Adhesive tape

Abstract

To provide a pressure-sensitive adhesive tape which is excellent in resistance against a strong alkaline solution and can be easily peeled from an adherend.SOLUTION: A pressure-sensitive adhesive tape is provided, having a base material, and a pressure-sensitive adhesive layer laminated on at least one surface of the base material. The pressure-sensitive adhesive layer contains a base polymer and a tackifier resin. The base polymer is a hydrogenated body of a block copolymer having at least a block derived from an aromatic vinyl monomer and a block derived from a conjugated diene monomer, or a block copolymer having at least a block derived from an aromatic vinyl monomer and a block derived from an olefin monomer. The tackifier resin contains a terpene phenol resin (T1) having a hydroxyl value of 50-140 mgKOH / g. In the adhesive layer, the total of contents of a terpene phenol resin (T2) having a hydroxyl value exceeding 140 mgKOH / g and a rosin ester resin (T3) is 5 pts.wt. or less based on 100 pts.wt. of the base polymer.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to an adhesive tape that is excellent in resistance to strongly alkaline solutions and can be easily peeled off from an adherend.

Background Art

[0002] Conventionally, adhesives and adhesive tapes have been widely used when fixing components in electronic devices. Further, adhesive tapes are also used as process materials in the manufacturing process of electronic devices. For example, when processing thin members in the manufacturing process of electronic devices, adhesive tapes are used to facilitate handling and prevent damage. In addition to high adhesiveness, these adhesives and adhesive tapes are required to have functions such as heat resistance, thermal conductivity, and impact resistance according to the environment of the used parts (for example, Patent Documents 1 to 3).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0004] In recent years, substrates such as printed wiring boards have been becoming thinner, and in the process of manufacturing a substrate from a copper-clad laminate, there has been a problem that the ends of the copper-clad laminate are damaged during the manufacturing process. In contrast, the problem is solved by performing the treatment with an adhesive tape attached to the ends of the copper-clad laminate for protection. Such an adhesive tape is required to be able to sufficiently protect the copper-clad laminate during the treatment and to be easily peeled off from the copper-clad laminate without damaging the copper-clad laminate after the treatment. However, in etching processes, desmear processes, etc. performed in the substrate manufacturing process, a strongly alkaline solution is used as the processing solution. In conventional adhesive tapes, when exposed to such a strongly alkaline solution, peeling easily occurs, and problems such as the inability to sufficiently protect the edges of copper-clad laminates or the corrosion of the copper on the surface of copper-clad laminates have arisen.

[0005] An object of the present invention is to provide an adhesive tape that is excellent in resistance to strongly alkaline solutions and can be easily peeled from an adherend.

Means for Solving the Problems

[0006] The present invention is an adhesive tape having a base material and an adhesive layer laminated on at least one surface of the base material, wherein the adhesive layer contains a base polymer and an adhesion-imparting resin, the base polymer is a hydrogenated product of a block copolymer having at least a block derived from an aromatic vinyl monomer and a block derived from a conjugated diene monomer, or a block copolymer having at least a block derived from an aromatic vinyl monomer and a block derived from an olefin monomer, the adhesion-imparting resin contains a terpene phenol resin (T1) having a hydroxyl value of 50 to 140 mgKOH / g, and in the adhesive layer, the total content of a terpene phenol resin (T2) having a hydroxyl value exceeding 140 mgKOH / g and a rosin ester resin (T3) is 5 parts by weight or less with respect to 100 parts by weight of the base polymer. The present invention will be described in detail below.

[0007] The inventors of the present invention have found that, in an adhesive tape having a base material and an adhesive layer laminated on at least one surface of the base material, by using a specific block copolymer in the adhesive layer, the re-peelability of the adhesive tape is improved, the adherend can be sufficiently protected by the adhesive tape during processing, and the adhesive tape can be easily peeled off without damaging the adherend after the processing is completed. Furthermore, the inventors of the present invention have studied the tackifier resin to be blended in the adhesive layer. Among the tackifier resins, the inventors of the present invention have particularly selected and used a terpene phenol resin (T1) having a hydroxyl value in a specific range, and by suppressing the total content of a terpene phenol resin (T2) having a higher hydroxyl value than T1 and a rosin ester resin (T3) to be equal to or less than a certain value, it has been found that the resistance to a strongly alkaline solution can be remarkably improved. As a result, the present invention has been completed.

[0008] The adhesive tape of the present invention has a base material and an adhesive layer laminated on at least one surface of the base material. The adhesive layer contains a base polymer and a tackifier resin. By containing the tackifier resin in addition to the base polymer in the adhesive layer, the adhesive strength of the adhesive tape is improved, and the adherend can be sufficiently protected.

[0009] The base polymer is a hydrogenated product of a block copolymer having at least a block derived from an aromatic vinyl monomer and a block derived from a conjugated diene monomer, or a block copolymer having at least a block derived from an aromatic vinyl monomer and a block derived from an olefin monomer. (Hereinafter, both are simply referred to as "block copolymer".) Since the base polymer is the block copolymer, the adhesive strength of the adhesive layer is within an appropriate range, and the re-peelability of the adhesive tape is improved. In addition, since the block copolymer has a relatively low polarity, when the base polymer is the block copolymer, for example, compared with the case of an acrylic polymer, a strongly alkaline solution hardly penetrates into the adhesive layer, and the resistance of the adhesive tape to a strongly alkaline solution is improved.

[0010] The above aromatic vinyl monomer is not particularly limited. For example, styrene, 2-methylstyrene, 3-methylstyrene, 4-methylstyrene, α-methylstyrene, 2,4-dimethylstyrene, 2,4-diisopropylstyrene, 4-t-butylstyrene, 5-t-butyl-2-methylstyrene, vinyl ethylbenzene, divinylbenzene, trivinylbenzene, divinylnaphthalene, t-butoxystyrene, vinylbenzyldimethylamine, (4-vinylbenzyl)dimethylaminoethyl ether, N,N-dimethylaminoethylstyrene, N,N-dimethylaminomethylstyrene, 2-ethylstyrene, 3-ethylstyrene, 4-ethylstyrene, 2-t-butylstyrene, 3-t-butylstyrene, 4-t-butylstyrene, vinylxylene, vinylnaphthalene, vinylpyridine, diphenylethylene, tertiary amino group-containing diphenylethylene, etc. may be mentioned. The above tertiary amino group-containing diphenylethylene is not particularly limited. For example, 1-(4-N,N-dimethylaminophenyl)-1-phenylethylene, etc. may be mentioned. These aromatic vinyl monomers may be used alone or in combination of two or more.

[0011] The above conjugated diene monomer is not particularly limited. For example, isoprene, 1,3-butadiene, 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, 1,3-hexadiene, 1,3-heptadiene, 2-phenyl-1,3-butadiene, 3-methyl-1,3-pentadiene, 2-chloro-1,3-butadiene, etc. may be mentioned. These conjugated diene monomers may be used alone or in combination of two or more. The above olefin monomer is not particularly limited. For example, ethylene, propylene, 1-butene, cis-2-butene, trans-2-butene, isobutene, 1-pentene, cis-2-pentene, trans-2-pentene, 1-hexene, cis-2-hexene, trans-2-hexene, cis-3-hexene, trans-3-hexene, cyclohexene, etc. may be mentioned. These olefin monomers may be used alone or in combination of two or more.

[0012] The block copolymer is not particularly limited, and may be a block copolymer having rubber elasticity at room temperature and having a hard segment portion and a soft segment portion, or a hydrogenated product thereof. Here, the block derived from the aromatic vinyl monomer is the hard segment portion, and the block derived from the conjugated diene monomer or the block derived from the olefin monomer is the soft segment portion. More specifically, a hydrogenated styrene-based block copolymer is preferable as the block copolymer. Examples of the hydrogenated styrene-based block copolymer include styrene-ethylene-butylene-styrene (SEBS) block copolymer, styrene-ethylene-propylene-styrene (SEPS) block copolymer, styrene-ethylene-ethylene-propylene-styrene (SEEPS), and the like. Further, examples of the block copolymer include styrene-isobutylene-styrene (SIBS) block copolymer and the like. Among them, SEBS block copolymer, SEPS copolymer and SIBS block copolymer are preferable, and SEBS block copolymer is more preferable because the adhesive force can be adjusted to be low. These block copolymers may be used alone or in combination of two or more.

[0013] The styrene content of the styrene-ethylene-butylene-styrene (SEBS) block copolymer is not particularly limited, but the preferable upper limit is 30% by weight, more preferably 25% by weight, and still more preferably 20% by weight. When the styrene content is within the above range, the adhesive layer does not become too hard and the adhesion to the adherend becomes high, so that the resistance of the adhesive tape to a strong alkaline solution is further improved. Therefore, even when the adhesive tape is bonded to an adherend having a larger surface roughness and exposed to a strong alkaline solution, peeling is less likely to occur. The lower limit of the styrene content is not particularly limited, but from the viewpoint of maintaining the cohesive force of the adhesive layer, the preferable lower limit is 8% by weight. Note that the styrene content can be calculated from the peak area ratio of each block measured by 1 1H-NMR.

[0014] The molar ratio of ethylene to butylene in the above styrene-ethylene-butylene-styrene (SEBS) block copolymer (mol% of ethylene / mol% of butylene) (hereinafter also referred to as "ethylene-butylene ratio") is not particularly limited, but the preferable lower limit is 1.0, and the more preferable lower limit is 1.2. When the ethylene-butylene ratio is within the above range, the resistance of the pressure-sensitive adhesive tape to a strong alkaline solution is further improved. For this reason, even when the pressure-sensitive adhesive tape is adhered to an adherend with a larger surface roughness and exposed to a strong alkaline solution, peeling is less likely to occur. Regarding the reason why the resistance of the pressure-sensitive adhesive tape to a strong alkaline solution is further improved, although not bound by this theory, it is considered that because the ratio of ethylene is higher than that of butylene, partial packing of ethylene sites occurs within the molecule, making it difficult for a strong alkaline solution to penetrate. The upper limit of the ethylene-butylene ratio is not particularly limited, but from the viewpoint that the above pressure-sensitive adhesive layer does not become too hard and has excellent adhesion to the adherend, the preferable upper limit is 2. In addition, the ethylene-butylene ratio can be calculated from the peak area ratio of each component measured by 1 1H-NMR.

[0015] The styrene content of the above styrene-ethylene-propylene-styrene (SEPS) block copolymer is not particularly limited, but from the same viewpoint as in the case of the above styrene-ethylene-butylene-styrene (SEBS) block copolymer, the preferable lower limit is 8% by weight, and the preferable upper limit is 30% by weight. The more preferable upper limit of the styrene content is 15% by weight, and the further preferable upper limit is 13% by weight. The styrene content of the above styrene-isobutylene-styrene (SIBS) block copolymer is not particularly limited, but from the same viewpoint as in the case of the above styrene-ethylene-butylene-styrene (SEBS) block copolymer, the preferable lower limit is 8% by weight, and the preferable upper limit is 30% by weight, the more preferable upper limit is 25% by weight, and the further preferable upper limit is 20% by weight.

[0016] In addition to the triblock copolymer of the block derived from the aromatic vinyl monomer and the block derived from the conjugated diene monomer or the block derived from the olefin monomer, the block copolymer may contain a diblock copolymer of the block derived from the aromatic vinyl monomer and the block derived from the conjugated diene monomer or the block derived from the olefin monomer. The content of the diblock copolymer in the block copolymer (hereinafter, also referred to as "diblock ratio") is not particularly limited, but the preferable lower limit is 10% by weight, and the more preferable lower limit is 30% by weight. When the diblock ratio is within the above range, the adhesion of the pressure-sensitive adhesive layer to the adherend is increased, so that the resistance of the pressure-sensitive adhesive tape to a strongly alkaline solution is further improved. Therefore, even when the pressure-sensitive adhesive tape is bonded to an adherend with a larger surface roughness and exposed to a strongly alkaline solution, peeling is less likely to occur. The upper limit of the diblock ratio is not particularly limited, but from the viewpoint of maintaining the cohesive force of the pressure-sensitive adhesive layer, the preferable upper limit is 90% by weight. The diblock ratio can be calculated from the peak area ratio of each copolymer measured by gel permeation chromatography (GPC) method.

[0017] The weight average molecular weight of the block copolymer is not particularly limited, but the preferable lower limit is 50,000, and the preferable upper limit is 600,000. When the weight average molecular weight is 50,000 or more, the heat resistance of the pressure-sensitive adhesive tape is further increased. When the weight average molecular weight is 600,000 or less, it is possible to prevent the compatibility between the block copolymer and other components from being excessively reduced. The more preferable lower limit of the weight average molecular weight is 100,000, and the more preferable upper limit is 500,000. The weight average molecular weight of the block copolymer means the weight average molecular weight measured as a polystyrene-equivalent molecular weight by gel permeation chromatography (GPC) method. For the measurement of the weight average molecular weight by the GPC method, for example, column LF-804 (manufactured by Showa Denko KK) can be used as the column.

[0018] The above tackifier resin contains a terpene phenol resin (T1) having a hydroxyl value of 50 to 140 mgKOH / g. Among various tackifier resins, the above tackifier resin contains a terpene phenol resin (T1) having a hydroxyl value within the above range, thereby improving the resistance of the pressure-sensitive adhesive tape to a strongly alkaline solution. The terpene phenol resin means a polymer containing terpene residues and phenol residues. The terpene phenol resin also includes a copolymer of terpene and phenol compound (terpene-phenol copolymer resin), a phenol-modified terpene resin obtained by phenol-modifying a homopolymer or copolymer of terpene (terpene resin, typically an unmodified terpene resin), and a resin obtained by hydrogenating the terpene moiety in these resins.

[0019] The terpene constituting the above terpene phenol resin (T1) is not particularly limited, but monoterpenes such as α-pinene, β-pinene, limonene, and camphene are preferred. Limonene includes d-form, l-form, and d / l-form (dipentene).

[0020] The hydroxyl value of the above terpene phenol resin (T1) has a lower limit of 50 mgKOH / g and an upper limit of 140 mgKOH / g. If the hydroxyl value of the above terpene phenol resin (T1) is within the above range, the polarity of the above terpene phenol resin (T1) will be within an appropriate range, making it difficult for a strongly alkaline solution to penetrate into the pressure-sensitive adhesive layer and improving the resistance of the pressure-sensitive adhesive tape to a strongly alkaline solution. The preferred lower limit of the hydroxyl value of the above terpene phenol resin (T1) is 55 mgKOH / g, and the preferred upper limit is 100 mgKOH / g. The more preferred lower limit is 60 mgKOH / g, and the more preferred upper limit is 80 mgKOH / g. That is, it is more preferable that the above terpene phenol resin (T1) contains a terpene phenol resin having a hydroxyl value of 60 to 80 mgKOH / g. The hydroxyl value of the tackifier resin is defined as the number of milligrams of potassium hydroxide required to neutralize acetic acid bound to hydroxyl groups when 1 g of the tackifier resin is acetylated, and is measured based on the potentiometric titration method specified in JIS K 0070:1992.

[0021] The softening point of the terpene phenol resin (T1) is not particularly limited, but a preferable lower limit is 145°C. If the softening point of the terpene phenol resin (T1) is 145°C or higher, the molecular weight of the terpene phenol resin increases, and its solubility in a strongly alkaline solution decreases. As a result, it becomes difficult for a strongly alkaline solution to penetrate into the pressure-sensitive adhesive layer, and the resistance of the pressure-sensitive adhesive tape to a strongly alkaline solution is further improved. For this reason, even when the pressure-sensitive adhesive tape is bonded to a substrate with a larger surface roughness and exposed to a strongly alkaline solution, peeling is less likely to occur. Also, if the softening point of the terpene phenol resin (T1) is 145°C or higher, the heat resistance of the pressure-sensitive adhesive tape becomes higher. A more preferable lower limit of the softening point of the terpene phenol resin (T1) is 150°C. The upper limit of the softening point of the terpene phenol resin (T1) is not particularly limited, but the substantial upper limit is about 180°C. The softening point of the tackifier resin is the temperature at which the solid resin begins to soften and deform, and is defined as a value measured based on the softening point test method (ring and ball method) specified in JIS K 5902 and JIS K 2207.

[0022] The content of the terpene phenol resin (T1) is not particularly limited, but a preferable lower limit with respect to 100 parts by weight of the base polymer is 3 parts by weight, and a preferable upper limit is 80 parts by weight. If the content of the terpene phenol resin (T1) is 3 parts by weight or more, the resistance of the pressure-sensitive adhesive tape to a strongly alkaline solution is further improved. If the content of the terpene phenol resin (T1) is 80 parts by weight or less, the adhesion promotion of the pressure-sensitive adhesive layer is suppressed, the glue residue is suppressed, and the re-peelability of the pressure-sensitive adhesive tape is further improved. A more preferable lower limit of the content of the terpene phenol resin (T1) is 10 parts by weight, and a more preferable upper limit is 60 parts by weight. Further, among the above-mentioned tacky terpene phenol resin (T1), the content of the terpene phenol resin having a hydroxyl value of 50 to 80 mgKOH / g is not particularly limited, and the preferable lower limit with respect to 100 parts by weight of the base polymer is 3 parts by weight, and the preferable upper limit is 80 parts by weight. A more preferable lower limit is 10 parts by weight, and a more preferable upper limit is 60 parts by weight.

[0023] The above-mentioned tackifying resin may contain a tackifying resin other than the above-mentioned terpene phenol resin (T1). The tackifying resin other than the above-mentioned terpene phenol resin (T1) is not particularly limited, and examples thereof include coumarone resins, terpene resins, terpene phenol resins, rosin resins, rosin derivative resins, petroleum resins, alkylphenol resins, and hydrides thereof. These tackifying resins may be used alone or in combination of two or more.

[0024] More specifically, examples of the above-mentioned rosin resin include unmodified rosins (raw rosins) such as gum rosin, wood rosin, and tall oil rosin, and modified rosins obtained by modifying these unmodified rosins. Examples of the modification in the above-mentioned modified rosin include hydrogenation, disproportionation, polymerization, and the like. More specifically, examples of the above-mentioned modified rosin include hydrogenated rosin, disproportionated rosin, polymerized rosin, and other chemically modified rosins.

[0025] More specifically, examples of the above-mentioned rosin derivative resin include rosin ester resins obtained by esterifying the above-mentioned rosin resin with alcohols, unsaturated fatty acid-modified rosin resins obtained by modifying the above-mentioned rosin resin with unsaturated fatty acids, and unsaturated fatty acid-modified rosin ester resins obtained by modifying the above-mentioned rosin ester resin with unsaturated fatty acids. Further, examples of the above-mentioned rosin derivative resin also include rosin alcohol resins obtained by reducing the carboxyl group in the above-mentioned unsaturated fatty acid-modified rosin resin or unsaturated fatty acid-modified rosin ester resin. Furthermore, examples of the rosin derivative resin include metal salts of the rosin resin or rosin derivative resin (particularly, rosin ester resin), rosin phenol resin, etc. The rosin phenol resin can be obtained by adding phenol to the rosin resin or rosin derivative resin under an acid catalyst and performing thermal polymerization.

[0026] More specifically, examples of the petroleum resin include aliphatic (C5-based) petroleum resin, aromatic (C9-based) petroleum resin, C5 / C9 copolymer-based petroleum resin, alicyclic petroleum resin, etc.

[0027] However, in the adhesive layer, the total content of the terpene phenol resin (T2) having a hydroxyl value exceeding 140 mgKOH / g and the rosin ester resin (T3) is 5 parts by weight or less with respect to 100 parts by weight of the base polymer. When the total content of the terpene phenol resin (T2) and the rosin ester resin (T3) is 5 parts by weight or less, the resistance of the adhesive tape to a strong alkaline solution is improved. Since the terpene phenol resin (T2) has a higher hydroxyl value and higher polarity than the terpene phenol resin (T1), if the content of the terpene phenol resin (T2) is too high, a strong alkaline solution easily penetrates into the adhesive layer, and the resistance of the adhesive tape to a strong alkaline solution decreases. In addition, since the rosin ester resin (T3) has functional groups such as an ester group, a hydroxyl group, and a carboxyl group, if the content of the rosin ester resin (T3) is too high, a strong alkaline solution easily penetrates into the adhesive layer, and the resistance of the adhesive tape to a strong alkaline solution decreases. The total content of the terpene phenol resin (T2) and the rosin ester resin (T3) is preferably 2 parts by weight or less, and more preferably 0 parts by weight. Also, from the viewpoint of further improving the resistance of the adhesive tape to a strong alkaline solution, the total content of the terpene phenol resin (T2) and the rosin ester resin (T3) is preferably not more than the content of the terpene phenol resin (T1).

[0028] The above adhesive layer may contain additives such as plasticizers, emulsifiers, softeners, fillers, pigments, dyes, and other resins, if necessary.

[0029] The thickness of the above adhesive layer is not particularly limited, but the preferable lower limit is 5 μm and the preferable upper limit is 100 μm. If the thickness of the adhesive layer is 5 μm or more, the adhesive strength of the adhesive tape becomes higher. If the thickness of the adhesive layer is 100 μm or less, the processability of the adhesive tape is improved.

[0030] In the adhesive tape of the present invention, the above adhesive layer is laminated on at least one surface of the base material. The adhesive layer may be laminated on one side of the base material or on both sides of the base material. The above base material is not particularly limited, and examples thereof include resin films and metal foils. The above resin film is not particularly limited, and examples thereof include polyolefin-based resin films such as polyethylene films and polypropylene films, polyester-based resin films such as polyethylene terephthalate (PET) films, ethylene-vinyl acetate copolymer films, polyvinyl chloride-based resin films, and polyurethane-based resin films. In addition, examples of the above base material also include polyolefin foam sheets such as polyethylene foam sheets and polypropylene foam sheets, and polyurethane foam sheets. Among them, a PET film is preferable.

[0031] The above base material preferably has a metal layer on the outermost surface of the surface opposite to the surface on which the adhesive layer is laminated. When the above base material has the above metal layer, even when the adhesive tape is folded (bent) and attached to the adherend, since the metal layer retains its shape, the restoring force due to folding the above base material is suppressed, and a gap is less likely to occur between the adherend and the adhesive layer, and peeling is less likely to occur. (Hereinafter, such performance is also referred to as "folded attachment property".) When the above base material does not have the above metal layer, for example, when it consists only of the above resin film, a gap is likely to occur between the adherend and the adhesive layer due to the restoring force of the resin film, and peeling is likely to occur. In addition, as an application for folding the adhesive tape and attaching it to the adherend, for example, in the manufacturing process of a substrate, there is an application where the adhesive tape is attached to the end of a copper-clad laminate to protect it from damage and the treatment is performed in a protected state. In such a case, the adhesive tape is folded and attached along the end of the copper-clad laminate so as to have a shape such as a U-shape, >-shape,}-shape, etc.

[0032] The metal constituting the metal layer is not particularly limited, and examples thereof include copper, aluminum, nickel, titanium, etc. Also, as the metal constituting the metal layer, alloys such as stainless steel and Monel are also included. Among them, copper is preferable because the restoring force after folding is small, so the foldability of the adhesive tape is further improved, and it is difficult to break, so the handleability of the adhesive tape becomes better.

[0033] The thickness of the metal layer is not particularly limited, but the preferable lower limit of the ratio of the thickness of the metal layer to the total thickness of the base material (thickness of the metal layer / total thickness of the base material) is 15%. If the ratio of the thickness of the metal layer is 15% or more, the foldability of the adhesive tape is further improved. A more preferable lower limit of the ratio of the thickness of the metal layer is 25%. The upper limit of the ratio of the thickness of the metal layer is not particularly limited and may be 100%. That is, the base material may be a metal base material. When the base material is a metal base material, the foldability of the adhesive tape is further improved, and the anchoring property between the base material and the adhesive layer is increased without passing through a resin layer as described later. Therefore, the adhesive residue of the adhesive layer is suppressed, and the re-peelability of the adhesive tape is further improved. The metal constituting the metal base material is not particularly limited and may be the same metal as the metal constituting the metal layer. Among them, since the restoring force after folding is small, the foldability of the adhesive tape is further improved, and it is difficult to break, so the base material is preferably a copper foil.

[0034] The thickness of the above-mentioned base material is not particularly limited, but the preferable lower limit is 5 μm and the preferable upper limit is 30 μm. If the thickness of the above-mentioned base material is within the above range, the folding and pasting property of the adhesive tape will be further improved. The more preferable lower limit of the thickness of the above-mentioned base material is 8 μm and the more preferable upper limit is 20 μm.

[0035] The adhesive tape of the present invention preferably further has a resin layer between the above-mentioned base material and the above-mentioned adhesive layer, and the above-mentioned resin layer preferably contains a resin having a polar functional group. Since the adhesive tape of the present invention has the above-mentioned resin layer, the anchoring property between the above-mentioned base material and the above-mentioned adhesive layer increases, so that a strongly alkaline solution hardly penetrates into the above-mentioned adhesive layer, and the resistance of the adhesive tape to the strongly alkaline solution is further improved. Further, by increasing the anchoring property between the above-mentioned base material and the above-mentioned adhesive layer, the adhesive residue of the above-mentioned adhesive layer is suppressed, and the re-peelability of the adhesive tape is further improved.

[0036] The above-mentioned polar functional group is not particularly limited, but at least one selected from the group consisting of a nitrile group, a carbonyl group, a carboxyl group, and an amino group is preferable because it has excellent adhesion to a resin base material such as a PET film and the above-mentioned metal base material. Among them, a nitrile group and a carbonyl group are more preferable.

[0037] Specific examples of the resin having the above-mentioned polar functional group include acrylonitrile-butadiene rubber (NBR), maleic anhydride-modified styrene-ethylene-butylene-styrene (maleic anhydride-modified SEBS), amine-modified styrene-ethylene-butylene-styrene (amine-modified SEBS), and the like. Among them, NBR and maleic anhydride-modified SEBS are preferable because they have excellent adhesion to a resin base material such as a PET film and also have excellent adhesion to the above-mentioned adhesive layer.

[0038] The thickness of the resin layer is not particularly limited, but the preferable lower limit is 0.1 μm and the preferable upper limit is 3 μm. If the thickness of the resin layer is within the above range, the resistance of the adhesive tape to a strong alkaline solution is further improved, and the peelability is also further improved. The more preferable lower limit of the thickness of the resin layer is 0.5 μm, and the more preferable upper limit is 2 μm.

[0039] The resin layer may contain additives such as a plasticizer, an emulsifier, a softening agent, a filler, a pigment, a dye, and other resins, etc. as required.

[0040] The method for producing the adhesive tape of the present invention is not particularly limited, and for example, the following methods can be mentioned. First, an adhesive solution containing the base polymer and the tackifier resin is prepared. Next, the adhesive solution obtained above is applied to the release-treated surface of a release film having one surface release-treated and dried to produce a laminated sheet having an adhesive layer on the release-treated surface of the release film. Next, the adhesive layer of the laminated sheet is transferred and laminated integrally to the base material via the resin layer as required to obtain an adhesive tape.

[0041] The use of the adhesive tape of the present invention is not particularly limited, but it can be suitably used for applications exposed to a strong alkaline solution. Examples of the applications exposed to the strong alkaline solution include, for example, applications in which an adhesive tape is attached to the end of a copper-clad laminate to protect it and the treatment is performed in a protected state in order to prevent damage to the copper-clad laminate in the manufacturing process of a substrate. In such a case, for example, an etching treatment, a desmear treatment, etc. are performed, and a strong alkaline solution is used as the treatment solution. That is, the adhesive tape of the present invention is preferably used for protecting a substrate having a metal layer such as a copper-clad laminate in an etching treatment or a desmear treatment in the manufacturing process of a substrate.

[0042] In addition, since the adhesive tape of the present invention also has excellent fold-back adhesiveness, it can also be suitably used for applications in which the adhesive tape is folded (bent) and attached to an adherend. As an application for folding back the above-mentioned adhesive tape and attaching it to an adherend, for example, in the manufacturing process of a substrate, there is an application where an adhesive tape is attached to the end of a copper-clad laminate to protect it and the treatment is carried out in a protected state to prevent damage to the copper-clad laminate. In such a case, the adhesive tape is folded back and attached along the end of the copper-clad laminate so as to have a shape such as a U-shape, >-shape,}-shape, etc.

Effects of the Invention

[0043] According to the present invention, it is possible to provide an adhesive tape that is excellent in resistance to a strongly alkaline solution and can be easily peeled off from an adherend.

Modes for Carrying Out the Invention

[0044] Examples will be given below to explain the aspects of the present invention in more detail, but the present invention is not limited only to these examples.

[0045] As the base polymer, the polymers shown in Tables 1 to 4 were used. Note that DYNARON 8300P and DYNARON 8600P are manufactured by JSR Corporation, Clayton G1643 and Clayton G1657 are manufactured by Clayton Polymer Corporation, and Taftec H1052, Taftec H1053 and Taftec H1041 are styrene-ethylene-butylene-styrene (SEBS) block copolymers manufactured by Asahi Kasei Corporation. Septon 2063, Septon 2004F and Septon 2002 are styrene-ethylene-propylene-styrene (SEPS) block copolymers manufactured by Kuraray Co., Ltd. SIBSTAR 102T and SIBSTAR 103T are styrene-isobutylene-styrene (SIBS) block copolymers manufactured by Kaneka Corporation. Quintac 3520 is an SIS (styrene-isoprene-styrene block copolymer) manufactured by Nippon Zeon Co., Ltd.

[0046] As the tackifier resin, the tackifier resins shown in Tables 1 to 4 were used. Note that U-115, T-80, T-130, T-145, T-160, S-145, G-125, G-150, and K-125 were terpene phenolic resins (YS Polyster) manufactured by Yasuhara Chemical Co., Ltd. P-125 was a hydrogenated petroleum resin (Alcon) manufactured by Arakawa Chemical Industries, Ltd. PX-1250 was a polyt terpene resin (YS Resin) manufactured by Yasuhara Chemical Co., Ltd. A-125 was a rosin ester resin (disproportionated rosin ester) (Super Ester) manufactured by Arakawa Chemical Industries, Ltd.

[0047] (Examples 1 to 32, Comparative Examples 1 to 9) The base polymer and tackifier resin of the types and amounts shown in Tables 1 to 4 were added to a solvent (toluene) so that the solution concentration was 30% by weight and stirred to prepare an adhesive solution. A polyethylene terephthalate film with one side release-treated was prepared. The adhesive solution obtained above was applied to the release-treated surface of this polyethylene terephthalate film so that the dried thickness was 30 μm and dried at 110°C for 5 minutes to produce a laminated sheet having an adhesive layer on the release-treated surface of the polyethylene terephthalate film.

[0048] A polyethylene terephthalate film with a thickness of 12 μm (t = 12 μm) was prepared as the base material. Nipol 1042 (manufactured by Nippon Zeon Co., Ltd., acrylonitrile-butadiene rubber) was added to a solvent (methyl ethyl ketone) so that the solution concentration was 5% by weight and stirred to prepare a resin solution. The obtained resin solution was applied to one surface of the base material so that the dried thickness was 1 μm and dried at 110°C for 5 minutes to form a resin layer. The laminated sheet was laminated on the obtained resin layer so that its adhesive layer faced the resin layer, and the adhesive layer was transferred and laminated integrally to the base material through the resin layer, and an adhesive tape having an adhesive layer with a thickness of 30 μm on one side of the base material through the resin layer was obtained.

[0049] <Evaluation 1> The following evaluations were performed on the adhesive tapes obtained in Examples 1 to 32 and Comparative Examples 1 to 9. The results are shown in Tables 1 to 4.

[0050] (1) Evaluation of resistance to strong alkaline solution As the copper plates with low surface roughness and high surface roughness, copper plates with a surface roughness Ra of 0.06 μm or 0.26 μm were used respectively. An adhesive tape was attached to the surface of the copper plate with a surface roughness Ra of 0.06 μm or 0.26 μm to prepare a laminate. This laminate was immersed in a 5 wt% aqueous sodium hydroxide solution at 50 °C for 30 minutes, then the laminate was taken out, the aqueous sodium hydroxide solution was removed, and it was left at room temperature for 30 minutes. After leaving it at room temperature for 30 minutes, the adhesive tape was peeled off from the copper plate. The area ratio (area of the non-corroded part / area of the whole part where the adhesive tape was attached to the copper plate × 100 (%)) between the non-corroded part and the whole part where the adhesive tape was attached to the copper plate was calculated and taken as the protection rate. When the protection rate (area of the non-corroded part / area of the whole part where the adhesive tape was attached to the copper plate × 100 (%)) was 80% or more, it was indicated as ◎; when it was 50% or more and less than 80%, it was indicated as ○; when it was less than 50%, it was indicated as ×.

[0051] (2) Evaluation of adhesive strength (180° peel adhesive strength to copper) A test piece was prepared by cutting the adhesive tape into a width of 25 mm, and a copper plate with a surface roughness Ra of 0.06 μm was used as the adherend for evaluation. In a standard environment of 23 °C and 50% RH, the adhesive surface of the test piece was pressed against the adherend with a 2 kg roller for one round trip. After leaving the test piece pressed against the adherend in the above standard environment for 20 minutes, in accordance with JIS-Z0237, the 180° peel adhesive strength was measured under the conditions of a peel angle of 180° and a tensile speed of 300 mm / min. The measurement was carried out 3 times, and their average value was taken as the adhesive strength. When the adhesive strength was 2 N / 25 mm or less, it was indicated as ◎; when it exceeded 2 N / 25 mm and was less than 15 N / 25 mm, it was indicated as ○; when it was 15 N / 25 mm or more, it was indicated as ×.

[0052] (Example 33) An adhesive tape was obtained in the same manner as in Example 4 except that no resin layer was provided between the base material and the adhesive layer.

[0053] (Examples 34 to 36) An adhesive tape was obtained in the same manner as in Example 4, except that a resin having a polar functional group of the type shown in Table 5 was used when forming the resin layer. Note that Nipol 1042 is an acrylonitrile-butadiene rubber manufactured by Nippon Zeon Co., Ltd., Toughtech M1943 is a maleic anhydride-modified styrene-ethylene-butylene-styrene manufactured by Asahi Kasei Corporation, and Toughtech MP10 is an amine-modified styrene-ethylene-butylene-styrene manufactured by Asahi Kasei Corporation.

[0054] (Example 37) An adhesive tape was obtained in the same manner as in Example 4, except that a copper foil with a thickness of 18 μm (t = 18 μm) was used instead of the polyethylene terephthalate film with a thickness of 12 μm (t = 12 μm) as the base material, and no resin layer was provided between the base material and the adhesive layer.

[0055] <Evaluation 2> The following evaluations were performed on the adhesive tapes obtained in Examples 33 to 37. The results are shown in Table 5.

[0056] (1) Evaluation of glue residue after high-temperature treatment A test piece obtained by cutting the adhesive tape into a width of 25 mm was used as a test piece, and a copper plate was used as the adherend for evaluation. In a standard environment of 23°C and 50% RH, the adhesive surface of the test piece was pressed against the adherend with a 2 kg roller for one round trip. The test piece thus pressed onto the adherend was left in the above standard environment for 20 minutes, and then left standing in an atmosphere of 80°C for 24 hours. Thereafter, the test piece pressed onto the adherend was returned to 23°C, and in accordance with JIS-Z0237, the test piece was peeled off under the conditions of a peeling angle of 180° and a tensile speed of 300 mm / min. The presence or absence of glue residue on the copper plate was confirmed.

[0057] (2) Evaluation of re-stickability Along the edge of a copper foil with a thickness of 50 μm, the adhesive tape was folded back (bent) in a U shape, pasted, crimped at 0.5 MPa, and allowed to stand for 24 hours to produce a laminate. At the folded part, the adhesive tape was folded back so that the adhesive tape overlapped by 5 mm each. After immersing this laminate in water at 50 °C for 30 minutes, it was confirmed whether water penetrated into the root part of the folded adhesive tape. When there was no water penetration into the root part of the folded adhesive tape, it was indicated as ○, and when there was water penetration, it was indicated as ×.

[0058]

Table 1

[0059]

Table 2

[0060]

Table 3

[0061]

Table 4

[0062]

Table 5

Industrial Applicability

[0063] According to the present invention, it is possible to provide an adhesive tape that is excellent in resistance to a strongly alkaline solution and can be easily peeled off from an adherend.

Claims

1. An adhesive tape having a base material and an adhesive layer laminated on at least one surface of the base material, The base material has a metal layer on the outermost surface of the surface opposite to the surface on which the adhesive layer is laminated, The adhesive layer contains a base polymer and an adhesion - imparting resin, The base polymer is a hydrogenated product of a block copolymer having at least a block derived from an aromatic vinyl monomer and a block derived from a conjugated diene monomer, or a block copolymer having at least a block derived from an aromatic vinyl monomer and a block derived from an olefin monomer, The adhesion - imparting resin contains a terpene phenol resin (T1) having a hydroxyl value of 50 to 140 mgKOH / g, In the adhesive layer, the total content of a terpene phenol resin (T2) having a hydroxyl value exceeding 140 mgKOH / g and a rosin ester resin (T3) is 5 parts by weight or less with respect to 100 parts by weight of the base polymer An adhesive tape characterized by the above.

2. The adhesive tape according to claim 1, wherein the content of the terpene phenol resin (T1) having a hydroxyl value of 50 to 140 mgKOH / g is 3 to 80 parts by weight with respect to 100 parts by weight of the base polymer.

3. The adhesive tape according to claim 1 or 2, wherein the terpene phenol resin (T1) having a hydroxyl value of 50 to 140 mgKOH / g contains a terpene phenol resin having a hydroxyl value of 50 to 80 mgKOH / g.

4. The adhesive tape according to claim 3, wherein the content of the terpene phenol resin having a hydroxyl value of 50 to 80 mgKOH / g is 3 to 80 parts by weight with respect to 100 parts by weight of the base polymer.

5. The pressure-sensitive adhesive tape according to claim 1, 2, 3, or 4, wherein the terpene phenol resin (T1) having a hydroxyl value of 50 to 140 mgKOH / g is characterized in that the softening point is 145°C or higher.

6. The pressure-sensitive adhesive tape according to claim 1, 2, 3, 4, or 5, wherein the base polymer is a hydrogenated styrene-based block copolymer.

7. The pressure-sensitive adhesive tape according to claim 6, wherein the hydrogenated styrene-based block copolymer is a styrene-ethylene-butylene-styrene (SEBS) block copolymer.

8. The pressure-sensitive adhesive tape according to claim 7, wherein the styrene-ethylene-butylene-styrene (SEBS) block copolymer has a styrene content of 25% by weight or less.

9. The pressure-sensitive adhesive tape according to claim 7 or 8, wherein the styrene-ethylene-butylene-styrene (SEBS) block copolymer has an ethylene / butylene ratio of 1.0 or more.

10. The pressure-sensitive adhesive tape according to claim 6, wherein the hydrogenated styrene-based block copolymer is a styrene-ethylene-propylene-styrene (SEPS) block copolymer.

11. The pressure-sensitive adhesive tape according to claim 10, wherein the styrene-ethylene-propylene-styrene (SEPS) block copolymer has a styrene content of 15% by weight or less.

12. The pressure-sensitive adhesive tape according to claim 1, 2, 3, 4, or 5, wherein the base polymer is a styrene-isobutylene-styrene (SIBS) block copolymer.

13. The pressure-sensitive adhesive tape according to claim 12, wherein the styrene-isobutylene-styrene (SIBS) block copolymer has a styrene content of 25% by weight or less.

14. The pressure-sensitive adhesive tape according to claim 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, further having a resin layer between the base material and the pressure-sensitive adhesive layer, wherein the resin layer contains a resin having a polar functional group.

15. The pressure-sensitive adhesive tape according to claim 14, wherein the resin having a polar functional group has at least one polar functional group selected from the group consisting of a nitrile group, a carbonyl group, a carboxyl group, and an amino group.

16. The pressure-sensitive adhesive tape according to claim 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14 or 15, wherein the metal layer is made of copper.

17. The pressure-sensitive adhesive tape according to claim 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15 or 16, wherein the base material is a copper foil.

18. The pressure-sensitive adhesive tape according to claim 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16 or 17, which is used for protecting a substrate having a metal layer in an etching process or a desmear process in a substrate manufacturing process.

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