Pressure-sensitive adhesive tape, article, and method for disassembling article

Abstract

To provide a pressure-sensitive adhesive tape which can be peeled by heating in a short time, can prevent an adherend from being thermally damaged, and can be easily peeled by heating, to provide an article in which at least two adherends are bonded to each other through the pressure-sensitive adhesive tape, and to provide a method for disassembling the article.SOLUTION: An adhesive tape comprising at least an adhesive layer, a heating element, and a melting and softening layer adjacent to the heating element in this order, wherein the heating element has an average thickness of 2 μm or more and 200 μm or less and is formed into a sheet by binding a conductive filler.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an adhesive tape that can be used in various fields such as the manufacture of electronic devices, an article having a structure bonded by the adhesive tape, and a method for dismantling the article. [Background technology]

[0002] As a joining means with excellent workability and high adhesive reliability, adhesive tapes are used in various industrial fields such as office equipment, IT products, home appliances, and automobiles for fixing parts, temporarily fixing parts, and labeling to display product information. In recent years, from the perspective of protecting the global environment, there has been an increasing demand in various industrial fields such as home appliances and automobiles for the recycling and reuse of used products. When recycling or reusing various products, it is necessary to remove adhesive tape used to secure parts or labels. However, because adhesive tape is found in various places within the product, there is a demand for a simple removal process that reduces labor costs.

[0003] In order to separate adherends from each other, for example, a hot melt adhesive composition has been proposed that dissolves quickly in a short time by electromagnetic induction heating (see, for example, Patent Document 1). As a method for separating adherends, a method for demolishing buildings has been proposed in which a metal base material is heated using an electromagnetic induction heating device, the adhesive between this base material and the interior material is heated and foamed, causing it to separate, and the interior material is then peeled off from the metal base material (see, for example, Patent Document 2). Also proposed is a double-sided adhesive tape having a heat conductive layer that can be easily dismantled by contacting it with a heat generating source and directly heating the heat conductive layer (see, for example, Patent Document 3). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2002-188068 [Patent Document 2] Japanese Patent Application Laid-Open No. 2006-200279 [Patent Document 3] Japanese Patent Application Laid-Open No. 2016-108394 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in conventional methods of peeling and dismantling by heating, heat is applied from the outside, and if an attempt is made to generate the amount of heat required to peel the adhesive tape from a heating element, the generated heat may cause thermal deterioration or thermal damage to the adherend. On the other hand, if an attempt is made to suppress thermal deterioration or thermal damage to the adherend, the amount of heat generated may decrease, causing the adhesive tape to not be heated sufficiently, making peeling difficult. Therefore, there is a demand for adhesive tapes that can be used to fasten adherends such as rigid bodies together, and that have the ability to dismantle and reuse the adherend components. In particular, there is a demand for adhesive tapes that can be easily dismantled and peeled off by heating.

[0006] An object of the present invention is to provide a pressure-sensitive adhesive tape that can be heated and peeled off in a short time, that can prevent thermal damage to an adherend, and that is easy to operate for heating and peeling off, an article having a structure bonded by the pressure-sensitive adhesive tape, and a method for dismantling the article. [Means for solving the problem]

[0007] The present invention relates to the following (1) to (14). (1) A pressure-sensitive adhesive tape comprising, at least in this order, an adhesive layer, a heating element, and a melt-softening layer adjacent to the heating element, wherein the heating element has an average thickness of 2 μm or more and 200 μm or less, and wherein the heating element is formed into a sheet by binding conductive filler. (2) The pressure-sensitive adhesive tape according to (1), wherein the heating element has a volume resistivity of 50 μΩ·cm or more at 20°C. (3) The pressure-sensitive adhesive tape according to (1) or (2), wherein the heating element is formed by binding fibrous or particulate conductive filler into a sheet and further impregnating it with a binder. (4) The pressure-sensitive adhesive tape according to any of (1) to (3), wherein the heating element is formed by binding fibrous or particulate conductive filler and an organic filler into a sheet. (5) The pressure-sensitive adhesive tape according to any of (1) to (4), wherein the heating element is formed into a sheet by sintering fibrous or particulate conductive filler. (6) The pressure-sensitive adhesive tape according to any one of (1) to (5), wherein the conductive filler is selected from the group consisting of metals, alloys, and carbon. (7) The pressure-sensitive adhesive tape according to any one of (1) to (6), wherein, in a plan view, the heating element has a pair of extending portions extending from the outer peripheries of the pressure-sensitive adhesive layer and the melt-softening layer. (8) The pressure-sensitive adhesive tape according to any one of (1) to (7), wherein the melt-softening layer further has an adhesive layer on the side opposite to the side adjacent to the heating element. (9) The pressure-sensitive adhesive tape according to any one of (1) to (8), wherein the melt-softening layer is peelable by heating. (10) The pressure-sensitive adhesive tape according to any one of (1) to (9), wherein the heating element is an electric conductor that generates heat when electricity is applied thereto and is peeled off by the heat generated by the electric conductor. (11) An article comprising at least two adherends and the pressure-sensitive adhesive tape according to any one of (1) to (10) between the two adherends, wherein the two adherends are bonded via the pressure-sensitive adhesive tape. (12) The article according to (11), wherein, in a plan view, the heating element constituting the pressure-sensitive adhesive tape has a pair of extension portions extending from the outer periphery of the adherend. (13) The method for dismantling an article according to (11) or (12), wherein the melt-softening layer is melted and / or softened by heating the heating element to separate the two adherends.(14) A method for dismantling articles according to (13), in which the heating element is heated by resistance heating, the heating element is electrically connected to a power source, electricity is passed from the power source to the heating element, and the melt-softening layer is melted and / or softened by resistance heating to separate the two adherends. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a pressure-sensitive adhesive tape that can be peeled off by heating in a short time, can prevent thermal damage to an adherend, and is easy to operate for peeling off by heating. Furthermore, the present invention can provide an article in which at least two adherends are bonded via the adhesive tape, and a method for dismantling the article, which can suppress thermal degradation of adherends such as electronic components, making them reusable and facilitating dismantling work. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a schematic cross-sectional view illustrating an example of the pressure-sensitive adhesive tape of the present invention. [Figure 2] FIG. 2 is a schematic cross-sectional view showing another example of the pressure-sensitive adhesive tape of the present invention. [Figure 3] FIG. 2 is a schematic plan view showing another example of the pressure-sensitive adhesive tape of the present invention. [Figure 4] 1A and 1B are schematic plan views showing examples of patterns of heating elements in the pressure-sensitive adhesive tape of the present invention. [Figure 5] FIG. 2 is a schematic cross-sectional view showing another example of the pressure-sensitive adhesive tape of the present invention. [Figure 6] 1 is a schematic plan view showing an example of an article of the present invention. [Figure 7] 1 is a schematic cross-sectional view showing an example of an article of the present invention. [Figure 8] 1 is a diagram schematically illustrating a method for dismantling an article according to the present invention. [Figure 9] 1 is a schematic plan view of the pressure-sensitive adhesive tape of Example 1. FIG. [Figure 10] 1 is a schematic cross-sectional view of the pressure-sensitive adhesive tape of Example 1. FIG. [Figure 11] 1 is a schematic plan view showing an article of an example and an evaluation method. FIG. [Figure 12]FIG. 1 is a schematic front view showing an article of an example and an evaluation method. [Figure 13] 1 is a schematic side view showing an example article and an evaluation method. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments of the present invention will be described in detail. In this specification, a numerical range indicated using "to" indicates a range that includes the numerical values ​​before and after "to" as the minimum and maximum values, respectively.

[0011] 1. Adhesive tape The present invention provides an adhesive tape having, at least in this order, an adhesive layer, a heating element, and a melt-softening layer adjacent to the heating element, wherein the heating element has an average thickness of 2 μm or more and 200 μm or less, and the heating element is formed into a sheet by binding conductive filler. The pressure-sensitive adhesive tape of the present invention can be used as an easily dismantlable pressure-sensitive adhesive tape that can be easily separated or dismantled after a certain period of time has passed after being applied to an adherend and fixing the adherends together. Because the pressure-sensitive adhesive tape of the present invention has the above-mentioned configuration, it is not limited by the material of the adherend, maintains high adhesive strength when fixing adherends together, and can be easily separated or disassembled by heating when separating or dismantling the adherends. Note that "separation or dismantling" will hereinafter also be referred to simply as "dismantling."

[0012] The pressure-sensitive adhesive tape of the present invention has a heating element, which is generated by directly passing electricity through the heating element or by heating means such as induction heating, infrared radiation, or microwave irradiation with external energy, thereby melting or softening the melt-softening layer adjacent to the heating element. In the present invention, since deterioration of the adherend due to external energy irradiation can be suppressed and the article can be dismantled with the adhesive tape embedded in the article, it is preferable that the heating element is an electrically conductive element that generates heat when electricity is passed through it, and it is preferable that the adhesive tape of the present invention be peeled off by the heat generated by the electrically conductive element. Here, in the pressure-sensitive adhesive tape of the present invention, the heating element has an average thickness of 2 μm or more and 200 μm or less, and the heating element is a sheet formed by binding conductive fillers, so that the volume resistivity can be increased. Specifically, by designing the heating element to have a thin average thickness, the volume resistivity tends to be increased. That is, the amount of heat generated by the heating element can be increased with the application of a smaller current, and this effect allows the thermoplastic resin constituting the melt-softening layer to be melted or softened efficiently. Therefore, the pressure-sensitive adhesive tape of the present invention has sufficient initial adhesive strength at around room temperature (0 to 40°C), and the adhesive strength decreases as it is heated by the heat from the heating element, and the residual adhesive strength after electrification is small relative to the initial adhesive strength, and the rate of decrease in adhesive strength due to electrification is large. Therefore, articles made using the pressure-sensitive adhesive tape of the present invention have excellent dismantling properties. Furthermore, even if a worker accidentally comes into contact with a live part during dismantling work, the pressure-sensitive adhesive tape of the present invention can generate a sufficient amount of heat at a low current that does not physically harm the worker, and therefore the dismantling method of the present invention is excellent in work safety. In other words, the adhesive tape of the present invention generates heat inside the tape, so that when an article having at least two adherends bonded via the adhesive tape of the present invention is dismantled, the article can be easily dismantled while reducing thermal damage to the adherends.

[0013] Furthermore, even in the case of articles to which electronic components that are built into equipment and completely shielded from the outside and inaccessible to adhesive tape are attached, the electronic components can be easily disassembled without the need for large-scale equipment. In particular, when the adhesive tape is thermally disassembled using the drive current within the electronic components while the electronic components are built into the electronic device, thermal deterioration of the circuits within the electronic components can be prevented, and thermal peeling can be performed without the need for external equipment, making the disassembly work easier.

[0014] The embodiment in which the adhesive tape of the present invention is "made peelable by heating" may be an embodiment in which the adhesive tape, particularly the melt-softening layer itself, melts or softens upon heating, causing cohesive failure within the melt-softening layer, and causing part or all of the adhesive tape to peel off from the adherend; or an embodiment in which the adhesive tape, particularly the melt-softening layer itself, melts or softens upon heating, causing a decrease in its adhesive strength, causing peeling (interfacial failure) between the melt-softening layer and the layer adjacent to the melt-softening layer or the adherend, making part or all of the adhesive tape peelable from the adherend. Furthermore, when the pressure-sensitive adhesive tape is peeled off by heating, the melt-softening layer may peel off from the adherend as a whole, or only a portion of the melt-softening layer may peel off from the adherend. Furthermore, the adhesive layer constituting the adhesive tape of the present invention is composed of a component that is less likely to melt or soften by heating than the component constituting the melt-softening layer, as will be described later. Therefore, in the pressure-sensitive adhesive tape of the present invention, the melt-softenable layer is heated by generating heat from the heating element, thereby selectively melting or softening the layer, thereby making the tape peelable. The configuration of the pressure-sensitive adhesive tape of the present invention will be described below.

[0015] [Heater] The heat generating element in the pressure-sensitive adhesive tape of the present invention has an average thickness of 2 μm or more and 200 μm or less, and is a heat generating element formed into a sheet by binding conductive fillers. The heating element in the pressure-sensitive adhesive tape of the present invention preferably exhibits a temperature rise of 120°C or higher, more preferably 150°C or higher, when a current of 0.5 A is applied to the heating element for 30 seconds. When the adhesive tape of the present invention has a heating element having such properties in its configuration, when an article in which at least two adherends are adhered via the adhesive tape of the present invention is dismantled, the article can be easily dismantled while reducing thermal damage to the adherends.

[0016] The conductive filler is preferably a filler selected from the group consisting of metals, alloys, and carbon. Examples of metals include silver, iron, copper, aluminum, nickel, titanium, chromium, platinum, gold, palladium, rhodium, iridium, and ruthenium. Examples of alloys include stainless steels such as SUS410, SUS304, and SUS430, and alloys of two or more metals such as brass, cupronickel, bronze, nichrome, and nickel silver. Examples of carbon include carbon nanomaterials such as graphite, graphene, graphene oxide, carbon nanotubes, graphene platelets, and carbon nanofibers. The conductive filler may be used alone or in combination of two or more kinds. Among these, a filler selected from the group consisting of silver, stainless steel, and carbon is more preferable as the conductive filler.

[0017] The conductive filler is preferably in the form of fibers or particles. When the conductive filler is fibrous, the average fiber diameter is preferably in the range of 0.01 μm to 30 μm, more preferably in the range of 0.02 μm to 20 μm, from the viewpoint of facilitating the production of a fibrous conductive filler in the form of a nonwoven fabric, as described below. The cross-sectional shape perpendicular to the longitudinal direction of the fiber may be any of circular, elliptical, approximately rectangular, irregular, etc. In this specification, the "average fiber diameter" is the average area diameter obtained by calculating the cross-sectional area of ​​20 fibrous conductive fillers photographed under a microscope in any cross section perpendicular to the longitudinal direction, and then calculating the diameter of a circle having the same area as the cross-sectional area. When the conductive filler is fibrous, the average fiber length is preferably in the range of 0.01 mm to 10 mm, more preferably in the range of 0.03 mm to 5 mm, from the viewpoint of easily improving the homogeneity of the fibrous conductive filler formed into a nonwoven fabric, as will be described later. In this specification, the "average fiber length" is the average value obtained by measuring 20 fibers of the fibrous conductive filler photographed under a microscope. When the conductive filler is fibrous, the aspect ratio thereof is preferably 33 to 10,000, and more preferably 150 to 1,500.

[0018] When the conductive filler is in the form of particles, the shape of the particles is not particularly limited, and examples thereof include spherical, scale-like, lamellar, leaf-like, columnar, equiaxed, leaf-like, plate-like, wedge-like, and rosette-like shapes. When the conductive filler is particulate, its particle size (average particle size) is preferably in the range of 0.01 μm to 500 μm, more preferably in the range of 0.02 μm to 200 μm, and even more preferably in the range of 0.05 μm to 100 μm, from the viewpoints of easily maintaining the strength of the heating element in a bound state and easily controlling the volume resistivity of the heating element. The particle size of the particulate conductive filler is the median diameter (D50) value measured with a laser diffraction / scattering particle size distribution analyzer.

[0019] Methods for bonding the conductive filler include sintering, chemical etching, laser welding, IH heating, chemical bonding, and thermal bonding. When the conductive filler is in the form of silver nanoparticles or silver nanowires dispersed in a dispersion medium, such as silver nanoink, the ink can be applied to a substrate, dried, and then the above-mentioned bonding method can be applied to form a sheet of conductive filler, i.e., a heating element. Here, the conductive filler being bound refers to a state in which the conductive filler is physically fixed, and the portion where the conductive filler is physically fixed is called a bound portion. In the bonded portion, the conductive fillers may be directly fixed to each other, or some of the conductive fillers may be indirectly fixed to each other via a component other than the metal component. Among these, sintering is preferred as a bonding method, from the viewpoints that bonding is easily achieved reliably, the conductive filler particles are fixed together, and the coefficient of variation (CV value) of the basis weight of the heating element as specified in JIS Z8101 (ISO3534) is easily stabilized. That is, the heating element is preferably a heating element formed by sintering fibrous or particulate conductive filler into a sheet, and more preferably a sintered fibrous conductive filler formed into a nonwoven fabric. Methods for turning fibrous conductive fillers into nonwoven fabrics include dry methods in which fibrous conductive fillers or webs mainly composed of fibrous conductive fillers are compression-molded by carding, air-laid, etc.; and wet paper-making methods in which fibrous conductive fillers are dispersed in water to prepare a slurry, which is then paper-formed into a sheet and subjected to the processes of dehydration, pressing, and drying. Sintering is preferably carried out in a vacuum or a non-oxidizing atmosphere at a temperature equal to or lower than the melting point of the material (metal, alloy) that constitutes the conductive filler.

[0020] The heating element in the pressure-sensitive adhesive tape of the present invention is more preferably a heating element obtained by binding fibrous or particulate conductive fillers to form a sheet, which is then impregnated with a binder. In the case of such a heating element, the adhesive strength between the adhesive layer and the heating element, and between the melt-softening layer and the heating element, tends to increase, which is preferable from the viewpoint of easily improving the performance of the pressure-sensitive adhesive tape. Examples of such binders include organic binders such as epoxy resins, acrylonitrile-butadiene copolymer resins, unsaturated polyester resins, phenol resins, melamine resins, polyimide resins, polyurea resins, and polyurethane resins, and inorganic binders such as colloidal silica, water glass, and sodium silicate. Among these, acrylonitrile-butadiene copolymer resins and phenol resins are preferred, and resol-type phenol resins are more preferred. A carbon-based sheet may be used as a heating element, which is made by binding fibrous or particulate conductive fillers into a sheet and then impregnating the sheet with a binder. Examples of carbon-based sheets include graphite sheets using carbon particles such as carbon fiber and graphite as conductive fillers and the above-mentioned resins, preferably resol-based phenolic resins, as binders.

[0021] The heat generating element in the pressure-sensitive adhesive tape of the present invention is also preferably a heat generating element formed by binding the above-mentioned fibrous or particulate conductive filler and organic filler into a sheet. In the case of such a heating element, it is easy to control the volume resistivity of the heating element within a suitable range described below, and the strength of the heating element tends to increase, which is preferable from the viewpoint that the performance of the pressure-sensitive adhesive tape is easily improved. Examples of such organic fillers include cellulose-based fillers derived from natural materials such as wood pulp, rice husks, cotton, bamboo, kenaf, and hemp; and fillers of heat-resistant resins such as liquid crystal polyester, aromatic polyamide, and nylon. The organic filler may be fibrous or particulate, and the preferred ranges of the average fiber diameter, average fiber length, and average particle diameter are preferably the same as those of the conductive filler described above. When the heating element is formed by binding fibrous or particulate conductive filler and organic filler into a sheet, the content of the organic filler in the entire heating element is preferably in the range of 0.01 to 60 mass%, more preferably in the range of 0.01 to 40 mass%.

[0022] Examples of heating methods and heating elements include resistance heating, electromagnetic induction heating, infrared heating, microwave heating, and heat conduction. Among these, resistance heating is preferred from the viewpoint that the melt-softening layer can be sufficiently softened or melted with even a small amount of energy, making it possible, for example, to thermally dismantle the adhesive tape using a driving current within an electronic component when the adhesive tape is built into an electronic device, and that there is no need to heat the heating element using an external heat source via the adherend, thereby preventing excessive heating of the adherend.

[0023] Here, "resistance heating" is a type of electrical heating method in which an electric current is passed through a resistive current-carrying body (heat-generating body) and the Joule heat generated is used to heat the current-carrying body. When a steady current is passed through a current-carrying body, the amount of Joule heat generated within a certain period of time is proportional to the square of the magnitude of the current and the resistance of the conductor (Joule's law). Current-carrying bodies have a resistance value (volume resistivity, etc.) specific to their material. "Electromagnetic induction heating" is a type of non-contact heating method of electric heating, also known as high-frequency induction heating. When a resistive current-carrying body (heat-generating body) is placed in the magnetic field generated by passing a high-frequency current (alternating current) through a coiled conductor, current flows through the current-carrying body due to the principle of electromagnetic induction, and the current-carrying body is heated by the resulting Joule heat. "Infrared heating" and "microwave heating" are non-contact heating methods that utilize radiant heat energy using electromagnetic waves in specific wavelength ranges, such as infrared rays and microwaves. The atomic bonds and molecules that make up a substance undergo thermal vibrations (molecular movement and crystal lattice vibrations) that correspond to the temperature of the substance itself, and when electromagnetic waves with a wavelength corresponding to this vibration frequency are absorbed, the molecular vibrations become more intense and heat is generated. "Heat conduction" is a heating method that utilizes the heat transfer phenomenon in which heat is transferred from a high-temperature side to a low-temperature side inside a solid. Heat can be transferred by directly contacting the heat source with a material that has excellent thermal conductivity.

[0024] When the heating means is resistance heating, the volume resistivity of the heating element at 20°C is preferably 50 μΩ·cm or more, more preferably 70 μΩ·cm or more, and even more preferably 100 μΩ·cm or more. To avoid excessively high voltages when energizing the heating element, the volume resistivity of the heating element at 20°C is preferably 100,000 μΩ·cm or less, more preferably 20,000 μΩ·cm or less, even more preferably 10,000 μΩ·cm or less, and particularly preferably 5,000 μΩ·cm or less. Specifically, the volume resistivity of the heating element can be in the range of 50 to 100,000 μΩ·cm, 50 to 20,000 μΩ·cm, 70 to 10,000 μΩ·cm, or 100 to 5,000 μΩ·cm. If the volume resistivity of the heating element is 50 μΩ·cm or more, when the heating element is connected to the wiring circuit within an electronic device and the driving current of the electronic device is passed through the heating element during dismantling of the item, only the adhesive tape can be heated, preventing high-temperature deterioration of the wiring circuit. Furthermore, by using a heating element whose volume resistivity falls within the above range, the melt-softening layer can be melted or softened in a short time, thereby shortening the dismantling time. Furthermore, when using a drive current within an electronic component, it is possible to prevent the electronic circuit and connecting parts from being excessively heated due to current flow through the heating element, thereby preventing thermal degradation of the electronic component.

[0025] The volume resistivity of the heating element can be measured at 20°C using a low resistivity meter (manufactured by Nitto Seiko Analytech Co., Ltd., product name "Loresta-AX MCT-T370") and a four-point probe (manufactured by Nitto Seiko Analytech Co., Ltd., product name "ASP Probe MCP-TP03P") in accordance with JIS K 7194. Measurement is performed at one point, and 4.532 is used as the correction coefficient for resistivity.

[0026] The heating element formed into a sheet by binding conductive fillers may be in a mesh shape, but is usually in a planar shape. A planar heating element can sufficiently adhere to the melt-softened layer in contact with the heating element before electricity is applied, and generates heat from the surface when electricity is applied, making the heating element itself less likely to be damaged or broken when electricity is applied. As the planar heating element, a heating element in which the above-mentioned fibrous or particulate conductive filler, preferably a fibrous conductive filler in the form of a nonwoven fabric, is bound by sintering to form a sheet is preferred, and a heating element in which fibrous or particulate conductive filler is bound to form a sheet and further impregnated with a binder is more preferred.

[0027] The planar heating element may be formed in a pattern, or may be in a strip or line shape (see also FIG. 4 described later). A strip or line heating element is advantageous in that it has high heat generation efficiency and a small contact area with the adherend, making it easy to peel off. In this case, the length of the heating element in the minor axis direction (strip width or line width) is preferably 0.5 to 20 mm, more preferably 1 to 10 mm, and even more preferably 2 to 5 mm.

[0028] When the planar heating element is patterned (has a pattern shape), the distance between the terminals (terminals for connecting to a power source) of the heating element can be increased, and the resistance can be increased. Therefore, the heat generation efficiency of the planar heating element is increased, and the pressure-sensitive adhesive tape of the present invention can be peeled off in a short time. When the planar heating element is in a patterned form, the pattern width is not particularly limited, and can be the same as the preferred range of the band width described above.

[0029] The planar heating element may be disposed on one or both sides of the substrate. In this case, the heating element is disposed so as to be in direct contact with one or both sides of the substrate. The heating element may be disposed so as to cover the entire area of ​​one or both sides of the substrate, or may be disposed in a line, strip, or pattern. The substrate is not particularly limited as long as it can support the heating element, but from the viewpoints of the adhesive tape's conformability, thinning, heat resistance, etc., a resin film such as polyesters such as polyethylene terephthalate and polyethylene naphthalate, polyolefins such as polypropylene, or polyimide is preferred.

[0030] The average thickness of the heating element is 2 μm or more and 200 μm or less, preferably 5 μm or more and more preferably 10 μm or more. On the other hand, the average thickness of the heating element is preferably 200 μm or less and more preferably 150 μm or less. From the viewpoints of easily increasing the volume resistance value of the heating element and easily obtaining a sufficient amount of heat generation in the pressure-sensitive adhesive tape of the present invention even at a low current, the average thickness of the heating element is preferably in the range of 10 to 150 μm. When the average thickness of the planar heating element is within the above range, a sufficient amount of current and heat generation can be obtained, the heating element can be efficiently heated by resistance heating, and the adhesive tape has excellent followability and application workability. The average thickness of the planar heating element is the average value of thickness measurements at five or more arbitrarily selected locations. When the planar heating element is arranged on one or both sides of a substrate, the average thickness of the planar heating element refers to the thickness excluding the substrate, and when the heating elements are arranged on both sides of the substrate, it refers to the thickness of the heating elements on each side.

[0031] Heating elements made by sintering fibrous or particulate conductive fillers into a sheet, or by binding fibrous or particulate conductive fillers into a sheet and then impregnating it with a binder, can be commercially available products, such as "Stainless Steel Fiber Sheet" from Tomoegawa Paper Co., Ltd. and "PGS Graphite Sheet" from Panasonic Corporation. Patterned versions of these can also be used.

[0032] [Adhesive layer] In the pressure-sensitive adhesive tape of the present invention, components constituting the pressure-sensitive adhesive layer include, for example, acrylic pressure-sensitive adhesives, urethane pressure-sensitive adhesives, rubber pressure-sensitive adhesives such as synthetic rubber or natural rubber, silicone pressure-sensitive adhesives, and vinyl ether pressure-sensitive adhesives. Among these, pressure-sensitive adhesives that can be used as pressure-sensitive adhesives are preferred, and acrylic pressure-sensitive adhesives containing acrylic polymers are more preferred. Acrylic pressure-sensitive adhesives containing acrylic polymers are less likely to melt or soften when heated. Therefore, the heat generated from the heating element of the pressure-sensitive adhesive tape of the present invention can selectively melt or soften the melt-softening layer, which will be described later, of the pressure-sensitive adhesive tape of the present invention. Note that a pressure-sensitive adhesive is an adhesive that bonds by applying pressure for a short period of time at room temperature around 20°C, and has tackiness at room temperature.

[0033] Examples of acrylic polymers include homopolymers of (meth)acrylic acid ester monomers and copolymers of (meth)acrylic acid ester monomers with other monomers. In this specification, "(meth)acrylic" is a term that collectively refers to acrylic, methacrylic, and both. "(Meth)acrylate" is a term that collectively refers to acrylate, methacrylate, and both.

[0034] Examples of the (meth)acrylic acid ester monomer include (meth)acrylic acid alkyl esters having an alkyl chain having 1 to 14 carbon atoms, such as methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, hexyl (meth)acrylate, cyclohexyl (meth)acrylate, octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isononyl (meth)acrylate, isodecyl (meth)acrylate, and lauryl (meth)acrylate. The acrylic polymer may contain one of these monomers as a constituent unit, or may contain two or more of these monomers as a constituent unit.

[0035] The content of the (meth)acrylic acid ester monomer is preferably in the range of 70 to 99.9 mass % of all the monomer components constituting the acrylic polymer, more preferably in the range of 80 to 99 mass %, and even more preferably in the range of 90 to 97 mass %.

[0036] Further, as other monomers for obtaining an acrylic polymer, a polar group-containing monomer may be contained. Examples of the polar group-containing monomer include carboxylic acids having an ethylenically unsaturated group, such as (meth)acrylic acid, itaconic acid, itaconic anhydride, maleic acid, maleic anhydride, and crotonic acid; (meth)acrylates having a hydroxyl group, such as 2-hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, caprolactone-modified (meth)acrylate, polyoxyethylene (meth)acrylate, and polyoxypropylene (meth)acrylate; Examples of such a monomer include nitrogen-containing monomers having an ethylenically unsaturated group, such as (meth)acrylonitrile, N-vinyl-2-pyrrolidone, N-vinylcaprolactam, N-vinyllaurolactam, (meth)acryloylmorpholine, (meth)acrylamide, N,N-dimethyl(meth)acrylamide, N-methylol(meth)acrylamide, N-butoxymethyl(meth)acrylamide, N,N-dimethylaminomethyl(meth)acrylate, and 2-(perhydrophthalimide-N-yl)ethyl acrylate.

[0037] When used in combination with a crosslinking agent described below, a crosslinked structure can be formed between the hydroxyl group or carboxyl group and the crosslinking agent, and the storage modulus of the adhesive layer can be adjusted. From this viewpoint, the polar group-containing monomer is preferably a (meth)acrylate having a hydroxyl group or a carboxylic acid having an ethylenically unsaturated group, and more preferably 2-hydroxyethyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, or acrylic acid.

[0038] The content of the polar group-containing monomer in the acrylic polymer is preferably in the range of 0.1 to 20 mass % of all the monomer components constituting the acrylic polymer, more preferably in the range of 1 to 13 mass %, and still more preferably in the range of 1.5 to 8 mass %.

[0039] The weight-average molecular weight of the acrylic polymer is preferably in the range of 400,000 to 1,400,000, more preferably in the range of 600,000 to 1,200,000, and even more preferably in the range of 650,000 to 1,100,000. Here, the weight-average molecular weight is the weight-average molecular weight measured by gel permeation chromatography (GPC) in terms of standard polystyrene. Specifically, it is determined using a GPC measuring device "SC8020" manufactured by Tosoh Corporation under the following measurement conditions. Sample concentration: 0.5% by mass (tetrahydrofuran solution) Sample injection volume: 100 μL Eluent: tetrahydrofuran (THF) ·Flow rate: 1.0mL / min Column temperature (measurement temperature): 40℃ Column: Tosoh Corporation "TSKgel GMHHR-H" Detector: Differential refraction

[0040] The adhesive layer may further contain a tackifying resin for the purpose of adjusting its adhesiveness. Examples of tackifying resins include rosin-based, polymerized rosin-based, polymerized rosin ester-based, rosin phenol-based, stabilized rosin ester-based, disproportionated rosin ester-based, hydrogenated rosin ester-based, terpene-based, terpene phenol-based, petroleum resin-based, C5 / C9 petroleum resin-based, and (meth)acrylate-based tackifying resins. Also usable are tackifying resins that are liquid at room temperature, such as process oil, polyester-based tackifying resins, and low-molecular-weight liquid rubbers such as polybutene. When the adhesive layer contains a tackifier resin, the amount thereof is preferably in the range of 1 to 150 parts by mass, more preferably 10 to 150 parts by mass, per 100 parts by mass of the base resin such as an acrylic polymer constituting the adhesive layer, from the viewpoint of improving adhesion at around room temperature (0 to 40°C) and exhibiting heat durability. Furthermore, when the adhesive layer contains a tackifier resin, the total content of the base resin and tackifier resin in the adhesive forming the adhesive layer is preferably 50% by mass or more, more preferably 70% by mass or more, and even more preferably 90% by mass or more, based on the total solid content of the adhesive.

[0041] The adhesive layer may further contain a crosslinking agent to improve cohesion, such as known crosslinking agents including isocyanate, epoxy, aziridine, polyvalent metal salt, metal chelate, ketohydrazide, oxazoline, carbodiimide, silane, and glycidyl(alkoxy)epoxysilane.

[0042] The adhesive layer may further contain other additives such as antioxidants, anti-aging agents, colorants such as pigments and dyes, thickeners, leveling agents, film-forming aids, infrared absorbers, ultraviolet absorbers, and water repellents, as needed, within the range that does not impair the effects of the present invention.

[0043] The adhesive layer may further contain a thermoplastic resin, and in the adhesive tape of the present invention, from the viewpoint of selectively melting or softening the melt-softening layer by heat generated from the heating element, it is preferable that the adhesive layer be composed of a component that is different from the thermoplastic resin contained in the melt-softening layer and that is difficult to melt or soften by heating. More specifically, it is preferable that the thermoplastic resin contains a temperature at which the loss tangent (tan δ) is 0.8 or higher in a temperature range of, for example, 40° C. or higher, higher than the melting point of the melt-softening layer described below.

[0044] The thickness of the adhesive layer is preferably in the range of 10 to 200 μm, more preferably in the range of 20 to 100 μm, from the viewpoints of adhesive strength to the adherend and film uniformity during solution coating. The thickness of the adhesive layer is the average value obtained by measuring the thickness at any five positions.

[0045] The melting point of the adhesive layer is preferably higher than that of the melt-softening layer described below. Here, the "melting point of the adhesive layer" refers to the melting point of a composition (hereinafter simply referred to as "adhesive layer composition") that is composed of a tackifier resin, a crosslinking agent, other additives, and a thermoplastic resin different from the thermoplastic resin contained in the melt-softening layer, which are optionally contained in an acrylic adhesive, a urethane adhesive, a rubber adhesive, a silicone adhesive, a vinyl ether adhesive, or the like that constitutes the adhesive layer. The melting point of the adhesive layer (adhesive layer composition) is, for example, preferably 130° C. or higher, and more preferably in the range of 130° C. to 200° C. By adjusting the melting point of the adhesive layer to the above range and the melting point of the melt-softening layer to the range described below, the heat generated from the heating element can cause the melt-softening layer to melt or soften before the adhesive layer melts or softens. That is, when an article having a structure bonded with the pressure-sensitive adhesive tape of the present invention is thermally dismantled, the melt-softening layer melts or softens stably and preferentially, and the article can be easily dismantled. The "melting point of the adhesive layer" is the temperature of the endothermic peak associated with the melting of the adhesive layer (adhesive layer composition), measured using differential scanning calorimetry (DSC).

[0046] In a temperature range of 40°C or higher, the temperature at which the adhesive layer (adhesive layer composition) has a tan δ of 0.8 or higher is preferably higher than the temperature at which the melt-softening layer has a tan δ of 0.8 or higher. In particular, the temperature at which the adhesive layer (adhesive layer composition) has a tan δ of 0.8 or higher is more preferably higher than the temperature at which the melt-softening layer has a tan δ of 1 or higher. Specifically, in the temperature range of 40°C or higher, the temperature when the tan δ of the adhesive layer (adhesive layer composition) is 0.8 is preferably higher than the temperature when the tan δ of the melt-softening layer is 0.8, more preferably higher than the temperature when it is 1, and even more preferably higher than the temperature when it is 1.2.

[0047] In one preferred embodiment of the adhesive layer (adhesive layer composition), the maximum value of tan δ in the temperature range of 80°C to 160°C is preferably less than 1, more preferably less than 0.8, and even more preferably 0.6 or less. From the viewpoint of allowing the adhesive layer to exhibit viscosity and elasticity, the tan δ of the adhesive layer (adhesive layer composition) in the temperature range of 80°C to 160°C is preferably 0.2 or more.

[0048] In one preferred embodiment of the adhesive layer, the temperature range in which the adhesive layer (adhesive layer composition) has a tan δ of 0.8 or more is preferably above 150° C., more preferably above 170° C. The upper limit of the temperature range is not particularly limited, but can be set to, for example, 300° C., preferably 250° C. In the pressure-sensitive adhesive tape of the present invention, when the pressure-sensitive adhesive layer has such physical properties, melting and / or softening of the pressure-sensitive adhesive layer can be suppressed when the pressure-sensitive adhesive layer and the melt-softening layer receive the same amount of heat from a heating element. In other words, when an article having a structure bonded with the adhesive tape of the present invention is thermally dismantled, melting or softening of the melt-softening layer is stably and preferentially caused to occur while melting or softening of the adhesive layer is suppressed, making it possible to easily dismantle the article in a short time. From the viewpoint of being able to exhibit good adhesion to adherends before and after disassembly, the tan δ of the adhesive layer (adhesive layer composition) at 23° C. is preferably 0.1 to 0.8, more preferably 0.2 to 0.6.

[0049] The tan δ of the adhesive layer (adhesive layer composition) is determined by dynamic viscoelasticity measurement at a frequency of 1 Hz. For example, a test piece of the adhesive layer composition with a dry thickness of approximately 2 mm is prepared, and the storage modulus G' and loss modulus (G") are measured using a viscoelasticity tester (ARES-G2, manufactured by TA Instruments Japan) at a frequency of 1 Hz, in the temperature range of -40°C to 200°C, and at a heating rate of 2°C / min. Tan δ is calculated using the formula [tan δ=G″ / G′].

[0050] The tan δ of the adhesive layer (adhesive layer composition) can be adjusted by the base polymer of the adhesive, which is the main component, for example, the type and combination of monomers constituting the acrylic polymer described above, the blending ratio of each monomer, the blending amount of tackifying resin added as needed, the blending amount (gel fraction) of crosslinking agent added as needed, etc.

[0051] [Melting and softening layer] The melt-softening layer constituting the pressure-sensitive adhesive tape of the present invention contains a thermoplastic resin. <Thermoplastic resin> Examples of thermoplastic resins include urethane-based resins, polycarbonates, vinyl chloride-based resins, acrylic-based resins, crystalline or non-crystalline polyester-based resins such as polyethylene terephthalate, polyamide-based resins, styrene-based resins, olefin-based resins, cellulose-based resins, silicone-based resins, fluorine-based resins, styrene-based thermoplastic elastomers, olefin-based thermoplastic elastomers, vinyl chloride-based thermoplastic elastomers, acrylic-based thermoplastic elastomers, urethane-based thermoplastic elastomers, ester-based thermoplastic elastomers, and amide-based thermoplastic elastomers. These may be used alone or in combination of two or more.

[0052] Of the above-mentioned thermoplastic resins, urethane-based resins, acrylic-based resins, polyester-based resins, styrene-based thermoplastic elastomers, olefin-based thermoplastic elastomers, vinyl chloride-based thermoplastic elastomers, acrylic-based thermoplastic elastomers, urethane-based thermoplastic elastomers, ester-based thermoplastic elastomers, and amide-based thermoplastic elastomers are preferred, with styrene-based thermoplastic elastomers being more preferred. These thermoplastic resins can be melted or softened by the heat generated by the heating element of the adhesive tape of the present invention, and can melt or soften the melt-softening layer without containing components that cause peeling to occur at the adhesive interface or components that cause a decrease in adhesive strength, such as a heat-foaming agent. Therefore, the adhesive tape becomes easily peelable, and preferably has a softening point, and when the temperature rises above the softening point, the melt-softened layer suddenly becomes flexible, which is advantageous in that it exhibits high deformability and fluidity.

[0053] The styrene-based thermoplastic elastomer is preferably a block copolymer consisting of a polymer block containing a structural unit derived from an aromatic vinyl compound and a polymer block containing a structural unit derived from a conjugated diene compound, or a hydrogenated product thereof. Specifically, polystyrene-polybutadiene diblock copolymers or their hydrogenated products, such as polystyrene-poly(ethylene-butylene) diblock copolymers (SEB), polystyrene-polybutadiene-polystyrene triblock copolymers (SBS) or their hydrogenated products, such as polystyrene-poly(ethylene-butylene)-polystyrene triblock copolymers (SEBS), polystyrene-polyisoprene diblock copolymers or their hydrogenated products, such as polystyrene-poly(ethylene-propylene) diblock copolymers (SEP), and polystyrene-polyisoprene-polystyrene triblock copolymers. Examples of suitable styrene random copolymers include polystyrene-poly(ethylene-propylene)-polystyrene triblock copolymers (SEPS), polystyrene-polybutadiene-polystyrene-polybutadiene tetrablock copolymers (SIS) and their hydrogenated products, such as polystyrene-poly(ethylene-propylene)-polystyrene triblock copolymers (SEPS), polystyrene-polybutadiene-polystyrene-polybutadiene tetrablock copolymers (SBSB) and their hydrogenated products, polystyrene-polybutadiene-polystyrene-polybutadiene-polystyrene pentablock copolymers (SBSBS), styrene multiblock copolymers, and hydrogenated products of styrene random copolymers such as styrene-butadiene rubber (SBR) in which the ethylenic double bonds have been hydrogenated. Moreover, commercially available styrene-based thermoplastic elastomers may be used.

[0054] The weight average molecular weight of the styrene-based thermoplastic elastomer is preferably in the range of 10,000 to 800,000, more preferably in the range of 30,000 to 500,000, and even more preferably in the range of 50,000 to 300,000. When the weight average molecular weight is within the above range, the storage modulus and loss tangent of the melt-softening layer can be easily adjusted to fall within the desired range, and the melt-softening layer can be easily melted or softened by heating. The weight average molecular weight of the styrene-based thermoplastic elastomer can be determined in the same manner as in the above-mentioned method for measuring the weight average molecular weight of the acrylic polymer.

[0055] The styrene-based thermoplastic elastomer may be used alone or in combination of two or more types, i.e., the styrene-based thermoplastic elastomer may be one or more types of triblock copolymer, one or more types of diblock copolymer, or a mixture of a triblock copolymer and a diblock copolymer. In particular, it is preferable that the styrene-based thermoplastic elastomer contains at least a diblock copolymer, from the viewpoint that the melt-softened layer exhibits appropriate cohesive strength, has good adhesive strength at around room temperature (0 to 40°C) before heating, and can be easily melted or softened by heating. The content of the diblock copolymer in the styrene-based thermoplastic elastomer is preferably in the range of 10 to 100% by mass, more preferably in the range of 10 to 90% by mass, and even more preferably in the range of 15 to 80% by mass. From the viewpoint of achieving an excellent balance between adhesiveness at 20°C and meltability upon heating, the range of 20 to 75% by mass is particularly preferred.

[0056] The melt-softening layer melts or softens due to the heat generated by the heating element, and the adhesive strength during heating decreases compared to the adhesive strength at around room temperature (0 to 40°C). The content of the thermoplastic resin in the melt-softening layer is preferably in the range of 30 to 95 mass % of the total amount of the melt-softening layer, and more preferably in the range of 35 to 90 mass %. When the blending amount of the thermoplastic resin in the melt-softening layer is in the above range, it is advantageous from the viewpoint of the coatability of the melt-softening layer and control of the melt-softening temperature.

[0057] <Optional ingredients> The melt-softening layer may further contain a filler for the purposes of improving the initial adhesive strength by imparting flexibility and increasing the heat storage effect of the melt-softening layer by reducing the thermal conductivity. Examples of fillers include organic fillers and inorganic fillers, which may be solid or hollow. Examples of resins constituting the organic filler include resins containing structural units derived from acrylonitrile, vinyl chloride, vinylidene chloride, styrene, vinyl acetate, ethylene, (meth)acrylic esters, and the like. Examples of the organic filler include acrylonitrile copolymers, vinylidene chloride copolymers, acrylic copolymers, styrene copolymers, polyethylene polymers, etc. The surface of the organic filler may be surface-treated with an organic surface treatment agent such as a fatty acid or a fatty acid ester, or an inorganic surface treatment agent such as calcium carbonate, barium sulfate, talc, titanium oxide, titanium, clay, or silica. Examples of inorganic substances that constitute the inorganic filler include metal oxide ceramics such as alumina, silica, silica alumina, zirconia, and magnesia; non-oxide ceramics such as silicon carbide, boron carbide, nitrogen carbide, aluminum nitride, silicon nitride, and boron nitride; glass, calcium carbonate, volcanic ash (shirasu), and fly ash. The inorganic filler may be subjected to a surface treatment such as hydrophobization with a silane coupling agent or a fluorine-based compound. The filler may be used alone or in combination of two or more kinds. When the melt-softening layer further contains a filler, the amount thereof is usually preferably in the range of 5 to 80% by volume, more preferably 10 to 65% by volume, based on the total volume of the melt-softening layer. The content of the organic or inorganic filler is usually preferably in the range of 0.01 to 30% by mass, more preferably 0.02 to 20% by mass, based on the total mass of the melt-softening layer.

[0058] The melt-softening layer may further contain other additives such as antioxidants, anti-aging agents, colorants such as pigments and dyes, thickeners, leveling agents, film-forming aids, infrared absorbers, ultraviolet absorbers, and water repellents, as needed, within the range that does not impair the effects of the present invention.

[0059] The melt-softening layer may further contain a tackifier resin for the purpose of adjusting its adhesiveness. Details of the tackifier resin are the same as those described in the section on the adhesive layer. The melt-softening layer may contain one tackifier resin alone or two or more tackifier resins. When the melt-softening layer contains a tackifier resin, it preferably contains a tackifier resin whose mass loss rate when heated from 25°C to 200°C at a temperature increase rate of 10°C / min under nitrogen is 5% or less. When the melt-softening layer contains a tackifying resin, the amount thereof is preferably in the range of 1 to 150 parts by mass, more preferably 10 to 150 parts by mass, per 100 parts by mass of the thermoplastic resin constituting the melt-softening layer, from the viewpoint of improving adhesion at around room temperature (0 to 40°C) and exhibiting heat durability. Furthermore, when the melt-softening layer contains a tackifying resin, the total content of the thermoplastic resin and tackifying resin constituting the melt-softening layer is preferably in the range of 70 to 99.9 mass%, more preferably 80 to 99.8 mass%, relative to the total mass of all components constituting the melt-softening layer, i.e., the thermoplastic resin and tackifying resin, as well as any optional crosslinking agent, filler, and other additives. The melt-softening layer may further contain a crosslinking agent for the purpose of improving cohesive strength. Details of the crosslinking agent are the same as those described in the section on the adhesive layer.

[0060] <Physical properties of the melt-softened layer> The melting point of the melt-softening layer is preferably lower than that of the adhesive layer, specifically preferably in the range of 80 to 200°C, more preferably in the range of 90 to 180°C, and even more preferably in the range of 100 to 160°C. Here, the "melting point of the melt-softening layer" means the melting point of the composition that contains the above-mentioned thermoplastic resin and that constitutes the melt-softening layer. In this specification, the "composition containing a thermoplastic resin that constitutes the melt-softening layer" will hereinafter also be referred to simply as the "melt-softening resin composition." In other words, the melt-softening resin composition is a composition comprising a thermoplastic resin that constitutes the melt-softening layer, and optionally a tackifying resin, a crosslinking agent, other additives, etc. The "melting point of the melt-softening layer" means the melting point of such a melt-softening resin composition. When the melting point of the melt-softening layer is within the above range, the pressure-sensitive adhesive tape of the present invention can exhibit high adhesive strength before heating. Furthermore, when thermally dismantling an article having a structure bonded with the pressure-sensitive adhesive tape of the present invention, even if the amount of heat generated from the heating element is small, the melting or softening of the melt-softening layer can be stably and preferentially caused, and the article can be easily dismantled in a short time. The "melting point of the melt-softened layer" is the temperature of the endothermic peak accompanying the melting of the melt-softened resin composition, as measured by differential scanning calorimetry (DSC).

[0061] The storage modulus G of the melt-softened layer (i.e., the melt-softened resin composition) at 23°C 23 is 1.0 × 10 from the viewpoint of achieving good adhesion between adherends at around room temperature (0 to 40°C). 3 Pa~1.0×10 9 Pa is preferred, 1.0 x 10 3 Pa ~ 5.0 × 10 7 Pa is more preferred, 5.0 × 10 3 Pa ~ 5.0 × 10 7 Pa is more preferable, and 5.0×10 3 Pa ~ 5.0 × 10 6 Pa is even more preferred, and 5.0 x 10 3 Pa~1.0×10 6 Pa is particularly preferred. Storage modulus G of the melt-softened layer at 120°C 120 is 1.0 × 10 0 Pa ~ 5.0 × 10 6 Pa is preferred, 1.0 x 10 3 Pa~1.0×10 6 Pa is more preferable, and 1.0 × 10 3 Pa~1.0×10 6 Pa is more preferable, and 5.0×10 3 Pa ~ 5.0 × 10 5 Pa is even more preferable. Storage modulus G 120 When the temperature is within the above range, the melt-softening layer melts or softens in a short time upon heating, making it possible to peel it off.

[0062] Furthermore, the melt-softened layer preferably has a tan δ in a temperature range of 80° C. or higher (preferably a tan δ in a temperature range of 100° C. or higher) of 0.8 or higher, more preferably 1 or higher. In one preferred embodiment of the melt-softening layer, the temperature at which the melt-softening layer has a tan δ of 0.8 or higher is lower than the temperature at which the adhesive layer (adhesive layer composition) has a tan δ of 0.8 or higher. In detail, the temperature range in which the tan δ of the melt-softened layer is 0.8 or more is preferably 80°C or higher, more preferably 80°C or higher and 200°C or lower, even more preferably 100°C or higher and 160°C or lower, and even more preferably 100°C or higher and 130°C or lower. More specifically, the temperature at which the tan δ of the melt-softened layer is 0.8 is preferably 80°C or higher, more preferably 80°C or higher and 200°C or lower, and even more preferably 100°C or higher and 160°C or lower. The temperature at which the melt-softened layer has a tan δ of 1 is preferably 80°C or higher, more preferably 80°C or higher and 200°C or lower, and even more preferably 100°C or higher and 180°C or lower.

[0063] The difference between the temperature at which the tan δ of the melt-softening layer is 0.8 (more preferably, the temperature at which tan δ is 1) and the temperature at which the tan δ of the adhesive layer (adhesive layer composition) is 0.8 (more preferably, the temperature at which tan δ is 1) may be a temperature difference at which the melt-softening layer preferentially melts or softens when heated from the heating element, and is, for example, 10°C or more, preferably 25°C or more, even more preferably 30°C or more, and more preferably 50°C or more. In the pressure-sensitive adhesive tape of the present invention, if the melt-softening layer has such physical properties, when the pressure-sensitive adhesive layer and the melt-softening layer receive the same amount of heat from a heating element, the melt-softening layer is more likely to melt and / or soften preferentially. When the heat generated by the heating element causes the melt-softened layer to reach the desired decomposition temperature range described below, the melting or softening makes it more likely to cause plastic deformation, and cohesive failure within the melt-softened layer can cause peeling within the melt-softened layer or at the interface between the melt-softened layer and an adjacent layer or adherend. That is, when an article having a structure bonded with the pressure-sensitive adhesive tape of the present invention is thermally dismantled, the melt-softening layer melts or softens stably and preferentially, and the article can be easily dismantled in a short time. From the viewpoint of improving the adhesiveness before dismantling, the tan δ of the melt-softened layer at 23° C. is preferably 0.1 to 0.8, and more preferably 0.2 to 0.6.

[0064] The storage modulus G and tanδ of the melt-softened layer (i.e., the melt-softened resin composition) are determined by dynamic viscoelasticity measurement. For example, a test piece of the melt-softened resin composition with a dry thickness of approximately 2 mm is prepared, and the storage modulus G' and loss modulus (G") are measured at each temperature using a viscoelasticity tester (ARES-G2, manufactured by TA Instruments Japan) under the following conditions: a frequency of 1 Hz, a temperature range of -40°C to 200°C, and a heating rate of 2°C / min. Tanδ is calculated using the formula [tanδ=G" / G'].

[0065] Storage modulus of the melt-softened layer G 23 , storage modulus G 120 The tan δ and melting point can be adjusted by the type and combination of thermoplastic resins, the amount of tackifier resin added as needed, the amount of crosslinking agent added as needed, and the like.

[0066] The thickness of the melt-softening layer can be 500 μm or less, preferably in the range of 10 to 200 μm, and more preferably in the range of 20 to 150 μm, from the viewpoints of coatability, adhesive strength to the adherend, and dismantling ability. The thickness of the melt-softening layer is the average value obtained by measuring the thickness at any five positions.

[0067] The pressure-sensitive adhesive tape of the present invention has at least one melt-softening layer adjacent to the heating element, but may also have a melt-softening layer c1 adjacent to one side of the layered heating element and a melt-softening layer c2 adjacent to the other side of the heating element. The specific layer structure of a pressure-sensitive adhesive tape having two melt-softening layers will be described later.

[0068] [Layer structure of adhesive tape] A first embodiment of the adhesive tape of the present invention may be a laminate embodiment in which the adhesive tape 10 has a planar heating element b, an adhesive layer a arranged on one side of the planar heating element b, and a melt-softening layer c arranged on the other side of the planar heating element b, and is laminated in the order of adhesive layer a / heating element b / melt-softening layer c, as shown in Figures 1 and 2. The heat generated by the heating element b melts or softens the melt-softening layer c adjacent to the heating element b, reducing the adhesive strength and making it possible to peel it off.

[0069] It is preferable that the planar heating element b has a pair of extension portions e that extend and are exposed from the outer peripheries of the adhesive layer a and the melt-softening layer c in a plan view (see Figures 3 and 4). The extension portions e may be provided in two or more independent locations, and their positions on the heating element are not particularly limited and can be appropriately selected depending on the purpose. The two extension portions e may be located on the same side of the outer peripheries of the adhesive layer a and the melt-softening layer c (see Figures 4(1) to (3)), or on two different sides (see Figures 3 and 4(4) to (6)).

[0070] The extensions e are preferably located on two opposing sides of the outer periphery of the adhesive layer a and the melt-softening layer c (see Figures 4(4) to (6)), and are preferably located on approximately diagonal lines of the outer periphery of the adhesive layer a and the melt-softening layer c (see Figures 4(2) to (7)). In addition, when the extensions e are located on the same side of the outer periphery of the adhesive layer a and the melt-softening layer c, the heating element b preferably has a U-shape or a zigzag shape in plan view (see Figures 4(1) to (4) and (8)), and may be located in close proximity on the same side as long as the heating element b can uniformly heat the adhesive layer a and the melt-softening layer c within their planes (see Figures 4(3) and (8)). This allows current to flow across the entire area of ​​the planar heating element b, further improving the heat generation efficiency.

[0071] The extensions e may be provided in three or more locations (see FIG. 4(9)), and a desired pair (two locations) may be selected appropriately to energize the heating element. The pair of extensions e of the heating element b functions as a pair of terminals for electrically connecting to a power source in the article dismantling method described below, making it possible to easily energize the heating element b.

[0072] The length of the extensions is preferably 1 to 50 mm, more preferably 2 to 25 mm, from the viewpoint of facilitating contact with a power source or a heat generating source. Each extension may be bent in a direction different from the surface direction of the adhesive tape. For example, when the adherends are bonded together, the extension portion can be folded in a direction perpendicular to the surface of the adhesive tape and stored, and when the bond between the adherends is to be released (during dismantling), the extension portion can be folded again in the surface direction to bring the extension portion into contact with a power source or a heat generating source.

[0073] The adhesive tape of the present invention may also be, as a second embodiment, an adhesive tape 20 that is a laminate in which adhesive layer a1 / heat generating element b / melt-softening layer c / adhesive layer a2 are laminated in this order, as shown in Figure 5. Alternatively, the adhesive tape 20 may be a laminate in the order of adhesive layer a1 / melt-softening layer c1 / heating element b / melt-softening layer c2, and in this case, the melt-softening layer c2 may further have an adhesive layer a2 on the side opposite to the heating element b side. That is, a second embodiment of the adhesive tape of the present invention is a laminate having a heating element b, an adhesive layer a1 arranged on one side of the heating element b, a melt-softening layer c arranged on the other side of the heating element b, and an adhesive layer a2 on a side of the melt-softening layer c different from the side adjacent to the heating element b. Another example of the second aspect is a laminate having a heating element b, a melt-softening layer c1 and a melt-softening layer c2 arranged on both sides of the heating element b, an adhesive layer a1 arranged on a side of the melt-softening layer c1 other than the side adjacent to the heating element b, and an adhesive layer a2 arranged on a side of the melt-softening layer c2 other than the side adjacent to the heating element b. The heat generated from the heating element b melts or softens the melt-softening layer c1 or c2 adjacent to the heating element b, reducing the adhesive strength and making it possible to peel it off. The pressure-sensitive adhesive tape of the present invention of the second aspect, in which an adhesive layer is further provided on the surface of the melt-softening layer different from the surface adjacent to the heating element (opposite surface), can increase the initial adhesive strength and increase the rate of decrease in adhesive strength due to heating. In plan view, the planar heating element b preferably has a pair of extension portions that extend and are exposed from the outer peripheries of the adhesive layer a1, the adhesive layer a2, and the melt-softening layer c. Details of the extension portions are the same as those of the planar heating element b in the first embodiment.

[0074] The pressure-sensitive adhesive tape of the present invention may have a release layer (also referred to as a release sheet or release liner). Examples of the release layer include lathing paper, kraft paper, clay-coated paper, paper laminated with a film such as polyethylene, paper coated with a resin such as polyvinyl alcohol or an acrylic ester copolymer, and a synthetic resin film such as polyester or polypropylene coated with a fluororesin or silicone resin. The release layer may be present on one side or both sides of the pressure-sensitive adhesive tape of the present invention.

[0075] The pressure-sensitive adhesive tape of the present invention may have other layers, such as functional layers having insulating properties, heat insulating properties, or heat shielding properties, such as an insulating layer or a heat insulating layer (e.g., a foamed resin layer, a hollow-containing layer, a hollow particle-containing layer, etc.), in addition to the pressure-sensitive adhesive layer, the heating element, and the melt-softening layer, as long as the outermost layers (excluding the release layer) positioned opposite each other in the thickness direction have adhesive surfaces that can be bonded to an adherend.

[0076] In the adhesive tape of the present invention, the adhesive layer a and the melt-softening layer c in the first embodiment described above may be the adhesive surfaces with the adherend, and the adhesive layer a1 and the adhesive layer a2 in the second embodiment described above may be the adhesive surfaces with the adherend.

[0077] The pressure-sensitive adhesive tape of the present invention may have the following exemplary configurations, but is not limited to these. In the following laminate configurations, " / " represents the lamination interface, and for example, "Layer A / Layer B" means that Layer A and Layer B are adjacent, i.e., in direct contact. · Release layer / adhesive layer a / heating element b / melt-softening layer c · Adhesive layer a / heating element b / melt-softening layer c / release layer · Release layer / adhesive layer a / heating element b / melt-softening layer c / release layer · Adhesive layer a / functional layer / heating element b / melt-softening layer c / release layer · Release layer / adhesive layer a / functional layer / heating element b / melt-softening layer c / release layer · Release layer / adhesive layer a / heating element b / melt-softening layer c / adhesive layer a · Adhesive layer a / heating element b / melt-softening layer c / adhesive layer a / peeling layer / peeling layer / adhesive layer a / heating element b / melting softening layer c / adhesive layer a / peeling layer / peeling layer / adhesive layer a / heating element b / melting softening layer c / functional layer / adhesive layer a / peeling layer / adhesive layer a / functional layer / heating element b / melting softening layer c / adhesive layer a / peeling layer / peeling layer / adhesive layer a / functional layer / heating element b / melting softening layer c / functional layer / adhesive layer a / peeling layer / peeling layer / adhesive layer a / melting softening layer c / heating element b / melting softening layer c / peeling layer

[0078] The overall thickness of the pressure-sensitive adhesive tape of the present invention is preferably in the range of 50 μm to 2000 μm, more preferably in the range of 50 μm to 1000 μm, and even more preferably in the range of 50 μm to 800 μm, which can provide cushioning (flexibility) and the like when bonding adherends together, and can further improve the handleability of the pressure-sensitive adhesive tape, such as mechanical strength and processability.

[0079] [Uses of adhesive tape] The adhesive tape of the present invention functions as an adhesive surface (adhesive surface) on both sides, excluding the release layer, so that adherends can be attached to both sides of the adhesive tape, making it suitable for use in joining adherends together. The pressure-sensitive adhesive tape of the present invention can be peeled off by heating, preferably by resistance heating, and is therefore particularly suitable for use as a resistance heating (electrical heating) peeling tape. The pressure-sensitive adhesive tape of the present invention can be suitably used, for example, for bonding rigid adherends together and for separating adherends from each other. The pressure-sensitive adhesive tape of the present invention can be easily peeled off by heating, and therefore can be used in applications where peeling of the pressure-sensitive adhesive tape is required for separating parts for the purpose of reuse or recycling. For example, it can be suitably used as a pressure-sensitive adhesive tape for fixing parts of various products in industrial applications such as electronic devices, automobiles, building materials, office automation, and home appliances, and improves work efficiency when separating parts or peeling off labels.

[0080] [Adhesive tape manufacturing method] There are no particular limitations on the method for producing the pressure-sensitive adhesive tape of the present invention. For example, the pressure-sensitive adhesive tape of the first aspect of the present invention can be produced by a method in which a composition containing the components constituting the pressure-sensitive adhesive layer and a solvent is applied to a release sheet and dried to form a pressure-sensitive adhesive layer, a composition containing the components constituting the melt-softening layer and a solvent is applied to another release sheet and dried to form a melt-softening layer, and these are sequentially laminated to each side of a planar heating element. Here, the release sheet on the melt-softening layer side of the obtained adhesive tape is peeled off, and an adhesive layer formed in the form of a release sheet is further attached to the exposed surface of the melt-softening layer, thereby producing the adhesive tape of the second aspect of the present invention described above. Alternatively, the adhesive tape of the first aspect of the present invention described above can be produced by laminating an adhesive layer formed in the form of a release sheet to one side of a planar heating element, and then applying a composition containing components constituting a melt-softening layer and a solvent to the other side of the planar heating element and drying the composition to form a melt-softening layer. Furthermore, by further laminating an adhesive layer formed in the form of a release sheet onto the surface of the melt-softenable layer of the obtained adhesive tape, the adhesive tape of the second aspect of the present invention described above can be produced. Furthermore, the composition containing the components constituting the adhesive layer and the composition containing the components constituting the melt-softening layer may be molded by extrusion molding, press molding, injection molding, or the like. The solvent is not particularly limited, and examples thereof include organic solvents such as toluene, xylene, ethyl acetate, butyl acetate, acetone, methyl ethyl ketone, and hexane; water; and aqueous solvents mainly containing water. Although the solvent may remain in the adhesive layer and melt-softening layer of the obtained adhesive tape, it is generally preferred that no solvent is contained.

[0081] 2.Goods The present invention also provides an article comprising at least two adherends and the pressure-sensitive adhesive tape of the present invention between the two adherends, wherein the two adherends are bonded together via the pressure-sensitive adhesive tape. The adherend may be rigid or flexible like a film, etc. The material and shape of the adherend are not particularly limited, and examples include plate-shaped adherends made of resin, glass, or metal, housings, covers, and parts having any of these on the adherend surface. The two adherends bonded via the pressure-sensitive adhesive tape may be the same or different. As a method for bonding the adherends, a method in which an adherend is attached to each adhesive surface of the pressure-sensitive adhesive tape of the present invention and the two adherends are bonded together can be mentioned. There are no particular limitations on the article, but from the viewpoint of effectively utilizing the effects of the pressure-sensitive adhesive tape of the present invention, it is preferable that the article be, for example, an electronic device or a part to be built into an electronic device. In the article of the present invention, the heating element constituting the pressure-sensitive adhesive tape preferably has a pair of extensions extending from the outer periphery of the adherend in plan view.

[0082] The article 100 of the present invention is an article in which the two adherends 50 are bonded together via the adhesive tape 10, as shown, for example, in a schematic plan view in FIG. 6 and a schematic cross-sectional view in FIG. 7, and includes two adherends 50 and an adhesive tape 10 including a laminate in which an adhesive layer a / a planar heating element b / a melt-softening layer c are laminated in this order between the two adherends 50. In plan view (FIG. 6), both ends in the major axis direction of the planar heating element b extend from the outer peripheries of the adhesive layer a and the melt-softening layer c. Both ends of the extending adhesive tape 10 can be used as a pair of terminals for electrically connecting to a power source or as ends for contacting a heat generating source when the heating means is resistance heating or thermal conduction in the method for dismantling an article described below, and can easily heat the heating element b of the adhesive tape 10. Furthermore, as shown in Fig. 6, a smaller contact area between the adherend and the adhesive tape in plan view is advantageous in that the heating efficiency of the heating element is higher and dismantling is easier because triggers for dismantling are more likely to occur when heated. Furthermore, although not shown, the article of the present invention may be an article comprising two adherends and an adhesive tape shown in FIG. 5 between the two adherends, with the two adherends adhered via the adhesive tape.

[0083] In a plan view of the article, the adhesive tape may be attached to the entire adhesion surface, which is the surface of the adherend that faces the adhesive tape, or the adhesive tape may be attached to only a portion of the adhesion surface of the adherend. In particular, it is preferable that the adhesive tape 10 is attached to only a portion of the adhesion surface of the adherend 50, as shown in Fig. 6. In this case, the planar shape of the pressure-sensitive adhesive tape 10 in the article may be a strip or line shape, or may be a patterned shape. If the contact area between the adherend and the pressure-sensitive adhesive tape is small, when the pressure-sensitive adhesive tape is peeled from the adherend by resistance heating, a starting point for peeling is more likely to occur between the adherend and the pressure-sensitive adhesive tape, which is advantageous from the viewpoint of facilitating peeling. Furthermore, when the article of the present invention is viewed in a plane, and the adhesive tape is attached to the entire adherend surface, which is the surface of the adherend facing the adhesive tape, the planar shape of the planar heating element in the adhesive tape may be the same shape as the planar shape of the adhesive tape, or may be strip-shaped, linear, or patterned.

[0084] 3. How to dismantle items The present invention also provides a method for dismantling an article according to the present invention, which comprises melting or softening the melt-softening layer by heating with a heating element to separate the two adherends. The disassembly method of the present invention preferably includes a step (separation step) of separating at least two adherends by melting or softening the melt-softening layer by heating with a heating element, and may further include other steps as necessary. There are no particular limitations on the means and method for heating the heating element, and examples include resistance heating, electromagnetic induction heating, infrared heating, microwave heating, heat conduction, etc. Of these, resistance heating is preferred.

[0085] When the heating element is heated by resistance heating, the separation step is preferably a step of electrically connecting the heating element to a power source, passing electricity from the power source to the heating element, and melting or softening the melt-softening layer adjacent to the heating element by resistance heating, thereby separating the two adherends. The power source may be an external power source or a power source for driving an article that is an electronic device or a component built into an electronic device. Furthermore, when the article is an electronic device or a component built into an electronic device and the power source is a power source for driving the electronic device, the separation step is preferably a step of electrically connecting the heating element to the power source and electric circuit of the electronic device, applying electricity from the power source to the heating element, and melting or softening the melt-softening layer by resistance heating to separate the two adherends. The electrical connection can be achieved by electrically connecting a pair of extensions of the heating element extending from the outer periphery of the heating element or the adhesive layer and the melt-softening layer to a power source using known means such as alligator clips. The electric circuit and the electrically connecting means are preferably formed of a conductive material that exhibits a volume resistivity different from that of the material of the heating element in the pressure-sensitive adhesive tape, and more preferably formed of a conductive material that has a volume resistivity lower than that of the heating element. In this case, when the heating element and the electric circuit are electrically connected and electricity is applied to the heating element from a driving power source, it is advantageous in that excessive heating of the electric circuit and the electrically connecting means is prevented, and voltage can be efficiently applied to the heating element, allowing it to be peeled off in a short time.

[0086] The method of applying electricity can be appropriately selected depending on the size of the pressure-sensitive adhesive tape of the present invention, the type of heating element, etc., and includes, for example, a method of applying a voltage of 0.1 to 200 V until the melt-softening layer melts or softens (for example, in the range of 0.5 seconds to 30 minutes). As schematically shown in Figure 8, a simple power source can be used. The heating element of the pressure-sensitive adhesive tape of the present invention is electrically connected to a power source, and a voltage is applied to the heating element to energize it, thereby heating the heating element and its surroundings by resistance heating. This heating melts or softens the melt-softening layer, releasing the adhesive state and making the tape peelable, allowing the bonded adherends to be disassembled.

[0087] The voltage applied to the heating element by energization is usually preferably in the range of 0.1 to 200V, more preferably 0.5 to 150V, and even more preferably 1.0V to 100V. In the pressure-sensitive adhesive tape of the present invention, the melt-softening layer melts or softens in a short time even when a low voltage is applied, and therefore, by applying a voltage within the above range in the separation step, articles can be dismantled in a short time without applying an excessive voltage, and damage to the articles due to heat can be prevented. In particular, by applying a voltage that is compatible with articles such as small electronic devices and household electrical appliances, these articles can be easily dismantled.

[0088] The current applied to the heating element is not particularly limited, and is generally preferably in the range of 0.01 to 20 A, more preferably 0.03 to 15 A, even more preferably 0.05 to 10 A, and particularly preferably 0.1 to 5 A. Since the adhesive tape of the present invention melts or softens the melt-softening layer in a short time, if the current applied in the separation step is within the above range, the article can be disassembled in a short time by passing the current that flows through general-purpose electronic devices and home appliances, and damage to the article due to heat can be prevented. In particular, by applying a current that can be handled by small electronic devices and home appliances, these articles can be easily disassembled. Furthermore, even if a worker accidentally comes into contact with a live part during dismantling work, the pressure-sensitive adhesive tape of the present invention can generate a sufficient amount of heat at a low current that does not physically harm the worker, and therefore the dismantling method of the present invention is excellent in work safety. The application time is not particularly limited, and is usually preferably 0.5 seconds to 30 minutes, more preferably 0.5 seconds to 120 seconds, and even more preferably 0.5 seconds to 30 seconds. When the application time is within the above range, the article is not damaged by heat and can be easily disassembled in a short time.

[0089] When the heating element is heated by electromagnetic induction heating, the separation step is preferably a step of melting or softening the melt-softened layer by electromagnetic induction heating using an electromagnetic induction heating means to separate the two adherends. There are no particular restrictions on the electromagnetic induction heating means, and any known electromagnetic induction heating device can be selected as appropriate.

[0090] When the heating element is either infrared heating or microwave heating, the separation step is preferably a step of melting or softening the melt-softening layer by either infrared heating using an infrared heating means or microwave heating using a microwave heating means, thereby separating the two adherends. There are no particular limitations on the infrared heating means and microwave heating means, and any known infrared heating device or microwave heating device can be appropriately selected.

[0091] When the heating element heats by heat conduction, the separation step is preferably a step of bringing the heating element into contact with a heat generation source, melting or softening the melt-softening layer by heat conduction, and separating the two adherends. There are no particular restrictions on the heat generation source, and any known heater can be selected as appropriate. The method of heat conduction using a heat generating source can be appropriately selected depending on the size of the adhesive tape, the type of heating element, etc., and examples include a method in which the adhesive tape is brought into contact with the heat generating source at a desired temperature until the melt-softening layer melts or softens.

[0092] The dismantling temperature of the article is preferably in the range of 80°C to 160°C, more preferably in the range of 90°C to 150°C, and even more preferably in the range of 100°C to 130°C. By setting the dismantling temperature within the above range, thermal damage to the article and adherend can be suppressed, and dismantling can be easily performed. In particular, when the pressure-sensitive adhesive tape is heated by resistance heating (current heating), by generating heat directly inside the tape, dismantling can be performed before the heat is transmitted to the article and adherend. The dismantling temperature of the article can be measured as the temperature of the heating element of the pressure-sensitive adhesive tape of the present invention (the temperature reached by the heating element during dismantling) using a temperature sensor using a thermocouple.

[0093] Although one embodiment of the pressure-sensitive adhesive tape, article, and method for dismantling an article of the present invention has been described above, the present invention is not limited to the configuration of the above-described embodiment. For example, the pressure-sensitive adhesive tape of the present invention may have any other optional configuration in addition to the configuration of the above-described embodiment, or may be replaced with any other configuration that produces a similar effect. [Example]

[0094] The present invention will be specifically described below with reference to examples. However, the present invention is not limited to the following examples. Materials used in the examples are shown below.

[0095] <Heater> Heating element 1: Metal fiber sheet Stainless steel fibers with an average fiber diameter of 1 μm to 50 μm and an average fiber length of 100 μm to 20 mm, with a basis weight of 50 g / m 2 After mixing with a binder (organic flocculant) to achieve the above, the material is formed into a sheet using a paper-making machine and sintered to obtain a metal fiber (stainless steel fiber) sheet. The thickness is 50 μm and the volume resistivity at 20°C is 1600 μΩ cm. Heating element 2: Graphite sheet Graphite sheet obtained by forming carbon fiber (average fiber length 100μm to 20mm) or graphite (average particle diameter 1μm to 100μm) into a sheet using a papermaking machine and sintering it. It has a thickness of 50μm and a volume resistivity of 5000μΩ·cm at 20℃. Heating element 3: Cured phenolic resin impregnated graphite sheet Carbon fiber (average fiber length 100μm-20mm) or graphite (average particle size 1μm-100μm) is formed into a sheet using a papermaking machine, then impregnated with a curable phenolic resin and baked in a hot press to produce a graphite sheet. It has a thickness of 90μm and a volume resistivity of 13,700μΩ·cm at 20℃. Heating element 4: Nichrome foil "Nichrome NCH1-H" [product name, manufactured by Takeuchi Metal Foil & Powder Co., Ltd., thickness 10 μm. Volume resistivity at 20°C: 108 μΩ·cm (catalog value), 105 μΩ·cm (measured value)] <Release layer> Release liner: 75 μm thick polyethylene terephthalate film with release treatment on one side

[0096] <Constituent materials of the melt-softening layer (melt-softening resin composition)> [Preparation Example 1] 100 parts by mass of a styrene-isoprene block copolymer composition (a mixture of styrene-isoprene diblock copolymer and styrene-isoprene triblock copolymer; 24% by mass of styrene-derived structural units), 40 parts by mass of Quinton G115 (a C5 / C9 petroleum resin manufactured by Zeon Corporation, softening point 115°C), 30 parts by mass of Pencel D-160 (a polymerized rosin ester resin manufactured by Arakawa Chemical Industries, Ltd., softening point 15°C to 150°C), 5 parts by mass of Nippon Oil Polybutene HV-50 (a polybutene manufactured by JX Nippon Oil & Energy Corporation, pour point -12.5°C), and 1 part by mass of an antioxidant (tetrakis[methylene-3-(3'5'-di-t-butyl-4-hydroxyphenyl)propionate]methane) were mixed and dissolved in 100 parts by mass of toluene as a solvent to obtain resin composition 1. The obtained resin composition 1 was applied to the release-treated surface of a release liner to a thickness of approximately 2 mm after drying to prepare layer 1, and the storage modulus G' and loss modulus (G") were measured using a viscoelasticity tester (ARES-G2, manufactured by TA Instruments Japan) under conditions of a frequency of 1 Hz, a temperature range of -40°C to 200°C, and a heating rate of 2°C / min. In addition, the tan δ of resin composition 1 at a frequency of 1 Hz was calculated using the formula [tan δ=G" / G']. The melting point of resin composition 1 is 140°C, and the storage modulus G 23 is 2.5 x 10 5 Pa, and the storage modulus G at 120 °C 120 is 5.0 x 10 4 Pa, and the temperature when tan δ was 0.8 was 125°C (the temperature range where tan δ was 0.8 or higher was 125°C or higher).

[0097] <Materials constituting the adhesive layer> [Preparation Example 2] A reaction vessel equipped with a stirrer, a reflux condenser, a nitrogen inlet tube, and a thermometer was charged with 79.9 parts by mass of n-butyl acrylate, 6 parts by mass of 2-ethylhexyl acrylate, 10 parts by mass of cyclohexyl acrylate, 4 parts by mass of acrylic acid, 0.1 parts by mass of 4-hydroxybutyl acrylate, and 200 parts by mass of ethyl acetate, and nitrogen was bubbled through the mixture at 23°C for 1 hour while stirring to obtain a mixture. Next, 2 parts by mass of a solution of 2,2'-azobis(2-methylbutynitrile) previously dissolved in ethyl acetate (solid content 1.0% by mass) was added to the mixture, and the mixture was stirred at 72°C for 4 hours, and then at 75°C for 5 hours. The resulting mixture was then diluted with ethyl acetate and filtered through a 200-mesh wire screen to obtain an acrylic copolymer solution (solid content concentration 26%) having a weight-average molecular weight of 1,060,000 and an average number of carbon atoms in the saturated hydrocarbon groups of the alkyl acrylate monomers of 4.4. Composition 2 was obtained by blending 1.0 part by mass of an adduct of tolylene diisocyanate and trimethylolpropane as a crosslinking agent ("Burnoc D-40" manufactured by DIC Corporation, isocyanate-based crosslinking agent, solid content 40%, hereinafter referred to as "D-40") into 100 parts by mass of the obtained acrylic copolymer solution. The obtained composition 2 was applied to the release-treated surface of a release liner so that the thickness after drying would be approximately 2 mm to prepare layer 2, and the storage modulus G' and loss modulus (G") were measured using a viscoelasticity tester (ARES-G2, manufactured by TA Instruments Japan) under conditions of a frequency of 1 Hz, a temperature range of -40°C to 200°C, and a heating rate of 2°C / min. In addition, the tan δ of composition 2 at a frequency of 1 Hz was calculated using the formula [tan δ=G" / G']. Composition 2 has a melting point of 150°C or higher and a storage modulus G at 23°C 23 is 7.5 x 10 4 Pa, and the storage modulus G at 120 °C 120 is 5.5 x 10 4Pa, and the temperature when tan δ was 0.8 was higher than 150°C (the temperature range where tan δ was 0.8 or higher was higher than 150°C). In addition, the maximum value of tan δ in the temperature range of 100°C to 150°C was 0.4.

[0098] 1. Examples of adhesive tape and product manufacturing [Example 1] <Preparation of adhesive tape> Resin composition 1 was applied to the release-treated surface of a release liner so that the thickness after drying would be 80 μm, and then dried at 90°C for 5 minutes to obtain a melt-softened layer c1 (thermal conductivity 0.16 W / m·K). On the other hand, Composition 2 was applied to the release-treated surface of another release liner so that the thickness after drying would be 50 μm, and then dried at 90°C for 3 minutes to prepare an adhesive layer (thermal conductivity 0.20 W / m·K). The thermal conductivity of the melt-softening layer and the adhesive layer is a value measured by a rapid thermal conductivity meter ("QTM-710" manufactured by Kyoto Electronics Manufacturing Co., Ltd.). A 50 mm long, melt-softening layer c1 cut to an arbitrary width was bonded to a 100 mm long heating element 1 using a hand roller, and the heating element 1 was positioned so that 25 mm extended from each end in the longitudinal direction. Similarly, a 50 mm long, cut adhesive layer with an arbitrary width was bonded to the opposite side of the heating element 1 bonded to the melt-softening layer c1, and the laminate was laminated from the top surface of the release liner using a roll with a linear pressure of 5 kg / cm and aged for 48 hours in an environment at 40°C. This produced a laminate in which both ends of the heating element 1 extended 25 mm from the outer periphery of the melt-softening layer c1 and adhesive layer in the longitudinal direction of the heating element 1, the total thickness excluding the release liner was 180 μm, and the layer structure excluding the release liner was the adhesive layer a1 / heating element 1 / melt-softening layer c1 in that order. The obtained laminate was cut to a width of 2 mm to obtain an adhesive tape (T-1) in which the melt-softening layer c1 and adhesive layer a1 were 2 mm wide x 50 mm long, the heating element 1 was 2 mm long x 100 mm long, and the heating element 1 had a pair of extensions extending from the outer peripheries of the melt-softening layer c1 and adhesive layer a1. A schematic plan view of the adhesive tape (T-1) is shown in Fig. 9, and a schematic cross-sectional view is shown in Fig. 10.

[0099] <Production of items> The adhesive tape of Example 1 (indicated by the symbol 10 in FIGS. 11 to 13) was peeled off from the release liner on the melt-softened layer c1 side, and applied to an adherend 50a (glass, width 40 mm × length 50 mm × thickness 10 mm) so that the 50 mm length of the tape adhesive surface (effective portion) crossed the center of the adherend 50a along the width direction of the adherend 50a (see FIGS. 11 to 13). Next, the release liner on the adhesive layer a1 side was peeled off, and the adhesive tape 10 was applied to an adherend 50b (glass, width 30 mm × length 100 mm × thickness 2.8 mm) in a sandwiched shape (see FIGS. 11 to 13), and a pressure of 20 N / cm was applied. 2 The resulting adhesive sheet was left to stand in an atmosphere of 23° C. and 50% RH for 24 hours or more, thereby obtaining an article of Example 1.

[0100] [Example 2] An adhesive tape (T-2) and an article of Example 2 were produced in the same manner as in Example 1, except that heat generating element 2 was used instead of heat generating element 1 in Example 1. [Example 3] An adhesive tape (T-3) and an article of Example 3 were produced in the same manner as in Example 1, except that heat generating element 3 was used instead of heat generating element 1 in Example 1. [Reference example 1] An adhesive tape (RT) and an article of a reference example were produced in the same manner as in Example 1, except that heat generating element 4 was used instead of heat generating element 1 in Example 1.

[0101] 2. Evaluation The push strength of the articles obtained in each of the Examples and Reference Examples was measured using the device shown in FIGS. 11 to 13 as follows. (1) Push strength before heating The articles obtained in each of the Examples and Reference Examples were used as test specimens, and in an environment of 23°C, a glass plate was pressed at the pressing position shown in Figure 11 in the direction of the arrow using the probe 70 shown in Figures 12 and 13 at a speed of 10 mm / min, and the strength at which the adhesive tape peeled off [push strength (G1)] was measured. (2) Push strength after 10 seconds of heating The articles obtained in each Example and Reference Example were used as test specimens. The heating element extension e of the adhesive tape 10 of each test specimen was clamped with alligator clips 60, and a current of 0.3 A was passed through the test specimen using a DC stabilized power supply (manufactured by Kikusui Electronics Co., Ltd., product name "PAS160-1"). Ten seconds after the start of current application, the glass plate was pressed in the direction of the arrow at a speed of 10 mm / min with probe 70 shown in Figures 12 and 13 while continuing to pass current, and the strength at which the adhesive tape peeled off [push strength (G2)] was measured. The temperature of the heating element (the dismantling temperature of the article) reached when the 0.3 A current was passed through the test specimen and heated to dismantle was approximately 95°C. The temperature of the heating element after the current was applied was measured by a temperature sensor using a thermocouple. (3) Residual adhesive strength Using the push strength (G1) and the push strength (G2), the residual adhesive strength was calculated using the following formula, and the dismantling properties were evaluated according to the following criteria. Residual adhesive strength (%)=100×G2 / G1 [Evaluation criteria for dismantling] ○: Residual adhesive strength is less than 75% △: Residual adhesive strength is 75% or more but less than 90% ×: Residual adhesive strength is 90% or more The above results are summarized in Table 1.

[0102] [Table 1]

[0103] The adhesive tapes of each Example had a smaller residual adhesive strength [%] after heating with an electric current of 0.3 A than the Reference Example. That is, the articles made using the adhesive tapes of each Example had a large rate of decrease in adhesive strength relative to the initial adhesive strength even when a low electric current that does not physically affect the worker was passed through, and were excellent in dismantling properties. [Industrial Applicability]

[0104] The pressure-sensitive adhesive tape of the present invention can be peeled off by heating in a short time, can prevent thermal damage to the adherend, and is easy to operate for heating and peeling. Therefore, the pressure-sensitive adhesive tape of the present invention can be suitably used in applications where peeling of the pressure-sensitive adhesive tape is required for separating parts for the purpose of reuse or recycling, for example, as a pressure-sensitive adhesive tape for fixing parts of various products in industrial applications such as electronic devices, automobiles, building materials, office automation, and home appliances, and improves work efficiency when separating parts or peeling labels. [Explanation of symbols]

[0105] a, a1, a2: Adhesive layer b: Heating element c: Melt-softened layer e: Extension part (of the heating element) 10, 20, 30: adhesive tape 50, 50a, 50b: Adherent 100: Goods 60: Alligator clip 70: Probe P: Press position

Claims

1. An adhesive tape comprising an adhesive layer, a heating element, and a melt-softening layer adjacent to the heating element, at least in this order, wherein the heating element has an average thickness of 2 μm or more and 200 μm or less, and the heating element is formed into a sheet by binding conductive fillers.

2. The pressure-sensitive adhesive tape according to claim 1 , wherein the heating element has a volume resistivity of 50 μΩ·cm or more at 20° C.

3. 2. The pressure-sensitive adhesive tape according to claim 1, wherein the heating element is a sheet formed by binding fibrous or particulate conductive fillers and further impregnating the sheet with a binder.

4. The pressure-sensitive adhesive tape according to claim 1 , wherein the heat generating element is a sheet formed by binding a fibrous or particulate conductive filler and an organic filler.

5. The pressure-sensitive adhesive tape according to claim 1 , wherein the heating element is a sheet made by sintering a fibrous or particulate conductive filler.

6. The adhesive tape according to claim 1 , wherein the conductive filler is selected from the group consisting of metals, alloys, and carbon.

7. The pressure-sensitive adhesive tape according to claim 1 , wherein the heating element has, in a plan view, a pair of extension portions extending from outer peripheries of the pressure-sensitive adhesive layer and the melt-softening layer.

8. The adhesive tape according to claim 1 , further comprising an adhesive layer on the surface of the melt-softenable layer opposite to the surface adjacent to the heating element.

9. The pressure-sensitive adhesive tape according to claim 1 , wherein the melt-softening layer becomes peelable by heating.

10. The pressure-sensitive adhesive tape according to claim 1 , wherein the heating element is an electric conductor that generates heat when an electric current is applied thereto, and the pressure-sensitive adhesive tape is peeled off by the heat generated by the electric conductor.

11. At least two adherends; and the adhesive tape according to any one of claims 1 to 10 between two of the adherends, An article in which the two adherends are bonded together via the adhesive tape.

12. The article according to claim 11 , wherein, in a plan view, the heating element constituting the pressure-sensitive adhesive tape has a pair of extension portions extending from an outer periphery of the adherend.

13. The method for dismantling an article according to claim 11, wherein the melt-softening layer is melted and / or softened by heating with the heating element to separate the two adherends.

14. 14. The method for dismantling articles according to claim 13, wherein the heating of the heating element is resistance heating, the heating element is electrically connected to a power source, electricity is passed from the power source to the heating element, and the melt-softened layer is melted and / or softened by resistance heating, thereby separating the two adherends.

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