JPH09265839A - Crosslinked urethane resin coated wire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a coating agent having a flame-retardant property and proper adhesion by extruding and coating a thermoplastic urethane resin composition of which a specified amount of a specific compound is composed and having a coating layer crosslinked by electron-beam irradiation on the outside of a conductor. SOLUTION: In this crosslinked urethane resin coated wire, flame-retardant 3wt.% or more containing halogen as a composite element and thermoplastic urethane resin composition of which calcium carbonate equivalent to the quantity of flame-retardant of 1wt.% or more are extruded and coated against a thermoplastic urethane resin of 100wt.% and a crosslinked urethane resin coating layer crosslinked by electron irradiation is provided on the outside of a conductor. This coating layer may be directly provided as an insulation layer on the conductor and may be provided as a wire protection film on the outside of the insulated wire on which the insulation layer is provided on the conductor or outside of a multiple strand insulated wire of which plural insulated wires are stranded.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a crosslinked urethane resin-coated electric wire having a coating layer having excellent adhesiveness.

[0002]

2. Description of the Related Art Urethane resin is used as a covering material for electric wires used in harsh operating environments such as vehicles because it has excellent mechanical strength, abrasion resistance, flexibility and cold resistance. ing. However, if the urethane resin is used as it is, the flame retardancy, heat resistance, water resistance, and chemical resistance do not meet the required characteristics for vehicles. Therefore, to impart flame retardancy, a flame retardant is added to the urethane resin. However, for other performance improvements,
This is achieved by crosslinking the urethane resin by electron beam irradiation.

When wiring a urethane-coated electric wire in a vehicle, for example, the covered electric wire may be fixed to an electric wire fixing tool such as a rubber grommet arranged in a storage box of electric equipment with an adhesive. As the adhesive in this case, a cyanoacrylate-based adhesive that can obtain a strong adhesive strength in a short time is often used.

[0004]

As the flame retardant for urethane resin, a flame retardant containing halogen and phosphorus such as chlorine and bromine as constituent elements (hereinafter, also referred to as halogen / phosphorus flame retardant) is urethane. It is widely used because it significantly improves the flame retardancy of resins. However, a flame-retardant coated electric wire obtained by extrusion-coating a composition in which the above flame retardant is blended in a urethane resin on the outside of a conductor, and electron beam cross-linking is used, as in the past, using a cyanoacrylate adhesive to fix an electric wire such as a rubber grommet. It was found that there is a problem in that the adhesive strength with the coating layer is significantly reduced even if an attempt is made to adhere and fix to the above, and the adhesive fixation cannot be achieved.

In view of the above problems, an object of the present invention is to provide a crosslinked urethane resin-coated electric wire which is flame retardant and has good adhesion without adhesion inhibition.

[0006]

In order to achieve the object of the present invention, in the present invention, 3 parts by weight or more of a flame retardant containing halogen and phosphorus as constituent elements is added to 100 parts by weight of a thermoplastic polyurethane resin. A thermoplastic urethane resin composition, in which calcium carbonate corresponding to 1% by weight or more of the amount of the flame retardant is mixed, is extruded and has a coating layer cross-linked by electron beam irradiation on the outside of the conductor. A crosslinked urethane coated wire is provided.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The crosslinked urethane resin-coated electric wire of the present invention comprises 3 parts by weight or more of a flame retardant containing halogen and phosphorus as constituent elements with respect to 100 parts by weight of a thermoplastic urethane resin and 1 of the amount of the flame retardant. A thermoplastic urethane resin composition mixed with calcium carbonate in an amount of not less than wt% is extrusion coated, and a crosslinked urethane resin coating layer crosslinked by electron beam irradiation is provided on the outside of the conductor. The coating layer is provided directly on the conductor as an insulating layer, on the outside of the insulated wire in which the insulating layer is provided on the conductor, or a multi-core twisted insulated wire in which a plurality of the insulated wires are twisted together. There is a case where it is provided as an electric wire protection layer on the outside of the. In any case, the coated electric wire of the present invention is one in which the outermost layer of the electric wire is provided with a coating layer made of a crosslinked body of the resin composition as described above.

In the coating layer in the present invention, a thermoplastic polyurethane resin is used as a base resin. Examples of the thermoplastic urethane resin include polyester-based urethane resins (adipate-based, caprolactone-based, polycarbonate-based) and polyether-based urethane resins. From the viewpoint of water resistance and mold resistance, ether-based urethane resins (elastomers) ) Is preferred.

Further, the resin composition for the coating layer in the present invention contains, as a flame retardant, a flame retardant containing halogen such as chlorine and bromine and phosphorus as constituent elements. Examples of such flame retardants include trisdichloropropyl phosphate, trischloroethyl phosphate, tris monochloropropyl phosphate, bis (2,3-dibromopropyl) -dichloropropyl phosphate, and the like. Dichloropropyl phosphate is preferable in terms of thermal stability. The blending amount of the flame retardant is required to be 3 parts by weight or more based on 100 parts by weight of the thermoplastic urethane resin, and is usually 3 to 30 parts by weight, preferably 5 to 20 parts by weight. If the blending amount is less than 3 parts by weight, imparting flame retardancy is insufficient, and if it exceeds 30 parts by weight, the mechanical properties of the coating layer may be adversely affected.

Further, the coating layer resin composition of the present invention contains 1% by weight of the above-mentioned halogen / phosphorus flame retardant compounding amount.
Calcium carbonate powder corresponding to the above is blended. The blending ratio of calcium carbonate to the flame retardant needs to be 1% by weight or more, and usually 2 to 10% by weight is preferable.
If the blending ratio is less than 1% by weight, the desired improvement in adhesiveness will not be achieved. When the amount of calcium carbonate added is 1% by weight or more, the effect of improving the adhesiveness increases as the amount increases,
If it exceeds 20% by weight, mechanical strength and cold resistance are impaired.

The resin composition for the coating layer in the present invention is a mixture of a thermoplastic urethane resin with a halogen / phosphorus flame retardant and calcium carbonate as essential components. It is preferred to add functional monomers. As a polyfunctional monomer,
Diacrylates such as diethylene glycol diacrylate, dimethacrylates such as ethylene glycol dimethacrylate, trimethylolethane triacrylate, triacrylates such as trimethylolpropane triacrylate, trimethylolethane trimethacrylate, trimethylolpropane trimethacrylate, etc. Trimethacrylate type, triallyl cyanurate, triallyl isocyanurate, diallyl phthalate, trimethyl methacryl isocyanurate, trimethyl methacryl isocyanurate, trimethyl acryl isocyanurate, trimethyl acryl isocyanurate and the like can be used. Particularly, from the viewpoint of crosslinking efficiency, trifunctional or higher functional monomers such as trimethylolpropane triacrylate and trimethylolpropane trimethacrylate are preferable.

If necessary, the resin composition for a coating layer in the present invention may be used in combination with other flame retardants, addition of flame retardant aids, blending of additives such as fillers and colorants, and the like. The invention can be appropriately performed without departing from the scope of the invention.

The crosslinked urethane resin-coated electric wire according to the present invention is, for example, a multi-core twisted insulated electric wire obtained by twisting a plurality of insulated electric wires having a polyethylene-based insulating layer on a conductor,
As the intervening layer, a polyolefin such as polyethylene, ethylene vinyl acetate copolymer, ethylene ethyl acrylate copolymer, or a thermoplastic urethane resin is coated by a conventional means such as extrusion molding, and halogen and phosphorus are further coated on the outside thereof. It is obtained by extrusion-coating a thermoplastic urethane resin composition containing a flame retardant contained as a constituent element, calcium carbonate, a cross-linking aid, etc., and subjecting it to cross-linking by electron beam irradiation to form a cross-linked urethane resin coating layer. The crosslinking treatment of the coating layer depends on the wall thickness, but for example, the outer diameter is 6.2 mm, the acceleration voltage is 500 to 3000 keV, and the irradiation dose is 2 to 50 Mrad.
It can be performed by irradiating an electron beam under moderate conditions.

Although the mechanism of impairing the adhesion between the cyanoacrylate adhesive and the urethane resin-coated electric wire containing an electron beam crosslinked flame retardant has not been clarified yet, it is not possible to understand the mechanism of the halogen / phosphorus flame retardant by electron beam irradiation. It is considered that a part of the product decomposes and the generated decomposition product hinders the adhesiveness. When calcium carbonate is used in combination, it is considered that the inhibitor substance is effectively rendered harmless to prevent adhesion inhibition.

[0015]

EXAMPLES The present invention will be described more specifically with reference to the following examples. Examples 1 to 8 and Comparative Examples 1 to 5 Resin compositions were prepared by further adding 5 parts by weight of trimethylolpropane trimethacrylate (TMPTM) to each composition shown in Table 1. The obtained resin composition was used as a flame-retardant crosslinked polyethylene insulated wire (conductor constitution; 7/22 / 0.0
5 、 outer diameter 1.7 mm) on a 2-core twisted insulated wire, 30
Using a mmφ extruder (L / D = 25), the extruder temperature is extrusion-coated from the feeder side under conditions of 160 ° C., 170 ° C., 180 ° C., and die temperature of 190 ° C., and the coated electric wire having an outer diameter of 6.2 mm. Got Then, the accelerating voltage to this coated wire; 1
The coating layer was cross-linked by electron beam irradiation at 000 keV and irradiation amount of 20 Mrad.

With respect to each of the obtained crosslinked coated electric wires, the adhesiveness with the cyanoacrylate adhesives A, B and C shown in Table 1 was evaluated by the following method. As shown in FIG. 1, the coated electric wire 1 is inserted into the hollow portion of the rubber grommet 2 (inner diameter 6.2 mm, length 3 cm), and the adhesive drip portion 3 is provided to fix the coated electric wire and the grommet. It was dropped and fixed for 60 seconds. Then, while holding down the covered electric wire 1, grommet 2
Was pulled out by hand. The results are shown in Table 1 as "X" for those that easily pulled out, and as "O" for those that could not be pulled out or those that had the coating layer torn and attached to the grommet after being pulled out.

[0017]

[Table 1]

From the results of Table 1, the crosslinked electric wires of Examples 1 to 8 using the thermoplastic urethane resin composition in which 1% by weight and 2.5% by weight of calcium carbonate were mixed with the halogen / phosphorus flame retardant. Shows that the adhesiveness with the cyanoacrylate adhesive is excellent. On the other hand, cross-linked coated electric wires using the compositions of Comparative Examples 1 and 2 in which the halogen / phosphorus flame retardant and calcium carbonate are not used in combination or the compositions of Comparative Examples 3 and 4 in which the amount of calcium carbonate is less than 1% by weight are sufficient. It can be seen that good adhesion is not obtained. Comparative Example 5 using calcium stearate instead of calcium carbonate
It can be seen that the composition (1) does not have sufficient adhesiveness.

The crosslinked urethane resin-coated electric wire of the present invention is
Calcium carbonate is blended with thermoplastic urethane resin together with halogen / phosphorus flame retardants, so it is flame retardant but does not cause adhesion inhibition, and it is possible to fix wires to grommets etc. during wiring without problems. You can

[Brief description of drawings]

FIG. 1 is a schematic view of a sample for an adhesion test between a covered electric wire and a grommet.

[Explanation of symbols]

 1 Covered wire 2 Grommet 3 Adhesive dripping part

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Reference number within the agency FI Technical indication location H01B 7/34 H01B 7/34 B (72) Inventor Kuniaki Hirano 2-6, Marunouchi, Chiyoda-ku, Tokyo No. 1 inside Furukawa Electric Co., Ltd.

Claims (1)

[Claims] 1. A flame retardant 3 containing halogen and phosphorus as constituent elements with respect to 100 parts by weight of a thermoplastic polyurethane resin.
A thermoplastic urethane resin composition in which 1 part by weight or more and calcium carbonate corresponding to 1% by weight or more of the amount of the flame retardant is mixed is extruded and has a coating layer cross-linked by electron beam irradiation on the outside of the conductor. A crosslinked urethane-coated electric wire characterized by: