adhesive tape

Abstract

An object of the present invention is to provide a pressure-sensitive adhesive tape that has excellent drop impact resistance, and to provide a pressure-sensitive adhesive tape that not only has excellent drop impact resistance but can also be more easily and quickly removed from an adherend. [Solution] The adhesive tape of the present invention comprises an adhesive layer, the adhesive layer containing particles having an average particle size of 4 to 40 μm and a silicone resin surface, and an adhesive resin, the content of the particles being 3 to 50 parts by mass per 100 parts by mass of the adhesive resin. The adhesive tape of the present invention also comprises the adhesive layer on one or both sides of a base layer, the base layer having a thickness of 10 to 500 μm, a breaking strength of 10 to 90 MPa, and a breaking elongation of 400 to 1500%.

Description

[Technical Field]

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

[0002] Because adhesive tapes are easy to work with and have high adhesive reliability, they are widely used as joining means in various industrial fields, such as office automation equipment, IT / home appliances, and automobiles, for purposes such as fixing parts, temporarily fixing parts, and labeling to display product information (e.g., Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2001-89726 Summary of the Invention [Problem to be solved by the invention]

[0004] An article in which a pair of adherends are joined and fixed via a pressure-sensitive adhesive tape has a problem in that, if dropped during handling, the adherends peel off from the pressure-sensitive adhesive tape and disintegrate due to the impact of the drop, making it impossible to maintain strong fixation. Therefore, pressure-sensitive adhesive tapes used for fixing are required to have high drop impact resistance that makes them less likely to peel off or break due to the impact of the drop, in order to prevent articles using the pressure-sensitive adhesive tape from disintegrating when dropped.

[0005] Meanwhile, in recent years, from the perspective of environmental protection, there has been an increasing demand in various industrial fields, such as home appliances and automobiles, for the recycling and reuse of used products or products scheduled for disposal. When recycling or reusing various products, the product must be disassembled and each component removed. Removing each component requires the removal of adhesive tape used to secure the components or labels. Recently, a recycling and reuse method has been proposed in which the adhesive tape is removed and disassembled by grasping and stretching the end of the tape. However, in recent years, adhesive tape has been installed in various locations throughout the product, making the adhesive tape removal process cumbersome. Furthermore, in products with a large number of densely packed components, removing a single component from among the densely packed components requires pulling the adhesive tape at a high angle (e.g., 60° or more) relative to the surface to which it is attached. However, pulling at such a high angle places a strain on the adhesive tape, and the tape may tear, especially when attempting to stretch it quickly. Therefore, in the process of removing adhesive tape, there is a demand for easier and faster removal of the adhesive tape, thereby reducing the operating costs. For this reason, adhesive tapes for fixing applications are required to have high drop impact resistance as described above, as well as to be easily and quickly removable when dismantling an article.

[0006] Therefore, the present invention has been made in view of the above problems, and has a first object to provide a pressure-sensitive adhesive tape that has excellent drop impact resistance. A second object of the present invention is to provide a pressure-sensitive adhesive tape that not only has excellent drop impact resistance but also can be more easily and quickly removed from an adherend. [Means for solving the problem]

[0007] In order to achieve the first object, the present invention provides the following pressure-sensitive adhesive tape. [1] An adhesive tape having an adhesive layer, The adhesive layer contains particles having an average particle size of 4 to 40 μm and having a silicone resin surface, and an adhesive resin, and the content of the particles is 3 to 50 parts by mass per 100 parts by mass of the adhesive resin. [2] The pressure-sensitive adhesive tape according to [1] above, wherein when particle diameters of particles corresponding to cumulative percentages of 10% and 90% in a cumulative particle size distribution of the particles are D10 and D90, respectively, the ratio of the particle diameter D90 to the particle diameter D10 (D90 / D10) is 2.5 to 20. [3] The adhesive tape according to either [1] or [2] above, which has the adhesive layer on one or both sides of a base layer.

[0008] In order to achieve the second object, the present invention provides the following pressure-sensitive adhesive tape. [4] The pressure-sensitive adhesive tape according to the above [3], wherein the base layer has a thickness of 10 to 500 μm, a breaking strength of 10 to 90 MPa, and a breaking elongation of 400 to 1500%. [5] The pressure-sensitive adhesive tape according to the above [5], wherein the base layer has a rubber hardness of 20 to 90A. [Effects of the Invention]

[0009] The present invention can provide a pressure-sensitive adhesive tape having excellent drop impact resistance by having a predetermined pressure-sensitive adhesive layer. Furthermore, by providing the above-mentioned specified adhesive layer on one or both surfaces of a specified base material layer, the present invention can provide an adhesive tape that not only has excellent drop impact resistance but can also be more easily and quickly removed from an adherend. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a schematic explanatory diagram illustrating a method for evaluating drop impact resistance. [Figure 2] FIG. 1 is a schematic explanatory view of a method for attaching a pressure-sensitive adhesive tape 1 to an acrylic plate 2 when evaluating impact resistance in the examples. [Figure 3] FIG. 1 is a schematic explanatory view of a test piece prepared when evaluating impact resistance in the examples. [Figure 4] FIG. 2 is a schematic explanatory diagram illustrating a method for placing a test piece on a U-shaped measurement table when evaluating impact resistance in the examples. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, an embodiment of the present invention (hereinafter referred to as "the present embodiment") will be described in detail, but the present invention is not limited to the present embodiment.

[0012] In this specification, the "drop impact resistance" of an adhesive tape refers to the resistance of the adhesive tape to peeling off or breaking against the impact (surface impact) that occurs when an article using the adhesive tape is dropped. Furthermore, "impact resistance" refers to the resistance of the adhesive tape to peeling off or breaking against the impact (point impact) that occurs when an article using the adhesive tape in a stationary state is hit by another article, such as a falling object. Since the manner in which impact stress is applied to the adhesive tape differs, the terms "drop impact resistance" and "impact resistance" are used to distinguish between the two terms in this specification.

[0013] "Adhesive tape" The adhesive tape of the present embodiment has a first aspect comprising at least a specific adhesive layer, and a second aspect comprising the specific adhesive layer of the first aspect on one or both surfaces of a specific base layer.

[0014] A first aspect of the adhesive tape of the present embodiment comprises an adhesive layer, the adhesive layer containing particles having an average particle size of 4 to 40 μm and having a silicone resin surface, and an adhesive resin, and the content of the particles is 3 to 50 parts by mass per 100 parts by mass of the adhesive resin.

[0015] In the pressure-sensitive adhesive tape of the first embodiment, the pressure-sensitive adhesive layer contains a predetermined amount of silicone resin-surfaced particles having an average particle size within a predetermined range, relative to the pressure-sensitive adhesive resin. This allows the silicone resin-surfaced particles in the pressure-sensitive adhesive layer to suppress particle aggregation and to be well dispersed in the pressure-sensitive adhesive resin. When stress (drop impact force) is applied to the pressure-sensitive adhesive tape of this embodiment due to a drop impact, the pressure-sensitive adhesive layer forms a cavity at the interface between the pressure-sensitive adhesive resin and the silicone resin, and the cavity relieves the stress, allowing the pressure-sensitive adhesive tape to exhibit excellent drop impact resistance. As a result, even when an article having a pair of adherends bonded together via the pressure-sensitive adhesive tape of this embodiment is subjected to a drop impact, the adhesive tape relieves the stress, making it difficult for the adherends to peel from the adhesive tape, maintaining a strong bond between the adherends and preventing damage and disintegration due to the drop impact.

[0016] A second aspect of the pressure-sensitive adhesive tape of this embodiment is a pressure-sensitive adhesive tape comprising a base layer and a pressure-sensitive adhesive layer on one or both sides of the base layer. The base layer of the pressure-sensitive adhesive tape of the second aspect has a thickness of 10 to 500 μm, a breaking strength of 10 to 90 MPa, and a breaking elongation of 400 to 1500%. Furthermore, the pressure-sensitive adhesive layer of the pressure-sensitive adhesive tape of the second aspect contains particles having an average particle size of 4 to 40 μm and a silicone resin surface, and a pressure-sensitive adhesive resin, with the content of the particles being 3 to 50 parts by mass per 100 parts by mass of the pressure-sensitive adhesive resin. In other words, the pressure-sensitive adhesive layer of the pressure-sensitive adhesive tape of the second aspect is the same as the pressure-sensitive adhesive layer of the pressure-sensitive adhesive tape of the first aspect. By virtue of having such a configuration, the pressure-sensitive adhesive tape of the second aspect not only has excellent drop impact resistance, but also can be more easily and quickly removed from an adherend (an object to which the pressure-sensitive adhesive tape is attached).

[0017] Specifically, the base layer of the pressure-sensitive adhesive tape of the second embodiment has a breaking strength of 10 to 90 MPa and a breaking elongation of 400 to 1500%, so that when the pressure-sensitive adhesive tape is peeled from the adherend, it can be peeled off (removed) without tearing even when pulled. Furthermore, the base layer of the pressure-sensitive adhesive tape of the second embodiment has a thickness of 10 to 500 μm, so that the strength of the pressure-sensitive adhesive tape and the ease of pulling the pressure-sensitive adhesive tape can be ensured. Furthermore, by satisfying the above-mentioned physical properties, the base layer can also absorb the impact of a drop, in addition to the drop impact absorbing effect of the pressure-sensitive adhesive layer, and thus the drop impact resistance of the pressure-sensitive adhesive tape is further improved. Furthermore, the adhesive layer of the pressure-sensitive adhesive tape of the second embodiment contains particles having an average particle size of 4 to 40 μm and a silicone resin surface, and an adhesive resin, with the content of the particles being 3 to 50 parts by mass per 100 parts by mass of the adhesive resin. Therefore, for the same reasons as the adhesive layer of the pressure-sensitive adhesive tape of the first embodiment described above, it not only has excellent drop impact resistance, but also, when combined with a substrate layer having the above characteristics, when the adhesive layer is pulled to peel the adhesive tape from the adherend, the silicone resin surface particles are exposed from the adhesive layer, which has become thinner as the adhesive tape stretches, and the particles present on the adhesive surface reduce frictional resistance, effectively reducing the adhesive strength of the adhesive layer to the adherend and facilitating peeling of the adhesive tape. Meanwhile, although the inclusion of a filler or the like in the pressure-sensitive adhesive composition may reduce adhesive performance due to the filler or the like, the particles have good dispersibility in the pressure-sensitive adhesive composition, preventing the addition of the particles from reducing adhesive performance and ensuring the adhesive strength of the pressure-sensitive adhesive tape. Therefore, the adhesive tape of the second aspect has excellent drop impact resistance, and further, when dismantling an article in which an adherend is attached to the adhesive tape, the adhesive tape can be more easily and quickly removed from the adherend.

[0018] <Base material layer> In the present embodiment, the pressure-sensitive adhesive tape of the first aspect may have a substrate layer or may not have a substrate layer, i.e., may be substrate-less. On the other hand, the pressure-sensitive adhesive tape of the second aspect has a substrate layer, and the substrate layer has a thickness of 10 to 500 μm, a breaking strength of 10 to 90 MPa, and a breaking elongation of 400 to 1500%.

[0019] (1) Base layer in the pressure-sensitive adhesive tape of the first embodiment Hereinafter, the base layer when the pressure-sensitive adhesive tape of the first embodiment has a base layer will be described. When the pressure-sensitive adhesive tape of the first embodiment has a base layer, the base layer is not particularly limited as long as it is a layer that can support the pressure-sensitive adhesive layer, and for example, a resin film, a rubber sheet, a foam sheet, a woven fabric, a nonwoven fabric, paper, metal foil, etc. can be used. The base layer may be a single layer, or may have a multilayer structure in which layers of the same or different materials are laminated. Furthermore, in the pressure-sensitive adhesive tape of the first embodiment, the base layer may be extensible or non-extensible.

[0020] Examples of resins that can be used to form resin films include styrene-based resins such as styrene-isoprene copolymer, styrene-isoprene-styrene copolymer, styrene-butadiene-styrene copolymer, styrene-ethylene-butylene copolymer, and styrene-ethylene-propylene copolymer; polyurethane resins such as ester-based polyurethane and ether-based polyurethane; polyolefin resins such as polyethylene and polypropylene; polyester resins such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate; polystyrene; polycarbonate; polymethylpentene; polysulfone; polyether ether ketone; polyethersulfone; polyetherimide; polyimide film; fluororesin; nylon; acrylic resin, soft vinyl chloride resin, elastic polyester resin, and soft polyolefin resin.

[0021] Examples of resins that can be used to form the foam sheet include polyolefin resins, polyester resins, polyvinyl chloride resins, polyphenylene sulfide resins, amide resins, polyimide resins, polyether ether ketone (PEEK), styrene resins, polyurethane resins, and rubber resins. Among these, at least one resin selected from the group consisting of polyolefin resins, polyurethane resins, acrylic resins, and rubber resins is preferred. Specifically, the foam sheet can be made of polyolefin foams made from polyolefin resins such as polyethylene, polypropylene, ethylene-propylene copolymers, and ethylene-vinyl acetate copolymers; polyurethane foams made from polyurethane resins; acrylic foams made from acrylic resins; and rubber foams made from rubber resins such as acrylic rubber and other elastomers. Among these, polyolefin foams are preferred because they are easily formed into a thin, closed-cell structure that provides excellent conformability to the surface irregularities of the adherend and excellent shock absorption.

[0022] Examples of the rubber sheet include a natural rubber sheet, a butyl rubber sheet, etc. Examples of the metal foil include an aluminum foil, a copper foil, etc.

[0023] Since the adhesive layer can further enhance drop impact resistance and also improve impact resistance, the substrate layer is preferably a resin film or foam sheet, and is preferably a resin film or foam sheet composed of a resin selected from styrene-based resins, polyurethane resins, polyolefin resins, and acrylic resins. Of these, a resin film or foam sheet composed of a styrene-based resin is more preferred, and a styrene-based resin film or styrene-based resin foam sheet containing a styrene-isoprene copolymer and a styrene-isoprene-styrene copolymer is preferred. The details of the styrene-based resin and polyurethane resin constituting the substrate layer can be the same as the details of the substrate material of the substrate layer in the pressure-sensitive adhesive tape of the second embodiment described below.

[0024] The substrate layer in the pressure-sensitive adhesive tape of the first embodiment may contain optional components such as additives such as a tackifying resin, a crosslinking agent, an antioxidant, an ultraviolet absorber, a filler, a polymerization inhibitor, a surface conditioner, an antistatic agent, an antifoaming agent, a viscosity modifier, a light stabilizer, a weathering stabilizer, a heat stabilizer, an antioxidant, a leveling agent, an organic pigment, an inorganic pigment, a pigment dispersant, silica beads, or organic beads; or inorganic fillers such as silicon oxide, aluminum oxide, titanium oxide, zirconia, or antimony pentoxide. These optional components may be used alone or in combination of two or more.

[0025] In the pressure-sensitive adhesive tape of the first embodiment, the thickness of the base layer is not particularly limited and can be appropriately set depending on the required properties, for example, 10 to 500 μm. The thickness of the base layer in the pressure-sensitive adhesive tape of the first embodiment is measured by the same method as the method for measuring the thickness of the base layer in the pressure-sensitive adhesive tape of the second embodiment described below.

[0026] The Shore A hardness of the base layer in the pressure-sensitive adhesive tape of the first aspect is not particularly limited, but is preferably in the range of 20A to 90A, more preferably in the range of 30A to 90A, and even more preferably in the range of 40A to 85A. By using a base layer having a Shore A hardness within the above range, it is possible to reduce the drop impact not only in the pressure-sensitive adhesive layer but also in the base layer. As a result, when an article to which an adherend has been fixed using the pressure-sensitive adhesive tape of the first aspect is dropped, the pressure-sensitive adhesive tape is more likely to absorb the impact, thereby protecting the adherend from the impact and improving the drop impact resistance of the pressure-sensitive adhesive tape.

[0027] The Shore A hardness of the base layer in the pressure-sensitive adhesive tape of the first embodiment can be measured by the same method as that for measuring the rubber hardness of the base layer in the pressure-sensitive adhesive tape of the second embodiment, which will be described later. The Shore A hardness can be adjusted by appropriately selecting materials, for example, by changing the type or molecular weight of the resin forming the base layer, or by changing the monomer unit of the resin.

[0028] The substrate layer may be subjected to a surface treatment such as corona treatment, chromic acid treatment, ozone exposure, flame exposure, high-voltage shock exposure, ionizing radiation treatment, coating treatment, etc. This is because the adhesive strength with the adhesive layer can be increased and peeling between the substrate layer and the adhesive layer can be suppressed when subjected to a drop impact.

[0029] In the pressure-sensitive adhesive tape of the first embodiment, the other physical properties of the base layer, such as breaking strength, breaking elongation, and 100% modulus, are not particularly limited and can be set appropriately depending on the required characteristics.

[0030] (2) Base layer in the pressure-sensitive adhesive tape of the second embodiment In the pressure-sensitive adhesive tape of the second embodiment, the base layer has a thickness of 10 to 500 μm, a breaking strength of 10 to 90 MPa, and a breaking elongation of 400 to 1500%.

[0031] In the pressure-sensitive adhesive tape of the second embodiment, the substrate layer is not particularly limited as long as it has the above-mentioned properties, and can be appropriately selected from known materials that can be used in pressure-sensitive adhesive tapes. It is preferable that the substrate layer contains the following substrate materials, and may further contain other components as necessary. The substrate layer may have a single layer structure, or a multi-layer structure of two, three or more layers.

[0032] In the pressure-sensitive adhesive tape of the second embodiment, the base layer has a breaking strength of 10 to 90 MPa, preferably 12 to 90 MPa, more preferably 30 to 90 MPa, and even more preferably 50 to 90 MPa. A breaking strength of 10 MPa or more allows the adhesive tape to be peeled from the adherend without tearing even when pulled by an operator. Furthermore, a breaking strength of 90 MPa or less prevents the operator from experiencing excessive stress when pulling the adhesive tape. In the adhesive tape of the second embodiment, the breaking strength of the base material layer refers to the stress value measured when the base material layer is punched out into a dumbbell shape with a gauge length of 20 mm and a width of 5 mm, and pulled in the longitudinal direction at a pulling rate of 500 mm / min using a Tensilon tensile tester (model: RTF-1210, manufactured by A&D Co., Ltd.) under measurement atmosphere conditions of 23°C and 50% RH, until breaking. The breaking strength can be adjusted by selecting an appropriate material and by applying stretching during the manufacturing process of the base layer.

[0033] In the pressure-sensitive adhesive tape of the second embodiment, the base layer has a breaking elongation of 400 to 1500%, preferably 500 to 1300%, more preferably 600 to 1200%, and even more preferably 800 to 1200%. A breaking elongation of 400% or more prevents excessive stress when peeling off the pressure-sensitive adhesive tape, even when the pressure-sensitive adhesive tape is firmly adhered to an adherend. Furthermore, a breaking elongation of 1500% or less prevents the adhesive tape from being stretched too far when peeling off, allowing for work in a small space. In the pressure-sensitive adhesive tape of the second embodiment, the breaking elongation of the base layer refers to the tensile elongation measured when the base layer is punched out into a dumbbell shape with a gauge length of 20 mm and a width of 5 mm, and pulled in the lengthwise direction at a pulling rate of 500 mm / min using a Tensilon tensile tester (model: RTF-1210, manufactured by A&D Co., Ltd.) under conditions of a measurement atmosphere of 23°C and 50% RH, and the tape breaks. The breaking elongation can be adjusted by appropriately selecting the material and by applying stretching during the manufacturing process of the base layer.

[0034] In the pressure-sensitive adhesive tape of the second aspect, the base layer preferably has a 100% modulus of 0.1 to 5 MPa, more preferably 0.5 to 4.5 MPa, and even more preferably 1 to 4 MPa. A 100% modulus of 0.1 MPa or more can suppress defects associated with shape deformation such as slippage when a load is applied to the pressure-sensitive adhesive tape or adherend. Furthermore, a 100% modulus of 5 MPa or less allows an operator to pull the pressure-sensitive adhesive tape from the adherend with a relatively light force in the initial stage of peeling it off. In the pressure-sensitive adhesive tape of the second embodiment, the 100% modulus of the base layer refers to the stress value measured when the base layer is punched out into a dumbbell shape with a gauge length of 20 mm and a width of 5 mm, and pulled in the longitudinal direction at a pulling rate of 500 mm / min using a Tensilon tensile tester (model: RTF-1210, manufactured by A&D Co., Ltd.) under measurement atmosphere conditions of 23°C and 50% RH, and the elongation reaches 100%. The 100% modulus can be adjusted by appropriately selecting the material and by applying stretching during the manufacturing process of the base layer.

[0035] In the pressure-sensitive adhesive tape of the second aspect, the base layer preferably has a rubber hardness in the range of 20A to 90A, more preferably in the range of 30A to 85A, even more preferably in the range of 40A to 80A, and even more preferably in the range of 40A to 75A. A rubber hardness of 20A or more can prevent the pressure-sensitive adhesive tape from tearing when stretched and peeled off. Furthermore, a rubber hardness of 90A or less makes the base layer soft, and the pressure-sensitive adhesive tape can more easily absorb impact, for example, when an adherend to which the pressure-sensitive adhesive tape is attached is dropped, or when another object is dropped onto an adherend to which the pressure-sensitive adhesive tape is attached, thereby protecting the adherend from impact (the drop impact resistance and impact resistance of the pressure-sensitive adhesive tape can be improved). The rubber hardness of the base layer is Shore A hardness, and refers to a value measured in accordance with JIS K 6253 using a durometer (spring type rubber hardness tester) (model: GS-719G, manufactured by Teclock Corporation). Furthermore, the rubber hardness can be adjusted by appropriately selecting the material, for example, by changing the molecular weight of the resin, or by changing the monomer unit if a styrene monomer unit is contained.

[0036] In the pressure-sensitive adhesive tape of the second embodiment, the base layer has a thickness of 10 to 500 μm, preferably 30 to 250 μm, and more preferably 50 to 200 μm. A thickness of 10 μm or more ensures the strength of the pressure-sensitive adhesive tape, while a thickness of 500 μm or less prevents the pressure-sensitive adhesive tape from becoming too thick and making it difficult to pull. In this specification, the "thickness of the base layer" refers to the average value of the thickness measured at any five points in the base layer using a TH-104 thickness measuring instrument for paper and film (manufactured by Tester Sangyo Co., Ltd.).

[0037] In the pressure-sensitive adhesive tape of the second embodiment, the thickness ratio of the adhesive layer to the base layer is not particularly limited and can be appropriately selected depending on the purpose. However, the ratio of the thickness of the adhesive layer to the thickness of the base layer, expressed as [thickness of adhesive layer / thickness of base layer], is preferably 1 / 5 to 5 / 1, more preferably 1 / 3 to 3 / 1, and even more preferably 1 / 2 to 2 / 1. When the thickness ratio of the adhesive layer to the base layer is within the preferred range, the pressure-sensitive adhesive tape can achieve excellent adhesion and removability (ease of peeling). On the other hand, if the ratio is greater than 5 / 1, there is a possibility that only the adhesive layer will remain on the adherend during the re-peeling process of the pressure-sensitive adhesive tape. Furthermore, if the ratio is less than 1 / 5, there is a concern that the adhesive layer will not be able to conform to the uneven surface of the adherend, resulting in a decrease in adhesive strength.

[0038] <<Materials for base material>> In the pressure-sensitive adhesive tape of the second embodiment, examples of the substrate material constituting the substrate layer include styrene-based resins such as styrene-isoprene copolymer, styrene-isoprene-styrene copolymer, styrene-butadiene-styrene copolymer, styrene-ethylene-butylene copolymer, and styrene-ethylene-propylene copolymer; polyurethane resins such as ester-based polyurethane and ether-based polyurethane; polyolefin resins such as polyethylene and polypropylene; polyester resins such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate; polystyrene; polycarbonate; polymethylpentene; polysulfone; polyether ether ketone; polyethersulfone; polyetherimide; polyimide film; fluorine resin; nylon; and acrylic resin. These may be used alone or in combination of two or more, but it is preferable to use two or more. Among these, styrene-based resins and polyurethane resins are preferred because they have excellent drop impact resistance and are easy to obtain suitable breaking strength and breaking elongation, and styrene-based resins are more preferred. Among these, it is particularly preferred to use a combination of a styrene-isoprene copolymer and a styrene-isoprene-styrene copolymer, because when combined with the specific adhesive layer described above, they exhibit high drop impact resistance and impact resistance, and can achieve high breaking elongation and breaking strength.

[0039] -Styrene-based resin- Since styrene resins are thermoplastic resins, they have excellent formability in extrusion molding, injection molding, etc., and are easy to form into a substrate layer. Furthermore, styrene resins are particularly likely to have excellent breaking elongation among the group of resins generally called thermoplastic resins, and further have excellent drop impact resistance, making them suitable for use as the substrate for the pressure-sensitive adhesive sheet of the second aspect.

[0040] Therefore, in the substrate material, the proportion of the styrene resin relative to the total resin components is preferably 50% to 100%, more preferably 60% to 100%, even more preferably 65% to 100%, and particularly preferably 70% to 100%. By keeping the proportion of the styrene resin within the above preferred range, a substrate layer with excellent breaking elongation and breaking strength can be obtained.

[0041] The styrene-based resin may have a single structure, such as a linear structure, a branched structure, or a multi-branched structure, or may be a mixture of different structures. A styrene-based resin rich in linear structures can provide the substrate layer with excellent elongation at break. On the other hand, a branched or multi-branched structure in which styrene blocks are arranged at the molecular end can form a pseudo-crosslinked structure and provide excellent cohesive strength. Therefore, it is preferable to use a mixture of styrene-based resins according to the required mechanical properties.

[0042] The styrene-based resin used preferably contains structural units represented by the following chemical formula (1) in a range of 13% to 60% by mass, more preferably 15% to 50% by mass, even more preferably 15% to 45% by mass, and particularly preferably 15% to 35% by mass, relative to the total mass of the styrene-based resin. When the proportion of structural units represented by the following chemical formula (1) relative to the total mass of the styrene-based resin is within the preferred range, it becomes easier to achieve suitable ranges of breaking elongation and breaking strength. In addition, * in the following chemical formula (1) represents a bond to another atom, and the same applies to chemical formulas (2) and (3) described below.

[0043] [ka]

[0044] When a styrene-isoprene copolymer and a styrene-isoprene-styrene copolymer are used in combination as the styrene-based resin, the content of the styrene-isoprene copolymer relative to the total mass of the styrene-isoprene copolymer and the styrene-isoprene-styrene copolymer is preferably 0% to 80% by mass, more preferably 0% to 70% by mass, even more preferably 0% to 50% by mass, and particularly preferably 0% to 30% by mass. When the content of the styrene-isoprene copolymer is within the above-mentioned preferred range, it is possible to achieve both excellent heat durability while maintaining excellent elongation at break and strength at break.

[0045] The styrene-isoprene copolymer preferably has a weight-average molecular weight, measured in terms of standard polystyrene using gel permeation chromatography (GPC), in the range of 10,000 to 800,000, more preferably in the range of 30,000 to 500,000, and even more preferably in the range of 50,000 to 300,000. When the weight-average molecular weight of the styrene-isoprene copolymer is within the above-mentioned preferred range, it is possible to ensure flowability during heating and compatibility when diluted with a solvent, which is preferable because it allows for a substrate layer to be obtained that has good workability in the production process and thermal durability.

[0046] Here, the weight average molecular weight of the styrene-isoprene copolymer measured by GPC is a value converted into standard polystyrene using a GPC apparatus (SC-8020, manufactured by Tosoh Corporation), and the measurement conditions are as follows. -Measurement conditions- Sample concentration: 0.5% by mass (tetrahydrofuran solution) Sample injection volume: 100 μL Eluent: tetrahydrofuran · Flow rate: 1.0mL / min · Measurement temperature: 40℃ Column: TSKgel® GMHHR-H(20) x 2 Guard column: TSKgel HXL-H Detector: Differential refractometer Standard polystyrene molecular weight: 10,000 to 20 million (Tosoh Corporation)

[0047] The method for producing the styrene-isoprene copolymer, the styrene-isoprene-styrene copolymer, and the mixture of the styrene-isoprene copolymer and the styrene-isoprene-styrene copolymer is not particularly limited and can be appropriately selected from conventionally known production methods. The block copolymer can be obtained by an anionic living polymerization method, and if necessary, a coupling agent is added and reacted. Specifically, the method for producing a styrene-isoprene copolymer is not particularly limited and can be appropriately selected from conventionally known production methods, such as a method in which a styrene block and an isoprene block are sequentially polymerized by an anionic living polymerization method.

[0048] The method for producing a styrene-isoprene-styrene copolymer is not particularly limited and can be appropriately selected from conventionally known production methods. Examples include a method in which a styrene block and an isoprene block are sequentially polymerized by an anionic living polymerization method, and a method in which a block copolymer having a living active end is produced and then reacted with a coupling agent to produce a coupled block copolymer.

[0049] The method for producing the mixture of styrene-isoprene copolymer and styrene-isoprene-styrene copolymer is not particularly limited and can be appropriately selected from conventionally known production methods. For example, a method of mixing the styrene-isoprene copolymer produced by the above-mentioned method with a styrene-isoprene-styrene copolymer can be mentioned.

[0050] As a method for producing a mixture of a styrene-isoprene copolymer and a styrene-isoprene-styrene copolymer, it is also possible to produce them as a mixture simultaneously in one polymerization step. In a more specific embodiment, the anionic living polymerization method involves first polymerizing styrene monomer in a polymerization solvent using an anionic polymerization initiator to form a polystyrene block having a living active end. Second, polymerizing isoprene from the living active end of the polystyrene block to obtain a styrene-isoprene diblock copolymer having a living active end. Third, reacting a portion of the styrene-isoprene diblock copolymer having a living active end with a coupling agent to form a coupled styrene-isoprene-styrene block copolymer. Fourth, using a polymerization terminator, deactivating the living active end of the remainder of the styrene-isoprene diblock copolymer having a living active end to form a styrene-isoprene diblock copolymer.

[0051] -Polyurethane resin- The polyurethane resin is not particularly limited and can be appropriately selected depending on the purpose, but preferably has a softening point of 40° C. or higher, more preferably 50° C. or higher. The upper limit of the softening point is preferably 100° C. or lower. The softening point refers to a value measured in accordance with JIS K 2207 (dry bulb method) (the same applies to softening points hereinafter).

[0052] As the polyurethane resin, a reaction product of a polyol (b1-1) and a polyisocyanate (b1-2) can be suitably used.

[0053] The polyol (b1-1) is not particularly limited and can be appropriately selected depending on the purpose. Examples include polyester polyols, polyether polyols, polycarbonate polyols, and acrylic polyols. These may be used alone or in combination of two or more. Among these, polyester polyols and polyether polyols are preferred as the polyol (b1-1) because they can provide the mechanical properties of the substrate layer. When heat resistance is required in the substrate layer, it is preferred to use polyester polyols, and when water resistance and biodegradability are required, it is preferred to use polyether polyols.

[0054] Examples of polyester polyols include polyesters obtained by an esterification reaction between a low-molecular-weight polyol and a polycarboxylic acid, polyesters obtained by a ring-opening polymerization reaction of a cyclic ester compound such as ε-caprolactone, and copolymer polyesters thereof.

[0055] Examples of low-molecular-weight polyols that can be used to produce polyester polyols include aliphatic alkylene glycols such as ethylene glycol, propylene glycol, 1,4-butanediol, 1,6-hexanediol, diethylene glycol, neopentyl glycol, and 1,3-butanediol, which have a weight-average molecular weight of approximately 50 to 300, and cyclohexanedimethanol.

[0056] Examples of polycarboxylic acids include aliphatic dicarboxylic acids such as succinic acid, adipic acid, sebacic acid, and dodecanedicarboxylic acid; aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, phthalic acid, and naphthalenedicarboxylic acid; and anhydrides or esters thereof.

[0057] Examples of polyether polyols include those obtained by addition polymerization of alkylene oxide using one or more compounds having two or more active hydrogen atoms as an initiator.

[0058] As the polycarbonate polyol, for example, a product obtained by reacting a carbonate ester and / or phosgene with a low-molecular-weight polyol described below can be used.

[0059] Examples of carbonate esters include methyl carbonate, dimethyl carbonate, ethyl carbonate, diethyl carbonate, cyclocarbonate, and diphenyl carbonate.

[0060] Examples of low molecular weight polyols that can be used to produce polycarbonate polyols and that can react with carbonate esters and / or phosgene include ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, 1,2-propanediol, 1,3-propanediol, dipropylene glycol, tripropylene glycol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 1,5-pentanediol, 1,5-hexanediol, 1,6-hexanediol, 2,5-hexanediol, 1 ,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,11-undecanediol, 1,12-dodecanediol, 2-methyl-1,3-propanediol, neopentyl glycol, 2-butyl-2-ethyl-1,3-propanediol, 3-methyl-1,5-pentanediol, 2-ethyl-1,3-hexanediol, 2-methyl-1,8-octanediol, 1,4-cyclohexanedimethanol, hydroquinone, resorcinol, bisphenol A, bisphenol F, 4,4'-biphenol, etc.

[0061] The polyisocyanate (b1-2) is not particularly limited and can be appropriately selected depending on the purpose, and examples thereof include alicyclic polyisocyanates, aliphatic polyisocyanates, aromatic polyisocyanates, etc., and examples thereof include alicyclic polyisocyanates, etc. These may be used alone or in combination of two or more.

[0062] Examples of alicyclic polyisocyanates include isophorone diisocyanate, 1,3-bis(isocyanatomethyl)cyclohexane, 4,4'-dicyclohexylmethane diisocyanate, 2,4-methylcyclohexane diisocyanate, 2,6-methylcyclohexane diisocyanate, cyclohexylene diisocyanate, methylcyclohexylene diisocyanate, bis(2-isocyanatoethyl)-4-cyclohexylene-1,2-dicarboxylate, 2,5-norbornane diisocyanate, 2,6-norbornane diisocyanate, dimer acid diisocyanate, bicycloheptane triisocyanate, etc. These may be used alone or in combination of two or more.

[0063] The method for producing the polyurethane resin (b1) by reacting the polyol (b1-1) with the polyisocyanate (b1-2) is not particularly limited and can be appropriately selected from conventionally known production methods. For example, there is a method in which the polyol (b1-1) placed in a reaction vessel is heated under normal pressure or reduced pressure to remove moisture, and then the polyisocyanate (b1-2) is supplied all at once or in portions and reacted.

[0064] The reaction of polyol (b1-1) with polyisocyanate (b1-2) is preferably carried out in such a manner that the equivalent ratio (NCO / OH equivalent ratio) of the isocyanate groups (NCO) in polyisocyanate (b1-2) to the hydroxyl groups (OH) in polyol (b1-1) is in the range of 1.0 to 20.0, more preferably 1.1 to 13.0, even more preferably 1.2 to 5.0, and particularly preferably 1.5 to 3.0.

[0065] The reaction conditions for the polyol (b1-1) and the polyisocyanate (b1-2) are not particularly limited and can be appropriately selected taking into consideration various conditions such as safety, quality, and cost. The reaction temperature is preferably 70°C to 120°C, and the reaction time is preferably 30 minutes to 5 hours.

[0066] When reacting the polyol (b1-1) with the polyisocyanate (b1-2), a catalyst such as a tertiary amine catalyst or an organometallic catalyst may be used as needed.

[0067] The reaction may be carried out in a solvent-free environment or in the presence of an organic solvent. The organic solvent is not particularly limited and can be appropriately selected depending on the purpose, and examples thereof include ester solvents such as methyl acetate, ethyl acetate, propyl acetate, and butyl acetate; ketone solvents such as acetone, methyl ethyl ketone, methyl butyl ketone, and cyclohexanone; ether ester solvents such as methyl cellosolve acetate and butyl cellosolve acetate; aromatic hydrocarbon solvents such as toluene and xylene; and amide solvents such as dimethylformamide and dimethylacetamide. These may be used alone or in combination of two or more. The organic solvent may be removed during the production of the polyurethane resin (b1) or after the production of the polyurethane (b1) by an appropriate method such as heating under reduced pressure or drying at normal pressure.

[0068] -Other ingredients- Other components in the substrate layer are not particularly limited and can be appropriately selected as long as they do not impair the properties of the pressure-sensitive adhesive tape, and examples thereof include tackifying resins; polymer components other than the substrate material; crosslinking agents, antioxidants, UV absorbers, fillers, polymerization inhibitors, surface conditioners, antistatic agents, antifoaming agents, viscosity modifiers, light stabilizers, weather stabilizers, heat stabilizers, antioxidants, leveling agents, organic pigments, inorganic pigments, pigment dispersants, silica beads, organic beads, and other additives; and inorganic fillers such as silicon oxide, aluminum oxide, titanium oxide, zirconia, and antimony pentoxide. These may be used alone or in combination of two or more. The content of other components in the base layer can be appropriately selected within a range that does not impair the properties of the adhesive tape.

[0069] The tackifier resin can be used for the purposes of increasing the adhesion between the adhesive layer of the adhesive tape and the base layer, and increasing the heat resistance.

[0070] The tackifying resin is not particularly limited and can be selected appropriately depending on the purpose, but it is preferable that the softening point is 80°C or higher, more preferably 90°C or higher, even more preferably 100°C or higher, and particularly preferably 110°C or higher.

[0071] As the tackifying resin, for example, those described in the section "--Rubber-based adhesive resin--" below can be used, and the same applies to preferred embodiments.

[0072] The antioxidant is not particularly limited and can be appropriately selected from known antioxidants depending on the purpose. Examples include phenolic antioxidants, phosphorus-based antioxidants (sometimes referred to as "processing stabilizers"), amine-based antioxidants, and imidazole-based antioxidants. These antioxidants may be used alone or in combination of two or more. Among these, phenolic antioxidants and phosphorus-based antioxidants are preferred. Using these in combination effectively improves the heat resistance stability of the substrate material, thereby maintaining good initial adhesion and providing an adhesive tape with even better heat durability. Note that phosphorus-based antioxidants may slightly discolor (yellowing) over time in high-temperature environments. Therefore, the amount used is preferably determined appropriately, taking into consideration the balance between initial adhesion, heat durability, and discoloration prevention.

[0073] As the phenolic antioxidant, a phenolic compound having a sterically hindered group can generally be used, and typical examples include monophenol, bisphenol, and polyphenol types. Specific examples include 2,6-di-t-butyl-4-methylphenol, 2,2'-methylenebis(4-methyl-6-t-butylphenol), 2,2'-methylenebis(4-ethyl-6-t-butylphenol), 4,4'-thiobis(6-t-butyl-3-methylphenol), 4,4'-butylidenebis(3-methyl-6-t-butylphenol), tetrakis-[methylene-3-(3'5'-di-t-butyl-4-hydroxyphenyl)propionate]methane, and n-octadecyl-3-(4'-hydroxy-3'5'-di-t-butylphenyl)propionate. These may be used alone or in combination of two or more.

[0074] The amount of the phenolic antioxidant used is not particularly limited and can be selected appropriately depending on the purpose, but it is preferably used in the range of 0.1 parts by mass to 5 parts by mass per 100 parts by mass of the substrate material, and using it in the range of 0.5 parts by mass to 3 parts by mass can effectively improve the heat resistance stability of the substrate material, and as a result, an adhesive tape can be obtained that maintains good initial adhesion and has even better heat durability.

[0075] <Adhesive layer> In this embodiment, the pressure-sensitive adhesive tape includes an adhesive layer for exhibiting drop impact resistance and adhesive strength. When the pressure-sensitive adhesive tape of this embodiment includes a base layer, the adhesive layer is provided on one or both sides of the base layer. In this embodiment, the pressure-sensitive adhesive layer in the pressure-sensitive adhesive sheet of the first aspect and the pressure-sensitive adhesive layer in the pressure-sensitive adhesive sheet of the second aspect each contain particles having an average particle size of 4 to 40 μm and having a silicone resin surface, and a pressure-sensitive adhesive resin, and the content of the particles is 3 to 50 parts by mass per 100 parts by mass of the pressure-sensitive adhesive resin. The adhesive composition forming the adhesive layer preferably contains the particles and an adhesive resin. The adhesive composition may further contain other components as needed in addition to the particles and the adhesive resin.

[0076] The adhesive layer in this embodiment contains particles whose surfaces are made of silicone resin, and by setting the average particle size of the particles and the amount of the particles relative to the adhesive resin within a predetermined range, the following effects can be achieved. First, since the silicone resin constituting the particle surfaces has low surface energy, by setting the average particle size of the particles within a predetermined range and further setting the amount of the particles relative to the adhesive resin within a predetermined range, aggregation of the particles can be easily suppressed, allowing the particles to be uniformly dispersed in the adhesive layer as primary particles. Furthermore, since the silicone resin constituting the particle surfaces has low surface energy, it has low adhesion to the adhesive resin. Therefore, when stress (drop impact force) is applied to the adhesive layer due to a drop impact, cavities are likely to form at the interface between the adhesive resin and the silicone resin, and the cavities perform a buffering function to relieve stress. Furthermore, since the average particle size of the particles whose surface is made of silicone resin is within a specified range, and the amount of silicone resin mixed with the adhesive resin is also within a specified range, when stress due to a drop impact is applied, cavities are formed around the particles, which are uniformly dispersed in the form of primary particles throughout the adhesive layer, making it possible to alleviate the stress due to the drop impact throughout the layer, and as a result, it is possible to exhibit excellent drop impact resistance properties.

[0077] Here, an adhesive layer containing particles with a silicone resin surface can form cavities between the particles with a silicone resin surface and the adhesive resin not only when an adherend to which the adhesive layer is attached is dropped and receives a surface impact, but also when an adherend to which the adhesive layer is attached is hit and receives a point impact when another object collides with the adherend. However, in the case of a point impact, it is presumed that the stress relief due to the adhesive layer's deformation following the distortion of the adherend upon impact is more influential than the stress relief due to the cavity. In contrast, in the case of a surface impact, the impact is received over the entire surface, making it difficult to achieve the effect of stress relief due to deformation following. Therefore, the present inventors have conducted extensive research and found that by adjusting the average particle size and content of the particles with a silicone resin surface contained in the adhesive layer, the function of the cavity in absorbing drop impact stress is enhanced, thereby improving drop impact resistance.

[0078] The stress of the adhesive layer at 25% elongation is not particularly limited and can be selected appropriately depending on the purpose, but is preferably 0.04 MPa to 0.4 MPa, and more preferably 0.05 MPa to 0.1 MPa. When the stress of the adhesive layer at 25% elongation is within the above-mentioned preferred range, the adhesive layer is less likely to undergo cohesive failure when subjected to an impact such as being dropped, thereby improving drop impact resistance. Furthermore, in the adhesive tape of the second aspect, when the stress of the adhesive layer at 25% elongation is within the above-mentioned range, peeling can be performed relatively easily even during stretch-peeling. On the other hand, if the stress of the adhesive layer at 25% elongation is less than 0.04 MPa, the adhesive layer will undergo cohesive failure when subjected to an impact such as a drop, making it difficult to achieve drop impact resistance, and the adhesive tape may peel off if a load is applied in the shear direction of the adhesive tape while fixing hard adherends together.On the other hand, if the stress exceeds 0.4 MPa, the amount of displacement of the adhesive layer will be small when subjected to an impact such as a drop, making it difficult to achieve drop impact resistance, and in the case of the adhesive tape of the second embodiment, the force required to stretch the adhesive tape when peeling it off may be excessive. The stress of the adhesive layer at 25% elongation refers to the stress value measured when the adhesive layer is punched out into a dumbbell shape with a gauge length of 20 mm and a width of 10 mm, and pulled in the longitudinal direction at a tensile speed of 300 mm / min using a Tensilon tensile testing machine (model: RTF-1210, manufactured by A&D Co., Ltd.) under measurement conditions of 23°C and 50% RH, until it is elongated by 25%.

[0079] The breaking strength of the adhesive layer is not particularly limited and can be appropriately selected depending on the purpose. However, it is preferably 0.5 MPa to 2.1 MPa, and more preferably 1.0 MPa to 2.1 MPa. When the breaking strength of the adhesive layer is within the above-mentioned preferred range, the adhesive layer is less likely to undergo cohesive failure upon impact, such as being dropped, and a suitable amount of displacement can be maintained, thereby improving drop impact resistance. Furthermore, in the adhesive tape of the second embodiment, tearing of the adhesive tape can be prevented even when the tape is stretched and peeled off, and the load required to stretch the adhesive tape is not excessive, making it easy to re-peel the tape by peeling it off. On the other hand, if the breaking strength of the adhesive layer is less than 0.5 MPa, the adhesive layer will undergo cohesive failure upon impact, such as being dropped, making it difficult to achieve drop impact resistance. Furthermore, in the adhesive tape of the second embodiment, adhesive residue may be left behind due to cohesive failure of the adhesive layer when the tape is stretched and peeled off. On the other hand, if the breaking strength exceeds 2.1 MPa, the adhesive layer will undergo small displacement upon impact, such as being dropped, making it difficult to achieve drop impact resistance and may not achieve sufficient adhesiveness. The force required to stretch and deform an adhesive tape also depends on the thickness of the adhesive tape. For example, even if an adhesive tape that is thick and has high breaking strength is stretched to peel off, it may not be possible to stretch it sufficiently and peel it off. The breaking strength of the adhesive layer refers to the stress value measured when the adhesive layer is punched out into a dumbbell shape with a gauge length of 20 mm and a width of 10 mm, and pulled in the longitudinal direction at a tensile speed of 300 mm / min using a Tensilon tensile testing machine (model: RTF-1210, manufactured by A&D Co., Ltd.) under conditions of 23°C and 50% RH until breaking.

[0080] The breaking elongation of the adhesive layer is not particularly limited and can be selected appropriately depending on the purpose, but is preferably 450% to 1,300%, more preferably 500% to 1,200%, and even more preferably 600% to 1,100%. Having a breaking elongation of the adhesive layer within this preferred range allows the adhesive layer to exhibit suitable adhesive strength while maintaining a suitable amount of displacement and being less susceptible to cohesive failure when subjected to impact, thereby improving drop impact resistance. Furthermore, the adhesive sheet of the second embodiment can achieve both suitable adhesiveness and removability (ease of peeling). The breaking elongation of the adhesive layer refers to the tensile elongation measured when the adhesive layer is punched out into a dumbbell shape with a gauge length of 20 mm and a width of 10 mm, and pulled in the lengthwise direction at a tensile speed of 300 mm / min using a Tensilon tensile testing machine (model: RTF-1210, manufactured by A&D Co., Ltd.) under conditions of a measurement atmosphere of 23°C and 50% RH, and when it breaks.

[0081] The thickness of the adhesive layer is not particularly limited as long as it is large enough to exhibit the desired adhesiveness and drop impact resistance, and can be appropriately selected depending on the purpose. When the adhesive tape of the present embodiment is a substrate-less tape that does not have a base layer, the thickness of the adhesive layer is preferably 5 μm to 500 μm, more preferably 20 μm to 400 μm, even more preferably 25 μm to 300 μm, and particularly preferably 50 μm to 150 μm. On the other hand, when the adhesive tape of the present embodiment has a base layer, the thickness of the adhesive layer is preferably 5 μm to 150 μm, more preferably 20 μm to 120 μm, even more preferably 40 μm to 110 μm, and particularly preferably 50 μm to 100 μm. When the adhesive tape has an adhesive layer on one or both sides of the base layer, the "thickness of the adhesive layer" means the thickness of the adhesive layer on one side of the adhesive tape. When the adhesive tape has an adhesive layer on both sides, the average thickness of the adhesive layer on one side may be the same as or different from the average thickness of the adhesive layer on the other side, but it is preferable that they are the same thickness. In this specification, the thickness of the adhesive layer can be measured by the following method. Specifically, an adhesive tape is immersed in liquid nitrogen for 1 minute, and then the adhesive tape is folded and split in the liquid nitrogen using tweezers along the width direction of the adhesive tape to prepare a section for observing the fractured surface in the thickness direction of the adhesive tape. The section is returned to room temperature in a desiccator, and then fixed to a sample stage so that an electron beam is incident perpendicularly to the fractured surface. The fractured surface is observed using an electron microscope. The thickness of the adhesive layer on the adhesive tape is measured at 10 points using the scale of the electron microscope, and the arithmetic average value is taken as the thickness of the adhesive layer. The thickness of the adhesive layer is the length measured from one surface to the other surface along the lamination direction.

[0082] The adhesive layer in this embodiment is formed from a pressure-sensitive adhesive composition containing at least particles having a predetermined average particle size and a silicone resin surface and an adhesive resin. The pressure-sensitive adhesive composition may further contain optional components in addition to the silicone resin surface particles and the adhesive resin, as needed. Each component contained in the pressure-sensitive adhesive composition constituting the adhesive layer will be described below.

[0083] -Particles with a silicone resin surface- In this embodiment, the pressure-sensitive adhesive composition, which is a precursor of the pressure-sensitive adhesive layer, contains particles having an average particle size of 4 to 40 μm and a silicone resin surface. By including these particles in the pressure-sensitive adhesive composition, which is a precursor of the pressure-sensitive adhesive layer, even when an article having an adherend fixed to the pressure-sensitive adhesive tape is dropped and subjected to a drop impact, the impact force is dispersed and mitigated by cavities formed between the particles dispersed throughout the pressure-sensitive adhesive layer and the pressure-sensitive adhesive resin, thereby preventing peeling or destruction of the pressure-sensitive adhesive layer. Furthermore, by including these particles in the pressure-sensitive adhesive composition forming the pressure-sensitive adhesive layer, when the pressure-sensitive adhesive tape of the second embodiment is stretched, the particles are exposed from the pressure-sensitive adhesive layer, reducing the adhesive area between the pressure-sensitive adhesive layer and the adherend, and the particles present on the adhesive surface reduce frictional resistance, thereby effectively reducing adhesive strength. Therefore, even when the stretching direction of the pressure-sensitive adhesive tape is at a relatively large angle, for example, perpendicular (sometimes referred to as the "90° direction") to the adherend surface, or even when the tape is stretched at a high speed, the pressure-sensitive adhesive tape can be peeled off more easily and quickly. Furthermore, when a filler or the like is contained in a pressure-sensitive adhesive composition, there is a risk that the addition of the filler will result in a decrease in adhesive performance, but particles whose surfaces are made of silicone resin have good dispersibility in the pressure-sensitive adhesive composition, so that the decrease in adhesive performance due to the addition of the particles is suppressed and the adhesive strength of the pressure-sensitive adhesive tape can be ensured. The reason for this good dispersibility is not clear, but it is presumed that particles whose surfaces are made of silicone resin have low surface energy, making it difficult for adhesion between particles to occur, and therefore preventing aggregation of secondary particles and the like.

[0084] In addition, since the particles having a silicone resin surface have good dispersibility in the pressure-sensitive adhesive composition, the particles are not unevenly distributed in the pressure-sensitive adhesive layer, but can be widely dispersed throughout the entire layer.As a result, compared to a pressure-sensitive adhesive layer containing a filler that does not have a silicone resin on its surface, such as silicone rubber particles, even when subjected to a drop impact, the particles having a silicone resin surface are dispersed throughout the pressure-sensitive adhesive layer, thereby dispersing and mitigating the drop impact force within the layer.In addition, when a drop impact force is applied, the particles having a silicone resin surface can form cavities at the interface between the particle surface and the pressure-sensitive adhesive resin, and the cavities improve the drop impact resistance.Furthermore, the cavities can suppress peeling and cohesive failure of the pressure-sensitive adhesive layer from the adherend.

[0085] The silicone resin surface particle may be any particle having a region formed of silicone resin on the particle surface. For example, the particle itself may be formed of silicone resin, or the particle may have silicone resin on part or all of its surface. For example, the particle having silicone resin on its entire surface may be a particle having a shell formed of silicone resin on its surface, with the interior of the shell being hollow. Furthermore, the silicone resin on part or all of its surface may have an internal material other than silicone resin (in other words, for example, a particle other than silicone resin, the surface of which is coated with silicone resin). However, the internal material is preferably a material having rubber elasticity, such as silicone rubber. That is, the silicone resin surface particle is preferably a particle having a core-shell structure in which the core is formed of a rubber material and the shell covering the core is formed of silicone resin. If the internal material of the particle is an elastic material, the adhesive performance of the adhesive layer can be more effectively ensured. Although the reason for this is unclear, it is presumed that when the particles are mixed with a solvent or the like to form a pressure-sensitive adhesive composition, the particles are able to absorb the solvent that has permeated the silicone resin surface and exhibit compatibility with the pressure-sensitive adhesive resin, compared to particles that are entirely made of silicone resin. The improved compatibility further suppresses a decrease in the adhesive performance of the pressure-sensitive adhesive layer. Examples of rubber materials that constitute the core include silicone, acrylic rubber, and diene rubber. Among these, silicone rubber, which has a low glass transition temperature and is easy to adjust, is preferred. A low glass transition temperature activates molecular micromotion, making it easier for the core to absorb external impact forces through thermal conversion, thereby further improving drop impact resistance. These particles may be used alone or in combination of two or more kinds. The particles can be produced by known production methods and are available as commercial products.

[0086] Specific examples of particles having a silicone rubber interior and a silicone resin on the surface include silicone rubber particles obtained by three-dimensionally crosslinking linear organopolysiloxane (see JP-A-63-77942, JP-A-3-93834, and JP-A-04-198324), and particles of powdered silicone rubber (see U.S. Pat. No. 3,843,601, JP-A-62-270660, and JP-A-59-96122), the surface of which is coated with (R'SiO 3 / 2 ) n Examples of such particles include those coated with a silicone resin, which is a cured product of polyorganosilsesquioxane having a three-dimensional network-like crosslinked structure represented by the formula (R' represents a substituted or unsubstituted monovalent hydrocarbon group) (see JP-A-7-196815). Examples of such silicone particles that can be used include Trefil E-500, Trefil E-600, Trefil E-601, and Trefil E-850, which are commercially available under the above-mentioned trade names from Dow Corning Toray Silicone Co., Ltd., and KMP-600, KMP-601, KMP-602, and KMP-605, which are commercially available from Shin-Etsu Chemical Co., Ltd.

[0087] As particles made of silicone resin, polyorganosilsesquioxane fine powder can be used.

[0088] The shape of the particles having a silicone resin surface is not particularly limited and can be appropriately selected depending on the purpose, and may be regular or irregular. Specific examples of particle shapes include polygonal, cubic, elliptical, spherical, needle-like, flat, and scale-like shapes. Among these, elliptical, spherical, and polygonal particle shapes are preferred, and spherical is more preferred. When the particle shape is elliptical, spherical, polygonal, or the like, the adhesive layer can slide smoothly against the adherend when the adhesive tape is stretched, allowing the adhesive tape to be peeled off more easily and quickly. Particles of these shapes may be used alone, or two or more types may be used in combination.

[0089] The particle size distribution (D90 / D10) of the particles having a silicone resin surface is not particularly limited and can be selected appropriately depending on the purpose, but is preferably 2.5 to 20, and from the viewpoints of drop impact resistance and impact resistance, is more preferably 2.5 to 15, and even more preferably 2.5 to 5. When the particle size distribution (D90 / D10) of the particles is within the preferred range, the pressure-sensitive adhesive tape has excellent drop impact resistance, and is also excellent in impact resistance, shear adhesive strength, and split adhesive strength. Furthermore, in particular, the pressure-sensitive adhesive tape of the second aspect can be peeled off more easily and quickly, is less likely to tear even when the pressure-sensitive adhesive tape base is thin, and is excellent in drop impact resistance, impact resistance, shear adhesive strength, and split adhesive strength. On the other hand, if the particle size distribution (D90 / D10) of the particles is less than 2.5, the stretch-peelability of the pressure-sensitive adhesive tape of the second embodiment may be impaired, while if it exceeds 20, the adhesive properties such as drop impact resistance, impact resistance, shear adhesive strength, and split adhesive strength may be impaired. The particle size distribution (D90 / D10) of particles can be obtained by measuring the average particle size of particles using, for example, a measuring instrument (Microtrac) that uses a laser diffraction scattering method, and converting the measured value into a particle size distribution.

[0090] The average particle size of the silicone resin-surfaced particles is 4 to 40 μm, preferably 5 to 40 μm, more preferably 10 to 35 μm, even more preferably 10 to 33 μm, and most preferably 10 to 25 μm. When the average particle size of the particles is within the preferred range, suitable drop impact resistance is easily achieved due to cavities formed at the interface between the adhesive resin and the silicone resin-surfaced particles upon application of a drop impact force. Furthermore, the pressure-sensitive adhesive tape of the second aspect can be peeled off more easily and quickly, is less likely to tear even when the base material of the pressure-sensitive adhesive tape is thin, and has excellent impact resistance, shear adhesive strength, and split adhesive strength. Note that if the average particle size of the particles is less than 2 μm, the cavities formed at the interface between the adhesive resin and the silicone resin-surfaced particles upon application of a drop impact force may be too small, making it difficult to achieve suitable drop impact resistance. Furthermore, the pressure-sensitive adhesive tape of the second aspect may suffer from impaired stretch releasability. On the other hand, if the average particle size of the particles exceeds 40 μm, coarse particles are likely to be present, which may result in the coarse particles being larger than the thickness of the adhesive layer, making it difficult to obtain a suitable adhesive strength. Also, adhesive properties such as drop impact resistance, impact resistance, shear adhesive strength, and split adhesive strength may be impaired. The average particle size of the particles refers to the volume average particle size, and can be measured, for example, by using a measuring device (Microtrac) that uses a laser diffraction scattering method.

[0091] The ratio of the average particle size of the silicone resin-surfaced particles to the average thickness of the adhesive layer is not particularly limited and can be selected appropriately depending on the purpose. However, the ratio of the average particle size of the particles to the average thickness of the adhesive layer, expressed as [volume-average particle size of particles / average thickness of adhesive layer], is preferably 5 / 100 or more, more preferably 5 / 100 to 95 / 100, even more preferably 10 / 100 to 75 / 100, and particularly preferably 20 / 100 to 60 / 100. When this ratio is 5 / 100 or more, cavities are likely to form at the interface between the adhesive resin and the silicone resin-surfaced particles upon application of a drop impact force, reducing the presence of coarse particles and improving drop impact resistance. Furthermore, the adhesive tape of the second embodiment can be more easily and quickly peeled off, and is less likely to tear even when the adhesive tape substrate is thin. Furthermore, if the ratio is 95 / 100 or less, it is advantageous in that adhesive properties such as drop impact resistance, impact resistance, shear adhesive strength, and split adhesive strength are also more excellent.

[0092] The content of the particles having a silicone resin surface in the adhesive layer is 3 to 50 parts by mass, preferably 5 to 40 parts by mass, and more preferably 7 to 35 parts by mass, per 100 parts by mass of the adhesive resin. When the content of the particles is 3 parts by mass or more per 100 parts by mass of the adhesive resin, the particles are dispersed within the adhesive layer. When the adhesive layer is subjected to a drop impact, cavities are more likely to form at the interface between the adhesive composition and the particles having a silicone resin surface, thereby preventing peeling from the adherend and damage to the adhesive layer. Furthermore, the adhesive tape of the second embodiment can be more easily and quickly peeled off. On the other hand, when the content of the particles is 50 parts by mass or less per 100 parts by mass of the adhesive resin, residue of the adhesive composition on the adherend can be prevented. Furthermore, a decrease in drop impact resistance and impact resistance, as well as a decrease in adhesive strength such as shear adhesive strength and split adhesive strength, can be prevented. The content of the particles in the adhesive layer can be appropriately adjusted when preparing the adhesive composition.

[0093] The volume ratio of the particles having a silicone resin surface to the total volume of the adhesive layer is preferably 5 to 50%, more preferably 10 to 50%, even more preferably 15 to 50%, and most preferably 20 to 50%. When the particle volume ratio is 5% or more, cavities are more likely to form at the interface between the adhesive resin and the silicone resin particles when subjected to a drop impact, thereby preventing peeling from the adherend and damage to the adhesive layer. Furthermore, the adhesive tape of the second aspect can be peeled more easily and quickly. On the other hand, when the particle volume ratio is 50% or less, residual adhesive composition on the adherend can be prevented. Furthermore, a decrease in drop impact resistance and impact resistance, as well as a decrease in adhesive strength such as shear adhesive strength and split adhesive strength, can be prevented. The volume ratio of the particles to the adhesive layer can be calculated using the following formulas (1) to (3). adhesive resin *1 Mass A (g) / Adhesive resin *1 Density A (g / cm 3 ) = Volume A (cm of adhesive resin * 1 3 )...Equation (1) Mass of particle B (g) / Density of particle B (g / cm 3 ) = particle volume B (cm 3 )...Equation (2) Particle volume B (cm 3 ) / (Adhesive resin *1 Volume A (cm 3 ) + particle volume B (cm 3 )) × 100 = particle volume ratio (%) Equation (3) In the above formulas (1) and (3), *1 The adhesive resin represented by the formula (I) may contain other components described below. The density is a value measured in accordance with JIS Z 8804.

[0094] -Adhesive resin- The adhesive resin is not particularly limited and can be appropriately selected from known adhesives, and examples thereof include acrylic adhesive resins, rubber adhesive resins, and urethane adhesive resins. These may be used alone or in combination of two or more. Among these, acrylic adhesive resins or rubber adhesive resins are preferred as the adhesive resin from the viewpoint of obtaining highly reliable adhesive strength.

[0095] --Acrylic adhesive resin-- The acrylic pressure-sensitive adhesive resin is not particularly limited and can be appropriately selected depending on the purpose. For example, it may contain an acrylic polymer as an essential component and, as necessary, additives such as a tackifier resin and a crosslinking agent.

[0096] Acrylic polymers can be produced, for example, by polymerizing (meth)acrylate monomers. As the (meth)acrylate monomer, for example, alkyl (meth)acrylate having an alkyl group having 1 to 12 carbon atoms can be used. Specific examples of alkyl (meth)acrylates having an alkyl group having 1 to 12 carbon atoms include methyl (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, t-butyl (meth)acrylate, n-hexyl (meth)acrylate, n-octyl (meth)acrylate, isooctyl (meth)acrylate, isononyl (meth)acrylate, cyclohexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, etc. These may be used alone or in combination of two or more.

[0097] As the alkyl(meth)acrylate having an alkyl group with 1 to 12 carbon atoms, it is preferable to use an alkyl(meth)acrylate having an alkyl group with 4 to 12 carbon atoms, it is more preferable to use an alkyl(meth)acrylate having an alkyl group with 4 to 8 carbon atoms, and it is particularly preferable to use n-butyl acrylate in order to ensure excellent adhesion to the adherend.

[0098] The alkyl (meth)acrylate having an alkyl group having 1 to 12 carbon atoms is preferably used in a range of 80 to 98.5 mass %, more preferably 90 to 98.5 mass %, based on the total amount of monomers used in producing the acrylic polymer.

[0099] In addition to the above-mentioned monomers, highly polar vinyl monomers can also be used as needed to prepare the acrylic polymer. Examples of highly polar vinyl monomers include (meth)acrylic monomers such as (meth)acrylic monomers having a hydroxyl group, (meth)acrylic monomers having a carboxyl group, and (meth)acrylic monomers having an amide group, as well as sulfonic acid group-containing monomers such as vinyl acetate, ethylene oxide-modified succinic acid acrylate, and 2-acrylamido-2-methylpropanesulfonic acid. These may be used alone or in combination of two or more.

[0100] Specific examples of vinyl monomers having a hydroxyl group include (meth)acrylic monomers such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, and 6-hydroxyhexyl (meth)acrylate.

[0101] It is preferable to use a vinyl monomer having a hydroxyl group when using a pressure-sensitive adhesive resin containing an isocyanate-based crosslinking agent. Specifically, it is preferable to use 2-hydroxyethyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, or 6-hydroxyhexyl (meth)acrylate as the vinyl monomer having a hydroxyl group.

[0102] The vinyl monomer having a hydroxyl group is preferably used in an amount of 0.01 to 1.0 mass %, more preferably 0.03 to 0.3 mass %, based on the total amount of monomers used in producing the acrylic polymer.

[0103] Specific examples of vinyl monomers having a carboxyl group include (meth)acrylic monomers such as acrylic acid, methacrylic acid, itaconic acid, maleic acid, (meth)acrylic acid dimer, crotonic acid, and ethylene oxide-modified succinic acid acrylate. Among these, acrylic acid is preferred.

[0104] Specific examples of vinyl monomers having an amide group include (meth)acrylic monomers such as N-vinylpyrrolidone, N-vinylcaprolactam, acryloylmorpholine, acrylamide, and N,N-dimethylacrylamide.

[0105] The highly polar vinyl monomer is preferably used in a range of 1.5% by mass to 20% by mass, more preferably 1.5% by mass to 10% by mass, and even more preferably 2% by mass to 8% by mass, relative to the total amount of monomers used in producing the acrylic polymer, since this allows for the formation of an adhesive layer that is well balanced in terms of cohesion, holding power, and adhesiveness.

[0106] The method for producing the acrylic polymer is not particularly limited and can be appropriately selected from known methods depending on the purpose, and examples thereof include methods in which a monomer is polymerized by a polymerization method such as a solution polymerization method, a bulk polymerization method, a suspension polymerization method, an emulsion polymerization method, etc. Among these, it is preferable to produce the acrylic polymer by a solution polymerization method or a bulk polymerization method.

[0107] During polymerization, if necessary, a peroxide-based thermal polymerization initiator such as benzoyl peroxide or lauroyl peroxide, an azo thermal polymerization initiator such as azobisisobutylnitrile, an acetophenone-based photopolymerization initiator, a benzoin ether-based photopolymerization initiator, a benzyl ketal-based photopolymerization initiator, an acylphosphine oxide-based photopolymerization initiator, a benzoin-based photopolymerization initiator, or a benzophenone-based photopolymerization initiator can be used.

[0108] The weight-average molecular weight of the acrylic polymer obtained by the above method is preferably 300,000 to 3,000,000, and more preferably 500,000 to 2,500,000, as measured using gel permeation chromatography (GPC) and converted into standard polystyrene.

[0109] Here, the weight average molecular weight of the acrylic polymer is measured by the GPC method using a GPC device (HLC-8329GPC, manufactured by Tosoh Corporation) and is a value converted into standard polystyrene. The measurement conditions are as follows. [Measurement conditions] Sample concentration: 0.5% by mass (tetrahydrofuran (THF) solution) Sample injection volume: 100 μL · Eluent: THF · Flow rate: 1.0mL / min · Measurement temperature: 40℃ Column: TSKgel GMHHR-H(20) x 2 Guard column: TSKgel HXL-H Detector: Differential refractometer Standard polystyrene molecular weight: 10,000 to 20 million (Tosoh Corporation)

[0110] As the acrylic pressure-sensitive adhesive resin, it is preferable to use one containing a tackifier resin in order to improve the adhesion to the adherend and the surface adhesive strength.

[0111] The tackifier resin contained in the acrylic adhesive resin is not particularly limited and can be selected appropriately depending on the purpose, but a softening point of 30° C. to 180° C. is preferred, and 70° C. to 140° C. is more preferred for forming an adhesive layer with high adhesive performance. When a (meth)acrylate tackifier resin is used, the glass transition temperature is preferably 30° C. to 200° C., and more preferably 50° C. to 160° C.

[0112] Specific examples of tackifier resins contained in acrylic pressure-sensitive adhesive resins include rosin-based tackifier resins, polymerized rosin-based tackifier resins, polymerized rosin ester-based tackifier resins, rosin phenol-based tackifier resins, stabilized rosin ester-based tackifier resins, disproportionated rosin ester-based tackifier resins, hydrogenated rosin ester-based tackifier resins, terpene-based tackifier resins, terpene phenol-based tackifier resins, petroleum resin-based tackifier resins, and (meth)acrylate-based tackifier resins. These may be used alone or in combination of two or more. Among these, preferred tackifier resins are polymerized rosin ester-based tackifier resins, rosin phenol-based tackifier resins, disproportionated rosin ester-based tackifier resins, hydrogenated rosin ester-based tackifier resins, terpene phenol-based resins, and (meth)acrylate-based resins.

[0113] The amount of tackifier resin used is not particularly limited and can be selected appropriately depending on the purpose, but it is preferable to use it in the range of 5 parts by mass to 65 parts by mass per 100 parts by mass of the acrylic polymer, and it is more preferable to use it in the range of 8 parts by mass to 55 parts by mass, as this makes it easier to ensure adhesion to the adherend.

[0114] It is preferable to use an acrylic adhesive resin containing a crosslinking agent in order to further improve the cohesive strength of the adhesive layer.

[0115] The crosslinking agent is not particularly limited and can be appropriately selected depending on the purpose. Examples include isocyanate-based crosslinking agents, epoxy-based crosslinking agents, metal chelate-based crosslinking agents, and aziridine-based crosslinking agents. These may be used alone or in combination of two or more. Among these, the crosslinking agent is preferably a type that is mixed with the acrylic polymer after production to promote a crosslinking reaction, and it is more preferable to use an isocyanate-based crosslinking agent or an epoxy-based crosslinking agent that is highly reactive with the acrylic polymer.

[0116] Examples of isocyanate crosslinking agents include tolylene diisocyanate, triphenylmethane isocyanate, naphthylene-1,5-diisocyanate, hexamethylene diisocyanate, diphenylmethane diisocyanate, xylylene diisocyanate, and trimethylolpropane-modified tolylene diisocyanate. These may be used alone or in combination of two or more. Among these, trifunctional polyisocyanate compounds such as tolylene diisocyanate and its trimethylolpropane adduct, and triphenylmethane isocyanate are particularly preferred.

[0117] As an index of the degree of crosslinking, the gel fraction value obtained by measuring the insoluble portion after immersing the adhesive layer in toluene for 24 hours is used. The gel fraction of the adhesive layer is not particularly limited and can be appropriately selected depending on the purpose, but is preferably 10% by mass to 70% by mass, more preferably 25% by mass to 65% by mass, and even more preferably 35% by mass to 60% by mass in order to obtain an adhesive layer with good cohesion and adhesiveness.

[0118] The gel fraction refers to a value measured by the following method. The adhesive composition was coated onto a release sheet so that the thickness after drying was 50 μm, dried at 100°C for 3 minutes, and aged at 40°C for 2 days. A 50 mm square piece was then cut out and used as a sample. Next, the mass (G1) of the sample before immersion in toluene was measured in advance. After immersion in toluene solution for 24 hours at 23°C, the toluene-insoluble portion of the sample was separated by filtration through a 300-mesh wire netting. After drying at 110°C for 1 hour, the mass (G2) of the residue was measured, and the gel fraction was calculated according to the following formula (4). The mass (G3) of particles in the sample whose surface is made of silicone resin was calculated from the mass (G1) of the sample and the composition of the adhesive composition. Gel fraction (mass%)=(G2-G3) / (G1-G3)×100...Equation (4)

[0119] --Rubber-based adhesive resin-- The rubber-based adhesive resin is not particularly limited, and examples thereof include rubber materials that can generally be used as adhesive resins, such as synthetic rubber-based adhesive resins and natural rubber-based adhesive resins, and those that contain additives such as tackifier resins as necessary.

[0120] Examples of rubber materials include block copolymers of aromatic vinyl compounds and conjugated diene compounds, specifically styrene-based resins such as styrene-isoprene copolymer, styrene-isoprene-styrene copolymer, styrene-isoprene-butadiene-styrene copolymer, styrene-butadiene-styrene copolymer, styrene-ethylene-butylene copolymer, styrene-ethylene-propylene copolymer, and hydrogenated versions thereof. These may be used alone or in combination of two or more. Among these, using two or more styrene-based resins in combination is more preferable because it can impart excellent adhesive properties and holding power to the pressure-sensitive adhesive tape, and using a combination of a styrene-isoprene copolymer and a styrene-isoprene-styrene copolymer is particularly preferable.

[0121] The styrene-based resin may have a single structure, such as a linear structure, a branched structure, or a multi-branched structure, or may be a mixture of different structures. When a styrene-based resin rich in linear structures is used in the adhesive layer, it can provide excellent adhesive performance to the adhesive tape. On the other hand, a branched or multi-branched structure in which styrene blocks are arranged at the molecular end can form a pseudo-crosslinked structure, which can provide excellent cohesive strength and therefore high holding power. For this reason, it is preferable to use a mixture of styrene-based resins according to the required properties.

[0122] The styrene resin preferably contains 10% to 80% by mass of the structural unit represented by the following chemical formula (2) relative to the total mass of the styrene resin, more preferably 12% to 60% by mass, even more preferably 15% to 40% by mass, and particularly preferably 17% to 35% by mass, thereby achieving excellent adhesion and heat resistance.

[0123] [ka]

[0124] When a styrene-isoprene copolymer and a styrene-isoprene-styrene copolymer are used in combination as the styrene-based resin, the content of the styrene-isoprene copolymer relative to the total mass of the styrene-isoprene copolymer and the styrene-isoprene-styrene copolymer is preferably 0% by mass to 80% by mass, more preferably 0% by mass to 77% by mass, even more preferably 0% by mass to 75% by mass, and particularly preferably 0% by mass to 70% by mass. When the content of the styrene-isoprene copolymer is within the above-mentioned preferred range, the pressure-sensitive adhesive tape can achieve both excellent adhesive performance and heat durability.

[0125] The styrene-isoprene copolymer preferably has a weight-average molecular weight, measured using gel permeation chromatography (GPC) in terms of standard polystyrene, in the range of 10,000 to 800,000, more preferably in the range of 30,000 to 500,000, and even more preferably in the range of 50,000 to 300,000. When the weight-average molecular weight of the styrene-isoprene copolymer is within the above-mentioned preferred range, it is possible to ensure flowability during heating and compatibility when diluted with a solvent, and therefore it is possible to obtain an adhesive tape that has good workability in the production process and is heat-resistant, which is preferable.

[0126] Here, the weight average molecular weight of the styrene-isoprene copolymer measured by GPC is a value converted into standard polystyrene using a GPC apparatus (SC-8020, manufactured by Tosoh Corporation), and the measurement conditions are as follows. -Measurement conditions- Sample concentration: 0.5% by mass (tetrahydrofuran solution) Sample injection volume: 100 μL Eluent: tetrahydrofuran · Flow rate: 1.0mL / min · Measurement temperature: 40℃ Column: TSKgel® GMHHR-H(20) x 2 Guard column: TSKgel HXL-H Detector: Differential refractometer Standard polystyrene molecular weight: 10,000 to 20 million (Tosoh Corporation)

[0127] The method for producing the styrene-based resin is not particularly limited and can be appropriately selected from conventionally known production methods. A block copolymer can be obtained by an anionic living polymerization method, and a coupling agent can be added as needed to react to obtain the styrene-based resin. Specifically, the method for producing a styrene-isoprene copolymer is not particularly limited and can be appropriately selected from conventionally known production methods, such as a method in which a styrene block and an isoprene block are sequentially polymerized by an anionic living polymerization method.

[0128] The method for producing a styrene-isoprene-styrene copolymer is not particularly limited and can be appropriately selected from conventionally known production methods. Examples include a method in which a styrene block and an isoprene block are sequentially polymerized by an anionic living polymerization method, and a method in which a block copolymer having a living active end is produced and then reacted with a coupling agent to produce a coupled block copolymer.

[0129] The method for producing the mixture of styrene-isoprene copolymer and styrene-isoprene-styrene copolymer is not particularly limited and can be appropriately selected from conventionally known production methods. For example, a method of mixing the styrene-isoprene copolymer produced by the above-mentioned method with a styrene-isoprene-styrene copolymer can be mentioned.

[0130] As a method for producing a mixture of a styrene-isoprene copolymer and a styrene-isoprene-styrene copolymer, it is also possible to produce them as a mixture simultaneously in one polymerization step. In a more specific embodiment, the anionic living polymerization method involves first polymerizing styrene monomer in a polymerization solvent using an anionic polymerization initiator to form a polystyrene block having a living active end. Second, polymerizing isoprene from the living active end of the polystyrene block to obtain a styrene-isoprene diblock copolymer having a living active end. Third, reacting a portion of the styrene-isoprene diblock copolymer having a living active end with a coupling agent to form a coupled styrene-isoprene-styrene block copolymer. Fourth, using a polymerization terminator, deactivating the living active end of the remainder of the styrene-isoprene diblock copolymer having a living active end to form a styrene-isoprene diblock copolymer.

[0131] The tackifier resin contained in the rubber-based pressure-sensitive adhesive resin is not particularly limited and can be selected appropriately depending on the purpose, but it is preferable to use a tackifier resin with a softening point of 80° C. or higher, which allows for the production of a pressure-sensitive adhesive tape with excellent initial adhesion and heat durability.

[0132] The tackifying resin is preferably solid at room temperature (23°C), and specific examples thereof include petroleum resins such as C5 petroleum resins, C9 petroleum resins, C5 / C9 petroleum resins, and alicyclic petroleum resins, as well as polymerized rosin resins, terpene resins, rosin resins, terpene-phenol resins, styrene resins, coumarone-indene resins, xylene resins, and phenolic resins. These may be used alone or in combination of two or more. Among these, it is preferable to use a combination of a C5 petroleum resin and a polymerized rosin resin as the tackifying resin, as this achieves both even better initial adhesion and thermal durability.

[0133] Petroleum resins are highly compatible with the structural unit represented by the chemical formula (1) constituting the styrene-based resin, and as a result, the initial adhesive strength and heat durability of the pressure-sensitive adhesive tape can be further improved.

[0134] Examples of C5 petroleum resins include Escoretz 1202, Escoretz 1304, and Escoretz 1401 (all manufactured by ExxonMobil Corporation), Wingtack 95 (manufactured by The Goodyear Tire & Rubber Company), Quinton K100, Quinton R100, and Quinton F100 (manufactured by Zeon Corporation), Picotack 95, and Picopal 100 (manufactured by Rika Hercules Corporation).

[0135] Examples of C9 petroleum resins include Nippon Oil Neopolymer L-90, Nippon Oil Neopolymer 120, Nippon Oil Neopolymer 130, Nippon Oil Neopolymer 140, Nippon Oil Neopolymer 150, Nippon Oil Neopolymer 170S, Nippon Oil Neopolymer 160, Nippon Oil Neopolymer E-100, Nippon Oil Neopolymer E-130, Nippon Oil Neopolymer 130S, and Nippon Oil Neopolymer S (all manufactured by JX Nippon Oil & Energy Corporation), and Petcol (registered trademark) (manufactured by Tosoh Corporation).

[0136] As the C5 / C9 petroleum resin, a copolymer of a C5 petroleum resin and a C9 petroleum resin can be used, and examples thereof include Escoretz 2101 (manufactured by Exxon Mobil Corporation), Quinton G115 (manufactured by Zeon Corporation), and Hercotack 1149 (manufactured by Rika Hercules Co., Ltd.).

[0137] Alicyclic petroleum resins can be obtained by hydrogenating C9 petroleum resins, and examples thereof include Escolez 5300 (manufactured by Exxon Mobil Corporation), Alcon P-100 (manufactured by Arakawa Chemical Industries, Ltd.), and Rigalite R101 (manufactured by Rika Hercules Co., Ltd.).

[0138] The amount of tackifier resin used is not particularly limited and can be selected appropriately depending on the purpose, but is preferably used in the range of 0% to 100% by mass, more preferably 0% to 70% by mass, even more preferably 0% to 50% by mass, and particularly preferably 0% to 30% by mass, relative to the total amount of components constituting the rubber-based pressure-sensitive adhesive resin. Using the tackifier resin within this preferred range makes it easier to achieve both excellent breaking elongation and thermal durability of the pressure-sensitive adhesive tape while improving the interfacial adhesion between the pressure-sensitive adhesive layer and the base layer. Furthermore, using the tackifier resin within this preferred range can improve adhesive strength while maintaining good drop impact resistance.

[0139] The amount of the tackifier resin having a softening point of 80°C or higher used is not particularly limited and can be selected appropriately depending on the purpose, but it is preferably used in a range of 3% by mass to 100% by mass, more preferably 5% by mass to 80% by mass, relative to the total amount of the styrene-based resin, and using it in a range of 5% by mass to 80% by mass is particularly preferred in order to obtain a pressure-sensitive adhesive tape that combines even better adhesion and excellent heat durability.

[0140] Furthermore, in order to obtain good application properties and initial adhesiveness in a constant temperature environment, a tackifier resin having a softening point of -5°C or lower can be used in combination with a tackifier resin having a softening point of 80°C or higher.

[0141] There are no particular restrictions on the tackifier resin having a softening point of -5°C or less, and it can be appropriately selected from known tackifier resins depending on the purpose, but it is preferable to use a tackifier resin that is liquid at room temperature.

[0142] Specific examples of tackifier resins having a softening point of -5°C or less include process oil, polyester, and liquid rubber such as polybutene. These may be used alone or in combination of two or more. Among these, it is preferable to use polybutene as the tackifier resin having a softening point of -5°C or less in order to achieve even better initial adhesiveness.

[0143] The tackifying resin having a softening point of −5° C. or less is preferably used in the range of 0 to 40% by mass, and more preferably 0 to 30% by mass, based on the total amount of the tackifying resin.

[0144] Furthermore, the tackifying resin having a softening point of -5°C or less is preferably used in a range of 0% by mass to 40% by mass relative to the total amount of the styrene-based resin, and more preferably in a range of 0% by mass to 30% by mass, since this improves the initial adhesive strength, allows for good adhesion, and also allows for sufficient heat durability.

[0145] The mass ratio of the tackifier resin having a softening point of 80°C or higher to the tackifier resin having a softening point of -5°C or lower is not particularly limited and can be selected appropriately depending on the purpose. However, it is preferable to use a tackifier resin having a softening point of 80°C or higher to a tackifier resin having a softening point of -5°C or lower in a mass ratio, expressed as [mass of tackifier resin having a softening point of 80°C or higher / mass of tackifier resin having a softening point of -5°C or lower], in a range of 5 to 50, and it is more preferable to use a tackifier resin having a softening point of 10 to 30 in order to obtain a pressure-sensitive adhesive tape that combines excellent initial adhesion and excellent holding power.

[0146] The mass ratio of the styrene resin to the tackifier resin is not particularly limited and can be selected appropriately depending on the purpose, but the mass ratio of the styrene resin to the tackifier resin, expressed as [styrene resin / tackifier resin], is preferably in the range of 0.5 to 10.0, and more preferably in the range of 0.6 to 9.0, because this improves the initial adhesive strength and provides excellent heat durability. Furthermore, a mass ratio [styrene resin / tackifier resin] of greater than 1 is preferred, for example, to prevent peeling due to the repulsive force of the adhesive tape when applied to a curved surface of an adherend (repulsion resistance).

[0147] --Urethane-based adhesive resin (urethane-based polymer)-- Urethane-based pressure-sensitive adhesive resins refer to pressure-sensitive adhesive resins containing a urethane-based polymer as a base polymer. The urethane-based pressure-sensitive adhesive resins are typically composed of urethane-based resins containing a urethane-based polymer as a base polymer obtained by reacting a polyol with a polyisocyanate compound, and may optionally contain additives such as tackifying resins. The urethane-based polymer is not particularly limited, and an appropriate one can be selected from various urethane-based polymers that can function as pressure-sensitive adhesives (e.g., ether-based polyurethanes, ester-based polyurethanes, carbonate-based polyurethanes, etc.). Examples of polyols include polyether polyols, polyester polyols, polycarbonate polyols, polycaprolactone polyols, etc. Examples of polyisocyanate compounds include diphenylmethane diisocyanate, tolylene diisocyanate, hexamethylene diisocyanate, etc. Examples of tackifying resins that can be contained in urethane-based pressure-sensitive adhesive resins include the tackifying resins exemplified above for the acrylic adhesive resins and styrene-based adhesive resins.

[0148] -Other ingredients- Other components in the adhesive layer are not particularly limited and can be appropriately selected as long as they do not impair the properties of the adhesive tape, and examples thereof include polymer components other than the adhesive resin, crosslinking agents, antioxidants, UV absorbers, fillers, polymerization inhibitors, surface conditioners, antistatic agents, antifoaming agents, viscosity modifiers, light stabilizers, weather stabilizers, heat stabilizers, antioxidants, leveling agents, organic pigments, inorganic pigments, pigment dispersants, plasticizers, softeners, flame retardants, metal deactivators, silica beads, organic beads, and other additives; and inorganic fillers such as silicon oxide, aluminum oxide, titanium oxide, zirconia, and antimony pentoxide. These may be used alone or in combination of two or more. The content of other components in the adhesive layer can be appropriately selected within a range that does not impair the properties of the adhesive tape.

[0149] The adhesive composition forming the adhesive layer may contain a crosslinking agent, if necessary, in addition to the adhesive resin described above. This is because the inclusion of a crosslinking agent can enhance the cohesive strength of the adhesive layer. The type of crosslinking agent is not particularly limited, and can be appropriately selected from conventionally known crosslinking agents. Examples of such crosslinking agents include isocyanate-based crosslinking agents, epoxy-based crosslinking agents, oxazoline-based crosslinking agents, aziridine-based crosslinking agents, melamine-based crosslinking agents, peroxide-based crosslinking agents, and metal chelate-based crosslinking agents. The crosslinking agents can be used alone or in combination of two or more. Among these, isocyanate-based crosslinking agents and epoxy-based crosslinking agents are preferred from the viewpoint of improving cohesive strength. Specific isocyanate-based crosslinking agents are as described above. The amount of crosslinking agent used is not particularly limited, and can be selected, for example, from a range of 10 parts by mass or less, for example, approximately 0.005 to 10 parts by mass, and preferably approximately 0.01 to 5 parts by mass, per 100 parts by mass of the adhesive resin.

[0150] The adhesive composition forming the adhesive layer may be foamable or may be in a foamed state. For this purpose, a foaming agent may be added to the adhesive composition during formulation. As the foaming agent, microballoons in expanded or expandable form may be used. A chemically foamable foaming agent may be used alone or in combination with other foaming agents. The adhesive composition may also be foamable or foamed physically, i.e., by adding a substance or substance mixture in a gaseous or supercritical liquid state. The foaming method described above is preferably carried out by adding microballoons and then expanding them.

[0151] "Microballoons" are hollow microbeads with an elastic, expandable thermoplastic polymer shell. These beads are filled with a low-boiling liquid or liquefied gas. Polyacrylonitrile, PVDC, PVC, or polyacrylates are particularly suitable as shell materials. Lower alkane hydrocarbons, such as isobutane or isopentane, are particularly suitable as low-boiling liquids, which are encapsulated in the polymer shell under pressure as liquefied gases.

[0152] In particular, heat acts on the microballoons, softening the outer polymer shell and simultaneously converting the liquid blowing agent gas present in the shell into a gaseous state. The microballoons then irreversibly expand in three dimensions. When the internal and external pressures become equal, the expansion ends, maintaining the polymer shell, resulting in a closed-cell foam.

[0153] Many types of microballoons are commercially available and are differentiated by their expansion size (unexpanded diameter 6-45 μm) and the initial temperature required for their expansion (75-220° C.). An example of a commercially available microballoon is the Expancel® DU type (DU = dry unexpanded) from Akzo Nobel.

[0154] Unexpanded microballoons are available as solids or aqueous dispersions with a microballoon content of approximately 40 to 45% by mass, and also as polymer-bonded microballoons (master batches), such as those containing approximately 65% by mass of microballoons in ethyl vinyl acetate. Among these, for example, Nobel's Expancel® DU type is preferred for ease of production when dispersed in a pressure-sensitive adhesive composition.

[0155] Foamed adhesive compositions can also be produced using so-called pre-expanded microballoons. In this category, microballoons that have already been expanded before being incorporated into the polymer matrix are dispersed in the adhesive composition. Pre-expanded microballoons are commercially available, for example, under the name Dualite® or under the type designation Expancel xxx DE (dry expanded) from Akzo Nobel.

[0156] When the pressure-sensitive adhesive composition contains microballoons, at least 90% of all hollow spaces formed by the microballoons in the pressure-sensitive adhesive layer preferably have a maximum diameter of 20 to 75 μm, more preferably 25 to 65 μm. "Maximum diameter" is understood to mean the maximum extension of the microballoons in any spatial direction.

[0157] Diameter determinations are made on freeze-fracture sections using a scanning electron microscope at 500x magnification. It is possible to determine the diameter of each individual microballoon graphically.

[0158] When foaming with microballoons, the microballoons can be provided to the formulation as a batch, a paste, or they can be present in suspension in a solvent.

[0159] The proportion of microballoons in the adhesive composition is between 0.5 and 2.5% by mass, preferably between 1.0 and 2.0% by mass, based on the total adhesive composition, where the values are for unexpanded microballoons.

[0160] The pressure-sensitive adhesive composition may contain non-expandable hollow microbeads in addition to the silicone resin-surfaced particles and expandable hollow microbeads. The hollow microbeads may have almost all of their gas-containing cavities permanently closed by dense shells, regardless of whether the shells consist solely of an elastic and thermoplastic extensible polymer mixture or, for example, of an elastic and—within the temperature range possible for plastic processing—non-thermoplastic glass.

[0161] Other beads that can be contained in the pressure-sensitive adhesive composition include, for example, polymer solid beads, glass hollow beads, glass solid beads, ceramic hollow beads, ceramic solid beads, and / or carbon solid beads ("carbon microballoons").

[0162] The relative density of the foamed pressure-sensitive adhesive composition is preferably 450 to 950 kg / m 3 , preferably 600 to 800 kg / m 3 is.

[0163] The relative density refers to the ratio of the density of a foamed PSA composition to the density of an unfoamed PSA composition of the same formulation. The relative density of the PSA composition is preferably 0.20 to 0.99, more preferably 0.30 to 0.90, and particularly preferably 0.50 to 0.85.

[0164] (Adhesive composition) The adhesive layer can be formed using an adhesive such as an aqueous adhesive, a solvent-based adhesive, a hot-melt adhesive, or an active energy ray-curable adhesive, including the above-mentioned adhesive composition. An aqueous adhesive refers to a form in which an adhesive composition (adhesive layer-forming components) is contained in a solvent (aqueous solvent) containing water as the main component, and typically includes what is called a water-dispersed adhesive (a form in which at least a portion of the adhesive composition is dispersed in water). A solvent-based adhesive refers to a form in which an adhesive composition is contained in an organic solvent. The adhesive layer in the adhesive tape of this embodiment is preferably formed using a solvent-based adhesive, from the viewpoint of achieving suitable adhesive properties such as shear adhesive strength.

[0165] <Other layers> The adhesive tape of the present embodiment is not particularly limited, and other layers may be provided as appropriate depending on the purpose, such as a primer layer, an antistatic layer, a non-flammable layer, a decorative layer, a conductive layer, a heat-conductive layer, and a release layer.

[0166] <Adhesive tape shape, characteristics, etc.> The pressure-sensitive adhesive tape of the present embodiment may be configured with only an adhesive layer, or may be configured with an adhesive layer on one side of a base layer, or may be configured with adhesive layers on both sides of a base layer in the first aspect. Also, in the second aspect, it may be configured with an adhesive layer on one side of a base layer, or may be configured with adhesive layers on both sides of a base layer, but because a pair of adherends are fixed via the adhesive tape, a configuration with adhesive layers on both sides of a base layer is preferred.

[0167] The shape and dimensions of the adhesive tape of this embodiment are not particularly limited, and include, for example, adhesive tapes having shapes and dimensions suitable for attachment to a specified adherend (e.g., adhesive tapes in a state after being punched), and long sheet-like adhesive tapes (e.g., adhesive tapes before being processed into a specific shape). Furthermore, the pressure-sensitive adhesive tape of the present embodiment may be optionally provided with a non-adhesive gripping region for, for example, attaching to an adherend or peeling from an adherend.

[0168] The thickness of the adhesive tape is not particularly limited and can be selected appropriately depending on the layer structure of the adhesive tape and the thicknesses of the adhesive layer and base layer, etc., but is preferably 15 μm to 800 μm, more preferably 30 μm to 540 μm, even more preferably 60 μm to 320 μm, and particularly preferably 70 μm to 250 μm. In this specification, the "thickness of the adhesive tape" refers to the average thickness of a total of 25 points, measured by cutting the adhesive tape at five points at 100 mm intervals along the length and across the width, and measuring the thickness of the adhesive layer at five points at 100 mm intervals along the width on each cut surface using a TH-104 thickness measuring instrument for paper and film (manufactured by Tester Sangyo Co., Ltd.).

[0169] When the pressure-sensitive adhesive tape of the present embodiment has a base layer, the hardness (Type A hardness (Shore A hardness)) of the pressure-sensitive adhesive tape is not particularly limited and can be appropriately selected depending on the purpose. However, it is preferably 10 to 100, more preferably 20 to 85, and even more preferably 64 to 85. When the Shore A hardness of the pressure-sensitive adhesive tape having a base layer is within the above-mentioned preferred range, the drop impact resistance is increased. Furthermore, even when the pressure-sensitive adhesive tape is stretched and peeled, the re-peeling operation by peeling the pressure-sensitive adhesive tape is facilitated. On the other hand, if the Shore A hardness is less than 10, the pressure-sensitive adhesive tape may not be able to withstand the impact force and may be destroyed. Furthermore, the pressure-sensitive adhesive tape may tear when stretched and peeled. On the other hand, if the Shore A hardness of the pressure-sensitive adhesive tape having a base layer exceeds 100, the pressure-sensitive adhesive tape may peel off at the interface between the pressure-sensitive adhesive tape and the adherend due to the impact force. Furthermore, when an attempt is made to stretch and re-peel the pressure-sensitive adhesive tape, re-peeling may not be possible because the stress required for stretching becomes too high. The rubber hardness of the adhesive tape is Shore A hardness, and refers to a value measured in accordance with JIS K 6253 using a durometer (spring type rubber hardness tester) (model: GS-719G, manufactured by Teclock Corporation).

[0170] The stress at 25% elongation of the pressure-sensitive adhesive tape is preferably 0.15 MPa to 82 MPa, more preferably 0.15 MPa to 10 MPa, even more preferably 0.15 MPa to 5 MPa, and most preferably 0.15 MPa to 3 MPa. When the stress at 25% elongation of the pressure-sensitive adhesive tape is 0.15 MPa to 82 MPa, a suitable adhesive strength for the pressure-sensitive adhesive tape can be obtained. Furthermore, the adhesive tape can be peeled off relatively easily (stretch-released). On the other hand, if the stress at 25% elongation of the adhesive tape is less than 0.15 MPa, the adhesive strength may be insufficient, and the adhesive tape may peel off when a load is applied in the shear direction of the adhesive tape while fixing hard adherends to each other. On the other hand, if the stress at 25% elongation of the adhesive tape exceeds 82 MPa, the adhesive tape may be difficult to displace in response to an impact force, making it difficult to obtain drop impact resistance, and the force required to stretch the adhesive tape when peeling it off tends to be excessive. The stress at 25% elongation of adhesive tape refers to the stress value measured when the adhesive tape is punched out into a dumbbell shape with a gauge length of 20 mm and a width of 5 mm, and pulled in the length direction at a tensile speed of 500 mm / min using a Tensilon tensile testing machine (model: RTF-1210, manufactured by A&D Co., Ltd.) under measurement conditions of 23°C and 50% RH, and stretched to 25%.

[0171] The breaking strength of the pressure-sensitive adhesive tape is not particularly limited and can be appropriately selected depending on the purpose, but is preferably 10 MPa to 100.0 MPa, more preferably 15 MPa to 90.0 MPa, even more preferably 30 MPa to 90.0 MPa, and particularly preferably 40 MPa to 90.0 MPa. When the breaking strength of the pressure-sensitive adhesive tape is within the above-mentioned preferred range, it is possible to obtain suitable adhesive strength while preventing the pressure-sensitive adhesive tape from being destroyed by impact force. Furthermore, it is possible to prevent the pressure-sensitive adhesive tape from tearing even when the pressure-sensitive adhesive tape is rapidly stretched to be peeled off, and the load required to stretch the pressure-sensitive adhesive tape is not excessive, making it easy to perform re-peeling by peeling. On the other hand, when the breaking strength of the pressure-sensitive adhesive tape is less than 10 MPa, the pressure-sensitive adhesive tape may tear when rapidly stretched to be peeled off. On the other hand, when the breaking strength of the pressure-sensitive adhesive tape exceeds 100.0 MPa, the pressure-sensitive adhesive tape may not be stretched sufficiently to be re-peeled. The force required to stretch and deform an adhesive tape also depends on the thickness of the adhesive tape. For example, even if an adhesive tape that is thick and has high breaking strength is stretched and then tried to be re-peeled, it may not be possible to stretch it sufficiently and the tape may not be re-peeled. The breaking strength of adhesive tape refers to the stress value measured when the tape is punched into a dumbbell shape with a gauge length of 20 mm and a width of 5 mm, and pulled lengthwise at a tensile speed of 500 mm / min using a Tensilon tensile testing machine (model: RTF-1210, manufactured by A&D Co., Ltd.) at an ambient temperature of 23°C and 50% RH until it breaks.

[0172] The breaking elongation of the adhesive tape is not particularly limited and can be selected appropriately depending on the purpose, but is preferably 400% to 2000%, more preferably 500% to 1800%, and even more preferably 600% to 1200%. If the breaking elongation of the adhesive tape is 400% or more, even if the adhesive tape is firmly adhered to an adherend, when the adhesive tape is re-peeled, the stress required to stretch the adhesive tape in the horizontal to vertical direction relative to the adherend surface is not too large, and the adhesive tape can be easily peeled off without excessive stretching. Furthermore, if the breaking elongation is 2000% or less, when the adhesive tape is re-peeled, the stretching distance in the horizontal to vertical direction relative to the adherend surface is not too long, allowing work to be done in a small space. If the breaking elongation is too small, when the adhesive tape is to be peeled again, it may break when stretched horizontally or vertically relative to the adherend surface to be peeled off, and the tape may not be able to be peeled off. On the other hand, if the breaking elongation is too large, when the adhesive tape is to be peeled again, the stretching distance in the horizontal or vertical direction relative to the adherend surface may become too long, resulting in poor workability. The breaking elongation of adhesive tape refers to the tensile elongation measured when the adhesive tape is punched out into a dumbbell shape with a gauge length of 20 mm and a width of 5 mm, and pulled in the lengthwise direction at a tensile speed of 500 mm / min using a Tensilon tensile testing machine (model: RTF-1210, manufactured by A&D Co., Ltd.) under measurement conditions of 23°C and 50% RH, until breaking.

[0173] In both the first and second aspects, the pressure-sensitive adhesive tape of this embodiment has the above-mentioned predetermined pressure-sensitive adhesive layer, and therefore can exhibit excellent drop impact resistance. The drop impact resistance can be confirmed by the method described in "Evaluation of Drop Impact Resistance" in the Examples section below. In the drop impact resistance evaluation, the height at which the pressure-sensitive adhesive tape peels off is preferably 60 cm or more, more preferably 70 cm or more, and particularly preferably 80 cm or more.

[0174] Among the pressure-sensitive adhesive tapes of this embodiment, the pressure-sensitive adhesive tape of the second aspect can be peeled by pulling in a direction perpendicular to the surface to which the tape is applied (90° direction) under specified conditions. Specifically, the pressure-sensitive adhesive tape of this embodiment has the results of evaluation according to the "Evaluation of 90° Stretch Peeling (High Speed)" described in the Examples section below, where "the pressure-sensitive adhesive tape broke zero times out of three times" or "the pressure-sensitive adhesive tape broke one time out of three times, and / or the area of the pressure-sensitive adhesive composition remaining on the adherend is less than one-fifth of the initial applied area." When the pressure-sensitive adhesive tape has such physical properties, it can be removed from the adherend more easily and more quickly.

[0175] The pressure-sensitive adhesive tape of this embodiment also has excellent impact resistance. Impact resistance can be confirmed, for example, by the method described in the "Evaluation of Impact Resistance" section in the Examples section below. In the evaluation of impact resistance, the height of the impact point at which peeling or destruction of the pressure-sensitive adhesive tape occurs can be appropriately selected within a range that does not impair the effects of the present invention, but is preferably 30 cm or more, more preferably 40 cm or more, even more preferably 50 cm or more, and particularly preferably 60 cm or more. If the height is less than 30 cm, sufficient impact resistance tends not to be obtained.

[0176] The 180° peel adhesive strength of the pressure-sensitive adhesive tape is not particularly limited and can be appropriately selected depending on the purpose, but is preferably 3 N / 20 mm to 50 N / 20 mm, more preferably 10 N / 20 mm to 50 N / 20 mm, and even more preferably 15 N / 20 mm to 45 N / 20 mm. When the 180° peel adhesive strength is within the above-mentioned preferred range, the pressure-sensitive adhesive tape has an appropriate adhesive strength without causing peeling or slippage from the adherend, and can be easily peeled off when stretched horizontally or vertically relative to the adhesive surface of the adherend and then peeled off again. The 180° peel adhesive strength of adhesive tape refers to the value measured in accordance with JIS Z 0237.

[0177] <Adhesive tape manufacturing method> In the present embodiment, the method for producing the pressure-sensitive adhesive tape is not particularly limited and can be appropriately selected from known methods. A method for producing a pressure-sensitive adhesive tape that does not have a base layer includes at least an adhesive layer forming step. A method for producing a pressure-sensitive adhesive tape in which an adhesive layer is provided on one or both sides of a base layer preferably includes an adhesive layer forming step, a base layer forming step, and a lamination step, and further includes other layer forming steps as necessary. The pressure-sensitive adhesive tape can also be produced by a simultaneous multilayer formation step in which the adhesive layer forming step and the base layer forming step are performed simultaneously.

[0178] The adhesive layer forming step is not particularly limited as long as it can form an adhesive layer and can be appropriately selected depending on the purpose, and examples include methods of forming an adhesive layer on the surface of a release sheet by heat pressing, extrusion casting, uniaxial stretching, sequential secondary stretching, simultaneous biaxial stretching, inflation, tube printing, calendaring, solution printing, etc. Among these, extrusion casting and solution printing are preferred. The release sheet is not particularly limited and can be appropriately selected depending on the purpose, and examples thereof include paper such as kraft paper, glassine paper, and wood-free paper; resin films such as polyethylene, polypropylene (biaxially oriented polypropylene (OPP), uniaxially oriented polypropylene (CPP)), and polyethylene terephthalate (PET); laminated paper in which the above-mentioned paper and a resin film are laminated together; and paper in which the above-mentioned paper has been sealed with clay, polyvinyl alcohol, or the like and one or both sides of which has been subjected to a release treatment with a silicone-based resin or the like. These may be used alone or in combination of two or more types.

[0179] The base layer forming step is not particularly limited as long as it can form a base layer and can be appropriately selected depending on the purpose, and examples include a heat press method, a casting method using extrusion molding, a uniaxial stretching method, a sequential secondary stretching method, a simultaneous biaxial stretching method, an inflation method, a tube method, a calendar method, and a solution method. These methods may be used alone or in combination of two or more. Among these, the casting method using extrusion molding, the inflation method, the tube method, the calendar method, and the solution method are preferred in terms of imparting suitable flexibility and extensibility to the base layer. The substrate layer may be surface-treated in order to further improve adhesion to the adhesive layer. The surface treatment method is not particularly limited and can be appropriately selected from known methods as long as it does not impair the properties of the adhesive tape. Examples include sandblasting, surface polishing / rubbing, corona discharge treatment, chromic acid treatment, flame treatment, hot air treatment, ozone treatment, ultraviolet irradiation treatment, and oxidation treatment.

[0180] The lamination step is a step of laminating a substrate layer and an adhesive layer. The method for laminating the substrate layer and the adhesive layer is not particularly limited and can be appropriately selected from known methods, for example, a method of laminating the substrate layer and the adhesive layer in a state where they are attached to the release sheet formed in the adhesive layer forming step by applying pressure.

[0181] <Applications of adhesive tape> The pressure-sensitive adhesive tape can be suitably used for fixing parts in various industrial fields, such as fixing metal plates to each other or fixing exterior parts to housings that make up relatively large electronic devices such as flat-screen televisions, home appliances, and office automation equipment, fixing exterior parts and rigid parts such as batteries to relatively small electronic devices such as mobile electronic terminals, cameras, and personal computers, or temporarily fixing such parts, as well as for applications such as labels that display product information.

[0182] Although the embodiments of the present invention have been described above, the pressure-sensitive adhesive tape of the present invention is not limited to the above examples and can be modified as appropriate. [Example]

[0183] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples in any way.

[0184] The pressure-sensitive adhesive tapes obtained in the examples and comparative examples were measured and evaluated according to the following methods.

[0185] (1) Measurement of the breaking strength and breaking elongation of the base layer Each substrate layer was punched out into a dumbbell shape with a gauge length of 20 mm and a width of 5 mm, and the breaking strength and breaking elongation of the substrate layer were measured by pulling them in the longitudinal direction at a tensile speed of 500 mm / min using a Tensilon tensile testing machine (model: RTF-1210, manufactured by A&D Co., Ltd.) under conditions of a measurement atmosphere of 23°C and 50% RH.

[0186] (2) Rubber hardness measurement The Type A hardness (Shore A) of each adhesive tape was measured in accordance with JIS K 6253 using a durometer (spring type rubber hardness tester) (model: GS-719G, manufactured by Teclock Corporation).

[0187] (3) Measurement of the thickness of the base layer and adhesive layer The base layer and adhesive layer were cut lengthwise at five locations at 100 mm intervals and widthwise at five locations, and the thickness of each cut surface was measured at five locations at 100 mm intervals widthwise using a TH-104 paper and film thickness measuring instrument (manufactured by Tester Sangyo Co., Ltd.). The average value of the thickness at these 25 locations was used as the thickness of the base layer and adhesive layer.

[0188] (4) Measurement of particle size The average particle size of the particles was measured using a measuring device (Microtrac) that uses a laser diffraction scattering method.

[0189] (5) Evaluation of 90° stretch peeling (high speed) Each adhesive tape was cut to a length of 60 mm and a width of 10 mm. With the length and width of the tape protruding from the tape as gripping handles, one side of the adhesive tape was attached to a clean, smooth-surfaced aluminum plate (150 mm long, 50 mm wide, 2 mm thick, alloy number A1050) under conditions of 23°C and 50% RH. Next, a clean, smooth-surfaced acrylic plate (150 mm long, 50 mm wide, 2 mm thick, Acrylite L, colorless, manufactured by Mitsubishi Rayon Co., Ltd.) was attached to the side of the adhesive tape opposite the side to which the aluminum plate was attached. The laminated structure of the aluminum plate, the adhesive tape, and the acrylic plate was pressed by rolling it back and forth once while applying a load of 5 kg, and then left to stand for 3 days under conditions of 23°C and 50% RH to prepare a test specimen. Under conditions of an atmosphere of 23°C and 50% RH, the gripping portion of the adhesive tape in the test piece was stretched in a 90° direction (vertical direction) on the acrylic plate side relative to the adhesive surface of the adhesive tape using a Tensilon tensile tester (model: RTF-1210, manufactured by A&D Co., Ltd.) with a load limiter set to 15 N and at a tensile speed of 1000 mm / min. During this time, the occurrence of breakage in the adhesive tape and the degree of residual adhesive composition on the adherend (at least one of the aluminum plate and the acrylic plate) after the adhesive tape was peeled off were visually confirmed. The test was carried out three times using the above method, and the removability (stretch peel in the vertical direction) was evaluated based on the following evaluation criteria. [Evaluation criteria] ⊚: The adhesive tape broke 0 times out of 3 times. ◯: The adhesive tape broke once out of three times, and / or the area of the adhesive composition remaining on the adherend was less than 1 / 5 of the initial applied area. Δ: The adhesive tape broke once out of three times, the adhesive tape did not stretch, and the area of the adhesive tape remaining on the adherend was 4 / 5 or more of the initial applied area. ×: The adhesive tape broke two or more times out of three times, and / or the adhesive tape did not stretch and could not be peeled off again. In addition, ◎ and ○ indicate that there is no problem in use.

[0190] (6) Evaluation of 90° stretch peeling (medium speed) The same test and evaluation was carried out in the "Evaluation of perpendicular stretch peeling (high speed)" above, except that the pulling speed of the pressure-sensitive adhesive tape was changed from 1000 mm / min to 500 mm / min.

[0191] (7) Evaluation of 90° stretch peeling (low speed) The same test and evaluation was carried out, except that the pulling speed of the adhesive tape was changed from 1000 mm / min to 50 mm / min in the above "Evaluation of perpendicular stretch peeling (high speed)".

[0192] (8) Evaluation of drop impact resistance As shown in FIG. 1(a), two pieces of each adhesive tape 1 were prepared, each cut to a length of 20 mm and a width of 2 mm. The adhesive tapes 1 were attached parallel to an aluminum plate 11 (50 mm long, 25 mm wide, 0.8 mm thick, alloy number A1050) with a 40 mm gap between them. An acrylic plate 12 (50 mm long, 25 mm wide, 2.5 mm thick, Acrylite L, colorless, manufactured by Mitsubishi Rayon Co., Ltd.) was attached to the opposite side of the adhesive tape 1 and pressed with a roller once back and forth under a 2 kg load. The plate was then left to stand for 24 hours under conditions of 40°C and 50% RH to prepare a test piece 10. Note that FIG. 1(a) is a schematic plan view of the test piece 10 as seen from the acrylic plate 12 side. For illustrative purposes, the acrylic plate 12 is shown shifted, but in reality, the periphery of the acrylic plate 12 and the periphery of the aluminum plate 11 are arranged so that they overlap in plan view. Next, as shown in FIG. 1(b), a U-shaped measurement platform 22 (made of aluminum, length t: 150 mm, width (no symbol in the figure): 100 mm, height h: 45 mm, thickness w: 5 mm) was placed on the base of a DuPont impact tester (manufactured by Tester Sangyo Co., Ltd.), and a 300 g stainless steel load 21 was attached to the acrylic plate 12 side of the test piece 10. The test piece 10 was dropped onto the U-shaped measurement platform 22 with the aluminum plate 11 side facing downward under conditions of 23°C and 50% RH. The arrow X in FIG. 1(b) indicates the direction in which the test piece 10 with the load 21 attached was dropped. The height H from the highest point in the height direction of the U-shaped measurement platform 22 to the position P of the adhesive surface of the test piece 10 with the load 21 was changed in 10 cm increments starting from 10 cm, and the test piece 10 was dropped five times for each height. The height H at which peeling or breakage of the adhesive tape 1 on the test piece 10 was observed was measured. In addition, assuming an article in which adhesive tape is attached to an adherend, the measurement was carried out by applying a 300 g stainless steel load 21 to the acrylic plate 12 side of the test piece 10.

[0193] (9) Impact resistance evaluation Two pieces of each adhesive tape were prepared by cutting them into a length of 20 mm and a width of 5 mm. As shown in Figure 2, the adhesive tape 1 was attached parallel to an acrylic plate 2 (length 50 mm, width 50 mm, thickness 2 mm, Acrylite L, color: colorless, manufactured by Mitsubishi Rayon Co., Ltd.) with a 40 mm gap between them. Next, as shown in Figure 3, the acrylic plate 2 with the adhesive tape 1 attached thereto was attached to the center of an ABS plate 3 (length 150 mm, width 100 mm, thickness 2 mm, Tough Ace R, manufactured by Sumitomo Bakelite Co., Ltd., color: natural, no grain) and the laminated structure of the acrylic plate 2, the adhesive tape 1, and the ABS plate 3 was pressed and bonded by rolling it back and forth once with a roller while applying a load of 2 kg. The laminate was then left to stand at 40°C and 50% RH for 24 hours to prepare a test specimen. As shown in FIG. 4, a U-shaped measurement platform (150 mm long, 100 mm wide, 45 mm high, and 5 mm thick, made of aluminum) 4 was placed on the base of a DuPont impact tester (manufactured by Tester Sangyo Co., Ltd.), and the test specimen was placed on the platform with the acrylic plate 2 of the test specimen facing downward (FIG. 4). Under conditions of an ambient temperature of 23°C and 50% RH, a stainless steel impact core (25 mm diameter, 300 g mass) 5 was dropped onto the center of the ABS plate 3 from the ABS plate 3 side. The height of the impact core 5 was changed in 10 cm increments starting from 10 cm, and the impact core 5 was dropped five times at 10-second intervals for each height. The height at which peeling or breakage of the adhesive tape was observed on the test specimen was measured, and the impact resistance was evaluated based on the following evaluation criteria. [Evaluation criteria] ⊚: When the impact core 5 was dropped from a height of 60 cm or more, the adhesive tape was not peeled off or broken. ◯: When the impact core 5 was dropped from a height of 30 cm to 50 cm, the adhesive tape was not peeled off or broken. △: When the impact core 5 was dropped from a height of 10 cm or more and less than 30 cm, the adhesive tape peeled off or was broken. ×: When the height of the impact core 5 reached 10 cm, the adhesive tape peeled off or was broken. ◎ and ○ indicate that there is no problem with use.

[0194] (10) Evaluation of 180° peel adhesive strength The 180° peel adhesive strength was measured in accordance with JIS Z 0237. Specifically, each adhesive tape was cut to a length of 150 mm and a width of 20 mm, and one side of the adhesive tape was backed with a 25 μm-thick PET film. Next, the other side of the adhesive tape was attached to a stainless steel plate (length 100 mm, width 30 mm, thickness 3 mm) under conditions of an atmosphere of 23°C and 50% RH. The laminated structure of the adhesive tape and the stainless steel plate was pressed and bonded by rolling it back and forth once with a roller while applying a load of 2 kg, and then left to stand for 1 hour under conditions of an atmosphere of 23°C and 50% RH to prepare a test specimen. The adhesive tape in the test piece was stretched in the 180° direction (horizontal direction) at a tension speed of 300 mm / min using a Tensilon tensile tester (model: RTF-1210, manufactured by A&D Co., Ltd.) under conditions of an atmosphere of 23°C and 50% RH, and the 180° peel adhesive strength of the adhesive tape was measured.

[0195] Next, the materials used in the examples and comparative examples are as follows.

[0196] <Material for base material> ·Base material (1) (SIS) A mixture of styrene-isoprene copolymer and styrene-isoprene-styrene copolymer (hereinafter sometimes referred to as "SIS") was used as the substrate material (1). The mixture contained 25% by weight of a styrene-derived structural unit represented by the following chemical formula (3), and the proportion of the styrene-isoprene copolymer to the total amount of the resin composition (1) was 17% by weight.

[0197] [ka]

[0198] ·Base material (2) (SEEPS) A pressure vessel that had been purged with nitrogen and dried was charged with 3,000 mL of cyclohexane as a solvent and 9.2 mL of 10.5% by mass sec-butyllithium (cyclohexane solution) as an initiator, and the temperature was raised to 60°C. After that, 100 mL of styrene was added and polymerization was carried out for 60 minutes. Then, 270 mL of isoprene and 350 mL of butadiene were added at the same temperature, and the mixture was allowed to react for 90 minutes. Subsequently, 100 mL of styrene was added at the same temperature, and the mixture was polymerized for 60 minutes. The polymerization was then terminated with 0.52 mL of methanol, and a polymerization reaction solution containing a block copolymer was obtained. To this reaction mixture, 29.3 g of palladium carbon (palladium loading: 5% by mass) was added as a hydrogenation catalyst, and a hydrogenation reaction was carried out for 10 hours at a hydrogen pressure of 2 MPa and 150° C. After cooling and releasing the pressure, the palladium carbon was removed by filtration, and the filtrate was concentrated and further dried in vacuo to obtain a substrate material (2). The obtained substrate material (2) was a styrene-ethylene-ethylene / propylene-styrene block copolymer (hereinafter sometimes referred to as "SEEPS"), with a styrene content of 30 mass%, a weight average molecular weight of 98,000, a molecular weight distribution of 1.03, and a hydrogenation rate of 98%.

[0199] <Adhesive composition> The pressure-sensitive adhesive composition of the present invention contains the following particles and pressure-sensitive adhesive resin.

[0200] <Additional particles> Silicone particles (1) The silicone particles (1) were particles with a silicone resin surface and a silicone rubber interior (KMP-601, manufactured by Shin-Etsu Chemical Co., Ltd., volume average particle size: 12 μm, particle size distribution (D 90 / D 10 ):4.4) was used.

[0201] Silicone particles (2) The silicone particles (2) were particles with a silicone resin surface and a silicone rubber interior (KMP-600, manufactured by Shin-Etsu Chemical Co., Ltd., volume average particle size: 5 μm, particle size distribution (D 90 / D 10 ):3.2) was used.

[0202] Silicone particles (3) The silicone particles (3) are particles having a silicone resin surface and a silicone rubber interior (Shin-Etsu Chemical Co., Ltd., KMP-602, volume average particle size: 30 μm, particle size distribution (D 90 / D 10 ):5.2) was used.

[0203] Silicone particles (4) The silicone particles (4) were particles with a silicone resin surface and a silicone rubber interior (Shin-Etsu Chemical Co., Ltd., X-52-7030, volume average particle size: 0.8 μm, particle size distribution (D 90 / D 10 ):6.0) was used.

[0204] Silicone particles (5) As the silicone particles (5), particles formed of silicone rubber (particles without silicone resin on the surface) (Shin-Etsu Chemical Co., Ltd., KMP-598, volume average particle size: 13 μm, particle size distribution (D 90 / D 10 ):4.9) was used.

[0205] Silicone particles (6) As the silicone particles (6), particles formed from silicone resin (KMP-701, manufactured by Shin-Etsu Chemical Co., Ltd., volume average particle size: 3.5 μm, particle size distribution (D 90 / D 10 ):3.4) was used.

[0206] Aluminum hydroxide particles Aluminum hydroxide particles (manufactured by Nippon Light Metal Co., Ltd., BW153, volume average particle size: 18 μm, particle size distribution (D 90 / D 10 ):12.3) was used.

[0207] Adhesive resin (1) (acrylic) A reaction vessel equipped with a stirrer, reflux condenser, nitrogen inlet tube, thermometer, and dropping funnel was charged with 75.94 parts by weight of n-butyl acrylate, 5 parts by weight of 2-ethylhexyl acrylate, 15 parts by weight of cyclohexyl acrylate, 4 parts by weight of acrylic acid, 0.06 parts by weight of 4-hydroxybutyl acrylate, and 200 parts by weight of ethyl acetate. The mixture was heated to 65°C while stirring and blowing in nitrogen to obtain mixture (1). Next, 4 parts by weight of a 2,2'-azobisisobutyronitrile solution (2.5% solids) previously dissolved in ethyl acetate was added to mixture (1), and the mixture was stirred and held at 65°C for 10 hours to obtain mixture (2). Next, mixture (2) was diluted with 98 parts by weight of ethyl acetate and filtered through a 200-mesh wire mesh to obtain acrylic copolymer solution (1) with a weight-average molecular weight of 1.6 million (polystyrene equivalent). Next, 100 parts by mass of the acrylic copolymer solution (1) was mixed and stirred with 5 parts by mass of a polymerized rosin ester-based tackifying resin (D-125, Arakawa Chemical Industries, Ltd.) and 15 parts by mass of a petroleum-based tackifying resin (FTR (registered trademark) 6125, manufactured by Mitsui Chemicals, Inc.), and then ethyl acetate was added to obtain an adhesive resin solution (1) with a solid content of 35% by mass.

[0208] Adhesive resin (2) (acrylic) A reactor equipped with a stirrer, reflux condenser, thermometer, dropping funnel, and nitrogen gas inlet was prepared by dissolving 96.4 parts by weight of n-butyl acrylate, 3.5 parts by weight of acrylic acid, 0.1 parts by weight of 2-hydroxyethyl acrylate, and 0.1 parts by weight of 2,2'-azobisisobutyronitrile as a polymerization initiator in a solvent consisting of 100 parts by weight of ethyl acetate. The mixture was polymerized at 70 ° C for 12 hours to obtain an acrylic copolymer with a weight average molecular weight of 800,000 (polystyrene equivalent). Next, 10 parts by weight of Arakawa Chemical Co., Ltd.'s Pencel D135 (a pentaerythritol ester of polymerized rosin) and 10 parts by weight of Arakawa Chemical Co., Ltd.'s Super Ester A100 (a glycerin ester of disproportionated rosin) were added to 100 parts by weight of the acrylic copolymer, and ethyl acetate was added and mixed uniformly to obtain a pressure-sensitive adhesive resin solution (2) with a non-volatile content of 35%.

[0209] <Preparation of Pressure-Sensitive Adhesive Composition> Adhesive composition (1) 30 parts by mass of silicone particles (1) were added to 100 parts by mass of the solid content of the adhesive resin solution (1). Subsequently, 1.3 parts by mass of a crosslinking agent (Burnoc D-40, manufactured by DIC Corporation; trimethylolpropane adduct of tolylene diisocyanate, isocyanate group content 7% by mass, non-volatile content 40% by mass) was added to the solution containing the silicone particles (1) based on 100 parts by mass of the adhesive resin solution (1), and the mixture was stirred and mixed uniformly, followed by the addition of ethyl acetate to obtain a solution of adhesive composition (1) with a solid content of 40% by mass.

[0210] Adhesive composition (2) 30 parts by mass of silicone particles (1) were added to 100 parts by mass of the solid content of the adhesive resin solution (2). Subsequently, 1.1 parts by mass of a crosslinking agent (Burnoc D-40, manufactured by DIC Corporation; trimethylolpropane adduct of tolylene diisocyanate, isocyanate group content 7% by mass, non-volatile content 40% by mass) based on 100 parts by mass of the adhesive resin solution (2) were added to the solution containing the silicone particles (1), and the mixture was stirred and mixed uniformly, followed by the addition of ethyl acetate to obtain a solution of adhesive composition (2) with a solid content of 40% by mass.

[0211] Adhesive composition (3) 30 parts by mass of silicone particles (2) were added to 100 parts by mass of the solid content of the adhesive resin solution (1). Subsequently, 1.3 parts by mass of a crosslinking agent (Burnoc D-40, manufactured by DIC Corporation; trimethylolpropane adduct of tolylene diisocyanate, isocyanate group content 7% by mass, non-volatile content 40% by mass) was added to the solution containing the silicone particles (2) based on 100 parts by mass of the adhesive resin solution (1), and the mixture was stirred and mixed uniformly, followed by the addition of ethyl acetate to obtain a solution of adhesive composition (3) with a solid content of 40% by mass.

[0212] Adhesive composition (4) 30 parts by mass of silicone particles (3) were added to 100 parts by mass of the solid content of the adhesive resin solution (1). Subsequently, 1.3 parts by mass of a crosslinking agent (Burnoc D-40, manufactured by DIC Corporation; trimethylolpropane adduct of tolylene diisocyanate, isocyanate group content 7% by mass, non-volatile content 40% by mass) was added to the solution containing the silicone particles (3) based on 100 parts by mass of the adhesive resin solution (1), and the mixture was stirred and mixed uniformly, followed by the addition of ethyl acetate to obtain a solution of adhesive composition (4) with a solid content of 40% by mass.

[0213] Adhesive composition (5) To 100 parts by mass of the adhesive resin solution (1), 1.3 parts by mass of a crosslinking agent (Burnoc D-40, manufactured by DIC Corporation; trimethylolpropane adduct of tolylene diisocyanate, isocyanate group content 7% by mass, non-volatile content 40% by mass) was added, and the mixture was stirred and mixed to become uniform. Then, ethyl acetate was added to obtain a solution of adhesive composition (5) with a solid content of 40% by mass.

[0214] Adhesive composition (6) 30 parts by mass of aluminum hydroxide particles were added to 100 parts by mass of the solid content of the PSA resin solution (1). Subsequently, 1.3 parts by mass of a crosslinking agent (Burnoc D-40, manufactured by DIC Corporation; trimethylolpropane adduct of tolylene diisocyanate, isocyanate group content 7% by mass, nonvolatile content 40% by mass) was added to the solution containing the aluminum hydroxide particles, based on 100 parts by mass of the PSA resin solution (1), and the mixture was stirred and mixed uniformly. Then, ethyl acetate was added to obtain a solution of PSA composition (6) with a solid content of 40% by mass.

[0215] Adhesive composition (7) 60 parts by mass of silicone particles (1) were added to 100 parts by mass of the solid content of the pressure-sensitive adhesive resin solution (1). Subsequently, 1.3 parts by mass of a crosslinking agent (Burnoc D-40, manufactured by DIC Corporation; trimethylolpropane adduct of tolylene diisocyanate, isocyanate group content 7% by mass, non-volatile content 40% by mass) was added to the solution containing the silicone particles (1) based on 100 parts by mass of the pressure-sensitive adhesive resin solution (1), and the mixture was stirred and mixed uniformly, followed by the addition of ethyl acetate to obtain a solution of pressure-sensitive adhesive composition (7) with a solid content of 40% by mass.

[0216] Adhesive composition (8) 30 parts by mass of silicone particles (4) were added to 100 parts by mass of the solid content of the pressure-sensitive adhesive resin solution (1). Subsequently, 1.3 parts by mass of a crosslinking agent (Burnoc D-40, manufactured by DIC Corporation; trimethylolpropane adduct of tolylene diisocyanate, isocyanate group content 7% by mass, non-volatile content 40% by mass) was added to the solution containing the silicone particles (4) based on 100 parts by mass of the pressure-sensitive adhesive resin solution (1), and the mixture was stirred and mixed uniformly, followed by the addition of ethyl acetate to obtain a solution of pressure-sensitive adhesive composition (8) with a solid content of 40% by mass.

[0217] Adhesive composition (9) 30 parts by mass of silicone particles (5) were added to 100 parts by mass of the solid content of the pressure-sensitive adhesive resin solution (1). Subsequently, 1.3 parts by mass of a crosslinking agent (Burnoc D-40, manufactured by DIC Corporation; trimethylolpropane adduct of tolylene diisocyanate, isocyanate group content 7% by mass, non-volatile content 40% by mass) was added to the solution containing the silicone particles (5) based on 100 parts by mass of the pressure-sensitive adhesive resin solution (1), and the mixture was stirred and mixed uniformly, followed by the addition of ethyl acetate to obtain a solution of pressure-sensitive adhesive composition (9) with a solid content of 40% by mass.

[0218] Adhesive composition (10) 30 parts by mass of silicone particles (6) were added to 100 parts by mass of the solid content of the pressure-sensitive adhesive resin solution (1). Subsequently, 1.3 parts by mass of a crosslinking agent (Burnoc D-40, manufactured by DIC Corporation; trimethylolpropane adduct of tolylene diisocyanate, isocyanate group content 7% by mass, non-volatile content 40% by mass) was added to the solution containing the silicone particles (6) based on 100 parts by mass of the pressure-sensitive adhesive resin solution (1), and the mixture was stirred and mixed uniformly, followed by the addition of ethyl acetate to obtain a solution of pressure-sensitive adhesive composition (10) with a solid content of 40% by mass.

[0219] Adhesive composition (11) Two parts by mass of silicone particles (6) were added to 100 parts by mass of the solid content of the pressure-sensitive adhesive resin solution (1). Subsequently, 1.3 parts by mass of a crosslinking agent (Burnoc D-40, manufactured by DIC Corporation; trimethylolpropane adduct of tolylene diisocyanate, isocyanate group content 7% by mass, non-volatile content 40% by mass) was added to the solution containing the silicone particles (6) based on 100 parts by mass of the pressure-sensitive adhesive resin solution (1), and the mixture was stirred and mixed uniformly. Then, ethyl acetate was added to obtain a solution of a pressure-sensitive adhesive composition (11) with a solid content of 40% by mass.

[0220] Adhesive composition (12) 45 parts by mass of silicone particles (1) were added to 100 parts by mass of the solid content of the pressure-sensitive adhesive resin solution (1). Subsequently, 1.3 parts by mass of a crosslinking agent (Burnoc D-40, manufactured by DIC Corporation; trimethylolpropane adduct of tolylene diisocyanate, isocyanate group content 7% by mass, non-volatile content 40% by mass) was added to the solution containing the silicone particles (1) based on 100 parts by mass of the pressure-sensitive adhesive resin solution (1), and the mixture was stirred and mixed uniformly, followed by the addition of ethyl acetate to obtain a solution of pressure-sensitive adhesive composition (12) with a solid content of 40% by mass.

[0221] Adhesive composition (13) 25 parts by mass of silicone particles (1) were added to 100 parts by mass of the solid content of the pressure-sensitive adhesive resin solution (1). Subsequently, 1.3 parts by mass of a crosslinking agent (Burnoc D-40, manufactured by DIC Corporation; trimethylolpropane adduct of tolylene diisocyanate, isocyanate group content 7% by mass, non-volatile content 40% by mass) was added to the solution containing the silicone particles (1) based on 100 parts by mass of the pressure-sensitive adhesive resin solution (1), and the mixture was stirred and mixed uniformly, followed by the addition of ethyl acetate to obtain a solution of pressure-sensitive adhesive composition (13) with a solid content of 40% by mass.

[0222] Adhesive composition (14) Two parts by mass of silicone particles (1) were added to 100 parts by mass of the solid content of the pressure-sensitive adhesive resin solution (1). Subsequently, 1.3 parts by mass of a crosslinking agent (Burnoc D-40, manufactured by DIC Corporation; trimethylolpropane adduct of tolylene diisocyanate, isocyanate group content 7% by mass, non-volatile content 40% by mass) was added to the solution containing the silicone particles (1) based on 100 parts by mass of the pressure-sensitive adhesive resin solution (1), and the mixture was stirred and mixed uniformly, followed by the addition of ethyl acetate to obtain a solution of pressure-sensitive adhesive composition (14) with a solid content of 40% by mass.

[0223] Next, examples and comparative examples will be described.

[0224] Example 1 The solution of the pressure-sensitive adhesive composition (1) was applied to a release liner (Film Vina 75E-0010GT, manufactured by Fujimori Kogyo Co., Ltd., the same applies hereinafter) using an applicator so that the thickness after drying would be 50 μm, and the applied solution was dried at 80° C. for 3 minutes to prepare a pressure-sensitive adhesive layer. Next, toluene was added to the substrate material (1) and stirred to make it uniform, and the mixture was applied to a release liner using an applicator so that the thickness after drying would be 100 μm, and then dried at 60° C. for 5 minutes to prepare a substrate layer. After peeling off the release liner from the base layer, the adhesive layer from which the release liner had been peeled off was attached to both sides of the base layer, and the laminated structure of the base layer and the adhesive layer was laminated by applying a pressure of 0.2 MPa to produce an adhesive tape (1). The obtained adhesive tape was evaluated by the above-mentioned method, and the results are shown in Table 1.

[0225] Example 2 An adhesive tape (2) was produced in the same manner as in Example 1, except that in the production of the adhesive tape (1) of Example 1, the substrate material (1) was changed to the substrate material (2). The obtained adhesive tape was evaluated by the above-mentioned method, and the results are shown in Table 1.

[0226] Example 3 An adhesive tape (3) was produced in the same manner as in Example 1, except that in the production of the adhesive tape (1) of Example 1, the adhesive composition (1) was changed to the adhesive composition (2). The obtained adhesive tape was evaluated by the above-mentioned method, and the results are shown in Table 1.

[0227] Example 4 An adhesive tape (4) was produced in the same manner as in Example 1, except that in the production of the adhesive tape (1) of Example 1, the adhesive composition (1) was changed to the adhesive composition (3). The obtained adhesive tape was evaluated by the above-mentioned method, and the results are shown in Table 1.

[0228] Example 5 An adhesive tape (5) was produced in the same manner as in the production of the adhesive tape (1) of Example 1, except that the thickness of the substrate layer was changed to 400 μm. The obtained adhesive tape was evaluated by the above-mentioned method, and the results are shown in Table 1.

[0229] Example 6 An adhesive tape (6) was produced in the same manner as in Example 1, except that in the production of the adhesive tape (1) of Example 1, the adhesive composition (1) was changed to the adhesive composition (4). The obtained adhesive tape was evaluated by the above-mentioned method, and the results are shown in Table 1.

[0230] Example 7 An adhesive tape (7) was produced in the same manner as in Example 1, except that in the production of the adhesive tape (1) of Example 1, a commercially available polyethylene terephthalate (PET) film (S-10 manufactured by Toray Industries, Inc., thickness 50 μm) was used as the base layer. The obtained pressure-sensitive adhesive tape was evaluated by the above-mentioned methods, and the results are shown in Table 1. The thickness, breaking strength, breaking elongation and rubber hardness of the PET film were measured by the above-mentioned methods, respectively.

[0231] Example 8 The pressure-sensitive adhesive composition (1) was applied to a release liner using an applicator so that the thickness after drying would be 100 μm, and then dried at 80° C. for 3 minutes to form a pressure-sensitive adhesive layer, thereby producing a pressure-sensitive adhesive tape (8). The pressure-sensitive adhesive tape (8) does not have a substrate layer. The obtained adhesive tape was evaluated by the above-mentioned method, and the results are shown in Table 1.

[0232] Example 9 An adhesive tape (9) was produced in the same manner as in the production of the adhesive tape (1) of Example 1, except that the thickness of the substrate layer was changed to 700 μm. The obtained adhesive tape was evaluated by the above-mentioned method, and the results are shown in Table 1.

[0233] Example 10 An adhesive tape (10) was produced in the same manner as in Example 1, except that in the production of the adhesive tape (1) of Example 1, the adhesive composition (1) was changed to the adhesive composition (12). The obtained adhesive tape was evaluated by the above-mentioned method, and the results are shown in Table 1.

[0234] Example 11 An adhesive tape (11) was produced in the same manner as in Example 1, except that the adhesive composition (1) in the production of the adhesive tape (1) of Example 1 was changed to an adhesive composition (13). The obtained adhesive tape was evaluated by the above-mentioned method, and the results are shown in Table 1.

[0235] Comparative Example 1 An adhesive tape (12) was produced in the same manner as in Example 1, except that in the production of the adhesive tape (1) of Example 1, the adhesive composition (1) was changed to the adhesive composition (5). The obtained adhesive tape was evaluated by the above-mentioned method, and the results are shown in Table 2.

[0236] Comparative Example 2 An adhesive tape (13) was produced in the same manner as in Example 1, except that in the production of the adhesive tape (1) of Example 1, the adhesive composition (1) was changed to the adhesive composition (6). The obtained adhesive tape was evaluated by the above-mentioned method, and the results are shown in Table 2.

[0237] Comparative Example 3 An adhesive tape (14) was produced in the same manner as in Example 1, except that in the production of the adhesive tape (1) of Example 1, the adhesive composition (1) was changed to the adhesive composition (7). The obtained adhesive tape was evaluated by the above-mentioned method, and the results are shown in Table 2.

[0238] Comparative Example 4 An adhesive tape (15) was produced in the same manner as in Example 1, except that in the production of the adhesive tape (1) of Example 1, the adhesive composition (1) was changed to the adhesive composition (8). The obtained adhesive tape was evaluated by the above-mentioned method, and the results are shown in Table 2.

[0239] Comparative Example 5 An adhesive tape (16) was produced in the same manner as in Example 1, except that in the production of the adhesive tape (1) of Example 1, the adhesive composition (1) was changed to the adhesive composition (9). The obtained adhesive tape was evaluated by the above-mentioned method, and the results are shown in Table 2.

[0240] Comparative Example 6 An adhesive tape (17) was produced in the same manner as in Example 1, except that in the production of the adhesive tape (1) of Example 1, the adhesive composition (1) was changed to the adhesive composition (10). The obtained adhesive tape was evaluated by the above-mentioned method, and the results are shown in Table 2.

[0241] Comparative Example 7 An adhesive tape (18) was produced in the same manner as in Example 1, except that in the production of the adhesive tape (1) of Example 1, the adhesive composition (1) was changed to the adhesive composition (11). The obtained adhesive tape was evaluated by the above-mentioned method, and the results are shown in Table 2.

[0242] Comparative Example 8 An adhesive tape (19) was produced in the same manner as in Example 1, except that in the production of the adhesive tape (1) of Example 1, the adhesive composition (1) was changed to the adhesive composition (14). The obtained adhesive tape was evaluated by the above-mentioned method, and the results are shown in Table 2.

[0243] Comparative Example 9 An adhesive tape (20) was produced in the same manner as in Example 8, except that the adhesive composition (1) in the production of the adhesive tape (8) of Example 8 was changed to the adhesive composition (5). The adhesive tape (20) does not have a base layer. The obtained adhesive tape was evaluated by the above-mentioned method, and the results are shown in Table 2.

[0244] [Table 1]

[0245] [Table 2]

[0246] The pressure-sensitive adhesive tapes of Examples 1 to 11 had the specific adhesive layer and therefore were superior in drop resistance compared to the pressure-sensitive adhesive tapes of Comparative Examples 1 to 9, which did not have the specific adhesive layer. Furthermore, among Examples 1 to 11, the pressure-sensitive adhesive tapes of Examples 1 to 6 and 10 to 11 had the specific adhesive layer and the specific base layer and therefore were superior in drop resistance and stretch-peelability compared to the pressure-sensitive adhesive tapes of Examples 7 to 9, which did not have the specific base layer. [Industrial Applicability]

[0247] According to the present invention, by having a specific adhesive layer, it is possible to provide a pressure-sensitive adhesive tape having excellent drop impact resistance. Also, according to the present invention, by having a specific adhesive layer and a specific base layer, it is possible to provide a pressure-sensitive adhesive tape having excellent drop impact resistance and being more easily and quickly removable from an adherend.

Claims

1. An adhesive tape having an adhesive layer on one or both sides of a base layer, the substrate layer has a thickness of 10 to 500 μm, a breaking strength of 10 to 90 MPa, and a breaking elongation of 400 to 1500%, The adhesive layer contains particles having an average particle size of 4 to 40 μm and having a silicone resin surface, and an adhesive resin; The content of the particles is 3 to 50 parts by mass relative to 100 parts by mass of the adhesive resin, An adhesive tape, characterized in that the volume ratio of the particles to the volume of the entire adhesive layer is 5 to 50%.

2. 2. The pressure-sensitive adhesive tape according to claim 1, wherein when particle diameters of particles corresponding to cumulative percentages of 10% and 90% in a cumulative particle size distribution of the particles are D10 and D90, respectively, the ratio of the particle diameter D90 to the particle diameter D10 (D90 / D10) is 2.5 to 20.

3. 3. The pressure-sensitive adhesive tape according to claim 1, wherein the base layer has a rubber hardness of 20 to 90A.

4. The pressure-sensitive adhesive tape according to any one of claims 1 to 3, wherein a ratio of an average particle size of the particles to an average thickness of the pressure-sensitive adhesive layer is 5 / 100 or more.

5. The pressure-sensitive adhesive tape according to any one of claims 1 to 4, which has a height H of 60 cm or more in a drop impact resistance test measured by the following measurement method. (Measurement method) Two pieces of adhesive tape cut to a length of 20 mm and a width of 2 mm were attached in parallel to an aluminum plate (length 50 mm, width 25 mm, thickness 0.8 mm, alloy number A1050) with a 40 mm gap between them. An acrylic plate (length 50 mm, width 25 mm, thickness 2.5 mm, Acrylite (registered trademark) L, color tone: colorless, manufactured by Mitsubishi Rayon Co., Ltd.) was attached to the other side of the adhesive tape, and pressure was applied by rolling it back and forth once while applying a load of 2 kg, and then the plate was left to stand for 24 hours under conditions of an atmosphere of 40°C and 50% RH to prepare a test piece. This was then tested in a DuPont impact tester (tester A U-shaped measuring stand was placed on the base of a test piece manufactured by Epson Corporation (manufactured by Epson Corporation), and a 300 g stainless steel load was placed on the acrylic plate side of the test piece, with the surface of the test piece where the acrylic plate and the load were in contact being the adhesive surface. The test piece was dropped five times onto the U-shaped measuring stand with the aluminum plate side facing downwards under conditions of an atmosphere of 23°C and 50% RH while changing the height H from the top of the U-shaped measuring stand in the height direction to the adhesive surface, and the height H was measured when peeling or destruction of the adhesive tape was observed on the test piece.

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