Leaked oil detection material

Abstract

To provide an oil leakage detection material which has no risk of misrecognition as leaked oil even when being wet with water such as rainwater, can surely detect leaked oil even in a wet state, and can detect even leaked oil having a refractive index of less than 1.5.SOLUTION: A leaked oil detection material 10 includes a colored layer 16 having an oil absorption property, a white layer 14 which is provided so as to come in contact with an upper surface of the colored layer 16, contains white powder and has an oil absorption property, a protective layer 12 which is provided so as to cover an upper surface of the white layer 14 and is composed of a transparent hydrophobic resin, and an oil absorption layer 18 which is provided on a lower face side of the colored layer 16, has an oil absorption property and an oil retention property, and has water repellency, wherein the colored layer 16 and the white layer 14 are sandwiched between the protective layer 12 and the oil absorption layer 18 so as to prevent water from being penetrated into the colored layer 16 and the white layer 14, when oil is leaked in the oil absorption layer 18, or oil is leaked therein and water comes in contact therewith, only the leaked oil is absorbed in the oil absorption layer 18, is penetrated into the colored layer 16 and the white layer 14, the white layer 14 becomes in a transparent state or a semi-transparent state, and a hue of the colored layer 16 can be visually observed through the protective layer 12.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an oil leakage detection material that can reliably detect oil leakage and temporarily retain leaked oil. [Background technology]

[0002] In order to check for oil leaks from welds in tanks and containers that store oil, or from joints in oil piping, nitrogen gas is filled into the empty tanks, containers, or oil piping up to a specified pressure during regular inspections when the tanks or containers are empty and no oil is flowing through the oil piping, and the rate at which the nitrogen gas pressure drops is observed to check for leaks. However, oil leaks from tanks and containers that store oil, or from oil piping through which oil flows, must be detected visually, and small amounts of oil leaking may not be detected visually. Also, if leaking oil drips onto the ground, it can cause soil contamination.

[0003] As a detection material capable of detecting oil leaks from tanks or containers in which oil is stored or from oil pipes through which oil flows, the following Patent Document 1 proposes an oil leakage detection material having a colored layer made of a synthetic resin having water permeability and oil retention properties to absorb and retain oil, formed of a nonwoven fabric having a thickness of 200 μm or more, the nonwoven fabric being colored, and a white layer having a thickness of at least 150 μm laminated to one side of the colored layer, which is opaque when the colored layer is wet with water and becomes transparent when the colored layer is wet with oil, and in which a white powder with a refractive index of 1.5 to 1.6 is dispersed in a transparent resin so that the hue of the colored layer can be seen through. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 6609085 Summary of the Invention [Problem to be solved by the invention]

[0005] The above-described oil leakage detector can detect oil leakage from a tank or container in which oil is stored, or from an oil pipe through which oil flows. However, when this oil leakage detection material gets wet with water such as rainwater, the white layer becomes slightly transparent, and there is a risk of misidentifying it as oil leakage. In addition, it was found that if the white layer of the oil leakage detection material that has become wet with water does not dry sufficiently, the leaked oil does not penetrate the white layer sufficiently, and the white layer does not become sufficiently transparent, making it difficult to reliably detect the oil leakage. Furthermore, since the refractive index of the white powder in the white layer is 1.5 to 1.6, it was also found that the white layer does not become sufficiently transparent with silicone oil with a refractive index of 1.4, making it difficult to detect the silicone oil leakage.

[0006] The present invention aims to provide an oil leak detection material which, even when wet with water such as rainwater, is not likely to be mistaken for an oil leak, can reliably detect oil leaks even when wet, and can detect oil leaks even from oils with a refractive index of less than 1.5, such as silicone oil. [Means for solving the problem]

[0007] The oil leakage detection material made to achieve the above-mentioned object is an oil leakage detection material comprising a colored layer colored with a predetermined color and having oil absorption properties, a white layer having oil absorption properties and arranged in contact with at least a part of the upper surface of the colored layer, the white layer having white particles or white powder contained in or attached to a transparent resin layer, a protective layer made of a transparent hydrophobic resin arranged to cover the upper surface of the white layer, and an oil absorption layer arranged on the lower surface side of the colored layer, which has oil absorption and oil retention properties and is formed of a material having water repellency or has been subjected to a water repellent treatment, wherein the colored layer and the white layer are sandwiched between the protective layer and the oil absorption layer so as to prevent water from penetrating into the colored layer and the white layer, and when leaked oil or leaked oil and water come into contact with at least a part of the surface of the oil absorption layer, only the leaked oil is absorbed by the oil absorption layer and penetrates into the colored layer and the white layer, the white layer becomes transparent or semi-transparent, and the hue of the colored layer can be visually observed through the protective layer.

[0008] It is preferable that a part of the peripheral surface of the oil absorbing layer is formed as an exposed surface so as to be in direct contact with the leaking oil or with water, so that the leaking oil can be detected promptly.

[0009] The oil absorbing layer is preferably made of a hydrophobic synthetic resin fiber and is a fabric exhibiting water repellency, which can enhance oil retention.

[0010] The oil absorbing layer and the colored layer are bonded together via a lipophilic first hydrophobic adhesive layer, and the colored layer and the white layer are sandwiched between the protective layer and the first hydrophobic adhesive layer, thereby enabling the oil absorbing layer and the colored layer to be reliably bonded together without any gaps.

[0011] The protective layer and the white layer are joined via a transparent second hydrophobic adhesive layer, and the white layer and the colored layer are sandwiched between the second hydrophobic adhesive layer and the oil-absorbing layer, so that the side surfaces of the white layer and the colored layer and the upper surface of the white layer can be reliably covered by the second hydrophobic adhesive layer, which is preferable.

[0012] It is preferable that the colored layer is any color selected from black, navy blue, red, orange, blue, green, brown, and purple, since this makes the difference from the white color of the white layer clear.

[0013] It is preferable that the colored layer and / or the white layer are shaped in the shape of letters, symbols, and / or graphics, or the colored layer is printed in the shape of letters, symbols, and / or graphics, since these shapes can be made to appear or disappear in the event of oil leakage.

[0014] Since the difference in refractive index between the white particles or white powder and the leaking oil to be detected is 0.1 or less, when the leaking oil to be detected penetrates the white layer, the white layer becomes sufficiently transparent so that the hue of the colored layer can be reliably observed with the naked eye, which is preferable.

[0015] The white particles or white powder are preferably selected from organic compounds, plastic powders, metal salts, glass beads and glass fillers. Effect of the Invention

[0016] According to the present invention, the white layer and the colored layer of the oil leakage detection material are covered with a protective layer made of a transparent hydrophobic resin and an oil absorbing layer that has oil absorption and oil retention properties and is formed of a material with water repellency or has been treated with water repellency, making them waterproof, and even if the oil leakage detection material gets wet with water such as rainwater, the water does not penetrate the oil absorbing layer, the white layer, and the colored layer, preventing misidentification caused by the white layer becoming transparent when wet with water. Furthermore, since the oil absorbing layer also has water repellency, it does not absorb water such as rainwater, and oil leakage can be detected even if the oil leakage detection material is wet with water. This oil absorbing layer has oil retention properties and can hold the leaked oil that penetrates the colored layer and the white layer, allowing reliable detection of oil leakage. In addition, the white particles or white powder of the white layer can be selected to be optimal in relation to the refractive index of the oil that is the subject of oil leakage detection. [Brief description of the drawings]

[0017] [Figure 1] 1A and 1B are a front view and a cross-sectional view of an example of an oil leakage detection material to which the present invention is applied. [Diagram 2] 2 is a front view of the oil leakage detection material of FIG. 1 when leaked oil is absorbed by the oil absorbing layer of the oil leakage detection material. FIG. [Diagram 3] FIG. 11 is a cross-sectional view of another example of an oil leakage detection material to which the present invention is applied. [Figure 4] FIG. 11 is a cross-sectional view of another example of an oil leakage detection material to which the present invention is applied. [Diagram 5] FIG. 11 is a front view of another example of an oil leakage detection material to which the present invention is applied. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] A front view of an example of an oil leakage detection material to which the present invention is applied is shown in Fig. 1(a), and a cross-sectional view of the material at the XX cross section is shown in Fig. 1(b). The oil leakage detection material 10 shown in Fig. 1 is rectangular as shown in Fig. 1(a), and includes a rectangular colored layer 16 colored with a predetermined color, a rectangular white layer 14 having approximately the same size as the colored layer 16 and provided in close contact with the upper surface of the colored layer 16, a protective layer 12 larger than the colored layer 16 and the white layer 14 and provided so as to cover the upper surface of the white layer 14, an oil absorbing layer 18 bonded to the lower surface of the colored layer 16 via a first hydrophobic adhesive layer 20, and a release paper 24 bonded to the lower surface of the oil absorbing layer 18 via an adhesive layer 22 for release paper, and the white layer 14 and the colored layer 16 are sandwiched between the protective layer 18 and the first hydrophobic adhesive layer 20.

[0019] The colored layer 16 may be made of a material having oil absorption properties, such as paper, nonwoven fabric, woven fabric, porous inorganic material such as porous cement, porous ceramics, porous metal, foamed plastic, or ink coating. These materials are colored in a predetermined color. The coloring is preferably done with a coloring agent such as a pigment, dye, or a mixture thereof that is resistant to fading in sunlight and has excellent light resistance, and a hue that is clearly contrasted with white and is easily recognized by the naked eye or an image sensor, among which any of chromatic colors such as black, navy blue, red, orange, blue, green, brown, and purple, is more preferable. Black and navy blue are prone to change in brightness and may be mistaken for a shadow, so red, which is a dangerous color due to changes in saturation, is more preferable because it is practical. The coloring may be applied to the material constituting the oil-absorbent material, or to a material molded into a predetermined shape. The colored layer 16 preferably has a thickness of 1 to 150 μm.

[0020] A rectangular white layer 14 having approximately the same size as the colored layer 16 is provided on the upper surface of the colored layer 16 in close contact with the upper surface of the colored layer 16. In the white layer 14, white particles or white powder are contained in an oil-absorbing transparent resin layer. When leaked oil penetrates the white layer 14, it becomes transparent or translucent. This phenomenon occurs because light that has passed through the leaked oil can pass through the white layer 14 without being significantly bent at the boundary with the white powder or white particles.

[0021] Examples of such white powders or white particles include organic compound powders or particles such as fatty acid derivatives, alcohol derivatives, ether derivatives, aldehyde derivatives, ketone derivatives, amine derivatives, amide derivatives, nitrile derivatives, hydrocarbon derivatives, thiol derivatives, and sulfide derivatives; polyvinyl chloride, polyethylene, polypropylene, polystyrene, acrylonitrile-butadiene-styrene, acrylonitrile-styrene, polymethyl methacrylic, polyvinyl alcohol, polyvinylidene chloride, polyethylene terephthalate, polyamide, polyacetal, polycarbonate, polyphenylene ether, poly(vinyl chloride), poly(vinyl alcohol), poly(vinylidene chloride), poly(vinyl ... Examples of the resin include plastic powders or particles such as butylene terephthalate, polyvinylidene fluoride, polysulfone, polyethersulfone, polyphenylene sulfide, polyarylate, polyamideimide, polyetherimide, polyetheretherketone, polyimide, liquid crystal polymer, polytetrafluoroethylene, phenol resin, urea resin, melamine resin, unsaturated polyester, epoxy resin, silicone resin, and polyurethane; alkaline earth metal salts such as magnesium carbonate and calcium carbonate; metal salt powders or particles such as aluminum hydroxide and talc; glass beads; and glass fillers.

[0022] It is preferable to select such white powder or white particle so that the difference in refractive index between the oil to be detected as the leak detection target is 0.1 or less. The oil to be detected as the leak detection target is a hydrophobic oil obtained from minerals such as petroleum, animals, and plants, floats on water, is liquid at room temperature, and has 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 the leak detection target, the white powder or white particle is preferably 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), or glass filler (refractive index 1.50 to 1.58). These white powders or white particles may be used alone or in a mixture of two or three types. The particle size of the white powder or white particles is preferably 20 μm or less, and particularly preferably 10 μm or less, since it enhances the light scattering effect and increases the whiteness of the white layer 14. The particle size of the white powder or white particles was measured with a grind meter.

[0023] The white layer 14 shown in Fig. 1 is formed by dispersing white powder or white particles in an oil-absorbing transparent resin layer. The transparent resin is an oil-philic transparent resin, such as a cellulose-based resin, a polyester-based resin, an acrylic-based resin, a urethane-based resin, or a synthetic rubber-based resin. In particular, a cellulose-based resin (e.g., ethyl cellulose) or a polyester-based resin is preferred. The amount of the white powder or white particles to be mixed with the transparent resin is preferably 0.5 to 15 times the mass of the transparent resin.

[0024] The thickness of the white layer 14 is preferably 1 μm or more, since this makes the white layer 14 sufficiently opaque. The upper limit of the white layer 14 is preferably 260 μm or less in relation to the flexibility of the oil leak detection material 10. The white layer 14 may be a lipophilic transparent resin layer of a predetermined thickness, on either one or both sides of which white powder or white particles are applied directly or via an adhesive layer.

[0025] The protective layer 12 is larger than the colored layer 16 and the white layer 14, and the upper surface of the white layer 14 and the side surfaces of the colored layer 16 and the white layer 14 are covered with the protective layer 12. The protective layer 12 is formed of a transparent hydrophobic resin. Examples of the transparent hydrophobic resin include cellulose, cellulose derivatives, polyolefin, polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, polyester, polystyrene, rubber hydrochloride, polyamide, fluororesin, polybutene, polyvinyl butyral, polyethylene oxide, polyurethane, cellulose acetate butyrate, hydroxyethyl cellulose, and polyimide.

[0026] The colored layer 16 has an oil-absorbing layer 18 bonded to its underside via a first hydrophobic adhesive layer 20. The oil-absorbing layer 18 is larger than the colored layer 16 and the white layer 14, has oil absorption and oil retention properties, and is formed from a material having water repellency or has been treated to have water repellency. As the oil-absorbing layer 18, fabrics such as nonwoven fabrics and woven fabrics that are made of hydrophobic synthetic resin fibers and exhibit water repellency can be preferably used because they have an oil-retentive property that can hold the absorbed oil between the fibers. Examples of hydrophobic synthetic resin fibers include polypropylene fibers and polyethylene fibers. Synthetic resin fibers such as nylon fibers, natural fibers, and semi-synthetic fibers such as acetate can also be used, but since they are hydrophilic, they can be used by subjecting the fibers or fabrics to a water-repellent treatment. Silicone-based water-repellent agents and fluorine-based water-repellent agents are known as water-repellent agents, and since fluorine-based treatment agents have both water repellency and oil repellency, silicone-based water-repellent agents can be preferably used. The oil-absorbing layer 18 may be a high-density polyethylene nonwoven fabric (Tyvek 1056DR (product name) manufactured by Asahi DuPont Flash Spun Products, Inc., with a basis weight of 54 g / m 2 ) can be preferably used.

[0027] In the oil leak detection material 10 shown in Fig. 1, the lower surface of the colored layer 16 and the upper surface of the oil absorbing layer 18 are joined via a lipophilic first hydrophobic adhesive layer 20. Since the first hydrophobic adhesive layer 20 is lipophilic, the oil absorbed in the oil absorbing layer 18 can permeate into the colored layer 16. Examples of adhesives that form such a first hydrophobic adhesive layer 20 include rubber-based adhesives, acrylic-based adhesives, silicone-based adhesives, polyvinyl-based adhesives, polyurethane-based adhesives, and composite adhesives thereof.

[0028] At least a part of the oil absorbing layer 18 of the oil leakage detection material 10, for example, the side surface of the oil absorbing layer 18 as shown in FIG. 1(b), is preferably formed on the exposed surface, so that the leaked oil can directly contact the oil absorbing layer 18, and the leaked oil can be rapidly absorbed by the oil absorbing layer 18 and can penetrate the colored layer 16 and the white layer 14. In the oil leakage detection material 10 shown in FIG. 1, the lower surface of the oil absorbing layer 18 is covered with a release paper 24 via an adhesive layer 22 for the release paper. By peeling off the release paper 24, the oil leakage detection material 10 can be attached to an object to be detected for oil leakage, such as a flange, via the adhesive layer 22 for the release paper. The adhesive layer 22 for the release paper is also formed of an adhesive that is lipophilic and hydrophobic, so that the leaked oil can penetrate from the adhesive layer 22 for the release paper into the oil absorbing layer 18. In addition, it is preferable that the adhesive layer 22 for the release paper is also formed from the same lipophilic and hydrophobic adhesive as the first hydrophobic adhesive layer 20, 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.

[0029] 1 is obtained by forming an oil-philic first hydrophobic adhesive layer 20 on one side of an oil-absorbing layer 18, forming a release adhesive layer 22 on the other side of the oil-absorbing layer 18, laminating a colored layer 16 and a white layer 14 on the first hydrophobic adhesive layer 20, and then covering the top surface of the white layer 14 and the side surfaces of the colored layer 16 and the white layer 14 with a transparent protective layer 12. Thereafter, the oil leak detection material 10 can be obtained by adhering a release paper 24 to the release paper adhesive layer 22.

[0030] The oil leak detection material 10 shown in Fig. 1 can be attached to a predetermined location of a flange or the like that is the object of oil leak detection by peeling off the release paper 24 and pressing the release paper adhesive layer 22 that is exposed. When the attached oil leak detection material 10 is not in contact with water or leaked oil, only the white color of the white layer 14 can be seen from the protective layer 12 as shown in Fig. 1(a), and the hue of the colored layer 16 cannot be seen. This is presumably because there is a large difference in refractive index between the white particles or white powder dispersed in the white layer 14 and the air in the minute space surrounding the white particles or white powder, and the light that has passed through the white layer 14 is largely bent and dispersed at the boundary between the white particles or white powder and the minute space.

[0031] On the other hand, when leaked oil comes into contact with the attached oil leakage detection material 10, the first hydrophobic adhesive layer 20 and the oil absorbing layer 18 are lipophilic, and the leaked oil penetrates the oil absorbing layer 18 and the first hydrophobic adhesive layer 20 from the exposed surface of the side of the oil absorbing layer 18, and also penetrates the colored layer 16 and the white layer 14. When the leaked oil penetrates the white layer 14, the white layer 14 becomes transparent or semi-transparent, and the hue of the colored layer 16 can be visually confirmed as shown in FIG. 2. The refractive index difference between the leaked oil that penetrates the white layer 14 by capillary action or the like and fills the microspace 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, and it is presumed that the light that has passed through the white layer 14 can pass through without being significantly bent at the boundary between the white particles or white powder and the leaked oil in the microspace. For this reason, it is preferable to select the white powder or white particles so that the refractive index difference with the oil to be detected for leaking oil is 0.1 or less.

[0032] In addition, even if water such as rainwater comes into contact with the attached oil leak detection material 10, the protective layer 12, the first hydrophobic adhesive layer 20, and the oil absorbing layer 18 are hydrophobic or water repellent, so that the water cannot penetrate into the colored layer 16 and the white layer 14 surrounded by these, and discoloration due to water penetration into the colored layer 16 and the white layer 14 can be avoided. In addition, even if water does not penetrate into the protective layer 12, the first hydrophobic adhesive layer 20, and the oil absorbing layer 18 and the surface of the oil leak detection material 10 is wet, when leaked oil comes into contact with the exposed surface of the side of the oil absorbing layer 18, the leaked oil is immediately absorbed into the oil absorbing layer 18, and the white layer 14 becomes transparent or semi-transparent, so that the hue of the colored layer 16 can be visually confirmed from the protective layer 12. Even if leaked oil and water come into contact with the exposed surface of the side surface of the oil absorbing layer 18 at the same time, only the leaked oil is selectively absorbed by the oil absorbing layer 18.

[0033] Even if oil leaks from the underside of the release paper adhesive layer 22 that attaches the oil leak detection material 10 shown in Fig. 1 to a flange or the like, by forming the release paper adhesive layer 22 with a hydrophobic and lipophilic adhesive, the leaked oil is absorbed into the oil absorbing layer 18 via the release paper adhesive layer 22. The leaked oil absorbed in the oil absorbing layer 18 in this way is retained within the oil absorbing layer 18, so that the oil leaked from the flange or the like can be prevented from immediately flowing out onto the ground or the like.

[0034] In the oil leakage detection material 10 shown in Figures 1 and 2, the colored layer 16 and the white layer 14 are bonded to the oil absorbing layer 18 via the first hydrophobic adhesive layer 20, and the upper surface of the white layer 14 and the side surfaces of the white layer 14 and the colored layer 16 are covered by the protective layer 12, but as shown in Figure 3, the white layer 14 and the colored layer 16 may be directly placed on one surface of the protective layer 12, and the protective layer 12 may be bonded to the upper surface of the white layer 14 and the side surfaces of the white layer 14 and the colored layer 16 via a lipophilic second hydrophobic adhesive layer 26. The second hydrophobic adhesive layer 26 is preferably formed of a hydrophobic adhesive, and examples of the adhesive include a rubber-based adhesive, an acrylic-based adhesive, a silicone-based adhesive, a polyvinyl-based adhesive, a polyurethane-based adhesive, and a composite adhesive thereof.

[0035] 4, the white layer 14 and the colored layer 16 may be placed directly on one surface of the protective layer 12, and the upper surface of the white layer 14 and the side surfaces of the white layer 14 and the colored layer 16 may be directly covered by the protective layer 12. Furthermore, the colored layer 16 and the white layer 14 of the oil leakage detection material 10 shown in FIGS. 1 and 2 are rectangular, but they may be circular as shown in FIG. 5. When the oil leakage detection material 10 is not in contact with leaked oil, the hue of the colored layer 16 cannot be seen from the protective layer 12 due to the white layer 14 as shown in FIG. 5(a), but when the oil leakage detection material 10 comes into contact with leaked oil, the white layer 14 becomes transparent or semi-transparent, and the hue of the colored layer 16 can be seen from the protective layer 12 as shown in FIG. 5(b). The shapes of the white layer 14 and the colored layer 16 can be any shape, such as letters, symbols, etc., in addition to various shapes such as a rectangle or a circle. For example, the white layer 14 itself can be shaped like letters indicating oil leakage, such as "oil," so that the letters are raised and displayed by the oil leakage, or conversely, the white layer 14 can be designed to be invisible, or the colored layer 16 can be shaped like letters or symbols, etc., so that they can be displayed or hidden. For example, taking the case where the colored layer 16 itself is shaped like letters indicating oil leakage, when there is no oil leakage, the letters are hidden by the white layer 14 and do not appear, but when there is oil leakage, the white layer 14 becomes transparent or semi-transparent and the letters of the colored layer 16 appear and are visually recognized as if they are floating above the protective layer 12. On the other hand, taking the case where the white layer 14 itself is shaped like letters indicating oil leakage, when there is no oil leakage, the colored layer 16 is visible in the non-letter-shaped parts of the white layer 14 and the letter shapes hide the colored layer 16, so that the letters appear visually recognized, but when oil leaks, the white layer 14 becomes transparent or semi-transparent and no longer hides the colored layer 16, so that the letter shapes become invisible and appear not to be displayed.

[0036] 1 to 5, the oil leak detection material 10 can be easily attached to locations such as flanges where oil leakage is likely, and can reliably detect the presence of an oil leak only when only leaked oil or a mixture of water and leaked oil containing water and leaked oil comes into contact with the oil leak detection material 10. In addition, the leaked oil can be temporarily retained within the oil absorption layer 18, and the leaked oil can be prevented from immediately flowing out onto the ground, etc. EXAMPLES

[0037] Examples of the present invention will be described in detail below, but the scope of the present invention is not limited to these examples.

[0038] Example 1 The oil leakage detection material 10 shown in FIG. 1 was produced. First, 30 parts by mass of stearic acid (refractive index 1.43) as a white powder, 5 parts by mass of transparent ethyl cellulose resin, and 65 parts by mass of xylene were kneaded together to produce a white ink. This white ink was applied to one side of a black-colored wood-free paper as the colored layer 16 with a coater applicator to a coating thickness of 150 μm, and then dried to form a white layer 14. Next, the substrate with the white layer 14 formed on one side of the colored layer 16 was cut into a 40 mm×40 mm square. In addition, a polyethylene nonwoven fabric (Tyvek 1056DR (product name) manufactured by Asahi DuPont Flash Spun Products Co., Ltd., basis weight 54 g / m) was used as the oil absorbing layer 18. 2An oil-permeable acrylic adhesive was applied to both sides of the sheet to form a first hydrophobic adhesive layer 20 and an adhesive layer 22 for release paper, and the sheet was then cut into a square of 50 mm x 50 mm. The cut colored layer 16 was attached to the center of the cut first hydrophobic adhesive layer 20 so that the white layer 14 was on the upper surface. Furthermore, a 50 mm x 50 mm transparent polyethylene terephthalate film was attached as a protective layer 12 so as to cover the upper surface of the white layer 14 and the side surfaces of the white layer 14 and the colored layer 16. Thereafter, a 50 mm × 50 mm release paper 24 was attached to the release paper adhesive layer 22 to obtain the oil leak detection material 10 shown in Figure 1. In the obtained oil leak detection material 10, the hue of the colored layer 16 cannot be seen from the protective layer 12 due to the opaque white layer 14.

[0039] Comparative Example 1 According to Example 1 described in Japanese Patent No. 6609085, a type A white ink was prepared. 18 parts by mass of talc (refractive index 1.54) as a white powder and 25 parts by mass of a medium containing 8% ethyl cellulose as a transparent resin solution were mixed to prepare a type A white ink. This white ink was applied to one side of a black-colored polypropylene nonwoven fabric as a colored layer with a coating thickness of 200 μm using a coater applicator, and then dried. A fluororesin coating agent was further applied to the upper surface of the white ink and then dried to form a transparent protective layer. An acrylic adhesive was attached to the other side of the colored layer as an adhesive layer, and the material was cut to 50 mm x 50 mm to obtain an oil leakage detection material. In the prepared oil leakage detection material, the hue of the colored layer cannot be seen from the protective layer due to the opaque white layer.

[0040] Example 2 The oil leakage detection material 10 obtained in Example 1 and the oil leakage detection material obtained in Comparative Example 1 were each attached to an aluminum plate to prepare a test specimen. The color density of the white layer visible through the protective layer of this test specimen was measured. This test specimen was immersed in a tray containing water (refractive index 1.33), silicone oil (refractive index 1.44), or hydraulic oil (refractive index 1.5) for 2 hours, and then the color density of the white layer visible through the protective layer was measured. The color density was measured using a densitometer (trade name x-rite 504, manufactured by X-Rite, Inc.) to measure the visual density of the shades. In addition, the color density of the colored layer itself was measured. The measurement results are shown in Table 1 below.

[0041] [Table 1]

[0042] As is clear from Table 1, the oil leakage detection material of Example 1 had no difference in color density of the white layer before wetting and after wetting with water, and was not affected by wetting with water. In addition, the color density of the white layer after wetting with silicone oil and the color density of the white layer after wetting with hydraulic oil increased significantly, and the color changed clearly with silicone oil and hydraulic oil, so that oil wetting could be visually confirmed. On the other hand, in the oil leakage detection material of Comparative Example 1, the color density of the white layer after wetting with water increased compared to the color density of the white layer before wetting, making it easy to mistake it for oil wetting. Also, the color density of the white layer after wetting with silicone oil was smaller than the color density of the colored layer itself, and was closer to the color density of the white layer after wetting with water, making it difficult to determine whether it was oil wetting or not. [Industrial Applicability]

[0043] The oil leakage detection material of the present invention does not discolor due to rainwater alone, and can reliably detect oil leakage even from silicone oil, which has a refractive index close to that of water, and can detect oil leakage from various oil tanks, piping flanges, etc. [Explanation of symbols]

[0044] 10: Oil leakage detection material, 12: Protective layer, 14: White layer, 16: Coloring layer, 18: Oil absorption layer, 20: First hydrophobic adhesive layer, 22: Adhesive layer for release paper, 24: Release paper, 26: Second hydrophobic adhesive layer

Claims

1. An oil leakage detection material comprising: a colored layer colored with a predetermined color and having oil absorption properties; a white layer having oil absorption properties, which is provided in contact with at least a part of the upper surface of the colored layer and in which white particles or white powder is contained or 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 surface side of the colored layer, which has oil absorption and oil retention properties and is formed of a material having water repellency or has been subjected to a water repellency treatment, the colored layer and the white layer are sandwiched between the protective layer and the oil absorbing layer so as to prevent water from penetrating into the colored layer and the white layer, This oil leakage detection material is characterized in that when leaking oil or leaking oil and water come into contact with at least a portion of the surface of the oil absorption layer, only the leaking oil is absorbed by the oil absorption layer and penetrates into the colored layer and the white layer, the white layer becomes transparent or translucent, and the hue of the colored layer can be visually observed through the protective layer.

2. 2. The oil leakage detection material according to claim 1, wherein a part of the peripheral surface of the oil absorbing layer is formed as an exposed surface so as to come into direct contact with the leaked oil or with water.

3. 2. The oil leakage detector according to claim 1, wherein the oil absorbing layer is made of hydrophobic synthetic resin fibers and is a fabric exhibiting water repellency.

4. The oil leakage detection material described in claim 1, characterized in that the oil absorption layer and the colored layer are joined via an oil-philic first hydrophobic adhesive layer, and the colored layer and the white layer are sandwiched between the protective layer and the first hydrophobic adhesive layer.

5. The oil leak detection material described in claim 1, characterized in that the protective layer and the white layer are joined via a transparent second hydrophobic adhesive layer, and the white layer and the colored layer are sandwiched between the second hydrophobic adhesive layer and the oil absorbing layer.

6. 2. The oil leakage detector according to claim 1, wherein the colored layer is any color selected from the group consisting of black, navy blue, red, orange, blue, green, brown, and purple.

7. The oil leakage detection material as described in claim 1, characterized in that the colored layer and / or the white layer are shaped in the shape of letters, symbols, and / or graphics, or the colored layer is printed in the shape of letters, symbols, and / or graphics.

8. 2. The oil leakage detection material according to claim 1, wherein the difference in refractive index between the white particles or white powder and the leakage oil to be detected is 0.1 or less.

9. 2. The oil leakage detection material according to claim 1, wherein the white particles or white powder is selected from the group consisting of organic compounds, plastic powders, metal salts, glass beads and glass fillers.

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