JPS62100969A - String heater element - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a novel filamentous heating element that generates electrical heat and a method for manufacturing the same. The present invention relates to a filamentous heating element (and its manufacturing method) that can withstand use.

[Prior art]

Flexible heat-generating wires made of thin metal wires have traditionally been used to keep equipment warm or heated, but they have also become widely used in consumer products such as electric blankets and electric carpets, and will become more popular in the future due to their convenience. The trend is for products to be used more frequently.

Conventionally, resistors made of thin metal wires such as tin-plated copper wires, stainless steel wires, and nichrome wires have been used for these heating elements, but when each of the above products is required to be flexible, For example, a flexible core with a very thin resistance wire wrapped around it in a spiral shape, or a fabric with carbon fixed to it using a resin binder are used.

However, none of these can meet the required performance in terms of bending resistance, abrasion resistance, etc., and they are still too flexible to be used in heating clothing or for the elderly and sick. are lacking, and further improvements are required.

Therefore, various attempts have been made to obtain a filament-like heating body in which a highly flexible filament is coated with carbon particles. For example, JP-A-51. The invention disclosed in Japanese Patent No. 109321 is to swell fibers such as nylon conjugate filaments, impregnate and disperse carbon particles, and heat-treat the fibers to form a filamentous heating body having a positive temperature coefficient of electrical resistance.

As mentioned above, this heating element has a positive temperature coefficient of resistance, so it does not require the use of a temperature control device. It is not possible to provide a stable supply industrially, and there is still a need for improvement.

Another method proposed is to fix carbon particles to the core yarn with a resin binder, but since there is a limit to the amount of carbon particles mixed into the resin, it is difficult to obtain a yarn heating element with low electrical resistance. is completed. In addition, these devices have not been widely used because the conductive layer tends to peel off due to bending, friction, etc. (and the electric resistance of each part of the heating wire is not uniform).

[Purpose of the invention]

Therefore, the present invention improves the conventional problems, has uniform electrical resistance in each part, is highly flexible, has good adhesion between the heating element layer and the core yarn, and is difficult to peel off due to bending, friction, etc. The first object of the present invention is to provide a filamentous heating element that can be stably used for a long period of time and is highly safe in the event of overheating, and a method for manufacturing the same.

Furthermore, a second object of the present invention is to provide a filamentous heating element that can maintain safety by fusing the heating element itself in the event that the heating element overheats, and a method for manufacturing the same.

[Structure of the invention]

To achieve the above object, the filamentous heating element of the present invention has a conductive structure in which multiple carbon particle layers in which carbon particles are dispersed in a synthetic resin are laminated on a core yarn made of spun yarn of synthetic fibers with a definite melting point. It is characterized by forming layers.

Next, each component of the present invention described above will be explained in sequence.

In the present invention, the above-mentioned "synthetic fiber with a clear melting point" means that it does not gradually soften or change in quality when heated, is made of a crystalline polymer, has high strength until it reaches its melting point, This refers to fibers made from thermoplastic synthetic resin that instantly melts when the temperature reaches . A heating element made of such fibers can be made into a safe heating element because it melts instantly and acts as a kind of temperature fuse when localized overheating occurs for some reason. Examples of preferred synthetic fibers include nylon (melting point range = 215
~220”C), Nylon 66 (melting point range: 255-2
60℃), polyester type (melting point range = 255-260
°c), polypropylene type (melting point range = 160-170
°c), polyethylene type (melting point range: 125 to 135 °C)
) and other fibers.

The core yarn used in the present invention is a spun yarn or sheath core yarn manufactured from the above-mentioned synthetic resin in order to have a rough surface structure and improve adhesion to the carbon particle layer.

As the spun yarn used in the present invention, it is preferable to use twine yarns, triplet yarns, etc., and in particular, when triplet yarns are used as a fabric, there is no unevenness in direction, so that a high-quality planar heating element can be obtained. Therefore, it is suitable for use in luxury goods.

In addition, the sheath core yarn used in the present invention is formed by winding cotton-like short fibers around a filament core and processing it, and is a yarn with a spun yarn-like feel and high strength. This material is suitable for carrying out the present invention. The cotton-like short fibers used in carrying out the present invention are preferably synthetic fibers with a definite melting point, but are not limited thereto, and cotton or the like can be used.

Further, there is no particular restriction on the thickness of the core yarn, but a core yarn having a yarn count of 40 to 10 is usually used, preferably 30 to 20.

The synthetic resin used in the present invention maintains stable performance at the temperatures described above, and has adhesive properties, bending resistance,
There is no particular restriction as long as it is a synthetic resin with excellent abrasion resistance, etc., but suitable resins include polyurethane resin,
Examples include polyacrylic resin, butyral resin, and thermoplastic resins are preferred.

As the carbon particles used in the present invention, carbon that is normally commercially available as a powder can be used, and the particle diameter is usually 20 to 40 mμ. The amount used is usually 5 to 1 per 100 parts by weight of the resin solid content.
5 parts by weight are used, preferably 7 to 12 parts by weight.

When the amount is less than 5 parts by weight, the resistance value becomes high and the calorific value per unit volume decreases, and when it is more than 15 parts by weight, the resin content is insufficient, making it impossible to coat uniformly. This is not preferred because mechanical strength such as bending resistance and abrasion resistance decreases.

In the filamentous heating element of the present invention, the heat generating layer of the present invention may be one layer, or may be laminated in multiple layers for the purpose of adjusting the electric resistance value, smoothing the surface, etc. The number of layers to be laminated is not particularly limited, but usually about 2 to 4 layers are used. that time,
For example, in order to improve the surface smoothness of the filament heating element, the concentration of carbon particles dispersed in the synthetic resin layer is 12% by weight and 10% by weight from the innermost layer, and 5% by weight from the outermost layer. It can be decided and implemented as appropriate.

The resistance value of the filamentous heating element of the present invention varies depending on the carbon content in the synthetic resin, the thickness of the laminated layers, etc.
Usually 0.4-0.6mm φ, preferably 0.5-0
．． When 55mI++φ, 07 to 12 to 14
m resistors can be obtained. By further twisting a plurality of filamentous heating elements to make them thicker, it is possible to reduce the resistance value.

The filamentous heating element of the present invention can be manufactured by the following steps. That is, <Preparation process> Preparation of core yarn: Prepare yarn without knots.

Preparation of carbon resin suspension: Melt and suspend the resin and carbon particles in an appropriate solvent, stir well in advance, and place the mixture in a sealed container except for the thread channel to prevent evaporation of the solvent. The viscosity of the suspension varies depending on the type and concentration of the resin, the carbon particle size, the amount of suspension, etc., but it is usually 2.
A range of 0 to 100 Boyes culmness is appropriate.

Coating Step> The core yarn is immersed in the 1U resin suspension in which colloidal carbon is suspended while stirring, and then taken out and passed through a die of a required size to adjust the amount of the suspension applied. In this case, to improve the mechanical strength of the heating element layer,
It is necessary that each single fiber constituting the yarn is sufficiently wetted with the suspension, and for this purpose, it is necessary to control the viscosity and adjust the die diameter. Industrially, it is preferable to employ a method in which the core yarn wound around a bobbin is continuously pulled out using a roller mechanism and submerged in a suspension.

Drying process> The core yarn pulled out from the coating process is then sent to the drying process. Drying can be done by normal ventilation drying, but in order to improve productivity, it is recommended to use various methods commonly used to accelerate drying, such as heating the drying air or heating the product with an infrared lamp. I can do it.

When a plurality of heat generating layers are formed, the heating layer can be formed by repeating the coating process and drying process described above.

<Post-process> The surface of the filamentous heating element obtained as described above is insulated by means similar to that used for coating and insulating electric wires, if necessary. There are no particular limitations on the insulating material used, and if there is a problem with the adhesion to the underlying heating element layer, as a pretreatment,
Techniques normally used in this type of process, such as using an undercoat material, can be used as appropriate.

In the case where the conductive layers described above are laminated, the adhesion of the carbon dispersion layer which becomes the heat generating layer is uniform, and the laminated carbon dispersion layer forms an annual ring shape, achieving uniform current density and preventing local overheating. is prevented and safety is maintained. This is considered to be because the dispersed concentration of carbon particles in each layered portion causes a kind of migration phenomenon.

The filamentous heating element of the present invention thus obtained is highly flexible, has excellent mechanical strength such as bending resistance and abrasion resistance, has a uniform resistance value per unit length of heating wire, and has various It can be advantageously used as a heat generating material for heat generating products. EXAMPLES Hereinafter, the present invention and its excellent characteristics will be specifically explained with reference to Examples.

[Examples 1 to 5 and Comparative Examples 1 to 4] In the present examples, twin threads and triple threads of various resins were used, and filaments of the same material were used as comparative examples.

An ester type polyurethane resin (manufactured by Dainichiseika) containing 10% of carbon particles with an average particle size of 10 μm was dissolved in a mixed solvent of methyl ethyl ketone and DMF at a weight ratio of 80,720 to a concentration of 24%. Dispersion solution (
(hereinafter referred to as "impregnation liquid") was obtained.

Next, each of the spun yarns and/or filament yarns of the various materials shown in Table 1 below was heated at 20°C.
at a speed of 2 m/min.
i? After the filament, the amount of the impregnating liquid applied was adjusted using a die, and the material was continuously passed through a dryer at a temperature of 120° C. to dry and solidify, thereby obtaining a filament coated with a dispersed layer of carbon particles.

The same operation as described above was repeated three times for the filament obtained above to obtain a filamentous heating element of the present invention having three carbon particle dispersed layers laminated thereon. The results of measuring the characteristics of each filamentous heating element thus obtained are shown in Table 1 above. Note that circularity was measured using a microscope, and resin adhesion stability was determined by observation.

(The following is a blank space) From the results in Table 1, it can be seen that a filamentous heating element made of a synthetic fiber with a definite melting point as a spun yarn and a sheath core yarn as a core yarn has the following characteristics.

■ When the heating element becomes overheated due to an abnormal situation, the filamentous heating element melts and cuts, creating a temperature fuse effect.

■ Because the fibers used are thermoplastic, they have high adhesion with the carbon particle binder resin.

■ Spun yarns, especially those using twin yarns, triple twisted yarns, and sheath core yarns as core yarns have a rough surface structure and have high adhesion with resin during coating.
High stability is achieved without the resin flowing down or flowing during heating during manufacturing or when generating heat as a heater.

As described above, the filamentous heating element of the present invention has excellent properties and can be used for various purposes as shown below. In other words, (1) the cold weather clothing field includes rider suits, fishing suits, diaper suits, inner suits, various work clothes, underwear, etc.; (2) the cold weather construction field includes carpets, blankets, and sports lap blankets, railways, Moquettes such as buses, etc.
(3) In the medical field, medical applications using far infrared rays include Supporter-1 belly band, so-called silver industrial products such as mats, medical sheets, (4) In the field of household heating materials, gloves, shoes, socks, cushions, etc. 5) Floor materials, kotatsu materials, etc. as heating building materials; (6) Heat insulation for OA equipment, automobile instruments, etc. as electrical materials; (7) Heat generation for various uses such as hotbed sheets, curing sheets, etc. as agricultural and civil engineering materials. It can be advantageously used as a raw material.

〔Effect of the invention〕

As described above, the filamentous heating element of the present invention uses a spun yarn made of synthetic fibers with a distinct melting point as the core yarn, and has a structure in which a carbon particle layer is formed around the core yarn, thereby achieving the following effects. is obtained.

■ Safety is ensured by melting and cutting during abnormal heat generation (heating), creating a so-called temperature fuse effect.

■ The use of fibers made from thermoplastic synthetic resin improves the adhesion with the carbon dispersion layer and the processability of the filamentous heating element.

■ Because the core yarn is a spun yarn, the surface of the yarn has a rough structure, and the amount of carbon particle suspension (impregnating liquid) that adheres to it increases.
Achieves low resistance and improves safety by preventing flow during heating.

■ By repeating coating, the surface of the carbon dispersion layer becomes smooth, making it possible to obtain high workability during processing such as weaving and knitting into planar heating elements, which was previously unobtainable. This enables advanced commercialization such as

In particular, when triple-twisted yarn is used as the core thread, the cross-sectional shape of the resulting thread-like heating element becomes circular with no directionality, which further reduces the coefficient of friction, making it suitable for producing high-end products. It can be a body.

■ Each layer of the carbon dispersion layer has a dense structure, which not only improves various mechanical strengths and provides durability, but also makes it possible to obtain strands with a low resistance value, which was not possible with conventional products of this type. can.

(2) Furthermore, since the carbon dispersed layer has a positive temperature coefficient of resistance, it is safe because it can exhibit self-temperature control.

Claims (3)

[Claims] (1) A conductive layer consisting of a carbon particle layer in which carbon particles are dispersed in a synthetic resin is formed around a core yarn made of spun yarn or sheath core yarn of synthetic fibers having a definite melting point. filiform heating element. (2) The filamentous heating element according to claim 1, wherein the spun yarn is a double yarn. (3) The filamentous heating element according to claim 1, wherein the spun yarn is triple twisted yarn.