JPS58223209A - Conductive resin composition for panel heater - 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 conductive resin composition for a planar heating element.

In recent years, so-called sheet heating elements, which generate heat by conducting electricity through a conductive material in which conductive carbon black is blended with a polymer material, have become popular as heating appliances.

Such a planar heating element has the advantage that it does not suffer from problems such as wire breakage due to bending, unlike heating elements using nichrome wire, is bendable, is safe, and has low maintenance costs.

However, when trying to reduce the overall thickness of conductive materials for planar heating elements on the market to produce a heat-generating effect, it has become difficult to use conductive materials, especially those made by kneading conductive filler into synthetic resin. If you try to create a heat generating effect with a film with a thickness of 100-200 microns, it is not only difficult to process the film, but also due to the thinning of the film.
It is not possible to obtain a low resistance value that is sufficient to generate sufficient heat.

For this reason, when producing a thin planar heating element, a method is currently used in which a conductive paint is applied to a polyester or nylon fabric.

According to the method of applying conductive paint to the woven fabric, 4-
Coating and drying had to be repeated five times, which was undesirable because it took a long time and the manufacturing cost was high.

In view of the above, the present inventors have carried out various studies and have found that linear low density polyethylene (hereinafter referred to as L-LDPE) is used as a carrier resin.
Even if the conductive IJt fJ or □' resin composition is made of polypropylene or high-density polyethylene, and conductive carbon black and graphite are blended into a thin film of 100 to 150 microns, the surface resistance is high. It was discovered that the value was extremely low at 80 to 120Ω, and the present invention was developed based on this finding.

That is, the present invention is a conductive resin composition for a planar heating element, characterized in that it is made by blending a conductive carbon blank and graphite with a carrier resin made of linear low-density polyethylene and polypropylene or high-density polyethylene. .

The L-LDPE used in the present invention is, for example,
2 to 0.935 (f/, -d) and a melt index of 1.0 to .zo (r/lo min) is used, preferably 10 to 2. s (r/lO min) is preferable.

The amount of L-LDPE used in the composition can range from 5 to 50% by weight, preferably from 5 to 30% by weight.

Further, the polypropylene and high-density polyethylene used in the present invention may be any of those normally used for films and monofilaments, and have a suitable melt index of 06 to 1o (y/10 minutes).

The conductive carbon black used in the present invention is a furnace type carbon black, and among them, the rate of change in resistance during processing is small. (Surface species are 200~xoooy/ri)
Things are preferable.

The content of the conductive carbon black is 10 to 40% by weight, preferably 10 to 35% by weight, based on the '41 resin.

Further, the graphite used in combination with the conductive carbon black is for further lowering the resistance value, and may be either a natural product or an artificially manufactured product, and its blending amount is 5 to 15% by weight based on the carrier resin. Preferably it is 5 to 10% by weight.

The composition of the present invention may contain an antioxidant, a lubricant, etc. in addition to the above-mentioned components.

When a blown film was formed using the conductive resin composition having the above-mentioned composition, bubble stability under processing conditions was good, and a film with a uniform thickness was obtained.

When we measured the physical properties of the film thus obtained, we found that the thickness of the film was 100 to 150 microns, and the surface resistance value was within the range of 90 to 120 ohm. A conductive film having a very low resistance value was obtained.

Then, using the conductive film described above, the distance between the electrodes is 15
When a planar heating element with a temperature of 0 to 0 was prepared and its heat generating property was examined, the surface humidity reached 60°C and a stable heat generation state was exhibited.

In contrast to the conductive resin composition of the present invention, conventional conductive resin compositions have poor elongation during melt molding, making it impossible to mold them into a blown film. In other cases, blown film processing is good, but the selection of resin and carbon black is insufficient, and graphite is not blended, so when the film is formed to a thickness of 150 microns, The resistance value was high and it did not generate enough heat.

The present invention will be specifically explained below using Examples.

Note that parts in Examples and Comparative Examples are parts by weight.

Example 1゜L-LDPK (flexibility 0.92, MI==2.0 Trade name: Urtozex 150 parts 2020L Mitsui Petrochemicals product) High-density polyethylene (density 0.95,
MI=0.9 Product name: Haise 48.0 parts Tsukusu 500
0 S Mitsui Petrochemical Co., Ltd. product) Conductive carbon black (Product name: Condaku Tensions 9'15 30.0 parts Co.) Natural graphite (Product name: csp Nippon Graphite Co., Ltd. product) 7, 0 parts Example 2゜L-LDPE (density 0.93, MI = 1.3 Trade name: Urtsek 215.0 parts 3010F Mitsui Petrochemicals product) Polypropylene (density 0.93, MI = 1.2 Trade name: Idemitsu Polyglo 48.0 parts E250G Idemitsu Petrochemical Co., Ltd. product) Conductive carbon black (Product name: Palcan XC-7230, 0 parts Cabot Co. product) Natural graphite (Product name: csp Nippon Graphite Co. product) 7.0 parts Examples 3 L-LDPE (density 0.935.MI=2.1 Product name:
Urtose 15.0 parts x352QL Mitsui Petrochemicals product) High density polyethylene (density 0.95,
MI=0.9 Product name: High 60.0 part Z3
300F Mitsui Petrochemical Co., Ltd. product) Conductive carbon black (Product name: Ketchen EC18, 0 parts Lion Co. product) Natural graphite (Product name: csp Nippon Graphite Co. product) 7.0 parts Comparative example I IJ-r=npz (Execution) Same product as Example 1)
630 parts conductive carbon black (same product as Example 1) 300 parts natural graphite (same product as Example 2) 70 parts Comparative Example 2゜L-LDPE (actual M+J Same product as Example 1)
150 parts low density polyethylene (density 0.92,
M r=7.0 Product name Nijiyo 480 copies Rex F
171 Showa Denko product) Conductive carbon black (same product as Example 2)
30.0 parts natural graphite (same product as Example 1) 70 parts Comparative Example 3 L-LDPE (same product as Example 1)
15.0 parts High-density polyethylene (same product as Example 1) 480 parts Conductive carbon black (
Acetylene black 30.0 parts Surface area 100 m/f military, manufactured by Kiikagaku Kogyo Co., Ltd.) Natural graphite (same product as Example 1) 7.0 parts Comparative Example 4 L-LDPE (same product as Example 1)
150 parts low density polyethylene (same product as Comparative Example 2)
480 parts conductivity, sexual power - Bon Black (
Example 3. aO, O part natural graphite (same product as implementation f!12)
7゜0 parts Comparative Example 5゜L-LDPE (same product as Example 1)
150 parts high-density polyethylene (same product as Example 1)
55.0 parts conductive carbon black (
Same product as Example 1) 3 O, O parts 70 each of the formulations of the above Example and Comparative Example! Bamba IJ
The mixture was placed in an S mixer and kneaded for 5 minutes at 180-200°C.

Next, this kneaded material was subjected to a mixing roll at a temperature of 130 to 150°C and kneaded for 5 minutes to form a mixture with a thickness of about 2 and a width of about 300.
1 into a plate shape, and make it into a square pellet using a square pelletizer.

The square pellets are extruded using a vented extruder with a diameter of 90% and a humidity of 180 to 200°C to obtain 2.5 to 3.0% cylindrical pellets.

This cylindrical pellet was subjected to an inflation extrusion molding machine with L/D = 20 at a temperature of 210 to 250°C.
to create a film with a thickness of 150 microns.

This film was used as a measurement piece for surface resistance, and the surface resistance was measured using a digital multimeter and a tester. The results are shown in Table 1. Furthermore, a planar heating element having a distance between electrodes of 150 mm was prepared using this film, and the temperature was measured using a surface thermometer when an AC power supply of 100 V was applied. The results are shown in Table 1.0 Table 1 (Note) The exothermic temperature is the value measured 2 hours after the AC 100V was turned on when the temperature was 15°C.

Claims (1)

[Claims] 1. A conductive resin composition for a planar heating element, comprising a phase resin comprising linear low-density polyethylene and high-density polyethylene bathed in polypropylene, and conductive carbon black and graphite mixed therein.