JPS6366889A - Filament heater - Google Patents

Abstract

(57) [Abstract] 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 an electrically heat-generating thread-like heating element that is highly flexible and durable for long-term use.

(Prior art) Flexible heat-generating wires made of thin metal wires have traditionally been used for heat insulation or heating of equipment, but they have also become widespread, especially for electric blankets and electric carpets for consumer use. Due to convenience, there is a trend toward diversification of equipment products in the future.

Conventionally, resistors made of thin metal wires such as 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, flexible The wires used include those with a very thin resistance wire wound in a spiral around the core, and wires with carbon fixed to the core using a resin binder.

However, none of these can meet the required performance in terms of bending resistance, abrasion resistance, etc., and it is still difficult to use them for heating clothing or seats for the elderly and sick.
Flexibility is lacking, and further improvements are required.

As an attempt to obtain a filamentous heating body with high flexibility, there is, for example, Japanese Patent Application Laid-Open No. 109321/1983. This is made by swelling the surface layer of fibers such as nylon conjugate filaments and impregnating and dispersing them with carbon particles to form a filamentous heating body. The resistance value of this heating element varies widely depending on the degree of impregnation, and the required resistance value cannot be stably supplied industrially.

(Problems to be Solved by the Invention) The present invention improves these conventional problems and has excellent flexibility, good adhesion between the heating element layer and the core yarn, and is difficult to peel off due to bending, friction, etc. It is necessary to provide a filamentous heating element that can be used stably for a long period of time.

(Means for Solving the Problems) The filamentous heating element of the present invention has the following features: (1) A core yarn made of synthetic fibers that do not have a clear melting point is covered with a flexible synthetic resin containing conductive particles dispersed therein. A filiform heating element characterized by:

(2) The filamentous heating element according to claim (1), wherein the synthetic fibers having no definite melting point are polyfluoroethylene fibers or aromatic polyamide fibers.

(3) Claim No. 1, wherein the conductive particles are at least one selected from carbon black and metal powder.
) is the filamentous heating element described in item 2.

The core yarn of the present invention uses a yarn made of synthetic fibers that do not have a clear melting point.

Such synthetic fibers may be filaments, staples, or a mixture thereof. Thermal fibers, crimped fibers, mixtures of these fibers with a difference in crimping, and even non-crimped fibers may be used. In some cases, such fibers may be mixed with natural fibers. In short, the core thread can also be used as a thread.
Further, the single fiber is preferably selected as long as it has a shape that can easily support the synthetic resin containing conductive particles, for example, a shape such as a spun yarn that has many voids and fluff and exhibits an anchoring effect.

Examples of the synthetic fibers constituting such fibers include aromatic resins and thermosetting resins, such as aromatic polyamide fibers, fluororesin putts such as polytetrafluoroethylene fibers, and polyamide-imide fibers. Fibers, polyimide fibers, polysulfide fibers, polysulfone fibers! ! Examples include fibers, polyacrylonitrile fibers, etc. When a filamentous heating element is constructed from a core yarn made of such fibers, a durable heating element that is free from fusing due to temperature can be provided.

In order to further improve adhesion to the carbon particle layer, these fibers may be employed as they are, in the form of threads, or in the form of yarns such as spun yarn or sheath core yarn. For example, in the case of twisted yarn, triple twisted yarn has the characteristic that when it is made into a fabric, there is no direction unevenness and a high-quality planar heating element can be obtained. Furthermore, it is also preferable to previously treat the core yarn with a substance that has high adhesiveness between the conductive particle-containing synthetic resin and the fibers to provide an adhesive layer.

The synthetic resin to be mixed with the conductive particles of the present invention is not particularly limited as long as it maintains stable performance against temperature and has excellent adhesiveness, bending resistance, abrasion resistance, etc., but is suitable. Examples of resins that can be used include urethane resins, acrylic resins, butyral resins, etc., and those that are particularly flexible are preferably selected.

Typical conductive particles of the present invention include, for example, total bending particles and carbon particles, but any type of particles may be used as long as they are conductive. For example, as the carbon particles, it is possible to use carbon that is usually commercially available as a powder, and the particle size is usually 20
~40 mμ is used. The amount used can be changed as appropriate depending on the desired resistance value. For example, in normal cases, 5 to 15 hand-hanging parts per 100 parts by weight of the resin solid content,
Preferably 7 to 12 parts by weight are used.

If it is less than 5 parts by weight, the resistance value will be high and the calorific value per unit volume will tend to decrease, and if it exceeds 15 parts by weight, it will be difficult to form a uniform flexing resistance and durability. Mechanical strength such as friction properties tends to decrease.

In the filamentous heating element of the present invention, preferably two conductive particle layers are provided.
Laminate multiple layers of ~4 layers.

In that case, the concentration of carbon particles dispersed in the synthetic resin layer can be changed for each layer as necessary. For example, in order to increase the surface smoothness of a filamentous heating element, 12 wt. ω% and 10 wt. 6. The outermost layer can be appropriately determined and implemented, such as by setting the outermost layer to 5-fold ω%.

The resistance value of the filamentous heating element of the present invention can be appropriately set depending on the carbon content in the synthetic resin, the thickness of the laminated layers, etc. For example, in the case of the above formulation, 0.4 to 0.
When the diameter is 6 mm, preferably 0.5 to 0.55 mm, a resistor of approximately 12 to 14 mm can be obtained. However, if necessary, it is also possible to obtain a resistor with a length of 1 to 100.07 m. Usually 07m between 10 and 20
This resistor is useful. In any case, the conductive particles and the synthetic resin to be mixed therewith can be selected depending on the purpose. It is also possible to reduce the resistance value by further twisting a plurality of filamentous heating elements to make them thicker.

An example of the method for producing the filamentous heating element of the present invention will be described below. Immediately, <i%1', preparation process> Preparation of core yarn: A yarn made of synthetic fiber without a definite melting point and without knots is prepared.

Preparation of resin suspension of carbon particles: In a suitable solvent,
)'fi is usually dissolved so that the solution viscosity is 20 to 100 boids, carbon particles are suspended in this, and the mixture is stirred well in advance and placed in a container closed except for the thread path to prevent evaporation of the solvent. Put it in. The viscosity is appropriately selected in consideration of workability within a range in which carbon particles do not settle.

Coating Step> The core yarn is immersed in the resin suspension in which carbon particles are suspended while being stirred, and then taken out and passed through a die of a required size to adjust the amount of the suspension to be adhered. In this case, in order 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. adjustment is necessary. 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 sent to the next drying process. For drying, normal ventilation drying may be used, but in order to improve productivity, various methods commonly used to accelerate drying may be used, such as heating the drying air or heating with an infrared lamp. .

It is preferable that the electrically conductive layer thus formed is laminated a plurality of times, preferably three times. Specifically, the coating step and the drying step are repeated a predetermined number of times to form a layer of carbon particles dispersed in a synthetic resin on the core yarn in the shape of annual rings. At this time, it is preferable to perform sufficient drying in the previous step so that the resin layer formed in the previous step is not redissolved in the solvent.

Of course, when the dispersion concentration of carbon particles or the type of resin in each layer to be laminated is different, even when the dispersion concentration of carbon particles is the same, when carried out industrially, generally the impregnation liquid for each lamination process is different. It is more efficient.

Post-process> The surface of the filamentous heating element obtained above is insulated in the same way as an electric wire is coated and insulated, 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, this type of process is usually used, such as using an undercoat as a pretreatment. Any technique used can be used as appropriate.

The filamentous heating element of the present invention obtained by GPT 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.

Hereinafter, the present invention will be specifically explained with reference to Examples.

(Example) Example 1 A polyester urethane resin (Dainichiseika Products) containing 10% by weight of carbon particles with an average particle size of 40 mμ was added to a mixed solvent of methyl ethyl ketone and DMF at a ratio of 80:20 at a concentration of 24. It was uniformly dissolved (impregnated liquid) so that the weight % was maintained.

The viscosity of this carbon suspension solution was measured with a B-type viscometer and was 45 poise at 30'C.

While stirring the above-mentioned impregnating liquid, a No. 20 double-ply spun yarn (0.56 mmφ) of aromatic polyamide fiber (“Kevlar” manufactured by DuPont) was immersed in it at 20° C. at a speed of 2 m/min. - The amount of thread attached was adjusted using a die with a diameter of 0.6 mm. The die used was made of stainless steel, and the thread hook was of the type that could sometimes be divided into two parts. Then, the yarn was continuously passed through a drying chamber adjusted to 120'C to dry and fix a layer of carbon particles dispersed in urethane resin around the core yarn.

The second stage treatment was carried out using exactly the same method as the first stage drying and fixing process. However, the diameter of the die at this time is 0.7
mmφ was used. Furthermore, the third stage processing was carried out in exactly the same manner as the first and second stages. The diameter of the die at this time is 0
．． It was 8mff1φ.

This filamentous heating element has a carbon layer shaped like an annual ring, and has 9 laminated layers!
It was confirmed that the surface roughness was small due to the U process, the surface was smooth, and the coefficient of friction was small.

(Effects of the Invention) The present invention provides a thread-like heating element that is highly flexible, has good adhesion between the heating element layer and the core yarn, is difficult to peel off due to bending, friction, etc., and can be used stably for a long period of time. As a result, it has been possible to provide a heating element that can be knitted and woven and can be applied to various uses such as the clothing field, construction field, agriculture, fisheries, and civil engineering field.

It can be suitably applied as a heated seat in vehicles such as cars, trains, aircraft, ships, and space rockets.

Claims (3)

[Claims] (1) A filamentous heating element characterized in that a core yarn made of synthetic fibers having no definite melting point is covered with a flexible synthetic resin containing conductive particles dispersed therein. (2) The filamentous heating element according to claim (1), wherein the synthetic fibers having no definite melting point are polyfluoroethylene fibers or wholly aromatic polyamide fibers. (3) The filamentous heating element according to claim (1), wherein the conductive particles are at least one selected from carbon black and metal powder.