A COATED NON-CONDUCTIVE SUBSTRATE

Abstract

A non-conductive substrate being at least partially coated with a paint including reduced graphene oxide and a thermosetting polymer, the non-conductive substrate being directly coated by the paint, a method for the manufacture of this coated non-conductive substrate, methods for detecting leaks or strain deformation and the uses of said coated non-conductive substrate.

Claims

1-29. (canceled)

30. A coated non-conductive substrate comprising: a non-conductive substrate being at least partially coated on at least one side with a paint including a reduced graphene oxide having a surface area below 300 m.sup.2.Math.gr.sup.1 and at least one thermosetting polymer, the non-conductive substrate being directly coated by the paint.

31. The coated non-conductive substrate as recited in claim 30 wherein a lateral size of the reduced graphene oxide is between 1 and 80 m.

32. The coated non-conductive substrate as recited in claim 30 wherein a weight percentage of oxygen in the reduced graphene oxide is between 2 and 20%.

33. The coated non-conductive substrate as recited in claim 30 wherein a concentration of the reduced graphene oxide in the paint is between 0.05 and 10% by weight.

34. The coated non-conductive substrate as recited in claim 30 wherein the thermosetting polymer is chosen from at least one of the group consisting of: epoxy resin, Polyester resin, Polyurethanes, Polyurea/polyurethane, Vulcanized rubber, Urea-formaldehyde, Melamine resin, Benzoxazines, Polyimides, Bismaleimides, Cyanate esters, polycyanurates, Furan, Silicone resins, Thiolyte and Vinyl ester resins and a mixture thereof.

35. The coated non-conductive substrate as recited in claim 30 wherein the non-conductive substrate is a textile or a plastic substrate.

36. The coated non-conductive substrate as recited in claim 30 wherein the non-conductive substrate is coated with paint strips to form an alternation between painted non-conductive substrate and non-painted non-conductive substrate.

37. A method for manufacture of the coated non-conductive substrate as recited in claim 30, the method comprising the successive following steps: A. mixing the reduced graphene oxide having a surface area below 300 m.sup.2.Math.gr.sup.1, a thermosetting monomer, a curing agent and optionally a solvent; B. depositing the mixture on the non-conductive substrate; and C. curing the mixture.

38. The method as recited in claim 37 wherein in step A), the solvent is chosen from at least one of the group consisting of: xylene, n-butanol, ethylbenzene, naphtha and a mixture thereof.

39. The method as recited in claim 37 wherein in step A), the curing agent is chosen from at least one of the group consisting of: polyamide, polyamide, phenols, amines and polyaddition isocyanate and a mixture thereof.

40. A method for detecting a leak with the coated non-conductive substrate as recited in claim 30, the method comprising the following successive steps: applying an electric voltage to the coated non-conductive substrate using an electronic system; and detecting a leak when an electrical circuit is formed in the coated non-conductive substrate.

41. The method as recited in claim 40 wherein the electronic system includes a power supply system and an emitter capable of indicating the leak.

42. A method for detecting a strain deformation with the coated non-conductive substrate as recited in claim 30, the method comprising the following successive steps: applying an electric voltage to the coated non-conductive substrate using an electronic system; and measuring an electrical resistance variation after deformation of the coated non-conductive substrate.

43. The method as recited in claim 42 wherein the electronic system includes a battery and a power supply system.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Other characteristics and advantages of the invention will become apparent from the following detailed description of the invention.

[0022] To illustrate the invention, various embodiments and trials of non-limiting examples will be described, particularly with reference to the following Figures:

[0023] FIG. 1 illustrates an example of one nanoplatelet of reduced graphene oxide according to the present invention.

[0024] FIG. 2 illustrates an example of a few nanoplatelets of reduced graphene oxide according to the present invention.

[0025] FIGS. 3a and 3b illustrate an example of a leak detection.

DETAILED DESCRIPTION

[0026] The invention relates to a non-conductive substrate being at least partially coated on at least one side with a paint comprising reduced graphene oxide having a surface area below 300 m.sup.2.Math.gr.sup.1 and at least one thermosetting polymer, the non-conductive substrate being directly coated by the paint.

[0027] Without willing to be bound by any theory, it seems that the paint including the reduced graphene oxide having a surface area below 300 m.sup.2.Math.gr.sup.1 and the thermosetting polymer well adheres on the non-conductive substrate increasing the lifetime of the coated non-conductive substrate. Indeed, it is believed that thanks to the thermosetting polymer, the reduced graphene oxide is highly dispersed in the paint leading to an improvement of the detection quality. Finally, the paint deposited on the non-conductive substrate is an easy and simple system allowing the detection of leak and strain deformation.

[0028] Preferably, the reduced graphene oxide has a surface area below 290 m.sup.2.Math.gr.sup.1. Preferably, the reduced graphene oxide has a surface area above 200 m.sup.2.Math.gr.sup.1. When the surface area is equal or above to 300 m.sup.2.Math.gr.sup.1, it seems that the quality of the leak detection of non-conductive substrates decreases since the paint is too sensitive and therefore, the background noise is also detected.

[0029] The reduced graphene oxide can be produced from kish graphite as disclosed in the patent applications PCT/IB2017/000348 published as WO2018/178845 A or PCT/IB2018/053416 published as WO2019/220177 A1. It can also be produced from electrode scraps as disclosed in PCT/IB2018/053643 published as WO2019/224579 A1.

[0030] Preferably, the non-conductive substrate is coated on both sides.

[0031] In a preferred embodiment, the coated non-conductive substrate is covered by a protective layer. The protective layer can be made of thermosetting polymers. In this case, the coated non-conductive substrate is protected against corrosion, etc.

[0032] Preferably, the lateral size of the reduced graphene oxide is between 1 and 80 m, more preferably between 40 and 80 m and advantageously between 60 and 80 m.

[0033] Preferably, the weight percentage of oxygen in the reduced graphene oxide is between 2 and 20% and preferably between 2 and 10%. Indeed, without willing to be bound by any theory, it is believed that the percentage of oxygen plays a role in the conductivity and electrical resistance of the paint.

[0034] Preferably, the reduced graphene oxide is not functionalized by a biopolymer. Indeed, without willing to be bound by any theory, it is believed that the biopolymer can decrease the sensitivity of the leak and strain deformation detection.

[0035] Preferably, the reduced graphene oxide is in a form of one or more nanoplatelets. Indeed, without willing to be bound by any theory, it is believed that the form of the reduced graphene oxide can play a role in the detection since it seems that the nanoplatelets can easily form a path in the paint wherein the electricity runs. FIG. 1 illustrates an example of one nanoplatelet of reduced graphene oxide. The lateral size means the highest length of the layer through the X axis, the thickness means the height of the layer through the Z axis and the width of the nanoplatelet is illustrated through the Y axis. FIG. 2 illustrates an example of a few nanoplatelets of reduced graphene oxide.

[0036] Advantageously, the thickness of the paint is between below 2 mm and preferably between 50 and 500 m.

[0037] Preferably, the concentration of the reduced graphene oxide in the paint is between 0.05 and 10% by weight, preferably between 0.05 and 7% by weight and advantageously between 0.5 and 4% by weight. Indeed, without willing to be bound by any theory, it seems that having the reduced graphene oxide in the above concentration can further improve the detection sensitivity in the case of strain because in that range the conductivity of the network of nanoparticles formed inside the thermosetting resin is more sensitive to deformations allowing to detect smaller strains.

[0038] Preferably, the paint does not comprise a thermoplastic polymer. In particular, the paint does not comprise acrylic polymer. Indeed, it is believed that the thermoplastic improves the viscosity of the paint leading to a bad dispersion of reduced graphene oxide and therefore a poor quality of the coated non-conductive substrate.

[0039] Advantageously, the thermosetting polymer is chosen from among: epoxy resin, Polyester resin, Polyurethanes, Polyurea/polyurethane, Vulcanized rubber, Urea-formaldehyde, Melamine resin, Benzoxazines, Polyimides, Bismaleimides, Cyanate esters, polycyanurates, Furan, Silicone resins, Thiolyte and Vinyl ester resins or a mixture thereof.

[0040] Preferably, the molar mass distribution of the polymer is below or equal to 1300 and advantageously between 700 and 1200.

[0041] Preferably, the non-conductive substrate is a textile or a plastic substrate. In particular, the textile is a geomembrane, a geotextile or a geosynthetic clay liner. Preferably, the geomembrane, the geotextile or the geosynthetic clay liner are woven or non-woven.

[0042] In a preferred embodiment, the plastic substrate is chosen from among: Poly(methyl methacrylate), Acrylonitrile Butadiene Styrene, Polyamides family, Policarbonate, Polyvinyl chloride, Polypropylene, Polyethylene and Polyethylene terephthalate or a mixture thereof.

[0043] Preferably, the plastic substrate does not comprise Poly-4-vinylphenol, polyethersulfone or Polydimethylsiloxane. Indeed, without willing to be bound by any theory, it is believed that the presence of these polymers can reduce the detection sensitivity.

[0044] Advantageously, the paint does not comprise titanium dioxide or copper. Preferably, the non-conductive substrate is coated with paint strips to form an alternation between painted and non-painted non-conductive substrate.

[0045] In another embodiment, the non-conductive substrate is coated with one entire layer of paint.

[0046] The second object of the present invention is a method for the manufacture of the non-conductive substrate being at least partially coated according to the present invention, comprising the successive following steps: [0047] A. mixing of reduced graphene oxide, a thermosetting monomer, a curing agent and optionally a solvent, [0048] B. deposition of the mixture on a non-conductive substrate and [0049] C. a curing step.

[0050] Preferably, in step B), the mixing is performed as follows: [0051] i. mixing of reduced graphene oxide having a surface area below 300 m.sup.2.Math.gr.sup.1 and a thermosetting base polymer and optionally a solvent, [0052] ii. addition of a curing agent, [0053] iii. mixing of the mixture obtained in step B).

[0054] Preferably, in step A), the solvent is chosen from among others: xylene, n-butanol, ethylbenzene, naphtha, n-butyl acetate, toluene, cyclic hydrocarbons, isopropanol and benzyl alcohol or a mixture thereof.

[0055] Preferably, in step A), the thermosetting monomer is chosen from: epoxy resin, ester, urethane, urea/polyurethane, Vulcanized rubber, Urea-formaldehyde, Melamine resin, Benzoxazines, imides, Bismaleimides, Cyanate esters, cyanurates, Furan, Silicone resins, Thiolyte and Vinyl ester resins or a mixture thereof.

[0056] Advantageously, in step A), the curing agent is chosen from among: polyamide, phenols, amines and polyaddition isocyanate or a mixture thereof.

[0057] Preferably, in step B), the deposition of the coating is performed by spin coating, spray coating, dip coating, film coating, coil coating, brush coating or spatula coating.

[0058] Preferably, in step C), the curing step is performed by drying at room temperature.

[0059] The third object of the present invention is a method for detecting a leak with the non-conductive substrate being at least partially coated according to the present invention comprising the following successive steps: [0060] a) application of an electric voltage to the non-conductive substrate being at least partially coated using an electronic system, [0061] b) detection of a leak when the electrical circuit is formed in the non-conductive substrate being at least partially coated.

[0062] Without willing to be bound by any theory, it is believed that as illustrated in FIGS. 3a and 3b, when the coated non-conductive substrate detects a leak, an electrical circuit is formed. Indeed, it seems that initially, the non-conductive substrate 1 coated with the paint 2 forms an open electrical circuit even with the application of an electric voltage applied by a voltage source 3. The coated non-conductive substrate is for example deposited on mining waste 4. When there is a leak 5, a conductive fluid (e.g. water) comes into contact with the paint 2 present on the non-conductive substrate 1 and close the circuit. Then, an emitter 6 indicates the leak.

[0063] Preferably, in step I), the electronic system comprises a power supply system and an emitter able to indicate the leak. For example, the power supply system is a battery. Preferably, the emitter is a light. Preferably, in step II), the light is a light emitting diode (LED). In this case, when the electrical circuit is closed as the leak is formed, the electronic system turns on the LED. Alternatively, the emitter is a computer able to indicate the leak by showing a map with the area affected by the leak.

[0064] The fourth object of the present invention is a method for detecting a strain deformation with the non-conductive substrate being at least partially coated according to the present invention comprising the following successive steps: [0065] 1. the application of an electric voltage to the non-conductive substrate being at least partially coated using an electronic system, [0066] 2. the measurement of the electrical resistance variation of the non-conductive substrate being at least partially coated.

[0067] Without willing to be bound by any theory, it is believed that in the paint, the reduced graphene oxide nanoparticles form a conductive network. When the material is subjected to a strain, the internal geometry of the network which is stronger than the thermosetting changes in an important way. The consequence is a change in the electrical resistance of the paint.

[0068] In this case, preferably, the gauge factor, being the ratio of relative change in electrical resistance to the mechanical strain c, is above 5.

[0069] Preferably, in step 1), the electronic system comprises a power supply system. Preferably, it is a battery.

[0070] Finally, the last object of the present invention is the use of a non-conductive substrate being at least partially coated according to the present invention for detecting leak or strain deformation.

[0071] The invention will now be explained in trials carried out for information only. They are not limiting.

EXAMPLES

Example 1: Conductivity Test

[0072] Different nanoparticles were mixed with an epoxy resin having a molar mass distribution between 700 and 1200, bisphenol A-(epichlorhydrin) epoxy resin having a molar mass distribution below or equal to 700 and xylene. The mixture was mixed and dispersed using a device called DISPERMAT. Then, a curing agent comprising polyamide was added in the mixture before being mixed. The mixture was deposited on poly(methylmethacrylate) (PMMA) substrate.

[0073] Then, an electric voltage (10V) was applied on all the trials using an electronic system including a battery. The electrical resistance was determined. The surface area was measured by Brunauer-Emmett-Teller (BET). The conductivity of all Trials was calculated.

[0074] The results are in the following Table 1:

TABLE-US-00001 Nanoparticles Nanoparticles Oxygen Lateral Surface Concentration Sheet Minimum content size area in the paint Resistance Conductivity Trials Nature (wt %) (m) (m.sup.2/gr) (wt. %) (/sq) (S/m) 1* Reduced Between Around 287 0.5 2.7 10.sup.6 3.7 10.sup.3 Graphene 2 and 2.5 70 oxide (rGO) 2* rGO Between Around 287 0.75 6.7 10.sup.4 1.5 10.sup.1 2 and 2.5 70 3* rGO Between Around 287 0.5 3.6 10.sup.8 2.8 10.sup.5 2 and 8 70 4* rGO Between Around 287 0.6 .sup.4.8 10.sup.10 2.1 10.sup.7 2 and 10 30 5 graphene <2 >5 0.5 >10.sup.12 <1 10.sup.8 6 graphene <2 >5 0.75 >10.sup.12 <1 10.sup.8 *according to the present invention.

[0075] Trials 1 to 4 show a high conductivity and therefore a high sensitivity for detecting leak and strain deformation compared to Trials 5 and 6.

Example 2: Leak Detection Test

[0076] Nanoplatelets of Reduced graphene oxide having from 1 to 5% by weight oxygen and a lateral size around 20 m was mixed with epoxy resin having a molar mass distribution between 700 and 1200, bisphenol A-(epichlorhydrin) epoxy resin having a molar mass distribution below or equal to 700 and xylene. A solvent comprising xylene, n-butanol, ethylbenzene and naphtha was added. The mixture was mixed and dispersed using a device called DISPERMAT. Then, a curing agent comprising polyamide was added in the mixture before being mixed. The mixture was deposited on a non-woven geotextile made of polyethylene terephthalate (PET). Then, drying was performed at room temperature.

[0077] The coated geotextile was perforated to create a small hole and then it was positioned between two layers of mining wastes. An electronic system, comprising a battery and LEDs, was connected to the coated geotextiles. Water was poured on the top of the mining wastes. When the water flows through the hole in the coated geotextile, the electrical circuit is formed and the LEDs switch on.

[0078] The same test was performed by depositing paint strips to form a paint alternation on the geotextile. When water came into contact with the coated geotextile, the LEDs that switched on were the one closest to the geotextile in contact with water. Thus, if the geotextile is broad (i.e. hundreds of meters), it is possible to quickly see where the water leak happened thanks to the correlation between the position and the LEDs that are shining.

Example 3: Strain Deformation Test

[0079] Different nanoparticles were mixed with an epoxy resin having a molar mass distribution between 700 and 1200, bisphenol A-(epichlorhydrin) epoxy resin having a molar mass distribution below or equal to 700 and xylene. The mixture was mixed and dispersed using a device called DISPERMAT. Then, a curing agent comprising polyamide was added in the mixture before being mixed. The mixture was deposited on poly(methylmethacrylate) (PMMA) substrate.

[0080] Then, a tensile loading was applied on all the Trials and the gauge factor, being the ratio of relative change in electrical resistance, to the mechanical strain c, was determined. The surface area was measured by Brunauer-Emmett-Teller (BET). A conventional strain gauge sensitivity being made of Constantan was added in comparison.

[0081] The results are in the following Table 2:

TABLE-US-00002 Nanoparticles Nanoparticles Oxygen Lateral Surface Concentration content size area in the paint Strain Gauge Trials Nature (wt %) (m) (m.sup.2/gr) (wt. %) (%) factor 7* rGO Between Around 70 287 0.6 0.2 8 2 and 2.5 8* rGO Between Around 70 287 0.6 0.4 27 2 and 2.5 9* rGO Between Around 70 287 0.6 0.6 27 2 and 2.5 10* rGO Between Around 70 287 0.6 0.8 30 2 and 2.5 12 conventional 0.2 2 strain gauge 13 conventional 0.4 2 strain gauge 14 conventional 0.6 2 strain gauge 15 conventional 0.8 2 strain gauge *according to the present invention.

[0082] Trials 7 to 10 show a high gauge factor and therefore a high sensitivity to detect the strain deformation compared to conventional strain gauge.