JPS63270870A - Production of flexible 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 Application Field] The present invention relates to a method for producing an electrically heated filamentous heating element with stable quality, which is highly flexible and durable for long-term use.

[Prior Art] Flexible heating wires made of thin metal wires have been used to keep equipment warm or heated, but electric blankets, electric blankets, etc.
It has become widely used in consumer products such as electric carpets, and due to its convenience, there is a trend of increasing diversification into products.

Conventionally, resistors made of fine metal wires such as stainless steel wires and nichrome wires have been used for these heating elements, but if the above products are required to be flexible, flexible Used materials include those in which ultra-thin resistance wire is wound in a spiral shape around a polyester 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.

An attempt was made to solve this problem by
There is a publication No. 470. This increases the flexibility of the heating element by providing a rubber or plastic layer containing conductive fine particles around the core yarn. but,
The manufacturing method is similar to that used for manufacturing electric wires, and uses 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 1 M or less through which the core thread is introduced and taken out, and is kept at a high temperature to the extent that rubber or plastic has fluidity. Therefore, the core thread is
The operation of passing the tube through two pores is extremely difficult. Moreover, 1q
Although the flexibility level of the heating element has been improved compared to thin metal wire, it can be used in fields such as rider suits, diaper suits, inner suits, gloves, shoes, etc. in the clothing field, and fields that require a high degree of bending resistance such as electric blankets. Due to its low level of bending resistance, it has not yet been put into practical use.

Further, Japanese Utility Model Publication No. 39-37687 discloses a method in which a resin containing conductive fine particles is prepared as a solution, applied to a core yarn, and then the solvent is removed and fixed. Coating is a method in which the core yarn is immersed in a solution and then excess solution is removed using a fine-hole file slit or the like, and the equipment is simpler and the operability is slightly better than in the above-mentioned melt coating method. However, with this method, 1n
In the case of heating elements, the solution cannot be uniformly applied to the thin metal wires, resulting in uneven temperature when energized, which may even cause burns or fires. Therefore, this method is not recognized as an appropriate manufacturing method for filamentous heating elements.

In addition, Japanese Patent Application Laid-open No. 109321/1984 is an attempt to obtain a highly flexible filamentous heating element. This is a method for manufacturing a filamentous heating element by softening a nylon conjugate filament by heating or swelling it with a swelling agent, and fixing carbon particles to the surface layer of the filament. This heating element has too high a resistance value per length and is not suitable for use as a heating element.

In addition, it is difficult to uniformly fix carbon particles, and therefore the resistance value varies widely, making it impossible to stably supply the desired resistance value industrially.

[Problems to be Solved by the Invention] The present invention solves these conventional problems and has excellent flexibility, good adhesion between the N-conducting layer and the core thread, and is difficult to peel off due to bending, abrasion, etc. A method for manufacturing a thread-like heating element that can be stably used for a long period of time in an operationally stable manner and a homogeneous thread-like heating element In order to solve the above-mentioned problems, the production of a thread-like heating element according to the present invention The method has the following configuration. That is, the interior of the box is a box in which a synthetic resin solution in which conductive fine particles are suspended is measured by a measuring device, the passage of the core thread is substantially sealed, and the interior is a highly concentrated vapor atmosphere of at least one solvent of the synthetic resin solution. Adhering to the core yarn through a discharge hole bored in a thread guide for the core yarn provided in the core yarn, and then drying and fixing it to form a conductive layer of a synthetic resin containing dispersed conductive fine particles on the core yarn. A method for producing a flexible filamentous heating element characterized by:

The most important point of the present invention is that a part of the passage of the core thread is substantially sealed, and the inside of the box is a highly concentrated vapor atmosphere of at least one solvent of a synthetic resin solution in which conductive fine particles are suspended. The synthetic resin solution is applied through a discharge hole drilled in a thread guide provided inside the thread guide for the core thread.

First, in the present invention, a thread guide is used as the attachment device. As will be described later, among the objects of the present invention, measured adhesion is essential to the present invention in order to make the resistance value per length uniform. For example, although it is possible to coat the wire uniformly using a device similar to the above-mentioned electric wire manufacturing method, the threadability of the core thread is poor. Moreover, in the method of making the core thread absorb the liquid flowing out of the discharge hole and depositing it, or the method of depositing the liquid in the form of a spray, uneven adhesion occurs. On the other hand, with the method of attaching from the thread guide, threading is extremely easy and the core thread runs directly to the outlet of the discharge hole, so the metered amount of liquid is immediately attached to the core thread and is uniform. Adhesion can be achieved.

However, although this attachment method using a thread guide has no problems in the production of filamentous heating elements for a single period of time, problems may arise in long-term operation. Most of the synthetic resin solution discharged from the adhesion device adheres to the core yarn and is dried and fixed, but some of it adheres to the attachment device, and as the solvent evaporates, solid content is deposited on the adhesion device. . The accumulated solid content gradually extends in the direction of movement of the core thread, creating an "iccicle".
When it reaches a length of 1 to 50 m, it is separated from the adhering device due to friction with the core yarn and carried to the core yarn. Naturally, the yarn in this area dries and sticks while remaining thick and is taken off, which is a serious defect in terms of quality. By using the above-described box of the present invention, evaporation of the solvent is suppressed, "icicles" do not occur, and yarn of good quality can be obtained stably even during long-term operation.

The high-concentration vapor needs to be a vapor containing at least one solvent of the synthetic resin solution, but the solvent can be appropriately selected in consideration of boiling point, saturated vapor pressure at room temperature, heat of vaporization, etc.

Specifically, methods for creating a high-concentration vapor atmosphere include installing a solvent tank for the solvent to be evaporated inside the box, creating a saturated vapor pressure atmosphere inside the box, and heating the solvent tank roughly to promote evaporation of the solvent. A method is preferably used. In these cases, it is necessary to control the level of the solvent. Other methods include a method in which a plate, a grid, or a porous body is provided inside the box and the solvent is circulated through it, and a method in which highly concentrated steam is generated outside the box and the steam flows into the inside of the box.

As the material for the core thread used in the present invention, synthetic fiber or natural fiber thread is used. This is the temperature normally used as a heating element, i.e. for a long period of time in the range of 20 to 100°C.
It is sufficient as long as it maintains stable performance and has good adhesion to the conductive layer. Thermoplastic synthetic fibers such as polyamide, polyester, and polyolefin have good non-hygroscopicity and chemical resistance, and are less susceptible to thermal deterioration in the above temperature range. This is preferable because it has a fuse function of blowing. In addition, by using heat-resistant IIfffi such as aromatic polyamide, polybenzimidazole, polyphenylene triazole, polyoxadiazole, polyimide, and thermosetting resin fiber, 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 such that it has good adhesion with synthetic resin, good absorption of synthetic resin solution, and surface characteristics of the yarn when dried and fixed after absorption, i.e., a smooth surface without protrusions or thick and thin parts. , the cross section of the thread-like heating element is not flat, and when it is made into a thread-like heating element, it has excellent resistance to external forces, such as tensile strength, elongation, initial Young's modulus, bending resistance, and abrasion resistance. It can be selected as appropriate depending on the purpose, taking into account the following.

Specifically, spun yarns, burnt spun yarns, flat yarns, bulky processed yarns, twisted yarns thereof, twin yarns, highly entangled yarns processed with fluid processing such as egg, taslan yarns, and bimetal composite fibers of synthetic fibers. and asymmetric cooling systems.

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 suitable as long as it maintains stable performance against temperature and has excellent adhesiveness, bending resistance, abrasion resistance, etc. Examples of resins that can be used include polyurethane resins, acrylic resins, butyral resins, and particularly flexible ones are preferably selected.

As the conductive fine particles used in the present invention, for example,
Representative examples include carbon particles and metal particles. As the carbon particles, usually various carbon blacks can be used, and the particle size is usually 1 to 5.
00 mμ, and those with a diameter of 20 to 200 mμ are more preferably used.

Also, graphite can be used as carbon particles,
As graphite, natural graphite, ie, phosphorous graphite, flaky graphite, earthy graphite, or artificial graphite with a size of 1 to 100 μm is preferably used, but phosphorous graphite or flaky graphite with a size of 5 to 100 μm is preferably used. A size of 50 μm is more preferably used. It is also preferable to use a mixture of carbon black and graphite as the carbon particles. The amount of carbon particles used can be changed as appropriate depending on the desired resistance value. For example, in order to obtain an appropriate resistance value as a heating element, in the resin solution, 5 to 25% by weight,
Preferably 7 to 15% by weight of carbon particles are used.

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.

This depends on the thickness of the thread, but the volume resistivity is approximately 0°01 to 1.
It is 0Ω·cm. The conductive fine particles and the synthetic resin used in combination with the conductive fine particles can be selected depending on the purpose. By further twisting multiple thread-like heating elements to make them thicker,
It is also possible to reduce the resistance value.

In the present invention, bubbles can be generated in the conductive resin layer by the following means in order to make the filamentous heating element flexible and durable against repeated folding and abrasion. As a means for this purpose, for example, azobisisobutyronitrile (AIB
Incorporating a blowing agent into the suspension, for example using a low boiling point solvent such as methyl ethyl ketone, which causes the solvent vapor to exotherm as the ambient temperature is higher than the temperature at which the solvent is normally evaporated (dryed) after coating. A method of drying under conditions in which the yarn is surrounded by a layer, especially when spinning yarn, especially burning yarn, involves immersing the yarn under conditions in which the air present on the surface of the yarn is not sufficiently replaced with the suspension, causing fine air bubbles to form. This can be achieved by managing the system so that it remains. In addition, when foaming is performed using the above-mentioned AIBN, for example, AIBN is added to the resin dissolved in dimethylformamide in advance.
If the mixture is mixed with N@ and dried at 150°C, it can be foamed by thermal decomposition.

There is no limit to the amount of bubbles mixed in; if there is a small amount, the flexibility of the filament heating element obtained will be on the same level as the material, and if it is large, the flexibility will increase, but if it is too large, the mechanical strength and surface smoothness will be reduced. becomes lower.

Therefore, it is preferable to determine it empirically or experimentally from the physical properties of each material constituting the filamentous heating element.

The heating layer of the filamentous heating element of the present invention may be a single layer, but may be laminated in multiple layers for the purpose of adjusting the electrical resistance value, smoothing the surface, etc. The number of layers to be laminated is not particularly limited, and the purpose can usually be achieved by laminating about 1 to 3 times. At this time, the concentration of carbon particles dispersed in each heat generating layer can be changed, for example, in order to improve the smoothness of the surface of the filamentous photothermal body. As an example, it can be carried out by sequentially setting the innermost layer to 12% by weight, 10% by weight, and the outermost layer to 5% by weight.

However, it is possible to make the metering deposit in one time, and it is more preferable to make it deposit in one time in terms of equipment.

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 1 to 1000 poise from the viewpoint of uniform adhesion and discharge efficiency of the metering device, and more preferably to 2 to 200 poise. In addition, the solid content of the synthetic resin solution, that is, the weight ratio of components other than the solvent, can be adjusted to 10 to 50% by weight.
This method is preferable from the viewpoint of energy saving in the drying process and workability in the suspension/dissolution process.

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

Measuring and Adhesion Step> The synthetic resin solution in which conductive fine particles are suspended is transferred from the sealed container to a measuring device through piping while being stirred. As the metering device, a known metering pump, particularly a gear pump, is suitably used. 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 is possible to make the variation extremely small.

Specifically, the weight variation CV% in the thread axis direction can be made 6.0 or less, and by doing so, the heat generation performance of the product can be at the same level as products made of conventional thin metal wires. can be satisfied.

The measured synthetic resin solution is roughly transferred through the piping to the adhesion device and is adhered to the core yarn. The adhesion device is a thread guide for the core yarn that has a discharge hole, and in order to continuously deposit a constant amount onto the core yarn, the distance from the discharge hole of the synthetic resin solution until the core yarn leaves the yarn guide is set. Preferably short.

In addition, in order to prevent the thread path of the core yarn from moving within the attachment device, there is a thread guide groove of either a 7-shaped groove, a U-shaped groove, or a flat groove, and discharge holes are provided in four parts of the yarn guide groove. Particular preference is given to using a perforated thread guide as an attachment device. FIG. 1 shows an example of a top view of the thread guide. The part indicated by the broken line is the transfer path for the measured synthetic resin solution. Figure 1 is a diagram of the thread guide grooves (a> is a V-shaped groove, (b) is a U-shaped groove, and (C> is a flat groove). Preferably, a material with holes is used, as shown in FIG. 2, which allows the synthetic resin solution to adhere more completely around the core yarn.

The thread guide has a discharge hole for discharging synthetic resin.
It is preferable to install a plurality of them before the next drying step. Moreover, a method is preferably used in which the plurality of discharge holes apply the synthetic resin solution to the core yarn from different directions, particularly from opposite directions. In this case, the synthetic resin solution discharged from the first discharge hole cannot completely cover the core yarn, and it is particularly important that the synthetic resin solution does not adhere to the surface of the core yarn on the opposite side of the discharge hole. It's predictable. The core yarn is completely covered with the synthetic resin solution by the discharge holes after the second discharge hole. Although it is preferable to use a plurality of thread guides as described above, it is preferable to use two thread guides.

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 by a roller before the adhering device and after the drying step and is taken off. In order to attach the yarn with appropriate tension, it is also preferable to tension the yarn using front and rear rollers.

Drying process> The core yarn drawn out after the adhesion process is transferred to the next drying process. Drying may be carried out by ordinary ventilation drying, but in order to improve productivity, various commonly used means for accelerating drying, such as dry air or heating with an infrared lamp, may be used in combination.

Since the filamentous heating element of the present invention thus obtained has the synthetic resin solution uniformly adhered to it, the variation in the amount of resin adhered in the filament axis direction is extremely low, and since the filamentous heating element employs a dry fixation method, There are air bubbles inside the filamentous heating element, which makes it highly flexible and has excellent mechanical properties such as bending resistance and abrasion resistance.The resistance value per unit length of the heating wire is uniform, making it suitable for various heating element products. It can be advantageously used as a heat generating material.

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

The viscosity in the present invention was measured by the following method.

(Viscosity) A sample was collected in a 500m0 cylindrical container, and the temperature was 30'C±.
The viscosity is measured immediately after production using a BM type rotating viscosity meter (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.)
After uniformly dissolving methyl ethyl ketone and dimethyl formamide in a mixed solution (weight ratio 80:20) to a concentration of 16% 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. The synthetic resin solution was adjusted so that the amounts of 7% and 5% by weight, respectively, based on the carbon suspension solution. The viscosity of this solution was 25 poise and the solids content was 26% by weight. For the core yarn, polyester was spun at a spinning speed of 3,000 m/min, and then drawn and pre-twisted using a conventional method.Then, the torque was reduced using a hot plate at 190°C, and a pre-twisted yarn with a cube cross section of 150 denier 72 filament was obtained. Obtained. This thread was twisted with S twist of 200T/m, and 7 twists of egg were applied to eliminate the torque.
This was used as the core thread.

The synthetic resin solution was sealed in a sealed container, stirred, and rotated once at zero.
．． A gear pump with a capacity of 0.017 cc was used to transfer the synthetic resin solution from the closed container to the deposition apparatus. As the attachment device, two V-shaped ceramic threading guides having a discharge hole diameter of 0.5 m and an angle of 60' were used as shown in FIG. 1(a). FIG. 3 is a cross-sectional view of the adhesion device including the core thread, and the adhesion device using this will be explained. Said thread guide 3.3' is installed in a box 1 with a solvent reservoir 6 filled with a solvent 7. The first is closed except for the yarn passage 2.2' of the core yarn 4 and a front lid portion not shown in the figure, and is substantially closed when attached.
All parts except 2' are completely sealed. The passage 2.2' is connected to the core yarn 4.
It is desirable to make the slit as narrow as possible without contacting the slit, and in this example, the slit has a width of 2#Ii. In this example, the solvents were methyl ethyl ketone (boiling point 80°) and dimethylformamide (boiling point 150° C.), and methyl ethyl ketone having a low boiling point was selected for solvent solution management. The synthetic resin solution was applied to the core yarn from the discharge hole 5.5' of the yarn guide 3.3' at a discharge rate of 0.136 cc/min. The core yarn was fed to the adhesion device at a constant speed by a roller with a circumferential speed of 1 m/min.

The thread tension just before the attachment device was 80 g. After attachment device 1
The solvent was evaporated using a 1.25 m long heating cylinder located at 5cIR. At this time, inside the heating cylinder? Temperature 180℃
This speeds up the evaporation of the solvent and promotes foaming, and also speeds up the solidification of the synthetic resin solution so that air bubbles are incorporated into the heat generating layer. In this way, the synthetic resin containing conductive fine particles dispersed therein was fixed to the core thread, and the thread was taken off by a roller at a circumferential speed of 1 m/min.

After 3 hours of continuous operation, "icicles" of solids made of the solution were found in the thread guide, which has two discharge holes (upper and lower).
was not seen at all.

The obtained filament has a heating element of 40 ctn per 25 ctn in the filament axis direction.
When the weight of the book was measured continuously, the average value was 0.030g.
/25 傂, standard deviation o, oo.

68, and the CV value calculated by dividing the standard deviation by the mean value was 2°'3%. In addition, when the resistance value of the same thread was measured, the average value was 3.42 Ω/25cm, the standard deviation was 0.105, and the Cv value was 3.1% tear. Therefore, by the method of the present invention, it becomes possible to uniformly apply and fix the synthetic resin solution in the direction of the thread axis, and the variation in the resistance value of the thread-like heating element becomes extremely small.

Comparative Example 1 Continuous operation for 3 hours was carried out in the same manner as in Example 1 except that the box was not used. Immediately after the start, the "iccicle" on the downstream side of the discharge device gradually grows, and after 20 minutes it reaches a length of 10
When it reached m, it was taken away by the thread. This part became extremely thick and remained on the filamentous heating element even after it was dried and fixed and removed, resulting in a defect. Such "icicles" occurred 10 times during continuous operation.

[Effects of the Invention] The present invention enables a synthetic resin solution to be evenly applied and the resistance value per length to be made uniform, so that a thread-like heating element that does not show any temperature unevenness when it is made into a product is a source of good operability. It can be manufactured under stable operating conditions. Further, a filamentous heating element is obtained which is highly flexible, has good adhesion between the heating element layer and the core thread, has excellent durability against bending and abrasion, and can be stably used for a long period of time. This makes it possible to provide a heating element that can be knitted and woven and can be applied to various uses such as the clothing field, the embedded field, agriculture, fisheries, and civil engineering fields. hot theory,
It can be applied to all kinds of vehicles such as cars, trains, aircraft, ships, and space rockets.

[Brief explanation of the drawing]

Figures 1 and 2 are examples of thread guides with solution discharge holes used in the present invention. FIG. 3 is a sectional view for explaining the adhesion device of the present invention. : Box 2.2': Passage 3.3' : Thread guide 4: Thread 5.5' : Discharge hole 6: Solvent tank 7: Solvent patent applicant Toshi Co., Ltd. +a+
(bJ
<c) Figure 1 Figure 2 Figure 6

Claims (1)

[Claims] A synthetic resin solution in which conductive fine particles are suspended is measured by a measuring device, and the passage of the core thread is substantially sealed, and the inside is provided with a highly concentrated vapor atmosphere of at least one solvent of the synthetic resin solution. A conductive layer of a synthetic resin containing dispersed conductive fine particles is formed on the core yarn by adhering it to the core yarn through a discharge hole drilled in the yarn guide of the core yarn, and then drying and fixing it. A method for manufacturing a flexible filamentous heating element.