Anticorrosive adhesive tape

Abstract

To provide an anticorrosive adhesive tape that is excellent in adhesion to an adherend with a complicated surface shape under low temperature environment and can suppress occurence of wrinkle due to coating.SOLUTION: The present invention relates to an anticorrosive adhesive tape provided with a base material and an adhesive layer provided on at least one side of the base material, wherein, under an environment of 5°C, the base material has a difference between the tensile load when stretched by 2.5% and the tensile load when stretched by 0.5% of 1.3 N / mm or less, and the tensile breaking point elongation of the base material measured under the environment at a temperature of 5°C. is 100% or more, and a dimensional change rate of the base material after immersing the base material in xylene for 5 minutes is 3% or less.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to an anticorrosive adhesive tape. [Background technology]

[0002] In order to prevent corrosion of iron or alloys containing iron, such as steel, anticorrosive paints containing a large amount of zinc are widely used. Zinc is a metal with a lower potential than iron and has a sacrificial anticorrosive effect, so it is known to have high anticorrosive properties. However, corrosion prevention using paint requires a drying process after application, which takes time, and the work efficiency decreases when performing localized repairs in civil engineering and architectural applications such as bridges. In addition, corrosion prevention using paint is prone to uneven work.

[0003] In view of the above situation, efforts have been made to impart sacrificial corrosion protection to the tape and improve workability. For example, in Patent Document 1, zinc particles and conductive filler are contained in the adhesive layer, and an electronic circuit is formed between the zinc plate substrate and oxygen / water, thereby realizing sacrificial corrosion protection. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2019-127606 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, when the anticorrosive member of Patent Document 1 is attached to an adherend having a complex surface shape such as unevenness during cold seasons such as winter, the anticorrosive member may not adhere sufficiently to the adherend, and the anticorrosive properties of the anticorrosive member may not be fully exhibited. Also, when the anticorrosive member of Patent Document 1 is attached to an adherend and then the adherend is painted, wrinkles may occur in the anticorrosive member, deteriorating the appearance of the painted adherend. Therefore, an object of the present invention is to provide an anticorrosive pressure-sensitive adhesive tape that has excellent adhesion to adherends having complex surface shapes in low-temperature environments and can suppress the occurrence of wrinkles due to painting. [Means for solving the problem]

[0006] As a result of intensive research, the inventors have found that the above-mentioned problems can be solved by using a substrate in which the difference from a predetermined tensile load measured in a low-temperature environment is a predetermined value or less, the tensile elongation at break measured in a low-temperature environment is a predetermined value or more, and the dimensional change rate of the substrate after immersion in xylene for 5 minutes is a predetermined value or less, and have completed the present invention. The present invention provides the following [1] to

[16] .

[0007] [1] An anti-corrosion adhesive tape comprising a substrate and an adhesive layer provided on at least one side of the substrate, wherein in an environment at 5°C, the difference between the tensile load when the substrate is elongated by 2.5% and the tensile load when the substrate is elongated by 0.5% is 1.3 N / mm or less, the tensile elongation at break of the substrate measured in an environment at 5°C is 100% or more, and the dimensional change of the substrate after immersing the substrate in xylene for 5 minutes is 3% or less. [2] The corrosion-preventive adhesive tape according to the above item [1], which does not rust in a cyclic corrosion test conforming to Cycle D of JIS K5600-7-9 and has an adhesive strength of 20 N / 25 mm or more after the cyclic corrosion test. [3] The anticorrosive adhesive tape according to [1] or [2] above, wherein the gloss retention of the substrate is 80% or more after 500 hours of an accelerated weather resistance test in accordance with cycle A of JIS K5600-7-7. [4] The anticorrosive adhesive tape according to any one of the above [1] to [3], wherein the thickness of the substrate is 20 to 1000 μm. [5] The anticorrosive pressure-sensitive adhesive tape according to any one of the above [1] to [4], wherein the substrate is a resin film having a paint film on its surface. [6] The anticorrosive adhesive tape according to [5] above, wherein the resin film is at least one film selected from the group consisting of a multilayer resin film consisting of a polyamide-based resin layer and a polyolefin-based resin layer, a soft acrylic-based resin film, and a fluororesin film. [7] The anticorrosive adhesive tape according to any one of the above [1] to [6], wherein, under room temperature conditions, the difference between the tensile load when the substrate is elongated by 2.5% and the tensile load when the substrate is elongated by 0.5% is 1.3 N / mm or less, and the tensile elongation at break of the substrate measured under room temperature conditions is 100% or more. [8] The corrosion-preventive adhesive tape according to any one of the above [1] to [7], wherein the adhesive layer contains a metal having a lower electric potential than iron. [9] The corrosion-preventive adhesive tape according to the above item [8], wherein the metal having a lower potential than iron is zinc.

[10] The corrosion-preventive adhesive tape according to the above [8] or [9], wherein the adhesive layer contains a conductive material other than the metal having a lower potential than iron.

[11] The corrosion-preventive adhesive tape according to the above

[10] , wherein the conductive material is a carbon nanotube.

[12] The anticorrosive adhesive tape according to any one of the above [1] to

[11] , wherein the adhesive layer is formed from an acrylic adhesive.

[13] The corrosion-preventive adhesive tape according to any one of the above [1] to

[12] , further comprising a metal layer between the substrate and the adhesive layer, the metal layer being a layer of a metal having a lower electric potential than iron.

[14] The corrosion-preventive adhesive tape according to the above

[13] , wherein the metal layer is a zinc layer.

[15] The anticorrosive adhesive tape according to any one of the above [1] to

[14] , wherein the adhesive layer has a thickness of 50 to 3000 μm.

[16] The anticorrosive pressure-sensitive adhesive tape according to any one of the above [1] to

[15] , wherein the pressure-sensitive adhesive layer has a storage modulus of 50,000 to 1,000,000 Pa at 23°C. Effect of the Invention

[0008] According to the present invention, it is possible to provide an anticorrosive pressure-sensitive adhesive tape that has excellent adhesion to adherends having complex surface shapes in low-temperature environments and is capable of suppressing the occurrence of wrinkles due to painting. [Brief description of the drawings]

[0009] [Figure 1] 1 is a schematic diagram showing an example of use of a modified example of the anticorrosive adhesive tape of one embodiment of the present invention. [Diagram 2] FIG. 2 is a schematic cross-sectional view showing another embodiment of the anticorrosive adhesive tape of the present invention. [Diagram 3] FIG. 2 is a schematic diagram showing a method for evaluating the convex-following ability of the anticorrosive pressure-sensitive adhesive tape of the present invention. [Figure 4] FIG. 1 is a diagram for explaining evaluation of topcoat painting. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] [Anti-corrosion adhesive tape] The present invention provides an anticorrosive adhesive tape comprising a substrate and an adhesive layer provided on at least one side of the substrate. In an environment at 5° C., the difference between the tensile load of the substrate when elongated by 2.5% and the tensile load of the substrate when elongated by 0.5% is 1.3 N / mm or less. Furthermore, the tensile elongation at break of the substrate measured in an environment at 5° C. is 100% or more, and the dimensional change of the substrate after immersing the substrate in xylene for 5 minutes is 3% or less.

[0011] <Base material> (Difference in tensile load) The substrate of the corrosion-preventive adhesive tape of the present invention has a difference (hereinafter sometimes simply referred to as "tensile load difference") between the tensile load when elongated by 2.5% and the tensile load when elongated by 0.5% in an environment at 5° C. of 1.3 N / mm or less. The difference in tensile load in an environment at 5° C. essentially means the tensile load per 2% elongation in the elastic region in an environment at 5° C. If the difference in tensile load in an environment at 5° C. exceeds 1.3 N / mm, the anticorrosive pressure-sensitive adhesive tape may peel off or tear when it is adhered to an adherend having a complex surface shape in a low-temperature environment. From this viewpoint, the difference in tensile load in an environment at 5° C. is preferably 1.2 N / mm or less, more preferably 1.1 N / mm or less, and even more preferably 1.0 N / mm or less. The lower limit of the range of the difference in tensile load in an environment at a temperature of 5°C is not particularly limited, but from the viewpoint of imparting a certain level of mechanical strength in a low-temperature environment, it is preferably 0.05 N / mm or more, more preferably 0.1 N / mm or more, and even more preferably 0.3 N / mm or more. The difference in tensile load is measured in both the MD and TD directions of the substrate, and the larger of these is used. If the MD and TD directions are unknown, the largest difference in tensile load should be used. The difference in tensile load can be obtained by the measurement method described in the Examples. The difference in tensile load of the substrate can be adjusted to within the above range by appropriately selecting the material used for the substrate, the thickness of the substrate, and the like.

[0012] The substrate of the anticorrosive pressure-sensitive adhesive tape of the present invention preferably has a tensile load difference of 1.3 N / mm or less under a room temperature (23° C.) environment. The tensile load difference under a room temperature environment means the tensile load per 2% elongation substantially in the elastic region under a room temperature environment. When the difference in tensile load under room temperature is 1.3 N / mm or less, the occurrence of lifting or tearing can be suppressed when the anticorrosive pressure-sensitive adhesive tape is adhered to an adherend having a complex surface shape under room temperature. From this viewpoint, the difference in tensile load under room temperature is more preferably 1.2 N / mm or less, even more preferably 1.1 N / mm or less, and even more preferably 1.0 N / mm or less. The lower limit of the range of the difference in tensile load under room temperature is not particularly limited, but from the viewpoint of imparting a certain level of mechanical strength under room temperature, it is preferably 0.05 N / mm or more, more preferably 0.1 N / mm or more, and even more preferably 0.2 N / mm or more.

[0013] (Tensile elongation at break) The substrate used in the anticorrosive adhesive tape of the present invention has a tensile elongation at break of 100% or more in an environment at a temperature of 5°C. If the tensile elongation at break of the substrate is less than 100% in an environment at a temperature of 5°C, when the anticorrosive adhesive tape is applied to an adherend having a complex surface shape in a low-temperature environment, the anticorrosive adhesive tape may lift or tear, resulting in insufficient adhesion of the anticorrosive adhesive tape to the adherend. In addition, if the tensile elongation at break of the substrate is less than 100% in an environment at a temperature of 5°C, the anticorrosive adhesive tape may wrinkle when a topcoat is applied to the adherend to which the anticorrosive adhesive tape is applied. From this viewpoint, the tensile elongation at break of the substrate is preferably 125% or more, more preferably 150% or more, and even more preferably 300% or more. On the other hand, the upper limit of the tensile elongation at break of the substrate in an environment at 5°C is not particularly limited, but from the viewpoint of mechanical strength in a low-temperature environment, it is preferably 700% or less, more preferably 600% or less, and even more preferably 500% or less. The tensile elongation at break is measured in both the MD and TD directions of the substrate, and the smaller of these is used. If the MD and TD directions are unknown, the smallest tensile elongation at break value should be used. The tensile elongation at break can be obtained by the measurement method described in the Examples. The tensile elongation at break can be adjusted to within the above range by appropriately selecting the material used for the substrate, the thickness of the substrate, and the like.

[0014] The substrate used in the anticorrosive adhesive tape of the present invention preferably has a tensile elongation at break of 100% or more under room temperature (23°C). When the substrate has a tensile elongation at break of 100% or more under room temperature, the anticorrosive adhesive tape can be prevented from lifting or tearing when the anticorrosive adhesive tape is attached to an adherend having a complex surface shape under room temperature. From this viewpoint, the tensile elongation at break of the substrate is more preferably 125% or more, even more preferably 150% or more, and even more preferably 300% or more. On the other hand, the upper limit of the tensile elongation at break of the substrate in a room temperature environment is not particularly limited, but from the viewpoint of mechanical strength in a room temperature environment, it is preferably 800% or less, more preferably 700% or less.

[0015] (Dimensional change rate after immersion in xylene) The dimensional change rate of the substrate used in the anticorrosive adhesive tape of the present invention after immersion in xylene for 5 minutes is 3% or less. If the dimensional change rate of the substrate is greater than 3%, when a topcoat paint is applied to an adherend to which the anticorrosive adhesive tape is attached, wrinkles may occur in the anticorrosive adhesive tape, and the appearance of the adherend coated with the topcoat paint may be deteriorated. From this viewpoint, the dimensional change rate of the substrate used in the anticorrosive adhesive tape of the present invention after immersion in xylene for 5 minutes is preferably 2% or less, more preferably 1.5% or less, and even more preferably 1% or less. The lower limit of the range of the dimensional change rate of the substrate used in the anticorrosive adhesive tape of the present invention after immersion in xylene for 5 minutes is not particularly limited, but is preferably 0%. The dimensional change rate of the substrate after immersion in xylene can be measured, for example, by the method described in the Examples below. The dimensional change rate of the substrate after immersion in xylene can be adjusted to within the above range by appropriately selecting the material used for the substrate.

[0016] (Materials used for the substrate) The substrate used in the present invention may be, for example, a sheet-like material such as a resin film or a nonwoven fabric. Examples of resin films include polyolefin resin films such as polypropylene resin films, polyethylene resin films, and ethylene-vinyl acetate copolymer (EVA) resin films, polyester resin films, polyamide resin films (nylon), acrylic resin films, polyurethane resin films, polystyrene resin films, polyvinyl chloride resin films, ethylene vinyl acetate resin films, acrylonitrile resin films, fluororesin films, polycarbonate resin films, AES resin films, and ASA resin films. The nonwoven fabric is made of synthetic resin fibers, such as polyamide, polyester, polyacrylic, polyolefin, or polyurethane. These sheet-like materials can be used alone or in combination of two or more. The resin film may be a single layer film or a multilayer film formed by laminating two or more of the above films. From the viewpoints of the difference in tensile load at a temperature of 5°C described above, the tensile elongation at break at a temperature of 5°C described above, and the weight change rate and shrinkage rate after immersion in xylene described above, the substrate is preferably a resin film, and more preferably a multilayer resin film.

[0017] When the substrate is a multilayer resin film, a multilayer resin film consisting of a polyamide resin layer and a polyolefin resin layer and a multilayer resin film consisting of a polyethylene terephthalate layer and a polyolefin resin layer are preferred, a multilayer resin film consisting of a polyamide resin layer and a polyolefin resin layer is more preferred, a multilayer resin film having a structure of a polyethylene layer / polyamide resin layer / polyethylene layer is even more preferred, and a multilayer resin film having a structure of a linear low-density polyethylene layer / polyamide resin layer / low-density polyethylene layer and a multilayer resin film having a structure of a linear low-density polyethylene layer / polyamide resin layer / linear low-density polyethylene layer are even more preferred. From the viewpoint of adhesion between the substrate and the pressure-sensitive adhesive layer, when the substrate is a multilayer resin film having a structure of a linear low-density polyethylene layer / polyamide resin layer / low-density polyethylene layer, it is preferred that the low-density polyethylene layer of the substrate and the pressure-sensitive adhesive layer are in contact. By using these multilayer resin films, the flexibility of the anticorrosive pressure-sensitive adhesive tape in a low-temperature environment can be further improved and the solvent resistance can be further increased. In addition, when the substrate is a single-layer resin film, a soft acrylic resin film and a fluororesin film are preferred.

[0018] From the viewpoint of improving the gloss retention rate after the accelerated weather resistance test described later, the substrate may be a resin film having a paint film on its surface.The paint film is preferably a resin film, more preferably a urethane resin film, an epoxy resin film, and a fluororesin film, even more preferably a fluororesin film, and even more preferably a difluoride-based fluororesin film and a trifluoride-based fluororesin film.The paint film may be provided on one side or both sides of the substrate, but is preferably provided on at least the side opposite to the side on which the pressure-sensitive adhesive layer of the substrate is provided.By using these paint films, the weather resistance of the anticorrosive pressure-sensitive adhesive tape can be further improved, and the gloss retention rate described later can be further increased.

[0019] From the viewpoint of improving weather resistance, an ultraviolet absorber, a light stabilizer (HALS), etc. may be blended into the resin constituting the substrate.

[0020] (Gloss retention of substrate after accelerated weathering test) The anticorrosive adhesive tape of the present invention preferably has a gloss retention rate of 80% or more after 500 hours of accelerated weather resistance testing in accordance with cycle A of JIS K5600-7-7. With the gloss retention rate of 80% or more, even if the anticorrosive adhesive tape is exposed to light for a long period of time, the progress of deterioration of the substrate can be stopped and the deterioration of the appearance of the anticorrosive adhesive tape can be prevented. In addition, light such as sunlight (especially ultraviolet light) can be sufficiently blocked, and both the deterioration of the adhesive layer and the decrease in the adhesive strength of the anticorrosive adhesive tape can be prevented. Considering these points, the gloss retention of the substrate constituting the anticorrosive pressure-sensitive adhesive tape of the present invention is preferably 85% or more, and more preferably 90% or more. The higher the gloss retention, the better, with the upper limit being 100%. The method for making the gloss retention rate equal to or greater than the lower limit is not particularly limited, but a weather-resistant substrate may be used. A weather-resistant resin may be used as the resin constituting the substrate so that the substrate itself has weather resistance. Weather resistance may also be improved by blending an ultraviolet absorber, a light stabilizer (HALS), or the like, into the resin constituting the substrate. For example, a weather-resistant coating film may also be provided.

[0021] The gloss retention can be measured by the following method. A corrosion-resistant adhesive tape (width 25 mm, length 100 mm) was attached to the surface of the tape, and the specular gloss of the substrate was measured from the substrate side using a glossmeter (for example, Horiba, Ltd., product name: "IG-340"). The specular gloss is measured using a glossmeter with a geometric condition of 60° in accordance with JIS K 5600-4-7. The specular gloss obtained by this measurement is designated as specular gloss A. Then, the tape is subjected to an accelerated weather resistance test in accordance with cycle A in JIS K 5600-7-7 for 500 hours. After the accelerated weather resistance test, the specular gloss of the substrate of the tape is measured by the same method as that performed before the test. The specular gloss obtained by the measurement after the test is designated as specular gloss B. The gloss retention of the tape is calculated from the two types of specular gloss obtained as described above. The formula for calculating the gloss retention is as follows. Gloss retention rate (%) = (Specular gloss B / Specular gloss A) x 100

[0022] (Thickness of substrate) The thickness of the substrate is not particularly limited, but is preferably 20 to 1000 μm, more preferably 40 to 500 μm, even more preferably 60 to 400 μm, and even more preferably 70 to 300 μm. By making the thickness of the substrate equal to or greater than these lower limits, it becomes easier to make the difference in tensile load equal to or less than 1.3 N / mm in an environment at a temperature of 5° C. Furthermore, by making the thickness of the substrate equal to or less than these upper limits, it becomes easier to make the tensile elongation at break of the substrate equal to or more than 100% measured in an environment at a temperature of 5° C.

[0023] <Adhesive layer> The corrosion-preventive pressure-sensitive adhesive tape of the present invention comprises a pressure-sensitive adhesive layer on at least one surface of a substrate. The pressure-sensitive adhesive layer will be described below.

[0024] (A metal with a lower potential than iron) The adhesive layer preferably contains a metal having a lower potential than iron. By containing a metal having a lower potential than iron (hereinafter also referred to as "sacrificial anticorrosive metal"), the adhesive layer has sacrificial anticorrosive properties, and the anticorrosive properties of the anticorrosive adhesive tape are improved. The sacrificial anticorrosive metal is dispersed in the adhesive constituting the adhesive layer.

[0025] Examples of sacrificial corrosion protection metals include cadmium, chromium, zinc, manganese, and aluminum, among which zinc and aluminum are preferred, and zinc is particularly preferred. By using zinc, the sacrificial corrosion protection properties are excellent.

[0026] The sacrificial metal for corrosion protection may be dispersed in the pressure-sensitive adhesive as a filler in any form, such as a particulate form, a scale form, a spindle form, etc., but is preferably in a particulate form. By making the sacrificial metal for corrosion protection into a particulate form, it becomes easy to disperse in the pressure-sensitive adhesive layer without substantially decreasing the adhesiveness of the pressure-sensitive adhesive layer. In this specification, the particulate shape refers to a shape in which the ratio of the length in the long axis direction to the length in the short axis direction (aspect ratio) is small, for example, the aspect ratio is 3 or less, preferably 2 or less. The particulate shape is not particularly limited, and may be spherical or amorphous such as powder. The particulate metal has a particle size of, for example, 1 to 500 μm, preferably 1 to 200 μm. In this specification, the particle size refers to the average particle size measured by a laser diffraction method.

[0027] The content of the sacrificial anticorrosive metal in the adhesive layer is, for example, 0.5 to 20 mass %, preferably 1 to 18 mass %, and more preferably 2 to 16 mass %, based on the total amount of the adhesive layer. When the content of the sacrificial corrosion protection metal is equal to or greater than these lower limits, the sacrificial corrosion protection is enhanced, thereby improving the corrosion protection performance, whereas when the content is equal to or less than these upper limits, the adhesive strength is increased.

[0028] The pressure-sensitive adhesive layer may not contain a sacrificial anticorrosive metal. When the pressure-sensitive adhesive layer does not contain a sacrificial anticorrosive metal, the adhesive strength of the anticorrosive pressure-sensitive adhesive tape is maintained high, and the anticorrosive pressure-sensitive adhesive tape is less likely to peel off from the adherend, thereby blocking water and oxygen and improving the anticorrosive properties.

[0029] (Conductive materials) The pressure-sensitive adhesive layer preferably further contains, in addition to the sacrificial protection metal, a conductive material other than the sacrificial protection metal. When the conductive material is contained, the electrons released when the sacrificial protection metal is ionized can be easily transferred to the adherend, and the sacrificial protection property can be easily improved. The conductive material may be one or more selected from carbon-based materials, metal-based materials, metal oxide-based materials, ionic polymers, and conductive polymers. Examples of carbon-based materials include carbon black, graphite, graphene, carbon nanotubes, and acetylene black. Examples of metal-based materials include metals with a more noble potential than iron, such as gold, silver, copper, nickel, or alloys containing these metals, or iron. Examples of metal oxide materials include indium tin oxide (ITO), antimony trioxide (ATO), fluorine-doped tin oxide (FTO), and zinc oxide. Examples of conductive polymers include polyacetylene, polypyrrole, PEDOT (polyethylenedioxythiophene), PEDOT / PSS (a composite of polyethylenedioxythiophene and polystyrene sulfonic acid), polythiophene, polyaniline, poly(p-phenylene), polyfluorene, polycarbazole, polysilane, or derivatives thereof. Examples of ionic polymers include sodium polyacrylate and potassium polyacrylate. The conductive materials may be used alone or in combination of two or more. Among the above, the conductive material is preferably a carbon-based material, and more preferably a carbon nanotube.

[0030] (Carbon Nanotubes) The adhesive layer preferably contains carbon nanotubes. By containing carbon nanotubes, the sacrificial corrosion protection of the adhesive layer is improved and the adhesive strength can be maintained at a high level, making it easier to obtain an anticorrosive adhesive tape that has both high adhesive strength and sacrificial corrosion protection. This is presumably because, although carbon nanotubes are a conductive material, the amount required to exhibit a certain level of sacrificial corrosion protection is small compared to other types of conductive materials, so the degree of decrease in adhesive strength is small.

[0031] Carbon nanotubes are tubular materials made from carbon. Carbon nanotubes have excellent electrical properties, and when combined with resins, they can be used to form highly conductive sheets. Carbon nanotubes are made of graphite sheets with a hexagonal mesh of carbon atoms rolled into a cylinder. Carbon nanotubes rolled in one layer are called single-wall carbon nanotubes, and those rolled in multiple layers are called multi-wall carbon nanotubes. In the anticorrosive adhesive tape according to one embodiment of the present invention, the type of carbon nanotube is not particularly limited, and may be any of single-wall carbon nanotubes, multi-wall carbon nanotubes, and mixtures containing these in any ratio. Carbon nanotubes manufactured by various methods such as arc discharge, laser evaporation, and chemical vapor deposition (CVD) can also be used.

[0032] The carbon nanotubes preferably have an average diameter of 1 to 100 nm, more preferably 2 to 15 nm. The carbon nanotubes preferably have an average length of 0.1 to 1000 μm, more preferably 10 to 500 μm. The carbon nanotubes preferably have an aspect ratio (average length / average diameter) of 10 to 100,000, more preferably 500 to 30,000. The diameter of a carbon nanotube refers to the outer diameter in the case of a single-wall carbon nanotube, and the outer diameter of the outermost tube in the case of a multi-wall carbon nanotube. The diameter and length of a carbon nanotube may be measured, for example, in an image obtained by observation with a transmission electron microscope (TEM), and the average diameter and average length may be calculated as the arithmetic mean of any 50 nanotubes.

[0033] From the viewpoint of the sacrificial corrosion resistance and adhesive strength of the adhesive layer, the content of the conductive material in the adhesive layer is preferably 0.005 to 10 mass%, more preferably 0.005 to 5 mass%, and even more preferably 0.006 to 3 mass%, based on the total amount of the adhesive layer.

[0034] When the conductive material is carbon nanotubes, the content of the carbon nanotubes in the adhesive layer is preferably 0.0005 to 0.7 mass %, more preferably 0.005 to 0.05 mass %, and even more preferably 0.006 to 0.045 mass %, based on the total mass of the adhesive layer. When the carbon nanotube content is equal to or greater than these lower limits, the sacrificial corrosion resistance is likely to be enhanced, whereas when the carbon nanotube content is equal to or less than these upper limits, the adhesive strength is likely to be improved.

[0035] (Adhesive) The adhesive layer is preferably formed of an adhesive. The type of adhesive is not particularly limited, but examples thereof include acrylic adhesives, rubber adhesives, urethane adhesives, and silicone adhesives. These may be used alone or in combination. Among these, the pressure-sensitive adhesive layer is preferably formed from an acrylic pressure-sensitive adhesive.

[0036] (Acrylic adhesive) The acrylic pressure-sensitive adhesive is a pressure-sensitive adhesive containing an acrylic polymer obtained by polymerizing a polymerizable monomer including a (meth)acrylic acid alkyl ester monomer (A). In this specification, the term "(meth)acrylic acid alkyl ester" refers to a concept including both acrylic acid alkyl ester and methacrylic acid alkyl ester, and the same applies to other similar terms. In addition, the term "polymerizable monomer" refers to a concept that can include not only a compound having no repeating unit, but also a monomer itself having a repeating unit, such as the olefin polymer (C) described later, as long as it is a compound that copolymerizes with the (meth)acrylic acid alkyl ester monomer (A).

[0037] ((Meth)acrylic acid alkyl ester monomer (A)) The (meth)acrylic acid alkyl ester monomer (A) is an ester of (meth)acrylic acid and an aliphatic alcohol, and is preferably an alkyl ester derived from an aliphatic alcohol in which the carbon number of the alkyl group of the aliphatic alcohol is preferably 2 to 14, more preferably 4 to 10. When the carbon number of the alkyl group is within this range, the adhesive strength is easily increased, and the storage modulus at 23°C of the adhesive described below is easily adjusted to a predetermined range.

[0038] Specific examples of the (meth)acrylic acid alkyl ester monomer (A) include ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, t-butyl (meth)acrylate, pentyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-octyl (meth)acrylate, isooctyl (meth)acrylate, nonyl (meth)acrylate, decyl (meth)acrylate, undecyl (meth)acrylate, dodecyl (meth)acrylate, tridecyl (meth)acrylate, and tetradecyl (meth)acrylate. Among these, n-butyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, and n-octyl (meth)acrylate are preferred, and n-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, or a combination thereof is more preferred. The (meth)acrylic acid alkyl ester monomer (A) may be used alone or in combination of two or more kinds.

[0039] The constituent unit derived from the (meth)acrylic acid alkyl ester monomer (A) constitutes the main component in the adhesive layer, and its content is generally 30% by mass or more, preferably 50% by mass or more, more preferably 70% by mass or more based on the total amount of the adhesive layer. In this way, by increasing the content of the (meth)acrylic acid alkyl ester monomer (A), it is possible to impart the desired adhesive strength to the adhesive layer. In addition, the content of the constituent unit derived from the (meth)acrylic acid alkyl ester monomer (A) is, for example, 97% by mass or less, preferably 95% by mass or less, more preferably 90% by mass or less in order to contain a certain amount or more of other components. The content of the constituent unit derived from the (meth)acrylic acid alkyl ester monomer (A) in the pressure-sensitive adhesive layer is substantially the same as the content of the (meth)acrylic acid alkyl ester monomer (A) in the pressure-sensitive adhesive composition described below, and can be expressed interchangeably. The same applies to components other than the component (A), such as the components (B) and (C) described below.

[0040] (Polar Group-Containing Vinyl Monomer (B)) The polymerizable monomer preferably contains a polar group-containing vinyl monomer (B) in addition to the (meth)acrylic acid alkyl ester monomer (A). The polar group-containing vinyl monomer (B) has a polar group and a vinyl group. By using the polar group-containing monomer (B), the adhesive strength to the adherend is easily improved. Examples of the polar group-containing vinyl monomer (B) include carboxylic acid vinyl esters such as vinyl acetate, carboxylic acids containing a vinyl group such as (meth)acrylic acid and itaconic acid, and their anhydrides, vinyl monomers having a hydroxyl group such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, caprolactone-modified (meth)acrylate, polyoxyethylene (meth)acrylate, and polyoxypropylene (meth)acrylate, and nitrogen-containing vinyl monomers such as (meth)acrylonitrile, N-vinylpyrrolidone, N-vinylcaprolactam, N-vinyllaurolactam, (meth)acryloylmorpholine, (meth)acrylamide, dimethyl(meth)acrylamide, N-methylol(meth)acrylamide, N-butoxymethyl(meth)acrylamide, and dimethylaminomethyl(meth)acrylate. Among these, (meth)acrylic acid, itaconic acid, and other vinyl group-containing carboxylic acids and their anhydrides are preferred, (meth)acrylic acid is more preferred, and acrylic acid is even more preferred. These polar group-containing vinyl monomers (B) may be used alone or in combination of two or more.

[0041] When the polar group-containing vinyl monomer (B) is used, the content of the structural unit derived from the polar group-containing vinyl monomer (B) in the adhesive layer is preferably 1 to 15 parts by mass, more preferably 2 to 12 parts by mass, and even more preferably 3 to 10 parts by mass, per 100 parts by mass of the structural unit derived from the (meth)acrylic acid alkyl ester monomer (A). By setting the content of the polar group-containing vinyl monomer (B) within such a range, the adhesive strength of the anticorrosive adhesive tape is easily improved.

[0042] (Olefin polymer (C)) The polymerizable monomer preferably further contains an olefin polymer (C) having a polymerizable bond at one end. By using such an olefin polymer (C), the adhesive strength of the anticorrosive adhesive tape can be easily improved. The polymerizable bond means an unsaturated carbon-carbon bond capable of polymerizing with a polymerizable monomer, and examples thereof include an unsaturated double bond, and preferably a (meth)acryloyl group. The olefin polymer (C) may be a polyolefin having a (meth)acryloyl group at one end. The polyolefin is a polymer of an aliphatic hydrocarbon compound having a double bond, such as ethylene, propylene, butane, butadiene, isoprene, or the like, or a hydrogenated product thereof.

[0043] Examples of polyolefins having a (meth)acryloyl group at one end include polyethylene having a (meth)acryloyl group at one end, which is prepared by reacting polyethylene having an epoxy group at one end with (meth)acrylic acid. In addition, examples include polybutadiene having a (meth)acryloyl group at one end or a hydrogenated product thereof, and examples of commercially available products thereof include "L-1253" manufactured by Kuraray Co., Ltd.

[0044] The number average molecular weight of the olefin polymer (C) is preferably 500 to 20000, more preferably 1000 to 10000. The number average molecular weight may be measured by gel permeation chromatography (GPC) and calculated using a calibration curve of standard polystyrene. In addition, the content of the structural unit derived from the olefin polymer (C) in the pressure-sensitive adhesive layer is preferably 1 to 20 parts by mass, more preferably 2 to 15 parts by mass, and even more preferably 4 to 12 parts by mass, per 100 parts by mass of the structural unit derived from the (meth)acrylic acid alkyl ester monomer (A).

[0045] (Crosslinking agent (D)) The polymerizable monomer preferably further contains a crosslinking agent. Examples of the crosslinking agent include a polyfunctional monomer having two or more vinyl groups, and preferably a polyfunctional (meth)acrylate having two or more (meth)acryloyl groups. The use of a polyfunctional monomer makes it easier to adjust the adhesive strength of the adhesive layer to an appropriate range. The polyfunctional (meth)acrylate is not particularly limited, and examples thereof include hexanediol di(meth)acrylate, ethoxylated bisphenol A di(meth)acrylate, tris(2-hydroxyethyl)isocyanurate triacrylate, ethoxylated trimethylolpropane triacrylate, proxied trimethylolpropane triacrylate, proxied glyceryl triacrylate, neopentyl glycol adipate diacrylate, and the like, as well as polymers such as polyethylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, and liquid hydrogenated 1,2-polybutadiene di(meth)acrylate. Among these polyfunctional (meth)acrylates, polymers are preferred, and liquid hydrogenated 1,2-polybutadiene diacrylate is more preferred. Commercially available liquid hydrogenated 1,2-polybutadiene diacrylates include "TEAI-1000" manufactured by Nippon Soda Co., Ltd. The content of the crosslinking agent-derived structural unit in the pressure-sensitive adhesive layer is preferably 0.1 to 4 parts by mass, more preferably 0.3 to 3 parts by mass, and even more preferably 0.5 to 2 parts by mass, relative to 100 parts by mass of the (meth)acrylic acid alkyl ester monomer (A). When the content of the crosslinking agent is within the above range, it is easy to adjust the storage modulus and adhesive strength of the pressure-sensitive adhesive layer to appropriate ranges.

[0046] (tackifier resin) The acrylic adhesive may contain a tackifier resin from the viewpoint of improving adhesive strength. As the tackifier resin, a tackifier resin having low polymerization inhibition properties, such as hydrogenated terpene resin, hydrogenated rosin, disproportionated rosin resin, petroleum resin, etc., is preferable. Among these, hydrogenated tackifier resins are preferable because tackifier resins having many double bonds inhibit polymerization reactions, and hydrogenated petroleum resins are particularly preferable. From the viewpoint of improving the cohesive strength and adhesive strength of the adhesive, the softening point of the tackifier resin may be about 95° C. or higher, but preferably includes one that is 120° C. or higher, and for example, one that is 95° C. or higher and lower than 120° C. may be used in combination with one that is 120° C. or higher and 150° C. or lower. The softening point may be measured by the ring and ball method specified in JIS K2207. The content of the tackifier resin in the acrylic adhesive is preferably 5 to 40 parts by mass, more preferably 7 to 35 parts by mass, and even more preferably 10 to 25 parts by mass, per 100 parts by mass of the structural units derived from the (meth)acrylic acid alkyl ester monomer (A).

[0047] (fine particles) The acrylic adhesive may contain fine particles, which can improve the adhesive strength. Examples of the fine particles include inorganic hollow particles such as glass balloons, shirasu balloons, and fly ash balloons; organic hollow particles made of polymethyl methacrylate, acrylonitrile-vinylidene chloride copolymers, polystyrene, and phenolic resins; inorganic fine particles such as glass beads, silica beads, and synthetic mica; and organic fine particles such as ethyl polyacrylate, polyurethane, polyethylene, and polypropylene. The content of the fine particles in the acrylic pressure-sensitive adhesive is preferably 0.1 to 15 parts by mass, more preferably 0.5 to 10 parts by mass, and even more preferably 0.7 to 5 parts by mass, based on 100 parts by mass of the structural units derived from the (meth)acrylic acid alkyl ester monomer (A).

[0048] (Other Ingredients) The acrylic adhesive used in the adhesive layer may contain, in addition to the components described above, various additives conventionally used in adhesives, such as plasticizers, softeners, pigments, dyes, dispersants, photopolymerization initiators, and flame retardants.

[0049] (Method of manufacturing acrylic adhesive and adhesive layer) The acrylic adhesive can be obtained by irradiating a pressure-sensitive adhesive composition containing the above-mentioned polymerizable monomer, and optionally a sacrificial anticorrosive metal and a conductive material with light to polymerize the polymerizable monomer. The pressure-sensitive adhesive composition may also contain at least one of the above-mentioned tackifier resin, fine particles, and other components as required. More specifically, first, the polymerizable monomer, the sacrificial corrosion protection metal and conductive material which are blended as necessary, and further the tackifier resin, fine particles, and other components which are blended as necessary are placed in a reaction vessel such as a glass vessel and mixed to obtain a pressure-sensitive adhesive composition. Next, in order to remove dissolved oxygen in the pressure-sensitive adhesive composition, an inert gas such as nitrogen gas is generally supplied to purge the oxygen. Then, the pressure-sensitive adhesive composition is applied onto a release sheet, or onto a support such as a resin film, woven fabric, or nonwoven fabric, and then irradiated with light to polymerize the polymerizable monomer, thereby obtaining a pressure-sensitive adhesive layer. The steps from coating or impregnation with the pressure-sensitive adhesive composition to the step of irradiating with light are preferably carried out in an inert gas atmosphere or in a state in which oxygen is blocked by a film or the like. In the present production method, the pressure-sensitive adhesive composition obtained by mixing the components may be pre-polymerized before being applied to a release sheet, a support or the like in order to increase the viscosity.

[0050] (Rubber adhesive) Next, the rubber-based adhesive used in the adhesive layer will be described. The rubber-based adhesive contains a rubber component and a tackifier resin, and it is preferable to use a styrene-isoprene block copolymer as the rubber component. The styrene-isoprene block copolymer has a diblock ratio of preferably 25 to 70% by mass, more preferably 30 to 65% by mass, and even more preferably 45 to 60% by weight. Here, the diblock refers to a diblock consisting of styrene and isoprene. By setting the diblock ratio within the above range, it becomes easier to increase the adhesive strength. In addition to the diblock, the styrene-isoprene block copolymer also contains one having three or more blocks, such as a triblock consisting of a styrene, isoprene, and styrene block.

[0051] The amount of styrene in the styrene-isoprene block copolymer is not particularly limited, but is preferably 14 to 24% by mass, and more preferably 15 to 18% by mass. If the amount of styrene is 14% by mass or more, the adhesive tends to have high cohesiveness. If the amount of styrene is 24% by mass or less, the cohesive strength becomes moderate and adhesive strength is easily expressed. The molecular weight of the styrene-isoprene block copolymer is not particularly limited, but the mass average molecular weight is preferably 100,000 to 400,000, and more preferably 150,000 to 250,000. The mass average molecular weight here refers to the molecular weight measured in terms of polystyrene by a GPC (gel permeation chromatography) method.

[0052] The tackifier resin used in the rubber-based adhesive can be any of various types, but is preferably a petroleum-based resin, a terpene resin, or a coumarone resin. The tackifier resin may be used alone or in combination of two or more types, but it is preferable to use a petroleum-based resin in combination with at least one selected from a terpene resin and a coumarone resin. Such a combination of tackifier resins makes it easier to improve the adhesive strength. Examples of the petroleum resin include aliphatic petroleum resin (C5 petroleum resin), alicyclic petroleum resin, aromatic petroleum resin, etc., and from the viewpoint of compatibility with the styrene-isoprene block copolymer, aliphatic petroleum resin is preferred. In addition, it is preferable to use a petroleum resin having a softening point of about 90 to 120°C. The terpene resin may have a softening point of about 80 to 120° C., but from the viewpoint of ensuring adhesive strength, it is preferable that the softening point is less than 100° C. The coumarone resin used has a softening point of preferably 110 to 130° C., more preferably 115 to 125° C., in order to ensure cohesive strength.

[0053] The amount of the tackifier resin is preferably 60 to 250 parts by mass, more preferably 100 to 200 parts by mass, and even more preferably 110 to 180 parts by mass, per 100 parts by mass of the rubber component. By setting the amount of the tackifier resin within the above range, it is possible to improve the cohesive force and impart appropriate adhesive strength. When a petroleum-based resin is used in combination with at least one selected from a terpene resin and a coumarone resin, the amount of the petroleum-based resin is preferably 50 to 200 parts by mass, more preferably 60 to 150 parts by mass, and more preferably 60 to 110 parts by mass, relative to 100 parts by mass of the rubber component. On the other hand, the amount of the terpene resin is preferably 10 to 70 parts by mass, more preferably 20 to 60 parts by mass, and even more preferably 30 to 50 parts by mass, relative to 100 parts by mass of the rubber component. Furthermore, the amount of the coumarone resin is preferably 10 to 60 parts by mass, more preferably 15 to 50 parts by mass, and even more preferably 20 to 40 parts by mass, relative to 100 parts by mass of the rubber component. The rubber-based adhesive may contain the above-mentioned fine particles, like the acrylic-based adhesive, and may also contain a sacrificial corrosion protection metal, a conductive material, a softener, an antioxidant, a filler, etc., as necessary.

[0054] (Urethane adhesive) The urethane-based adhesive is not particularly limited, and examples thereof include urethane resins obtained by reacting at least a polyol with a polyisocyanate compound. Examples of the polyol include polyether polyol, polyester polyol, polycarbonate polyol, polycaprolactone polyol, etc. Examples of the polyisocyanate compound include diphenylmethane diisocyanate, tolylene diisocyanate, hexamethylene diisocyanate, etc. These urethane adhesives may be used alone or in combination of two or more. In addition, as the urethane-based adhesive, a urethane resin obtained by reacting a polyurethane polyol with a polyfunctional isocyanate-based curing agent may be used. The polyurethane polyol may be a reaction product of the above-mentioned polyol with a polyisocyanate compound, or a reaction product of a polyol with a polyisocyanate compound and a chain extender such as a diamine. As the polyfunctional isocyanate-based curing agent, any compound having two or more isocyanate groups may be used, and the above-mentioned isocyanate compounds may be used. The urethane-based adhesive may contain the above-mentioned fine particles in addition to the urethane resin, and may also contain a tackifier resin, a sacrificial corrosion-protective metal, a conductive material, a softener, an antioxidant, a filler, etc., as necessary.

[0055] (Silicone adhesive) Examples of silicone-based adhesives include silicone-based adhesives of addition reaction type, peroxide curing type, or condensation reaction type. Among them, addition reaction type silicone-based adhesives are preferably used from the viewpoint of being curable at low temperature in a short time. The addition reaction type silicone-based adhesive is cured when the adhesive layer is formed. When an addition reaction type silicone-based adhesive is used as the silicone-based adhesive, the silicone-based adhesive may contain a catalyst such as a platinum catalyst. The silicone-based adhesive may contain fine particles, and may also contain a crosslinking agent and various additives for controlling adhesive strength.

[0056] (Storage modulus) The pressure-sensitive adhesive layer preferably has a storage modulus of 50,000 to 1,000,000 Pa at 23° C. When the storage modulus at 23° C. is within the above range, when the pressure-sensitive adhesive layer is damaged by an external impact or the like, the force to restore the damaged area (hereinafter also referred to as self-repairing force) becomes strong. As a result, rust generation is suppressed and anticorrosive performance is improved. The storage modulus of the pressure-sensitive adhesive layer at 23° C. is more preferably 200,000 to 800,000 Pa, and even more preferably 300,000 to 600,000 Pa, from the viewpoints of increasing the self-repairing ability and improving the anticorrosive performance. The storage modulus can be calculated by measuring the dynamic viscoelasticity spectrum using, for example, DVA-200 (manufactured by IT Measurement & Control Co., Ltd.) under the following conditions: shear mode: 10 Hz, strain: 0.1%, temperature range: -100°C to 100°C, and heating rate: 10°C / min.

[0057] (Thickness) The thickness of the adhesive layer is preferably 50 to 3000 μm, more preferably 100 to 2000 μm, and even more preferably 120 to 1500 μm. By making the thickness 50 μm or more, the self-repairing ability can be increased, and the anticorrosive properties of the anticorrosive adhesive tape can be improved, and the adhesive strength can also be easily increased. In addition, by making the thickness of the adhesive layer 3000 μm or less, the effect of improving the anticorrosive performance according to the thickness can be obtained.

[0058] <Presence or absence of rust in cyclic corrosion tests> The anticorrosive adhesive tape of the present invention preferably does not rust in a cyclic corrosion test in accordance with JIS K5600-7-9 (General test methods for paints-Part 7: Long-term durability of coating films-Section 9: Cyclic corrosion test method-Salt spray / dry / wet, Cycle D). The absence of rust in the cyclic corrosion test means that the anticorrosive adhesive tape of the present invention has excellent corrosion prevention properties. The occurrence of rust can be suppressed by adjusting the composition, thickness, etc. of the adhesive layer provided in the anticorrosive adhesive tape.

[0059] The occurrence of rust in the cyclic corrosion test is confirmed as follows. A test piece is prepared by attaching the anticorrosive adhesive tape of the present invention to a test plate specified in JIS K5600-7-9. At this time, the test piece is prepared by attaching the anticorrosive adhesive tape so that the adhesive layer of the anticorrosive adhesive tape is in contact with the surface of the test plate. The size of the anticorrosive adhesive tape is 150 mm in length and 70 mm in width. Next, a cut is made on the test piece from the side of the anticorrosive adhesive tape. The cut is made by making two straight cuts that cross each other (i.e., the cuts are made to form an X mark). Each cut should be 70 mm long, and the two cuts should intersect at a 90° angle. The cuts are made using a single-edged cutting tool so that they reach the test plate, which is the base material, as specified in JIS K5600-7-9. After that, the test piece with the notch is subjected to a salt spray test based on cycle D of JIS K5600-7-9, Appendix 1. The test is performed for 28 cycles (total of 168 hours). After the salt spray test, the test piece is observed to check for the presence or absence of rust at the cut area.

[0060] <Adhesive strength after cyclic corrosion test> The anticorrosive adhesive tape of the present invention has an adhesive strength of, for example, 10N / 25mm or more, preferably 20N / 25mm or more, more preferably 25N / 25mm or more, and even more preferably 30N / 25mm or more after a cyclic corrosion test in accordance with JIS K5600-7-9 (General test methods for paints-Part 7: Long-term durability of coatings-Section 9: Cyclic corrosion test method-Salt spray / dry / wet, Cycle D). When the adhesive strength is 20N / 25mm or more, it is possible to ensure sufficient long-term adhesive strength, and the anticorrosive adhesive tape is less likely to peel off from an adherend such as a steel material, thereby preventing a decrease in anticorrosive properties. On the other hand, the upper limit of the adhesive strength is not particularly limited, but from a practical standpoint, it is preferably 200 N / 25 mm or less.

[0061] The adhesive strength of the anticorrosive adhesive tape after the cyclic corrosion test is measured as follows. The anticorrosive adhesive tape of the present invention is applied to a stainless steel plate (SUS plate) to prepare a sample for evaluating adhesive strength. At this time, the adhesive layer of the anticorrosive adhesive tape is applied so as to come into contact with the surface of the SUS plate to prepare a sample for evaluating adhesive strength. The size of the anticorrosive adhesive tape 10 is 100 mm in length and 25 mm in width. Using the adhesive strength evaluation sample, a salt spray test is carried out based on cycle D of JIS K5600-7-9, Appendix 1. The test is carried out for 28 cycles (total of 168 hours). After the salt spray test, the adhesive strength evaluation samples are subjected to a peel test of anticorrosive adhesive tape to measure their adhesive strength. The peel test is performed using a tensile tester at a peel angle of 180° and a speed of 300 mm / min, and the average value of the detected load (N) is taken as the adhesive strength.

[0062] <Composition of anti-corrosion adhesive tape> 1, the anticorrosive adhesive tape of the present invention is preferably a single-sided adhesive tape having a substrate 12 and an adhesive layer 11 provided on one side of the substrate 12. This allows the adhesive layer 11 to be protected by the substrate 12. The anticorrosive adhesive tape in each drawing is used by attaching the surface 11A of the adhesive layer 11 to an adherend as an adhesive surface. Furthermore, although not shown, the anticorrosive pressure-sensitive adhesive tape may be a double-sided pressure-sensitive adhesive tape having a substrate and pressure-sensitive adhesive layers provided on both sides of the substrate.

[0063] As described above, the adhesive layer in the present invention may not contain a metal having a lower potential than iron. In this case, in order to enhance the corrosion resistance of the anticorrosive adhesive tape 10, as shown in FIG. 2, the anticorrosive adhesive tape 10 further includes a metal layer 13 between the substrate 12 and the adhesive layer 11, and the metal layer 13 is preferably a layer of a metal having a lower potential than iron. As the metal having a lower potential than iron, the above-mentioned metals may be used without any particular limitation, but the metal layer 13 is more preferably a layer of zinc. Specifically, the metal layer 13 may be adhered to the substrate 12 by an adhesive or the like, or may be formed on the substrate 12 by sputtering or vacuum deposition. The metal layer 13 may also be a metal film formed by coating the surface of the adhesive layer 11 with a metal by sputtering or vacuum deposition.

[0064] The metal layer 13 is formed directly on the adhesive layer 11 in such a manner that it is sandwiched between the substrate 12 and the adhesive layer 11. That is, the metal constituting the metal layer 13, which has a lower potential than iron, comes into contact with the adhesive layer 11. When the metal, which has a lower potential than iron, comes into contact with the adhesive layer 11, electrons released upon ionization can be easily transferred to the adhesive layer 11, thereby improving the corrosion resistance of the anticorrosive adhesive tape 10. Also in this case, from the viewpoint of the corrosion resistance of the anticorrosive adhesive tape 10, it is preferable that the adhesive layer 11 contains a conductive material other than the metal, which has a lower potential than iron.

[0065] The thickness of the metal layer 13 is preferably 2.5 μm or more. When the thickness of the metal layer 13 is 2.5 μm or more, the metal layer 13 can sufficiently supply electrons due to ionization of the metal in the metal layer 13, and the corrosion prevention adhesive tape 10 can maintain sufficient corrosion prevention. From the viewpoint of enhancing the corrosion prevention of the corrosion prevention adhesive tape 10, the thickness of the metal layer 13 is more preferably 5 μm or more. In addition, from the viewpoint of ensuring the flexibility of the corrosion prevention adhesive tape 10 to improve the handleability of the corrosion prevention adhesive tape 10 and to facilitate the adhesion of the corrosion prevention adhesive tape to an adherend having a complex shape, the thickness of the metal layer 13 is preferably 200 μm or less, more preferably 100 μm or less.

[0066] The anticorrosive adhesive tape of the present invention may have a release sheet attached to the surface of the adhesive layer. The release sheet is preferably peeled off from the adhesive layer before using the anticorrosive adhesive tape to expose the adhesive layer, and the exposed adhesive layer is then attached to an adherend. More specifically, the release sheet is preferably attached to the surface of the adhesive layer opposite to the surface on which the substrate 12 or metal layer 13 is provided, that is, the surface 11A. The release sheet may be a resin film, and it is preferable that the surface to be bonded to the pressure-sensitive adhesive layer is a release-treated surface that has been subjected to a release treatment using a silicone release agent or the like.

[0067] [Applications of anti-corrosion adhesive tape] The anticorrosive pressure-sensitive adhesive tape of the present invention is applied to various adherends and used to prevent corrosion of the adherends. Since the anticorrosive pressure-sensitive adhesive tape of the present invention has excellent adhesive strength and anticorrosive properties, it is preferable to apply it to the surface of an adherend made of various metal materials. The metal material is preferably a metal material containing at least one selected from the group consisting of iron and iron-containing alloys. Specific examples of the iron-containing alloy include alloy steels such as nickel-chromium steel, nickel-chromium-molybdenum steel, chromium steel, chromium-molybdenum steel, and manganese steel, and various steel materials such as carbon steel.

[0068] The anticorrosive adhesive tape of the present invention is preferably used for an adherend having a complex surface shape in a low temperature environment. Specific examples of the adherend include adherends having uneven surfaces, such as a member having a welded portion formed by joining two members by welding. In a member having a welded portion, the welded portion is the convex portion. An example of an adherend having a welded portion is a welded pipe. In a welded pipe, the joint portion connecting two pipes is the welded portion. For an adherend having a welded portion, the anticorrosive adhesive tape may be applied so as to cover the welded portion. Generally, even if an anticorrosive paint is applied to a welded portion, the paint drips before it hardens, resulting in a thinner film thickness after hardening than necessary, which can cause cracks and expose the cracked surfaces, making the welded portion relatively susceptible to rusting, but by applying the anticorrosive pressure-sensitive adhesive tape of the present invention, rusting at such welded portions can be appropriately prevented. Furthermore, even when the anticorrosive pressure-sensitive adhesive tape of the present invention is applied to an adherend having a complex surface shape such as a welded portion in a low-temperature environment, it can ensure high adhesion and conformability without tearing, and therefore can exhibit excellent anticorrosive properties.

[0069] Furthermore, the anti-corrosion adhesive tape of the present invention is less likely to wrinkle even when a topcoat paint is applied on top of it, and therefore can be suitably used in construction in which the anti-corrosion adhesive tape is attached to an adherend, and then a topcoat paint is applied to the adherend to which the anti-corrosion adhesive tape has been applied. The topcoat paint may be a known one, and may be a resin paint using various resins as a binder, or an inorganic paint. The topcoat paint generally contains a pigment. The topcoat paint may be diluted with various organic solvents or water, and is preferably a solvent-based paint diluted with an organic solvent. The topcoat paint may be applied to at least the portion where the adhesive tape is attached (i.e., the surface of the substrate), but generally, it is sufficient to apply the topcoat paint to both the portion where the anticorrosive adhesive tape is attached and the portion where the anticorrosive adhesive tape is not attached.

[0070] The anticorrosive pressure-sensitive adhesive tape of the present invention may be applied to an adherend by pressure bonding to various adherends while heating the tape to, for example, 90 to 150° C., preferably 90 to 130° C. By applying the tape to the adherend while heating, the tape can be adhered to the adherend with higher adhesion and conformability, and high corrosion prevention can be easily ensured. The pressure-sensitive adhesive tape may be heated by a known heating device such as an industrial dryer. The anticorrosive pressure-sensitive adhesive tape of the present invention may be used for repair, which refers to the application of anticorrosive treatment to metal materials such as steel materials constituting existing structures such as bridges, steel towers, viaducts, tanks, plants, piers, and pipes. EXAMPLES

[0071] The present invention will be described in more detail below using examples, but the present invention is not limited to these examples.

[0072] [Method of measurement and evaluation] In each of the Examples and Comparative Examples, the anticorrosive pressure-sensitive adhesive tapes were measured and evaluated by the following methods.

[0073] <Tensile elongation at break> The substrates used to prepare the anticorrosive adhesive tapes of each Example and Comparative Example were subjected to tensile tests in both the MD and TD directions using a tensile testing machine (Tensilon Universal Material Testing Machine, manufactured by A&D Co., Ltd.) in an environment at 5°C and an environment at 23°C, respectively, and the tensile elongation at break was calculated using the following formula. Tensile elongation at break (%) = (LL 0 ) / L 0 ×100 where L is the length of the specimen at break, L 0 is the length of the sample before the tensile test. Of the calculated tensile elongation at break in the MD direction and the tensile elongation at break in the TD direction, the smaller value was determined as the tensile elongation at break of the film. The conditions for measuring the tensile load and the tensile elongation at break were as follows. Dimensions and shape of substrate: 24mm wide x 80mm long strip Chuck distance: 50mm Tensile speed: 300mm / min

[0074] <Difference in tensile load> The substrates used in each of the Examples and Comparative Examples were measured for the tensile load when pulled 2.5% and the tensile load when pulled 0.5% using a tensile tester under an environment of 5°C and an environment of 23°C, respectively, and the difference between the two was calculated. The measurements were performed in each of the MD and TD directions, and the difference between the tensile load when the anticorrosive adhesive tape was pulled 2.5% and the tensile load when the anticorrosive adhesive tape was pulled 0.5% was calculated for each direction. The larger of the calculated differences in the tensile loads in the MD and TD directions was taken as the difference in tensile load. The measurement conditions are shown below. Sample size: width 24mm x length 80mm Chuck distance: 50mm Tensile speed: 300mm / min

[0075] <Solvent resistance> 1. Sample Preparation Cut the sample into a 60 mm square. Measure the length of the diagonal of the cut sample. This length of the diagonal is called diagonal A. 2. Solvent resistance measurement The sample obtained in step 1 above is immersed in xylene for 5 minutes. After immersion, measure the length of the diagonal of the sample. This length of the diagonal is called diagonal B. The dimensional change rate of the base material of the tape was calculated from the lengths of the two diagonals obtained as described above. The formula for calculating the dimensional change rate is as follows. Dimensional change rate (%) = (Diagonal B - Diagonal A) / Diagonal A x 100

[0076] <Storage modulus at 23℃> The storage modulus at 23°C of the adhesive layer of the anticorrosive adhesive tape was calculated by measuring the dynamic viscoelasticity spectrum using a dynamic viscoelasticity measuring device (manufactured by IT Measurement & Control Co., Ltd., product name "DVA-200") under the following conditions: shear mode: 10 Hz, strain: 0.1%, temperature range: -100°C to 100°C, heating rate: 10°C / min.

[0077] <Whether or not rust occurs during cyclic corrosion testing> Using the method described in the specification, the presence or absence of rust in the cut area was visually confirmed in accordance with JIS K5600-7-9 (general test methods for paints - Part 7: Long-term durability of coating films - Section 9: Cyclic corrosion test method - Salt spray / dry / wet, Cycle D).

[0078] <Adhesive strength> 1. Sample Preparation The anticorrosive adhesive tape (width 25 mm, length 100 mm) of each Example and Comparative Example was attached to a SUS plate (width 50 mm, length 125 mm) by rolling a 2 kg roller back and forth twice at a speed of 10±0.5 mm / s to prepare a sample for adhesive strength evaluation. The initial adhesive strength (adhesive strength before the test) was measured using the sample for adhesive strength evaluation. 2. Measurement of adhesive strength Using the sample obtained in 1 above, a combined cycle corrosion resistance test based on cycle D of JIS K5600-7-9 was carried out for 168 hours. The sample was then fixed to the chuck of a tensile tester ("Tensilon Universal Material Tester" manufactured by A&D Co., Ltd.). After that, in an environment of 23°C and 50 RH%, the corrosion-resistant adhesive tape was pulled 60 mm or more at a peel angle of 180° and a speed of 300 mm / min, and the average value of the load (N) detected by the load cell was recorded and used as the adhesive strength.

[0079] <Practical evaluation of convexity tracking ability> The convex portion followability was evaluated in an environment at a temperature of 5° C. according to the procedures 1. to 4. below. 1. As shown in FIG. 3, anticorrosive adhesive tape 10 (30 mm square) was attached to adhesion surface 20A of L-shaped SUS plate 20 so that height h from the corner and width t were 2 mm. 2. A squeegee was pressed against the portion of the anticorrosive adhesive tape 10 that was not attached to the L-shaped SUS plate 20 . 3. After the pressing in 2 above, the height h was measured and visual inspection was performed to check for the occurrence of tears in the anticorrosive adhesive tape 10. If tears occurred in the anticorrosive adhesive tape 10 during the pressing, the height h was recorded as 2 mm. 4. Based on the measured value of the height h obtained in 3 above, the convex portion-following ability of the anticorrosive adhesive tape 10 was evaluated according to the following criteria. ◯: No lifting occurred (height h was 0 mm), and no tearing occurred in the anticorrosive adhesive tape 10. △·· Lifting occurred (height h is greater than 0 mm) or the anticorrosive adhesive tape 10 was torn × Lifting occurred (height h was greater than 0 mm) and the anticorrosive adhesive tape 10 was torn.

[0080] <Evaluation of topcoat coating> A rolled steel material for general construction (SS400) measuring 70 mm long x 150 mm wide was prepared. Then, anticorrosive adhesive tapes (width 60 mm, length 140 mm) of each Example and Comparative Example were attached to the rolled steel material. The rolled steel material to which the anticorrosive adhesive tape was attached was painted with a topcoat paint (manufactured by Dai Nippon Toryo Co., Ltd., product name "V Flon #100H Smile Topcoat") using a brush (see FIG. 4). After the topcoat paint applied to the rolled steel material was dried for 24 hours, the occurrence of wrinkles in the anticorrosive adhesive tape was visually observed. ○ There were no wrinkles in the anti-corrosion adhesive tape. × There were wrinkles in the anti-corrosion adhesive tape.

[0081] <Weatherability (gloss retention)> The anticorrosive adhesive tape (width 25 mm, length 100 mm) of each Example and Comparative Example was attached, and the specular gloss of the surface of the tape was measured from the substrate side using a gloss meter (manufactured by Horiba, Ltd., product name: "IG-340"). The specular gloss was measured using a gloss meter with a geometric condition of 60° in accordance with JIS K 5600-4-7. The specular gloss obtained by this measurement is designated as specular gloss A. Then, the tape was subjected to an accelerated weather resistance test for 500 hours in accordance with cycle A in JIS K 5600-7-7. After the accelerated weather resistance test was performed, the specular gloss of the substrate of the tape was measured by the same method as that performed before the test. The specular gloss obtained by the measurement after the test is designated as specular gloss B. The gloss retention of the tape substrate was calculated from the two types of specular gloss thus obtained. The formula for calculating the gloss retention is as follows: Gloss retention rate (%) = (Specular gloss B / Specular gloss A) x 100 ◎ Gloss retention rate of 90% or more ○ Gloss retention is between 80% and 90% × Gloss retention is less than 80%

[0082] <Practical evaluation of peeling> Anticorrosive adhesive tapes (25 mm wide, 100 mm long) of each of the Examples and Comparative Examples were attached to a SUS plate (50 mm wide, 125 mm long) and cured at 23°C for 3 days to prepare samples for peeling evaluation. Water was sprayed for 5 minutes at a water pressure of 8 MPa toward the longitudinal end side of the anticorrosive adhesive tape from a spraying position diagonally above the anticorrosive adhesive tape in the peeling evaluation sample. The position where water was sprayed (spraying position) was a position where the angle between the line connecting the spraying position and the center part of the end of the anticorrosive adhesive tape and the SUS plate was 30°, and directly above a point 5 cm horizontally away from the center part of the end of the anticorrosive adhesive tape. The distance that the anticorrosive adhesive tape had peeled off after the water spraying was measured and evaluated according to the following criteria. ◎ Peeling distance is 0 mm or more and less than 15 mm ○ Peeling distance is 15mm or more but less than 25mm × Peeling distance is 25mm or more

[0083] [Materials used] In each of the examples and comparative examples, the following materials were used.

[0084] <Adhesive layer> 2-Ethylhexyl acrylate n-Butyl acrylate Acrylic Acid Olefin polymer: Product name "L-1253", manufactured by Kuraray Co., Ltd., hydrogenated polybutadiene having a (meth)acryloyl group at one end Tackifier resin 1: Product name "Alcon P140", manufactured by Arakawa Chemical Industries, Ltd., hydrogenated petroleum resin, softening point 140°C Tackifier resin 2: Product name "Alcon P100", manufactured by Arakawa Chemical Industries, Ltd., hydrogenated petroleum resin, softening point 100°C Fine particles: Product name "Cellstar Z-27", manufactured by Tokai Kogyo Co., Ltd., glass balloon Zinc particles: Sakai Chemical Industry Co., Ltd., product name "Zinc powder #40", average particle size: 50 μm Carbon nanotubes (CNT): JEIO, product name "JENOTUBE8A", average diameter 6-9nm, average length 100-200μm Dispersant: Sekisui Chemical Co., Ltd., product name "S-LEC BX-L", polyvinyl butyral resin Crosslinking agent: Product name "TEAI-1000", manufactured by Nippon Soda Co., Ltd. Polymerization initiator: 2,2-dimethoxy-2-phenylacetophenone

[0085] <Film> F124: Multilayer film with a structure of low-density polyethylene / nylon / linear low-density polyethylene, product name "Diamilon MF F124", manufactured by Mitsubishi Chemical Corporation F119: Multilayer film with a structure of low-density polyethylene / nylon / linear low-density polyethylene, product name "Diamilon MF F119", manufactured by Mitsubishi Chemical Corporation Lamitop 45: A multi-layer film with a structure of low-density polyethylene / nylon / linear low-density polyethylene, product name "Lamitop 45", manufactured by Okura Kogyo Co., Ltd. Lamitop 70: A multi-layer film with a structure of linear low-density polyethylene / nylon / linear low-density polyethylene, product name "Lamitop 70", manufactured by Okura Kogyo Co., Ltd. C691: Multilayer film with a nylon / EVAL / linear low-density polyethylene structure, product name "Diamilon MF C691", manufactured by Mitsubishi Chemical Corporation MBS121E: Acrylic resin film, product name "ACRYPLEN MBS121E", manufactured by Mitsubishi Chemical Corporation Purelon: A multi-layer film with a polyethylene / polypropylene / polyethylene structure, product name "Purelon CP-WGF", manufactured by Sumika Sekisui Film Co., Ltd. CZ: Nylon 6, product name "Diamilon CZ", manufactured by Mitsubishi Chemical Corporation LLDPE: Linear low-density polyethylene, manufactured by Sakai Chemical Industry Co., Ltd. Soft acrylic sheet: Soft acrylic resin film, product name "Soft Acrylic Sheet", manufactured by Tatsuta Chemical Co., Ltd. 50NS: Fluorine resin film, product name "Aflex 50NS", manufactured by AGC Inc. Some of the resin films used had a fluororesin coating on the surface. The coating was formed on the side of the substrate opposite to the side on which the pressure-sensitive adhesive layer was provided. The presence or absence of the coating is shown in the table.

[0086] [Examples 1 to 13, Comparative Examples 1 to 4] A pressure-sensitive adhesive composition was prepared according to the formulation shown in Tables 1 and 2. The pressure-sensitive adhesive composition was purged with nitrogen to remove dissolved oxygen. The pressure-sensitive adhesive composition was then applied onto a film. Then, the pressure-sensitive adhesive composition was applied to a film at an ultraviolet irradiation intensity of 5 mW / cm. 2 The lamp intensity of the chemical lamp was adjusted so that the ultraviolet rays were irradiated for 15 minutes to obtain an anticorrosive adhesive tape. The components of the adhesive composition and the film coated with the adhesive composition are as described above.

[0087] [Table 1]

[0088] [Table 2]

[0089] As is clear from the above examples, the anti-corrosion adhesive tapes produced in Examples 1 to 13, which satisfy the requirements of the present invention, have excellent adhesion to adherends having complex surface shapes in low-temperature environments, and are able to suppress the occurrence of wrinkles caused by painting. In contrast, the anticorrosive adhesive tapes produced in Comparative Examples 1 to 4 did not satisfy the requirements of the present invention, and therefore either had poor adhesion to adherends having complex surface shapes in low-temperature environments, or wrinkles occurred due to painting. [Explanation of symbols]

[0090] 10. Anticorrosive adhesive tape 11 Adhesive layer 12 Base material 13 Metal layer 20 L-shaped SUS plate 20A Adhering surface 30 General structural rolled steel (SS400) 40 Topcoat paint h Height t width

Claims

1. A corrosion prevention adhesive tape comprising a substrate and an adhesive layer provided on at least one surface of the substrate, In an environment of a temperature of 5°C, the difference between the tensile load when the substrate is elongated by 2.5% and the tensile load when the substrate is elongated by 0.5% is 1.3 N / mm or less; The tensile elongation at break of the substrate measured in an environment at a temperature of 5°C is 100% or more, A corrosion-preventive adhesive tape in which the dimensional change rate of the substrate is 3% or less after the substrate is immersed in xylene for 5 minutes.

2. 2. The corrosion-preventive adhesive tape according to claim 1, which does not develop rust in a cyclic corrosion test in accordance with Cycle D of JIS K5600-7-9 and has an adhesive strength of 20 N / 25 mm or more after the cyclic corrosion test.

3. 2. The anticorrosion adhesive tape according to claim 1, wherein the substrate has a gloss retention rate of 80% or more after 500 hours of an accelerated weather resistance test in accordance with Cycle A of JIS K5600-7-7.

4. 2. The anticorrosion adhesive tape according to claim 1, wherein the thickness of the substrate is 20 to 1000 μm.

5. 2. The anticorrosion adhesive tape according to claim 1, wherein the substrate is a resin film having a coating film on the surface thereof.

6. The corrosion-resistant adhesive tape according to claim 5, wherein the resin film is at least one film selected from the group consisting of a multilayer resin film consisting of a polyamide-based resin layer and a polyolefin-based resin layer, a soft acrylic-based resin film, and a fluororesin film.

7. In a room temperature environment, the difference between the tensile load when the substrate is elongated by 2.5% and the tensile load when the substrate is elongated by 0.5% is 1.3 N / mm or less; 2. The anticorrosion adhesive tape according to claim 1, wherein the tensile elongation at break of the substrate measured under room temperature conditions is 100% or more.

8. 2. The anticorrosion adhesive tape according to claim 1, wherein the adhesive layer contains a metal having a lower potential than iron.

9. 9. The corrosion-preventive adhesive tape according to claim 8, wherein the metal having a lower potential than iron is zinc.

10. The corrosion-preventive adhesive tape according to claim 8 , wherein the adhesive layer contains a conductive material other than the metal having a lower potential than iron.

11. The corrosion-preventive adhesive tape according to claim 10, wherein the conductive material is carbon nanotubes.

12. 2. The anticorrosion adhesive tape according to claim 1, wherein the adhesive layer is formed from an acrylic adhesive.

13. 2. The corrosion-preventive adhesive tape according to claim 1, further comprising a metal layer between the substrate and the adhesive layer, the metal layer being a layer of a metal having a lower potential than iron.

14. The corrosion-preventive pressure-sensitive adhesive tape according to claim 13, wherein the metal layer is a zinc layer.

15. 2. The anticorrosion adhesive tape according to claim 1, wherein the thickness of the adhesive layer is 50 to 3000 μm.

16. 2. The anticorrosion adhesive tape according to claim 1, wherein the pressure-sensitive adhesive layer has a storage modulus of 50,000 to 1,000,000 Pa at 23°C.

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