JPH0244123B2 - KOBUNSHIKANONTAI - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a heat-sensitive material made of a specific polyamide resin composition, and particularly to a heat-sensitive material that controls the resistance value and impedance of the heat-sensitive material with respect to temperature in a device that controls heat using a capacitance component as one of the control factors. It concerns materials with improved behavior.

The use of organic polymeric materials whose electrical properties change significantly with temperature, such as polyvinyl chloride and polyamide, as heat-sensitive elements has been known for some time, as seen in electric blankets, electric carpets, etc. . Control factors for the thermosensitive element include direct current volume resistivity, relative dielectric constant, and volume resistivity, and the control circuit can be operated by a combination of one or more of these. Therefore, the characteristics required of a heat-sensitive element include: large changes in electrical properties due to temperature, small changes in electrical properties due to moisture absorption, and no change in electrical properties over time due to heat cycles. Examples include being stable.

Until now, in order to meet this type of purpose, ion conductive substances such as surfactants have been added to the above organic polymer materials as additives (Japanese Patent Application Laid-Open No. 14179-1979), and ion-conductive substances that are easy to dissociate have been added to the organic polymer materials. Copper halides and other substances were added (Japanese Patent Application Laid-open No. 56-3904). However, since the conductive carrier of these compositions is naturally an ionic substance, it will polarize when a DC electric field is applied, causing a large change in impedance over time, and the former is particularly poor in heat resistance, so as described below, It could not be used as a temperature sensor in a thermal heater.

Therefore, as a result of intensive studies to solve some of the above-mentioned practical problems, the present invention has revealed that it is possible to create a heat-sensitive material that satisfies the above-mentioned performance requirements by combining a specific polyamide resin and a specific additive. They discovered this and arrived at the present invention.

That is, the present invention provides a heat-sensitive material comprising a polyamide composition containing 0.1 to 10.0 parts by weight of ferric chloride to a polyamide resin having 14 or less amide groups per 100 carbon atoms.

According to the heat-sensitive element made of the heat-sensitive material of the present invention, the rate of change in electrical properties with respect to temperature is extremely large, and unlike surfactants, it may bleed out or deteriorate over time. Because there is no
Furthermore, it does not corrode metal wires or metal foils such as aluminum and copper used for signal conductors.
It has advantages such as excellent heat resistance and easy kneading of the polyamide resin and ferric chloride.

The polyamide resin used in the present invention is polyaminoundecamide (nylon 11) or polyω
- A polyamide with a low concentration of amide groups represented by laurolactam (nylon 12), more specifically a homopolyamide or copolyamide having 14 or less amide groups per 100 carbon atoms.

The amount of ferric chloride, which is an additive component of the polyamide composition for heat-sensitive elements in the present invention, is as follows:
0.1 to 10.0 parts by weight, preferably 0.5 to 5.0 parts by weight is appropriate; if it is less than 0.1 parts by weight, the electrical properties will not change sufficiently with respect to temperature, and if it is more than 10.0 parts by weight, the mechanical properties of the polyamide resin will deteriorate. It is not desirable because it is stored away.

The method of adding ferric chloride to the polyamide resin is not particularly limited, and may be a method of adding it during the polyamide polymerization step, a method of mechanically mixing polyamide powder and ferric chloride, or a method of adding ferric chloride to polyamide pellets and ferric chloride. Any method can be used, such as a method of mixing diiron and then melting and kneading it in an extruder.

The polyamide composition containing ferric chloride is usually further formed into a wire or sheet shape using an extruder or the like to form a heat-sensitive element.

The effects of the present invention will be explained below using examples.

Example 1 After dry blending 1 part by weight of ferric chloride with 100 parts by weight of nylon 12 pellets (“Diamid L1901” manufactured by Daicel Hulls), they were melt-kneaded using an extruder and pelletized using a pelletizer. did. This pellet was compression molded at 220° to form a sheet approximately 0.5 mm thick. The temperature dependence of the specific volume impedance of this sheet at 1000Hz was measured. As a result, a very large slope was obtained as shown by curve A in FIG.

Example 2 After completely dissolving ferric chloride in water, nylon 6.12 powder (“Diamid
After mixing 100 parts by weight of ferric chloride with 5 parts by weight of ferric chloride using a Henschel mixer, water was completely evaporated. A sheet with a thickness of about 0.5 mm was created by compression molding this powder at 220°, and Example 1
The volume specific impedance was measured in the same manner. As shown by curve B in FIG. 1, the results showed a good temperature gradient similar to Example 1.

Comparative Example 1 A sheet with a thickness of approximately 0.5 mm was made in the same manner as in Example 1 except that ferric chloride was not mixed into the nylon 12 pellets, and the temperature and impedance characteristics were examined. Curve C in the diagram
As shown in , it can be seen that the slope is gentler than that of the present invention.

Comparative Example 2 A sheet with a thickness of about 0.5 mm was made in the same manner as in Example 1 except that nylon 6.12 pellets were used and ferric chloride was not mixed, and the temperature and impedance characteristics were determined. Upon investigation, it was found that the curve D resembles that of FIG. 1, and the slope is gentler than that of the present invention.

As can be seen from these results, the temperature sensing element of the present invention has a significantly improved temperature detection function, that is, the rate of change in impedance with respect to temperature, compared to nylon 12 or nylon 6/12 alone. It has electrical properties.

[Brief explanation of the drawing]

FIG. 1 is a graph showing the relationship between volume specific impedance and temperature of polymer thermosensitive bodies obtained in Examples and Comparative Examples of the present invention.

Claims (1)

[Claims] 1 Adding 0.1 to 10.0 ferric chloride to a polyamide resin with 14 or less amide groups per 100 carbon atoms
Polymer temperature sensitive body made of a polyamide composition containing parts by weight