JPH02132357A - Oil leak sensing element - Google Patents

Abstract

PURPOSE:To sense disconnection resulting from oil leak by providing a distributing layer made of carbon or graphite on the layer swelled by oil. CONSTITUTION:The sensing element is formed by providing both a coated layer 2 made of high polymer material swelled by oil and a distributing layer 4 made of conductive carbon or graphite on a core material 1 made of material unswelled by oil and desirably providing a protective layer 3 made of material uninterrupting permeation of oil on the layer 4. As the core material 1, a ceramic plate, etc., can be utilized. The layer 2 can be formed by thermally melt-sticking a sheet of an ethylene-vinyl acetate copolymer on the core material 1. The layer 4 can be formed by coating the layer 2 with the cluster ions of aromatic acid anhydride via a mask. The same material as the material of the layer 2 can be utilized for the layer 3.

Description

[Detailed description of the invention] 11 steps and more! The present invention relates to a sensing element for detecting oil leaks from oil tanks, fuel tanks, etc., and more specifically, to an oil leak sensing element with excellent corrosion resistance and having a wiring layer made of a continuous thin film of conductive carbon or graphite. Regarding sensing elements.

Traditionally, oil leak sensing elements have been made by coating a metal conductor with a material that dissolves in oil, and when the coating melts in the oil, shijitsu occurs between the conductors, thereby detecting oil leaks. Many methods are known.

However, in areas where oil leaks occur, chemicals other than oil may also leak out, resulting in corrosion of metal conductors.

Although there is a desire for an oil leak sensing element that can reliably detect oil leaks and has excellent durability and corrosion resistance, conventional products are still insufficient.

An object of the present invention is to provide an oil leak sensing element that has excellent corrosion resistance and is less likely to be damaged.

As a result of intensive research to solve the problems of the prior art, the present inventor made a core material (substrate) from a material that does not swell with oil, and coated the surface of the core material with a polymeric material that swells with oil. If a continuous thin film made of conductive carbon or graphite is applied to the outer surface of the coating layer and wiring is applied, the coating layer will swell with oil and the wiring will be cut. It was discovered that if connected, it could be used as an oil leak sensing element. Furthermore, by providing an oil-permeable protective layer on the wiring layer made of conductive carbon or graphite, it is possible to protect the wiring layer from physical damage without impairing its function as a sensing element, increasing durability and reliability. I discovered that it is possible to secure sex.

The present invention has been completed based on these findings.

2. That is, according to the present invention, a core material (A) made of a material that does not substantially swell with oil, and a coating made of a polymeric material that swells with oil provided on the core material (A). layer (B), a wiring layer (C) consisting of a continuous thin film of conductive carbon or graphite provided on the outer surface of the coating layer (B), and optionally provided on the wiring from a material that does not impede the permeation of oil. An oil leak sensing element constituted by the protective layer (D) is provided.

When the sensing element of the present invention comes into contact with oil, the coating layer (B) swells and the area of the outer surface increases, so that the wiring layer applied to the outer surface is cut. By monitoring the electrical current flowing through this wiring layer, oil leaks can be detected.

Hereinafter, the constituent elements of the present invention will be explained.

(Core material) In the present invention, the core material (A) is made of a material that does not substantially swell with oil.

The material that does not substantially swell with oil is not particularly limited, and includes, for example, various metals, non-metals such as ceramics and glass, and polymeric materials that do not swell with oil.

Examples of polymeric materials that can be detected include not only polymers that hardly swell with oil, such as polytetrafluoroethylene, but also polymers that swell to a negligible degree depending on polar solvents, such as polyethylene. Can be used depending on the type of oil. Further, highly crosslinked thermosetting resins such as epoxy resins and unsaturated polyester resins can also be used depending on the purpose.

When external force is applied to the core material, the wiring layer (
C) serves to prevent it from breaking.

(Coating layer made of polymeric material) In the present invention, a coating layer (B) made of a polymeric material that swells with oil is provided on the core material (A).

The polymer material to be coated on the surface of the core material is a polymer that swells with oil or organic solvent, such as ethylene-based copolymer such as ethylene-vinyl acetate copolymer or ethylene-ethyl acrylate copolymer. Polymers, various elastomers, etc. can be suitably used. The polymer material may be any material as long as it swells with oil, and it does not matter whether it is crosslinked or non-crosslinked.

The method of providing the covering layer (B) on the core material (A) is as follows:
A method of heat-sealing (hot press method) or bonding a polymeric material formed in advance into a sheet onto the surface of the core material using an adhesive, or a method of applying an organic solvent solution of the polymeric material onto the core material and then drying it. When the core material is a polymer, there are various methods such as a method of laminating the core material and a coating polymer by co-extrusion.

The thickness of the coating layer can be determined as appropriate depending on the shape and size of the sensing element, but it is usually preferably about 0.5 mm to several mm in order to break the wiring due to swelling.

(Wiring) In the present invention, a wiring layer (C) made of a continuous thin film of conductive carbon or graphite is provided on the outer surface of the coating layer CB).

Conductive carbon and graphite are materials that do not corrode easily, have conductivity, and can form continuous wiring layers. Furthermore, since conductive carbon and graphite are materials that can be formed into thin films and have little elongation, the wiring can be cut due to swelling of the coating layer.

As a method for forming such a thin film of conductive carbon or graphite, for example, a method of forming a thin film of 1 to several tens of μm using benzene or aromatic acid anhydride as a raw material using an ion beam is preferable. (Refer to the 25th Summer Seminar Report on Carbon Materials).

Furthermore, specifically, as a method of providing the wiring layer (C) on the surface of the coating layer (B) using a continuous thin film of conductive carbon or graphite, for example, an aromatic acid such as berylenetetracarboxylic dianhydride may be used. There is a method such as the cluster ion beam method, which uses an anhydride as a raw material, heats it to evaporate it, ionizes the clusters to create cluster ions, and deposits the cluster ions. The shape of the circuit can be determined by a mask placed on the covering layer (B) (
IEICE Technical Report 87.29 (1987)
.

The shape of the wiring layer is not particularly limited as long as it is a continuous thin film and can conduct electricity.

(Protective layer) In the present invention, it is desirable to further provide the wiring layer (C) with a protective layer (I) made of a material that does not prevent oil from permeating.

As the protective layer for the wiring layer, any material may be used as long as it does not prevent oil from entering and can protect the wiring layer from damage, and it can be used regardless of whether it is a metal, an inorganic material, or an organic material. The shape of the protective layer can be selected as desired, such as a uniform film in the case of a material that is permeable to oil, or a porous or meshed material in the case of a metal or an organic material that is impermeable to oil. is possible. Further, it may be formed of the same material as the covering layer (B).

The protective layer (D) may have a shape that protects only the wiring layer portion, or may be formed to cover the entire surface of the coating layer including the wiring layer.

The protective layer (D) can be applied by any method such as heat fusion or using an adhesive.

Note that instead of the protective layer, the oil leak sensing element may be placed in a perforated container, for example.

(The following is a blank space) By Ichikawa The oil leak sensing element of the present invention is such that when oil enters the location where the sensing element is placed due to oil leakage, etc., the oil applied to the outer surface layer of the core material (A) The swelling coating layer (B) swells and its volume increases. If the interface between the core material and the covering layer is laminated by heat fusion or adhesive, the area of the outer surface of the covering layer will increase in particular.

In this case, the wiring layer (C) applied to the outer surface of the covering layer is a thin film of carbon or graphite with little elongation, so that cutting occurs. Therefore, by monitoring the power supply to this wiring layer, it is possible to detect a disconnection in the wiring layer due to oil leakage, and it is possible to detect that oil leakage has occurred.

Hereinafter, the present invention will be specifically explained with reference to Examples, but the present invention is not limited to these Examples.

[Example 1] 1cmx3cmXO. A 5 cm ceramic plate was used as the core material, and ethylene-vinyl acetate copolymer (vinyl acetate content: 25% by weight) was applied to a thickness of 1 mm using a hot press method.
The outer surface is coated with conductive carbon to a thickness of 1 μm.
A wiring circuit with a width of 2 mm was written by the cluster ion beam method, and to protect the wiring layer, a protective layer with a thickness of 0.2 mm was coated with the same resin as the coating layer by hot pressing to obtain an oil leak sensing element. .

FIG. 1 is a schematic diagram of this oil leak sensing element, which has a structure in which a coating layer 2 that swells with oil is provided on a core material 1, a wiring layer 4 is provided on the outer surface of the coating layer 2, and a protective layer 4 is further provided on the outer surface of the coating layer 2. It becomes.

When this sensing element was immersed in xylene at room temperature while electricity was being applied between both ends, the wire was disconnected after 1 hour.

The oil leak sensing element of the present invention has excellent corrosion resistance and breakage resistance, and can detect oil leaks, so it can be used to detect raw oil spill accidents in crude oil tanks, chemical plants, etc. can do.

[Brief explanation of the drawing]

1. Core material 2 made of a material that does not substantially swell with oil: Covering layer 3 made of a polymeric material that swells with oil: Protective layer 4 for wiring: Made of a continuous thin film of conductive carbon or conductive graphite. wiring layer

Claims (1)

[Claims] (1) Core material made of material that does not substantially swell with oil (
A), a coating layer (B) made of a polymer material that swells with oil, provided on the core material (A), and a continuous thin film of conductive carbon or graphite provided on the outer surface of the coating layer (B). An oil leak sensing element composed of a wiring layer (C) and a protective layer (D) made of a material that does not prevent oil from permeating, which is optionally provided on the wiring.