JPS5882501A - High molecular temperature sensitive element - 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 flexible polymer temperature-sensitive material that is made of a composition containing conductor particles and semiconductor particles in a polymer matrix and that detects changes in resistance or impedance due to temperature. be.

Today, in place of conventional temperature-sensitive materials using inorganic sintered bodies, polymeric temperature-sensitive materials using polymeric materials as a base material are being tried for applications that require excellent flexibility. A polymeric thermosensitive material has conductor particles and semiconductor particles dispersed in a polymer matrix, and these conductor particles and semiconductor particles form a series circuit in the polymer matrix.

Generally, semiconductor particles have a specific resistance several orders of magnitude higher than conductor particles, so in such a composition, conductor particles simply function as electrodes inside the material. . ,
Anti-A16. Ishi,.

The temperature characteristics of the semiconductor particles are determined only by the semiconductor particles.

However, it is necessary to blend the semiconductor particles to sufficiently bring out their properties. If the polymer matrix is a crystalline polymer material such as polypropylene or polyamide,
This combination of a large amount of conductor particles and semiconductor particles significantly impairs the flexibility of the matrix material, and the advantage of using a polymeric material as the matrix material is lost. In addition, if the polymer matrix is an amorphous polymer material such as soft polysalt vinyl or thermoflexible polyurethane, heating the polymer composition and applying a DC voltage may cause the conductor particles and semiconductor particles to be removed. As a result, the resistance and impedance of the polymer composition increase significantly over time. This is one of the major reasons why it has not been widely put into practical use.

On the other hand, as a measure to reduce the amount of conductor particles and semiconductor particles blended into the polymer matrix and to suppress the decrease in flexibility of the polymer material, two or more types of polymer substances that are incompatible with each other are used as the polymer matrix. Composite polymer compositions are being tested. In general, polymeric substances are made up of extremely long chain molecules, so it is difficult to completely mix two or more types of polymeric substances down to the molecular level simply by, for example, a cross-mixing operation. The mixing state changes depending on external conditions such as time and kneading temperature. In particular, when two or more types of polymeric substances that are incompatible with each other are kneaded, a phenomenon occurs in which the arrangement of the molecular chains of these polymeric substances is locally disturbed. Here, when the above-mentioned composite polymer matrix is mixed with conductor particles and semiconductor particles in the IJ gas and kneaded, these particles are localized in the disordered parts and form a single polymer matrix into the IJ gas. However, the composite polymer composition can form a conductive core and bring out the characteristics of the semiconductor particles with a content smaller than that of the conductor particles and semiconductor particles.
A large variation in the blending amount of polymeric substances of different kinds or a large variation in the disordered state of the structure due to the crosstalk operation results in a large variation in the properties of the polymer thermosensitive material.

The magnitude of this variation leads to poor yield as a polymer resin and difficulty in connecting it to the control circuit.
The result is not practical.

The present invention compensates for the above drawbacks and fully improves the characteristics of semiconductor particles.
The object of the present invention is to provide a polymeric temperature sensitive body that can be drawn out stably and has flexibility, which is a characteristic of polymeric materials.

In general, the conductive particles used in this type of polymeric composition are carbon black, graphite, and metal powder, and the semiconductor particles are metal acids [arsenic compounds or organic semiconductors]. , a thermoplastic elastomer (thermoplastic elastomer) is used as the polymer matrix, and the volume of 4-body particles is 6 to 26 per 100 parts of the thermoplastic elastomer.
It has been found that by blending 10 to 60 parts by volume of 10 parts and 10 parts by volume of semiconductor particles, a polymer thermosensitive material with excellent characteristics can be obtained.

Here, thermoplastic elastomer is a copolymer consisting of a hard phase and a soft phase, examples of which are listed in Table 1.

Table 1: The polymer temperature sensitive body of the present invention has good and stable electrical properties.
What is shown can be understood as follows. As is well known, thermoplastic elastomers have a hard phase 1
It is a block copolymer consisting of segments that form a soft phase 2 and segments that form a soft phase 2, and as shown in Figure 1, segments of the same type of different molecules aggregate to form a hard phase 1 and a jealous phase 2. . It can be considered that the hard phase 1 has a strong cohesive force between segments, and the conductor particles 3 and semiconductor particles 4 are dispersed between the phases of the hard phase 1 or inside the soft phase. Moreover, the formation of the hard phase 2 and the soft phase 2 is based on the inherent properties of the thermoplastic elastomer itself, such as intermolecular interactions. Or it doesn't depend on factors such as history.

Furthermore, since the hard phase 1 has the function of holding the conductor particles 3 and the semiconductor particles 4, for example, in a normal thermoplastic resin or amorphous polymer such as polyvinyl chloride or polyurethane, a conductor can be formed by the force of an electric field or the like. There is no possibility that the arrangement of the particles 3 or the semiconductor particles 4 or the state of contact between the particles will change.

In this way, by using a thermoplastic elastomer as a polymer matrix, it is possible to obtain a polymer composition with stable properties that has the heat resistance and toughness of its hard phase and the flexibility of its soft phase. . Carbon black and graphite are known to have a reinforcing effect on rubbery substances.

In the compositions of the present invention, especially when the conductor particles are carbon black or graphite, they have a reinforcing effect on the matrix material and are further advantageous in terms of flexibility. Furthermore, when the semiconductor particles are organic semiconductors,
Like the carbon black and graphite mentioned above, these have good affinity for polymeric materials, are finely dispersed in the matrix, and by closely intercalating between the conductor particles, contribute to the realization of a stable structure and are sensitive to Stabilizes the properties of warm bodies. This organic semiconductor particle uses a metal or a compound containing a nitrogen atom as an electron donor 7, 7, 8
．． 8-tetracyanoquinodimethane C (hereinafter abbreviated as TCNQ) salt shows even better results due to the excellent stability and heat resistance of the material itself. Examples of electron donors include alkali metals, alkaline earth metals, copper, zinc, and metal complex ions. Among them, when potassium or sodium is used as an electron donor, 20
Ion radical salts are so stable that they do not decompose for a long time even when heated at 8 degrees Celsius to 0 to 300 degrees Celsius, and when these salts are used, particularly excellent results are obtained. That is, carbon black or graphite is selected as the conductor particle, TCNQ salt with potassium or sodium as the electron donor is selected as the semiconductor particle, and a thermoplastic elastomer is used as the polymer matrix, and the mixture is kneaded while the melting temperature of the matrix material changes. This makes it possible to obtain a useful polymer temperature sensitive body with stable properties and flexibility.

Hereinafter, the present invention will be explained in detail with reference to Examples and Comparative Examples.

Comparative Example 1 200y of potassium TCNQ with a specific resistance of 3 x 1o6Ωcm at room temperature was applied to polypropylene rsooy.
, and graphite of O,OO3Ω・cm 1001
The resulting sample was mixed and kneaded for 20 minutes using a heated roll at 190°C.
A 100 m x 10 cm x 1 test piece was made by press molding with f, and colloidal carbon was coated on both sides in a circular shape with a diameter of 5 cm to make it a sample for electrical custom measurement.Comparative Example 2 Polyvinyl chloride 10M parts To 50000y of a polyvinyl chloride composition containing 10.30 parts by weight of a plasticizer and 6 parts by weight of a heat-resistant stabilizer, 20% of potassium TCNQ having a specific resistance of 3 x 106 Ωcm at room temperature was added.
0p, and 0.003Ω・cm graphite 10
0y was added and mixed, and the temperature was increased to 160' in the same manner as in Comparative Example 1.
A sample was prepared by kneading and press forming using C.

Comparative Example 3 250% each of polypropylene and thermoplastic polyurethane
The specific resistance at room temperature is 3×
Potassium TCNQ of 106 Ω·cm was mixed with 1501 of potassium TCNQ and 70 parts of graphite of 0.003 Ω·cm were added, and the mixture was kneaded and press-molded under the same conditions as in Comparative Example 1 to prepare a sample.

Example 1 Block copolymer of polystyrene and polybutadiene
5ooP, the specific resistance at room temperature is 3 x 106Ω11
Potassium TcNQ of cfi and graphite of O, OO3Ωmcm were added and mixed in varying amounts, and kneaded at 210'C in the same manner as in Comparative Example 1.
A sample was created by press molding.

Example 2 Block copolymer of polypropylene and EPDM rso
To oy, sodium TCNQ with a specific resistance of -7% 10" Ω cm at room temperature was added to oooy, and 126y of furnace black were added and mixed, and cross-wired and press-molded in the same manner as in Comparative Example 1 to create a sample. did.

The electrical characteristics were determined by changing the warm temperature of the sample, measuring the DC resistance at that time, calculating the volume resistivity at each warm temperature, and measuring the sample 2.
The difference (Δρ) between the maximum value and the minimum value and the average value (ρ) of m-product specific resistance in 0 sheets of 6On were determined. Further, the thermistor B constant (B, ) between 30° C. and 60° C. was determined from the value of the volume resistivity.

Furthermore, using the above sample, DCl was added in an atmosphere of 100°C.
A heat resistance test was conducted by applying a voltage of 0.00 V/cm for 200 hours, and the ratio of volume resistivity (ρt/ρ.) at 60° C. before (ρ.) and after (ρ,) the heat resistance test was determined. For mechanical properties, a tensile test was conducted according to ll5K7113, and the tensile strength (
S) and elongation (L) are measured, and the values of the polymer composition (S, ,
The ratio of LO (134/S0.L(/Lo)) was determined.

The above is shown in Table 2.

Table 2 However, each value of Example 1 in Table 2 is a representative value.

From this result, the following can be said.

(a) Electrical properties The composition of Comparative Example 2 has a volume resistivity ratio ρt/ρ before and after the heat resistance test. is very large. This is due to the movement and polarization of the conductor particles and semiconductor particles due to the use of the thermoplastic amorphous polymer material as the matrix material, as described above. In addition, the composition of Comparative Example 3 had a very large difference Δρ between the maximum and minimum volume resistivity at 60°C, and
t/p0 is also large. This is due to large variations in the disordered state of the structure due to the crosstalk operation due to the use of a composite polymer matrix as described above. As described above, in the composition of Comparative Example 2.3, these values further increase during mass production, resulting in poor yield and difficulty in coupling with a control circuit, making it difficult to put it to practical use in terms of stability and reliability. In contrast, these values for the composition i of this example are small and stable. Further, the thermistor B constant was also comparable to that of the comparative example, and the characteristics of the semiconductor particles were fully brought out and stable characteristics were exhibited.

(b) Mechanical custom-made polymer matrix) The ratio Sf/So of the tensile strength of the polymer composition to the IJ gas material is approximately the same value in both comparative examples and examples, but the composition of comparative example 10 has a polymer matrix. Since the material itself has a high tensile strength, the tensile strength of the composition is also greater and harder than other compositions. Furthermore, the elongation ratio 4L,/Lo is a very small value in Comparative Example 1.

As described above, the composition of Comparative Example 1 is hard and brittle, and significantly impairs the flexibility characteristic of polymeric materials, making it difficult to put it to practical use in applications requiring excellent flexibility. The composition of Comparative Example 3 shows properties intermediate between those of Comparative Example 1 and the compositions of Examples, but as in (a) above, the composition has a composite polymeric polymer)
Due to the harmful effects of IJ gas, these values become extremely low. On the other hand, in the case of the clasp example, the tensile strength of the composition was low and the elongation was high, indicating that the properties were stable and the composition had sufficient flexibility.

As described above, the polymer composition of the present invention has stable properties due to the good heat resistance and toughness of the hard phase in the molecules of the polymer matrix material and the excellent flexibility of the soft phase with good compatibility. Table 3 shows the respective values obtained from the impedance measured at the frequency e o Hz in the same manner as in Table 2.

1 2: Average value of volume specific impedance of 20 samples d: Difference between maximum and minimum volume specific impedance Bz: 30 Tl: Thermistor B between ' and 60°C
Constant Z, /Z0: 1001: Under atmosphere DC100
V/l: m (D voltage 7 When a heat resistance test is performed by applying voltage for 200 hours, 60 before (zo) and after (2t) the heat resistance test
Ratio of volume specific impedance at °C (Z, /Z0) In Comparative Example 2, the value of volume specific impedance is the first
This value is very different from the volume resistivity value in the table, and is larger than the others. By using a thermoplastic, non-crystalline polymer material as a matrix material, conductive particles,
This is thought to be because the matrix material easily enters between the semiconductor particles, and the conductor particles and semiconductor particles are separated in some places due to thermal expansion. If the volume specific impedance value and the volume specific resistance value are different, it is necessary to change the constants of the control circuit depending on the DC, AC, or AC half-wave driving method when coupling with the control circuit, making it inconvenient to use.

When the blending amounts of potassium TCNQ and graphite in Example 1 were varied, the volume resistivity and thermistor B constant between 30°C and 60°C for each blending amount were determined by the second
．． Shown in Figures 3 and 4.5. In addition, the amount of potassium TC
It was determined by calculation from the density values of disks made by pressure molding NQ and graphite.

Figures 2 and 3 show the values of the volume resistivity and thermistor B constant with respect to the volume of potassium TCNQ, with the amount of graphite as a volume per 100 parts of the matrix material as a parameter. represents. The amount of potassium TCNQ is 10
In a region smaller than 1.5 mm, the volume resistivity value increases rapidly, and the thermistor B constant decreases rapidly, and the respective values vary widely, making it impossible to fully bring out the characteristics of the semiconductor particles. This is because the amount of potassium TCNQ blended is small, so the conductive path with graphite is cut off by the matrix material. Further, in the range where the amount of potassium TCNQ is more than 60 parts, the hardness of the composition increases due to the large amount of addition, causing problems in flexibility.

Figures 4 and 6 show the values of the volume resistivity and thermistor B constant for the volumetric amount of graphite, using the amount of potassium TCNQ as a parameter for 100 parts of the matrix material volume. ing. In a region where the amount of graphite blended is less than 6 parts, the volume resistivity value increases rapidly due to the same reasons as above, and the thermistor B constant decreases rapidly. Unable to fully bring out its characteristics. The blending amount of graphite is 2
In a region where the amount is more than 6 parts, a conductive path made only of graphite is formed, and the volume resistivity value rapidly decreases, and the volume resistivity value is almost determined by graphite.
The value of the thermistor B constant also drops rapidly. The same applies to the volume specific impedance as shown in Tables 2 and 3.

As described above, by using a thermoplastic elastomer (thermoplastic elastomer) as a polymer matrix, and mixing and kneading 6 to 26 parts by volume of conductor particles and 10 to 60 parts by volume of semiconductor particles to 100 parts of this volume. , it is possible to fully bring out the characteristics of semiconductor particles and obtain a flexible polymer temperature sensitive body with excellent stable characteristics.

[Brief explanation of drawings]

Figure 1 is a schematic diagram of conductor particles and semiconductor particles dispersed in a thermoplastic elastomer, Figure 2 is a diagram showing the volume 19-specific resistance value versus the amount of potassium TONO added, and Figure 3 is a diagram of potassium TCNQ. A diagram showing the value of the thermistor B constant with respect to the blending amount, Figure 4 is a diagram showing the volume resistivity value with respect to the blending amount of graphite,
FIG. 6 shows the value of the thermistor B constant with respect to the blended amount of graphite. 1...Hard phase in thermoelastomer, 20.
... Soft phase in thermoelastomer, 3...
Atsugi particle, 4... Semiconductor particle. Name of agent Patent attorney Toshio Nakao and 1 other person 1 Tokou 8-82501 (6) Figure 1 6 - Figure 2 Potassium cho (:A/Q Drunkenness Quantity Quantity 5゛1 Figure 3 Kawau 4 Ding c-NQ*8 (m) No. 41 El

Claims (1)

[Scope of Claims] 0) A composition comprising conductor particles and semiconductor particles dispersed in a polymer matrix, wherein the polymer matrix is a thermoplastic elastomer, and the conductor particles are contained per 100 parts by volume of the thermoplastic elastomer. and semiconductor particles by volume of 6 to 25 parts and 10 parts, respectively.
A polymer thermosensitive body characterized by ~60 parts of Kokichi. (2) The polymer temperature sensitive body according to claim 1, wherein the conductor is carbon black or graphite. (3) Polymer thermosensitivity according to claim 1, wherein the semiconductor is a metal acid arsenide or an organic semiconductor. (4) The organic semiconductor uses a metal or a compound containing a nitrogen atom as an electron donor. The polymer thermosensitive material according to claim 3, which is a 7,7,8.8-tetracyanoquinodimethane salt. (6) The polymer thermosensitive material according to claim 4, wherein the metal atom is potassium or sodium.