JPH0251927B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a polymer thermosensitive material made of a polyamide copolymer, and particularly to a thermosensitive material in a device that controls temperature using electrical resistance or electrical resistance and capacitance as control factors. The present invention relates to a polymer thermosensitive body with improved effects caused by. Polymer thermosensitive materials are often used as constituent materials for electric wires for heating elements such as electric blankets and electric carpets. (2) small fluctuations in electrical properties depending on the environment in which the heating element is used, especially humidity; (3) mechanical strength and electrical properties within the normal operating temperature range. (4) it has a clear melting point to cope with abnormal temperature rises, etc. Polymer materials known to have been used as thermosensors include polyvinyl chloride, cellulose esters, polyamides, copolymers of acrylic esters and acrylonitrile (Japanese Patent Publication No.
Publication No. 1627), Special Publication No. 1976-7635, Special Publication No. 1973
-Refer to Publication No. 14179). Examples of applications of heat-sensitive temperature control lines or surfaces using these polymeric materials are shown in FIGS. 1A and 1B. A is a partially cutaway perspective view showing an example of a heat-sensitive temperature control line, which essentially consists of an insulating material 1, a core wire 2, a polymer temperature-sensitive body 3, a signal line 4, and a heater line 5. Further, B is a sectional view showing an example of a heat-sensitive temperature control surface. With this configuration, the temperature can be detected along the thermosensitive temperature control line or surface by utilizing the fact that the electrical characteristics of the polymer thermosensitive body 3, that is, the resistance value, impedance, or capacitance, change depending on the temperature. and control. Among the polymer materials mentioned above that are known as polymer thermosensors, polyamide resin has
Since it has excellent mechanical properties, heat resistance, moldability, etc., it is often used as a polymer thermosensitive material. Furthermore, polyamide resin is a crystalline polymer and has a clearer melting point than other resins, making it possible to cope with abnormal temperature rises. That is, when a polyamide resin is used for the polymer thermosensitive body 3 shown in FIGS. 1A and B, the melting point of the polyamide resin is around 200°C, and the temperature of the exothermic wire may exceed the melting point due to abnormal temperature rise. When this occurs, the polymer thermosensitive body melts, causing a short circuit between the heating wire 5 and the signal wire 4 shown in FIGS. 1A and 1B, and it becomes possible to activate the safety device. However, typical polyamide resins such as nylon 6 or nylon 66, as described in Japanese Patent Publication No. 1627/1982, have too high water absorption as heat-sensitive materials, so they cannot be used as heat-sensitive wires for electric blankets, for example. As is already known, even if a moisture-proof film of polyvinyl chloride or the like is formed as the outermost layer, it is difficult to obtain substantially complete moisture resistance. For this reason, nylon 6 or nylon 66
The control temperature point of a heat sensitive body using a heat sensitive body varies considerably depending on the environmental conditions in which it is placed. That is,
Nylon 6 or nylon 66 has extremely high water absorption ability, and its electrical properties vary significantly depending on the environmental conditions in which it is used, so it is practically used as an electric blanket,
It is impossible to use it as a heat-sensitive wire for electric carpets, etc. This disadvantage increases synergistically when water-absorbing additives such as surfactants are added. Currently, the best polymer thermosensor is
Nylon 11, nylon 12, or nylon 11, nylon 12, nylon 6/12, nylon 12/12, and polyvinyl chloride are known. However, although polyvinyl chloride has fewer problems regarding water absorption, it does not have sufficient heat resistance and does not have a clear melting point, so it is difficult to integrate the heating wire and the sensor wire. On the other hand, nylon 11 and nylon 12 are nylon 6,
Although its water absorption properties are improved compared to nylon 66,
In today's world, where highly accurate temperature control is required, the water absorption rates of Nylon 11 and Nylon 12 are not sufficiently low, and the control temperature varies greatly between drying and water absorption. This variation tends to further increase synergistically when a water-absorbing electrical property improver is added. The present inventors solved the above problems, especially humidity (water absorption).
The fluctuation in electrical properties is small, that is, the equilibrium water absorption rate is small, and the electrical properties are
As a result of intensive study of polymer thermosensitive materials that are equivalent to or higher than 12, we found that the water absorption rate of a copolymer consisting of polybutadiene and a polyamide polymer component whose both terminals are carboxylic acid groups or amino groups is already low. and found that this copolymer is effective as a polymeric thermosensitive material (Japanese Patent Application No. 183277/1983). However, since this copolyamide contains double bonds in its molecules, it is relatively easily altered by heat, and it is difficult to control the extrusion processing conditions normally used, such as the generation of gel during wire coating or film forming. It may cause difficulties. The inventors of the present invention have conducted intensive studies to improve the processability problem and further improve heat resistance.
It has been discovered that polybutadiene, in which both ends are carboxylic acid groups or amino groups and the double bonds are hydrogenated, copolymerizes with commonly used polyamide resin monomers, and furthermore, the copolymer has a low water absorption rate.
The present invention was achieved by discovering that it has good thermal stability and extrusion processability is equivalent to that of polyamide homopolymer. That is, the present invention uses 99 to 5 parts by weight of a polyamide polymer component having one or more types of repeating units represented by the following general formula (1) or (2) and an average molecular weight of 500 to 10,000, which has carboxylic acid groups or amino groups at both ends. By copolymerizing 1 to 95 parts by weight of a polybutadiene component whose double bonds are hydrogenated, a copolyamide with low water absorption and improved thermal stability was obtained. (1) -NH( _CH2 )nCO- (n is an integer of 5 to 11) (2) -NHXNHCOYCO- [X is _CmH2m (m is an integer of 6 to 12), isophorone group, phenylene group, or cyclohexylene Base, Y is
ClH ₂ l (l is an integer from 4 to 10), represents a phenylene group or a cyclohexylene group] This copolyamide has a low water absorption rate, and therefore, when used as a polymeric temperature sensitive material in electric blankets and electric carpets. , fluctuations in the control temperature point due to changes in environmental conditions, especially humidity, are small, making highly accurate temperature control possible. Monomers constituting the polyamide polymer component described in the present invention include, for example, caprolactam, lauryllactam, 11-aminoundecanoic acid, 12-aminododecanoic acid, hexamethylene adipamide, hexamethylene sebapamide, hexamethylene dodecamide, and terephthalate. These include acid, diamine salts of dibasic acids having a ring such as cyclohexanedicarboxylic acid, dibasic acid salts of phenylenediamine, cyclohexanediamine, and isophoronediamine, and the like. Polybutadiene in which a double bond having a carboxylic acid group or an amino group at both ends is hydrogenated is produced by hydrogenating polybutadiene having a carboxylic acid group or an amino group at both ends. The polybutadiene to be hydrogenated may contain any bonds such as 1.2 bonds, 1.4 trans bonds, 1.4 cis bonds, etc., but from the viewpoint of ease of hydrogenation, it is desirable to have a large proportion of 1.2 bonds. It is technically difficult to perform complete hydrogenation, so polybutadiene with a hydrogenation rate of 70% or more is preferably used, and polybutadiene with a hydrogenation rate of 90% or more is more preferably used. It is technically difficult to carboxylate or aminate 100% of both ends of polybutadiene, and therefore it is difficult to convert 100% of the ends of hydrogenated polybutadiene into carboxylic acid groups or amino groups. Hydrogenated polybutadiene with a carboxylic acid terminal ratio or amino terminal ratio of 60% or more is preferably used, and hydrogenated polybutadiene with a large terminal ratio of 75% or more is more preferably used. If the molecular weight of the hydrogenated polybutadiene is less than 500, the effect of reducing water absorption will be small, and if it is greater than 10,000, it will be difficult to obtain desirable physical properties. When the polyamide polymer component exceeds 99 parts by weight, each property is almost the same as that of polyamide homopolymer, and water absorption does not decrease. If the hydrogenated polybutadiene component exceeds 95 parts by weight, the mechanical strength and heat resistance will decrease, and the absolute value of impedance will become high, making it unsuitable for use as a polymer thermosensitive material. The copolymerization method may be either condensation polymerization or ring-opening polymerization. In addition, in order to adjust the molecular weight of the copolymer, a diamine compound or a dicarboxylic acid compound can be added in consideration of the number of moles of hydrogenated polybutadiene. The polymer thermosensor of the present invention has small fluctuations in temperature control due to the influence of water absorption, and unlike conventional polymer thermosensors, hygroscopic properties are not controlled by additives, so there is no possibility of bleed polarization. It is stable over a long period of time. In addition, it is more flexible than conventional polymer thermosensitive materials, and when used in electric blankets, etc., a blanket that has excellent flexibility and feels good on the skin can be obtained. Furthermore, the polymer thermosensitive material of the present invention has a clear melting point between 150°C and 180°C, although it differs depending on the copolymerization ratio, and its melting behavior is also sharp.
When used as a heater wire, it functions as a temperature fuse. Of course, it is also possible to add stabilizers and electrical modifiers to the polymer thermosensitive material of the present invention. This will be explained below using examples and comparative examples. Example 1 76.40 g of 12-aminododecanoic acid, 1.57 g of hexamethylene diamine, hydrogenated polybutadiene with carboxylic acid at both ends (1.2 98% hydrogenation of polybutadiene with 80% or more vinyl bonds, terminal carboxylic acid concentration
0.935 meq/g) was placed in a flask and heated at 250° C. for 3 hours while flowing nitrogen to obtain a homogeneous translucent copolymer. The obtained polymer was press molded into a flat plate about 1 mm thick, and after vacuum drying at 60°C for 24 hours and standing in water at 40°C for 5 days, the specific volume impedance of each plate at 100Hz was measured. Comparative Example 1 The electrical properties of Nylon 12 were measured in the same manner as in Example 1. The results are shown in Table-1. Example 2 54.57 g of 12-aminododecanoic acid, 2.61 g of hexamethylene diamine, and 48.20 g of the hydrogenated polybutadiene used in Example 1 were placed in a flask and polymerized in the same manner as in Example 2, resulting in the same electrical properties as in Example 1. The results of the measurements are shown in Table 1.

【table】

【table】 [Brief explanation of the drawing]

FIG. 1A is a partially cutaway perspective view showing an example of a heat-sensitive temperature control line, and FIG. 1B is a sectional view showing an example of a heat-sensitive temperature control line. 1... Insulating material, 2... Core wire, 3... Polymer temperature sensitive body, 4... Signal line, 5... Heater wire.

Claims (1)

[Scope of Claims] 1 99 to 5 parts by weight of a polyamide polymer component having one or more repeating units represented by the following general formula (1) or (2), and both terminals are carboxylic acid groups or amino groups. 1. A polymer thermosensitive material comprising a copolymerized polyamide resin obtained by copolymerizing 1 to 95 parts by weight of a polybutadiene component whose double bonds with an average molecular weight of 500 to 10,000 are hydrogenated by 70% or more. (1) -NH( _CH2 ) _o CO- (in the formula, n is an integer from 5 to 11) (2) -NHXNHCOYCO- [in the formula, X is C _n H _2n (m is an integer from 6 to 12), It represents an isophorone group, a phenylene group, or a cyclohexylene group, and Y represents ClH ₂ l (l is an integer of 4 to 10), a phenylene group, or a cyclohexylene group. ]