JP2900063B2 - Adhesive polyethylene resin composition for coating communication cables - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a communication cable which is sufficiently firmly adhered to a substrate such as a metal even at a relatively low temperature, for example, at an adhesion temperature range of about 150 to 190 ° C. The present invention relates to an adhesive polyethylene resin composition for coating.

[Conventional technology and its problems]

Polyethylene has excellent physical properties such as low-temperature brittleness, abrasion, and weather resistance, and also has excellent electrical characteristics, particularly high-frequency characteristics, and has been widely used as an insulation jacket of communication cables.

However, as is well known, polyethylene has inferior adhesiveness, and as it is, it does not sufficiently adhere to not only polyethylene but also a polymer having a polar group such as polyamide or polyester, or even a polar article such as metal. In particular, a thin-core communication cable or the like is formed at an extremely high speed, so that the adhesiveness is further deteriorated. Therefore, conventionally, a modified polyethylene obtained by grafting an unsaturated carboxylic acid or a vinyl trialkoxysilane to a polyethylene has been used as a polyethylene having improved adhesiveness.

[Problems of the prior art]

The above-mentioned adhesion-improved polyethylene has been used as an insulation jacket for communication cables, but recently, the required performance for the cables and the like has been further increased, and in order to prevent performance deterioration due to thermal deterioration, the temperature at the time of coating ( It has become necessary to lower the bonding temperature. At the same time, the molding speed has been further increased in order to improve productivity. When the molding speed is very high as described above, lowering the temperature at the time of coating particularly causes a considerable decrease in adhesiveness, and the adhesive polyethylene composition currently used cannot respond any longer.

[Means for solving the problem]

The present invention provides an adhesive polyethylene resin composition for coating communication cables that adheres and adheres to a substrate sufficiently at a low molding temperature of about 190 ° C. or less, even when the molding speed such as cable molding is extremely high. About.

That is, the present invention relates to 100 parts by weight of polyethylene, 0.05 to 0.3 parts by weight of a silane coupling agent, and an organic peroxide having a decomposition temperature in the range of 180 to 230 ° C. for obtaining a half life of 1 minute.
The present invention relates to an adhesive polyethylene resin composition for coating a communication cable consisting of up to 0.2 parts by weight.

Examples of the polyethylene include ethylene homopolymers such as low-density polyethylene and high-density polyethylene, ethylene and α-olefin having 3 to 10 carbon atoms, for example, propylene, butene-1, hexene-1, 4-methylpentene-1, and octene. Is an ethylene copolymer of linear low-density polyethylene obtained by copolymerizing -1 or the like by a polymerization method such as solution polymerization or gas phase polymerization under relatively low temperature and low pressure conditions, or a mixture thereof. .

As the silane coupling agent, vinyl trialkoxysilanes are preferable, for example, vinyltris (β-methoxyethoxy) silane, vinyltriethoxysilane,
Vinyl trimethoxy silane, γ-methacryloxy propyl trimethoxy silane, etc. are mentioned.

Grafting of a silane coupling agent to polyethylene is generally performed by melt extrusion in the presence of an organic peroxide, and can be combined with a Banbury mixer or other kneading machine in addition to a normal single screw extruder. . As the organic peroxide used here, the same organic peroxides as described below or different organic peroxides may be used. However,
The amount used is different from the case where the modification is performed as in the present invention and at the same time, the adhesion is also improved, and the amount added is much smaller, at most 0.01 part by weight, generally 0.003 to 0.0
The amount is about 07 parts by weight, and substantially all of the silane coupling agent has been consumed when the grafting of the silane coupling agent is completed. Silane-modified polyethylene may be used as it is, or may be used after dilution with unmodified polyethylene as long as the adhesiveness is not impaired.

The addition amount of the silane coupling agent is preferably in the range of 0.05 to 0.3 parts by weight based on polyethylene. 0.0
If the amount is less than 5 parts by weight, the adhesion performance is not sufficiently improved, and if the added amount exceeds 0.3 parts by weight, the reason is not clear (the reaction between the silane coupling agents occurs, and it does not contribute to the adhesion. No further improvement in adhesive performance is observed.

As an organic peroxide, 2,5-dimethyl 2,5-di (t-
Butylperoxy) hexane, α, α'-bis (t-butylperoxy-m-isopropyl) benzene, di-isopropylbenzene hydroperoxide, di-t-
Butyl peroxide, 2,5-dimethyl-2,5-di (t-
(Butylperoxy) hexane-3,1,1,3,3-tetramethylbutyl hydroperoxide and the like. These have a decomposition temperature of 180-230 ° C to obtain their one-minute half-life.
Range.

If the decomposition temperature for obtaining a one-minute half-life is less than 180 ° C., decomposition proceeds rapidly in the initial stage of melt-kneading, and uniform improvement in adhesiveness is not observed. When the decomposition temperature exceeds 230 ° C., decomposition does not proceed sufficiently in a relatively low molding temperature range of about 160 to 190 ° C., and no improvement in adhesiveness is observed.

The addition amount of the organic peroxide is preferably in the range of 0.01 to 0.2 parts by weight based on 100 parts by weight of polyethylene. If the amount of the organic peroxide is less than 0.01 part by weight, sufficient adhesive strength cannot be obtained.
If it exceeds 0.2 parts by weight, the excess peroxide not contributing to the modification causes a crosslinking reaction of the polyethylene, which causes burning or lumps at the time of molding, or increases the smell of the decomposition product, which is not preferable. .

The adhesive polyethylene resin composition for coating a communication cable of the present invention may be obtained by melting polyethylene, a silane coupling agent and an organic peroxide in a temperature range in which the organic peroxide is not substantially decomposed, such as a Banbury mixer. Using a kneader or a single-screw or twin-screw extruder, the mixture can be melt-kneaded and then pelletized for production. Further, at the time of coating on a substrate, a mixture obtained by dry blending the three components may be supplied to an extruder.

 Hereinafter, the present invention will be described in more detail with reference to Examples.

Example 1 Low density polyethylene (MI: 0.28 g / 10 min, density: 0.920 g / c
m ² ) 100 parts of vinyltriethoxysilane 0.2 part, di-isopropylbenzene hydroperoxide 0.1
Parts and 0.1 part by weight of an antioxidant were added and dry-blended to obtain a composition.

This composition was supplied to an extruder and extrusion-coated at a temperature of 180 ° C on a copper conductor having a diameter of 0.65 mm running at a speed of 220 m / min. The coating thickness averaged 95 μm. Cut this communication cable to a length of about 10 to 15 cm, and place 5 cm near one end.
The length of the covering layer is left, the others expose the copper conductor. This specimen is inserted into the capillary of the nipple (diameter almost equal to the outer diameter of the conductor) from the top side, and the tip of the copper conductor is fixed by the upper gripper of the Instron universal tensile tester, and the nipple is gripped by the lower gripper And pull at a speed of 200 mm / min. At this time, the coating layer cannot be passed through the capillary and peels off. Its strength was 780 g.

Example 2 100 parts by weight of linear low-density polyethylene (butene-1 content: 7 mol%, MI: 2.0 g / 10 min, density: 0.922 g / cm ² ), 0.2 part by weight of vinyl tris (β-methoxyethoxy) silane ,
0.15 parts by weight of di-t-butyl peroxide, antioxidant
0.1 parts by weight was melt-kneaded at a temperature of 150 ° C. by a Banbury mixer, and then pelletized by an extruder at a temperature of 150 ° C.

This composition was fed to an extruder and extrusion-coated at a temperature of 190 ° C. on a copper conductor having a diameter of 0.65 mm running at a speed of 235 m / min. The coating thickness averaged 90 μm. When the peel strength was measured in the same manner as in Example 1, it was 950 g.

Comparative Example 1 In Example 1, the organic peroxide was changed to di-t-butyl-
A composition was obtained in the same manner as in Example 1, except that 0.008 parts by weight of di-peroxyisophthalate (the decomposition temperature for obtaining a half life of 1 minute was 168 ° C).

This composition was extrusion-coated on a copper conductor in the same manner as in Example 1. The coating thickness averaged 92 μm. When the peel strength was measured in the same manner as in Example 1, it was 240 g.

In this Comparative Example 1, when the extrusion coating temperature was set to 230 ° C., the peel strength was 820 g, which was almost the same as that of Example 1.

Comparative Example 2 In Example 1, di-t-butyl peroxide was used.
A composition was obtained in the same manner as in Example 1 except that the amount was 0.27 parts by weight.

When this composition was extrusion-coated on a copper conductor in the same manner as in Example 1, burning or bumps were observed on the coated surface, resulting in a cable with extremely poor appearance.

〔The invention's effect〕

The adhesive polyethylene resin composition for coating a communication cable of the present invention is a composition having a sufficient adhesive strength to a substrate even by extrusion coating at a low temperature of about 190 ° C. or lower, for example. Since it can be molded at a low temperature, it does not cause deterioration of the polyethylene resin due to excessive heat, and is suitable as a coating material for communication cables, which have recently become increasingly demanding in performance.

 ──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-56-143234 (JP, A) JP-A-59-91139 (JP, A) JP-A-61-213214 (JP, A) JP-A-62 253608 (JP, A) JP-A-55-150502 (JP, A)

Claims (1)

(57) [Claims] (1) 100 parts by weight of polyethylene, 0.05 to 0.3 parts by weight of a silane coupling agent, 0.01 to 0.2 parts of an organic peroxide having a decomposition temperature in the range of 180 to 230 ° C. for obtaining a half life of 1 minute.
An adhesive polyethylene resin composition for coating a communication cable consisting of parts by weight.