JP6002253B2 - Waterproof double-sided adhesive tape for portable electronic devices - Google Patents

Description

  The present invention relates to a waterproof double-sided pressure-sensitive adhesive tape for portable electronic devices that is excellent in waterproofness and punchability.

  Conventionally, a double-sided pressure-sensitive adhesive tape has been used to fix and integrate members in various fields. In recent years, a waterproof function has been demanded in portable electronic devices such as mobile phones that are carried and used, and a double-sided adhesive tape that fixes and integrates members constituting the portable electronic device is also waterproof. It is requested.

  Patent Document 1 discloses a double-sided adhesive tape in which a pressure-sensitive adhesive layer is formed on both sides of a nonwoven fabric base material, the interlaminar fracture area ratio of the double-sided adhesive tape is 10% or less, and the tensile strength of the double-sided adhesive tape is A double-sided adhesive tape is disclosed in which both the MD direction (longitudinal direction) and the TD direction (lateral direction) are 20 N / 10 mm or more.

  However, the double-sided pressure-sensitive adhesive tape has insufficient waterproofness, and a double-sided pressure-sensitive adhesive tape having excellent waterproofness is desired.

In addition, as a waterproof double-sided pressure-sensitive adhesive tape for portable electronic devices, a double-sided pressure-sensitive adhesive tape in which a pressure-sensitive adhesive layer is laminated and integrated on both sides of a foamed sheet has also been proposed. A double-sided pressure-sensitive adhesive tape having a pressure-sensitive adhesive layer, which is used for fixing a component of a portable electronic device, has a thickness of 70 to 300 μm, and the foam base material is a polyolefin-based foam base material, A waterproof double-sided pressure-sensitive adhesive tape for portable electronic devices in which the foam substrate has a 25% compressive strength of 40 to 160 kPa and a tensile strength of 300 to 1500 N / cm ² has been proposed.

  On the other hand, in recent years, further downsizing of portable electronic devices has been demanded, and with the downsizing of portable electronic devices, double-sided adhesive tapes having a narrow width or a thin thickness are desired.

  However, if there are coarse bubbles in the foam original sheet, the cut surface of the bubbles is exposed and opened at the cut end face in the narrow part of the foam sheet obtained by cutting the foam original sheet, There is a problem in that the waterproof end of the waterproof double-sided pressure-sensitive adhesive tape for portable electronic devices may be impaired due to the state where the cut end faces of the foam sheet communicate with each other through coarse bubbles.

  Furthermore, in the production of the foam sheet, there is a possibility that partially coarse bubbles are formed, and as described above, even if the cross section of the bubbles is not exposed and opened on the cut end surface of the foam sheet, There may be a state in which the foam sheet exists. In this way, the foamed sheet portion in which coarse air bubbles are present has low elastic recovery and mechanical strength, the adhesion to the adherend is reduced, or the foamed sheet breaks during use. Thus, there is a problem that the waterproofness of the waterproof double-sided pressure-sensitive adhesive tape for portable electronic devices is lowered.

  In addition, since the foam sheet is manufactured by foaming a foam material, the thickness accuracy is low. The thinner the waterproof double-sided adhesive tape for portable electronic devices, the less the foam sheet thickness. The effect of uniformity on the waterproofness of waterproof double-sided adhesive tape for portable electronic devices is large. The thinner the waterproof double-sided adhesive tape for portable electronic devices, the more accurate the waterproofness of the waterproof double-sided adhesive tape for portable electronic devices. Has the problem of lowering.

  Further, as described above, since the foam sheet is manufactured by foaming a foam having a foaming property, there is a limit to reducing the thickness of the foam sheet, and waterproof double-sided adhesive for portable electronic devices. There is a problem that thinning of the tape is insufficient.

  In addition, in order to achieve miniaturization of portable electronic devices in recent years, it is necessary to improve the dimensional accuracy of each member. About the double-sided adhesive tape that integrates the members constituting the portable electronic device However, improvement in dimensional accuracy is also required. The double-sided pressure-sensitive adhesive tape is usually used after being punched into a desired shape, and an improvement in dimensional accuracy is required for the punched double-sided pressure-sensitive adhesive tape.

JP 2001-152111 A Japanese Patent No. 4623198

  The present invention provides a waterproof double-sided pressure-sensitive adhesive tape for portable electronic devices that has excellent waterproofness and punching workability without causing problems as in the case of using a foam sheet for a base material layer.

  The waterproof double-sided pressure-sensitive adhesive tape A for portable electronic devices of the present invention is provided with heat on both sides of a non-foamed first synthetic resin layer 1 containing at least one synthetic resin selected from the group consisting of polyolefin resins and polyester resins. A base material layer 4 in which a non-foamed second synthetic resin layer 2 and 2 containing at least one synthetic resin selected from the group consisting of a plastic elastomer and a rubber-based resin are laminated and integrated; and the base material layer 4 The pressure-sensitive adhesive layers 3 and 3 are laminated and integrated on both sides.

  The first synthetic resin layer 1 constituting the waterproof double-sided pressure-sensitive adhesive tape A for portable electronic devices is non-foamed and contains at least one synthetic resin selected from the group consisting of polyolefin resins and polyester resins. It is preferable that a polyester resin is contained.

  The polyolefin resin is not particularly limited, and examples thereof include a polyethylene resin and a polypropylene resin. Examples of the polyethylene resin include a low density polyethylene resin, a medium density polyethylene resin, a high density polyethylene resin, and a linear low density polyethylene resin, which may be used alone or in combination. .

  Examples of polypropylene resins include propylene homopolymers and copolymers of propylene and other olefins containing more than 50% by weight of the propylene component. May be. Further, the copolymer of propylene and other olefins may be a block copolymer or a random copolymer.

  Examples of the olefin copolymerized with propylene include α such as ethylene, 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-octene, 1-nonene and 1-decene. -Olefin and the like.

  Examples of the polyester-based resin include polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate, and polyethylene terephthalate is preferable.

  As shown in FIG. 1, on both surfaces of the first synthetic resin layer 1, a non-foamed material containing at least one synthetic resin selected from the group consisting of a thermoplastic elastomer and a rubber resin, preferably a rubber resin, is used. The second synthetic resin layers 2 and 2 are laminated and integrated to form a base material layer 4, and the second synthetic resin layer 2 is elastically deformed so that the portable electronic device is along the surface shape of the adherend. The waterproof double-sided pressure-sensitive adhesive tape is attached in a watertight state, and waterproofness is imparted between the members joined through the waterproof double-sided pressure-sensitive adhesive tape for portable electronic devices.

  Furthermore, even when the adherend is deformed or displaced after the waterproof double-sided adhesive tape for portable electronic devices is attached to the adherend, the second synthetic resin layer 2 is adhered by elastic deformation. It absorbs the deformation or displacement of the body, and the waterproofness between the members joined via the waterproof double-sided adhesive tape for portable electronic devices is reliably maintained.

  The thermoplastic elastomer is not particularly limited, and examples thereof include polyurethane-based thermoplastic elastomers, polyester-based thermoplastic elastomers, polyolefin-based thermoplastic elastomers, PVC-based thermoplastic elastomers, polyamide-based thermoplastic elastomers, and the like. A plastic elastomer is preferable, and a polyester polyurethane thermoplastic elastomer is more preferable. In addition, a thermoplastic elastomer may be used independently or 2 or more types may be used together. The thermoplastic elastomer may be cross-linked. The thermoplastic elastomer may be cross-linked by any method as long as it is a reaction that connects two or more molecular chains or the same molecular chain with chemical bonds or physical crosslinks. Examples include a method of crosslinking by adding a crosslinking agent such as an organic peroxide to the thermoplastic elastomer, and a method of irradiating the thermoplastic elastomer with radiation such as an electron beam. A vulcanization accelerator and a silane coupling agent are used in combination. You can also.

  There are two types of polyurethane-based thermoplastic elastomers: an incomplete thermoplastic type having partial crosslinking in the molecule, and a complete thermoplastic type that is a completely linear polymer. The incomplete thermoplastic type is excellent in heat resistance, chemical resistance and mechanical strength.

  Polyurethane-based thermoplastic elastomers include (1) caprolactone type obtained by addition polymerization of polyisocyanate in the presence of short-chain polyol to polylactone ester polyol obtained by ring-opening caprolactone, (2) adipic acid and glycol Polyester-based polyurethane thermoplastic elastomers such as adipic acid type (adipate type) obtained by addition polymerization of polyisocyanate in the presence of a short-chain polyol with adipic ester polyol and (3) ring-opening polymerization of tetrahydrofuran Polytetramethylene glycol (PTMG) is a PTMG type (ether type) polyurethane-based thermoplastic elastomer obtained by addition polymerization of polyisocyanate in the presence of a short-chain polyol.

  A polyester-based polyurethane-based thermoplastic elastomer is commercially available from BASF under the trade name “Elastolan NY585”. Polyether-based polyurethane-based thermoplastic elastomers are commercially available from BASF under the trade names “Elastolan NY90A” and “Elastolan NY97A”. Polyurethane thermoplastic elastomers are: Asahi Glass, Kyowa Hakko, Kuraray, Sanyo Kasei, Sumitomo Bayer Urethane, Dainichi Seika, Dow Chemical, Milactone, Nippon Polyurethane, Dainippon Ink , Takeda Pharmaceutical, Toyobo, Nisshinbo, Hokushin Chemical and others.

  Examples of the polyester-based thermoplastic elastomer include, for example, an aromatic polyester having a high melting point and a high crystallinity in the hard segment, such as polybutylene terephthalate (PBT), and an amorphous polycrystal having a glass transition temperature of −70 ° C. in the soft segment. Examples include ethers such as multi-block polymers using polytetramethylene ether glycol (PTMG).

  Polyester-based thermoplastic elastomers are commercially available from Toyobo Co., Ltd., Toray DuPont, Dainippon Ink Chemical Co., Japan Easy Plastics, and others.

  The polyolefin-based thermoplastic elastomer is a mixture in which a thermoplastic crystalline polyolefin such as polypropylene or polyethylene is used for a hard segment, and a fully vulcanized or partially vulcanized rubber is used for a soft segment. The thermoplastic crystalline polyolefin is, for example, an α-olefin homopolymer having 1 to 4 carbon atoms or a copolymer of two or more types, and preferably polyethylene or polypropylene. Examples of the soft segment component include butyl rubber, halobutyl rubber, EPDM, EPR rubber, acrylonitrile / butadiene rubber, NBR, and natural rubber.

  Polyolefin thermoplastic elastomers are available from Sumitomo Chemical, Mitsui Petrochemical, Nippon Synthetic Rubber, Mitsubishi Yuka, Nippon Petrochemical, Tonen Chemical, Monsanto, Advanced Elastomer Systems, LP It is commercially available.

  An example of the polyamide-based thermoplastic elastomer is a block copolymer in which a polyamide such as nylon is used as a hard segment, and a polyester or polyol is used as a soft segment.

  Polyamide-based thermoplastic elastomers are commercially available from Ube Industries, Daicel Huls, Toray, Mitsubishi Kasei, Dainippon Ink and Chemicals.

  The rubber-based resin is not particularly limited as long as it has rubber elasticity at room temperature. Examples of rubber resins include chloroprene rubber (CR), isoprene rubber (IR), butyl rubber (IIR), nitrile-butadiene rubber (NBR), natural rubber, styrene-butadiene copolymer rubber (SBR), and butadiene rubber (BR). ), Urethane rubber, fluorine rubber, acrylic rubber, ethylene-propylene copolymer rubber, ethylene-propylene-diene copolymer rubber, urethane rubber, silicone rubber and the like. The rubber-based resin is excellent in cushioning and durability of the rubber-based resin sheet, so that the rubber-based resin is nitrile-butadiene rubber (NBR), styrene-butadiene copolymer rubber (SBR), butyl rubber (IIR), chloroprene rubber (CR). Is preferred. The rubber-based resins having rubber elasticity at room temperature may be used alone or in combination of two or more. In the present invention, nitrile-butadiene rubber (NBR) contains rubber called nitrile rubber. In the present invention, the styrene-butadiene copolymer rubber (SBR) also contains a rubber called a styrene rubber. The rubber-based resin may be cross-linked. The crosslinking of the rubber-based resin may be any method as long as it is a reaction that connects two or more molecular chains or the same molecular chain with chemical bonds or physical cross-links. Examples include crosslinking by adding a crosslinking agent such as an organic peroxide to the rubber resin, and irradiating the rubber resin with radiation such as an electron beam. A vulcanization accelerator and a silane coupling agent are used in combination. You can also.

  As described above, since the base material layer 4 is configured by laminating and integrating the non-foamed second synthetic resin layer on both surfaces of the non-foamed first synthetic resin layer, the base material layer 4 is composed of a foam sheet. Compared to the above, the base material layer 4 is excellent in thickness accuracy, and the surface of the base material layer 4 is also excellent in smoothness.

  Accordingly, a gap is generated between the adherend to which the waterproof double-sided pressure-sensitive adhesive tape for portable electronic devices of the present invention is attached (hereinafter simply referred to as “the adherend”) and the waterproof double-sided adhesive tape for portable electronic devices. As a result, the waterproof double-sided pressure-sensitive adhesive tape for portable electronic devices can be attached to the adherends, and excellent waterproofness can be imparted between the adherends.

  In the state where the waterproof double-sided pressure-sensitive adhesive tape for portable electronic devices of the present invention is adhered to the adherend, the second synthetic resin layer mainly deforms along the surface of the adherend, thereby the adherend. The waterproof double-sided pressure-sensitive adhesive tape for portable electronic devices is prevented from forming a gap and is waterproof.

  That is, in the waterproof double-sided pressure-sensitive adhesive tape for portable electronic devices of the present invention, one second synthetic resin layer is deformed along the shape of the adherend adhered to one second synthetic resin layer, and the other When the other second synthetic resin layer is deformed along the shape of the adherend adhered to the second synthetic resin layer, the gap between the two adherends is a waterproof double-sided adhesive tape for portable electronic devices. Waterproofing is given by being watertightly closed by.

  The second synthetic resin layer is deformed by the pressing force of the adherend pressed against the second synthetic resin layer. At this time, the second synthetic resin layer is opposite to the face in contact with the adherend. Is received by the first synthetic resin layer, so that the second synthetic resin layer reliably receives the pressing force by the adherend and is in a state along the surface of the adherend. The waterproof double-sided adhesive tape for portable electronic devices adheres to the surface of the adherend without causing a gap between the adherend and the waterproof double-sided adhesive tape for portable electronic devices. Sex is imparted.

  And as above-mentioned, as for the 2nd synthetic resin layer, the surface on the opposite side to the surface which contacts a to-be-adhered body is received by the 1st synthetic resin layer, and the pressing force received from a to-be-adhered body is small. Even in some cases, it can be easily deformed. Therefore, even if the thickness of the second synthetic resin layer is reduced and the deformation tolerance of the second synthetic resin layer is reduced, the surface shape of the adherend is maintained. Can be deformed accurately. Furthermore, since the second synthetic resin layer is a non-foamed sheet, even if the thickness thereof is reduced, the waterproof property is not deteriorated due to exposure of the cut end faces of the bubbles as in the case of the foamed sheet. Therefore, the waterproof double-sided pressure-sensitive adhesive tape for portable electronic devices of the present invention can exhibit excellent waterproofness even if its thickness is reduced.

  Furthermore, since the waterproof double-sided pressure-sensitive adhesive tape for portable electronic devices of the present invention can reduce the thickness of the second synthetic resin layer, it is transformed into a waterproof double-sided pressure-sensitive adhesive tape for portable electronic devices after being disposed at a desired location. Even when a deformation stress is applied, the second synthetic resin layer is not excessively deformed, and the waterproof double-sided adhesive tape for portable electronic devices is disposed at a desired location to reliably maintain waterproofness. Can do.

  Moreover, the waterproof double-sided pressure-sensitive adhesive tape for portable electronic devices of the present invention is usually used after being punched into a desired shape according to the place where it is disposed. When punching waterproof double-sided adhesive tape for portable electronic devices, the cutting blade enters one second synthetic resin layer in the thickness direction, but as described above, the second synthetic resin layer is received by the first synthetic resin layer. Therefore, the cutting blade can easily enter the second synthetic resin layer to accurately cut the second synthetic resin layer. When a waterproof double-sided adhesive tape for portable electronic devices is stamped, the waterproof double-sided adhesive tape for portable electronic devices is usually placed on a hard mounting surface, and waterproof double-sided adhesive tape for portable electronic devices. The other second synthetic resin layer of the tape is accurately cut by the cutting blade while being received on the mounting surface.

  Therefore, the waterproof double-sided pressure-sensitive adhesive tape for portable electronic devices of the present invention is used after being cut into a desired shape easily and accurately by punching, and the waterproof part is reliably waterproofed with the waterproof double-sided adhesive tape for portable electronic devices. can do.

  Since the first synthetic resin layer 1 and the second synthetic resin layer 2 constituting the base material layer 4 of the waterproof double-sided pressure-sensitive adhesive tape for portable electronic devices of the present invention are non-foamed sheets, air bubbles ( There is no foam cell), no coarse bubbles are present inside, and the base material layer 4 is formed substantially uniformly in elastic recovery and mechanical strength as a whole. Therefore, the waterproof double-sided pressure-sensitive adhesive tape for portable electronic devices of the present invention can be uniformly and reliably adhered to the adherend as a whole, and exhibits excellent waterproofness.

  Furthermore, since the base material layer of the waterproof double-sided pressure-sensitive adhesive tape for portable electronic devices does not have air bubbles (foamed cells) as described above, it has a sufficient mechanical strength with a substantially uniform overall, The base material layer of waterproof double-sided pressure-sensitive adhesive tape for portable electronic devices may be damaged even when impact force is applied to the adherend bonded and integrated via the waterproof double-sided pressure-sensitive adhesive tape for portable electronic devices. In spite of the impact force from the outside, the adherends can be reliably joined and integrated in a state where waterproofness is ensured by the waterproof double-sided adhesive tape for portable electronic devices.

  In addition, waterproof double-sided adhesive tapes for portable electronic devices are used internally in small portable electronic devices such as mobile phones and portable electronic terminals to provide waterproofness. These waterproof double-sided adhesive tapes for portable electronic devices are electronic devices. Since the terminal itself is small, a narrow one is used. Since there are no air bubbles in the base material layer, even if the width of the base material layer is narrowed, the width between the end faces in the width direction of the base material layer is the base material layer as in the case where the base material layer is a foamed sheet. Therefore, the waterproof double-sided pressure-sensitive adhesive tape for portable electronic devices of the present invention can maintain excellent waterproofness even if the width thereof is narrowed. It can be suitably used for imparting waterproofness to equipment. If the width of the waterproof double-sided pressure-sensitive adhesive tape for portable electronic devices of the present invention is too narrow, there will be no problem with the initial waterproof property of the waterproof double-sided pressure-sensitive adhesive tape for portable electronic devices. Since waterproofness may fall when used over it, 0.5-2 mm is preferable.

  If the thickness of the first synthetic resin layer 1 is thin, the first synthetic resin layer cannot sufficiently receive the second synthetic resin layer. If the synthetic resin layer is deformed excessively, the waterproof double-sided adhesive tape for portable electronic devices may not be punched into the desired shape.If it is thick, the rigidity of the first synthetic resin layer is increased, and the first synthetic resin layer is not covered. The followability with respect to the surface of the adherend is reduced, and as a result, the followability with respect to the surface shape of the adherend of the second synthetic resin layer laminated and integrated on the first synthetic resin layer is also reduced and waterproof. May decrease, the thickness is preferably 5 to 38 μm, more preferably 10 to 25 μm.

  If the thickness of the second synthetic resin layer 2 is thin, the second synthetic resin layer cannot be sufficiently deformed along the surface shape of the adherend, and the waterproof double-sided adhesive tape for portable electronic devices is waterproof. If the second synthetic resin layer is subjected to deformation stress, the second synthetic resin layer is excessively deformed and the waterproof double-sided adhesive tape for portable electronic devices is disposed. The second synthetic resin layer may be excessively deformed when punching the waterproof double-sided adhesive tape for portable electronic devices, and the waterproof double-sided adhesive tape for portable electronic devices cannot be punched into the desired shape. Therefore, 5 to 100 μm is preferable, and 10 to 60 μm is more preferable.

  If the ratio between the thickness of each of the second synthetic resin layers 2 and 2 and the thickness of the first synthetic resin layer 1 (second synthetic resin layer / first synthetic resin layer) is small, the second synthetic resin layer is covered. It cannot be sufficiently deformed along the surface shape of the sticking body, and the waterproofness of the waterproof double-sided pressure-sensitive adhesive tape for portable electronic devices may decrease. If it is large, a deformation stress is applied to the second synthetic resin layer. In some cases, the second synthetic resin layer may be excessively deformed to adversely affect the vicinity of the space where the waterproof double-sided adhesive tape for portable electronic devices is disposed, or Since the second synthetic resin layer may be excessively deformed during punching and the waterproof double-sided adhesive tape for portable electronic devices may not be punched into a desired shape, 0.9 to 9.5 is preferable, and 1.3 to 4 is preferable. Is more preferable.

  The first synthetic resin layer and the second synthetic resin layer contain additives such as a filler, an ultraviolet absorber, a light stabilizer, an antistatic agent, a pigment, and a dye as long as the physical properties are not impaired. It may be. Each of the surfaces of the first synthetic resin layer and the second synthetic resin layer may be subjected to surface treatment such as corona discharge treatment.

  Next, the manufacturing method of a base material layer is demonstrated. The method for producing the base material layer is not particularly limited.For example, (1) a non-foamed first synthetic resin sheet containing at least one synthetic resin selected from the group consisting of polyolefin resins and polyester resins, and A non-foamed second synthetic resin sheet containing at least one synthetic resin selected from the group consisting of a thermoplastic elastomer and a rubber-based resin is produced in a general manner, and second on both sides of the first synthetic resin sheet. A method of producing a base material layer by laminating and integrating synthetic resin sheets by thermal fusion; (2) a non-foamed first material containing at least one synthetic resin selected from the group consisting of polyolefin resins and polyester resins; A synthetic resin sheet is manufactured in a general-purpose manner, and on both sides of the first synthetic resin sheet, at least selected from the group consisting of a thermoplastic elastomer and a rubber-based resin. A method of producing a base material layer by extrusion laminating a non-foamed second synthetic resin layer containing a kind of synthetic resin, (3) at least one kind of synthesis selected from the group consisting of polyolefin resin and polyester resin A composition for a first synthetic resin containing a resin is supplied to a first extruder and melt-kneaded in the absence of a foaming agent, and at least one selected from the group consisting of a thermoplastic elastomer and a rubber-based resin. A composition for a second synthetic resin containing a synthetic resin is supplied to a second extruder, melt-kneaded in the absence of a foaming agent, and a coextrusion die connecting the first and second extruders together. By supplying and coextruding the first synthetic resin composition and the second synthetic resin composition, the second synthetic resin composition is formed on both sides of the first synthetic resin layer comprising the first synthetic resin composition. Second synthetic resin layer (4) A non-foamed first synthetic resin sheet containing at least one synthetic resin selected from the group consisting of polyolefin-based resins and polyester-based resins. On the other hand, a coating solution is prepared by dissolving at least one synthetic resin selected from the group consisting of a thermoplastic elastomer and a rubber-based resin in a solvent, and this coating solution is applied to both surfaces of the first synthetic resin sheet. Examples thereof include a method for producing a base material layer by coating and drying.

  In the waterproof double-sided pressure-sensitive adhesive tape A for portable electronic devices of the present invention, pressure-sensitive adhesive layers 3 and 3 are laminated and integrated on both surfaces of the base material layer 4. In addition, it is preferable that at least one surface, preferably both surfaces, of the second synthetic resin layers 2 and 2 of the base material layer 4 are subjected to a surface treatment in order to improve adhesion to the pressure-sensitive adhesive layer. Examples of the surface treatment include corona discharge treatment, chromic acid treatment, ozone exposure treatment, flame exposure treatment, high piezoelectric impact exposure treatment, oxidation treatment such as ionizing radiation treatment, and coating treatment with a primer or a release agent.

  The pressure-sensitive adhesive constituting 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. Agents, polyurethane pressure-sensitive adhesives, fluorine-based pressure-sensitive adhesives, epoxy-based pressure-sensitive adhesives, etc., and acrylic pressure-sensitive adhesives are preferred. In addition, an adhesive may be used independently or 2 or more types may be used together.

  The acrylic pressure-sensitive adhesive is not particularly limited, but a (meth) acrylic acid alkyl ester is an essential monomer component (monomer main component), and if necessary, a copolymerizable monomer (with polar group) And a pressure-sensitive adhesive having an acrylic polymer obtained by polymerizing or copolymerizing a monomer or a polyfunctional monomer as a base polymer (main component). The polymerization method may be a general-purpose method, and is not particularly limited, and examples thereof include a UV polymerization method, a solution polymerization method, and an emulsion polymerization method. In addition, (meth) acrylic acid means acrylic acid or methacrylic acid.

  Examples of the (meth) acrylic acid alkyl ester include, for example, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, butyl (meth) acrylate, (meth) Isobutyl acrylate, s-butyl (meth) acrylate, t-butyl (meth) acrylate, pentyl (meth) acrylate, isopentyl (meth) acrylate, hexyl (meth) acrylate, heptyl (meth) acrylate, Octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isooctyl (meth) acrylate, nonyl (meth) acrylate, isononyl (meth) acrylate, decyl (meth) acrylate, isodecyl (meth) acrylate , Undecyl (meth) acrylate, dodecyl (meth) acrylate, ( T) Decyl acrylate, tetradecyl (meth) acrylate, pentadecyl (meth) acrylate, hexadecyl (meth) acrylate, heptadecyl (meth) acrylate, octadecyl (meth) acrylate, nonadecyl (meth) acrylate, (meta ) Eicosyl acrylate.

  Since the (meth) acrylic acid alkyl ester is used as the main monomer component of the acrylic polymer, the proportion of the (meth) acrylic acid alkyl ester is, for example, 60% with respect to the total amount of monomer components for preparing the acrylic polymer. % By weight or more is preferable, and 80% by weight or more is more preferable.

  The acrylic polymer may contain various copolymerizable monomers such as polar group-containing monomers and polyfunctional monomers as monomer components. By containing the 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 may be used independently or 2 or more types may be used together.

  Examples of polar group-containing monomers include (meth) acrylic acid, itaconic acid, maleic acid, fumaric acid, crotonic acid, isocrotonic acid, and other carboxyl group-containing monomers or anhydrides thereof (such as maleic anhydride); (meth) acrylic Hydroxyl-containing monomers such as hydroxyalkyl (meth) acrylates such as hydroxyethyl acid, hydroxypropyl (meth) acrylate, and hydroxybutyl (meth) acrylate; acrylamide, methacrylamide, N, N-dimethyl (meth) acrylamide, N Amide group-containing monomers such as methylol (meth) acrylamide, N-methoxymethyl (meth) acrylamide, N-butoxymethyl (meth) acrylamide; aminoethyl (meth) acrylate, dimethylaminoethyl (meth) acrylate, (meta ) Amino group-containing monomers such as t-butylaminoethyl crylate; 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- In addition to 2-pyrrolidone and (meth) acryloylmorpholine, N-vinylpyridine, N-vinylpiperidone, N-vinylpyrimidine, N-vinylpiperazine, N-vinylpyrrole, N-vinylimidazole, N-vinyloxazole, and other heterocyclic rings Vinyl monomers; (meth) acrylic acid alkoxyalkyl monomers such as (meth) acrylic acid methoxyethyl and (meth) acrylic acid ethoxyethyl; sulfonic acid group-containing monomers such as sodium vinyl sulfonate; Phosphoric acid group-containing monomers such as Le acryloyl phosphate; cyclohexyl maleimide, imide group-containing monomers such as isopropyl maleimide; an isocyanate group-containing monomers such as 2-methacryloyloxyethyl isocyanate.

  Examples of the multifunctional monomer include hexanediol di (meth) acrylate, butanediol di (meth) acrylate, (poly) ethylene glycol di (meth) acrylate, (poly) propylene glycol di (meth) acrylate, and neopentyl glycol. Di (meth) acrylate, pentaerythritol di (meth) acrylate, pentaerythritol tri (meth) acrylate, dipentaerythritol hexa (meth) acrylate, trimethylolpropane tri (meth) acrylate, tetramethylolmethane tri (meth) acrylate, allyl Examples include (meth) acrylate, vinyl (meth) acrylate, divinylbenzene, epoxy acrylate, polyester acrylate, and urethane acrylate.

  The acrylic polymer may contain a copolymerizable monomer in addition to the polar group-containing monomer and the polyfunctional monomer. Examples of such a copolymerizable monomer include vinyl acetate and vinyl propionate. Esters; aromatic vinyl compounds such as styrene and vinyltoluene; olefins or dienes such as ethylene, butadiene, isoprene and isobutylene; vinyl ethers such as vinyl alkyl ether; vinyl chloride and the like.

  The pressure-sensitive adhesive layer may appropriately contain additives within a range that does not impair the physical properties. Examples of additives include tackifiers such as rosin derivative resins, polyterpene resins, petroleum resins and oil-soluble phenol resins, plasticizers, fillers, anti-aging agents, antioxidants, pigments and dyes such as carbon black, and the like. A coloring agent etc. are mentioned. The pressure-sensitive adhesive layer may be crosslinked with a general-purpose crosslinking agent such as an aziridine-based crosslinking agent, an epoxy-based crosslinking agent, or an isocyanate-based crosslinking agent.

  The method for producing a waterproof double-sided pressure-sensitive adhesive tape for portable electronic devices by laminating and integrating a pressure-sensitive adhesive layer on both surfaces of a non-foamed base material layer is not particularly limited. For example, a pressure-sensitive adhesive such as an acrylic pressure-sensitive adhesive is ethyl acetate. The adhesive layer solution obtained by stirring until uniform in a solvent such as is coated on both sides of the substrate layer in a general manner and then dried to adhere to both sides of the substrate layer A method for producing a waterproof double-sided pressure-sensitive adhesive tape for portable electronic devices by laminating and integrating the agent layers, and (2) the above-mentioned pressure-sensitive adhesive on the release treatment surface of the synthetic resin film which has been subjected to release treatment by a general-purpose coating method By applying the layer solution and drying, a pressure-sensitive adhesive layer is formed on the synthetic resin film, and this pressure-sensitive adhesive layer is transferred to both sides of the base material layer and laminated together to provide waterproof both sides for portable electronic devices. For example, how to manufacture adhesive tape It is.

  If the thickness of the pressure-sensitive adhesive layer is thin, the adhesiveness of the waterproof double-sided pressure-sensitive adhesive tape for portable electronic devices may be reduced and the waterproof property may be reduced. If the thickness is thick, the waterproof property may be impaired. Is preferable, and 15 to 65 μm is more preferable.

  Waterproof double-sided adhesive tape for portable electronic devices is required to be thin, but if the overall thickness of waterproof double-sided adhesive tape for portable electronic devices is too thin, the waterproof double-sided adhesive tape for portable electronic devices adheres to the adherend. However, the waterproof property of the waterproof double-sided pressure-sensitive adhesive tape for portable electronic devices may be reduced, so that it is preferably 35 to 400 μm, more preferably 80 to 200 μm.

  In addition, a primer layer, a colored layer, etc. may interpose between each layer of the waterproof double-sided adhesive tape for portable electronic devices.

  Next, the point of use of the waterproof double-sided pressure-sensitive adhesive tape for portable electronic devices of the present invention will be described. The waterproof double-sided pressure-sensitive adhesive tape for portable electronic devices of the present invention is used to integrate members constituting the portable electronic device, and any member may be integrated, as described below. The waterproof double-sided pressure-sensitive adhesive tape for portable electronic devices is preferably used for constituting the liquid crystal display module unit B.

  As shown in FIG. 2, the backlight housing 5 is formed in a rectangular frame shape made of synthetic resin, and has a flat rectangular frame-like panel arrangement stage for placing a liquid crystal display panel on the upper end portion. The portion 51 is formed in an open state on the upper end surface of the backlight housing 5, and the reflector mounting step 52 for disposing the reflector plate is opened in the lower end surface at the lower end portion. It is formed in a planar rectangular frame shape.

  A flat rectangular liquid crystal display panel 6 having a size slightly smaller than the upper end opening of the backlight housing 5 is disposed on the panel placement step 51 of the backlight housing 5. In addition, a plurality of optical films are disposed in the backlight housing 5 in a state of being stacked on each other.

  Specifically, the light guide plate 7, the diffusion sheet 8, and one or a plurality of prism sheets 9, 9... For improving luminance are laminated in this order, and then the prism sheet 9 is formed. The prism sheet 9 is disposed in the backlight housing 5 so as to face the liquid crystal display panel 6 and to be substantially flush with the panel receiving surface 51a of the panel disposition step 51. In addition, optical films other than the above may be appropriately laminated.

  In addition, the reflector 10 is disposed and integrated with the reflector arrangement step 52 of the backlight casing 5, and an LED (not shown) is disposed in the backlight casing 5 as a light source. Has been.

  The liquid crystal display panel 6 and the prism sheet 9 facing the liquid crystal display panel 6 are integrated through a known double-sided adhesive tape C.

  The double-sided adhesive tape C is disposed on the panel receiving step 51 of the backlight housing 5 in a state of being disposed on the panel receiving surface 51a of the panel disposing step 51 of the backlight housing 5. The entire width of the width dimension from the inner periphery of the panel receiving surface 51a to the outer periphery of the prism sheet 9 disposed in the opening surrounded by the panel receiving surface 51a of the panel mounting step 51 is The panel receiving surface 51a of the step for disposing the panel of the backlight housing 5 and the prism sheet 9 and the liquid crystal display panel 6 are disposed on both sides of the panel through the double-sided adhesive tape C. Sticking is integrated.

  In the above description, the optical film facing the liquid crystal display panel 6 is described as the prism sheet 9. However, the optical film facing the liquid crystal display panel 6 is not necessarily a prism sheet, and other optical films may be used. Good.

  Further, a waterproof double-sided pressure-sensitive adhesive tape A for portable electronic devices, which is punched into a rectangular frame shape, is attached to and integrated with a single adhesive layer 3 on the upper end opening end surface of the backlight housing 5. A transparent protective plate 11 is laminated and integrated through the other pressure-sensitive adhesive layer 3 of the waterproof double-sided pressure-sensitive adhesive tape A for equipment to constitute a liquid crystal display module unit B.

  As described above, the waterproof double-sided pressure-sensitive adhesive tape for portable electronic devices is used after being punched into a desired shape in advance depending on the location where the waterproof double-sided adhesive tape for portable electronic devices is used. Therefore, the liquid crystal display module unit B can be accurately disposed in a predetermined position without impairing the visibility of the liquid crystal display panel 6. The transparent protective plate 11 can be disposed and integrated above the liquid crystal display panel 6 via the waterproof double-sided adhesive tape A for portable electronic devices.

  When the transparent protective plate 11 is disposed on the upper end opening end surface of the backlight housing 5 via the waterproof double-sided adhesive tape A for portable electronic devices, the waterproof double-sided adhesive tape A for portable electronic devices has a thickness direction. Although the pressing force is applied, the waterproof double-sided adhesive tape A for portable electronic devices, particularly the second synthetic resin layer, is greatly deformed by the pressing force and protrudes above the liquid crystal display panel 6 to obstruct the visibility of the liquid crystal display panel 6. There is nothing to do.

  Further, even when the liquid crystal display module unit B is in use, pressing force may be applied in the thickness direction to the waterproof double-sided adhesive tape A for portable electronic devices via the transparent protective plate 11. However, the waterproof double-sided pressure-sensitive adhesive tape A for portable electronic devices, particularly the second synthetic resin layer, is greatly deformed and does not protrude above the liquid crystal display panel 6 and impair the visibility of the liquid crystal display panel 6. The visibility of the panel 6 can be stably maintained over a long period of time.

  Since the waterproof double-sided pressure-sensitive adhesive tape for portable electronic devices of the present invention has the configuration as described above, it is excellent in punching workability and can be used after being accurately punched into a desired shape. It can adhere | attach well on the surface of a kimono body and can provide the waterproof property excellent in the required location.

It is the longitudinal cross-sectional view which showed the waterproof double-sided adhesive tape for portable electronic devices of this invention. It is the liquid crystal display module unit comprised using the waterproof double-sided adhesive tape for portable electronic devices of this invention. It is the top view which showed the test piece produced in the waterproof test. It is the longitudinal cross-sectional view which showed the test body produced in the waterproof test.

  Next, examples of the present invention will be described, but the present invention is not limited to the following examples.

(Examples 1-2, Comparative Example 4)
Monomer and adhesive containing 60 parts by weight of butyl acrylate, 3 parts by weight of acrylic acid and 37 parts by weight of 2-ethylhexyl acrylate in a 2 liter separable flask equipped with a stirrer, a cooler, a thermometer and a nitrogen gas inlet A reaction solution consisting of 5 parts by weight of an imparting agent (trade name “Arcon A100” manufactured by Arakawa Chemical Co., Ltd.) and 5 parts by weight of ethyl acetate was added, and dissolved oxygen was removed by bubbling with nitrogen gas for 30 minutes. Nitrogen gas was substituted, and the temperature of the reaction solution was raised to 120 ° C. in an oil bath while stirring the reaction solution. When the reaction solution reaches 120 ° C., the monomer is added while adding a polymerization initiator solution prepared by dissolving 0.15 parts by weight of benzoyl peroxide in 1.35 parts by weight of cyclohexane over 6 hours. After the polymerization was completed, ethyl acetate was further added to the reaction solution to prepare an acrylic pressure-sensitive adhesive solution.

  Next, a polyethylene terephthalate film whose one surface was release-treated was prepared, and the acrylic pressure-sensitive adhesive solution was applied to the release-treated surface of the polyethylene terephthalate film so that the thickness after drying was 50 μm at 110 ° C. It was dried for 5 minutes to prepare a laminated sheet in which a pressure-sensitive adhesive layer made of an acrylic pressure-sensitive adhesive was laminated on the release treatment surface of the polyethylene terephthalate film. A total of two laminated sheets were produced in the same manner.

  Meanwhile, one polyethylene terephthalate sheet having a certain thickness was prepared, and two nitrile-butadiene rubber (NBR) sheets having a certain thickness were prepared.

  Next, a nitrile-butadiene rubber (NBR) sheet is laminated on each of both surfaces of the polyethylene terephthalate sheet to produce a laminate, and the laminate is pressed in the thickness direction while being heated to 40 ° C. A non-foamed nitrile-butadiene rubber (NBR) sheet was laminated and integrated on both surfaces of a polyethylene terephthalate sheet to prepare a base material layer. In the base material layer, the thickness of the first synthetic resin layer made of a polyethylene terephthalate sheet and the thickness of the second synthetic resin layer made of a nitrile-butadiene rubber (NBR) sheet were as shown in Table 1.

  One laminate sheet is laminated on one surface of the base material layer so that the pressure-sensitive adhesive layer faces the base material layer, and the pressure-sensitive adhesive layer is transferred to the base material layer to be integrated and laminated. Laminate the other laminated sheet on the other side so that the pressure-sensitive adhesive layer faces the base material layer, transfer the pressure-sensitive adhesive layer to the base material layer, and integrate the layers together. Obtained a waterproof double-sided pressure-sensitive adhesive tape for portable electronic devices in which a 20 μm pressure-sensitive adhesive layer was laminated and integrated.

(Example 3 )
Waterproof double-sided adhesive for portable electronic devices in the same manner as in Example 1 except that a polyurethane-based thermoplastic elastomer sheet (trade name “Elastolan S80A” manufactured by BASF) was used instead of the nitrile-butadiene rubber (NBR) sheet. I got a tape.

(Comparative Example 1)
Polyurethane thermoplastic elastomer sheet (trade name “Elastolan S95A” manufactured by BASF) was supplied to an extruder, melted and kneaded, extruded from a T-die attached to the tip of the extruder, and a polyurethane thermoplastic elastomer sheet having a thickness of 60 μm was obtained. Produced.

  A waterproof double-sided pressure-sensitive adhesive tape for portable electronic devices was obtained in the same manner as in Example 1 except that this polyurethane-based thermoplastic elastomer sheet was used as a base material layer.

(Comparative Example 2)
A total of two laminated sheets in which an adhesive layer made of an acrylic adhesive was laminated on the release treatment surface of a polyethylene terephthalate film were produced in the same manner as in Example 1.

  One polyethylene terephthalate sheet having a certain thickness was prepared, and one nitrile-butadiene rubber (NBR) sheet having a certain thickness was prepared.

  Next, a nitrile-butadiene rubber (NBR) sheet is superposed on one surface of the polyethylene terephthalate sheet to produce a laminate, and this laminate is pressed in the thickness direction while being heated to 40 ° C., whereby non-foamed polyethylene terephthalate. A non-foamed nitrile-butadiene rubber (NBR) sheet was laminated and integrated on one surface of the sheet to prepare a base material layer. In the base material layer, the thickness of the first synthetic resin layer made of a polyethylene terephthalate sheet and the thickness of the second synthetic resin layer made of a nitrile-butadiene rubber (NBR) sheet were as shown in Table 1.

  While laminating one laminated sheet on the first synthetic resin layer of the base material layer so that the adhesive layer faces the base material layer, the adhesive layer is transferred to the base material layer and laminated and integrated. The other laminated sheet is laminated on the second synthetic resin layer of the base material layer so that the pressure-sensitive adhesive layer faces the base material layer, and the pressure-sensitive adhesive layer is transferred to the base material layer and laminated and integrated. Thus, a waterproof double-sided pressure-sensitive adhesive tape for portable electronic devices in which a pressure-sensitive adhesive layer having a thickness of 50 μm was laminated and integrated on both surfaces of the base material layer was obtained.

(Comparative Example 3)
A waterproof double-sided pressure-sensitive adhesive tape for portable electronic devices was obtained in the same manner as in Example 1 except that a polyethylene terephthalate sheet having a thickness of 38 μm was prepared and this polyethylene terephthalate sheet was used as a base material layer.

  The retention strength, waterproofness and punchability of the obtained waterproof double-sided pressure-sensitive adhesive tape for portable electronic devices were measured in the following manner, and the results are shown in Table 1. In Table 1, nitrile-butadiene rubber (NBR) is represented as “NBR”, polyurethane-based thermoplastic elastomer as “PU”, and polyethylene terephthalate as “PET”.

(Holding power)
The measurement was performed according to JIS Z0237, except that the holding strength of the waterproof double-sided pressure-sensitive adhesive tape for portable electronic devices was set to 85 ° C., 500 g, for one hour.

(Waterproof)
A waterproof double-sided pressure-sensitive adhesive tape for portable electronic devices is punched into a rectangular frame shape (frame shape) in which a flat rectangular shape having an outer dimension of 46 mm × width 61 mm and a flat rectangular shape having a height 42 mm × width 57 mm is formed. A test piece 12 having the planar shape shown in FIG. 3 was produced. The width of each side was 2 mm.

  Next, synthetic resin plates 13 and 14 formed of two sheets of polymethyl methacrylate were prepared. A single-sided adhesive tape 15 comprising a polyethylene terephthalate sheet having a width of 1 mm and a thickness of 50 μm as a base material and an adhesive layer laminated and integrated on one side of the base material is prepared. A square frame was pasted on the upper surface of 13. The square frame formed of this single-sided adhesive tape 15 was formed as a planar rectangular frame having an outer dimension of 45 mm × 60 mm and an inner dimension of 43 mm × 58 mm.

  After removing the polyethylene terephthalate film on one adhesive layer of the test piece 12 to expose the adhesive layer, the test piece 12 is placed so as to cover the square frame-shaped single-sided adhesive tape 15 on the synthetic resin plate 13. Sticked.

  Thereafter, after removing the polyethylene terephthalate film on the other adhesive layer of the test piece 12 to expose the adhesive layer, the synthetic resin plate 14 is laminated on the test piece 12, and the load is 5 kg. By pressing for 2 seconds, the synthetic resin plates 13 and 14 were laminated and integrated through the test piece 12 to prepare a test specimen. The specimen was left at 23 ° C. for 1 day. In addition, a circular through hole 13a having a diameter of 1 cm is formed in the central portion of the synthetic resin plate 13 so as to penetrate between both surfaces, and the two synthetic resin plates 13 and 14 are passed through the through hole 13a. The space 16 surrounded by the opposite surface and the test piece 12 was in communication with the outside.

  As shown in FIG. 4, the test specimen is placed so that the test piece 12 of the test specimen is completely submerged and the upper end opening of the through hole 13a of the upper synthetic resin plate 13 is positioned above the water surface. I sunk in the water. The two synthetic resin plates 13 and 14 were adjusted to be in a horizontal state.

  Thereafter, air is pressed into the space portion 5 of the test body through the through hole 13a of the synthetic resin plate 13 at a pressure of 1 MPa for 30 minutes, and air is introduced from the interface between the synthetic resin plates 13 and 14 and the test piece 12. It was visually observed whether it was leaking. In the case of 30 minutes, the case where no air leak occurred was indicated as “◯”, and the case where the air leak occurred was indicated as “X”. With respect to the test piece in which no air leakage occurred during the 30 minutes of air injection, air was further injected into the space 5 of the test specimen through the through hole 13a of the synthetic resin plate 13 at a pressure of 1 MPa for 2 hours. A case where no air leak occurred even after 2 hours was indicated as “◎”. It should be noted that air was not leaked from the through hole 13a of the synthetic resin plate 13 when the air was press-fitted from the through hole 13a of the synthetic resin plate 13.

(Punching workability)
A waterproof double-sided pressure-sensitive adhesive tape for portable electronic devices is punched into a rectangular frame shape (frame shape) in which a flat rectangular shape having an outer dimension of 46 mm × width 61 mm and a flat rectangular shape having a height 42 mm × width 57 mm is formed. A test piece having the planar shape shown in FIG. 3 was produced. The width of each side was 2 mm.

In the obtained test piece, the respective widths of the central part in the vertical direction and the horizontal direction are measured, the arithmetic average value of these measured values is calculated, and this arithmetic average value is set as the width of the test piece based on the following criteria. Based on the evaluation.
A: The width of the test piece was 2 mm or more and less than 2.15 mm.
○: The width of the test piece was 2.15 mm or more and less than 2.3 mm.
X: The width of the test piece was 2.3 mm or more.

DESCRIPTION OF SYMBOLS 1 1st synthetic resin layer 2 2nd synthetic resin layer 3 Adhesive layer 4 Base material layer 5 Backlight housing | casing 5 Space part
51 Panel placement step
51a Panel receiving surface
52 Reflector plate placement step 6 Liquid crystal display panel 7 Light guide plate 8 Diffusion sheet 9 Prism sheet
10 Reflector
11 Transparent protective plate
12 specimens
13 Synthetic resin board
13a Through hole
14 Synthetic resin board
15 Single-sided adhesive tape
16 Space A Waterproof double-sided adhesive tape for mobile electronic devices B LCD module unit C Double-sided adhesive tape

Claims (1)

From the thermoplastic elastomer and rubber resin on both sides of the non-foamed first synthetic resin layer containing at least one synthetic resin selected from the group consisting of polyolefin resin and polyester resin (excluding polyethylene terephthalate) A base layer formed by laminating and integrating a non-foamed second synthetic resin layer containing at least one synthetic resin selected from the group consisting of: a pressure-sensitive adhesive layer laminated and integrated on both sides of the base layer; A waterproof double-sided pressure-sensitive adhesive tape for portable electronic devices, wherein the second synthetic resin layer has a thickness of 2.08 times or more the thickness of the first synthetic resin layer.

Images