JP2003340984A - Conductive heat generating sheet having light weight and light transmitability - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a conductive heat generating sheet having light weight and light transmitability. <P>SOLUTION: The conductive heat generating sheet having light weight and light transmitability is provided with a conductive resin layer, which contains a metallic conductive filler having a grain diameter from 0.01 to 10 μm by 10 to 30 weight %, and is laminated on at least one surface of a base cloth. The weight per unit length of the conductive heat generating sheet is in the range from 50 to 300 g/m<SP>2</SP>, and the light transmitability is not smaller than 20%, and the electric resistance is in the range from 0.5×10<SP>3</SP>to 1×10<SP>6</SP>Ω/10 cm. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a conductive heat generating sheet having a light weight and a light transmitting property which can be used as a snow melting sheet by covering it on a tent or an air film structure.

[0002]

2. Description of the Related Art In recent years, tents and air film structures have been used so that events and work can be continued even during snowfall or rain (for example, JP 2001-30379 A).
No. 5). And in order to prevent snowfall during snowfall,
A method in which a conductive heating sheet is coated on these structures to melt snow is used.

As such a conductive heat generating sheet, one using a conventional stainless fiber (for example, Japanese Patent Laid-Open No. 2001-14
No. 0224) or a resin using carbon is proposed.

However, since the conductive heat-generating sheet using stainless fiber generally has a large basis weight, there is a problem that if such a sheet is stuck on the air film structure, the air film structure is overloaded. .

On the other hand, a conductive heat-generating sheet made of a conductive resin in which carbon is kneaded is generally excellent in lightness but poor in light transmission. Therefore, when such a sheet is stuck on the air-membrane structure, the air-membrane structure is formed. There was a problem that the inside of the body became dark and hindered events and the like. Especially in a large tent with a double film structure made of a thin film cloth having high light transmittance, the thin film cloth colored light like a stained glass to transmit the light, which was aesthetic. When covered with a low sheet, there was a problem that light was not transmitted inside the tent, which impaired aesthetics.

For the above reasons, it has been desired to propose a conductive heat generating sheet having a light weight and a light transmitting property.

[0007]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the prior art, and its problem is that it is lightweight and has a light transmitting property suitable as a snow melting sheet for an air film structure or the like. The object is to provide a conductive heat-generating sheet having properties.

[0008]

Means for Solving the Problems As a result of intensive studies to achieve the above-mentioned object, the present inventor has found that at least one of the base fabrics is
By laminating a conductive resin layer containing a predetermined amount of a metal-based conductive filler having a specific particle size on the surface, it was found that a conductive heat-generating sheet having desired lightness and light transmittance can be obtained, and further study is conducted. The present invention has been completed by stacking the layers.

Thus, according to the present invention, "a conductive heat generating sheet in which a conductive resin layer containing 10 to 30% by weight of a metallic conductive filler having a particle diameter of 0.01 to 10 μm is laminated on at least one surface of a base fabric. And the basis weight is 50 to 300
g / m ² , light transmittance of 20% or more, and conductive resistance of 0.5 × 10 ³ to 1 × 10 ⁶ Ω / 10 cm, light weight and light transmittance. A conductive heating sheet "is provided.

At this time, the specific resistance of the metal-based conductive filler is preferably 60 Ω · cm or less. As such a metal-based conductive filler, one made of tin oxide is preferably exemplified. Further, in order to protect the conductive resin layer, it is preferable that a non-conductive resin layer is laminated on the conductive resin layer.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below. First, the fibrous material forming the base fabric that constitutes the electrically conductive heat generating sheet of the present invention is not particularly limited, and polyester fibers represented by polyethylene terephthalate and polylactic acid, aramid fibers, carbon fibers, polyolefin fibers, polyacrylates. Illustrative are synthetic fibers such as fibers. Particularly, polyester fiber and aramid fiber are preferably exemplified. These fibers may be one kind or a combination of plural kinds. Depending on the type of fiber material used, it is possible to add functions such as high strength, abrasion resistance, flame retardancy, easy recyclability, and biodegradability to the conductive heat generating sheet.

These fibers are long fibers or short fibers, or
It is used as a yarn such as a processed yarn or a spun yarn of the composite fiber, and is used in the form of a fabric such as a woven or knitted fabric or a non-woven fabric which is a known fiber aggregate using these yarns. Further, two or more kinds of these cloths may be stuck together to form a multilayer cloth.
As the woven structure of the woven fabric, a plain weave, a twill weave, a satin weave, or a modified structure thereof is preferably used. In knitting,
Either a warp knit or a weft knit can be used. Further, in the case of a non-woven fabric, it may be a non-woven fabric composed of long fibers or a short fiber. These non-woven fabrics can be obtained by a card web, needle punch, spun bond, air laid, or a dry method in which these are combined, or a wet method in which fibers are dispersed in water or the like to form a slurry and paper is made. it can.

The single fineness of the fibers constituting the base cloth is not particularly limited, but 0.5-10.0 decitex (more preferably 1
Those in the range of 5 decitex) are preferable. Further, the basis weight of the base cloth is preferably in the range of 50 to 250 g / m ² in order to obtain the basis weight of the conductive heat generating sheet as described later.

In the present invention, at least one of the above-mentioned base fabrics is used.
A conductive resin layer containing a metal-based conductive filler is laminated on the surface.

Examples of the resin forming the conductive resin layer include urethane resin, acrylic resin, silicon resin, fluorine resin, vinyl chloride resin, vinyl acetate resin, polyethylene resin, polyvinylidene chloride resin, polyimide resin, polypropylene resin, and the like. A conductive resin is exemplified. Among them, urethane resin and acrylic resin are preferable because they have high transparency in order to obtain the light transmittance described later. As a method for laminating these resins on the base cloth, known techniques such as coating, laminating, impregnation and dip laminating can be used. Further, the resin layer may be a rubber film obtained by laminating a sheet-shaped unvulcanized rubber having high chemical resistance on the metal film layer and then vulcanizing it.

The thickness of the conductive resin layer is 5 to 50 μm.
It is preferably in the range of (more preferably 15 to 25 μm). If the thickness of the conductive resin layer is smaller than this range, a sufficient conductive effect may not be obtained. On the other hand, when the thickness is larger than 50 μm, the basis weight of the conductive heat generating sheet may be heavy, and film formation may be difficult.

The metal-based conductive filler contained in the conductive resin layer must have a particle size in the range of 0.01 to 10 μm (preferably 0.015 to 0.8 μm). The particle size of the metal-based conductive filler is extremely important for obtaining a predetermined light transmittance, and particularly, the light transmittance is improved by making the particle size smaller than the wavelength of visible light (0.4 to 0.8 μm). Sex is obtained. Here, the particle size is 0.01 μm
If it is smaller than this, a lattice as a conductive path is not sufficiently formed in the resin layer, which is not preferable. Conversely, if the particle size is 10
When it is larger than μm, the light transmittance is lowered, which is not preferable. The shape of the particles of the metal-based conductive filler is not particularly limited, and examples thereof include spherical and needle-shaped particles as well as scaly particles effective for conductive efficiency.

In the present invention, the particle size means the average value of the diameter of the metal-based conductive filler when it is spherical,
When the metal-based conductive filler is rod-shaped, the average value of its major axis is used, and when the metal-based conductive filler is scaly, the average value of its longest diameter is used.

As a material of such a metallic conductive filler,
In order to obtain the light transmittance described later, metal, metal oxide, resin plated with metal, and the like are preferably exemplified. Among these, tin oxide is particularly preferable in terms of obtaining excellent light transmittance because of high transparency. It is also possible to compound such a metal-based conductive filler in order to adjust the conductivity and the light transmittance. For example, by combining a highly transparent filler made of tin oxide and a white but highly conductive filler made of titanium oxide, it is possible to control the light transmittance, the electrical conductivity, and the hue of the appearance.

The metal-based conductive filler preferably has a smaller specific resistance, and the specific resistance is preferably 60 Ω · cm or less (more preferably 55 Ω · cm or less). In the present invention, the specific resistance is 490 N (50 kgf) / c.
The value measured with m ² green compact shall be used.

The metallic conductive filler is contained in the conductive resin layer in an amount of 10 to 30% by weight (preferably 15% by weight) based on the weight of the resin.
.About.25% by weight). The content is
When it is less than 10% by weight, the metal-based conductive fillers are not sufficiently contacted with each other, and sufficient conductivity of the resin layer cannot be obtained, which is not preferable. On the contrary, when the content exceeds 30% by weight,
It is not preferable because the light transmittance is impaired.

In the present invention, the conductive resin layer may be laminated on only one surface of the base cloth, or may be laminated on both surfaces of the base cloth. Further, a plurality of such conductive resin layers may be formed. Above all, in terms of lightness and cost, it is preferable to be laminated only on one surface of the base fabric.

Further, in order to protect the conductive resin layer and prevent electric leakage from the surface during energization, it is preferable that a non-conductive resin layer is laminated on the conductive resin layer.
The resin forming the non-conductive resin layer may be the same as the resin forming the conductive resin layer. The method for laminating the non-conductive resin layer on the conductive resin layer may be the same as the method for laminating the conductive resin layer on the base cloth.

The thickness of the non-conductive resin layer is 5 to
A range of 50 μm (more preferably 15 to 25 μm) is suitable. If the thickness of the non-conductive resin layer is smaller than 5 μm, a sufficient protective effect may not be obtained. On the other hand, when the thickness is larger than 50 μm, the basis weight of the conductive heat generating sheet may be heavy, and film formation may be difficult.

Next, in the conductive heating sheet of the present invention,
The basis weight is 50 to 300 g / m ² (preferably 60 to 15
It must be 0 g / m ² ). The basis weight is 300g
If it is larger than / m ² , it is not preferable in terms of lightness. On the other hand, if the basis weight is less than 50 g / m ² , the tensile strength and tear strength of the conductive heat-generating sheet may be lowered, and the handleability may be deteriorated, which is not preferable.

Further, in the conductive heat generating sheet of the present invention,
The light transmittance needs to be 20% or more (preferably 40% or more). When the light transmittance is lower than 20%, the amount of light transmitted to the inside is low when the conductive heat-generating sheet is attached to the upper part of a tent or the like for use, which is not preferable. Here, the light transmittance in the present invention means JIS L1055 6.1.
The light transmittance (%) measured by the method A and calculated by the following formula is used. Transmittance (%) = (1-i t / i 0) × 100 However, i _t is the illuminance (lx) when wearing the test piece, i ₀ is the illuminance when not wearing a test piece (lx ).

Further, in the conductive heating sheet of the present invention, the conductive resistance is 0.5 × 10 ³ to 1 × 10 ⁶ Ω / 10 cm.
(Preferably 1 × 10 ³ to 1 × 10 ⁵ Ω / 10 cm). The conductive resistance is 0.5 × 10 ³ Ω / 10c
If it is smaller than m, sufficient heat generation due to energization cannot be obtained, which is not preferable. On the contrary, the conductive resistance is 1 × 10 ⁶ Ω / 10 c
When it is larger than m, it is necessary to increase the load voltage in order to obtain a predetermined heat generation, which is not preferable for safety. Here, the conductive resistance referred to in the present invention is, as schematically shown in FIG. 1, by implanting metal eyelets at 10 cm intervals of the sample,
The value obtained by measuring the conductivity between eyelets with a conductivity measuring device shall be used. Although the non-conductive resin layer 3 is shown in FIG. 1, the conductive heat-generating sheet of the present invention is not limited to this, and a non-conductive resin layer may or may not be formed. May be.

The light-weight and light-transmitting conductive heat-generating sheet of the present invention has the above-mentioned basis weight, light-transmitting property, and conductivity. Such a conductive heat generating sheet, as described above, the particle diameter of the metal-based conductive filler, the conditions such as the mixing ratio of the metal-based conductive filler is appropriately selected within the above range, and at least one surface of the base cloth, It can be easily obtained by laminating a conductive resin layer containing a metal-based conductive filler.

[0029]

EXAMPLES Examples and comparative examples of the present invention will be described in detail below, but the present invention is not limited thereto.
Each measurement item in the examples was measured by the following method. <Light Transmittance> The light transmittance was measured according to JIS L1055 6.1A method, and the light transmittance (%) was measured by the following formula. Transmittance (%) = (1-i t / i 0) × 100 However, i _t is the illuminance (lx) when wearing the test piece, i ₀ is the illuminance when not wearing a test piece (lx ). <Conductivity> Metallic eyelets were driven into the sample at intervals of 10 cm, and the electrical conductivity between the eyelets was measured by a conductivity measuring device “Loresta” manufactured by Mitsubishi Chemical. <Surface Condition> The quality of the surface condition was visually evaluated by three testers and evaluated in three levels. “Excellent” is indicated by ◯, “Slightly uneven surface” is indicated by Δ, and “Surface is uneven and inferior” is indicated by x.

[Example 1] As a warp, the total fineness is 154d.
tex / 20fil polyethylene terephthalate fiber, weft polyethylene terephthalate fiber having a total fineness of 154dtex / 20fil is used as a weft yarn, and both are 11
Plain woven fabric with a weave density of 4 / 2.54 cm
/ M ² ) was obtained and used as a base fabric. Then, a urethane resin (Seiko Chemical Co., Ltd.) in which 20% by weight of a metal-based conductive filler (specific resistance: 50 Ω · cm manufactured by Mitsubishi Materials) whose material is tin oxide and whose average particle diameter is 0.02 μm with respect to the resin weight is mixed. ), Polyester-based polyurethane U-146
8) was coated with a coating thickness of 20 μm on one surface of the base fabric (coating amount: 15 g / m ² ) to laminate a conductive resin layer to obtain a conductive heat generating sheet. The conductive resistance of the obtained conductive heating sheet is 2.0 × 10 ⁴ Ω / 10c
m, light transmittance was 40%, and the conductive heat-generating sheet was excellent in lightness, light transmittance, and conductivity. Also,
The surface quality was good.

Example 2 In Example 1, a urethane resin (polyester polyurethane U-1468 manufactured by Seiko Kasei Co., Ltd.) was applied on the conductive resin layer to give a coating film thickness 2
A non-conductive resin layer was laminated by coating at 0 μm (coating amount: 12 g / m ² ) to obtain a conductive heat generating sheet.
The conductive resistance of the obtained conductive heating sheet is 2.0 × 10 ⁴ Ω
/ 10 cm, the light transmittance was 35%, and the conductive heat generating sheet was excellent in lightness, light transmittance and conductivity. The surface quality was good.

[Example 3] A conductive heat-generating sheet was obtained in the same manner as in Example 1 except that the coating amount of the conductive resin was changed to 25 g / m ² . The obtained conductive heat generating sheet had a conductive resistance of 1.0 × 10 ³ Ω / 10 cm and a light transmittance of 25%, and the conductive heat generating sheet was excellent in lightness, light transmittance and conductivity. . The surface quality was good.

[Comparative Example 1] In Example 1, carbon black (# 30 manufactured by Mitsubishi Chemical Co., Ltd.) was used instead of the metallic conductive filler made of tin oxide. A heat generating sheet was obtained. The conductive resistance of the obtained conductive heating sheet is 3.0 × 10 ³ Ω / 10 cm,
The light transmittance was 15%, and the conductive heat generating sheet had poor light transmittance. The quality of the surface condition was x.

[0034]

According to the present invention, there is provided a conductive heat-generating sheet excellent in lightness, light transmission and conductivity. The conductive heat generating sheet is excellent in lightness and light transmittance, and therefore, it is very suitable as a snow melting sheet used by being coated on a tent or an air film structure.

[Brief description of drawings]

FIG. 1 schematically shows a method for measuring conductivity.

[Explanation of symbols]

1 base cloth 2 Conductive resin layer 3 Non-conductive resin layer 4 Eyelet 5 Conductivity measuring device

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) H05B 3/14 H05B 3/14 B 3/20 321 3/20 321 389 389 F term (reference) 2E141 GG13 3K034 AA02 AA03 AA06 AA10 AA15 AA25 AA34 BA08 BA13 BB10 BC03 BC12 HA01 HA09 JA09 3K092 PP20 QA05 QB02 QB03 QB18 RF04 RF14 RF17 RF19 RF22 TT30 VV33 VV40 4F100 AA28B AB01B AK01B AK01C AK42 AK51 BA02 BA03 BA07 DE01B DG11A DG12 GB07 JG01B JG04B YY00B

Claims (4)

[Claims] 1. A particle size of 0.
A conductive heat-generating sheet in which a conductive resin layer containing 10 to 30% by weight of a metal-based conductive filler of 01 to 10 μm is laminated, the basis weight is 50 to 300 g / m ² , and the light transmittance is 20% or more. And the conductive resistance is 0.5 × 10 ³ to 1
A conductive heat-generating sheet having a light weight and a light-transmitting property, characterized by having a density of × 10 ⁶ Ω / 10 cm. 2. The specific resistance of the metallic conductive filler is 60 Ω.
The conductive heat-generating sheet having a lightness and a light-transmitting property according to claim 1, which has a size of not more than cm. 3. The electrically conductive heat-generating sheet having a light weight and a light transmitting property according to claim 2, wherein the metallic conductive filler is made of tin oxide. 4. The electrically conductive heat-generating sheet having light weight and light transmission according to claim 1, wherein a non-conductive resin layer is formed on the conductive resin layer.