JPS63270866A - Production of yarn like heat generator - 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 Field of Application] The present invention relates to a method for producing an electrically heated filamentous heating element that is highly flexible and durable for long-term use.

[Conventional technology]

Traditionally, flexible heating wires made of thin metal wires have been used to keep equipment warm or heated, but electric blankets,
It has become widely used in consumer products such as electric carpets, and due to its convenience, there is a trend that products will become more diversified 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 Some examples include those in which ultra-thin resistance wire is spirally wound around a synthetic core thread, and those in which carbon is fixed to a fabric using a resin binder.

However, none of these materials can satisfy the required performance in terms of bending resistance, abrasion resistance, etc., and also lacks flexibility, so improvements are required.

Tokkosho, 38-
There is a publication No. 1470. This increases the flexibility of the heating element by providing a rubber or plastic layer containing conductive fine particles around the core yarn. This manufacturing method is that of electric wire manufacturing, and requires large-scale equipment consisting of a conductive rubber or plastic heating and melting section, a heat-insulating piping section, and a melt-coating section. The melt-coated portion is provided with two pores each having a diameter of 11 or less for introducing and extracting the core yarn, and is kept at a high temperature to the extent that rubber or plastic has fluidity. Therefore, the operation of passing the core yarn through the two pores is very difficult. Although this invention has improved the level of flexibility compared to thin metal wires, it also
The flexibility level is extremely low for fields that require a high degree of bending durability, such as inner suits, gloves, shoes, and electric blankets, and it has not yet been put to practical use.

In addition, Japanese Utility Model Publication No. 39-37687 discloses that a resin containing conductive fine particles is made into a solution, applied to a core yarn, and then the solvent is removed.
A method of fixing is disclosed. The application means,
This is a method in which the core yarn is immersed in a solution and then excess solution is removed using pores, slits, etc., and the equipment is simplified and the operability is improved somewhat compared to the above-mentioned melt coating method.

However, in the heating element obtained by this method, since the solution cannot be applied uniformly, temperature unevenness occurs when electricity is applied, and there is even a risk of causing burns or fire. Therefore, this method is not recognized as an appropriate method for producing filamentous heating elements.

In an attempt to obtain a highly flexible filamentous heating element, for example,
There is Japanese Unexamined Patent Publication No. 109321/1983. This proposed a filament-like heating element and its manufacturing method in which carbon particles were fixed to the surface layer of the filament by softening the nylon conjugate filament by heating or swelling it with a swelling agent. This heating element has too high a resistance value per length, is not suitable for use as a heating element, and has a complicated manufacturing method. Furthermore, it is difficult to uniformly fix the carbon particles, and therefore the resistance value varies widely, making it impossible to industrially and stably manufacture the required resistance value.

[Problem that the invention seeks to solve]

The present invention solves these conventional problems and provides a filament-like heat generating material that is highly flexible, has good adhesiveness between the conductive layer and the core yarn, is difficult to peel off due to bending or abrasion, and can be used stably for a long time. The present invention provides a method for manufacturing a body with stable operability.

[Means for Solving the Problems] In order to solve the above problems, the method for manufacturing a filamentous heating element of the present invention has the following configuration. That is, a synthetic resin solution in which conductive fine particles are suspended is measured by a metering device, and the core yarn is introduced into the pores of a coating device, and at the outlet of the pores, it joins and adheres to the synthetic resin solution, and is then dried and fixed. A method for producing a filamentous heating element is characterized in that a conductive layer of a synthetic resin solution containing conductive fine particles dispersed therein is formed on the core yarn.

Measuring a synthetic resin solution in which conductive fine particles are suspended,
It is important to cover the core yarn with the measured synthetic resin solution from the periphery of the core yarn in order to ensure a stable resistance value with little variation as a filamentous heating element.

As the coating device for coating, it is preferable to use a device consisting of a core metal nipple through which the core thread runs and a die that guides the resin solution.

It is preferable that the inner diameter D1 of the nipple and the inner diameter D2 of the die be set so as to satisfy the following formula, and that the device is combined so that the core metal and the cap have substantially the same center line.

d+0.05 ≦D1≦d+0.4 (All units are M1) Note that d is the apparent diameter of the core yarn, and in the case of multifilament, the calculation was performed assuming monofilament with the same total denier. The inner diameter D1 of the nipple is d+0.0
If it is too small than 5, the threadability of the core thread will deteriorate and the core thread will tend to become fluffy, and if it is too large than d+0.4, the synthetic resin solution will tend to flow back into the nipple area, which is not preferable.

If the inner diameter D2 of the die is less than the inner diameter D1 of the nipple, the core thread will easily come into contact with the inner wall of the die, and the impregnated resin solution will be squeezed out at the exit and will tend to accumulate around the die exit.
The core yarn tends to become fluffy. Also, the inner diameter D2 is 2. If it is too large than O#, uneven discharge of the synthetic resin solution from the die tends to occur, which tends to cause variations in coating thickness, that is, variations in resistance value.

As the material for the core thread used in the present invention, thread-like synthetic fibers or natural fibers are used. It is sufficient that it maintains stable performance for a long period of time at the temperature normally used as a heating element, that is, in the range of 20 to 100°C, and that it has good adhesion to the conductive layer.

Thermoplastic synthetic fibers such as polyamides, polyesters, and polyolefins are non-hygroscopic and chemical resistant, and are less prone to thermal deterioration in the above temperature range, as well as being eluted by heating in the event of localized abnormal heating. This is preferable because it has a fuse function. Furthermore, by using heat-resistant fibers such as aromatic polyamide, polybenzimidazole, polyphenylene triazole, polyoxadiazole, polyimide, and thermosetting resin fibers, the usable temperature range can be increased and the product life can be significantly extended. It is preferable because it has advantages such as:

The form of the core yarn used in the present invention is preferably one that has good contact with the conductive layer and is difficult to peel off. For example, spun yarn and double-structured yarn with short fibers on the surface layer have fluff on the fiber surface, so they absorb synthetic resin well, and after becoming a thread-like heating element, the conductive layer is attached to the surface of the core yarn and the fluff. Good tangle adhesion. Moreover, for this purpose, it is more preferable to use a bulky textured yarn as the core yarn. Furthermore, the bulky textured yarn may be subjected to interlacing treatment or heated.

In this case, the synthetic resin solution adhering to the core yarn penetrates into the interior of the core yarn due to the bulkiness of the core yarn, and is dried and fixed as it is.

Because the bulky processed yarn has crimps, the contact area with the resin solution is large, and since there is little fluff on the fiber surface, there are no thick parts or protrusions derived from fluff in the yarn axis direction after drying and fixation, resulting in high-quality It is also preferable from the viewpoint of good workability.

It is also preferable to treat the core yarn in advance with a substance that has high affinity for both the conductive fine particle-containing synthetic resin and the core yarn.

The synthetic resin containing dispersed conductive fine particles used in the present invention is not particularly limited, but is preferably used as long as it has heat resistance stability and excellent adhesiveness, bending resistance, abrasion resistance, etc. Examples of resins that can be used include polyurethane resins, acrylic resins, butyral resins, and particularly flexible resins are preferably selected.

As the conductive fine particles used in the present invention, for example,
Carbon particles and metal particles are representative examples. Various carbon blacks can be used as the carbon particles, and the particle size is 1 to 5 () Om.
It is preferable to use a particle having a particle size of 10 to 200 μm. Further, graphite can be used as the carbon particles, and as the graphite, natural graphite, that is, phosphor graphite, flaky graphite, globular graphite, or artificial graphite with a size of 1 to 100 μm is preferably used. However, especially phosphorous graphite or scaly graphite 5 to 5
Those with a size of 0 μm are preferably used. It is also preferable to use a mixture of carbon black and graphite as the carbon particles. The type of carbon particles used can be changed as appropriate depending on the desired resistance value. For example, in order to obtain a resistance value suitable for a heating element, carbon particles are usually used in an amount of 5 to 25% by weight, preferably 7 to 15% by weight, in the resin solution.

The resistance value of the filamentous heating element of the present invention can be appropriately set depending on the content of carbon particles dispersed in the synthetic resin, the thickness of the laminated layers, etc. For example, in the case of the above formulation, a resistance value of 1 to 100.07 m can be obtained. The volume resistivity of the resin at this time depends on the thickness of the thread, but is approximately 0.01 to 10Ω. The conductive fine particles and the synthetic resin used in combination with the conductive fine particles 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. The heating layer of the filamentous heating element of the present invention may have a thickness of 1M, but may be laminated in multiple layers for the purpose of adjusting the electrical resistance value, smoothing the surface, etc. There is no particular restriction on the number of layers to be laminated,
; Normally, one to three layers of lamination may defeat the purpose. that time,
The concentration of carbon particles dispersed in each heating layer can be changed, for example, in order to improve the surface smoothness of the filamentous heating element.

For example, the content may be 12% by weight, 10% by weight from the innermost layer, 5% by weight from the outermost layer, etc.

However, it is industrially preferable to deposit the amount in one go.

In the method for producing a filamentous heating element of the present invention, air bubbles are present in the conductive synthetic resin layer covering the core yarn. The presence of air bubbles can dramatically improve the flexibility and repeat durability.

Further, according to the present invention, the weight variation Cv in the yarn axis direction can be reduced to 6.
0% or less, and a thread-like heating element with the core thread located almost in the center of the conductive layer can be created, resulting in a product with excellent flexibility and performance comparable to products made of conventional thin metal wires. be satisfied.

That is, the resistance value variation can be brought to a practical level.

An example of the method for producing the filamentous heating element of the present invention will be described below.

<Preparation process> Preparation of core thread: Prepare thread without knots.

Preparation of resin suspension of conductive fine particles: A synthetic resin solution is prepared by dissolving and suspending the resin and conductive fine particles in an appropriate solvent. At this time, it is preferable to adjust the viscosity of the synthetic resin solution to 2 to 200 voices in terms of uniform adhesion and the discharge effect of the metering device. In addition, it is preferable to adjust the solid content of the synthetic resin solution, that is, the proportion of W other than the solvent, to 10 to 50% by weight from the viewpoint of energy saving in the drying process after deposition and workability in the suspension/dissolution process.

The synthetic resin solution is sealed in a closed container to prevent evaporation of the solvent.

The solution contains a large amount of fine particles, and if left alone,
Due to the structural viscosity, the viscosity of the solution increases rapidly, causing adverse effects such as a decrease in pump efficiency. In order to prevent this, it is preferable to keep the solution constantly flowing, especially to stir it.

(Measuring and adhering step) The synthetic resin solution in which conductive fine particles are suspended is transferred from the closed container to a measuring device through piping while stirring.A known metering pump, particularly a gear pump, is suitably used as the measuring device. One of the purposes of the present invention is to reduce the variation in the resistance value of the strands, but by measuring the synthetic resin solution using a measuring device and making it adhere to the core yarn, the amount of adhesion in the axial direction of the strands can be reduced. It has become possible to extremely reduce variations.

The measured synthetic resin solution is roughly transported through piping to the coating device. The coating device used is, for example, the one shown in FIG. 1, in which the core yarn 4 is introduced into the pores, and at the outlet of the pores, it joins and adheres to the synthetic resin solution introduced from the inlet 1. The coating device is composed of a core metal 2 through which the core thread runs and a cap 3 through which the resin liquid is introduced.

As a result, a strand 8 is formed in which the periphery of the core thread is completely covered with the synthetic resin solution.

In order to reduce variations in the amount of adhesion, it is preferable to feed the core yarn to the adhesion device at a constant speed.

For this purpose, a method is preferably used in which the yarn is fed and taken up by a roller before the adhering device and after the drying step described below. In order to adhere with appropriate tension, it is also preferable to use front and rear rollers to create a tensioned state.

<Drying process> The core yarn pulled out from the weighing and attaching 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. .

The thus obtained filamentous heating element of the present invention has extremely low variation in the amount of resin deposited in the direction of the filament axis because the synthetic resin solution is uniformly adhered thereto.Also, since the filamentous heating element employs a dry fixation method, the filamentous heating element It has air bubbles inside and is highly flexible, has good adhesion between the heating element layer and core yarn, has excellent mechanical strength such as bending resistance and abrasion resistance, and has a high resistance value per unit length of heating wire. is uniform, and as a result, it can be knitted and woven, and can be advantageously used as a heat-generating material for various heat-generating products in the fields of clothing, clothing, agriculture, fisheries, and civil engineering. Of course, it can be applied to all vehicles such as cars, trains, aircraft, ships, and space rockets.

〔Example〕

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

Note that the viscosity in the present invention was measured by the following method.

(Viscosity) A sample was collected in a soo mQ cylindrical container, and the temperature was 30°C.
The viscosity immediately after production is measured using a BM type rotational viscometer (manufactured by Tokyo Keiki) at ±1°C.

In addition, prior to measurement, the sample is sufficiently stirred using a propeller mixer or a homomixer.

Example 1 Polyester type polyurethane resin (Dainichiseika Kagyo Co., Ltd.)
f4) After uniformly dissolving in a mixed solution of methyl ethyl ketone and dimethyl formamide (weight ratio 80:20) to a concentration of 18% by weight, carbon black with an average particle size of 40 mμ and graphite with an average particle size of 8.8 μm were dissolved in carbon. The synthetic resin solutions were adjusted to have a mold content of 7% and 5%, respectively, based on the suspension solution. The viscosity of this solution was 35 voids and the solid content was 27% by weight. For the core yarn, polyester was spun at a spinning speed of 3000 m/min, and then drawn and pre-twisted using a conventional method.Then, the torque was reduced using a hot plate at 190°C to create a 150-denier, 96-filament trilobal cross-section pre-twisted yarn. Obtained.

Four of these threads were combined to form a core thread. The density of the core yarn is 1.3
85, the apparent diameter of the core yarn is d-0.25 m.

The synthetic resin solution was sealed in a sealed container, stirred, and transferred from the sealed container to a deposition device using a gear pump with a capacity of 0.017 cc per rotation. The deposition device is the first
Using the diagram, set the inner diameter of the nipple to 0.4Mφ and the inner diameter of the die to 0.
．． It was set to 55 mφ.

The solution was filled and supplied into the gap between the nipple and the die through eight discharge holes at a discharge rate of 0.491 CC/min, and adhered to the core yarn from the periphery. The core yarn was sent to the adhesion device at a constant speed by a roller with a circumferential speed of 2 m/min.

The thread tension just before the applicator was 105 g. After the deposition device, the solvent was evaporated using a heating cylinder with a length of 2.5 m installed at position 15 (J).At this time, the temperature of the inner wall of the heating cylinder was set to 190°C to accelerate the evaporation of the solvent and promote foaming. The solidification of the synthetic resin solution was accelerated to allow air bubbles to be incorporated into the heat generating layer.In this way, the synthetic resin containing dispersed conductive particles was fixed to the core thread, and then pulled by a roller at a circumferential speed of 2 m/min. I took it.

When the obtained filamentous heating element was continuously measured using 40 mold openings of 25 cm each in the filament axis direction, the average value was 0.034 (J
/25CIn, standard deviation 0.00051, and the CV value obtained by dividing the standard Q deviation by the average value was 1.5%. In addition, when the resistance value of the same thread was measured, the average value was 4.15Ω/25c.
m, standard deviation was 0.125, and Cv value was 3.0%.

From this, it was found that the method of the present invention allowed the synthetic resin solution to adhere uniformly in the yarn axis direction, and thus the variation in the resistance value of the filamentous heating element became extremely small.

A fabric-like heating element obtained using the thread-like heating element will be explained with reference to FIG. The fabric-like heating element 15 shown in the figure uses an electric electrode wire 16 made of tin-plated copper wire and a polyester thread 17 for the warp, and the thread-like heating element 8 and a polyester thread 18 for adjusting the amount of heat generated for the weft. A fabric-like heating element was made using ordinary weaving. Both sides of the fabric were coated with polyethylene for the purpose of providing a rough insulation coating. Further, a lead wire 19 through which current is passed was connected to the electrode wire 16 by soldering 20. When electricity was supplied from a Ni--Cd battery to this fabric-like heating element sewn onto the lining of a vest, it was found to be extremely flexible with no local temperature unevenness, and was well received by those who tried it on.

Comparative Example 1 A filamentous heating element was obtained by immersing the core yarn in the synthetic resin solution containing the carbon particles of Example 1 and pulling it out from a nozzle having a diameter of 0.9 m. The weight variation CV is 5.0%, and the resistance value variation C■ is 9.5%. Compared to the case of metered liquid supply, the weight variation C■ is higher, and there is variation in the amount of adhesion. The uniformity of values was poor.

A cloth-like heating element was manufactured in the same manner as in Example 1, and when it was sewn into the lining of a vest and a current was passed through it, local temperature abnormalities occurred, which was unpopular with those who tried it on.

Example 2 In the coating device shown in FIG. 1, the inner diameter D1 of the nipple
and the inner diameter D2 of the die was varied as shown in Table 1.
A filamentous heating element was obtained in the same manner as in Example 1. Table 1 shows the operability. In addition, for all levels except experiment numbers N, 1, 5, and 9.10, the weight variation and resistance value variation as a thread-like heating element are all at the same level as Example 1, and the thread-like heating element has a uniform resistance value. Met. Experiment N, 2
, 3, 4.6, and 7.8 were more preferable because they had stable operability and operability, and had good filamentous heating element characteristics.

(Margins below) Table 1 [Effects of the Invention] According to the method of the present invention, variations in the amount of synthetic resin solution deposited are small and variations in resistance value can be controlled to be small, so temperature variations when manufactured into products can be completely eliminated. You can press it so small that you won't feel it.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an example of a coating device used in the present invention. FIG. 2 is an explanatory diagram of a fabric-like heating element obtained by weaving a thread-like heating element.

Claims (2)

[Claims] (1) While measuring the synthetic resin solution in which conductive fine particles are suspended using a measuring device, the core thread is introduced into the pores of the coating device, where it joins and adheres to the synthetic resin solution at the exit of the pore, and is then dried and fixed. A method for producing a filamentous heating element, comprising: forming a conductive layer of a synthetic resin containing conductive fine particles dispersed thereon on the core yarn. (2) In the coating device, the inner diameter D_1 of the exit portion of the core bar through which the core thread runs and the inner diameter D_2 of the outlet port of the cap that guides the resin solution satisfy the following formula, and the core bar and the cap are substantially centered on the center line. Claim No. 1 (1) characterized in that
) The method for producing a filamentous heating element according to item 1. d+0.05≦D_1≦d+0.4 D_1<D_2≦2.0 However, d=20√{(Fineness of core yarn)/9π×10^5×(Density of core yarn)} (All units are mm)