Double-sided adhesive tape and method for manufacturing the same

Abstract

The present invention provides a double-sided adhesive tape that allows for quick peeling of the release film during bonding, easy peeling of only one of the release films, and less likelihood of lifting or other issues occurring between the release film and the adhesive layer even when a roll is formed. [Solution] The double-sided adhesive tape of the present invention has a first release film, an adhesive layer, and a second release film laminated in this order. T1≧T2 (1) (In equation (1), T1 is the thickness of the first release film (μm), and T2 is the thickness of the second release film (μm)) And, P1≧P2 (2) (In equation (2), P1 represents the 180° peel strength (mN / 50mm) of the first release film, and P2 represents the 180° peel strength (mN / 50mm) of the second release film), provided that when T1=T2, P1>P2, and when P1=P2, T1>T2, the adhesive layer has a predetermined adhesive strength.

Description

Technical Field

[0001] The present invention relates to a double-sided pressure-sensitive adhesive tape and a method for producing the same. Background Art

[0002] Double-sided pressure-sensitive adhesive tapes are widely applied to various uses, such as the use of laminating various members including electronic members, semiconductor members, architectural members and the like. For example, Patent Document 1 discloses a double-sided adhesive tape having excellent strength even when it is thin.

[0003] Such a double-sided pressure-sensitive adhesive tape is formed, for example, to include a pair of release films (mold release films) and a pressure-sensitive adhesive layer interposed between the pair of release films. When laminating members (adherends), for example, one release film is peeled from the double-sided pressure-sensitive adhesive tape, and the exposed pressure-sensitive adhesive layer is laminated to an adherend. Then, another adherend is laminated to the pressure-sensitive adhesive layer exposed by peeling the other release film, whereby the adherends can be laminated to each other. Generally, in order to facilitate the peeling of the pressure-sensitive adhesive layer from the release films, each of the pair of release films is subjected to a release treatment on one side to form a release-treated surface. Prior Art Documents Patent Documents

[0004] Patent Document 1 Japanese Unexamined Patent Application Publication No. 2005-105212 Summary of the Invention Problems to be Solved by the Invention

[0005] When joining components together with double-sided adhesive tape, workability is also important. For example, when peeling the release film from the double-sided adhesive tape, it is required that the release film can be peeled off quickly, and that only one side of the release film can be easily peeled off, preventing the so-called "separation" phenomenon. In addition, in the manufacture of double-sided adhesive tape, it is common to wind the tape onto a roll, and it is required that such a roll does not easily develop lifting or other issues between the release film and the adhesive layer. In particular, it has been difficult to meet these requirements with double-sided adhesive tapes that use adhesives that do not easily develop the desired adhesive strength at room temperature.

[0006] The present invention has been made in view of the above, and aims to provide a double-sided adhesive tape and a method for manufacturing the same that, even when equipped with an adhesive that does not easily exhibit adhesive strength at room temperature, allows for the rapid peeling of the release film during bonding, allows for easy peeling of only one of the release films, and furthermore, makes it difficult for lifting or other issues to occur between the release film and the adhesive layer even when a roll body is formed. [Means for solving the problem]

[0007] The inventors of the present invention conducted extensive research to achieve the above objective and, as a result, discovered that the above objective can be achieved by adjusting the thickness and peeling force of a pair of release films and the adhesive force of the adhesive layer to a predetermined range, thereby completing the present invention.

[0008] In other words, the present invention encompasses, for example, the subject matter described in the following sections. Item 1 A double-sided adhesive tape in which a first release film, an adhesive layer, and a second release film are laminated in this order, The following formula (1) T1≧T2 (1) (In equation (1), T1 represents the thickness (μm) of the first release film, and T2 represents the thickness (μm) of the second release film.) And, the following equation (2) P1≧P2 (2) (In equation (2), P1 is measured in accordance with JIS Z 0237 and represents the 180° peel strength (mN / 50mm) of the polyester adhesive tape against the release surface of the first release film, and P2 is measured in accordance with JIS Z 0237 and represents the 180° peel strength (mN / 50mm) of the polyester adhesive tape against the release surface of the second release film.) Satisfying the conditions, However, when T1=T2, P1>P2, When P1=P2, T1>T2, The adhesive layer is a double-sided adhesive tape in which the adhesive strength A1 measured by the adhesive strength measurement method A1 below is less than 6.5 N / 20 mm, and the adhesive strength A2 measured by the adhesive strength measurement method A2 below is 6.5 N / 20 mm or more. <Method for measuring adhesive strength A1> After peeling off the second release film of the double-sided adhesive tape and bonding the corona-treated side of a 50 μm polypropylene film, which has been corona-treated on one side, to the exposed adhesive layer surface, a test sheet is prepared by passing it through a heat laminator with the roll heated to 100°C at a speed of 500 mm / min. This test sheet is cut to 20 mm x 300 mm, and the surface of the adhesive layer exposed by peeling off the first release film is bonded to a 115 mm x 50 mm polypropylene resin plate (thickness 2 mm) to prepare a test piece. The polypropylene film surface of this test piece is subjected to a bonding treatment A by passing it back and forth twice at 300 mm / min using a 2 kg pressure roll in accordance with the method of JIS Z 0237. The test piece subjected to the compression treatment A is stored in a 23°C, 50% RH environment for 30 minutes, and the polypropylene film is peeled off at a peeling angle of 180° in accordance with the method described in JIS Z 0237. The adhesive force measured at this time is defined as adhesive force A1. <Method for measuring adhesive strength A2> The aforementioned crimping process A is changed to crimping process B using a laminator heated to a roll temperature of 120°C (feed speed 500 mm / min). The test piece subjected to crimping process B is stored in a 23°C 50% RH environment for 24 hours. The polypropylene film is then peeled off at a peeling angle of 180° in accordance with the method described in JIS Z 0237, and the adhesive strength measured at this time is defined as adhesive strength A2. Section 2 The double-sided adhesive tape according to claim 1, wherein the adhesive layer contains a block copolymer containing styrene units. Section 3 Double-sided adhesive tape as described in item 1 or 2, wound in a roll shape. Section 4 A method for manufacturing double-sided adhesive tape as described in item 1 or 2, Step 1 involves applying an adhesive composition to the release-treated side of the first release film to form the adhesive layer, Step 2 involves bonding the release-treated side of the second release film to the adhesive layer formed in Step 1 to obtain a double-sided adhesive tape. A method for manufacturing double-sided adhesive tape, comprising the following: Section 5 The method for manufacturing a double-sided adhesive tape according to claim 4, further comprising a step 3 of winding the double-sided adhesive tape after step 2. [Effects of the Invention]

[0009] The double-sided adhesive tape of the present invention allows for quick peeling of the release film during bonding, even when the adhesive is not easily tackled at room temperature, and also allows for easy peeling of only one of the release films. Furthermore, even when a roll is formed, it is less likely to cause lifting or other issues between the release film and the adhesive layer. [Modes for carrying out the invention]

[0010] Embodiments of the present invention will be described in detail below. In this specification, the expressions "contains" and "include" include the concepts of "contains," "includes," "substantially," and "consisting only of."

[0011] 1. Double-sided adhesive tape The double-sided pressure-sensitive adhesive tape of the present invention has a first release film, a pressure-sensitive adhesive layer, and a second release film laminated in this order. In particular, the double-sided pressure-sensitive adhesive tape of the present invention satisfies the following formula (1) T1≧T2 (1) (In formula (1), T1 represents the thickness (μm) of the first release film, and T2 represents the thickness (μm) of the second release film) and the following formula (2) P1≧P2 (2) (In formula (2), P1 is measured by a method in accordance with JIS Z 0237, and represents the 180° peel strength (mN / 50mm) of a polyester pressure-sensitive adhesive tape against the release surface of the first release film; P2 is measured by a method in accordance with JIS Z 0237, and represents the 180° peel strength (mN / 50mm) of a polyester pressure-sensitive adhesive tape against the release surface of the second release film) , provided that P1>P2 when T1=T2, and T1>T2 when P1=P2.

[0012] Further, in the double-sided pressure-sensitive adhesive tape of the present invention, the adhesive force A1 measured by adhesive force measurement method A1 is less than 6.5 N / 20 mm, and the adhesive force A2 measured by adhesive force measurement method A2 is 6.5 N / 20 mm or more.

[0013] The double-sided pressure-sensitive adhesive tape of the present invention enables the release film to be rapidly peeled off during bonding because the thickness and peeling force of the pair of release films are adjusted within predetermined ranges, and the adhesive force of the pressure-sensitive adhesive layer is adjusted within a predetermined range. In addition, with the double-sided pressure-sensitive adhesive tape of the present invention, only one release film can be easily peeled off, and the so-called "uneven peeling" phenomenon is less likely to occur. In particular, even when the double-sided pressure-sensitive adhesive tape of the present invention includes a pressure-sensitive adhesive that hardly exhibits adhesive force at normal temperature (for example, 25°C), the release film can be rapidly peeled off during bonding, only one release film can be easily peeled off, and furthermore, even when formed into a roll, lifting or the like is less likely to occur between the release film and the pressure-sensitive adhesive layer. Moreover, even when the double-sided pressure-sensitive adhesive tape of the present invention is formed into a roll, lifting or tunneling is less likely to occur between the release film and the pressure-sensitive adhesive layer.

[0014] In addition, the double-sided pressure-sensitive adhesive tape of the present invention can be easily produced. For example, even when producing a roll, the phenomenon of the release film lifting from the pressure-sensitive adhesive layer during winding (so-called tunneling) is less likely to occur, and wrinkling is also less likely to occur.

[0015] (Release Film) The double-sided pressure-sensitive adhesive tape of the present invention has a pair of release films. Such a pair of release films are directly bonded to both surfaces of the pressure-sensitive adhesive layer, and are films that play a role in protecting the pressure-sensitive adhesive layer. As described above, in the present invention, one release film is referred to as a first release film, and the other release film is referred to as a second release film.

[0016] In the present invention, T1≧T2 and P1≧P2, provided that P1>P2 when T1=T2, and T1>T2 when P1=P2. Accordingly, the double-sided pressure-sensitive adhesive tape of the present invention enables rapid peeling of the release film during lamination, is less prone to the occurrence of uneven peeling, and even when formed into a roll, can make it difficult for lifting or the like to occur between the release film and the pressure-sensitive adhesive layer. Here, T1 is the thickness (μm) of the first release film, T2 is the thickness of the second release film, P1 is the 180° peel strength (mN / 50mm) of a polyester pressure-sensitive adhesive tape against the release surface of the first release film, measured by a method in accordance with JIS Z 0237, and P2 is the 180° peel strength (mN / 50mm) of a polyester pressure-sensitive adhesive tape against the release surface of the second release film, measured by a method in accordance with JIS Z 0237.

[0017] When T1<T2 or P1<P2, it is difficult to rapidly peel the release film, and the phenomenon of uneven peeling is also prone to occur.

[0018] T1 (the thickness of the first release film) is preferably 20 µm or more, more preferably 30 µm or more, particularly preferably 45 µm or more, and is preferably 150 µm or less, more preferably 100 µm or less, still more preferably 80 µm or less.

[0019] T2 (the thickness of the second release film) is preferably 10 µm or more, more preferably 20 µm or more, particularly preferably 35 µm or more, and is preferably 120 µm or less, more preferably 80 µm or less, still more preferably 60 µm or less.

[0020] P1 (the 180° peel strength of the polyester adhesive tape against the release surface of the first release film) is preferably 100 mN / 50 mm or more, more preferably 200 mN / 50 mm or more, particularly preferably 300 mN / 50 mm or more, and also preferably 7000 mN / 50 mm or less, more preferably 5500 mN / 50 mm or less, even more preferably 3000 mN / 50 mm or less, and particularly preferably 1000 mN / 50 mm or less.

[0021] P2 (the 180° peel strength of the polyester adhesive tape against the release surface of the second release film) is preferably 100 mN / 50 mm or more, more preferably 200 mN / 50 mm or more, particularly preferably 300 mN / 50 mm or more, and preferably 1000 mN / 50 mm or less.

[0022] The above values ​​T1 and T2 can be measured, for example, using a commercially available thickness measuring device.

[0023] The above P1 and P2 can be measured by a method in accordance with JIS Z 0237. Specifically, P1 and P2 can be measured by measuring the 180° peel strength on the release surface of the release film using a polyester adhesive tape (for example, Nitto Denko 31B tape) in accordance with JIS Z 0237. Polyester adhesive tape refers to a tape in which an acrylic adhesive is formed on a polyester base material, and in this invention, Nitto Denko 31B tape is used. The release surface refers to the surface to which the first release film and the second release treatment have been applied, as described later, and is sometimes referred to as the release treatment surface.

[0024] The method for adjusting P1 and P2 is not particularly limited, and known methods can be widely adopted, for example.

[0025] In the double-sided adhesive tape of the present invention, the release film can use a substrate that has been treated with a release agent on at least one side. That is, the release film can use a substrate that has a release agent layer formed on at least one side. In this specification, the release surface means the surface on which the release agent layer is formed. Such a release surface is formed so that it can be easily peeled off from the adhesive layer even when it is bonded to the adhesive layer.

[0026] Examples of substrates include resin films and paper. Examples of resin films include polyethylene terephthalate, polybutylene terephthalate, polyethylene, polypropylene, polyarylate, and polyester, while examples of paper include polyethylene laminated paper, polypropylene laminated paper, clay-coated paper, resin-coated paper, and glassine paper.

[0027] The mold release layer can be formed, for example, by known methods. For example, the mold release layer can be formed from various resins. Such resins include, for example, silicone resins, long-chain alkyl resins, fluororesins, and the like.

[0028] Silicone release agents can be cured by heat condensation, heat addition, or UV curing. Examples of heat condensation release agents include those obtained by reacting polydimethylsiloxane and polymethylhydrosiloxane with an organotin catalyst, while examples of heat addition release agents include those obtained by reacting vinyl group-containing polydimethylsiloxane and polymethylhydrogensiloxane with a platinum catalyst. Examples of UV curing release agents include those obtained by polymerizing epoxy group-containing modified silicone by photocationic polymerization. To adjust the release properties, MQ resin, vinyl group-containing silicone resin, silicone oil, silane coupling agents, leveling agents, etc., may be added to the silicone release agent. The thickness may also be adjusted to adjust the release force.

[0029] The method for manufacturing the release film is not particularly limited; for example, it can be manufactured by known methods, or commercially available products can be used. The first and second release films can be any grade in which the 180° peel strength of Nitto Denko's 31B tape against the release surface falls within the above range. For example, release films from Oji F-Tex can be widely used, as well as release films from Toyobo, Mitsubishi Chemical, Fujimori Industries, Toray Film Processing, Nippa, Nakamoto Pax, and others.

[0030] When applying commercially available release films to the double-sided adhesive tape of the present invention, the first and second release films can be selected such that the combination satisfies T1≧T2 and P1≧P2 (where P1>P2 when T1=T2, and T1>T2 when P1=P2).

[0031] (Adhesive layer) In the double-sided adhesive tape of the present invention, the adhesive layer has an adhesive strength A1 measured by the <Method A1 for measuring adhesive strength> described below that is less than 6.5 N / 20 mm, and an adhesive strength A2 measured by the <Method A2 for measuring adhesive strength> that is 6.5 N / 20 mm or more.

[0032] <Method for measuring adhesive strength A1> After peeling off the second release film of the double-sided adhesive tape and bonding the corona-treated side of a 50 μm polypropylene film, which has been corona-treated on one side, to the exposed adhesive layer surface, a test sheet is prepared by passing it through a heat laminator with the roll heated to 100°C at a speed of 500 mm / min. This test sheet is cut to 20 mm x 300 mm, and the surface of the adhesive layer exposed by peeling off the first release film is bonded to a 115 mm x 50 mm polypropylene resin plate (thickness 2 mm) to prepare a test piece. The polypropylene film surface of this test piece is subjected to a bonding treatment A by passing it back and forth twice at 300 mm / min using a 2 kg pressure roll in accordance with the method of JIS Z 0237. The test piece subjected to the compression treatment A is stored in a 23°C, 50% RH environment for 30 minutes, and the polypropylene film is peeled off at a peeling angle of 180° in accordance with the method described in JIS Z 0237. The adhesive force measured at this time is defined as adhesive force A1.

[0033] <Method for measuring adhesive strength A2> The aforementioned crimping process A is changed to crimping process B using a laminator heated to a roll temperature of 120°C (feed speed 500 mm / min). The test piece subjected to crimping process B is stored in a 23°C 50% RH environment for 24 hours. The polypropylene film is then peeled off at a peeling angle of 180° in accordance with the method described in JIS Z 0237, and the adhesive strength measured at this time is defined as adhesive strength A2. Specifically, the second release film of the double-sided adhesive tape is peeled off to expose the adhesive layer surface, and the corona-treated side of a 50 μm polypropylene film, which has been corona-treated on one side, is bonded to this surface. Then, the sheet is passed through a heat laminator with the roll heated to 100°C at a speed of 500 mm / min to produce a test sheet. This test sheet is cut to 20 mm x 300 mm, and the surface of the adhesive layer exposed by peeling off the first release film is bonded to a 115 mm x 50 mm polypropylene resin plate (thickness 2 mm) to produce a test piece. The polypropylene film surface of this test piece is subjected to bonding treatment A by passing it back and forth twice at 300 mm / min using a 2 kg pressure roll in accordance with the method of JIS Z 0237, and then bonding treatment B is performed by passing it back and forth twice at 300 mm / min using a laminator with the roll temperature heated to 120°C (feed speed 500 mm / min). The test piece subjected to the compression treatment B is stored for 24 hours in a 23°C 50%RH environment. The polypropylene film is then peeled off at a peeling angle of 180° in accordance with the method described in JIS Z 0237, and the adhesive strength measured at this time is defined as adhesive strength A2. Compression treatment B means that after compression treatment A, the piece is further processed by passing it back and forth twice at 300 mm / min using a laminator (feed speed 500 mm / min) heated to a roll temperature of 120°C.

[0034] The double-sided adhesive tape of the present invention, by comprising the adhesive layer, has increased adhesive strength to various substrates, and in particular, can further enhance adhesive strength to polypropylene film. For example, the double-sided adhesive tape of the present invention can improve the adhesion between metal foil such as copper and polypropylene film.

[0035] In particular, having the adhesive strength A1 within the above range prevents the peeling force of the first release film from becoming too heavy, and having the adhesive strength A2 within the above range makes it easier to achieve sufficient adhesion to the substrate. The lower limit of the adhesive strength A1 is not particularly limited; for example, it may be 0.1 N / 25 mm or higher, or 0.2 N / 25 mm or higher.

[0036] The adhesive layer can be formed from various resins, as long as it has the adhesive strength described above. An example of an adhesive layer having the adhesive strength described above is a block copolymer containing styrene units. In this case, the double-sided adhesive tape of the present invention allows for quick peeling of the release film during bonding, reduces the likelihood of separation, and also reduces the likelihood of lifting or other issues occurring between the release film and the adhesive layer even when a roll is formed.

[0037] Examples of block copolymers containing styrene units include blocks composed of isopentane-derived structures and block copolymers composed of styrene-based polymers. Examples of isopentane-derived structures include propylene-ethylene copolymers.

[0038] In block copolymers containing styrene units, examples of blocks composed of styrene polymers include blocks composed of styrene polymers and α-methylstyrene polymers.

[0039] A block copolymer containing styrene units may include blocks composed of other polymers in addition to blocks composed of isopentane-derived structures and blocks composed of styrene-based polymers. Examples of blocks composed of other polymers include blocks composed of ethylene-derived structures, or blocks composed of acrylic acid ester polymers or methacrylic acid ester polymers.

[0040] In a block copolymer containing styrene units, if a block composed of isopentane-derived structures is denoted as A, and a block composed of a styrene-based polymer is denoted as B, the block copolymer may be a diblock copolymer with an AB structure, or a triblock copolymer with an ABA structure or a BAB structure. It may also be a block copolymer having a repeating structure of each block, such as an -ABAB- structure. Furthermore, as described above, it may be a block copolymer further containing blocks composed of other polymers.

[0041] The melt flow rate (MFR) of a block copolymer containing styrene units, measured under the conditions of 200°C and 10 kg, can range from, for example, "No Flow" to 150 g / 10 min, preferably from "No Flow" to 120 g / 10 min. When the MFR is within these ranges, the double-sided adhesive tape of the present invention exhibits excellent adhesive performance, making it easier to control the adhesive strengths A1 and A2 within the desired range.

[0042] Block copolymers containing styrene units can be obtained by polymerization using known methods, or commercially available products can be used. Examples of commercially available block copolymers containing styrene units include the Septon® series manufactured by Kuraray Co., Ltd.

[0043] The adhesive layer may contain other resins in addition to block copolymers containing styrene units, such as terpene phenol resins and other aromatic resins.

[0044] Terpene phenol resins are, for example, resins obtained by copolymerizing terpene monomers and phenols. The softening point of terpene phenol resins is preferably 125°C or higher, more preferably 130°C or higher. Furthermore, the softening point of terpene phenol resins is preferably 170°C or lower, more preferably 165°C or lower, and even more preferably 160°C or lower. The softening point of terpene phenol resins is the value measured using an automatic softening point measuring device (FLEX SCIENTIFIC, EX-719PD4) in accordance with the method described in JIS K2207.

[0045] The number-average molecular weight of the terpene phenol resin is preferably 800 or more, more preferably 850 or more, and even more preferably 900 or more. Furthermore, the number-average molecular weight of the terpene phenol resin is preferably 1500 or less, more preferably 1400 or less, and even more preferably 1300 or less. The number-average molecular weight of the terpene phenol resin was measured by gel permeation chromatography (GPC) and converted using a calibration curve created with standard polystyrene of known molecular weight.

[0046] Examples of commercially available terpene phenol resins include YS Polystar T130, YS Polystar T145, YS Polystar T160, YS Polystar S145, and YS Polystar G150, all manufactured by Yasuhara Chemical Co., Ltd.

[0047] Other aromatic resins include, for example, styrene polymers, specifically α-methylstyrene homopolymers, styrene homopolymers, and copolymers of α-methylstyrene and styrene. Aromatic resins can function as tackifiers, as described later.

[0048] The softening point of other aromatic resins is preferably 80°C or higher, more preferably 85°C or higher, preferably 140°C or lower, more preferably 130°C or lower, and even more preferably 120°C or lower.

[0049] The adhesive layer preferably contains a block copolymer containing at least styrene units, more preferably contains a block copolymer containing styrene units and a terpene phenol resin and / or the aromatic resin, and even more preferably contains a block copolymer containing styrene units, a terpene phenol resin and the styrene polymer.

[0050] The adhesive layer may contain additives in addition to the resin. Examples of additives include antioxidants (or anti-aging agents), silane coupling agents, tackifiers other than terpene phenol resins, oil components, softeners, crosslinking agents, pigments, hydrogen abstraction initiators, and the like.

[0051] Examples of antioxidants include phenolic antioxidants, amine antioxidants, lactone antioxidants, phosphorus antioxidants, and sulfur antioxidants. These antioxidants may be used individually or in combination of two or more types.

[0052] Examples of silane coupling agents include mercapto-based silane coupling agents containing a mercapto group, epoxy-based silane coupling agents having an epoxy group, and vinyl-based silane coupling agents having a vinyl group. Among these, it is preferable to use a mercapto-based silane coupling agent. Examples of mercapto-based silane coupling agents include mercaptotrimethoxysilane, mercaptomethyltrimethoxysilane, mercaptomethyltriethoxysilane, triethoxy(2-mercaptoethyl)silane, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 3-mercaptopropylmethyldimethoxysilane, 4-mercaptobutyltrimethoxysilane, 10-mercaptodecyltriethoxysilane, 11-mercaptondecyltrimethoxysilane, and 11-mercaptondecyltriethoxysilane.

[0053] Paraffin-based or naphthenic system oils are preferred as oil components, and paraffin-based system oils are more preferably used because they are less likely to cause rubber degradation.

[0054] Examples of hydrogen abstraction initiators include benzophenone compounds such as methyl benzoylmate and 4-methylbenzophenone.

[0055] In the adhesive layer, when a block copolymer containing styrene units is used, the content is preferably 20 parts by mass or more, more preferably 30 parts by mass or more, even more preferably 40 parts by mass or more, particularly preferably 45 parts by mass or more, and also preferably 90 parts by mass or less, more preferably 80 parts by mass or less, even more preferably 70 parts by mass or less, and particularly preferably 60 parts by mass or less, based on 100 parts by mass of the total mass of the adhesive layer.

[0056] In the adhesive layer, when a terpene phenol resin is used in combination, the content is preferably 10 parts by mass or more, more preferably 20 parts by mass or more, even more preferably 30 parts by mass or more, particularly preferably 35 parts by mass or more, and may be 100 parts by mass or less, preferably 100 parts by mass or less, more preferably 90 parts by mass or less, even more preferably 80 parts by mass or less, even more preferably 60 parts by mass or less, and even more preferably 50 parts by mass or less.

[0057] In the adhesive layer, the content of the other aromatic resin may be 0 parts by mass, more preferably 0.1 parts by mass or more, even more preferably 0.1 parts by mass or more, particularly preferably 5 parts by mass or more, preferably 30 parts by mass or less, more preferably 20 parts by mass or less, and even more preferably 15 parts by mass or less.

[0058] In the adhesive layer, the content of the additive is preferably 10 parts by mass or less, more preferably 5 parts by mass or less, and even more preferably 1 part by mass or less, based on 100 parts by mass of the total mass of the adhesive layer.

[0059] In the adhesive layer, the resin content is preferably 80% by mass or more, more preferably 90% by mass or more, even more preferably 95% by mass or more, and particularly preferably 99% by mass or more.

[0060] The thickness of the adhesive layer is not particularly limited, but is preferably 5 μm or more, more preferably 10 μm or more, even more preferably 20 μm or more, and also preferably 500 μm or less, more preferably 300 μm or less, even more preferably 200 μm or less, and particularly preferably 100 μm or less.

[0061] The adhesive layer may be a single layer or a multilayer structure.

[0062] The method for forming the adhesive layer is not particularly limited, and for example, a wide range of known methods can be employed. For example, as described below, the adhesive layer can be manufactured using an adhesive composition.

[0063] (Double-sided adhesive tape) As described above, the double-sided adhesive tape of the present invention is a laminate in which a first release film, an adhesive layer, and a second release film are laminated in that order. In particular, the double-sided adhesive tape of the present invention allows for quick peeling of the release film during bonding by adjusting the thickness and peeling force of the pair of release films to a predetermined range, and by adjusting the adhesive force of the adhesive layer to a predetermined range. Furthermore, with the double-sided adhesive tape of the present invention, only one of the release films can be easily peeled off, making the so-called "separation" phenomenon less likely to occur. For this reason, by using the double-sided adhesive tape of the present invention, the efficiency of bonding work between components (adherents) can be improved.

[0064] The double-sided adhesive tape of the present invention may be wound into a roll shape. That is, the double-sided adhesive tape of the present invention can be formed into a roll. The method of forming the roll is not particularly limited, and for example, the roll of the double-sided adhesive tape of the present invention can be formed by step 3 described below.

[0065] The method for manufacturing the double-sided adhesive tape of the present invention is not particularly limited, and can be manufactured by, for example, a manufacturing method comprising the following steps 1 and 2. Step 1: A step of applying an adhesive composition to the release treatment side of the first release film to form the adhesive layer. Step 2: A step to obtain a double-sided adhesive tape by bonding the release-treated side of the second release film to the adhesive layer formed in Step 1.

[0066] In step 1, an adhesive composition is applied to the release-treated side of the first release film (i.e., the release surface). Specifically, a liquid adhesive composition, either dissolved in a solvent (solvent-based adhesive composition) or melted by heating (hot-melt adhesive composition), is applied to the release film, and an adhesive layer can be formed by drying the solvent component (solvent-based adhesive composition) or cooling it (hot-melt adhesive composition).

[0067] The adhesive composition used in step 1 is a raw material for forming an adhesive layer, and is a raw material containing the resin and, optionally, additives. To improve the coating properties of the adhesive composition, it is preferable that the adhesive composition contains a solvent.

[0068] Examples of solvents include hydrocarbons such as hexane, heptane, octane, toluene, xylene, ethylbenzene, cyclohexane, and methylcyclohexane; halogenated hydrocarbons such as dichloromethane, trichloroethane, trichloroethylene, tetrachloroethylene, and dichloropropane; alcohols such as methanol, ethanol, propanol, isopropyl alcohol, butanol, isobutyl alcohol, and diacetone alcohol; ethers such as diethyl ether, diisopropyl ether, dioxane, and tetrahydrofuran; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, isophorone, and cyclohexanone; esters such as methyl acetate, ethyl acetate, butyl acetate, isobutyl acetate, amyl acetate, and ethyl butyrate; and polyols and their derivatives such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monomethyl ether acetate, propylene glycol monomethyl ether, propylene glycol monoethyl ether, and propylene glycol monomethyl ether acetate.

[0069] If the adhesive composition contains a solvent, the amount is not particularly limited, but is preferably 25 to 500 parts by mass, and more preferably 30 to 400 parts by mass, per 100 parts by mass of resin.

[0070] The adhesive composition can be coated using known coating equipment. Examples of coating equipment include blade coaters, air knife coaters, roll coaters, bar coaters, gravure coaters, microgravure coaters, rod blade coaters, lip coaters, die coaters, and curtain coaters.

[0071] If the adhesive composition contains a solvent, the adhesive composition can be applied to the release-treated side of the first release film, and then the solvent can be dried using an appropriate drying method. This forms an adhesive layer on the release film.

[0072] In step 2, the side of the second release film that has been treated for mold release is bonded (laminated) to the adhesive layer formed in step 1. This makes it possible to obtain a double-sided adhesive tape in which the first release film, the adhesive layer, and the second release film are laminated in this order.

[0073] As described above, the double-sided adhesive tape of the present invention can be made into a roll. Therefore, in the method for manufacturing the double-sided adhesive tape, after manufacturing the double-sided adhesive tape through steps 1 and 2, the double-sided adhesive tape can be formed into a roll. That is, the method for manufacturing the double-sided adhesive tape can include the following step 3. Step 3: After step 2, the process of wrapping double-sided adhesive tape around the tape.

[0074] In step 3, the method of winding the double-sided adhesive tape is not particularly limited, and a wide range of known methods can be adopted in the present invention. In the double-sided adhesive tape of the present invention, it is preferable to wind the tape so that the first release film is inside the winding (i.e., positioned on the inside). In this case, the occurrence of lifting or tunneling between the release film and the adhesive layer becomes particularly unlikely.

[0075] In step 3, for example, a roll can be formed by winding the double-sided adhesive tape of the present invention around a roll-shaped core. Alternatively, a roll can also be formed by winding the double-sided adhesive tape without using a core.

[0076] The double-sided adhesive tape of the present invention is less prone to the phenomenon of the release film lifting away from the adhesive layer during winding (so-called tunnel formation), and is also less prone to wrinkle formation.

[0077] When winding the double-sided adhesive tape of the present invention into a roll shape, it is preferable to wind it so that the first release film is inside the winding (i.e., positioned on the inside). In this case, the occurrence of lifting or tunneling between the release film and the adhesive layer becomes particularly unlikely.

[0078] As described above, the roll of double-sided adhesive tape of the present invention can be easily manufactured by a method comprising steps 1, 2, and 3, and is less prone to the phenomenon of the release film lifting away from the adhesive layer during winding (so-called tunnel formation), and is also less prone to wrinkle formation.

[0079] The double-sided adhesive tape of the present invention offers excellent workability because the release film can be quickly peeled off during bonding, and only one side of the release film can be easily peeled off. Furthermore, even when the double-sided adhesive tape of the present invention is formed into a roll, lifting or tunneling between the release film and the adhesive layer is less likely to occur. Even when manufacturing a roll, the phenomenon of the release film lifting from the adhesive layer (so-called tunneling) during winding is less likely to occur, and wrinkle formation is also less likely. Therefore, the double-sided adhesive tape of the present invention can be applied to various uses, for example, in bonding metal foil such as copper to a polypropylene film, or in bonding a decorative film having a design layer formed by printing, etc., to a polypropylene film. In particular, it exhibits excellent adhesive performance when bonding to three-dimensional polypropylene resin molded bodies using TOM molding, vacuum forming, etc.

[0080] In specifying the inventions included in this disclosure, the components (properties, structure, function, etc.) described in each embodiment of this disclosure may be combined in any way. That is, this disclosure includes, This specification encompasses all subjects consisting of any combination of each combinatable configuration described herein. [Examples]

[0081] The present invention will be described more specifically below with reference to examples, but the present invention is not limited to the embodiments of these examples. The peel strength of the first release film and the second release film was measured by the method in accordance with JIS Z 0237 as described above, and represents the 180° peel strength of the polyester adhesive tape against the release surface.

[0082] (Manufacturing Example 1; Adhesive Composition) Adhesive composition 1 was obtained by dissolving 100 parts by mass of thermoplastic resin (Kuraray Co., Ltd., Septon 2005, MFR@200℃, 10kg: No Flow), 100 parts by mass of terpene phenol resin (Yasuhara Chemical Co., Ltd., YS Polystar T130, softening point 130℃), and 0.6 parts by mass of antioxidant (BASF, IRGANOX1010) in toluene to a solid content concentration of 30% by mass. (Manufacturing Example 2; Adhesive Composition) Adhesive composition 2 was obtained by dissolving 100 parts by mass of thermoplastic resin (Kuraray Co., Ltd., Septon 2002, MFR@200℃, 10kg:100g / 0min), 95 parts by mass of terpene phenol resin (Yasuhara Chemical Co., Ltd., YS Polystar T130, softening point 130℃), 5 parts by mass of aromatic resin (Mitsui Chemicals, Inc., FTR8100, softening point 100℃), and 0.6 parts by mass of antioxidant (BASF, Inc., IRGANOX1010) in toluene to a solid content concentration of 50% by mass.

[0083] (Example 1) A roll-shaped double-sided adhesive tape (roll of double-sided adhesive tape) was manufactured using a coating machine equipped with a first paper feed section, a die coater head, a drying oven, a second paper feed section, and a laminating machine. First, a roll-shaped first release film, RL-07(7)#50 (manufactured by Oji F-Tex Co., Ltd., 50 μm thick, 180° peel strength 580 mN / 50 mm), with a width of 1000 mm and a length of 1000 m, was set in the first paper feed section. The adhesive composition 1 prepared above was then coated onto the release treatment side of this first release film using the die coater head, with a coating width of 980 mm and a thickness of 30 μm for the adhesive layer after drying. As a result, 10 mm of uncoated adhesive areas were formed at both ends of the first release film. Next, the solvent was evaporated in the drying oven attached to the coating machine to dry the film and form an adhesive layer (step 1).

[0084] Next, the second release film, RL-07(4)#38 (manufactured by Oji F-Tex Co., Ltd., 38 μm thick, 180° peel strength 375 mN / 50 mm), in a roll shape measuring 1000 mm wide x 1000 m long, which was set in the second paper feed section, was laminated onto the adhesive layer that came out of the drying oven, with the release layer side of the second release film in contact (Step 2). The lamination was performed using a laminating machine attached to the coating machine. After that, the first release film was wound onto an ABS core measuring 3 inches in diameter and 1050 mm wide, with the first release film inside the winding (Step 3). At this time, the winding was done so that 25 mm of the film protruded from each end of the core. When the winding length reached 500 m, it was cut, and the end of the winding was secured with tape at three points at equal intervals to prevent the winding from loosening. In this way, a roll-shaped double-sided adhesive tape was produced in which the first release film, adhesive layer, and second release film were laminated in this order.

[0085] (Example 2) Except for changing the second release film to RL-07(4)#50 (manufactured by Oji F-Tex Co., Ltd., 50 μm thick, 180° peel strength 375 mN / 50 mm), a double-sided adhesive tape was prepared in the same manner as in Example 1, with the first release film, adhesive layer, and second release film laminated in this order.

[0086] (Example 3) A double-sided adhesive tape was prepared in the same manner as in Example 1, except that adhesive composition 2 was used instead of adhesive composition 1, and the second release film was changed to RL-07(7)#38 (manufactured by Oji F-Tex Co., Ltd., thickness 38 μm, 180° peel strength 580 mN / 50 mm). The tape consisted of a first release film, an adhesive layer, and a second release film laminated in this order.

[0087] (Comparative Example 1) Except for changing the first release film to RL-07(4)#50 (manufactured by Oji F-Tex Co., Ltd., 50 μm thick, 180° peel strength 375 mN / 50 mm) and the second release film to RL-07(7)#38 (manufactured by Oji F-Tex Co., Ltd., 38 μm thick, 180° peel strength 580 mN / 50 mm), a double-sided adhesive tape was prepared in the same manner as in Example 1, with the first release film, adhesive layer, and second release film laminated in this order.

[0088] (Comparative Example 2) A double-sided adhesive tape was prepared in the same manner as in Example 1, with the first release film, adhesive layer, and second release film laminated in that order, except that the first release film was changed to RL-07(4)#50 (manufactured by Oji F-Tex Co., Ltd., thickness 50 μm, 180° peel strength 375 mN / 50 mm) and the second release film was also changed to RL-07(4)#50 (manufactured by Oji F-Tex Co., Ltd., thickness 50 μm, 180° peel strength 375 mN / 50 mm).

[0089] (Comparative Example 3) A double-sided adhesive tape was prepared in the same manner as in Example 3, with the first release film, adhesive layer, and second release film laminated in that order, except that the first release film was changed to RL-07(4)#75 (manufactured by Oji F-Tex Co., Ltd., thickness 75 μm, 180° peel strength 375 mN / 50 mm) and the second release film was changed to RL-07(7)#75 (manufactured by Oji F-Tex Co., Ltd., thickness 75 μm, 180° peel strength 580 mN / 50 mm).

[0090] The adhesive strength A1, adhesive strength A2, manufacturing suitability, peelability of the release film, separation, and roll evaluation (presence or absence of lifting and tunneling) of the double-sided adhesive tapes obtained in each example and comparative example were evaluated using the following methods.

[0091] [Adhesion strength A1] Adhesion strength A1 was measured according to the <Method for Measuring Adhesion Strength A1> described above. Specifically, sheet-like double-sided adhesive tape was cut from the roll obtained in the examples and comparative examples. At that time, the outer three layers were cut off in accordance with the method for sampling test pieces described in JIS Z 0237. The second release film was peeled off the sheet-like double-sided adhesive tape thus obtained, and a 50 μm polypropylene film (OPP Alphan®, manufactured by Oji F-Tex Co., Ltd., 50 μm thick), which had been corona-treated on one side, was bonded to the surface of the exposed adhesive layer using a hand roller so that the corona-treated side was in contact with the adhesive layer surface, thereby obtaining a sheet. The corona treatment conditions were an output of 7 W, an electrode distance of 1 mm, and an electrode movement speed of 4.3 m / min. Next, this sheet was passed through a heat laminator with the roll heated to 100 °C at a speed of 500 mm / min to obtain a test piece sheet with improved adhesion to the polypropylene film. A test piece was prepared by cutting this test sheet to 20 mm x 300 mm, peeling off the first release film, and bonding the exposed adhesive layer surface to a 115 mm x 50 mm polypropylene resin plate (2 mm thick). The polypropylene film surface of this test piece was subjected to bonding treatment A by using a 2 kg pressure roll to pass back and forth twice at 300 mm / min in accordance with the method of JIS Z 0237. The test piece subjected to bonding treatment A was stored in a 23°C 50% RH environment for 30 minutes, and the polypropylene film was peeled off at a peeling angle of 180° in accordance with the method described in JIS Z 0237. The adhesive force measured at this time was defined as adhesive force A1.

[0092] [Adhesive strength A2] Adhesion strength A2 was measured by the aforementioned <Method for measuring adhesion strength A2>. Specifically, in the measurement of adhesion strength A1, the compression process A was changed to compression process B using a laminator heated to a roll temperature of 120°C (feed speed 500 mm / min). The test piece subjected to compression process B was stored in a 23°C 50% RH environment for 24 hours, and the polypropylene film was peeled off at a peeling angle of 180° in accordance with the method described in JIS Z 0237. The adhesion strength measured at this time was defined as adhesion strength A2.

[0093] [Manufacturing suitability] In the examples and comparative examples, between the second release film lamination in step 2 and winding onto the ABS core in step 3, visual inspection was performed to check whether any part of the release film was lifting or tunneling away from the adhesive layer, and whether any wrinkles or other phenomena occurred during winding due to lifting or other reasons. The manufacturing suitability was then evaluated according to the following criteria. ≪Judgment criteria≫ A: No floating or tunneling was observed, indicating excellent manufacturing suitability. B: Slight lifting occurred before winding onto the ABS core, but no lifting or wrinkles occurred after winding. C: Even in the roll shape after winding, lifting, tunneling, or wrinkles were observed, indicating a lack of manufacturing suitability.

[0094] (Release film peelability test) Ten test pieces measuring 50 mm x 100 mm were prepared by cutting sheet-like double-sided adhesive tape from the roll obtained in the examples and comparative examples. Next, the second release film was peeled off by hand. The time from the start of peeling to the completion of peeling the second release film was measured. This measurement was repeated 10 times, and the average time required to peel off the second release film by hand was calculated, and the ease of peeling by hand, i.e., the ease of peeling the release film, was evaluated according to the following criteria. ≪Judgment criteria≫ A: The second release film could be peeled off within 30 seconds of starting the manual peeling process, demonstrating that the release film could be removed quickly. B: It took more than 30 seconds to peel off the second release film within 60 seconds of starting the manual peeling process, so it was not possible to quickly remove the release film. C: It took more than 60 seconds to peel off the second release film after starting the manual peeling process, indicating poor manual peeling performance.

[0095] (Tearful farewell) In the above manual peeling test of the release film, when the second release film was peeled off, the laminate of the first release film and the adhesive layer was visually observed, and the separation was evaluated according to the following criteria. ≪Judgment criteria≫ A: In all 10 samples, no lifting was observed between the first release film and the adhesive layer, and the occurrence of separation was suppressed. B: One to five test specimens showed a gap between the adhesive layer and the first release film. C: Six or more test specimens showed lifting between the adhesive layer and the first release film.

[0096] (Roll evaluation (presence or absence of floating and tunnels)) From the rolls obtained in the examples and comparative examples, a 1m length of double-sided adhesive tape was pulled out in the direction of the tangential extension of the roll, and the pulled-out double-sided adhesive tape was visually inspected for any lifting or tunneling between the release film and the adhesive layer. This was repeated 10 times (total of 10m), and evaluated according to the following criteria. A: In all 10 measurements, no lifting or tunneling was observed between the first release film and the adhesive layer. B: During 10 measurements, lifting or tunneling was observed between the first release film and the adhesive layer in 1 to 5 instances. C: In 6 or more of the 10 measurements, lifting or tunneling was observed between the first release film and the adhesive layer.

[0097] (Evaluation results) Table 1 shows the composition of the first release film, the second release film, and the adhesive layer used in the manufacture of the double-sided adhesive tapes for each example and comparative example, as well as the evaluation results (adhesion strength A1, adhesion strength A2, manufacturing suitability, peelability of the release film, separation, roll evaluation (presence or absence of lifting and tunneling)).

[0098] Table 1 shows that the double-sided adhesive tapes obtained in the examples, i.e., those satisfying T1≧T2 and P1≧P2 (where P1>P2 when T1=T2, and T1>T2 when P1=P2), allowed for quick peeling of the release film during bonding. Furthermore, the double-sided adhesive tapes obtained in the examples allowed for easy peeling of only one of the release films (suppressing separation). Moreover, the double-sided adhesive tapes obtained in the examples were less prone to lifting between the release film and the adhesive layer even when forming a roll, and were less prone to lifting or tunneling during roll formation, resulting in excellent manufacturing suitability.

[0099] [Table 1]

Claims

1. A double-sided adhesive tape in which a first release film, an adhesive layer, and a second release film are laminated in this order, The first release film and the second release film are substrates having a release treatment layer formed on one side, and the release treatment layer is at least one selected from the group consisting of silicone resins, long-chain alkyl resins, and fluororesins. The adhesive layer comprises a block copolymer containing styrene units, a terpene phenol resin, and other aromatic resins. The block copolymer containing the styrene units is a block copolymer composed of a block made from an isopentane-derived structure and a styrene-based polymer. The aforementioned terpene phenol resin has a softening point of 125°C or higher and 170°C or lower. The aromatic resin is a polymer containing styrene units, and has a softening point of 80°C or higher and 140°C or lower. The content of the block copolymer containing the styrene units is 20 parts by mass or more and 90 parts by mass or less, based on 100 parts by mass of the total mass of the adhesive layer. The content of the terpene phenol resin is 10 parts by mass or more and 100 parts by mass or less, based on 100 parts by mass of the total mass of the adhesive layer. The content of the aromatic resin is 0.1 parts by mass or more and 30 parts by mass or less, based on 100 parts by mass of the total mass of the adhesive layer. The following formula (1) T1 ≥ T2 (1) (In formula (1), T1 represents the thickness (μm) of the first release film, and T2 represents the thickness (μm) of the second release film.) And, the following equation (2) P1 ≥ P2 (2) (In formula (2), P1 is measured in accordance with JIS Z 0237 and represents the 180° peel strength (mN / 50mm) of the polyester adhesive tape against the release surface of the first release film, and P2 is measured in accordance with JIS Z 0237 and represents the 180° peel strength (mN / 50mm) of the polyester adhesive tape against the release surface of the second release film.) Satisfying the conditions, However, when T1 = T2, P1 > P2, When P1 = P2, then T1 > T2, The 180° peel strength P1 (mN / 50mm) of the polyester adhesive tape against the release surface of the first release film, measured by a method conforming to JIS Z 0237, is 100 mN / 50mm or more and 7000 mN / 50mm or less. The 180° peel strength P2 (mN / 50mm) of the polyester adhesive tape against the release surface of the second release film, measured by a method conforming to JIS Z 0237, is 100 mN / 50mm or more and 1000 mN / 50mm or less. The adhesive layer is a double-sided adhesive tape in which the adhesive strength A1 measured by the adhesive strength measurement method A1 below is less than 6.5 N / 20 mm, and the adhesive strength A2 measured by the adhesive strength measurement method A2 below is 6.5 N / 20 mm or more. <Method for measuring adhesive strength A1> After peeling off the second release film of the double-sided adhesive tape and bonding the corona-treated side of a 50 μm polypropylene film, which has been corona-treated on one side, to the exposed adhesive layer surface, a test sheet is prepared by passing it through a heat laminator with the roll heated to 100°C at a speed of 500 mm / min. This test sheet is cut to 20 mm x 300 mm, and the surface of the adhesive layer exposed by peeling off the first release film is bonded to a 115 mm x 50 mm polypropylene resin plate (thickness 2 mm) to prepare a test piece. The polypropylene film surface of this test piece is subjected to a bonding treatment A by passing it back and forth twice at 300 mm / min using a 2 kg pressure roll in accordance with the method of JIS Z 0237. The test piece subjected to the compression treatment A is stored in a 23°C 50% RH environment for 30 minutes, and the polypropylene film is peeled off at a peeling angle of 180° in accordance with the method described in JIS Z 0237. The adhesive force measured at this time is defined as adhesive force A1. <Method for measuring adhesive strength A2> After peeling off the second release film of the double-sided adhesive tape and bonding the corona-treated side of a 50 μm polypropylene film, which has been corona-treated on one side, to the exposed adhesive layer surface, a test sheet is prepared by passing it through a heat laminator with the roll heated to 100°C at a speed of 500 mm / min. This test sheet is cut to 20 mm x 300 mm, and the surface of the adhesive layer exposed by peeling off the first release film is bonded to a 115 mm x 50 mm polypropylene resin plate (thickness 2 mm) to prepare a test piece. The polypropylene film surface of this test piece is subjected to a bonding process A by passing it back and forth twice at 300 mm / min using a 2 kg bonding roll in accordance with the method of JIS Z 0237, and then a bonding process B is performed by passing it back and forth twice at 300 mm / min using a laminator (feed speed 500 mm / min) with the roll temperature heated to 120°C. The test piece subjected to the compression treatment B is stored in a 23°C, 50% RH environment for 24 hours, and the polypropylene film is peeled off at a peeling angle of 180° in accordance with the method described in JIS Z 0237. The adhesive force measured at this time is defined as adhesive force A2.

2. The double-sided adhesive tape according to claim 1, which is wound in a roll shape.

3. A method for manufacturing a double-sided adhesive tape according to claim 1 or 2, Step 1 involves applying an adhesive composition to the release-treated side of the first release film to form the adhesive layer, Step 2 involves bonding the release-treated side of the second release film to the adhesive layer formed in step 1 to obtain a double-sided adhesive tape. A method for manufacturing double-sided adhesive tape, comprising the following:

4. The method for manufacturing a double-sided adhesive tape according to claim 3, further comprising a step 3 of winding the double-sided adhesive tape after step 2.

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