JP7292617B2 - Crack detection label - Google Patents

Description

TECHNICAL FIELD The present invention relates to a crack detection label capable of reliably detecting cracks occurring in concrete structures and the like.

Concrete is widely used in structures such as bridges and tunnels on automobile roads and railways, but it is known that these concrete cracks occur due to the effects of temperature, humidity, and external force when used for a long time. . Leaving cracks in the concrete unattended can lead to serious accidents, such as the delamination of walls and the progress of corrosion of internal reinforcing bars, so regular inspections and management are necessary.

As a means for crack inspection, for example, in Patent Document 1, a structure in which a specular reflection layer, a glass sphere layer, and a retention layer are laminated on an adhesive layer is attached to a concrete structure via the adhesive layer, and when a crack occurs, By using the uneven spacing of the glass beads or the breakage of the adhesive layer, strong reflected light can be confirmed by the specular reflection layer and the glass beads in the non-cracked areas, but this reflection is weakened in the cracked areas. , a crack detection sheet has been proposed that enables the occurrence of cracks to be confirmed by visual confirmation.

In addition, in Patent Document 2, a fiber-containing plastic plate in which sheet-like fibers are impregnated with a matrix resin is attached to the surface of concrete, and the whitening phenomenon of the plastic plate due to the elongation of the tensile stress of cracks is used to determine the whitened area and cracks. A crack sensor has been proposed that allows visual confirmation of crack conditions by matching the degree of .

On the other hand, in Patent Document 3, a wireless tag having an antenna is attached to an object to be detected, and the antenna is disconnected due to a crack in the object to be detected. has been proposed.

JP 2016-218049 A Japanese Unexamined Patent Application Publication No. 2012-93260 Japanese Patent Application Laid-Open No. 2005-30811

According to the methods disclosed in Patent Documents 1 and 2, when it is desired to detect minute cracks, there is a possibility that the minute cracks may be overlooked due to differences in the ability of inspectors and individual differences in judgment. In addition, it is technically not easy to manufacture the detection sheet or sensor without variations corresponding to the amount of cracks to be detected, and there is a problem that it is difficult to obtain an inexpensive and highly accurate one.

Further, Patent Document 3 detects the presence or absence of cracks based on the presence or absence of disconnection of the antenna of the wireless tag. There is no description as to whether or not the type of deterioration detection device can be selected for reliable disconnection detection according to the difference in crack level to be detected. Preparing a plurality of types of deterioration detection devices with different properties, etc., requires high design and manufacturing costs.

The present disclosure has been made in view of such circumstances, and it is an object of the present disclosure to provide an inexpensive crack detection label that can reliably visually detect the presence or absence of a desired crack to be detected.

The present disclosure is a label for detecting cracks that occur on the surface of an inspection object, comprising: a resin substrate; An adhesive layer provided on the other surface of the resin base material and used to adhere the resin base material to the inspection object. and are laminated in this order.

Further, the rupture layer may be colored in a color different from that of the resin substrate, or the rupture layer may contain a phosphorescent pigment or a pearl pigment.

Further, the resin base material and the rupture layer may be transparent or translucent, or may have a visible light transmittance of 30 from the surface of the rupture layer to the adhesion surface of the adhesive layer. % or more.

Further, it may be characterized by further comprising a rupture indication layer that ruptures together with the rupture layer on the surface of the rupture layer opposite to the resin base material, and the rupture indication layer is provided with the resin base material. may be characterized by printed layers colored in different colors, or said printed layers may be characterized by comprising phosphorescent pigments or pearlescent pigments.

Further, the breakage indicating layer may be a layer in which a metal deposition layer or a metal foil is layered or laminated. Further, the rupture layer may be characterized by containing an ultraviolet-curing acrylic-modified polyester resin, or the rupture layer may be characterized by containing a polyethylene-based wax.

Further, it may be characterized in that a cut with a constant depth is formed in the stacking direction including the fracture layer, and the cut may be characterized in that it is formed in an intermittent line, or , the notch may be formed in a half-cut state.

In the present disclosure, an adhesive layer is provided on one side of the resin base material to be attached to the test object, and the opposite side is provided with a breaking layer that breaks before the resin base material due to a tensile force in the surface direction. By using an inexpensive crack detection label, it is possible to reliably visually detect the presence or absence of a desired crack to be detected.

It is a sectional view explaining the structure of the label for crack detection of a 1st embodiment. It is sectional drawing which stuck the label for crack detection of 1st Embodiment to the test object. FIG. 2 is a plan view of a plurality of crack detection labels of the first embodiment attached to an inspection object; FIG. 5 is a cross-sectional view illustrating the structure of a crack detection label according to a second embodiment; FIG. 10 is a cross-sectional view of the crack detection label of the third embodiment attached to an inspection object; FIG. 11 is a cross-sectional view illustrating the structure of a crack detection label according to a fourth embodiment; FIG. 14 is a perspective view showing a state in which the crack detection label of the fifth embodiment is attached to an inspection object; FIG. 14 is a perspective view showing a state in which the crack detection label of the sixth embodiment is attached to an inspection object;

An example of the crack detection label of the present disclosure will be described below with reference to drawings and the like. However, the crack detection label of the present disclosure is not limited to the embodiments and examples described below.

In addition, each figure shown below is shown typically. Therefore, the size and shape of each part are appropriately exaggerated for easy understanding. In each figure, hatching indicating cross sections of members is omitted as appropriate. Numerical values such as dimensions and material names of each member described in this specification are examples as an embodiment, and are not limited to these, and can be appropriately selected and used. In this specification, terms specifying shapes and geometrical conditions, such as parallel, orthogonal, perpendicular, etc., not only have strict meanings but also include substantially the same states.

1. First Embodiment A first embodiment of the crack detection label of the present disclosure will be described. FIG. 1 is a cross-sectional view showing an example of the crack detection label of the first embodiment. FIG. 1(a) is a cross-sectional view of the crack detection label 100, FIG. 1(b) is a detailed cross-sectional view of only the fracture layer 1 of FIG. 1(a), and FIG. FIG. 1(a) is a cross-sectional view of a separator-attached crack detection label 100A in which a separator 6 is provided on the surface of the adhesive layer 5 of the crack detection label 100 opposite to the primer layer 4 and the resin base material 3. is.

As shown in FIG. 1(a), the crack detection label 100 has a laminated structure in which an adhesive layer 5, a primer layer 4, a resin base material 3, a primer layer 2 and a breaking layer 1 are laminated in this order from the lower layer side. have.

(a) Adhesive layer The adhesive layer 5 adheres the above-described crack detection label 100 to the surface of the concrete structure or the like to be inspected in the present disclosure, and when the concrete structure or the like cracks, and When a precursory state of a crack is confirmed by a strike inspection, the crack detection label 100 attached across the cracked portion and the precursory confirmation portion is extended to a predetermined length following the crack and the breakage of the precursory confirmation portion. It is required to have a predetermined adhesive strength so that it can be stretched by a certain amount. As such an adhesive layer, various materials used for general labels can be used, for example, natural rubber adhesive, synthetic rubber adhesive, silicone resin adhesive, urethane resin adhesive, acrylic resin adhesive. agents and the like can be used.

Synthetic rubber adhesives include, for example, isoprene rubber, isobutylene-isoprene rubber, polyisobutylene rubber, styrene-butadiene rubber, styrene-isoprene block copolymer, styrene-butadiene block copolymer, styrene-ethylene-butylene block copolymer. Polymers, ethylene-vinyl acetate copolymers, and the like can be used. A siloxane polymer, for example, can be used as the silicone resin-based pressure-sensitive adhesive. Examples of acrylic resin adhesives include polymers such as acrylic acid, methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, and acrylonitrile. Polymers and the like can be used. Moreover, these adhesives can also be used in combination of 2 or more types.

The adhesive layer 5 may contain a tackifier, a filler, a softening agent, an anti-aging agent, or a coloring agent such as a dye or pigment, if necessary. Examples of tackifiers include rosin-based resins, terpene-based resins, phenol-based resins, and xylene-based resins. Fillers include silica, talc, calcium carbonate, clay and the like. A plasticizer etc. are mentioned as a softening agent.

The thickness of the adhesive layer 5 is not particularly limited, but even if the surface of the concrete structure to be inspected has some unevenness, the crack detection label 100 can be adhered and the deformation at the time of cracking can be correctly transmitted. It is necessary to have an appropriate thickness for the thickness, for example 0.01 to 5.0 mm, preferably 0.02 to 0.05 mm. If the thickness is in the range of 0.01 to 5.0 mm, the thickness should be made thinner in order to increase the sensitivity of crack propagation in the structure, etc., and the thickness should be made thicker if the surface of the structure, etc. has large unevenness. By appropriately selecting the thickness within this range, appropriate crack detection can be performed. Furthermore, if the thickness is in the range of 0.02 to 0.05 mm, crack detection can be performed under conditions that both improve the sensitivity of transmission of cracks in structures, etc., and follow the unevenness of the surface of structures, etc. can be done. The adhesive layer 5 may be colored or transparent, that is, permeable to visible light.

(b) Resin Base Material As shown in FIG. 1(a), the resin base material 3 is laminated on the adhesive layer 5 with the primer layer 4 interposed therebetween. The resin base material 3 is required to expand according to the elongation of the adhesive layer 5 described above, following deformation due to cracks in the concrete structure to be inspected, and to be elastically deformed by a predetermined length. The predetermined length is the length of elongation of the crack detection label assumed due to the crack, and is about 0.1 to 10 mm when the length of the crack detection label is about 20 to 200 mm. As a result, the fracture layer 1, which will be described later, has the property of breaking before the resin base material 3 as the crack progresses in the structure, so that the crack state of the structure or the like can be detected on the outermost surface of the crack detection label. It can be reliably displayed on a certain fracture layer 1. - 特許庁If the resin base material 3 has the property of breaking before the breaking layer 1, the deformation transmitted to the adhesive 5 due to cracks in the structure etc. will break the resin base material 3 as the intermediate layer. For example, if the resin substrate 3 and the fracture layer 1 are separated or broken at the interface, the fracture layer 1 on the outermost surface may not display the cracked state correctly. It is important that the material 3 can follow a predetermined elastic deformation.

Various resins can be used as the material having such a predetermined elastic deformation property. For example, polyethylene film, polypropylene film, polyethylene fluoride film, polyvinylidene fluoride film, polyvinyl chloride film, polyvinylidene chloride film, ethene-vinyl alcohol film, polyvinyl alcohol film, polymethyl methacrylate film, polyether sulfone film, polyether ether Ketone film, polyamide film, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer film, polyester film such as polyethylene terephthalate film, polyimide film, polyurethane film, urethane resin film such as acrylic modified polyurethane film, acrylonitrile-butadiene-styrene resin film , a polycarbonate resin film, an acetate resin film, or a composite material thereof can be used.

When the fracture layer 1 on the outermost surface of the resin substrate 3 is a member that easily transmits visible light and ultraviolet rays, that is, when it has transparency to visible light and ultraviolet rays, the resin substrate 3 is also exposed to visible light and ultraviolet rays for a long period of time. It is desirable to have as much weather resistance as possible because the base material may deteriorate due to continuous exposure to ultraviolet rays. A polycarbonate resin film or the like can be selected to enhance the weather resistance of the base material itself. Alternatively, an antioxidant or an ultraviolet absorber may be added to the base material. As the UV absorber, various known UV absorbers such as benzophenone-based, triazine-based, benzotriazole-based, acrylonitrile-based, salicylate-based, ultrafine titanium oxide, and ultrafine zinc oxide can be selected. In addition, in order to delay deterioration due to hydrolysis during long-term use, for example, when using a polyester base material that is relatively susceptible to hydrolysis, a known hydrolysis-resistant agent such as a carbodiimide compound may be added.

Although the thickness of the resin base material 3 is not particularly limited, it is desirable that the resin base material 3 has a certain thickness so as not to break due to a predetermined elongation due to cracking. The required thickness is related to the elastic modulus of the member, and is, for example, 0.01 to 3.0 mm, preferably 0.03 to 1.0 mm, more preferably 0.05 to 0.25 mm. If the thickness is 0.01 to 3.0 mm, it is possible to cope with both conditions in which the amount of elongation due to cracking is small and large. If the thickness is 0.03 to 1.0 mm, a thinner member can be selected, which broadens the range of material selection and contributes to reducing the manufacturing cost of the crack detection label. Furthermore, if the thickness is 0.05 to 0.25 mm, the range of selection of these members is further widened. This contributes to shortening the manufacturing delivery date and reducing the manufacturing cost of the crack detection label. The resin base material 3 may be colored or may have transparency.

(c) Primer layer As shown in FIG. 1(a), a primer layer between the resin substrate 3 and the adhesive 5 on the lower layer side, and between the resin substrate 3 and the breaking layer 1 on the upper layer side. 4 and a primer layer 2 are formed. In practice, a liquid primer is applied to two surfaces of the resin base material 3, the surface layer on the adhesive 5 side and the surface layer on the rupture layer 1 side, to form a layer, and the adhesive layer 5 and the rupture layer 1 are laminated on this. ing. The primer layers 4 and 2 are formed to ensure adhesion between the resin base material 3 and the adhesive layer 5 and between the resin base material 3 and the fracture layer 1, respectively. If these are not in close contact with each other, when the structure or the like cracks, the deformation of the crack is not transmitted from the adhesive layer 5 to the resin substrate 3, and the resin substrate 3 peels off from the adhesive layer 5 at the interface. When the resin base material 3 is deformed, the fracture layer 1 may peel off from the resin base material 3 at the interface, and the cracked state of the fracture layer 1 may not be displayed accurately.

The primer layer 4 and the primer layer 2 are not particularly limited as long as they can ensure adhesion between the adhesive layer 5 and the resin base material 3, and between the resin base material 3 and the breaking layer 1. Known acrylic, polyester, Various primers such as polyurethane-based, silicone-based, and rubber-based primers can be selected. As a forming method, any method such as a printing method, a spray coating method, an inkjet method, or the like can be selected on both front and back surfaces of the resin base material 3 . The thickness of the primer layers 2 and 4 is not particularly limited as long as it has a thickness necessary to ensure adhesion, and may be, for example, about 0.1 to 200 μm. The primer layer 2 and the primer layer 4 may be of the same material or may be of different materials. Also, the thicknesses of the primer layer 2 and the primer layer 4 may be the same or different.

In addition, when the adhesive layer 5 and the resin base material 3, or the resin base material 3 and the breaking layer 1 can be adhered without an adhesive, for example, the resin base material 3 is made of an easy-adhesive resin. , When the surface is treated for easy adhesion or when they are closely adhered to each other by a heat press process or the like, either one of the primer layer 2 and the primer layer 4 may be omitted, or the primer layer 2 and the primer Both layers 4 may be absent. The primer layers 2 and 4 may be colored or transparent.

(d) Breaking layer As shown in FIG. 1(a), the breaking layer 1 is laminated via the resin base material 3 and the primer layer 2 on the surface of the resin base material 3 opposite to the adhesive layer 5. . When the crack detection label 100 is attached to the surface of a concrete structure or the like to be inspected, the fracture layer 1 can be visually recognized from the outside as the outermost surface portion of the crack detection label 100. .

The rupture layer 1 elastically deforms to some extent following the elongation deformation caused by the cracking of the resin base material 3 disposed therebelow. Since the amount of elongation that allows elastic deformation of the resin base material 3 is smaller than the amount of elongation that can be elastically deformed, when the crack progresses to a predetermined level and the deformation progresses, the resin base material 3 stretches following this, but the fracture layer above it 1 breaks beyond the elongation limit. If the conditions for breaking are determined in accordance with the degree of cracking to be confirmed, when the breaking layer 1 breaks, the checking person can immediately grasp the degree of cracking.

For example, the elongation of the crack detection label 100 due to cracking is between 0.1 and 0.3 mm, and the crack detection label 100 is manufactured under conditions such that the fracture layer 1 breaks. By doing so, when it is visually confirmed from the outside that the fracture layer 1 is fractured, it is immediately confirmed that cracks have occurred at that location at intervals of 0.1 to 0.3 mm or more. I can grasp it.

In addition, as will be described later, if a plurality of types of crack detection labels with different elongation conditions that cause breakage of the breakable layer 1 are attached side by side to the same expected crack occurrence location, these multiple cracks can be detected. By confirming which rupture layer of the detection label has ruptured, it is possible to accurately narrow down the level of cracks that have actually occurred.

As a material for such a rupture layer 1, in a relative relationship with the resin base material 3, the resin base material 3 does not break with respect to the condition of a predetermined elongation amount, but the rupture layer 1 breaks. It suffices to select one that satisfies the conditions, including its dimensions and thickness. As such a member, the physical properties are clearly different from those of the resin base material 3 described above, and materials that can be laminated relatively easily include, for example, methacrylic resins such as polymethyl methacrylate, trifunctional or higher, preferably hexafunctional or higher ultraviolet rays. Prints a liquid coating solution that dilutes and mixes photopolymerization initiators such as benzophenone, acetophenone, and thioxanthone in epoxy-modified acrylate resin, urethane-modified acrylate resin, acrylic-modified polyester resin, etc. that are cured by ionizing radiation such as electron beams. , die coating, spray coating, ink jetting, or the like. Among them, a polyester acrylate oligomer resin having a high functional group number is preferably selected because it is easy to break as a breaking layer when a predetermined elongation occurs, that is, good breaking aptitude.

Further, an appropriate additive or filler may be added or filled in a predetermined proportion to the aforementioned ionizing radiation-curable resin such as ultraviolet rays or electron beams used for the rupture layer 1 . In particular, wax-based additives such as polypropylene wax, polyethylene wax, paraffin wax, ethylene vinyl acetate wax, and ethylene acrylic acid wax reduce the cohesive strength of the entire fracture layer, making it easier to break when a predetermined elongation occurs. have the effect of improving Among them, polyethylene wax is good in these aptitudes. FIG. 1(b) is an enlarged cross-sectional view of the fracture layer 1 of the crack detection label 100, in which the additive 11 is uniformly dispersed in the resin layer 10. As shown in FIG. In this embodiment, the additive 11 is polyethylene wax. Conversely, inorganic fillers such as silica are poorly dispersible in the ionizing radiation curable resin and adversely affect performance such as rupture susceptibility.

Although the thickness of the fracture layer 1 is not particularly limited, it is desirable to have a thickness necessary for reliable fracture only within a predetermined range of elongation due to cracking. The thickness is also related to the elastic modulus of the member, and is, for example, 0.001 to 1 mm, preferably 0.005 to 0.1 mm, more preferably 0.01 to 0.05 mm. When the thickness is 0.001 to 1 mm, it is possible to meet the conditions for reliable breakage within a predetermined range of elongation under both conditions of small elongation due to cracking and large elongation. If the thickness is 0.005 to 0.1 mm, the rupture layer can be formed with a thinner thickness, and the resin that reliably forms the rupture layer can be cured even if the energy for irradiating ultraviolet rays and electron beams is reduced. Therefore, stable rupture properties can be obtained. Furthermore, if the thickness is 0.01 to 0.05 mm, the resin that forms the rupture layer can be cured more reliably even if the energy for irradiating ultraviolet rays and electron beams is reduced, and more stable rupture characteristics can be obtained. Obtainable. The rupture layer 1 is generally transparent due to its property of being cured by ultraviolet rays and electron beams, but may be colored to the extent that curing by ultraviolet rays and electron beams is not hindered.

The rupture layer 1 itself can be colored in a predetermined color by directly adding a pigment, colorant, dye, or the like of a predetermined color to the above materials used for forming the rupture layer 1 . The details are common to the printed layer 7 of the second embodiment described later, but the coloring of the fracture layer 1 itself is different from the coloring of the resin base material 3 that is visually recognized as the base when the fracture layer 1 is fractured. You may choose a color combination that provides sufficient contrast for the For example, the resin substrate 3 may be colored red and the rupture layer 1 itself may be colored green. It can also be a matte color by itself, or vice versa. In order to ensure the visibility of the fractured state of the fractured layer 1 from a distance, for example, each colored part of the resin base material 3 and the fractured layer 1 itself is defined in 7.1.1 of JIS Z8730 (2009). The color difference ΔE ^* ab in the L ^* a ^* b ^* color system is preferably 25.0 or more.

Moreover, the coloring of the rupture layer 1 itself may contain a phosphorescent pigment, or may contain a pearl pigment contained in pearl ink. The formation method and effects thereof are common to the description of the printed layer 7 of the second embodiment.

(e) Separator The components of the crack detection label 100 of the first embodiment have been described above. It is desirable to attach a separator to maintain the FIG. 1(c) is a cross-sectional view of a crack detection label 100A having a separator 6 attached to the adhesive surface of the adhesive layer 5 of the crack detection label 100 opposite to the resin base material 3. FIG. By attaching the separator 6 to the adhesive layer 5, the adhesive layer 5 is not exposed in the air in the storage state before being attached to the test object, and the adhesive strength can be maintained for a long period of time. The material of the separator is not particularly limited as long as it can adhere to the adhesive layer without hindering the adhesive strength of the adhesive layer. can be used.

(f) Function of crack detection label (1)
Next, the usage and functions of the crack detection label 100 having the layer structure described above will be described.

FIG. 2 is a cross-sectional view showing a state in which the crack detection label 100 is attached to an inspection object such as a concrete structure. First, as shown in FIG. 2( a ), the crack detection label 100 is attached to the surface of the inspection object 20 such as a concrete structure by pressing the surface of the adhesive layer 5 . It is preferable to select a place where the crack is expected to occur first due to concentration of internal stress in a concrete structure, for example, and the crack detection label 100 is attached to the expected crack. It is preferable to stick it in a straddling arrangement.

Moreover, even if a crack is already occurring or has progressed to some extent, the crack detection label 100 can be attached so as to straddle the crack. In this case, when the crack progresses further than the present condition, the breakage layer 1 of the crack detection label 100 is broken according to the progressed crack interval, so that the progress of the predetermined crack can be detected. , the progress of cracks can be clearly grasped.

When the test object 20 receives a tensile force in the horizontal direction of FIG. 2(a), that is, along the X direction, elongation occurs in the elastic deformation range along the X direction. However, if the surface of the inspection object 20 is concrete, this elongation will hardly occur and cracks will occur. When the inspection object 20 extends in the X direction, the adhesive layer 5 of the crack detection label 100, which is in close contact with the inspection object 20, the resin substrate 3 thereabove, and the rupture layer 1 above it are integrally inspected. It stretches following the growth of 20.

Furthermore, when the test object 20 is stretched in the X direction by the tensile force in the X direction, the test object 20 breaks at a certain stage, and as shown in FIG. give rise to At this time, the adhesive layer 5, the resin base material 3, and the fracture layer 1 continue to stretch to some extent following the spread of the cracks 31, but eventually, the fracture layer 1, which has the smallest allowable elongation, stretches. reaches its limit and breaks, forming a broken portion 32 .

Since the fracture portion 32 is formed in the fracture layer 1, which is the outermost surface of the crack detection label 100, an inspector can reliably confirm the fracture by simply visually checking the surface of the crack detection label 100 from the outside. By confirming the fracture of the fault 1 , that is, the fractured portion 32 , it is possible to recognize that the inspection object 20 has a crack. For example, if the rupture layer 1 of the crack detection label 100 is designed to break at an elongation of 0.2 to 0.3 mm, confirm that the rupture layer 1 has broken. Thus, it can be immediately determined that the crack to be inspected has expanded with a width of at least 0.2 mm.

As described above, the crack detection label of the present disclosure does not detect the degree of cracking based on subtle changes in reflectance or whitening degree on the label surface, but rather whether the fracture layer on the label surface is simply broken or not. It is sufficient to confirm only the state change of whether or not there is any cracking, and from the correlation with the limit elongation amount associated with the breaking condition of the attached label, the level of cracks that occurred, that is, the interval between cracks, can be uniquely determined. can be judged. For this reason, the inspector does not require special skills, and errors in grasping the state of cracks due to the inspector's misjudgment or individual differences can be reduced as much as possible.

In addition, the label for detecting cracks of the present disclosure can be exposed to ultraviolet light, which is usually used for forming resin substrates commonly used in magnetic cards and the like, adhesive layers used in ordinary labels, surface protective layers, and the like. , Only by adjusting the layer thickness of the electron beam curable resin and additives, it is possible to easily associate the rupture condition of the rupture layer with the elongation amount of the label, so the manufacturing cost of the crack detection label can be reduced and can be reproduced. Excellent reliability such as durability.

Both the resin substrate 3 and the fracture layer 1 of the crack detection label 100 may be transparent or translucent. Furthermore, the adhesive layer 5 may also be transparent or translucent, or the adhesive layer 5 may be separated into islands and formed at the interface with the resin base material 3 . In this case, visibility is poor when checking the state of the rupture layer 1 to see if the rupture layer 1 is broken due to cracks, but the rupture layer 1, the resin base material 3 and the adhesive layer 5, or through the rupture layer 1. Through the gaps between the resin base material 3 and the adhesive layer 5 arranged in an island shape, the state of cracks in the inspection object 20 can be directly visually recognized, making it possible to confirm the situation more accurately.

In this case, specifically, the total light transmittance defined in JIS K7375 (2008) of each of the resin base material 3 and the breaking layer 1 is preferably 50% or more. Further, in the state in which the adhesive layer 5, the resin base material 3 and the breaking layer 1 are laminated, from the surface of the breaking layer 1 to the sticking surface of the adhesive layer 5 in the direction perpendicular to the surface direction of the breaking layer 1 , the transmittance of visible light having a wavelength of 380 to 780 nm is preferably 30% or more. When the adhesive layer 5 is arranged in an island shape and there are partial gaps, the direction perpendicular to the surface direction of the rupture layer 1 in the state in which the resin base 3 and the rupture layer 1 are laminated It is sufficient that the transmittance of visible light with a wavelength of 380 to 780 nm from the surface of the rupture layer 1 to the interface of the adhesive layer 5 of the resin substrate 3 is 30% or more.

(g) Function of crack detection label (2)
Furthermore, by using a plurality of crack detection labels having different breaking properties, it is possible to grasp the crack level more accurately.

FIG. 3 is a plan view of the crack detection labels 101 and 102 of the present disclosure having different breaking properties applied to an inspection object 20, viewed in a direction perpendicular to the inspection object surface. In FIG. 3A, a crack detection label 101 and a crack detection label 102 having different breaking characteristics are arranged vertically and parallel along the surface of the inspection object 20, in the vertical direction, that is, along the Y direction. affixed. In the crack detection labels 101 and 102, the rupture layer 1, which is the outermost surface, is visible. Incidentally, the crack detection label 101 is ruptured when the elongation of the rupture layer 1 is in the range of 0.2 to 0.3 mm, and the crack detection label 102 is ruptured when the elongation of the rupture layer 1 is 0.3 to 0.3 mm. It shall be designed to break in the range of 0.4 mm.

When the inspection target 20 receives a tensile force in the X direction and extends along the X direction, the crack detection labels 101 and 102 also extend in the X direction following this. In practice, each of the adhesive layer 5, the resin base material 3, and the fracture layer 1 extends integrally along the X direction, as in FIG. 2(a). Eventually, as shown in FIG. 3(b), the inspection object 20 develops a crack 31, and the crack detection labels 101 and 102 extend as much as possible following the crack. , the rupture layer 1 on the outermost surface is broken, and the crack detection label 102 is in a stable state with no change in the rupture layer 1 on the outermost surface.

In the above case, the inspector who checked the surfaces of the crack detection labels 101 and 102 immediately found that the inspection object 20 had a crack of 0.2 to 0.3 mm due to the difference in the respective fracture conditions. can be judged. In this manner, by attaching a plurality of crack detection labels having different breaking properties to the same assumed crack location, it is possible to more reliably grasp the crack condition. Moreover, according to the present disclosure, there is no risk of individual differences occurring among inspectors, and the simple layered structure can be provided at low cost. As the number of crack detection labels attached with different breaking conditions increases, more detailed determination becomes possible.

2. Second Embodiment (a) Structure Next, a second embodiment of the crack detection label of the present disclosure will be described. FIG. 4 is a cross-sectional view showing the crack detection label 110 of the second embodiment. As shown in FIG. 4, the difference of the second embodiment from the first embodiment is that a printed layer 7 is further provided as an upper layer of the rupture layer 1 as a rupture display layer. The fracture display layer in the present disclosure means various layers provided on the upper layer of the fracture layer in order to improve the visibility of the fractured state of the fracture layer, not only the printed layer in the present embodiment, but also the metal deposition layer described later. Also includes metal foil and the like.

In the first embodiment, the ionizing radiation curable resin itself forming the rupture layer 1 can be colored to some extent. Ultraviolet rays and electron beams cannot sufficiently be irradiated to the lower layer portion of 1, which may lead to uneven curing of the rupture layer 1 and waste of energy due to increased irradiation intensity. In addition, when the coloration is light, it may be difficult to visually recognize the state of the fractured portion due to the fracture of the fractured layer of the label for detecting cracks from a distance.

On the other hand, in the present embodiment, the rupture layer 1 is formed in advance, cured with ultraviolet rays or electron beams, and then the printed layer 7 is formed on the upper surface thereof, so that it is colored with a high density with low light transmittance. However, there is no problem with the function of the rupture layer 1, and the rupture state of the crack detection label can be reliably visually recognized even from a distance.

(b) Printed layer The printed layer 7 can be colored and designed as desired, for example, in a state in which the adhesive layer 5 to the breaking layer 1 are laminated, or on the resin substrate 3 excluding the adhesive layer 5 In a state in which the rupture layer 1 is laminated, an ink composed of a predetermined color pigment, coloring agent, dye, etc. and a solvent or the like is applied to the upper surface of the rupture layer 1 by known transfer such as printing, die coating, spray coating, inkjet, etc. It can be formed by a coating technique.

The coloring of the printed layer 7 may be a combination of colors that gives sufficient contrast to the coloring of the resin base material 3 that is visually recognized as the underlying layer when the fracture layer 1 is fractured. For example, the resin base material 3 may be colored red and the printed layer 7 may be colored green. It can also be a combination of matte colors and vice versa. In order to ensure the visibility of the fractured state of the fractured layer 1 from a distance, for example, each colored portion of the resin base material 3 and the printed layer 7 is L defined in 7.1.1 of JIS Z8730 (2009) The color difference ΔE ^* ab in the ^* a ^* b ^* color system is preferably 25.0 or more.

In addition, the coloring of the printing layer 7 may be coloring of a uniform constant density over the entire surface of the fracture layer (so-called solid printing). A design in which a printed portion is mixed can also be used. In the case of such a design, if all of the breaking layer 1, the resin base material 3 and the adhesive layer 5 are transparent or translucent, the actual cracked portion of the inspection object 20 is the adhesive layer 5, the resin Through the base material 3, the rupture layer 1, and the non-printed portions of the printed layer 7, it is possible to visually confirm that the rupture layer 1 has been ruptured due to changes in the arrangement of the printed layer 7 and the like.

Moreover, the coloring of the printed layer 7 may be a phosphorescent printed layer containing a phosphorescent pigment. By capturing excitation light such as ultraviolet light during the daytime, luminous energy is stored, and the rupture state of the rupture layer 1 can be visually confirmed by the luminescence of the printed layer 7 even at night. The ink resin material for forming the phosphorescent print layer has a certain degree of transparency, such as acrylic resin, vinyl chloride-vinyl acetate copolymer, polyester resin, urethane resin, epoxy resin, ultraviolet curable resin, and electron beam curable resin. Thermoplastic, thermosetting, or electron beam curable resins can be used. Transparency is not limited as long as the phosphorescent pigment to be used has transparency and translucency to light of a wavelength that can stimulate it and light of a wavelength that emits afterglow. For example, in SrAl ₂ O ₄ -based phosphorescent pigments, the excitation light has a wavelength of 200 to 450 nm, and the emitted light has a peak at 520 nm, with a wavelength range of about 430 to 640 nm.

As a luminous pigment, a sulfide-based luminous pigment is used in which zinc sulfide or the like is used as a mother crystal, and a trace amount of impurities, that is, Cu, Bi, or the like is added as an activator. :Bi, CaSrS:Bi, ZnCdS:Cu, etc., which emit light in yellow-green, purple-blue, blue and yellow, respectively. Among them, ZnS:Cu is well known as a phosphorescent pigment for yellow-green luminescent luminous paint. These phosphorescent pigments contain a small amount of an activator such as europium and, if necessary, a small amount of a co-activator such as manganese, bismuth, tin, lanthanum, cerium, praseodymium, neodymium, and samarium, thereby improving the phosphorescent performance. can be improved. These phosphorescent pigments may be added to the rupture layer 1 itself in addition to being used to form the printed layer 7 as described above.

Also, the printing layer 7 may be colored with a pearl ink containing a pearl pigment. Pearl inks are known inks containing pearl pigments in which the surfaces of thin plate-like mica particles (mica) are coated with titanium dioxide, iron oxide, or the like, and can provide complex luster and colors. By using this for the printed layer 7, visibility of the broken state of the broken layer 1 of the label for crack detection from a distance is improved. In order to obtain the same effect, the pearl pigment may be added to the rupture layer 1 itself in addition to being used to form the printed layer 7 with pearl ink as described above.

3. 3rd Embodiment (a) Structure Next, 3rd Embodiment of the label for crack detection of this indication is described. FIG. 5 is a cross-sectional view showing a crack detection label 120 of the third embodiment. FIG. 5A is a cross-sectional view showing a state in which a crack detection label 120 is attached to the surface of an inspection object 20 such as a concrete structure. The difference of the third embodiment from the first embodiment is that a metal deposition layer 8 as a rupture indicating layer and a surface protection layer 12 are further provided on the upper layer of the rupture layer 1 .

Instead of coloring the rupture layer 1 itself to some extent or providing a printed layer on it, or in addition to these, the crack detection label 120 clearly indicates that it has been ruptured on the upper layer of the rupture layer 1. By stacking the metal vapor deposition layer 8 as a breakage display layer to be obtained, the visibility of the breakage state from a distance can be improved. Furthermore, the metal vapor deposition layer 8 has a light shielding effect against direct sunlight and heat shielding, so that it is possible to suppress deterioration in quality and function due to an increase in temperature of the crack detection label 120 and the like. In addition, a surface protective layer 12 is further provided thereon in order to suppress deterioration of the metal deposition layer 8 itself due to environmental conditions.

(b) Vapor-deposited metal layer The vapor-deposited metal layer 8 is formed by heating aluminum, zinc, tin, copper, nickel, chromium, titanium, gold, silver, and indium by a heating method such as a resistance heating method, a high-frequency induction heating method, or an electron beam heating method. It can be formed by vapor-depositing a metal such as the above on the surface of the rupture layer 1 by a known vacuum vapor deposition method. In particular, a metal deposition layer of aluminum is suitable from the viewpoints of ease of processing, material, processing cost, durability, visibility, and the like.

The thickness of the metal vapor deposition layer 8 is not particularly limited, but it is desirable to have a certain thickness from the viewpoint of ensuring visibility of the fractured portion when fractured and durability such as prevention of peeling off. The required thickness is, for example, 10-1000 nm, preferably 20-500 nm, more preferably 50-200 nm. If the thickness is 10 to 1000 nm, it is possible to meet a wide range of requirements such as manufacturing cost and ensuring visibility of the broken state from a distance. If the thickness is 20 to 500 nm, it is possible to more reliably achieve both durability and visibility, and if the thickness is 50 to 200 nm, extremely stable durability and visibility can be ensured, and crack detection can be achieved. It is possible to obtain high reliability in long-term use of labels for labels.

(c) Surface Protective Layer It is desirable to provide a surface protective layer 12 on the metal deposition layer 8 to protect it. When the metal deposition layer 8 is directly exposed to the outside air, wind and rain for a long period of time, it may peel off from the rupture layer 1, resulting in deterioration in quality, such as reduced visibility in confirming the rupture state when cracked. Therefore, in order to protect it, transparent resin or the like is laminated.

The material of the surface protective layer 12 is not particularly limited as long as it has a certain degree of transparency that does not hinder the visibility of the metal deposition layer 8 and a protective function against the external environment. Photopolymerization initiators such as benzophenone, acetophenone, and thioxanthone are diluted and mixed with methacrylic resin, ionizing radiation-curable epoxy-modified acrylate resin, urethane-modified acrylate resin, acrylic-modified polyester resin, etc. A liquid coating liquid may be used and formed by printing, die coating, spray coating, inkjet, or the like.

Since it is preferable that the surface protective layer 12 breaks following the breakage of the underlying breakable layer 1, it is desirable to make the thickness as thin as possible, for example, about 1 to 100 μm. However, even if the surface protective layer 12 itself does not necessarily follow the rupture layer 1 and break, there is no problem in confirming the rupture state itself as long as the metal vapor deposition layer 8 on the rupture layer 1 can be visually recognized. . In addition, if it is used in a relatively stable environment that is not exposed to wind and rain, the surface protective layer 12 may not be provided on the metal deposition layer 8 .

(d) Function of crack detection label (3)
First, as shown in FIG. 5A, the crack detection label 120 in this embodiment is placed on the surface of the inspection target 20 such as a concrete structure at a predetermined position, and the surface of the adhesive layer 5 is attached. Press and stick. When the inspection target 20 receives a tensile force along the X direction in FIG. 5A, elongation occurs in the elastic deformation range along the X direction, and the crack detection label 120 that is in close contact with this stretches. The adhesive layer 5, the resin base material 3, and the rupture layer 1 integrally follow the elongation of the test object 20 and cause elastic deformation along the X direction to extend.

Furthermore, when the test object 20 is stretched in the X direction by the tensile force in the X direction, the test object 20 breaks at a certain stage, and as shown in FIG. give rise to At this time, the adhesive layer 5, the resin base material 3, and the rupture layer 1 continue to stretch to some extent following the spread of the cracks 31, but eventually the rupture layer 1, which has the smallest allowable elongation amount, stretches. reaches the limit of , and a fractured portion 33 is formed in the fractured layer 1 . At this time, since the metal vapor deposition layer 8 which is the upper layer of the fracture layer 1 does not exist in the fracture portion 33, the pattern of the metal vapor deposition layer 8 is apparently separated to the left and right across the fracture portion 33. appear. Therefore, by confirming the separated pattern of the metal deposition layer 8, it can be clearly recognized that the rupture layer 1 below it has been ruptured, and it can be determined that a predetermined amount of cracking has occurred in the inspection object 20. The metal deposition layer 8 functions as a fracture indication layer that visually indicates that the fracture layer 1 is fractured.

As described above, in the present embodiment, the fractured state of the fractured layer 1 is displayed as it is by the metal vapor deposition layer 8 on the upper layer, so that even when an inspector checks from a distance, it can be confirmed with good visibility. can. Further, in the present embodiment, at least two regions are provided where the surface protective layer 12 is not partially applied, and, for example, these two points can be exposed as points for measuring the electrical resistance of the vapor deposited metal layer 8. can. By providing these two measurement points in an arrangement that straddles the crack, the metal vapor deposition layer 8 can be separated by measuring the electrical resistance at these measurement points together with visual confirmation of the fracture state as necessary. It is also possible to grasp the situation from changes in electrical resistance.

4. Fourth Embodiment (a) Structure Next, a fourth embodiment of the crack detection label of the present disclosure will be described. FIG. 6 is a cross-sectional view showing the crack detection label 130 of the fourth embodiment. A difference of the fourth embodiment from the first embodiment is that a metal foil 9 is further provided as an upper layer of the rupture layer 1 as a rupture display layer.

Instead of coloring the rupture layer itself to some extent or providing a printed layer on it, or in addition to these, the crack detection label 130 can clearly indicate that the upper layer of the rupture layer 1 is broken. By laminating the metal foil 9 as a breakage display layer, the visibility of the breakage state from a distance can be improved. Furthermore, the metal foil 9 has a light shielding effect against direct sunlight and the like, and a heat shielding effect, so that it is possible to suppress deterioration in quality and function due to an increase in temperature of the crack detection label 130 and the like. In addition, when the metal foil 9 is broken following the breakage of the lower fracture layer 1, the electrical resistance of the metal foil 9 between two points across the fractured portion changes significantly. can be measured to check for cracks, and an electrical resistance detector can be installed to send a signal to the outside when the electrical resistance value is abnormal.

(b) Metal foil The metal foil 9 is formed by a known rolling method, such as by rolling a metal such as aluminum, zinc, tin, copper, nickel, chromium, titanium, gold, silver, or indium using a rolling mill or the like. to use. In particular, aluminum metal foil is suitable from the viewpoints of ease of processing, material, processing cost, durability, visibility, and the like.

The thickness of the metal foil 9 is not particularly limited, but it is desired that the metal foil 9 be thin enough to ensure the minimum durability because it is required to follow the fracture of the fracture layer 1 below. The required thickness is, for example, 5-100 μm, preferably 10-30 μm. If the thickness is 5 to 100 μm, it is possible to meet a wide range of requirements such as manufacturing cost, durability, and breakability. If the thickness is 10 to 30 μm, higher durability and breakability can be stably ensured.

(c) Dry Laminate Layer As shown in FIG. 6, a dry laminate layer 13 is formed between the rupture layer 1 and the metal foil 9 in order to ensure adhesion between them. The material is not particularly limited, and various known acrylic, polyester, polyurethane, silicone, rubber, and other materials diluted with a solvent or the like can be selected. As a forming method, a dry laminate layer 13 is formed on the surface of the breaking layer 1 by any method such as a printing method, a coating method, a spray coating method, an inkjet method, etc., and is exposed to a predetermined temperature for a predetermined time to evaporate the solvent. Leave only the adhesive component. A metal foil 9 is placed on the dry laminate layer 13, and is adhered to the rupture layer 1 by applying predetermined heat and pressure. Although there is no particular limitation on the thickness, a thickness of about 1 to 50 μm, preferably about 6 to 10 μm, is preferable from the viewpoints of ensuring adhesion and breaking aptitude of the metal foil.

(d) Function of crack detection label (4)
The crack detection label 130 in this embodiment is basically as described in the fourth embodiment, and the metal foil 9 on the outermost surface is broken along with the breakage of the lower breakage layer 1, so that the inspection target is Cracks can be visually recognized while ensuring visibility.

Furthermore, since the electrical resistance value of the metal foil 9 clearly changes before and after the breakage, it is possible to detect the occurrence of an abnormality such as a crack by detecting the change in the electrical resistance value in addition to visual confirmation. is also possible. For example, a measuring device that measures the electrical resistance value by using two points across the cracked portion of the metal foil 9 as measuring points, and an alarm device that notifies the outside by emitting an abnormal signal or emitting an audible signal when the measured value is abnormal. can be installed together. In addition, the metal foil 9 is formed as a part of the antenna circuit of the RFID tag, and when the metal foil 9 breaks due to cracking, the communication signal of the RFID tag cannot be transmitted. A method of judging the presence or absence of cracks based on whether or not the RFID tag can be read can be considered. As in the case of the metal deposition layer 8, a surface protective layer is provided on the upper layer of the metal foil 9 to protect the metal foil 9 from deterioration of the surface over a long period of time.

5. Fifth Embodiment Next, a fifth embodiment of the crack detection label of the present disclosure will be described. FIG. 7 is a perspective view showing a state in which the crack detection label 140 of the fifth embodiment is attached to the inspection object 20 in which cracks have begun to occur. The difference of the fifth embodiment from the first embodiment is that a half-cut cut of a certain depth is formed from the surface of the fracture layer 1 toward the stacking direction, and the shape of the cut is intermittent linear. It is formed. The intermittent linear shape includes, for example, a perforation shape.

FIG. 7 shows a crack detection label in which a perforated portion 14 is cut to a certain depth in the stacking direction from the rupture layer 1 that is the outermost surface of the crack detection label having the layer structure of the first embodiment. The label 140 is attached to the inspection object 20 where cracks 31 have begun to occur. The depth of the incision is such that only the rupture layer 1 penetrates without reaching the adhesive layer 5 and the resin base material 3 . Thereby, the rupture layer 1 can increase the easiness of rupture with respect to the amount of elongation of the crack 31 compared to the case where there is no notch. When it is difficult to make the thickness of the rupture layer 1 thin, the thickness of the rupture layer is increased to some extent, and the depth and pitch of the perforations 14 formed thereon are adjusted. , the same detection sensitivity as when the thickness of the rupture layer 1 is formed thin can be obtained, and the rupture layer 1 can be ruptured for a very small amount of elongation.

In addition, additives can be appropriately added in order to increase the sensitivity of the rupture layer 1. However, when manufacturing labels for detecting cracks according to various sensitivities, it is necessary to mass-produce the same additives in the same amount. If the sensitivity is adjusted later by changing the depth of the notch, etc., fine changes and adjustments of the manufacturing conditions during the manufacturing process become unnecessary and the manufacturing becomes easy. The depth of the cut does not need to be limited to the above. For example, the fracture layer 1 itself can be half-cut, or the resin substrate 3 can be cut halfway in the thickness direction, and the fracture layer 1 can be cut to prevent cracks. Conditions may be determined according to the amount of elongation. When the breaking layer 1 itself is half-cut, the slit shape may be a continuous line slit instead of a perforation.

6. Sixth Embodiment Next, a sixth embodiment of the crack detection label of the present disclosure will be described. FIG. 8 is a perspective view showing a state in which the crack detection label 150 of the sixth embodiment is attached to the inspection object 20 in which cracks have begun to occur. A difference with respect to the fifth embodiment is that a notch having a depth penetrating from the surface of the breaking layer 1 to the adhesive layer 5 is formed in the stacking direction. Originally, when the crack detection label is stretched due to cracking, the rupture layer 1 is formed under the condition that the rupture layer 1 is ruptured before the resin base material 3. This relationship does not change significantly. Depending on the convenience of manufacturing, it is possible to appropriately select between half-cutting and penetrating formation.

7. EXAMPLES Next, the present disclosure will be described by examples.
(a) Test piece preparation conditions A polyethylene terephthalate film having a thickness of 230 µm was selected as the resin base material, and a medium of melamine resin paint (manufactured by Dainippon Ink Mfg. Co., Ltd., TCM01 medium) was applied as a primer layer on both sides of the film. It was applied in a thickness of 0.4 μm with a minute coating amount and heat-treated at 180° C. for 20 seconds. On one side thereof, an acrylic emulsion-type adhesive (Olibain BPW5012 manufactured by Toyo Ink Mfg. Co., Ltd.) is applied to form a coating film, which is heat-treated at 100° C. for 60 seconds to form an adhesive layer having a thickness of 20 μm. formed. In addition, on the resin substrate surface on the side opposite to the adhesive layer, 100 parts by mass of a polyester acrylate oligomer UV-curable resin (KIZ044 mat, manufactured by The Inktec Co., Ltd.) with a high functional group number (18 functional groups) is applied with UV-curable 5 parts by mass of an initiator was diluted and mixed, applied, and cross-linked and cured by UV irradiation to form a rupture layer as a hard coat layer.

Under the above common conditions, test pieces with test numbers 1, 2, 3, 4, and 5 had a fracture layer thickness of 10.0 μm, and test numbers 6, 7, 8, 9, and 10 as conditions for the fracture layer. The fault layer thickness was 16.0 μm, and test numbers 11, 12, 13, 14, and 15 had a fracture layer thickness of 20.0 μm. In test numbers 2, 7, 12, 14, and 15, 1 part by mass of polyethylene wax fine particles was added as an additive to 100 parts by mass of the ultraviolet-curable resin (solid content). , 8, 9, 10 and 13, 2 parts by mass of the same additive was added. Furthermore, in test numbers 4 and 9, an aluminum vapor deposition layer having a thickness of 50 nm was formed as a metal vapor deposition layer on the fracture layer, and a high functional group (18 functional) polyester acrylate oligomer UV-curable resin was formed as a surface protective layer. (KIZ044 mat, manufactured by The Inktec Co., Ltd.) was diluted with 5 parts by mass of an ultraviolet curing initiator, applied, and crosslinked and cured by UV irradiation to form a surface protective layer with a thickness of 5 μm. . In addition, in Test No. 14, cuts in the perforated portion as intermittent linear shapes penetrating in the lamination direction, and in Test No. 15, only the fracture layer penetrated in the lamination direction, and the resin base material The notch of the perforated portion was formed as an intermittent linear shape of a half-cut with a depth not reaching . Note that the length of each cut portion in the surface direction of the perforation was 3.0 mm, and the length of each non-cut portion was 2.0 mm.

In test numbers 5 and 10, 100 parts by weight of Dick Dry LX-500 as a dry laminate layer and 10 parts by weight of curing agent KW-75 were mixed and dispersed in 100 parts by weight of solvent MEK on the fracture layer. was applied to a thickness of 5.0 μm as a solid content coating amount, dried at 100° C. for 20 seconds, an aluminum foil having a thickness of 11 μm was placed thereon, dry-laminated, and adhered to the upper layer of the rupture layer.

(b) Test method, results Test pieces of test numbers 1 to 15 are finally finished with a width of 15.0 mm and a length of 40.0 mm in the surface direction, and the perforations of test numbers 14 and 15 are , on a line parallel to the width direction passing through the center in the length direction. Each of these test pieces is adhered to a resin base material (230 μ thick polyethylene terephthalate film) simulating an object to be inspected, both ends are held so that the interval is 50 mm as a starting point, and a tensile test is performed at a speed of 100 mm / min. Table 1 below shows the results of testing for the amount of elongation when the fractured layer breaks, and the visibility of the fractured state when viewed by a confirmer from a distance of 10 m.

From Table 1, by changing the thickness of the fracture layer and changing the amount of additive added, the range of elongation of the test piece, which corresponds to the progress of cracking, and the presence or absence of fracture detection change. I found out to do. In addition, instead of increasing the content of the additive, forming perforation-shaped incisions with a depth that penetrates or half-cuts in the lamination direction also increases the sensitivity of fracture detection to the amount of elongation of the test piece. I found that I can do it. Therefore, by determining the thickness condition of the fracture layer and the additive amount condition or the cut condition corresponding to the degree of cracking to be detected, and using a crack detection label with predetermined conditions according to this, the detection of crack generation is It was found that the presence or absence of rupture of the rupture layer of the label can be determined by a simple visual inspection method. Also, even if a metal vapor deposition layer, surface protective layer, or metal foil is laminated on the outermost surface, the point of breakage is the same as when there is no such layer, and the visibility of breakage confirmation is better with these layers. confirmed to improve.

1 Breaking Layer 2 Primer Layer 3 Resin Base Material 4 Primer Layer 5 Adhesive Layer 6 Separator 7 Printed Layer 8 Metal Deposition Layer 9 Metal Foil 10 Resin Layer 11 Additive 12 Surface Protection Layer 13 Dry Laminate Layers 14, 15 Perforation 20 Inspection Target 31 Cracks 32, 33 Fractured portions 100, 101, 102, 110, 120, 130, 140, 150 Crack detection label 100A Crack detection label with separator

Claims (6)

A label for detecting cracks occurring on a surface of an inspection object,
a resin substrate; a fracture layer provided on at least a portion of one surface of the resin substrate and breaking before the resin substrate due to a tensile force generated in the surface direction of the resin substrate;
An adhesive layer provided on the other surface of the resin base material and used to adhere the resin base material to the inspection object is laminated in this order,
The rupture layer is colored in a color different from that of the resin base material,
A label for detecting cracks, wherein the breaking layer contains an ultraviolet-curing acrylic-modified polyester resin . A label for detecting cracks occurring on a surface of an inspection object,
a resin substrate; a fracture layer provided on at least a portion of one surface of the resin substrate and breaking before the resin substrate due to a tensile force generated in the surface direction of the resin substrate;
An adhesive layer provided on the other surface of the resin base material and used to adhere the resin base material to the inspection object is laminated in this order,
The rupture layer is colored in a color different from that of the resin base material,
A label for detecting cracks, wherein the breaking layer contains polyethylene wax. 3. The crack detection label according to claim 1, wherein the rupture layer contains a phosphorescent pigment or a pearl pigment. The label for crack detection according to any one of claims 1 to 3 , characterized in that a notch with a constant depth is formed in the stacking direction including the rupture layer. 5. The crack detection label according to claim 4 , wherein the notch is formed in an intermittent line. 6. The crack detection label according to claim 4 , wherein the notch is formed in a half-cut state.

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