1983). 34206, JP-A-60-34205, etc.).

By the way, the above composition has the property of being difficult to cross-link due to the high melt index of the copolymer, in other words, due to its low molecular weight. Heating is not only undesirable from the viewpoint of energy saving, but also causes the problem of dulling of the stranded wire conductor.

Furthermore, in the past, the highly crosslinked product of the above composition was generally made of Fi.
Considering the poor adhesion with the wire conductor and its difficulty in crosslinking, it is unavoidable to use it in a moderately crosslinked state.

[Problem to be solved by the invention]

In view of the above, the present invention provides a composition that can crosslink a high melt index ethylene-vinyl acetate copolymer or ethylene-ethyl acrylate copolymer with high efficiency, and that has good adhesion to a stranded wire conductor in a highly crosslinked state. The object of the present invention is to develop a water running prevention cable using the composition and the composition.

[Means for solving problems]

Based on recent research, the present inventors have found that ethylene-vinyl acetate copolymer or ethylene-ethyl acrylate copolymer with a high melt index can be thermally crosslinked with an organic peroxide crosslinking agent in the presence of an organic polyfunctional compound. We obtained an unexpected new finding that it is possible to achieve a high degree of crosslinking, and that the resulting elevated structure has excellent adhesion to stranded conductors.

The present invention was developed based on this knowledge, and is based on the above! lB is an organic polymer having a melt index of at least 50 and consisting of at least one selected from the group consisting of ethylene-vinyl acetate copolymer and ethylene-ethyl acrylate copolymer, and 0.5 parts by weight per 100 parts by weight of the organic polymer. A composition for preventing water running, characterized by comprising ~5 parts by weight of an organic peroxide crosslinking agent and 0.1 to 10 parts by weight of an organic polyfunctional compound, and a twist 11al1
The problem is solved by a water running prevention cable characterized in that the space between the bodies and between the mtlAR body and the crosslinked polyolefin insulating layer formed thereon is filled with a crosslinked product of the above water running prevention composition. Ru.

[Structure and Effect of the Invention When 0.1 to 10 parts by weight of an organic polyfunctional compound is present in the crosslinking system of the above-mentioned polymer having a humelto index of at least 50 and an organic peroxide crosslinking agent, crosslinking of the above-mentioned crosslinking system is achieved. The efficiency is improved, and as a result, a crosslinked body with a high gel fraction can be obtained even if the temperature and time for crosslinking are kept under conventional conditions, and the problem of dulling of the stranded conductor is also solved. Furthermore, the crosslinked product of the present invention has excellent adhesion to the stranded wire conductor in a highly crosslinked state, probably due to the coexistence of the organic polyfunctional compound.

The ethylene-vinyl acetate copolymer has a vinyl acetate content of 10 to 50% by weight, particularly 15 to 45% by weight, and a melt index of at least 50, preferably 70 to 500, particularly 100 to 400. Preferably.

As an ethylene-ethyl acrylate copolymer, the content of ethyl acrylate is 10 to 50% by weight, especially 1
5 to 45% by weight with a melt index of at least 50, preferably 70 to 500, especially 100 to 40
A value of 0 is preferred.

The above copolymer No. 211 may be used alone or as a mixture of the two in any ratio, as long as the mixture of the two has a melt index of at least 50.

Examples of organic peroxide crosslinking agents include dicumyl peroxide, 1.1-bis(t-butylperoxy) 3.3.5-trimethylcyclohexane, n-butyl-4,4-bis(
Including t-butylperoxy)valerate, t-butylcumyl peroxide, α,tX”-bis(t-butylperoxy-isopropyl)benzene, and other materials known as cross-linking agents for polyethylene, etc. Can be used.

As the organic polyfunctional compound, a compound having at least two reactive carbon-carbon double bonds in the molecule is used,
For example, at least difunctional, especially 2 to 4 functional aromatic compounds, aliphatic compounds, cyclic compounds, metal-containing compounds, etc. are preferred, and molecular weights of 50 to 100,000 are preferred.
0, particularly preferably 100 to 10,000. Specific examples are shown below.

+1) polyfunctional aromatic compound nidivinylbenzene,
Diaryl phthalate, diaryl isophthalate, 4,4'-isopropylidene diphenol bis(diethylene glycol methacrylate) ether, triallyl trimellitate, N,N'-metaphenylene
Bismaleimide, etc. (2) Polyfunctional aliphatic compounds: ayn-1,2-polybutadiene, 1,4-butanediol diacrylate, N,N-methylene bisacrylamide, neopentyl glycol dimethacrylate, trimethylolpropane trimethacrylate , 1,6-hexanediol dimethacrylate, etc., (3) Polyfunctional cyclic compounds: triallyl isocyanurate, triaryloylhexahydro-1,3,5 triazine, diaryl chlorendate, etc., (4) polyfunctional metal-containing compounds, etc. Aluminum acrylate, zinc acrylate, magnesium acrylate, etc.

Among the above, particularly preferred are triallyl trimellitate, N,N''-metaphenylene bismaleimide, trimethylolpropane trimethacrylate, and triallyl isocyanurate.

If the amount of the organic peroxide crosslinking agent and the organic polyfunctional compound used is less than the above-mentioned lower limit amounts, efficient crosslinking will not be achieved; on the other hand, if the amount used is more than the respective upper limit amounts, the crosslinking efficiency will no longer improve; On the contrary, the adhesion of the crosslinked body to the stranded wire conductor may deteriorate.

FIG. 1 is an example of a cross-sectional view of a water running prevention cable according to the present invention, in which a stranded conductor (11) consisting of a large number of hard copper strands (11) is shown.
2) and the interlayer (5) between the stranded conductor section) and the crosslinked polyolefin insulation layer (4) formed thereon.
is filled with the crosslinked product (6) of the composition for preventing water running.

The water running prevention cable of the present invention has a gap between the stranded conductors (2) (
3) is filled with the anti-water running II compound of the present invention under pressure,
An insulating layer made of a cross-linkable polyolefin insulator, such as a polyethylene composition, is formed on the stranded conductor (2) using a normal extruder, and then heated using a continuous cross-linking device to form an insulating layer and prevent water running. It can be produced by simultaneously crosslinking both materials. Note that during thermal crosslinking using a continuous crosslinking device, heat is transferred from the outside to the inside, so generally the composition for preventing water running exists between the eyebrows (5) of the m&IIs body (2) and the crosslinked polyolefin insulating layer (4). The gap between the lff1 & llI bodies (2) (the fraction of anti-hydrotaxis &ll animal gel present in the powder tends to be lower).However, fortunately, the anti-hydrotaxis composition of the present invention has a gel fraction of 20-20. Since it shows good adhesion to the stranded wire conductor between 80% and 80%, the heating conditions during crosslinking can be adjusted to
The gel fraction of the composition for preventing water running is 50 to 80%.
, especially about 60 to 75%, and the gel fraction of the water running prevention composition present in the gap (3) is 20 to 60%, especially 30 to 75%.
It is preferable to set it to about 55%. By doing so, the heating conditions during crosslinking can be made mild, which is preferable from the viewpoint of cable production cost and prevention of dulling of the stranded conductor (2), and on the other hand, the water running prevention of the present invention. Due to the high crosslinking efficiency of the composition for
The degree of crosslinking of the anti-water run & 11 precepts can be made higher overall compared to the case where i-products are used.

〔Example〕

EXAMPLES The present invention will be explained in detail by showing Examples and Comparative Examples below.

Examples 1 to 10, Comparative Examples 1 to 2 Ethylene-vinyl acetate copolymer or ethylene-ethyl acrylate copolymer was blended with various organic peroxide crosslinking agents and polyfunctional compounds as shown in the table below. A product (composition is in parts by weight) was prepared, and then press molded and crosslinked under heating conditions of 170° C. for 5 minutes to obtain a crosslinked sheet with a thickness of 1 mm.

The same table also shows the gel fraction of each sheet measured according to JIS C3005.

As can be seen from Table 1, it is clear from comparison with the comparative example that the composition of the present invention has a high gel fraction and extremely excellent crosslinking efficiency.

[Margin below]

Examples 11 to 20 Example compositions 1 to 10 were press-fitted into a stranded conductor (2) made of 19 hard W4M wires with a diameter of 2.3 mm, a crosslinkable polyethylene insulation composition was extrusion coated thereon, and then The &ltc material and the polyethylene insulation composition present between the stranded wire conductors were crosslinked by heating to produce a water running prevention cable having a crosslinked polyethylene insulation layer (4).

Table 2 shows the type of water running prevention composition used, the stranded wire conductor (2) after crosslinking, and the crosslinked polyethylene insulation layer (4).
The degree of crosslinking of each anti-water running composition present in the gap (3) between the eyebrows (5) and the stranded conductor (2) (see Figure 1), measurement results regarding the anti-water running performance of the cable, etc. shows.

Regarding the water running prevention performance of the cable, the length is 100c.
A water pressure of 0.5 kg/cm" was applied to one cut surface of the cable, and the water pressure was left for 24 hours. After that, it was examined whether water seeped out from the other cut surface of the cable. If the test was not approved, the test was considered a fail, and if the test was not approved, the test was considered a pass.

Table 2 [Effects of the Invention] The composition for preventing water running of the present invention has high crosslinking performance, so even if the temperature and time for crosslinking are made milder than before, a crosslinked product with a high gel fraction can be obtained. As a result, it is possible to reduce the cost in cable manufacturing, and the problem of twisting the stranded conductor, which has been a problem in the past, can be solved. Furthermore, the crosslinked body of the present invention has excellent adhesion to the stranded wire conductor in the elevated state.

[Brief explanation of drawings]

FIG. 1 is an example of a cross-sectional view of a water running prevention cable according to the present invention. (1) Hard copper wire (2) Twisted conductor (3) Gap between stranded conductors (2) (4) Structured polyolefin wAa layer (5) Crosslinked polyolefin! ! Between the eyebrows (6) between the 1 & 1 layer (4) and the stranded wire conductor (2) For preventing water running & [1 parabolic bridge (or more) Fig.

Claims (2)

[Claims] (1) A melt index of at least 5 consisting of at least one member selected from the group consisting of ethylene-vinyl acetate copolymer and ethylene-ethyl acrylate copolymer
0 of an organic polymer, 0.5 to 5 parts by weight of an organic peroxide crosslinking agent per 100 parts by weight of the organic polymer, and 0.1
1. A composition for preventing water running, comprising: ~10 parts by weight of an organic polyfunctional compound. (2) The space between the stranded wire conductors and between the stranded wire conductor and the crosslinked polyolefin insulation layer formed thereon is filled with a crosslinked product of the composition for preventing water running according to claim 1. A cable that prevents water from running.