JPH066475Y2 - Cord heater - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial field of application> The present invention relates to a cord-shaped heater. Cord-shaped heaters are used for hot carpets, heat retention for electronic jars, defrost heaters for electric refrigerators, etc., but the structure is such that a resistance heating wire is spirally wound around a cord-shaped winding core and insulating resin is applied on top of it. Extrusion coated structure, if necessary,
The resistance heating wire is wound in multiple layers, and the temperature sensitive wire is further wound into a sensor. In any case, the winding core, as a tension member, is related to the strength of the cord-shaped heater and the workability at the time of manufacturing the heater.

<Prior Art> Conventionally, polyethylene terephthalate fiber (commonly called polyester fiber) or glass fiber has been used as a core, but it is necessary to make the core material thin and to reduce obstacles during processing. As described in JP-B-60-9279, it has been attempted to use an aromatic polyamide fiber which is a high modulus heat-resistant fiber as a core material. By using this fiber, the low modulus of the polyester fiber can be covered, and as a result, the cord-like body of the winding core can be made thin, and there is an advantage that the feeling of strangeness due to the thickness of the cord can be reduced especially in the hot carpet. . At the same time, there is also an advantage that fluffing caused by breaking of the single fiber when winding the resistance heating wire, which is a drawback of using glass fiber, can be reduced.

<Problems to be Solved> As described above, although aromatic polyamide fibers (commonly called aramid fibers) have less fuzz than glass fibers, they are still unsatisfactory. Furthermore, aramid fiber is a fiber with high hygroscopicity, specifically 20 ° C ×
Moisture absorption of 10% is reached under 95% RH. This has a big problem as an electric material. That is, when the temperature sensitive wire is introduced into the heater as a sensor, the sensor is affected by the temperature, and therefore the presence of the hygroscopic material is inappropriate. Therefore, it is necessary to use polyester fiber or glass fiber, which is a fiber material with low moisture absorption, even if the workability is poor.

Regarding the occurrence of fluff, if the single fiber is thickened, the fluff can be reduced, but in the case of the aramid fiber produced by the wet solution spinning method, it is quite difficult to make a thick one until the occurrence of fluff is reduced. is there.

<Means for Solving Problems> As a result of earnest research on a fiber material having low hygroscopicity and excellent processability, the present inventor has found that it is an unheated spun raw yarn after melt spinning of wholly aromatic polyester fiber. These problems could be solved by using a non-heat resistant fiber as the core.

Like polyethylene terephthalate fiber, wholly aromatic polyester fiber has a low hygroscopicity and has a hygroscopicity of 1% or less even at 95% RH at 20 ° C because it is made of a polymer with an ester bond. This property is due to the raw material polymer and is a performance that cannot be obtained with the aramid fiber.

The wholly aromatic polyester referred to herein is a polymer obtained by condensation by adding one or more aromatic hydroxy acids, optionally an aromatic diol or an aromatic diacid, and a melt-processable polyester, It is called wholly aromatic in the sense that at least one aromatic ring in the raw material components used contributes to the polymer main chain.

Of these wholly aromatic polyesters, hydroxybenzoic acid, especially p-hydroxybenzoic acid and 6-hydroxy-
Polyester with 2-naphthoic acid, or even p,
In addition to polyesters copolymerized with p'-bisphenol as the third component, polyesters composed of p-hydroxybenzoic acid, p, p'-biphenyl, terephthalic acid and / or isophthalic acid are useful, but are not limited thereto. However, it does not hinder the introduction of other components into the polymer as long as the object of the present invention is not impaired.

The melt-spun raw yarn made of wholly aromatic polyester has a melting point and a fiber strength of about 11 g / d, which is lower than 21 g / d of aramid fiber. Therefore, spun raw yarn in an inert gas or air at 300
It is also a characteristic of all aromatic polyesters that the strength is usually doubled or more when heat-treated at a temperature close to ℃. Heat treatment increases strength and elongation, but module does not change.

It is not necessary to use wholly aromatic polyester fiber after heat treatment as the fiber of the core of the present invention. This is because even ordinary polyester fibers having a melting point of 240 ° C. are not thermally problematic, non-heat-resistant fibers are sufficient, and therefore non-heat-resistant wholly aromatic polyester fibers before heat treatment are also sufficiently satisfied. Even with a fully aromatic polyester spun yarn, the modulus of the fiber is high at about 600 g / d, the requirements for making the core thin are satisfied, and the strength is also 7 g / d or more, which is the same as ordinary polyester fiber, sufficient. Is.

Generally, wholly aromatic polyester fiber has the following physical properties In particular, a monomer containing a copolymer of p-hydroxybenzoic acid and 6,2-hydroxynaphthoic acid as a main component has the following physical properties.

Heat treatment of wholly aromatic polyester spun yarn is 20 ~
Although it is carried out under a temperature condition of 30 ° C. lower, it is close to the melting point, so that there is a problem that the filaments stick to each other during the heat treatment and the yarn becomes a tape. Therefore, in order to use the thus-glued fibers as a core, it is necessary to twist the filaments to remove the glue of the single fibers so that the cross-section of the core is circular. On the other hand, when the spun raw yarn itself is used for the winding core, heat treatment is not performed, so naturally there is no single fiber sticking,
Can be used as a winding core without the twisting process,
Can be streamlined. Furthermore, the non-sticky yarn has less fluffing and has good workability.

The wholly aromatic polyester fiber used in the winding core of the present invention may be mixed with other fibers within a range that does not impair the effects of the present invention.

With respect to the structure of the winding core, the resistance heating wire, the covering body, and the like which compose the cord-shaped heater of the present invention, those generally used can be applied. For example, as the winding core, a cord having a total denier of 500 to 2000 denier by combining fibers of 3 to 10 denier is used. As the resistance heating element, nickel chrome wire, copper wire, copper nickel wire, etc. are generally used, and the thickness thereof is preferably 0.05 to 0.3 mm of straight yarn. Examples of the resin used for the insulating coating include vinyl chloride resin, silicon resin, fluorine resin, urethane resin and the like.

Next, the present invention will be specifically described by way of examples.

Example 1 A melted liquid crystal polymer composed of a copolymer of p-hydroxybenzoic acid and 6-hydroxy-2-naphthoic acid was melt-spun to obtain a spinning dope of 1000d / 200f. Powerful
The tensile modulus was 11 kg (strength 11 g / d), the breaking elongation was 1.5%, and the Young's modulus was 600 g / d. 1000d without twisting this yarn
Use one to make the core. 0.1mm as resistance heating wire
A nickel-chromium wire was wrapped around it and then covered with a soft vinyl chloride resin insulator to make a cord-shaped heater. This cord-shaped heater was cut into 1 m and the resistance value was measured under a load of 1 kg, but it was almost the same as the resistance value under no load. Almost no fluff was observed. Furthermore, the cord of this thickness does not give a feeling of strangeness when used for a hot carpet.

[Brief description of drawings]

FIG. 1 is a plan view of a partly cutaway portion of the cord-shaped heater. In the figure, 1 is a cord-shaped winding core, 2 is a resistance heating wire, and 3 is a coating resin layer which is an insulator.

Claims (2)

[Scope of utility model registration request] 1. A cord-shaped heater in which a resistance heating wire is wound around a cord-shaped winding core of a fiber and further covered with an insulating material, and the fibers constituting the winding core are formed by melt-spinning the wholly aromatic polyester fiber. A cord-shaped heater characterized by being a heat treated spun yarn. 2. The cord-shaped heater according to claim 1, wherein the wholly aromatic polyester fiber is substantially a polyester synthesized from P-hydroxybenzoic acid and 6-hydroxy-2-naphthoic acid.