Adhesive tape

Abstract

To provide an adhesive tape that offers excellent resistance to the penetration of plating solution, especially when plating is performed for extended periods (e.g., 24 hours) on overlapping sections, and also offers excellent peelability after plating and resistance to contamination of non-plated areas. [Solution] An adhesive tape comprising a base material made of metal foil, a back treatment layer formed on one side of the base material, and an adhesive layer formed on the other side of the base material, wherein the release agent layer is SiO 4 / 2 The adhesive tape comprises an addition-reactive silicone resin composition containing a silica structure having units, the adhesive layer comprises a styrene-isoprene-styrene block copolymer and a tackifying resin having acid groups, and the adhesive tape has a self-back adhesive strength of 3.4 N / 10 mm or more after immersion in a 5 wt% sulfuric acid aqueous solution for 24 hours.

Description

[Technical Field]

[0001] The present invention relates to an adhesive tape, and more particularly to an adhesive tape (hereinafter sometimes simply referred to as "masking tape" or "plating masking tape") that is suitably used for masking when plating the surface of a metal material with the same or a different type of metal. [Background technology]

[0002] As for plating methods, for example, wet plating methods such as electrolytic plating and electroless plating are known for metal materials (stainless steel, iron, etc.). In these wet plating methods, an acidic or alkaline plating solution is used, and by applying electrical energy or chemical reaction energy, the metal in the plating solution is deposited on the surface of the metal material, forming a plating film.

[0003] In the wet plating process described above, masking tape may be applied to the unplated areas of the material to be plated, such as metal materials, to prevent plating from being applied to those areas, i.e., to protect the unplated areas. This masking tape is removed from the unplated areas of the material to be plated after the series of plating processes are completed.

[0004] For example, Patent Document 1 discloses a masking tape for metal plating that has excellent resistance to penetration of plating solutions, good peelability after plating, and excellent resistance to contamination, discoloration, and peeling of rust inhibitors on unplated parts. The tape is formed by containing a specific monomer in an acrylic copolymer that is the main component, crosslinking it with a specific crosslinking agent, and forming an adhesive layer with an adhesive having a specific elastic modulus.

[0005] In addition, in Patent Document 2, there is no adhesive residue at the initial stage of pasting, washing is unnecessary, and when stored for a certain period with the masking tape pasted, the part where the tape is pasted does not become cloudy, and plating can be stably applied thereon. A masking tape suitable for masking (surface protection) when plating the same or different metals on a metal surface and a method for producing the same are disclosed. The masking tape has an adhesive layer formed of an adhesive containing a hydrogenated styrene-based elastomer that has been washed in advance to remove calcium stearate and low molecular weight polyethylene as an anti-blocking agent on one side of a polyolefin-based resin substrate.

[0006] Patent Document 3, which has not yet been published, describes an adhesive tape having a substrate made of a metal foil and an adhesive layer containing A) a styrene-isoprene-styrene block copolymer and B) an adhesive resin having an acid group. When this adhesive tape is used for plating masking, it improves the problems that have conventionally existed, such as resistance to plating solution penetration, peelability after plating, and stain resistance of non-plated parts.

Prior Art Documents

Patent Documents

[0007]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0008] However, a problem was found with the adhesive tape described in Patent Document 3: the plating solution can seep in from the overlapping portion, causing masking defects. Specifically, for example, when an adhesive tape is applied to a cylindrical stainless steel member by wrapping it around the circumference for masking and then subjected to plating, there is usually a portion where the end of the wrapping overlaps the beginning of the wrapping of the adhesive tape (see Figure 5). When the adhesive tape described in Patent Document 3 is subjected to plating in this manner, there were no problems with masking under general conditions of immersion in the plating bath for about 2 to 4 hours. However, under conditions of immersion in the plating bath for 24 hours or more, the adhesive force between the adhesive layer of the upper adhesive tape and the back surface of the lower adhesive tape (self-back surface adhesive force) decreases in the overlapping portion of the adhesive tape (hereinafter sometimes referred to as the overlapping portion). As a result, the plating solution gradually seeps in from the edge of the beginning of the wrapping of the adhesive tape and the area around the edge through the interface between the adhesive layer and the back surface of the adhesive tape, making masking defects more likely. In extreme cases, the adhesive tape located on the upper side of the overlapping section was observed to partially peel away from the back surface of the adhesive tape located below it.

[0009] The present invention solves the aforementioned problems, and its objective is to provide an adhesive tape that has excellent resistance to the penetration of plating solution, especially when plating is performed for a long period of time (e.g., 24 hours) on overlapping portions, and also has excellent peelability after plating and stain resistance to the unplated portion. [Means for solving the problem]

[0010] The present invention provides the following embodiments. [1] An adhesive tape comprising a base material made of metal foil, a back treatment layer formed on one side of the base material, and an adhesive layer formed on the other side of the base material, The aforementioned back-processing layer is SiO 4 / 2 The composition includes a cured product of an addition-reactive silicone resin composition containing a silica structure having units, The adhesive layer comprises a styrene-isoprene-styrene block copolymer and a tackifying resin having acidic groups. The adhesive tape is an adhesive tape having a self-back adhesive strength of 3.1 N / 10 mm or more, preferably 3.1 N / 10 mm or more and 10 N / 10 mm or less, and more preferably 3.4 N / 10 mm or more and 5.3 N / 10 mm or less after immersion in a 5 wt% sulfuric acid aqueous solution (50°C) for 24 hours.

[0011] [2] The back treatment layer has an average of one or more alkenyl groups in its molecule, with an average unit formula: (R 1 3SiO 1 / 2 )x(SiO 4 / 2 ) 1.0 (In the formula, R 1 R independently represents an alkenyl group having 2 to 10 carbon atoms, an unsubstituted or substituted monovalent hydrocarbon group having 1 to 10 carbon atoms without an aliphatic unsaturated bond, or a hydroxyl group or alkoxy group. 1 Adhesive tape [1] comprising an organopolysiloxane resin (MQ resin) represented by (one or more of which are alkenyl groups, and x is a number between 0.5 and 2.0).

[0012] [3] The adhesive tape of [1] or [2], wherein the adhesive strength of the self-back surface after immersion in the 5 wt% sulfuric acid aqueous solution (50°C) for 24 hours is greater than the adhesive strength of the self-back surface before immersion.

[0013] [4] The adhesive layer is an adhesive tape of any of [1] to [3], wherein the acid value is in the range of 0.3 mg KOH / g or more and 5.5 mg KOH / g or less, preferably 0.4 mg KOH / g or more and 5.1 mg KOH / g or less, and more preferably 0.6 mg KOH / g or more and 3.0 mg KOH / g or less.

[0014] [5] The content of the tackifying resin is in the range of 20 parts by mass or more and 107 parts by mass or less, preferably 25 parts by mass or more and 100 parts by mass or less, and more preferably 40 parts by mass or more and 70 parts by mass or less, per 100 parts by mass of the styrene-isoprene-styrene block copolymer, any of the adhesive tapes of [1] to [4].

[0015] [6] The styrene-isoprene-styrene block copolymer has a styrene content of 13% by mass or more and 18% by mass or less, preferably 14% by mass or more and 17% by mass or less, more preferably 15% by mass or more and 16% by mass or less, and a styrene-isoprene block content of 50% by mass or more and 80% by mass or less, preferably 53% by mass or more and 79% by mass or less, more preferably 55% by mass or more and 78% by mass or less, any of the adhesive tapes of [1] to [5].

[0016] [7] The base material is an adhesive tape of any of [1] to [6], made of soft aluminum foil.

[0017] [8] An adhesive tape according to any of [1] to [7], having an intermediate layer between the substrate and the adhesive layer containing a modified polyolefin resin having acid groups or hydroxyl groups.

[0018] [9] The adhesive tape is any of the adhesive tapes [1] to [8] used for plating masking. [Effects of the Invention]

[0019] According to the present invention, an adhesive tape is provided that exhibits excellent resistance to the penetration of plating solution in the overlapping portions, as well as excellent peelability after plating and stain resistance in the unplated portions. [Brief explanation of the drawing]

[0020] [Figure 1] This is a cross-sectional view showing the configuration of an adhesive tape, which is one embodiment of the present invention. [Figure 2] This is a cross-sectional view showing the configuration of an adhesive tape, which is another embodiment of the present invention. [Figure 3] This is a cross-sectional view showing the structure of an adhesive tape, which is one reference example of the present invention. [Figure 4] A cross-sectional view showing the configuration of an adhesive tape, which is another reference example of the present invention. [Figure 5] This is a perspective view showing adhesive tape attached to a stainless steel cylindrical component. [Figure 6]This is a top view showing a test specimen used in the acid-resistant aqueous solution penetration (liquid diving) test of the present invention. [Modes for carrying out the invention]

[0021] The following describes in detail one embodiment of the present invention, but the scope of the present invention is not limited to the embodiment described herein, and various modifications can be made without departing from the spirit of the invention. Furthermore, if multiple upper and lower limits are given for a particular parameter, any combination of these upper and lower limits can be used to create a suitable numerical range.

[0022] [Composition of adhesive tape 10] Figure 1 shows an example of the configuration of the adhesive tape 10 of the present invention. The adhesive tape 10 of the present invention comprises a base material 2, a back treatment layer 1 formed on one side of the base material 2, and an adhesive layer 3 formed on the other side of the base material 2. Figure 2 shows another example of the configuration of the adhesive tape 10 of the present invention. As shown in Figure 2, the adhesive tape 10 of the present invention comprises a base material 2, a back treatment layer 1 formed on one side of the base material 2, an intermediate layer 4 formed on the other side of the base material 2, and an adhesive layer 3 formed on the surface of the intermediate layer 4. The adhesive tape 10 of the present invention may also include a release liner on the adhesive layer 3 that has release properties relative to the adhesive layer 3, although this is not shown.

[0023] [How to use adhesive tape 10] The adhesive tape 10 of the present invention is used, for example, as a masking tape for plating to protect unplated areas during wet plating. Specifically, when plating a desired portion of a material to be plated, the adhesive tape 10 is applied to the unplated areas of the material to be plated (hereinafter sometimes simply referred to as the "adherend") to mask them from the plating solution and prevent plating from being applied to those areas. In this case, as shown in Figure 5, for example, the adhesive tape 10 may be applied in overlapping layers to the back of already applied layers. That is, when an adhesive tape 10 with a length from the starting end line 6 to the ending end line 7 is applied to a cylindrical member (adherend) 5 by wrapping it around it, an overlapping layer 8a (approximately 5-10 mm wide) is formed. The masked material to be plated is then immersed in the plating solution. After the series of plating processes are completed, the adhesive tape 10 is peeled off again from the unplated areas.

[0024] Next, the composition of each layer of the adhesive tape 10 of the present invention will be described in detail. <Back processing layer 1> The back treatment layer 1 contains a cured product of an addition-reactive silicone resin composition. The back treatment layer 1 may also be a cured layer made of a cured product of an addition-reactive silicone resin composition. The addition-reactive silicone resin composition referred to herein is (a) an alkenyl group-containing organopolysiloxane, (b) an organohydrogenpolysiloxane, (c) a platinum group metal curing catalyst, and (d) SiO 4 / 2 This refers to a curable organopolysiloxane composition containing a silica structure having units.

[0025] (a) Alkenyl group-containing organopolysiloxane (a) The alkenyl group-containing organopolysiloxane, which is component (a), is an organopolysiloxane having two or more alkenyl groups bonded to silicon atoms at the terminal and / or side chain portions of the molecule. Component (a) is a liquid or gum-like precursor component that imparts an appropriate peeling effect to the back treatment layer 1 and sets the self-back adhesive strength of the adhesive tape 10 within an appropriate range, and is the base component of the above addition-reactive silicone resin composition. Component (a) above may be an organopolysiloxane containing linear, branched, or partially cyclic structures, but a linear organopolysiloxane is industrially preferred.

[0026] The above-mentioned alkenyl group is not particularly limited, but examples include vinyl group, allyl group, propenyl group, isopropenyl group, butenyl group, hexenyl group, and cyclohexenyl group, which typically have 2 to 8 carbon atoms. Among these, vinyl group and hexenyl group are preferred from the viewpoint of peeling performance and the reactivity of addition reaction type crosslinking with the organohydrogenpolysiloxane, which is component (b) described later.

[0027] The alkenyl group-containing organopolysiloxane of component (a) may be used alone, or in combination of two or more types with different viscosities or two or more types with different numbers of alkenyl groups.

[0028] (b) Organohydrogenpolysiloxane The organohydrogenpolysiloxane component (b) is an organohydrogenpolysiloxane having an average of two or more hydrogen atoms (hydrosilyl groups) directly bonded to silicon atoms in one molecule, and acts as a crosslinking agent for component (a). Specifically, the hydrosilyl groups in component (b) and the alkenyl groups in component (a) crosslink through a hydrosilylation reaction (addition reaction) promoted by the platinum group metal hardening catalyst component (c), described later, to form a hardened layer having a three-dimensional network structure.

[0029] The component (b) preferably has at least three silicon-bonded hydrogen atoms in one molecule, and the bonding positions are not particularly limited, but the content of silicon-bonded hydrogen atoms is preferably in the range of 0.1 to 2.0% by mass of the entire organohydrogenpolysiloxane composition, and more preferably in the range of 0.5 to 1.8% by mass. Examples of organic groups other than hydrogen atoms that bond to the silicon atoms contained in component (b) include alkyl groups such as methyl, ethyl, propyl, butyl, and octyl groups, with methyl groups being preferred. Examples of its molecular structure include linear, branched, and branched cyclic structures.

[0030] As the organohydrogenpolysiloxane mentioned above, known ones used in addition-reactive silicone compositions are used. Specifically, examples include dimethylsiloxane-methylhydrogensiloxane copolymer with trimethylsiloxy groups sealed at both ends, dimethylsiloxane-methylhydrogensiloxane copolymer with dimethylhydrogensiloxy groups sealed at both ends, dimethylpolysiloxane with dimethylhydrogensiloxy groups sealed at both ends, methylhydrogenpolysiloxane with trimethylsiloxy groups sealed at both ends, cyclic methylhydrogenpolysiloxane, and cyclic methylhydrogensiloxane-dimethylsiloxane copolymer. Note that component (b) may be used alone or in combination of two or more types with different numbers of hydrosilyl groups.

[0031] The amount of component (b) is not particularly limited, but for example, it is preferable that the molar ratio of SiH groups in component (b) to vinyl groups (CH2=CH-) in the alkenyl groups in component (a) is 0.5 to 5, and more preferably 1 to 3. If the molar ratio is smaller than the lower limit, the curability of the back treatment layer 1 may decrease, and if it exceeds the upper limit, the self-back adhesion may become excessive.

[0032] (c) Platinum group metal curing catalyst (c) component is a platinum group metal-based catalyst, which is a catalyst for promoting the hydrosilylation reaction (addition reaction) between (a) component and (b) component. Any catalyst known to those skilled in the art for promoting the so-called hydrosilylation reaction can be used. Examples of such platinum group metal-based catalysts include catalysts such as platinum-based, palladium-based, rhodium-based, ruthenium-based, etc. Among these, platinum-based catalysts are particularly preferably used. Examples of this platinum-based catalyst include chloroplatinic acid, an alcohol solution or aldehyde solution of chloroplatinic acid, various complexes of chloroplatinic acid with olefins or vinylsiloxanes, various complexes of platinum with olefins or vinylsiloxanes, etc. In particular, platinum alkenylsiloxane complexes such as the complex of chloroplatinic acid and divinyltetramethyldisiloxane, the complex of chloroplatinic acid and tetramethyltetravinylcyclotetrasiloxane, platinum divinyltetramethyldisiloxane complex, platinum tetramethyltetravinylcyclotetrasiloxane complex, etc. can be preferably used.

[0033] (c) The blending amount of the component may be a catalytic amount. Usually, based on the total mass of the above curable organopolysiloxane composition, the amount of platinum group metal contained in the (c) component is preferably 1 to 1,000 ppm, and more preferably in the range of 5 to 500 ppm.

[0034] (c) The platinum group metal-based curing catalyst of the component may be a commercially available one. For example, "DOWSIL RX 212" (trade name), "DOWSIL NC-25" (trade name) manufactured by Dow Corning Toray Co., Ltd., "CAT-PL-50T" (trade name) of Shin-Etsu Chemical Co., Ltd., etc. can be mentioned.

[0035] (d) SiO 4 / 2 silica structure having units In addition to the above (a), (b), and (c) components, the back surface treatment layer 1 of the present invention further contains a silica structure having SiO 4 / 2 units, so-called silica (SiO2) fine particles, as a peeling control agent for appropriately increasing the self-back adhesion of the adhesive tape 10. Thereby, the "SiO 4 / 2The interaction between the back treatment layer 1 containing a silica structure having units and the adhesive layer 3 containing a tackifier having acid groups is strengthened, and in particular, the self-back adhesive strength after immersion in a 5 wt% sulfuric acid aqueous solution for a long period of time (e.g., 24 hours) can be set to the desired adhesive strength.

[0036] The above (d) component is SiO 4 / 2 The amount of silica structure having units is not particularly limited, and is, for example, 0.1% by mass or more in the curable organopolysiloxane composition, and may be 1% by mass or more, 3% by mass or more, 5% by mass or more, or more than 10% by mass, from the viewpoint of effectively exhibiting the effect of adding a release control agent. The upper limit of the amount of component (d) in the curable organopolysiloxane composition is, for example, less than 50% by mass, may be around 30% by mass or less, or may be 15% by mass or less. In one embodiment, the amount of component (d) may be in the range of 1 to 49% by mass, 3 to 30% by mass or 5 to 15% by mass. SiO in the curable organopolysiloxane composition 4 / 2 The content of silica structures (silica nanoparticles) with units can also be determined by measuring the mass loss using DSC (Differential Scanning Calorimetry).

[0037] The above SiO 4 / 2 The silica structure having units (silica nanoparticles) is not particularly limited, but examples include fumed silica, calcined silica, precipitated silica, etc. 4 / 2 Silica structures (silica nanoparticles) having units may be used individually or in combination of two or more types.

[0038] The above SiO 4 / 2 From the viewpoint of improving the dispersibility of silica structures (silica fine particles) having units in curable organopolysiloxane compositions, silane coupling agents such as hexamethyldisilazane having hydrophobic groups and divinyltetramethyldisilazane having vinyl groups may be used.

[0039] (e) Other stripping control agents The back treatment layer 1 of the present invention is used to further increase the self-adhesion strength of the adhesive tape 10, by using SiO 4 / 2 It is preferable to include MQ resin as a release control agent other than silica structures having units. MQ resin is defined by the general formula R3SiO 1 / 2 The unit M, represented by the general formula SiO 4 / 2 This refers to a silicone resin having a three-dimensional structure consisting of Q units represented by [the formula shown]. More specifically, it is a component that effectively bleeds out onto the surface of the cured layer (back-treated layer) which is cured with a high crosslinking density by using component (a) above, thereby imparting a high peeling force to adhesive substances to the surface of the cured layer, i.e., increasing the self-back-side adhesion force.

[0040] The above MQ resins include (e)-1: MQ resins having an average of one or more alkenyl groups in the molecule, and (e)-2: MQ resins that do not have alkenyl groups, which are represented by the following average unit formulas. ·(e)-1 A molecule having an average of one or more alkenyl groups, with the average unit formula: (R 1 3SiO 1 / 2 )x(SiO 4 / 2 ) 1.0 (In the formula, R 1 R independently represents an alkenyl group having 2 to 10 carbon atoms, an unsubstituted or substituted monovalent hydrocarbon group having 1 to 10 carbon atoms without an aliphatic unsaturated bond, or a hydroxyl group or alkoxy group. 1 Organopolysiloxane resin (MQ resin) represented by (one or more of which are alkenyl groups, and x is a number between 0.5 and 2.0), ·(e)-2 Average unit formula: (R 2 3SiO 1 / 2 )y(SiO 4 / 2 ) 1.0 (In the formula, R 2 Organopolysiloxane resin (MQ resin) represented by (where is an unsubstituted or substituted monovalent hydrocarbon group having 1 to 10 carbon atoms that does not independently have an aliphatic unsaturated bond, and y is a number between 0.5 and 2.0)

[0041] In the average unit formula in (e)-1 above, R1 R independently represents an alkenyl group-containing organic group having 2 to 10 carbon atoms, an unsubstituted or substituted monovalent hydrocarbon group having 1 to 10 carbon atoms without an aliphatic unsaturated bond, or a hydroxyl group or alkoxy group. 1 One or more of these are organic groups containing an alkenyl group with 2 to 10 carbon atoms.

[0042] The above R 1 The organic group containing an alkenyl group having 2 to 10 carbon atoms is preferably one having 2 to 8 carbon atoms, for example, alkenyl groups such as vinyl group, allyl group, hexenyl group, and octenyl group; acryloylalkyl groups and methacryloylalkyl groups such as acryloylpropyl group, acryloylmethyl group, and methacryloylpropyl group; cycloalkenylalkyl groups such as cyclohexenylethyl group; and alkenyloxyalkyl groups such as vinyloxypropyl group, with vinyl group being particularly preferred. 1 Examples of unsubstituted or substituted monovalent hydrocarbon groups having 1 to 10 carbon atoms that do not have an aliphatic unsaturated bond include alkyl groups having 1 to 6 carbon atoms such as methyl, ethyl, propyl, and butyl groups; and aryl groups having 6 to 10 carbon atoms such as phenyl and tolyl groups. 1 A methyl group is preferred as the monovalent hydrocarbon group. 1 Examples of alkoxy groups include methoxy groups, ethoxy groups, and propoxy groups.

[0043] The above (e)-1 has an average of one or more alkenyl groups in one molecule, for example, R in the above average unit formula 1 Preferably, 5 to 30 mol% are alkenyl groups, 50 to 95 mol% are alkyl groups, and 0 to 20 mol% are hydroxyl groups.

[0044] In the above average unit formula, x is (SiO 4 / 2 (R) for units 1 3SiO 1 / 2This represents the molar ratio in units of 0.5 to 2.0, preferably between 0.5 and 1.0. If x is less than 0.5, when blended into the above-mentioned curable organopolysiloxane composition, the compatibility with other siloxane components may decrease, and a homogeneous cured layer may not be obtained. On the other hand, if x exceeds 2.0, the initial self-back adhesive strength may not increase sufficiently.

[0045] In the average unit formula in (e)-2 above, R 2 R is an unsubstituted or substituted monovalent hydrocarbon group having 1 to 10 carbon atoms that does not independently have an aliphatic unsaturated bond. Examples of unsubstituted or substituted monovalent hydrocarbon groups having 1 to 10 carbon atoms that do not have an aliphatic unsaturated bond include alkyl groups having 1 to 6 carbon atoms such as methyl, ethyl, propyl, and butyl groups; and aryl groups having 6 to 10 carbon atoms such as phenyl and tolyl groups. 2 A methyl group is preferred as the group.

[0046] (e)-2 above is R 2 In addition, hydroxyl groups and hydrolyzable alkoxy groups may be included, and their content should be 0 to 4.0% by mass of the total mass of (e)-2. Examples of the above alkoxy groups include methoxy groups, ethoxy groups, isopropoxy groups, butoxy groups, and phenoxy groups, and methoxy groups are preferred when used.

[0047] In the above average unit formula, y is (SiO₂ 4 / 2 (R) for units 2 3SiO 1 / 2 ) represents the molar ratio in units and is a number between 0.5 and 2.0, preferably between 0.5 and 1.0. If y is less than 0.5, when it is incorporated into the curable organopolysiloxane composition, the compatibility with other siloxane components may decrease and a homogeneous cured layer may not be obtained. On the other hand, if y exceeds 2.0, the initial self-back adhesive strength may not increase sufficiently.

[0048] The MQ resin described above is not particularly limited, and (e)-1 and (e)-2 may be used individually or in combination of two or more types. However, from the viewpoint of suppressing the transfer of silicone compounds from the back treatment layer 1 of the adhesive tape 10 to the adhesive layer 3, it is preferable to include an MQ resin having an average of one or more alkenyl groups in the molecule of (e)-1. By including an MQ resin having an average of one or more alkenyl groups in the molecule of (e)-1 as the MQ resin, the MQ resin that bleeds out near the surface of the adhesive layer 3 is fixed on the surface of the adhesive layer 3 by an addition reaction with the above-mentioned component (b). This increases the self-back adhesive strength more stably and also suppresses the decrease in the adhesive strength of the adhesive layer 3 of the adhesive tape 10 to the adherend (plating target material) (and also suppresses the transfer of silicone compounds).

[0049] The amount of MQ resin having an average of one or more alkenyl groups in the molecule of (e)-1 described above is not particularly limited, and is, for example, 5% by mass or more in the curable organopolysiloxane composition, and may be 9% by mass or more, 16% by mass or more, or 31% by mass or more, from the viewpoint of effectively exhibiting the effect of adding a release control agent. The upper limit of the amount of component (e)-1 in the curable organopolysiloxane composition is, for example, 75% by mass or less, may be 59% by mass or less, or may be 49% by mass or less. In one preferred embodiment, the amount of component (e)-1 described above may be in the range of 9 to 17% by mass, 9 to 59% by mass, 31 to 49% by mass, 31 to 75% by mass, or 9 to 75% by mass.

[0050] For (e)-1 above, commercially available products may be used, such as "DOWSIL SD 7292" (product name) and "DOWSIL BY 24-4980" (product name) from Dow Toray Industries, Inc., and "KS-3800" (product name) from Shin-Etsu Chemical Co., Ltd.

[0051] Furthermore, when the back treatment layer 1 contains MQ resin that does not have the alkenyl group of (e)-2 described above, the amount of (e)-2 is not particularly limited and is, for example, 10% by mass or more in the curable organopolysiloxane composition, and may be 20% by mass or more, 27% by mass or more, 33% by mass or more, or 36% by mass, from the viewpoint of effectively exhibiting the effect of adding a release control agent. The upper limit of the amount of component (e)-2 in the curable organopolysiloxane composition is, for example, less than 55% by mass, may be 50% by mass or less, may be 41% by mass or less, or may be 31% by mass or less. In one preferred embodiment, the amount of component (e)-2 described above may be in the range of 33 to 54.5% by mass, may be in the range of 20 to 41% by mass, or may be in the range of 20 to 54.5% by mass.

[0052] For (e)-2 above, commercially available products may be used, such as "DOWSIL BY 24-843" (product name) manufactured by Dow Toray Corporation.

[0053] (f) Other optional components Furthermore, known hydrosilylation reaction control agents, antioxidants, pigments, stabilizers, antistatic agents, defoaming agents, adhesion enhancers, thickeners, or inorganic fillers other than silica (e.g., alumina) may be added as needed, within the limits that do not impede the effects of the present invention. The amount of each addition may be appropriately selected in accordance with the prior art.

[0054] The addition-reactive silicone resin composition of the present invention can be used by directly applying it to a substrate if the viscosity of the composition is low. However, it is generally used after being dissolved in a solvent to improve workability during application and processing, and to further improve the storage stability of the composition. Examples of solvents in this case include aromatic hydrocarbons such as benzene, toluene, and xylene; aliphatic hydrocarbons such as heptane, hexane, and pentane; halogenated hydrocarbons such as trichloroethylene and perchloroethylene; ethyl acetate; and methyl ethyl ketone.

[0055] <Addition-reactive silicone resin composition> The addition-reactive silicone resin composition can be prepared, for example, by first uniformly mixing the above components other than (c) the platinum group metal curing catalyst, and then adding component (c) immediately before use. This manufacturing method is preferred from the viewpoint of ensuring pot life. Components (a), (b), and (d) may be silicone resin compositions that have been prepared in advance as compositions containing any of these components. For example, "DOWSIL SRX 370" (product name) manufactured by Dow-Toray can be used.

[0056] <Formation of back-side treatment layer 1> The back treatment layer 1 can be formed by coating and curing an addition-reactive silicone resin composition on one side of the substrate 2. The coating method is not particularly limited, but for example, the above composition can be applied to the surface of the substrate 2 at a rate of 0.01 to 100 g / m² using coating methods such as coating with a comma coater, lip coater, roll coater, die coater, knife coater, blade coater, rod coater, kiss coater, gravure coater, and wire bar coater, screen coating, dipping coating, or cast coating. 2 After coating, a cured film can be formed on the surface of the substrate 2 by heating at a temperature in the range of 50 to 200°C for 1 to 180 seconds. To improve adhesion with the back treatment layer 1 (cured film), the substrate 2 may be one which has been subjected to corona treatment, etching treatment, primer treatment, or plasma treatment on its surface.

[0057] <Base material 2> As the base material 2, a metal foil is used. The metal foil is not particularly limited as long as it has chemical resistance, but examples include stainless steel foil, zinc foil, copper foil, aluminum foil, and lead foil. Among these, zinc foil and aluminum foil are preferred from the viewpoint of ease of handling and the clarity of the plating line when the adhesive tape 10 is peeled off again after the plating is completed, and soft aluminum foil is more preferably used from the viewpoint of conformability when attaching the adhesive tape 10 to the material to be plated and better tearability by hand.

[0058] Furthermore, the thickness of the substrate 2 is not particularly limited, but is preferably in the range of 30 μm to 200 μm. The lower limit of the thickness of the substrate 2 is more preferably 50 μm, and even more preferably 75 μm. The upper limit is more preferably 150 μm, and even more preferably 125 μm. Specifically, the thickness of the substrate 2 is more preferably in the range of 50 μm to 150 μm, and even more preferably in the range of 75 μm to 125 μm.

[0059] Furthermore, the substrate 2 may be subjected to surface treatment as needed for purposes such as improving adhesion with the adhesive layer 3. The surface treatment applied to the substrate 2 is not particularly limited, but examples include corona treatment, plasma treatment, and anchor coating treatment. Among these, anchor coating treatment, in which an anchor coating agent is applied to the surface of the substrate 2 to form the intermediate layer 4, is preferred.

[0060] <Adhesive layer 3> The adhesive layer 3 consists of an adhesive composition comprising A) a styrene-isoprene-styrene block (SIS) copolymer and B) a tackifying resin.

[0061] (Styrene-isoprene-styrene block copolymer) The styrene-isoprene-styrene block (SIS) copolymer contained in the adhesive composition constituting the adhesive layer 3 is composed of polystyrene blocks and polyisoprene blocks, and includes styrene-isoprene diblock copolymer and styrene-isoprene-styrene triblock copolymer. Since the styrene-isoprene-styrene block (SIS) copolymer is stable in acidic or basic aqueous solutions, it can be a suitable adhesive material for the adhesive layer 3 of a plating masking adhesive tape.

[0062] The styrene-isoprene-styrene block copolymer described above may have either a linear or radial polymer structure. However, when it has a linear structure, it is highly flexible, resulting in excellent adhesion to various substrates and making it easier to maintain a balance between adhesive performance and appropriate heat resistance. Therefore, the styrene-isoprene-styrene block copolymer used in the adhesive composition constituting the adhesive layer 3 is preferably a linear structure consisting of a styrene-isoprene diblock copolymer and a styrene-isoprene-styrene triblock copolymer. A linear styrene-isoprene block copolymer and a styrene-isoprene-styrene triblock copolymer refer to a linear copolymer in which styrene blocks and isoprene blocks are bonded together.

[0063] Furthermore, the styrene-isoprene-styrene block copolymer described above may be unhydrogenated or hydrogenated. Specifically, "unhydrogenated styrene-isoprene-styrene block copolymer" refers to a block copolymer in which the isoprene-based block has not been hydrogenated. Specifically, "hydrogenated styrene-isoprene-styrene block copolymer" refers to a block copolymer in which all or part of the isoprene-based block has been hydrogenated. From the viewpoint of versatility and cost, the styrene-isoprene-styrene block copolymer described above is preferably unhydrogenated.

[0064] As the styrene-isoprene-styrene block copolymer, from the viewpoint of masking properties, adhesive residue, and adhesive breakability of the adhesive tape 10, a copolymer with a styrene-isoprene diblock content (SI diblock content) in the range of 50% by mass or more and 80% by mass or less is used. The lower limit of the above styrene-isoprene diblock content is preferably 53% by mass, more preferably 55% by mass. The upper limit is preferably 79% by mass, more preferably 78% by mass. Specifically, the above styrene-isoprene diblock content (SI diblock content) is preferably in the range of 53% by mass or more and 79% by mass or less, and more preferably in the range of 55% by mass or more and 78% by mass or less.

[0065] In other words, if the amount of SI diblocks in the styrene-isoprene-styrene block copolymer is less than 50% by mass, the amount of styrene-isoprene-styrene triblocks (SIS triblocks), which have a strong cohesive force, increases, and the number of pseudo-crosslinked sites (polystyrene domains) increases. As a result, the cohesive force of the adhesive layer 3 increases, making it less likely for the adhesive layer 3 to undergo cohesive failure when the adhesive tape 10 is re-peeled off, which is good for adhesive residue, but it may result in poor adhesive tearing of the adhesive layer 3 when the adhesive tape 10 is cut by hand. In this case, the adhesive layer 3 may peel off from the substrate 2 at the cut end of the adhesive tape 10, making it impossible to adhere it cleanly to the material to be plated, and the adhesion, i.e., the masking performance, may be insufficient. Furthermore, depending on the physical properties of the tackifying resin contained in the adhesive layer 3, the adhesive layer 3 may harden, for example, resulting in poor conformability to minute irregularities in the material to be plated, poor adhesion at the interface between the adhesive layer 3 and the adherend, and the risk of poor masking. As a result, the plating solution may penetrate the unplated areas, potentially worsening the clarity of the plating lines. Furthermore, as the adhesive layer 3 hardens, its adhesion to the metal foil of the substrate 2 tends to decrease. Depending on the material and surface roughness of the metal foil, as well as the type and amount of tackifying resin added, the adhesive layer 3 may peel off the metal foil of the substrate 2 when the adhesive tape 10 is re-peeled, potentially transferring as adhesive residue to the unplated areas of the material to be plated.

[0066] On the other hand, if the amount of SI diblocks in the styrene-isoprene-styrene block copolymer exceeds 80% by mass, the amount of SIS triblocks, which have high cohesive force, decreases, and the pseudo-crosslinking sites (polystyrene domains) decrease. As a result, the cohesive force of the adhesive layer 3 decreases, and there is a risk that adhesive residue will be generated on the non-plated parts when the adhesive tape 10 is peeled off again.

[0067] Furthermore, the amount of styrene in the styrene-isoprene-styrene block copolymer contained in the adhesive layer 3 is in the range of 13% by mass or more and 18% by mass or less, from the viewpoint of the masking properties and adhesive residue of the adhesive tape 10. The lower limit of the above styrene amount is preferably 14% by mass, more preferably 15% by mass. The upper limit is preferably 17% by mass, more preferably 16% by mass. Specifically, the above styrene amount is preferably in the range of 14% by mass or more and 17% by mass or less, and more preferably in the range of 15% by mass or more and 16% by mass or less.

[0068] In other words, if the amount of styrene in the styrene-isoprene-styrene block copolymer is less than 13% by mass, the cohesive force of the adhesive layer 3 decreases as the pseudo-crosslinking sites (polystyrene domains) decrease, which may result in adhesive residue being generated on the non-plated parts when the adhesive tape 10 is peeled off again.

[0069] On the other hand, if the amount of styrene in the styrene-isoprene-styrene block copolymer exceeds 18% by mass, the adhesive layer 3 hardens as the number of pseudo-crosslinked sites (polystyrene domains) increases. For example, this can lead to poor conformability to minute irregularities in the material to be plated, poor adhesion at the interface between the adhesive layer 3 and the adherend, and the risk of masking failure. As a result, the plating solution may penetrate the unplated areas, potentially resulting in poor clarity of the plating lines.

[0070] Thus, in the styrene-isoprene-styrene block copolymer described above, if the styrene content is in the range of 13% to 18% by mass and the styrene-isoprene block content is in the range of 50% to 80% by mass, the two factors of "interface adhesion" and "cohesive force" of the adhesive layer 3 can be balanced and contributed to. Therefore, by using a tackifying resin having acid groups, as described later, in combination to set the acid value of the adhesive layer 3, i.e., the adhesive composition constituting it, within a specific range, it becomes easy to achieve both the masking properties of the adhesive tape 10 and the absence of adhesive residue when re-peeled, even when used under harsh plating conditions. Furthermore, when the adhesive tape 10 is cut by hand, the adhesive tearability of the adhesive layer 3, i.e., its ease of tearing by hand, is good, so the peeling of the adhesive layer 3 from the substrate 2 at the cut portion of the adhesive tape 10 is suppressed, and it can be neatly attached to the material to be plated without causing poor adhesion.

[0071] Furthermore, the mass-average molecular weight (Mw) of the styrene-isoprene-styrene block copolymer contained in the adhesive layer 3 is not particularly limited, but is preferably in the range of 150,000 to 250,000. If the mass-average molecular weight (Mw) of the styrene-isoprene-styrene block copolymer is less than 50,000, the cohesive force of the adhesive layer 3 decreases, which may result in adhesive residue being generated on the non-plated parts when the adhesive tape 10 is peeled off again.

[0072] On the other hand, when the mass-average molecular weight (Mw) of the styrene-isoprene-styrene block copolymer exceeds 250,000, the cohesive force of the adhesive layer 3 tends to increase. For example, this can lead to poor conformability to minute irregularities in the material to be plated, poor adhesion at the interface between the adhesive layer 3 and the adherend, and the risk of masking failure. As a result, the plating solution may penetrate the unplated areas, potentially resulting in poor clarity of the plating lines.

[0073] Furthermore, the adhesive layer 3 containing the styrene-isoprene-styrene block copolymer may also contain other synthetic rubbers, natural rubbers, etc., in addition to the styrene-isoprene-styrene block copolymer, to the extent that it does not impair its properties.

[0074] (Adhesive-granting resin) The adhesive composition constituting the adhesive layer 3 contains at least one tackifying resin having acid groups. Having acid groups means containing acid groups in a substantial amount. For example, a tackifying resin with an acid value of 1.5 mg KOH / g or more is considered a tackifying resin having acid groups. The tackifying resin having acid groups may also be a tackifying resin in which acid groups have been introduced by acid modification of a tackifying resin that does not have acid groups.

[0075] "Without acid groups" means that the substance does not contain acid groups in substantial amounts. For example, a tackifying resin with an acid value of less than 1.5 mg KOH / g is considered a tackifying resin without acid groups. Examples of tackifying resins without acid groups include petroleum resins (e.g., aliphatic (C5), alicyclic (DCPD), aromatic (C9), aliphatic / aromatic copolymer (C5 / C9) hydrocarbon resins, etc.), terpene resins (e.g., α-pinene, β-pinene, dipentene, etc.), coumarone-indene resins, styrene resins, xylene resins, and resins obtained by hydrogenating these resins.

[0076] Furthermore, the meaning of "acid modification" as described above includes polymerizing monomer units having acidic functional groups, such as carboxylic acid group-containing monomers, carboxylic acid ester group-containing monomers, or acid anhydride group-containing monomers, onto a tackifying resin that does not have the aforementioned acid groups.

[0077] Examples of monomers containing carboxylic acid groups include maleic acid, fumaric acid, acrylic acid, methacrylic acid, and itaconic acid. Examples of monomers containing carboxylic acid ester groups include vinyl acetate, vinyl propionate, and vinyl benzoate. Examples of monomers containing acid anhydride groups include maleic anhydride, fumaric anhydride, and itaconic anhydride.

[0078] Methods for polymerizing the above-mentioned monomer having an acidic functional group onto a tackifying resin that does not have an acidic group include polymerization methods that are known in themselves. For example, one method is to graft polymerize the above-mentioned monomer having an acidic functional group onto a tackifying resin that does not have an acidic group in the presence of a radical polymerization initiator.

[0079] In the graft polymerization method described above, organic peroxides such as hydroperoxides, dialkylperoxides, and diacylperoxides can be used as radical polymerization initiators. Other methods include dissolving a tackifying resin without acid groups and an acid anhydride group-containing monomer in an organic solvent such as xylene, adding the initiator, and heating and stirring to cause a reaction, or heating and melting a tackifying resin without acid groups without using a solvent, and then adding the acid anhydride group-containing monomer and initiator to cause a reaction.

[0080] The acid value, which represents the amount of acid groups in the tackifying resin having the above-mentioned acid groups, has a lower limit of preferably 1.5 mg KOH / g, more preferably 5.0 mg KOH / g, and even more preferably 10.0 mg KOH / g. The upper limit is not particularly limited, but for example, it is 25.0 mg KOH / g. Specifically, the acid value of the tackifying resin having the above-mentioned acid groups is preferably in the range of 1.5 mg KOH / g to 25.0 mg KOH / g, more preferably in the range of 5.0 mg KOH / g to 25.0 mg KOH / g, and even more preferably in the range of 10.0 mg KOH / g to 25.0 mg KOH / g. If the above acid value is less than 1.5 mg KOH / g, the acid modification effect tends not to be sufficiently obtained. Depending on the type and amount of tackifying resin added, or the type of styrene-isoprene-styrene block copolymer mentioned above, the adhesion between the adhesive layer 3 and the adherend, i.e., the masking properties, may be insufficient, causing the plating solution to penetrate the unplated areas and potentially resulting in poor clarity of the plating lines. Furthermore, the adhesion (anchoring force) of the adhesive layer 3 to the substrate 1 and intermediate layer 4 may be insufficient, potentially resulting in adhesive residue on the unplated areas when the adhesive tape 10 is peeled off again.

[0081] Commercially available tackifying resins having the above-mentioned acid groups can also be used. Specifically, for example, maleic anhydride-modified aliphatic (C5) hydrocarbon resins such as Quintone (product name) CX495 (product name, acid value: 1.8 mg KOH / g, softening point: 96°C), Quintone (product name) C200H (product name, acid value: 1.7 mg KOH / g, softening point: 101°C), Quintone (product name) C210 (product name, acid value: 1.7 mg KOH / g, softening point: 110°C) manufactured by Nippon Zeon Co., Ltd., as well as Quintone (product name) E200SN (product name, acid value: 1.7 mg KOH / g, softening point: 102°C), Quintone (product name) D295 (product name, acid value: 8.0 mg KOH / g, softening point: 94°C), Quintone (product name) Examples include maleic anhydride-modified aliphatic / aromatic (C5 / C9) hydrocarbon resins such as D200 (trade name, acid value: 17.0 mg KOH / g, softening point: 102°C).

[0082] Among the tackifying resins having the above-mentioned acid groups, aliphatic / aromatic copolymer (C5 / C9) hydrocarbon resins are preferred from the viewpoint of compatibility with the styrene-isoprene-styrene block copolymer and the above-mentioned tackifying resins having the above-mentioned acid groups.

[0083] The adhesive composition constituting the adhesive layer 3 may include an acid-free tackifying resin, as exemplified below.

[0084] The above-mentioned aliphatic (C5) hydrocarbon resin is not particularly limited, but commercially available products such as Quintone (trade name) R100 (trade name, softening point: 96℃), Quintone (trade name) M100 (trade name, softening point: 95℃), Quintone (trade name) A100 (trade name, softening point: 100℃) manufactured by Nippon Zeon Corporation, and T-REZ RB093 (trade name, softening point: 93℃), T-REZ RB100 (trade name, softening point: 100℃), T-REZ RC100 (trade name, softening point: 100℃), and T-REZ RC115 (trade name, softening point: 115℃) manufactured by TonenGeneral Sekiyu K.K. can be used.

[0085] The above-mentioned aliphatic / aromatic copolymer (C5 / C9) hydrocarbon resin is not particularly limited, but commercially available products such as Quintone (trade name) N180 (trade name, softening point: 80°C), Quintone (trade name) S195 (trade name, softening point: 94°C), Quintone (trade name) D100 (trade name, softening point: 99°C) from Nippon Zeon Corporation, and T-REZ RD104 (trade name, softening point: 104°C) from TonenGeneral Sekiyu K.K. can be used.

[0086] The above-mentioned hydrogenated petroleum resin is not particularly limited, but commercially available products such as AlconP-100 (trade name, softening point: 100℃), AlconP-115 (trade name, softening point: 115℃), AlconP-125 (trade name, softening point: 125℃) manufactured by Arakawa Chemical Industries, Ltd., and T-REZ HA085 (trade name, softening point: 85℃), T-REZ HA103 (trade name, softening point: 103℃), T-REZ HA125 (trade name, softening point: 125℃) manufactured by TonenGeneral Sekiyu K.K. can be used.

[0087] The above-mentioned terpene resin is not particularly limited, but commercially available products such as YS Resin PX800 (product name, softening point: 80°C), YS Resin PX1000 (product name, softening point: 100°C), YS Resin PX1150 (product name, softening point: 115°C), YS Resin PX1250 (product name, softening point: 125°C), and YS Resin TO115 (product name, softening point: 115°C) manufactured by Yasuhara Chemical Co., Ltd. can be used.

[0088] Among the tackifying resins that do not have the above-mentioned acid groups, aliphatic / aromatic copolymer (C5 / C9) hydrocarbon resins, hydrogenated petroleum resins, and terpene resins are preferred from the viewpoint of compatibility with the above-mentioned styrene-isoprene-styrene block copolymer and the tackifying resins that have the above-mentioned acid groups, and from the viewpoint of controlling the balance between adhesive strength (adhesion) and re-peelability to the material to be plated, with hydrogenated petroleum resins and terpene resins being more preferred.

[0089] The content of the tackifying resin having acid groups in the adhesive composition constituting the adhesive layer 3 can be appropriately adjusted according to the acid value of the tackifying resin used, such that the acid value of the adhesive composition is in the range of 0.3 mg KOH / g to 5.5 mg KOH / g. In this case, the total content of the tackifying resin, i.e., the total content of the tackifying resin having acid groups and the tackifying resin not having acid groups, is preferably adjusted to be in the range of 20 parts by mass to 107 parts by mass per 100 parts by mass of the styrene-isoprene-styrene block copolymer. The lower limit of the total content of the tackifying resin is more preferably 25 parts by mass, and even more preferably 40 parts by mass. The upper limit of the total content of the tackifying resin is preferably 100 parts by mass, and even more preferably 70 parts by mass. Specifically, the total content of the tackifying resin is more preferably in the range of 25 parts by mass to 100 parts by mass, and even more preferably in the range of 40 parts by mass to 70 parts by mass.

[0090] If the total content of the above-mentioned tackifying resins is less than 20 parts by mass, the effect of adding the tackifying resins is insufficient, and the amount of styrene-isoprene-styrene block copolymer in the adhesive layer 3 becomes too high. In particular, if the amount of styrene-isoprene diblock (SI diblock) is low or the amount of styrene is high, it may not be possible to sufficiently reduce the elastic modulus of the rubbery flat area of ​​the adhesive layer 3 at room temperature. In this case, the adhesive strength (adhesion) and tack of the adhesive layer 3 to the material to be plated will decrease, which may cause poor masking due to penetration of the plating solution into the unplated areas during the series of plating processes, and may result in poor clarity of the plating lines.

[0091] On the other hand, if the total content of the tackifying resin exceeds 107 parts by mass, the content of styrene-isoprene-styrene block copolymer in the adhesive layer 3 decreases, and the content ratio of oligomer tackifying resin increases. As a result, the tackifying resin begins to be unevenly distributed on the surface of the adhesive layer 3, and in particular, if the content of tackifying resin with a high acid value is high, the hydrophilicity of the surface of the adhesive layer 3 tends to increase. In this case, the plating solution can easily penetrate the unplated areas through the adhesive layer 3, which may result in poor clarity of the plating lines. Furthermore, in particular, if the amount of styrene-isoprene diblock (SI diblock) in the styrene-isoprene-styrene block copolymer is high, or if the amount of styrene is low, if it adheres strongly due to the effect of excessive acid groups, or if the cohesive force of the surface of the adhesive layer 3 decreases, there is a risk of contamination of the unplated areas with adhesive residue when the adhesive tape 10 is peeled off again.

[0092] When the total content of the tackifying resin is within the above range, it becomes easy to adjust the acid value of the adhesive composition constituting the adhesive layer 3 to a range of 0.3 mg KOH / g to 5.5 mg KOH / g, and both factors—interface adhesion (tackiness) that can suppress the penetration of the plating solution and cohesive force that can suppress the generation of adhesive residue when re-peeled—are well-balanced in the adhesive layer 3. As a result, it becomes possible to achieve both the masking properties of the adhesive tape 10 and the absence of adhesive residue when re-peeled, even when used under harsh plating conditions.

[0093] The tackifying resin described above is an oligomer with a mass-average molecular weight (Mw) of less than 10,000, but the mass-average molecular weight (Mw) is preferably in the range of 1,000 to 6,000, and more preferably in the range of 1,400 to 4,000.

[0094] The above-mentioned tackifying resins with a mass-average molecular weight (Mw) of less than 1,000 may reduce the cohesive force of the adhesive layer 3, especially if their content is high. Furthermore, when acid-modified, the effect of the acid modification tends to be minimal.

[0095] On the other hand, tackifying resins with a mass-average molecular weight (Mw) exceeding 6,000 may, depending on their structure, become too hard, hardening the adhesive layer 3. This reduces their effectiveness as tackifiers, potentially leading to poor conformability to minute irregularities in the material to be plated, poor adhesion at the interface between the adhesive layer 3 and the adherend, and resulting in masking failure. Consequently, the plating solution may penetrate the unplated areas, potentially reducing the clarity of the plating lines.

[0096] Furthermore, the tackifying resin described above preferably has a softening point in the range of 80°C to 135°C. The lower limit of the softening point is more preferably 90°C, and even more preferably 96°C. The upper limit is more preferably 125°C, and even more preferably 120°C. Specifically, the softening point is more preferably in the range of 90°C to 125°C, and even more preferably in the range of 96°C to 120°C. In this specification, the softening point of the tackifying resin refers to the value measured in accordance with JIS K 2531.

[0097] If the softening point of the tackifying resin is below 80°C, and especially if a large amount of tackifying resin is added, the cohesive force of the adhesive layer 3 tends to decrease. Therefore, when the adhesive tape 10 is peeled off again, there is a risk of contamination of the non-plated surface due to adhesive residue.

[0098] On the other hand, if the softening point of the tackifying resin exceeds 135°C, in particular, if the amount of styrene-isoprene diblock (SI diblock) in the styrene-isoprene-styrene block copolymer is small, or if the amount of styrene is large, the elastic modulus of the rubbery flat region of the adhesive layer 3 near room temperature tends to become excessively large. In this case, the adhesive strength (tackiness) and tack of the adhesive layer 3 to the material to be plated will decrease, which may cause poor masking due to penetration of the plating solution into the unplated areas during the series of plating processes, potentially resulting in poor clarity of the plating lines.

[0099] (Other additives) Furthermore, the adhesive composition constituting the adhesive layer 3 may contain additives such as softeners (process oils, etc.), anti-aging agents (hindered phenol-based antioxidants, etc.), heat stabilizers, colorants, flame retardants, and crosslinking agents, to the extent that they do not impair the effects of the present invention.

[0100] The above-mentioned softening agents are generally added to rubbers such as styrene-isoprene-styrene block copolymers to impart plasticity, i.e., appropriate tackiness, or to improve the processability of the rubber. However, depending on the type and amount added, adhesive residue may easily form on the adherend. Therefore, from the viewpoint of preventing adhesive residue, it is preferable not to add the above-mentioned softening agents to the adhesive composition constituting the adhesive layer 3. The adhesive composition constituting the adhesive layer 3 uses a relatively soft styrene-isoprene-styrene block copolymer as the base polymer, with a styrene-isoprene block content in the range of 50% to 80% by mass. In addition, a tackifying resin having acid groups is used in combination to adjust the acid value to an appropriate range. Therefore, it is possible to ensure appropriate tackiness (adhesion) without adding a softening agent.

[0101] (Adhesive layer) The adhesive layer 3, that is, the adhesive composition constituting it, has an acid value within a specific range, namely, an acid value in the range of 0.3 mg KOH / g to 5.5 mg KOH / g. The lower limit of the acid value is preferably 0.4 mg KOH / g, more preferably 0.6 mg KOH / g. The upper limit is preferably 5.1 mg KOH / g, more preferably 3.0 mg KOH / g. Specifically, the acid value of the adhesive composition constituting the adhesive layer 3 is preferably in the range of 0.4 mg KOH / g to 5.1 mg KOH / g, and more preferably in the range of 0.6 mg KOH / g to 3.0 mg KOH / g.

[0102] If the acid value of the adhesive layer 3 is less than 0.3 mg KOH / g, the lack of acid groups may result in insufficient adhesion to the material to be plated, for example, leading to poor masking during plating and the risk of the plating solution penetrating the unplated areas. As a result, the clarity of the plated lines may be reduced. In addition, the anchoring ability (adhesion) to the substrate 2 tends to be poor, so depending on the material of the substrate 2 and the intermediate layer 4, adhesive residue may be left on the unplated areas when the adhesive tape 10 is peeled off again.

[0103] On the other hand, if the acid value of the adhesive layer 3 exceeds 5.5 mg KOH / g, the hydrophilicity may become too high due to the excess acid groups, which may cause the plating solution to easily penetrate the unplated areas through the adhesive layer. As a result, the clarity of the plating line may be reduced. Also, if the content of the tackifying resin is particularly high, depending on the type and properties of the tackifying resin, the adhesion to the material to be plated may decrease, resulting in poor masking during plating, which may cause the plating solution to penetrate the unplated areas. As a result, the clarity of the plating line may be reduced. Furthermore, in this case, the cohesive force of the adhesive layer 3 may decrease, which may cause adhesive residue to be left on the unplated areas when the adhesive tape 10 is peeled off again.

[0104] The acid value of the adhesive layer 3 can be adjusted, for example, by increasing or decreasing the acid value by changing the conditions for acid modification of the tackifying resin. Alternatively, it can be adjusted by mixing multiple types of components with different acid values. Examples of multiple types of components with different acid values ​​include tackifying resins having acid groups and tackifying resins without acid groups.

[0105] The acid value of adhesive layer 3 can be determined in accordance with JIS K 5601-2-1:1999. Alternatively, if the acid value of the material used is known, it can be calculated from the amount of the adhesive composition.

[0106] The thickness of the adhesive layer 3 is not particularly limited, but from the viewpoint of balancing adhesion (tackiness) to the plated material and re-peelability, as well as ease of handling, a range of 20 μm to 100 μm is preferred. The lower limit of the thickness of the adhesive layer 3 is more preferably 25 μm. The upper limit is more preferably 75 μm. Specifically, the thickness of the adhesive layer 3 is preferably in the range of 25 μm to 75 μm.

[0107] The adhesive tape 10, which has such an adhesive layer 3 on the base material 2, preferably has a 180° peel adhesive strength (hereinafter sometimes simply referred to as "180° peel adhesive strength") to a stainless steel plate (SUS304 plate, #360 polished finish) measured at a peeling speed of 5 mm / second in accordance with the method described in JIS Z 0237 (2009), after being attached to a stainless steel plate (SUS304 plate, #360 polished finish) and stored for 96 hours in a temperature and humidity environment of 50°C and 90%RH, is preferably 7.0 N / 10 mm or more, more preferably 9.0 N / 10 mm or more, and even more preferably 10.0 N / 10 mm or more. Furthermore, the above 180° peel adhesive strength is preferably smaller than the adhesion force between the base material 2 and the adhesive layer 3, which will be described later, from the viewpoint of suppressing adhesive residue on the unplated parts of the material to be plated when the adhesive tape 10 is peeled off again.

[0108] The 180° peel adhesive strength of the adhesive tape 10 described above is measured by the following method. First, the adhesive tape 10 is attached to a stainless steel plate (SUS304 plate, #360 polished finish), and a 2000g roller is passed back and forth once at a speed of 5mm / second to press it down. Next, the sample with the adhesive tape 10 attached to the stainless steel plate (SUS304 plate, #360 polished finish) is left to stand and stored for 96 hours in a constant temperature chamber adjusted to a temperature and humidity environment of 50°C and 90%RH. After 96 hours of storage, the sample is removed and left to stand for 30 minutes in an environment of 23°C and 50%RH, and then the adhesive strength is measured when the tape is peeled off the stainless steel plate (SUS304 plate, #360 polished finish) at a speed of 5mm / second in a 180° direction using a tensile testing machine.

[0109] <Middle Class 4> An anchor coating agent may be applied to the surface of the base material 2 to form an intermediate layer 4, if necessary, for purposes such as improving adhesion with the adhesive layer 3. By forming the intermediate layer 4, the adhesion between the base material 2 and the adhesive layer 3 can be stably increased, making it less likely for adhesive residue to be generated on the non-plated parts when the adhesive tape 10 is peeled off again. In addition, when the adhesive tape 10 is cut by hand or with a utility knife, it is possible to suppress the peeling of a portion of the adhesive layer 3 from the base material 2 at the cut edge.

[0110] The adhesion force between the base material 2 and the adhesive layer 3 in the adhesive tape 10 is not particularly limited, but from the viewpoint of suppressing adhesive residue on the unplated portion of the material to be plated when the adhesive tape 10 is re-peeled, it is preferable that it is greater than the 180° peel adhesion force to the stainless steel plate (SUS304 plate, #360 polished finish) described above. The adhesion force between the base material 2 and the adhesive layer 3 is preferably 11.0 N / 10 mm or more, more preferably 12.0 N / 10 mm or more, and even more preferably 13.0 N / 10 mm or more.

[0111] The adhesion force between the base material 2 and the adhesive layer 3 is measured by the following method. First, the adhesive layer side of a rubber-based adhesive tape (model number: No. 6200 / film tape) made of a PET base material manufactured by Maxell Corporation is attached to the surface of the adhesive layer 3 of the adhesive tape 10, and pressure is applied by moving a 2000g roller back and forth once at a speed of 5 mm / second. After standing and curing for 30 minutes in an environment of 23°C and 50%RH, the adhesive tape is peeled off at a speed of 5 mm / second in a 180° direction relative to the adhesive tape 10 using a tensile testing machine, and the adhesion force at the interface between the base material 2 and the adhesive layer 3 is measured.

[0112] The material of the anchor cart used to form the intermediate layer 4 is not particularly limited, but from the viewpoint of achieving both resistance to plating solutions and adhesion, a modified polyolefin resin having acid groups or hydroxyl groups is preferred, and a modified polyolefin resin having acid groups is more preferred.

[0113] The above-mentioned modified polyolefin resin having an acid group, so-called acid-modified polyolefin resin, is a compound obtained by graft polymerization of an unsaturated carboxylic acid and / or its acid anhydride onto a polyolefin. Specifically, for example, an unsaturated carboxylic acid and / or its acid anhydride are bonded to the main chain polyolefin via one of the carbon atoms adjacent to the contained carbonyl group, forming a side chain.

[0114] Commercially available modified polyolefin resins having the above-mentioned acid groups can be used, for example, Unistoll P-902, Unistoll P-802, and Unistoll P-501 (all product names) manufactured by Mitsui Chemicals, Inc., Cornova MPOA502 and Cornova MPO A201 (all product names) manufactured by Nippon Seema Co., Ltd., "Hardren" (product name) manufactured by Toyobo Co., Ltd., "Aurolene" (product name) manufactured by Nippon Paper Chemical Co., Ltd., "Surfren" (product name) manufactured by Mitsubishi Chemical Corporation, "Sumifit" (product name) manufactured by Sumika Chemtex Co., Ltd., and "Zychsen" (product name) manufactured by Sumitomo Seika Co., Ltd.

[0115] The modified polyolefin resin having the above-mentioned acid group can be prepared by well-known and conventional methods. For example, it can be prepared by melt-kneading a polyolefin before acid modification with an unsaturated carboxylic acid or its acid anhydride in the presence of a radical generating agent such as an organic peracid or peroxide. Examples of polyolefins before acid modification used in the preparation of acid-modified polyolefins include α-olefin homopolymers having 2 to 10 carbon atoms such as ethylene, propylene, 1-butene, 1-hexene, 3-methyl-1-butene, 4-methyl-1-pentene, 1-heptene, 1-octene, and 1-decene; random or block polymers of two or more of the above α-olefins; random, block, or graft polymers of the above α-olefins with other monomers; or mixtures of these polymers.

[0116] Furthermore, examples of polyolefin resins having hydroxyl groups include polyolefin resins having hydroxyl groups at the molecular ends. Note that polyolefin resins are the same as described above, so their explanation will be omitted. Polyolefin resins having hydroxyl groups at the molecular ends can be obtained, for example, by polymerizing conjugated diene monomers by known methods such as anionic polymerization, hydrolyzing the resulting polymer, and then hydrogenating it.

[0117] Commercially available polyolefin resins having the hydroxyl groups mentioned above can be used, for example, Polytail H (trade name) manufactured by Mitsubishi Chemical Corporation, and Unistoll P-901 and Unistoll P-801 (both trade names) manufactured by Mitsui Chemicals, Inc.

[0118] In addition to the above-mentioned polyolefin resin having acid or hydroxyl groups, the intermediate layer 4 may further contain crosslinking agents such as polyfunctional epoxy compounds and other additives, to the extent that they do not hinder the effects of the present invention.

[0119] The thickness of the intermediate layer 4 is not particularly limited, but for example, it can be 0.05 g / m² as a coating amount. 2 More than 0.5g / m 2 The following range is preferable.

[0120] <Removable Liner> In the adhesive tape 10 of the present invention, if a release liner is used as necessary, the release liner is not particularly limited, but for example, a film such as paper, polyethylene, polypropylene, or polyethylene terephthalate can be used that has been subjected to a release treatment to improve its release properties from the adhesive layer 3.

[0121] Furthermore, the thickness of the release liner is not particularly limited, but is usually in the range of 25 μm to 125 μm.

[0122] <Formation of adhesive layer 3> The adhesive layer 3 can be formed by applying and drying a solution of the adhesive composition to the other side of the substrate 2 where the release agent layer 1 is not formed. In this case, to improve the adhesion between the substrate 2 and the adhesive layer 3, an intermediate layer 4 may be provided by applying and drying a solution of a resin such as a modified polyolefin resin on the substrate 2 beforehand. Subsequently, if necessary, the release treatment side of the release liner is bonded onto the formed adhesive layer 3. After that, by heating and curing as necessary, an adhesive tape 10 having the structure shown in Figure 1 or Figure 2 can be obtained.

[0123] <Self-back adhesive strength> The adhesive tape 10 of the present invention has a back treatment layer 1 made of SiO 4 / 2 The adhesive layer 3 contains a silica structure having units, and the adhesive layer 3 contains a tackifying resin having acid groups. Therefore, it exhibits high adhesive strength to its own back side, that is, the side of the substrate 2 opposite to the adhesive layer 3 (back treatment layer 1). As a result, the adhesive tape 10 exhibits excellent masking properties, especially in wet plating environments where plating solution does not penetrate from the overlapping parts, particularly during long-duration (e.g., 24 hours) plating processes.

[0124] The adhesive strength of the back surface can be expressed by the peel strength against the back surface (back surface treatment layer 1). In this invention, the adhesive strength of the back surface refers to the peel force measured at a peel angle of 180° and a peel speed of 300 mm / min when the adhesive tape 10 of the present invention is attached to a stainless steel plate by three adhesive layers on the back surface treatment layer 1 (back surface) of the base material 2 of the adhesive tape 10 of the present invention, with the three adhesive layers of the adhesive tape 10 overlapping each other. A detailed method for measuring the adhesive strength of the back surface will be described later.

[0125] The adhesive tape 10 of the present invention has a self-back adhesive strength of 3.1 N / 10 mm or more after immersion in a 5 wt% sulfuric acid aqueous solution (50°C) for 24 hours, from the viewpoint of sufficiently improving the penetration resistance to the plating solution during long-term plating treatment for overlapping portions. On the other hand, if the self-back adhesive strength is too high, there is a risk of adhesive residue being left on the adherend. Also, there is a risk that the resistance when pulling the adhesive tape 10 from the winding will become too large, resulting in poor workability, and that zipping will occur when pulling the adhesive tape 10 from the winding, causing wrinkles in the metal foil. The self-back adhesive strength of the adhesive tape 10 after immersion in the above 5 wt% sulfuric acid aqueous solution (50°C) for 24 hours is preferably 3.1 N / 10 mm or more and 10 N / 10 mm or less, and more preferably 3.4 N / 10 mm or more and 5.3 N / 10 mm or less. The adhesive strength of the back surface after immersion in the above 5 wt% sulfuric acid aqueous solution (50°C) for 24 hours cannot be stated definitively as it is related to the thickness of the adhesive tape 10 and the viscoelastic properties of the adhesive layer 3, but in the present invention, the SiO contained in the back surface treatment layer 1 4 / 2 It is effective to adjust this by controlling the amount of silica structure containing units and the amount of acid groups contained in the adhesive layer 3. Furthermore, the adhesive strength of the back surface before immersion in a 5 wt% sulfuric acid aqueous solution (50°C) (initial) is preferably 3.0 N / 10 mm or more, and the adhesive strength of the back surface after immersion in a 5 wt% sulfuric acid aqueous solution (50°C) for 3 hours is preferably 3.1 N / 10 mm or more. From the viewpoint of masking performance, the adhesive strength of the back surface after immersion in the above 5 wt% sulfuric acid aqueous solution (50°C) for 24 hours is preferably greater than the adhesive strength of the back surface before immersion (initial).

[0126] [Plating method using adhesive tape 10] An example of a plating method using the adhesive tape 10 of the present invention is described below. First, the adhesive layer 3 side of the adhesive tape 10, which has an adhesive layer 3 that has been cut by hand, is neatly attached to the surface of the material to be plated that is to be prevented from being plated, i.e., the surface of the non-plated part, and any unnecessary parts are trimmed with a utility knife or the like. After that, by performing a plating treatment, plating can be applied only to the part to be plated (hereinafter sometimes referred to as the "plated surface" or "surface to be plated").

[0127] The above-mentioned plating methods include wet plating methods such as electrolytic plating and electroless plating. Advantages of electrolytic plating include (1) low cost, (2) fast plating speed, (3) ability to apply thick plating, (4) ability to plate various metals and alloys, and (5) minimal thermal impact on the plated metal. Advantages of electroless plating include (1) no electricity is used, so plating is possible even if the object to be plated is not conductive, (2) uniform plating is possible on the surface because it is not affected by the flow of electricity, and (3) plating of complex shapes is possible. The appropriate plating method should be selected depending on the type of metal to be plated and the material of the plated surface.

[0128] For example, chromium plating is a plating method that forms a film of metallic chromium on the surface of the object to be treated. Currently, chromium plating baths used industrially have a highly acidic composition. For example, Sargent baths contain 250 g / l of chromic anhydride and 2.5 g / l of sulfuric acid. Also, siliceous fluoride baths contain 250 g / l of chromic anhydride, 0.5 to 1.5 g / l of sulfuric acid and 5 to 10 g / l of sodium siliceous fluoride. Chromium plating is usually carried out at a plating bath temperature of 40°C to 70°C for 10 minutes to several days.

[0129] The adhesive tape 10 exhibits excellent performance in terms of resistance to penetration of the plating solution and contamination of non-plated areas under plating treatment conditions where the plating solution contains a strong acid and the temperature is high. Therefore, when using the adhesive tape 10 as a masking tape, applying a chromium plating treatment method is preferable because it allows the performance of the adhesive tape 10 to be fully utilized.

[0130] When performing a plating treatment (for example, chromium plating) using the adhesive tape 10, specifically, a plating solution containing sulfuric acid at a concentration of 8 w / v% or less, preferably 6 w / v% or less, and more preferably 5 w / v% or less, can be used as the plating bath. In this case, the temperature of the plating bath can be set to 30°C or higher and 80°C or lower, preferably 40°C or higher and 70°C or lower, and more preferably 50°C or higher and 60°C or lower. The plating time can be set from 10 minutes to several days, preferably 1 hour or higher and 7 hours or lower, and more preferably 2 hours or higher and 4 hours or lower.

[0131] The conditions for the plating process in the above-described plating method can be those of a commonly used process. For example, first, as a pretreatment of the surface to be plated of the base material that has been finished, a cleaning process (washing process) is preferably performed. The washing process can be either a dry or wet process. Preferred dry processes include ashing, UV treatment, and reactive ion etching. Preferred wet processes include immersion and spin coating, and among these, the immersion method is more preferable because it allows for batch processing. Specific examples of wet processes include ultrasonic cleaning in water, immersion in an alkaline degreasing solution, immersion in an acidic degreasing solution, immersion in an aqueous surfactant solution, and immersion in a soft etching solution. Among these, from the viewpoint of simplicity, immersion in an acidic degreasing solution, immersion in an alkaline degreasing solution, and immersion in a soft etching solution are preferred as wet processes. In addition, if necessary, a finishing cleaning process by electrolytic cleaning or a base plating by strike plating may be performed.

[0132] After the cleaning step as a pretreatment as described above, the adhesive layer 3 of the adhesive tape 10 of the present invention is neatly applied to the surface of the material to be plated that is to be prevented from being plated, i.e., the surface of the unplated area, to mask it. Subsequently, an electrolytic plating method or an electroless plating method is appropriately selected depending on the type of metal to be plated and the material of the plated surface, and the material to be plated is immersed in the plating solution. The main plating treatment is then performed on the unmasked surface of the material to be plated according to the normal electrolytic plating or electroless plating treatment conditions. In the case of electroless plating, before immersion in the plating solution, a catalytic treatment is performed with a metal compound (e.g., a palladium compound) that has catalytic activity for depositing the metal.

[0133] Typical examples of plated metals include copper plating, zinc plating, chromium plating, nickel plating, and gold plating. Since nickel plating and gold plating can also be performed using electroless plating, this method can be used for nickel plating and gold plating on non-conductive materials or with complex patterns.

[0134] After the plating process described above, the plated material is washed with water, dried by methods such as blowing off the water or heating, then the adhesive tape 10 is removed and a finishing treatment is performed. The adhesive tape 10 may be removed before washing with water. For materials prone to hydrogen embrittlement, a baking treatment may be performed to remove hydrogen by heating to approximately 190°C to 220°C, for example. [Examples]

[0135] Next, the present invention will be described in more detail based on examples. However, the present invention is not limited to the following examples.

[0136] 1. Preparation of Reference Adhesive Tape 20 <Raw Material Resin> The resins shown in Table 1 below were prepared as raw materials for the reference adhesive tape 20.

[0137] [Table 1]

[0138] <Reference example 1> (Preparation of resin solution for intermediate layer 4) A resin solution for intermediate layer 4 was prepared by dissolving 10 parts by mass of an acid-modified polyolefin resin (resin for anchor coat layer, trade name: Unistol P902, acid value: 55 mg KOH / g) manufactured by Mitsui Chemicals, Inc. in 130 parts by mass of toluene.

[0139] (Preparation of adhesive solution for adhesive layer 3) 100 parts by mass of styrene-isoprene-styrene block copolymer (SIS-1, trade name: Quintac (trade name) 3520, styrene content: 15% by mass, SI diblock content: 78% by mass, polymer structure: linear structure) manufactured by Nippon Zeon Corporation, 40 parts by mass of tackifying resin (tackifying resin (1), trade name: Alcon P-115, softening point: 115℃, hydrogenated petroleum resin) manufactured by Arakawa Chemical Industries, Ltd., and tackifying resin (adhesive) manufactured by Nippon Zeon Corporation. After mixing 10 parts by mass of the additive resin (2), trade name: Quintone (trade name) D200, acid value: 17.0 mg KOH / g, softening point: 102℃, aliphatic (C5) / aromatic (C9) copolymer hydrocarbon resin, and 1.0 part by mass of an antioxidant manufactured by BASF Japan Ltd. (trade name: Irganox 1010, hindered phenol antioxidant), the mixture was diluted with toluene to a non-volatile content of 50% by mass, and stirred at room temperature for 48 hours or more to obtain an adhesive solution.

[0140] (Preparation of reference adhesive tape 20) First, as the base material 2, a soft aluminum foil (80 μm thick) conforming to JIS H 4160 was prepared. Next, the resin solution for the intermediate layer 4 prepared above was applied to the soft aluminum foil using a bar coater, with a coating amount of 0.12 g / m² after drying. 2The adhesive solution was applied in this manner and dried at 110°C for 2 minutes to form the intermediate layer 4. Subsequently, the adhesive solution prepared above was applied using a comma coater onto the intermediate layer 4 formed on the soft aluminum foil, so that the dry thickness of the adhesive layer 3 was 30 μm, and dried at 110°C for 3 minutes to form the adhesive layer 3, thereby producing the reference adhesive tape 20.

[0141] <Reference example 2> In preparing the adhesive solution for Reference Adhesive Tape 20, Reference Adhesive Tape 20 was prepared in the same manner as Reference Example 1, except that the amount of tackifying resin (tackifying resin (2), trade name: Quintone (trade name) D200, acid value: 17.0 mg KOH / g, softening point: 102°C, aliphatic (C5) / aromatic (C9) copolymer hydrocarbon resin) manufactured by Nippon Zeon Co., Ltd. was changed to 5 parts by mass.

[0142] <Reference example 3> In preparing the adhesive solution for Reference Adhesive Tape 20, Reference Adhesive Tape 20 was prepared in the same manner as Reference Example 1, except that the amount of tackifying resin (tackifying resin (2), trade name: Quintone (trade name) D200, acid value: 17.0 mg KOH / g, softening point: 102°C, aliphatic (C5) / aromatic (C9) copolymer hydrocarbon resin) manufactured by Nippon Zeon Co., Ltd. was changed to 20 parts by mass.

[0143] <Reference example 4> In preparing the adhesive solution for Reference Adhesive Tape 20, Reference Adhesive Tape 20 was prepared in the same manner as Reference Example 1, except that the amount of tackifying resin (tackifying resin (2), trade name: Quintone (trade name) D200, acid value: 17.0 mg KOH / g, softening point: 102°C, aliphatic (C5) / aromatic (C9) copolymer hydrocarbon resin) manufactured by Nippon Zeon Co., Ltd. was changed to 30 parts by mass.

[0144] <Reference example 5> In preparing the adhesive solution for Reference Adhesive Tape 20, Reference Adhesive Tape 20 was prepared in the same manner as Reference Example 1, except that the amount of tackifying resin (tackifying resin (1), product name: Alcon P-115, softening point: 115°C, hydrogenated petroleum resin) manufactured by Arakawa Chemical Industries, Ltd. was changed to 30 parts by mass.

[0145] <Reference example 6> In preparing the adhesive solution for Reference Adhesive Tape 20, Reference Adhesive Tape 20 was prepared in the same manner as Reference Example 1, except that the amount of tackifying resin (tackifying resin (1), product name: Alcon P-115, softening point: 115°C, hydrogenated petroleum resin) manufactured by Arakawa Chemical Industries, Ltd. was changed to 60 parts by mass.

[0146] <Reference example 7> In preparing the adhesive solution for Reference Adhesive Tape 20, Reference Adhesive Tape 20 was prepared in the same manner as Reference Example 2, except that the amount of tackifying resin (tackifying resin (1), product name: Alcon P-115, softening point: 115°C, hydrogenated petroleum resin) manufactured by Arakawa Chemical Industries, Ltd. was changed to 20 parts by mass.

[0147] <Reference example 8> In preparing the adhesive solution for Reference Adhesive Tape 20, Reference Adhesive Tape 20 was prepared in the same manner as Reference Example 7, except that the amount of tackifying resin (tackifying resin (2), trade name: Quintone (trade name) D200, acid value: 17.0 mg KOH / g, softening point: 102°C, aliphatic (C5) / aromatic (C9) copolymer hydrocarbon resin) manufactured by Nippon Zeon Co., Ltd. was changed to 20 parts by mass.

[0148] <Reference example 9> Reference adhesive tape 20 was prepared in the same manner as in Reference Example 3, except that in the preparation of the adhesive solution for Reference Adhesive Tape 20, 100 parts by mass of styrene-soprene-styrene block copolymer (SIS-2, product name: Quintac (product name) 3433N, styrene content: 16% by mass, SI diblock content: 56% by mass, polymer structure: linear structure) manufactured by Nippon Zeon Co., Ltd. was used instead of 100 parts by mass of styrene-soprene-styrene block copolymer (SIS-1, product name: Quintac (product name) 3520, styrene content: 15% by mass, SI diblock content: 78% by mass, polymer structure: linear structure) manufactured by Nippon Zeon Co., Ltd.

[0149] <Reference example 10> In preparing the adhesive solution for Reference Adhesive Tape 20, Reference Adhesive Tape 20 was prepared in the same manner as Reference Example 9, except that the amount of tackifying resin (tackifying resin (2), trade name: Quintone (trade name) D200, acid value: 17.0 mg KOH / g, softening point: 102°C, aliphatic (C5) / aromatic (C9) copolymer hydrocarbon resin) manufactured by Nippon Zeon Co., Ltd. was changed to 60 parts by mass.

[0150] <Reference example 11> Reference adhesive tape 20 was prepared in the same manner as in Reference Example 3, except that in the preparation of the adhesive solution for Reference Adhesive Tape 20, 100 parts by mass of styrene-isoprene-styrene block copolymer (SIS-3, product name: SIS5506, styrene content: 16% by mass, SI diblock content: 55% by mass, polymer structure: linear structure) manufactured by JSR Corporation was used instead of 100 parts by mass of styrene-isoprene-styrene block copolymer (SIS-1, product name: Quintac (product name) 3520, styrene content: 15% by mass, SI diblock content: 78% by mass, polymer structure: linear structure) manufactured by Nippon Zeon Co., Ltd.

[0151] <Reference example 12> The reference adhesive tape 20 was prepared in the same manner as in Reference Example 9, except that an intermediate layer 4 was not formed on the base material 2, which is soft aluminum foil (thickness 80 μm), the amount of tackifying resin (tackifying resin (2), trade name: Quintone (trade name) D200, acid value: 17.0 mg KOH / g, softening point: 102℃, aliphatic (C5) / aromatic (C9) copolymer hydrocarbon resin) manufactured by Nippon Zeon Co., Ltd. was changed to 10 parts by mass in the preparation of the adhesive solution for the reference adhesive tape 20, and the thickness of the adhesive layer 3 was changed to 50 μm.

[0152] <Reference example 13> In preparing the adhesive solution for Reference Adhesive Tape 20, the amount of tackifying resin (tackifying resin (1), trade name: Alcon P-115, softening point: 115℃, hydrogenated petroleum resin) manufactured by Arakawa Chemical Industries, Ltd. was changed to 30 parts by mass, and 40 parts by mass of tackifying resin (tackifying resin (3), trade name: Quintone (trade name) CX495, acid value: 1.8 mg KOH / g, softening point: 96℃, aliphatic (C5) hydrocarbon resin) manufactured by Nippon Zeon Co., Ltd. was used instead of 10 parts by mass of tackifying resin (tackifying resin (2), trade name: Quintone (trade name) D200, acid value: 17.0 mg KOH / g, softening point: 102℃, aliphatic (C5) / aromatic (C9) copolymer hydrocarbon resin) manufactured by Nippon Zeon Co., Ltd. was used.

[0153] <Reference example 14> In preparing the adhesive solution for Reference Adhesive Tape 20, Reference Adhesive Tape 20 was prepared in the same manner as Reference Example 13, except that the tackifying resin (1), trade name: Alcon P-115, softening point: 115°C, hydrogenated petroleum resin manufactured by Arakawa Chemical Industries, Ltd. was not used, and the amount of tackifying resin (3), trade name: Quintone CX495, acid value: 1.8 mg KOH / g, softening point: 96°C, aliphatic (C5) hydrocarbon resin manufactured by Nippon Zeon Corporation was changed to 30 parts by mass.

[0154] <Reference Example 1> Reference adhesive tape 20 was prepared in the same manner as in Reference Example 1, except that a tackifying resin (tackifying resin (2), trade name: Quintone (trade name) D200, acid value: 17.0 mg KOH / g, softening point: 102°C, aliphatic (C5) / aromatic (C9) copolymer hydrocarbon resin) manufactured by Nippon Zeon Co., Ltd. was not used in the preparation of the adhesive solution for Reference Adhesive Tape 20.

[0155] <Reference Comparison Example 2> Reference adhesive tape 20 was prepared in the same manner as in Reference Example 9, except that a tackifying resin (tackifying resin (2), trade name: Quintone (trade name) D200, acid value: 17.0 mg KOH / g, softening point: 102°C, aliphatic (C5) / aromatic (C9) copolymer hydrocarbon resin) manufactured by Nippon Zeon Co., Ltd. was not used in the preparation of the adhesive solution for Reference Adhesive Tape 20.

[0156] <Reference Comparison Example 3> Reference adhesive tape 20 was prepared in the same manner as in Reference Example 1, except that in the preparation of the adhesive solution for Reference Adhesive Tape 20, 100 parts by mass of styrene-isoprene-styrene block copolymer (SIS-1, trade name: Quintac (trade name) 3520, styrene content: 15% by mass, SI diblock content: 78% by mass, polymer structure: linear structure) manufactured by Nippon Zeon Co., Ltd. was replaced with 100 parts by mass of styrene-isoprene-styrene block copolymer (SIS-4, trade name: Quintac (trade name) 3450, styrene content: 19% by mass, SI diblock content: 30% by mass, polymer structure: radial structure) manufactured by Nippon Zeon Co., Ltd.

[0157] <Reference Comparative Example 4> Reference adhesive tape 20 was prepared in the same manner as in Reference Comparative Example 3, except that in the preparation of the adhesive solution for Reference Adhesive Tape 20, 100 parts by mass of styrene-isoprene-styrene block copolymer (SIS-4, trade name: Quintac (trade name) 3450, styrene content: 19% by mass, SI diblock content: 30% by mass, polymer structure: radial structure) manufactured by Nippon Zeon Co., Ltd. was replaced with 100 parts by mass of styrene-isoprene-styrene block copolymer (SIS-5, trade name: KRATON (trade name) D1161, styrene content: 15% by mass, SI diblock content: 19% by mass, polymer structure: linear structure) manufactured by Kraton Polymers International.

[0158] <Reference Example 5> In preparing the adhesive solution for Reference Adhesive Tape 20, Reference Adhesive Tape 20 was prepared in the same manner as Reference Example 1, except that the amount of tackifying resin (tackifying resin (2), trade name: Quintone (trade name) D200, acid value: 17.0 mg KOH / g, softening point: 102°C, aliphatic (C5) / aromatic (C9) copolymer hydrocarbon resin) manufactured by Nippon Zeon Co., Ltd. was changed to 2 parts by mass.

[0159] <Reference Comparison 6> In preparing the adhesive solution for Reference Adhesive Tape 20, Reference Adhesive Tape 20 was prepared in the same manner as Reference Example 9, except that the amount of tackifying resin (1), product name: Alcon P-115, softening point: 115°C, hydrogenated petroleum resin, manufactured by Arakawa Chemical Industries, Ltd. was changed to 30 parts by mass, and the amount of tackifying resin (2), product name: Quintone D200, acid value: 17.0 mg KOH / g, softening point: 102°C, aliphatic (C5) / aromatic (C9) copolymer hydrocarbon resin, manufactured by Nippon Zeon Corporation was changed to 70 parts by mass.

[0160] 2. Evaluation Method Next, we will explain the characteristics of the reference adhesive tape 20, the evaluation method for acidic aqueous solution penetration (liquid immersion) and adhesive residue in the acidic aqueous solution immersion test, and the evaluation method for the plating.

[0161] <Adhesive Tape Characteristics> (1) Reference thickness of adhesive tape 20 The thickness of the reference adhesive tapes 20 prepared in Reference Examples 1-14 and Reference Comparative Examples 1-6 was measured using a dial gauge in accordance with JIS Z 0237 (2009).

[0162] (2) Adhesion to the material to be plated (stainless steel plate (SUS304 plate, #360 polished finish)) Under a temperature of 23°C, the reference adhesive tapes 20 prepared in Reference Examples 1-14 and Reference Comparative Examples 1-6 were subjected to adhesion strength tests (180° peel adhesion strength tests) on the plating target material (stainless steel plate (SUS304 plate, #360 polished finish)) in accordance with the method described in JIS Z 0237 (2009), and the 180° peel adhesion strength was measured.

[0163] Specifically, first, the reference adhesive tape 20 was attached to the material to be plated (stainless steel plate (SUS304 plate, #360 polished finish)), and a 2000g roller was passed back and forth once at a speed of 5mm / second to press it down. Next, the sample with the reference adhesive tape 20 attached to the material to be plated (stainless steel plate (SUS304 plate, #360 polished finish)) was left to stand and stored for 96 hours in a constant temperature chamber adjusted to a temperature and humidity environment of 50°C and 90%RH. After 96 hours of storage, the sample was removed and left to stand for 30 minutes in an environment of 23°C and 50%RH. Then, the adhesive strength was measured using a tensile testing machine when the tape was peeled off from the material to be plated (stainless steel plate (SUS304 plate, #360 polished finish)) at a speed of 5mm / second in a 180° direction.

[0164] (3) Adhesion between the substrate and the adhesive layer Under a temperature of 23°C, the adhesion strength between the substrate and the adhesive layer was measured for the reference adhesive tapes 20 prepared in Reference Examples 1-14 and Reference Comparative Examples 1-6.

[0165] Specifically, first, the adhesive layer side of a rubber-based adhesive tape (model number: No. 6200 / film tape) made of a PET substrate manufactured by Maxell Corporation was attached to the surface of the adhesive layer 3 of the reference adhesive tape 20, and pressure was applied by moving a 2000g roller back and forth at a speed of 5mm / second once. Subsequently, after being left to stand and cure for 30 minutes in an environment of 23°C and 50%RH, the reference adhesive tape 20 was peeled off at a speed of 5mm / second in a 180° direction using a tensile testing machine, and the adhesion force at the interface between the substrate 2 and the adhesive layer 3 was measured. In the case where peeling occurred at the interface between the adhesive layer 3 of the reference adhesive tape 20 and the adhesive layer of the film tape (No. 6200), the adhesion force was considered to be greater than or equal to the measured value.

[0166] (4) Tearability of adhesive tape by hand (adhesive breakage) Under a temperature of 23°C, the tearability of the reference adhesive tapes 20 prepared in Reference Examples 1-14 and Reference Comparative Examples 1-6 was evaluated.

[0167] The evaluation criteria were as follows, with a rating of B or higher considered a passing grade. A: When cut by hand, the adhesive layer hardly stretched and cut cleanly together with the substrate, and no peeling of the adhesive layer from the substrate was observed at the cut area. B: When cut by hand, the adhesive layer stretched slightly, but it could be cut relatively well together with the substrate, and almost no peeling of the adhesive from the substrate was observed at the cut area. C: When cut by hand, the adhesive layer stretched significantly, and it was possible to cut it together with the substrate, but peeling of the adhesive layer from the substrate was observed at the cut point.

[0168] <Acidic aqueous solution immersion test> (1) Resistance to penetration of acidic aqueous solutions (liquid immersion) The resistance of the reference adhesive tapes 20 prepared in Reference Examples 1-14 and Reference Comparative Examples 1-6 to acidic aqueous solutions was evaluated. Specifically, first, samples similar to those used in the adhesive strength tests above were prepared for each sample. Next, two types of 60°C sulfuric acid aqueous solutions with different sulfuric acid concentrations were prepared ((1) sulfuric acid concentration: 2% by mass [0.41N], (2) sulfuric acid concentration: 5% by mass [1.02N]). Subsequently, each sample was immersed in the respective acidic aqueous solution for 3 hours, then removed from the acidic aqueous solution and washed with water. Then, the reference adhesive tape 20 was peeled off the stainless steel plate (SUS304·BA plate), and the gloss condition of the surface of the stainless steel plate (SUS304·BA plate) that had been masked by the reference adhesive tape 20 was visually observed to evaluate the penetration (liquid penetration) of the acidic aqueous solution.

[0169] The evaluation criteria were as follows, with a rating of B or higher considered a passing grade. A: No infiltration of acidic aqueous solution was observed. B: Slight penetration of the acidic aqueous solution was observed at the edges. C: Significant penetration of acidic aqueous solution was observed.

[0170] (2) Adhesive residue after removing adhesive tape For each of the reference adhesive tapes 20 in Reference Examples 1-14 and Reference Comparative Examples 1-6, when the reference adhesive tape 20 was re-peeled off to evaluate the penetration state of the acidic aqueous solution, the state of adhesive residue on the surface of the stainless steel plate (SUS304 BA plate: adherend) that had been masked by the reference adhesive tape 20 was simultaneously observed visually and evaluated.

[0171] The evaluation criteria were as follows, with a rating of B or higher considered a passing grade. A: No adhesive residue was found on the adherend. B: A small amount of adhesive residue was observed at the edges of the adherend. C: Significant adhesive residue was observed on the adherend.

[0172] <Plating Evaluation> (1) Clarity (clearness) of the plated lines For the reference adhesive tapes 20 prepared in Reference Examples 1, 7, 10, 13 and Reference Comparative Example 1, the reference adhesive tapes 20 were used as masking tapes for plating, and chromium plating was performed by electrolytic plating. The clarity of the plating lines after plating (clearance of the plating masking) was then evaluated. Specifically, each reference adhesive tape 20, 25 mm wide and 100 mm long, was attached to the side of a cylindrical stainless steel (SUS304) member, approximately 50 mm in diameter and 70 mm in height, whose surface had been degreased with thinner. The tape was then firmly pressed down by hand using a spatula. A standard Sargent bath (chromic anhydride:sulfuric acid = 100:1 [mass ratio]) was used as the chromium plating bath. Before chromium plating, in order to improve adhesion in chromium plating, the stainless steel cylindrical member to which the reference adhesive tape 20 was attached was connected to the anode side in a separate bath of sulfuric acid solution and subjected to reverse electrolysis by applying an electric current. After reverse electrolysis, the stainless steel cylindrical member to which the reference adhesive tape 20 was attached was immersed in the chromium plating bath, heated to 50°C, and left immersed for 3 hours. Subsequently, the cathode current density was 40 A / dm². 2 Then, chromium plating was performed for 1 minute to form a chromium plating film with a thickness of 0.4 μm on the plated surface. Next, the chromium plating solution was thoroughly washed with tap water, and the reference adhesive tape 20 was peeled off again. The clarity of the plating line was then visually observed and evaluated.

[0173] The evaluation criteria were as follows, with a rating of B or higher considered a passing grade. A: The plating lines were clear. B: Slight areas where the plating lines were unclear were observed. C: The plating lines were generally indistinct.

[0174] (2) Adhesive residue after removing adhesive tape For the reference adhesive tapes 20 prepared in Reference Examples 1, 7, 10, 13 and Reference Comparative Example 1, when the reference adhesive tapes 20 were re-peeled off to evaluate the clarity of the plating lines, the condition of the adhesive residue on the surface of the unplated portion of the stainless steel cylindrical member that had been masked by the reference adhesive tapes 20 was simultaneously observed visually and evaluated.

[0175] The evaluation criteria were as follows, with a rating of B or higher considered a passing grade. A: No adhesive residue was found on the adherend. B: A small amount of adhesive residue was observed at the edges of the adherend. C: Significant adhesive residue was observed on the adherend.

[0176] 3. Evaluation Results The evaluation results for Reference Examples 1-14 are shown in Tables 2-5, and the evaluation results for Reference Adhesive Tape 20 of Reference Comparison Examples 1-6 are shown in Tables 6 and 7.

[0177] [Table 2]

[0178] [Table 3]

[0179] [Table 4]

[0180] [Table 5]

[0181] [Table 6]

[0182] [Table 7]

[0183] As shown in Tables 2-5, when the adhesive tapes of Reference Examples 1-14, in which the adhesive layer 3 satisfies the requirements of the present invention, were applied, good results were obtained in both the acidic aqueous solution penetration resistance (liquid penetration) and adhesive residue evaluation items in the acidic aqueous solution immersion test. Furthermore, when the adhesive tapes of Reference Examples 1, 7, 10, and 13 were applied to actual chromium plating processes, good results were obtained in all evaluation items (clearness and adhesive residue) of the plating evaluation. In other words, the adhesive tapes of Reference Examples 1-14, in which the adhesive layer 3 satisfies the requirements of the present invention, were found to have excellent resistance to plating solution penetration, good peelability after plating, and excellent stain resistance of non-plated areas, possessing excellent properties as plating masking tapes. In addition, good results were obtained in the evaluation of adhesive tearing, indicating that these adhesive tapes also have excellent tearability by hand.

[0184] Among these reference examples, the adhesive tapes of Reference Examples 1 to 6, in which the styrene-isoprene-styrene block copolymer contains styrene-isoprene blocks in the range of 50% to 80% by mass, the tackifier having an acid group is an aliphatic (C5) / aromatic (C9) copolymer hydrocarbon resin, the total amount of tackifier added is in the range of 40 parts by mass to 70 parts by mass, and the acid value of the adhesive layer is in the range of 0.6 mg KOH / g to 3.0 mg KOH / g, received an A rating in all evaluations of acidic aqueous solution penetration resistance (liquid submersion), adhesive residue, and adhesive breakage in the acidic aqueous solution immersion test, confirming that they are superior to the adhesive tapes of the other reference examples.

[0185] In contrast, as shown in Tables 6 and 7, when the adhesive tapes of Reference Comparative Examples 1 to 6, in which the adhesive layer 3 does not satisfy the requirements of the present invention, were applied, it was confirmed that at least one evaluation item in the acidic aqueous solution immersion test—resistance to penetration of acidic aqueous solution (liquid submersion), adhesive residue, and adhesive breakage—was inferior compared to the adhesive tapes of Reference Examples 1 to 14. Furthermore, when the adhesive tape of Reference Comparative Example 1 was applied to an actual chrome plating process, it was confirmed that the clarity (clearance) in the plating evaluation items was inferior compared to the adhesive tapes of Reference Examples 1, 7, 10, and 13.

[0186] Specifically, the adhesive tape of Reference Comparative Example 1, which does not contain an acid-modified tackifying resin as a tackifying resin and whose adhesive composition constituting the adhesive layer 3 has an acid value of 0, showed poor adhesion to SUS 180° peel after being attached to a SUS304 plate and stored for 96 hours in a constant temperature bath adjusted to a temperature and humidity environment of 50°C and 90%RH. In particular, in the evaluation of acidic aqueous solution penetration resistance (liquid dive) in an acidic aqueous solution immersion test in a 5% sulfuric acid aqueous solution at 60°C for 3 hours, it was confirmed that it was inferior to the adhesive tapes of Reference Examples 1 to 8, which used the same styrene-isoprene-styrene block copolymer as Reference Comparative Example 1 and whose acid value was in the range of 0.3 mg KOH / g to 5.5 mg KOH / g of the present invention.

[0187] Similarly, the adhesive tape of Reference Comparative Example 2, which does not contain an acid-modified tackifying resin as a tackifying resin and whose adhesive composition constituting the adhesive layer 3 has an acid value of 0, also showed poor adhesion to SUS180° after being attached to a SUS304 plate and stored for 96 hours in a constant temperature bath adjusted to a temperature and humidity environment of 50°C and 90%RH. In particular, in the evaluation of acidic aqueous solution penetration resistance (liquid dive) in an acidic aqueous solution immersion test in a 5% sulfuric acid aqueous solution at 60°C for 3 hours, it was confirmed that it was inferior to the adhesive tapes of Reference Examples 9, 10, and 12-14, which used the same styrene-isoprene-styrene block copolymer as Reference Comparative Example 2 and whose acid value was in the range of 0.3 mg KOH / g to 5.5 mg KOH / g of the present invention.

[0188] Furthermore, although the acid value of the adhesive composition constituting the adhesive layer 3 satisfies the range of the present invention, the adhesive tapes of Reference Comparative Examples 3 and 4, in which the amount of styrene-isoprene-styrene block copolymer was below the lower limit of 50% by mass of the present invention, had a large cohesive force of adhesive layer 3. In the evaluation of the tearability (adhesive tearability) of the adhesive tapes, it was confirmed that they were inferior to the adhesive tapes of Reference Examples 1 to 14, in which the amount of styrene-isoprene-styrene block copolymer was in the range of 50% by mass or more and 80% by mass or less of the present invention.

[0189] Furthermore, although the amount of styrene-isoprene-styrene block copolymer satisfies the scope of the present invention, the adhesive tapes of Reference Comparative Example 5, in which the acid value of the adhesive composition constituting the adhesive layer 3 is below the lower limit of the present invention of 0.3 mg KOH / g, and Reference Comparative Example 6, in which the acid value exceeds the upper limit of the present invention of 5.5 mg KOH / g, showed low adhesive strength to SUS180° peel after being attached to a SUS304 plate and stored for 96 hours in a constant temperature bath adjusted to a temperature and humidity environment of 50°C and 90% RH. In particular, in the evaluation of acidic aqueous solution penetration resistance (liquid dive) in an acidic aqueous solution immersion test in an acidic aqueous solution aqueous solution at 60°C for 3 hours, it was confirmed that they were inferior to the adhesive tapes of Reference Examples 1 to 14, in which the acid value is in the range of 0.3 mg KOH / g to 5.5 mg KOH / g of the present invention.

[0190] 4. Preparation of adhesive tape 10 <Raw Material Resin> The materials shown in Table 8 below were prepared to form the back treatment layer 1 of the adhesive tape 10.

[0191] [Table 8]

[0192] <Example 1> A solution of an addition-reactive silicone resin composition with a non-volatile content of 0.48% by mass was prepared by mixing 100 parts by mass of silicone resin composition A (non-volatile content) and 5 parts by mass of release control agent A (non-volatile content), adding 0.6 parts by mass of platinum group metal curing catalyst (an amount such that the amount of platinum metal is 410 ppm relative to silicone resin A) and a toluene / rubber volatile oil SK9 = 1 / 1 mixed solvent as a diluent, and further mixing uniformly.

[0193] As base material 2, a flexible aluminum foil (80 μm thick) conforming to JIS H 4160 was prepared. Next, a solution of the prepared addition-reactive silicone resin composition was applied to one side of the flexible aluminum foil using a bar coater, dried at 120°C for 3 minutes, and then heated and cured to form back treatment layer 1. The adhesion amount (Dry) of back treatment layer 1 was 0.086 g / m². 2 That was the case.

[0194] Next, an adhesive tape 10 was fabricated by forming an intermediate layer 4 and an adhesive layer 3 on the other side of the base material 2 in the same manner as in Reference Example 1.

[0195] <Examples 2-5, Comparative Examples 1-4> Adhesive tape 10 was manufactured in the same manner as in Example 1, except that the materials and mixing ratios shown in Tables 9 to 11 were used in the manufacturing of the back treatment layer 1.

[0196] <Comparative Example 5> A solution of non-silicone resin with a solid content of 0.4% by mass was prepared by uniformly mixing 100 parts by mass of non-silicone resin and 24,900 parts by mass of toluene.

[0197] As base material 2, a flexible aluminum foil (80 μm thick) conforming to JIS H 4160 was prepared. Next, the prepared non-silicone resin solution was applied to one side of the flexible aluminum foil using a bar coater, and heated and dried at 120°C for 3 minutes to form back treatment layer 1. The adhesion amount (Dry) of back treatment layer 1 was 0.018 g / m². 2 That was the case.

[0198] Next, an adhesive tape 10 was fabricated by forming an intermediate layer 4 and an adhesive layer 3 on the other side of the base material 2 in the same manner as in Reference Example 1.

[0199] <Comparative Example 6> The adhesive tape 10 was prepared in the same manner as in Example 5, except that the intermediate layer 4 and the adhesive layer 3 were formed in the same manner as in Reference Comparative Example 1.

[0200] 5. Evaluation Method (1) Self-back adhesive strength The self-back adhesive strength of the adhesive tapes 10 prepared in Examples 1-5 and Comparative Examples 1-6 was evaluated. Specifically, first, the adhesive layer 3 surface of the adhesive tape 10 of the present invention (25 mm wide x 110 mm long) was attached to the material to be plated (stainless steel plate (SUS304 plate, #360 polished finish)) while pressing it down with a spatula. Furthermore, the adhesive layer 3 surface of the adhesive tape 10 of the present invention (25 mm wide x 110 mm long) was neatly attached on top of the back treatment layer 1 (self-back) of the above adhesive tape 10 while pressing it down with a spatula to prevent shifting in the width direction. Then, a roller with a mass of 2000 g was passed back and forth once at a speed of 5 mm / second over the two adhesive tapes 10 that had been attached together with a spatula to press them down and prepare an overlapping mask steel plate for measuring the self-back adhesive strength. This was used as a test piece for measuring the self-back adhesive strength after immersion in an acidic aqueous solution for 0 hours (initial).

[0201] Next, a 5% by mass [1.02N] sulfuric acid aqueous solution was prepared at 50°C. The overlapping mask steel plates prepared above were immersed in the acidic aqueous solution for 3 hours, then removed from the acidic aqueous solution and washed with water. These were then used as test pieces for measuring the self-back adhesive strength after 3 hours of immersion in the acidic aqueous solution.

[0202] Similarly, the overlapping mask steel plates were immersed in the above acidic aqueous solution for 24 hours, then removed from the acidic solution and washed with water. These were then used as test pieces for measuring the adhesive strength of the back surface after 24 hours of immersion in the acidic aqueous solution.

[0203] For each of the test specimens prepared as described above ((1) immersion in acidic aqueous solution for 0 hours, (2) immersion in acidic aqueous solution for 3 hours, (3) immersion in acidic aqueous solution for 24 hours), after being left to stand and cure for 30 minutes in an environment of 23°C and 50% RH, the 25 mm wide adhesive tape 10 that was later applied on top was peeled off at a speed of 300 mm / min in the 180° direction using a tensile testing machine, and the adhesion force at the interface between the back treatment layer 1 and the adhesive layer 3 was measured and defined as the back adhesive force (unit: converted to N / 10 mm).

[0204] (2) Resistance to penetration of acidic aqueous solutions (liquid immersion) The resistance of the adhesive tapes 10 prepared in Examples 1-5 and Comparative Examples 1-6 to penetration of acidic aqueous solutions was evaluated. Specifically, first, two pieces of the adhesive tape 10 of the present invention (width 25 mm x length 100 mm) were prepared. As shown in Figure 6, the first piece of adhesive tape 10 was first pressed onto a stainless steel plate using a spatula, and then pressed down by passing a 2000 g roller back and forth once at a speed of 5 mm / second. Next, the second piece of adhesive tape 10 was pressed onto the right end of the first piece of adhesive tape using a spatula, as shown in Figure 6, so that an overlapping portion 8b (width approximately 10 mm) was formed. Then, pressed down by passing a 2000 g roller back and forth once at a speed of 5 mm / second, and test pieces for liquid penetration evaluation were prepared. Next, a sulfuric acid aqueous solution at 60°C (sulfuric acid concentration: 5% by mass [1.02 N]) was prepared as the acidic aqueous solution. Next, each sample was immersed in the sulfuric acid solution for the specified time ((1) 3 hours, (2) 24 hours), then removed from the sulfuric acid solution and washed with water. The immersion was such that approximately 3 / 5 of the length of the adhesive tape 10 was submerged in the sulfuric acid solution. The two adhesive tapes 10 were then peeled off the stainless steel plate (SUS304-BA plate), and the gloss and other characteristics of the surface of the stainless steel plate (SUS304-BA plate) that had been masked by the adhesive tape 10 of the present invention were visually compared and observed to evaluate the penetration state (liquid penetration) of the acidic solution.

[0205] The evaluation criteria were as follows, with a rating of B or higher considered a passing grade. A: No infiltration of acidic aqueous solution was observed. B: Slight penetration of the acidic aqueous solution was observed near the edges or overlapping sections. C: Significant penetration of the acidic aqueous solution was observed near the edges or overlapping sections.

[0206] (3) Adhesive residue after removing adhesive tape For each adhesive tape 10 in Examples 1-5 and Comparative Examples 1-6, when the adhesive tape 10 was re-peeled off to evaluate the penetration state of the acidic aqueous solution, the state of adhesive residue on the surface of the stainless steel plate (SUS304 BA plate: adherend) that had been masked by the adhesive tape 10 was simultaneously observed visually and evaluated.

[0207] The evaluation criteria were as follows, with a rating of B or higher considered a passing grade. A: No adhesive residue was found on the adherend. B: A small amount of adhesive residue was observed on the substrate, particularly at the edges or near the overlapping sections. C: Significant adhesive residue was observed on the adherend.

[0208] 6. Evaluation Results The evaluation results for Examples 1-5 are shown in Tables 9 and 10, and the evaluation results for Comparative Examples 1-6 are shown in Tables 10 and 11.

[0209] [Table 9]

[0210] [Table 10]

[0211] [Table 11]

[0212] As shown in Tables 9 and 10, the adhesive tapes of Examples 1 to 5 that satisfy the requirements of the present invention had a self-back adhesive strength of 3.4 N / 10 mm or more after immersion in a 5 wt% sulfuric acid aqueous solution (50°C) for 24 hours. Furthermore, when the adhesive tapes were peeled off after being immersed in a 5 wt% sulfuric acid aqueous solution (60°C) for 24 hours with the tapes overlapping, no traces of liquid penetration (evidence of sulfuric acid solution intrusion) were observed, and no adhesive residue was found, confirming that they possessed excellent masking performance.

[0213] In addition, the back treatment layer is SiO 4 / 2 The adhesive tapes of Examples 1, 3, and 4, which contained a release control agent in addition to a silica structure with units, tended to have increased self-adhesion compared to the adhesive tape of Example 5, which did not contain a release control agent.

[0214] Although not shown in the table, for the adhesive tapes of Examples 2 and 5, when the stainless steel cylindrical members to which the adhesive tape was attached were immersed in a chromium plating bath, heated to 50°C, and immersed for 24 hours to perform the plating treatment, it was confirmed that the clarity of the plating line was good and no adhesive residue was generated. Furthermore, when the adhesive tape of Example 1 was immersed in a 5 wt% sulfuric acid aqueous solution (50°C) for 48 hours, the self-back adhesive strength was measured to be 3.4 N / 10 mm, which was found to be not significantly different from the value after 24 hours of immersion.

[0215] In contrast, as shown in Tables 10 and 11, the adhesive tapes of Comparative Examples 1 to 6, which do not satisfy any of the requirements of the present invention, had a self-back adhesive strength of less than 3.1 N / 10 mm after immersion in a 5 wt% sulfuric acid aqueous solution (50°C) for 24 hours (except for Comparative Example 5). When the adhesive tapes were peeled off after being immersed in a 5 wt% sulfuric acid aqueous solution (60°C) for 24 hours with the tapes overlapping, traces of liquid penetration (evidence of sulfuric acid solution intrusion) were observed, confirming that their masking performance was clearly inferior compared to the adhesive tapes of Examples 1 to 5.

[0216] In detail, the adhesive tape of Comparative Example 1 has an adhesive layer containing a styrene-isoprene-styrene block copolymer and a tackifying resin having acid groups, but the silicone resin C used in the back treatment layer is SiO 4 / 2 Because it does not contain silica structures with units, the adhesive strength on the back of the tape after immersion in a 5wt% sulfuric acid aqueous solution (50°C) for 24 hours was less than 3.1 N / 10 mm, and when the adhesive tape was peeled off after being immersed in a 5wt% sulfuric acid aqueous solution (60°C) for 24 hours with the tapes overlapping, traces of liquid penetration (evidence of sulfuric acid solution intrusion) were observed. However, the adhesive strength on the back of the tape after immersion in a 5wt% sulfuric acid aqueous solution (50°C) for 3 hours was 3.1 N / 10 mm, and when the adhesive tape was peeled off after being immersed in a 5wt% sulfuric acid aqueous solution (60°C) for 3 hours with the tapes overlapping, no traces of liquid penetration (evidence of sulfuric acid solution intrusion) were observed.

[0217] In addition, although the adhesive tapes of Comparative Examples 2 to 4 contain a styrene-isoprene-styrene block copolymer and a tackifier resin having an acid group in the adhesive layer, the silicone resin B used for the back surface treatment layer does not contain a silica structure having SiO 4 / 2 units. Therefore, the self-back adhesion after immersion in a 5 wt% sulfuric acid aqueous solution (50 °C) for 24 hours is less than 3.1 N / 10 mm. When the adhesive tape was immersed in a 5 wt% sulfuric acid aqueous solution (60 °C) for 24 hours in a state where the adhesive tapes were laminated and then the adhesive tape was peeled off, traces of liquid immersion (traces of penetration of the sulfuric acid solution) were observed. Incidentally, the self-back adhesion and the traces of liquid immersion (traces of penetration of the sulfuric acid solution) after immersion in a 5 wt% sulfuric acid aqueous solution (50 °C) for 3 hours were also not satisfactory.

[0218] Furthermore, although the adhesive tape of Comparative Example 5 contains a styrene-isoprene-styrene block copolymer and a tackifier resin having an acid group in the adhesive layer, an uncured non-silicone resin was used instead of the addition-reactive silicone resin composition for the back surface treatment layer. Therefore, dipping occurred when the adhesive tape was pulled out from the wound body of the adhesive tape, wrinkles formed on the soft aluminum foil of the adhesive tape, and linear inhomogeneous portions also formed on the surface of the adhesive layer. As a result, it was difficult to adhere and attach it neatly to the stainless steel plate. Therefore, although the self-back adhesion was large, when the adhesive tape was immersed in a 5 wt% sulfuric acid aqueous solution (60 °C) for 24 hours in a state where the adhesive tapes were laminated and then the adhesive tape was peeled off, traces of liquid immersion (traces of penetration of the sulfuric acid solution) and adhesive residue were observed. Incidentally, the self-back adhesion and the traces of liquid immersion (traces of penetration of the sulfuric acid solution) after immersion in a 5 wt% sulfuric acid aqueous solution (50 °C) for 3 hours were also not satisfactory.

[0219] In addition, for the adhesive tape of Comparative Example 6, the silicone resin A used for the back surface treatment layer is SiO 4 / 2Although it contains a silica structure having units, since the adhesive layer does not contain a tackifier resin having an acid group, the self-back adhesion after immersion in a 5 wt% sulfuric acid aqueous solution (50 °C) for 24 hours is less than 3.1 N / 10 mm. When the adhesive tape was immersed in a 5 wt% sulfuric acid aqueous solution (60 °C) for 24 hours in a state where the adhesive tapes were laminated and then the adhesive tape was peeled off, traces of liquid immersion (traces of intrusion of the sulfuric acid solution) were observed.

[0220] Although not described in the table, for the adhesive tape of Comparative Example 1, a stainless steel cylindrical member to which the adhesive tape was attached was immersed in a chromium plating bath, heated to 50 °C, and immersed for 3 hours and 24 hours for plating treatment. As a result, the clarity of the plating line was good in the plating treatment with an immersion time of 3 hours and no residue of the adhesive remained. However, it was confirmed that the plating line was overall unclear in the plating treatment with an immersion time of 24 hours.

[0221] From the above evaluation results, it was confirmed that the adhesive tape of the present invention is useful as, for example, a masking tape for a long-time plating treatment of 24 hours.

Explanation of Signs

[0222] 10, 20... Adhesive tape, 1... Back surface treatment layer, 2... Base material, 3... Adhesive layer, 4... Intermediate layer, 5... Stainless steel (SUS304) cylindrical member, 6... Adhesive tape attachment start end line, 7... Adhesive tape attachment end end line, 8a, 8b... Adhesive tape overlapping portion. 9... Stainless steel plate.

Claims

1. An adhesive tape comprising a base material made of metal foil, a back treatment layer formed on one side of the base material, and an adhesive layer formed on the other side of the base material, The aforementioned back processing layer is SiO ４／２ The composition includes a cured product of an addition-reactive silicone resin composition containing a silica structure having units, The adhesive layer comprises a styrene-isoprene-styrene block copolymer and a tackifying resin having acidic groups. The adhesive tape is an adhesive tape having a self-adhesive strength of 3.1 N / 10 mm or more after being immersed in a 5 wt% sulfuric acid aqueous solution (50°C) for 24 hours.

2. The aforementioned back-processed layer has an average of one or more alkenyl groups in its molecule, with an average unit formula: (R １ ３ SiO １／２ ) x (SiO ４／２ ) １．０ (In the formula, R １ R independently represents an alkenyl group having 2 to 10 carbon atoms, an unsubstituted or substituted monovalent hydrocarbon group having 1 to 10 carbon atoms without an aliphatic unsaturated bond, or a hydroxyl group or alkoxy group, and these three R １ The adhesive tape according to claim 1, comprising an organopolysiloxane resin (MQ resin) represented by (one or more of which are alkenyl groups, and x is a number from 0.5 to 2.0).

3. The adhesive tape according to claim 1, wherein the adhesive strength of the back surface after immersion in the 5 wt% sulfuric acid aqueous solution (50°C) for 24 hours is greater than the adhesive strength of the back surface before immersion.

4. The adhesive tape according to claim 1, wherein the adhesive layer has an acid value in the range of 0.3 mg KOH / g or more and 5.5 mg KOH / g or less.

5. The adhesive tape according to claim 1, wherein the content of the tackifying resin is in the range of 20 parts by mass or more and 107 parts by mass or less per 100 parts by mass of the styrene-isoprene-styrene block copolymer.

6. The adhesive tape according to claim 1, wherein the styrene-isoprene-styrene block copolymer has a styrene content in the range of 13% by mass or more and 18% by mass or less, and a styrene-isoprene block content in the range of 50% by mass or more and 80% by mass or less.

7. The adhesive tape according to claim 1, wherein the base material is made of soft aluminum foil.

8. The adhesive tape according to claim 1, further comprising an intermediate layer between the substrate and the adhesive layer, the intermediate layer containing a modified polyolefin resin having acidic groups or hydroxyl groups.

9. The adhesive tape is an adhesive tape according to any one of claims 1 to 8, used for plating masking.

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