Adhesive tape

Abstract

To provide a tape that ensures excellent manual tearability, enhances efficiency of piping installation work, offers high adhesion to foamed polyolefin-based pipe insulators, and prevents deterioration of the insulation efficiency of the pipe insulator itself.SOLUTION: An adhesive tape has a base material and an adhesive layer, wherein a foamed polyolefin sheet having heat retention and elasticity is excluded, a base material comprising a fabric support layer, an adhesive layer, and an aluminum foil is employed, and an adhesive layer composed of a cured product of a butyl rubber-based adhesive composition exhibiting a predetermined storage elastic modulus is formed on the base material.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a pressure-sensitive adhesive tape having a butyl rubber-based pressure-sensitive adhesive layer. More specifically, the present invention relates to a pressure-sensitive adhesive tape having a butyl rubber-based pressure-sensitive adhesive layer, which is easily torn by hand and can be used to connect pipe insulation materials (insulation material connecting tape). [Background technology]

[0002] Buildings, such as buildings and factories, are equipped with pipes for transporting heat transfer fluids for air conditioning systems. To prevent energy loss from the heat transfer fluid flowing inside the pipes, the pipes are surrounded by annular foam pipe insulation made from expanded polyolefin (e.g., polyethylene). When installing pipes, the pipes must be connected together, but the pipe insulation pieces must also be connected together. A commonly used method for connecting pipe insulation pieces is to use insulation connection tape. With this method, multiple pipe insulation pieces are first fitted into the pipes, and then the ends of adjacent pieces are butted together. Tape is then wrapped around the outer periphery of the butt joints to connect and secure them. After joining and connecting multiple pipe insulation pieces together in this manner, protective or decorative tape is wrapped around the pipe insulation pieces in a spiral to prevent the outer surface of the pipe insulation pieces from being exposed. The surface of pipe insulation is often embossed to provide a textured surface, taking into consideration the ease of wrapping the decorative tape or protective tape (often non-adhesive) around the pipe insulation in a spiral shape, so that the tape can be wrapped securely without slipping. Note that the pipe insulation is not adhered to the pipe, but can be slid over the outer surface of the pipe.

[0003] Such foamed polyolefin insulation repeatedly expands and contracts depending on temperature during long-term use. As a result, as it deteriorates over time, it may remain in a thermally shrunk state. As a result, depending on the performance of the insulation splicing tape, gaps may appear at the joints where the insulation pieces are butted together. Unless the insulation splicing tape itself has exceptional insulating and moisture-proofing properties, even if the resulting gap appears to be covered by the splicing tape, the pipes will inevitably be exposed to the outside air. This can lead to condensation due to the temperature difference between the heat transfer medium flowing through the pipes and the ambient temperature. If this condensation turns into droplets and adheres to the pipes, it can cause deterioration of the pipes and the building. Furthermore, these gaps can reduce the insulation effect and increase energy loss. Therefore, at the connection points where the end faces of adjacent pipe insulation materials are butted together, it is necessary to firmly bond, fix, and maintain the adjacent pipe insulation materials together using insulation material connection tape to prevent the above-mentioned gaps from occurring over the long term.

[0004] Conventionally, vinyl tape has been used to connect pipe insulation, but the tape's fixing strength is weak, so it is necessary to wrap it multiple times, which has the drawback of taking a long time to connect. In addition, the number of times the tape is wrapped varies depending on the worker, and if the number of times it is wrapped is insufficient, the connection will peel off over time due to insufficient fixing strength. "Tapes using soft butyl-based adhesives have also been used, focusing on their ability to conform to the unevenness (embossed areas) on the surface of insulation and their airtightness. However, because they were designed specifically for airtightness, they were not heat-resistant enough, and when the temperature of the pipe or the ambient temperature rose, they softened, hindering the ability to maintain connections. As a result, they could not withstand the repeated expansion and contraction of the insulation due to heat, as mentioned above, and gaps could appear in the connections. Furthermore, when the butyl rubber adhesive was touched during work, black powder would fall off, staining the hands black and accidentally soiling the installation area."

[0005] Patent Document 1 discloses a connecting tape that employs a tape substrate that is made of a metal foil such as aluminum foil and a reinforcing layer such as glass cloth only in the center of the width of the metal foil. It also describes that an acrylic adhesive is preferably used for the adhesive layer, and that the thickness is 30 to 50 μm. From this patent document, it is inferred that butyl rubber, which softens at high temperatures, is not suitable for use in the adhesive layer.

[0006] The tape in Patent Document 1 uses a metal foil tape substrate to allow it to conform to the uneven surface of the pipe insulation. However, because the tape is easily deformed, it is prone to wrinkling when the insulation is wrapped around it. Wrinkles in the applied tape reduce adhesion to the insulation, preventing sufficient fixing strength and potentially leading to gaps at the connection over time. Furthermore, gaps between the tape and the insulation in wrinkled areas may reduce the insulation effectiveness. Therefore, the tape wrapping process must be performed carefully and meticulously, and is significantly affected by the skill of the worker. Furthermore, because the tape substrate has a reinforcing layer, such as a filament made of glass cloth or glass fiber, in the center of the width of the tape substrate, the tape cannot be torn by hand and must be cut with scissors, posing workability challenges. Furthermore, with this connection tape, the tape substrate needs to be wrapped around the connection point of the insulation to tighten the insulation to a certain extent in order to fit the tape substrate into the recesses of the uneven outer surface of the insulation. This means that the insulation becomes slightly thinner at the connection point, potentially reducing its insulation effectiveness.

[0007] Patent Document 2 solves the problem of reduced thermal insulation in Patent Document 1, and discloses a tape for pipe insulation covers, which comprises a tape substrate formed of a deformable fiber-reinforced metal foil, an insulating sheet bonded to the tape substrate and capable of stretching in the thickness direction, an adhesive layer provided on the side of the insulating sheet opposite the tape substrate, a release sheet tape substrate 1 covering the adhesive layer, an insulating sheet, an insulating sheet 3, and a release sheet 4 covering the first adhesive layer 3.

[0008] In Patent Document 2, a foamed polyolefin sheet is used to allow the tape to conform to the uneven surface of the pipe insulation, but because the adhesive layer that contributes to adhesion to the insulation is thin, the tape does not conform sufficiently to insulation with deep unevenness, and if the foamed polyolefin sheet is particularly thick, gaps may occur at the connection unless the tape is pressed sufficiently into the uneven surface of the pipe insulation. Also, to give the tape an insulating effect, a soft foamed resin sheet such as a foamed polyolefin sheet with a thickness of 1 mm to 3 mm is laminated, but this makes the tape difficult to tear by hand, and to achieve a good finished appearance, it is still necessary to cut it with scissors or something similar, which poses a problem in workability.

[0009] Patent Document 3 provides an adhesive tape that has strong adhesive strength between the metal foil and the substrate, the metal foil layer does not peel off when the tape is pulled out for use, has excellent water resistance, and is easily torn by hand.The adhesive tape discloses an adhesive tape in which an adhesive layer is provided on a laminate formed by laminating a metal foil layer on the adhesive layer surface of a laminate film formed by co-extrusion of a substrate layer made of a woven fabric or soft polyolefin flat yarn and an adhesive layer containing a linear ethylene-α-olefin copolymer.

[0010] In Patent Document 3, the hand tearability of the tape is improved by using the tape configuration as described above. However, when applying the adhesive solution dissolved in an organic solvent, the thickness of the adhesive layer after drying is set to 10 to 50 μm for acrylic adhesives and 80 to 150 μm for rubber adhesives. In the examples, the acrylic adhesive has a solid content of 30 g / m 2 However, this thickness was not sufficient to conform to the uneven surface of the pipe insulation, and there was a problem with the fixing strength when used to connect pipe insulation. As a result, it could not withstand the repeated expansion and contraction of the insulation as described above, and there was a risk of gaps occurring at the connection, so there was still room for improvement. [Prior art documents] [Patent documents]

[0011] [Patent Document 1] JP 2013-53214 A (Patent No. 5560512 Specification) [Patent Document 2] Patent No. 5425332 specification [Patent Document 3] JP 2003-183603 A (Patent No. 3905372) Summary of the Invention [Problem to be solved by the invention]

[0012] Therefore, an object of the present invention is to provide an adhesive tape for connecting pipe insulation materials that is easy to tear by hand and can firmly bond, fix, and maintain pipe insulation materials that repeatedly expand and contract depending on the temperature of the heat medium inside the pipe and the ambient temperature. [Means for solving the problem]

[0013] In order to achieve the above object, a substrate including a fabric support layer, an adhesive layer, and aluminum foil and a storage modulus of 1.0 × 10 at -10 °C measured at a frequency of 0.1 Hz are 6 Pa or more 1.8×10 6 We have developed an adhesive tape having a cross-linked butyl rubber adhesive layer characterized by a compressive strength of 100 MPa or less.

[0014] The storage modulus of the adhesive layer at 60°C measured at a frequency of 0.1 Hz was 7.0 × 10 4 Pa or more 9.0×10 4 It is suitable that the saturation is less than 1 Pa.

[0015] It was also found that the thickness of the adhesive layer must be at least 200 μm, preferably 300 μm, in order for it to fully penetrate into the uneven recesses (depth of recess: approximately 1 to 1.5 mm) on the surface of a typical pipe insulation material.

[0016] More specifically, the present invention provides the following pressure-sensitive adhesive tape. (1) A substrate including a fabric support layer, an adhesive layer, and an aluminum foil, and an adhesive layer including butyl rubber, a crosslinking agent, and a softener, The storage modulus (G') of the adhesive layer at -10°C measured at a frequency of 0.1 Hz is 1.0 x 10 6 Pa or more 1.8×10 6 An adhesive tape characterized by a tensile strength of 100 Pa or less. (2) The storage modulus (G') of the pressure-sensitive adhesive layer at 60°C measured at a frequency of 0.1 Hz is 7.0 × 10 4 Pa or more 9.0×10 4 The pressure-sensitive adhesive tape according to item (1) above, wherein the compressive strength is 100 Pa or less. (3) The adhesive tape according to (1) or (2) above, wherein the adhesive layer has a thickness of 300 μm or more. (4) The pressure-sensitive adhesive tape according to any one of the preceding items (1) to (3), characterized in that the cross-linking agent contained in the pressure-sensitive adhesive layer is a dinitroso compound, and the amount of the cross-linking agent added is 0.35 parts by mass or more and 1.10 parts by mass or less per 100 parts by mass of the butyl rubber. (5) The pressure-sensitive adhesive tape according to any one of (1) to (4) above, wherein the pressure-sensitive adhesive layer further contains a thiazole compound as a cross-linking accelerator. (6) The kinematic viscosity of the softener at 40°C is 20mm 2 / s or more 100mm 2 / s or less, and the amount of the rubber component containing the butyl rubber is 40 parts by mass or more and 70 parts by mass or less per 100 parts by mass of the total amount of the rubber components including the butyl rubber. (7) The pressure-sensitive adhesive tape according to any one of the above items (1) to (6), which is used for connecting pipe insulation materials. [Effects of the Invention]

[0017] The adhesive tape of the present invention does not use a foamed polyolefin sheet that has heat-retaining and stretchable properties, but instead uses a substrate that includes a cloth-like support layer, an adhesive layer, and aluminum foil, making it easy to tear by hand and improving the work efficiency of pipe installation.In addition, since it has an adhesive layer that exhibits a predetermined storage modulus, it has high adhesion to foamed polyolefin pipe insulation, and no gaps are created at the butt joints of the pipe insulation, so there is no reduction in insulation efficiency. [Brief explanation of the drawings]

[0018] [Figure 1] FIG. 1 is a schematic diagram illustrating a method for measuring storage modulus. [Figure 2] FIG. 1 is a schematic diagram illustrating a method for measuring shear adhesive strength to a thermal insulating material. [Figure 3] FIG. 1 is a schematic diagram illustrating an evaluation method for a peeling test. [Figure 4] FIG. 2 is a schematic diagram illustrating a method for measuring moisture permeability. DETAILED DESCRIPTION OF THE INVENTION

[0019] The pressure-sensitive adhesive tape of the present invention comprises a substrate including a fabric support layer, an adhesive layer, and an aluminum foil, and a pressure-sensitive adhesive layer including butyl rubber, a crosslinking agent, and a softener. In particular, the pressure-sensitive adhesive tape of the present invention has a storage modulus (G') of the pressure-sensitive adhesive layer at -10°C measured at a frequency of 0.1 Hz of 1.0 x 10 6 Pa or more 1.8×10 6 Pa or less.

[0020] [Base material] In order to improve the work efficiency of pipe insulation, the inventors of the present invention have focused on ease of hand tearing and have eliminated foamed polyolefin sheets, which have heat retention properties and stretchability in the thickness direction (cushioning properties), from the substrate structure. Specifically, the substrate of the pressure-sensitive adhesive tape of the present invention includes a fabric support layer, an adhesive layer, and aluminum foil. Specifically, a laminate composed of, for example, a first laminate layer / aluminum foil / adhesive layer / fabric support layer / second laminate layer (adhesive layer side) is preferably used as the substrate. The interfaces of each layer are optionally treated to improve adhesion, such as by corona treatment, plasma treatment, or application of an anchor coating agent. The fabric support layer, adhesive layer, aluminum foil, and laminate layer are described below.

[0021] <Fabric support layer> The fabric support layer is not particularly limited, but from the viewpoints of the ease of hand-tear of the adhesive tape and its ability to conform to the irregularities on the surface of the insulating material, a woven fabric (such as staple fiber or resin cloth) woven using filaments made of recycled fibers, thermoplastic resin, etc. as warp and weft yarns is preferably used. The fabric support layer may also be a cross-bonded fabric (soft cloth) in which filaments made of thermoplastic resin are cross-bonded as warp and weft yarns or as warp and both diagonal yarns.

[0022] The material of the filaments constituting the cloth-like body is not particularly limited, and examples thereof include natural fibers such as cotton and hemp, regenerated fibers such as rayon and cupra, and thermoplastic resins. Examples of such thermoplastic resins include olefin polymers such as high-density polyethylene, linear low-density polyethylene, polypropylene, and ethylene-propylene block copolymers, polyesters such as polyethylene terephthalate and polybutylene terephthalate, polyamides such as nylon 6 and nylon 66, polyacrylic resins, and vinylidene chloride resins. Of these, olefin polymers are preferably used.

[0023] The shape of the filament may be any selected from monofilament, tape, yarn, split yarn, multifilament, staple fiber, etc., among which a tape-shaped flat yarn is preferred. Such a flat yarn can also be made into a split yarn by making many small cuts in the longitudinal direction (machine direction).

[0024] The filament may be unstretched, but is preferably stretched. The stretching may be either uniaxial or biaxial.

[0025] The yarn density of the woven fabric support layer is not particularly limited, and the yarn density of the warp yarns (threads running along the length of the adhesive tape) is preferably in the range of 10 / 25.4 mm to 80 / 25.4 mm, more preferably 20 / 25.4 mm to 60 / 25.4 mm, and particularly preferably 25 / 25.4 mm to 50 / 25.4 mm. The yarn density of the weft yarns (threads running along the width of the adhesive tape) is preferably in the range of 5 / 25.4 mm to 40 / 25.4 mm, more preferably 10 / 25.4 mm to 30 / 25.4 mm, and particularly preferably 15 / 25.4 mm to 25 / 25.4 mm.

[0026] The average fineness of the woven fabric support layer is not particularly limited, but the average fineness of the warp yarns is preferably in the range of 50 dt to 1,000 dt, more preferably 50 dt to 250 dt, and particularly preferably 60 dt to 150 dt. The average fineness of the weft yarns is preferably in the range of 50 dt to 1,000 dt, more preferably 200 dt to 400 dt, and particularly preferably 250 dt to 360 dt.

[0027] Furthermore, from the viewpoint of achieving both maintaining the tensile strength of the adhesive tape and improving its hand-tearability, it is preferable that the woven cloth support layer is formed so that the number of warp threads is greater than the number of weft threads, and the average fineness of the warp threads is smaller than the average fineness of the weft threads.

[0028] The thickness of the fabric support layer is not particularly limited, but is preferably in the range of 8 μm to 400 μm, more preferably 15 μm to 200 μm, and particularly preferably 20 μm to 100 μm. The filaments that make up the fabric may be blended with lubricants, antiblocking agents, stabilizers, antioxidants, antistatic agents, antifogging agents, colorants, and other additives.

[0029] <Aluminum foil> In the substrate of the adhesive tape of the present invention, aluminum foil is laminated to the cloth-like support layer via an adhesive layer to impart appropriate rigidity to the adhesive tape. Aluminum foil is a suitable metal layer because it has appropriate rigidity while also having deformation-following properties and hand-tearability. As the aluminum foil, either soft aluminum foil or hard aluminum foil may be used, but from the viewpoint of the balance of the above-mentioned performance, it is preferable to use soft aluminum foil.

[0030] The thickness of the aluminum foil can be selected arbitrarily depending on the purpose. However, from the viewpoints of preventing pinholes, strength, processability, handleability, and hand-tearability of the aluminum foil, the thickness is preferably in the range of 5 μm to 70 μm, more preferably 5 μm to 50 μm, and particularly preferably 6 μm to 30 μm.

[0031] <Adhesive layer> The adhesive layer material used to bond the fabric support layer and aluminum foil is not particularly limited, but examples include olefin polymers such as low-density polyethylene, linear low-density polyethylene, high-density polyethylene, ethylene-α-olefin copolymers such as ethylene-propylene copolymer, ethylene-vinyl acetate copolymer, and polypropylene; polyesters such as polyethylene terephthalate and polybutylene terephthalate; polyamides such as nylon 6 and nylon 66; polyvinyl chloride; and thermoplastic resins such as polyurethane. Among these, olefin polymers are preferred from the viewpoint of adhesive strength between the aluminum foil and the fabric support layer, and resins containing low-density polyethylene, linear low-density polyethylene, or linear ethylene-α-olefin copolymer as an adhesive component are more preferred. Linear ethylene-α-olefin copolymers can be obtained by copolymerizing ethylene with an α-olefin having 3 to 12 carbon atoms using a metallocene catalyst or the like.

[0032] The lamination of the fabric support layer and the aluminum foil can be carried out by a method known per se using the adhesive layer material. Specific examples include a method in which the fabric support layer and the aluminum foil are prepared in advance, and an adhesive layer material such as an olefin polymer is melt-extruded into a film between the fabric support layer and the aluminum foil, and the three layers are simultaneously pressure-laminated to form a laminate, and a method in which a laminate film formed by melt-extruding an adhesive layer material onto the fabric support is bonded to the aluminum foil by thermocompression bonding.

[0033] Furthermore, when laminating the fabric support layer and aluminum foil via an adhesive layer, it is desirable from the standpoint of adhesion to pretreat the joint surface between the extruded adhesive material and the fabric support layer, or the joint surface between the extruded adhesive material and the aluminum foil, with ozone in a temperature range of 190°C or higher and 320°C or lower, preferably 190°C or higher and 300°C or lower.

[0034] The thickness of the adhesive layer is not particularly limited, but is preferably in the range of 10 μm or more and 60 μm or less, and more preferably in the range of 15 μm or more and 40 μm or less.

[0035] <Laminate layer> On the outside of the laminate consisting of the aluminum foil / adhesive layer / fabric support layer, a laminate layer is preferably provided on the side opposite the adhesive layer of the aluminum foil and / or the side opposite the adhesive layer of the fabric support layer for the purposes of protecting the aluminum foil, improving the hand-tearability of the adhesive tape, ensuring the tensile strength of the adhesive tape, or providing additional functions such as coloring the adhesive tape. From the perspective of suppressing curling of the adhesive tape and improving hand-tearability (preventing misalignment of the warp and weft yarns when torn), it is more preferable to provide the laminate layer on both the side opposite the adhesive layer of the aluminum foil and the side opposite the adhesive layer of the fabric support layer. In this case, it is preferable that both laminate layers are made of the same material.

[0036] The material of the laminate layer is not particularly limited as long as it is a thermoplastic resin, and the same materials as those used for the laminate layer of known pressure-sensitive adhesive tapes can be used. Specific examples include thermoplastic resins such as olefin polymers such as low-density polyethylene, linear low-density polyethylene, high-density polyethylene, ethylene-α-olefin copolymers such as ethylene-propylene copolymers, ethylene-vinyl acetate copolymers, and polypropylene; polyesters such as polyethylene terephthalate and polybutylene terephthalate; polyamides such as nylon 6 and nylon 66; polyvinyl chloride; and polyurethane. Among these, when hand-tearability is important, it is preferable to use low-density polyethylene or linear low-density polyethylene among the olefin polymers.

[0037] Methods for providing the laminate layer include a method in which a laminate consisting of an aluminum foil / adhesive layer / cloth-like body support layer is obtained, and then the material resin of the laminate layer is extrusion laminated, with or without an adhesive, to form the laminate layer on a predetermined surface; a method in which the fabric upper body support layer / adhesive layer is extrusion laminated onto the aluminum foil, and then a layer of the material resin of the laminate layer is co-extruded onto the outside of the cloth-like body support layer; and a method in which, when the cloth-like body support layer and aluminum foil are prepared in advance, the material resin of the laminate layer is extrusion laminated onto a predetermined surface to form a pre-laminated laminate.

[0038] The thickness of the laminate layer is not particularly limited, but from the viewpoint of improving the flexibility (softness) and ease of hand tearing of the adhesive tape, it is usually preferably in the range of 10 μm or more and 60 μm or less, more preferably in the range of 15 μm or more and 40 μm or less.

[0039] [Adhesive layer] The adhesive layer used in the pressure-sensitive adhesive tape of the present invention is a cured product layer composed of a cured product of a butyl rubber-based adhesive composition (hereinafter sometimes simply referred to as the adhesive composition) containing butyl rubber, a crosslinking agent, and a softener. The butyl rubber-based adhesive composition can be easily converted into a solventless adhesive (solid adhesive) by heat kneading using a kneader such as a pressure kneader, and the solventless adhesive composition can be formed directly onto a substrate as an adhesive layer by heat coating using a coater such as a calendar. Therefore, thick adhesive layer coating is possible, which is difficult with solvent-based acrylic adhesive compositions, which tend to generate foam due to solvent removal during adhesive layer formation. For example, a homogeneous adhesive layer having a thickness of 250 μm or more can be easily formed. Therefore, the solventless butyl rubber-based adhesive composition can be a suitable adhesive layer for the pressure-sensitive adhesive tape of the present invention, particularly for a connecting tape for insulating materials having an uneven surface, from the perspective of its ability to conform to unevenness. Such a butyl rubber-based pressure-sensitive adhesive composition contains, for example, regular butyl rubber or recycled butyl rubber, a crosslinking agent, a softener, and, if necessary, optional components such as a crosslinking accelerator, a tackifying resin, a filler, and other additives.

[0040] The adhesive layer containing the butyl rubber, the crosslinking agent, and the softener has a storage modulus (G') of 1.0 x 10 at -10°C measured at a frequency of 0.1 Hz. 6 Pa or more 1.8×10 6 Pa or less. That is, in an adhesive tape used to connect pipe insulation materials that repeatedly expand and contract depending on the temperature of the heat transfer medium in the pipe and the ambient temperature, stress accompanying the contraction and expansion of the insulation material is slowly and repeatedly applied mainly in the plane direction of the adhesive layer during long-term use. Therefore, the present inventors have considered that in order for an insulation material joining tape to firmly fix and maintain insulation materials together over a long period of time (to increase the shear adhesive strength), the adhesive layer must have (1) a sufficiently large cohesive strength (shear strength) and (2) a strong interfacial adhesive strength (peel strength) to the insulation material, which are capable of withstanding the shear stress slowly and repeatedly applied in the plane direction. As a result of extensive investigation, the inventors have adopted the "storage tank elastic modulus" measured in shear mode as a specific index of the physical properties of the adhesive layer to satisfy the required characteristics (1) and (2), and have determined that the storage modulus (G') at -10°C, measured at a frequency of 0.1 Hz, of an adhesive layer containing butyl rubber, a crosslinking agent, and a softener, is 1.0 × 10 6 Pa or more 1.8×10 6 It has been found that if the shear strength is in the range of 100 Pa or less, the adhesive layer will have an excellent balance of shear strength and peel strength, and will be able to firmly fix and maintain the heat insulating materials together over long periods of use. Here, a lower sine wave frequency when measuring the storage modulus will reproduce the very slow expansion and contraction behavior of actual heat insulating materials, so in the present invention, the frequency of the sine wave applied when measuring the storage modulus in shear mode was set to 0.1 Hz.

[0041] The adhesive layer has a storage modulus (G') of 1.0 x 10 at -10°C measured at a frequency of 0.1 Hz. 6 If the adhesive strength is less than 1.8 × 10 Pa, the adhesive layer will have insufficient cohesive strength, and if the adhesive layer is particularly thick, the adhesive tape may peel off from the insulation material due to the inability to withstand the shear force applied slowly and repeatedly in the surface direction during long-term use. 6If the pressure-sensitive adhesive layer exceeds Pa, the adhesive layer will become too hard, and if the adhesive layer is particularly thin, it will not be able to fully penetrate into the recesses of the uneven surface of the insulation, reducing the anchoring effect and interfacial adhesive strength, and the adhesive tape may not be able to withstand the shear force that is slowly and repeatedly applied in the surface direction during long-term use, causing it to peel off from the insulation. Also, if the adhesive layer becomes too hard, the shear force that is slowly and repeatedly applied in the surface direction during long-term use will not be alleviated and will concentrate at the adhesive interface, causing the adhesive tape to peel off from the insulation.

[0042] The adhesive layer has a storage modulus (G') of 7.0 x 10 at 60°C measured at a frequency of 0.1 Hz. 4 Pa or more 9.0×10 4 The pressure-sensitive adhesive layer preferably has a storage modulus (G') of 7.2 × 10 Pa or less at 60°C when measured at a frequency of 0.1 Hz. 4 If the adhesive strength is less than 9.0 × 10 Pa, the adhesive layer will have insufficient cohesive strength, and if the adhesive layer is particularly thick, the adhesive tape may peel off from the insulating material due to the inability to withstand the shear force applied slowly and repeatedly in the surface direction during long-term use. 4 If the pressure-sensitive adhesive layer exceeds this value, the adhesive layer will become too hard, and if it is particularly thin, it will not be able to fully penetrate into the recesses of the uneven surface of the insulation, reducing the anchoring effect and interfacial adhesive strength, and the adhesive tape may peel off from the insulation because it cannot withstand the shear force that is slowly and repeatedly applied in the surface direction during long-term use.Furthermore, if the adhesive layer becomes too hard, the shear force that is slowly and repeatedly applied in the surface direction will not be alleviated and will concentrate at the adhesive interface, causing the adhesive tape to peel off from the insulation.

[0043] The adhesive layer of the adhesive tape of the present invention contains butyl rubber as the rubber component of its adhesive composition. The butyl rubber is a copolymer (isobutylene-isoprene rubber) of isobutene (isobutylene) and a small amount of isoprene, and preferably has an isoprene content (unsaturation) of 0.3 mol% to 3.0 mol%. The type of butyl rubber is not particularly limited, and examples include synthetic butyl rubber (regular butyl rubber) and recycled butyl rubber. These butyl rubbers can be used alone or in combination with different types. From the perspective of preventing accidental staining during work, it is preferable to use synthetic butyl rubber (regular butyl rubber) rather than black recycled butyl rubber.

[0044] Mooney viscosity ML of the above butyl rubber (1+8) There are no particular limitations on 125°C, but it is preferably in the range of 25 to 90°C, more preferably 30 to 60°C.

[0045] The pressure-sensitive adhesive layer may contain rubber components other than butyl rubber as part of the pressure-sensitive adhesive composition, provided that the effects of the present invention are not impaired. Examples of such rubber components include polyisobutylene, acrylic rubber, silicone rubber, urethane rubber, vinyl alkyl ether rubber, polyvinyl alcohol rubber, polyvinylpyrrolidone rubber, polyacrylamide rubber, cellulose rubber, natural rubber, butadiene rubber, chloroprene rubber, styrene-butadiene rubber, acrylonitrile-butadiene rubber, styrene-ethylene-butadiene-styrene rubber, styrene-isoprene-styrene rubber, polyisoprene rubber, styrene-butadiene-styrene rubber, and ethylene-propylene rubber. Preferred examples of rubber components other than butyl rubber include polyisoprene rubber and polyisobutylene.

[0046] The blending ratio of the butyl rubber is, for example, preferably 70% by mass or more, more preferably 80% by mass to 100% by mass, even more preferably 90% by mass to 100% by mass, and most preferably 100% by mass, i.e., the entire rubber component is butyl rubber. If the blending ratio of the butyl rubber is within the above range, the adhesive layer will have an excellent balance of shear strength and peel strength, and will be able to firmly fix and maintain the heat insulating materials together over long periods of use.

[0047] The proportion of the total amount of rubber components including butyl rubber in the pressure-sensitive adhesive composition is preferably 10% by mass or more and 50% by mass or less, and more preferably 15% by mass or more and 45% by mass or less.

[0048] The adhesive layer of the adhesive tape of the present invention contains a crosslinking agent as a component for crosslinking the butyl rubber to increase cohesive strength.

[0049] Examples of crosslinking agents for crosslinking the butyl rubber include crosslinking agents containing at least one selected from sulfur, sulfur-based compounds (sulfur donors), dinitroso compounds, quinone dioxime compounds, bismaleimide compounds, and resin-based crosslinking agents. Examples of the sulfur-based compounds include sulfur; and thiuram compounds such as tetramethylthiuram monosulfide, tetramethylthiuram disulfide, activated tetramethylthiuram disulfide, tetraethylthiuram disulfide, tetrabutylthiuram monosulfide, tetrabutylthiuram disulfide, N,N'-dimethyl-N,N'-diphenylthiuram disulfide, dipentamethylenethiuram monosulfide, dipentamethylenethiuram disulfide, dipentamethylenethiuram tetrasulfide, dipentamethylenethiuram hexasulfide, dicyclopentamethylenethiuram disulfide, mixed alkylthiuram disulfides, and tetrabenzylthiuram disulfide. Examples of dinitroso compounds include poly-p-dinitrosobenzene and dinitrosobenzene, and examples of quinone dioxime compounds include p-quinone dioxime and p,p'-dibenzoylquinone dioxime. Examples of bismaleimide compounds include N,N'-m-phenylenedimaleimide, N,N'-p-phenylenedimaleimide, and N,N'-ethylenedimaleimide. Examples of resin-based crosslinking agents include alkylphenol resin oligomers. Among these, dinitroso compounds are preferred as crosslinking agents from the viewpoints of being able to crosslink at lower temperatures and in shorter times, improving the cohesive force (shear strength) of the adhesive layer, and being environmentally friendly.

[0050] The amount of the crosslinking agent added is set so that the storage modulus (G') at -10°C measured at a frequency of 0.1 Hz of the adhesive layer containing the butyl rubber, the crosslinking agent described below, and the softener is 1.0 x 10 6 Pa or more 1.8×10 6The crosslinking agent may be appropriately adjusted to a range of 0.35 to 1.10 parts by mass per 100 parts by mass of butyl rubber. The crosslinking agent may be, for example, a dinitroso compound. The crosslinking agent may be, for example, a dinitroso compound added in an amount of 0.35 to 1.10 parts by mass per 100 parts by mass of butyl rubber. The crosslinking agent may be, for example, a dinitroso compound added in an amount of 0.35 to 1.05 parts by mass, more preferably, 0.63 to 0.88 parts by mass. If the crosslinking agent is added in an amount of less than 0.35 parts by mass, the adhesive layer may not be sufficiently improved in cohesion. In particular, if the adhesive layer is thick, the adhesive tape may peel off from the insulating material due to insufficient shear force applied slowly and repeatedly in the surface direction during long-term use. On the other hand, if the crosslinking agent is added in an amount of more than 1.10 parts by mass, the adhesive layer may become too hard. In particular, if the adhesive layer is thin, the adhesive layer may not be able to fully penetrate the recesses of the uneven surface of the insulating material, resulting in a reduced anchoring effect and a reduced interfacial adhesion. Consequently, the adhesive tape may peel off from the insulating material due to insufficient shear force applied slowly and repeatedly in the surface direction during long-term use. Furthermore, if the adhesive layer becomes too hard, the shear stress slowly and repeatedly applied in the surface direction during long-term use may not be alleviated and may concentrate at the adhesive interface, resulting in peeling of the adhesive tape from the insulating material. Furthermore, the crosslink density may increase too much during kneading of the adhesive composition described below, causing the surface of the kneaded material to become rough and scorched, potentially resulting in poor processability during calendar coating. If the amount of crosslinking agent added is within the above-mentioned range, the adhesive composition will be sufficiently crosslinked and cured, imparting to the adhesive layer, i.e., the cured product layer, a sufficiently large cohesive force (shear strength) to withstand the shear stress slowly and repeatedly applied in the surface direction during long-term use. When an unsaturated rubber component having a double bond is blended as needed in addition to butyl rubber as a rubber component, the amount of the crosslinking agent (dinitroso compound) added is within the above-mentioned range per 100 parts by mass of the total amount of butyl rubber and unsaturated rubber components.

[0051] <Softener> The adhesive layer of the pressure-sensitive adhesive tape of the present invention contains a softener as a component of the adhesive composition. The softener is blended to impart excellent adhesive (bonding) properties to the adhesive layer over a wide temperature range (e.g., −10 to 60°C), i.e., to impart the adhesive layer with the minimum flexibility necessary to conform to the uneven surface of the heat insulating material while maintaining as much cohesive strength as possible, and to impart the minimum stress relaxation properties necessary to suppress stress concentration at the adhesive interface. Examples of suitable softeners include paraffinic process oil, naphthenic process oil, aromatic process oil, liquid polyisoprene, liquid polybutadiene, liquid styrene-butadiene rubber, liquid polybutene, and other liquid rubbers. These softeners can be used alone or in combination of two or more. Among these, from the viewpoint of ease of adjusting the balance between the cohesive strength and hardness of the adhesive layer, softeners containing at least one selected from naphthenic process oil, paraffinic process oil, and mixtures thereof (for example, a mixture of solvent-refined high-viscosity naphthene and hydrogenated medium-viscosity paraffin, etc.) are preferably used.

[0052] The kinematic viscosity of the softener at 40°C is not particularly limited, but may be, for example, 10 mm 2 / s or more 150mm 2 / s or less, and more preferably 20 mm 2 / s or more 100mm 2 The kinematic viscosity of the softener at 40°C is in the range of 10mm / s or less. 2 If the viscosity is less than 1 / s, particularly if the blending amount of the softener is large, the cohesive strength of the adhesive layer will not be maintained and will decrease, and the storage modulus (G') of the adhesive layer at 60°C measured at a frequency of 0.1 Hz may fall below the desired lower limit mentioned above. As a result, for example, at high temperatures (e.g., 60°C) or during long-term use, the shear adhesive strength to the heat insulating material may decrease, and the adhesive tape may peel off from the heat insulating material. On the other hand, if the kinematic viscosity of the softener at 40°C is 150 mm 2If the storage modulus (G') of the adhesive layer measured at a frequency of 0.1 Hz exceeds 1 / s, particularly if the amount of softener is small, the adhesive layer may not have the minimum required softness and stress relaxation properties, and the adhesive layer may have a storage modulus (G') at -10°C measured at a frequency of 0.1 Hz that exceeds the desired upper limit described above. As a result, for example, the shear adhesive strength to the insulating material may decrease at low temperatures (e.g., -10°C) or during long-term use, and the adhesive tape may peel off from the insulating material.

[0053] The kinematic viscosity of the softener is a value measured in accordance with JIS K2283 (2000), specifically, a value measured using a glass capillary viscometer. When multiple types of softeners with different kinematic viscosities are used in combination, the kinematic viscosity is a value measured as the kinematic viscosity of a mixture of those softeners.

[0054] Specific examples of the naphthenic process oil include Diana Process Oil NP-24 (main component: a mixture of solvent-refined high-viscosity naphthenes and solvent-refined low-viscosity naphthenes, kinematic viscosity at 40°C: 22.7 mmHg) manufactured by Idemitsu Kosan Co., Ltd. 2 / s), Diana Process Oil NS-28 (main component: solvent refined high viscosity naphthene, kinematic viscosity at 40°C: 28.1 mm 2 / s), Diana Process Oil NR-26 (main component: solvent refined high viscosity naphthene, kinematic viscosity at 40°C: 25.7 mm 2 / s) (all product names).

[0055] Specific examples of the paraffin-based process oil include Diana Process Oil PW-32 (main component: hydrogenated low-viscosity paraffin, kinematic viscosity at 40°C: 30.6 mmHg) manufactured by Idemitsu Kosan Co., Ltd. 2 / s), Diana Process Oil PW-90 (main component: hydrogenated medium viscosity paraffin, kinematic viscosity at 40°C: 90.5 mm 2 / s), Diana Process Oil PA-32 (main component: a mixture of solvent-refined medium viscosity paraffin and hydrogenated medium viscosity paraffin, kinematic viscosity at 40°C: 28.7 mm 2 / s) (all product names).

[0056] The mixed process oil of naphthenic process oil and paraffinic process oil is specifically Diana Process Oil NS-90S (a mixture of solvent-refined high-viscosity naphthene and hydrogenated medium-viscosity paraffin, kinematic viscosity at 40°C: 96.7 mm) manufactured by Idemitsu Kosan Co., Ltd. 2 / s), Diana Process Oil NS-100 (a mixture of solvent-refined high-viscosity naphthenes and hydrogenated medium-viscosity paraffins, kinematic viscosity at 40°C: 94.7 mm 2 / s) (all product names).

[0057] The amount of the softener added is preferably 40 to 70 parts by mass, more preferably 45 to 60 parts by mass, per 100 parts by mass of the total rubber component including butyl rubber. If the amount of the softener added is less than 40 parts by mass, particularly if the softener has a high kinematic viscosity at 40°C, the adhesive layer may not achieve the minimum required softness and stress relaxation properties, and the storage modulus (G') of the adhesive layer at -10°C measured at a frequency of 0.1 Hz may exceed the desired upper limit. As a result, for example, the shear adhesive strength to the insulating material may decrease at low temperatures (e.g., -10°C) or over long-term use, which may result in peeling of the adhesive tape from the insulating material or reduced tack, resulting in poor initial adhesion. On the other hand, if the softener content exceeds 70 parts by mass, particularly if the softener has a low kinematic viscosity at 40°C, the cohesive strength of the adhesive layer may not be maintained and may decrease, and the storage modulus (G') of the adhesive layer at 60°C measured at a frequency of 0.1 Hz may fall below the desired lower limit. As a result, for example, the shear adhesive strength to the insulating material may decrease at high temperatures (e.g., 60°C) or over long-term use, and the adhesive tape may peel off from the insulating material. By adjusting the amount of softener added within the above range, it is possible to impart to the adhesive layer the minimum softness that allows it to conform to the uneven surface of the insulating material while maintaining as much cohesive force as possible of the adhesive layer, and the minimum stress relaxation property that suppresses stress concentration at the adhesive interface.

[0058] The adhesive layer of the adhesive tape of the present invention may contain optional components other than the butyl rubber, crosslinking agent, and softener, such as a crosslinking accelerator, a tackifying resin, a filler, and other additives, in the adhesive composition thereof.

[0059] <Crosslinking accelerator> The pressure-sensitive adhesive layer of the present invention preferably contains a crosslinking accelerator as a catalyst for increasing the rate of crosslinking reaction by the crosslinking agent. Examples of such crosslinking accelerators include thiourea compounds such as diethylthiourea and trimethylthiourea; thiazole compounds such as 2-mercaptobenzothiazole, 2-(morpholinodithio)benzothiazole, and dibenzothiazyl disulfide; sulfenamide compounds such as N-cyclohexyl-2-benzothiazole sulfenamide and Nt-butyl-2-benzothiazole sulfenamide; thiuram compounds such as tetramethylthiuram disulfide and tetramethylthiuram monosulfide; dithiocarbamate compounds such as zinc dimethyldithiocarbamate; guanidine compounds such as diphenylguanidine; peroxides such as dicumyl peroxide; and halogen compounds such as zinc chloride. In addition to the crosslinking accelerator, the pressure-sensitive adhesive layer of the present invention may also contain a crosslinking accelerator auxiliary agent such as a metal oxide such as zinc oxide or a fatty acid such as stearic acid. Furthermore, in the case of a metal oxide such as zinc oxide, it is also possible to use only a crosslinking promoter for the metal oxide together with the crosslinking agent without using the crosslinking promoter.

[0060] The crosslinking accelerator may be appropriately selected depending on the crosslinking agent used, but for example, when a dinitroso compound suitable as the crosslinking agent is used, it is preferable to use a thiazole compound such as dibenzothiazyl disulfide as the crosslinking accelerator. When this crosslinking agent and a crosslinking accelerator are used in combination, crosslinking of the butyl rubber proceeds at a relatively low temperature in a short time, and deterioration of the butyl rubber over time is also reduced, so that an adhesive layer capable of stably maintaining good adhesive properties is provided.

[0061] The amount of the crosslinking accelerator added is not particularly limited. However, if the amount of crosslinking accelerator added is too high, its effect may saturate, and the adherend may be contaminated. Furthermore, when a release liner is attached to the pressure-sensitive adhesive layer, depending on the type of crosslinking accelerator, its bleed-out may cause the release liner to have a heavy release force. If the amount is too low, the effect of the crosslinking accelerator may not be fully exerted. The amount of crosslinking accelerator added is preferably 10.0 parts by mass or less, more preferably 0.1 to 8.0 parts by mass, even more preferably 0.2 to 5.0 parts by mass, and particularly preferably 0.3 to 1.0 parts by mass, per 100 parts by mass of butyl rubber. The amount of crosslinking accelerator added is not particularly limited. However, if the amount of crosslinking accelerator added is too high, its effect may saturate, and the adherend may be contaminated. Depending on the type of crosslinking accelerator, the butyl rubber may be deteriorated over time. If the amount is too low, the effect of the crosslinking accelerator added may not be fully exerted. The amount of the crosslinking accelerator added is preferably 50 parts by mass or less, more preferably 0.5 to 25.0 parts by mass, and even more preferably 1.0 to 10.0 parts by mass, per 100 parts by mass of butyl rubber.

[0062] <Tackifying resin> The tackifying resin is a component that is optionally added to improve the adhesive strength of the adhesive layer and to facilitate softening of the butyl rubber (and other rubber components that are added as needed) at high temperatures. Examples of the tackifying resin include petroleum-based resins (e.g., aliphatic (C5), alicyclic (DCPD), aromatic (C9), and aliphatic / aromatic copolymer (C5 / C9) hydrocarbon resins), terpene-based resins (e.g., terpene resins, aromatic-modified terpene resins, terpene phenolic resins, hydrogenated terpene phenolic resins, hydrogenated terpene resins, and hydrogenated aromatic-modified terpene resins), rosin-based resins (e.g., rosin esters, stabilized rosin esters, special rosin esters, disproportionated rosin, polymerized rosin, polymerized rosin esters, rosin-modified phenolic resins, modified rosin pentaerythritol esters, rosin-modified glycerin esters, rosin-modified maleic acid resins, rosin derivatives, hydrogenated rosin, ultra-light-colored rosin, and ultra-light-colored rosin esters), as well as various resins that are compatible with butyl rubber, such as coumarone-indene resins, styrene-based resins, and xylene-based resins, as well as hydrogenated versions of these resins. These tackifying resins can be used alone or in combination. Among these, petroleum-based resins are preferred as tackifier resins.

[0063] In order to ensure even better adhesive strength, the softening point of the tackifier resin is preferably in the range of 80°C or higher and 150°C or lower, more preferably in the range of 85°C or higher and 140°C or lower, even more preferably in the range of 90°C or higher and 130°C or lower, and particularly preferably in the range of 95°C or higher and 120°C.

[0064] The amount of the tackifier resin added is not particularly limited, but is preferably, for example, 10 parts by mass or more and 200 parts by mass or less, more preferably 20 parts by mass or more and 150 parts by mass or less, and even more preferably 30 parts by mass or more and 100 parts by mass or less, relative to 100 parts by mass of the total amount of the rubber components including the butyl rubber.

[0065] <Filler> The filler is a component that is optionally blended to reinforce the pressure-sensitive adhesive composition. Examples of the filler include, but are not limited to, inorganic fillers such as calcium carbonate (e.g., heavy calcium carbonate or light calcium carbonate), talc, titanium oxide, carbon black, silica, magnesium oxide, and organic fillers such as resins. These fillers can be used alone or in combination of two or more. Among these, calcium carbonate is preferred as the filler.

[0066] The average particle size of the filler is, for example, 0.001 μm or more and 10 μm or less, and the residue on a 350 mesh sieve measured in accordance with JIS K5101 is, for example, 10 mass% or less, preferably 5 mass% or less, and for example, 0.1 mass% or more.

[0067] The amount of the filler added is not particularly limited, but is, for example, in the range of 30 parts by mass or more and 500 parts by mass or less, preferably 50 parts by mass or more and 400 parts by mass or less, and more preferably 100 parts by mass or more and 300 parts by mass or less, relative to 100 parts by mass of the total amount of the rubber components including the butyl rubber.

[0068] Furthermore, in the adhesive layer of the adhesive tape of the present invention, other additives such as antioxidants, colorants and plasticizers may be added and blended in appropriate proportions to the adhesive composition, if necessary.

[0069] [Adhesive tape manufacturing method] The butyl rubber-based PSA composition described above can be obtained by blending the above-mentioned optional components in the above-mentioned proportions with the above-mentioned butyl rubber, crosslinking agent, and softener as essential ingredients, followed by heating and kneading to form a kneaded mixture. The method for producing the butyl rubber-based PSA composition is not particularly limited. In the present invention, the PSA composition is prepared by blending the components of the PSA composition stepwise using, for example, a batch-type kneading device such as a pressure kneader, Banbury mixer, or mixing roll, or a continuous kneading device such as a twin-screw kneader, and then kneading the mixture while heating without using any organic solvents or water. By kneading while heating in this manner, a uniform crosslinking reaction occurs between the butyl rubber polymer and the crosslinking agent, resulting in a PSA composition in which the butyl rubber polymers are appropriately crosslinked and cured via the crosslinking agent.

[0070] The above-mentioned production method is merely an example and is not intended to be limiting. For example, it is possible to prepare a pressure-sensitive adhesive composition by changing or adjusting the amounts of the components and the order of addition, or by using an appropriate organic solvent. When kneading under heat, the kneading temperature is appropriately selected, for example, within a temperature range of 80 to 200°C, preferably 85 to 170°C, depending on the formulation and batch amount of the pressure-sensitive adhesive composition, the capacity of the kneading device, etc. The kneading time is appropriately selected within a range of 3 to 60 minutes, preferably 4 to 30 minutes, depending on the kneading temperature, and the torque and kneading state during kneading are observed, with the end point of the torque increase after the addition of the crosslinking agent being determined as the end point of the crosslinking reaction.

[0071] The adhesive composition crosslinked by heat kneading in this way has good moldability and easily softens when heated, so that by applying this adhesive composition to a substrate having a laminate structure of laminate layer / aluminum foil / adhesive layer / resin cloth layer / laminate layer (adhesive layer side) using a calender roll or extruder, etc., an adhesive tape can be produced in which an adhesive layer (cured layer) consisting of a cured product of the adhesive composition is provided on the substrate. This production method does not use organic solvents that cause environmental pollution or water, which requires a great deal of energy for drying, so there is no need for a heating step in a drying oven after coating the substrate, making it environmentally friendly and significantly contributing to energy conservation.

[0072] The thickness of the adhesive layer is not particularly limited, and may be any thickness as long as it has the excellent shear adhesive strength required for connecting pipe insulation materials. From the viewpoint of conformability to the uneven surface of the insulation material, the thickness is, for example, 200 μm or more, preferably 300 μm or more, more preferably 400 μm or more. From the viewpoint of economy, the thickness is, for example, 1000 μm or less, preferably 700 μm or less, more preferably 500 μm or less. Since the adhesive tape of the present invention uses a substrate having the above-mentioned laminated structure as a substrate, if the substrate is particularly thick and the adhesive layer is thin, the flexibility may be somewhat insufficient, and the conformability to the uneven shape of the surface of the pipe insulation material may be insufficient, resulting in reduced interfacial adhesion. However, if the thickness of the adhesive layer is within the above range, even when the flexibility of the adhesive tape is somewhat insufficient, the adhesive layer can be deformed and brought into contact with the substrate along the surface of the recesses (depth of recesses: about 1 to 1.5 mm) of the uneven shape of the surface of a typical pipe insulation material, and the interfacial adhesion strength is sufficient due to the anchoring effect.

[0073] Furthermore, the surface of the laminate layer that forms the adhesive layer of the substrate can be subjected to a surface treatment such as corona discharge treatment or plasma treatment, or an undercoat layer can be provided, or both, as needed, to improve the adhesion of the adhesive layer to the substrate. Furthermore, a colored layer or a known release layer (peeling treatment layer) can be provided, as needed, on the surface of the laminate layer on the side opposite to the laminate layer that forms the adhesive layer of the substrate.

[0074] A release liner can also be provided on the surface of the adhesive layer formed on the surface of the laminate layer of the substrate. Examples of release liner substrates include plastic substrate sheets (synthetic resin sheets) such as polyester sheets (polyethylene terephthalate (PET) sheets, etc.), olefin resin sheets (polyethylene sheets, polypropylene sheets, etc.), polyvinyl chloride sheets, polyimide sheets, polyamide sheets (nylon sheets), and rayon sheets, as well as paper (high-quality paper, Japanese paper, kraft paper, glassine paper, synthetic paper, top-coated paper, etc.), and also include multilayered structures (e.g., two- or three-layer composites) formed by laminating or coextruding these materials. The release layer of the release liner is formed by applying a release agent to one side of the release liner substrate and drying it. Examples of such release agents include silicone-based release agents, fluorine-based release agents, and long-chain alkyl-based release agents.

[0075] [Adhesive tape] As mentioned above, the expansion and contraction of the foamed polyolefin sheet is very slow due to the temperature difference between the heat transfer medium flowing through the pipe and the ambient temperature, and seasonal temperature fluctuations. Therefore, the inventors adopted "shear adhesive strength" measured by a tensile test as an index for evaluating the adhesion between the heat insulating material, which slowly expands and contracts over long-term use, and the adhesive layer of the adhesive tape. In addition, since a slower pulling speed when measuring the shear adhesive strength can reproduce the very slow expansion and contraction behavior of the actual heat insulating material, the pulling speed in the present invention was set to 1 mm / min.

[0076] The shear adhesive strength of the pressure-sensitive adhesive tape of the present invention to a heat insulating material (the evaluation method is described in detail in the Examples) is, at 23° C., for example, 30 N or more, preferably 35 N or more, more preferably 40 N or more. At −10° C., it is, for example, 139 N or more, preferably 162 N or more, more preferably 170 N or more. Furthermore, at 60° C., it is, for example, 11 N or more, preferably 13 N or more, more preferably 15 N or more.

[0077] If the shear adhesive strength is equal to or greater than the above-mentioned value, the adhesive tape can firmly fix and maintain the heat insulating materials together over a long period of use, and the adhesive tape will not easily peel off from the heat insulating materials. Therefore, the heat insulating performance of the heat insulating materials can be maintained, and condensation will not occur.

[0078] The moisture permeability (evaluation method will be described in detail in the Examples) of the pressure-sensitive adhesive tape of the present invention is, for example, 0.4 g / 24 hr or less, and preferably 0.3 g / 24 hr or less.

[0079] If the moisture permeability is below the above value, the adhesive tape itself has adequate moisture-proofing properties, so as long as the adhesive tape is firmly fixed and maintained on the insulation, the phenomenon of condensation caused by localized exposure of the pipe to the outside air is greatly suppressed. Even if a small gap occurs in the connection where the insulation materials are butted together, extreme condensation is suppressed. [Example]

[0080] The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited to the following examples. In the following description, "parts" means "parts by mass."

[0081] [Example 1] <Preparation of Pressure-Sensitive Adhesive Composition> Butyl rubber (product name: Butyl 065, manufactured by Japan Butyl Co., Ltd., unsaturation level: 1.1 mol%, Mooney viscosity: ML (1+8)125°C: 32) 1,000g [100 parts by mass], calcium carbonate (product name: Tankal 325, manufactured by Yuko Mining Co., Ltd.) 800g [80 parts by mass], rutile-type titanium dioxide (product name: Typaque CR-50, manufactured by Ishihara Sangyo Co., Ltd., average particle size: 0.25μm) 125g [12.5 parts by mass], and crosslinking accelerator (product name: Noccela DM-P, manufactured by Ouchi Shinko Chemical Industry Co., Ltd., dibenzothiazyl disulfide) 5g [0.5 parts by mass] were added and kneaded for approximately 10 minutes. Next, 400 g (40 parts by mass) of calcium carbonate (Tancal 325), 700 g (70 parts by mass) of a tackifier resin (product name: Quinton (registered trademark) M100, manufactured by Zeon Corporation, softening point: 95°C, aliphatic hydrocarbon resin), and 14 g (1.4 parts by mass) of a crosslinking agent (product name: Valnoc DNB, manufactured by Ouchi Shinko Chemical Industry Co., Ltd., 25% dilution of poly-p-dinitrosobenzene) were added to the kneaded mixture, and the mixture was kneaded for approximately 10 minutes to perform crosslinking. Note that the addition of 1.4 parts by mass of Valnoc DNB corresponds to the addition of 0.35 parts by mass of the dinitroso compound poly-p-dinitrosobenzene. Finally, 950 g (95 parts by mass) of calcium carbonate (Tancal 325), 40 g (4 parts by mass) of antioxidant (product name: Chinox® 1010, manufactured by Chitec Chemical Co., Ltd., a phenolic antioxidant), and 480 g (48 parts by mass) of softener (product name: Diana Process Oil NS-90S, manufactured by Idemitsu Kosan Co., Ltd., a mixture of solvent-refined high-viscosity naphthene and hydrogenated medium-viscosity paraffin) were added to the above kneaded mixture in several batches, and the mixture was kneaded for approximately 10 minutes to prepare a butyl rubber-based pressure-sensitive adhesive composition. The composition of each material is shown in Table 1.

[0082] <Preparation of adhesive tape> First, a laminated substrate was prepared consisting of a colored layer (2 μm thick), a first laminate layer (20 μm thick), an aluminum foil (7 μm thick), an adhesive layer (20 μm thick), a resin cloth layer (43 μm thick), and a second laminate layer (20 μm thick). The materials of each layer are as follows: Colored layer: Ivory colored urethane resin First laminate layer: Low density polyethylene resin Aluminum foil: soft aluminum foil Adhesive layer: Linear ethylene-α-olefin copolymer Resin cloth layer: Flat yarn fabric woven with high density polyethylene flat yarn as warp thread (thread density: 46 threads / inch) and weft thread (thread density: 16 threads / inch) Second laminate layer: Low density polyethylene resin

[0083] Next, the pressure-sensitive adhesive composition prepared above was applied to the second laminate layer of the substrate prepared above at 100°C using a four-roll calender to produce a pressure-sensitive adhesive tape with a 400µm thick adhesive layer. The adhesive layer was applied to the substrate so that the warp direction of the resin cloth of the substrate was the application direction (MD). The surface of the second laminate layer of the substrate was previously subjected to a corona treatment to improve adhesion with the adhesive layer, and a release paper was attached to the surface of the adhesive layer.

[0084] [Examples 2 to 8, Comparative Examples 1 and 2] Pressure-sensitive adhesive compositions were prepared and pressure-sensitive adhesive tapes were fabricated in the same manner as in Example 1, except that the amount of crosslinking agent (Barnock DNB) [amount of poly-p-dinitrosobenzene] was changed to the amounts shown in Tables 1 and 2. The formulations of each material are shown in Tables 1 and 2.

[0085] [Examples 9 to 12] Except for changing the amount of softener (product name: Diana Process Oil NS-90S) to 40 parts by mass, 45 parts by mass, 60 parts by mass, and 70 parts by mass, pressure-sensitive adhesive compositions were prepared and pressure-sensitive adhesive tapes were fabricated in the same manner as in Example 5. The formulations of each material are shown in Table 2.

[0086] Comparative Example 3 Except for changing the blending amount of the crosslinking agent (Barnock DNB) to 4.2 parts by mass [blended amount of poly-p-dinitrosobenzene: 1.05 parts by mass] and the blending amount of the softener (product name: Diana Process Oil NS-90S) to 35 parts by mass, an adhesive composition was prepared and an adhesive tape was produced in the same manner as in Example 1. The blending amounts of each material are shown in Table 2.

[0087] Comparative Example 4 Except for changing the blending amount of the crosslinking agent (Barnock DNB) to 1.4 parts by mass [blended amount of poly-p-dinitrosobenzene: 0.35 parts by mass] and the blending amount of the softener (product name: Diana Process Oil NS-90S) to 70 parts by mass, an adhesive composition was prepared and an adhesive tape was fabricated in the same manner as in Example 1. The blending amounts of each material are shown in Table 2.

[0088] <Test Method> (1) Storage modulus Measurements were performed using a dynamic viscoelasticity measuring device (DMS6100, Hitachi High-Tech Science Corporation). Figure 1 shows a schematic diagram of the device. The butyl rubber-based pressure-sensitive adhesive composition prepared using the pressure kneader was sandwiched between two release liners (made of PET) and pressed at 70°C to produce a sheet of the pressure-sensitive adhesive composition (adhesive layer) approximately 1 mm thick. The resulting sheet was cut into a 10 mm x 10 mm measurement sample. The release liners were then peeled off from the measurement sample, and only the pressure-sensitive adhesive composition sheet (adhesive layer) was placed in the device. Dynamic viscoelasticity spectra were measured in shear mode over a specified temperature range, heating rate, and frequency (measurement temperature range: -20°C to 100°C, heating rate: 2°C / min, frequency: 0.1 Hz), and the storage modulus (G') [Pa] at -10°C and 60°C was determined.

[0089] (2) Measurement of shear adhesive strength to insulation As insulation material 1, a heat-resistant pipe cover (embossed round bar type) manufactured by Inaba Denki Sangyo Co., Ltd. (product model number: PME-38-20, compatible pipe outer diameter: 38.1 mm, wall thickness: 20 mm, material: insulation material / chemically cross-linked 30x expanded polyethylene, embossed surface film / polyethylene) was cut to a length of 100 mm. As shown in Figure 2, the ends of the two insulation materials were butted together, and a 25 mm-wide adhesive tape 2 was wrapped around the butted joint to connect the two insulation materials. This sample was placed in a tensile tester and left at 23 °C for 1 hour. The insulation material 1 was then pulled in the shear direction at a pulling rate of 1 mm / min. The maximum tensile load at which the adhesive tape peeled off was measured, and this value was taken as the shear adhesive strength [N] of the insulation material. The measurement results are shown in Table 1 or 2 together with the formulation.

[0090] (3) Peeling test of adhesive tape and insulation joints As insulation material 1, a heat-resistant pipe cover (round bar type with embossed skin) manufactured by Inaba Denki Sangyo Co., Ltd. (product model number: PME-38-20, compatible pipe outer diameter: 38.1 mm, wall thickness: 20 mm, material: insulation material part / chemically cross-linked 30x expanded polyethylene, embossed surface film part / polyethylene) was cut to a length of 600 mm, and as shown in Figure 3, two insulation materials 1 were passed through an aluminum pipe 3 with a pipe outer diameter of 38 mm, and the ends of each were butted together. A 25 mm wide adhesive tape 2 was wrapped around the butted joint once to connect the two insulation materials. Both ends of the butted insulation material were firmly fixed to the aluminum pipe 3 with cable ties 4. The sample was stored alternately at 0°C and 40°C for one hour each, and after this alternating storage at low and high temperatures (temperature shock) was repeated 10 times, the sample was visually inspected for peeling of the adhesive tape 2 and evaluated according to the following criteria, with ratings of A and B being deemed to be acceptable for practical use. A: No peeling was observed. B: Some peeling was observed on the edges of the tape, but no peeling was observed in the center of the tape (the joint where the two insulation materials were butt-jointed). C: Peeling was observed in the center of the tape (the joint where two pieces of insulation were butt-jointed). The observation results are shown in Table 1 or 2 along with the formulations.

[0091] (4) Hand tearability test of adhesive tape An adhesive tape measuring 300 mm in length and 100 mm in width was prepared, and the condition of the tape when torn by hand in the width direction (the weft direction of the resin cloth in the substrate) was observed to evaluate the hand-tearability of the adhesive tape. A rating of A was determined to be a level that is acceptable for practical use. A: I was able to easily cut it straight by hand. C: It was not easy to cut by hand.

[0092] (5) Moisture permeability of adhesive tape As the insulation material 1, a heat-resistant pipe cover (embossed round bar type) manufactured by Inaba Denki Sangyo Co., Ltd. (product model number: PME-38-20, compatible pipe outer diameter: 38.1 mm, wall thickness: 20 mm, material: insulation material / chemically cross-linked 30x expanded polyethylene, embossed surface film / polyethylene) was cut to a length of 25 mm. As shown in Figure 2, the end faces of the two insulation materials were butted together, and a 25 mm-wide adhesive tape 2 was wrapped around the butted joint to connect the two insulation materials. Then, a lid 5 was placed on the bottom side of the opening of the insulation material connected with the adhesive tape 2 and sealed. Next, 8 g of calcium chloride was placed inside the insulation material, and a lid 6 was placed on the top side of the opening of the insulation material to seal it. This was stored in a constant temperature bath at 40 °C and 90% RH for 24 hours, after which the weight of water vapor adsorbed by the calcium chloride was measured. The amount of water vapor adsorbed by calcium chloride over a 24-hour period was taken as a simple value for the moisture permeability (g / 24hr) of the adhesive tape tested.

[0093] [Table 1]

[0094] [Table 2]

[0095] As shown in Tables 1 and 2, the pressure-sensitive adhesive tapes of Examples 1 to 12, which satisfy the requirements of the present invention, have a shear adhesive strength of 30 N or more to a foamed polyethylene heat insulating material, and in a peeling test, no peeling was observed in the center part of the pressure-sensitive adhesive tape (the joint where two heat insulating materials are butted together). That is, the storage modulus (G') of the adhesive layer made of the cured product of the butyl rubber-based pressure-sensitive adhesive composition at -10°C measured at a frequency of 0.1 Hz was 1.0 x 10 6 Pa or more 1.8×10 6 It was confirmed that when the storage modulus (G') of the adhesive layer is in the range of 1.6 x 10 Pa or less (Examples 1 to 12), the adhesive layer has an excellent balance of shear strength and peel strength, and can firmly fix and maintain the heat insulating materials together over a long period of use. In particular, when the storage modulus (G') of the adhesive layer is 1.6 x 10 6Pa or more 1.7×10 6 When the adhesive strength was 35 N or less (Examples 4 to 6, 10 and 11), the shear adhesive strength to a foamed polyethylene heat insulating material was 35 N or more, and no peeling was observed in a peel test. It was also confirmed that the adhesive tapes of Examples 1 to 12 had good hand tearability and appropriate moisture resistance. Although not shown in the table, the shear adhesive strength to a heat insulating material was also measured at -10°C and 60°C in the same manner as at 23°C, and was found to be 181 N at -10°C and 21 N at 60°C.

[0096] In contrast, as shown in Table 2, the pressure-sensitive adhesive tapes of Comparative Examples 1 to 4, which do not satisfy the requirements of the present invention, had a shear adhesive strength of less than 30 N to a foamed polyethylene heat insulating material, and peeling was observed in the center part of the tape (the joint where two heat insulating materials were butt-jointed) in a peeling test, demonstrating that the adhesiveness was inferior to that of the pressure-sensitive adhesive tapes of Examples 1 to 12. Specifically, when the storage modulus (G') of the adhesive layer was 1.0 x 10 6 If the storage modulus (G') of the adhesive layer is less than 1.8 × 10 Pa (Comparative Examples 1 and 4), the adhesive layer is too soft to firmly fix and maintain the pipe insulation material, and the storage modulus (G') of the adhesive layer is 1.8 × 10 6 If the adhesive layer was greater than Pa (Comparative Examples 2 and 3), the adhesive layer was too hard, reducing the initial adhesiveness and stress relaxation properties to the pipe insulation material, and the pipe insulation material could not be firmly fixed or maintained. [Industrial Applicability]

[0097] According to the present invention, the adhesive tape is easy to tear by hand, improves the efficiency of pipe installation work, and has high adhesion to pipe insulation made of foamed polyolefin, so that the insulating efficiency of the pipe insulation itself is not reduced over long-term use. [Explanation of symbols]

[0098] 1...Insulation material, 2...adhesive tape, 3...Aluminum pipe, 4... Cable ties, 5...A sealing cover on the underside of the joined insulation material members, 6...Sealing cover on the top side of the joined insulation material parts

Claims

1. The adhesive tape comprises a substrate including a fabric support layer, an adhesive layer, and an aluminum foil, and an adhesive layer including butyl rubber, a crosslinking agent, and a softener, The storage modulus (G') of the pressure-sensitive adhesive layer at -10°C measured at a frequency of 0.1 Hz is 1.0 x 10 ６ Pa or more 1.8×10 ６ The adhesive tape has a compressive strength of 0.2 Pa or less.

2. The storage modulus (G') of the pressure-sensitive adhesive layer at 60°C measured at a frequency of 0.1 Hz is 7.0 × 10 ４ Pa or more 9.0×10 ４ The adhesive tape according to claim 1, wherein the elastic modulus is 0.05 Pa or less.

3. 3. The adhesive tape according to claim 1, wherein the adhesive layer has a thickness of 300 μm or more.

4. 3. The adhesive tape according to claim 1, wherein the crosslinking agent contained in the adhesive layer is a dinitroso compound, and the amount of the crosslinking agent added is 0.35 parts by mass or more and 1.10 parts by mass or less per 100 parts by mass of the butyl rubber.

5. 4. The pressure-sensitive adhesive tape according to claim 3, wherein the cross-linking agent contained in the pressure-sensitive adhesive layer is a dinitroso compound, and the amount of the cross-linking agent added is 0.35 parts by mass or more and 1.10 parts by mass or less per 100 parts by mass of the butyl rubber.

6. The adhesive tape according to claim 4 , wherein the adhesive layer further contains a thiazole-based compound as a crosslinking accelerator.

7. The adhesive tape according to claim 5 , wherein the adhesive layer further contains a thiazole compound as a crosslinking accelerator.

8. The kinematic viscosity of the softener at 40°C is 20 mm ２ / s or more 100mm ２ 3. The pressure-sensitive adhesive tape according to claim 1, wherein the butyl rubber is present in an amount of 40 parts by mass or more and 70 parts by mass or less per 100 parts by mass of a total amount of the rubber components including the butyl rubber.

9. The kinematic viscosity of the softener at 40°C is 20 mm ２ / s or more 100mm ２ 4. The pressure-sensitive adhesive tape according to claim 3, wherein the butyl rubber is present in an amount of 40 parts by mass or more and 70 parts by mass or less per 100 parts by mass of the total amount of the rubber components including the butyl rubber.

10. The kinematic viscosity of the softener at 40°C is 20 mm ２ / s or more 100mm ２ 5. The pressure-sensitive adhesive tape according to claim 4, wherein the butyl rubber is present in an amount of 40 parts by mass or more and 70 parts by mass or less per 100 parts by mass of a total amount of the rubber components including the butyl rubber.

11. The kinematic viscosity of the softener at 40°C is 20 mm ２ / s or more 100mm ２ 6. The pressure-sensitive adhesive tape according to claim 5, wherein the butyl rubber is present in an amount of 40 parts by mass or more and 70 parts by mass or less per 100 parts by mass of the total amount of the rubber components including the butyl rubber.

12. The kinematic viscosity of the softener at 40°C is 20 mm ２ / s or more 100mm ２ 7. The pressure-sensitive adhesive tape according to claim 6, wherein the butyl rubber content is 40 parts by mass or more and 70 parts by mass or less per 100 parts by mass of the total amount of the rubber components including the butyl rubber.

13. The kinematic viscosity of the softener at 40°C is 20 mm ２ / s or more 100mm ２ 8. The pressure-sensitive adhesive tape according to claim 7, wherein the butyl rubber is present in an amount of 40 parts by mass or more and 70 parts by mass or less per 100 parts by mass of a total amount of the rubber components including the butyl rubber.

14. 3. The adhesive tape according to claim 1, which is used for connecting pipe insulation materials.

15. The adhesive tape according to claim 3, which is used for connecting pipe insulation materials.

16. The adhesive tape according to claim 4, which is used for connecting pipe insulation materials.

17. The adhesive tape according to claim 5, which is used for connecting pipe insulation materials.

18. The adhesive tape according to claim 6, which is used for connecting pipe insulation materials.

19. The adhesive tape according to claim 7, which is used for connecting pipe insulation materials.

20. The adhesive tape according to claim 8, which is used for connecting pipe insulation materials.

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