JPS61154103A - Heat 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] <Industrial Application Field> The present invention relates to a heat-sensitive element made of a novel resin composition,
More specifically, the present invention relates to a high-performance heat-sensitive element particularly excellent in bending fatigue resistance, which is used as a sensor material for controlling the temperature of heating appliances such as electric blankets and electric carpets.

<Prior art> The use of polymeric materials as temperature sensors by utilizing the temperature dependence of their electrical properties has been well known for a long time, as seen in the case of electric blankets and electric carpets. It is being

In these heating devices, one or a combination of two or more properties of the polymer, such as dielectric constant, DC resistance, and impedance, are selected as the control factor, and the fact that these properties change with temperature is utilized. This activates the temperature control circuit. The characteristics required of such a heat-sensitive element material are (1) large changes in the electrical properties of the polymer due to temperature, that is, high temperature detection sensitivity;
(2) Changes in electrical characteristics due to moisture absorption are small; (3)
(4) excellent mechanical properties, especially bending fatigue resistance; and (4) excellent mechanical properties, especially bending fatigue resistance. In general, polyamides have electrical properties that are highly temperature dependent, and are also materials with excellent heat resistance, mechanical properties, and moldability. Among them, so-called high-grade polyamides such as nylon 11 and nylon 12 are suitable as materials for heat-sensitive elements. It is put into practical use. However, polyamide is inherently hygroscopic, and even nylon 11 and nylon 12, which have relatively low hygroscopicity among polyamides, inevitably change in properties due to moisture absorption. In order to reduce the hygroscopicity of nylon and improve the temperature detection sensitivity to obtain a high-performance heat-sensitive element material, methods using a mixture of nylon and a low polymerization degree phenolic resin (for example, No. 117) or a method using graft copolymerized 7-pot type phenol resin on nylon (for example, Japanese Patent Publication No. 117-3).
No. 7640) is disclosed.

<Problems to be Solved by the Invention> Although these methods are effective in terms of moisture resistance, on the other hand, introducing phenolic resin into nylon impairs nylon's inherent toughness and bending fatigue resistance. Even if a 7-enol resin with a low degree of polymerization is used to reduce the decrease in bending fatigue resistance, for example, if an electric blanket is folded, curled, or wrinkled during use, It is difficult to withstand the harsh bending conditions assumed. In addition, these materials still lack temperature detection sensitivity, and there is a long-awaited high-performance heat-sensitive element material with even higher sensitivity, lower moisture absorption, and excellent mechanical properties such as resistance to bending fatigue.

An object of the present invention is to provide a high-performance heat-sensitive element material that has higher sensitivity and lower moisture absorption than conventional materials, and has excellent mechanical properties such as bending fatigue strength.

Means for Solving the Problems> The above problems are (1) (c) (a) 90 to 10% by weight of polyamide units represented by the following formula (1) and (b) the following (2)
) A polyester amide composed of 10 to 90% by weight of polyester units represented by the formula (B) (c) 90 to 60% by weight of polyamide units represented by the following formula (1) and (d) the following formula (3) and /or 100 parts by weight of at least one polyesteramide selected from polyesteramides composed of 10 to 40% polyester units represented by formula (4) and 1 to 50 parts by weight of (It) phenol formaldehyde resin. The problem is solved by providing a heat-sensitive element characterized by being made of a kneaded resin composition.

k is an integer of 4 to 10, and R represents a divalent aliphatic or alicyclic group having 2 to 10 carbon atoms. ) The present invention will be explained in detail below.

Among the polyesteramides used in the present invention, the polyesteramide represented by ^ is a polyesteramide in which the polyamide portion is (1)
It is a copolymer consisting of undecaneamide or dodecanamide units represented by the formula, and the polyester portion is composed of butylene terephthalate or butylene inphthalate units. ξ-poor is obtained by polycondensing monomer raw materials such as lactam, l, 4-butanediol, terephthalic acid and its esters, and isophthalic acid and its esters, and is disclosed in, for example, JP-A-56-88428. It is manufactured by a similar method. The copolymerization ratio of the polyamide portion and the polyester portion must be within the range of 90/10 to 1 O/90% by weight; if it is out of this range, the bending fatigue resistance of the copolymer will be undesirably reduced.

Among the polyesteramides used in the present invention, the (C) polyamide unit constituting the polyesteramide represented by be guided. On the other hand, among the bridged polyester units, those represented by formula (3) are derived from lactones, and examples of monomer raw materials include butyrolactone, caprolactone, and the like.

In addition, as the diol component forming the polyester unit represented by formula (4), ethylene glycol, 1,3-
Propanediol, 2,2-dimethyl-1,3-furopanediol, 1,4-butanediol, 1,5-bentanediol, 1,6-hexanediol, l,4-cyclohexane dimetatool, etc. Examples of dicarboxylic acids include adipic acid, azelaic acid, sepacic acid, and dodecanedioic acid.

The above-mentioned polyesteramide can be produced from the above-mentioned raw materials using the method disclosed in, for example, Japanese Patent Application Laid-Open No. 57-207644.

The copolymerization ratio of polyamide part and polyester part is 90
/10 to 60/40% by weight, and if the polyamide portion exceeds 90% by weight, the bending fatigue resistance of the polymer will decrease significantly, and the polyamide portion must be in the range of 60% by weight.
If the melting point of the polymer is lower than , the melting point of the polymer will be too low and it will not be practical as a heat-sensitive element used in the heat-generating part of a heating appliance.

The above-mentioned polyesteramide itself can be used as a heat-sensitive element material with poor temperature sensing ability and mechanical properties.
For example, JP-A-57-206001゜58-13662
Publication No. 4) By combining it with a phenol resin, it becomes an extremely excellent heat-sensitive element material with further improved moisture resistance and electrical property stability.

(1) Phenol-formaldehyde resin used in the present invention is obtained by condensation polymerization of phenol, alkylphenol, phenol derivatives such as oxybenzoic acid esters, and formaldehyde under a conventional acid catalyst. When phenol undergoes condensation polymerization with formaldehyde, there are a total of three reaction sites: both ortho positions and the rose position.

When alkylphenols substituted at one of these positions, oxybenzoic acid esters, etc. are used as raw materials, most of the phenolic resins produced have a linear structure, and the linear phenolic resins obtained in this way have a linear structure. The average molecular weight usually ranges from 200 to 2000. On the other hand, when the raw material is phenol in which no reaction site of phenol is substituted, a crosslinked three-dimensional structure is formed. In the present invention, phenolic resins with a linear structure can of course be used, and even phenolic resins with a partially crosslinked three-dimensional structure can have extremely high crosslinking density and must be completely cured. It can be used if

For example, a phenol resin with an appropriately controlled crosslinking density, such as a granular phenol resin commercially available from Kanebo Co., Ltd. under the trade name "Bel Pearl", is preferably used in the present invention.

The blending amount of the medium polyester amide component and ('I) phenol formaldehyde resin component must be within the range of (■) 1 to 5 parts by weight of phenol formaldehyde resin to (■) iomm parts of the polyester amide component. , 5 to 40 parts by weight of (I) phenol formaldehyde resin per 100 parts by weight of (I) polyesteramide component.
More preferably, the range is parts by weight. If the content of phenol formaldehyde resin is less than 1 part by weight, it is disadvantageous because the hygroscopicity of the polymer increases, while if the content of phenol resin exceeds 50 parts by weight, the material becomes hard and brittle and the bending fatigue resistance is impaired. Therefore, it is inconvenient.

The method of mixing polyesteramide and phenol resin is not particularly limited, and a commonly known method can be employed. In other words, there are methods in which polyesteramide and phenolic resin pellets, powder, pieces, liquid, etc. are uniformly mixed using a high-speed stirrer and then melt-kneaded using an extruder. Any method can be adopted, such as a method of blending and extrusion molding, or a method of melt-kneading using a Banbury mixer or a rubber roll machine.

Electrical property improving materials such as copper halides, complex salts of copper halide, alkali metal halides, and surfactants may be further added to the resin composition of the present invention as long as the stability of its electrical properties is not impaired. Other additives such as antioxidants, thermal decomposition stabilizers, light resistance agents, hydrolysis resistance improvers, colorants, flame retardants, various molding aids, etc. can also be added as long as they do not impair mechanical properties or electrical properties. can be used as appropriate.

A heat-sensitive element can be obtained by feeding the resin composition into a conventional extruder or the like and molding it into a shape such as a heating wire or a sheet.

<Function> It is extremely important to combine the polyesteramide and phenol resin as the heat-sensitive element material of the present invention.

By using a specific polyester amide, which is inherently extremely flexible and has excellent bending fatigue resistance, a material with excellent bending fatigue resistance and durability that cannot be obtained with a combination of nylon and phenolic resin can be obtained. The moisture resistance of the amide was effectively improved by the added phenol resin, and an extremely excellent heat-sensitive element material with good electrical properties, moisture resistance, and durability was obtained.

<Example> The present invention will be explained in more detail by giving examples below. In addition, evaluation of various properties in the following Examples and Comparative Examples was performed as follows.

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

(2) Melting point: Perkin-Elmer @DSC
- Melting peak temperature when measured at a heating rate of 20° C./min using a type I B differential calorimeter.

(3) Moisture absorption rate: Calculated from the weight increase when the polymer was placed in an atmosphere of 25° C. and 65% RH and the equilibrium weight was reached.

(4) Thermistor properties: After drying the resin composition, a sheet with a thickness of about 0.2cm is formed by melt pressing, and this “
Conductive paint was applied circularly on both sides of the sheet to form electrodes, and after measuring the AC resistance at a frequency of 120k,
Volume specific impedance (Zs
p) was calculated. B is a parameter of thermistor characteristics from the volume specific impedance at 50℃ and 110℃
The z constant was calculated according to the formula below. The larger this value is, the more sensitive the heating element becomes.

(6) Flexural fatigue resistance: The resin composition is melted in a hot press, then cooled in a cooling press to create a press sheet with a thickness of 1 mm, and a test piece with a width of 5 fi and a length of 80 fi is cut from this sheet. , Load l#, bending angle 2700, speed 12 () using Toyo Seiki's new MIT soft fatigue resistance tester.
A bending test was conducted under the conditions of bending times/minute, and the number of bends until the test piece broke was measured to determine the bending fatigue resistance.

Example 1 A mixture of 54.5 parts by weight of 11-decanoic acid, 12.5 parts of terephthalic acid (ffi parts), and 12.2 parts by weight of 1,4-butanediol was heated at a temperature of 230° C. under N atmosphere. After about 1 hour of adding a polymerization catalyst, the reaction conditions are brought to 250°C and 1 Torr or less, and the polymerization reaction is further carried out for about 2 hours to separate the polyamide (N-11) part and polyester (PBT) part. Weight ratio is 75:25, relative viscosity 153, melting point 153°C
A polyesteramide was obtained.

Next, 85 parts by weight of this polyesteramide and 15 parts by weight of granular phenolic resin "Perval" S-930 manufactured by Kanebo Co., Ltd. were tri-blended in a Henschel mixer, and then melt-kneaded in an extruder to obtain a resin composition with a thickness of 0. .2 m
A sheet was prepared to be used as a sample for measuring electrical properties and hygroscopicity, and a sheet with a thickness of ``law'' was made to be used as a sample for measuring bending fatigue resistance.The respective properties were measured, and the results shown in Table 1 were obtained.

It has been found that the heat-sensitive element obtained here has good sensitivity, excellent bending fatigue resistance, and is of extremely high performance with little influence of humidity.

Comparative Example 1 The properties of a resin composition obtained by melt-kneading in exactly the same manner as in Example 1 except that Nimen 12 was used instead of the polyesteramide resin were measured according to Example 1, and the results are shown in Table 1. It was shown to. This product has low bending fatigue resistance and cannot be put into practical use.
-It was unbearable.

Example 2 Raw materials include 22.9 parts by weight of 12-aminododecanoic acid, 37.0 parts by weight of terephthalic acid, and 3 parts by weight of 1,4-butanediol.
Polymerization was carried out in exactly the same manner as in Example 1 except that 6.1 parts by weight was used, and the weight ratio of the polyamide (N-12) part and the polyester (PBT) part was 30 near 0. The properties of a resin composition obtained by melt-kneading 70 parts by weight of polyester amide having a relative viscosity of L52 and a melting point of 171°C and 30 parts by weight of °°Bebelur' S-930 were measured in the same manner as in Example 1 and are shown in Table 1. The results were obtained. The heat-sensitive element obtained here was also found to be an excellent heat-sensitive element with high bending resistance, moisture resistance, and temperature measurement sensitivity.

Example 3 A resin composition obtained by melt-kneading 20 parts by weight of a phenol resin obtained by condensation polymerization of P-nonylphenol and formalin under an acidic catalyst and 80 parts by weight of the polyesteramide prepared in Example 1. The mechanical properties were measured in the same manner as in Example 1, and the results are shown in Table 1.

Examples 4 to 6 Table 1 shows the properties of various R1 compositions obtained by changing the types and mixing ratios of the polyesteramide and phenol resin used. All of the heat-sensitive elements obtained here were extremely high-performance heat-sensitive elements having high sensitivity, high moisture resistance, and high durability.

<Effects of the Invention> The present invention provides a high-performance heat-sensitive element that has excellent bending fatigue resistance that cannot be obtained with conventional combinations of nylon and phenol resin, and also has high sensitivity and low moisture absorption.

By using such high-performance heat-sensitive elements, the durability of heating appliances such as electric blankets and electric carpets can be improved, and temperature control can also be made more precise.

Patent Output Toshi Co., Ltd.

Claims (1)

[Scope of Claims] (I) (A) (a) 90 to 10% by weight of polyamide units represented by the following formula (1) and (b) 10 to 90% by weight of polyester units represented by the following formula (2) Constituent polyesteramide and (B) (c) 90 to 60% by weight of polyamide units represented by the following formula (1) and (d
) 100 parts by weight of at least one polyesteramide selected from polyesteramides composed of 10 to 40% by weight of polyester units represented by the following formula (3) and/or (4) and (II) phenol formaldehyde resin A heat-sensitive element comprising a resin composition obtained by kneading 1 to 50 parts by weight. ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (1) ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (2) ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (3) ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ ( 4) (Here, i is 10 or 11, j is an integer from 3 to 11, k
represents an integer of 4 to 10, and R represents a divalent aliphatic or alicyclic group having 2 to 10 carbon atoms. )