JP2014037543A - Double-sided adhesive tape - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a double-sided adhesive tape the total thickness of which is thin and which has a foam layer and is excellent in re-releasability.SOLUTION: The double-sided adhesive tape has 500 μm or less in total thickness and has a foam layer, a reinforcing layer of 4-25 μm in thickness and adhesive layers as both surface layers. The adhesive layer as a surface layer on at least one side is formed of an adhesive composition including an acrylic polymer composed of an alkyl ester (meth)acrylate having a 4-9C straight-chain or branched-chain alkyl group, a carboxyl group-containing monomer and a hydroxyl group-containing monomer as essential monomer components, a tackifier resin and a crosslinking agent. In the acrylic polymer, the ratio of the alkyl ester (met)acrylate having the 4-9C straight-chain or branched-chain alkyl group based on the total amount of monomers constituting the acrylic polymer is 80-99.9 wt%; the ratio of the carboxyl group-containing monomer based on the same is 0.1-10 wt%; and the hydroxyl group-containing monomer based on the same is 0.01-5 wt%. The double-sided adhesive tape is a re-releasable adhesive tape.

Description

  The present invention relates to a double-sided pressure-sensitive adhesive tape. More specifically, the present invention relates to a double-sided pressure-sensitive adhesive tape having a thin thickness, a foam layer, and excellent removability.

  Conventionally, double-sided pressure-sensitive adhesive tapes (double-sided pressure-sensitive adhesive tapes) with a pressure-sensitive adhesive layer (pressure-sensitive adhesive layer) on both sides of the base material are used in various industrial fields as highly reliable joining and fixing means. Has been. For example, it is used for assembling parts or joining parts together.

  As such a double-sided pressure-sensitive adhesive tape with a base material, for example, a base material using a non-woven fabric (Patent Document 1), a paper base material, or a base material using a plastic film is known. .

  In recent years, cellular phones and the like have been required to have a waterproof function, and a double-sided pressure-sensitive adhesive tape with a base material for fixing parts in such applications has also been required to have a waterproof (waterproof) function. However, when the base material of the double-sided pressure-sensitive adhesive tape with the base material is a nonwoven fabric or paper, these materials are impregnated with water, which causes a problem in terms of waterproofness. In addition, in the case of using a plastic film as a base material, the followability to unevenness (step followability) deteriorates due to the rigidity of the plastic film, and the stepped portion is lifted to obtain a good waterproof property. Was difficult.

  In recent years, the double-sided pressure-sensitive adhesive tape with a base material has been required to be thin from the viewpoint of weight reduction, size reduction, and thickness reduction of the product.

JP 2001-152111 A

  The present inventors have found that a double-sided pressure-sensitive adhesive tape that is a thin film and excellent in waterproof properties can be obtained by using a foam base material as the base material of the double-sided pressure-sensitive adhesive tape with a base material and reducing the thickness.

  However, a double-sided adhesive tape with a base material using a foam base material has a foam base material and a pressure-sensitive adhesive when the product is disassembled or when a part is recovered from the product. There have been problems such as peeling between the layers, damage to the foam base material, delamination due to tearing of the foam base material, and remaining adhesive on the adherend. In particular, when the total thickness of the double-sided pressure-sensitive adhesive tape with a base material using a foam base material is thinned, the above-described problem is remarkably generated in terms of the strength of the foam base material.

  For this reason, the present condition is that the foam base material is used as a base material, and the double-sided adhesive tape with a base material which is thin and excellent in removability is not obtained.

  Accordingly, an object of the present invention is to provide a double-sided pressure-sensitive adhesive tape having a thin total thickness, a foam layer, and excellent removability.

As a result of diligent studies to solve the above problems, the present inventors have provided a reinforcing layer in addition to the foam layer in the double-sided pressure-sensitive adhesive tape in which both surface layers are pressure-sensitive adhesive layers, and at least the surface layer on one side. When the composition of the pressure-sensitive adhesive layer is a specific composition, it has been found that good removability can be obtained even if it has a foam layer and the total thickness is 500 μm or less, and the present invention has been completed.

That is, the present invention has a total thickness of 500 μm or less, a foam layer, a reinforcing layer having a thickness of 4 to 25 μm, and a pressure-sensitive adhesive layer as both surface layers, and at least one surface surface pressure-sensitive adhesive layer. (Meth) acrylic acid alkyl ester having a linear or branched alkyl group having 4 to 9 carbon atoms, a carboxyl group-containing monomer, and a hydroxyl group-containing monomer are essential monomer components. Formed from a pressure-sensitive adhesive composition containing an acrylic polymer, a tackifier resin, and a crosslinking agent,
In the acrylic polymer, the proportion of (meth) acrylic acid alkyl ester having a linear or branched alkyl group having 4 to 9 carbon atoms, carboxyl group-containing monomer, and hydroxyl group-containing monomer is acrylic. 80 to 99.9% by weight of a (meth) acrylic acid alkyl ester having a linear or branched alkyl group having 4 to 9 carbon atoms, based on the total amount of monomer components constituting the polymer, Provided is a double-sided pressure-sensitive adhesive tape for re-peeling, characterized by comprising 0.1 to 10% by weight of a monomer and 0.01 to 5% by weight of a hydroxyl group-containing monomer.

  In the double-sided pressure-sensitive adhesive tape of the present invention, the pressure-sensitive adhesive composition preferably contains 5 to 50 parts by weight of a tackifier resin and 0.001 to 10 parts by weight of a crosslinking agent with respect to 100 parts by weight of an acrylic polymer.

  In the double-sided pressure-sensitive adhesive tape of the present invention, the crosslinking agent is an isocyanate crosslinking agent, and the acrylic polymer is a (meth) acrylic acid alkyl ester having a linear or branched alkyl group having 4 to 9 carbon atoms, carboxyl It is preferable that it is an acryl-type polymer comprised by using a group containing monomer and a hydroxyl group containing monomer as an essential monomer component.

  In the double-sided pressure-sensitive adhesive tape of the present invention, at least one side of the pressure-sensitive adhesive surface has a 180 ° peel adhesive strength (23 ° C., 50% RH, tensile speed of 5 m / min, peeling condition with a peeling angle of 180 °, glass plate) of 15N. / 10 mm or less is preferable.

  In the present application, “removability” refers to the interface between the adherend and the adhesive surface without causing the adhesive to remain on the adherend or the adhesive tape to break when the adhesive tape is peeled off from the adherend. In addition, it means a property that can be easily separated without requiring a large force at the time of peeling.

  The double-sided pressure-sensitive adhesive tape of the present invention has a foam layer, has a thin total thickness, and is excellent in removability. Furthermore, since the double-sided pressure-sensitive adhesive tape of the present invention has a foam layer, it can have characteristics such as impact absorbability, step following ability, water stoppage, workability, and sealability.

FIG. 1 is a schematic cross-sectional view showing an example of the double-sided pressure-sensitive adhesive tape of the present invention. 2A and 2B are schematic views of a sample for evaluation used in measuring the pressure adhesive force, where FIG. 2A is a top view and FIG. 2B is a cross-sectional view taken along line A-A ′. FIG. 3 is a schematic cross-sectional view showing a method for measuring the pressing adhesive force. 4A and 4B are schematic views of a sample for evaluation used for evaluating the drop impact resistance characteristics. FIG. 4A is a top view, and FIG. 4B is a B-B ′ sectional view. FIG. 5 is a schematic diagram of a sample for evaluation used when evaluating waterproof properties, (a) is a top view, and (b) is an end view of a C-C ′ cut portion.

  The double-sided pressure-sensitive adhesive tape of the present invention has at least two pressure-sensitive adhesive layers as a foam layer, a reinforcing layer, and a surface layer. In the present application, the term “pressure-sensitive adhesive tape (pressure-sensitive adhesive tape)” includes a sheet-like material, that is, “pressure-sensitive adhesive sheet (pressure-sensitive adhesive sheet)”. Moreover, the double-sided pressure-sensitive adhesive tape of the present invention may have a form in which sheet-like ones are laminated, or may have a form wound in a roll shape.

  The laminated structure (layer structure) in the double-sided pressure-sensitive adhesive tape of the present invention is not particularly limited as long as both surface layers are pressure-sensitive adhesive layers and have a foam layer and a reinforcing layer. In the double-sided pressure-sensitive adhesive tape of the present invention, the reinforcing layer and the foam layer may be laminated directly or via an adhesive layer. Note that the foam layer and the reinforcing layer may have only one layer or a plurality of layers.

  The double-sided pressure-sensitive adhesive tape of the present invention has at least one foam layer, at least one reinforcing layer, and two surface adhesive layers, and the surface adhesive layer on one side is reinforced with the foam layer. Of the layers, the distance from the reinforcing layer (distance in the thickness direction from the reinforcing layer) is relatively small, and the adhesive layer of the surface layer on the other side is the distance from the foam layer of the foam layer and the reinforcing layer (foaming) When the distance in the thickness direction from the body layer is relatively small, the surface pressure-sensitive adhesive layer on the side where the distance from the reinforcing layer is relatively small can be referred to as the “surface pressure-sensitive adhesive layer on the reinforcing layer side”. On the other hand, the pressure-sensitive adhesive layer on the surface layer on the side having a relatively small distance from the foam layer can be referred to as the “surface pressure-sensitive adhesive layer on the foam layer side”. In the double-sided pressure-sensitive adhesive tape of the present invention, “reinforcing layer-side adhesive surface” refers to an adhesive surface provided by the surface-side adhesive layer on the reinforcing layer side, and “foam layer-side adhesive surface” refers to the foam layer. The adhesive surface provided by the adhesive layer of the surface layer of the side is said.

  As a preferred embodiment of the double-sided pressure-sensitive adhesive tape of the present invention, the double-sided pressure-sensitive adhesive tape has at least one foam layer, at least one reinforcing layer, and two surface adhesive layers, and has at least one surface adhesive layer. It is mentioned that it is an adhesive layer by the side of a reinforcement layer. More specifically, the preferred embodiment includes (a) at least one foam layer, at least one reinforcing layer, and two surface adhesive layers, and both surface adhesives on both sides. (B) at least one foam layer, at least one reinforcing layer, and two surface adhesive layers, and the surface layer on one side The pressure-sensitive adhesive layer is a pressure-sensitive adhesive layer on the surface of the reinforcing layer, and the pressure-sensitive adhesive layer on the surface of the other side is the pressure-sensitive adhesive layer on the surface of the foam layer.

  In particular, the double-sided pressure-sensitive adhesive tape of the present invention has (b) at least one foam layer, at least one reinforcing layer, and two surface adhesive layers. More preferably, the pressure-sensitive adhesive layer is a surface layer on the reinforcing layer side, and the pressure-sensitive adhesive layer on the surface layer on the other side is a pressure-sensitive adhesive layer on the surface layer on the foam layer side. When fixing or sticking a member (part, part) to a desired position (for example, container, casing, product, etc.) through a double-sided pressure-sensitive adhesive tape of the present invention, a reinforcing layer is used from the viewpoint of removability. This is because it is preferable that the adhesive surface on the side is attached to the member and the adhesive surface on the foam layer side is attached to the object.

  As a typical preferred embodiment of the double-sided pressure-sensitive adhesive tape of the present invention, it has a pressure-sensitive adhesive layer on one side of the foam layer, and has a reinforcing layer on the other side of the foam layer via the pressure-sensitive adhesive layer, Furthermore, the structure which has an adhesive layer on this reinforcement layer (lamination structure of an adhesive layer / foam body layer / adhesive layer / reinforcement layer / adhesive layer) is mentioned (refer FIG. 1).

  FIG. 1 is a typical example of a specific configuration of the double-sided pressure-sensitive adhesive tape of the present invention. In FIG. 1, 1 is a double-sided pressure-sensitive adhesive tape, 11a and 11b are pressure-sensitive adhesive layers, 12 is a pressure-sensitive adhesive layer, 13 is a foam layer, and 14 is a reinforcing layer. In addition, the adhesive layer 11a and the adhesive layer 11b are layers which provide the adhesive surface of a double-sided adhesive tape, and the adhesive layer 12 is a layer used for fixation of a foam layer and a reinforcement layer. This double-sided pressure-sensitive adhesive tape has a laminated structure of a foam layer and an adhesive layer as the outermost layer, and a laminated structure of a reinforcing layer and an adhesive layer as the outermost layer. In the double-sided pressure-sensitive adhesive tape having this configuration, the pressure-sensitive adhesive layer 11a on the foam layer 13 is a “surface pressure-sensitive adhesive layer on the foam layer side”, and the pressure-sensitive adhesive surface provided by the pressure-sensitive adhesive layer 11a is “the foam layer side”. "Adhesive surface of". The pressure-sensitive adhesive layer 11b on the reinforcing layer 14 is a “surface-side pressure-sensitive adhesive layer on the reinforcing layer side”, and the pressure-sensitive adhesive surface provided by the pressure-sensitive adhesive layer 11b is “the pressure-sensitive adhesive surface on the reinforcing layer side”. The total thickness of the double-sided pressure-sensitive adhesive tape in FIG. 1 is the pressure-sensitive adhesive surface provided by the pressure-sensitive adhesive layer 11a to the pressure-sensitive adhesive surface provided by the pressure-sensitive adhesive layer 11a (the pressure-sensitive adhesive surface on the reinforcing layer side). Means the distance in the thickness direction (distance a).

  The total thickness of the double-sided pressure-sensitive adhesive tape of the present invention is 500 μm or less (for example, 80 to 500 μm), preferably 400 μm or less (for example, 100 to 400 μm) from the viewpoint of thinning, miniaturization, weight reduction, and resource saving. More preferably 300 μm or less (for example, 120 to 300 μm), and even more preferably 200 μm (for example, 150 to 200 μm). The “total thickness” of the double-sided pressure-sensitive adhesive tape of the present invention refers to the thickness from one adhesive layer surface (adhesive surface) to the other adhesive layer surface.

(Foam layer)
The foam layer is a layer that includes at least one layer in the double-sided pressure-sensitive adhesive tape of the present invention, and is a layer having a cell structure. The foam layer is composed of a foam (foamed structure).

  The cell structure of the foam layer is not particularly limited, but there is a closed cell structure, a semi-continuous semi-closed cell structure (a cell structure in which a closed cell structure and an open cell structure are mixed, and the ratio is not particularly limited). In particular, from the viewpoint of flexibility, a cell structure in which the closed cell structure part is 40% or less, preferably 30% or less in the cell structure of the foam layer is suitable.

The density of double-sided adhesive tape of the foam layer of the present invention (apparent density) can be set appropriately in accordance with the use purpose, 0.67 g / cm ³ or less (preferably 0.40 g / cm ³ or less, More preferably, it is 0.20 g / cm ³ or less. The lower limit of the apparent density of the resin foam is preferably 0.02 g / cm ³ or more (preferably 0.03 g / cm ³ or more). When the apparent density of the foam layer exceeds 0.67 g / cm ³ , foaming becomes insufficient, and the flexibility may be impaired to cause a defect. On the other hand, if it is less than 0.02 g / cm ³ , the strength of the resin foam may be significantly lowered, which is not preferable.

  The average cell diameter of the foam layer of the double-sided pressure-sensitive adhesive tape of the present invention is not particularly limited, but is preferably 10 to 1000 μm, more preferably in terms of impact absorbability, step following ability, water-stopping property, workability, sealability, and the like. Is 15 to 800 μm, and more preferably 20 to 600 μm.

  Although it does not restrict | limit especially as a foam which comprises the foam layer of the double-sided adhesive tape of this invention, A plastic foam (resin foam) is preferable. The plastic material (including the rubber material) for forming the plastic foam is not particularly limited, and can be appropriately selected from known plastic materials. A plastic material can be used individually or in combination of 2 or more types. In addition, the foam may have a single layer form or may have a laminated form.

  Specifically, examples of the plastic foam include olefin resin foams such as polyethylene foam, polypropylene foam, ethylene-propylene copolymer foam, and ethylene-vinyl acetate copolymer foam; polyethylene terephthalate foam Polyester resin foam such as polyethylene naphthalate foam and polybutylene terephthalate foam; Polyvinyl chloride resin foam such as polyvinyl chloride foam; Vinyl acetate resin foam; Polyphenylene sulfide resin foam; Polyamide Amide resin foams such as (nylon) resin foams, wholly aromatic polyamide (aramid) resin foams; polyimide resin foams; polyether ether ketone (PEEK) resin foams; styrene resins such as polystyrene foams Foam; polyurethane resin foam What urethane resin foam and the like. Moreover, you may use a rubber-type resin foam as a plastic foam.

  Of these, olefin-based resin foams are preferable from the viewpoint of good chemical resistance, solvent resistance, moisture permeability resistance, elasticity, and workability, and polyethylene foams and polypropylene foams are particularly preferable.

  In addition, in the plastic foam, the characteristics related to the bubble such as the form of the bubble (the form of the open cell, the form of the closed cell, or the form in which these are mixed), the size of the bubble, the thickness between the bubbles, It is not limited, and can be appropriately selected from the characteristics relating to the bubbles in the known plastic foam. The plastic foam can be formed by using a known or conventional forming method (for example, a forming method using a foaming agent).

  The surface of the foam layer of the double-sided pressure-sensitive adhesive tape of the present invention may be subjected to a known surface treatment. For example, chemical or physical surface treatment such as undercoating treatment, corona discharge treatment, or plasma treatment may be performed. More specifically, the adhesiveness with the pressure-sensitive adhesive layer (the pressure-sensitive adhesive layer that provides the pressure-sensitive adhesive surface of the double-sided pressure-sensitive adhesive tape of the present invention or the pressure-sensitive adhesive layer used for fixing the foam layer and the reinforcing layer) is increased. Therefore, conventional surface treatments such as corona treatment, chromic acid treatment, ozone exposure, flame exposure, high-voltage impact exposure, oxidation treatment by chemical or physical methods such as ionizing radiation treatment, etc. may be applied. A coating treatment with an agent or a release agent may be applied.

  In addition, the foam layer may include a filler (inorganic filler, organic filler, etc.), an anti-aging agent, an antioxidant, an ultraviolet absorber, an antistatic agent, a lubricant, a plasticizer, a flame retardant, Various additives such as a surfactant may be blended.

  It should be noted that the foam layer is a halogen-free foam layer that does not intentionally contain a halogen compound because the double-sided pressure-sensitive adhesive tape of the present invention may be used for the prevention of corrosion against metals and the fixing of electrical and electronic parts. Preferably there is. The halogen compound is generally blended with a flame retardant or plasticizer containing a halogen compound.

  In addition, the foam layer of the double-sided pressure-sensitive adhesive tape of the present invention may be colored in order to develop design properties and optical properties (such as light shielding properties and light reflectivity) in the double-sided pressure-sensitive adhesive tape.

  For example, when the double-sided pressure-sensitive adhesive tape is used for light shielding, the visible light transmittance of the foam is 15% or less (for example, 0 to 15%), more preferably 10% or less, similarly to the visible light transmittance of the double-sided pressure-sensitive adhesive tape. (For example, 0 to 10%) is preferable.

  Moreover, when using a double-sided adhesive tape for light reflection use, the visible light reflectance of a foam is 20% or more (for example, 20-100%) similarly to the visible light reflectance of a double-sided adhesive tape, More preferably, it is 25%. It is preferable to be the above (for example, 25 to 100%).

  A colorant is used for coloring the foam layer. In addition, a coloring agent can be used individually or in combination of 2 or more types.

When the double-sided pressure-sensitive adhesive tape is used for light shielding, the foam layer is colored black. As black, L ^* (brightness) defined by the L ^* a ^* b ^* color system is preferably 35 or less (for example, 0 to 35), more preferably 30 or less (for example, 0 to 30). Note that a ^* and b ^* defined by the L ^* a ^* b ^* color system can be appropriately selected according to the value of L ^* . As a ^* and b ^* , for example, both are preferably in the range of −10 to 10 (particularly −5 to 5), and in particular, both are 0 or almost 0 (−2.5 to 2. 5 range) is preferred.

In this application, L ^* , a ^* , and b ^* defined in the L ^* a ^* b ^* color system are color difference meters (trade name “CR-200” manufactured by Minolta Co .; color difference meter). It is obtained by measuring. The L ^* a ^* b ^* color system is a color space recommended by the International Commission on Illumination (CIE) in 1976, and is a color space called the CIE 1976 (L ^* a ^* b ^* ) color system. It means that. The L ^* a ^* b ^* color system is defined in JIS Z 8729 in the Japanese Industrial Standard.

  Examples of the black colorant used for coloring in black include carbon black (furnace black, channel black, acetylene black, thermal black, lamp black, etc.), graphite, copper oxide, manganese dioxide, aniline black, perylene black, titanium. Use of black, cyanine black, activated carbon, ferrite (nonmagnetic ferrite, magnetic ferrite, etc.), magnetite, chromium oxide, iron oxide, molybdenum disulfide, chromium complex, complex oxide black pigment, anthraquinone organic black pigment, etc. it can. Among these, carbon black is preferable from the viewpoint of cost and availability.

  The amount of the black colorant to be used is not particularly limited, and an amount that can provide desired optical characteristics in the double-sided pressure-sensitive adhesive tape of the present invention is used.

On the other hand, when the double-sided pressure-sensitive adhesive tape is used for light reflection, the foam layer is colored white. As white, L ^* (brightness) defined by the L ^* a ^* b ^* color system is preferably 87 or more (for example, 87 to 100), more preferably 90 or more (90 to 100). Note that a ^* and b ^* defined by the L ^* a ^* b ^* color system can be appropriately selected according to the value of L ^* . As a ^* and b ^* , for example, both are preferably in the range of −10 to 10 (particularly −5 to 5), and in particular, both are 0 or almost 0 (−2.5 to 2. 5 range) is preferred.

  Examples of the white colorant used for coloring in white include titanium oxide (titanium dioxide such as rutile titanium dioxide and anatase titanium dioxide), zinc oxide, aluminum oxide, silicon oxide, zirconium oxide, magnesium oxide, and oxidation. Calcium, tin oxide, barium oxide, cesium oxide, yttrium oxide, magnesium carbonate, calcium carbonate (light calcium carbonate, heavy calcium carbonate, etc.), barium carbonate, zinc carbonate, aluminum hydroxide, calcium hydroxide, magnesium hydroxide, water Zinc oxide, aluminum silicate, magnesium silicate, calcium silicate, barium sulfate, calcium sulfate, barium stearate, zinc white, zinc sulfide, talc, silica, alumina, clay, kaolin, titanium phosphate, mica, gypsum, white carbon Inorganic white colorants such as diatomaceous earth, bentonite, lithopone, zeolite, sericite, hydrous halloysite, acrylic resin particles, polystyrene resin particles, polyurethane resin particles, amide resin particles, polycarbonate resin particles, silicone resins Examples thereof include organic white colorants such as particles, urea-formalin resin particles, and melamine resin particles.

  The amount of the white colorant used is not particularly limited, and an amount that can provide desired optical characteristics in the double-sided pressure-sensitive adhesive tape of the present invention is used.

  The foaming ratio of the foam layer of the double-sided pressure-sensitive adhesive tape of the present invention is, for example, 1.5 to 30 cc / second from the viewpoint of obtaining good shock absorption, step following ability, water-stopping, workability, sealing properties, etc. g is preferred, preferably 2.5 to 25.0 cc / g. In addition, in this application, the expansion ratio of a foam layer is defined as the reciprocal number of the apparent density measured based on JISK6767.

  In addition, the elongation of the foam layer is, for example, 100 to 600% in the MD direction, preferably 400 to 400% from the viewpoint of obtaining good shock absorption, step following ability, water stoppage, workability, sealability and the like with the double-sided pressure-sensitive adhesive tape. 550% and 100 to 500% in the CD direction, preferably 150 to 450%. In the present application, the elongation of the foam layer is measured according to JIS K 6767.

  Furthermore, the tensile strength of the foam layer is, for example, 0.5 to 15 MPa in the MD direction from the viewpoint of obtaining good impact absorbability, step followability, water stoppage, workability, sealability, etc. with a double-sided adhesive tape, Is 1.0-10.0 MPa, 0.5-13.0 MPa in the CD direction, preferably 1.0-9.0 MPa. In addition, in this application, the tensile strength of a foam layer is measured based on JISK6767.

  Furthermore, the compression hardness of the foam layer is obtained by sandwiching the foam layer with a flat plate, for example, from the point of obtaining good shock absorption, step following ability, water stoppage, workability, sealability, etc. with a double-sided adhesive tape, 5-150 kPa is preferable at the load when 25% of initial thickness is compressed, More preferably, it is 12-120 kPa. In addition, in this application, the compression hardness of a foam layer is measured based on JISK6767.

  The thickness of the foam layer of the double-sided pressure-sensitive adhesive tape of the present invention can be appropriately selected according to strength, flexibility, purpose of use and the like, as long as the total thickness of the double-sided pressure-sensitive adhesive tape does not exceed 500 μm, and is preferably 50 to 480 μm, for example. Is 80 to 300 μm, more preferably 100 to 200 μm. If the thickness of the foam layer is less than 50 μm, through holes may be formed, and if the thickness of the foam layer exceeds 480 μm, the double-sided pressure-sensitive adhesive tape may not be able to ensure sufficient adhesive properties.

(Reinforcing layer)
Unlike the above-mentioned foam layer, the reinforcing layer of the double-sided pressure-sensitive adhesive tape of the present invention is a non-foamed layer that does not have a cell structure, and is composed of a non-foamed structure. In the double-sided pressure-sensitive adhesive tape of the present invention, the reinforcing layer is a layer that contributes to improvement of removability.

  As the non-foamed structure constituting the reinforcing layer of the double-sided pressure-sensitive adhesive tape of the present invention, various thin-leaf shaped sheets can be suitably used. Such a sheet is not particularly limited, but includes, for example, fiber-based sheets such as cloth, nonwoven fabric, felt, and net; paper-based sheets such as various papers; metal-based sheets such as metal foils and metal plates; And plastic-based sheets such as films and sheets; and laminates thereof.

  Examples of the material or material of the plastic sheet include polyester (polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, polybutylene naphthalate, etc.), polyolefin (polyethylene, polypropylene, ethylene-propylene copolymer, etc.), and polyvinyl alcohol. , Polyvinylidene chloride, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, polyvinyl acetate, polyamide, polyimide, cellulose, fluororesin, polyether, polystyrene resin (polystyrene, etc.), polycarbonate, polyethersulfone, etc. Is mentioned.

  Further, on the surface of the reinforcing layer base material, if necessary, a conventional surface treatment such as chromic acid treatment, ozone exposure, flame exposure, high piezoelectric exposure, Oxidation treatment or the like by a chemical or physical method such as ionizing radiation treatment may be performed.

  The thickness of the reinforcing layer of the double-sided pressure-sensitive adhesive tape of the present invention is not particularly limited, but is preferably 2 to 250 μm from the viewpoints of removability, shock absorption, step following ability, water-stopping, workability, and sealing properties, preferably Is 4 to 25 μm.

(Surface adhesive layer)
The pressure-sensitive adhesive layer on the surface layer on at least one side of the double-sided pressure-sensitive adhesive tape of the present invention is an essential monomer component of a (meth) acrylic acid alkyl ester having a linear or branched alkyl group having 4 to 9 carbon atoms. Is formed from a pressure-sensitive adhesive composition containing an acrylic polymer, a tackifier resin, and a crosslinking agent. The pressure-sensitive adhesive layers of both surface layers may be formed from a pressure-sensitive adhesive composition having the same composition, or may be formed from pressure-sensitive adhesive compositions having different compositions. The “pressure-sensitive adhesive composition” includes the meaning of “a composition for forming a pressure-sensitive adhesive”.

  In particular, in the double-sided pressure-sensitive adhesive tape of the present invention, the surface layer pressure-sensitive adhesive layer on the reinforcing layer side is essentially a single amount of (meth) acrylic acid alkyl ester having a linear or branched alkyl group having 4 to 9 carbon atoms. It is preferably formed from an adhesive composition containing an acrylic polymer, a tackifier resin, and a cross-linking agent that are configured as body components. When fixing a member (part, part) to a desired position of a target object (for example, container, casing, product, etc.) via the double-sided adhesive tape of the present invention, the adhesive surface on the reinforcing layer side is attached to the member. The adhesive layer on the foam layer side is preferably affixed to the object, and the releasability is particularly required in the surface adhesive layer on the reinforcing layer side.

  In the pressure-sensitive adhesive composition, an acrylic polymer (simply composed of the (meth) acrylic acid alkyl ester having a linear or branched alkyl group having 4 to 9 carbon atoms as an essential monomer component) The content of “sometimes referred to as“ acrylic polymer ”” is preferably 50% by weight or more (for example, 50 to 95% by weight), more preferably 70% by weight or more (based on the total solid content). For example, 70 to 85% by weight).

  The acrylic polymer is composed of (meth) acrylic acid alkyl ester having a linear or branched alkyl group having 4 to 9 carbon atoms as an essential monomer component. A polymer (copolymer) obtained by polymerizing (or copolymerizing) a polymerizable copolymerizable monomer.

  Examples of the (meth) acrylic acid alkyl ester having a linear or branched alkyl group having 4 to 9 carbon atoms include butyl (meth) acrylate, isobutyl (meth) acrylate, (meth) acrylic acid s- Butyl, t-butyl (meth) acrylate, pentyl (meth) acrylate, isopentyl (meth) acrylate, hexyl (meth) acrylate, heptyl (meth) acrylate, octyl (meth) acrylate, (meth) acryl Examples include 2-ethylhexyl acid, isooctyl (meth) acrylate, nonyl (meth) acrylate, and isononyl (meth) acrylate. These (meth) acrylic acid alkyl esters are used alone or in combination of two or more.

  As the (meth) acrylic acid alkyl ester having a linear or branched alkyl group having 4 to 9 carbon atoms, particularly from the viewpoint of low-temperature adhesion and rough surface adhesion, butyl acrylate (BA), 2-ethylhexyl acrylate (2EHA) is preferred. That is, as a suitable acrylic polymer, a polymer composed of one kind of butyl acrylate or 2-ethylhexyl acrylate as an essential monomer component; butyl acrylate and 2-ethylhexyl acrylate as an essential monomer. Examples thereof include a polymer constituted as a monomer component. When the acrylic polymer is a polymer having butyl acrylate and 2-ethylhexyl acrylate as essential monomer components, butyl acrylate is the total amount (total weight) of butyl acrylate and 2-ethylhexyl acrylate. The content is preferably 50% by weight or more.

  Since the (meth) acrylic acid alkyl ester having a linear or branched alkyl group having 4 to 9 carbon atoms is a main monomer component constituting the acrylic polymer, it constitutes an acrylic polymer. The proportion of the (meth) acrylic acid alkyl ester relative to the total amount of the monomer components is preferably, for example, 80% by weight or more (for example, 80 to 99.9% by weight), more preferably 85% by weight or more (for example, 85-98 wt%), and still more preferably 90 wt% or more (for example, 90-95 wt%).

  As described above, the acrylic polymer may contain various copolymerizable monomers such as a polar group-containing monomer and a polyfunctional monomer as a constituent monomer component. By including a copolymerizable monomer as the monomer component, for example, the adhesive force to the adherend can be improved in the surface pressure-sensitive adhesive layer, or the cohesive force of the surface pressure-sensitive adhesive layer can be increased. In addition, a copolymerizable monomer can be used individually or in combination of 2 or more types.

  Examples of the polar group-containing monomer include, for example, (meth) acrylic acid, itaconic acid, maleic acid, fumaric acid, crotonic acid, isocrotonic acid and other carboxyl group-containing monomers or anhydrides thereof (maleic anhydride, etc. Hydroxyl group-containing monomers such as hydroxyalkyl (meth) acrylate such as hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, hydroxybutyl (meth) acrylate; acrylamide, methacrylamide, N, N -Amide group-containing monomers such as dimethyl (meth) acrylamide, N-methylol (meth) acrylamide, N-methoxymethyl (meth) acrylamide, N-butoxymethyl (meth) acrylamide; aminoethyl (meth) acrylate, ( (Meth) acrylic acid dimethylaminoethyl, (meth) acrylic acid Amino group-containing monomers such as t-butylaminoethyl phosphate; Glycidyl group-containing monomers such as glycidyl (meth) acrylate and methyl glycidyl (meth) acrylate; Monomers containing cyano groups such as acrylonitrile and methacrylonitrile Body: N-vinyl-2-pyrrolidone, (meth) acryloylmorpholine, N-vinylpyridine, N-vinylpiperidone, N-vinylpyrimidine, N-vinylpiperazine, N-vinylpyrrole, N-vinylimidazole, N-vinyl Heterocycle-containing vinyl monomers such as oxazole; (meth) acrylic acid alkoxyalkyl monomers such as methoxyethyl (meth) acrylate and ethoxyethyl (meth) acrylate; sulfonic acid group-containing monomers such as sodium vinyl sulfonate 2-Hydroxyethylacryloyl Phosphoric acid group-containing monomers such as Osufeto; cyclohexyl maleimide, imide group-containing monomers such as isopropyl maleimide; 2-methacryloyl isocyanate group-containing monomers such as methacryloyloxyethyl isocyanate, and the like. In the double-sided pressure-sensitive adhesive tape of the present invention, the polar group-containing monomer includes a carboxyl group-containing monomer from the viewpoint of suppressing adhesive residue on the adherend during peeling and obtaining easy peelability from the adherend. A monomer, an anhydride thereof, and a hydroxyl group-containing monomer are preferable, and acrylic acid and hydroxyethyl acrylate are particularly preferable.

  In particular, in the double-sided pressure-sensitive adhesive tape of the present invention, as a monomer component constituting the acrylic polymer, it is possible to suppress adhesive residue on the adherend during peeling and to obtain easy peelability from the adherend. When the polar group-containing monomer is included, it is preferable that both the carboxyl group-containing monomer or its anhydride and the hydroxyl group-containing monomer are included at the same time.

  The ratio of the polar group-containing monomer is not particularly limited, but it is 15% by weight with respect to the total amount of monomer components constituting the acrylic polymer from the viewpoint of the balance between the adhesiveness on the adhesive surface and the removability. % Or less (for example, 0.01 to 15% by weight), more preferably 10% by weight or less (for example, 0.1 to 10% by weight), and even more preferably 5% by weight or less (for example, 0.1 to 5%). % By weight), and even more preferably 3% by weight or less (for example, 0.1 to 3% by weight).

  Examples of the polyfunctional monomer include hexanediol di (meth) acrylate, butanediol di (meth) acrylate, (poly) ethylene glycol di (meth) acrylate, and (poly) propylene glycol di (meth). ) Acrylate, neopentyl glycol di (meth) acrylate, pentaerythritol di (meth) acrylate, pentaerythritol tri (meth) acrylate, dipentaerythritol hexa (meth) acrylate, trimethylolpropane tri (meth) acrylate, tetramethylolmethanetri (Meth) acrylate, allyl (meth) acrylate, vinyl (meth) acrylate, divinylbenzene, epoxy acrylate, polyester acrylate, urethane acrylate and the like. The proportion of the polyfunctional monomer is preferably 2% by weight or less (for example, 0.01 to 2% by weight), more preferably 0.02 to less than the total amount of monomer components constituting the acrylic polymer. 1% by weight. When the ratio of the polyfunctional monomer exceeds 2% by weight, the cohesive force of the pressure-sensitive adhesive layer on the surface layer becomes too high, and the adhesiveness may be lowered. Moreover, when the ratio of the polyfunctional monomer is too small (for example, less than 0.01% by weight based on the total amount of the monomer components constituting the acrylic polymer), for example, aggregation of the pressure-sensitive adhesive layer on the surface layer The power may be reduced.

  In addition to the polar group-containing monomer and the multifunctional monomer, the acrylic polymer may be used as a constituent copolymerizable monomer component such as vinyl acetate, vinyl propionate, or the like. Esters; aromatic vinyl compounds such as styrene and vinyl toluene; olefins or dienes such as ethylene, butadiene, isoprene and isobutylene; vinyl ethers such as vinyl alkyl ether; vinyl chloride and the like can be used. Furthermore, (meth) acrylic acid ester etc. which have alicyclic hydrocarbon groups, such as cyclopentyl (meth) acrylate, cyclohexyl (meth) acrylate, and isobornyl (meth) acrylate, can be included.

  Furthermore, the above-mentioned acrylic polymer includes, for example, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, and the like as constituent monomer components. (Meth) acrylic acid alkyl ester having a linear or branched alkyl group having 1 to 3 carbon atoms, decyl (meth) acrylate, isodecyl (meth) acrylate, undecyl (meth) acrylate, (meth ) Dodecyl acrylate, tridecyl (meth) acrylate, tetradecyl (meth) acrylate, pentadecyl (meth) acrylate, hexadecyl (meth) acrylate, heptadecyl (meth) acrylate, octadecyl (meth) acrylate, (meth) C10-20, such as nonadecyl acrylate and eicosyl (meth) acrylate Having a linear or branched alkyl group (meth) may contain an acrylic acid alkyl ester.

  In particular, the acrylic polymer is a straight chain having 4 to 9 carbon atoms from the viewpoint of more effectively exhibiting both adhesive properties and removability on the adhesive surface of the double-sided adhesive tape of the present invention. It is preferable that a (meth) acrylic acid alkyl ester having a chain or branched alkyl group, a carboxyl group-containing monomer, and a hydroxyl group-containing monomer are constituted as essential monomer components.

  In particular, when the pressure-sensitive adhesive composition contains an isocyanate-based cross-linking agent described later as an additive, the acrylic polymer is a (meth) acrylic acid alkyl ester having a linear or branched alkyl group having 4 to 9 carbon atoms. It is preferable that a carboxyl group-containing monomer and a hydroxyl group-containing monomer are constituted as essential monomer components. This is because the adhesive surface of the double-sided pressure-sensitive adhesive tape of the present invention can obtain both properties of adhesive properties and removability at a higher level.

  The acrylic polymer is an essential (single amount) (meth) acrylic acid alkyl ester having a linear or branched alkyl group having 4 to 9 carbon atoms, a carboxyl group-containing monomer, and a hydroxyl group-containing monomer. The ratio of each monomer component in the case where it is constituted as a body component has 4 to 9 carbon atoms with respect to the total amount of monomer components constituting the acrylic polymer from the point of obtaining the above effect more effectively. (Meth) acrylic acid alkyl ester having a linear or branched alkyl group 80 to 99.9% by weight, carboxyl group-containing monomer 0.1 to 10% by weight, hydroxyl group-containing monomer 0.01 to 5 It is preferable that it is weight%. In particular, 85 to 95% by weight of a (meth) acrylic acid alkyl ester having a linear or branched alkyl group having 4 to 9 carbon atoms, containing a carboxyl group, based on the total amount of monomer components constituting the acrylic polymer. More preferably, it is 0.1 to 5% by weight of the monomer and 0.05 to 3% by weight of the hydroxyl group-containing monomer.

  The acrylic polymer can be obtained by polymerizing the monomer component by a known or conventional polymerization method. Examples of the polymerization method of the acrylic polymer include a solution polymerization method, an emulsion polymerization method, a bulk polymerization method, and a polymerization method by active energy ray irradiation (active energy ray polymerization method). Among them, the solution polymerization method and the active energy ray polymerization method are preferable in terms of transparency, water resistance, cost, and the like, and the solution polymerization method is more preferable.

  In solution polymerization, various common solvents can be used. Examples of such solvents include esters such as ethyl acetate and n-butyl acetate; aromatic hydrocarbons such as toluene and benzene; aliphatic hydrocarbons such as n-hexane and n-heptane; cyclohexane and methylcyclohexane Organic solvents such as ketones such as methyl ethyl ketone and methyl isobutyl ketone. A solvent can be used individually or in combination of 2 or more types.

  In the polymerization of the acrylic polymer, a polymerization initiator can be used. Such a polymerization initiator can be appropriately selected from known or commonly used ones. Examples of the polymerization initiator include 2,2′-azobisisobutyronitrile, 2,2′-azobis (4-methoxy-2,4-dimethylvaleronitrile), 2,2′-azobis (2,4 -Dimethylvaleronitrile), 2,2'-azobis (2-methylbutyronitrile), 1,1'-azobis (cyclohexane-1-carbonitrile), 2,2'-azobis (2,4,4-trimethyl) Pentane), azo polymerization initiators such as dimethyl-2,2′-azobis (2-methylpropionate); benzoyl peroxide, t-butyl hydroperoxide, di-t-butyl peroxide, t-butyl peroxide Oxybenzoate, dicumyl peroxide, 1,1-bis (t-butylperoxy) -3,3,5-trimethylcyclohexane, 1,1-bis (t Such as butyl peroxy) an oil-soluble polymerization initiator such as peroxide polymerization initiators such as cyclododecane and the like. In addition, a polymerization initiator can be used individually or in combination of 2 or more types. The amount of the polymerization initiator used is not particularly limited as long as it can be conventionally used as a polymerization initiator.

  The crosslinking agent contained in the pressure-sensitive adhesive composition for forming the surface pressure-sensitive adhesive layer of the double-sided pressure-sensitive adhesive tape of the present invention is not particularly limited. For example, an isocyanate-based crosslinking agent, an epoxy-based crosslinking agent, a melamine-based crosslinking agent, In addition to oxide crosslinking agents, urea crosslinking agents, metal alkoxide crosslinking agents, metal chelate crosslinking agents, metal salt crosslinking agents, carbodiimide crosslinking agents, oxazoline crosslinking agents, aziridine crosslinking agents, amine crosslinking agents Etc. The reason why the cross-linking agent is included in the pressure-sensitive adhesive composition forming the surface pressure-sensitive adhesive layer of the double-sided pressure-sensitive adhesive tape of the present invention is to improve anchoring property and prevent cohesive failure of the pressure-sensitive adhesive layer. In addition, a crosslinking agent can be used individually or in mixture of 2 or more types.

  Among them, the acrylic polymer contained in the surface pressure-sensitive adhesive layer can be cross-linked to further increase the cohesive force of the pressure-sensitive adhesive layer, and the pressure-sensitive adhesive property and removability can be balanced at a higher level. From the standpoint of compatibility, an isocyanate-based crosslinking agent is preferable.

  Examples of such isocyanate-based crosslinking agents (polyfunctional isocyanate compounds) include lower aliphatic polyisocyanates such as 1,2-ethylene diisocyanate, 1,4-butylene diisocyanate, and 1,6-hexamethylene diisocyanate; Alicyclic polyisocyanates such as pentylene diisocyanate, cyclohexylene diisocyanate, isophorone diisocyanate, hydrogenated tolylene diisocyanate, hydrogenated xylene diisocyanate; 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 4,4 ′ -Aromatic polyisocyanates such as diphenylmethane diisocyanate, xylylene diisocyanate, etc., etc., with trimethylolpropane / tolylene diisocyanate Things [Nippon Polyurethane Industry Co., Ltd. under the trade name "Coronate L"], trimethylolpropane / hexamethylene diisocyanate adduct [Nippon Polyurethane Industry Co., Ltd. under the trade name "Coronate HL"], and also such. When the pressure-sensitive adhesive composition for forming the surface pressure-sensitive adhesive layer of the double-sided tape of the present invention contains an isocyanate-based crosslinking agent, a monomer component containing a hydroxyl group-containing monomer as a copolymerizable monomer is used at the same time. It is preferable to include an acrylic polymer obtained by copolymerization.

  The content of the cross-linking agent in the pressure-sensitive adhesive composition is not particularly limited, but the acrylic polymer can be cross-linked, and the cohesive force of the pressure-sensitive adhesive layer can be further increased. Is preferably 0.001 to 10 parts by weight, more preferably 0.01 to 7% by weight, even more preferably, with respect to 100 parts by weight of the acrylic polymer. Is 0.1 to 5 parts by weight.

  It does not specifically limit as tackifying resin (tackifier) contained in the adhesive composition which forms the adhesive layer of the surface layer of the double-sided adhesive tape of this invention, For example, terpene type tackifying resin, phenol type tackifying Resins, rosin-based tackifier resins, petroleum-based tackifier resins, and the like. The reason why the tackifying resin is included in the pressure-sensitive adhesive composition forming the surface pressure-sensitive adhesive layer of the double-sided pressure-sensitive adhesive tape of the present invention is to prevent cohesive failure while maintaining the pressure-sensitive adhesive properties. When cohesive failure of the pressure-sensitive adhesive layer occurs, for example, when the double-sided pressure-sensitive adhesive tape is bonded to the adherend and then peeled off, the adhesive layer remains on the adherend and adversely affects the removability. Because. In addition, tackifying resin can be used individually or in mixture of 2 or more types.

  Examples of the terpene-based tackifier resin include terpene resins such as α-pinene polymers, β-pinene polymers, and dipentene polymers, and modified terpene resins (phenol-modified, aromatic-modified, hydrogen-modified). And modified terpene resins (for example, terpene phenol resins, styrene modified terpene resins, aromatic modified terpene resins, hydrogenated terpene resins, etc.) and the like.

  Examples of the phenolic tackifying resin include condensates of various phenols (eg, phenol, m-cresol, 3,5-xylenol, p-alkylphenol, resorcin, etc.) and formaldehyde (eg, alkylphenolic resin, xyleneformaldehyde). Rosin (unmodified rosin, modified resin), resole obtained by addition reaction of the phenols and formaldehyde with an alkali catalyst, novolak obtained by condensation reaction of the phenols and formaldehyde with an acid catalyst, and the like. And rosin-modified phenolic resins obtained by thermal polymerization by adding phenol to an rosin or various rosin derivatives using an acid catalyst.

  Examples of the rosin-based tackifying resin include unmodified rosin (raw rosin) such as gum rosin, wood rosin and tall oil rosin, and modified products obtained by modifying these unmodified rosins by hydrogenation, disproportionation, polymerization, or the like. In addition to rosin (hydrogenated rosin, disproportionated rosin, polymerized rosin, and other chemically modified rosins), various rosin derivatives and the like can be mentioned. Examples of the rosin derivative include rosin ester compounds obtained by esterifying unmodified rosin with alcohols, and modified rosins obtained by esterifying modified rosins such as hydrogenated rosin, disproportionated rosin, and polymerized rosin with alcohols. Ester compounds such as rosin esters; Unmodified rosin and modified rosins (hydrogenated rosin, disproportionated rosin, polymerized rosin, etc.) modified with unsaturated fatty acids; Unsaturated fatty acid modified rosins; Rosin esters with unsaturated fatty acids Unmodified rosin, modified rosin (hydrogenated rosin, disproportionated rosin, polymerized rosin, etc.), unsaturated fatty acid modified rosins and unsaturated fatty acid modified rosin esters Reduced rosin alcohols; unmodified rosin, modified rosin and various rosin derivatives Rosins and the like (in particular, rosin esters) and the like metal salts of.

  Examples of the petroleum-based tackifier resins include aromatic petroleum resins, aliphatic petroleum resins, alicyclic petroleum resins (aliphatic cyclic petroleum resins), aliphatic / aromatic petroleum resins, aliphatic Known petroleum resins such as alicyclic petroleum resins, hydrogenated petroleum resins, coumarone resins and coumarone indene resins can be used. Specifically, as the aromatic petroleum resin, for example, a vinyl group-containing aromatic hydrocarbon having 8 to 10 carbon atoms (styrene, o-vinyltoluene, m-vinyltoluene, p-vinyltoluene, α -Methyl styrene, β-methyl styrene, indene, methyl indene, etc.) are used alone or in combination of two or more. As the aromatic petroleum resin, an aromatic petroleum resin (so-called “C9 petroleum resin”) obtained from a fraction such as vinyltoluene or indene (so-called “C9 petroleum fraction”) can be preferably used. Examples of the aliphatic petroleum resin include olefins having 4 to 5 carbon atoms and dienes [olefins such as butene-1, isobutylene and pentene-1; dienes such as butadiene, piperylene (1,3-pentadiene) and isoprene. Etc.] are used alone or in combination of two or more. As the aliphatic petroleum resin, an aliphatic petroleum resin (so-called “C4 petroleum resin”) obtained from a fraction such as butadiene, piperylene or isoprene (so-called “C4 petroleum fraction” or “C5 petroleum fraction”). And “C5-based petroleum resin” and the like can be suitably used. As the alicyclic petroleum resin, for example, an alicyclic hydrocarbon obtained by cyclizing and dimerizing an aliphatic petroleum resin (so-called “C4 petroleum resin”, “C5 petroleum resin”, etc.) is used. Polymers, cyclic diene compounds (cyclopentadiene, dicyclopentadiene, ethylidene norbornene, dipentene, ethylidenebicycloheptene, vinylcycloheptene, tetrahydroindene, vinylcyclohexene, limonene, etc.) or hydrogenated products thereof, Aromatic hydrocarbon resins, and alicyclic hydrocarbon resins obtained by hydrogenating the aromatic rings of the following aliphatic / aromatic petroleum resins. Examples of the aliphatic / aromatic petroleum resins include styrene-olefin copolymers. As the aliphatic / aromatic petroleum resin, so-called “C5 / C9 copolymer petroleum resin” or the like can be used.

  Examples of the tackifier resin include commercial products such as those manufactured by Sumitomo Bakelite Co., Ltd., trade names “Sumilite Resin PR-12603”, Arakawa Chemical Industries, Ltd., and trade names “Pencel D125”.

  Among these, as the tackifying resin, a rosin-based tackifying resin is preferable, and rosin esters are particularly preferable from the viewpoint of achieving both the adhesive property on the adhesive surface and the removability at a higher level.

  In addition, a tackifying resin having a softening point of 80 to 180 ° C. is preferable, and a softening point of 85 to 160 ° C. is particularly preferable from the viewpoint of making the adhesive property and removability on the adhesive surface compatible at a higher level. A tackifying resin is more preferred. In particular, a tackifying resin having a softening point of less than 130 ° C. (for example, a range of more than 90 ° C. and less than 130 ° C.) is preferable. Therefore, a polymerized rosin ester having a softening point of less than 130 ° C. is more preferable.

  The softening point of the tackifying resin is defined as a value measured by a ring and ball method (for example, the ring and ball method defined in JIS K 5902).

  The content of the tackifying resin in the pressure-sensitive adhesive composition is not particularly limited, but is preferably 5 to 50 parts by weight with respect to 100 parts by weight of the acrylic polymer, from the viewpoint of achieving both adhesive properties and removability. More preferably, it is 10 to 45 parts by weight.

  In addition to the acrylic polymer, the crosslinking agent, and the tackifying resin, the pressure-sensitive adhesive composition forming the surface pressure-sensitive adhesive layer may contain an additive. Examples of such additives include plasticizers, fillers, antioxidants, antioxidants, colorants (such as pigments and dyes such as carbon black), and crosslinking accelerators (crosslinking aids).

  The pressure-sensitive adhesive composition can be obtained, for example, by mixing an acrylic polymer, a crosslinking agent, and a tackifying resin. As a typical example, a composition containing an acrylic polymer obtained by solution polymerization of a composition containing a (meth) acrylic acid alkyl ester having a linear or branched alkyl group having 4 to 9 carbon atoms ( For example, a composition comprising an acrylic polymer and a solvent) may be mixed with a crosslinking agent and a tackifying resin.

  Although the formation method of the adhesive layer of the surface layer of the double-sided adhesive tape of this invention is not restrict | limited, For example, the method of apply | coating and forming the said adhesive composition on a predetermined | prescribed surface is mentioned. In the formation method, heating, drying, active energy ray irradiation (for example, ultraviolet irradiation) or the like may be performed as necessary.

  The gel fraction of the pressure-sensitive adhesive layer on the surface of the double-sided pressure-sensitive adhesive tape of the present invention (particularly the gel fraction of the pressure-sensitive adhesive layer on the surface of the reinforcing layer side) is a point where the adhesive properties and removability are compatible at a high level. It is preferably 10 to 60% by weight, more preferably 10 to 50% by weight.

  The gel fraction can be determined as an ethyl acetate insoluble matter. Specifically, the weight fraction of the insoluble matter after soaking the adhesive layer in ethyl acetate at 23 ° C. for 7 days with respect to the pre-immersion sample. It is determined as a rate (unit: weight%).

Specifically, it is a value calculated by the following “Method for measuring gel fraction”.
(Measurement method of gel fraction)
From the double-sided pressure-sensitive adhesive sheet of the present invention, a surface pressure-sensitive adhesive layer for obtaining the gel fraction: about 0.1 g was collected, and a porous tetrafluoroethylene sheet having an average pore diameter of 0.2 μm (trade name “NTF1122”, Nitto Denko Corporation) After wrapping in (manufactured), it is bound with a kite string, the weight at that time is measured, and this weight is taken as the weight before immersion. The weight before immersion is the total weight of the pressure-sensitive adhesive layer, the tetrafluoroethylene sheet, and the kite string. In addition, the total weight of the tetrafluoroethylene sheet and the kite string is also measured, and this weight is defined as the wrapping weight.
Next, a pressure-sensitive adhesive layer wrapped with a tetrafluoroethylene sheet and bound with a kite string (referred to as “sample”) is placed in a 50 ml container filled with ethyl acetate and allowed to stand at 23 ° C. for 7 days. Then, the sample (after ethyl acetate treatment) is taken out from the container, transferred to an aluminum cup, dried in a dryer at 130 ° C. for 2 hours to remove ethyl acetate, the weight is measured, and the weight is immersed. After weight.
Then, the gel fraction is calculated from the following formula.
Gel fraction (% by weight) = ((A−B) / (C−B)) × 100
(In the above formula, A is the weight after immersion, B is the weight of the bag, and C is the weight before immersion.)

  The gel fraction can be controlled by, for example, the composition of monomer components constituting the acrylic polymer in the pressure-sensitive adhesive composition, the weight average molecular weight of the acrylic polymer, the ratio of the crosslinking agent, and the like.

  In the double-sided pressure-sensitive adhesive sheet of the present invention, the pressure-sensitive adhesive layer on the surface of the foam layer side is not particularly limited. For example, a pressure-sensitive adhesive layer formed using a known and common pressure-sensitive adhesive (pressure-sensitive adhesive) as a main component is used. Can be used. Such an adhesive is not particularly limited, and examples thereof include acrylic adhesives, rubber adhesives, vinyl alkyl ether adhesives, silicone adhesives, polyester adhesives, polyamide adhesives, and urethane adhesives. Well-known adhesives, such as an adhesive, a fluorine adhesive, and an epoxy adhesive, are mentioned. These pressure-sensitive adhesives can be used alone or in combination of two or more. The pressure-sensitive adhesive may be any type of pressure-sensitive adhesive. For example, an emulsion-type pressure-sensitive adhesive, a solvent-type pressure-sensitive adhesive, a hot-melt-type pressure-sensitive adhesive (hot-melt-type pressure-sensitive adhesive), an active energy ray A curable adhesive (in particular, an ultraviolet curable adhesive) can be used. Furthermore, an appropriate additive may be contained in the pressure-sensitive adhesive layer on the surface layer on the foam layer side.

  The pressure-sensitive adhesive layer on the surface of the foam layer may be a pressure-sensitive adhesive layer having the same or substantially the same composition as the pressure-sensitive adhesive layer on the surface of the reinforcing layer. From the viewpoint of productivity of the pressure-sensitive adhesive tape, it is preferable that the pressure-sensitive adhesive layer on the foam layer side and the pressure-sensitive adhesive layer on the reinforcing layer side have the same or substantially the same composition.

  The thickness of the pressure-sensitive adhesive layer on the surface of one side of the double-sided pressure-sensitive adhesive sheet of the present invention is not particularly limited as long as the total thickness of the double-sided pressure-sensitive adhesive tape does not exceed 500 μm, but from the viewpoint of ensuring sufficient adhesiveness and removability. 2 to 140 [mu] m is preferable, more preferably 20 to 100 [mu] m, and still more preferably 20 to 75 [mu] m. In the double-sided pressure-sensitive adhesive sheet of the present invention, the thicknesses of the pressure-sensitive adhesive layers on the surface layers on both sides may be the same or different. Further, the surface pressure-sensitive adhesive layer may have either a single layer or a multilayer.

  For example, it has a pressure-sensitive adhesive layer on one side of the foam layer, a reinforcing layer on the other side of the foam layer via the pressure-sensitive adhesive layer, and further has a pressure-sensitive adhesive layer on the reinforcing layer ( In the double-sided PSA sheet of the pressure-sensitive adhesive layer / foam layer / pressure-sensitive adhesive layer / reinforcing layer / pressure-sensitive adhesive layer, FIG. 1), the thickness of the pressure-sensitive adhesive layer on the reinforcing layer side is preferably 2 to 140 μm, more preferably. Is 20 to 100 μm, and on the other hand, the thickness of the pressure-sensitive adhesive layer on the foam layer side is preferably 2 to 140 μm, more preferably 20 to 100 μm.

(Other layers)
The double-sided pressure-sensitive adhesive tape of the present invention may have other layers (for example, an intermediate layer, an undercoat layer, etc.) as long as the effects of the present invention are not impaired. In addition, an adhesive layer for fixing the reinforcing layer and the foam layer between the reinforcing layer and the foam layer (for example, a known adhesive layer or the same adhesive layer as the above-mentioned surface adhesive layer). You may have. In addition, since the total thickness of the double-sided adhesive tape of this invention says the thickness from one adhesive surface to the other adhesive surface, the thickness of the other layer is contained in the total thickness of a double-sided adhesive tape.

(Release liner)
The pressure-sensitive adhesive surface of the double-sided pressure-sensitive adhesive tape of the present invention may be protected by a release liner (separator) until use. Each pressure-sensitive adhesive surface of the double-sided pressure-sensitive adhesive tape may be protected by two release liners, or may be wound in a roll shape with one release liner whose both surfaces are release surfaces. It may be protected. The release liner is used as a protective material for the adhesive surface, and is peeled off when it is attached to an adherend. In the present invention, when a release liner is used, the thickness of the release liner is not included in the total thickness of the double-sided pressure-sensitive adhesive tape.

  As such a release liner, a conventional release paper or the like can be used, and is not particularly limited. For example, a substrate having a release treatment layer, a low-adhesive substrate made of a fluoropolymer, and a low adhesion made of a nonpolar polymer. Can be used. As a base material which has the said peeling process layer, the plastic film, paper, etc. which were surface-treated with peeling processing agents, such as a silicone type, a long-chain alkyl type, a fluorine type, and molybdenum sulfide, are mentioned, for example. Examples of the fluorine-based polymer in the low-adhesive substrate made of a fluorine-based polymer include polytetrafluoroethylene, polychlorotrifluoroethylene, polyvinyl fluoride, polyvinylidene fluoride, tetrafluoroethylene / hexafluoropropylene copolymer, chloro Examples include fluoroethylene / vinylidene fluoride copolymers. Examples of the nonpolar polymer of the low-adhesive substrate made of a nonpolar polymer include olefin resins (for example, polyethylene and polypropylene). The release liner can be formed by a known or common method. Further, the thickness of the release liner is not particularly limited.

(Double-sided adhesive tape)
In the double-sided pressure-sensitive adhesive tape of the present invention, at least one side of the pressure-sensitive adhesive surface (especially the pressure-sensitive adhesive surface on the reinforcing layer side) preferably has no adhesive residue in the following removability evaluation test.
Removability evaluation test: A double-sided pressure-sensitive adhesive tape (width 10 mm × length 100 mm) was attached to a glass plate (manufactured by Matsunami Glass Industry Co., Ltd., trade name “Slide Glass White Edge Polish No. 1”), 23 ° C., 50 After leaving for 30 minutes in an atmosphere of% RH, the presence or absence of adhesive residue on the glass plate surface when the double-sided PSA sheet was peeled off from the glass plate under the conditions of a peeling angle of 180 ° and a tensile speed of 5 m / min. Is visually evaluated.

  Such an adhesive surface can suppress adhesive residue and contamination on the adherend when it is peeled off after being attached to the adherend.

  Generally, the behavior of the double-sided pressure-sensitive adhesive tape when peeled from the adherend (re-peeling behavior) is related to the high-speed peeling phenomenon, but this high-speed peeling (high-speed peeling; In the case of 5 m / min or 10 m / min), removability is required. In the double-sided pressure-sensitive adhesive tape of the present invention, in particular, it must be peeled in the state of interfacial peeling that peels at the interface between the adherend and the double-sided pressure-sensitive adhesive tape, and further, the interlayer between the foam layer and the pressure-sensitive adhesive layer It is necessary to suppress delamination, damage to the foam layer, interlayer breakage due to tearing of the foam layer, and the like.

  For this reason, 180 ° peel adhesive strength (23 ° C., 50% RH, tensile speed 5 m / min) to the adherend on the adhesive surface (especially the adhesive surface on the reinforcing layer side) of at least one side of the double-sided adhesive tape of the present invention. The peeling condition at a peeling angle of 180 ° (degrees) is preferably 15 N / 10 mm or less. Occurrence of problems such as interfacial delamination at the interface between the adherend and double-sided adhesive tape, delamination between the foam layer and the adhesive layer, damage to the foam layer, and interlaminar fracture due to tearing of the foam layer It is because it can suppress effectively and can exhibit removability. The 180 ° peel adhesive force is peeled off at a high speed peeling force [high speed peeling conditions (23 ° C., 50% RH, tensile speed: 5 m / min, peeling angle: 180 ° (degrees)) from the adherend. May be referred to as “adhesive strength when measured by Moreover, it is more preferable that the high-speed peeling force of the adhesive surface is 10 N / 10 mm or less (for example, 2 to 10 N / 10 mm) from the viewpoint of obtaining better removability.

  In the double-sided pressure-sensitive adhesive tape of the present invention, for example, 180 ° peel adhesive strength (23 ° C., 50% RH, tensile speed 5 m / min, peeling angle 180 °) of the adhesive surface on at least one side (particularly the adhesive surface on the reinforcing layer side). The peeling condition of the glass plate) is 15 N / 10 mm or less, so there may be cases where interfacial peeling cannot be performed at the interface between the glass plate and the double-sided adhesive tape, or delamination between the foam layer and the adhesive layer. There is no breakage of the foam layer, interlaminar fracture due to tearing of the foam layer, etc., and good removability is exhibited with respect to the glass plate as the adherend.

  In addition, the adhesive surface (especially the adhesive surface on the reinforcing layer side) of at least one side of the double-sided adhesive tape of the present invention is a metal plate such as a SUS plate or an Al plate (aluminum plate), PET, in addition to the above glass plate. It also has a high-speed peeling force of 15 N / 10 mm or less for adherends such as films, plastic films such as PC plates (polycarbonate plates), plastic plates, and composite materials thereof. For this reason, good removability is exhibited also to these adherends.

  Since the pressure-sensitive adhesive surface (particularly the pressure-sensitive adhesive surface on the reinforcing layer side) of at least one side of the double-sided pressure-sensitive adhesive tape of the present invention has the above configuration, it has excellent removability.

  In the double-sided pressure-sensitive adhesive tape of the present invention, at least the adhesive surface on the reinforcing layer side has no adhesive residue in the removability evaluation test, and 180 ° peel adhesive strength (23 ° C., 50% RH, tensile speed 5 m / min, It is preferable that the peeling condition at a peeling angle of 180 ° (to the glass plate) is 15 N / 10 mm or less. When fixing or sticking a member (part, part) to a desired position (for example, container, casing, product, etc.) through a double-sided pressure-sensitive adhesive tape of the present invention, a reinforcing layer is used from the viewpoint of removability. This is because it is preferable that the adhesive surface on the side is attached to the member and the adhesive surface on the foam layer side is attached to the object.

  The double-sided pressure-sensitive adhesive tape of the present invention has a 180 ° peel adhesive strength (23 ° C., 50% RH, a tensile speed of 5 m / min, a peel angle of 180) on at least one side of the pressure-sensitive adhesive surface (particularly the pressure-sensitive adhesive surface on the reinforcing layer side). The peeling condition at 0 ° (for the glass plate) is 15 N / 10 mm or less, and it is sufficient that no adhesive residue is generated in the re-peelability evaluation test. Therefore, in the double-sided pressure-sensitive adhesive tape of the present invention, the surface pressure-sensitive adhesive layer is not particularly limited as long as these requirements are satisfied, and (meth) acrylic acid having a linear or branched alkyl group having 4 to 9 carbon atoms. It may be a pressure-sensitive adhesive layer other than a pressure-sensitive adhesive layer formed from a pressure-sensitive adhesive composition containing an acrylic polymer comprising an alkyl ester as an essential monomer component, a tackifier resin, and a crosslinking agent.

  In general, the behavior of the double-sided pressure-sensitive adhesive tape that binds to and adheres to the adherend is related to the peeling phenomenon at a low speed. In the case where the speed is 300 mm / min, etc., it is necessary to exhibit sufficient adhesion reliability and to have sufficient adhesive strength so as not to peel from the adherend when the double-sided pressure-sensitive adhesive tape is used. When the peeling force at the time of low-speed peeling from the adherend is 2.5 N / 10 mm or less, there may be a case where sufficient adhesive force cannot be exerted on the adherend.

  For this reason, in the double-sided pressure-sensitive adhesive tape of the present invention, 180 ° peel adhesive strength (23 ° C., 50% RH, tensile speed 300 mm / min, peeling angle 180) on at least one of the pressure-sensitive adhesive surfaces (particularly the pressure-sensitive adhesive surface on the reinforcing layer side). The peeling condition (° (degree)) is preferably 2.5 N / 10 mm or more (for example, 2.5 to 15 N / 10 mm), more preferably 5.0 N / 10 mm or more (for example, 5.0 to 14 N / 10 mm). . The 180 ° peel adhesive strength was measured by peeling at a low peel strength [low speed peel conditions (23 ° C., 50% RH, tensile speed: 300 mm / min, peel angle: 180 ° (degrees))]. May be referred to as [adhesive strength of].

  In the double-sided pressure-sensitive adhesive tape of the present invention, at least one side of the pressure-sensitive adhesive surface (especially the pressure-sensitive adhesive surface on the reinforcing layer side) has the following characteristics: , Monomer composition and weight average molecular weight of acrylic polymer contained in surface adhesive layer; selection of type and amount of crosslinking agent and tackifying resin; adjustment by controlling gel fraction of surface adhesive layer can do.

  In the double-sided pressure-sensitive adhesive tape of the present invention, the compression load is not particularly limited, but compression when compressed by 20% of the initial thickness in terms of impact absorbability, level difference followability, water stoppage, workability, sealability, etc. For example, the load is preferably 0.1 to 300 kPa, and preferably 0.1 to 250 kPa.

The compressive load is defined by the following equation.
Compressive load = (Load when 10 double-sided adhesive tapes are stacked and compressed by a predetermined thickness of 10 mm / min at the initial thickness) / (Area of double-sided adhesive tape)
In addition, the area of a double-sided adhesive tape shall be 30 cm x 30 cm.

  Since the double-sided pressure-sensitive adhesive sheet of the present invention has a foam layer, it can have the compressive load regardless of the material and thickness of the reinforcing layer. For example, even if the double-sided pressure-sensitive adhesive sheet of the present invention has a reinforcing layer made of a hard material as a reinforcing layer (for example, the above-mentioned metal-based sheet or plastic-based sheet), since it has a foam layer at the same time, The compression load can be provided.

  The compression load of the double-sided pressure-sensitive adhesive sheet of the present invention can be adjusted by selecting the thickness and type of the foam layer, the reinforcing layer and the pressure-sensitive adhesive layer, the foaming ratio of the foam layer, the cell structure, and the like.

  When the double-sided pressure-sensitive adhesive tape of the present invention has the above compressive load, the step following ability is good and the sealing function is also improved.

  In the double-sided pressure-sensitive adhesive tape of the present invention, for example, the pressure adhesive force when a polycarbonate plate and an acrylic plate are bonded together with a 2 kg roller 1 reciprocating compressive load is not particularly limited, but it prevents peeling due to stress of the internal material. For example, 30-100N is preferable, Preferably it is 50-80N.

  Such pressure adhesive force can be obtained by adjusting the thickness and type of the foam layer, the reinforcing layer and the pressure-sensitive adhesive layer, the foaming ratio of the foam layer, and the like.

  Moreover, since the double-sided pressure-sensitive adhesive tape of the present invention has a foam layer, variation in the pressure adhesive force for each compression load is small, and a sufficient pressure adhesive force can be ensured even with light pressure bonding. For example, even with a compressive load as small as 500 g, a pressure adhesive force of about 80 to 90% can be ensured with respect to a pressure adhesive force that can secure an adhesive area of 100%.

  For this reason, the double-sided pressure-sensitive adhesive tape of the present invention is excellent in adhesion reliability and is also excellent in workability. Therefore, the double-sided pressure-sensitive adhesive tape of the present invention can be applied to adherends that are difficult to increase the compressive load at the time of application (for example, adherends that are easily broken, soft adherends, adherends having uneven surfaces, etc.). It can use suitably.

  Note that the pressure adhesive strength is a measurement sample obtained by laminating a polycarbonate plate and an acrylic plate with a predetermined compression load using a window frame-shaped double-sided adhesive tape having a width of 40 cm, a length of 60 cm, and a width of 1 mm. Is defined as the maximum stress until the acrylic plate and the polycarbonate plate are separated by pressing the acrylic plate in the thickness direction of the acrylic plate from the inside toward the outside at 10 mm / min.

  Moreover, since the double-sided adhesive tape of this invention has a foam layer, it is excellent in the drop impact characteristic. Also from this fact, the double-sided pressure-sensitive adhesive tape of the present invention has good adhesion reliability. The double-sided pressure-sensitive adhesive tape of the present invention has a high temperature (for example, about 30 to 50 ° C.) even at a low temperature (for example, about −30 to 10 ° C.) from the point that the foam layer relieves stress when absorbing the shock. Even so, it has excellent impact drop characteristics.

  In the double-sided pressure-sensitive adhesive tape of the present invention, the dielectric breakdown voltage (dielectric breakdown strength) is preferably 2 to 40 kV / mm, and preferably 4 to 15 kV / mm.

  Since the double-sided pressure-sensitive adhesive tape of the present invention has the reinforcing layer together with the foam layer, the insulation can be easily controlled by selecting the material of the reinforcing layer. When the double-sided pressure-sensitive adhesive tape of the present invention is used for fixing an electronic component or the like, it is preferable that the double-sided adhesive tape is excellent in insulation.

  The double-sided pressure-sensitive adhesive tape of the present invention can control optical characteristics such as transmittance and reflectance by coloring the foam layer.

  For example, when using a double-sided pressure-sensitive adhesive tape for light-shielding applications, the visible light transmittance is 15% or less (for example, 0 to 15%), more preferably 10% or less (for example, by coloring the foam layer or the reinforcing layer black). 0 to 10%) is preferable. Moreover, when using a double-sided adhesive tape for a light reflection use, visible light reflectance is 20% or more (for example, 20-100%) by white-coloring a foam layer or a reinforcement layer, More preferably, 25% or more ( For example, it is preferably 25 to 100%. Such a double-sided pressure-sensitive adhesive tape with controlled optical characteristics can be used as an optical member such as a light diffusing member, a scattering element member, or a condensing member.

  The double-sided pressure-sensitive adhesive tape of the present invention can be produced using a known or common method. For example, (i) the pressure-sensitive adhesive composition is used to form a pressure-sensitive adhesive layer on a predetermined surface such as a foam layer or a reinforcing layer, and (ii) the foam layer or the reinforcing layer is formed on the pressure-sensitive adhesive layer. Etc., or by making the pressure-sensitive adhesive layer the outermost layer. As a specific method used when forming the pressure-sensitive adhesive layer on a predetermined surface such as a foam layer or a reinforcing layer using the pressure-sensitive adhesive composition (i), for example, a foam layer or Applying the pressure-sensitive adhesive composition on a predetermined surface such as a reinforcing layer and performing heating or drying as necessary to form a pressure-sensitive adhesive layer (direct copying method), or on an appropriate support surface Apply the pressure-sensitive adhesive composition to the surface of the release liner (for example, on the release-treated surface of the release liner, etc.), heat or dry as necessary to form a pressure-sensitive adhesive layer, and then apply the appropriate support. A method (transfer method) for transferring a pressure-sensitive adhesive layer on the surface of the body (for example, a pressure-sensitive adhesive layer on the surface subjected to the release treatment of the release liner) onto a predetermined surface such as a foam layer or a reinforcing layer. Can be mentioned.

  Specifically, the double-sided pressure-sensitive adhesive tape of FIG. 1 (double-sided pressure-sensitive adhesive tape having a laminated structure of pressure-sensitive adhesive layer / foam layer / pressure-sensitive adhesive layer / reinforcing layer / pressure-sensitive adhesive layer) is (i) one side of the foam layer. An adhesive layer is formed on the adhesive layer by a direct copy method or a transfer method, and a pressure-sensitive adhesive layer is formed on one side of the reinforcement layer by a direct copy method or a transfer method. By providing a foam layer on the agent layer, etc., a laminated structure of foam layer / adhesive layer / reinforcing layer is obtained, and (ii) the surface on the foam layer side and the surface on the reinforcing layer side of the laminated structure Both can be produced by forming a pressure-sensitive adhesive layer by a direct copy method or a transfer method.

  Since the double-sided pressure-sensitive adhesive tape of the present invention has a foam layer, it is excellent in properties such as impact absorbability, level difference followability, waterstop, workability, and sealability.

  Here, a double-sided pressure-sensitive adhesive tape having a pressure-sensitive adhesive layer on both sides of the foam layer (corresponding to the double-sided pressure-sensitive adhesive tape of the present invention obtained by removing the reinforcing layer, a configuration of pressure-sensitive adhesive layer / foam layer / pressure-sensitive adhesive layer) When the material is fixed to the adherend and then peeled off from the adherend (for example, when reworked or peeled after use), the foam layer may be inferior in strength but may be inferior in strength. There are cases where delamination with the adhesive layer, breakage of the foam layer, interlaminar fracture due to tearing of the foam layer, residual adhesive on the adherend, and the like.

  For example, when the double-sided pressure-sensitive adhesive tape (adhesive layer / foam layer / adhesive layer configuration) is used for the purpose of recovering members (parts, parts) or for easy disassembly, it is foamed when peeled off from the adherend. When interlaminar fracture occurs due to tearing of the body layer, there are aspects that are difficult to use. As a specific example, a member (part, part) is fixed to a desired position of a target object (for example, a container, a casing, a product, etc.) via the double-sided adhesive tape, and the member, the double-sided adhesive tape, And when obtaining the structure of the target object and recovering the member or disassembling the structure after the end of use, if an interlaminar fracture occurs due to the foam layer tearing, the recovery of the member or the dismantling of the structure May be difficult.

  Since the double-sided pressure-sensitive adhesive tape of the present invention has a reinforcing layer together with the foam layer, the strength of the foam layer is supplemented, and the disadvantages of the double-sided pressure-sensitive adhesive tape having the pressure-sensitive adhesive layer on both sides of the foam layer are described. Can be supplemented. When the double-sided pressure-sensitive adhesive tape of the present invention is peeled off from the adherend during rework or after use, the reinforcing layer of the double-sided pressure-sensitive adhesive tape becomes a part to be caught (a part to be grasped and a part to be grasped). For this reason, the double-sided pressure-sensitive adhesive tape of the present invention, even if the total thickness is thin, delamination between the foam layer and the pressure-sensitive adhesive layer, damage to the foam layer, interlaminar fracture due to tearing of the foam layer, It can be easily removed again without causing the adhesive to remain on the adherend.

  The material of the member (part, part) or target object (for example, container, casing, product, etc.) to be adhered is not particularly limited, but is a metal such as stainless steel or aluminum; glass; polycarbonate, poly Examples thereof include plastics (resins) such as methyl methacrylate (PMMA), polypropylene, and polyethylene terephthalate (PET), and composite materials thereof.

  The double-sided pressure-sensitive adhesive tape of the present invention has good removability to various adherends (for example, adherends obtained from metals, plastics, glass, and composite materials thereof). This is because the double-sided pressure-sensitive adhesive tape of the present invention has a reinforcing layer together with the foam layer. The reinforcing layer becomes a portion to be caught (a portion to be grasped and a portion to be grasped) when the double-sided adhesive tape is peeled off from the adherend after reworking or after use.

  As described above, the double-sided pressure-sensitive adhesive tape of the present invention has cutting (punching) processability, re-peelability upon re-attachment, step following ability, sealing performance, water stopping performance, adhesion reliability, workability, optical function, repulsion resistance It can have properties such as property, easy peelability, and insulation. Therefore, the double-sided adhesive tape of the present invention is used for, for example, fixing a lens of a mobile phone, fixing a key module member of a mobile phone, impact material of an electronic device, fixing a decoration panel of a TV, a battery pack protection of a personal computer, a digital video camera. It is extremely useful for applications such as lens waterproofing.

  Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited to these examples.

Example 1
In a reaction vessel equipped with a cooling tube, a nitrogen introduction tube, a thermometer, a dropping funnel, and a stirring device, 69 parts by weight of toluene, 163 parts by weight of ethyl acetate, 80 parts by weight of butyl acrylate, 20 parts by weight of 2-ethylhexyl acrylate, 3 parts by weight of acrylic acid, 5 parts by weight of vinyl acetate, 0.1 part by weight of 2-hydroxyethyl acrylate, 0.2 part by weight of 2,2-azobisisobutyronitrile as an initiator, and 60 ° C. in a nitrogen stream Polymerization was carried out for 6 hours to obtain an acrylic polymer solution.
In this solution, 30 parts by weight of a polymerized rosin ester resin (softening point: 123 ° C.), 100 parts by weight of an acrylic polymer in the solution, an isocyanate-based crosslinking agent (trade name “Coronate L” Nippon Polyurethane Industry ( Co., Ltd.) was mixed with 1.5 parts by weight (in terms of solid content) to prepare an acrylic pressure-sensitive adhesive composition.
This acrylic pressure-sensitive adhesive composition was applied on a silicone-treated release paper having a thickness of 135 μm using a bar coater and dried at 110 ° C. for 3 minutes to form a pressure-sensitive adhesive layer having a thickness of 25 μm.
The pressure-sensitive adhesive layer on one side of a sheet-like foam (trade name “Bora La XL-HN # 03001W Shorikuro”, manufactured by Sekisui Chemical Co., Ltd., thickness: 100 μm, average cell diameter: 163 μm, density: 0.34 g / cc) Is transferred, and a PET base material (non-foamed structure, thickness: 5 μm, trade name “Lumirror # 5AF53”, manufactured by Toray Industries, Inc.) is pasted onto the pressure-sensitive adhesive layer, and a foam / pressure-sensitive adhesive layer / PET base material Next, by transferring the pressure-sensitive adhesive layer to both sides of the laminate, the pressure-sensitive adhesive layer (the pressure-sensitive adhesive layer on the surface of the foam layer) / foam layer / A double-sided pressure-sensitive adhesive tape (total thickness: 180 μm) of pressure-sensitive adhesive layer / reinforcing layer / pressure-sensitive adhesive layer (surface-side pressure-sensitive adhesive layer on the reinforcing layer side) was produced.

(Example 2)
Instead of a PET base material (non-foamed structure, thickness: 5 μm, trade name “Lumirror # 5AF53”, manufactured by Toray Industries, Inc.), a PET base material (non-foamed structure, thickness: 12 μm, trade name “Lumirror S-10 # 12”) Except for using “Toray Industries, Inc.”, the pressure-sensitive adhesive layer (the pressure-sensitive adhesive layer on the surface of the foam layer) / foam layer / pressure-sensitive adhesive layer / reinforcing layer / pressure-sensitive adhesive is the same as in Example 1. A double-sided pressure-sensitive adhesive tape (total thickness: 187 μm) of a layer (surface layer pressure-sensitive adhesive layer on the reinforcing layer side) was produced.

(Example 3)
Use of a foam (trade name “Borara XL-HN # 03001W Shorishiro”, manufactured by Sekisui Chemical Co., Ltd., thickness: 100 μm, average cell diameter: 163 μm, density: 0.34 g / cc) as the foam, PET group Instead of the material (non-foamed structure, thickness: 5 μm, trade name “Lumirror # 5AF53”, manufactured by Toray Industries, Inc.), PET base material (non-foamed structure, thickness: 25 μm, trade name “Lumirror S-10 # 25”, Toray Industries, Inc. Except having used company company), it was carried out similarly to Example 1, and the adhesive layer (adhesive layer of the surface layer by the side of a foam layer) / foam layer / adhesive layer / reinforcement layer / adhesive layer (reinforcement) A double-sided pressure-sensitive adhesive tape (total thickness: 200 μm) of the surface-side pressure-sensitive adhesive layer on the layer side was prepared.

Example 4
Except that the acrylic pressure-sensitive adhesive composition was applied on a silicone-treated release paper having a thickness of 135 μm using a bar coater and dried at 110 ° C. for 3 minutes to form a pressure-sensitive adhesive layer having a thickness of 50 μm. In the same manner as in Example 1, the pressure-sensitive adhesive layer (the pressure-sensitive adhesive layer on the foam layer side) / foam layer / the pressure-sensitive adhesive layer / the reinforcing layer / the pressure-sensitive adhesive layer (the pressure-sensitive adhesive layer on the reinforcing layer side) A double-sided adhesive tape (total thickness: 255 μm) was produced.

(Example 5)
Except that the acrylic pressure-sensitive adhesive composition was applied on a silicone-treated release paper having a thickness of 135 μm using a bar coater and dried at 110 ° C. for 3 minutes to form a pressure-sensitive adhesive layer having a thickness of 50 μm. In the same manner as in Example 2, the pressure-sensitive adhesive layer (the pressure-sensitive adhesive layer on the foam layer side) / foam layer / the pressure-sensitive adhesive layer / the reinforcing layer / the pressure-sensitive adhesive layer (the pressure-sensitive adhesive layer on the reinforcing layer side) A double-sided adhesive tape (total thickness: 262 μm) was produced.

(Comparative Example 1)
A double-sided pressure-sensitive adhesive tape (trade name “No. 57115B”, pressure-sensitive adhesive layer / foam layer / double-sided pressure-sensitive adhesive layer, total thickness: 150 μm) was used.

(Comparative Example 2)
A double-sided pressure-sensitive adhesive tape (trade name “No. 57120B”, double-sided pressure-sensitive adhesive tape of pressure-sensitive adhesive layer / foam layer / pressure-sensitive adhesive layer, total thickness: 200 μm) was used.

(Evaluation)
About double-sided pressure-sensitive adhesive tapes produced in Examples and Comparative Examples, 180 ° peel adhesive strength (high speed peeling conditions, low speed peeling conditions), pressure adhesive strength, drop impact resistance, optical characteristics, waterproof characteristics, compressive load, dielectric breakdown strength, The removability was measured or evaluated.

(180 ° peel adhesion)
A double-sided pressure-sensitive adhesive tape was cut into a size having a width of 10 mm and a length of 100 mm, and a PET film for backing (with a thickness of 25 μm) was bonded to one pressure-sensitive adhesive layer to prepare a measurement sample.
Adhesive surface for measuring the adhesive force is applied to an adherend (stainless steel plate (SUS304BA plate), glass plate (manufactured by Matsunami Glass Industrial Co., Ltd., trade name “Slide Glass White Edge Polish No. 1”)) with 2 kg roller and one reciprocation. Crimped and left in an environment of 23 ° C. × 50% RH for 30 minutes.
After standing, under low-speed peeling conditions [Tensile speed: 300 mm / min, using a universal tensile and compression tester (device name “Tensile and compression testing machine TG-1kN”, manufactured by Minebea Co., Ltd.)] and high-speed peeling conditions [Tension Speed: 5 m / min and 10 m / min, using a high-speed peel tester (manufactured by Tester Sangyo Co., Ltd.)], peeled at a peel angle of 180 °, and measured 180 ° peel adhesive strength. The measurement was performed in an environment of 23 ° C. × 50% RH.
In addition, the measurement is performed by the pressure-sensitive adhesive surface (sometimes referred to as “foam surface”) provided by the surface adhesive layer on the foam layer side and the pressure-sensitive adhesive surface provided by the surface pressure-sensitive adhesive layer on the reinforcing layer side. (Sometimes referred to as “re-peeling surface”).
The measurement results are shown in Table 1 below.

(Compression load)
A test piece was prepared by cutting 10 sheets of double-sided pressure-sensitive adhesive tape into a size of 30 cm × width: 30 cm.
The test piece is placed on a parallel flat plate of a universal tensile compression tester (tensile compression tester, device name “TG-1kN”, manufactured by Minebea Co., Ltd.), 10% of the initial thickness at 10 mm / min, Compressed by 20%, 30%, 40% or 50%, the load at that time was measured, and the compression load at each compression rate was determined from the following formula.
Compressive load [kPa] = (Load when compressed by a predetermined thickness of the initial thickness) / (Area of specimen)

表２において、「ｏｖｅｒｌｏａｄ」は、引張圧縮試験機のロードセルの測定可能限界を超えたことを示す。

In Table 2, “overload” indicates that the measurable limit of the load cell of the tensile compression tester was exceeded.

(Press adhesive strength)
The produced double-sided pressure-sensitive adhesive tape was cut into a window frame shape (frame shape) having a width of 1 mm (width: 40 mm, length: 60 mm) as shown in FIG. 2 to obtain a window frame-shaped double-sided pressure-sensitive adhesive tape.
Using the window frame-shaped double-sided adhesive tape, an acrylic plate (acrylic lens, width: 40 mm, length: 60 mm, thickness: 1 mm) and a polycarbonate plate (PC plate) having a through hole with a diameter of 15 mm in the center ( Weigh: 70 mm, Vertical: 80 mm, Thickness: 2 mm) and a sample for evaluation by pasting them together under pressure and reciprocation conditions of a roller having a predetermined weight (1 kg, 2 kg, 3 kg, 4 kg and 5 kg). (1 kg evaluation sample, 2 kg evaluation sample, 3 kg evaluation sample, 4 kg evaluation sample, and 5 kg evaluation sample) were obtained (see FIGS. 2A and 2B).
Separately from these, an evaluation sample (5 kg evaluation sample) bonded together under the condition of one reciprocation of a 5 kg roller is put into an autoclave, and further subjected to pressure bonding at 5 atm, 50 ° C. for 1 hour. An autoclave evaluation sample) was also obtained. In the autoclave evaluation sample, it is assumed that the adhesive area of the window frame-shaped double-sided pressure-sensitive adhesive tape is 100%.

  The double-sided pressure-sensitive adhesive tape of the example is a pressure-sensitive adhesive surface provided by a pressure-sensitive adhesive layer (foam surface) provided by a surface-sensitive adhesive layer on the foam layer side on a polycarbonate plate, and provided by a surface-sensitive adhesive layer on the reinforcing layer side. (Re-peeling surface) was attached to an acrylic plate.

  2A and 2B are schematic views of a sample for evaluation used in measuring the pressure adhesive force, where FIG. 2A is a top view and FIG. 2B is a cross-sectional view taken along line A-A ′. In FIG. 2, 21 is a polycarbonate plate, 22 is a window frame-shaped double-sided adhesive tape, 23 is an acrylic plate, and 24 is a through hole of the polycarbonate plate.

  Next, these evaluation samples are set in a universal tensile compression tester (device name “Tensile compression tester, TG-1kN” manufactured by Minebea Co., Ltd.), and the round bar is passed through the through hole of the polycarbonate plate. The acrylic plate was pressed with a round bar under the condition of 10 mm / min, and the maximum stress until the acrylic plate and the polycarbonate plate were separated was measured as the pressing adhesive force (see FIG. 3). The measurement was performed at room temperature. The measurement results are shown in Table 3 below.

  FIG. 3 is a schematic cross-sectional view showing a method for measuring the pressing adhesive force. In FIG. 3, 21 is a polycarbonate plate, 22 is a window frame-shaped double-sided adhesive tape, 23 is an acrylic plate, 31 is a round bar, and 32 is a support base. As shown in FIG. 3, the evaluation sample is fixed to a support base 32 of a tensile and compression tester, and the acrylic plate 23 of the evaluation sample is pressed by a round bar 31 that has passed through the through hole of the polycarbonate plate 21. In the evaluation sample, the polycarbonate plate 21 was loaded when the acrylic plate was pressed, and was not bent or damaged.

(Drop impact resistance)
The produced double-sided adhesive tape was cut into a window frame shape (frame shape) (width: 40 mm, length: 60 mm) having a width of 1 mm to obtain a window frame-like double-sided adhesive tape.
Using the window frame-shaped double-sided adhesive tape, an acrylic plate (acrylic lens, width: 40 mm, length: 60 mm, thickness: 1 mm) and a polycarbonate plate (PC plate) (width: 70 mm, length: 80 mm, thickness: 2 mm) was bonded together by pressure bonding under the condition of 1 reciprocation of a 2 kg roller to obtain a sample for evaluation (see FIGS. 4A and 4B).
The double-sided pressure-sensitive adhesive tape of the example is a pressure-sensitive adhesive surface provided by a pressure-sensitive adhesive layer (foam surface) provided by a surface-sensitive adhesive layer on the foam layer side on a polycarbonate plate, and provided by a surface-sensitive adhesive layer on the reinforcing layer side. (Re-peeling surface) was attached to an acrylic plate.
Next, after attaching a weight to the sample for evaluation to make the total weight 110 g, the sample for evaluation was freely dropped onto a concrete plate from a height of 1.2 m, and the impact resistance against dropping was evaluated. Evaluation of the drop impact resistance characteristics is as follows. First, 18 times of free fall at room temperature (23 ° C.), and then 18 hours of free fall at room temperature, both held 18 times, even lower temperature (−5 ° C.) This was done by allowing it to fall freely 60 times below.
Evaluation Criteria Good: Acrylic plate was not cracked and held the acrylic plate for both “18 free drops at normal temperature” and “60 free drops at low temperature”. "Acrylic plate cracked due to free fall at normal temperature" or "A free fall at normal temperature did not cause cracking of the acrylic plate, but held the acrylic plate, but free under low temperature Acrylic plate cracked when dropped. ''

  4A and 4B are schematic views of a sample for evaluation used for evaluating the drop impact resistance characteristics. FIG. 4A is a top view, and FIG. 4B is a B-B ′ sectional view. In FIG. 4, 41 is a polycarbonate plate, 42 is a window frame-shaped double-sided adhesive tape, and 43 is an acrylic plate (acrylic lens).

(optical properties)
Visible light transmittance is irradiated from one side of the double-sided pressure-sensitive adhesive tape to the other side using a spectrophotometer (device name “U-4100 type spectrophotometer”, manufactured by Hitachi High-Technologies Corporation). This was determined by measuring the intensity of the transmitted light having a wavelength of 550 nm.

(Waterproof characteristics)
The produced adhesive tape was cut into a window frame shape (frame shape) having a width of 1 mm (width: 60 mm, length: 40 mm) to obtain a window frame-shaped double-sided adhesive tape.
Next, the window frame-shaped double-sided adhesive tape is bonded to four acrylic plates (acrylic lens, width: 60 mm, vertical: 40 mm, thickness: 1 mm), and then the window frame-shaped double-sided as shown in FIG. By pressing four acrylic plates with adhesive tape on a polycarbonate plate (PC plate) with two step tapes (width: 5 mm) under the condition of one reciprocating 2 kg roller, Samples for evaluation with respect to the thickness (10 μm, 20 μm, 30 μm, 50 μm, 70 μm, and 100 μm) were obtained (see FIG. 5).
The step tape is affixed for the purpose of providing irregularities on the polycarbonate plate, and is used to obtain the desired irregularity height.
In addition, in the same procedure as above, four acrylic plates with window frame-like double-sided adhesive tape attached are replaced with 2 kg of polycarbonate plate (two step tapes are not attached and the surface is smooth). A sample for evaluation having a concavo-convex height of 0 μm (no step) was obtained by pressure bonding under the condition of one reciprocation of the roller.
In addition, since the nonwoven fabric (width: 35 mm, length: 55 mm, thickness: 0.05 mm) has the property of discoloring when it absorbs water, for visual evaluation when immersed in the interior, the acrylic plate and the polycarbonate plate I put it in between. The nonwoven fabric has no influence on the waterproof property evaluation test.

  The double-sided pressure-sensitive adhesive tapes of the examples are provided with a pressure-sensitive adhesive layer (foam surface) provided by the surface-side pressure-sensitive adhesive layer on the foam layer side on a polycarbonate plate and provided by the surface-side pressure-sensitive adhesive layer on the reinforcing layer side. The adhesive surface (removable surface) was affixed to the acrylic board.

The waterproof evaluation test is based on the IPX7 standard (JIS C 0920 / IEC 60529), and samples for evaluation for each uneven height are placed in a water tank with a depth of 1 m for 30 minutes in a standard state (temperature: 23 ° C., humidity: 50%). It was done by submerging and checking the presence or absence of water in the interior.
In addition, the evaluation test of the waterproof characteristic was performed after aging the sample for evaluation with respect to each unevenness height in a standard state (temperature: 23 ° C., humidity: 50%) for 30 minutes.

  For evaluation, prepare two samples for evaluation (see FIGS. 5 (a) and 5 (b)) to which four acrylic plates are attached, and observe the presence / absence of water immersion in eight samples. It went by. The evaluation results are shown in Table 6. In Table 6, the numerical values in the table indicate the number of samples in which internal water immersion was not observed in the waterproof test and the evaluation was “good waterproof”. For example, when the number in the table is 8, it indicates that all the samples can be evaluated as having good waterproof properties, and when the number in the table is 7, 7 samples in 8 samples indicate that the waterproof properties are good. Indicates that the evaluation was successful. When the number in the table is 0, it indicates that water immersion was confirmed in all samples.

  FIG. 5 is a schematic diagram of a sample for evaluation used when evaluating waterproof properties, (a) is a top view, and (b) is an end view of a C-C ′ cut portion. In FIG. 5, 51 is a polycarbonate plate, 52 is a step tape, 53 is a window frame-shaped double-sided adhesive tape, 54 is an acrylic plate (acrylic lens), and 55 is a non-woven fabric.

(Dielectric breakdown voltage)
Dielectric breakdown voltage (dielectric breakdown strength) is determined by sandwiching a double-sided adhesive tape between two stainless steel spherical electrodes (500 g) with a diameter of 125 mm, pressurizing at a pressure increase rate of 1.0 kv / s, and reading the maximum value until conduction. (Based on JIS C2107). The maximum value was taken as the dielectric breakdown voltage.

(Removability evaluation test)
A PET film (trade name “Lumirror S-10 # 25”, manufactured by Toray Industries, Inc.) was lined on one adhesive surface of the double-sided adhesive sheet, and a tape piece 10 mm wide × 100 mm long was cut out.
Next, the other adhesive surface was pasted (crimped) on a glass plate (Matsunami Glass Industry Co., Ltd., trade name “Slide Glass White Edge No. 1”) by reciprocating a 2 kg roller, and this was used as an evaluation sample. It was.
After leaving the sample for evaluation in an atmosphere of 23 ° C. and 50% RH for 30 minutes, using a high-speed peel tester (manufactured by Tester Sangyo Co., Ltd.), at a peel angle of 180 ° and a tensile speed of 5 m / min, The tape piece was peeled off from the glass plate. After peeling off the tape piece, visually observe the surface of the glass plate. If there is no glue residue, “○” (good removability), and if there is glue residue “×” (poor removability) Table 8 shows the results.

1 Double-sided adhesive tape 11a Adhesive layer 11b Adhesive layer 12 Adhesive layer 13 Foam layer 14 Reinforcement layer a Distance (distance in the thickness direction)
21 Polycarbonate plate 22 Window frame-like double-sided adhesive tape 23 Acrylic plate 24 Polycarbonate plate through hole 31 Round bar 32 Support base 41 Polycarbonate plate 42 Window frame-like double-sided adhesive tape
43 Acrylic board (acrylic lens)
51 Polycarbonate plate 52 Step tape 53 Window frame-shaped double-sided adhesive tape 54 Acrylic plate (acrylic lens)
55 Nonwoven fabric

Claims (4)

The total thickness is 500 μm or less, the foam layer, the reinforcing layer having a thickness of 4 to 25 μm, and the pressure-sensitive adhesive layer as both surface layers, and the pressure-sensitive adhesive layer on the surface layer on at least one side have a carbon number (Meth) acrylic acid alkyl ester having 4 to 9 linear or branched alkyl groups, a carboxyl group-containing monomer, and an acrylic system comprising a hydroxyl group-containing monomer as essential monomer components Formed from a pressure-sensitive adhesive composition containing a polymer, a tackifying resin, and a crosslinking agent,
In the acrylic polymer, the proportion of (meth) acrylic acid alkyl ester having a linear or branched alkyl group having 4 to 9 carbon atoms, carboxyl group-containing monomer, and hydroxyl group-containing monomer is acrylic. 80 to 99.9% by weight of a (meth) acrylic acid alkyl ester having a linear or branched alkyl group having 4 to 9 carbon atoms, based on the total amount of monomer components constituting the polymer, A double-sided pressure-sensitive adhesive tape for re-peeling comprising 0.1 to 10% by weight of a monomer and 0.01 to 5% by weight of a hydroxyl group-containing monomer.   The double-sided pressure-sensitive adhesive tape for re-peeling according to claim 1, wherein the pressure-sensitive adhesive composition contains 5 to 50 parts by weight of a tackifying resin and 0.001 to 10 parts by weight of a crosslinking agent with respect to 100 parts by weight of an acrylic polymer. .   The crosslinking agent is an isocyanate-based crosslinking agent, and the acrylic polymer has a (meth) acrylic acid alkyl ester having a linear or branched alkyl group having 4 to 9 carbon atoms, a carboxyl group-containing monomer, and The double-sided pressure-sensitive adhesive tape for re-peeling according to claim 1 or 2, which is an acrylic polymer comprising a hydroxyl group-containing monomer as an essential monomer component.   2. The 180 ° peel adhesive strength (23 ° C., 50% RH, tensile speed of 5 m / min, peeling condition of 180 ° peel angle, glass plate) of the adhesive surface on at least one side is 15 N / 10 mm or less. The double-sided pressure-sensitive adhesive tape for re-peeling according to any one of -3.

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