JPH043085B2 - - Google Patents

Description

[Detailed description of the invention]

INDUSTRIAL APPLICATION FIELD The present invention relates to a polymer thermosensitive body used in temperature sensors such as electric heating devices, flexible thermosensitive heater wires, and the like. BACKGROUND ART Conventionally, a polymer temperature sensing body is generally disposed between a pair of wire-wound electrodes and used as a flexible temperature sensing wire or a thermal heater wire. A specific polyamide composition is used as the material for this polymer thermosensitive body, and changes in its capacitance, resistance, impedance, etc. due to temperature are utilized to perform the function of a temperature sensor. The performance required for this polymer thermosensitive material is as follows:
(1) Good temperature detection sensitivity, (2) Sharp melting point,
(3) Impedance due to ion polarization effect does not change over time in response to a DC component electric field; (4) It is not easily affected by humidity. Polymer temperature sensitive bodies containing polyamide as a main component can easily provide the above-mentioned performances (1) and (2), and there are many known examples. Regarding item (3), in addition to the performance of the polymer thermosensitive material itself, such as the stabilizer composition of the polyamide composition, the type and molecular weight of additives, and other conditions other than the material, such as the configuration of the thermal heater wire and the applied electric field conditions, It is also greatly influenced by The influence of humidity in item (4) depends on the characteristics of the polymer thermosensitive material itself. Even nylon 11 and nylon 12, which have low hygroscopicity among polyamide resins, are significantly affected by humidity, and many patents have been disclosed to improve this. For example, Tokukai Akira
No. 56-100881 discloses a temperature sensitive body made of a blended resin composition of polyamide and dimer acid-containing polyamide. Problems to be Solved by the Invention However, in the blended resin composition of the polyamide and dimer acid-containing polyamide described above, as the dimer acid content increases, the effect of reducing the influence of humidity on the temperature-sensitive characteristics is excellent; There was a problem in that the mechanical properties of the product, especially the tear strength, were significantly reduced, making it difficult to put it into practical use. SUMMARY OF THE INVENTION An object of the present invention is to provide a polymeric thermosensitive material that exhibits extremely small fluctuations in temperature-sensitive characteristics due to humidity and has excellent mechanical properties. Means for solving the problem Dimer acid-containing polyamide (A) and carboxyl group-containing polyolefin (B) are mixed in a ratio of the former to the latter (A/
By combining in the range of B) = 0.2 to 5 and containing 10 to 60% by weight in the polyamide, a polymer temperature sensitive material with extremely small fluctuations in temperature sensitive characteristics due to humidity and excellent mechanical properties can be obtained. be able to. Moreover, this polyamide composition can further reduce property fluctuations due to humidity by combining it with a phenolic compound. Function Carboxyl group-containing polyolefins have low hygroscopicity, generally have weaker intermolecular forces than polyamides, and have a higher degree of polymerization. Therefore, it has excellent mechanical properties. On the other hand, dimer acid-containing polyamide is a polyamide with low hygroscopicity, but since the structure of the monomer molecules is complex, irregular, and has a large molecular weight, it generally has a low degree of polymerization and poor mechanical properties. Both of these exhibit compatibility with polyamide, and exhibit their respective characteristics in polyamide. The dimer acid-containing polyamide is effective in reducing fluctuations in the temperature-sensitive properties of a polymer thermosensitive body due to humidity, and the carboxyl group-containing polyolefin is effective in suppressing deterioration in mechanical properties. Here, the low hygroscopicity of the carboxyl group-containing polyolefin is its own characteristic, and although it has almost no moisture-proofing effect on the temperature-sensitive properties of the polymer thermosensitive material, it has a large reinforcing effect on the mechanical properties. As described above, by blending both the dimer acid-containing polyamide and the carboxyl group-containing polyolefin with the polyamide, an excellent polymer temperature sensitive body can be obtained. Furthermore, phenolic compounds have excellent compatibility with polyamide and have a great moisture-proofing effect. This is because dimer acid-containing polyamide has a complex and amorphous molecular structure, which makes it easy to coordinate the phenolic compound to the amide group in the polyamide composition, resulting in a great moisture-proofing effect. It will be done. Examples The dimer acid-containing polyamide used in the present invention is a polyamide containing a dimer acid having 36 carbon atoms, which is generally obtained by a Diels-Alder reaction between linoleic acid and a conjugated isomer of linoleic acid. Usually, a product commercially available from Henkel Hakusui Co., Ltd. under the trade name "Macromelt" can be used. In addition, carboxyl group-containing polyolefins are
It is commercially available from Mitsui Polychemical Co., Ltd. under the trade name "Himilan" and from Mitsui Petrochemical Industries Co., Ltd. under the trade name "Admer." These were blended with polyamide, kneaded into pellets using an extruder, and then formed into a sheet using a hot press to prepare a sample. The influence of humidity on temperature-sensitive characteristics was measured using a sample prepared above with silver paint electrodes on both sides of a sheet approximately 10 x 10 cm in size and 0.1 cm thick. It is expressed as the temperature difference (ΔT _W ) of the thermistor characteristics when saturated moisture is absorbed.
In addition, the tear strength was determined by the size of approximately 6 x 10 cm and thickness of 0.04 cm produced as described above, and approximately 3 cm in the center of the 6 cm width.
Using a sheet sample with a notch in it, fix one side of the notch and pull the other side, calculate the load when tearing from the notch part, and express it as the value (G) when converted to 1 mm thickness. Ta. Examples of the present invention are shown in the table along with comparative examples.

[Table] The dimer acid-containing polyamide (A) and carboxyl group-containing polyolefin (B) used in the present invention are blended in a polyamide composition at a ratio (A/B) of 10 to 60% by weight in the range of 0.2 to 5. It has good properties as a polymer thermosensitive material. In addition, phenolic compounds include oxybenzoic acid alkyl esters, dioxybenzoic acid alkyl esters, gallic acid alkyl esters, alkylphenols, halogenated phenols, etc., or condensation polymers of oxybenzoic acid alkyl esters, alkylphenols, halogenated phenols, etc. is used, and is added in an amount of 5 to 30 parts by weight per 100 parts by weight of the polymer containing the polyamide component to further reduce fluctuations in temperature-sensitive characteristics due to humidity. Effects of the Invention The present invention provides a polymeric thermosensitive material that exhibits extremely small fluctuations in temperature-sensitive characteristics due to humidity and has excellent mechanical properties.

Claims (1)

[Scope of Claims] 1. A polyamide composition containing 10 to 60% by weight of dimer acid-containing polyamide (A) and carboxyl group-containing polyolefin (B) at a ratio (A/B) of the former to the latter in the range of 0.2 to 5. Polymer thermosensitive body made of material. 2. The polymer thermosensitive material according to claim 1, wherein the dimer acid-containing polyamide contains a saturated carboxylic acid obtained by hydrogenating dimer acid as a monomer. 3. The polymer temperature sensitive body according to claim 1, wherein the carboxyl group-containing polyolefin is polyethylene or polypropylene copolymerized with an acrylic acid monomer component or a maleic acid monomer component at the terminal. 4. The polymer thermosensitive material according to claim 1, wherein the polyamide composition contains 5 to 30 parts by weight of a phenolic compound based on 100 parts by weight of the polymer containing the polyamide component.