JPS59196362A - Temperature-sensing element - Google Patents

Abstract

PURPOSE:To provide a high-molecular temperature-sensing element which has a high temperature sensitivity even against high-frequency current and exhibits less changes in characteristics in wet, by blending a specified polyester amide, a specified higher aliph. polyamide, copper halide, etc. in a specified ratio. CONSTITUTION:0.01-5pts.wt. at least one compd. (e.g. cuprous chloride or sorbitan) selected from copper halides (complex salt), alkali metal halides and surfactants is mixed with 100pts.wt. mixture consisting of a polyester amide (A) composed of 90-40wt% polyamide unit of formula I (wherein k is 10, 11) and 10-60wt% polyester unit of formulas II and/or III (wherein m is 3-11; n is 4- 10; R is a bivalent aliph. or alicyclic group) and 10-90wt% higher fatty acid polyamide (B) (e.g. nylon 11) wherein the number of carbon atoms per amide group in the molecular chain is 8 or greater. The titled temperature-sensing element is prepd. from the resulting resin compsn.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a heat-sensitive element used to control the temperature of heating appliances such as electric blankets and electric carpets. More specifically, the present invention relates to a novel polymer thermosensitive material which has high temperature detection sensitivity even at high frequencies and whose characteristics change little due to moisture absorption.

Utilizing the temperature dependence of the electrical properties of polymeric materials to use them as temperature sensing bodies, that is, heat-sensitive elements, has long been common, as can be seen in the case of electric blankets and electric carpets. Are known. In these heating appliances, one of the properties of the polymer material incorporated in the circuit as a temperature sensor, such as dielectric constant, DC resistance, and impedance, or a combination of two or more properties is selected as the control factor, and this is The temperature control circuit is operated by utilizing the fact that the characteristics of 4 and 4 change depending on the temperature P. The properties required for such a heat-sensitive element material include (1) the electrical properties of the polymer vary greatly with temperature (especially when an alternating current is applied,
(2) Changes in electrical properties due to moisture absorption are small, and (6) Excellent heat resistance. Can be mentioned. General polyamides have strong temperature dependence in electrical properties (and are also poor in heat resistance, mechanical properties, and moldability, and are particularly suitable for so-called high-grade polyamides such as nylon 11 and nylon 12, and high-grade holamides. Compositions to which electrical property improvers such as copper compounds and halogenated potassium metal salts are added have been put into practical use as suitable heat-sensitive and element materials. However, among polyamides, the amide group concentration is low (and even nylon 11 and nylon 12, which have relatively low hygroscopicity, cannot avoid the influence of moisture absorption. At the same time, there is a need for new materials that exhibit highly sensitive temperature sensing functions.

In addition, the temperature dependence of the countercurrent electrical properties of polyamide is 1.00.
In the high frequency range of 0H2 or higher, it is normal for the low frequency range of 50 to 60H2 to be lower than the low frequency range, but as temperature control circuits become more diverse, As things that use high frequencies appear,
At present, there is a strong demand for heat-sensitive element materials whose electrical properties have a sufficiently large temperature dependence even in the high frequency range.

Therefore, the present inventors have developed a method that has low hygroscopicity and 1,0
As a result of intensive study to develop a high-performance heat-sensitive element material that has high temperature detection sensitivity even in the high frequency range of 00Hz or higher, we found that a blend of a specific aliphatic polyester amide and a specific higher aliphatic polyamide was developed. The present inventors have discovered that a novel resin composition further mixed with an electrical property improving agent can provide a high-performance heat-sensitive element that satisfies the above-mentioned required performance, and has arrived at the present invention.

That is, the present invention provides (A) (a) 90 to 40 polyamide units by weight represented by the following formula (I) and (1)) the following (
A polyester amide composed of 10 to 60 polyester units represented by Yutake and/or formula (B), (B) the number of carbon atoms per amide group in the molecular chain is 8
The above higher aliphatic polyamide and (C) copper halide, complex salt of halogenated WJ, alkali metal halide salt,
and surfactants, (A) 90 to 10 parts by weight and (B) 10 to 9 parts by weight.
(C) 0.01 to 100 parts by weight including 0 parts by weight
The object of the present invention is to provide a high-performance heat-sensitive element characterized by comprising a resin composition mixed in a proportion of 5 parts by weight.

(-HN-(CH2)k-C-masu (1)
1 ・(0-(CH2), C÷ (I
O1 -E-0-R-0-C-(CH2)n-C-)
(@1 0 0 (where k is 10 or 11, m is 3 to 11, n is 4 to
An integer of 10, R represents a divalent aliphatic or alicyclic group.

) The heat-sensitive element of the present invention is made of polyester amide with essentially low hygroscopicity, higher aliphatic 6F with a low concentration of amide groups,
+) Since it is composed of amide, the amount of moisture absorbed is extremely small compared to conventional heat-sensitive elements made of polyamide, and it exhibits a stable temperature control function with less fluctuation in electrical characteristics due to moisture absorption. In addition, by combining the specified polyester amide, higher aliphatic polyamide, and electrical property improver, the dispersibility of the electrical property improver is good, and the effect of improving electrical properties is large (i, high frequency region of 000Hz or more e
In this case as well, it is possible to obtain a heat-sensitive element of high practical value whose electrical characteristics have extremely large temperature dependence.

The polyesteramide (A) used in the present invention is a copolymer obtained by copolymerizing a polyamide-forming component and a polyester-forming component. The polyamide unit (a) constituting this polyesteramide is an undecane amide unit or dodecan amide unit represented by the above-mentioned formula (I), and each is derived from the corresponding amino acid yalactam. On the other hand, among the polyester units (b), those represented by the formula Φ are derived from lactones, and examples of monomer raw materials include butyrolactone and caprolactone. Diol components forming the polyester unit represented include ethylene glycol, 1.5-propanediol, 2.2-
Examples include dimethy/l/-1,3-propanediol, 1,4-butanediol, 1,5-bentanediol, 1,6-hexanediol and 1,4-cyclohexane dimetatool, Dicarboxylic acids include adipic acid, azelaic acid, sebacic acid and dodecanoic acid.

A typical method for producing the polyester amide of the present invention is a method in which an amino acid or lactam as an amide component raw material, a lactone or di-p as an ester component, and a dicarboxylic acid are mixed, and the mixture is subjected to heating and reduced compression polymerization in the presence of a catalyst. However, the manufacturing method is not limited to this; for example, it is also possible to use a method in which one or both of the amide component and the ester component is made into an oligomer having an appropriate molecular weight, and then this is used as a raw material. The copolymerization ratio of polyesteramide is (a) polyamide units 90 to 4
0 weight ratio, ('b) polyester units 10 to less than 60 weight ratio, the effect of lowering moisture absorption is insufficient,
On the other hand, if it exceeds 60% by weight, the melting point of the polymer becomes too low (which may result in a lack of practical heat resistance), which is not preferable.

There are no particular restrictions on the degree of polymerization E of the above polyesteramide (orthochlorophenol K (measured at 25°C after dissolving 0.5 ml of polymer in ml of orthochlorophenol).
1.2 to 2.5 can be used.

The (B) higher aliphatic polyamide used in the present invention is:
It is a polyamide in which the number of carbon atoms per amide group in the molecular chain is 8 or more, and a specific example is nylon 11.
, nylon 12, nylon 61o1, nylon 612, nylon 116, and nylon 1112. These polyamides can be obtained by commonly known melt polymerization, interfacial polymerization, bath liquid polymerization, etc. using the corresponding lactam amino acids and salts of diamine and dicarboxylic acids as raw materials. Each of these polyamides can be used alone or in the form of a copolymer, and components such as nylon 6, nylon 66, nylon 6T, and nylon 6■ may also be incorporated within a range that does not impair properties such as moisture resistance. can.

The composition ratio of (A) polyester amide and (B) higher polyamide is 90:10 to 10:90, and (80:20,
, -2.9280 (weight ratio). If the content of polyesteramide exceeds 9 parts by weight, the molding processability of the polymer decreases, and if the content of the polyesteramide is less than 10 parts by weight, the effect of reducing moisture absorption is undesirable.

Compounds used as electrical property improving additives in the present invention (specific examples of 0 include steel chloride, cupric chloride, cuprous bromide,
Copper halides such as cupric bromide and cupric iodide, complex salts of these copper halides with organic compounds such as xylylene diamine, 2-mercaptobenzimidazole, and benzimidazole, -potassium iodide, iodide sodium,
halogenated alkali metal salts such as titanium fluoride and lithium chloride, alkylamide type polyoxine ethylene glycol type nonionic surfactants, phosphate ester type nonionic surfactants, sorbitan ester type nonionic surfactants, Examples include surfactants such as imidacillin type amphoteric surfactants and amidoamine type carboxylate type amphoteric surfactants. More specifically about surfactants, sorbitan, mannitol, or combinations of ethylene oxide adducts thereof and quaternary ammonium halide salts such as tetradenyldimethylpendylammonium chloride, dialkyl iv:7 combinations of ester compounds such as tricresyl phosphate, quaternary ammonium hydride salts such as tricresyl phosphate, and dioctyl mono[(
Examples include imidazole derivatives such as 2-methytV-3-bendi#-3-chloroimidazoni)V) methylcophosphate and 1-boly(ethylene glycol terephthalate)-2-methyl-6-pencyl-imidazolium chloride. It will be done. These additives can be used alone or in combination. The blending amount of these additives (C) is suitably 0.01 to 5 parts by weight, particularly 0.06 to 4 parts by weight, and 0.01 to 5 parts by weight, particularly 0.06 to 4 parts by weight, per 10 parts by weight of the mixture of base polymers (A) and (B). If it is less than 0.01 parts by weight, the effect of improving electrical properties is insufficient (on the other hand, if it exceeds 5 parts by weight, bleed-out of the additive becomes noticeable, which is not preferable).

There are no particular restrictions on the method of mixing (A) polyesteramide, (B) higher aliphatic polyamide, and (C) the king of electrical property modifiers (such as a Henschel mixer, etc.). A method of melt-kneading polyester amide and an electrical property improver with one of the polyester amide and then melt-kneading it again with the remaining resin; An appropriate method can be selected from methods such as adding an electrical property improver during the polymerization of one of the polyamides and melt-kneading the remaining resin.

The resin composition E of the present invention may be used during polymerization or after polymerization before molding, as long as its mechanical properties and electrical properties are not impaired. Antioxidants, thermal decomposition stabilizers, light stabilizers, hydrolysis resistance improvers, colorants, flame retardants, various molding aids, and the like can be added as appropriate.

The heat-sensitive element of the present invention can be obtained by supplying the resin composition to a common extruder or the like and molding it into a shape such as a heating wire or a sheet.

The present invention will be described in more detail with reference to Examples below. How are the characteristics in Examples and Comparative Examples evaluated? I did this.

(1) Relative viscosity of solution: Relative viscosity at 25°C of a solution in which 0.5 g of polymer is dissolved in 100 g of orthochlorophenol.

(2) Melting point: Perkin-E1mer DSC
- Melting peak temperature measured at a heating rate of 20° C./min using a type IB differential calorimeter.

(3) Moisture absorption rate: Polymer at 25℃ and 65%RH atmosphere
It was calculated from the weight increase when the equilibrium weight was reached.

(4) Thermistor properties: After drying the resin composition, a sheet with a thickness of about 0.2 hm is formed by melt pressing, and conductive paint is applied circularly on both sides of this sheet to form an electrode.
After measuring the AC resistance at a frequency e of OOHz, the volume specific impedance (Zsp) was calculated from the electrode area and sheet thickness. The Bz constant, which is a parameter of the thermistor property, was calculated from the volume specific impedance at 50° C. and 110° C. according to the following formula. The larger this value is, the more sensitive the thermal element becomes.

B□= Powerful Chivalry (Investment) Planning Takumi T: 323K
T,: 1/T, -1/T2 in 5B5 Example 1 87.3 parts by weight of 12-aminododecanoic acid, 16.2 parts by weight of dodecanoic acid, 11.4 parts by weight of 1,4-butanedio-1, and ester The mixture of catalysts was heated under an atmosphere of N2.
The reaction was carried out by heating at a temperature of 30°C for 5 hours, and then a polymerization catalyst was added to bring about a reaction condition of 250°C I Torr or less for about 1 hour, and then the polymerization reaction was carried out for about 2 hours. A polyesteramide was obtained in which the weight specific strength of the 12)' part and the polyester)v (PBD) part was 80:20, the relative viscosity was 1.65, and the melting point was 157°C. Next eResin obtained by mixing 70 parts by weight of the polyester amide, 50 parts by weight of nylon 11 (relative viscosity 1.80), and 0.1 part by weight of copper iodide in a Henschel mixer, and then melt-kneading in an extruder. From the composition to a thickness of 0,2. A sheet of 50 nm was prepared, its volume specific impedance was determined, and the Ez constant at 50 to 110°C was calculated.The moisture absorption rate of the resin composition was also measured, and the results shown in Table 1 were obtained. It was found that the heat-sensitive element obtained here had excellent cicada-like sensitivity, low hygroscopicity, and extremely high performance.

Examples 2 to 5 Example 1 except for changing the type and amount of the electrical property improver
A sheet with a thickness of 0.21111 was prepared from a similar resin composition, and its Bz constant and moisture absorption rate are shown in Table 1.These thermosensitive elements also have low moisture absorption and good sensitivity. It turned out to be extremely high performance.

Examples 6 to 8 Borien'? t-reamide (N-11/PB
D Iso 75/25 wt Chi, relative viscosity 1.68, melting point 16
1°C) 80 parts by weight, nylon 12 (relative viscosity 1.78)
Sheets with a thickness of 0.2 mm were prepared from a resin composition prepared by melt-kneading 20 parts by weight and various electrical property improvers, and the B
The Z constant and moisture absorption rate were measured in the same manner as in Example 1.
The results shown in the table were obtained.

The heat-sensitive element obtained here was also found to have good sensitivity, low moisture absorption, and high reliability.

Examples 9 to 11 Polyesteramide (N-12/PBS) obtained by polymerizing a mixture of 12-aminododecanoic acid, sebacic acid, and 1,4-butanediol by the method shown in Example 1.
=40/6Owt ratio, relative viscosity 1.57, melting point ios°C
) 60 parts by weight, nylon 12 (relative viscosity 1.78) 70
A sheet with a thickness of 0.2 sheets was prepared from a resin composition obtained by bath-melting and kneading parts by weight and various electrical property improvers, and the Bz constant and moisture absorption rate of the sheet were measured in the same manner as in Example 1.
table? I showed this. The heat-sensitive element obtained here also has excellent low hygroscopicity and sensitivity.

Comparative Example 1 A resin composition with a thickness of 0.2 mm made of a resin composition obtained in exactly the same manner as in Example 1 except that no electrical property improver was added.
The Bzqil number and moisture absorption rate of the sheet were determined and added to Table 1 as a comparative example. The heat-sensitive element obtained here is Bz
The constant is small and the sensitivity is insufficient.

Comparative Example 2 Nylon 12 (relative viscosity 1', 78)
．． Table 1 shows the properties of a 0.2 inch thick sheet made of the composition containing 1 part by weight. The heat-sensitive element made of this resin composition had a high moisture absorption rate, and its properties were insufficient for accurate temperature control.

(Blank below this page) 51 Continuation of page 1 0 shots Akira Tosaku Shujuki 9-1 Oecho, Minato-ku, Nagoya City Toshi Co., Ltd. Nagoya Plant

Claims (1)

[Scope of Claims] (A) (a) 90 to 40% by weight of polyamide units represented by the following formula (I) and (b) represented by the following formula (6) and/or -9 to (1) Polyester unit 10~
Polyesteramide, CB) composed of 60% by weight
Higher aliphatic polyamides having 8 or more carbon atoms per amide group in the molecular chain, and (C) a compound selected from copper halides, complex salts of copper halides, alkali metal halides, and surfactants. (A)9
0 to 10 parts by weight and (f3) 10 to 90 parts by weight, for a total of 100 parts by weight, and (c) 0.01 to 5 parts by weight of a resin composition. Sex elements. (-HN (CH2)k-C-)(I)1'co-(CHx)m C+
(II) 1 E-Ok'-0-C-(CH2)fr-C'-3-Qn
) 111 0 0 (where k is 10 or 11, m is 3-11, n is 4~
An integer of 10, R represents a divalent aliphatic or alicyclic group. )