JP2011122166A - Double-faced adhesive tape - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a double-faced adhesive tape which is thin and excellent in waterproofness (water cut-off property), and to provide a double-faced adhesive tape which is also excellent in processability. <P>SOLUTION: In the double-faced adhesive tape, acrylic adhesive layers containing an acrylic polymer as a main component are arranged on both sides of a foam substrate. The acrylic polymer includes a 1-20C alkyl ester of (meth)acrylic acid as a main monomer component in an amount of ≥60 wt.% based on the total amount of monomer components. The total thickness of the double-faced adhesive tape is ≤200 μm. The double-faced adhesive tape preferably has a tensile strength of 0.5-20 MPa. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a double-sided pressure-sensitive adhesive tape that is a thin film and has excellent waterproof properties.

  Conventionally, a double-sided pressure-sensitive adhesive tape with a base material (double-sided pressure-sensitive adhesive tape) provided with a pressure-sensitive adhesive layer (pressure-sensitive adhesive layer) on both sides of the base material has been used in various fields for various purposes such as bonding and fixing. It has been. For example, a base material using a non-woven fabric (Patent Document 1), a paper base material, and a plastic film base material are known.

  In recent years, a waterproof function has been required for cellular phone applications, and therefore, a waterproof (waterproof) function has also been required for a double-sided adhesive tape with a base material for fixing components in such applications. However, when using non-woven fabric or paper as the base material, these materials are impregnated with water, causing problems in terms of waterproofness, and using a plastic film as the base material. However, due to the rigidity of the plastic film, the followability to unevenness (step followability) deteriorates, and it is difficult to obtain good waterproof properties, for example, the stepped portion is lifted.

  Furthermore, in recent years, the double-sided pressure-sensitive adhesive tape with a base material has been required to have a thin film from the viewpoint of lightening, downsizing, and thinning of the product, and it is required to have good workability even if it is thin. ing.

JP 2001-152111 A

Accordingly, an object of the present invention is to provide a double-sided pressure-sensitive adhesive tape that is a thin film and is excellent in waterproofness (waterproofness).
Another object of the present invention is to provide a double-sided pressure-sensitive adhesive tape that is also excellent in processability.

  As a result of intensive studies to solve the above-mentioned problems, the present inventor found that a double-sided pressure-sensitive adhesive tape with a base material uses a foam base material as the base material, and a total thickness of 250 μm or less is good even for a thin film. It has been found that waterproofness can be obtained. Further, the inventors have found that good workability can be obtained if the tensile strength is within a specific range, and the present invention has been completed.

That is, in the present invention, an acrylic pressure-sensitive adhesive layer mainly composed of an acrylic polymer is provided on both surfaces of a foam base material, and the acrylic polymer contains (meth) acrylic acid C _1-20 alkyl ester. A double-sided polymer characterized in that the main component of the monomer is a (meth) acrylic acid C _1-20 alkyl ester ratio of 60% by weight or more based on the total amount of the monomer components, and the total thickness is 200 μm or less. Provide adhesive tape.

  Furthermore, this invention provides the said double-sided adhesive tape whose tensile strength is 0.5-20.0 MPa.

  Furthermore, this invention provides the said double-sided adhesive tape whose elongation is 100 to 600%.

  Furthermore, this invention provides the said double-sided adhesive tape whose total thickness of the adhesive layer of both sides is 10-170 micrometers.

  Furthermore, this invention provides the said double-sided adhesive tape whose 30% compression load is 5-200 kPa.

  Furthermore, this invention provides the said double-sided adhesive tape whose press adhesive force is 30-200N.

  Furthermore, the present invention provides the above double-sided pressure-sensitive adhesive tape, wherein the foam base material is a halogen-free foam base material that does not intentionally contain a halogen compound.

  Furthermore, this invention provides the said double-sided adhesive tape whose chlorine gas generation amount is 50 microgram / g or less.

  Furthermore, this invention provides the said double-sided adhesive tape in which the foam base material is colored black.

  Furthermore, this invention provides the said double-sided adhesive tape whose visible light transmittance | permeability is 15% or less.

  Furthermore, this invention provides the said double-sided adhesive tape in which the foam base material is colored white.

  Furthermore, this invention provides the said double-sided adhesive tape whose visible light reflectance is 20% or more.

  Furthermore, this invention provides the said double-sided adhesive tape used for an optical member.

  Furthermore, this invention provides the said double-sided adhesive tape used for a waterproof use.

  Furthermore, this invention provides the said double-sided adhesive tape used with respect to the adherend which has an uneven | corrugated shape or a curved surface part.

  According to the double-sided pressure-sensitive adhesive tape of the present invention, since it has the above-described configuration, it is a thin film and is excellent in waterproofness (waterproofness). Moreover, when tensile strength is 0.5-20.0 MPa, it is excellent also in workability.

It is the schematic of the sample for evaluation used when measuring press adhesive force, (a) is a top view, (b) is A-A 'sectional drawing. It is a schematic sectional drawing which shows the measuring method of press adhesive force. It is the schematic of the sample for evaluation used when measuring a drop impact-proof characteristic, (a) is a top view, (b) is B-B 'sectional drawing. It is a schematic sectional drawing of the sample for evaluation used when evaluating a resilience-proof characteristic. It is a microscope photograph which shows the floating distance calculated | required when evaluating a resilience-proof characteristic. It is the schematic of the sample for evaluation used when evaluating a waterproof characteristic, (a) is a top view, (b) is C-C 'sectional drawing. It is the schematic which shows a pendulum testing machine. It is the schematic of the sample for evaluation used when evaluating dust sealability. It is the schematic which shows a dust seal property evaluation test apparatus.

  The present invention is a double-sided pressure-sensitive adhesive tape with a base material (pressure-sensitive adhesive tape with a base material) having a pressure-sensitive adhesive layer on both surfaces of a foam base material and having a total thickness of 250 μm or less. The total thickness in the double-sided pressure-sensitive adhesive tape with a substrate refers to the thickness from one pressure-sensitive adhesive layer surface (adhesive surface) to the other pressure-sensitive adhesive layer surface (adhesive surface). In the present invention, “pressure-sensitive adhesive tape (pressure-sensitive adhesive tape)” includes a sheet-like material, that is, “pressure-sensitive adhesive sheet (pressure-sensitive adhesive sheet)”.

  In the double-sided pressure-sensitive adhesive tape of the present invention, the base material is a foam base material, thereby exhibiting waterproofness and water-stopping property.

(Foam substrate)
In the double-sided pressure-sensitive adhesive tape of the present invention, the foam substrate is not particularly limited, but a substrate formed of a plastic 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.

  Specifically, as the plastic foam, for example, an olefin resin foam such as polyethylene foam, polypropylene foam, ethylene-propylene copolymer foam, ethylene-vinyl acetate copolymer foam, etc. Polyester resin foams such as polyethylene terephthalate foam, polyethylene naphthalate foam, polybutylene terephthalate foam; polyvinyl chloride resin foams such as polyvinyl chloride foam; vinyl acetate resin Foam made of polyphenylene sulfide resin; Foam made of polyamide (nylon) resin; Foam made of amide resin such as foam made of wholly aromatic polyamide (aramid) resin; Foam made of polyimide resin; Polyether ether Ketone (PEEK) foam; Styrene tree such as polystyrene foam Ltd. foam; and urethane resin foam and the like, such as polyurethane resin foam. A rubber-based resin foam may be used as the plastic foam.

  Of these, olefin resin foams are preferred from the viewpoint of good chemical resistance, solvent resistance, moisture permeation resistance, elasticity, and processability, and polyethylene foams, polypropylene foams, and the like are particularly preferred.

  In the plastic foam, the characteristics related to the bubble such as the shape of the bubble (the shape of the open cell, the shape of the closed cell, or the mixed form thereof), the size of the bubble, and the thickness between the bubbles are particularly limited. However, it 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 base material may be subjected to a known surface treatment. For example, the surface of the foam base material on the pressure-sensitive adhesive layer side may be subjected to chemical or physical surface treatment such as undercoating treatment, corona discharge treatment, or plasma treatment. In addition, the foam base material may have a single layer form or may have a laminated form.

  For foam base materials, fillers (inorganic fillers, organic fillers, etc.), anti-aging agents, antioxidants, UV absorbers, antistatic agents, lubricants, plasticizers, flame retardants, interfaces as required Various additives such as an activator may be blended.

  The foam base material is used as a base material for corrosion prevention of metal and double-sided pressure-sensitive adhesive tapes, and the double-sided pressure-sensitive adhesive tapes may be used for fixing electrical and electronic parts. A non-halogen-free foam substrate is preferred. The halogen compound is generally blended with a flame retardant or plasticizer containing a halogen compound.

  Moreover, the foam base material may be colored in order to develop design properties and optical properties (light blocking properties, light reflectivity, etc.) in the double-sided pressure-sensitive adhesive tape. 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 applications, the foam substrate is colored black. As black, L ^* (brightness) defined by the L ^* a ^* b ^* color system is preferably 35 or less (0 to 35), more preferably 30 or less (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.

When the double-sided pressure-sensitive adhesive tape is used for light reflection, the foam substrate is colored white. As white, L ^* (brightness) defined by the L ^* a ^* b ^* color system is preferably 87 or more (87 to 100), more preferably 87 or more (87 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.

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 black colorants include carbon black (furnace black, channel black, acetylene black, thermal black, lamp black, etc.), graphite, copper oxide, manganese dioxide, aniline black, perylene black, titanium 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, and the like can be used. Among these, carbon black is preferable from the viewpoint of cost and availability.

  Examples of the white colorant include titanium oxide (titanium dioxide such as rutile titanium dioxide and anatase titanium dioxide), zinc oxide, aluminum oxide, silicon oxide, zirconium oxide, magnesium oxide, calcium oxide, 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, zinc hydroxide, 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, diatomaceous earth, bentonite, litho Inorganic white colorants such as styrene, zeolite, sericite, hydrous halloysite, acrylic resin particles, polystyrene resin particles, polyurethane resin particles, amide resin particles, polycarbonate resin particles, silicone resin particles, urea Examples thereof include organic white colorants such as formalin resin particles and melamine resin particles.

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

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

  Moreover, when using a double-sided adhesive tape for a light reflection use, the visible light reflectance of a foam base material is 20 [%] or more (20-100 [%]) similarly to the visible light reflectance of a double-sided adhesive tape, More preferably, it is 25% or more (25 to 100%).

  The foaming ratio of the foam base material is, for example, 1.5 to 30 [cc / g], preferably 2.5 to 25.0 [cc] from the viewpoint of sealing properties, cushioning properties, elasticity, workability, and waterproofness. / G]. In addition, in this application, the expansion ratio of a foam base material is defined as the reciprocal number of the apparent density measured based on JISK6767.

  The elongation of the foam base material is, for example, 100 to 600 [%] in the MD direction, preferably 400 to 550 [%] in terms of sealing properties, cushioning properties, elasticity, workability, and waterproofness, and the CD direction. 100 to 500 [%], preferably 150 to 450 [%]. In addition, in this application, the elongation of a foam base material is measured based on JISK6767.

  The tensile strength of the foam substrate is, for example, 0.5 to 15 [MPa], preferably 1.0 to 10.0 in the MD direction from the viewpoint of sealing properties, cushioning properties, elasticity, workability, and waterproofness. [MPa] and 0.5 to 13.0 [MPa] in the CD direction, preferably 1.0 to 9.0 [MPa]. In addition, in this application, the tensile strength of a foam base material is measured based on JISK6767.

  The compression hardness of the foam base material is, for example, 5 to 150 when the base material is compressed 25% of the initial thickness on a flat plate in terms of sealing properties, cushioning properties, elasticity, workability, and waterproofness. [KPa], preferably 12 to 120 [kPa]. In addition, in this application, the compression hardness of a foam base material is measured based on JISK6767.

  The surface of the foam substrate is used to improve the adhesion to the pressure-sensitive adhesive layer, etc., using conventional surface treatments such as corona treatment, chromic acid treatment, ozone exposure, flame exposure, high-voltage impact exposure, and ionizing radiation treatment. An oxidation treatment or the like by a physical or physical method may be applied, or a coating treatment or the like with an undercoat agent or a release agent may be applied.

  As long as the total thickness of the double-sided pressure-sensitive adhesive tape does not exceed 250 μm, the thickness of the foam substrate can be appropriately selected according to strength, flexibility, purpose of use, and the like, for example, 50 to 240 μm, preferably 80 to 200 μm, More preferably, it is about 100-150 micrometers. If the foam substrate is less than 50 μm, there may be a problem in that through holes are formed, and if it exceeds 240 μm, a problem may occur in that sufficient adhesive properties cannot be secured. In addition, the foam base material may have a single layer form or may have a laminated form.

(Adhesive layer)
The pressure-sensitive adhesive layer (pressure-sensitive adhesive layer) is a layer that provides a pressure-sensitive adhesive surface (pressure-sensitive adhesive surface) in the double-sided pressure-sensitive adhesive tape of the present invention. Such a pressure-sensitive adhesive layer is formed with a known and common pressure-sensitive adhesive (pressure-sensitive adhesive) as a main component. The pressure-sensitive adhesive for forming the pressure-sensitive adhesive layer is not particularly limited. For example, an acrylic pressure-sensitive adhesive, a rubber-based pressure-sensitive adhesive, a vinyl alkyl ether pressure-sensitive adhesive, a silicone-based pressure-sensitive adhesive, a polyester-based pressure-sensitive adhesive, and a polyamide-based pressure-sensitive adhesive Known pressure-sensitive adhesives such as pressure-sensitive adhesives, urethane-based pressure-sensitive adhesives, fluorine-based pressure-sensitive adhesives, and epoxy-based pressure-sensitive adhesives can be used. Among the above, an acrylic pressure-sensitive adhesive can be suitably used as the pressure-sensitive adhesive. Moreover, these adhesives can be used individually or in combination of 2 or more types. The pressure-sensitive adhesive may be any 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), or the like can be used. .

  The acrylic pressure-sensitive adhesive is not particularly limited, but (meth) acrylic acid alkyl ester is an essential monomer component (monomer main component), and if necessary, copolymerizable with this. An adhesive having an acrylic polymer obtained by polymerizing (or copolymerizing) a monomer (such as a polar group-containing monomer or a polyfunctional monomer) as a base polymer (main agent) can be used. The polymerization method is not particularly limited, and a commonly used method known to those skilled in the art such as a UV polymerization method, a solution polymerization method or an emulsion polymerization method can be used.

Examples of (meth) acrylic acid alkyl ester ((meth) acrylic acid alkyl ester having a linear or branched alkyl group) used as a monomer main component of the acrylic polymer include, for example, (meth) acrylic acid Methyl, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, butyl (meth) acrylate, isobutyl (meth) acrylate, s-butyl (meth) acrylate, (meth) acrylic T-butyl acid, pentyl (meth) acrylate, isopentyl (meth) acrylate, hexyl (meth) acrylate, heptyl (meth) acrylate, octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, ( (Meth) Isooctyl acrylate, (Meth) acrylate nonyl, (Meth) acrylate Nonyl, decyl (meth) acrylate, isodecyl (meth) acrylate, undecyl (meth) acrylate, dodecyl (meth) acrylate, tridecyl (meth) acrylate, tetradecyl (meth) acrylate, pentadecyl (meth) acrylate (Meth) acrylic acid C _1-20 alkyl esters such as hexadecyl (meth) acrylate, heptadecyl (meth) acrylate, octadecyl (meth) acrylate, nonadecyl (meth) acrylate, eicosyl (meth) acrylate [preferably (Meth) acrylic acid C _2-14 alkyl ester, more preferably (meth) acrylic acid C _2-10 alkyl ester].

  Since the (meth) acrylic acid ester is used as the main monomer component of the acrylic polymer, the proportion of the (meth) acrylic acid alkyl ester is, for example, relative to the total amount of monomer components for preparing the acrylic polymer. It is important that the amount is 60% by weight or more (preferably 80% by weight or more).

  In the acrylic polymer, various copolymerizable monomers such as polar group-containing monomers and polyfunctional monomers may be used as monomer components. By using a copolymerizable monomer as the monomer component, for example, the adhesive force to the adherend can be improved, or the cohesive force of the pressure-sensitive adhesive 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, and 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, (meta ) Dimethylaminoethyl acrylate, (meth) acrylic Amino group-containing monomers such as t-butylaminoethyl acid; glycidyl group-containing monomers such as glycidyl (meth) acrylate and methyl glycidyl (meth) acrylate; cyano group-containing monomers such as acrylonitrile and methacrylonitrile N-vinyl-2-pyrrolidone, (meth) acryloylmorpholine, N-vinylpyridine, N-vinylpiperidone, N-vinylpyrimidine, N-vinylpiperazine, N-vinylpyrrole, N-vinylimidazole, N-vinyloxazole Heterocycle-containing vinyl monomers such as (meth) acrylic acid methoxyethyl, (meth) acrylic acid ethoxyethyl and other (meth) acrylic acid alkoxyalkyl monomers; vinyl sulfonate sodium and other sulfonic acid group-containing monomers Body; 2-hydroxyethylacryloylfu Phosphoric acid group-containing monomers such as Sufeto; cyclohexyl maleimide, imide group-containing monomers such as isopropyl maleimide; 2-methacryloyl isocyanate group-containing monomers such as methacryloyloxyethyl isocyanate, and the like. As the polar group-containing monomer, a carboxyl group-containing monomer such as acrylic acid or its anhydride is suitable. The amount of the polar group-containing monomer used is 30% by weight or less (for example, 0.1 to 30% by weight), preferably 0.1 to 15%, based on the total amount of monomer components for forming the acrylic polymer. % By weight. When the usage-amount of a polar group containing monomer exceeds 30 weight%, the cohesive force of an acrylic adhesive will become high too much, and there exists a possibility that adhesiveness may fall. Moreover, when there is too little usage-amount of a polar group containing monomer (for example, it is less than 1 weight% with respect to the monomer component whole quantity for preparing an acrylic polymer), the cohesion force of an acrylic adhesive will fall, A high shearing force may not be obtained.

  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, tetramethylol methanetri ( Examples include meth) acrylate, allyl (meth) acrylate, vinyl (meth) acrylate, divinylbenzene, epoxy acrylate, polyester acrylate, and urethane acrylate. The amount of the polyfunctional monomer used is 2% by weight or less (for example, 0.01 to 2% by weight), preferably 0.02 to less than the total amount of monomer components for preparing the acrylic polymer. 1% by weight. If the amount of the polyfunctional monomer used exceeds 2% by weight based on the total amount of the monomer components for forming the acrylic polymer, the cohesive force of the acrylic pressure-sensitive adhesive may become too high and the adhesiveness may decrease. is there. Moreover, when there is too little usage-amount of a polyfunctional monomer (for example, it is less than 0.01 weight% with respect to the monomer component whole quantity for preparing an acrylic polymer), for example, aggregation of an acrylic adhesive The power may be reduced.

  In addition to the polar group-containing monomer and polyfunctional monomer, examples of copolymerizable monomers include vinyl esters such as vinyl acetate and vinyl propionate; aromatic vinyl such as styrene and vinyltoluene. Compounds; ethylene, butadiene, isoprene, isobutylene and other olefins or dienes; vinyl alkyl ethers and other vinyl ethers; vinyl chloride and the like can be used. Furthermore, (meth) acrylic acid ester which has alicyclic hydrocarbon groups, such as cyclopentyl (meth) acrylate, cyclohexyl (meth) acrylate, and isobornyl (meth) acrylate, etc. are mentioned.

  Furthermore, the pressure-sensitive adhesive layer may contain appropriate additives depending on the application. For example, depending on the type of pressure-sensitive adhesive, a crosslinking agent (for example, polyisocyanate-based crosslinking agent, silicone-based crosslinking agent, epoxy-based crosslinking agent, alkyl etherified melamine-based crosslinking agent), tackifier (for example, rosin derivative resin) , Polyterpene resin, petroleum resin, oil-soluble phenol resin, etc., solid, semi-solid, or liquid at room temperature), plasticizer, filler, anti-aging agent, antioxidant, colorant (carbon black and other pigments) An appropriate additive such as a dye may be included.

  The resin composition (pressure-sensitive adhesive composition) forming the pressure-sensitive adhesive layer can be prepared by mixing the above base polymer, various additives added according to the purpose, and the like using a known method.

  Although the formation method in particular of an adhesive layer is not restrict | limited, For example, the method of apply | coating and forming the said adhesive composition on suitable support bodies, such as a release liner and a base material, is mentioned. In addition, in this formation method, you may perform a heating, drying, etc. as needed.

  The total thickness of the pressure-sensitive adhesive layer (the total thickness of the pressure-sensitive adhesive layers on both sides) varies depending on the type of the pressure-sensitive adhesive layer, and is not particularly limited as long as the total thickness of the double-sided pressure-sensitive adhesive tape does not exceed 250 μm, but is usually about 10 to 200 μm. Preferably, it is 30-170 micrometers, More preferably, it is 40-150 micrometers, Most preferably, it is 50-100 micrometers. If the total thickness of the pressure-sensitive adhesive layer is less than 10 μm, sufficient adhesive properties may not be ensured. On the other hand, if it exceeds 200 μm, workability may be deteriorated. Note that the thicknesses of the pressure-sensitive adhesive layers on both sides may be the same or different. Moreover, the thickness of the adhesive layer on one side is not particularly limited, but is 5 to 100 μm, preferably 15 to 75 μm, and more preferably 20 to 65 μm. The pressure-sensitive adhesive layer may have either a single layer or a multilayer.

(Release liner)
The pressure-sensitive adhesive layer surface (adhesive surface) of the double-sided pressure-sensitive adhesive tape of the present invention may be protected by a release liner (separator, release film) 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 pressure-sensitive adhesive layer, and is peeled off when being applied 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 of a 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 conventional method. Further, the thickness of the release liner is not particularly limited.

(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. For example, another layer may be provided between the foam substrate and the pressure-sensitive adhesive layer. In such a case, since the total thickness of the double-sided pressure-sensitive adhesive tape of the present invention refers to the thickness from one adhesive surface to the other adhesive surface, the thickness of the other layer is included in the total thickness of the double-sided adhesive tape.

(Double-sided adhesive tape)
The double-sided pressure-sensitive adhesive tape of the present invention has a pressure-sensitive adhesive layer on both sides of a foam substrate, and has a total thickness (thickness from one pressure-sensitive adhesive surface to the other pressure-sensitive adhesive surface) of 250 μm or less. It is. Moreover, the double-sided pressure-sensitive adhesive tape may have a form in which sheet-like ones are laminated, or may have a form wound in a roll shape.

  The double-sided pressure-sensitive adhesive tape of the present invention can be produced using a known or common method. For example, it can produce by apply | coating the said adhesive composition to both surfaces of a foam base material, and forming an adhesive layer. It can also be produced by transferring a pressure-sensitive adhesive layer formed by applying the pressure-sensitive adhesive composition onto a suitable support such as a release liner or a base material on both sides of the foam base material. .

  The total thickness of the double-sided pressure-sensitive adhesive tape is 250 μm or less (for example, 50 to 250 μm), preferably 200 μm or less (for example, 100 to 200 μm), more preferably 150 μm or less from the viewpoints of thinning, miniaturization, weight reduction, and resource saving. (For example, 100 to 150 μm).

  The double-sided pressure-sensitive adhesive tape of the present invention has a foam base material as a base material and has a total thickness of 250 μm or less.

  In the double-sided pressure-sensitive adhesive tape of the present invention, the tensile strength based on JIS K 6767 is preferably, for example, 0.5 to 20.0 [MPa], preferably 3.0 to 13.0 [MPa] from the viewpoint of improving workability. MPa].

  Such tensile strength can be obtained by adjusting the thickness and type of the foam base material, the expansion ratio, and the thickness and type of the pressure-sensitive adhesive.

  In this invention, when it has the above tensile strength, workability will become favorable, for example, it can perform a cutting process, a punching process, and the re-peeling at the time of reattachment can be performed easily. Double-sided pressure-sensitive adhesive tapes having such tensile strength can be suitably used for applications such as fixing members, dustproofing, waterproofing, shock absorption, etc., by cutting or punching them into special or complex shapes. it can.

  In the double-sided pressure-sensitive adhesive tape of the present invention, the elongation based on JIS K 6767 is not particularly limited, but is preferably 100 to 600 [%], for example, from the viewpoints of sealing properties, cushioning properties, elasticity, workability, and waterproofness. Is 400 to 550 [%].

The elongation based on JIS K 6767 is obtained by the following formula.
Elongation [%] = (Distance between marked lines at break-Initial distance between marked lines) / (Initial distance between marked lines) × 100

  Such elongation can be obtained by adjusting the thickness and type of the foam substrate, the expansion ratio, and the thickness and type of the pressure-sensitive adhesive.

  In the double-sided pressure-sensitive adhesive tape of the present invention, the compression load is not particularly limited, but the compression load when compressed by 30% of the initial thickness (from the viewpoint of sealing properties, cushioning properties, elasticity, workability, and waterproofness) 30% compression load), for example, is preferably 5 to 200 [kPa], more preferably 5 to 150 [kPa], and still more preferably 12 to 120 [kPa].

The compressive load is defined by the following formula.
Compressive load = (Load when 10 double-sided adhesive tapes are stacked at a rate of 10 mm / min by the predetermined thickness) ÷ (Area of double-sided adhesive tape)
The area of the double-sided adhesive tape was 30 mm × 30 mm.

  Such a compressive load can be obtained by adjusting the thickness and type of the foam base material, the expansion ratio, and the thickness and type of the pressure-sensitive adhesive.

  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 compression load is not particularly limited, but it prevents peeling due to stress of the internal material. Therefore, for example, 30 to 200 [N] is preferable, more preferably 50 to 200 [N], and still more preferably 55 to 200 [N].

  Such pressure adhesive force can be obtained by adjusting the thickness and type of the foam base material, the expansion ratio, and the thickness and type of the pressure-sensitive adhesive.

  Moreover, in the double-sided adhesive tape of this invention, since the foam base material is used, the dispersion | variation in the press adhesive force for every compression load is small, and sufficient press adhesive force can be ensured even with light press 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%.

  Moreover, the variation in the pressure adhesive force for each compression load can adjust the thickness and type of the foam base material, the expansion ratio, and the thickness and type of the pressure-sensitive adhesive.

  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 is suitable for adherends that are difficult to increase the compression load at the time of application (for example, adherends that are easily broken, soft adherends, and adherends with stepped surfaces). Can be suitably used.

  In addition, the pressure adhesive force is a measurement sample obtained by bonding a polycarbonate plate and an acrylic plate with a predetermined compressive load with a window frame-shaped double-sided adhesive tape having a width of 40 mm, a length of 60 mm, 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 base material, 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. In addition, 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 base material relieves stress when absorbing the shock. ) Has excellent impact drop characteristics.

In the double-sided pressure-sensitive adhesive tape of the present invention, the impact absorbability defined by the following formula is not particularly limited from the viewpoint of sealing properties, cushioning properties, elasticity, workability, and waterproofness, but is preferably 5% or more, More preferably, it is 7 [%] or more, and still more preferably 10 [%] or more.
Shock absorption (%) = (F0−F1) / F0 × 100
F0: Impact force when not using double-sided adhesive tape (blank value)
F1: Impact force when using a double-sided pressure-sensitive adhesive tape In addition, as the value of shock absorbency is closer to 100%, the double-sided pressure-sensitive adhesive tape as a sample absorbs the shock.

  In particular, in the double-sided pressure-sensitive adhesive tape of the present invention, the impact absorbency defined by the above formula is not compressed at all (compression rate 0%), and in the thickness direction so as to be a predetermined thickness with respect to the initial thickness. When compressed [For example, when compressed in the thickness direction to be 85% of the initial thickness (15% compression), or compressed in the thickness direction to be 70% of the initial thickness (30% compression) Etc.], it is preferable to have an impact absorbability defined by the above formula. This is because it can be applied regardless of the size of the gap and can be used for various purposes.

  Such impact absorbability can be obtained by adjusting the thickness and type of the foam base material, the expansion ratio, and the thickness and type of the pressure-sensitive adhesive.

In the double-sided pressure-sensitive adhesive tape of the present invention, the dust sealability defined by the following formula is not particularly limited, but 90% or more is preferable in terms of sealability, cushioning properties, elasticity, workability, waterproofness, and dustproofness. More preferably, it is 95 [%] or more, and still more preferably 98 [%] or more.
Dust sealability (%) = (P ₀ −P _f ) / P ₀ × 100
P ₀ : number of particles in the space (blank value)
P _f : Number of particles passing through the double-sided adhesive tape

  Such dust sealability can be obtained by adjusting the thickness and type of the foam base material, the expansion ratio, and the thickness and type of the pressure-sensitive adhesive.

  When the double-sided pressure-sensitive adhesive tape of the present invention has the above-described dust sealability, it can be suitably used for fixing electronic parts.

  The double-sided pressure-sensitive adhesive tape of the present invention is preferably a halogen-free double-sided pressure-sensitive adhesive tape. This is because corrosion to metal can be prevented and it may be used for fixing electric / electronic parts. Moreover, when the double-sided pressure-sensitive adhesive tape of the present invention is halogen-free, it is a thin film, excellent in waterproofness and environmentally friendly. For example, it is possible to suppress the generation of gas having toxicity and corrosivity during combustion.

  Such a halogen-free double-sided pressure-sensitive adhesive tape does not intentionally use a halogen compound as a raw material for a foam base material or an adhesive, uses a halogen-free foam base material that does not intentionally contain a halogen compound, When an additive is used, it can be obtained by not using an additive derived from a halogen compound. In addition, the means for obtaining such a halogen-free double-sided pressure-sensitive adhesive tape may be used in combination.

In particular, in the double-sided pressure-sensitive adhesive tape of the present invention, the amount of chlorine-based gas quantified based on a method for measuring the amount of halogen-based gas described below is preferably 50 [μg / g] or less, more preferably. Is 30 [μg / g] or less, and more preferably 15 [μg / g] or less. Here, the chlorine-based gas is defined as a chlorine compound such as chlorine (Cl ₂ ) or hydrochloric acid (HCl). When the generation amount of chlorine-based gas is 50 [μg / g] or less, in particular, corrosion against metals can be prevented, and it can be suitably used for fixing electric / electronic parts.

  In addition, the double-sided adhesive tape whose chlorine gas generation amount is 50 [μg / g] or less can be obtained by using the means for obtaining the halogen-free double-sided adhesive tape.

  The amount of halogen gas generated is determined by weighing a predetermined amount of double-sided adhesive tape, burning it completely with the combustion gas sampling method, and absorbing the generated gas in the absorption liquid. , Fluorine ions, bromine ions and iodine ions can be determined (μg / g).

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

  For example, when the double-sided pressure-sensitive adhesive tape is used for light shielding applications, the visible light transmittance is 15% or less (0 to 15%), more preferably 10% by coloring the foam base material black. ] (0 to 10 [%]) is preferable below. Moreover, when using a double-sided adhesive tape for light reflection use, visible light reflectance is 20 [%] or more (20-100 [%]) by white-coloring a foam base material, More preferably, it is 25 [%. ] Or more (25 to 100 [%]). In addition, in this invention, the visible light transmittance | permeability and visible light reflectance of a double-sided adhesive tape are measured by the below-mentioned method.

  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 light collecting member.

  In the double-sided pressure-sensitive adhesive tape of the present invention, the floating distance required by the following sample for measuring the floating distance is not particularly limited. However, from the viewpoint of preventing the peeling due to the stress of the internal member, for example, 0 to 0. 3 mm is preferable, and preferably 0 to 0.1 mm.

  The floating distance is adjusted by aligning one end in the length direction of the polyethylene terephthalate film (width: 10 mm, length: 100 mm) with one end in the length direction of the polycarbonate plate (width: 10 mm, length: 30 mm, thickness: 2 mm). The polycarbonate plate and the polyethylene terephthalate film are fixed, and a double-sided pressure-sensitive adhesive tape (width: 10 mm, length: 3 mm) is attached to the other end in the length direction of the polyethylene terephthalate film. After being laminated so that they overlap, the polyethylene terephthalate film is folded in a loop shape, and bonded and aged so that it is 10 mm from the end of the surface opposite to the surface in contact with the polyethylene terephthalate film of the polycarbonate plate Obtained sample (floating distance measurement Use samples from the reference 4), are determined.

  The floating distance is the maximum distance between the adhesive surface of the double-sided adhesive tape and the surface of the polycarbonate plate in the sample for measuring the floating distance (corresponding to a in FIG. 5, a in FIG. 5 is 0.194 mm). The difference between the floating distance (floating height) before aging and the floating distance (floating height) after aging is the final floating distance (floating height).

  Such a floating distance can be obtained by adjusting the thickness and type of the foam base material, the expansion ratio, and the thickness and type of the pressure-sensitive adhesive.

  When the double-sided pressure-sensitive adhesive tape of the present invention has such a floating distance, good repulsion resistance can be exhibited. Moreover, the smaller the floating distance, the better the repulsion resistance. For example, when the main panel of a mobile phone is fixed with a double-sided adhesive tape, such floating may occur due to stress from internal members, deterioration of the double-sided adhesive tape over time, or uneven or double-sided shape of the adherend However, it may cause problems. Such a double-sided pressure-sensitive adhesive tape can be suitably used for an adherend having an uneven shape or a curved surface portion.

  As described above, the double-sided pressure-sensitive adhesive tape of the present invention has cutting (punching) processability, re-peelability upon reattachment, step following ability, sealing performance, water stopping performance, anti-floating property, adhesion reliability, workability, optical It can have characteristics such as function and resilience resistance. For this reason, the double-sided pressure-sensitive adhesive tape of the present invention is used, for example, for 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, protecting a battery pack of a personal computer, It is extremely useful for applications such as lens waterproofing.

  Moreover, the double-sided adhesive tape of this invention is used for an optical member. More specifically, it is used for applications for bonding optical members (for optical member bonding), optical product manufacturing applications, and the like.

  The optical member is a member having optical properties (for example, polarization, light refraction, light scattering, light reflection, light transmission, light absorption, light diffraction, optical rotation, visibility, etc.). Say. Although it will not specifically limit if it is a member which has an optical characteristic as an optical member, For example, it is used for the member which comprises apparatuses (optical apparatus), such as a display apparatus (image display apparatus) and an input device, or these apparatuses. For example, a polarizing plate, a wave plate, a retardation plate, an optical compensation film, a brightness enhancement film, a light guide plate, a reflection film, an antireflection film, a transparent conductive film (such as an ITO film), a design film, a decorative film, Examples include a surface protective film, a prism, a lens, a color filter, a transparent substrate, and a member in which these are laminated. In addition, said "plate" and "film" shall each also include forms, such as plate shape, film shape, and sheet shape, for example, "polarizing plate" shall also include "polarizing film" and "polarizing sheet".

  Examples of the display device include a liquid crystal display device, an organic EL (electroluminescence) display device, a PDP (plasma display panel), and electronic paper. Moreover, a touch panel etc. are mentioned as said input device.

  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 in the 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 and 1.5 parts by weight of an isocyanate-based crosslinking agent (trade name “Coronate L” manufactured by Nippon Polyurethane Industry Co., Ltd.) with respect to 100 parts by weight of the polymer component in the solution. Part (solid content conversion) was blended to obtain an acrylic pressure-sensitive adhesive composition.
This acrylic pressure-sensitive adhesive composition was applied onto a release paper treated with silicone 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.
On this pressure-sensitive adhesive layer, a black polyethylene foam base material [trade name “Borara XL-HN # 03001W Shorikuro” manufactured by Sekisui Chemical Co., Ltd., thickness: 0.10 mm, foaming ratio: 2.9 cc / g, elongation rate : 480% (MD direction), 195% (CD direction), tensile strength: 9.5 MPa (MD direction), 8.7 MPa (CD direction), compression hardness: 64 kPa (at 25% compression)] A single-sided pressure-sensitive adhesive tape having a layer structure of release liner / pressure-sensitive adhesive layer / foam base was formed by bonding so as to contact the layer.
Next, using an acrylic pressure-sensitive adhesive composition and a bar coater, it was applied onto a process release liner and dried at 110 ° C. for 3 minutes to form a pressure-sensitive adhesive layer having a thickness of 25 μm.
After bonding the single-sided pressure-sensitive adhesive tape having the layer structure of the release liner / pressure-sensitive adhesive layer / foam base material so as to be in contact with the foam base material on the pressure-sensitive adhesive layer formed on this process release liner, The process release liner was peeled off to form a layer structure of release liner / adhesive layer / foam substrate / adhesive layer, thereby producing a double-sided adhesive tape.

(Example 2)
Instead of the black polyethylene foam base material, the white polyethylene foam base material [trade name “Borara XL-HN # 03001W Shorishiro” manufactured by Sekisui Chemical Co., Ltd., thickness: 0.10 mm, foaming ratio: 3.1 cc / g, Elongation: 497% (MD direction), 184% (CD direction), tensile strength: 9.4 MPa (MD direction), 8.4 MPa (CD direction), compression hardness: 64 kPa (at 25% compression) ] Was used in the same manner as in Example 1 except that a double-sided pressure-sensitive adhesive tape was produced.

(Example 3)
A double-sided pressure-sensitive adhesive tape was produced in the same manner as in Example 1 except that a pressure-sensitive adhesive layer having a thickness of 50 μm was formed on the release liner and the process release liner.

Example 4
A double-sided pressure-sensitive adhesive tape was produced in the same manner as in Example 2, except that a pressure-sensitive adhesive layer having a thickness of 50 μm was formed on the release liner and the process release liner.

(Comparative Example 1)
As a double-sided adhesive tape, a double-sided adhesive tape with a substrate (trade name “No. 5637” manufactured by Nitto Denko Corporation, a structure in which an acrylic adhesive layer is laminated on both sides of a PET # 12 substrate, from one adhesive surface The thickness to the other adhesive surface: 0.10 mm) was used.

(Comparative Example 2)
As a double-sided adhesive tape, a double-sided adhesive tape with a base material (trade name “No. 5100” manufactured by Nitto Denko Corporation, a structure in which an acrylic adhesive layer is laminated on both sides of a nonwoven fabric base, from one adhesive side to the other Thickness up to the adhesive surface: 0.20 mm) was used.
(Comparative Example 3)
Double-sided adhesive tape with a base material (trade name “KF-5713” manufactured by Nitto Denko Corporation, a structure in which an acrylic adhesive layer is laminated on both sides of a foam base material, from one adhesive surface to the other as a double-sided adhesive tape The thickness up to the adhesive surface was 0.33 mm).

(Evaluation)
For Examples and Comparative Examples, 180 ° peel adhesion, pressure adhesion, drop impact resistance, rebound resistance, optical properties, waterproof properties, tensile strength, elongation, compressive load, halogen generation, impact absorption, dust seal Sex was measured or evaluated, respectively.

(180 ° peel adhesion)
The produced adhesive tape was cut into a size of 20 mm in width and 100 mm in length, and a measurement film was produced by bonding a PET film (polyester film having a thickness of 25 μm) to one adhesive layer.
The release liner of the measurement sample was peeled off to expose the adhesive surface for measuring the adhesive force, and then pressed onto a SUS plate with a 2 kg roller and one reciprocation, and left in an environment of 23 ° C. × 50% RH for 30 minutes.
After leaving, it is peeled off at a tensile speed of 300 mm / min and a peeling angle of 180 ° with a universal tensile compression testing machine (device name “Tensile compression testing machine, TG-1kN” manufactured by Minebea Co., Ltd.), and 180 ° peel adhesive strength is obtained. It was measured. The measurement was performed in an environment of 23 ° C. × 50% RH. The measurement results are shown in Table 1 below.

(Press adhesive strength)
The produced adhesive tape was cut into a window frame shape (frame shape) having a width of 1 mm as shown in FIG. 1 (width: 40 mm, length: 60 mm) to obtain a window frame-shaped 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) having a through hole with a diameter of 15 mm in the center ( Welding: 70 mm, Vertical: 80 mm, Thickness: 2 mm) are bonded together by pressure bonding under the condition of one reciprocating roller with a predetermined pressure load (1 kg, 2 kg, 3 kg, 4 kg, or 5 kg), and an evaluation sample (Samples for 1 kg evaluation, samples for 2 kg evaluation, samples for 3 kg evaluation, samples for 4 kg evaluation, and samples for 5 kg evaluation) were obtained (see FIGS. 1A and 1B).
Separately from these, an evaluation sample (5 kg evaluation sample) bonded 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%.

  FIG. 1 is a schematic view of a sample for evaluation used when measuring pressure adhesive strength, (a) is a top view, and (b) is a cross-sectional view taken along line A-A ′. In FIG. 1, 1 is a polycarbonate plate, 2 is a window frame-shaped double-sided pressure-sensitive adhesive tape, 3 is an acrylic plate, and 4 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. 2). The measurement was performed at room temperature. The measurement results are shown in Table 2 below.

  FIG. 2 is a schematic cross-sectional view showing a method for measuring the pressing adhesive force. In FIG. 2, 1 is a polycarbonate plate, 2 is a window frame-shaped double-sided adhesive tape, 3 is an acrylic plate, 21 is a round bar, and 22 is a support base. The evaluation sample is fixed to the support base 22 of the tensile and compression tester as shown in FIG. 2, and the evaluation sample acrylic plate 3 is pressed by the round bar 21 that has passed through the through hole of the polycarbonate plate 1. In the sample for evaluation, the polycarbonate plate 1 was subjected to a load when the acrylic plate was pressed, and was not bent or damaged.

  In the examples, the variation in the pressure adhesion force due to the pressure bonding load was small, while in the comparative example, the variation in the pressure adhesion force due to the compression load was large. Since the Example has a foam base material, sufficient pressure-adhesive force could be secured even with light pressure bonding, as compared with the comparative example of PET base material.

(Drop impact resistance)
The produced adhesive tape was cut into a window frame shape (frame shape) having a width of 1 mm as shown in FIG. 3 (width: 40 mm, length: 60 mm) to obtain a window frame-shaped 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 the 2 kg roller to obtain a sample for evaluation (see FIGS. 3A and 3B).
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. The drop impact resistance was evaluated by first free-falling 18 times at room temperature (about 23 ° C.) and then holding 18 times in 18 free-falls at room temperature. About) was carried out by free-falling 60 times under.
Evaluation criteria Good: “Acrylic plate was not peeled off and held the acrylic plate for both 18 free falls at normal temperature and 60 free drops at low temperature”
Defect: “Acrylic plate peeled off by free fall at room temperature” or “Acrylic plate was not peeled by free fall at room temperature, and the acrylic plate was held, but at low temperature Acrylic board peeling due to free fall at

  FIG. 3 is a schematic view of a sample for evaluation used in evaluating the drop impact resistance characteristics, (a) is a top view, and (b) is a B-B ′ sectional view. In FIG. 3, 31 is a polycarbonate plate, 32 is a window frame-shaped double-sided adhesive tape, and 33 is an acrylic plate (acrylic lens).

In Table 3, the number of times described in the case of being evaluated as “defective” indicates the number of times when the acrylic plate peels due to free fall. For example, “defective (once)” indicates that the acrylic plate peeled off in the first free fall and was evaluated as defective.

  Since the compositions of the pressure-sensitive adhesives of the example and the comparative example 1 are the same, the drop impact characteristics of the example having a foam base material are much better.

(Repulsion resistance)
Polycarbonate plate (width: 10 mm, length: 30 mm, thickness: 2 mm), cut double-sided adhesive tape of example (width: 10 mm, length: 3 mm), and polyethylene terephthalate film (PET film) (“PET # 100 ”, Width: 10 mm, length: 100 mm), samples for evaluation shown in FIGS. 4 and 5 were produced.
The sample for evaluation was aged at 23 ° C. for 24 hours, and further aged at 80 ° C. for 24 hours.
Then, using a digital microscope (trade name “VH-500” manufactured by Keyence Corporation), “floating distance” (floating height) (between the adhesive surface of the double-sided adhesive tape and the surface of the polycarbonate plate) Maximum distance) (see Fig. 5), and the difference between the floating distance before aging (floating height) and the floating distance after aging (floating height) is evaluated as the final "floating distance" (floating height) did.
The smaller the “floating distance”, the better the resilience characteristics.

  FIG. 4 is a schematic cross-sectional view of an evaluation sample used for evaluating the resilience resistance. In FIG. 4, 41 is a polycarbonate plate, 42 is a double-sided adhesive tape, and 43 is a polyethylene terephthalate film. 5, 51 is a polycarbonate plate, 52 is a double-sided adhesive tape, 53 is a polyester film, a is a floating distance (floating height) (the maximum distance between the adhesive surface of the double-sided adhesive tape and the surface of the polycarbonate plate) ).

(optical properties)
The visible light transmittance was irradiated from one side of the double-sided pressure-sensitive adhesive tape at a wavelength of 550 nm using a spectrophotometer (device name “U-4100 type spectrophotometer” manufactured by Hitachi High-Technologies Corporation), and the other side. It was determined by measuring the intensity of light transmitted to the side.
Visible light reflectance is measured by irradiating one surface of a double-sided adhesive tape at a wavelength of 550 nm using a spectrophotometer (device name “U-4100 type spectrophotometer” manufactured by Hitachi High-Technologies Corporation). It was determined by measuring the intensity of the light reflected from the irradiated surface.
The measurement was performed with the release liner peeled off.

In Table 5, “-” indicates that measurement was not performed.

(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 the four acrylic plates with adhesive tape on the 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.
The step tape is affixed for the purpose of providing unevenness on the polycarbonate plate, and two tapes having thicknesses of 10 μm, 20 μm, 30 μm, 50 μm, 70 μm, and 100 μm are used (see FIG. 6).
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 an uneven height of 0 μm (no step) was also obtained by pressure bonding under the condition of one reciprocation of the roller.
In addition, since the nonwoven fabric (width: 20 mm, length: 30 mm, thickness: 0.05 mm) has a property which discolors when it absorbs water, it put between the acrylic board and the polycarbonate board for internal water immersion evaluation. In addition, the nonwoven fabric does not have any influence on the waterproof property evaluation test.

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 the evaluation, two samples for evaluation (see FIGS. 6A and 6B) to which four acrylic plates are attached are prepared for each uneven height, and the presence or absence of water immersion is visually observed for the eight samples. Was done. 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.

  6A and 6B are schematic views of a sample for evaluation used for evaluating waterproof properties, where FIG. 6A is a top view and FIG. 6B is a cross-sectional view taken along C-C ′. In FIG. 6, 61 is a polycarbonate plate, 62 is a step tape, 63 is a window frame-shaped double-sided adhesive tape, 64 is an acrylic plate (acrylic lens), and 65 is a non-woven fabric.

  The example had better waterproof properties than the comparative example. This is considered to be due to the good followability to the uneven surface of the adherend unique to the foam substrate.

(Tensile strength, elongation)
Tensile strength was evaluated by measuring tensile strength and elongation based on JIS K 6767.
The double-sided pressure-sensitive adhesive tape was cut into dumbbell No. 1 to obtain a test piece, and a marked line was attached to the center of the parallel part of the test piece so that the interval was 40 mm.
The test piece with the marked line is accurately placed on the upper and lower chucks of a universal tensile compression tester (tensile compression tester, device name “TG-1kN” manufactured by Minebea Co., Ltd.) so that no distortion occurs during measurement. The sample was pulled at a pulling speed of 500 mm / min, and the maximum load (stress at break) and the distance between the marked lines were measured.
From the maximum load and the distance between the marked lines, the tensile strength and elongation were determined from the following formula.
Tensile strength [MPa] = (Maximum load) / (Cross sectional area of test piece)
Elongation [%] = (Distance between marked lines at break-Initial distance between marked lines) / (Initial distance between marked lines) × 100

(Compression load)
A test piece was prepared by cutting 10 sheets of double-sided pressure-sensitive adhesive tape into 30 mm × width: 30 mm.
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, The load at that time was measured by compressing by 20%, 30%, 40% or 50%, and the compression load at each compression rate was obtained from the following formula.
Compression load [kPa] = (Load when compressed by a predetermined thickness of the initial thickness) / (Area of specimen)

  In Table 8, “overload” indicates that the measurable limit of the load cell of the tensile compression tester was exceeded. From Table 8, it was confirmed that the example was a more flexible tape.

(Halogen generation amount)
The example and comparative example except a release liner were used as the double-sided adhesive tape as a measurement sample.
30 mg of a measurement sample was weighed and completely burned by a combustion gas sampling method (automatic combustion apparatus, manufactured by Mitsubishi Chemical Analytech Co., Ltd., “AQF-100”), and the generated gas was dissolved in an aqueous solution [H ₂ O ₂ (30 ppm), Methanesulfonic acid (adjusted to 3 ppm)].
250 μL of this absorbing solution was introduced into an ion chromatograph (anion / DIONEX, DX-320), and chlorine ions, fluorine ions, bromine ions and iodine ions were quantified (μg / g).
The results are shown in Table 9. In Table 9, “<3” indicates that it is less than 3 [μg / g] which is the lower limit of quantification.

(Shock absorption)
For the examples (layer structure of release liner / adhesive layer / foam substrate / adhesive layer), the sample was cut into a width: 20 mm × length: 20 mm (20 mm square), the release liner was removed, and the measurement sample did. Similarly, the comparative example was used as a measurement sample except for the release liner. The measurement sample corresponds to the measurement sample 72 in FIG.

The impact absorbability (impact absorbability) is the impact force when the double-sided adhesive tape as a sample is not inserted using the pendulum tester shown in FIG. 7 (impact force of only the support plate and the acrylic plate) (blank value): F0 and impact force when the double-sided pressure-sensitive adhesive tape as a sample was inserted between the support plate and the acrylic plate (numerical value at the time of laminating the double-sided pressure-sensitive adhesive tape): F1 was measured and calculated from the following formula.
Shock absorption (%) = (F0−F1) / F0 × 100

  FIG. 7 is a schematic view showing a pendulum tester in which a measurement sample is inserted. In FIG. 7, 7 is a pendulum tester, 71 is a load cell, 72 is a measurement sample (double-sided adhesive tape), 73 is an acrylic plate, 74 is an iron ball, and 75 is pressing pressure adjusting means. 76 is a support plate, 77 is a support column, and 78 is a support bar. The load cell 71 includes a pressure sensor that senses the impact force when the iron ball 74 collides, and can measure a specific numerical value of the impact force. As shown in FIG. 7, the measurement sample 72 is inserted at a position on the load cell between the acrylic plate 73 and the support plate 76. The compression rate of the measurement sample 72 is adjusted by the pressing pressure adjusting means 75. The iron ball 74 is an impactor, and has a diameter of 19.5 mm and a weight of 40 g (0.39 N). Further, the iron ball 74 is temporarily fixed in a state where it is swung up to a drop angle (swing angle) of 40 °, and then shaken off.

  For each measurement sample, the shock absorption is measured when the measurement sample is not compressed at all (compression ratio 0%), when the measurement sample is compressed 15% (15% compression, and the measurement sample is 85% of the initial thickness). And when the measurement sample is compressed by 30% (30% compression, when the measurement sample is compressed in the thickness direction so as to be 70% of the initial thickness). 3 times each. Table 9 shows the average value of impact absorbability of each measurement sample under each test condition.

(Dust seal)
As for the examples (layer configuration of release liner / adhesive layer / foam substrate / adhesive layer), as shown in FIG. 8, frame shape (window frame shape) (length: 52 mm × width: 52 mm, width) : 2 mm), and a sample for evaluation was obtained by removing the release liner (evaluation sample 8 in FIG. 8). The comparative example was similarly used as an evaluation sample. The evaluation sample corresponds to the evaluation sample 94 in FIG.

  The dust sealability was determined by determining the proportion of particles that passed through the evaluation sample as a gasket material using the dust sealability evaluation test apparatus shown in FIG.

  In FIG. 9, 9 is a dust sealability evaluation test apparatus, 91 is a box, 92 is a pedestal, 93 is an evaluation box, 931 is a ceiling plate of the evaluation box, and 932 is an evaluation. 94 is an evaluation sample (frame-shaped double-sided adhesive tape), 95 is a particle counter, 96 is a suction pump, 97 is an evaluation box internal space, 98 Is an external space part of the evaluation box. In the dust sealability evaluation test apparatus 9, a system closed from the outside by a box 91 is obtained. A particle counter 95 is connected to the evaluation box outer space 97 inside the box 91. The evaluation box 93 is located on the pedestal 92. The evaluation box 93 is composed of an evaluation box ceiling plate 931 and an evaluation box body 932, has a hexahedral box structure, and has a square opening at the center of one surface. . Further, when this opening is covered with the ceiling plate 931 of the evaluation box, the evaluation box internal space 97 inside the evaluation box 93 can be made an independent system. In the evaluation box internal space 97, a suction pump 96 is connected, and a particle counter 95 is further connected. The evaluation sample 94 is arranged around the opening of the evaluation box body 932 in a form sandwiched between the ceiling plate 931 of the evaluation box and the evaluation box body 932. The evaluation box internal space portion 97 and the evaluation box external space portion 98 are partitioned by the evaluation sample 94, the ceiling plate 931 of the evaluation box, and the evaluation box main body 932. The thickness (gap) of the evaluation sample 94 is adjusted to be 0.12 mm.

As the particles, silica particles having an average particle diameter of 0.5 μm, silica particles having an average particle diameter of 1 μm, silica particles having an average particle diameter of 2 μm, and silica particles having an average particle diameter of 5 μm were used. The evaluation box internal space 97 was decompressed with the suction pump 96, the number of particles that passed through the evaluation sample 94 was determined, and the dust sealability was calculated from the following formula. The number of particles that have passed through the evaluation sample 94 is determined by the particle counter 95 by the number of particles in the evaluation box internal space portion 97 before and after the decompression operation and the evaluation box external space portion 98 before and after the decompression operation. It can be determined from the number of particles.
Dust sealability (%) = (P ₀ −P _f ) / P ₀ × 100
P ₀ : Number of particles in the evaluation box outer space 98 before the pressure reducing operation P _f : Passing through the evaluation sample 94 by the pressure reducing operation, the evaluation box outer space 98 passes through the evaluation box inner space 98 The number of particles moved to the portion 97. The closer the value of the dust sealability is to 100%, the better the dust sealability.
The measurement results of the dust sealability are shown in Table 9. In Table 9, “> 99” indicates a value exceeding 99%.
In Table 9, “-” indicates that measurement was not performed.

  The present invention relates to a double-sided pressure-sensitive adhesive tape that is a thin film and has excellent waterproof properties.

DESCRIPTION OF SYMBOLS 1 Polycarbonate plate 2 Window frame-shaped double-sided adhesive tape 3 Acrylic plate 4 Polycarbonate plate through-hole 21 Round bar 22 Support base 31 Polycarbonate plate 32 Window frame-shaped double-sided adhesive tape 33 Acrylic plate 41 Polycarbonate plate 42 Double-sided adhesive tape 43 Polyethylene terephthalate film 51 Polycarbonate plate 52 Double-sided adhesive tape 53 Polyester film a Floating distance 61 Polycarbonate plate 62 Step tape 63 Window frame-like double-sided adhesive tape 64 Acrylic plate 65 Non-woven fabric 7 Pendulum testing machine 71 Load cell 72 Measurement sample (double-sided adhesive tape)
73 Acrylic plate 74 Iron ball 75 Holding pressure adjusting means 76 Support plate 77 Support column 78 Support rod 8 Sample for evaluation 9 Dust seal property evaluation test apparatus 91 Box 92 Base 93 Evaluation box 931 Ceiling plate for evaluation box 932 Evaluation box Body body part 94 Evaluation sample (frame-shaped double-sided adhesive tape)
95 Particle counter 96 Suction pump 97 Internal space part for evaluation box 98 External space part for evaluation box

Claims (15)

An acrylic pressure-sensitive adhesive layer mainly composed of an acrylic polymer is provided on both surfaces of the foam substrate, and the acrylic polymer is composed of (meth) acrylic acid C _1-20 alkyl ester as a monomer main component. A double-sided pressure-sensitive adhesive tape, characterized in that the ratio of (meth) acrylic acid C _1-20 alkyl ester is 60% by weight or more based on the total amount of monomer components, and the total thickness is 200 μm or less.   The double-sided pressure-sensitive adhesive tape according to claim 1, wherein the tensile strength is 0.5 to 20 MPa.   The double-sided pressure-sensitive adhesive tape according to claim 1 or 2, wherein the elongation is 100 to 600%.   The double-sided pressure-sensitive adhesive tape according to claim 1, wherein the total thickness of the pressure-sensitive adhesive layers on both sides is 10 to 170 μm.   The double-sided pressure-sensitive adhesive tape according to any one of claims 1 to 4, wherein the 30% compression load is 5 to 200 kPa.   The double-sided pressure-sensitive adhesive tape according to any one of claims 1 to 5, wherein the pressing adhesive force is 30 to 200N.   The double-sided pressure-sensitive adhesive tape according to any one of claims 1 to 6, wherein the foam base material is a halogen-free foam base material that does not intentionally contain a halogen compound.   The double-sided pressure-sensitive adhesive tape according to any one of claims 1 to 7, wherein a chlorine-based gas generation amount is 50 µg / g or less.   The double-sided pressure-sensitive adhesive tape according to any one of claims 1 to 8, wherein the foam substrate is colored black.   The double-sided pressure-sensitive adhesive tape according to claim 9, wherein the visible light transmittance is 15% or less.   The double-sided pressure-sensitive adhesive tape according to any one of claims 1 to 8, wherein the foam substrate is colored white.   The double-sided pressure-sensitive adhesive tape according to claim 11, wherein the visible light reflectance is 20% or more.   The double-sided pressure-sensitive adhesive tape according to any one of claims 1 to 12, which is used for an optical member.   The double-sided pressure-sensitive adhesive tape according to any one of claims 1 to 13, which is used for waterproofing.   The double-sided pressure-sensitive adhesive tape according to any one of claims 1 to 14, wherein the double-sided pressure-sensitive adhesive tape is used for an adherend having an uneven shape or a curved surface portion.