Adhesive tape

Abstract

The present invention addresses the problem of providing an adhesive tape which has excellent resistance to plating solution penetration at overlapped portions, particularly during long plating processes (e.g., 24 hours), and which also has superior peelability after plating and excellent contamination resistance in non-plated areas. The adhesive tape comprises a base material comprising a metal foil, a back-surface treatment layer formed on one surface of the base material, and a adhesive layer formed on the other surface of the base material. A releasant layer includes an addition-reaction type silicone resin composition including a silica structure having an SiO4 / 2 unit. The adhesive layer comprises a styrene / isoprene / styrene block copolymer and a tackifier resin having an acid group. The adhesive tape has an adhesive force in application to the back surface thereof of 3.4 N / 10 mm or greater after 24-hour immersion in 5 wt% aqueous sulfuric acid solution.

Description

Adhesive tape

[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.

[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 in the 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 modulus of elasticity.

[0005] Furthermore, Patent Document 2 discloses a masking tape and a method for manufacturing the same, which is mainly suitable for masking (surface protection) when plating the same or different metals onto a metal surface. The purpose is to provide a masking tape and a method for manufacturing the same, in which an adhesive layer is formed on one side of a polyolefin resin substrate, consisting of an adhesive containing a hydrogenated styrene elastomer from which calcium stearate has been removed by prior washing and an adhesive containing low molecular weight polyethylene as an anti-blocking agent.

[0006] Patent Document 3, which has not yet been published, describes an adhesive tape having a base material made of metal foil and an adhesive layer containing A) a styrene-isoprene-styrene block copolymer and B) a tackifying resin having acid groups. When used for plating masking, this adhesive tape improves upon the conventional problems of resistance to plating solution penetration, peelability after plating, and stain resistance of non-plated areas.

[0007] Japanese Patent Publication No. 2004-35965, Japanese Patent Publication No. 2010-77339, Japanese Patent Application No. 2023-041895, Specification

[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 starting end 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 of the unplated portion.

[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, wherein the back treatment layer is made of SiO ４／２It includes a cured product of an addition-reactive silicone resin composition containing a silica structure having units, the adhesive layer includes a styrene-isoprene-styrene block copolymer and an adhesion-imparting resin having an acid group, and the adhesive tape has a self-back adhesion of 3.1 N / 10 mm or more, preferably 3.1 N / 10 mm or more and 10 N / 10 mm or less, more preferably 3.4 N / 10 mm or more and 5.3 N / 10 mm or less after being immersed in a 5 wt% sulfuric acid aqueous solution (50 °C) for 24 hours.

[0011] [2] The back surface treatment layer has an average of one or more alkenyl groups in the molecule, and the average unit formula: (R １ ３ SiO １／２ ),x(SiO ４／２ ), １．０ (wherein R １ 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 an alkoxy group, and one or more of these three R １ are alkenyl groups, and x is a number from 0.5 to 2.0). The adhesive tape of [1] containing an organopolysiloxane resin (MQ resin) represented by

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

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

[0014] [5] The content of the adhesion-imparting 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, more preferably 40 parts by mass or more and 70 parts by mass or less with respect to 100 parts by mass of the styrene-isoprene-styrene block copolymer. The adhesive tape of any one of [1] to [4].

[0015] [6] 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, 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 the styrene-isoprene diblock content is in the range 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, and is an adhesive tape according to any one of [1] to [5].

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

[0017] [8] An adhesive tape according to any one of [1] to [7], which has an intermediate layer containing a modified polyolefin resin having an acid group or a hydroxyl group between the base material and the adhesive layer.

[0018] [9] The adhesive tape is an adhesive tape according to any one of [1] to [8] and is used for plating masking.

[0019]

[10] A plating method, which includes adhering the surface of the adhesive layer of the adhesive tape according to any one of [1] to [8] to a part of the plating surface of the plating target member, performing a plating treatment on the plating surface, and peeling the adhesive tape after the plating treatment is completed.

[0020]

[11] A plated member plated by the plating method according to

[10] .

[0021] According to the present invention, there is provided an adhesive tape that is excellent in resistance to penetration of plating liquid into the overlapped portion, and is also excellent in peelability after plating and stain resistance of the non-plated portion.

[0022] It is a cross-sectional view showing the configuration of an adhesive tape which is an embodiment of the present invention. It is a cross-sectional view showing the configuration of an adhesive tape which is another embodiment of the present invention. It is a cross-sectional view showing the configuration of an adhesive tape which is a reference example of the present invention. It is a cross-sectional view showing the configuration of an adhesive tape which is another reference example of the present invention. It is a perspective view showing a state where an adhesive tape is attached to a stainless steel cylindrical member. It is a top view showing a test piece to be subjected to the acid aqueous solution immersion resistance (liquid immersion) test of the present invention.

[0023] 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.

[0024] [Structure of the Adhesive Tape 10] Figure 1 shows an example of the structure 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 structure 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 be provided with a release liner on the adhesive layer 3 that has release properties relative to the adhesive layer 3, although this is not shown.

[0025] [Usage of 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 "substrate") 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 (substrate) 5 by wrapping it around it, an overlapping layer 8a (approximately 5 to 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.

[0026] Next, the structure of each layer of the adhesive tape 10 of the present invention will be described in detail. <Back surface treatment layer 1> The back surface treatment layer 1 contains a cured product of an addition-reactive silicone resin composition. The back surface treatment layer 1 may be a cured layer composed of a cured product of an addition-reactive silicone resin composition. The addition-reactive silicone resin composition referred to here is a curable organopolysiloxane composition containing (a) an alkenyl group-containing organopolysiloxane, (b) an organohydrogenpolysiloxane, (c) a platinum group metal-based curing catalyst, and (d) a silica structure having SiO ４／２ units.

[0027] (a) Alkenyl group-containing organopolysiloxane The alkenyl group-containing organopolysiloxane as the component (a) is an organopolysiloxane having two or more alkenyl groups bonded to silicon atoms at the terminal and / or side chain sites of the molecule. The component (a) is a liquid or gum-like precursor component for imparting an appropriate peeling effect to the back surface treatment layer 1 and setting the self-back surface adhesive force of the adhesive tape 10 within an appropriate range, and is the base component of the addition-reactive silicone resin composition. The above component (a) may be a linear, branched, or partially cyclic organopolysiloxane, but industrially, linear organopolysiloxanes are preferred.

[0028] The alkenyl group is not particularly limited, and examples thereof include those having about 2 to 8 carbon atoms such as vinyl group, allyl group, propenyl group, isopropenyl group, butenyl group, hexenyl group, cyclohexenyl group, etc. Among these, from the viewpoints of peeling performance and the reactivity of addition-reaction type crosslinking with the organohydrogenpolysiloxane as the component (b) described later, a vinyl group or a hexenyl group is preferred.

[0029] The alkenyl group-containing organopolysiloxane of this component (a) may be used alone, or in combination of two or more having different viscosities or two or more having different numbers of alkenyl groups.

[0030] (b) Organohydrogenpolysiloxane The organohydrogenpolysiloxane, which is 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). That is, the hydrosilyl groups in component (b) and the alkenyl groups in component (a) are crosslinked by a hydrosilylation reaction (addition reaction) promoted by the platinum group metal hardening catalyst of component (c), which will be described later, to form a hardened layer having a three-dimensional network structure.

[0031] 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.

[0032] 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.

[0033] (b) The amount of component is not particularly limited, but for example, the vinyl group (CH) in the alkenyl group in component (a)２ Preferably, the molar ratio of SiH groups in component (b) to the CH- portion 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.

[0034] (c) Platinum group metal hardening catalyst The platinum group metal catalyst, which is component (c), is a catalyst for promoting the hydrosilylation reaction (addition reaction) between component (a) and component (b), and any catalyst known to those skilled in the art for promoting so-called hydrosilylation reactions can be used. Examples of such platinum group metal catalysts include platinum-based, palladium-based, rhodium-based, and ruthenium-based catalysts, and among these, platinum-based catalysts are particularly preferred. Examples of such platinum-based catalysts include chloroplatinic acid, an alcohol solution or aldehyde solution of chloroplatinic acid, complexes of chloroplatinic acid with various olefins or vinylsiloxanes, and complexes of platinum with various olefins or vinylsiloxanes. In particular, platinum alkenylsiloxane complexes such as a complex of chloroplatinic acid and divinyltetramethyldisiloxane, a complex of chloroplatinic acid and tetramethyltetravinylcyclotetrasiloxane, a platinum-divinyltetramethyldisiloxane complex, and a platinum-tetramethyltetravinylcyclotetrasiloxane complex can be preferably used.

[0035] The amount of component (c) should be a catalytic amount, and is usually preferably 1 to 1,000 ppm, and more preferably 5 to 500 ppm, of the amount of platinum-based metal contained in component (c) relative to the total mass of the above-mentioned curable organopolysiloxane composition.

[0036] (d) SiO ４／２ Silica structure having units The back treatment layer 1 of the present invention, in addition to the above components (a), (b), and (c), has a release control agent for appropriately increasing the self-adhesion strength of the adhesive tape 10, which is SiO ４／２ Silica structures having units, so-called silica (SiO ２ ) Further contains fine particles. This results in the adhesive tape 10 having "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 force 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 force.

[0037] 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 from the viewpoint of effectively exhibiting the effect of adding a release control agent, it may be 1% by mass or more, 3% by mass or more, 5% by mass or more, or more than 10% by mass. 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).

[0038] 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.

[0039] 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.

[0040] (e) Other release 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 SiO４／２ It is preferable to include MQ resin as a release control agent other than silica structures having units. MQ resin is a general formula R ３ SiO １／２ The unit M and 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.

[0041] 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 formula. • (e)-1: Having an average of one or more alkenyl groups in the molecule, 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 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 ３ SiO １／２ )y(SiO ４／２ ) １．０ (In the formula, R ２ (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 from 0.5 to 2.0) Organopolysiloxane resin (MQ resin)

[0042] In the average unit formula in (e)-1 above, R １R 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.

[0043] 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.

[0044] 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.

[0045] In the above average unit formula, x is (SiO ４／２ (R) for units １ ３ SiO 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 x is less than 0.5, when blended into the above 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.

[0046] 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.

[0047] (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.

[0048] In the above average unit formula, y is (SiO ４／２ (R) for units ２ ３ SiO 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.

[0049] 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) (it also suppresses the transfer of silicone compounds).

[0050] 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.

[0051] Furthermore, when the back treatment layer 1 contains MQ resin that does not have the alkenyl group of (e)-2, 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 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] (f) Other optional components Furthermore, known hydrosilylation reaction regulators, antioxidants, pigments, stabilizers, antistatic agents, defoaming agents, adhesion enhancers, thickeners, or inorganic fillers other than silica (e.g., alumina) may be added as needed, to the extent that they do not interfere with the effects of the present invention. The amount added may be appropriately selected in accordance with the prior art.

[0053] 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.

[0054] <Addition-reactive silicone resin composition> An addition-reactive silicone resin composition can be prepared, for example, by first uniformly mixing the above components other than (c) a 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 Corporation can be used.

[0055] <Formation of Back 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.

[0056] <Base Material 2> Metal foil is used as the base material 2. 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.

[0057] 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.

[0058] 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 an intermediate layer 4, is preferred.

[0059] <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.

[0060] (Styrene-Isoprene-Styrene Block Copolymer) The styrene-isoprene-styrene block (SIS) copolymer contained in the adhesive composition that constitutes 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.

[0061] 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 has a highly flexible structure, 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 a styrene block and an isoprene block are bonded together.

[0062] 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.

[0063] 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 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 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.

[0064] 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 peeled off again, 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 portion of the adhesive tape 10, making it impossible to neatly adhere it 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, the type and amount of tackifying resin added, the adhesive layer 3 may peel off from 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.

[0065] 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 a strong 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.

[0066] 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.

[0067] 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.

[0068] 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.

[0069] 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., the 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.

[0070] 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.

[0071] 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.

[0072] 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.

[0073] (Tackifying 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.

[0074] "Without acid groups" means that an acid group is not present in substantial quantities. 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), and aliphatic / aromatic copolymer (C5 / C9) hydrocarbon resins), terpene resins (e.g., α-pinene, β-pinene, dipentene), coumarone-indene resins, styrene resins, xylene resins, and resins obtained by hydrogenating these resins.

[0075] 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 above-mentioned acid groups.

[0076] 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.

[0077] 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.

[0078] 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.

[0079] The acid value, which represents the amount of acid groups in the tackifying resin having the above-mentioned acid groups, preferably has a lower limit of 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 or more and 25.0 mg KOH / g or less, more preferably in the range of 5.0 mg KOH / g or more and 25.0 mg KOH / g or less, and even more preferably in the range of 10.0 mg KOH / g or more and 25.0 mg KOH / g or less. 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.

[0080] 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.

[0081] The adhesive composition constituting the adhesive layer 3 may include an acid-free tackifying resin, as exemplified below.

[0082] 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°C), Quintone (trade name) M100 (trade name, softening point: 95°C), Quintone (trade name) A100 (trade name, softening point: 100°C) manufactured by Nippon Zeon Corporation, and T-REZ RB093 (trade name, softening point: 93°C), T-REZ RB100 (trade name, softening point: 100°C), T-REZ RC100 (trade name, softening point: 100°C), and T-REZ RC115 (trade name, softening point: 115°C) manufactured by TonenGeneral Sekiyu K.K. can be used.

[0083] 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.

[0084] The above-mentioned hydrogenated petroleum resin is not particularly limited, but commercially available products such as AlconP-100 (trade name, softening point: 100°C), AlconP-115 (trade name, softening point: 115°C), and AlconP-125 (trade name, softening point: 125°C) manufactured by Arakawa Chemical Industries, Ltd., and T-REZ HA085 (trade name, softening point: 85°C), T-REZ HA103 (trade name, softening point: 103°C), and T-REZ HA125 (trade name, softening point: 125°C) manufactured by TonenGeneral Sekiyu K.K. can be used.

[0085] 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.

[0086] 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.

[0087] 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, that is, 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.

[0088] If the total content of the 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, resulting in poor clarity of the plating lines.

[0089] 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 degree of hydrophilicity of the surface of the adhesive layer 3 tends to increase. In this case, the plating solution can easily penetrate the unplated parts 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, when the adhesive tape 10 is peeled off again, contamination of the unplated parts due to adhesive residue may occur.

[0090] 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.

[0091] 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.

[0092] 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 they are present in large quantities. Furthermore, when acid-modified, the effect of the acid modification tends to be minimal.

[0093] 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.

[0094] 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.

[0095] 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.

[0096] 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.

[0097] (Other Additives) The adhesive composition constituting the adhesive layer 3 may also 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.

[0098] 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.

[0099] (Adhesive layer) The adhesive layer 3, that is, the adhesive composition constituting it, has an acid value within a specific range, that is, an acid value in the range of 0.3 mg KOH / g or more and 5.5 mg KOH / g or less. 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 or more and 5.1 mg KOH / g or less, and more preferably in the range of 0.6 mg KOH / g or more and 3.0 mg KOH / g or less.

[0100] 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.

[0101] 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.

[0102] 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.

[0103] The acid value of the 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 material incorporated into the adhesive composition.

[0104] The thickness of the adhesive layer 3 is not particularly limited, but from the viewpoint of balancing adhesion (adhesion) 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.

[0105] The adhesive tape 10 having such an adhesive layer 3 on the base material 2 is preferably, more preferably, 9.0 N / 10 mm or more, and even more preferably 10.0 N / 10 mm or more, when attached to a stainless steel plate (SUS304 plate, #360 polished finish), stored for 96 hours in a temperature and humidity environment of 50°C and 90% RH, and then measured in accordance with the method described in JIS Z 0237 (2009) at a peeling speed of 5 mm / second, to have a 180° peel adhesive strength (hereinafter sometimes simply referred to as "180° peel adhesive strength") of 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 180° peel adhesive strength is preferably smaller than the adhesion force between the substrate 2 and the adhesive layer 3, as described later, from the viewpoint of suppressing adhesive residue on the unplated portion of the material to be plated when the adhesive tape 10 is peeled off again.

[0106] 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 roller with a mass of 2000 g is moved back and forth once at a speed of 5 mm / 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 storage for 96 hours, 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 5 mm / second in the 180° direction using a tensile testing machine.

[0107] <Intermediate Layer 4> An anchor coating agent may be applied to the surface of the substrate 2 as needed to form an intermediate layer 4, for purposes such as improving adhesion with the adhesive layer 3. By forming the intermediate layer 4, the adhesion between the substrate 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 part of the adhesive layer 3 from the substrate 2 at the cut edge.

[0108] 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 peeled off again, 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.

[0109] 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 adhesive tape (model number: No. 6200 / film tape) made of 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.

[0110] The material of the anchor cart agent 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.

[0111] 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 is bonded to the main chain polyolefin via one of the carbon atoms adjacent to the contained carbonyl group, forming a side chain.

[0112] 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.

[0113] 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.

[0114] In addition to the above-mentioned acid or hydroxyl group-containing polyolefin resin, 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.

[0115] The thickness of the intermediate layer 4 is not particularly limited, but for example, it could be 0.05 g / m² as the coating amount. ２ 0.5g / m or more ２The following range is preferable.

[0116] <Release 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.

[0117] Furthermore, the thickness of the release liner is not particularly limited, but is usually in the range of 25 μm to 125 μm.

[0118] <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 base material 2 where the release agent layer 1 is not formed. In this case, in order to improve the adhesion between the base material 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 base material 2 in advance. 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.

[0119] <Self-adhesive strength on the back> 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.

[0120] The adhesive strength of the back surface can be expressed by the peel strength against the back surface (back surface treatment layer 1). In the present 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, and the tape is peeled. A detailed method for measuring the adhesive strength of the back surface will be described later.

[0121] 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 of the plating solution into the overlapping portion during long-term plating treatment. On the other hand, if the self-back adhesive strength is too high, there is a risk that adhesive residue will easily be 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 there is a risk 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 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).

[0122] [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 member 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").

[0123] The above-mentioned plating methods include wet plating methods such as electrolytic plating and electroless plating. The 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. The 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 plating method should be appropriately selected depending on the type of metal to be plated and the material of the plated surface.

[0124] 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.

[0125] The adhesive tape 10 exhibits excellent performance in terms of resistance to penetration of the plating solution and staining 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.

[0126] 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.

[0127] 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-finished component, 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, with the immersion method being more preferable because it allows for batch processing. Specific examples of wet processes include ultrasonic cleaning in water, immersion in alkaline degreasing solution, immersion in acidic degreasing solution, immersion in surfactant aqueous solution, and immersion in soft etching solution. Among these, from the viewpoint of simplicity, immersion in acidic degreasing solution, immersion in alkaline degreasing solution, and immersion in soft etching solution are preferred as wet processes. Additionally, if necessary, a final cleaning process by electrolytic cleaning or a base plating by strike plating may be performed.

[0128] 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 component to be plated that is to be prevented from being plated, i.e., the surface of the unplated portion, 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 component to be plated is immersed in the plating solution. The main plating treatment is then performed on the unmasked surface of the component 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 (for example, a palladium compound) that has catalytic activity for depositing the metal.

[0129] 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.

[0130] After the plating process described above, the plated component is washed with water, dried by 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.

[0131] Next, the present invention will be described in more detail based on examples. However, the present invention is not limited to the following examples.

[0132] 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.

[0133]

[0134] <Reference Example 1> (Preparation of resin solution for intermediate layer 4) 10 parts by mass of acid-modified polyolefin resin (resin for anchor coat layer, trade name: Unistol P902, acid value: 55 mg KOH / g) manufactured by Mitsui Chemicals, Inc. was dissolved in 130 parts by mass of toluene to prepare a resin solution for intermediate layer 4.

[0135] (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°C, 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°C, 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 the mixture was stirred at room temperature for 48 hours or more to obtain an adhesive solution.

[0136] (Preparation of Reference Adhesive Tape 20) First, a soft aluminum foil (80 μm thick) conforming to JIS H 4160 was prepared as the base material 2. 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. ２ The 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.

[0137] <Reference Example 2> Reference adhesive tape 20 was prepared in the same manner as in 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.

[0138] <Reference Example 3> Reference adhesive tape 20 was prepared in the same manner as in 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.

[0139] <Reference Example 4> Reference adhesive tape 20 was prepared in the same manner as in 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.

[0140] <Reference Example 5> Reference adhesive tape 20 was prepared in the same manner as in 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 in the preparation of the adhesive solution for Reference Adhesive Tape 20.

[0141] <Reference Example 6> Reference adhesive tape 20 was prepared in the same manner as in 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 in the preparation of the adhesive solution for Reference Adhesive Tape 20.

[0142] <Reference Example 7> Reference adhesive tape 20 was prepared in the same manner as in 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.

[0143] <Reference Example 8> Reference adhesive tape 20 was prepared in the same manner as in 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.

[0144] <Reference Example 9> Reference adhesive tape 20 was prepared in the same manner as in Reference Example 3, except that 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.

[0145] <Reference Example 10> Reference adhesive tape 20 was prepared in the same manner as in 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.

[0146] <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.

[0147] <Reference Example 12> 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°C, 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 reference adhesive tape 20, and the thickness of the adhesive layer 3 was changed to 50 μm.

[0148] <Reference Example 13> Reference adhesive tape 20 was prepared in the same manner as in Reference Example 12, 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 40 parts by mass of tackifying resin (3), product name: Quintone (product name) CX495, acid value: 1.8 mg KOH / g, softening point: 96°C, aliphatic (C5) hydrocarbon resin manufactured by Nippon Zeon Co., Ltd. was used instead of 10 parts by mass of tackifying resin (2), product name: Quintone (product 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.

[0149] <Reference Example 14> Reference adhesive tape 20 was prepared in the same manner as in 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 in the preparation of the adhesive solution for Reference Adhesive Tape 20, 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.

[0150] <Reference Comparative 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.

[0151] <Reference Comparative 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.

[0152] <Reference Comparative 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-4, product name: Quintac (product name) 3450, styrene content: 19% by mass, SI diblock content: 30% by mass, polymer structure: radial structure) manufactured by Nippon Zeon Co., Ltd. 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.

[0153] <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-5, product name: KRATON D1161, styrene content: 15% by mass, SI diblock content: 19% by mass, polymer structure: linear structure) manufactured by Kraton Polymers International was used instead of 100 parts by mass of styrene-isoprene-styrene block copolymer (SIS-4, product name: Quintac 3450, styrene content: 19% by mass, SI diblock content: 30% by mass, polymer structure: radial structure) manufactured by Nippon Zeon Co., Ltd.

[0154] <Reference Comparative Example 5> Reference adhesive tape 20 was prepared in the same manner as in 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.

[0155] <Reference Comparative Example 6> Reference adhesive tape 20 was prepared in the same manner as in 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.

[0156] 2. Evaluation Methods 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.

[0157] <Adhesive Tape Characteristics> (1) Thickness of Reference Adhesive Tape 20 The thickness of the reference adhesive tapes 20 prepared in Reference Examples 1 to 14 and Reference Comparative Examples 1 to 6 was measured using a dial gauge in accordance with JIS Z 0237 (2009).

[0158] (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 to 14 and Reference Comparative Examples 1 to 6 were subjected to an adhesion strength test (180° peel adhesion strength test) to the material to be plated (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.

[0159] 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 moved back and forth once at a speed of 5 mm / 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, and then the adhesive strength was measured when the tape was peeled off from the material to be plated (stainless steel plate (SUS304 plate, #360 polished finish)) at a speed of 5 mm / second in a 180° direction using a tensile testing machine.

[0160] (3) Adhesion between the substrate and the adhesive layer The adhesion between the substrate and the adhesive layer of the reference adhesive tapes 20 prepared in Reference Examples 1 to 14 and Reference Comparative Examples 1 to 6 was measured under a temperature of 23°C.

[0161] Specifically, first, the adhesive layer side of a rubber-based adhesive tape (model number: No. 6200 / film tape) made of PET substrate manufactured by Maxell Corporation was attached to the surface of the adhesive layer 3 of the reference adhesive tape 20, and a 2000g roller was pressed down by moving it back and forth once at a speed of 5 mm / second. 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 5 mm / 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.

[0162] (4) Tearability of adhesive tape by hand (adhesive tearing) The tearability of the reference adhesive tapes 20 prepared in Reference Examples 1 to 14 and Reference Comparative Examples 1 to 6 was evaluated under a temperature of 23°C.

[0163] The evaluation criteria were as follows, with a rating of B or higher considered a pass. A: When cut by hand, the adhesive layer hardly stretched and could be cut cleanly together with the substrate, and no peeling of the adhesive layer from the substrate was observed at the cut. B: When cut by hand, the adhesive layer stretched slightly but could be cut relatively cleanly together with the substrate, and almost no peeling of the adhesive from the substrate was observed at the cut. C: When cut by hand, the adhesive layer stretched significantly and could be cut together with the substrate, but peeling of the adhesive layer from the substrate was observed at the cut.

[0164] <Acidic Aqueous Solution Immersion Test> (1) Resistance to Acidic Aqueous Solution Penetration (Liquid Submersion) The resistance to acidic aqueous solution penetration was evaluated for the reference adhesive tapes 20 prepared in Reference Examples 1 to 14 and Reference Comparative Examples 1 to 6. Specifically, first, samples similar to those used in the above adhesive strength test were prepared for each. Next, two types of 60°C sulfuric acid aqueous solutions with different sulfuric acid concentrations were prepared ((1) sulfuric acid concentration: 2% by mass [0.41 N], (2) sulfuric acid concentration: 5% by mass [1.02 N]). Subsequently, each sample was immersed in each 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 state of penetration (liquid submersion) of the acidic aqueous solution.

[0165] The evaluation criteria were as follows, with a rating of B or higher considered a pass. A: No penetration of the acidic aqueous solution was observed at all. B: Slight penetration of the acidic aqueous solution was observed at the edges. C: Significant penetration of the acidic aqueous solution was observed.

[0166] (2) For each of the reference adhesive tapes 20 of Reference Examples 1 to 14 and Reference Comparative Examples 1 to 6, when the reference adhesive tapes 20 were peeled off again in order 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.

[0167] The evaluation criteria were as follows, with a rating of B or higher considered a pass. A: No adhesive residue was observed on the substrate. B: Slight adhesive residue was observed at the edges of the substrate. C: Significant adhesive residue was observed on the substrate.

[0168] <Plating Evaluation> (1) Clarity of Plating Lines (Clarity of Cutting) The reference adhesive tapes 20 prepared in Reference Examples 1, 7, 10, 13 and Reference Comparative Example 1 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 plating masking) was evaluated. Specifically, each reference adhesive tape 20, 25 mm wide and 100 mm long, was attached to the side of a cylindrical member made of stainless steel (SUS304) with a diameter of approximately 50 mm and a height of 70 mm, whose surface had been degreased with thinner. The tapes were 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 cylindrical stainless steel 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. Next, chromium plating was performed for 1 minute at a cathode current density of 40 A / dm2 to form a chromium plating film with a thickness of 0.4 μm on the plated surface. Then, after thoroughly washing the chromium plating solution with tap water, the reference adhesive tape 20 was peeled off again, and the clarity of the plating line was visually observed and evaluated.

[0169] The evaluation criteria were as follows, with a rating of B or higher considered a pass. A: The plating lines were clear. B: There were slight areas where the plating lines were unclear. C: The plating lines were unclear overall.

[0170] (2) Adhesive residue after peeling off the 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 peeled off again in order to evaluate the clarity of the plating lines, the state of 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.

[0171] The evaluation criteria were as follows, with a rating of B or higher considered a pass. A: No adhesive residue was observed on the substrate. B: Slight adhesive residue was observed at the edges of the substrate. C: Significant adhesive residue was observed on the substrate.

[0172] 3. Evaluation Results The evaluation results for Reference Examples 1 to 14 are shown in Tables 2 to 5, and the evaluation results for Reference Adhesive Tape 20 of Reference Comparative Examples 1 to 6 are shown in Tables 6 and 7.

[0173]

[0174]

[0175]

[0176]

[0177]

[0178]

[0179] As shown in Tables 2 to 5, when the adhesive tapes of Reference Examples 1 to 14, in which the adhesive layer 3 satisfies the requirements of the present invention, were applied, it was confirmed that 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, it was confirmed that good results were obtained in all evaluation items (clearness and adhesive residue) of the plating evaluation. In other words, it was found that the adhesive tapes of Reference Examples 1 to 14, in which the adhesive layer 3 satisfies the requirements of the present invention, 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, it was confirmed that good results were obtained in the evaluation of adhesive tearing, and it was found that these adhesive tapes also have excellent tearability by hand.

[0180] Among these reference examples, the adhesive tapes of Reference Examples 1 to 6, in which the styrene-isoprene-styrene block copolymer contains 50% to 80% by mass of styrene-isoprene blocks, the tackifier having an acidic 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.

[0181] 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 of the evaluation items 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) of the plating evaluation items was inferior compared to the adhesive tapes of Reference Examples 1, 7, 10, and 13.

[0182] 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, exhibited low 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 an evaluation of its resistance to acidic aqueous solution penetration (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 to be 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.

[0183] 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 acid-resistant aqueous solution penetration (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.

[0184] 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.

[0185] 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 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 which the tapes were immersed 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.

[0186] 4. Preparation of Adhesive Tape 10 <Raw Materials> The materials shown in Table 8 below were prepared to form the back treatment layer 1 of the adhesive tape 10.

[0187]

[0188] <Example 1> 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) were mixed, and 0.6 parts by mass of platinum group metal curing catalyst (an amount such that the amount of platinum metal relative to silicone resin A is 410 ppm) and toluene / rubber volatile oil SK9 = 1 / 1 mixed solvent were added as diluents and further mixed uniformly to prepare a solution of addition-reactive silicone resin composition with a non-volatile content concentration of 0.48% by mass.

[0189] As the base material 2, a soft 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 soft aluminum foil using a bar coater, dried at 120°C for 3 minutes, and then heated and cured to form the back treatment layer 1. The adhesion amount (Dry) of the back treatment layer 1 was 0.086 g / m². ２ That was the case.

[0190] Next, an adhesive tape 10 was manufactured 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.

[0191] <Examples 2-5, Comparative Examples 1-4> Adhesive tapes 10 were prepared in the same manner as in Example 1, except that the materials and mixing ratios shown in Tables 9-11 were used in the production of the back treatment layer 1.

[0192] <Comparative Example 5> A non-silicone resin solution 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.

[0193] As the 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 the back treatment layer 1. The adhesion amount (Dry) of the back treatment layer 1 was 0.018 g / m². ２ That was the case.

[0194] Next, an adhesive tape 10 was manufactured 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] <Comparative Example 6> An 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.

[0196] 5. Evaluation Method (1) Self-back adhesive strength The self-back adhesive strength of the adhesive tapes 10 prepared in Examples 1 to 5 and Comparative Examples 1 to 6 was evaluated. Specifically, first, the adhesive layer 3 surface of the adhesive tape 10 of the present invention (width 25 mm x length 110 mm) was pressed onto the material to be plated (stainless steel plate (SUS304 plate, #360 polished finish)) using a spatula. Furthermore, the adhesive layer 3 surface of the adhesive tape 10 of the present invention (width 25 mm x length 110 mm) was neatly attached on the back treatment layer 1 (self-back) of the above adhesive tape 10, pressing it onto it with a spatula so as not to shift 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 overlapped with a spatula to press them together 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).

[0197] 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.

[0198] 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.

[0199] 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 cured 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).

[0200] (2) Resistance to penetration of acidic aqueous solutions (liquid immersion) The resistance to penetration of acidic aqueous solutions was evaluated for the adhesive tapes 10 prepared in Examples 1 to 5 and Comparative Examples 1 to 6. 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 attached to a stainless steel plate while being pressed down with 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 attached to the right end of the first piece of adhesive tape as shown in Figure 6, while being pressed down with a spatula, and then pressed down by passing a 2000 g roller back and forth once at a speed of 5 mm / second to prepare a test piece for liquid immersion evaluation. 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.

[0201] The evaluation criteria were as follows, with a rating of B or higher considered a pass. A: No penetration of the acidic aqueous solution was observed at all. B: Slight penetration of the acidic aqueous solution was observed near the edges or overlapping areas. C: Significant penetration of the acidic aqueous solution was observed near the edges or overlapping areas.

[0202] (3) Adhesive residue after peeling off the adhesive tape For each adhesive tape 10 in Examples 1 to 5 and Comparative Examples 1 to 6, when the adhesive tape 10 was peeled off again in order 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.

[0203] The evaluation criteria were as follows, with a rating of B or higher considered a pass. A: No adhesive residue was observed on the substrate. B: Slight adhesive residue was observed on the substrate near the edges or overlapping sections. C: Significant adhesive residue was observed on the substrate.

[0204] 6. Evaluation Results The evaluation results for Examples 1 to 5 are shown in Tables 9 and 10, and the evaluation results for Comparative Examples 1 to 6 are shown in Tables 10 and 11.

[0205]

[0206]

[0207]

[0208] 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.

[0209] In addition, the back processing layer is SiO ４／２The adhesive tapes of Examples 1, 3, and 4, which contained a release control agent in addition to a silica structure having units, tended to have increased self-adhesion compared to the adhesive tape of Example 5, which did not contain a release control agent.

[0210] 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 lines was good and no adhesive residue was generated. Furthermore, when the adhesive tape of Example 1 was measured after immersion in a 5 wt% sulfuric acid aqueous solution (50°C) for 48 hours, it was found to be 3.4 N / 10 mm, which was confirmed to be not significantly different from the value after 24 hours of immersion.

[0211] 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.

[0212] In detail, the adhesive tape of Comparative Example 1 has an adhesive layer that contains 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 ４／２Because it does not contain silica structures with units, the adhesive strength on the back of the tape after immersion in a 5 wt% 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 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. However, the adhesive strength on the back of the tape after immersion in a 5 wt% 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 5 wt% 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.

[0213] Furthermore, although the adhesive tapes of Comparative Examples 2 to 4 contain a styrene-isoprene-styrene block copolymer and an acidic resin in the adhesive layer, the silicone resin B used in the back treatment layer is SiO ４／２ Because it does not contain silica structures with units, the self-adhesion strength of the back surface after immersion in a 5 wt% sulfuric acid aqueous solution (50°C) for 24 hours was less than 3.1 N / 10 mm. When the adhesive tape was peeled off after being immersed in a 5 wt% sulfuric acid aqueous solution (60°C) for 24 hours with multiple layers of tape applied, traces of liquid penetration (evidence of sulfuric acid solution intrusion) were observed. Similarly, the self-adhesion strength of the back surface and traces of liquid penetration (evidence of sulfuric acid solution intrusion) after immersion in a 5 wt% sulfuric acid aqueous solution (50°C) for 3 hours were also unsatisfactory.

[0214] Furthermore, although the adhesive tape of Comparative Example 5 contained a styrene-isoprene-styrene block copolymer and an acidic resin in its adhesive layer, it used an uncured non-silicone resin instead of an addition-reactive silicone resin composition for the back treatment layer. As a result, zipping occurred when pulling the adhesive tape from the winding, wrinkles formed in the soft aluminum foil of the adhesive tape, and linear heterogeneity occurred on the surface of the adhesive layer, making it difficult to adhere cleanly to the stainless steel plate. Therefore, although the self-back adhesive strength was high, when the adhesive tape was 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) and adhesive residue were observed. Similarly, the self-back adhesive strength and traces of liquid penetration (evidence of sulfuric acid solution intrusion) after immersion in a 5 wt% sulfuric acid aqueous solution (50°C) for 3 hours were also unsatisfactory.

[0215] Furthermore, in Comparative Example 6, the adhesive tape used in the back treatment layer was made of SiO ４／２ Although it contains silica structures with units, the adhesive layer does not contain tackifying resins with acid groups. Therefore, after immersion in a 5 wt% sulfuric acid aqueous solution (50°C) for 24 hours, the self-adhesion strength on the back surface was less than 3.1 N / 10 mm. When the adhesive tapes were peeled off after being immersed in a 5 wt% sulfuric acid aqueous solution (60°C) for 24 hours with multiple layers of adhesive tape applied, traces of liquid penetration (evidence of sulfuric acid solution intrusion) were observed.

[0216] Although not shown in the table, regarding the adhesive tape of Comparative Example 1, when a cylindrical stainless steel member to which the adhesive tape was attached was immersed in a chromium plating bath, heated to 50°C, and plated for 3 hours and 24 hours, it was confirmed that the plating line was clear and no adhesive residue was generated after the 3-hour immersion plating treatment, but the plating line was generally unclear after the 24-hour immersion plating treatment.

[0217] Based on the above evaluation results, it was confirmed that the adhesive tape of the present invention is useful, for example, as a masking tape for long-duration plating processes of 24 hours.

[0218] 10, 20... Adhesive tape, 1... Back treatment layer, 2... Base material, 3... Adhesive layer, 4... Intermediate layer, 5... Cylindrical member made of stainless steel (SUS304), 6... Adhesive tape application start line, 7... Adhesive tape application end line, 8a, 8b... Adhesive tape overlapping section. 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, wherein the back treatment layer is made of SiO ４／２ The adhesive tape comprises 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 acid groups, and the adhesive tape 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.

2. The back treatment 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 or 2, 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 any one of claims 1 to 3, 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 any one of claims 1 to 4, 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 any one of claims 1 to 5, 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 any one of claims 1 to 6, wherein the base material is made of soft aluminum foil.

8. The adhesive tape according to any one of claims 1 to 7, 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 used for plating masking, according to any one of claims 1 to 8.

10. A plating method comprising: attaching the adhesive layer surface of an adhesive tape described in any one of claims 1 to 8 to a part of the surface of a member to be plated; performing a plating treatment on the surface of the member to be plated; and peeling off the adhesive tape after the plating treatment is completed.

11. A plated member plated by the plating method described in claim 10.

Images