Double-sided adhesive tape, and method for manufacturing double-sided adhesive tape

Abstract

Provided is a double-sided adhesive tape comprising an adhesive layer composed of a rubber-based adhesive and having excellent anchorability between a substrate layer and an adhesive layer. According to the present invention, provided is a double-sided adhesive tape comprising a substrate layer composed of a substrate, and an adhesive layer composed of an adhesive composition on both surfaces of the substrate layer, wherein the substrate is a non-woven fabric including a polyester fiber, and the adhesive composition includes a styrene-butadiene-based block copolymer in which a butadiene portion is partially hydrogenated, and the arithmetic average height Sa of the surface of the adhesive layer, based on ISO25178, is 15 μm or less.

Description

[Technical Field]

[0001] This invention relates to a double-sided adhesive tape and a method for manufacturing a double-sided adhesive tape. [Background technology]

[0002] In various industrial fields such as electrical appliances, automobiles, and construction, double-sided adhesive tape is used, for example, to fix various parts. The adhesives used in double-sided adhesive tape include acrylic adhesives and rubber adhesives, and in the above applications, heat-resistant acrylic adhesives are frequently used. However, acrylic adhesives have a problem in that they have low adhesion to olefin resin materials such as polyethylene and polypropylene, which have seen increased use in recent years.

[0003] While rubber-based adhesives exhibit high adhesion to olefin-based resin materials, their adhesive strength tends to decrease in high-temperature environments. Patent Document 1 discloses an adhesive composition for use in double-sided adhesive tapes, in which a block copolymer of a monovinyl-substituted aromatic compound and a conjugated diene compound is used as the base polymer, and the adhesive composition exhibits improved cohesiveness in high-temperature environments. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Patent No. 6663448 [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] Double-sided adhesive tape has a thick adhesive layer on both sides of a substrate layer, which is made up of a base material. Therefore, when forming the adhesive layer by coating the substrate with an adhesive dissolved in a solvent such as water, the energy, cost, and time required for the drying process of the solvent after coating are significant. On the other hand, hot-melt coating, in which the adhesive is applied to the substrate in a molten state at high temperature, does not require a drying process, thus reducing the energy, cost, and time involved in manufacturing.

[0006] Hot-melt adhesives used in hot-melt coatings tend to have a high melt viscosity during application. As a result, when applied to a substrate, the anchoring (adhesion) between the substrate layer and the adhesive layer is often insufficient, leading to the problem of adhesive residue (the phenomenon of adhesive remaining on the substrate) when double-sided adhesive tape is applied to and removed from the adherend.

[0007] This invention has been made in view of these circumstances, and aims to provide a double-sided adhesive tape comprising an adhesive layer composed of a rubber-based adhesive, which exhibits excellent anchoring properties between the base layer and the adhesive layer. [Means for solving the problem]

[0008] [1] A double-sided adhesive tape comprising a base layer made of a substrate and adhesive layers made of an adhesive composition on both sides of the base layer, wherein the base is a nonwoven fabric containing polyester fibers, the adhesive composition contains a styrene-butadiene block copolymer in which the butadiene portion is partially hydrogenated, and the arithmetic mean height Sa of the surface of the adhesive layer according to ISO 25178 is 15 μm or less. [2] The double-sided adhesive tape according to [1], wherein the tensile breaking strength in the longitudinal direction of the double-sided adhesive tape is 5 to 50 N / 20 mm based on JIS Z 0237. [3] The basis weight of the substrate is 5 to 20 g / m² 2 The double-sided adhesive tape described in [1] or [2]. [4] The density of the base material is 0.3 to 0.7 g / cm³ 3The double-sided adhesive tape described in any one of items [1] to [3]. [5] The double-sided adhesive tape according to any one of items [1] to [4], wherein the thickness of the substrate is 15 to 40 μm. [6] The adhesive composition comprises a first tackifier, a second tackifier, and a third tackifier, wherein the first tackifier is a terpene resin that is liquid at 23°C, the second tackifier is a terpene resin with a softening point of 120°C or lower, and the third tackifier is a terpene phenol resin with a softening point of 135°C or higher, and the double-sided adhesive tape according to any one of [1] to [5]. [7] The adhesive composition is applied to one side of the substrate layer at a rate of 80 to 100 g / m² 2 Double-sided adhesive tape as described in any one of items [1] to [6], provided in the specified quantity. A method for manufacturing a double-sided adhesive tape according to any one of items [8], [1] to [7], comprising the steps of: hot-melt coating the adhesive composition onto the release surface of a release paper; and forming the adhesive layer on both sides of the substrate layer by bonding and transferring the hot-melt coated adhesive composition onto the release paper to the substrate. [Effects of the Invention]

[0009] Through diligent research, the inventors discovered that by constructing a base layer with a nonwoven fabric containing polyester fibers, constructing an adhesive layer with an adhesive composition containing a styrene-butadiene block copolymer in which the butadiene portion is partially hydrogenated, and setting the arithmetic mean height Sa of the surface of the adhesive layer to 15 μm or less, it is possible to realize a double-sided adhesive tape that exhibits excellent anchoring properties between the base layer and the adhesive layer, as well as good adhesive strength, even when the adhesive layer is formed by hot-melt coating. This led to the completion of the present invention. Due to its properties, the double-sided adhesive tape according to the present invention is less likely to leave adhesive residue when peeled off from the adherend. [Brief explanation of the drawing]

[0010] [Figure 1] This figure shows an example of the layer structure of the double-sided adhesive tape according to the present invention. [Figure 2] It is a diagram showing another example of the layer structure of the double-sided pressure-sensitive adhesive tape according to the present invention. Mode for Carrying Out the Invention

[0011] Hereinafter, embodiments of the present invention will be described with reference to the drawings. Each feature shown in the following embodiments can be combined with each other. Furthermore, an invention can be claimed independently for each feature.

[0012] 1. Layer structure of double-sided pressure-sensitive adhesive tape FIG. 1 is a diagram showing an example of the layer structure of a double-sided pressure-sensitive adhesive tape according to the present invention. As shown in FIG. 1, a double-sided pressure-sensitive adhesive tape 1 includes a base material layer 2 made of a base material, and pressure-sensitive adhesive layers 3 made of a pressure-sensitive adhesive composition on both sides of the base material layer 2. The pressure-sensitive adhesive layer 3 is provided directly on the surface of the base material layer 2; in other words, no other layer is interposed between the base material layer 2 and the pressure-sensitive adhesive layer 3. FIG. 2 is a diagram showing another example of the layer structure of the double-sided pressure-sensitive adhesive tape according to the present invention. As shown in FIG. 2, the double-sided pressure-sensitive adhesive tape 1 may include a base material layer 2 made of a base material, pressure-sensitive adhesive layers 3 made of a pressure-sensitive adhesive composition on both sides of the base material layer 2, and release paper 4 bonded to the pressure-sensitive adhesive layers 3. In this case, the release-treated surface of the release paper 4 is bonded to the surface of the pressure-sensitive adhesive layer 3 opposite to the surface in contact with the base material.

[0013] The double-sided pressure-sensitive adhesive tape of the present embodiment has an overall long tape shape. In the present invention, the direction in which a long tape is wound or unwound is referred to as the longitudinal direction. Alternatively, a product may be obtained by peeling off one of the release papers respectively bonded to two pressure-sensitive adhesive layers, and winding a long tape into a roll such that one release-treated surface of the other release paper and the other release-treated surface are respectively bonded to the two pressure-sensitive adhesive layers.

[0014] 2. Pressure-sensitive adhesive composition 2.1. Styrene-butadiene block copolymer The pressure-sensitive adhesive composition constituting the pressure-sensitive adhesive layer comprises a styrene-butadiene block copolymer in which butadiene moieties are partially hydrogenated. The styrene-butadiene block copolymer according to the present invention means a block copolymer comprising a block having styrene monomer units and a block having butadiene monomer units. The styrene monomer units are structural units (monomer units) of blocks and copolymers derived from styrene. The butadiene monomer units are structural units (monomer units) of blocks and copolymers derived from butadiene.

[0015] In the styrene-butadiene block copolymer, the content of styrene monomer units is preferably 5 to 50% by mass, and more preferably 10 to 40% by mass. Specific examples of the content of styrene monomer units include 5, 10, 15, 20, 25, 30, 35, 40, 45, and 50% by mass, and it may be within a range between any two of the numerical values exemplified herein. By setting the content within such a range, the obtained double-sided pressure-sensitive adhesive tape has appropriate adhesive force to an adherend and holding power. The content of styrene monomer units can be measured based on JIS K6383.

[0016] In the styrene-butadiene block copolymer according to the present invention, butadiene moieties are partially hydrogenated. With respect to the butadiene moieties of the styrene-butadiene block copolymer, 20 to 90% by mass is preferably hydrogenated, and 30 to 80% by mass is more preferably hydrogenated. Specific examples of the styrene-butadiene block copolymer in which butadiene moieties are partially hydrogenated include styrene-butadiene-butylene-styrene block copolymer (SBBS).

[0017] The adhesive composition according to the present invention preferably includes a triblock copolymer as a styrene-butadiene block copolymer, comprising block A containing monomer units derived from styrene, block B containing monomer units derived from butadiene, and block C containing monomer units derived from styrene. Furthermore, the adhesive composition according to the present invention preferably includes a diblock copolymer as a styrene-butadiene block copolymer, comprising block A containing monomer units derived from styrene, and block B containing monomer units derived from butadiene. Here, it is preferable that a portion of block B containing monomer units derived from butadiene is hydrogenated. That is, it is preferable that block B containing monomer units derived from butadiene has a butadiene block and a butylene block.

[0018] The adhesive composition according to the present invention preferably contains 50 to 85% by mass of the diblock copolymer, and more preferably 55 to 80% by mass, when the total mass of the styrene-butadiene block copolymer contained in the adhesive composition is taken as 100% by mass. Specifically, the content of the diblock copolymer may be, for example, 50, 55, 60, 65, 70, 75, 80, or 85% by mass, and may be within the range of any two of the values ​​exemplified here. By setting the content of the diblock copolymer within the above numerical range, an adhesive composition having appropriate tack can be obtained.

[0019] The weight-average molecular weight of the styrene-butadiene block copolymer is not particularly limited, but is preferably 30,000 to 500,000, and more preferably 60,000 to 300,000. The weight-average molecular weight can be determined by gel permeation chromatography (GPC).

[0020] Styrene-butadiene block copolymers may be used individually or in combination of two or more types. For example, two or more styrene-butadiene block copolymers with different peak-top molecular weight, weight-average molecular weight, molecular weight distribution, MFR, styrene-derived monomer unit content, diblock copolymer content, viscosity, etc., may be used in combination.

[0021] 2.2. First Tackifire The adhesive composition constituting the adhesive layer preferably contains a terpene resin that is liquid at 23°C as the first tackifier. In the present invention, "tackifier" means a tackifier, which is a thermoplastic resin that is liquid or solid at room temperature and added to enhance tackiness. The adhesive composition may contain one type of first tackifier alone, or two or more types in combination. The terpene resin according to the present invention refers to a polymer of terpenes, a copolymer of terpenes and other monomers, and polymers thereof that have been hydrogenated, and examples include terpene resins, aromatically modified terpene resins, terpene phenol resins, and hydrogenated terpene phenol resins. It is more preferable to use an aromatically modified terpene resin as the first tackifier.

[0022] Examples of terpene resins that are liquid at 23°C include YS Resin LP (aromatic modified terpene resin, flash point 220°C, manufactured by Yasuhara Chemical Co., Ltd.), Daimaron (liquid terpene resin, flash point 174°C, manufactured by Yasuhara Chemical Co., Ltd.), YS Resin CP (liquid terpene resin, flash point 178°C, manufactured by Yasuhara Chemical Co., Ltd.), YS Resin PX300N (terpene resin, flash point 202°C, manufactured by Yasuhara Chemical Co., Ltd.), and YS Polystar T30 (terpene phenol resin, flash point 205°C, manufactured by Yasuhara Chemical Co., Ltd.). Among these, YS Resin LP is preferred from the viewpoint of having a high flash point, low heat loss, and high compatibility with the styrene-butadiene block copolymer according to the present invention. The flash point of a terpene resin that is liquid at 23°C is preferably 180°C or higher, more preferably 200°C or higher, and even more preferably 210°C or higher.

[0023] For terpene resins that are liquid at 23°C, the viscosity at 25°C is preferably 500 to 150,000 mPa·s, and more preferably 1,000 to 100,000 mPa·s. The viscosity at 25°C can be, for example, 500, 1,000, 2,000, 5,000, 10,000, 20,000, 50,000, 100,000, 120,000, or 150,000 mPa·s, and may be within the range of any two of the values ​​exemplified here.

[0024] 2.3. The Second Tackifire The adhesive composition constituting the adhesive layer preferably contains a tackifier with a softening point of 120°C or lower as a second tackifier. The adhesive composition may contain one type of second tackifier alone, or two or more types in combination.

[0025] The softening point of the second tackifier is, for example, 70 to 120°C, preferably 80 to 120°C, and more preferably 85 to 115°C. Specifically, the softening point may be, for example, 70, 75, 80, 85, 90, 95, 100, 105, 110, 115, or 120°C, and may be within the range of any two of the values ​​exemplified here.

[0026] As the second tackifier, for example, C9 petroleum resin, hydrogenated C9 petroleum resin, C5 petroleum resin, alicyclic petroleum resin, alicyclic / aromatic petroleum resin, rosin resin (polymerized rosin ester, modified polymerized rosin ester, stabilized rosin ester, etc.), terpene resin (excluding terpene resins that are liquid at 23°C), etc. are used. As the second tackifier, it is preferable to use a terpene resin because of its good adhesive properties, and more preferable to use a terpene resin.

[0027] 2.4. The Third Tackifire The adhesive composition constituting the adhesive layer preferably includes a tackifier having a softening point of 135°C or higher as a third tackifier. The adhesive composition may contain one third tackifier alone or two or more in combination.

[0028] The softening point of the third tackifier is, for example, 135 to 180°C, and more preferably 140 to 170°C. Specifically, the softening point may be, for example, 135, 140, 145, 150, 155, 160, 165, 170, 175, 180°C, and may be within the range of any two of the values ​​exemplified here.

[0029] As the third tackifier, for example, C9 petroleum resins, hydrogenated C9 petroleum resins, C5 petroleum resins, alicyclic petroleum resins, alicyclic / aromatic petroleum resins, terpene resins (terpene resins, aromatically modified terpene resins, terpene phenol resins, hydrogenated terpene phenol resins, etc.), rosin resins (polymerized rosin esters, modified polymerized rosin esters, stabilized rosin esters, etc.), alkylphenol compounds, etc., can be used, all having a softening point of 135°C or higher. From the viewpoint of having an excellent balance between melt viscosity and high-temperature tackiness, it is preferable to use terpene phenol resins as the third tackifier. In particular, from the viewpoint of obtaining an adhesive composition with low melt viscosity that is easy to coat, it is even more preferable to use terpene phenol resins as the third tackifier.

[0030] The softening point of the tackifier described above can be defined as the value measured based on the softening point test method (ring-ball method) specified in JIS K5902 and JIS K2207. Specifically, the sample is melted as quickly as possible at the lowest possible temperature and carefully filled into a ring placed on a flat metal plate, taking care not to create bubbles. After cooling, the raised portion from the plane including the top end of the ring is cut off with a slightly heated knife. Next, a support (ring stand) is placed in a glass container (heating bath) with a diameter of 85 mm or more and a height of 127 mm or more, and glycerin is poured in to a depth of 90 mm or more. Next, a steel ball (diameter 9.5 mm, weight 3.5 g) and the ring filled with the sample are immersed in the glycerin so that they do not come into contact with each other, and the temperature of the glycerin is maintained at 20°C ± 5°C for 15 minutes. Next, the steel ball is placed in the center of the surface of the sample in the ring and placed in a fixed position on the support. Next, maintain a distance of 50 mm from the top of the ring to the glycerin surface, place a thermometer, and position the center of the thermometer's mercury bulb at the same height as the center of the ring, then heat the container. The flame of the Bunsen burner used for heating should be positioned midway between the center and edge of the container's bottom to ensure even heating. The rate of increase in the bath temperature after reaching 40°C from the start of heating can be set to 5.0 ± 0.5°C per minute. The temperature at which the sample gradually softens and flows out of the ring and contacts the bottom plate can be read and defined as the softening point. Two or more softening points can be measured simultaneously, and the average value can be used.

[0031] Furthermore, since the softening point is approximately 50°C higher than the glass transition temperature (Tg) of the tackifier, the softening point can be estimated by detecting Tg using DSC (Differential Scanning Calorimetry). One method for identifying the softening point of tackifiers in adhesives using this technique is to isolate the tackifier component in the adhesive using preparative HPLC, measure Tg from the DSC measurement results of the isolated sample, and then estimate the softening point.

[0032] 2.5. Content of each component The content of the styrene-butadiene block copolymer, the first tackifier, the second tackifier, and the third tackifier in the adhesive composition is not particularly limited. For example, by setting the content of each component within the following ranges, it is easier to obtain an adhesive tape that has even higher adhesive strength to olefin-based materials, especially high adhesive strength at high temperatures.

[0033] The adhesive composition preferably contains 45 to 55 parts by mass of styrene-butadiene block copolymer when the total adhesive composition is 100 parts by mass. Specifically, the content of styrene-butadiene block copolymer may be, for example, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, or 55 parts by mass, and may be within the range of any two of the values ​​exemplified here.

[0034] The adhesive composition preferably contains 5 to 15 parts by mass of the first tackifier when the total adhesive composition is 100 parts by mass. Specifically, the content of the first tackifier may be, for example, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, or 15 parts by mass, and may be within the range of any two of the values ​​exemplified here.

[0035] The adhesive composition preferably contains 10 parts by mass or more of the second tackifier, more preferably 10 to 40 parts by mass, and even more preferably 12 to 25 parts by mass, when the total adhesive composition is 100 parts by mass. Specifically, the content of the second tackifier may be, for example, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, or 40 parts by mass, and may be within the range of any two of the values ​​exemplified here.

[0036] The adhesive composition preferably contains 10 to 30 parts by mass of the third tackifier, and more preferably 15 to 28 parts by mass, when the total adhesive composition is 100 parts by mass. Specifically, the content of the third tackifier may be, for example, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, or 30 parts by mass, and may be within the range of any two of the values ​​exemplified here.

[0037] The adhesive composition preferably contains 45 to 55 parts by mass of styrene-butadiene block copolymer, 5 to 15 parts by mass of a first tackifier, 10 to 40 parts by mass of a second tackifier, and 10 to 30 parts by mass of a third tackifier, based on 100 parts by mass of the adhesive composition.

[0038] 2.6. Other ingredients In addition to the above components, the adhesive composition according to the present invention may also contain various additives such as plasticizers, antioxidants, ultraviolet absorbers, stabilizers, fillers, and modifiers, to the extent that they do not impair the effects of the present invention.

[0039] (Plasticizer) The adhesive composition may contain a plasticizer. Examples of plasticizers include phthalate ester plasticizers, polybutene, paraffinic process oils, naphthenic process oils, aromatic process oils, liquid paraffin, and hydrocarbon synthetic oils.

[0040] (Antioxidant / UV absorber) Antioxidants include 2,6-di-t-butyl-4-methylphenol, n-octadecyl-3-(4'-hydroxy-3',5'-di-t-butylphenyl)propionate, 2,2'-methylenebis(4-methyl-6-t-butylphenol), 2,2'-methylenebis(4-ethyl-6-t-butylphenol), 2,4-bis(octylthiomethyl)-o-cresol, 2-t-butyl-6-(3-t-butyl-2-hydroxy-5-methylbenzyl)-4-methylphenyl acrylate, 2,4-di-t-amyl-6-[1-(3,5-di-t-amyl-2-hydroxyphenyl)ethyl]phenyl acrylate, and 2-[1-(2-hydroxy-3,5-di-tert-pentylphenyl] Examples of antioxidants include phenolic antioxidants such as acrylate, tetrakis[methylene-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate]methane, 2,4-bis[(dodecylthio)methyl]-6-methylphenol, and pentaerythritol tetrakis[3-[3,5-di(tert-butyl)-4-hydroxyphenyl]propionate]; sulfur-based antioxidants such as dilaurylthiodipropionate, laurylstearylthiodipropionate, and pentaerythritol tetrakis(3-laurylthiopropionate); phosphorus-based antioxidants such as tris(nonylphenyl)phosphite and tris(2,4-di-t-butylphenyl)phosphite; and lactone-based antioxidants. Examples of UV absorbers include benzotriazole-based UV absorbers such as 2-(2'-hydroxy-5'-methylphenyl)benzotriazole, 2-(2'-hydroxy-3',5'-t-butylphenyl)benzotriazole, and 2-(2'-hydroxy-3',5'-di-t-butylphenyl)-5-chlorobenzotriazole; benzophenone-based UV absorbers such as 2-hydroxy-4-methoxybenzophenone; salicylate-based UV absorbers; cyanoacrylate-based UV absorbers; and hindered amine-based light stabilizers. These can be used individually or in combination.

[0041] The antioxidant content per 100 parts by mass of the adhesive composition is, for example, 0.1 to 3.5 parts by mass, specifically, for example, 0.1, 0.2, 0.3, 0.4, 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, and 3.5 parts by mass, and may be within the range of any two of the values ​​exemplified here.

[0042] (Filler) Examples of fillers include calcium carbonate, kaolin, talc, titanium dioxide, mica, styrene beads, and silica. These particulate fillers can be used individually or in combination.

[0043] 2.7. Viscosity of the adhesive composition The adhesive composition preferably has a melt viscosity of 100,000 mPa·s or less at 180°C, and more preferably between 20,000 and 90,000 mPa·s. Specifically, the melt viscosity may be, for example, 20,000, 30,000, 40,000, 50,000, 60,000, 70,000, 80,000, 90,000, or 100,000 mPa·s, and may also be within the range of any two of the values ​​exemplified here. By setting the melt viscosity at 180°C within the above numerical range, an adhesive composition suitable for hot-melt coating can be obtained. The melt viscosity at 180°C can be controlled by appropriately selecting the type of compounding in the adhesive composition and adjusting the amount thereof. The melt viscosity of the adhesive composition can be measured at 180°C with a shear rate of 10¹ / s using a rheometer.

[0044] 3.Base material The base material constituting the base layer is a nonwoven fabric containing polyester fibers. The nonwoven fabric used as the base material preferably has polyester fibers as its main component, that is, 50% or more by mass of the entire base material, more preferably 80% or more by mass, and even more preferably 95% or more by mass. Alternatively, a nonwoven fabric made of polyester fibers may be used to constitute the base material. For example, polyethylene terephthalate (PET) fibers can be used as the polyester fibers.

[0045] When double-sided adhesive tape is applied to an object and then removed, adhesive residue can remain on the object, either as only the adhesive layer being left behind, or as the substrate breaking midway through its thickness, leaving behind a portion of the substrate layer and the adhesive layer (core material cracking). Because polyester fiber nonwoven fabrics are relatively dense, when an adhesive composition is applied, the contact area between the substrate and the adhesive composition increases, improving the anchoring properties between the substrate layer and the adhesive layer, and also resulting in good substrate strength. Therefore, by using a nonwoven fabric containing polyester fibers as the substrate, adhesive residue is less likely to occur when double-sided adhesive tape is applied to an object and then removed.

[0046] The nonwoven fabric used as the base material may contain fibers other than polyester fibers, as long as they do not impair the effects of the present invention. Examples of components other than polyester fibers include rayon, polyolefin fibers, vinylon, acetate fibers, polyvinyl alcohol fibers, polyamide fibers, and polyurethane fibers. The nonwoven fabric does not have to contain fibers other than polyester fibers.

[0047] The basis weight of the substrate is, for example, 3 to 35 g / m². 2 It is 5-20g / m 2 Preferably, it is 6-14 g / m 2 It is more preferable that the basis weight of the base material be, specifically, for example, 3, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 20, 25, 30, 35 g / m². 2 And it may be within the range of any two of the numbers exemplified here.

[0048] The thickness of the substrate is, for example, 9 to 45 μm, preferably 15 to 40 μm, and more preferably 17 to 26 μm. Specifically, the thickness of the substrate is, for example, 9, 10, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 35, 40, 45 μm, and may be within the range of any two of the values ​​exemplified here.

[0049] The density of the base material is, for example, 0.2 to 1.0 g / cm³. 3, which is 0.3 to 0.7 g / cm 3 , and is preferably 0.4 to 0.7 g / cm 3 and more preferably. Specifically, the density of the substrate is, for example, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0 g / cm 3 , and may be within a range between any two of the numerical values exemplified herein.

[0050] By setting the basis weight, density and thickness of the substrate within the above ranges, adhesive residue is less likely to occur when the double-sided adhesive tape is attached to an adherend and then peeled off.

[0051] 4. Characteristics of Double-sided Adhesive Tape 4.1. Surface Roughness of Adhesive Layer In the present invention, the arithmetic mean height Sa of the surface of the adhesive layer based on ISO 25178 is 15 μm or less. Although the lower limit of the arithmetic mean height Sa of the adhesive layer surface is not particularly limited, it is, for example, 0 μm or more. The arithmetic mean height Sa of the adhesive layer surface is more preferably 12 μm or less, and still more preferably 10 μm or less. Specifically, the arithmetic mean height Sa of the adhesive layer surface is, for example, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15 μm, and may be within a range between any two of the numerical values exemplified herein. By setting the arithmetic mean height Sa of the adhesive layer surface within the above numerical range, a double-sided adhesive tape having a smooth adhesive layer surface and good adhesive force can be obtained. The arithmetic mean height Sa of the adhesive layer surface can be measured using a measuring device such as a laser microscope.

[0052] 4.2. Coating Amount of Adhesive Layer The pressure-sensitive adhesive composition constituting the adhesive layer is provided on one side of the base material layer in an amount of, for example, 50 to 110 g / m 2 , and is preferably provided in an amount of 80 to 100 g / m 2 Specifically, the amount of the pressure-sensitive adhesive composition per one side of the base material layer is, for example, 50, 60, 70, 80, 90, 100, 110 g / m 2The values ​​may be within the range of any two of the values ​​exemplified here. By setting the amount of adhesive composition applied within the above numerical range, a double-sided adhesive tape with good adhesive strength can be obtained.

[0053] 4.3. Tensile breaking strength The tensile breaking strength in the longitudinal direction of the double-sided adhesive tape is preferably 5 to 50 N / 20 mm, more preferably 10 to 50 N / 20 mm, and even more preferably 20 to 50 N / 20 mm. Specifically, the tensile breaking strength may be, for example, 5, 10, 15, 20, 25, 30, 35, 40, 45, or 50 N / 20 mm, and may also be within the range of any two of the values ​​exemplified here. By setting the tensile breaking strength of the double-sided adhesive tape within the above numerical range, a double-sided adhesive tape with appropriate strength can be obtained, and core material cracking is less likely to occur when peeling the double-sided adhesive tape from the adherend. The tensile breaking strength can be measured according to JIS Z0237.

[0054] 4.4. Adhesive strength The double-sided adhesive tape preferably has an adhesive strength of 10 N / 20 mm or more to a SUS substrate at 80°C according to JIS Z0237, more preferably 11 N / 20 mm or more, and even more preferably 12 N / 20 mm or more. Specifically, the adhesive strength may be, for example, 10, 10.5, 11, 11.5, 12, 12.5, 13, 13.5, 14, 15, 16, 17, 18, 19, or 20 N / 20 mm, and may also be within the range of any two of the values ​​exemplified here.

[0055] Furthermore, the double-sided adhesive tape preferably has an adhesive strength of 26 N / 20 mm or more to a SUS substrate at 23°C according to JIS Z0237, more preferably 28 N / 20 mm or more, and even more preferably 32 N / 20 mm or more. Specifically, the adhesive strength may be, for example, 26, 27, 28, 30, 32, 34, 36, 38, 40, 42, 44, 46, 48, or 50 N / 20 mm, and may also be within the range of any two of the values ​​exemplified here.

[0056] Adhesion can be controlled by adjusting the type and amount of the adhesive composition, and in particular by adjusting the type and amount of the adhesive composition so that the holding force of the adhesive tape and the melt viscosity of the adhesive composition fall within a specific numerical range. Adhesion can be determined by measuring the 180° peel adhesion to a SUS substrate in a 23°C or 80°C atmosphere, based on JIS Z0237 "10. Adhesion".

[0057] 5. Method for manufacturing double-sided adhesive tape The method for producing the adhesive composition is not particularly limited. For example, the method for producing the adhesive composition according to this embodiment may include a tackifier mixing step in which raw materials including a styrene-butadiene block copolymer, a first tackifier, a second tackifier, and a third tackifier are mixed in a kneader mixer. In addition, antioxidants and plasticizers may be further added in the above step. In the tackifier mixing step, mixing can be carried out for, for example, 3 to 30 minutes at 5 to 25 rpm. Furthermore, it is preferable that the method for producing the adhesive composition includes a styrene-butadiene block copolymer addition and mixing step in which the styrene-butadiene block copolymer is further added and mixed after the tackifier mixing step. In the styrene-butadiene block copolymer addition and mixing step, mixing can be carried out for, for example, 20 to 200 minutes at 5 to 30 rpm.

[0058] A method for manufacturing double-sided adhesive tape preferably includes a coating step in which an adhesive composition is applied to the release surface of a release liner using a hot-melt method. The adhesive composition according to this embodiment has low viscosity at high temperatures, making it possible to apply it using a hot-melt method. Compared to a method in which the adhesive composition is dissolved in a solvent, applied, and dried, the hot-melt method allows for the production of double-sided adhesive tape with less energy, cost, and time. Known methods can be used for the coating, including, for example, die coating, roll coating, curtain coating, spray coating, and cloth coating.

[0059] Furthermore, the manufacturing method of the double-sided adhesive tape preferably includes a transfer step in which a molten adhesive composition, which has been hot-melted onto release paper, is bonded to the substrate and transferred to form adhesive layers on both sides of the substrate layer. When the adhesive layer is formed by the transfer method, the surface of the adhesive layer is easily smoothed, making it easy to set the surface roughness of the adhesive layer within the above range, and thus a double-sided adhesive tape with good adhesive strength can be obtained.

[0060] When forming an adhesive layer using a transfer method, the adhesive composition does not penetrate the substrate as easily as when the adhesive layer is formed by directly coating the substrate (direct coating), and the anchoring between the substrate layer and the adhesive layer tends to be insufficient. In the present invention, by using a nonwoven fabric containing polyester fibers as the substrate, sufficient anchoring between the substrate layer and the adhesive layer can be achieved even when using a transfer method. [Examples]

[0061] The present invention will be described in more detail below based on examples, but the present invention is not limited to these examples.

[0062] <Preparation of adhesive composition> Tackifier was added to a kneader mixed at a temperature of 200°C, and then an antioxidant was added. The mixture was kneaded at 15 rpm for 10 minutes. After that, the block copolymer was added and kneaded at 15 rpm for 5 minutes, and then kneaded at 30 rpm for 100 minutes to obtain the adhesive composition. The amount (parts by mass) of each component in the adhesive composition in the examples and comparative examples is shown in Tables 1 and 2.

[0063] The melt viscosity of the obtained adhesive composition at 180°C was measured using a rheometer (Anton Paar, MCR302, measuring jig Φ25 cone plate angle 1°) under a shear rate of 10 (1 / s). The measurement results are shown in Tables 1 and 2.

[0064] The block copolymers used in the examples and comparative examples are as follows: Asaprene N521 (manufactured by Asahi Kasei Corporation): SBBS (a styrene-butadiene-butylene-styrene block copolymer in which the butadiene portion is partially hydrogenated), styrene content 25% by mass, diblock content 60% by mass, weight-average molecular weight 150,000 ToughTec P1500 (manufactured by Asahi Kasei Corporation): SBBS (a styrene-butadiene-butylene-styrene block copolymer in which the butadiene portion is partially hydrogenated), styrene content 30% by mass, diblock content 65% by mass, weight-average molecular weight 80,000 Quintac 3421 (manufactured by Zeon Corporation): SIS (styrene-isoprene-styrene block copolymer)

[0065] The tackifiers used in the examples and comparative examples are as follows: YS Resin LP (manufactured by Yasuhara Chemical Co., Ltd.): Aromatically modified terpene resin that is liquid at 23°C, flash point 220°C. YS Resin PX1150N (manufactured by Yasuhara Chemical Co., Ltd.): Terpene resin, softening point 115℃ YS Polystar T160 (manufactured by Yasuhara Chemical Co., Ltd.): Terpene phenol resin, softening point 160℃

[0066] The antioxidants used in the examples and comparative examples are as follows: Irganox 1010 (manufactured by BASF Japan Ltd.): Phenolic antioxidant

[0067] <Manufacturing of double-sided adhesive tape> In Examples 1-9 and Comparative Examples 2-6, the prepared adhesive composition was heated to 200°C in a melter to melt it, and then coated onto the release surface of the release paper using a slot die coater. Furthermore, the molten adhesive composition, which had been hot-melt coated onto the release paper, was transferred to both sides of the substrate shown in Tables 1 and 2, respectively, to form adhesive layers on both sides of the substrate layer and produce a double-sided adhesive tape. In Comparative Example 1, the adhesive layer was formed by directly coating the substrate with the heated and melted adhesive composition as described above, and a double-sided adhesive tape was produced. The amount of adhesive composition per side of the substrate layer was set as shown in Tables 1 and 2.

[0068] The release papers used in the examples and comparative examples are as follows: SLB-50WD (#1400) (manufactured by Sumika Kako Paper Co., Ltd.): Silicone-coated double-sided release paper, 98 μm thickness

[0069] The substrates used in the examples and comparative examples are as follows. The thickness, basis weight, and density of each substrate are shown in Tables 1 and 2. The thickness of the substrates was measured using a digital thickness gauge (TECLOCK Co., Ltd., SMD-565J-L). Examples 1, 5, 6, Comparative Example 1: Polyester nonwoven fabric (Daio Paper Corporation, Polyester Paper HD13) Example 2: Polyester nonwoven fabric (Daio Paper Corporation, Polyester Paper HD14) Example 3: Polyester nonwoven fabric (manufactured by Daio Paper Corporation, Polyester Paper HS9) Example 4: Polyester nonwoven fabric (manufactured by Daio Paper Corporation, Polyester Paper HS6) Example 7: Polyester nonwoven fabric (Daio Paper Corporation, Polyester Paper HD30) Example 8: Polyester nonwoven fabric (Daio Paper Corporation, Polyester Paper HD4) Example 9: Polyester nonwoven fabric (Daio Paper Corporation, Polyester Paper HD8) Comparative Example 2: Rayon Nonwoven Fabric (Manufactured by Daio Paper Corporation, a nonwoven fabric consisting of FS Rayon L17, pulp, and rayon) Comparative Example 3: OPP film (Futamura Chemical Co., Ltd., FOR12, biaxially oriented polypropylene film) Comparative Example 4: Rayon Nonwoven Fabric (Daio Paper Corporation, FS Rayon Paper L11, pulp and rayon nonwoven fabric) Comparative Examples 5 and 6: Rayon nonwoven fabric (manufactured by Daio Paper Corporation, consisting of high-transparency rayon 7, pulp, and rayon)

[0070] <Measurement of the arithmetic mean height Sa of the adhesive layer> Using a laser microscope, the release liner was peeled off the double-sided adhesive tape manufactured as described above, and the arithmetic mean height Sa of the adhesive layer surface was measured. The measurement results are shown in Tables 1 and 2.

[0071] <Rating> The following evaluations were performed on the double-sided adhesive tapes of the examples and comparative examples.

[0072] (Adhesive strength) The adhesive strength (180° peel adhesive strength) of double-sided adhesive tape to a stainless steel plate was measured under 23°C and 80°C atmospheres. First, a piece of double-sided adhesive tape was punched out to a width of 20 mm and a length of 200 mm. The release paper was peeled off one side, and a PET film (38 μm thick) measuring 20 mm wide x 200 mm long was attached. Then, the release paper was peeled off the other side, and the tape was attached to the stainless steel plate and pressed down. Subsequently, the 180° peel strength was measured using a tensile testing machine under 23°C or 80°C atmospheres and a tensile speed of 300 mm / min. The measurement results are shown in Tables 1 and 2.

[0073] (Tensile breaking strength) The tensile breaking strength in the longitudinal direction of double-sided adhesive tape was measured. First, the double-sided adhesive tape was punched out to a width of 20 mm and a length of 200 mm. After removing the release paper from both sides, the tensile breaking strength was measured using a tensile testing machine at a tensile speed of 300 mm / min and in a 23°C atmosphere. The measurement results are shown in Tables 1 and 2.

[0074] (Glue residue) After measuring the adhesive strength of the double-sided adhesive tape to the SUS plate under the aforementioned 23°C atmosphere, the adhesive residue on the surface of the SUS plate after removing the double-sided adhesive tape was checked. Specifically, the surface of the SUS plate was photographed, and the area of ​​adhesive residue was measured by image analysis. The measurement results were evaluated according to the following criteria, and the results are shown in Tables 1 and 2. ○: The area where adhesive residue remains is less than 50% of the area where the double-sided adhesive tape is applied. ×: The area where adhesive residue remains is 50% or more of the area where the double-sided adhesive tape is applied. Cutting: During the measurement of adhesive strength, the substrate cut, making it impossible to measure adhesive residue. The "×" rating includes cases where only the adhesive layer remained on the surface of the SUS plate, and cases where a portion of the base material layer and the adhesive layer remained due to cracking of the core material. The evaluation results are shown in Tables 1 and 2.

[0075] (Evaluation results) In Examples 1-9, less adhesive residue was observed compared to Comparative Examples 1-6. Furthermore, the double-sided adhesive tapes of Examples 1-9 exhibited good adhesive strength and tensile breaking strength. Therefore, it is considered that the double-sided adhesive tapes of Examples 1-9 exhibited excellent anchoring properties between the base material layer and the adhesive layer, resulting in less adhesive residue when peeled from the adherend.

[0076] [Table 1]

[0077] [Table 2]

[0078] Although various embodiments of the present invention have been described above, these are presented as examples only and are not intended to limit the scope of the invention. These novel embodiments can be implemented in a variety of other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their variations are included in the scope and spirit of the invention, as well as in the claims of the invention and its equivalents. [Explanation of Symbols]

[0079] 1: Double-sided adhesive tape 2: Base material layer 3: Adhesive layer 4: Release paper

Claims

1. It is a double-sided adhesive tape, A base layer composed of a base material, The substrate layer comprises an adhesive layer composed of an adhesive composition on both sides. The aforementioned substrate is a nonwoven fabric containing polyester fibers. The adhesive composition comprises, when the total adhesive composition is 100 parts by mass, 45 to 55 parts by mass of a styrene-butadiene block copolymer in which the butadiene portion is partially hydrogenated, 5 to 15 parts by mass of a first tackifier, 10 to 40 parts by mass of a second tackifier, and 10 to 30 parts by mass of a third tackifier. The styrene-butadiene block copolymer has a styrene monomer unit content of 5 to 50% by mass. The first tackifier is a terpene-based resin that is liquid at 23°C. The second tackifier is a terpene-based resin with a softening point of 120°C or lower. The third tackifier is a terpene phenol resin with a softening point of 135°C or higher. A double-sided adhesive tape having an arithmetic mean height Sa of 1 to 15 μm on the surface of the adhesive layer according to ISO 25178.

2. The double-sided adhesive tape according to claim 1, wherein the tensile breaking strength in the longitudinal direction of the double-sided adhesive tape according to JIS Z0237 is 5 to 50 N / 20 mm.

3. The basis weight of the aforementioned substrate is 5 to 20 g / m². ２ The double-sided adhesive tape according to claim 1 or claim 2.

4. The density of the aforementioned substrate is 0.3 to 0.7 g / cm³. ３ The double-sided adhesive tape according to claim 1 or claim 2.

5. The double-sided adhesive tape according to claim 1 or claim 2, wherein the thickness of the base material is 15 to 40 μm.

6. The adhesive composition is applied to one side of the substrate layer at a rate of 80 to 100 g / m². ２ The double-sided adhesive tape according to claim 1 or claim 2, provided in an amount of [amount missing].

7. A method for manufacturing a double-sided adhesive tape according to claim 1 or claim 2, The process involves applying the adhesive composition to the release surface of the release paper using a hot melt coating method. A manufacturing method comprising the step of forming the adhesive layer on both sides of the substrate layer by bonding and transferring the adhesive composition, which has been hot-melted onto the release paper, to the substrate.

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