KR102198815B1 - Leakage detection sensor - Google Patents

Abstract

The present invention relates to a leakage detection sensor, and more particularly, to a leakage detection sensor for preventing damage to a metallic electrode formed on the upper surface of a film to detect a leakage state by a chemical solution.
To this end, the present invention includes a lower film in which at least one pair of metallic electrodes are formed side by side at intervals to detect leakage on an upper surface; An electrode composition layer applied to cover each of the electrodes; and the electrode composition layer is graphene 5 to 10 wt%, binder 30 to 50 wt%, 2-ethoxyethanol 20 to 25 wt%, DPGDME After mixing 20 to 25% by weight and 5 to 10% by weight of a dispersant, it is formed by coating the electrode with a coating solution prepared by high-pressure dispersion.

Description

Leakage detection sensor

The present invention relates to a leakage detection sensor, and more particularly, to a leakage detection sensor for preventing damage to a metallic electrode formed on the upper surface of a film to detect a leakage state by a chemical solution.

The leak detection sensor of Registration Patent No. 10-1571398 (leak detection device) registered by the present applicant has a structure that detects various leaking water, conductive and non-conductive chemical solutions, oil and organic solvents, and its structure is "corrosion resistance. And a base film made of a material having excellent chemical resistance; conductive lines formed side by side in a pair at intervals from each other on the upper surface of the base film by a metal material having conductivity.

Accordingly, when a leaked liquid flows between adjacent conductive lines, water, conductive and non-conductive chemical solutions, and oil and organic solvents can be discriminated by a change in the capacitance value.

Of course, it is also applied to a sensing device that detects a leaked state due to a change in electrical conductivity and a change in resistance value due to leakage, not capacitance value.

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However, according to the prior art, the conductive line is formed of a conductive metal material such as copper, nickel, gold, etc., so that the conductivity is very good, but when a chemical solution such as an alkali solution or an acid solution comes into contact, it is easily corroded and used repeatedly. The number of times is limited, and there is a problem in that a detection signal error occurs frequently due to corrosion.

Of course, in the case of forming a conductive line made of carbon material, it is relatively stronger to chemical solutions than metal material, but this is because the size of the resistance value per unit area does not appear evenly, so after installing the sensor, it is necessary to reset the basic resistance value in the controller every time. There is discomfort.

In addition, when the conductive line made of carbon material has a very large resistance value and the sensor area is wide or the length of the sensor is installed as long as several meters to several tens of meters, the detection performance is very deteriorated due to the high resistance value.

<Prior technical literature>

1. Registered Patent No. 10-1571398

(Leakage detection device)

In order to solve such a conventional problem, the present invention prevents direct contact between the chemical substance and the electrode by coating a metallic conductive line, that is, an electrode with graphene ink, thereby protecting the electrode from damage and maintaining a high conductivity. Its purpose is to provide a leak detection sensor.

The leak detection sensor of the present invention for achieving the above object,

A lower film in which at least one pair of metallic electrodes are formed side by side at intervals to detect leakage on the upper surface;

Consisting of; an electrode composition layer applied to cover each of the electrodes,

The electrode composition layer is high pressure after mixing 5 to 10% by weight of graphene, 30 to 50% by weight of binder, 20 to 25% by weight of 2-ethoxyethanol, 20 to 25% by weight of DPGDME, and 5 to 10% by weight of dispersant It is characterized in that it is formed by coating the electrode with a coating solution prepared by dispersion.

The leak detection sensor according to the present invention protects the leaked chemical solution from direct contact with the metallic electrode by coating the electrode with a composition for an electrode including graphene, thereby preventing damage to the electrode while maintaining high conductivity. .

For this reason, the leak detection sensor of the present invention can be used several times or semi-permanently, and since corrosion of the electrode does not occur, there is an advantage in that an error in the detection signal does not occur.

1 is a diagram showing the structure of a leak detection sensor according to the present invention.
FIG. 2 is a view showing a cross section of FIG. 1 and a state for detecting a leak state.
3 is a diagram showing another form of an electrode.
Figure 4 is a diagram showing the reduced graphene oxide that is positively charged and coated on the surface of the sensing line.
Figure 5 is a diagram showing the negatively charged reduced graphene oxide.
6 is a diagram showing the initial charge distribution of a general sensor.
7 is a diagram showing an initial charge distribution of an electrode including charged and reduced graphene oxide applied to the present invention.
8 is a diagram showing a charge distribution when a general sensor contacts harmful substances.
9 is a view showing a charge distribution when a sensing line including charged and reduced graphene oxide contacts a harmful substance according to another embodiment of the present invention.

The above-described objects, features, and advantages will be described later in detail with reference to the accompanying drawings, and accordingly, one of ordinary skill in the art to which the present invention pertains will be able to easily implement the technical idea of the present invention.

In describing the present invention, if it is determined that a detailed description of known technologies related to the present invention may unnecessarily obscure the subject matter of the present invention, a detailed description will be omitted.

The terms used in the present invention have been selected from general terms that are currently widely used while considering functions in the present invention, but this may vary depending on the intention or precedent of a technician working in the field, the emergence of new technologies, and the like.

In addition, in certain cases, there are terms arbitrarily selected by the applicant, and in this case, the meaning of the terms will be described in detail in the description of the corresponding invention.

Therefore, the terms used in the present invention should be defined based on the meaning of the term and the overall contents of the present invention, not a simple name of the term.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

However, the embodiments of the present invention exemplified below may be modified in various forms, and the scope of the present invention is not limited to the embodiments described below.

The embodiments of the present invention are provided to more completely describe the present invention to those of ordinary skill in the art.

FIG. 1 is a diagram showing the structure of a leak detection sensor according to the present invention, and FIG. 2 is a diagram showing a cross section of FIG. 1 and a state for detecting a leak state.

The lower film 100 is a film made of a material such as PI, Teflon having excellent acid resistance and chemical resistance, and a pair of electrodes 110 and 120 long in the longitudinal direction are formed side by side while maintaining a distance from each other on the upper surface. ) May be formed by plating or sputtering with a conductive material such as copper, nickel, silver, or gold.

The electrodes 110 and 120 have high conductivity, have a width of 2 to 3 cm, and have a length of several cm to tens of meters depending on the length of the lower film 100.

These electrodes 110 and 120 consist of three layers, and the lowermost first layer may be formed by an etching method, and the electrodes 110 and 120 are formed in a state in which a copper foil layer is formed on the entire upper surface of the lower film 100. The first layer of copper is formed by masking only the part to be formed and corrosion of the remaining copper foil parts.

It is preferable that this first layer has a thickness of about 13 to 20 μm.

That is, if it is too thick, peeling can easily occur from the lower film 100, and if it is too thin, the second layer cannot be easily attached. Therefore, having a thickness of 13 to 20 μm has the best results experimentally.

In addition, the reason why the first layer is formed of a copper layer is that the third layer, which is the uppermost layer, is not directly attached to the lower film 100 by plating, so that the first layer is first formed of a copper layer.

On the upper side of the first layer, a second layer is laminated by a plating method, and the second layer is a nickel layer having a thickness of about 1 to 15 μm, which is a silver or gold layer forming the third layer. Since the first layer, the copper layer, is not immediately adhered to the upper surface of the copper layer by plating, the first layer, the copper layer, and the second layer, the nickel layer, which are well adhered by plating, are formed first.

Thereafter, a third layer of silver or gold is laminated by plating to a thickness of 0.03 to 0.07 μm. This third layer is not directly attached to the copper layer, which is the first layer, by plating, but is plated on the nickel layer, which is the second layer. It adheres well and is stacked.

After all, in order to form the electrodes 110 and 120 on the upper surface of the lower film 100 by plating a third layer of silver or gold having excellent conductivity, the first layer and the second layer are sequentially stacked first and then the uppermost layer. It is formed by laminating a third layer of silver or gold by plating.

Of course, a metal layer having a high conductivity, such as copper, nickel, silver, gold, etc., may be directly formed as the electrodes 110 and 120 by plating or sputtering.

On the electrodes 110 and 120, as shown in Fig. 2, the electrode composition layers 111 and 121 are each printed with a thickness of 1 to 2 µm by a printing method. As shown in Fig. 2, there is a leakage between the electrodes 110 and 120. Even if a leak (L) such as water, chemical solution, oil, organic solvent, etc. is located, the electrode (110, 120) is prevented from being oxidized or damaged by preventing the leak (L) and the electrode (110, 120) from directly contacting. To protect.

These electrode composition layers 111 and 121 have higher resistance than the metal electrodes 110 and 120, but are printed with a very thin thickness on the electrodes 110 and 120, so that the resistance is very low.

That is, since there is a gap equal to the thickness of the electrode composition layers 111 and 121 between the leakage liquid L and the electrodes 110 and 120, the resistance of the electrode composition layers 111 and 121 is almost negligible.

Therefore, in the case of detecting the leakage (L) of acid, alkali, oil, organic solvent, etc. leaked by the capacitive method, the electrodes 110 and 120 are protected from the chemical solution, and water and acid between the two electrodes 110 and 120 , In the case of detecting a leakage state by a change in electrical conductivity or a change in resistance value caused by leakage (L) of a conductive liquid such as alkali, the electrode composition layers 111 and 121 are applied to the electrodes 110 and 120 It is possible to determine the leaked state and the type of the leaked fluid by conduction of the leaked fluid L by the change in its electrical conductivity or resistance value.

The electrode composition layers 111 and 121 are prepared in a form that can be coated by graphene having conductivity, and then applied to the electrodes 110 and 120, and the composition for electrodes is 5 to 10% by weight of graphene and 30 to the binder. 50% by weight, 2-Ethoxyethanol (2-Ethoxyethanol) 20 to 25% by weight, DPGDME (Diropylene Glycol Dimethylether) 20 to 25% by weight, and dispersant 5 to 10% by weight are mixed and stirred with a mixer and then subjected to high pressure dispersion. It is manufactured in the form of a coating solution.

Here, a fluororesin having acid resistance and chemical resistance is used as the binder, 2-ethoxyethanol is mixed as a solvent, and DPGDME is mixed as a retarding solvent.

When such a mixture is dispersed under high pressure, the viscosity of the graphene coating solution increases due to rapid volatilization while heat is generated. At this time, the viscosity must be maintained by delaying volatilization.

Therefore, by delaying volatilization by DPGDME, the coating solution has a uniform viscosity even after high-pressure dispersion.

In addition, after high-pressure dispersion for rapid curing of the fluororesin, 17 to 23% by weight of the fluororesin, that is, 5.1 to 11.5% by weight of the total coating solution, may be additionally added.

The thus prepared coating solution is coated so as to completely cover each electrode 110 and 120 so as not to be exposed to the outside, and the graphene ink layers 111 and 121 are not connected to each other.

Silver ink may be mixed to increase the conductivity of the electrode composition layers 111 and 121, and 40 to 60% by weight of silver ink may be mixed with 40 to 60% by weight of the coating solution. Based on 40-60% by weight, 15-25% by weight of silver powder, 40-60% by weight of a binder, and 20-30% by weight of DPGDME are configured to be mixed.

Meanwhile, as shown in FIG. 3, in order to increase the detection performance while using the leakage detection sensor according to the present invention as a sensor that detects leakage according to a change in capacitance value, a capacitance pattern 130 is formed. A pair of electrodes 110 and 120 are formed long in the longitudinal direction of the lower film 100 while maintaining a distance from each other, and a capacitance pattern for sensing capacitance at predetermined intervals on the electrodes 110 and 120 130 is formed.

The capacitive pattern 130 is arranged so that a plurality of stem lines 131 and 132 are branched in a direction in which the pair of lower electrodes 110 and 120 face each other and alternately

The stem lines 131 and 132 are formed to extend toward conductive lines facing each other in a rounded shape, and have a structure that alternates with each other, thereby acting as a similar capacitor.

Accordingly, it is possible to form an accurate capacitance value.

The leak detection sensor of the present invention described above has been described as an example of a long shape, but may have a structure that is formed in an area-type pad shape and installed in a point shape in a specific area where leakage is expected.

Meanwhile, as another form of the present invention, the surface of the electrodes 110 and 120 is coated with an electrode composition containing graphene oxide to be used as an electrode while having chemical resistance, chemical resistance, chemical resistance and chemical resistance. The electrode 110 of is coated with an electrode composition containing positively charged reduced graphene oxide to form an electrode, and another electrode 120 is an electrode containing negatively charged reduced graphene oxide The electrode is formed by the solvent composition.

In the present invention, graphene is used as an electrode composition, and graphene is a two-dimensional carbon sheet made of carbon atoms and exhibits a wide specific surface area, excellent thermal conductivity, and fast electron transfer characteristics compared to conventional nanomaterials. .

Graphene can be obtained by physically separating graphite layer by layer, but this method is not suitable for mass production, and large-area graphene production is impossible. Another method is a chemical exfoliation method of graphite, that is, a manufacturing process through an oxidation process.This method is inexpensive to manufacture, enables mass production, and enables functionalization of the generated graphene, allowing various applications. You can get a pin.

In the case of graphene oxide, it may have a smaller number of layers than in the case of graphene by a physical method.

Various functional groups such as an epoxy group, a hydroxy group, a carbonyl group, or a carboxy group exist on the surface of graphene oxide obtained through the oxidation process.

In order to use such graphene oxide as a component of an electrode, in the present invention, graphene oxide is reduced and used as reduced graphene oxide (rGO).

In particular, in the present invention, when the reduced graphene oxide is manufactured, the sensitivity of the sensor can be greatly improved, particularly when used as a capacitive sensor, by using a reduced graphene oxide having a polarity by giving a polarity.

The leakage detection sensor according to the present invention comprises: coating a composition for an electrode including positively charged reduced graphene oxide on the electrode 110; Coating an electrode composition including negatively charged reduced graphene oxide on the electrode 120; And curing step; may be prepared including.

FIG. 4 is a diagram showing a positively charged reduced graphene oxide, and FIG. 5 is a diagram showing a negatively charged reduced graphene oxide, in which the composition for an electrode according to the present invention is charged and reduced oxide graphene. Pins are used for electrodes.

Reduced graphene, which can be obtained by reducing graphene oxide, can be used as an electrode because it exhibits conductivity unlike insulating graphene oxide.

In the present invention, among the reduced graphene oxide, positively charged reduced graphene oxide or negatively charged reduced graphene oxide is used.

The positively charged reduced graphene oxide may be, for example, a surface charge represented by NH ₃ ⁺ functional groups (Fig. 4), and the negatively charged reduced graphene oxide has a surface charge of COO ^- functional group. It may appear (Fig. 5).

NH ₃ ⁺ group or ^{COO-oxidation} of the reduced graphene having a functional group is the functional group NH ₃ ⁺ or COO at reduced graphene oxide ^- while remaining the functional group can be obtained by reducing the graphene oxide.

In the case of charging the reduced graphene oxide, there is an effect on the value of the change in capacitance related to the sensitivity of the sensor.

6 is a diagram showing the initial charge distribution of a general sensor, FIG. 7 is a diagram showing the initial charge distribution of a sensing line including charged and reduced graphene oxide applied to the present invention, and FIG. 8 is a diagram showing the harmfulness of a general sensor. It is a diagram showing the charge distribution when a substance is in contact.

And, FIG. 9 is a diagram showing a charge distribution when a sensing line including charged and reduced graphene oxide contacts a harmful substance according to another embodiment of the present invention.

Referring to FIG. 6, when a conventional electrode does not contain a material having a polarity, charges are distributed to the + electrode and the-electrode, so that an initial charge amount value can be obtained.

In FIG. 7, when the electrode is coated with charged and reduced graphene oxide, that is, any one electrode (upper electrode or lower electrode) used as the + electrode is coated with positively charged reduced graphene oxide, and the-electrode Another electrode (lower electrode or upper electrode) used as a voltage is applied when negatively charged reduced graphene oxide is coated.

When the positively charged reduced graphene oxide is coated on the + electrode, the -charges induced by the application of voltage are canceled by the positively charged reduced graphene oxide, so that the initial charge value is lowered.

8 and 9, when the electrode of the conventional sensor does not contain polarity and when the electrode is coated with charged and reduced graphene oxide, when exposed to harmful substances, the electric charge value depends on the harmful substances. Since the value of the amount of charge by the substance is the same, the current value of the amount of charge becomes similar.

Since the capacitance depends on the amount of charge, the amount of change in the capacitance depends on the difference between the current amount of charge and the initial amount of charge, so if the initial charge value decreases, the range of change in the capacitance value widens when the current charge value is the same. The resolution and sensitivity of the sensor are improved.

That is, when charged and reduced graphene oxide is added to the electrode composition as in the present invention, the amount of charge is affected, so that the sensitivity of the sensor acting as the capacitance type of the present invention can be improved.

The composition for an applied capacitive hazardous substance electrode according to the present invention includes charged and reduced graphene oxide, a binder, a solvent and a curing agent.

In addition, the composition for a capacitive toxic substance electrode according to the present invention may further include a dispersant and a volatilization delay agent for increasing the dispersibility of the charged and reduced graphene oxide.

Binders that can be used in the composition for a capacitive hazardous material electrode of the present invention include ethylcellulose, polyvinylalcohol, polyvinylpyrrolidone, polyvinylbutyral, and polymethyl Although methacrylate (poly(methylmetacrylate)), polyurethane (polyurethane) or polyester (polyester) may be used, oil-based fluorine resin is most preferred for high acid resistance.

Solvents that can be used in the composition for the capacitive hazardous substance electrode of the present invention are 2-ethoxyethanol, ethanol, methanol, toluene, xylene, or methyl ethyl. Ketones (methyl ethyl ketone) can be used.

As a dispersant that can be used in the composition for a capacitive hazardous substance electrode applied to the present invention, Solspers 20000, Solspers 38500, BYK 170, and the like may be used.

Volatilization retarding agents that can be used in the composition for a capacitive hazardous material electrode of the present invention may be butyl carbitol acetate, dipropylene glycol dimethyl ether, or the like.

The curing agents that can be used in the composition for the capacitive hazardous substance electrode of the present invention include benzoyl peroxide, azobisisobutyronitrile, and 2-cyano-2-propyl azoformide (2- CYANO-2-PROPYLAZOFORMAMIDE), 2, 2-azobis (2,4-dimethylvaleronitrile) (2, 2-AZOBIS (2, 4-DIMETHYLVALERONITRILE), 2,2-azobis (2- (2- already Dazolin-2-yl)propane](2, 2-AZOBIS[2-(2-IMIDAZOLIN-2-YL)PROPANE]), 2,2-azobis(2-methylbutyronitrile)(2,2- AZOBIS (2-METHYLBUTYRONITRILE) can be used in any one, 2, 2-azobis (2,4-dimethylvaleronitrile) (2, 2-AZOBIS (2, 4-DIMETHYLVALERONITRILE) is most preferred.

The composition for a capacitive hazardous substance electrode applied in the present invention comprises: mixing charged and reduced graphene oxide, a binder, a solvent, a dispersant, and a volatilization retardant; A dispersion step of first dispersing the mixture by stirring it with a homomixer, and second dispersing the first dispersed mixture with a high pressure disperser; Injecting a curing agent into the dispersed mixture; can be prepared by performing.

It is preferable that the curing temperature is pre-cured at 100°C and then cured at 180°C.

The first dispersing step is a step of mixing charged and reduced graphene oxide and an oil-based fluorine resin in a solvent to maximize the capacitance reaction width, and is preferably performed at 5,000 to 7,000 rpm for 1 to 2 hours.

The step of secondary dispersing the first mixture using a high-pressure disperser increases the coating properties and dispersibility of the composition for capacitive hazardous substance sensor electrodes by crushing and dispersing the mixture under high pressure.

The secondary dispersion may preferably be carried out 5 to 10 times under a pressure of 300 to 350 bar.

A curing agent is added to the dispersed mixture, and agitation is performed for 10 to 30 minutes at 3,000 to 5,000 rpm using a homomixer.

Based on the total weight of the electrostatic capacitive electrode composition, the charged and reduced graphene oxide is 5 to 20 wt%, the binder is 30 to 60 wt%, the solvent is 30 to 50 wt%, the curing agent is 20 to 60 wt%, and the dispersant is It may be included in 5 to 20wt%.

As described above, specific parts of the present invention have been described in detail, and for those of ordinary skill in the art, it is obvious that these specific techniques are only preferred embodiments, and the scope of the present invention is not limited thereby. something to do.

Accordingly, it will be said that the substantial scope of the present invention is defined by the appended claims and their equivalents.

100: lower film
110,120: electrode
111,121: electrode composition layer
130: capacitance pattern
131,132: stem line
L: leakage

Claims (6)

A lower film in which at least one pair of metallic electrodes are formed side by side at intervals to detect leakage on the upper surface;
Consisting of; an electrode composition layer applied to cover each of the electrodes,
Consisting of coating a composition for an electrode comprising positively charged reduced graphene oxide on the surface of the one metallic electrode,
A leak detection sensor, characterized in that the surface of the another metallic electrode is coated with a composition for an electrode comprising negatively charged reduced graphene oxide.
delete delete delete The method of claim 1, wherein the positively charged reduced graphene oxide has a surface charge of NH ₃ ⁺ functional groups, and the negatively charged reduced graphene oxide has a surface charge of COO ^- functional groups. Leak detection sensor.
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