Adhesive tape and articles using the same

Abstract

To provide an adhesive tape having excellent adhesion to a porous member, and an article using the adhesive tape.SOLUTION: An adhesive tape comprises at least an adhesive layer (A), the adhesive layer (A) composed of an acrylic adhesive. When subjected to a 5 μm compression, the adhesive layer (A) has a strength of 18 N / cm2 or less. There is also provided an article comprising the adhesive layer (A) of the adhesive tape bonded to a porous member.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an adhesive tape used for fixing mesh members and porous sheets (hereinafter collectively referred to as porous members) that have numerous openings that penetrate through both sides. [Background technology]

[0002] For example, speakers and earphones in televisions and audio products have porous members such as mesh or porous sheets that have breathability and sound transmission properties, placed at positions corresponding to the sound-producing and sound-receiving parts to prevent foreign matter such as dust and water droplets from entering. These members are fixed to other parts such as the housing via adhesive tape (see Patent Document 1). [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 7-305038 [Overview of the project] [Problems that the invention aims to solve]

[0004] In order to fix parts with adhesive tape, it is necessary to ensure a sufficient contact area between the adhesive tape and the part. However, porous members generally have a large porosity per unit area, and the line width of the region defining the porosity is small. Furthermore, if the contact area is curved, it is even more difficult to obtain a sufficient contact area with the adhesive layer of the adhesive tape, making it difficult to firmly fix the porous member as it easily peels off the adhesive tape.

[0005] This disclosure has been made in view of the above-mentioned problems, and provides an adhesive tape, etc., with excellent adhesion to porous members. [Means for solving the problem]

[0006] The present invention comprises at least an adhesive layer (A), wherein the adhesive layer (A) is formed of an acrylic adhesive and has a compressive strength of 18 N / cm when compressed to 5 μm in a compressive strength test. 2 The following adhesive tape is provided. [Effects of the Invention]

[0007] The adhesive tape of the present invention exhibits excellent adhesion to porous members, and can firmly fix the porous member to another adherend. [Brief explanation of the drawing]

[0008] [Figure 1] This is a schematic diagram illustrating a method for measuring the compressive strength of the adhesive layer (A) at different compression ratios. [Modes for carrying out the invention]

[0009] The adhesive tape of the present invention has at least an adhesive layer (A), the adhesive layer (A) is formed of an acrylic adhesive, and has a compressive strength of 18 N / cm when compressed to 5 μm in a compressive strength test. 2 The following characteristics apply:

[0010] According to the adhesive tape of the present invention, when the adhesive layer (A) is adhered to a porous member, the adhesive layer (A) can easily penetrate into the numerous openings on the surface (adhered surface) of the porous member, increasing the contact area between the adhesive layer (A) and the porous member, and as a result, a high adhesive strength can be achieved to the porous member.

[0011] The adhesive tape of the present invention may have at least a predetermined adhesive layer (A), and may be a base material-less double-sided adhesive tape with release films provided on both surfaces of the adhesive layer (A), or it may be a single-sided or double-sided adhesive tape having an adhesive layer (A) on at least one surface of the base material. In the case of a double-sided adhesive tape having adhesive layers on both surfaces of the base material, the adhesive layer (A) may be present on at least one surface of the base material, the adhesive layer (A) may be present on both surfaces of the base material, or the adhesive layer (A) may be present on one surface of the base material and a different adhesive layer (B) may be present on the other surface. The adhesive tape having an adhesive layer (A) on both surfaces of the base material is preferable because it can exhibit high adhesive strength to porous members on both sides, thus providing a degree of freedom in the bonding surface of the adhesive tape when attaching it to a porous member. On the other hand, an adhesive tape having an adhesive layer (A) on one side of the substrate and an adhesive layer (B) on the other side is preferable because the side with adhesive layer (A) can be used as the bonding surface to the porous member, thereby exhibiting high adhesive strength to the porous member, and the adhesive layer (B) is bonded to another adherend that fixes the porous member, so the composition and physical properties of the adhesive layer (B) can be appropriately adjusted according to the type of other adherend.

[0012] Furthermore, if the adhesive tape has an adhesive layer on one or both sides of the base material, the adhesive layer may be formed directly on the base material or through another layer.

[0013] The adhesive tape of the present invention will be described in detail below. <1> Adhesive layer (A) In this invention, the adhesive layer (A) is formed of an acrylic adhesive, and the strength when compressed to 5 μm in a compressive strength test is 18 N / cm². 2 The following applies: The adhesive layer (A) constitutes the surface that adheres to the porous member when bonding the adhesive tape of the present invention to the porous member.

[0014] The adhesive layer (A) described above has a compressive strength of 18 N / cm when compressed to 5 μm in a compressive strength test. 2By doing the following, when bonding to the porous member, it becomes easier for the adhesive layer (A) to bite into a large number of openings on the surface of the porous member due to deformation, the contact area with the porous member can be increased, and high adhesive strength can be exhibited. Among them, since the deformability and the biting property into the openings of the adhesive layer (A) are further improved, the strength when compressed by 5 μm in the compression strength test of the adhesive layer (A) is 16 N / cm 2 It is preferably the following, 14 N / cm 2 It is more preferably the following, 11 N / cm 2 It is even more preferably the following. In addition, the lower limit of the strength when compressed by 5 μm in the compression strength test of the adhesive layer (A) is not particularly limited, and can be 0 N / cm 2 or more, and can be 0 N / cm 2 even more than, and can be 0.5 N / cm 2 or more, and can be 1 N / cm 2 or more.

[0015] The strength when compressed by 5 μm in the compression strength test of the adhesive layer (A) can be defined according to the following procedures 1 to 3. · Procedure 1: The adhesive layer (A) with a thickness of 50 μm after drying is laminated so that the total thickness becomes about 1 mm to prepare a test piece (20 mm square, total thickness about 1 mm). As shown in FIG. 1, the test piece 1 is bonded and set to a stainless steel (SUS) block 2 with a thickness of 10 mm and a 50 mm square. Then, in an environment of 23°C and 50% RH, the central part of the test piece is compressed at a speed of 10 mm / min (arrow X in FIG. 1) with a tensile testing machine (compression mode) equipped with a stainless steel (SUS) probe 3 with a diameter of 7 mm, and the compression strength for each compression rate is measured. The compression rate is a value based on the following formula (1). Compression rate (%) = {Movement distance of the probe (μm) / Measured thickness of the test piece (μm)} × 100... Formula (1) · Procedure 2: Next, the compression rate of the adhesive layer (A) of the adhesive tape when compressed by 5 μm from the thickness of the adhesive layer (A) of the adhesive tape (thickness before compression) is calculated from the following formula (2). Compression rate (%) = {5 μm / Thickness of the adhesive layer (A) of the adhesive tape (μm)} × 100... Formula (2) · Step 3: Identify the compressive strength at the compression ratio obtained in Step 2 from the "compressive strength for each compression ratio" measured in Step 1, and set this value as the strength when the adhesive layer (A) is compressed by 5 μm.

[0016] The strength when the adhesive layer (A) is compressed by 5 μm in the compressive strength test can be adjusted by the composition of the adhesive composition constituting the adhesive layer (A), the degree of crosslinking (gel fraction) of the adhesive layer (A), the thickness of the adhesive layer (A), etc.

[0017] When the adhesive tape of the present invention has adhesive layers (A) on both sides of the base material, the strength when each of the adhesive layer (A1) on one side and the adhesive layer (A2) on the other side is compressed by 5 μm in the compressive strength test may be the same or different as long as it is within the above range.

[0018] (Acrylic adhesive) The acrylic adhesive forming the above adhesive layer (A) preferably uses a (meth)acrylic adhesive in which an acrylic copolymer composed of a (meth)acrylate alone or a copolymer of a (meth)acrylate and another monomer is used as a base polymer, and additives such as an adhesion-imparting resin and a crosslinking agent are blended therein as necessary.

[0019] As the above acrylic copolymer contained in the acrylic adhesive, an acrylic copolymer having an alkyl (meth)acrylate monomer as a main monomer component can be preferably used. The alkyl group of the above alkyl (meth)acrylate monomer may be linear or branched, but an alkyl (meth)acrylate monomer having a linear alkyl group is preferred because it is easy to adjust the compressive strength to be low.

[0020] Examples of the alkyl (meth)acrylate monomers mentioned above include alkyl (meth)acrylates in which the number of carbon atoms in the alkyl group is 1 to 18, such as methyl (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, t-butyl (meth)acrylate, n-hexyl (meth)acrylate, n-octyl (meth)acrylate, isooctyl (meth)acrylate, isononyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, lauryl (meth)acrylate, isostearyl (meth)acrylate, isobornyl (meth)acrylate, and cyclohexyl (meth)acrylate. One or more of these can be used. In particular, (meth)acrylate monomers having 2 to 16 carbon atoms in the alkyl group are preferred, (meth)acrylate monomers having 3 to 14 carbon atoms are more preferred, and it is even more preferable to use at least n-butyl (meth)acrylate and / or 2-ethylhexyl (meth)acrylate. By using the above monomers, the desired adhesive strength can be achieved by compressive load, and the conformability and adhesive strength to the bonding surface of the porous member can be improved.

[0021] The content of alkyl (meth)acrylate monomers in the above acrylic copolymer is preferably in the range of 80 to 98.5% by mass of the monomer components constituting the acrylic copolymer, and more preferably in the range of 90 to 98.5% by mass. Furthermore, the content of linear alkyl (meth)acrylate monomers in the alkyl (meth)acrylate monomer is preferably 60 mol% or more, more preferably 75 mol%, and even more preferably 85 mol% or more. This is because increasing the proportion of linear alkyl (meth)acrylate monomers allows for lower compressive strength, making it easier to penetrate into numerous pores and thus increasing the adhesive strength to porous members.

[0022] The monomer components constituting the above-mentioned acrylic copolymer may include, in addition to the alkyl (meth)acrylate monomers described above, vinyl monomers having hydroxyl groups. Examples of vinyl monomers having hydroxyl groups include hydroxyl group-containing (meth)acrylates such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 2-hydroxyhexyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylic, 8-hydroxyoctyl (meth)acrylate, 10-hydroxydecyl (meth)acrylate, and 12-hydroxylauryl (meth)acrylate. Among these, it is preferable to use at least 2-hydroxyethyl (meth)acrylate and 4-hydroxybutyl (meth)acrylate as vinyl monomers having hydroxyl groups.

[0023] The content of the vinyl monomer having hydroxyl groups in the above acrylic copolymer is preferably within the range of 0.01% to 0.2% by mass, and more preferably within the range of 0.01% to 0.1% by mass, of the total monomer components constituting the above acrylic copolymer. By setting the content of vinyl monomer having hydroxyl groups in the total monomer within the above range, the adhesive layer (A) can exhibit the desired adhesive strength under compressive load, thereby improving the conformability and adhesive strength to the adherend surface of the porous member.

[0024] The monomer components constituting the above acrylic copolymer may include, in addition to the alkyl (meth)acrylate monomers described above, vinyl monomers having acidic groups. Examples of vinyl monomers having acidic groups include (meth)acrylic monomers having carboxyl groups such as acrylic acid, methacrylic acid, carboxyethyl (meth)acrylate, carboxypentyl (meth)acrylate, (anhydride) itaconic acid, (anhydride) maleic acid, fumaric acid, crotonic acid, acrylate dimer, and ethylene oxide-modified succinic acid acrylate; vinyl monomers having sulfonic acid groups such as (meth)acrylamidepropanesulfonic acid, sulfopropyl (meth)acrylate, (meth)acryloyloxynaphthalenesulfonic acid, sodium vinylsulfonate, styrenesulfonic acid, allylsulfonic acid, 2-(meth)acrylamide-2-methylpropanesulfonic acid, and (meth)acrylamidepropanesulfonic acid; and (meth)acrylic monomers having phosphate groups such as 2-hydroxyethyl acryloyl phosphate. In particular, it is preferable to use a (meth)acrylic monomer having a carboxyl group, and more preferably to use acrylic acid or methacrylic acid. By using a (meth)acrylic monomer having a carboxyl group, and especially by using acrylic acid or methacrylic acid, the adhesive layer (A) can develop the desired adhesive strength under compressive load, thereby improving the conformability and adhesive strength to the adherend surface of the porous member.

[0025] The content of the vinyl monomer having acid groups in the above acrylic copolymer is preferably in the range of 1% to 30% by mass, more preferably in the range of 1% to 15% by mass, and even more preferably in the range of 1% to 7% by mass, of the total monomer components constituting the above acrylic copolymer. By setting the content of the vinyl monomer having acid groups in the total monomer within the above range, the adhesive layer (A) can exhibit the desired adhesive strength under compressive load, thereby improving the conformability and adhesion strength to the adherend surface of the porous member.

[0026] The monomer components constituting the above acrylic copolymer may include, in addition to the alkyl (meth)acrylate monomers mentioned above, isobornyl (meth)acrylate, cyclohexyl (meth)acrylate, vinyl monomers having an aliphatic cyclic structure; monomers having an amide group such as (meth)acrylamide, N-vinyl-2-pyrrolidone, N,N-dimethylacrylamide, N,N-diethyl (meth)acrylamide, n-vinylcaprolactam, acryloylmorpholine, acrylamide, and 2-(perhydrophthalimido-N-yl)ethyl acrylate; vinyl monomers having an amino group such as aminoethyl (meth)acrylate, N,N-dimethylaminoethyl (meth)acrylate, and N,N-dimethylaminopropyl (meth)acrylate; vinyl monomers having an imide group such as cyclohexylmaleimide, isopropylmaleimide, N-cyclohexylmaleimide, and itaconimide.

[0027] Furthermore, the monomers constituting the acrylic copolymer may also include other copolymerizable vinyl monomers such as vinyl acetate and styrene.

[0028] The weight-average molecular weight of the above acrylic copolymer is preferably 400,000 or more, specifically in the range of 400,000 to 2,000,000, more preferably in the range of 420,000 to 1,500,000, and even more preferably in the range of 600,000 to 1,300,000. By setting the weight-average molecular weight of the acrylic copolymer within the above range, high cohesive force can be achieved, and high adhesive strength can be exhibited to the bonding surface of the porous member.

[0029] The weight-average molecular weight of the above acrylic copolymer is a standard polystyrene equivalent value measured by gel permeation chromatography (GPC). The weight-average molecular weight is measured using the GPC method with a Tosoh Corporation GPC instrument (HLC-8320GPC) under the following conditions.

[0030] Sample concentration: 0.5% by mass (THF solution) Sample injection volume: 100 μL Eluent:THF Flow rate: 1.0mL / min Measurement temperature: 40℃ This column: TSKgel GMHHR-H(S) x 2 tubes) Guard column: TSKguradcolumn HHR(S) Detector: Differential refractometer Standard polystyrene molecular weight: 10,000 to 20,000,000 (manufactured by Tosoh Corporation)

[0031] The above-mentioned acrylic adhesive may contain a tackifying resin to improve adhesion and bonding strength to the adherend. Examples of the tackifying resins that can be used include rosin-based tackifying resins, polymerized rosin-based tackifying resins, polymerized rosin ester-based tackifying resins, rosin phenol-based tackifying resins, stabilized rosin ester-based tackifying resins, disproportionated rosin ester-based tackifying resins, hydrogenated rosin ester-based tackifying resins, terpene-based tackifying resins, terpene phenol-based tackifying resins, petroleum resin-based tackifying resins, (meth)acrylate-based tackifying resins, etc. In particular, it is preferable to use one or more selected from the group consisting of polymerized rosin ester-based tackifying resins, disproportionated rosin ester-based tackifying resins, petroleum-based tackifying resins, and terpene phenol-based tackifying resins, as this provides excellent compatibility with the above-mentioned acrylic copolymer and can further improve the conformability, adhesion, and bonding strength to the adherend surface of the porous member.

[0032] The amount of the tackifying resin in the acrylic copolymer is preferably in the range of 10 to 60 parts by mass, more preferably in the range of 20 to 50 parts by mass, and even more preferably in the range of 20 to 40 parts by mass, per 100 parts by mass of the acrylic copolymer. By setting the amount of the tackifying resin per 100 parts by mass of the acrylic copolymer within the above range, the conformability and adhesion of the adhesive layer (A) to the adherend surface of the porous member can be improved.

[0033] The above-mentioned acrylic adhesive may be crosslinked with a crosslinking agent to enhance the cohesive force of the adhesive layer. Examples of crosslinking agents that can be used include isocyanate-based crosslinking agents, epoxy-based crosslinking agents, metal chelate-based crosslinking agents, and aziridine-based crosslinking agents. Among these, isocyanate-based crosslinking agents and epoxy-based crosslinking agents are more preferable because they are easily mixed with the acrylic copolymer or its solution and can rapidly promote the crosslinking reaction.

[0034] Examples of the above-mentioned isocyanate-based crosslinking agents include tolylene diisocyanate, naphthylene-1,5-diisocyanate, hexamethylene diisocyanate, diphenylmethane diisocyanate, xylylene diisocyanate, and trimethylolpropane-modified tolylene diisocyanate, with tolylene diisocyanate and trimethylolpropane-modified tolylene diisocyanate being preferred.

[0035] The above crosslinking agent can be used by adjusting the amount added to the acrylic copolymer so that the gel fraction of the adhesive layer (A) falls within the range described above.

[0036] The above-mentioned acrylic adhesive may optionally contain known additives such as plasticizers, softeners, antioxidants, flame retardants, fillers such as glass or plastic fibers, balloons, or beads, metal powders, metal oxides, or metal nitrides, colorants such as pigments or dyes, leveling agents, thickeners, water repellents, and defoamers.

[0037] (Adhesive layer (A)) The thickness of the adhesive layer (A) described above is sufficient to ensure that the strength when compressed by 5 μm in a compressive strength test falls within the predetermined range described above, but it is preferably 15 μm or more, more preferably 20 μm or more, and even more preferably 25 μm or more. Furthermore, there is no particular upper limit to the thickness of the adhesive layer (A), but it can be 150 μm or less, and from the viewpoint of thinning the adhesive tape, it is preferably 100 μm or less, more preferably 70 μm or less, and even more preferably 50 μm or less. By setting the thickness of the adhesive layer (A) within the above range, the adhesive layer (A) can deform sufficiently and easily penetrate into the numerous openings on the surface of the porous member. Furthermore, even if the acrylic adhesive forming the adhesive layer (A) is soft, if the thickness of the adhesive layer (A) is too small, the apparent deformation will be small, making it difficult for the adhesive to penetrate into the openings on the surface of the porous member. On the other hand, even if the acrylic adhesive is hard, if the thickness of the adhesive layer (A) is large, the apparent deformation will be large, making it easier for the adhesive to penetrate into the openings on the surface of the porous member.

[0038] Furthermore, if the adhesive tape of the present invention has adhesive layers (A) on both sides of the base material, the thicknesses of the adhesive layer (A1) on one side and the adhesive layer (A2) on the other side may be the same or different, as long as they are within the above range.

[0039] The gel fraction of the adhesive layer (A) is not particularly limited as long as the strength when compressed to 5 μm in a compressive strength test falls within the predetermined range described above, but it is preferably 17% or more, more preferably 20% to 50%, and even more preferably 22% to 40%. This is because setting the gel fraction of the adhesive layer (A) within a preferred range results in high adhesive strength to the adherend surface of the porous member and good shear holding characteristics to the adherend surface.

[0040] The gel fraction of the adhesive layer (A) described above is expressed as the insoluble portion after immersion in toluene for 24 hours, and refers to the value calculated from the following measurement method and formula. (Measurement method) Adhesive (a) used to form the adhesive layer (A) was applied to the release surface of the release liner so that the thickness after drying was 50 μm. The adhesive layer (A) was formed by drying at 100°C for 3 minutes and then aging at 40°C for 2 days. The obtained adhesive layer (A) was cut into 50 mm x 40 mm squares to form test specimens. After measuring the mass (G1) of the above test specimens, the test specimens were immersed in toluene at 23°C for 24 hours. The mixture of the immersed test specimens and toluene was filtered using a 300-mesh wire mesh to extract components insoluble in toluene, and the mass (G2) of the insoluble components dried at 105°C for 1 hour was measured. The gel fraction was calculated based on the above masses (G1) and (G2) and the following formula. Gel fraction (mass %) = (G2 / G1) × 100

[0041] Storage modulus G' of the adhesive layer (A) at 40°C 40 In other words, the storage modulus G' of the acrylic adhesive constituting the adhesive layer (A) at 40°C. 40 The storage modulus G' of the acrylic adhesive constituting the adhesive layer (A) is preferably 52,000 Pa or less, more preferably 40,000 Pa or more and 51,000 Pa or less, and even more preferably 42,000 Pa or more and 51,000 Pa or less. 40 By setting the range to the above, the porous member will be more likely to bite into the openings, improving the adhesive strength and also increasing the shear holding strength. Note that the storage modulus G' 40 If the value is too high, it may become difficult to bite into the openings in the surface of the porous member to be attached, while if the value is too low, it may be difficult to obtain sufficient shear holding force.

[0042] The storage modulus G' of the adhesive layer (A) and the acrylic adhesive forming the adhesive layer (A) at 40°C. 40This refers to the storage modulus (G') measured at 40°C when a viscoelasticity tester (manufactured by T.A. Instruments Japan, product name: ARES G2) is used. The test specimen is placed between parallel discs with a diameter of 8 mm, which are the measuring parts of the tester, to form an adhesive layer with a thickness of approximately 2 mm. The storage modulus (G') is measured at a frequency of 1 Hz from -50°C to 150°C.

[0043] The adhesive tape of the present invention preferably has a 180° peel adhesive strength of the adhesive layer (A) measured by the method described below of 2.5 N / 20 mm or more, more preferably 3.0 N / 20 mm or more, and more preferably 3.5 N / 20 mm or more, so that it can adhere sufficiently to porous members. (Measurement method) Under conditions of 23°C and 50% RH relative humidity, the adhesive surface of the adhesive tape of the present invention, on the side not to be evaluated, is backed with a 25 μm thick polyethylene terephthalate (PET) film, and then cut to a length of 100 mm and a width of 20 mm to obtain a test piece. Next, the adhesive layer (A) side of the test piece is laminated once through a laminator at 23°C and 50% RH with a linear pressure of 1000 N in the center of a mesh (T-No. 180T, water-repellent treated, mesh 180, opening ratio 37%, manufactured by NBC Industries Co., Ltd.) cut to a length of 150 mm and a width of 50 mm. After being left for 24 hours in an environment of 23°C and 50% RH relative humidity, the side of the mesh opposite to the side to which the test piece is laminated is fully fixed to a stainless steel plate measuring 2 mm thick, 200 mm long, and 50 mm wide with fixing tape (adhesive tape as described in Example 1). Then, the adhesive force obtained when peeling the test piece from the mesh in a 180° direction at a tensile speed of 300 mm / min using a tensile testing machine is defined as the 180° peel adhesive force of the adhesive layer (A) of the adhesive tape. If the adhesive tape is substrate-less, consisting only of the adhesive layer (A), one side of the adhesive layer (A) is used as the adhesion surface to the mesh, and the other side is used as the adhesion surface (backing surface) on which the adhesive force is not evaluated. If the substrate has adhesive layers on both sides, one surface of the adhesive layer (the side of adhesive layer (A)) is used as the adhesion surface to the mesh, and the other surface of the adhesive layer is used as the adhesion surface (backing surface) on which the adhesive force is not evaluated.

[0044] <2> Base material The adhesive tape of the present invention may have a base material. The base material can function as a layer that supports the adhesive layer (A). Furthermore, if the adhesive tape of the present invention is a double-sided adhesive tape having adhesive layers on both sides of the base material, the base material functions as a core.

[0045] The above-mentioned substrate is not particularly limited, and for example, resin substrates, foam substrates, nonwoven fabrics, rubber sheets, woven fabrics, paper, glass, metal foils, composites thereof, etc., can be used. The resin substrate is a non-foamed or non-porous resin film or sheet, and is distinguished from nonwoven fabrics and foam substrates.

[0046] In particular, a resin substrate is preferred because it can exhibit high adhesion between the adhesive layer (A) and the substrate, can be easily colored, and readily exhibits shielding and design properties based on the color of the substrate.

[0047] As the resin substrate mentioned above, sheets or films obtained using polyester such as polyester, polyethylene terephthalate, polyethylene naphthalate, and polybutylene terephthalate, polyolefins, polyacrylates, polyvinyl chloride, polyethylene, polypropylene, ethylene vinyl alcohol, polyurethane, polyamide, and polyimide can be used.

[0048] The above-mentioned substrate may contain known additives such as light stabilizers, antioxidants, anti-aging agents, heat stabilizers, colorants such as pigments and dyes, lubricants, fillers, antistatic agents, slip agents, and antiblocking agents.

[0049] The above-mentioned substrate may have a single-layer structure or a multilayer structure of two or more layers.

[0050] The above-mentioned substrate may have a primer layer on its surface and may be surface-treated in order to improve adhesion with the adhesive layer. Examples of surface treatments include sandblasting, solvent treatment, corona discharge treatment, atmospheric pressure plasma treatment, chromic acid treatment, flame treatment, hot air treatment, ozone / ultraviolet irradiation treatment, oxidation treatment, and anchor coating treatment. Furthermore, the surface of the above-mentioned substrate may be treated with release treatment, antistatic treatment, corona treatment, etc.

[0051] The above-mentioned substrate may be colorless or colored. In particular, it is preferable that the above-mentioned substrate be a colored substrate of the same color as the porous member. By making it the same color as the porous member, it is possible to suppress the reduction in design quality caused by the adhesive tape being visible through the openings of the porous member, and the appearance of the product can be improved.

[0052] The above-mentioned colored substrate may be formed, for example, by providing a colored layer on the surface of a resin film by printing or coating, or it can be formed by incorporating a coloring agent into the resin material that makes up the resin film.

[0053] The thickness of the above-mentioned substrate can be set appropriately depending on the application of the adhesive tape. From the viewpoint of thinning, for example, it can be 200 μm or less, 100 μm or less, 80 μm or less, 50 μm or less, 30 μm or less, or 20 μm or less. Furthermore, from the viewpoint of handling and processability of the adhesive tape, the thickness of the above-mentioned substrate can be 1 μm or more, 3 μm or more, or 5 μm or more.

[0054] <3> Adhesive layer (B) If the adhesive tape of the present invention is a double-sided adhesive tape having adhesive layers on both sides of a base material, then one side of the base material may have an adhesive layer (A), and the other side of the base material may have an adhesive layer (B) that is different from adhesive layer (A). "Adhesive layer (B) being different from adhesive layer (A)" means that the strength when compressed by 5 μm in a compression strength test falls outside the range defined by adhesive layer (A).

[0055] The adhesive (b) constituting the adhesive layer (B) described above can be an adhesive used in general adhesive tapes. Examples of such adhesives include acrylic adhesives, urethane adhesives, synthetic rubber adhesives, natural rubber adhesives, and silicone adhesives. Among these, acrylic adhesives are preferred. Details of the acrylic copolymer contained in the acrylic adhesive (composition of monomers, crosslinking agents, tackifying resins, and optional additives constituting the acrylic copolymer, as well as physical properties, etc.) are described above. <1> The details of the acrylic adhesive can be the same as those described in the section on "Adhesive Layer (A)".

[0056] The thickness of the adhesive layer (B) is not particularly limited and can be set appropriately depending on the application, but for example it can be 1 μm or more and 150 μm or less. In particular, from the viewpoint of making the adhesive tape thinner, the thickness may be 100 μm or less, 70 μm or less, 50 μm or less, or 30 μm or less. Furthermore, in order to ensure adhesion by the adhesive layer (B), the thickness may be 3 μm or more, 5 μm or more, 10 μm or more, or 20 μm or more.

[0057] <4> Release Liner The adhesive tape of the present invention may have a release liner disposed on the surface of the adhesive layer. The release liner is not particularly limited, but examples include a base material such as a synthetic resin film such as polyethylene, polypropylene, or polyester film, paper, nonwoven fabric, cloth, foam sheet, metal foil, or laminate thereof, on which at least one side has been subjected to a release treatment such as a silicone-based treatment, a long-chain alkyl-based treatment, or a fluorine-based treatment to enhance release from the adhesive. Among these, a release liner on one side of polyethylene-laminated paper or polyester film that has been subjected to a silicone-based release treatment is preferred.

[0058] The total thickness of the adhesive tape of the present invention can be adjusted as appropriate according to the specifications of the tape and is not particularly limited, but is preferably in the range of 15 μm to 400 μm. In particular, for small articles such as speakers and earphones, where thinness is required, the total thickness of the adhesive tape is preferably 250 μm or less, more preferably 100 μm or less, and even more preferably 60 μm or less. Furthermore, from the viewpoint of adhesion to porous members and processability, the total thickness of the adhesive tape is preferably 15 μm or more, more preferably 20 μm or more, more preferably 25 μm or more, even more preferably 42 μm or more, and even more preferably 52 μm or more. Note that the thickness of the release liner is not included in the total thickness of the adhesive tape.

[0059] <5> Manufacturing method The method for manufacturing the adhesive tape of the present invention can be appropriately selected according to the specifications of the adhesive tape. If the adhesive tape of the present invention is a substrate-less specification, it can be manufactured by coating an acrylic adhesive that forms an adhesive layer (A) onto a release liner and drying it. If the adhesive tape of the present invention has a substrate specification, it may be manufactured by, for example, coating an acrylic adhesive that forms an adhesive layer (A) onto one or both sides of the substrate and drying it (direct method), or by forming an adhesive layer (A) on the surface of a release liner by coating an acrylic adhesive for forming an adhesive layer (A) and drying it, and then transferring the adhesive layer (A) to one or both sides of the substrate (transfer method). In the case of a double-sided specification where an adhesive layer (A) is formed on one side of the substrate and an adhesive layer (B) is formed on the other side, the respective adhesive layers can be formed by the direct method or the transfer method described above using an acrylic adhesive that forms adhesive layer (A) and an adhesive that forms adhesive layer (B).

[0060] Methods for applying adhesive to a substrate or release liner include, for example, using an applicator, roll coater, gravure coater, reverse coater, spray coater, air knife coater, die coater, etc.

[0061] <6> Goods The article of the present invention is an article formed by bonding the above-mentioned adhesive tape to a porous member.

[0062] In the present invention, a porous member refers to a member having a large number of openings that penetrate through both the front and back surfaces, and is not particularly limited as long as it is a member having a large number of openings on its surface. Examples of such porous members include mesh members formed by woven netting, expansion, punching, etc., and porous sheets having a large number of micropores that communicate in the thickness direction. The mesh member usually has a structure in which, in a plan view, the opening positions viewed from one surface coincide with the opening positions viewed from the other surface. On the other hand, in the porous sheet, in a plan view, the opening positions viewed from one surface may or may not coincide. The porous member may have a surface that is hydrophilic or liquid-repellent.

[0063] If the porous member is a mesh member, the material constituting the mesh member is not particularly limited and may be a metal or a resin. Examples of metals include copper, nickel, silver, gold, platinum, aluminum, iron, molybdenum, titanium, chromium, cobalt, zinc, and other metals commonly used in metal meshes. As for the resin, it is not particularly limited as long as a mesh can be created, and known resins such as polyester resin, polyolefin resin, acrylic resin, nylon resin, and fluororesin can be used.

[0064] Whether the number of openings (mesh) per inch of the mesh member is large or small, the adhesive tape of the present invention can fully perform its function by allowing the adhesive layer (A) to penetrate into the openings. The mesh is not particularly limited, but it is preferable to have 140 or more openings to achieve the desired adhesive strength. The upper limit of the mesh is not particularly limited as long as it performs its function as a mesh member, and can be, for example, 1000 or less, and more particularly 700 or less.

[0065] Furthermore, whether the perforation ratio of the mesh member is high or low, the adhesive tape of the present invention can fully perform its function by allowing the adhesive layer (A) to penetrate into the perforations. The perforation ratio is not particularly limited, but is preferably 60% or less. The lower limit of the perforation ratio is not particularly limited as long as it functions as a mesh member, and can be, for example, 10% or more.

[0066] When the mesh size and perforation ratio of the mesh member are within the above range, a balance can be achieved between the proportion in which the adhesive layer (A) penetrates the perforations of the mesh member and the proportion in which it adheres to the non-perforated areas defining the perforations. This allows for superior adhesive strength to the mesh member and enhances the effectiveness of the adhesive tape of the present invention.

[0067] Specific examples of the above-mentioned mesh materials include, but are not limited to, mesh covers used in audio-related equipment such as speaker meshes and earphone meshes, and mobile devices; screen meshes used in screen printing; mesh belts; filters such as air filters and liquid filters; wire nets; metal steel; mesh plates; perforated metal; electrode substrates; and current collectors.

[0068] When the porous member described above is a porous sheet, the material used to form the porous sheet is not particularly limited, and examples of materials used in general-purpose porous sheets can be given. Specifically, these include polyester resins such as polyethylene terephthalate (PET) and polybutylene terephthalate (PBT); polyolefin resins such as polycarbonate (PC), polyethylene (PE), and polypropylene (PP); fluororesins such as polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), ethylene-tetrafluoroethylene copolymer (ETFE), and ethylene-chlorotrifluoroethylene copolymer (ECTFE); resins such as polyimide, polyetherimide, and polyamideimide; and elastomers such as silicone rubber. The porous sheet may be a single layer or a multilayer body with multiple layers laminated together.

[0069] The average pore size of the porous sheet described above can be appropriately designed according to the required properties such as breathability, sound transmission, and waterproofing, and can be, for example, 0.01 μm to 1 μm. Furthermore, the porosity of the porous sheet described above can be appropriately designed according to the required properties such as breathability, sound transmission, and waterproofing, and can be, for example, 5% to 95%, preferably 10% to 80%, and more preferably 20% to 50%.

[0070] Examples of the porous sheets mentioned above include, but are not limited to, sponge sheets, cork, waterproof membranes, sound-permeable membranes, breathable membranes, waterproof sound-permeable membranes, waterproof breathable membranes, filters, separators, and covering materials.

[0071] This disclosure is not limited to the embodiments described above. The embodiments described above are illustrative, and any configuration that is substantially identical to the technical idea described in the claims of this disclosure and achieves similar effects is included within the technical scope of this disclosure. [Examples]

[0072] The present invention will be described in more detail below with reference to examples and comparative examples.

[0073] [Evaluation Method] The evaluation methods used for the adhesive tapes obtained in the examples and comparative examples are shown below.

[0074] (Strength when the adhesive layer is compressed by 5 μm) The strength of the adhesive layer (A1) of the adhesive tapes obtained in the examples and comparative examples was determined when compressed by 5 μm according to the following procedure 1 to 3. Procedure 1: Using each acrylic adhesive composition prepared in the "Preparation of Acrylic Adhesives" section below, adhesive layers with a dry thickness of 50 μm were formed. These adhesive layers were then stacked to create a test specimen (20 mm square, total thickness approximately 1 mm) with a total thickness of approximately 1 mm (thickness was measured before measurement). As shown in Figure 1, the test specimen 1 was placed in the center of a 10 mm thick, 50 mm square stainless steel (SUS) block 2. The central part of the test specimen was then compressed at a speed of 10 mm / min using a tensile testing machine (compression mode) equipped with a 7 mm diameter stainless steel (SUS) probe 3 in a 23°C, 50% RH environment. The compressive strength of the adhesive layers formed by each acrylic adhesive composition was measured for each compression ratio. The compression ratio of the test specimen was calculated based on the following formula (1). Compression ratio (%) = {Probe travel distance (μm) / Actual thickness of test specimen (μm)} × 100 …Equation (1) Step 2: Next, for the adhesive tapes obtained in the examples and comparative examples, the compression ratio of the adhesive layer (A1) of each adhesive tape was calculated from the thickness of the adhesive layer (A1) (thickness before compression) by 5 μm using the following formula (2). Compression ratio (%) = {5 μm / Thickness of adhesive layer (A1) of adhesive tape (μm)} × 100 …Equation (2) Step 3: The compressive strength at the compression ratio determined in Step 2 was identified from the "compressive strength for each compression ratio" measured in Step 1 using the same acrylic adhesive composition, and this value was taken as the strength of the adhesive layer (A1) of the adhesive tape when compressed by 5 μm.

[0075] (180° peel adhesion) Under conditions of 23°C and 50% RH relative humidity, one side (adhesive layer (A2) side) of the adhesive tapes prepared in the examples and comparative examples was backed with a 25 μm thick polyethylene terephthalate (PET) film, and then cut to a length of 100 mm and a width of 20 mm to obtain test specimens. Next, the adhesive side (adhesive layer (A1) side) of the above test specimens was laminated once through a laminator at 23°C and 50% RH with a linear pressure of 1000 N in the center of a mesh (T-No. 180T, water-repellent treated, mesh 180, opening ratio 37%, manufactured by NBC Industries Co., Ltd.) cut to a length of 150 mm and a width of 50 mm. After being left for 24 hours in an environment of 23°C and 50% RH relative humidity, the side of the mesh opposite to the side on which the test specimen was laminated was completely fixed to a stainless steel plate measuring 2 mm thick, 200 mm long, and 50 mm wide with fixing tape (adhesive tape described in Example 1). Then, the adhesive strength was measured when the test specimen was peeled from the mesh in a 180° direction at a tensile speed of 300 mm / min using a tensile testing machine. This adhesive strength was defined as the 180° peel adhesive strength of the adhesive layer (A1) in the adhesive tapes of the example and comparative example.

[0076] (Shear holding strength) Under conditions of 23°C and 50% RH relative humidity, one side (adhesive layer (A1) side) of the adhesive tapes prepared in the examples and comparative examples was backed with 50 μm thick aluminum foil, and then cut to a length of 100 mm and a width of 20 mm. Next, the other adhesive side (adhesive layer (A2) side) was bonded to a stainless steel plate (SUS304 with a hairline finish using #360 sandpaper) with an adhesive area of ​​20 mm x 20 mm (4 cm). 2 A test specimen was prepared by applying pressure to the adhesive tape with a 2kg roller in one pass-through motion. After being left for 1 hour in an environment of 23°C and 50% RH relative humidity, the stainless steel plate side of the test specimen was fixed in an environment of 40°C, and a 500g load was applied to the free end of the adhesive tape in the shear direction. The time (minutes) until the adhesive tape peeled off (fell) was measured while the above load was applied and left in an environment of 40°C. If it was held for 24 hours, the test was terminated there and the result was "1440<".

[0077] (Gel fraction) Each acrylic adhesive composition prepared in the "Preparation of Acrylic Adhesives" section below was applied to the release surface of a release liner so that the thickness after drying was 50 μm. After drying at 100°C for 3 minutes, the material was aged at 40°C for 2 days to form an adhesive layer (A). The resulting adhesive layer (A) was cut into 50 mm x 40 mm squares to form test specimens. After measuring the mass (G1) of the test specimens, they were immersed in toluene at 23°C for 24 hours. The mixture of the immersed test specimens and toluene was filtered using a 300-mesh wire mesh to extract components insoluble in toluene, and the mass (G2) of the insoluble components dried at 105°C for 1 hour was measured. The gel fraction was calculated based on the above masses (G1) and (G2) and the following formula, and this was used as the gel fraction of the adhesive layers (A1) and (A2) formed using each acrylic adhesive composition in the adhesive tapes of the examples and comparative examples. Gel fraction (mass %) = (G2 / G1) × 100

[0078] (Storage modulus G') 40 ) Storage modulus G' 40 The storage modulus (G') at 40°C was measured using a viscoelasticity tester (manufactured by T.A. Instruments Japan, product name: ARES G2). The test specimen was placed between parallel discs with a diameter of 8 mm, which are the measuring parts of the tester, to form an adhesive layer approximately 2 mm thick after drying using each acrylic adhesive composition prepared in the "Preparation of Acrylic Adhesives" section below. The storage modulus (G') at 40°C was measured at a frequency of 1 Hz from -50°C to 150°C. The G' values ​​at 40°C represent the storage modulus (G') at 40°C for each adhesive layer (A1) and (A2) formed using each acrylic adhesive composition in the adhesive tapes of the examples and comparative examples. 40 That's what I decided.

[0079] [Preparation of acrylic adhesive] The acrylic adhesives used in the examples and comparative examples were prepared by the following methods.

[0080] (Acrylic adhesive composition P-1) In a reaction vessel equipped with a stirrer, reflux condenser, nitrogen inlet tube, and thermometer, 93.4 parts by mass of n-butyl acrylate, 3.0 parts by mass of vinyl acetate, 3.5 parts by mass of acrylic acid, and 0.1 parts by mass of 2-hydroxyethyl acrylate, along with 150 parts by mass of ethyl acetate, were charged. The mixture was heated to 72°C while stirring and blowing in nitrogen. Next, 2 parts by mass (0.1% by mass of solids) of 2,2'-azobis(2-methylbutyronitrile) solution, which had been previously dissolved in ethyl acetate, was added to the mixture. The mixture was held at 72°C for 4 hours while stirring, and then held at 75°C for 5 hours. The mixture was diluted with ethyl acetate and filtered through a 200-mesh wire mesh to obtain a solution of acrylic copolymer (A-1) with a weight-average molecular weight of 1,000,000 (35% by mass of non-volatile content).

[0081] To 100 parts by mass of the above acrylic copolymer (A-1), 9.3 parts by mass of polymerized rosin ester tackifying resin D-125 (manufactured by Arakawa Chemical Industries, Ltd.) and 9.3 parts by mass of disproportionated rosin ester tackifying resin A-100 (manufactured by Arakawa Chemical Industries, Ltd.) were mixed and stirred, and then ethyl acetate was added to obtain an adhesive solution with a solid content of 38% by mass. Next, to 100 parts by mass of the above adhesive solution, 0.6 parts by mass of Barnock D-40 (manufactured by DIC Corporation, trimethylolpropane adduct of tolylene diisocyanate, isocyanate group content 7% by mass, nonvolatile content 40% by mass) was added as a crosslinking agent, and the mixture was stirred and mixed until homogeneous to obtain an acrylic adhesive composition (P-1).

[0082] (Acrylic adhesive composition P-2) Acrylic adhesive composition (P-2) was obtained in the same manner as acrylic adhesive composition (P-1), except that the amount of Barnock D-40 added was changed to 0.5 parts by mass.

[0083] (Acrylic adhesive composition P-3) Acrylic adhesive composition (P-3) was obtained in the same manner as acrylic adhesive composition (P-1), except that the amount of Barnock D-40 added was changed to 0.9 parts by mass.

[0084] (Acrylic adhesive composition P-4) Acrylic adhesive composition (P-4) was obtained in the same manner as acrylic adhesive composition (P-1), except that the amount of Barnock D-40 added was changed to 1.24 parts by mass.

[0085] (Acrylic adhesive composition P-5) A solution of acrylic copolymer (A-2) with a weight-average molecular weight of 800,000 (non-volatile content 35% by mass) was obtained by the same procedure as for the preparation of acrylic copolymer (A-1), except that the monomer composition was changed to 70.0 parts by mass of n-butyl acrylate, 25.9 parts by mass of 2-ethylhexyl acrylate, 4.0 parts by mass of acrylic acid, and 0.1 parts by mass of 2-hydroxyethyl acrylate.

[0086] To 100 parts by mass of the above acrylic copolymer (A-2), 10 parts by mass of polymerized rosin ester tackifier D-125 (manufactured by Arakawa Chemical Industries, Ltd.) and 15 parts by mass of disproportionated rosin ester tackifier A-100 (manufactured by Arakawa Chemical Industries, Ltd.) were mixed and stirred, and then ethyl acetate was added to obtain an adhesive solution with a solid content of 40% by mass. Next, 1.5 parts by mass of Barnock D-40 was added to 100 parts by mass of the above adhesive solution as a crosslinking agent, and the mixture was stirred and mixed until homogeneous to obtain an acrylic adhesive composition (P-5).

[0087] (Acrylic adhesive composition P-6) An acrylic adhesive composition (P-6) was obtained in the same manner as the acrylic adhesive composition (P-5), except that the amount of Barnock D-40 added was changed to 1.8 parts by mass.

[0088] (Acrylic adhesive composition P-7) A solution of acrylic copolymer (A-3) with a weight-average molecular weight of 600,000 (non-volatile content 35% by mass) was obtained by the same procedure as for the preparation of acrylic copolymer (A-1), except that the monomer composition was changed to 60.0 parts by mass of n-butyl acrylate, 30.9 parts by mass of 2-ethylhexyl acrylate, 6.0 parts by mass of vinyl acetate, 3.0 parts by mass of acrylic acid, and 0.1 parts by mass of 2-hydroxyethyl acrylate.

[0089] To 100 parts by mass of the above acrylic copolymer (A-3), 10 parts by mass of polymerized rosin ester tackifying resin D-125 (manufactured by Arakawa Chemical Industries, Ltd.) and 15 parts by mass of disproportionated rosin ester tackifying resin A-100 (manufactured by Arakawa Chemical Industries, Ltd.) were mixed and stirred, and then ethyl acetate was added to obtain an adhesive solution with a solid content of 40% by mass. Next, 1.1 parts by mass of Barnock D-40 was added to 100 parts by mass of the above adhesive solution as a crosslinking agent, and the mixture was stirred and mixed until homogeneous to obtain an acrylic adhesive composition (P-7).

[0090] (Acrylic adhesive composition P-8) A solution of acrylic copolymer (A-4) with a weight-average molecular weight of 1.1 million (non-volatile content 35% by mass) was obtained by the same procedure as for the preparation of acrylic copolymer (A-1), except that the monomer composition was changed to 97.94 parts by mass of n-butyl acrylate, 2.0 parts by mass of acrylic acid, and 0.06 parts by mass of 4-hydroxybutyl acrylate.

[0091] To 100 parts by mass of the above acrylic copolymer (A-4), 5 parts by mass of polymerized rosin ester tackifying resin D-125 (manufactured by Arakawa Chemical Industries, Ltd.), 25 parts by mass of disproportionated rosin ester tackifying resin A-100 (manufactured by Arakawa Chemical Industries, Ltd.), and 20 parts by mass of petroleum resin FTR6100 (manufactured by Mitsui Chemicals, Inc.) were mixed and stirred, and then ethyl acetate was added to obtain an adhesive solution with a solid content of 40% by mass. Next, 1.0 part by mass of Barnock D-40 was added to 100 parts by mass of the above adhesive solution as a crosslinking agent, and the mixture was stirred and mixed until homogeneous to obtain an adhesive composition (P-8).

[0092] [Example 1] The above adhesive composition (P-1) was applied to the release-treated surface of a release liner (a 75 μm thick polyethylene terephthalate film with one side release-treated) to a dry thickness of 22 μm, and dried at 85°C for 3 minutes to produce an adhesive layer. Next, one adhesive layer was bonded to each side of a 6 μm thick colorless transparent polyethylene terephthalate film (both sides treated with a corona treatment machine to a wettability index of 56 mN / m) as a substrate, and the two were bonded together from the release liner side using a laminating roll at 23°C and 50% RH with a linear pressure of 50 N / cm. This was then aged for 48 hours at 40°C to obtain an adhesive tape (T-1) with a thickness of 50 μm. Of the adhesive layers bonded to both sides of the substrate, one was designated as adhesive layer (A1) and the other as adhesive layer (A2). The same procedure was followed for other examples and comparative examples.

[0093] [Examples 2-4] Except for using adhesive compositions (P-2) to (P-4) instead of the adhesive composition (P-1) mentioned above, adhesive tapes (T-2) to (T-4) with a thickness of 50 μm were obtained by the same procedure as in Example 1.

[0094] [Example 5] An adhesive tape (T-5) with a thickness of 100 μm was obtained by the same procedure as in Example 1, except that the thickness of the adhesive composition (P-1) after drying was 47 μm.

[0095] [Example 6] An adhesive tape (T-6) with a thickness of 50 μm was obtained by the same procedure as in Example 1, except that the thickness of the adhesive composition (P-1) after drying was 20 μm, and a 10 μm thick black polyethylene terephthalate film was used as the substrate (a 6 μm thick colorless transparent polyethylene terephthalate film with a 4 μm thick black coating layer on one side, both sides treated with a corona treatment machine to a wetting index of 56 mN / m). [Example 7] An adhesive tape (T-7) with a thickness of 69 μm was obtained by the same procedure as in Example 1, except that a 25 μm thick colorless transparent polyethylene terephthalate film (treated on both sides to a wetting index of 56 mN / m using a corona treatment machine) was used as the base material.

[0096] [Example 8] An adhesive tape (T-8) with a thickness of 50 μm was obtained by the same procedure as in Example 1, except that adhesive composition (P-5) was used instead of the adhesive composition (P-1) described above.

[0097] [Example 9] An adhesive tape (T-9) with a thickness of 64 μm was obtained by the same procedure as in Example 1, except that adhesive composition (P-6) was used instead of the above adhesive composition (P-1) to obtain a thickness of 24 μm after drying, and a colorless transparent polyethylene terephthalate film with a thickness of 16 μm (both sides treated with a corona treatment machine to a wetting index of 56 mN / m) was used as the substrate.

[0098] [Example 9] An adhesive tape (T-10) with a thickness of 50 μm was obtained by the same procedure as in Example 1, except that adhesive composition (P-7) was used instead of the adhesive composition (P-1) mentioned above.

[0099] [Comparative Example 1] An adhesive tape (T-11) with a thickness of 30 μm was obtained by the same procedure as in Example 1, except that the thickness of the adhesive composition (P-1) after drying was 12 μm.

[0100] [Comparative Example 2] An adhesive tape (T-12) with a thickness of 50 μm was obtained by the same procedure as in Example 1, except that adhesive composition (P-6) was used instead of the adhesive composition (P-1) mentioned above.

[0101] [Comparative Example 3] An adhesive tape (T-13) with a thickness of 50 μm was obtained by the same procedure as in Example 1, except that adhesive composition (P-5) was used instead of the above adhesive composition (P-1) and the thickness after drying was 19 μm, and the substrate was a colorless transparent polyethylene terephthalate film with a thickness of 12 μm (both sides treated with a corona treatment machine to a wetting index of 56 mN / m).

[0102] [Comparative Example 4] An adhesive tape (T-14) with a thickness of 30 μm was obtained by the same procedure as in Example 9, except that the thickness of the adhesive composition (P-7) after drying was 12 μm.

[0103] [Comparative Example 5] An adhesive tape (T-15) with a thickness of 40 μm was obtained by the same procedure as in Example 1, except that adhesive composition (P-8) was used instead of the above adhesive composition (P-1) and the thickness after drying was 17 μm.

[0104] The results of the evaluation methods described above for the adhesive tapes obtained in Examples 1-10 and Comparative Examples 1-5 are shown in the table below.

[0105] [Table 1]

[0106] [Table 2]

[0107] [Table 3] [Explanation of Symbols]

[0108] 1…Test piece 1, 2…Stainless steel (SUS) block, 3…Stainless steel (SUS) probe

Claims

1. An adhesive tape having at least an adhesive layer (A), The adhesive layer (A) is formed of an acrylic adhesive, the acrylic adhesive contains an acrylic copolymer and a tackifying resin, the acrylic copolymer content is 78.6 to 83.9% by mass of the total amount of the adhesive layer (A), the tackifying resin content is in the range of 10 to 40 parts by mass per 100 parts by mass of the acrylic copolymer, and the strength when the adhesive layer (A) is compressed by 5 μm is 18 N / cm 2 The adhesive tape is as follows: the 180° peel adhesive strength of the adhesive layer (A) is 2.5 N / 20 mm or more, and the thickness of the adhesive layer (A) is 15 μm or more and 150 μm or less.

2. The adhesive tape according to claim 1, characterized in that the adhesive layer (A) has a gel fraction of 20% or more and 50% or less.

3. The adhesive tape according to claim 1 or 2, wherein the adhesive layer (A) has a storage modulus of 50,000 Pa or less at 40°C and a frequency of 1 Hz.

4. The adhesive tape according to any one of claims 1 to 3, having an adhesive layer on both sides of the base material, with the adhesive layer (A) on at least one side of the base material.

5. The adhesive tape according to any one of claims 1 to 4, which is used by bonding the adhesive layer (A) to a porous member.

6. An article comprising a porous member to which an adhesive layer (A) of an adhesive tape described in any one of claims 1 to 5 is bonded.

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