JP2590948B2 - Curl cord - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an elastic curl cord suitable for telephones, headphones, and the like.

(Prior Art) The configuration and characteristics of curl cords suitable for telephones and the like are introduced in, for example, JP-A-62-17909. A sheet (2) formed by extruding a synthetic resin, for example, is formed on the outside where a plurality of core wires each formed by covering a conductor with an insulating coating (1) are arranged, and then processed into a spiral shape. Its important functions are that it has an appropriate stretching property, that it has sufficient recovery characteristics as a coil spring, and that it has a good appearance that does not cause twisting or reversal.

The additional properties required are that the insulation layer has good electrical insulation, and that the insulation coating and sheath can be easily extruded twice.

Polyester elastomer having a specific composition as a composition for making a curl cord having a small permanent elongation,
That is, a coated electric wire made of a specific copolyether-ester elastic material is introduced in Japanese Patent Publication No. 58-1484.

(Problems to be solved by the invention) The sheath material of the curl cord generally used at present is
Most of soft vinyl chloride is used because of its flexibility, processability, and inexpensiveness. Various patents such as the above-mentioned patent publication have been proposed to improve its recoverability, spring constant, and flexibility at low temperatures. At present, it is not possible to provide features that can replace vinyl.

When a flexural modulus G introduced in Japanese Patent Application Laid-Open No. Sho 62-17909 has a specific elastic polymer, for example, a polyester-based or polyamide-based elastomer insulator, the curl cord recoverability is improved. However, these materials generally have low insulation resistance. In particular, polyamide-based elastomers are hygroscopic and are not preferable as an insulating layer.

Further, when the copolyester ether elastic body is directly coated on the conductor as in the inventions of the above-mentioned publications and Japanese Patent Publication No. Sho 58-1484, the elastic body may be heated when curled or used in a heated atmosphere. Since the polyether part in the inside was in contact with the metal conductor, it was found that oxidation deterioration was rapidly caused and durability was deteriorated.

(Means for Solving the Problems) In order to solve the above problems, the present invention uses a crystalline polyester copolymer having good electrical insulation properties and no metal contact deterioration for the insulating layer (1), and is flexible and recoverable. A mixture of a polyetherester copolymer having good properties and a halogenated polyolefin having excellent flexibility and abrasion resistance is used for the sheath (2) so that the sheath does not come into direct contact with the conductor to prevent oxidative deterioration, and is soft and durable. This is to produce a more reliable curl cord.

Crystalline homopolyesters have excellent electrical and thermal properties, but generally have a high melting point.If this is used for the insulating layer, the so-called curl processability of heat setting the wire in a spiral shape is not good. In order to solve the problem, a crystalline polyester copolymer having good heat setting properties is used. Further, by using a polyester copolymer having a Shore D hardness of 40 or more and 80 or less so as not to hinder the extensibility of the curl cord, a curl cord having excellent workability and excellent functionality can be produced.

Also, when the sheath is extruded and coated on the conductor coated with the polyester copolymer, the polyester copolymer in the insulating layer must not melt. Therefore, the polyester copolymer must have a melting point of 180 ° C. or higher.

The crystalline polyester copolymer of the present invention having a melting point of 180 ° C. or higher has terephthalic acid or naphthalenedicarboxylic acid as a main component as an acid component.
Aromatic dicarboxylic acids other than naphthalenedicarboxylic acid include isophthalic acid, orthophthalic acid, bis (p-carboxyphenyl) methane, anthracene dicarboxylic acid and ester-forming derivatives thereof, and the like. Examples thereof include 1,4-cyclohexanedicarboxylic acid, cyclopentanedicarboxylic acid, 4,4'-biciglohexyldicarboxylic acid, and ester-forming derivatives thereof.

 Preferred are isophthalic acid and orthophthalic acid.

As the alcohol component, ethylene glycol or
Although 1,4-butanediol is a main constituent, glycols other than ethylene glycol and 1,4-butanediol include propylene glycol, neopentyl glycol, 1,5-pentanediol, 1,6-hexanediol, Examples include decamethylene glycol and cyclohexane dimethanol, and preferred are 1,6-hexanediol and cyclohexane dimethanol.

Further, as a copolymer component in the polyester copolymer of the present invention, polylactones may be mentioned, δ-valerolactone, ε-caprolactone, β-propiolactone,
A polyester obtained by subjecting a lactone such as β-2,2-dimethylpropiolactone to ring-opening addition polymerization of a crystalline polyester component or a polyester copolymer obtained by copolymerizing a polylactone can be used.

The polyetherester copolymer used for the sheath (2) has as a hard segment at least one crystalline polyester selected from the group consisting of polybutylene terephthalate, polyethylene terephthalate, polybutylene naphthalate and polyethylene naphthalate, and polytetramethylene. It is an elastic body having at least one kind of polyalkylene glycol selected from the group consisting of glycol, polypropylene glycol and copolyether of these glycols as a soft segment.

Examples of the halogenated polyolefin used for the sheath (2) include chlorinated polyethylene and chlorinated polypropylene.

The mixture of the polyetherester copolymer and the halogenated polyolefin of the sheath (2) may contain a filler or a flame retardant to such an extent that its basic properties are not lost. In particular, those containing flame retardants have high utility value in terms of fire prevention and safety.

(Action) By using a polyester copolymer having a melting point of 180 ° C or higher and a Shore D hardness of 40 or more and 80 or less for the insulating layer, a conductor coating having high insulation resistance can be formed, and a mixture of a polyetherether copolymer and a halogenated polyolefin is formed thereon. A curled cord having a curl setting property and a good curl setting property, excellent appearance, and excellent stretchability and recoverability can be obtained.

(Examples) In order to clarify the effect of the invention, the following curl codes were created, and the appearance as curl codes (setability),
The stretchability, recovery, and the degree of deterioration of the insulating layer and the sheath layer after the heat aging test were evaluated.

For comparison, the results of trial production and evaluation of curl codes of combinations of materials not included in the present invention under the same conditions are shown as comparative examples.

An insulating polymer shown in FIG. 1 was extruded and coated at 250 ° C. on a stranded copper wire having a conductor outer diameter of 0.8 mm to obtain an insulated wire core having an insulating layer thickness of 0.5 mm. Next, a sheath polymer was extruded and coated on the insulated wire core to a thickness of 1.0 mm.
The wire was heated at 170 ° C. for 60 minutes to be curled in a state where the wires were wound around a mandrel having a diameter five times the self-diameter so that the wires were in close contact with each other.

After the wire wound around the mandrel was cooled to room temperature, the mandrel was pulled out, and the appearance of the curl cord (whether the wire was set to the mandrel diameter or the wires were in tight contact with each other) was examined.

An object in which the inner diameter of the curl is not larger than the outer diameter of the mandrel by 2% or more and whose electric wires are closely adhered to each other with no gap was judged as having good setting properties, and the other objects were judged as having poor setting properties. Then, both ends of the curl cord were stretched, and it was determined that the wires had smooth and uniform stretchability without sticking between the wires and good stretchability.

The curl cord was stretched at 50 ° C. to 5 times the natural length L ₀ and held for 10 minutes, and then the length L was measured 5 seconds after loosening to examine the recoverability of the curl cord.

Those having (L−L ₀ ) / L ₀ × 100 smaller than 2.0 (%) were judged as having good recoverability, and those having 2.0 or more were judged as having poor recoverability.

After the curl cord was heated in an oven at 150 ° C. for 10 days, the insulating layer and the sheath layer were taken out and the strength retention was examined. Insulation layer, sheath layer strength retention rate is 70
% Or less was determined as good heat resistance, and less than 70% was determined as poor heat resistance.

Also, after fixing the electric wire before curling on the iron bridge, rub it at a speed of 10 cm / sec while pressing the wear wheel CS-17 of the Taber abrasion tester with a load of 0.1 kg, the number of times until the sheath layer breaks Was measured. Those that were broken after 10,000 times or less were judged to have poor wear resistance, and those that did not break were judged to have good wear resistance.

(Effects of the Invention) According to the present invention, a conductor coated with a crystalline polyester resin having excellent properties as an insulating material, and a sheath material in which a halogenated polyolefin is mixed with a polyetherester copolymer having a medium hardness are soft and wear-resistant. A curl cord excellent in mechanical properties such as properties can be realized.

This new configuration of curl cords eliminates the drawbacks of curl cords of conventional vinyl chloride telephones, for example, which are hardened in cold climates, resulting in poor stretchability and poor recoverability. It can also be used for automotive telephone cords that require heat resistance, and can be used for new applications.

Claims (4)

(57) [Claims] 1. A curled cord in which a conductor covered with an insulating layer (1) is covered by a sheath (2), wherein the insulating layer (1) has a Shore D hardness of 40 to 80 and a melting point of 180 ° C.
The above-mentioned crystalline polyester copolymer is mainly contained, and the sheath (2) has a Shore D hardness of 50 or less and mainly contains a mixture of a polyetherester copolymer composed of a crystalline polyester segment and a polyether segment and a halogenated polyolefin. Characteristic curl code. 2. A crystalline polyester copolymer comprising terephthalic acid or naphthalenedicarboxylic acid as an acid component, ethylene glycol or 1,4-butanediol as an alcohol component, and terephthalic acid as a copolymer component. 2. The curl cord according to claim 1, further comprising an aromatic dicarboxylic acid other than naphthalenedicarboxylic acid and / or a glycol other than ethylene glycol and 1,4-butanediol. 3. The curl cord according to claim 1, wherein the polyester copolymer is a polyester comprising a crystalline aromatic polyester and a polylactone. 4. A polyetherester copolymer comprising: polybutylene terephthalate, polyethylene terephthalate,
One or more polyester components selected from the group consisting of polybutylene naphthalate and polyethylene naphthalate are used as hard segments, and polytetramethylene glycol,
The curl cord according to claim 1, characterized in that the curl cord is an elastic body having as a soft segment at least one polyalkylene glycol selected from the group consisting of polypropylene glycol and copolyethers of these glycols.