JPS6311761B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a temperature sensing element used in a flexible linear temperature sensing wire used in a temperature sensing device for controlling the temperature of a heating element such as an electric blanket or an electric carpet. The purpose is to stabilize the impedance value. Until now, the polymer temperature-sensitive materials used for this type of purpose are polymer compositions made by adding a small amount of a substance that provides ionic conductivity, such as a surfactant, to a flexible resin such as soft polyvinyl chloride. things were being used. However, since the conductive carrier of these compositions is an ionic substance, polarization occurs when a direct current electric field is applied, making it impossible to use them as temperature sensitive bodies for temperature detection lines as the object of the present invention. . Furthermore, as seen in JP-A-51-12692, attempts have been made to suppress the polarization phenomenon by adding phosphoric acid, boric acid, or phosphorus or boron compounds. However, these compounds have high hygroscopicity, so polyamide compositions containing these compounds have a significant drop in impedance under high humidity.
There are some difficulties in putting it into practical use. As a similar example, Japanese Patent Publication No. 51-42314 discloses a composition in which moisture resistance is improved by introducing a hydroxyphenyl group or blending a phosphoric acid ester into a polyamide. However, in both of the above-mentioned compositions, the polyamide compositions containing phosphorus or boron compounds or phosphoric acid esters completely lose the flexibility and flexibility required for thermosensitive materials after being left in a high-temperature atmosphere. . The present invention eliminates these conventional drawbacks and provides a polymer thermosensitive material that has low polarization and hygroscopicity and does not suffer from deterioration in flexibility due to thermal deterioration. The thermosensitive material in the present invention is a composition in which a thiophosphite is blended with a polyamide. Here, thiophosphite esters collectively refer to the following compounds. Note that Z ₁ to _{Z 4} represent a sulfur atom or an oxygen atom, and at least one phosphorus-sulfur bond is included in the molecule. Moreover, the hydrocarbon group means an alkyl group, a phenyl group, or a phenyl group substituted with an alkyl group, and the alkyl group has 1 to 27 carbon atoms. (1 set (However, R ₁ to _{R 3} are hydrocarbon groups, and one of them may be a hydrogen atom.) Compounds represented by: tris(phenylthio) phosphite, bis(phenylthio) monodecyl phosphite, bis (laurylthio) hydrogen phosphite, etc. (2) Equation (However, R ₁ and R ₂ are hydrocarbon groups, and R′ is a hydrocarbon group with one extra bond or the case where nothing is bonded to the oxygen atom.) The group shown by represents a carbon atom. Compounds linked by a linking chain comprising: tetrakis(phenylthio)dipropylene glycol diphosphite, Tetrakis(phenylthio)tetrakis(tridecylthio)pentaerythritol tetraphosphite Such. (3) Equation (However, R ₁ to _{R 5} are hydrocarbon groups, n is a natural number) Polymer represented by: Hydrogenated thiobisphenol A phosphorite polymer Such. All of these materials have excellent polarization resistance, heat deterioration resistance, and moisture resistance. Here, the blending amount of thiophosphite is polyamide 100.
Good results are obtained when the amount is 0.01 to 10 parts by weight. When the amount is less than 0.01 part by weight, sufficient polarization resistance, heat deterioration resistance, or moisture resistance cannot be imparted.
On the other hand, if it exceeds 10 parts by weight, sufficient compatibility with polyamide will be impaired, which is not preferable. Furthermore, compositions containing these thiophosphite esters together with certain phenolic antioxidants in polyamides have better polarization resistance and heat deterioration resistance than when each is used alone. found. Incidentally, the combined use of additives of this kind is generally widely used for the purpose of preventing oxidation of plastics, and many examples have been reported in which synergistic effects have been observed in preventing deterioration of mechanical properties and the like. In the present invention, the phenolic antioxidant is a general term for the following, and all of them are compounds that are blended into polyamides with thiophosphite esters to impart good polarization resistance and heat deterioration resistance to the composition. refers to The classification and specific examples of phenolic antioxidants are shown below. (1) Hydroquinone derivative a Hindered form: 2,5-di-t-butylhydroquinone, b Others: Hydroquinone monomethyl ether (2) Phenol derivative a Hindered form Monophenolic 2,6-di-t-butylphenol, 2, 6-di-t-butyl-4-ethylphenol Bisphenol 2,2'-methylenebis(4-methyl-6-t
-butylphenol) Trisphenol, tetrakisphenol Tetrakis [methylene-3-(3′,5′-di-
t-Butyl-4'-hydroxyphenyl)propionate]methane b Others: Monophenolic 2(2'-hydroxy-5'-methylphenyl)benzotriazole (3) Thiobisphenol derivative hindered form: 4,4'-thiobis(3-methyl-6-t-butylphenol) 2,2'-thiobis(4-methyl-6-t-butylphenol) In addition, in the above, the hindered form means that t is present at at least one of the ortho positions of the hydroxyl group.
- Refers to those into which a large group such as a butyl group has been introduced. The amount of phenolic antioxidant added to impart good properties depends on the amount of thiophosphite added, but it is based on 100 parts by weight of polyamide.
A suitable amount is 0.01 to 20 parts by weight. If it is less than 0.01 parts by weight, no significant synergistic effect is observed, and if it is more than 20 parts by weight, the mechanical properties of the composition itself are impaired. However, a particularly desirable method of use is to add 0.1 to 1.0 parts by weight of the thiophosphite and 1 to 10 parts by weight of the phenolic antioxidant to 100 parts by weight of the polyamide. This is because phenolic antioxidants generally have good compatibility with polyamide compositions and can be added in large amounts, whereas thiophosphite esters have slightly poor compatibility. Apart from the synergistic effect, phenolic substances generally have the effect of improving the moisture resistance of polyamide compositions, and this also makes the above method of use recommended. Better results can be obtained by increasing the amount of at least one of thiophosphites and phenolic antioxidants.
By appropriately increasing or decreasing both, it is possible to obtain a composition that corresponds to the degree of polarization resistance and heat deterioration resistance to be achieved. Particularly excellent effects can be achieved when a thiobisphenol derivative is used as the phenolic antioxidant. The reason for this is that this compound contains a sulfur atom in its molecule, which may have a unique interaction with the thiophosphite molecule. It goes without saying that plasticizers and fillers that are generally added to polyamides can also be appropriately added to these compositions. The structure of the temperature detection line, which is the object of the present invention, is as shown in FIG. That is, 1 is a heat-resistant core thread, 2 and 3 are inner and outer electrical conductor wires, respectively. 4 is a polymer temperature sensitive body interposed between the electric conductor wires 2 and 3, and 5 is a jacket. Either one of the conductor wires 2 or 3 can serve as a heater, and is electrically heated by applying a direct current or a half-wave rectified wave, for example. Temperature detection is carried out by applying an alternating current voltage between the inner and outer electric conductor wires and detecting changes in the impedance of the polymer thermosensitive body due to changes in temperature. Next, the present invention will be explained in more detail with reference to Examples. Example 1 Tris(phenylthio) phosphorite to 100 parts by weight of polydodecanamide (nylon 12)
0.01 part by weight was added, extruded into a gut shape using an extruder, and then pelletized. The pellets were dried and passed through a wire-making extruder to form temperature detection wires. Example 2 A temperature detection line was prepared in the same manner as in Example 1 by adding 10 parts by weight of tetrakis(phenylthio)dipropylene glycol diphosphorite to 100 parts by weight of polyundecaneamide. Example 3 0.2 parts by weight of bis(phenylthio)monodecyl phosphorite and 2,2'-methylenebis(4-methyl-
6-t-butylphenol) 2.0 parts by weight was added,
Similarly, it was used as a temperature detection line. Example 4 0.5 parts of bis(laurylthio)hydrogen phosphorite per 100 parts by weight of polydodecanamide
Parts by weight and 2,2'-thiobis(4-methyl-6
-t-butylphenol) 5.0 parts by weight was added,
Similarly, it was used as a temperature detection line. Example 5 Hydrogenated thiobisphenol A phosphorite polymer based on 100 parts by weight of polyundecaneamide
0.1 part by weight and 10 parts by weight of 4,4'-thiobis(3-methyl-6-t-butylphenol) were added to form a temperature detection line. Conventional example 1 Phosphoric acid for 100 parts by weight of polydodecanamide
1.0 parts by weight was blended to form a temperature detection line. Conventional Example 2 A temperature detection line was prepared by blending 10 parts by weight of tris(p-hydroxyphenyl) phosphate with 100 parts by weight of polydodecanamide. Conventional Example 3 Polydodecanamide alone was used as a temperature detection line in the same way. Conventional Example 4 A temperature detection line was similarly made using polyundecaneamide alone. As a reference example, 2,2'-thiobis(4-methyl-6
- 5.0 parts by weight of t-butylphenol) was added and a temperature detection wire was assembled in the same manner. The following table shows a comparison of various characteristics between the temperature sensitive body shown in the above example and the temperature sensitive body shown in the conventional example and reference example.

【table】

[Table] As is clear from the above results, Examples 1 and 2
The polymer temperature sensitive body used in the temperature sensitive heater has better polarization resistance and heat deterioration resistance than polydodecanamide (nylon 12) and polyundecaneamide (nylon 11) alone in conventional examples 3 and 4, respectively. It can be seen that both the film and the moisture resistance are excellent. Furthermore, the polydodecanamide composition of Example 1 has greatly improved heat deterioration resistance and moisture resistance compared to the composition containing phosphoric acid of Conventional Example 1, and has significantly improved heat deterioration resistance and moisture resistance compared to the composition of Conventional Example 1 containing tris(p-hydroxyphenyl) phosphate. It can be seen that the heat deterioration resistance is significantly improved compared to the blended composition. Furthermore, as can be seen in Examples 3 to 5,
When a thiophosphite and a phenolic antioxidant are used in combination, the effect of improving polarization resistance and heat deterioration resistance is remarkable. In particular, as seen in Examples 4 and 5, the effect of the thiobisphenol system is extremely excellent, completely preventing an increase in impedance value when a DC electric field is applied. As described above, it can be seen that the polymeric temperature sensitive material of the present invention has excellent electrical and mechanical properties. Example 6 2, based on 100 parts by weight of polydodecanamide
Add 5.0 parts by weight of 2'-thiobis(4-methyl-6-t-butylphenol) to make a masterbatch, and then add 0.01, 0.1, 0.5, and 1.0 parts by weight of tris(phenylthio) phosphorite to the masterbatch separately. These were each used as temperature detection lines in the same manner as in Example 1. These four types of samples were further divided into five groups, and each was placed in a dryer at 120℃ to increase the temperature from 10V/mm to 50V/mm.
The applied DC electric field was changed in increments, and electric fields of these strengths were applied to each sample for 300 hours. The impedance ratio before and after application was calculated, and the relationship between electric field strength and impedance ratio was plotted using the amount of tris(phenylthio) phosphorite added as a parameter. These results are shown in FIG. 2, using as a reference example a sample to which tris(phenylthio)phosphite was added. In the figure, the numerical value at the shoulder of the curve indicates the amount of tris(phenylthio)phosphite added (hereinafter expressed as phr) with respect to 100 parts by weight of polydodecanamide. As can be seen from Figure 2, when applying an electric field of the same electric field strength, the impedance ratio decreases as the amount of tris(phenylthio) phosphite added increases, and when compared with the reference example.
Sufficient effects were observed even with addition of 0.01 phr. Further, by changing the amount added depending on the electric field strength applied to these temperature detection lines, it is possible to obtain a composition optimal for a polymeric temperature sensitive body. For example, as shown in Figure 2, when applying an electric field of 10 V/mm to a polymer thermosensitive material,
The amount of tris(phenylthio) phosphite added should be 0.1phr, 20V/mm, 40V/mm~
In the case of 50V/mm, excellent results can be achieved by adding 0.5 phr and 1.0 phr, respectively. Example 7 1.0 parts by weight of tetrakis(phenylthio)tetrakis(tridecylthio)pentaerythritol tetraphosphite was added to 100 parts by weight of polyundecaneamide to prepare a masterbatch, and then 4,4'-thiobis(3-methyl-6- t-
butylphenol) 0.01, 1.0, 5.0, respectively
20 parts by weight were separately added to the masterbatch, and each was used as a temperature detection line in the same manner as in Example 1. These four types of samples were further divided into five groups, each of which was placed in a dryer at 120℃ in the same way as in Example 6, and a DC voltage was applied from 10V/mm to 50V/mm in 10V/mm increments. Electric fields of these intensities were applied to each sample for 300 hours by varying the field.
Calculate the impedance ratio before and after application, and calculate the electric field strength using the added amount (phr) of tetrakis(phenylthio)tetrakis(tridecylthio)pentaerythritol tetraphosphite as a parameter.
The relationship between impedance ratios was plotted. These results are shown in FIG. 3, using as a reference example a sample to which tetrakis(phenylthio)tetrakis(tridecylthio)pentaerythritol tetraphosphite was not added. As can be seen from Figure 3, when applying an electric field with the same electric field strength, as the amount of tetrakis(phenylthio)tetrakis(tridecylthio)pentaerythritol tetraphosphite added increases, the impedance ratio decreases, and when compared with the reference example, the impedance ratio becomes 0.01. Sufficient effects were observed even with the addition of phr. Further, by changing the amount added depending on the electric field strength applied to these temperature detection lines, it is possible to obtain an optimal composition as a polymeric temperature sensitive body. These matters are the same as in the sixth embodiment. For example, as can be seen from Figure 3, when the amount of tetrakis(phenylthio)tetrakis(tridecylthio)pentaerythritol tetraphosphite added is 1.0, 5.0, and 20 phr, respectively, the electric field applied to the polymer temperature sensitive body is The intensities are 10V/mm, 15V/mm and 30V/mm, respectively.
Excellent results can be achieved by setting it to mm. These things are related to the field strength of the electric field applied to the polymer temperature sensitive body and the required heat resistance when the temperature detection wire shown in Examples 6 and 7 is incorporated into a heating device such as an electric blanket or electric carpet. This means that by simply increasing or decreasing the amount of thiophosphite (or thiobisphenol) added depending on the degree of oxidation, it is possible to easily obtain a polymer thermosensitive material most suitable for the heating device. . As can be seen from the above examples, the polymeric temperature sensitive material of the present invention not only has excellent electrical and mechanical properties, but also has the advantage that it can be used in a wide range of applications as a temperature sensitive material.

[Brief explanation of the drawing]

Figure 1 shows the configuration of a temperature detection line using a thermosensor, and Figures 2 and 3 show the application of temperature detection lines using polyamides with different contents of thiophosphites as the thermosensor. The relationship between electric field strength and impedance ratio is shown. 1... Core yarn, 2, 3... Electric conductor wire, 4... Polymer temperature sensitive body, 5... Outer cover.

Claims (1)

[Scope of Claims] 1. A polymer thermosensitive material comprising a polyamide composition containing a thiophosphite. 2 Thiophosphite esters are polyamide 100
The polymer thermosensitive material according to claim 1, which is contained in an amount of 0.01 to 10 parts by weight. 3. The polymer temperature sensitive body according to claim 1 or 2, wherein the polyamide composition contains a phenolic antioxidant. 4. The polymer thermosensitive material according to claim 3, wherein the phenolic antioxidant is contained in an amount of 0.01 to 20 parts by weight based on 100 parts by weight of the polyamide. 5. The polymer thermosensitive material according to claim 3 or 4, wherein the phenolic antioxidant is a thiobisphenol antioxidant.