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

Abstract

To provide a pressure-sensitive adhesive tape which has a small content of a volatile component, reduces an adverse effect on an external environment, 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 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 melting and softening layer contains a thermoplastic resin having a weight average molecular weight of 80000 to 150000 and a tackifier resin having a mass reduction rate of 3% or less when heated from 25 °C to 200 °C at a heating rate of 10 °C / min under nitrogen.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] 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. On the other hand, from the viewpoint of addressing environmental pollution, there is a demand for reducing emissions of volatile organic substances (VOCs) into the external environment. When raw materials used to produce pressure-sensitive adhesive tapes contain solvents, it is preferable that they do not contain environmentally restricted substances from the viewpoint of environmental regulations. Toluene, a VOC, is an environmentally restricted substance that is often used as a raw material. Its handling is strictly restricted by REACH regulations, the PRTR Act, VOC regulations, etc., and reduction of toluene is required. From this perspective, there is still room for improvement in the selection of solution-type raw materials that do not cause problems in solubility, miscibility, etc. even when toluene is not used and can still exhibit the above-mentioned functions of the adhesive tape.

[0006] The present inventors have discovered that the above-mentioned problems can be solved by an adhesive tape having a melt-softening layer containing a specific thermoplastic resin and a specific tackifier resin, in which the adhesive layer, heating element, and the melt-softening layer have a specific configuration, and have arrived at the present invention. That is, an object of the present invention is to provide an adhesive tape which has an extremely low content of volatile organic substances when dismantled, can be heated and peeled off in a short time, can prevent thermal damage to an adherend, and is easy to operate for heating and peeling, an article having a structure adhered with the adhesive tape, and a method for dismantling the article. [Means for solving the problem]

[0007] The present invention relates to the following (1) to (16). (1) A pressure-sensitive adhesive tape having, at least in this order, a pressure-sensitive adhesive layer, a heating element, and a melt-softening layer adjacent to the heating element, wherein the melt-softening layer contains a thermoplastic resin having a weight-average molecular weight of 80,000 to 150,000, and a tackifier resin having a mass loss rate of 3% or less when heated from 25°C to 200°C at a temperature rising condition of 10°C / min under nitrogen. (2) The pressure-sensitive adhesive tape according to (1), wherein the thermoplastic resin constituting the melt-softening layer contains 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. (3) The pressure-sensitive adhesive tape according to (1), wherein the storage modulus of the melt-softening layer at 150°C is 1.0 × 10 3 ~1.0×10 5(4) The pressure-sensitive adhesive tape according to any one of (1) to (3), wherein the melt flow rate (MFR: 190°C, 21.6 kg load) of the thermoplastic resin constituting the melt-softening layer is 9 g / 10 min or more. (5) The pressure-sensitive adhesive tape according to any one of (1) to (4), wherein the content of the thermoplastic resin constituting the melt-softening layer is 30 to 80 mass% with respect to the entire composition constituting the melt-softening layer. (6) The pressure-sensitive adhesive tape according to any one of (1) to (5), wherein the content of the tackifier resin constituting the melt-softening layer is 20 to 100 mass parts with respect to 100 mass parts of the thermoplastic resin constituting the melt-softening layer. (7) The pressure-sensitive adhesive tape according to any one of (1) to (6), wherein, when the pressure-sensitive adhesive tape is heated at 150°C for 30 seconds in a nitrogen atmosphere, the mass loss rate of the pressure-sensitive adhesive tape after heating relative to the mass of the pressure-sensitive adhesive tape before heating is 0.5% or less. (8) The pressure-sensitive adhesive tape according to any one of (1) to (7), wherein the heating element has a volume resistivity of 30 μΩ·cm or more at 20°C. (9) The pressure-sensitive adhesive tape according to any one of (1) to (8), wherein, in a plan view, the heating element has a pair of extension portions extending from the outer peripheries of the adhesive layer and the melt-softening layer. (10) The pressure-sensitive adhesive tape according to any one of (1) to (9), wherein the melt-softening layer further has an adhesive layer on the side opposite to the side adjacent to the heating element. (11) The pressure-sensitive adhesive tape according to any one of (1) to (10), wherein the melt-softening layer becomes peelable by heating. (12) The pressure-sensitive adhesive tape according to any one of (1) to (11), wherein the heating element is an electric conductor that generates heat when electricity is passed through it and is peeled off by the heat generated by the electric conductor.

[0008] (13) An article comprising at least two adherends and the pressure-sensitive adhesive tape according to any one of (1) to (12) between the two adherends, the two adherends being bonded via the pressure-sensitive adhesive tape. (14) The article according to (13), 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 adherends. (15) The method for dismantling articles according to (13) or (14), wherein the melt-softening layer is melted and / or softened by heating from the heating element, thereby separating the two adherends. (16) The method for dismantling articles according to (15), wherein the heating from the heating element is resistance heating, the heating element is electrically connected to a power source, current is applied from the power source to the heating element, and the melt-softening layer is melted and / or softened by resistance heating, thereby separating the two adherends. [Effects of the Invention]

[0009] According to the present invention, it is possible to provide an adhesive tape that has a low content of volatile components, has a reduced adverse effect on the external environment, can be heated and peeled off in a short time, can prevent thermal damage to the adherend, and is easy to operate when heated and peeled off. Furthermore, the present invention can provide an article in which at least two adherends are adhered via the pressure-sensitive adhesive tape, and a method for dismantling the article. The article and the method for dismantling an article of the present invention suppress thermal degradation of adherends such as electronic components, making them reusable and facilitating dismantling work. Furthermore, the content of volatile components is low, which reduces the adverse effects on the external environment due to smoke, etc., and is also excellent in terms of safety for workers during dismantling. [Brief explanation of the drawings]

[0010] [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

[0011] 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.

[0012] 1. Adhesive tape The present invention provides an 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 melt-softening layer contains a thermoplastic resin having a weight-average molecular weight of 80,000 to 150,000, and a tackifier resin that exhibits a mass loss rate of 3% or less when heated from 25°C to 200°C at a temperature increase rate of 10°C / min under nitrogen. The pressure-sensitive adhesive tape of the present invention can be used as an easily dismantled pressure-sensitive adhesive tape that can easily separate or dismantle the bonded portions between adherends after a certain period of time has passed after application to adherends 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 adherends, maintains high adhesive strength when fixing the adherends together, and can be easily separated or dismantled by heating when separating or dismantling the adherends. Note that "separation or dismantling" will hereinafter also be referred to simply as "dismantling."

[0013] 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 melt-softening layer contains a thermoplastic resin having a weight-average molecular weight within a specific range and a tackifier resin having a thermal mass loss rate within a specific range or less, so that the melt-softening layer has a low content of volatile components and sufficient initial adhesive strength, and as a result, the thermoplastic resin constituting the melt-softening layer can be efficiently melted or softened. 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. In other words, since the adhesive tape of the present invention generates heat inside the tape, 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. Furthermore, since the adhesive tape of the present invention has a low content of volatile components, adverse effects on the external environment due to smoke, etc., when fixing adherends to each other or when peeling and dismantling by heating are reduced, and the tape is also excellent in terms of safety for workers during dismantling.

[0014] 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 heated and peeled off using the drive current within the electronic components while the articles are built into electronic equipment, thermal deterioration of the circuits within the electronic components can be prevented, and heating and peeling can be performed without the need for external equipment, making the disassembly work easier.

[0015] The embodiment in which the pressure-sensitive adhesive tape of the present invention is "made releasable by heating" may be an embodiment in which the pressure-sensitive adhesive tape, particularly the melt-softening layer itself, melts or softens upon heating, causing cohesive failure within the melt-softening layer, and part or all of the pressure-sensitive adhesive tape peels off from the adherend, or an embodiment in which the pressure-sensitive adhesive tape, particularly the melt-softening layer itself, melts or softens upon heating, thereby reducing its adhesive strength, causing peeling (interfacial failure) between the melt-softening layer and a layer adjacent to the melt-softening layer or the adherend, making part or all of the pressure-sensitive adhesive tape releasable 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 part of the melt-softening layer may peel off from the adherend. Furthermore, the adhesive layer constituting the pressure-sensitive 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, by generating heat from the heating element, the pressure-sensitive adhesive tape of the present invention can selectively melt or soften the melt-softening layer, thereby making it peelable. The configuration of the pressure-sensitive adhesive tape of the present invention will be described below.

[0016] [Heater] The heating element can be appropriately selected from known heating elements depending on the heating means used. Examples of heating and heating means include resistance heating, electromagnetic induction heating, infrared heating, microwave heating, thermal conduction, etc. Among these, resistance heating is preferred from the viewpoint that the melt-softened layer can be sufficiently softened or melted even with a small amount of energy, and that, for example, the pressure-sensitive adhesive tape can be thermally disassembled using a driving current in an electronic component while it is built into an electronic device, and that excessive heating of the adherend can be prevented because there is no need to heat the heating element using an external heat source via the adherend.

[0017] 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 thermal energy using electromagnetic waves in specific wavelength ranges, such as infrared and microwaves. The atomic bonds and molecules that make up a substance undergo thermal vibrations (molecular movement and crystalline lattice vibrations) that correspond to the substance's own temperature, and when electromagnetic waves of 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.

[0018] When the heating means is resistance heating, the heating element is preferably a conductive material having resistance, such as a metal, a nonmetal, or an organic-inorganic composite material. Examples of metals include nichrome (108 μΩ·cm); stainless steels such as SUS410 (62.2 μΩ·cm), SUS304 (72.0 μΩ·cm), and SUS430 (60.0 μΩ·cm); titanium (55.0 μΩ·cm); nickel silver (e.g., 34.0 μΩ·cm for "Nickel Silver C7701" manufactured by Takeuchi Metal Foil Powder Co., Ltd.), and metal fiber sheets (e.g., "Stainless Steel Fiber Sheet" manufactured by Tomoegawa Paper Mills). The values ​​in parentheses indicate the approximate volume resistivity of each material at 20°C. Among these, nichrome and stainless steel are preferred from the viewpoints that they are difficult to tear when made into a foil, are easy to handle as a tape, and can melt the melt-softened layer in a short time to significantly reduce the adhesive strength. Examples of non-metals include carbon (3352 μΩ·cm, for example) such as carbon nanomaterials such as graphite, graphene, graphene oxide, carbon nanotubes, graphene platelets, and carbon nanofibers. Examples of organic-inorganic composite materials include metal-deposited films in which a metal such as aluminum or chromium is deposited on a polyester film, conductively plated woven or nonwoven fabrics, and conductively coated films.

[0019] When the heating means is resistance heating, the volume resistivity of the heating element at 20°C is preferably 30 μΩ·cm or more, more preferably 50 μΩ·cm or more, even more preferably 70 μΩ·cm or more, and particularly preferably 100 μΩ·cm or more. To avoid increasing the voltage required when energizing the heating element too much, 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 30 to 100,000 μΩ·cm, 50 to 20,000 μΩ·cm, 70 to 10,000 μΩ·cm, or 100 to 5,000 μΩ·cm.

[0020] If the volume resistivity of the heating element is 30 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 flowing through the heating element, thereby preventing thermal degradation of the electronic component.

[0021] 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 MCP-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.

[0022] When the heating means is electromagnetic induction heating, the heating element is preferably a current-carrying element having resistance, such as metals such as iron, aluminum, nickel, stainless steel, zinc, lead, magnesium, oxides or alloys of these metals, etc. Among these, aluminum and iron are preferred.

[0023] When the heating means is infrared heating or microwave heating, the heating element is preferably a substance that has the property of absorbing specific wavelengths of infrared heating or microwave heating and generating thermal vibration (heat), such as organic substances and inorganic substances. Examples of organic substances include resins, rubbers, fibers, organic dyes, organic dyes, and organic pigments. Examples of inorganic substances include metallic inorganic substances, non-metallic inorganic substances, inorganic pigments, inorganic dyes, and inorganic pigments. Examples of metallic inorganic substances include non-ferrous metals such as aluminum, titanium, chromium, manganese, cobalt, nickel, magnesium, zinc, and copper; iron; and oxides of the above non-ferrous metals and iron. Examples of non-metallic inorganic substances include silicon, carbon, silicon oxides (eg, SiO2), and the like.

[0024] When the heating means is thermal conduction, the heating element is preferably made of a material with excellent thermal conductivity, such as a metal or non-metal. Examples of metals include aluminum, iron, copper, and oxides and nitrides of these metals. Examples of non-metallic materials include ceramics such as silicon carbide, graphite, and the like.

[0025] When the heating means is resistance heating, the shape of the heating element is not particularly limited as long as the heating elements are in electrical contact with each other so as to generate resistance heating, and can be appropriately selected depending on the purpose, and examples include a planar, mesh, particulate, fibrous, etc. Among these, a planar shape is preferred from the viewpoint that it can adhere sufficiently to the melt-softened layer in contact with the heating element before electricity is applied, and that the heating element itself is less likely to be destroyed or broken when electricity is applied because heat is generated on the surface. Examples of planar heating elements include metal foils made of the aforementioned metals; sheets of the aforementioned non-metals; resin films or sheets in which particles or fibers made of the aforementioned metals or non-metals are densely dispersed, such as metal-deposited films, conductively plated woven or non-woven fabrics, or conductively coated films; coatings of the aforementioned metals or non-metals; sheets in which non-woven fabrics are impregnated with the aforementioned metals or non-metals; and non-woven fabrics of the aforementioned metals or non-metals, such as metal fiber sheets. The planar heating element may also be a heating element formed by binding fibrous or particulate conductive fillers composed of at least one of the above-mentioned metals, alloys, or carbon together by sintering to form a sheet, or a heating element formed by binding such fibrous or particulate conductive fillers together to form a sheet, which is then impregnated with a binder. The fibrous or particulate conductive filler is preferably formed into a nonwoven fabric, which is then bound by sintering to form a sheet, thereby forming a heating element.

[0026] The planar heating element may be formed into a pattern, or may be in a strip or line shape (see also Figure 4 described below). A strip or line heating element is advantageous in that it has high heat generation efficiency and is easy to peel off due to a small contact area with the adherend. In this case, the length of the heating element in the minor axis direction (band 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.

[0027] 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. This increases the heat generation efficiency of the planar heating element, allowing the adhesive tape of the present invention to be peeled off in a short time. When the planar heating element is in a pattern, the pattern width is not particularly limited, and can be the same as the preferred range of the band width.

[0028] The planar heating element may be disposed on one or both surfaces of the substrate, in which case the heating element is disposed so as to be in direct contact with one or both surfaces of the substrate. The heating element may be arranged so as to cover the entire area of ​​one or both surfaces of the substrate, and may be arranged 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.

[0029] Examples of the mesh-shaped heating element include a planar heating element having a plurality of through holes, a mesh-shaped or lattice-shaped heating element, etc. These may also be integrally molded heating elements.

[0030] Furthermore, the shape of the heating elements does not necessarily have to be integrally molded as long as the heating elements can be electrically contacted with each other. For example, the heating element may be a particle or fiber made of the metal or non-metal, and particulate, mesh-like, or fibrous heating elements may be dispersed in the resin film serving as the base material described above, thereby forming electrical contact between the heating elements. When particulate, mesh-like or fibrous heating elements are dispersed in the resin film as the substrate, the content of the particulate or fibrous heating elements in the resin film as the substrate is preferably 20 to 95 mass %, more preferably 40 to 90 mass %.

[0031] The average thickness of the planar heating element is usually 1 μm or more, preferably 2 μm or more, more preferably 3 μm or more, even more preferably 5 μm or more, and particularly preferably 10 μm or more. The average thickness of the planar heating element is preferably 200 μm or less, more preferably 150 μm or less, even more preferably 100 μm or less, and particularly preferably 50 μm or less. 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.

[0032] When the heating means is electromagnetic induction heating or heat conduction, the shape of the heating element can be selected appropriately, and may be, for example, a sheet, a mesh, or a resin film or sheet in which particles or fibers comprising the heating element are densely dispersed. The planar heating element may be molded into a pattern, or may be in a strip or line shape. When the heating element is in a strip or line shape, the heating efficiency is high and the contact area with the adherend is small, making it easy to peel off. The length of the heating element in the minor axis direction (band width or line width) is preferably 1 to 10 mm, more preferably 2 to 5 mm. The average thickness of the planar heating element is preferably 5 to 200 μm, more preferably 10 to 150 μm, and even more preferably 12 to 100 μm.

[0033] When the heating means is infrared heating or microwave heating, the heating element may be a resin film or sheet in which particles or fibers made of the heating element are dispersed at a high density. When the heating means is infrared heating, a pigment or the like may be used as the infrared absorbing material, and such a pigment may be dispersed in a resin film or sheet, or may be coated on the resin film or sheet by painting or the like.

[0034] The heating element may be manufactured as needed, or a commercially available product may be used. Examples of commercially available products include sheet heating elements made of nichrome foil, stainless steel foil, titanium foil, nickel silver, etc., such as "NCH1-H," "SUS304-H," "SUS430-H," "TR270C-H," and "Nickel Silver C7701" (all manufactured by Takeuchi Metal Foil Powder Co., Ltd.); and "Stainless Steel Fiber Sheet" manufactured by Tomoegawa Paper Co., Ltd. Patterned versions of these may also be used.

[0035] [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-softenable layer, which will be described later, of the pressure-sensitive adhesive tape of the present invention. A pressure-sensitive adhesive is an adhesive that adheres by applying pressure for a short period of time at room temperature around 20°C, and has tackiness at room temperature.

[0036] Examples of the acrylic polymer include a homopolymer of a (meth)acrylic acid ester monomer, and a copolymer of a (meth)acrylic acid ester monomer and another monomer. 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.

[0037] 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.

[0038] 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 %.

[0039] 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.

[0040] 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.

[0041] 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 %.

[0042] 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, the GPC measurement is performed using a Tosoh Corporation "SC8020" GPC measuring device 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

[0043] The adhesive layer may further contain a tackifier resin for the purpose of adjusting its adhesiveness. Details of the tackifier resin will be described later in the section on the melt-softening layer. When the adhesive 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 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, relative to the total solid content of the adhesive.

[0044] 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.

[0045] 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.

[0046] 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.

[0047] 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).

[0048] 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-softened layer has a tan δ of 0.8 or higher. In particular, it is more preferable that the temperature at which the adhesive layer (adhesive layer composition) has a tan δ of 0.8 or higher is 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.

[0049] 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. 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, from the viewpoint of allowing the adhesive layer to exhibit viscosity and elasticity.

[0050] 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.

[0051] 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'].

[0052] 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.

[0053] [Melting and softening layer] The melt-softening layer constituting the pressure-sensitive adhesive tape of the present invention contains a thermoplastic resin having a weight-average molecular weight of 80,000 to 150,000, and a tackifier resin that exhibits a mass loss rate of 3% or less when heated from 25°C to 200°C at a temperature increase rate of 10°C / min under nitrogen.

[0054] <Thermoplastic resin> Examples of thermoplastic resins include urethane resins, polycarbonates, vinyl chloride resins, acrylic resins, crystalline or amorphous polyester resins such as polyethylene terephthalate, polyamide resins, styrene resins, olefin resins, cellulose resins, silicone resins, fluorine resins, styrene thermoplastic elastomers, olefin thermoplastic elastomers, vinyl chloride thermoplastic elastomers, acrylic thermoplastic elastomers, urethane thermoplastic elastomers, ester thermoplastic elastomers, amide thermoplastic elastomers, etc. These may be used alone or in combination of two or more.

[0055] The weight-average molecular weight of the thermoplastic resin is in the range of 80,000 to 150,000, and more preferably in the range of 80,000 to 130,000. When the weight-average molecular weight is in this range, the storage modulus and loss tangent of the melt-softening layer can be easily adjusted to fall within desired ranges, making it easier to melt or soften the melt-softening layer by heating. Furthermore, the viscosity of the melt-softened layer when softened can be reduced, making it easier to dismantle. The weight-average molecular weight of the thermoplastic resin can be determined in the same manner as the method for measuring the weight-average molecular weight of the acrylic polymer described above. The melt flow rate (MFR: 190°C, 21.6 kg load) or melt index (MI: 190°C, 21.6 g load) of the thermoplastic resin preferably has a value corresponding to the range of the weight average molecular weight described above, and is preferably 9 g / 10 min or more. For example, in the case of a styrene-based thermoplastic elastomer described below, the range of 9 to 30 g / 10 min, and more preferably 10 to 25 g / 10 min, is preferably measured at 190°C and 21.6 g load.

[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 constituting the melt-softening layer is preferably in the range of 30 to 80 mass %, more preferably in the range of 35 to 70 mass %, based on the entire composition constituting the melt-softening layer. If the blending amount of the thermoplastic resin in the melt-softening layer is within the above range, it is advantageous from the viewpoint of the coatability of the melt-softening layer and the control of the melt-softening temperature.

[0057] 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 pressure-sensitive adhesive tape of the present invention, and can melt or soften the melt-softened layer without containing a component that generates a peeling starting point at the adhesive interface or a component that causes a decrease in adhesive strength, such as a heat-foaming agent. Therefore, the pressure-sensitive adhesive tape is easily peelable, and preferably has a softening point, and is advantageous in that the melt-softened layer rapidly becomes flexible at a temperature higher than the softening point, thereby exhibiting high deformability and fluidity.

[0058] 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.

[0059] 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.

[0060] <Tackifying resin> The tackifier resin contained in the melt-softening layer has a mass loss rate of 3% or less when heated from 25°C to 200°C at a temperature increase rate of 10°C / min under nitrogen. The mass loss rate is more preferably 1% or less, and may be 0%. In other words, a tackifier resin having a mass reduction rate within the above range is a tackifier resin having a low content of low molecular weight, easily volatile components. If the melt-softening layer contains the tackifier resin described above, smoke generation due to volatile components can be suppressed when the melt-softening layer is heated, and adverse effects on the external environment can be reduced. The mass loss rate of the tackifier resin can be determined by measuring the mass loss when the temperature is raised from 25°C to 200°C at a rate of 10°C / min using a commercially available thermogravimetric differential thermal analyzer (TG-DTA; for example, Hitachi High-Tech Science Corporation, product name "TG-DTA7200").

[0061] Examples of tackifying resins include various tackifying resins such as 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. A commercially available tackifier resin can be used, and an adhesive resin that satisfies the mass loss rate within the above range can be applied to the melt-softening layer in the adhesive tape of the present invention. In addition, tackifying resins that are liquid at room temperature (25°C), such as process oil, polyester-based tackifying resins, and low-molecular-weight liquid rubbers such as polybutene, can also be used in the melt-softening layer of the adhesive tape of the present invention, so long as they satisfy the mass loss rate within the above-mentioned range. The tackifier resin may be contained alone or in combination of two or more kinds.

[0062] The content of the tackifier resin in the melt-softening layer is preferably in the range of 20 to 100 parts by mass, more preferably 30 to 90 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, the total content of the thermoplastic resin and tackifier 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 tackifier resin, as well as any optional crosslinking agents, fillers and other additives.

[0063] <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 constituting 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 using 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 filler or inorganic filler is usually preferably in the range of 0.01 to 30% by mass, more preferably 0.02 to 20% by mass, relative to the total mass of the melt-softening layer.

[0064] 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. 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.

[0065] <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" refers to the melting point of the composition containing the thermoplastic resin that constitutes the melt-softening layer. In this specification, the "composition containing the 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 and a tackifying resin that constitute the melt-softening layer, and optionally 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).

[0066] 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 preferred, 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 preferred, 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. Storage modulus G of the melt-softened layer at 150°C 150 is 1.0 × 10 3 Pa~1.0×10 5 Pa is preferred, 5.0 x 10 3 Pa~1.0×10 5 Pa is more preferable. Storage modulus G 150 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.

[0067] 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.

[0068] 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 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 melt-softening layer reaches a desired decomposition temperature range described below due to the heat generated from the heating element, plastic deformation is more likely to occur due to melting or softening, and cohesive failure within the melt-softening layer can cause peeling within the melt-softening layer or at the interface between the melt-softening 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.

[0069] The storage modulus G and tan δ of the melt-softened layer (that is, the melt-softened resin composition) can be determined by dynamic viscoelasticity measurement. For example, a test piece of the melt-softened resin composition having 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 conditions of a frequency of 1 Hz, a temperature range of -40°C to 200°C, and a heating rate of 2°C / min. Tan δ is calculated using the formula [tan δ=G” / G']. When the melt-softening layer contains a filler, the above-described dynamic viscoelasticity measurement is carried out on the melt-softening resin composition excluding the filler to determine the storage modulus G and tan δ.

[0070] 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.

[0071] 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.

[0072] 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.

[0073] When the pressure-sensitive adhesive tape of the present invention is heated at 150°C for 30 minutes in a nitrogen atmosphere, the mass loss rate of the pressure-sensitive adhesive tape after heating relative to the mass of the pressure-sensitive adhesive tape before heating is 0.5% or less, preferably in the range of 0.0 to 0.4%, and more preferably in the range of 0.0 to 0.2%. The pressure-sensitive adhesive tape of the present invention, in which the mass loss rate before and after heating is within the above-mentioned range, has a low content of volatile components due to the pressure-sensitive adhesive layer and the melt-softening layer containing specific constituents, and therefore reduces adverse effects on the external environment due to smoke, etc., when peeled off and disassembled by heating. In addition, the pressure-sensitive adhesive tape of the present invention has excellent dismantling properties and is also excellent in terms of safety for workers during dismantling.

[0074] The pressure-sensitive adhesive tape of the present invention has a push strength of 40 N / 0.8 cm before heating, as measured by the method described in the Examples. 2 It is preferable that the strength is more than 45N / 0.8cm. 2 When the pre-heating push strength is within the above range, the pressure-sensitive adhesive tape of the present invention and the adherend are sufficiently adhered to each other, and therefore the pressure-sensitive adhesive tape can be used as a joining means with high adhesive reliability. In addition, when an article adhered using the pressure-sensitive adhesive tape of the present invention is peeled off by resistance heating (electrical heating), the pressure-sensitive adhesive tape of the present invention has a push strength of 2.90 N / 0.8 cm after being heated by electrical current at 1.5 A for 10 seconds. 2 Preferably less than 2.5N / 0.8cm 2 More preferably, it is 2.0N / 0.8cm or less. 2 When the push strength after heating with electricity at 1.5 A for 10 seconds is within the above range, the pressure-sensitive adhesive tape of the present invention can be easily peeled from the adherend after heating, and the dismantling property is excellent.

[0075] [Layer structure of adhesive tape] 1 and 2, the first embodiment of the pressure-sensitive adhesive tape of the present invention may be a laminate embodiment in which the pressure-sensitive 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. 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 enabling peeling.

[0076] 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)).

[0077] 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.

[0078] The extensions e may be provided at 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 function as a pair of terminals for electrically connecting to a power source in the article dismantling method described below, making it possible to easily apply electricity to the heating element b.

[0079] The length of the extension is preferably 1 to 50 mm, more preferably 2 to 25 mm, in order to facilitate contact with a power source or a heat generating source. Each extension portion 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 may be folded in a direction perpendicular to the surface direction of the adhesive tape and stored, and when the bond between the adherends is to be released (during disassembly), the extension portion may be folded again in the surface direction to bring the extension portion into contact with a power source or a heat generating source.

[0080] The pressure-sensitive adhesive tape of the present invention may also have a second embodiment in which the pressure-sensitive adhesive tape 20 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 Fig. 5. Alternatively, the pressure-sensitive adhesive tape 20 may be a laminate in which adhesive layer a1 / melt-softening layer c1 / heat generating element b / melt-softening layer c2 are laminated in this order, and in this case, an adhesive layer a2 may be further provided on the side of melt-softening layer c2 opposite to the heat generating element b side. That is, a second embodiment of the pressure-sensitive adhesive tape of the present invention includes 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 that is different from the side adjacent to the heating element b. Another example of the second embodiment includes a laminate having a heating element b, melt-softening layers c1 and c2 arranged on both sides of the heating element b, an adhesive layer a1 arranged on a side of the melt-softening layer c1 that is different from the side adjacent to the heating element b, and an adhesive layer a2 arranged on a side of the melt-softening layer c2 that is different from the side adjacent to the heating element b. The heat generated by 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 adhesive tape of the present invention of the second embodiment, in which an adhesive layer is further provided on a surface (opposite surface) of the melt-softening layer different from the surface adjacent to the heating element, 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.

[0081] 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.

[0082] 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.

[0083] 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.

[0084] 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

[0085] 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.

[0086] [Uses of adhesive tape] The pressure-sensitive adhesive tape of the present invention has both surfaces, excluding the release layer, that function as adhesive surfaces (adhesive surfaces), and therefore adherends can be attached to both surfaces of the pressure-sensitive 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 to each other and for separating adherends from each other. Since the pressure-sensitive adhesive tape of the present invention can be easily peeled off by heating, it 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 an adhesive tape for fixing components of various products in industrial applications such as electronic devices, automobiles, building materials, office automation, and home appliances, and improves work efficiency when separating components or peeling off labels.

[0087] [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. However, since toluene has been subject to strict restrictions in recent years as an environmentally regulated substance under the REACH regulation, the PRTR Act, VOC regulation, etc., solvents other than toluene, such as organic solvents such as ethyl acetate, propyl acetate, butyl acetate, acetone, methyl ethyl ketone, and hexane; water; or aqueous solvents mainly composed of water, are preferred. By using the above-mentioned solvents other than toluene in the composition containing the components constituting the adhesive layer and the composition containing the components constituting the melt-softening layer, it is possible to comply with the reduction in toluene required from the standpoint of environmental regulations. In general, it is preferred that the adhesive layer and melt-softenable layer of the resulting adhesive tape do not contain a solvent.

[0088] 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.

[0089] 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 either resistance heating or thermal conduction in the article dismantling method described below, making it possible to easily heat the heating element b of the adhesive tape 10. Furthermore, as shown in Figure 6, when viewed in a plan view, a smaller contact area between the adherend and the adhesive tape is advantageous in that the heat generation efficiency of the heating element is higher and disassembly is easier because it is more likely to trigger disassembly 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.

[0090] In a plan view of the article, the adhesive tape may be attached to the entire adherend surface, which is the surface of the adherend facing the adhesive tape, or the adhesive tape may be attached to a portion of the adherend surface. In particular, as shown in Fig. 6, it is preferable that the adhesive tape 10 is attached to a portion of the adherend surface of the adherend 50. In this case, the shape of the adhesive tape 10 in the article in a plan view may be a strip or line, or may be a patterned shape. If the contact area between the adherend and the adhesive tape is small, when the adhesive tape is peeled off from the adherend by resistance heating, a starting point for peeling is more likely to occur between the adherend and the adhesive tape, which is advantageous in terms of making peeling easier. 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.

[0091] 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.

[0092] 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 electronic device or an article that is 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 the driving power source of the electronic device, the separation process is preferably a process of electrically connecting the heating element to the driving power source and electrical circuit of the electronic device, passing electricity from the driving 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 the heating element or a pair of extensions of the heating element extending from the outer periphery of the adhesive layer and the melt-softening layer to the power source using known means such as alligator clips. The electrical circuit and the electrical connection means are preferably formed from a conductive material that exhibits a volume resistivity different from that of the material of the heating element in the adhesive tape, and more preferably from a conductive material that has a volume resistivity lower than that of the heating element. In this case, when the heating element and the electrical circuit are electrically connected and electricity is passed through the heating element from the driving power source, excessive heating of the electrical circuit and the electrically connecting means can be prevented, while voltage can be efficiently applied to the heating element, allowing it to be peeled off in a short time, which is advantageous.

[0093] The method of applying electricity can be selected appropriately depending on the size of the pressure-sensitive adhesive tape of the present invention or the type of heating element, and examples include 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). A simple power supply can be used as shown schematically in Figure 8. The heating element of the pressure-sensitive adhesive tape of the present invention is electrically connected to a power supply, and a voltage is applied to the heating element to energize it, thereby heating the heating element and its surroundings by resistance heating. By this heating, the melt-softening layer melts or softens, releasing the adhesive state and making the bonded adherends peelable, allowing them to be disassembled.

[0094] 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 adhesive tape of the present invention, the melt-softening layer melts or softens in a short time even when a low voltage is applied. Therefore, by applying a voltage within the above range in the separation process, the articles can be disassembled in a short time without applying excessive voltage, and damage to the articles due to heat can be prevented. In particular, by applying a voltage that can be handled by small electronic devices, household electrical appliances, and other items, these items can be easily dismantled.

[0095] The current applied to the heating element is not particularly limited, and is usually 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. In the pressure-sensitive adhesive tape of the present invention, the melt-softening layer melts or softens in a short time, so if the current applied in the separation step is in the above range, the articles can be disassembled in a short time by passing the current that flows in general-purpose electronic devices or home appliances, and damage to the articles due to heat can be prevented. In particular, by applying a current that can be applied to small electronic devices and household electrical appliances, these items can be easily disassembled. 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.

[0096] 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.

[0097] When the heating element is either infrared heating or microwave heating, the separation step is preferably a step of separating the two adherends by melting or softening the melt-softened layer by either infrared heating using an infrared heating means or microwave heating using a microwave heating means. There are no particular restrictions on the infrared heating means or microwave heating means, and known infrared heating devices and microwave heating devices can be selected as appropriate.

[0098] 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.

[0099] The dismantling temperature of the article is preferably within the range of 80°C to 160°C, more preferably within the range of 90°C to 150°C, and even more preferably within the range of 100°C to 130°C. By setting the disassembly temperature within the above range, thermal damage to the article and adherend can be suppressed, and disassembly can be easily achieved. In particular, when the pressure-sensitive adhesive tape is heated by resistance heating (electrical heating), by generating heat directly inside the tape, disassembly can be achieved 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.

[0100] Although an embodiment of the pressure-sensitive adhesive tape, the article, and the method for dismantling an article according to 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 components in addition to the components of the above-described embodiments, or may be substituted with any other components that produce the same effect. [Example]

[0101] 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.

[0102] Heating element Nichrome foil: "Nichrome NCH1-H" [product name, manufactured by Takeuchi Metal Foil & Powder Co., Ltd., thickness 10 μm, volume resistivity 108 μΩ·cm (catalog value), 105 μΩ·cm (measured value)] <Melting and softening layer> <Thermoplastic resin constituting the melt-softening layer> The following styrene-based thermoplastic elastomers (all manufactured by Zeon Corporation, MFR measurement conditions: 190°C, 21.6 kg load) were used. Thermoplastic resin 1: "Quintac (registered trademark) 3270", 24% by mass of structural units derived from styrene, MFR 20 g / 10 min Thermoplastic resin 2: "Quintac (registered trademark) 3280", 25% by mass of structural units derived from styrene, MFR 12 g / 10 min Thermoplastic resin 3: "Quintac (registered trademark) 3520", 15% by mass of structural units derived from styrene, MFR 6.5 g / 10 min

[0103] <Tackifying resin constituting the melt-softening layer> The following commercially available products were used. The mass loss rate (hereinafter simply referred to as "mass loss rate") of each commercially available product when heated from 25°C to 200°C at a temperature increase rate of 10°C / min under nitrogen was determined based on measurements taken using a thermogravimetric differential thermal analyzer "TG-DTA7200" (manufactured by Hitachi High-Tech Science Corporation). Tackifying resin 1: "Quinton (registered trademark) G115", C5-based / C9-based petroleum resin, manufactured by Zeon Corporation, mass reduction rate 0.6%, softening point 115°C Tackifying resin 2: "Quinton (registered trademark) M100", aliphatic hydrocarbon resin, manufactured by Zeon Corporation, mass loss rate 0.9%, softening point 95.0°C Tackifying resin 3: "Pensel D-160", polymerized rosin ester resin, manufactured by Arakawa Chemical Industries, Ltd., mass loss rate 1.6%, softening point 150-165°C Tackifying resin 4: "Pensel D-125", rosin ester type, manufactured by Arakawa Chemical Co., Ltd., mass reduction rate 0.4%, softening point 15~150℃ Tackifying resin 5: "Nippon Oil Polybutene HV-50", polybutene (number average molecular weight 800), manufactured by ENEOS Corporation, mass reduction rate 3.4%, pour point -12.5°C <Anti-aging agent> Anti-aging agent: "Irganox (registered trademark) 1010", manufactured by BASF Japan Ltd.

[0104] Functional Layer Heat insulating layer: Polyethylene foam layer (thickness 100 μm, porosity 60%) <<Peeling layer>> Release liner: 75 μm thick polyethylene terephthalate film with release treatment on one side

[0105] <Preparation Example of Melt-Softening Layer (Melt-Softening Resin Composition)> [Preparation Example 1-1] 100 parts by mass of thermoplastic resin 1, 36.3 parts by mass of tackifier resin 1, 28.6 parts by mass of tackifier resin 3, and 0.9 parts by mass of an antioxidant were mixed and dissolved in 150 parts by mass of n-propyl acetate as a solvent to obtain a resin composition (1-1). The obtained resin composition (1-1) was applied to the release-treated surface of a release liner so that the thickness after drying would be approximately 2 mm to prepare a layer (1-1). Using a viscoelasticity tester (ARES-G2, manufactured by TA Instruments Japan), the storage modulus G' and loss modulus (G") were measured 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 the resin composition (1-1) at a frequency of 1 Hz was calculated using the formula [tan δ=G" / G']. The melting point of the layer (1-1) is 140°C, and the storage modulus at 23°C is 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 storage modulus G at 150 °C 150 is 2.0 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).

[0106] [Preparation Example 1-2] A resin composition (1-2) was obtained in the same manner as in Preparation Example 1-1, except that 100 parts by mass of thermoplastic resin 2 was used instead of thermoplastic resin 1 in Preparation Example 1-1. A layer (1-2) was produced from the obtained resin composition (1-2) in the same manner as in Preparation Example 1-1. The storage modulus G of the layer (1-2) at 23°C 23 is 6.0 x 10 5 Pa, and the storage modulus G at 120 °C 120 is 8.0 x 10 4 Pa, and the storage modulus G at 150 °C 150 is 7.7 x 10 4 Pa, and the temperature when tan δ was 0.8 was 115°C.

[0107] [Preparation Example 1-3] 100 parts by mass of thermoplastic resin 2, 36.3 parts by mass of tackifier resin 2, 28.6 parts by mass of tackifier resin 4, and 0.9 parts by mass of an antioxidant were mixed and dissolved in 150 parts by mass of n-propyl acetate as a solvent to obtain a resin composition (1-3). A layer (1-3) was produced from the obtained resin composition (1-3) in the same manner as in Preparation Example 1-1. The storage modulus G of the layer (1-3) at 23°C 23 is 8.5 x 10 4 Pa, and the storage modulus G at 120 °C 120 is 4.0 x 10 4 Pa, and the storage modulus G at 150 °C 150 is 2.0 x 10 4 Pa, and the temperature when tan δ was 0.8 was 80°C.

[0108] [Preparation Example 1-4] A resin composition (1-4) was obtained by mixing 100 parts by mass of thermoplastic resin 3, 36.3 parts by mass of tackifier resin 1, 28.6 parts by mass of tackifier resin 3, 50.8 parts by mass of tackifier resin 5, and 0.9 parts by mass of an antioxidant, and dissolving the mixture in 181.5 parts by mass of toluene as a solvent. A layer (1-4) was produced from the obtained resin composition (1-4) in the same manner as in Preparation Example 1-1. The storage modulus G of the layer (1-4) at 23°C 23 is 2.5 x 10 5 Pa, and the storage modulus G at 120 °C 120 is 5.5 x 10 4 Pa, and the storage modulus G at 150 °C 150 is 1.5 x 10 4 Pa, and the temperature when tan δ was 0.8 was 125°C.

[0109] [Preparation Example 1-5] A resin composition (1-5) was obtained in the same manner as in Preparation Example 1-4, except that tackifier resin 5 was not added. A layer (1-5) was produced from the obtained resin composition (1-5) in the same manner as in Preparation Example 1-1. The storage modulus G of the layer (1-5) at 23°C 23 is 2.0 x 10 5 Pa, and the storage modulus G at 120 °C 120 is 6.7 x 10 4 Pa, and the storage modulus G at 150 °C 150 is 1.5 x 10 4 Pa, and the temperature when tan δ was 0.8 was 120°C.

[0110] [Preparation Example 1-6] A resin composition (1-6) was obtained in the same manner as in Preparation Example 1-4, except that tackifier resin 3 and tackifier resin 5 were not added. A layer (1-6) was produced from the obtained resin composition (1-6) in the same manner as in Preparation Example 1-1. The storage modulus G of the layer (1-6) at 23°C 23 is 1.7 x 10 5 Pa, and the storage modulus G at 120 °C 120 is 8.2 x 10 4 Pa, and the storage modulus G at 150 °C 150 is 3.0 x 10 4 Pa, and the temperature when tan δ was 0.8 was 127°C.

[0111] [Preparation Example 1-7] A resin composition (1-7) was obtained by mixing 100 parts by mass of thermoplastic resin 3, 36.3 parts by mass of tackifier resin 2, 28.6 parts by mass of tackifier resin 4, and 0.9 parts by mass of an antioxidant, and dissolving the mixture in 181.5 parts by mass of toluene as a solvent. A layer (1-7) was produced from the obtained resin composition (1-7) in the same manner as in Preparation Example 1-1. The storage modulus G of the layer (1-7) at 23°C 23 is 1.9 x 10 5 Pa, and the storage modulus G at 120 °C 120 is 6.0 x 10 4 Pa, and the storage modulus G at 150 °C 150 is 1.8 x 10 4 Pa, and the temperature when tan δ was 0.8 was 120°C.

[0112] <Preparation example of 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 ("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 a layer (2). Using a viscoelasticity tester (ARES-G2, manufactured by TA Instruments Japan), the storage modulus G' and loss modulus (G") were measured 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']. The melting point of the composition (2) is 150°C or higher, and the storage modulus at 23°C is G 23 is 7.5 x 10 4 Pa, and the storage modulus G at 120 °C 120 is 5.5 x 10 4 Pa, 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.

[0113] 1. Examples of adhesive tape and product manufacturing [Example 1] <Preparation of adhesive tape> (i) Composition (2) was applied to the release-treated surface of a release liner so that the thickness after drying would be 50 μm, and dried at 90° C. for 3 minutes to obtain an adhesive layer a1. On the other hand, resin composition (1-1) was applied to the release-treated surface of another release liner so that the thickness after drying would be 80 μm, and dried at 90° C. for 3 minutes to obtain a melt-softening layer c1. The adhesive layer a1 was attached to one side of the heat insulating layer (functional layer), and the melt-softening layer c1 was attached to the other side of the heat insulating layer, and the two layers were laminated on top of the release liner with a roll at a linear pressure of 5 kg / cm. This was aged for 48 hours in an environment of 40 ° C, resulting in a laminate L1 with a total thickness of 230 μm excluding the release liner and a layer structure excluding the release liner of melt-softening layer c1 / heat insulating layer / adhesive layer a1 in that order. (ii) Next, composition (2) was applied to the release-treated surface of the other release liner so that the thickness after drying was 50 μm, and the mixture was dried at 90 ° C for 3 minutes to obtain an adhesive layer a2. The laminate L1 was cut to a length of 50 mm and an arbitrary width, and a 100 mm long piece of nichrome foil was attached to the melt-softened layer c1 of the laminate L1 with a hand roller, and the nichrome foil was positioned so that it extended 25 mm from both ends in the longitudinal direction. Similarly, an adhesive layer a2 cut to an arbitrary width and 50 mm in length was attached to the opposite side of the nichrome foil to which the melt-softened layer c1 was attached, so that both ends of the nichrome foil extended 25 mm from the outer periphery of the melt-softened layer c1 and adhesive layer a2 in the longitudinal direction of the nichrome foil. The upper surface of the release liner was laminated with a roll at a linear pressure of 5 kg / cm, and the laminate was aged for 48 hours in an environment of 40° C. As a result, a laminate L2 was produced, which had a total thickness excluding the release liner of 290 μm and a layer structure excluding the release liner of adhesive layer a2 / nichrome foil b / melt-softening layer c1 / heat insulating layer / adhesive layer a1 in this order. The obtained laminate L2 was cut to a width of 2 mm, and an adhesive tape (T-1) was obtained in which the laminate L1 and adhesive layer a2 were 2 mm wide x 50 mm long, the nichrome foil was 2 mm long x 100 mm long, and the nichrome foil had a pair of extensions extending from the outer periphery of the melt-softened layer c1 and adhesive layer a2. A schematic plan view of the adhesive tape (T-1) is shown in Figure 9, and a schematic cross-sectional view is shown in Figure 10.

[0114] <Production of items> The release liner on the adhesive layer a1 side of the adhesive tape (T-1) of Example 1 (indicated by the symbol 10 in Figures 11 to 13) was peeled off, and the tape was applied to an adherend 50a (glass, width 40 mm × length 50 mm × thickness 10 mm) so that the 50 mm length of the adhesive surface (effective portion) of the tape crossed the center of the adherend 50a along the width direction of the adherend 50a (see Figures 11 to 13). Next, the release liner on the adhesive layer a2 side was peeled off, and the adhesive tape (T-1) was sandwiched between the adherend 50b (glass, width 30 mm × length 100 mm × thickness 2.8 mm) (see Figures 11 to 13), and applied with a pressure of 20 N / cm 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.

[0115] [Examples 2 to 3] Pressure-sensitive adhesive tapes (T-2) to (T-3) and articles of Examples 2 to 3 were obtained in the same manner as in Example 1, except that resin composition (1-2) or resin composition (1-3) was used instead of resin composition (1-1) in Example 1. [Comparative Examples 1 to 4] Pressure-sensitive adhesive tapes (T-4) to (T-7) and articles of comparative examples 1 to 4 were obtained in the same manner as in Example 1, except that resin compositions (1-4) to (1-7) were used instead of resin composition (1-1) in Example 1.

[0116] 2. Evaluation The push strength of the articles obtained in each of the Examples and Comparative Examples was measured using the apparatus shown in Figures 11 to 13 as follows: (1) Push strength before heating The articles obtained in each of the examples and comparative examples were used as test pieces, 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 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. [Evaluation criteria for initial adhesion] 〇: Push strength (G1) is 45N / 0.8cm 2 End ▲: Push strength (G1) is 40N / 0.8cm 2 More than m, 45N / 0.8cm 2 less than ×: Push strength (G1) is 40N / 0.8cm 2 less than

[0117] (2) Push strength after 10 seconds of heating The articles obtained in each of the Examples and Comparative Examples were used as test specimens, and the extended portion e of the nichrome foil (heating element) in the adhesive tape 10 of each test specimen was clamped with an alligator clip 60, and a current of 0.5 A, 1.0 A, or 1.5 A was passed through the test specimens using a DC stabilized power supply (manufactured by Kikusui Electronics Co., Ltd., product name "PAS160-1"). 10 seconds after the start of current application, the glass plate was pressed in the direction of the arrow with a probe 70 shown in Figures 12 and 13 at a speed of 10 mm / min while continuing to pass the current, and the strength at which the adhesive tape peeled off [push strength (G2)] was measured. The temperature achieved by the heating element when heated to 0.5A for dismantling (the temperature at which the item was dismantled) was approximately 100°C, the temperature achieved by the heating element when heated to 1.0A for dismantling (the temperature at which the item was dismantled) was approximately 160°C, and the temperature achieved by the heating element when heated to 1.5A for dismantling (the temperature at which the item was dismantled) was approximately 200°C. The temperature of the heating element after the current was applied was measured by a temperature sensor using a thermocouple.

[0118] (3) Residual adhesive strength and push strength reduction rate Using the push strength (G1) and the push strength (G2), the residual adhesive strength and the push strength reduction rate were calculated using the following formula, and the dismantling properties were evaluated according to the following criteria. Residual adhesive strength (%)=100×G2 / G1 Push strength reduction rate (%) = 100 x [1-(G2 / G1)] [Evaluation criteria for dismantling] ○: Residual adhesive strength is less than 50% △: Residual adhesive strength is 50% or more

[0119] (4) Presence or absence of volatile components The presence or absence of smoke or odor when dismantling each of the obtained articles by electrical heating was confirmed, and the results were judged as follows. ○: No smoke or odor ×: At least one of smoke and odor was generated

[0120] The above results are summarized in Table 1. Regarding the push strength after 10 seconds of heating with a 1.5 A current, in the articles of Examples 1 to 3 and Comparative Examples 1 and 4, the adhesive tape peeled off under its own weight within 10 seconds of the start of heating with a 1.5 A current, and the push strength could not be measured using the above method. Therefore, it was determined that the push strengths of the articles of Examples 1 to 3 and Comparative Examples 1 and 4 after 10 seconds of heating with a current of 1.5 A were smaller than the value of Comparative Example 2, which had the lowest push strength.

[0121] [Table 1] [Industrial Applicability]

[0122] 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]

[0123] a, a1, a2: Adhesive layer b: Heating element c: Melt-softened layer d: Heat insulating 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 having at least an adhesive layer, a heating element, and a melt-softening layer adjacent to the heating element, in this order. The melt-softening layer contains a thermoplastic resin having a weight average molecular weight of 80,000 to 150,000 and a tackifier resin having a mass reduction rate of 3% or less when raised from 25°C to 200°C under a nitrogen atmosphere at a temperature increase rate of 10°C / min.

2. The adhesive tape according to Claim 1, wherein the thermoplastic resin constituting the melt-softening layer contains a block copolymer composed 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.

3. The storage elastic modulus of the molten softening layer at 150°C is 1.0×10 ３ to 1.0×10 ５ Pa, and the adhesive tape according to claim 1.

4. The adhesive tape according to Claim 1, wherein the melt flow rate (MFR: 190°C, 21.6 kg load) of the thermoplastic resin constituting the melt-softening layer is 9 g / 10 min or more.

5. The adhesive tape according to Claim 1, wherein the content of the thermoplastic resin constituting the melt-softening layer is in the range of 30 to 80% by mass with respect to the entire composition constituting the melt-softening layer.

6. The adhesive tape according to Claim 1, wherein the content of the tackifier resin constituting the melt-softening layer is in the range of 20 to 100 parts by mass with respect to 100 parts by mass of the thermoplastic resin constituting the melt-softening layer.

7. The adhesive tape according to Claim 1, wherein when the adhesive tape is heated at 150°C for 30 seconds in a nitrogen atmosphere, the mass reduction rate of the adhesive tape after heating with respect to the mass of the adhesive tape before heating is 0.5% or less.

8. The adhesive tape according to Claim 1, wherein the volume resistivity of the heating element at 20°C is 30 μΩ·cm or more.

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

10. The adhesive tape according to Claim 1, further having an adhesive layer on the other surface side with respect to the surface of the melt-softening layer adjacent to the heating element.

11. The adhesive tape according to Claim 1, wherein the melt-softening layer can be peeled off by heating.

12. The adhesive tape according to Claim 1, wherein the heating element is an energized body that generates heat by energization, and is peeled off by the heat generation of the energized body.

13. An article comprising at least two adherends and the adhesive tape according to any one of claims 1 to 12 between the two adherends, wherein the two adherends are adhered via the adhesive tape.

14. The article according to claim 13, wherein in a plan view, the heating element constituting the adhesive tape has a pair of extending portions extending from the outer periphery of the adherend.

15. A method for disassembling the article according to claim 13, the method comprising melting and / or softening the melt-softening layer by heating the heating element to separate the two adherends.

16. The method for disassembling the article according to claim 15, wherein the heating of the heating element is resistance heating, the heating element and a power source are electrically connected, the heating element is energized from the power source, and the melt-softening layer is melted and / or softened by resistance heating to separate the two adherends.

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