JPH03266322A - Moisture-sensitive switch - Google Patents

Abstract

PURPOSE:To provide a switch having moisture-sensing function and capable of being miniaturized and reduced in weight by forming a rubber contact in which conductive particles are dispersed on a rubber plate in which water- absorptive polymer particles are dispersed. CONSTITUTION:A water-absorptive rubber plate 3 is fixed and mounted on a conductive substrate 1 via insulating spacers 2, 2'. The upper part of a conductive rubber contact 4 which touches the substrate 1 at its lower surface is inset in the hole pierced in the plate 3. The contact 4 is composed of a rubber plate in which water-absorptive polymer particles are dispersed and conductive particles which are dispersed in the rubber plate. When the rubber plate 3 absorbs water and is swollen, it bends upward so that the contact part 4 is separated from the substrate 1 and ON state is changed into OFF.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to moisture sensitive switches. More specifically, the present invention relates to a moisture sensitive switch whose electrical contacts open and close due to water absorption.

[Prior art] and [Problem to be solved by the invention]
BACKGROUND ART Malfunctions, damage, and electric shocks of electrical products and equipment due to water leakage and condensation have long been a problem. In order to avoid such a situation, a combination of a dew condensation sensor or the like and a relay is used, but such a combination cannot be made smaller and lighter.

An object of the present invention is to provide a moisture-sensitive switch that has a sensor function and a switch function for moisture, and can be made smaller and lighter.

[Means to solve the problem]

This object of the present invention is achieved by a moisture-sensitive switch in which a rubber plate-like member in which water-absorbing polymer particles are dispersed is attached with a rubber contact in which conductive particles are dispersed.

The main body of this moisture-sensitive switch is composed of a rubber plate-like body in which water-absorbing polymer particles are dispersed.

Examples of water-absorbing polymer particles include water-absorbing polymers that are insoluble in water and have a particle size of about 1 to 100 μm and have a water retention capacity of about 50 times or more than its own weight, such as starch-sodium acrylate graft copolymer, isobutylene-maleic anhydride. Salt copolymer, styrene-maleic anhydride copolymer, sodium polyacrylate crosslinked product, polyvinyl alcohol-acrylate graft copolymer, vinyl ester-unsaturated carboxylic acid copolymer, vinyl ester-unsaturated carboxylic acid copolymer Saponified acid ester copolymers and the like are used.

These water-absorbing polymer particles are natural rubber, polybutadiene rubber, styrene-butadiene rubber, chloroprene rubber, nitrile rubber, ethylene-propylene (-diene) copolymer rubber, and butyl rubber.

It is used by adding about 1 to 100 parts by weight, preferably about 20 to 50 parts by weight, to 100 parts by weight of synthetic rubber such as isoprene rubber, acrylic rubber, hydrin rubber, fluororubber, silicone rubber, urethane rubber, polysulfide rubber, etc. It will be done.

After adding a vulcanizing agent and other rubber compounding agents depending on the type of rubber used, these are kneaded using a mixing roll, panburi mixer, various kneaders, etc., and then processed by pressure molding, injection molding, etc. It is vulcanized and molded into a plate-shaped body using a molding method.

The shape of the plate-shaped body is related to the manner in which the rubber contacts in which conductive particles are dispersed are attached, but it is generally an elongated shape, and may be disc-shaped in some cases. Its thickness is several mm to maximize the swelling speed due to water absorption.
It is preferable that it is below.

Further, the contact portion of the moisture-sensitive switch is constituted by a rubber contact in which conductive particles are dispersed.

As the conductive particles, carbon black, graphite, carbon fiber, metal-plated synthetic fiber or glass fiber, metal powder such as nickel powder, copper powder, gold powder, aluminum powder, aluminum fiber, nickel fiber, brass fiber, etc. are used. . When these conductive particles are in the form of powder, they have a particle size of several microns or less, and when they are fibrous, they have a length of about several hundred microns or less. These conductive particles are added in an amount of about 10 to 60 parts by weight, preferably about 30 to 50 parts by weight, per 100 parts by weight of the various rubbers mentioned above.

The conductive rubber contacts may be attached to the rubber plate-like body that maintains water absorption properties by vulcanizing and fitting the rubber plate-like body and the rubber contacts separately.

Alternatively, each molding material may be injected and molded at the same time.

1 and 2 of the drawings show an embodiment in which conductive rubber contacts are attached by fitting. In the embodiment of FIG. 1,
A water-absorbing rubber plate-like body 3 is fixedly placed on a conductive substrate 1 via an insulating spacer 2゜2', and the water-absorbing rubber plate-like body 3 is placed in a hole bored in this rubber plate-like body.

The upper part of the conductive rubber contact 4 whose lower surface is in contact with the conductive substrate is fitted (a), and when the water-absorbing rubber plate absorbs water and swells, it curves upward, and the contact portion 4 separates from the conductive substrate 1. At a distance b), the state changes from ON to OFF. In addition, in the embodiment shown in FIG. 2, part of the conductive substrate 1 forms independent conductive terminals 5.5', and correspondingly conductive rubber contacts are arranged at 6 and 6'. As the two points, ON(a)-OFF(b) operation is performed. Incidentally, the shape of the contact point may be an arc like a general contact point.

When using a moisture-sensitive switch consisting of a water-absorbing rubber plate and conductive rubber contacts, it is effective to combine it with a sheet heating element in order to increase the response speed and shorten the time it takes to recover. be. Examples of planar heating elements include a heating element made by molding a conductive polymer into a sheet shape with electrodes attached to it and generating heat when electricity is applied, and a heating element made by embedding nichrome wire in a sheet-shaped conductive polymer. It is installed at the bottom of the location where the moisture-sensitive switch is installed.

〔Effect of the invention〕

In the moisture-sensitive switch comprising a water-absorbing rubber plate and a conductive rubber contact according to the present invention, due to water absorption and swelling of the water-absorbing rubber plate, the contact between the conductive rubber contact and the conductor gradually separates, and Along with this, the resistance value also increases, and finally it turns ON.
It becomes completely separated from the OFF state.

Therefore, based on the function of opening and closing electrical contacts due to water absorption, it can be effectively used in various applications as a switch with a sensor function that prevents electrical equipment from malfunctioning, damage, electric shock, etc. due to water leakage, condensation, etc. I can do it.

〔Example〕

Next, the present invention will be explained with reference to examples.

Example A perforated disc-shaped water-absorbing rubber plate with a diameter of 10 mm and a thickness of 0.5 mm with a hole of 1 mm in diameter in the center was vulcanized and molded (160°C, 10 minutes) from the following compound. )did.

A conductive rubber contact 12 (made of a vulcanized molded product (170° C., 10 minutes) of the following compound (170° C., 10 minutes) was placed in the center perforation of a perforated disc-shaped water-absorbing rubber plate 11 with Lower spherical part maximum diameter 2mm,
0.25 mm in height), and the upper part thereof was coated with sealant (silicone RTV) 13.

Process oil 25
Surfactant (Kao product Emulgen PP150)
10 Sunlight crack prevention agent (Irunai Shinko Chemical Products Sunnock) 1 Sulfur
0.75 zinc oxide
5 stearic acid
1 Anti-foaming agent (Benjo lime product Vesta BS)
6 Vulcanization accelerator (Irunai Shinko Chemical Products) Tsukusera BZ 2
Tsukusera TT O
,5 Tsukuseller TRA
0.5 Tsukusera-M1 As shown in Fig. 3, Ketchen Black formed in this way 3゜Zinc oxide 5Stearic acid 1Sulfur
1.5 Anti-foaming agent (Vesta BS) 6
Vulcanization accelerator Tsukusela BZ 2
Tsukusera TT O,
5Tsukuseller TRA
O,5 Tsukusela-M1 The moisture sensitive switch constructed in this manner is
As shown in the figure, a circular polyester film (thickness 65 μm) 16 is provided with an ITO conductive film 14 on the upper surface side and a planar heating element 15 on the lower surface side, and a circular polyester film spacer (width 2 mm, thickness 0.2mm)
17. Fixed mounting via 17'.

In this state, the ITO conductive film 14, which corresponds to the ground, and the conductive rubber contact 12 are in contact with each other and are in an ON state, and are in an energized state.
When 1 absorbs water and swells when exposed to water or immersed in water, the plate-like body curves upward, the contact between the conductive film and the contact gradually separates, the resistance increases, and finally the plate becomes OFF.

The relationship between the degree of swelling (volume ratio of the swollen part to the initial volume) and resistance when immersed in water is shown in the graph in Figure 4, and the immersion time when immersed in water at 25°C or 50°C. The relationship between and resistance is shown in the graph of FIG.

[Brief explanation of drawings]

1 to 3 are longitudinal cross-sectional views showing one embodiment of the moisture-sensitive switch according to the present invention. Moreover, FIGS. 4 and 5 are graphs showing the relationship between swelling degree or immersion time and resistance, respectively. (Explanation of symbols) 1... Conductive substrate 2.17... Insulating spacer 3.11... Water-absorbing rubber plate-like body 4.6, 1. 2
・・・Conductive rubber contact

Claims (1)

[Claims] 1. A moisture-sensitive switch consisting of a rubber plate-like body in which water-absorbing polymer particles are dispersed and a rubber contact in which conductive particles are dispersed.