Oil leak detection material

Abstract

The present invention provides an oil leak detection material that can reliably detect only oil leaks even when wet with rainwater or other water, can accurately detect the location of the oil leak in a short time regardless of the viscosity or amount of the oil to be detected, and has excellent weather resistance and water resistance. [Solution] The oil leak detection material 10 comprises a colored layer 11 colored with a predetermined color, and a white discoloration layer provided in contact with at least a part of the upper surface of the colored layer 11, in which white powder 12, which is white particles or white powder, has a coating 12a made of silicone resin or silicone rubber on at least a part of its surface, and the white powder 12 is bound together by the coating 12a, while having gaps that absorb oil leaks and repel water.

Description

Technical Field

[0001] The present invention relates to an oil leakage detection material that can reliably detect oil leakage and has excellent weather resistance and water resistance.

Background Art

[0002] For oil leakage at welded joints of tanks or containers where oil is stored, joints of oil pipes, etc., when the tank or container is empty during regular inspections or when there is no oil flowing in the oil pipe, nitrogen gas is enclosed in the empty tank, container, or oil pipe up to a predetermined pressure, and the rate of pressure drop of the nitrogen gas is observed to inspect for leakage. However, for oil leakage in a tank or container storing oil or an oil pipe through which oil is flowing, although it has to be detected visually, there is a risk that a small amount of oil leakage may not be detected visually.

[0003] As a detection material capable of detecting oil leakage from a tank or container storing oil or an oil pipe through which oil is flowing, Patent Document 1 discloses a synthetic resin having water permeability and oil retention for absorbing and holding oil, formed of a non-woven fabric with a thickness of 200 μm or more, a colored layer in which the non-woven fabric is colored, and a white layer with a thickness of at least 150 μm in which a white powder having a refractive index of 1.5 to 1.6 is dispersed in a transparent resin and laminated on one side of the colored layer, the colored layer being opaque when wetted with water and transparent when wetted with the oil so that the hue of the colored layer can be seen through. However, such a conventional oil leakage detection material may be misrecognized as oil leakage because the white layer becomes slightly transparent even when wetted with water such as rainwater. If the white layer is not sufficiently dried after being wetted with water, the oil leakage does not sufficiently penetrate into the white layer and the transparency of the white layer becomes insufficient, making it impossible to reliably detect oil leakage. Furthermore, since the refractive index of the white powder in the white layer is 1.5 to 1.6, the white layer does not become sufficiently transparent with silicone oil having a refractive index of 1.4, making it difficult to detect silicone oil leakage.

[0004] Therefore, the applicant has already provided an oil leak detection material, as described in Patent Document 2, comprising: a colored layer having oil absorption properties and colored with a predetermined color; a white layer having oil absorption properties provided in contact with at least a part of the upper surface of the colored layer and containing or having white particles or white powder attached to a transparent resin layer; a protective layer made of a transparent hydrophobic resin provided so as to cover the upper surface of the white layer; and an oil absorption layer provided on the lower side of the colored layer and being made of a material having oil absorption and oil retention properties and being water-repellent or having been treated with a water-repellent coating, wherein the colored layer and the white layer contain water To prevent penetration of the oil, the colored layer and the white layer are sandwiched between the protective layer and the oil-absorbing layer, and the refractive index difference between the oil, which is the target of oil leak detection and has a refractive index of 1.40 to 1.55, and the white particles or white powder is 0.1 or less. When oil leaks or oil leaks and water come into contact with at least a part of the surface of the oil-absorbing layer, only the oil leaks are absorbed by the oil-absorbing layer and penetrate the colored layer and the white layer, causing the white layer to become transparent or semi-transparent, and allowing the hue of the colored layer to be visually observed through the protective layer.

[0005] The oil leak detection material developed in this way can withstand rainwater and detect silicone oil, but because the oil leak seeps into the oil-absorbing layer from the side by capillary action, penetrates through the colored layer, and reaches the white layer, the white layer becomes transparent or semi-transparent, and the hue of the colored layer becomes visible, causing a change in color and thus detecting the oil leak, it can take several minutes to tens of minutes or more to detect even low-viscosity oils like gasoline, and several hours for high-viscosity oils, which is a problem as it prevents rapid detection of oil leaks.

[0006] Furthermore, this oil leak detection material requires a sufficient amount of oil to penetrate the oil-absorbing layer in the layer-plane direction and diffuse not only into the colored layer but also into the interlayer direction of the white layer. Therefore, there was a risk that droplet-shaped oil leaks might be too small to cause discoloration and thus not be detected, or that extremely small amounts of mist-like oil leaks might not be detected.

[0007] Furthermore, this oil leak detection material had a problem in that it could not accurately detect the location of the oil leak because the oil leaked from the leak point penetrated and diffused into the oil-absorbing layer, colored layer, and white layer, and the direction of penetration and diffusion was influenced by the fiber orientation of the oil-absorbing layer, colored layer, and white layer.

[0008] Furthermore, these oil leak detection materials used a lipophilic transparent resin in the white layer, such as ethylcellulose (a cellulose-based resin). However, sunlight and ultraviolet rays easily broke the carbon-carbon bonds in the main chain, causing the material to become hydrophilic in a short period of time, making it prone to discoloration from rainwater or water leaks. Therefore, there was a need for an oil leak detection material that was highly weather-resistant and water-resistant, did not discolor with water, and only discolored in the event of an oil leak. [Prior art documents] [Patent Documents]

[0009] [Patent Document 1] Patent No. 6609085 [Patent Document 2] Patent No. 7546125 [Overview of the Initiative] [Problems that the invention aims to solve]

[0010] The present invention aims to provide an oil leak detection material that can reliably detect only oil leaks even when wet with water such as rainwater, can accurately detect the location of the oil leak in a short time regardless of the viscosity or amount of the oil leak to be detected, and has excellent weather resistance and water resistance. [Means for solving the problem]

[0011] The oil leak detection material of the present invention, which was made to achieve the above objective, A colored layer that has been colored with a predetermined color, A white discoloration layer is provided in contact with at least a portion of the upper surface of the colored layer, and the white powder, which is white particles or white powder, has a coating made of silicone resin or silicone rubber on at least a portion of its surface, and the white powder particles are bound together by the coating, while having gaps that absorb oil and repel water. They are prepared.

[0012] This oil leak detection material is designed so that when the leaked oil is absorbed into the gap, the discolored layer becomes transparent, making the color of the colored layer visible.

[0013] The oil leak detection material preferably contains the white particles or white powder having a refractive index of 1.40 to 1.50.

[0014] This oil leak detection material is made of a silicone resin or silicone rubber having, for example, a polydimethylsiloxane skeleton, a polydiphenylsiloxane skeleton, or a polymethylphenylsiloxane skeleton.

[0015] This oil leak detection material contains, for example, 30 to 90 parts by mass of the white powder and 10 to 70 parts by mass of the silicone resin or silicone rubber in the discoloration layer.

[0016] This oil leak detection material is such that, for example, the discolored layer is a coating layer of a composition containing the white powder, binder, and solvent, and the gaps are traces of the solvent disappearing from the coating layer.

[0017] The oil leak detection material may have the underside of the colored layer covered with an oil-absorbing or non-oil-absorbing base layer made of an oil-absorbing base layer selected from woven fabric, non-woven fabric, and paper, or a film.

[0018] This oil leak detection material may also include an oil-absorbing and / or oil-permeable protective layer, selected from woven fabric, nonwoven fabric, paper, and mesh, which covers the upper surface of the discoloration layer.

[0019] It is preferable that the protective layer of this oil leakage detection material is made of a hydrophobic material.

[0020] This oil leakage detection material preferably includes an adhesive layer or an adhesive layer that can adhere to an object to be detected for oil leakage on the lower surface side of the colored layer.

[0021] This oil leakage detection material may be such that the adhesive layer or the adhesive layer and the colored layer are permeable to the oil leakage.

[0022] This oil leakage detection material is such that the white powder is the white particles or white powder selected from, for example, organic compounds, metal soaps, plastic powders, metal inorganic salts, minerals, glass beads, and glass fillers.

[0023] It is more preferable that the white powder of this oil leakage detection material is the white particles or white powder containing the metal soap and / or amorphous silica.

[0024] It is even more preferable that the white powder of this oil leakage detection material is the white particles or white powder containing amorphous silica.

[0025] This oil leakage detection material is such that the colored layer is colored in any color selected from, for example, black, dark blue, red, orange, blue, green, brown, and purple, and intermediate colors thereof.

[0026] This oil leakage detection material may be such that the colored layer and / or the discoloration layer are shaped into the shape of letters, symbols, and / or figures, or the colored layer may be printed in the shape of letters, symbols, and / or figures.

[0027] It is preferable that the difference in refractive index between the white particles or white powder and the oil leakage of this oil leakage detection material is 0.1 or less.

Advantages of the Invention

[0028] The oil leak detection material of the present invention does not change color to transparent or semi-transparent even when wet with water from leaks or rainwater. Even when wet, the color-changing layer, which has a silicone resin or silicone rubber, changes color to transparent or semi-transparent only when exposed to oil from a leak, making the color of the colored layer visible. Therefore, oil leaks can be reliably detected without misidentification.

[0029] Furthermore, this oil leak detection material can detect oil leaks in a timely manner, whether it is a large amount of oil or a small amount such as a droplet or oil mist. As long as the oil seeps into the discolored layer, the discolored layer will change color from white to transparent or semi-transparent within tens of seconds at the latest, making the color of the colored layer visible.

[0030] Furthermore, this oil leak detection material allows for accurate identification of the oil leak location and enables quick repairs, as only the areas wet with oil in the discolored layer become transparent or semi-transparent, revealing the color of the colored layer underneath.

[0031] Furthermore, because the silicone resin or silicone rubber in the discoloration layer of this oil leak detection material does not decompose or become hydrophilic due to sunlight or ultraviolet rays, it has excellent weather resistance and water resistance, and can maintain its performance for a long period of time, eliminating the need for frequent replacement and reducing troublesome labor. [Brief explanation of the drawing]

[0032] [Figure 1] These are a front view and a schematic cross-sectional view showing the state before and after use of one embodiment of an oil leak detection material to which the present invention is applied. [Figure 2] This is a schematic cross-sectional view showing a partially enlarged view of the discolored layer of an oil leak detection material to which the present invention is applied. [Figure 3] These are a front view and a schematic cross-sectional view showing the state of an oil leak detection material before and after use in another embodiment to which the present invention is applied. [Figure 4] These are a front view and a schematic cross-sectional view showing the state of an oil leak detection material before and after use in another embodiment to which the present invention is applied. [Figure 5]This is a schematic cross-sectional view showing the state of an oil leak detection material before use in another embodiment to which the present invention is applied. [Modes for carrying out the invention]

[0033] Figure 1(a1) shows a front view of an example of an oil leak detection material 10 to which the present invention is applied before use, and Figure 1(b1) shows a schematic cross-sectional view of the same material in cross-section XX. Figure 1(a2) shows a front view of an example of a used state in which the material is attached to an object 30 to be detected for oil leaks and the oil leak 20 adheres to it, and Figure 1(b2) shows a schematic cross-sectional view of the same material in cross-section XX.

[0034] As shown in Figures 1(a1) and (b1), the oil leak detection material 10 has a rectangular colored layer 13 that is colored with a predetermined color, a white discoloration layer 11 that contains white powder 12 which are rectangular in shape and white particles or white powder of the same size as the colored layer 13, and a release paper 16 which is bonded to it via a release paper adhesive layer 15. In the discoloration layer 11, as shown in Figure 2, at least a portion of the surface of the white powder 12 has a coating 12a made of silicone resin or silicone rubber, and the white powder 12s are connected to each other by the coating 12a, so that it has gaps 12b that absorb oil leaks 20 (see Figures 1(a2) and (b2)) and repel water and do not absorb water.

[0035] As shown in Figures (a2) and (b2), the oil leak detection material 10 is designed so that when the leaked oil 20 is absorbed into the gap 12b and wets the white powder 12, the discoloration layer 11 becomes transparent, the color of the colored layer 13 becomes visible, and the oil leak and the location of the leak are detected.

[0036] A white discoloration layer 11 is provided in close contact with the upper surface of the colored layer 13. The discoloration layer 11 is formed by a coating layer of a composition containing white powder 12, a silicone resin or silicone rubber raw material binder, and a solvent. After coating with the composition, when the solvent evaporates, the cured product, which is the raw material binder or, if necessary, a thermo-cured or photo-cured silicone resin or silicone rubber, forms a film 12a on at least a portion of the surface of the white powder 12, while binding the white powder 12 together. However, gaps 12b are formed as traces of the solvent's disappearance within the coating layer as the solvent evaporates. At this time, the discoloration layer 11 and the colored layer 13 are joined together due to the bonding properties of the raw material binder. Since the gaps 12b are formed between the individual white particles or white powder of the white powder 12, the discoloration layer 11 is a porous layer.

[0037] In order to form the gap 12b, it is important to adjust the ratio of the white powder 12 to the raw material binder of silicone resin or silicone rubber in the composition to 30-90:70-10 by weight, preferably 50-80:50-20. Such a composition may optionally contain additives such as a silicone crosslinking agent.

[0038] If the mass ratio of the white powder 12 to the silicone resin or silicone rubber binder is outside the range of 30-90:70-10, and the proportion of the white powder 12 is low, the whiteness will decrease due to a reduction in porosity and a relative decrease in the white component of the white powder, resulting in a smaller change in color tone with the colored layer 13 in the event of oil leakage. On the other hand, if the mass ratio of the silicone resin or silicone rubber binder is low, the water repellency and coating strength will decrease, causing discoloration due to water absorption, or the coating to become brittle and easily peel off.

[0039] The mass ratio of the white powder 12 to the silicone resin or silicone rubber raw material binder is adjusted as appropriate depending on the properties of the white powder 12 (for example, physical properties such as particle size and specific surface area). For example, if the white powder 12 is mainly silica-based powder with an average particle size of about 10 μm, a ratio of about 40 parts by mass of white powder to 60 parts by mass of silicone resin or silicone rubber is preferred. On the other hand, if the white powder 12 is zinc stearate with an average particle size of about 10 μm, a ratio of about 75 parts by mass of white powder to 25 parts by mass of silicone resin or silicone rubber is preferred.

[0040] Suitable materials for use as white powders are those with a refractive index in the range of 1.40 to 1.50, that are resistant to decomposition by sunlight and ultraviolet rays, are poorly soluble in water, and have a melting point (above 100°C) that does not melt at ambient temperature. Metal soaps and silica are examples of materials that meet these characteristics and are preferred. Silica, in particular, is preferred over metal soaps with similar refractive indices because it becomes clearer and more transparent upon contact with oil, and also has a higher melting point.

[0041] The white powder 12 is made visible as white due to diffuse reflection, provided that its average particle size is 20 μm or less, preferably 20 to 1 μm. A particle size of 10 μm or less is particularly preferable because it increases the light scattering effect and thus the whiteness of the discolored layer 11. The particle size of the white powder or white particles is measured, for example, with a grindometer. Since the silicone resin or silicone rubber coating 12a is extremely thin and almost transparent, the white powder 12 continues to diffusely reflect light regardless of the thickness of the silicone resin or silicone rubber coating 12 on at least a portion of its surface. Therefore, the discolored layer 11 is visible as white unless it comes into contact with the leaked oil 20.

[0042] When the discolored layer 11 comes into contact with the leaked oil, the high permeability of the leaked oil to the gap 12b due to the silicone resin or silicone rubber in the coating 12a allows the leaked oil to penetrate the gap 12b, overcoming the oil-repellent properties of the silicone resin or silicone rubber. Once the gap 12b is filled, the white powder 12 can no longer diffusely reflect light, and the layer becomes transparent or semi-transparent. This phenomenon occurs because light that has passed through the permeated leaked oil can pass through the discolored layer 11 without being significantly bent at the boundary with the white powder or white particles.

[0043] However, because silicone resin and silicone rubber have high water repellency and therefore low affinity for water, moisture such as rainwater, leaks, and humidity cannot penetrate the gap 12b. As a result, even when wet with these moisture, the discoloration layer 11 does not become transparent or semi-transparent, but remains white. Thus, the oil leak detection material 10 is able to selectively detect oil leaks.

[0044] However, silicone resins and silicone rubbers do not decompose in sunlight or ultraviolet rays, are less likely to become hydrophilic, and are resistant to high temperatures and humidity, making them excellent materials in terms of weather resistance and water resistance. Therefore, this oil leak detection material 10 does not change color with water, only with oil, and does not deteriorate even under harsh indoor and outdoor conditions, maintaining high weather resistance, water resistance, and oil leak detection selectivity.

[0045] Examples of such white particles or white powders include those that are solid at room temperature, specifically fatty acid derivatives such as stearic acid and palmitic acid and their calcium salts such as metal soaps, alcohol derivatives, ether derivatives, aldehyde derivatives, ketone derivatives, amine derivatives, amide derivatives, nitrile derivatives, hydrocarbon derivatives, thiol derivatives, sulfide derivatives, and other organic compound powders or particles, as well as polyvinyl chloride, polyethylene, polypropylene, polystyrene, acrylonitrile butadiene styrene, acrylonitrile styrene, polymethyl methacrylic, polyvinyl alcohol, polyvinylidene chloride, polyethylene terephthalate, polyamide, polyacetal, and poly Examples include plastic powders or particles such as recarbonates, polyphenylene ethers, polybutylene terephthalate, polyvinylidene fluoride, polysulfones, polyethersulfones, polyphenylene sulfides, polyarylates, polyamide-imides, polyetherimides, polyetheretherketones, polyimides, liquid crystal polymers, polytetrafluoroethylenes, phenolic resins, urea resins, melamine resins, unsaturated polyesters, epoxy resins, silicone resins, and polyurethanes; alkaline earth metal salts such as magnesium carbonate and calcium carbonate; inorganic metal salt powders or particles such as aluminum hydroxide, talc, and silica; mineral powders or particles; glass beads; and glass fillers.

[0046] It is preferable to select such white powders or white particles such that the difference in refractive index between them and the oil of the oil leak detection target is 0.1 or less. The oil of the oil leak detection target is a hydrophobic oil derived from minerals such as petroleum, animals, or plants that floats on water and is liquid at room temperature, with a refractive index of 1.40 to 1.55, such as insulating oil, kerosene, light oil, heavy oil, linseed oil, paraffin oil, silicone oil, and hydraulic oil. When such oil is used as the oil leak detection target, preferred white powders or white particles include stearic acid (refractive index 1.43), talc (refractive index 1.54), urea resin powder (refractive index 1.57), calcium carbonate (refractive index 1.50 to 1.64), aluminum hydroxide (refractive index 1.57), magnesium carbonate (refractive index 1.52 to 1.53), glass beads (refractive index 1.52 to 1.57), and glass filler (refractive index 1.50 to 1.58).

[0047] These white powders or white particles may be used individually or in combination of several types, such as two or three types.

[0048] It is preferable to make the discolored layer 11 sufficiently opaque by setting its thickness to 1 μm or more. The upper limit of the discolored layer 11 is preferably 260 μm or less, considering its relationship with the flexibility of the oil leak detection material 10.

[0049] In the oil leak detection material 10, the colored layer 13 can be made of oil-absorbing materials such as paper, nonwoven fabrics, woven fabrics, porous cement, porous ceramics, porous metals, and other porous inorganic materials, foamed plastics, and ink coatings. These materials are colored to a predetermined color. The coloring is preferably done with a coloring agent such as a pigment, dye, or mixture thereof that is resistant to fading in sunlight and has excellent lightfastness. A hue that is easily recognizable by the naked eye or image sensors and has a clear contrast with white is preferred, and among these, chromatic colors such as black, navy blue, red, orange, blue, green, brown, and purple, or intermediate colors of any of these, are even more preferred. Black and navy blue are prone to changes in brightness and may be mistaken for shadows, so red, which is a dangerous color due to changes in saturation, is practical and even more preferred. The coloring may be applied to the material constituting the oil-absorbing material, or to the material molded into a predetermined shape. The thickness of the colored layer 13 is preferably 1 to 150 μm.

[0050] The oil leak detection material 10 shown in Figure 1 is manufactured as follows. First, a composition containing white powder 12, a silicone resin or silicone rubber raw material binder, a solvent, and various additives as needed is prepared. This composition is applied to the upper surface of a colored layer 13, which has a release paper attached to an adhesive layer 15 on its lower side, to form a coating layer. The resulting coating layer is air-dried or air-dried to evaporate the solvent, and heat-treated or light-irradiated as needed to crosslink and harden into silicone resin or silicone rubber. The hardened material forms a film 12a on at least a portion of the surface of the white powder 12, binding the white powders 12 together, and gaps 12b are formed as the solvent evaporates, resulting in the oil leak detection material 10.

[0051] As shown in Figure 1(b2), the oil leak detection material 10 is used by attaching the adhesive layer 15 to an object 30 to be detected for oil leaks, such as a flange or pipe. When oil leaks onto the discolored layer 11, it penetrates into the gap 12b, and at the point of penetration, the discolored layer 11 becomes transparent or semi-transparent, making the colored layer 13 visible, allowing for the rapid detection of both the fact of an oil leak and the location of the leak. This penetration of oil into the gap 12b is more of a filling phenomenon than a capillary action, so the oil does not diffuse to areas other than the leak location, making it possible to identify the discolored area retrospectively.

[0052] The mechanism of discoloration of the oil leak detection material 10 is presumed to be as follows. When the oil leak detection material 10 is not in contact with an oil leak, only the white color of the discolored layer 11 is visible, as shown in Figure 1(a1), and the hue of the colored layer 13 is not visible. The difference in refractive index between the white particles or white powder dispersed in the discolored layer 11 and the air in the gaps, i.e., microscopic spaces, surrounding the white particles or white powder is large, and the light that has passed through the discolored layer 11 is greatly bent and dispersed at the boundary between the white particles or white powder and the microscopic spaces. On the other hand, when an oil leak comes into contact with the oil leak detection material 10, the oil leak penetrates into the discolored layer 11. The discolored layer 11 becomes transparent or semi-transparent, and the hue of the colored layer 13 becomes visible, as shown in Figure 1. The refractive index difference between the oil that has penetrated the discolored layer 11 and filled the microscopic space surrounding the white particles or white powder and the white particles or white powder is smaller than the refractive index difference between air and the white particles or white powder. This allows light that has passed through the discolored layer 11 to pass through without being significantly bent at the boundary between the white particles or white powder and the oil in the microscopic space. For this reason, it is preferable to select the white powder or white particles such that the refractive index difference with the oil of the oil leak detection target is 0.1 or less.

[0053] Although not shown in Figure 1(b2), this oil leak detection material 10 may also be used in such a way that the oil seeping from the object to be detected 30 penetrates the adhesive layer 15, colored layer 13, and discoloration layer 11, causing the discoloration layer 11 to change to a transparent or semi-transparent state, and making the color of the colored layer 13 visible. It is preferable that the adhesive layer 15 is formed of an adhesive such as rubber, acrylic, silicone, polyvinyl, or polyurethane so that the oil penetrates the adhesive layer 15 and reaches the colored layer 13 and discoloration layer 11.

[0054] Another embodiment of the oil leak detection material 10 is shown in Figure 3. A schematic cross-sectional view of an example before use is shown in Figure 3(a1), and a schematic cross-sectional view of the material in use, with the oil leak 20 attached to the object to be detected 30, is shown in Figure 3(a2). In this embodiment, the oil leak detection material 10 has a base layer 14 between the colored layer 13 and the adhesive layer 15 of the oil leak detection material in Figure 1. This oil leak detection material 10 can be used in the same manner as shown in Figure 1.

[0055] The base material layer 14 may be, for example, an oil-permeable nonwoven or woven fabric made of a hydrophobic resin, and is preferably a nonwoven fabric. Examples of hydrophobic resins include cellulose, cellulose derivatives, polyolefins, polyvinyl chloride, polyvinylidene chloride, polyester, polystyrene, hydrochloric acid rubber, polyamide, fluororesin, polybutene, polyvinyl butyral, polyethylene oxide, polyurethane, cellulose acetate butyrate, hydroxyethylcellulose, and polyimide.

[0056] The colored layer 13 may be made of the aforementioned materials and may be attached to the base layer 14 via adhesives such as heat welding, rubber-based, acrylic-based, silicone-based, polyvinyl-based, polyurethane-based adhesives, or composites thereof. Alternatively, the colored layer 13 may be printed on the base layer 14 with a colorant-containing ink.

[0057] The base layer 14 may be made of a hydrophobic resin and be an oil-impermeable film so that only oil leaks from the discoloration layer 11 side are detected. Examples of such hydrophobic resins include cellulose, cellulose derivatives, polyolefins, polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, polyester, polystyrene, hydrochloric acid rubber, polyamide, fluororesin, polybutene, polyvinyl butyral, polyethylene oxide, polyurethane, cellulose acetate butyrate, hydroxyethylcellulose, and polyimide.

[0058] Another embodiment of the oil leak detection material 10 is shown in Figure 4. A schematic cross-sectional view of an example before use is shown in Figure 4(a1), and a schematic cross-sectional view of the material in use, with the oil leak 20 attached to the object to be detected 30, is shown in Figure 4(a2). The oil leak detection material 10 in this embodiment has a protective layer 17 made of nonwoven fabric on the upper surface of the discolored layer 11 of the oil leak detection material in Figure 1. This oil leak detection material 10 can be used in the same manner as shown in Figure 1.

[0059] The discoloration layer 11 consists of a white powder 12 and a coating 12a, and because it has gaps, it is easily peeled off by physical contact such as scratching with a fingernail or rubbing against tools. Therefore, covering and protecting it with an oil-absorbing and / or oil-permeable nonwoven fabric protective layer 17 does not affect oil leak detection, but also makes it resistant to physical contact.

[0060] The protective layer 17 may be made of nonwoven fabric, or of any other material such as woven fabric, paper, or mesh, as long as it is oil-absorbing and / or oil-permeable. Examples of materials for the protective layer 17 include hydrophobic resins, specifically cellulose, cellulose derivatives, polyolefins, polyvinyl chloride, polyvinylidene chloride, polyester, polystyrene, hydrochloric acid rubber, polyamide, fluororesin, polybutene, polyvinyl butyral, polyethylene oxide, polyurethane, cellulose acetate butyrate, hydroxyethylcellulose, and polyimide.

[0061] The adhesive layer 22 for the release paper is preferably formed of an adhesive that is both lipophilic and hydrophobic, specifically a rubber-based adhesive, an acrylic-based adhesive, a silicone-based adhesive, a polyvinyl-based adhesive, a polyurethane-based adhesive, or a composite adhesive thereof.

[0062] Another embodiment of the oil leak detection material 10 is shown in Figure 5. The oil leak detection material 10 shown in Figures 1 and 3-4 has an adhesive layer 15, but as shown in Figure 5, it does not have to have an adhesive layer.

[0063] In addition, the shapes of the oil leak detection material 10 shown in Figures 1 and 3-5 can be replaced with various other shapes such as rectangles and circles, as well as arbitrary shapes such as letters and symbols. For example, the colored layer 11 itself can be made into the shape of letters indicating an oil leak, such as the word "oil," so that the letters become visible when oil leaks occur, or conversely, it can be designed to be invisible. Alternatively, the colored layer 13 can be made into the shape of letters or symbols to be displayed or hidden.

[0064] For example, if the colored layer 13 itself is shaped like letters indicating an oil leak, when there is no oil leak, the letters are hidden by the discolored layer 11 and do not appear. When an oil leak occurs, the discolored layer 11 becomes transparent or semi-transparent, and the letters of the colored layer 13 become visible and can be displayed. On the other hand, if the discolored layer 11 itself is shaped like letters indicating an oil leak, when there is no oil leak, the colored layer 13 is visible in the non-letter-shaped parts of the discolored layer 11, while the letter shape hides the colored layer 13, making it visible as letters. However, when an oil leak occurs, the discolored layer 11 becomes transparent or semi-transparent and no longer hides the colored layer 13, so the letters become invisible and appear not to be displayed.

[0065] This oil leak detection material 10 can be easily attached to areas where oil leaks are likely to occur, such as flanges, and can reliably detect oil leaks even if the material 10 gets wet with rainwater or leak water. Alternatively, this oil leak detection material 10 can reliably detect the presence of an oil leak only when oil alone or a water-oil mixture containing both water and oil comes into contact with the material 10. [Examples]

[0066] The following describes in detail examples to which the present invention is applied and comparative examples to which the present invention is not applied. (Example 1) The oil leak detection material shown in Figure 3 was prepared as follows. First, a black ink was prepared by kneading 10 parts by mass of carbon black as a black pigment, 25 parts by mass of transparent silicone resin (Shin-Etsu Chemical Co., Ltd., KR-220L), and 65 parts by mass of 1-butanol. This black ink was screen printed onto a tacky white polyester film (Lintec Corporation, PETWH50(A)PAT1 8LK2) used as a base layer / adhesive layer / release paper to a thickness of approximately 5 μm, and then dried to form a colored layer. Next, a white ink was prepared by kneading 35 parts by mass of zinc stearate (refractive index 1.45~1.50) as a white powder, 12 parts by mass of transparent silicone resin (Shin-Etsu Chemical Co., Ltd., KR-220L), and 53 parts by mass of 1-butanol. This white ink was screen printed to a thickness of approximately 15 μm onto the colored layer / substrate layer / adhesive layer / release paper side, and then dried to form a discolored layer. Afterward, it was cut into 50 mm x 50 mm squares to obtain the oil leak detection material shown in Figure 3. The resulting oil leak detection material had an opaque discolored layer that made the hue of the colored layer almost invisible.

[0067] (Example 2) The oil leak detection material shown in Figure 4 was prepared as follows. First, a white ink was prepared by kneading 35 parts by mass of zinc stearate (refractive index 1.45-1.50) as a white powder, 12 parts by mass of transparent silicone resin (Shin-Etsu Chemical Co., Ltd., KR-220L), and 53 parts by mass of 1-butanol. This white ink was applied to a polyester nonwoven fabric, which served as the nonwoven fabric layer, by screen printing to a thickness of approximately 15 μm, and then dried to form a discolored layer. Next, a black ink was prepared by kneading 10 parts by mass of carbon black as a black pigment, 25 parts by mass of transparent silicone resin (Shin-Etsu Chemical Co., Ltd., KR-220L), and 65 parts by mass of 1-butanol. This black ink was applied to the discolored layer side of the discolored layer / nonwoven fabric layer by screen printing to a thickness of approximately 5 μm, and then dried to form a colored layer. An acrylic adhesive and release paper were applied to the colored layer side of this colored layer / discolored layer / nonwoven fabric layer as an adhesive layer / release paper. Then, it was cut into 50mm x 50mm squares to obtain the oil leak detection material shown in Figure 4. The resulting oil leak detection material had an opaque discolored layer that made it almost impossible to see the hue of the colored layer.

[0068] (Comparative Example 1) An oil leak detection material as shown in Example 1 of Patent Document 2 was prepared. First, a white ink was prepared by kneading 30 parts by mass of stearic acid (refractive index 1.43) as a white powder, 5 parts by mass of transparent ethylcellulose resin, and 65 parts by mass of xylene. This white ink was applied to one side of a black-colored high-quality paper to form a colored layer using a coater applicator to a coating thickness of 150 μm, and then dried to form a discoloration layer. Next, the substrate with the discoloration layer formed on one side of the colored layer was cut into 40 mm x 40 mm squares. In addition, a polyethylene nonwoven fabric (Tyvek 1056DR (trade name), manufactured by Asahi DuPont Flashspun Products, with a basis weight of 54 g / m²) was used as the oil absorption layer. 2An oil-permeable acrylic adhesive was applied to both sides of the material to form a first hydrophobic adhesive layer and a release paper adhesive layer, which were then cut into 50mm x 50mm squares. The cut colored layer was attached to the center of the cut first hydrophobic adhesive layer with the discoloration layer facing upwards. Furthermore, a 50mm x 50mm transparent polyethylene terephthalate film was applied as a protective layer so that the top surface of the discoloration layer and the sides of both the discoloration layer and the colored layer were covered. Subsequently, a 50mm x 50mm release paper was attached to the release paper adhesive layer 22 to obtain an oil leak detection material. In the obtained oil leak detection material, the hue of the colored layer could not be seen from the protective layer due to the opaque discoloration layer.

[0069] (Comparative Example 2) An oil leak detection material was prepared in the same manner as in Example 1, except that the resin of the discoloration layer was a cellulose-based resin. First, a black ink was prepared by kneading 10 parts by mass of carbon black as a black pigment, 25 parts by mass of transparent silicone resin (Shin-Etsu Chemical Co., Ltd., KR-220L), and 65 parts by mass of 1-butanol. This black ink was applied to a tacky white polyester film (Lintec Corporation, PETWH50(A)PAT1 8LK2) used as the base layer / adhesive layer / release paper with a coating thickness of approximately 5 μm by screen printing, and then dried to form a colored layer. Next, a white ink was prepared by kneading 35 parts by mass of zinc stearate (refractive index 1.45~1.50) as a white powder, 5 parts by mass of ethyl cellulose resin, and 60 parts by mass of 1-butanol. This white ink was applied to the colored layer side of the colored layer / base layer / adhesive layer / release paper with a coating thickness of approximately 15 μm by screen printing, and then dried to form a discoloration layer. Subsequently, the material was cut into 50mm x 50mm squares to obtain the oil leak detection material shown in Figure 1. The resulting oil leak detection material had an opaque discoloration layer, making the hue of the colored layer almost invisible.

[0070] (Example 3) Test specimens were prepared by attaching the oil leak detection materials 10 obtained in Examples 1 and 2 and the oil leak detection materials obtained in Comparative Examples 1 and 2 to aluminum plates. These test specimens were placed outdoors (south-facing, 45-degree angle, no shade) for one month. After that, they were immersed in a tray containing water (refractive index 1.33), hydraulic oil (refractive index 1.5; manufactured by ENEOS Corporation, High-Pressure Insulating Oil K), or silicone oil (refractive index 1.44; manufactured by Shin-Etsu Chemical Co., Ltd., KF-96-500CS), and the time until the discoloration layer began to change was measured. The measurement results are shown in Table 1 below.

[0071] [Table 1]

[0072] As is clear from Table 1, the oil leak detection material 10 of Examples 1 and 2 did not change color when immersed in water, but when immersed in hydraulic oil and silicone oil, they clearly changed color in 1 second, 10 seconds, and 30 seconds, allowing for instantaneous visual detection of oil wetting. On the other hand, the oil leak detection material of Comparative Example 1 did not change color when immersed in water, but it took 600 seconds when immersed in hydraulic oil and 8 hours when immersed in silicone oil, making instantaneous visual detection of oil wetting impossible. Furthermore, Comparative Example 2 changed color immediately when immersed in water. This was because the cellulose resin in the discoloration layer deteriorated due to ultraviolet light, increasing its hydrophilicity, resulting in discoloration when wet, making it clear that it could not be used outdoors. [Industrial applicability]

[0073] According to the oil leak detection material of the present invention, it does not change color with rainwater alone, but only changes color when oil is leaking, and can reliably detect oil leaks even with silicone oil, which has a refractive index close to that of water, and can detect oil leaks from tanks and pipe flanges of various types of oil. [Explanation of Symbols]

[0074] 10 is the oil leak detection material, 11 is the discolored layer, 12 is the white powder, 12a is the coating, 12b is the gap, 13 is the colored layer, 14 is the base layer, 15 is the adhesive layer, 16 is the release paper, 20 is the oil leak, and 30 is the object to be detected by the oil leak.

Claims

1. A colored layer that has been colored with a predetermined color, A white discoloration layer is provided in contact with at least a portion of the upper surface of the colored layer, and the white powder, which is white particles or white powder, has a coating made of silicone resin or silicone rubber on at least a portion of its surface, and the white powder particles are bound together by the coating, while having gaps that absorb oil and repel water. An oil leak detection material characterized by having the following features.

2. The oil leak detection material according to claim 1, characterized in that the discolored layer becomes transparent when the oil leak is absorbed into the gap, making the color of the colored layer visible.

3. The oil leak detection material according to claim 2, characterized in that the white powder contains white particles or white powder having a refractive index of 1.40 to 1.

50.

4. The oil leak detection material according to claim 1, characterized in that the silicone resin or silicone rubber has a polydimethylsiloxane skeleton, a polydiphenylsiloxane skeleton, or a polymethylphenylsiloxane skeleton.

5. The oil leak detection material according to claim 1, characterized in that the discoloration layer contains, for example, 30 to 90 parts by mass of the white powder and 10 to 70 parts by mass of the silicone resin or silicone rubber.

6. The oil leak detection material according to claim 1, characterized in that the discolored layer is a coating layer of a composition containing the white powder, the raw material binder of the silicone resin or silicone rubber, and a solvent, and the gap is the trace of the disappearance of the solvent in the coating layer.

7. The oil leak detection material according to claim 1, characterized in that the lower surface of the colored layer is covered with an oil-absorbing or non-oil-absorbing base layer made of an oil-absorbing base layer or film selected from woven fabric, non-woven fabric, and paper.

8. The oil leak detection material according to claim 1, characterized in that it comprises an oil-absorbing and / or oil-permeable protective layer selected from woven fabric, nonwoven fabric, paper, and mesh, which covers the upper surface of the discoloration layer.

9. The oil leak detection material according to claim 8, characterized in that the protective layer is made of a hydrophobic material.

10. The oil leak detection material according to claim 1, characterized in that the lower surface of the colored layer is provided with an adhesive layer that can be adhered to or attached to an object for which oil leaks should be detected.

11. The oil leak detection material according to claim 10, characterized in that the adhesive layer or the adhesive layer and the colored layer are permeable to the oil leak.

12. The oil leak detection material according to claim 1, characterized in that the white powder is white particles or white powder comprising at least one selected from organic compounds, metal soaps, plastic powders, metal inorganic salts, minerals, silica, glass beads, and glass fillers.

13. The oil leak detection material according to claim 12, characterized in that the white powder is the white particles or white powder containing the metal soap and / or amorphous silica.

14. The oil leak detection material according to claim 12, characterized in that the white powder is the white particles or white powder containing amorphous silica.

15. The oil leak detection material according to claim 1, characterized in that the colored layer is colored with any of the following colors: black, navy blue, red, orange, blue, green, brown, and purple, or any intermediate color thereof.

16. The oil leak detection material according to claim 1, characterized in that the colored layer and / or the discoloration layer are shaped into the form of letters, symbols, and / or figures, or the colored layer is printed in the form of letters, symbols, and / or figures.

17. The oil leak detection material according to claim 1, characterized in that the difference in refractive index between the white particles or white powder and the oil leak is 0.1 or less.

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