JPH06290860A - Sheet form heat emitting body and base cloth for it - Google Patents

Abstract

PURPOSE:To provide a quilt, etc., having excellent performance by forming a sheet form heat emitting body using a base cloth made from cotton cloth which has a specific thread gauge, a specific per-inch density of warp and weft, and a specific number of structural points per square inch. CONSTITUTION:A base cloth for a sheet form heat emitting body is made from a cotton cloth having a thread gage of 10-50#, a warp density per inch of 30-200 pieces, a weft density per inch of 50-200 pieces, and a number of structural points per square inch of 50-500. A pair of current feeding electrodes are woven in this base cloth, and thereto an electroconductive substance is attached as a binder, and its inner surface is covered with an insulative substance so that a flexible sheet form heat emitting body is accomplished. Because the base cloth is excellent in flexibility inherent in cotton cloth, the quantity of plasticizer in a soft vinyl chloride film as the insulative layer of the heat emitting body using it can be reduced greatly from the conventional standard to give an excellent flexibility so that it is favorably used to a quilt etc.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flexible sheet heating element.

[0002]

2. Description of the Related Art A conductive composition in which a conductive material such as conductive carbon is mixed with a binder such as a plastic is applied on both sides of a base cloth in which a pair of current-carrying electrode wires are woven beforehand by a roll coating method or a dipping method. There is known a flexible sheet heating element obtained by insulatingly coating both surfaces of the conductive sheet obtained as described above. A polyester film or a polyvinyl chloride film is generally used as the insulating coating material. When a soft polyvinyl chloride film is used, it is possible to obtain a more flexible sheet heating element, and not only the flat surface but also the heat insulation of the surface part such as a tank and the flexibility like a futon. Besides, it can also be used for the inevitable use of folding.

However, in order to use it for bending, generally, a polyvinyl chloride film is used in a soft polyvinyl chloride film.
A large amount of plasticizer such as 80 parts per 100 parts by weight is contained. In this case, when the heating element is used at high temperature for a long time, the plasticizer in vinyl chloride is transferred to the plastic in the conductive composition. As a result, the plastic swells, which may lower the conductivity or the adhesive strength with the base cloth.
There was a problem in maintaining stable performance of the heating element. If the content of the plasticizer is lowered, the above-mentioned problems are solved, but the flexibility is lowered, and a new problem occurs that the polyvinyl chloride film is broken by repeated fatigue due to bending.

[0004]

The present invention does not have the above-mentioned problems, has sufficient flexibility, and has no change in adhesiveness even when used for a long period of time, and there is no change in resistance value. It is intended to provide a sheet heating element.

[0005]

As a result of studies, the inventors of the present invention have found that the flexibility and folding endurance of the sheet heating element as a whole are closely related not only to the vinyl chloride film but also to the flexibility of the base cloth. It was found that the flexibility as a whole can be maintained even if the plasticizer content of the PVC film is reduced by using a specific woven fabric as the base fabric, and the present invention has been accomplished.

That is, the gist of the present invention is that the thread thickness is 10
Base for a sheet heating element made of a woven fabric having a count of 50, a warp yarn density of 30 to 200 yarns per inch, a weft yarn density of 50 to 200 yarns per inch, and a weave point of 50 to 5000 points per square inch. Exists on cloth. A flexible sheet heating element is obtained by weaving a pair of current-carrying electrodes in this base cloth, adhering a conductive substance together with a binder thereto, and coating both surfaces with an insulating substance.

To explain the present invention in more detail, a cotton woven cloth, a polyester fiber woven cloth, a glass fiber woven cloth or the like can be used as the base cloth. Conductive substances include conductive carbon black, graphite, silver powder, copper powder,
Nickel powder or the like is used. As the binder, polyurethane resin, vinyl chloride-ethylene copolymer, phenol resin, acrylic resin, polyester resin, epoxy resin or the like is used. As the insulating material, a soft polyvinyl chloride film is preferable, and specifically, vinyl chloride homopolymer, vinyl chloride-vinyl acetate copolymer, vinyl chloride-ethylene copolymer, vinyl chloride-propylene copolymer, vinyl chloride. -Styrene copolymer, vinyl chloride-butadiene copolymer, vinyl chloride-isoprene copolymer, vinyl chloride-vinylidene chloride copolymer, vinyl chloride-acrylic acid ester copolymer, vinyl chloride-maleic acid ester copolymer , Vinyl chloride-methacrylic acid copolymer, vinyl chloride-acrylonitrile copolymer,
Vinyl chloride resin such as vinyl chloride-vinylidene chloride-vinyl acetate terpolymer, phthalic acid-based, adipic acid-based,
Examples thereof include those which are softened by a general plasticizer such as polyester and made into a film.

When the yarn count is less than 10 (thick yarn), the insulating coating must be made considerably thick in order to prevent the unevenness of the yarn from appearing on the surface of the sheet heating element, and it should be warm after energization. It takes a long time to become. On the other hand, if it is larger than 50 (the thread is thin), it becomes difficult to adhere the conductive substance and the binder in a sufficient amount for heat generation. The yarn density is preferably about 30 to 80 yarns per inch for both warp and weft yarns, but it depends on the thickness of the yarns used. That is, the thickness and density of the yarn may be selected so that the weight per square meter is 80 to 130 g.

Further, when compared with the same thickness and the same density, the woven cloth is richer in flexibility as the number of texture points is smaller. Therefore, the planar heating element manufactured by using the woven cloth is more flexible. become. Therefore, if classified by the Mihara design, a satin weave or a twill weave can provide a planar heating element having a higher flexibility than a plain weave. The sheet heating element is obtained by weaving a pair of current-carrying electrode wires into a base cloth, first attaching a conductive substance together with a binder on both sides thereof to form a conductive sheet, and then covering both sides of the sheet with an insulating substance. It is formed.

When a soft polyvinyl chloride film is used as the insulating material, the film and the conductive sheet are usually bonded together via an adhesive by heat lamination using a roll at a high temperature of 160 to 200 ° C. During this lamination, the electrode wires have good thermal conductivity, so that the temperature becomes higher than that of other parts of the conductive sheet, so that the film may melt and break at a part of the electrode wires.

In order to prevent this, the exposed area of the electrode wire on the surface of the base cloth is adjusted to 20% or less of the total area of the electrode wire on the surface side, and the exposure is not locally large. preferable. Specifically, the weaving method of the thread and the insertion position of the electrode wire are devised so that the surface of the electrode wire is uniformly covered with the thread. As the weaving method of the base cloth, satin weave is preferable.

[0012]

[Example] A cotton cloth made of five satin weaves having a yarn thickness of 20 and a density of 50 yarns per inch in both lengthwise and widthwise (10 points in length and width in 10 points per 1 inch) A conductive paint in which a conductive substance made of a mixture of conductive carbon black and graphite and a binder made of a polyurethane resin are dispersed in a mixed solvent of dioxane and ethyl acetate at a mixing ratio of 1: 1 by weight on a base fabric woven with After coating and drying, a conductive sheet having a thickness of 0.8 mm, to which 100 g / m ^{2 of} conductive paint was attached, was obtained. Then, using polyvinyl chloride plastisol containing isocyanate and polyester polyol on both sides of this sheet as an adhesive, with respect to 100 parts by weight of vinyl chloride resin having a degree of polymerization of 1300,
A 0.4 mm thick vinyl chloride film containing 69 parts by weight of a trimellitic acid ester plasticizer was laminated by heating lamination (roll temperature 170 ° C.) to obtain a sheet heating element.

This planar heating element was subjected to a folding fatigue test at -5 ° C. according to JIS-P8115 using an MIT folding endurance tester. As a result, it was found that it can withstand bending of 3000 times. On the other hand, when a cotton cloth made of five satin weaves having a yarn thickness of 20 and a density of 80 pieces per square inch (16 points per inch in both longitudinal and transverse directions) is 100
The vinyl chloride film was cracked at 0 times. Also,
When the dynamic viscoelasticity of these two kinds of planar heating elements was measured,
The storage elastic modulus was 8 × 10 ⁹ at −5 ° C. when a 5 piece satin weave cotton cloth having a yarn count of 20 and a density of 50 per 1 square inch was used, whereas the yarn thickness was It was found that when a 5 piece satin weave cotton cloth having 20 count and a density of 80 pieces per 1 square inch was used, it was as high as 1.5 × 10 ¹⁰ at -5 ° C.

[0014]

EFFECTS OF THE INVENTION According to the present invention, since the cotton cloth is excellent in flexibility, the amount of the plasticizer in the soft vinyl chloride film, which is the insulating layer of the planar heating element using the cotton cloth, can be significantly increased as compared with the conventional one. It can be reduced, and therefore, there is no change in resistance value due to use, and it is excellent in flexibility, so that it can be suitably used for applications such as futons.

Claims (7)

[Claims] 1. The yarn has a thickness of 10 to 50, a warp density of 30 to 200 yarns per inch, a weft yarn density of 50 to 200 yarns per inch, and a square design point. Made of woven fabric with 50 to 5000 points per inch,
Base fabric for sheet heating element. 2. The base fabric according to claim 1, wherein the woven fabric is a cotton woven fabric. 3. An electrode wire woven base cloth, wherein a pair of current-carrying electrode wires are woven into the base cloth according to claim 1. 4. The electrode wire woven base fabric according to claim 3, wherein the exposed area of the electrode wire on at least one surface is 20% or less of the total area of the electrode wire on the surface. 5. A planar heating element in which a conductive material is attached to the electrode wire woven base fabric according to claim 3 together with a binder, and then both surfaces are coated with an insulating material. 6. The sheet heating element according to claim 5, wherein the conductive material is conductive carbon black, the binder is a urethane resin, and the insulating material is a soft polyvinyl chloride film. 7. The cotton-like heating element according to claim 6, wherein the base cloth is a cotton woven cloth.