JPH0636676A - Element for protection against overcurrent - Google Patents

Abstract

PURPOSE:To provide a stable element for protection against overcurrent, made from a dopant-containing polyaniline and having its resistance value not varied even when left in a high-temperature environment by preheating the element at specific temperatures. CONSTITUTION:All element for protection against overcurrent, made from a dopant-containing conductive polyaniline, is preheated at 100-200 deg.C and is thereby relieved from residual stress and the polyaniline is crosslinked in progress and thereby its molecular chain is held in position, so that changes in the resistance value of the element when the element is left in a high- temperature environment can be reduced significantly. Therefore, the element is stable with its resistance value not varied even when left in a high- temperature environment of about 50 to 150 deg.C.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an overcurrent protection device made of a conductive polyaniline containing a dopant.

[0002]

2. Description of the Related Art An overcurrent protection device made of a conductive polyaniline containing a dopant is known from JP-A-59-134523. However, there is a problem in that the resistance value of the overcurrent protection element made of the dopant-containing conductive polyaniline changes when it is exposed to a high temperature environment of about 50 to 150 ° C.

[0003]

The problem of the present invention is 50-
An object of the present invention is to provide an overcurrent protection element made of a conductive polyaniline containing a dopant, which does not change its resistance value even when exposed to a high temperature environment of about 150 ° C.

[0004]

The present invention is an overcurrent protection device comprising a conductive polyaniline containing a dopant, wherein the overcurrent protection device is preheated at 100 to 200 ° C. It provides an element.

Dopant-Containing Conductive Polyaniline The dopant-containing conductive polyaniline, which is a material of the overcurrent protection device of the present invention, is a polyaniline doped with the following dopants that impart conductivity.

As the dopant, for example, a protic acid is used, and specifically, hydrochloric acid, sulfuric acid, nitric acid, camphor β-sulfonic acid, paratoluenesulfonic acid, methanesulfonic acid, benzenesulfonic acid, and other sulfonic acids, citric acid. And carboxylic acids such as maleic acid, malonic acid and oxalic acid. Among these, preferred is camphor β-sulfonic acid. Polyaniline doped with sulfonic acid has a small change in resistance value over time, and polyaniline doped with camphor β-sulphonic acid has a large increase in resistance value due to heating (see FIG. 1), and can reliably cut off current. it can. The amount of dopant doping is usually
30 to 50 mol% of the aniline unit, preferably 40 to
It is 50 mol%. As a method of doping, for example,
A chemical doping method, an electrochemical doping method, etc. are mentioned.

Manufacture of overcurrent protection device The manufacture of the overcurrent protection device of the present invention is carried out by molding the above-mentioned dopant-containing conductive polyaniline into a molded body having an appropriate shape by, for example, press molding or casting molding. The overcurrent protection element of the present invention is 100 to 200 ° C. during or after the molding, preferably 120 to 180 ° C.
And more preferably, heating at 140 to 180 ° C. If the heating temperature is too high, polyaniline may be thermally decomposed. Examples of the shape of the molded body include a cylindrical shape, a disk shape, and a sheet shape. A typical element has a cylindrical shape and is used by providing electrodes to be described later at the upper and lower circular end portions.

During press molding, for example, the mold used for molding may be heated, and during casting, for example, hot air may be heated. Further, the molded body may be heated after the molding, and further, the electrodes may be heated after the electrodes described below are formed on the molded body. Further, in the case of molding with a molding resin such as an epoxy resin in order to maintain or protect the insulation of the overcurrent protection element, it is possible to combine the heating and curing of the molding resin with the above heating. The heating time is usually 10 minutes to 5 hours, preferably 30 minutes to 3 hours, and more preferably 1 to 3 hours. If the heating time is too long, the resistance value may increase.

The overcurrent protection element of the present invention is usually used, for example, in a state of being sandwiched between two electrodes at the time of use.
As a material for this electrode, a conductive substance capable of obtaining ohmic property is used, and for example, gold is mentioned. Examples of the method for attaching the electrodes include vapor deposition, conductive paste coating, electroless plating, electrolytic plating, and the like.

The element of the present invention does not necessarily need to be provided with the above-mentioned electrodes at the time of manufacture and sale. This is because, for example, as described above, when the device is mechanically clamped and clamped by a predetermined electrode or the like provided in advance in use, it is not necessary to previously provide the electrode on the element.

[0011]

[Function] When the overcurrent protection device made of polyaniline containing dopant is exposed to a high temperature environment of about 50 to 150 ℃, the main cause of its resistance value changing is the residual stress during molding of polyaniline containing dopant. Believed to be due to. According to the present invention, when the overcurrent protection element is preheated, the residual stress is relaxed, and the molecular chain is fixed by pre-crosslinking of polyaniline, so that the change in resistance value when exposed to a high temperature environment is prevented. It is estimated that it can be significantly suppressed.

[0012]

Example 1 In a 200 ml Erlenmeyer flask, 13.3 g of aniline and hydrochloric acid (36%) 1
8 ml and 200 ml of distilled water were added, and while stirring at 0 ° C, 15.3 g of ammonium peroxodisulfate was added to 27 ml of distilled water.
The solution dissolved in was added dropwise over 30 minutes and reacted for 5 hours. The obtained polymer was washed with distilled water and then treated with aqueous ammonia to dedope the hydrochloric acid. After further washing with distilled water, it was immersed in 0.1 M camphor β-sulfonic acid and re-doped to obtain camphor β-sulfonic acid-doped polyaniline. This was separated by filtration, dried, and then press-molded to form a molded body having a diameter of 4 mm and a thickness of 2.5 mm, and the molded body was heated at 150 ° C. for 2 hours. Gold was vacuum-deposited on the heat-treated molded body to form an overcurrent protection element. When the resistance value of the obtained overcurrent protection element was measured, it was 5Ω.
Further, the rate of change of resistance value when the obtained overcurrent protection element was placed in an environment of 80 ° C. was examined. The result is shown in FIG.

Example 2 The same operation as in Example 1 was carried out except that paratoluenesulfonic acid was used as a dopant to obtain an overcurrent protection device. Regarding the obtained overcurrent protection element, the rate of change in resistance value was examined in the same manner as in Example 1. The result is shown in FIG.

Comparative Example 1 An overcurrent protection element was obtained by performing the same operation as in Example 1 except that heating was not performed after forming the molded body. Regarding the obtained overcurrent protection element, the rate of change in resistance value was examined in the same manner as in Example 1. The result is shown in FIG.

Comparative Example 2 An overcurrent protection device was obtained in the same manner as in Example 2 except that the molded body was not heat-treated. Regarding the obtained overcurrent protection element, the rate of change in resistance value was examined in the same manner as in Example 1. The result is shown in FIG.

[0016]

The overcurrent protection device made of the conductive polyaniline containing the dopant of the present invention is stable because its resistance value does not change even when exposed to a high temperature environment of about 50 to 150 ° C.

[Brief description of drawings]

FIG. 1 is a graph showing changes in resistance values of polyaniline doped with camphor β-sulfonic acid and polyaniline doped with benzenesulfonic acid with temperature.

FIG. 2 is a graph showing the rate of change in resistance of the overcurrent protection devices manufactured in Examples 1 and 2 and Comparative Examples 1 and 2.

Claims (1)

[Claims] 1. An overcurrent protection device comprising a conductive polyaniline containing a dopant, wherein the overcurrent protection device is preheated at 100 to 200 ° C.