JPS62160681A - Carbon fiber panel heater material and manufacture of the same - 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 The present invention relates to a carbon fiber planar heating element material and a method for manufacturing the same. The present invention relates to a carbon fiber planar heating element material in which countless conductive paths are formed in a planar manner, and a method for manufacturing the same.

[Conventional technology and its problems]

Traditionally, metal conducting wires have been commonly used as current-carrying heating elements, but heating elements using metal conducting wires have a heating part that is essentially a line and not a surface, so it is difficult to achieve uniform temperature distribution within a predetermined area. It is difficult to obtain, and has the disadvantage that the temperature may be uneven, for example, there are parts that are extremely hot and parts that are not so hot. To avoid this, arranging the metal conductors in a meandering manner as densely as possible within a given area will increase the weight of the heating element, which is not desirable for use as a heating element built into electric blankets, electric lap blankets, or clothing, and will cause the metal wires to be arranged in a meandering manner as closely as possible within a given area. 9
The drawback is that they must be handled carefully as there is a risk of shorting out the insulation if bent or stepped on.

Therefore, it is virtually impossible to make a surface heating element in the essential sense using metal conductive wires.

On the other hand, carbon fibers are known not only to have excellent mechanical strength and elasticity, but also to have favorable electrical properties, such as excellent electrical conductivity. In general, carbon fiber filaments with a diameter of about 6μ to 15μ are commercially available, and since they are much thinner than ordinary metal conductors and have a lighter specific gravity than metals, these filaments can be spread out over a surface. If this were done, it would be possible to obtain an extremely thin and light heating element that could essentially be called a surface heating element. However, the fact is that an effective technology for distributing and deploying carbon fiber filaments on an industrial scale has not yet been realized.
It is only possible to arrange a tow (approximately 2 to 5 filaments thick), which is a collection of 0.0000 or more filaments, in a meandering manner similar to a metal conductor wire. Even when electricity is applied to the carbon fiber in such a tow state, the expected amount of heat is not obtained, and the carbon fiber is a failure as a current-carrying heating element.

As another attempt, it may be possible to make a surface heating element by cutting carbon fibers from about 5 m to 3/-rn, dispersing them, and spreading them out on the surface. ,
Since the dispersed and expanded carbon fibers must be identified in that state, a fixing medium must be found. One attempt was to similarly cut thermoplastic glass fibers into short pieces, mix them with carbon fibers, stretch them into a thin sheet, and use heat and pressure to partially melt the glass fibers and fix the carbon fibers. be. This was an excellent idea because Tankan synthetic fibers could also be used as a means of dispersing carbon fibers, but the reality is that mixing and dispersing carbon fibers into a plastic fiber mass is a very labor-intensive process. C,
Furthermore, during mixing and dispersion work, short carbon fibers are scattered into the air and enter human respiratory organs, eyes, mouths, etc., resulting in a deterioration of the working environment. The same applies when glass fibers are used as the medium fibers for dispersion and fixation. In any case, this method is not practical unless we wait for the appearance of a new machine specifically developed and designed for this purpose.

One remaining hope is to incorporate carbon fiber into paper. However, creating a carbon fiber surface heating element by dispersing carbon fibers using paper as a medium and setting them in that state would not be successful because the paper would burn if electricity was applied to the carbon fibers to generate heat. As a practical attempt, in addition to the difficulty of encountering great resistance from conventional technical knowledge,
A large amount of expensive carbon fiber was washed away before the paper layer was formed.
There is a major disadvantage in that the yield of carbon fibers remaining in the paper layer is extremely low, making it economically unviable. This disadvantage is a major problem that has not been solved until the present invention.

[Purpose of the invention]

Therefore, the present invention solves all the above-mentioned problems and disadvantages, and creates a thin, light, and bendable carbon fiber surface in which carbon fibers are dispersed using paper as a medium and fixed in a paper layer at a high yield. The purpose of the present invention is to provide a shaped heating element material.

Another object of the present invention is to manufacture a carbon fiber planar heating element material as described above, which does not require new expensive machinery and equipment and can almost completely prevent the loss of carbon fibers during the manufacturing process. The goal is to provide a method for

[Summary of the invention]

In order to achieve the above object, the present invention first forms a base layer, which is essentially paper, on a paper screen, and before it is completely dry (for example, when it is a wet paper layer with a water content of 70-80%).
A mixed layer consisting of a mixture of paper and carbon fiber is formed thereon. It is essentially necessary to use Japanese paper as the mixed layer paper. "Essentially Japanese paper" here means that it is mainly composed of bast fibers such as paper mulberry, Japanese mulberry, and Manila hemp, and contains 0 to 30%
% of synthetic fibers such as rayon fibers.

In addition to the well-known characteristics of strong stiffness and long fiber length, bast fibers also have feathers or needle-like protrusions on the fiber surface. For this reason, the bast fibers are well intertwined with each other, resulting in excellent formation, and their feathers or small needle-like protrusions skillfully capture the carbon fibers mixed in the bast fibers to prevent them from being washed away.

Such "essentially Japanese paper" stocks may be used not only in the mixed layer but also in the initially formed base layer, but in any case when bast fibers are used, they are usually H4biscus man (scientific name: H4biscus man)
It is preferable to use the mucilage extracted from the roots of ihot L, ). In the production of washi paper, this "Ne' J It was also found that it has an effective effect on dispersion.If such a dispersant is not used, carbon fibers tend to clump and are difficult to spread evenly over a surface.

It is also possible to use chemical dispersants equivalent to the mucilage of A. japonica (e.g. Alcox trademark); however, the mucilage of the . It was observed that some viscosity remained.

Thus, according to the present invention, due to the existence of the base layer (wet paper layer) that is formed first, the carbon fibers in the paper stock solution as a mixed layer poured onto it do not directly flow down through the paper screen, but instead flow into the base layer. It stays on top and is entangled with the bast fibers that form the mixed layer and is well retained in the mixed layer. The paper fibers of the mixed layer and the paper fibers of the substrate are intertwined with each other, making both layers a seamless integral body with virtually no boundaries.

In the present invention, the carbon fiber used in the mixed layer preferably has a high electrical conductivity, that is, a small specific electric resistance ρ, preferably in the range of 10<ρ and 30 μΩm. Although not limited to this, the company recognized as the most suitable was the British company Courtauld (Courtauld).
PAN-based carbon fiber (registered trademark: Grafi, IAS). This filament has a diameter of 6.8 μm and a specific resistance of 20 μΩm. In addition, the same Grafil system has a resistivity of 12 μΩm and approximately 27 μΩm.
There are also Ωm ones. In addition to such PAN-based carbon fibers, pitch-based and rayon-based carbon fibers with equivalent electrical properties can also be used in the present invention.

Carbon fibers are used by cutting filaments into substantially equal lengths, preferably in the range of about 1 to 50 lengths, preferably about 5 to 15 lengths. The mixing ratio in the mixed layer is in the range of about 5 to 20, preferably about 8 to 15, based on the dry weight of the paper stock (bast fiber).
Winter range.

The base layer is formed to have a thickness of about 0.1 tan or more after drying without carbon fibers mixed in, and the mixed layer containing carbon fibers above it has a thickness of about 0.05 to 0.0 tan.
It is formed to have a thickness of 3 mm, preferably 0.1 to 0.2 mm. A mixed layer thinner than 0.05 mm has a low carbon fiber content and cannot generate a sufficient amount of heat. A mixed layer thicker than No. 03 is not only uneconomical because it consumes a large amount of carbon fiber, but also generates an excessive amount of heat, which is not preferable.

In the mixed layer, the short carbon fibers are held entangled with the paper fibers as described above, and the carbon fibers are in contact with each other, so that they are virtually continuous from one end to the other in the mixed layer, and have virtually no surface area. As a result, a wide conductive path is formed. Although this is not intended to be a particular theoretical limitation, it is believed that heat is generated in such conductive paths not only within the carbon fiber itself, but also at the points of contact or connections between carbon fibers and other carbon fibers. Is recognized. Therefore, in the case of using long fibers, it is recognized that it is necessary to use carbon fibers cut into the above-mentioned length range in the above-mentioned weight ratio in order to obtain the desired heat generation.

The carbon fiber planar heating element material of the present invention, in which the paper base layer and the carbon fiber-containing mixed layer are formed virtually integrally, can be produced by a patch method or a continuous (Fourdrinier) papermaking method. Manufactured in continuous length, this material has high strength and
Even if it contains highly elastic carbon fiber, its thickness is at most 0.3 mm, and since the carbon fiber is not a lump, but is separated and dispersed into single fibers of several microns, it cannot be used with ordinary knives. It can be easily cut to a predetermined length and can be cut into desired shapes and dimensions (e.g. 8mm).
00 x 500 mm rectangle) can be made.

In the case of a heating element material cut into a rectangular shape, a pair of electrodes are attached along two opposing sides of the heating element material, and the heating element is easily turned into a planar heating element by connecting it to a power source. Electrodes can be formed by tightly crimping thin strips of copper sheet metal, aluminum foil, etc. on both ends of the surface of the mixed layer, and can still be formed by applying silver or copper plating in strips on the edges. good.

The sheet heating element thus formed poses no serious danger to the human body even if it directly touches the surface of the mixed layer when, for example, an AC voltage of 100V is applied between both electrodes, but it is used as a practical electrical product. For waterproofing/moisture proofing or from a safety standpoint, it is necessary to apply an insulating coating to the heat generating part (mixed layer) and electrodes, for example by laminating with a plastic film. In order to protect the carbon fibers and paper fibers from oxidative deterioration, it is preferable to apply the plastic laminate to cover both sides of the material so as to seal the material from the outside air. The outer periphery of such a laminate may be further covered with a protective material such as cloth, non-woven fabric, leather, plywood, ceramic plate, etc. to form a final product.

[Embodiments of the invention]

Embodiments of the present invention will be described with reference to the drawings. First, Figures 1 and 2 show an example of the carbon fiber planar heating element material of the present invention. Figure 1 is drawn exaggerated and thick to show the overall concept, and electrodes are FIG. 2 is a partially cutaway side view of the material of the present invention, which is a super-enlarged partial sectional view particularly to schematically illustrate the concept of the intertwined state of fibers in the mixed layer.

The planar heating element material of the present invention basically consists of a base layer 1 and a mixed layer 2 integrally bonded thereon. Base layer 1 is
Japanese paper consisting essentially of paper, e.g. of processed base paper grade such as wallpaper, fusuma paper, etc., of packaging paper grade such as kraft paper, etc., or of bast fibers (e.g. mulberry, manila hemp, mitsumata) The material may be selected from a wide range of materials, such as those made of high grade Japanese paper, but it is preferably made of the same Japanese paper grade as the mixed layer 2 described below.

As shown in an enlarged view in FIG. 2, the mixed layer 2, which is integrally combined with the base layer 1, consists of a paper material 3 and short carbon fibers 4 which are dispersed and held as uniformly as possible in the paper material 3. Consists of a mixture of. According to the present invention, the paper quality 3 needs to be "essentially Japanese paper" as described above. In Figure 2, the individual bast fibers are shown in white as f, and the carbon fibers 4 are shown in black, but the thickness and length of each fiber are exaggerated. , which differs from the actual ratio. The feathers or needle-like protrusions on the surface of the bast fibers are omitted. The base layer 1 does not show individual fibers, and the paper quality is indicated by notching as a whole, but it is assumed that the base layer 1 is filled with fibers similar to the white blank fibers f.

The paper fibers f in the mixed layer 2 intertwine with the paper fibers in the base layer 1, especially in the region close to the base layer 1, and also intertwine with the paper fibers f in the base layer 1.
It is also intertwined. In this way, the paper quality 3 in the mixed layer 2
(Paper fiber f) has two functions: as a medium for dispersing and holding the short carbon fibers 4, and as a bonding medium for bonding the mixed layer itself to the base layer 1.

It goes without saying that both the paper quality of the base layer 1 and the paper quality 3 of the mixed layer 2 may contain not only solp and fibers but also other additives such as dyes, pigments, and sizing agents. Still, it is preferable that the paper material of the base layer 1 and/or the paper material 3 of the mixed layer 2 be applied by spraying or impregnating a flame retardant (fire retardant), as described below.

The short carbon fibers 4 in the mixed layer 2 are carbon fiber filaments cut into uniform lengths of about 1 m to about 50 m, preferably about 5 m to 15 m. The most important property of the carbon fiber used is electrical conductivity (or specific electrical resistance). For purposes of this invention, about 10
It has been found that favorable results can be obtained using carbon fibers with a resistivity of .about.30 .mu..OMEGA.m. The most suitable carbon fiber is PAN-based carbon fiber (registered trademark: GrafilAS) manufactured by Courtaulds, UK, as described above.

As schematically shown in FIG. 2, the carbon fibers 4 in the mixed layer 2 contact or connect with each other randomly while being dispersed in the paper material 3, and eventually spread from one end of the mixed layer 2 to the other. A conductive path is formed that continues and spreads out in a planar manner from the negative side edge to the other side edge. A countless number of such conductive paths are formed over the entire surface of the mixed layer 2, and the mixed layer has a substantially thickness of about 0.05 to 0.3 m, preferably about 0.1 m to 0.3 m.
A planar conductive layer having a diameter of 0.28 mm is formed.

Therefore, for example, as shown in FIG. 1, an electrode 51 is crimped onto one end surface of the mixed layer 2, and an electrode 52 is crimped onto the other end surface,
Each conductor 6. When the carbon fibers are connected to an appropriate power source, for example, an AC power source, through the wires 62 and 62, the carbon fibers generate heat in a planar manner over the entire current-carrying layer, as will be seen from the test results described later.

In order to use the material of the present invention as a current-carrying heating element, electrodes 51 and 5
It is necessary to press and attach the □ onto the surface of the mixed layer 2. The electrode bay, 52, is a thin plate or foil of aluminum or copper, which is stretched across the surface of the mixed layer 2 from end to end, as shown later in FIG. 11, and tightly pressed against the mixed layer 2.

It is generally insufficient to simply bond the electrodes 51, 5□ to the mixed layer 2 with an adhesive or the like, and it is preferable to attach them by some mechanical means. An example thereof is shown in FIG. 3 as a partial plan view and in FIG. 4 as a partially enlarged sectional view. In FIG. 3, the electrode 5 is made of aluminum foil, which is firmly pressed onto one end of the surface of the mixed layer 2, and is minced 7 in three rows. Therefore, as shown in an enlarged view in FIG. 4, the material of the electrode 5 (aluminum foil) penetrates the mixed layer 2 and digs into the base layer 1 as a leg piece or tongue piece 8. The electrodes can thus contact not only the carbon fibers 4 on the surface of the mixed layer 2, but also the carbon fibers within the mixed layer.

The method of manufacturing the two-layer structure electric heating element material of the present invention explained above is shown in FIGS.
This will be explained with reference to FIG. 0 (second embodiment).

The first embodiment illustrates a patch method, and in FIGS. 5 and 6, a roll 10 rotating in the direction of the arrow is shown.
．． 11 is hung by a permeable belt 12, the upper run of which runs from left to right in the figure. Several formworks 13 (three formworks 13, 13□, and 133 are shown) are placed on this upper run. As can be seen from the cross-sectional view of the formwork 13 on the right in FIG. be.

Along the running path of the permeable belt 12, a base layer injection position A is provided on the inlet side, and a mixed layer injection position B is provided on the exit side. For convenience of illustration, the permeable belt 12 is drawn to be long enough to hold three formworks, but in reality, a longer belt is used, and the position where the formwork is placed on the belt 12 is set before position A. A position for draining the mixed layer injected from position B to the outlet side shall be provided.

At the injection position A, the first stock 16 for forming the base layer is poured as shown by the arrow. The pouring may be carried out parallel to the running direction of the belt 12. In FIG. 6, the first stock 16 has just been poured and the formwork 13. The paper stock 16 is of course poured onto the paper screen 14 so as to have a uniform thickness.

The first paper stock 16 is, for example, softwood group (NBKP).
, softwood pulp mixed with hardwood pulp (NLBKP)
) can be used as a 0.5 to 2 aqueous solution by adding a dye and a sizing agent to the mixture, but it is also possible to use the same Japanese paper grade as the second sample described later.

If the base layer is not Japanese paper, it will be slightly thicker (0.1 mm or more).
It is desirable to form the

Moisture in the injected solution of the first stock 16 immediately flows down through the paper screen 14 and the permeable belt 12, forming a formation. In the second mold 13□ in FIG. 6, a wet paper web layer 1', which is to become a base layer, is already formed and is ready to capture the fibers to be injected next.

On top of the wet paper web layer 1', a second paper stock 17, which is to become a mixed layer (current-carrying layer), is injected in the direction of the arrow at the next injection position B. This injection may also be performed in the running direction instead of from the side, but in order to prevent the short carbon fibers 4 mixed in the paper stock 17 from clumping in one place or being aligned only in one direction. It is necessary to aim the particles randomly in all directions so as to achieve uniform dispersion. One means for this purpose is, for example, as shown in FIG. The belt 12 is slightly tilted alternately in the transverse direction of the belt, and the belt 12 is slightly pushed up from below to give a slight vibration up and down.

The second paper stock 17 is prepared as shown in the following table (2).

Table I Composition 1 Add water to (1) + (2) to make an aqueous solution with a concentration of approximately 3%,
Add a small amount of neri (troro mallow mucus) to it.

Composition 2 (1) Bast fiber Mulberry: Rayon fiber 70:3
0 (7 Tomonaga) (2) Carbon fiber (same 1) Add water to 15 pieces (1) + (2) to make an aqueous solution with a concentration of about 1.5%, and add a small amount of Neri to it.

Composition 3 (1) Bast fiber Mulberry: Manila hemp 50:50
(2) Carbon fiber (same as 1) 8% (1) + (
Add water to 2) to make an aqueous solution of about 3 g, and add a small amount of neri to it.

Composition 4 (2) Carbon fiber (1.10+mn length) 15% (1)+
Add water to (2) to make about 2 liters of aqueous solution, and add a small amount of neri to it.

The second stock 17 poured into the form (133) is blocked by the edges of the form, so it does not flow out to the surroundings, but is dehydrated through the previously formed wet paper web base layer (1'). A mixed paper layer is formed on the wet paper layer. Carbon fiber(
4) is moderately dispersed and retained in this mixed paper layer.

When the naturally dripping water in both the mixed layer and the base layer runs out,
The drying zone C shown in FIG. 8, in which the formwork moves to the next drying zone C, may be located on the extension line of the permeable belt 12, or may be placed to the side, but the drying zone C shown in FIG. For drying, a thin iron plate 19 is placed on the heater 18, and a formwork 134 having a wet base layer and a mixed layer is placed thereon.

The material of the present invention, which has been dried to the official moisture content, is placed in the formwork 13 in FIG. As shown in (shown in a cross section for convenience), it is peeled off from the paper screen 14 and taken out. The material of the present invention is designated by the symbol 1+2 as a combination of a base layer 1 and a mixed layer.

Next, FIGS. 9 and 10 show an example of a continuous manufacturing method.

The rolls 20 and 21 rotate in the direction of the arrow, and the fourdrinier 22
is hung, and its upper run is supported by a number of support rolls or table rolls 23.

A liquid tank 24 is arranged at the upper run inlet end of the Fourdrinier 22, and is filled with a first stock solution 25. The first stock solution 25 may be a paper stock whose main material is coniferous wood or guruno, as described in the previous embodiment (Kunochi method), or Japanese paper grade paper like the second paper stock. It may be a fee. A regulating plate 26 is disposed at the outlet of the liquid tank 24 to control the liquid flow 27 of the first paper stock.
can be controlled. The liquid stream 27 moves in the direction of the arrow with the movement of the fourdrinier 22, causing most of the water to immediately fall through the fourdrinier 22, leaving the fibers on the fourdrinier 22. In time, a wet paper web base layer 28 is formed on the Fourdrinier 22 and is ready to receive a second stock.

The second stock is fed onto the Fourdrinier 22 from a gutter 29 placed at a small distance from the wet paper 28 . Preferably, the gutter 29 is installed so that it can reciprocate transversely to the Fourdrinier 22 in order to uniformly distribute the carbon fibers.

The second paper material is a mixed solution 30 prepared in the same manner as in the first embodiment, essentially for forming Japanese paper, and containing the required amount of carbon fibers. A second like this
The paper stock mixed solution 30 is supplied to the gutter 29 from an appropriate liquid tank (not shown) provided on the side of the Fourdrinier 22, and flows gently from the gutter 29 onto the wet paper 28 as a liquid stream 32. Served. In order to prevent the liquid flow 32 containing carbon fibers from flowing out from both sides of the Fourdrinier 22, a pair of restraining plates 31 are erected on the sides of the Fourdrinier 22. In the figure, only one holding plate 31 is shown. The liquid stream 32 immediately causes most of the moisture to fall through the wet paper web base layer 28, leaving carbon fibers and paper fibers on the base layer, and eventually a wet paper web mixed layer 33 is formed on the wet paper web base layer.

The conveyor belt 34 is approached from above, and the roll 2
At the point where the pressure roll 35 is in contact with the paper layer 36 on the fourdrinier 22 (the mixed layer and the base layer are combined)
is transferred to the cloth belt 34. The coefficient of friction between the cloth belt 34 and the half-dried paper layer 36 is smaller than the coefficient of friction between the paper layer 36 and the fourdrinier 22.

The fabric belt 34 carrying the semi-dry paper layer 36 approaches the drying drum 40 via a roll 38, as shown in FIG. 10 following FIG. In FIG. 10, the half-dry paper layer 36 is depicted as a single layer, as it is more integrated than in FIG.

During almost one revolution around the drying drum 40, the paper layer (containing carbon fibers) is almost completely dried, and the paper layer (containing carbon fibers) is almost completely dried, and then the paper layer (containing carbon fibers) is completely dried.
It is separated from the cloth belt 34 at the point , and the continuous web-like material 41 of the present invention moves in the direction of the arrow to the next step, for example, a cutting step. The conveying fabric belt 34 passes through several guide rolls (not shown) and returns to the guide roll 37 (FIG. 9) on the fourdrinier 22.

FIG. 11 shows several examples of sandals with energizing heating elements in which the material of the present invention manufactured as described above is cut into appropriate lengths, and a pair of electrodes are provided so that the sandals can be connected to a power source. Each sample A to F has approximately 1.2 ry on both ends of the surface of the mixed layer 2.
A piece of aluminum foil with a width of r is crimped and sewn with a sewing machine at an angle of [5,5°] as shown in Figure 3 above. The composition of each sample is shown in the following table (■).

Table ■ (Resample number Dimensions -) Base layer Mixed layer Resistance true)
A 800X570 Composition 1' Composition 1 39
B 800x570 Composition 1' Composition 1 44
C900X300 Composition 2' Composition 2 20D
800X300 Composition 3' Composition 375E 6
00X450 KP Composition 4 57F
600X450 KP Composition 4 33 (note)
The base layer compositions 1', 2/, and 3/ are the compositions 1 and 2.3 in Table ■ above, respectively, with carbon fiber removed (
Japanese paper).

The base layer KP is mainly made of coniferous trees (NBK
P and NLRKP), including dyes and neutral sizing agents,
It does not contain any moss.

Next, samples A to F were subjected to a current test and the results are shown in the graph of FIG. Graph A, B, C, D, E
and F correspond to Sunnor A, B, C, D, g and F, respectively.

Each graph shows 100V between electrodes 5 and -5□ of each sample.
(50V for C and F) is applied to the mixed layer 2.
The average of the temperature values measured by contacting a thermocouple with a thermocouple at five points on the surface (points indicated by circles in FIG. 11) was recorded at predetermined intervals. The measurement time is 30 minutes for the first 10 minutes.
every second, then every minute for the next five minutes, then every five minutes. The temperature is represented by a thick line connecting the black circles, and the thin line represents the variation in the current value (A) measured at the same time as the temperature. R, T in each graph.

indicates the room temperature at which each sample was tested.

Graph A shows that the rapid temperature rise of sample A stops after about 4 minutes, the current stabilizes, and after reaching a temperature of about 60°C in 10 minutes, there is no substantial fluctuation until the 20th minute. There is. This temperature and current stability was substantially maintained for a continuous 120 minutes. After 10 hours, the electricity was turned off and Sunsol A was left to cool, and the base layer and mixed layer were inspected, but no signs of deterioration were observed in either the paper quality or the carbon fiber.

Graph B shows that the sudden temperature rise stops after 3 and a half minutes, and the temperature rises to 6 in 6 and a half minutes.
This shows that after reaching 0°C, there was no substantial change. The current value remains stable after the 9th minute. Temperature and current stability was maintained after 120 minutes. Inspection after 10 hours found no deterioration.

Graph C represents the test results when 50V AC voltage was applied to Sandal C. Increased amount of carbon fiber and electrode 5. ．． Considering the small resistance between 52 and 52, the voltage was lowered. After a slow temperature rise, it reached a level of 50° C. in about 9 minutes and stabilized thereafter.

Graph D shows that the temperature rise stopped after about 3 minutes and remained stable after 4 minutes. There is also no substantial variation in the current value.

Graphs E and F both show a slow temperature increase and a relatively long duration of cleavage to stability, about 7-8 minutes.

In addition to these tests, there are also examples where similar samples were energized continuously for 20 to 30 hours and for 10 days.
None of the paper materials were burnt out due to excessive temperature rise, and it was confirmed that the stability as seen in each of the graphs above was substantially achieved. Examples of failures in exams are:
There was smoking due to overheating in that area due to poor contact of electrodes 5I- or 52 on the mixed layer surface, which occurred about 1 minute after the start of the test. This smoke is due to the paper being burnt. An electrode that reaches a stable temperature level after a few minutes is, in this sense, an electrode that maintains sufficient contact.

An example of a surface heating element product manufactured using the surface heating element material of the present invention that passed the current conduction test as described above is shown in FIGS. 13 and 14.

The product shown in the cross-sectional view in FIG. 13 has inside thereof the current-carrying heating element material 50 of the present invention in which the base layer 1 and the mixed layer 2 as described above are combined, and the surface of the mixed layer 2 is Electrodes fixed at both ends5. and 52, the entire body is laminated and sealed with plastic films 51 and 52 on the front and back sides. Lead wires 68, 6□ are pulled out from the seams of laminates 51 and 52. As the laminate film, a composite film of polyethylene and polyester is suitable, but it is not limited thereto.

The carbon fibers 4 held in the mixed layer 2 (see Fig. 2) will not fall off due to friction or contact even when exposed without being laminated, but they will not be damaged mechanically by being sealed with the laminate 51 and 52. (if available) and also against oxidative deterioration that may occur due to prolonged heating in air. Similarly, the sealing by lamination provides sufficient protection against damage and deterioration of the paper materials 1 and 3, and also provides the necessary waterproofness as an electrical product.

FIG. 14 is a partial sectional view illustrating a product in which the electric heating element product shown in FIG. 13 is further completely covered with protective coatings 61 and 62. The heating element material 50 is hermetically covered on both sides with laminate films 51 and 52, as in FIG. The covered electrode 5 is clamped by a retainer 55 having a U-shaped cross section in order to strengthen the pressure bonding or biting into the mixed layer 2, and the retainer 55 is fitted with a screw (56).
It will be stopped. The screw 56 is tightened through the mixed layer 2°, the base layer 1 and the laminate film 51,52. Even if the screw 56 penetrates the mixed layer 2, the electrical properties of the mixed layer are not impaired in any way. It is more preferable if the screw is made of an insulating material.

The conductive wires from both electrodes (only one is shown in FIG. 14) are put together to form an insulating coat 060, and are led out of the protective covering 61, 62 from an appropriate side of the heating element.

Various materials can be used as the protective coating 61,62. Heater products that come into contact with the human body, such as throw blankets, floor blankets, electric blankets, etc., include woven fabrics, gill fabrics, knitted fabrics, and car heaters. ! Clothes, leather, leather, vinyl cloth, etc. can be used for one or both of the coverings 61, 62. Furthermore, when manufacturing a wall-mounted or floor-standing P-wall heater, a plywood board, a ceramic board, a gypsum board, a hard PVC board, a thick paperboard, etc. can be used as the covering 61, 62.

Both the heating element coated with a laminate as shown in FIG. 13 and the heating element further coated with a protective coating as shown in FIG. 14 have the same basic heat generation characteristics as the heating element material shown in the graph of FIG. 12. Even in the heater shown in Fig. 14, which has a protective coating 61, 62 (for example, gypsum board) with a thickness of 5 layers on both sides, the upper limit temperature of the internal heating element material is 60 to 7
The temperature never exceeded 0°C, and the amount of heat generated and the amount of heat dissipated through the coatings 61 and 62 were well balanced, and it was observed that a stable temperature level was maintained for a long time as a whole, and of course there were no ignition accidents.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to efficiently, inexpensively, and safely produce a planar heating element material using carbon fiber, which has been considered difficult in the past.

Since the heating element material of the present invention has a two-layer structure, it is possible to substantially eliminate the loss of carbon fibers during the manufacturing process. In the present invention, since the current-carrying layer containing carbon fibers has a composition essentially of Japanese paper, during the manufacturing process, Neri (dispersant) contained in the paper stock solution disperses the carbon fibers well, and the Japanese paper fibers It holds carbon fibers well and prevents them from separating from the paper as much as possible even after production.

According to the present invention, carbon fibers are successfully dispersed in a medium using papermaking technology. The work environment can be maintained in a good manner without being scattered and causing harm to workers. In the present invention, since the carbon fibers can be thinly and sparsely spread and dispersed, the consumption amount of carbon fibers can be kept within a reasonable range, and the product price will not rise.

Since the heating element material according to the present invention is thin and light, and is easy to cut and cut, electric heating products of various shapes and sizes can be easily manufactured.

Electric heating products using the material of the present invention do not damage the structure and electrical properties of the current-carrying layer even when bent, so there are no surface drawings that require special care in handling, and they are safe even when stepped on or stepped on. Will

[Brief explanation of drawings]

Fig. 1 is an exaggeratedly enlarged side view of the carbon fiber planar heating element material of the present invention, with electrodes and conductive wires attached, and Fig. 2 is a partially cutaway side view showing the carbon fiber sheet heating element material of the present invention in a mixed layer. FIG. 3 is an enlarged partial sectional view schematically showing the entanglement of carbon fibers; FIG. 3 is a partial plan view illustrating how to attach the electrode to the material of the present invention; FIG. 4 is an enlarged partial sectional view of the electrode portion in FIG. , FIG. 5 is a side view illustrating the punch method for manufacturing the carbon fiber planar heating element material of the present invention, FIG. 6 is a plan view of FIG. 5, and FIG. 7 shows the tilting operation at the mixed layer injection position. Fig. 6 is a view from the ■-■ arrow to explain, Fig. 8 is a side view to explain the drying and removal process following the operations in Figs. 5 and 6, and Fig. 9 is a side view to explain the continuous method of the present invention. , FIG. 10 is a side view illustrating the drying process following FIG. 9, and FIG. 11 is a current-carrying heating element in which the carbon fiber planar heating element material according to the present invention is cut into various sizes and a pair of electrodes are attached. A plan view of sandals A-F, Figure 12 is sandal A in Figure 11.
Graph A-F showing the results of the energization test corresponding to -F; FIG. 13 is a sectional view showing an example of an energization heating element made using the carbon fiber planar heating element material of the present invention; FIG. 2 is a cross-sectional view showing another example of the energized heating element. [Main symbols] 1...Base layer 2...Mixed layer 3...Paper quality f...Paper fiber 4...Carbon fiber 5...Electric ff1 (st, st...pair of electrodes) 16・
...First paper stock 17...Second paper stock 25...First paper stock 30...Second paper stock patent applicant Hara Co., Ltd. 1) Industry Figure 1 Figure 5 Figure 11 Figure 13 Figure 14 Procedural Amendment, A. March 2, 1985 Director General of the Patent Office Mr. Michibu Uga 1, Indication of the Case 1985 Patent Application No. 2
98418 No. 2, Title of the invention: Carbon fiber planar heating element material and its manufacturing method 3, Relationship with the case of the person making the amendment Patent applicant name: Harada Sangyo Co., Ltd. 4, Agent address: Nishishinfy, Minato-ku, Tokyo ! 41 6 21 Daiwa Bank Toranobar Building Shikoku Law Office

Claims (1)

[Claims] 1. A base layer formed from a paper material, a paper material that is essentially Japanese paper that is integrally bonded thereto, and short carbon fibers uniformly dispersed therein. It consists of a mixed layer,
Some of the paper fibers in the mixed layer are tightly intertwined with both the paper fibers in the base layer and the carbon fibers in the mixed layer, and the carbon fibers in the mixed layer touch or connect with each other to form an edge of the mixed layer as a whole. It forms a countless number of conductive paths that are continuous from the end to the end and spread virtually in a planar shape, and by providing a pair of electrodes on the surface of the mixed layer and applying electricity, the carbon fibers in the mixed layer can generate heat. A carbon fiber sheet heating element material that is characterized by: 2. A patent claim in which the short carbon fibers are cut into substantially uniform lengths within the range of 1 to 50 mm, and are mixed at a weight ratio of 5 to 20% based on the dry weight of the paper fibers of the mixed layer. The carbon fiber planar heating element material according to item 1. 3. The short carbon fibers are cut into substantially uniform lengths within the range of 5 to 15 mm, and account for 8 to 15% of the weight of the bast fibers such as paper mulberry, Japanese mulberry, or Manila hemp forming the mixed layer. The carbon fiber planar heating element material according to claim 1, wherein the carbon fiber sheet heating element material is mixed in a weight proportion within the range of . 4. The short carbon fiber has a diameter of 6 to 8 μm and a specific electrical resistance of 10
The carbon fiber planar heating element material according to claim 1, 2 or 3, wherein the carbon fiber sheet heating element material has a resistance of 30 μΩm. 5. The short carbon fiber has a diameter of 6.8 μm and a specific electrical resistance of 20
The carbon fiber planar heating element material according to claim 4, which is a PAN-based carbon fiber with a μΩm. 6. The carbon fiber planar heating element material according to claim 1, wherein the thickness of the mixed layer is within the range of 0.05 to 0.3 mm, and the thickness of the base layer is approximately 0.1 mm or more. 7. The carbon fiber planar heating element material according to claim 1, wherein the base layer and/or the mixed layer are coated with a flame retardant. 8. (a) Inject the first paper stock solution for forming a base layer onto the paper screen and dehydrate it to form a wet paper base layer with a water content of 60 to 90%, (b) The first paper stock solution A second paper stock solution is prepared by mixing and dispersing short carbon fibers in an amount of 5 to 20% of the dry weight of a second paper stock essentially for Japanese paper of the same type or different from the paper stock of ( c) injecting said second stock solution onto said wet paper web base layer without tearing it; (d) leaving substantially all of said short carbon fibers on substantially the entire surface of said wet paper web base layer; (e) dehydrating the second paper stock solution injected through the wet paper paper base layer to form a mixed wet paper paper layer containing cut carbon fibers in a planar form on the wet paper paper base layer; The base layer and mixed wet paper layer are combined and dried,
A method for manufacturing a carbon fiber planar heating element material comprising forming a base layer that is integrated with virtually no boundaries and a carbon fiber-containing mixed layer thereon. 9. The second paper stock is mainly made of bast fibers such as paper mulberry, Japanese mulberry or Manila hemp, and contains 0 to 30% (by weight) of synthetic fibers such as viscose rayon.
0.5~
Claim 8, wherein the aqueous solution has a concentration of 2.5%, and the first stock solution is the same as the aqueous solution of the second stock, or another wood pulp aqueous solution is used. Method. 10. The method according to claim 8 or 9, wherein the first and second stock solutions are sequentially poured into a mold having a paper screen at the bottom, which is placed on a permeable belt. Method. 11. Claim 8 or 9, wherein the first and second stock solutions are continuously injected onto the continuously running paper screen at different points along the running path of the paper screen. Method described. 12. Claim 8, wherein the short carbon fibers are cut into substantially uniform lengths within the range of 1 to 50 mm.
Or the method described in Section 9. 13. The short carbon fibers are cut into approximately uniform lengths within the range of 5 to 15 mm and account for 8 to 15% of the second paper stock.
(by weight). 14. The short carbon fiber has a diameter of 6 to 8 μm and a specific electrical resistance of 1
Claims 8 and 9 using 0 to 30 μΩm
Or the method described in item 13. 15. The short carbon fiber has a diameter of 6.8 μm and a specific electrical resistance of 2
The method according to claim 8, 9 or 13, using PAN-based carbon fibers of 0 μΩm. 16. The thickness of the carbon fiber-containing mixed layer to be formed is 0.
Within the range of 0.05 to 0.3 mm, the thickness of the base layer is 0.1 m.
The method according to claim 8 or 9, wherein the number is m or more. 17. Claim 8 or 9 comprising the step of applying a flame retardant to the formed base layer and/or mixed layer
The method described in section.