JPS6176549A - Thermistor material - Google Patents

Abstract

PURPOSE:To provide a thermistor material having suppressed variation of the impedance characteristics between the dried state and the moistened state, increased thermistor constant at the high-temperature side, and improved sensitivity, by compounding a polyamide composition having low amide group concentration with a rhodanate. CONSTITUTION:The objective material can be produced by compounding (A) a polyamide composition having lower amide group concentration than that of polydodecanamide (nylon 12) with (B) 0.01-1.0wt% rhodanate. The rhodanate is KSCN having high thermal stability, low toxicity and good dispersibility in the polyamide resin.

Description

DETAILED DESCRIPTION OF THE INVENTION The following is an illustration, and it is obvious that changes and improvements may be made without departing from the spirit of the present invention.

(Example 1) Rodan force as an ionic additive in nylon 12 resin
J (KSCN) tO, 2 weight chips were uniformly dispersed, a 0.5 nm thick press sheet was formed, and the temperature-impedance characteristics after drying at 40°C.
All characteristic measurements were carried out after moisture absorption treatment up to saturation water absorption rate of ℃ x 90%. Furthermore, the saturated water absorption rate at that time was measured.

The thermistor characteristics were measured at 1 KHz, and changes in the thermistor characteristics were expressed by how many degrees of deviation occurred in the impedance value equivalent to 60° C. during drying.

The above results indicate that the thermistor characteristics shift due to moisture absorption △'r=iscte
g 40°C x 90% saturated water absorption rate -1,82N Chithermistor constant Inui ℃ ~ Tei ℃ B = 9000°.

(Example 2) A press sheet with a reduced thickness of 5 was formed by uniformly dispersing 0.2% by weight of Rodan Kali (KSCN) in a nylon 12 polyamide elastomer (Daicel Chemical @E40L), and the same test as above was conducted. did.

The above results indicate that the thermistor characteristics shift due to moisture absorption △T=14deg4
0℃×90℃ Saturated water absorption rate = 1.58% by weight
Thermistor constant dry 5℃~65℃ B = 5900
It is in °.

(Example 3) Polyamide resin using higher fatty acid (dibasic acid) or dimer acid as raw material (Nippon Rilsan M1446) K
After uniformly dispersing 0.2% by weight on Rodan Cali, a 0.5% thickness Gress sheet was prepared and all tests similar to those described above were carried out.

The above results indicate that the thermistor characteristics shift due to moisture absorption △T=10deg4
0°C x 90% saturated water absorption rate = 1.52% by weight Thermistor constant dry 5°C to 65°C 13 = 9600
It is in °.

Next, as comparative examples, examples containing no potassium rhodanide and KI as potassium rhodanide are shown in each example.
A test similar to the above was conducted on an example in which 1% by weight of .

If we add 'E' to the above result, we get K as shown in the following table.

Here the thermistor constant is T . It is.

Furthermore, the relationship between temperature and impedance constant (in IKkIz) is as shown in FIG.

In the figure, the broken line indicates the moisture absorption state, and the solid line indicates the dry state.

Here, the polyamide composition is limited to a polyamide composition with an amide group concentration lower than that of polydodecasoamide (nylon 12) (including all of nylon 12), and t is a polyamide composition with a water absorption rate higher than that of nylon 12. In this case, even if Rodan salts are used as the ionic additive, the impedance change due to moisture absorption will be too large to be practical, and the smaller the amide group acceptance degree, the better.

In addition, the addition of Rodan salt made the O1 imaginary amount more than 1,
This is because if it is less than this, it will be difficult to design the thermistor characteristics (the B constant will not become large). The reason why it is less than 1i weight is that an increase in water absorption rate is observed, which is thought to be due to the hydrophilic properties of Rodan salt, and the thermistor properties do not increase much even if more than that is added, making it impractical. It is for this purpose.

Rodan Potash (KSCN) was selected as the Rodan salt because of its thermal stability, low toxicity, and better dispersibility into polyamide resin than other Rodan salts.

Further, the polyamide composition may be modified by adding a plasticizer, a heat stabilizer, an antioxidant, etc. to the extent that it does not bleed, or by alloying with other polymers having low water absorption and good compatibility.

(Effects of the Invention) As described on paper, the present invention incorporates 0.01 to 1.0 parts by weight of Rodan salts into a polyamide composition having an amide group mystery level equal to or lower than the amide group concentration of polydodecasoamide (nylon 12). This has the effect of reducing the impedance fluctuation between the dry state and the moisture absorption state in the thermistor constant, and increasing the thermistor constant on the high temperature side to completely improve the thermistor sensitivity.

[Brief explanation of the drawing]

FIG. 1 shows the structure of a general heat-sensitive sheet heating element, and FIG. 2 shows the temperature-impedance characteristics of the thermistor material of the present invention.

Claims (2)

[Claims] (1) A thermistor material characterized in that 0.01 to 1.0 parts by weight of rhodan salts are blended into a polyamide composition having an amide group concentration lower than that of polydodecasoamide (nylon 12). (2) Claim 1 in which the rhodan salt is KSCN
Thermistor materials listed in section.