JP2001214017A - Polymer temperature sensor and temperature sensing element produced by using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polymer temperature sensor for a temperature sensing element for the temperature control of an electric warmer satisfying all requirements such as electrical properties, heat-stability, temperature fuse function and moisture resistance. SOLUTION: A polyolefin composition produced by compounding a modified polyolefin with a conductivity imparting material is used as the polymer temperature sensor. The migration of the conductivity imparting agent by the flow of electric current can be prevented by the interaction of the functional group introduced to the polyolefin resin and the conductivity imparting agent to keep the electric properties over a long period. The polymer temperature sensor having the above structure satisfies the required moisture resistance, electrical properties, mechanical strength, heat-stability, temperature fuse function and moldability.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polymer temperature sensing element used for a flexible temperature sensor or a temperature sensing heater such as an electric heater, and a temperature sensing element using the same.

[0002]

2. Description of the Related Art It has been well known to control the temperature of electric heating devices such as electric blankets and electric carpets by utilizing the temperature dependence of the electrical characteristics of polymer materials. JP-A-9-45507 and JP-A-10-140004 disclose a method of using a polyvinyl chloride, polyamide, or polyamide-modified olefin resin mixture and adding a conductivity-imparting material to improve the temperature dependence of electrical characteristics.
And many other publications. Further, Japanese Patent Application Laid-Open No. 8-78137 describes a method in which an ionic conductive solid electrolyte obtained by adding lithium perchlorate to a polyolefin oxide in a polyester resin is used as a polymer material.

[0003] Polymer materials for controlling temperature include:
(1) High temperature dependence of electrical characteristics, (2) Thermal stability of electrical characteristics and mechanical strength, (3) Temperature fuse, ie, high-temperature low-viscosity melting property, (4) Low hygroscopicity or electrical property during moisture absorption It is required that the characteristics do not change.

[0004]

However, when a conventional polyamide and a polyamide mixture are used as a polymer material, the electrical properties, mechanical strength, heat stability, temperature fuse function, and moldability are other polymer materials. Polyamide is more excellent, but polyamide has high hygroscopicity, and even those having low hygroscopicity, such as nylon 11 and nylon 12, exhibit a moisture absorption rate of about 1%.
There has been a problem that it is difficult to accurately perform temperature control without being affected by the humidity of the surrounding environment.

[0005] In order to solve the problem of moisture absorption, even in a method in which the high-temperature low-viscosity meltability of the polyester resin is improved, it is difficult to perform accurate temperature control because the polyester resin exhibits a moisture absorption of about 1%. In addition, when a resin other than polyamide is used, there has been a problem that requirements such as electrical characteristics, mechanical strength, heat stability, temperature fuse function, and moldability are not satisfied.

When a polyolefin resin having a low moisture absorption is used for the temperature sensing element, the polyolefin resin does not have a polar group, so that the conductivity-imparting material does not react with the polyolefin.
There is a problem that the electrical properties cannot be maintained because the conductivity-imparting agent moves when the power is supplied.

As described above, a polymer material satisfying all the required characteristics has not been obtained, and an object of the present invention is to solve the above-mentioned problems and to provide a high-sensitivity and stable polymer polymer which is less affected by moisture absorption. An object of the present invention is to provide a heating element and a temperature sensing element using the same.

[0008]

According to the present invention, there is provided a polymer thermosensitive material comprising a modified polyolefin resin having a polyolefin resin having at least one functional group selected from an epoxy group, a carboxyl group and an acid anhydride. Using an olefin composition containing a conductivity-imparting material, the interaction between the functional group introduced into the polyolefin resin and the conductivity-imparting agent prevents migration of the conductivity-imparting agent during energization and maintains electrical characteristics for a long time. be able to.

By using an olefin composition for the polymer thermosensor, it is possible to obtain a polymer thermosensor that satisfies humidity resistance, electrical properties, mechanical strength, heat stability, temperature fuse function, and moldability. I can do it.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In order to solve the above-mentioned problems, a first aspect of the present invention will be described.
The present invention relates to an olefin composition comprising a polymer thermosensitive material, a modified polyolefin resin in which a polyolefin resin is introduced with at least one functional group of an epoxy group, a carboxyl group and an acid anhydride, and a conductivity-imparting material. Interaction between the functional group introduced into the resin and the conductivity-imparting agent prevents the migration of the conductivity-imparting agent during energization and maintains the electrical properties for a long period of time. Moisture resistance, electrical properties, and mechanical strength It is possible to obtain a polymer thermosensor that satisfies heat stability, temperature fuse function, and moldability.

[0011] The invention according to claim 2 provides an olefin composition comprising a polymer thermosensitive body and a polyolefin resin, a conductivity-imparting material, and a compatibilizer for reacting the polyolefin resin and the conductivity-imparting agent. When used, the conductivity-imparting agent and the polyolefin resin can be reacted with each other by the compatibilizing agent, whereby the migration of the conductivity-imparting agent during energization can be prevented, and the electrical characteristics can be maintained for a long time.

According to a third aspect of the present invention, the compatibilizing agent is a modified polyolefin resin or a polystyrene resin having at least one functional group such as an epoxy group, a carboxyl group and an acid anhydride. The property imparting agent and the polyolefin resin can be made to react better, and the conductivity imparting agent can be prevented from moving during energization, and the electrical properties can be maintained for a long time.

The invention of claim 4 is characterized in that at least one of polyethylene, polypropylene and ethylene-propylene copolymer is used as the polyolefin resin.
It is possible to obtain a temperature fuse function for fusing in a temperature range of 30 ° C. to 200 ° C.

[0014] The invention of claim 5 provides an alkylphenol-formaldehyde condensate polymer or oxybenzoate-formaldehyde condensate polymer or an oxybenzoate ester-formaldehyde condensate polymer as the conductivity-imparting material. The condensation polymer can coordinate to the functional group of the modified polyolefin to increase the temperature sensitivity.

According to a sixth aspect of the present invention, the use of zinc iodide and zinc oxide as the conductivity-imparting material enhances the temperature dependence of impedance due to the ion carrier properties of zinc iodide, and the functional groups of the modified polyolefin To form a zinc complex to enhance the current-carrying stability and to stabilize it thermally.
However, when used for a long time at high temperature, iodine generated by zinc iodide acts on the electrodes as iodide ions, generating metal iodide which is an electrical insulator, and it is difficult to obtain impedance stability with time between electrodes. Become. By adding zinc oxide, it is possible to prevent zinc oxide from forming a metal iodide as an acceptor of iodine ions.

In the invention of claim 7, the olefin composition contains naphthylamine or hindered phenol, and the heat resistance can be enhanced by the antioxidative properties of naphthylamine and hindered phenol.

Further, the invention of claim 8 includes a phosphite ester compound in the olefin composition, wherein the phosphite ester compound has an antioxidant property and a reducible rust-preventive action, whereby heat deterioration is suppressed and heat resistance is reduced. Stability can be improved.

According to a ninth aspect of the present invention, there are provided a pair of electrodes provided concentrically, the polymer thermosensitive body according to any one of the first to seventh aspects provided between the electrodes, and The temperature can be controlled by applying an electric current between the electrodes and measuring the impedance of the polymer thermosensitive element, and the electrode provided on the surface of the polymer thermosensitive element is energized. Thus, the function of a heater can be fulfilled, so that it is possible to provide a thermosensitive element in which the functions of heat generation, temperature detection and temperature fuse are integrated into one.

[0019]

Embodiments of the present invention will be described below.

Example 1 The polymer thermosensitive material of Example 1 was prepared by grafting a polyolefin with a maleic anhydride graft-polymerized polyolefin into which a functional group such as an acid anhydride represented by maleic anhydride or an epoxy group was introduced, or glycyl methacrylate. An olefin composition is used in which a modified polyolefin resin such as a polyolefin copolymer or glycyl methacrylate graft-polymerized polyolefin is mixed with a conductivity-imparting material.

The interaction between the functional group introduced into the polyolefin resin and the conductivity-imparting agent can prevent the conductivity-imparting agent from moving during energization and maintain the electrical characteristics for a long time. By using the polyolefin composition for the polymer thermosensor, a polymer thermosensor satisfying moisture resistance, electrical characteristics, mechanical strength, heat stability, temperature fuse function, and moldability can be obtained.

(Embodiment 2) Next, Embodiment 2 will be described. Example 2 differs from Example 1 in that a polyolefin resin and a conductivity-imparting agent are reacted using a compatibilizer.

The polymer thermosensitive body of Example 2 was prepared by using an olefin composition containing a polyolefin resin, a conductivity-imparting material, and a compatibilizer for reacting the polyolefin resin and the conductivity-imparting agent. Thus, the conductivity-imparting agent and the polyolefin resin can be caused to react with each other, so that the migration of the conductivity-imparting agent during energization can be prevented, and the electrical characteristics can be maintained for a long period of time.

Third Embodiment Next, a third embodiment will be described.

The compatibilizer is a modified polyolefin having at least one functional group such as an epoxy group, a carboxyl group and an acid anhydride, such as a glycyl methacrylate-modified polyolefin, a maleic anhydride-modified polyolefin, an oxazoline-containing polystyrene, and a carboxylic acid-containing polyolefin. Resin and polystyrene resin can be used.

The compatibilizer is a polyolefin composition 100
1 to 30 parts by weight based on parts by weight,
If the amount is less than 1 part by weight, the effect is low, and if it is more than 30 parts by weight, the moisture absorbing property of the composition is significantly impaired.

The compatibilizer can cause the conductivity-imparting agent and the polyolefin resin to react with each other, prevent the migration of the conductivity-imparting agent during energization, and maintain the electrical characteristics for a long time.

(Embodiment 4) Next, Embodiment 4 will be described. Example 4 differs from Examples 1 to 3 in that polyethylene and polypropylene were used as the polyolefin resin.

Using polyethylene, polypropylene, ethylene-propylene copolymer as the polyolefin resin,
It is possible to obtain a temperature fuse function for fusing in a temperature range of 30 ° C. to 200 ° C.

Fifth Embodiment Next, a fifth embodiment will be described. Example 5 differs from Examples 1 to 4 in that an alkylphenol-formaldehyde condensation polymer or an oxybenzoate-formaldehyde condensation polymer was used as the conductivity-imparting material.

Examples of the conductivity-imparting material include an alkylphenol-formaldehyde condensation polymer or an oxybenzoate-formaldehyde condensation polymer, and p-oxybenzoic acid octyl ester-aldehyde condensation polymer;
-Isobenzoyl oxybenzoate-formaldehyde condensation polymer, p-oxybenzoic acid alkyl ester, p-dodecylphenol-aldehyde condensation polymer, p
-Chlorophenol-aldehyde condensation polymers and formaldehyde condensation polymers of p-hydroxybenzoic acid alkyl esters can be used.

The conductive material is a polyolefin composition 10
When the amount is less than 5 parts by weight, the effect is low. When the amount is more than 30 parts by weight, the properties of the composition are significantly impaired.

The alkylphenol-formaldehyde condensate or the oxybenzoate-formaldehyde condensate can coordinate with the ether group and the carboxyl group introduced into the polyolefin to increase the temperature sensitivity.

(Embodiment 6) Next, Embodiment 6 will be described. Example 6 differs from Example 1 to Example 5 in that zinc iodide and zinc oxide were used as the conductivity-imparting material.

As a conductivity-imparting material, zinc iodide having a high thermal stability is used in an amount of 0.1 part by weight based on 100 parts by weight of the polyolefin composition.
01 to 30 parts by weight were blended. 0.01% zinc iodide
If the amount is less than the weight part, the sensitizing property and the current stabilizing effect are low,
If it exceeds 30 parts by weight, the physical properties of the composition are significantly impaired.

In addition, zinc oxide powder having a particle diameter of 0.1 to 0.5 μm as an acceptor of iodide ions generated from zinc iodide when used at a high temperature for a long time is used in an amount of 0.1 to 0.5 part by weight per 100 parts by weight of the polyolefin composition. 01 to 30 parts by weight were blended. If the amount of zinc oxide is less than 0.01 part by weight, the sensitizing property and the current-stabilizing effect are low. If the amount is more than 30 parts by weight, the physical properties of the composition are significantly impaired.

Examples of the metal deactivator as an interfacial stabilizer between the electrode and the polyolefin composition include disalicyroid hydrazine decamethylenedicarboxylate and N, N'-bis [3- (3,5-di-t- [Butyl-4-hydroxyphenyl) propionyl] hydrazine and 1,2,3 benzotriazole or 1-hydroxymethylbenzotriazole or 1,2-dicarboxyethylbenzotriazole as a derivative thereof was used.

Zinc iodide enhances the temperature dependence of impedance due to the ion carrier properties of zinc iodide, and forms a zinc complex at a carboxyl group or the like introduced into the modified polyolefin, thereby enhancing the current-carrying stability and thermally stabilizing. I do. However, when used for a long time at high temperature, iodine generated by zinc iodide acts on the electrodes as iodide ions, generating metal iodide which is an electrical insulator, and it is difficult to obtain impedance stability with time between electrodes. Become. By adding zinc oxide, it is possible to prevent zinc oxide from forming a metal iodide as an acceptor of iodide ions, and zinc oxide generates zinc iodide to improve current-carrying stability. Also,
By blending the metal deactivator, the electric resistance at the interface between the electrode and the polyolefin composition can be stabilized.

(Embodiment 7) Next, Embodiment 7 will be described. Example 7 differs from Examples 1 to 6 in that naphthylamine or hindered phenol was added to the polyolefin composition.

As the hindered phenol, triethylene glycol-bis [3- (3-t-butyl-5-methyl-4-hydroxyphenyl) propionate] or pentaerythrityl-tetrakis [3- (3,5-di-t
-Butyl-4-hydroxyphenyl) propionate]
And naphthylamine are used, and the heat stability can be enhanced by the antioxidant properties of hindered phenol and naphthylamine.

(Eighth Embodiment) Next, an eighth embodiment will be described. Example 8 differs from Examples 1 to 7 in that a phosphite compound was blended into the polyolefin composition.

Examples of the phosphite compound include tetraphenyldipropylene glycol phosphite, tetraphenyltetra (tridecyl) pentaerythritol tetraphosphite, which has a high molecular weight, excellent non-volatility, and a suitable phosphoric acid concentration, and hydrogenated bisphenol. A-pentaerythritol phosphite polymer is used. Due to the antioxidant property and the reduction rust preventive action of the phosphite compound, the thermal deterioration property is suppressed, and the heat stability can be increased.

For evaluation of the polymer thermosensitive body, a polyolefin composition having the composition shown in Table 1 was blended, kneaded by an extruder, and formed into a sheet having a size of 70 mm × 70 mm and a thickness of 0.8 mm by a hot press. Table 1 shows the results of measurement of the temperature dependence of impedance, moisture resistance, and half-wave conduction stability using a sample prepared by providing silver-coated electrodes on both surfaces.

[0044]

[Table 1]

The temperature dependence of the impedance is a thermistor B constant of 40 to 80 ° C., and the half-wave conduction stability is 100.
The temperature difference ΔTz between the initial impedance at 80 ° C. and the impedance after 50-hour half-wave conduction at 80 ° C. for 200 hours. FIG. 1 shows the evaluation of ΔTz. The half-wave energization causes deterioration of the polymer thermosensor, and changes impedance-temperature dependent characteristics. That is, this ΔT
The smaller the value of z, the higher the half-wave conduction stability. Moisture resistance is the initial impedance at 45 ° C and 4
It was represented by the temperature difference ΔTw of the impedance after standing at 5 ° C. and 95 RH% for 72 hours. The evaluation of ΔTw is shown in FIG. From FIG. 2, since the test piece is due to moisture absorption, the impedance-temperature dependent characteristics change, and a temperature difference occurs between the initial impedance value and the same impedance value after moisture absorption. This ΔTw
The smaller the value, the higher the moisture resistance performance.

(Embodiment 9) FIG. 3 is a structural view of a temperature sensing element according to Embodiment 9 of the present invention. In FIG. 3, 1 is 15
00 denier polyester core wire, 2 and 4, copper, aluminum, gold, platinum, palladium, silver, tin, solder, nickel, stainless steel, titanium, indium, etc., winding electrode wire, 3 between electrode wires 2 and 4 Polymer thermosensor,
Reference numeral 5 denotes an insulating jacket layer.

Next, the operation and operation will be described. Since the electrical properties such as capacitance, electrical resistance, and impedance of the polymer thermosensitive body 3 change depending on the temperature, electricity is supplied between the electrodes 2 and 4 to measure the electrical properties of the polymer thermosensitive body 3. Thus, the temperature can be detected, and the temperature of an electric warming device such as an electric blanket or an electric carpet can be controlled.

Further, since the electrode provided on the surface of the polymer thermosensitive element can also function as a heater when energized, a thermosensitive element which integrates the functions of heat generation, temperature detection and temperature fuse into one is provided. Can do things.

[0049]

As described above, according to the first aspect of the present invention, the interaction between the functional group introduced into the polyolefin resin and the conductivity-imparting agent prevents the migration of the conductivity-imparting agent at the time of energization, and the long term. Electrical characteristics can be maintained,
A polymer thermosensor that satisfies moisture resistance, electrical properties, mechanical strength, heat stability, temperature fuse function, and moldability can be obtained.

According to the second aspect of the present invention, the conductivity-imparting agent and the polyolefin resin can be reacted with each other by the compatibilizing agent. can do. Further, the moisture resistance can be further increased by reducing the moisture absorption rate of the polymer thermosensor itself.

According to the ninth aspect of the present invention, the electric current is applied between the electrodes to measure the impedance of the polymer thermosensitive material,
A temperature-sensitive element for controlling the temperature of an electric warmer such as an electric blanket or an electric carpet can be provided. In addition, since the electrodes provided on the surface of the polymer thermosensitive element can also function as a heater when energized, it is possible to provide a thermosensitive element that integrates the functions of heat generation, temperature detection, and temperature fuse into one.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram for evaluating half-wave conduction stability of a polymer thermosensor in Example 8 of the present invention.

FIG. 2 is a diagram showing a stable evaluation of moisture resistance performance of the polymer thermosensor.

FIG. 3 is a configuration diagram of a temperature-sensitive element according to a ninth embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Polyester core wire 2, 4 Electrode wire 3 Polymer thermosensitive element 5 Insulation jacket layer

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat ゛ (Reference) C08K 5/524 C08K 5/524 C08L 23/00 C08L 23/00 23/06 23/06 23/12 23 / 12 23/16 23/16 25/06 25/06 61/06 61/06 H01L 35/00 H01L 35/00 S // H05B 3/00 310 H05B 3/00 310E F term (reference) 3K058 AA55 AA92 BA02 BA03 CA12 CA24 CA46 CA56 CA65 CE02 CE12 CE16 4J002 BB031 BB092 BB121 BB151 BB212 BC032 BC122 CC043 CC053 CD192 DD086 DE106 EJ067 EN067 FD077 FD113 FD116 GQ00

Claims (9)

[Claims] 1. A polymer thermosensor having an olefin composition comprising a modified polyolefin resin obtained by introducing at least one functional group of an epoxy group, a carboxyl group and an acid anhydride into a polyolefin resin and a conductivity-imparting material. 2. A polyolefin resin, a conductivity-imparting material,
A polymer thermosensor having an olefin composition containing the polyolefin resin and a compatibilizer that reacts the conductivity-imparting agent. 3. The compatibilizer is a modified polyolefin resin or a polystyrene resin into which at least one functional group of an epoxy group, a carboxyl group and an acid anhydride has been introduced.
The polymer thermosensitive body according to the above. 4. The polymer thermosensor according to claim 1, wherein the polyolefin resin is at least one of polyethylene, polypropylene, and ethylene-propylene copolymer. 5. The polymer thermosensor according to claim 1, wherein the conductivity-imparting material is an alkylphenol-formaldehyde condensation polymer or an oxybenzoate-formaldehyde condensation polymer. 6. The polymer thermosensitive body according to claim 1, wherein the conductivity-imparting material is zinc iodide or zinc oxide. 7. The polymer thermosensor according to claim 1, wherein the olefin composition contains naphthylamine or hindered phenol. 8. The polymer thermosensor according to claim 1, wherein the olefin composition contains a phosphite compound. 9. A pair of electrodes provided concentrically, a polymer thermosensitive body according to claim 1 provided between said electrodes, and an insulating outside provided outside said electrodes. A temperature-sensitive element consisting of a layer.