JP2011249613A - Electromagnetic wave absorbing adhesive sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electromagnetic wave absorbing adhesive sheet which can be stably adhered to even a surface having curved and rugged portions, which can obtain a strong and stable adhesion state by simply adhering with pressure especially to outdoor buildings and concrete structures, and which can furthermore stably keep an electromagnetic wave absorbing ability.SOLUTION: A electromagnetic wave absorbing adhesive sheet has an electromagnetic wave absorbing laminated structure 10 in which a divided conductive film 1, an electromagnetic wave absorbing sheet 2, and an electromagnetic wave reflecting sheet 3 are stacked in this order. A protection layer 4 is formed on one side 1A which is the opposite side of the electromagnetic wave absorbing sheet of the divided conductive film 1, and a bubble-containing adhesive layer 5 is formed on one side 3A which is the opposite side of the electromagnetic wave absorbing sheet of the electromagnetic wave reflecting sheet 3.

Description

  The present invention can stably adhere to adherends having various surface properties, and particularly maintain the stable adhesion state to outdoor buildings and structures, and also stably maintain electromagnetic wave absorption performance. The present invention relates to a highly durable electromagnetic wave absorbing pressure-sensitive adhesive sheet.

  With the recent expansion of applications of electromagnetic wave absorbers, the use of electromagnetic wave absorbers in various environments is increasing. For example, in an automatic toll collection system (ETC) on an expressway using electromagnetic waves in the GHz band, the vehicle is confirmed by wireless communication between a road antenna attached to a tollgate gate ceiling and an in-vehicle antenna attached to a car. However, the system malfunctions when communication is established with a vehicle traveling in the adjacent lane, and even in a tunnel due to electromagnetic waves from the adjacent vehicle due to congestion during traffic jams, Causes electromagnetic interference such as noise entering the radio. For this reason, electromagnetic wave absorbers are attached to the walls and roofs of toll collection buildings, to soundproof walls on expressways, and to the inner wall surface of tunnels.

  However, the electromagnetic wave absorber attached to the walls and roofs of such buildings, the soundproof walls of highways, and the inner wall surface of the tunnel naturally increases in area, so the electromagnetic wave absorber installation work (installation work) is not easy. . In addition, since the electromagnetic wave absorber cannot be fixed to a building, a soundproof wall, an inner wall of a tunnel, or the like as it is, for example, a hole or a recess is formed in the peripheral portion of the electromagnetic wave absorber, while the wall or roof plate of the building, Pretreatment (processing) such as providing a projection for locking the electromagnetic wave absorber by driving a bolt or the like into the soundproof wall or the inner wall of the tunnel is required. Therefore, if it is an adhesive sheet type electromagnetic wave absorber that can be easily mounted simply by pressure bonding to an object to be mounted, it is considered that the cost and work time for mounting (installation) of the electromagnetic wave absorber can be reduced. However, although there have been proposals for an electromagnetic wave absorber of the adhesive sheet type (for example, Patent Document 1), all of them are intended to be mounted on small electric devices such as mobile phones and personal computers, and are outdoors. However, an electromagnetic wave absorber that can be stably mounted only by pressure bonding to a large area surface including a large number of curved surface portions and uneven portions such as a building or a concrete structure has not been realized.

JP 2005-277145 A

  Therefore, the problem to be solved by the present invention is that it can be stably adhered even to a surface including a curved surface portion or an uneven portion, and particularly strong and stable adhesion only by pressure bonding to an outdoor building or a concrete structure. An object of the present invention is to provide an electromagnetic wave absorbing pressure-sensitive adhesive sheet that can obtain a state and can also stably maintain electromagnetic wave absorption performance.

In order to solve the above-described problems, the present invention adopts the following configuration.
(1) It has a laminated structure part for electromagnetic wave absorption in which a divided conductive film, an electromagnetic wave absorbing sheet and an electromagnetic wave reflecting sheet are laminated in this order, and a protective layer is provided on one side opposite to the electromagnetic wave absorbing sheet side of the divided conductive film. An electromagnetic wave absorbing pressure-sensitive adhesive sheet, which is formed and has a bubble-containing pressure-sensitive adhesive layer formed on one side of the electromagnetic wave reflecting sheet opposite to the electromagnetic wave absorbing sheet.
(2) The laminated structure for electromagnetic wave absorption has the divided conductive film bonded to one side of the electromagnetic wave absorbing sheet via an adhesive layer, and the electromagnetic wave reflecting sheet is attached to the other side of the electromagnetic wave absorbing sheet via an adhesive layer. The electromagnetic wave-absorbing pressure-sensitive adhesive sheet according to (1), which is bonded.
(3) The electromagnetic wave absorbing pressure-sensitive adhesive sheet according to (2), wherein the pressure-sensitive adhesive layer is formed of an acrylic pressure-sensitive adhesive having a gel fraction of 70 to 90%.
(4) The electromagnetic wave absorbing pressure-sensitive adhesive sheet according to any one of the above (1) to (3), wherein the bubble-containing pressure-sensitive adhesive layer contains 5 to 50% by volume of bubbles.
(5) The electromagnetic wave absorbing pressure-sensitive adhesive sheet according to (4), wherein the bubble-containing pressure-sensitive adhesive layer contains 5 to 50% by volume of hollow microspheres having a specific gravity of 0.1 to 0.8 g / cm ³ .

The electromagnetic wave absorbing pressure-sensitive adhesive sheet of the present invention has an electromagnetic wave absorbing laminated structure portion in which a divided conductive film, an electromagnetic wave absorbing sheet, and an electromagnetic wave reflecting sheet are laminated in this order. Type electromagnetic wave absorber, or a matching film (absorption film) and a reflective film similar to the λ / 4 type electromagnetic wave absorber, and a divided conductive film is provided between the matching film and the reflective film (so-called “divided” Unlike the conductive film electromagnetic wave absorber "), since it does not have a matching film, it is possible to achieve lighter weight and thickness reduction and rich flexibility. The bubble-containing pressure-sensitive adhesive layer formed on one side of the laminated structure for electromagnetic wave absorption has excellent deformability to follow the surface even if the surface of the adherend has a curved surface or an uneven portion. Therefore, the electromagnetic wave absorbing pressure-sensitive adhesive sheet of the present invention can stably adhere to a surface containing a large number of curved surface portions and uneven portions, and particularly has curved surface portions and uneven portions such as surfaces of outdoor buildings and concrete structures. A strong and stable adhesive state can be obtained only by pressure-bonding to a surface having a relatively large area including many.
Furthermore, since not only the bubble-containing pressure-sensitive adhesive layer but also the laminated structure portion for absorbing electromagnetic waves has flexibility, it is excellent in stress relaxation and can maintain a stable adhesive state for a long period of time.
Furthermore, since the protective layer is provided on the outermost surface, the entire pressure-sensitive adhesive sheet has excellent weather resistance and high temperature and high humidity resistance, and maintains stable electromagnetic wave absorption performance for a long period of time.

It is a schematic cross section of an example of the adhesive sheet for electromagnetic wave absorption of this invention. It is the schematic (The figure (A) is a top view on the surface side, and the figure (B) is a top view on the back side) which shows the evaluation method of the uneven | corrugated followable | trackability of an adhesive sheet.

Hereinafter, the present invention will be described in more detail with reference to preferred embodiments thereof.
FIG. 1 is a schematic cross-sectional view of an example of the electromagnetic wave absorbing pressure-sensitive adhesive sheet of the present invention.
The electromagnetic wave absorbing pressure-sensitive adhesive sheet of the present invention (hereinafter also simply referred to as “pressure-sensitive adhesive sheet”) includes a divided conductive film 1, an electromagnetic wave absorbing sheet 2, and an electromagnetic wave reflecting sheet as shown in the pressure-sensitive adhesive sheet 100 of the example of FIG. 3 has an electromagnetic wave absorbing laminated structure 10 laminated in this order, and a protective layer 4 is provided on one side 1A of the divided conductive film 1 opposite to the electromagnetic wave absorbing sheet 2 side. A bubble-containing pressure-sensitive adhesive layer 5 is formed on one side 3A opposite to the sheet 2 side.

  The surface of the protective layer 4 is used as an electromagnetic wave incident surface, and the adhesion target (exposed surface) 5A of the bubble-containing pressure-sensitive adhesive layer 5 is brought into pressure contact with the surface of the adhesion target 7 so that the adhesion target 7 Even if the surface is a curved surface or an uneven surface, the bubble-containing pressure-sensitive adhesive layer 5 adheres closely to the surface shape and is attached to the adherend 7 in a strong and stable adhesive state.

[Laminated structure for electromagnetic wave absorption]
As shown in FIG. 1, the laminated structure portion 10 for absorbing electromagnetic waves in the pressure-sensitive adhesive sheet of the present invention preferably has the divided conductive film 1 bonded to one side of the electromagnetic wave-absorbing sheet 2 via the pressure-sensitive adhesive layer 6. The electromagnetic wave reflecting sheet 3 is bonded to the other surface of the electromagnetic wave absorbing sheet 2 with an adhesive layer 6 interposed therebetween. By adopting such a configuration, it becomes more advantageous in terms of weather resistance, adhesion to an adherend, and the like.

(Divided conductive film)
A divided conductive film (DCF = Divided Conductive Film) 1 used in the present invention is a structure in which a plurality of island-shaped conductive films are arranged (insulated) with a gap between each other. Various conductive materials can be applied. Preferable examples include metals such as platinum, gold, silver, nickel, chromium, aluminum, copper, zinc, tungsten, and iron, preferably copper.

  As a method of forming the divided conductive film 1, (1) after laminating a metal foil on a substrate, or forming a conductive film such as a metal film by vacuum deposition or sputtering, a desired conductive film is formed by photolithography. A method of forming a plurality of island-shaped conductive film portions by patterning into a pattern; (2) a method of forming a plurality of island-shaped conductive film portions by printing a metal paste on a substrate; The method etc. which affix the metal piece cut | judged by the desired pattern to the base material are mentioned. As the shape (planar shape) of the island-shaped conductive film portion, any shape such as a circle, a rectangle, a polygon, a ring, and an indeterminate shape can be selected. In addition, the plurality of island-shaped conductive film portions are arranged such that a part or the whole of the plurality of island-shaped conductive film portions forms a geometric pattern such as a checkered pattern, a matrix shape, a stripe shape, or a polka dot shape. It may be. As described above, the divided conductive film has a plurality of conductive film portions formed on a base material, and a plastic film such as a polyethylene terephthalate (PET) film or a polyimide (PI) film is used for the base material. The The thickness of the base material is preferably about 25 to 125 μm, more preferably about 50 to 100 μm. If the thickness of the substrate exceeds 125 μm, good flexibility may not be obtained, and it is not preferable in terms of cost. On the other hand, when the thickness is less than 25 μm, the handling in the production of the divided conductive film 1 and in the case of producing the electromagnetic wave absorbing laminated structure 10 using the divided conductive film 1 tends to be reduced.

  The shape (planar shape) of the conductive film portion in the divided conductive film 1, the thickness of the conductive film portion, the dimension of the gap between adjacent conductive film portions (separation distance), the arrangement form of the conductive film portions, and the like consider the electromagnetic wave absorption performance. To be determined. Specifically, for example, when used for preventing communication troubles in ETC, since the communication frequency of ETC is 5.8 GHz, in order to efficiently absorb the electromagnetic wave of 5.8 GHz, Planar shape of the film part: a square of 4.5 mm on one side, a thickness of the conductive film part: 35 μm, a dimension (separation distance) between adjacent conductive film parts: 1.7 mm, an arrangement form of the conductive film part: a square matrix The form to do is mentioned.

(Electromagnetic wave absorbing sheet)
The electromagnetic wave absorbing sheet 2 used in the present invention is a binder made of resin and / or rubber, an electromagnetic wave loss material such as ferrite, conductive filler (eg, graphite, carbon black, metal powder, carbon nanotube, etc.) (hereinafter, It is a sheet made of a polymer composition in which a material (also simply referred to as “loss material”) is dispersed. The loss material is preferably graphite in terms of specific gravity, cost, formability, and the like.

  Examples of the resin include polyester resins such as polyethylene terephthalate (PET), polyolefin resins such as polyethylene (PE) and polypropylene (PP), polyimide (PI), polyetheretherketone (PEEK), polyvinyl chloride (PVC), Examples thereof include thermoplastic resins such as polyvinylidene chloride resin, polyamide resin, polyurethane resin, polystyrene resin, acrylic resin, fluorine resin, cellulose resin, and polycarbonate resin. As rubber, nitrile rubber (NBR), hydrogenated nitrile rubber (HNBR), styrene-butadiene rubber (SBR), chloroprene rubber (CR), ethylene propylene rubber (EPDM), vinylidene fluoride rubber (FKM), Examples include vinyl methyl silicone rubber (VMQ). Resin and / or rubber may be used individually by 1 type, or may mix and use 2 or more types. Among the resins, polyolefin resins (especially polyethylene (PE)) and acrylic resins are preferable in terms of molding processability, weather resistance, cost, etc., more preferably low density polyethylene (LDPE), polymethyl methacrylate. (PMMA). Among the rubbers, ethylene propylene rubber (EPDM) is preferably used because it is particularly excellent in weather resistance.

  The mixing ratio of the binder and the loss material is preferably 20 to 200 parts by weight, more preferably 50 to 120 parts by weight with respect to 100 parts by weight of the binder. If the amount of the loss material is larger or smaller than the preferable range, the electromagnetic wave absorption performance may be deteriorated.

  The thickness of the electromagnetic wave absorbing sheet 2 is set in consideration of the entire characteristics of the laminated structure portion 10 for absorbing electromagnetic waves including the divided conductive film 1 and the electromagnetic wave reflecting sheet 3, and is generally within a range of 1.5 to 5 mm. Is set. If the thickness is less than 1.5 mm, a sufficient electromagnetic wave absorbing effect tends to be hardly obtained. Conversely, if the thickness exceeds 5 mm, flexibility tends to be impaired, and the weight of the pressure-sensitive adhesive sheet also increases.

  The manufacturing method of the said electromagnetic wave absorption sheet is not specifically limited, It can manufacture with the manufacturing method of well-known resin and / or a rubber sheet. When the binder is a resin, (1) Dissolve or disperse the resin and the loss material in an organic solvent with an appropriate disperser such as a bead mill to prepare a coating liquid, and apply it on the substrate subjected to the release treatment. And (2) kneading the resin and the lossy material with a Brabender, kneader, Banbury mixer, twin-screw or single-screw extruder, etc. A method of forming a sheet by die sheet forming, calendar forming, roll forming, press forming, inflation forming or the like is preferable. In the case where the binder is rubber or a combination of rubber and resin, the above method (2) is suitable.

  The electromagnetic wave absorbing sheet 2 may include a dispersant, plasticity, a surface conditioner, an antifoaming agent, an anti-thickening agent, an antigelling agent, a crosslinking agent, a filler, a lubricant, a colorant, and a flame retardant as necessary. An additive such as an antistatic agent can also be added.

(Electromagnetic wave reflection sheet)
The electromagnetic wave reflecting sheet 3 used in the present invention needs to be excellent in electromagnetic wave shielding properties that reflect an electromagnetic wave and does not transmit the electromagnetic wave itself, and a metal foil such as aluminum, copper, iron, or nickel is used. Among these, aluminum foil is preferable from the viewpoints of flexibility, lightness, and the like. The metal foil may be a flat plate, a punch-through metal, an expanded metal, or a mesh. When punch-through metal, expanded metal, and mesh have a large number of through-holes, it is important that the size of the through-hole is about λ / 20 when the wavelength of the electromagnetic wave is λ. By doing so, electromagnetic waves are prevented from passing through the through holes.

  The thickness of the electromagnetic wave reflection sheet 3 is preferably 0.025 mm or more, and more preferably 0.1 mm or more from the viewpoint of reflection performance, strength, and the like. Moreover, since it will become heavy and a tendency for a flexibility to fall when thickness is too large, 0.5 mm or less is preferable and 0.3 mm or less is more preferable.

(Adhesive layer)
Various pressure-sensitive adhesives can be used for the adhesive layer 6 used for bonding the divided conductive film 1 and the electromagnetic wave absorbing sheet 2 and for bonding the electromagnetic wave absorbing sheet 2 and the electromagnetic wave reflecting sheet 3. For example, acrylic adhesives, rubber adhesives, vinyl alkyl ether adhesives, silicone adhesives, polyester adhesives, polyamide adhesives, urethane adhesives, fluorine adhesives, epoxy adhesives, etc. Can be mentioned. Among these, from the viewpoint of strong adhesion, an acrylic pressure-sensitive adhesive and / or a rubber-based pressure-sensitive adhesive is preferable, and an acrylic pressure-sensitive adhesive is more preferable.

  The gel fraction of the pressure-sensitive adhesive layer 6 is preferably 70 to 90% (% by weight), more preferably 75 to 90%, and particularly preferably 80 to 90%. When the gel fraction is lower than 70%, good weather resistance and durability tend to be difficult to obtain, and when it is higher than 90%, good adhesiveness tends to be difficult to obtain.

  Examples of the rubber adhesive include natural rubber, styrene-isoprene-styrene block copolymer (SIS block copolymer), styrene-butadiene-styrene block copolymer (SBS block copolymer), and styrene-ethylene / butylene. -Rubber components such as styrene block copolymer (SEBS block copolymer), styrene-butadiene rubber, polybutadiene, polyisoprene, polyisobutylene, butyl rubber, chloroprene rubber, silicone rubber, acrylonitrile-butadiene rubber, ethylene-propylene terpolymer Examples thereof include a rubber-based adhesive used as a base polymer.

  Examples of the acrylic pressure-sensitive adhesive include a pressure-sensitive adhesive containing an acrylic polymer as a base polymer (main component). The acrylic polymer is a monomer mainly composed of an alkyl (meth) acrylate having an alkyl group having 2 to 18 carbon atoms. An acrylic polymer as a component is preferred.

  Examples of the alkyl (meth) acrylate having an alkyl group having 2 to 18 carbon atoms include ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, sec -Butyl (meth) acrylate, t-butyl (meth) acrylate, n-octyl (meth) acrylate, isooctyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isononyl (meth) acrylate, dodecyl (meth) acrylate, iso Examples include stearyl (meth) acrylate. 1 type (s) or 2 or more types are used for this alkyl (meth) acrylate.

  In the acrylic polymer, a copolymerizable monomer may be used as a monomer component together with the alkyl (meth) acrylate having an alkyl group having 2 to 18 carbon atoms. Examples of such copolymerizable monomers include carboxyl group-containing monomers such as acrylic acid, methacrylic acid, carboxyethyl acrylate, carboxypentyl acrylate, itaconic acid, maleic acid, and crotonic acid; 2-hydroxyethyl (meth) acrylate, (Meth) acrylic acid 2-hydroxypropyl, (meth) acrylic acid 4-hydroxybutyl, (meth) acrylic acid 6-hydroxyhexyl, (meth) acrylic acid 8-hydroxyoctyl, (meth) acrylic acid 10-hydroxydecyl, Hydroxyl group-containing monomers such as (meth) acrylic acid 12-hydroxylauryl and (4-hydroxymethylcyclohexyl) -methyl acrylate; acid anhydride monomers such as maleic anhydride and itaconic anhydride; 2-acrylamido-2-methylprop Sulfonic acid group-containing monomers such as sulfonic acid and sulfopropyl acrylate; Phosphoric acid group-containing monomers such as 2-hydroxyethylacryloyl phosphate; Amide monomers such as N-substituted (meth) acrylamides such as (meth) acrylamide and N-methylolacrylamide Succinimide monomers such as N- (meth) acryloyloxymethylene succinimide, N- (meth) acryloyl-6-oxyhexamethylene succinimide, N- (meth) acryloyl-8-oxyoctamethylene succinimide; vinyl acetate, N-vinyl Vinyl monomers such as pyrrolidone, N-vinylcarboxylic acid amides, styrene and N-vinylcaprolactam; Cyanoacrylate monomers such as acrylonitrile and methacrylonitrile; (meth) acrylic Acrylic acid ester monomers such as glycidyl, tetrahydrofurfuryl (meth) acrylate, polyethylene glycol (meth) acrylate, polypropylene glycol (meth) acrylate, fluorine (meth) acrylate, silicone (meth) acrylate, 2-methoxyethyl acrylate; methyl Examples include alkyl (meth) acrylates having an alkyl group different from alkyl (meth) acrylates constituting the main component such as (meth) acrylate and octadecyl (meth) acrylate; alicyclic acrylates such as isobornyl (meth) acrylate, and the like. . Among these, a hydroxyl group-containing monomer and a carboxyl group-containing monomer are preferable, and acrylic acid is particularly preferable. One or two or more copolymerizable monomers can be used.

  The component ratio of the alkyl (meth) acrylate having an alkyl group having 2 to 18 carbon atoms and the copolymerizable monomer (alkyl (meth) acrylate having an alkyl group having 2 to 18 carbon atoms: copolymerizable monomer) is 60. -99.9% by weight: 0.1 to 40% by weight is preferable, 70 to 99.5% by weight: 0.5 to 30% by weight is more preferable, and 80 to 99% by weight: 1 to 20% by weight is more preferable. 90-99 wt%: 1-10 wt% is particularly preferred.

  The acrylic pressure-sensitive adhesive is a monomer mixture (that is, an alkyl (meth) acrylate having an alkyl group having 2 to 18 carbon atoms) having the above-described alkyl (meth) acrylate having an alkyl group having 2 to 18 carbon atoms as a main component. Or a mixture of an alkyl (meth) acrylate having an alkyl group having 2 to 18 carbon atoms and a copolymerizable monomer) or a partial polymer thereof, a polyfunctional (meth) acrylate and a polymerization initiator are further blended Particularly preferred is a polymer obtained by polymerizing the polymerizable composition.

  As the polymerization initiator, various polymerization initiators (for example, a thermal polymerization initiator and a photopolymerization initiator) can be used without limitation, and a photopolymerization initiator is particularly preferable in that the polymerization time can be shortened. Can be used.

  The photopolymerization initiator is not particularly limited, and for example, benzoin ether photopolymerization initiator, acetophenone photopolymerization initiator, α-ketol photopolymerization initiator, aromatic sulfonyl chloride photopolymerization initiator, photoactivity An oxime photopolymerization initiator, a benzoin photopolymerization initiator, a benzyl photopolymerization initiator, a benzophenone photopolymerization initiator, a ketal photopolymerization initiator, a thioxanthone photopolymerization initiator, or the like can be used.

  Specifically, examples of the benzoin ether photopolymerization initiator include benzoin methyl ether, benzoin ethyl ether, benzoin propyl ether, benzoin isopropyl ether, benzoin isobutyl ether, 2,2-dimethoxy-1,2-diphenylethane- Examples include 1-one and anisole methyl ether. Examples of the acetophenone photopolymerization initiator include 2,2-diethoxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 1-hydroxycyclohexyl phenyl ketone, 4-phenoxydichloroacetophenone, 4-t-butyl-dichloro. Examples include acetophenone. Examples of the α-ketol photopolymerization initiator include 2-methyl-2-hydroxypropiophenone, 1- [4- (2-hydroxyethyl) -phenyl] -2-hydroxy-2-methylpropane-1- ON etc. are mentioned. Examples of the aromatic sulfonyl chloride photopolymerization initiator include 2-naphthalenesulfonyl chloride. Examples of the photoactive oxime photopolymerization initiator include 1-phenyl-1,1-propanedione-2- (o-ethoxycarbonyl) -oxime. Examples of the benzoin photopolymerization initiator include benzoin. Examples of the benzyl photopolymerization initiator include benzyl. Examples of the benzophenone-based photopolymerization initiator include benzophenone, benzoylbenzoic acid, 3,3′-dimethyl-4-methoxybenzophenone, polyvinylbenzophenone, α-hydroxycyclohexyl phenyl ketone, and the like. Examples of the ketal photopolymerization initiator include benzyl dimethyl ketal. Examples of the thioxanthone photopolymerization initiator include thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, 2,4-dimethylthioxanthone, isopropylthioxanthone, 2,4-dichlorothioxanthone, 2,4-diethylthioxanthone, 2,4. -Diisopropylthioxanthone, dodecylthioxanthone and the like are included.

  Examples of the thermal polymerization initiator include 2,2′-azobisisobutyronitrile, 2,2′-azobis-2-methylbutyronitrile, 2,2′-azobis (2-methylpropionic acid) dimethyl, 4,4'-azobis-4-cyanovaleric acid, azobisisovaleronitrile, 2,2'-azobis (2-amidinopropane) dihydrochloride, 2,2'-azobis [2- (5-methyl-2- Imidazolin-2-yl) propane] dihydrochloride, 2,2′-azobis (2-methylpropionamidine) disulfate, 2,2′-azobis (N, N′-dimethyleneisobutylamidine) dihydrochloride and other azo Thermal polymerization initiators; peroxide thermal polymerization initiators such as dibenzoyl peroxide and tert-butyl permaleate; redox thermal polymerization Initiator and the like. The amount of the thermal polymerization initiator used is not particularly limited as long as it can be conventionally used as a thermal polymerization initiator.

  The photopolymerization initiator is used in an amount of 0.01 to 5 with respect to 100 parts by weight of a monomer mixture or a partial polymer thereof mainly composed of an alkyl (meth) acrylate having an alkyl group having 2 to 18 carbon atoms. It is used in a proportion of parts by weight (preferably 0.05 to 3 parts by weight).

  In activating the photopolymerization initiator, the thermal foaming agent-containing pressure-sensitive adhesive composition is irradiated with active energy rays. Examples of such active energy rays include ionizing radiation such as α rays, β rays, γ rays, neutron rays, electron rays, and ultraviolet rays, and ultraviolet rays are particularly preferable. The irradiation energy of the active energy beam, the irradiation time, etc. are not particularly limited as long as the photopolymerization initiator can be activated to cause the reaction of the monomer component.

  As the polyfunctional (meth) acrylate, any compound having at least two (meth) acryloyl groups can be used without particular limitation. Examples of such polyfunctional (meth) acrylates include trimethylolpropane tri (meth) acrylate, tetramethylolmethane tetraacrylate, pentaerythritol di (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth). ) Acrylate, 1,2-ethylene glycol di (meth) acrylate, 1,4-butylene glycol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, 1,12-dodecanediol di (meth) acrylate , Dipentaerythritol monohydroxypenta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, polyethylene glycol di (meth) acrylate, hexanediol di (meth) Acrylate, (poly) ethylene glycol di (meth) acrylate, (poly) propylene glycol di (meth) acrylate, neopentyl glycol di (meth) acrylate, tetramethylol methanetri (meth) acrylate, allyl (meth) acrylate, vinyl ( (Meth) acrylate, epoxy acrylate, polyester acrylate, urethane acrylate, reactive hyperbranched polymer having a plurality of (meth) acryloyl groups at the terminal [for example, trade names “CN2300”, “CN2301”, “CN2320” (manufactured by SARTOMER), etc.] Etc. In addition, polyfunctional (meth) acrylate can be used 1 type or in combination of 2 or more types.

  The amount of the polyfunctional (meth) acrylate used is blended so that the gel fraction of the polymer to be obtained is within the above-mentioned preferred range. For example, the specific amount of use varies depending on the molecular weight, the number of functional groups, and the like, but a monomer mixture or a partially polymerized product thereof mainly composed of an alkyl (meth) acrylate having an alkyl group having 2 to 18 carbon atoms. 0.001-5 weight part is preferable with respect to a weight part, More preferably, it is 0.001-3 weight part, Especially preferably, it is 0.01-2 weight part. When the amount exceeds 5 parts by weight, the cohesive force of the pressure-sensitive adhesive layer tends to be too high, and the pressure-sensitive adhesive force tends to decrease. On the other hand, when the amount used is too small (for example, less than 0.001 part by weight), The cohesive force of the agent layer is lowered, and the weather resistance tends to be lowered.

  Various additives may be blended in the pressure-sensitive adhesive layer 6 together with the pressure-sensitive adhesive. Examples of such additives include crosslinking agents such as isocyanate crosslinking agents and epoxy crosslinking agents; tackifiers such as rosin derivative resins, polyterpene resins, petroleum resins, and oil-soluble phenol resins; plasticizers; fillers; Antiaging agents; surfactants and the like.

  The method for forming the pressure-sensitive adhesive layer 6 is not particularly limited. For example, the pressure-sensitive adhesive composition is applied on a suitable support such as a release film or a base material to form a pressure-sensitive adhesive composition layer. If necessary, it is formed by drying or curing (curing with heat or active energy rays). In addition, when curing with an active energy beam (photocuring), the photopolymerization reaction is inhibited by oxygen in the air, so that an appropriate support such as a release film or a substrate can be laminated on the layer. In addition, it is preferable to block oxygen by performing photocuring in a nitrogen atmosphere.

  When the pressure-sensitive adhesive layer 6 formed in this way has a release film or a base material only on one side, the other side is attached to the divided conductive film 1, the electromagnetic wave absorbing sheet 2 or the electromagnetic wave reflecting sheet 3. Then, it peels and uses the peeling film and base material of one single side | surface. When the pressure-sensitive adhesive layer 6 has a release film or a base material on both surfaces, the adhesive surface exposed by peeling one release film or base material is attached to the divided conductive film 1, the electromagnetic wave absorbing sheet 2, and the electromagnetic wave reflection sheet 3. After attaching, the other release film or substrate is peeled off and used.

  The thickness of the pressure-sensitive adhesive layer 6 is preferably 25 to 200 μm, more preferably 50 to 100 μm, from the viewpoints of appearance characteristics, cost, and adhesiveness. If it is less than 25 μm, the adhesiveness tends to decrease, and if it exceeds 200 μm, the cost performance tends to decrease and the appearance characteristics tend to be poor.

  In addition, the adhesive layer 6 is used for bonding the divided conductive film 1 and the electromagnetic wave absorbing sheet 2 (adhesive layer interposed between the divided conductive film 1 and the electromagnetic wave absorbing sheet 2), the electromagnetic wave absorbing sheet 2, and the like. Although the same thickness may be sufficient as what is used for bonding of the electromagnetic wave reflection sheet 3 (adhesive layer interposed between the electromagnetic wave absorption sheet 2 and the electromagnetic wave reflection sheet 3), the thickness is different within the above range. It may be.

[Protective layer]
The protective layer 4 used in the present invention is a highly durable film.
High-durability films include films that can withstand long-term use outdoors, films made of polyolefin-based thermoplastic resins such as polypropylene homopolymers and polypropylene random polymers, and polyester-based films such as polyethylene terephthalate (PET) films. Examples thereof include a film, a film made of a urethane polymer, a composite film containing an acrylic polymer and a urethane polymer, and a fluorine film. Any one of these films may be used alone, or two or more may be laminated and used in the form of a laminated film. Among these, a fluorine-based film is preferable from the viewpoint of weather resistance.

(Polyolefin thermoplastic film)
Examples of the polyolefin-based thermoplastic resin film include films composed mainly of a polymer containing an α-olefin having 4 to 12 carbon atoms, and films such as a polyethylene-based resin, a polypropylene-based resin, and an ethylene vinyl acetate copolymer. It is done.

  Specifically, olefin polymers such as low density polyethylene, linear low density polyethylene, polypropylene, poly-1-butene, poly-4-methyl-1-pentene, ethylene / propylene copolymers, ethylene / 1- Butene copolymer, ethylene / 1-hexene copolymer, ethylene-4-methyl-1-pentene copolymer, ethylene / 1-octene copolymer, ethylene / propylene / butene copolymer, ethylene / methyl acrylate Copolymer, ethylene / methyl methacrylate copolymer, ethylene / vinyl acetate copolymer, ethylene / ethyl acrylate copolymer, ethylene / vinyl alcohol copolymer, polyvinyl chloride, polyvinylidene chloride, and the like. .

(Polyester film)
Examples of the polyester film include a polyethylene terephthalate (PET) film and a polybutylene terephthalate (PBT) film.

(Urethane polymer film)
Examples of the film made of a urethane polymer include films made of various urethane polymers having a urethane bond in the main chain, obtained by reacting diisocyanate with a diol or diamine.

(Fluorine film)
Examples of the fluorine-based film include polytetrafluoroethylene (PTFE), a copolymer of tetrafluoroethylene and perfluoroalkyl vinyl ether (PFA), a copolymer of tetrafluoroethylene and hexafluoropropylene (FEP), and polychlorotriethylene. Examples thereof include films of fluoroethylene (PCTFE), a copolymer of tetrafluoroethylene and ethylene (ETFE), polyvinylidene fluoride (PVdF), polyvinyl fluoride (PVF), and the like.

(Composite film)
A composite film made of an acrylic polymer and a urethane polymer is a composite film having flexibility and water resistance on a curved surface while achieving both high strength and high elongation at break.

<Acrylic polymer for composite film>
The acrylic polymer contained in the composite film is an acrylic polymer containing at least a (meth) acrylic acid monomer and a monofunctional (meth) acrylic monomer having a homopolymer glass transition temperature (Tg) of 0 ° C. or higher as monomer components. Based copolymer (hereinafter also referred to as “acrylic component”). In addition, the aspect in which an acrylic component further contains the monofunctional (meth) acrylic-type monomer whose glass transition temperature (Tg) of a homopolymer is less than 0 degreeC as a monomer component is preferable.

  In the composite film, the (meth) acrylic acid monomer is a (meth) acrylic monomer having a carboxyl group, and examples thereof include acrylic acid, methacrylic acid, maleic acid, and crotonic acid. Among these, acrylic acid is particularly preferable. The content of the (meth) acrylic acid monomer in the acrylic component is 1% by weight or more and 15% by weight or less, and preferably 2% by weight or more and 10% by weight or less. If the content of the (meth) acrylic acid monomer is less than 1% by weight, it takes a long time for the reaction, making it very difficult to form a film, and there may be a problem that the strength of the film is not sufficient. . When the content of the (meth) acrylic acid monomer exceeds 15% by weight, the water absorption rate of the film increases, which may cause a problem in water resistance. The (meth) acrylic acid monomer greatly affects the compatibility with the urethane component and the acrylic component, and is an essential component having a very important function.

  In the composite film, the monofunctional (meth) acrylic monomer having a Tg of 0 ° C. or higher is preferably at least one selected from the group consisting of acryloyl morpholine, isobornyl acrylate, and dicyclopentanyl acrylate, and acryloyl morpholine. And / or isobornyl acrylate, or acryloylmorpholine and / or dicyclopentanyl acrylate is more preferable, and isobornyl acrylate is particularly preferable.

  The content of the monofunctional (meth) acrylic monomer having a Tg of 0 ° C. or higher is preferably 20 wt% or more and 99 wt% or less in the acrylic component, and is 30 wt% or more and 98 wt% or less. Is more preferable. If the content of such monofunctional (meth) acrylic monomer is less than 20% by weight, there may be a problem that the strength of the film is not sufficient, and if it exceeds 99% by weight, the rigidity of the film will increase too much and become brittle. There is.

  In the composite film, the monofunctional (meth) acrylic monomer having a Tg of less than 0 ° C. includes, for example, n-butyl acrylate, 2-ethylhexyl acrylate, isooctyl acrylate, isobutyl acrylate, 2-methoxyethyl acrylate, tetrahydro Examples include furfuryl acrylate, phenoxyethyl acrylate, ethoxyethyl acrylate, and 3-methoxybutyl acrylate. These can be used alone or in combination of two or more.

  In the composite film, it is particularly preferable to use n-butyl acrylate as a monofunctional (meth) acrylic monomer having a Tg of less than 0 ° C. A monofunctional (meth) acrylic monomer having a Tg of less than 0 ° C. may not be contained (content is 0% by weight). However, when it is contained, the content is from 0% by weight in the acrylic component. The amount is preferably 50% by weight or less, more preferably more than 0% by weight and 45% by weight or less. When the content of the monofunctional (meth) acrylic monomer exceeds 50% by weight, there may be a problem that the strength of the film is not sufficient.

  The type, combination, amount of use, and the like of the (meth) acrylic monomer are appropriately determined in consideration of compatibility with urethane, polymerizability at the time of photocuring such as radiation, and characteristics of the high molecular weight obtained.

  In the composite film, together with the (meth) acrylic monomer, vinyl acetate, vinyl propionate, styrene, acrylamide, methacrylamide, mono- or diester of maleic acid and derivatives thereof, N-methylolacrylamide, glycidyl acrylate, glycidyl methacrylate, N, N-dimethylaminoethyl acrylate, N, N-dimethylaminopropyl methacrylamide, 2-hydroxypropyl acrylate, N, N-dimethylacrylamide, N, N-diethylacrylamide, imide acrylate, N-vinylpyrrolidone, oligoester acrylate, ε -Caprolactone acrylate, dicyclopentanyl (meth) acrylate, dicyclopentenyl (meth) acrylate, methoxylated cyclododecatriene Acrylate may be copolymerized monomer such as methoxyethyl acrylate. Note that the types and amounts of the monomers to be copolymerized are appropriately determined in consideration of the characteristics of the composite film.

  In addition, other polyfunctional monomers can be added within a range that does not impair the characteristics. Polyfunctional monomers include ethylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate, hexanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, and pentaerythritol. Examples include tri (meth) acrylate, dipentaerythritol hexa (meth) acrylate, urethane acrylate, epoxy acrylate, and polyester acrylate. Particularly preferred is trimethylolpropane tri (meth) acrylate.

  The polyfunctional monomer can be contained in the range of 1 to 20 parts by weight with respect to 100 parts by weight of the acrylic monomer. If the content of the polyfunctional monomer is 1 part by weight or more, the cohesive force of the composite film is sufficient, and if it is 20 parts by weight or less, the elastic modulus does not become too high, and the unevenness of the adherend surface is reduced. Can follow.

<Urethane polymer for composite film>
The urethane polymer used for the composite film (hereinafter also referred to as “urethane component”) is obtained by reacting a diol with a diisocyanate. In general, a catalyst is used for the reaction between the hydroxyl group of the diol and the isocyanate, but the reaction can be promoted without using an environmental load catalyst such as dibutyltin dilaurate or tin octoate.

  Examples of the low molecular weight diol include divalent alcohols such as ethylene glycol, diethylene glycol, propylene glycol, butylene glycol, and hexamethylene glycol.

  Moreover, as a high molecular weight diol, polyether polyol obtained by addition polymerization of ethylene oxide, propylene oxide, tetrahydrofuran or the like, or the above-mentioned divalent alcohol, 1,4-butanediol, 1,6-hexanediol And polyester polyols composed of polycondensates of dihydric basic acids such as adipic acid, azelaic acid and sebacic acid, acrylic polyols, carbonate polyols, epoxy polyols and caprolactone polyols. Among these, for example, polyoxytetramethylene glycol (PTMG), polyalkylene carbonate diol (PCD) and the like are preferably used.

  Examples of the acrylic polyol include a copolymer of a monomer having a hydroxyl group, a copolymer of a hydroxyl group-containing substance and an acrylic monomer, and the like. Examples of the epoxy polyol include an amine-modified epoxy resin.

  In the composite film, the diol can be used alone or in combination in consideration of solubility in acrylic monomers, reactivity with isocyanate, and the like. When the strength is required, it is effective to increase the amount of the urethane hard segment by the low molecular weight diol. When importance is attached to elongation, a diol having a large molecular weight is preferably used alone. Polyether polyols are generally inexpensive and have good water resistance, and polyester polyols have high strength. In the present invention, the type and amount of the polyol can be freely selected according to the use and purpose, and the viewpoints such as the properties of the base material to be applied, reactivity with isocyanate, compatibility with acrylic, etc. From the above, the type, molecular weight and amount of use of the polyol can be selected as appropriate.

≪Diisocyanate for urethane polymer≫
Examples of the diisocyanate include aromatic, aliphatic and alicyclic diisocyanates, dimers and trimers of these diisocyanates. Examples of aromatic, aliphatic, and alicyclic diisocyanates include tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), xylylene diisocyanate (XDI), naphthylene diisocyanate (NDI), and phenolene diisocyanate (PPDI). m-tetramethylxylylene diisocyanate (TMXDI), methylcyclohexane diisocyanate (hydrogenated TDI), dicyclohexylmethane diisocyanate (hydrogenated MDI), cyclohexane diisocyanate (hydrogenated PPDI), bis (isocyanatomethyl) cyclohex Xan (hydrogenated XDI), norbornene diisocyanate (NBDI), isophorone diisocyanate (IPDI), hexamethylene diisocyanate (HDI), butanedi Cyanate, hexamethylene diisocyanate 2,4-trimethyl hexamethylene diisocyanate to 2,4,4-trimethyl like. Moreover, these dimers, trimers, and polyphenylmethane diisocyanate are used. Examples of the trimer include isocyanurate type, burette type, and allophanate type, and can be used as appropriate.

  Among these, in particular, methylcyclohexane diisocyanate (hydrogenated TDI), dicyclohexylmethane diisocyanate (hydrogenated MDI), cyclohexane diisocyanate (hydrogenated PPDI), bis (isocyanatomethyl) cyclohexane (hydrogenated) XDI), norbornene diisocyanate (NBDI), isophorone diisocyanate (IPDI), hexamethylene diisocyanate (HDI), butane diisocyanate, 2,4-trimethylhexamethylene diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate and other fats Aliphatic and alicyclic diisocyanates are preferably used. This is because it is not preferable to use an aromatic diisocyanate containing a benzene ring because a colored substance having a conjugated structure is easily generated by a photoreaction. In the present invention, it does not contain a benzene ring, is hardly yellowed, and has no yellow color. Modified aliphatic and alicyclic diisocyanates are preferably used.

  These diisocyanates can be used alone or in combination. From the viewpoints of the characteristics of the support to which the composite film is applied (applied or the like), solubility in acrylic monomers, reactivity with hydroxyl groups, and the like, the type and combination of diisocyanates may be appropriately selected.

  Urethane polymers include hexamethylene diisocyanate (HDI), hydrogenated tolylene diisocyanate (HTDI), hydrogenated 4,4-diphenylmethane diisocyanate (HMDI), isophorone diisocyanate (IPDI), and hydrogenated xylene diisocyanate (HXDI). It is preferably formed using at least one diisocyanate selected from the group consisting of: hydrogenated xylene diisocyanate is particularly preferred.

  The amount of the diol component and diisocyanate component used to form the urethane polymer is preferably [NCO] / [OH] (equivalent ratio) of 1.1 or more and 2.0 or less, and 1.12 or more. 1.60 or less, more preferably 1.15 or more and 1.40 or less. If the [NCO] / [OH] (equivalent ratio) is less than 1.1, the molecular weight of the urethane polymer becomes too high, the viscosity of the composite film precursor (syrup solution) becomes large, and the work in the subsequent sheeting process can be performed. It can be difficult. On the other hand, when [NCO] / [OH] (equivalent ratio) exceeds 2.0, the molecular weight of the urethane polymer becomes small, and the breaking strength tends to decrease.

<Acrylic component / urethane component ratio in composite film>
The ratio of the acrylic component and the urethane component forming the composite film is, by weight ratio, the acrylic component / urethane component is 0.25 or more and 4.00 or less, preferably 0.429 or more and 2.333 or less. Especially preferably, it is 0.538 or more and 1.857 or less. When the acrylic component / urethane component is less than 0.25, the viscosity of the syrup solution becomes large, and the work may be difficult in the subsequent sheet forming step. On the other hand, when the acrylic component / urethane component exceeds 4.00, the amount of urethane polymer in the composite film becomes less than 25%, the tensile strength at break is lowered, and it may not be practically used.

  A hydroxyl group-containing acrylic monomer may be added to the urethane polymer. By adding a hydroxyl group-containing acrylic monomer, a (meth) acryloyl group can be introduced at the molecular end of the urethane prepolymer, and a copolymerizability with a (meth) acrylic monomer is imparted. It is also possible to improve the S—S (stress-strain) characteristics such as the breaking strength. Examples of the hydroxyl group-containing acrylic monomer used here include hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, hydroxybutyl (meth) acrylate, hydroxyhexyl (meth) acrylate, and the like. It is preferable that the usage-amount of a hydroxyl-containing acrylic monomer is 0.1-10 weight part with respect to 100 weight part of urethane polymers, More preferably, it is 1-5 weight part.

(Film stabilizer)
From the viewpoint of weather resistance, a film (including a composite film) can be appropriately treated with a weather resistance stabilizer. The treatment using the weather stabilizer is (i) a treatment for applying the weather stabilizer to the surface of the film, supporting the film by transfer or the like, (ii) a treatment for kneading the weather stabilizer into the film, or ( iii) It can be carried out by using these (i) and (ii) in combination.

  As said weather resistance stabilizer, a ultraviolet absorber, a light stabilizer, antioxidant, etc. are mentioned, 1 type (s) or 2 or more types can be used.

(UV absorber)
As the UV absorber, known UV absorbers such as benzotriazole UV absorbers, triazine UV absorbers, benzophenone UV absorbers, and benzoate UV absorbers can be appropriately used. The ultraviolet absorber can use 1 type (s) or 2 or more types.

Examples of benzotriazole ultraviolet absorbers include 2- (2-hydroxy-5-tert-butylphenyl) -2H-benzotriazole, benzenepropanoic acid and 3- (2H-benzotriazol-2-yl)- Ester compound with 5- (1,1-dimethylethyl) -4-hydroxy (C ₇ -C ₉ side chain and straight chain alkyl), octyl-3- [3-tert-butyl-4-hydroxy-5 (5-Chloro-2H-benzotriazol-2-yl) phenyl] propionate and 2-ethylhexyl-3- [3-tert-butyl-4-hydroxy-5- (5-chloro-2H-benzotriazole-2) -Yl) phenyl] propionate, 2- (2H-Benzotriazol-2-yl) -4,6-bis (1-methyl-1-pheni) Ruethyl) phenol, 2- (2H-benzotriazol-2-yl) -6- (1-methyl-1-phenylethyl) -4- (1,1,3,3-tetramethylbutyl) phenol, Reaction product of methyl-3- (3- (2H-benzotriazol-2-yl) -5-tert-butyl-4-hydroxyphenyl) propionate / polyethylene glycol 300, 2- (2H-benzotriazol-2-yl ) -P-cresol, 2- [5-chloro (2H) -benzotriazol-2-yl] -4-methyl-6- (tert-butyl) phenol 2- (2H-benzotriazol-2-yl) -4 , 6-Di-tert-pentylphenol, 2- (2H-benzotriazol-2-yl) -4- (1,1,3,3-tetramethylbutyl) pheno 2,2′-methylenebis [6- (2H-benzotriazol-2-yl) -4- (1,1,3,3-tetramethylbutyl) phenol], methyl-3- (3- (2H -Benzotriazol-2-yl) -5-tert-butyl-4-hydroxyphenyl) propionate and polyethylene glycol 300 reaction product, 2- (2H-benzotriazol-2-yl) -6-dodecyl-4- Methylphenol, 2- [2-hydroxy-3- (3,4,5,6-tetrahydrophthalimido-methyl) -5-methylphenyl] benzotriazole, 2,2′-methylenebis [6- (benzotriazole-2- Yl) -4-tert-octylphenol] and the like.

Moreover, as a hydroxyphenyl triazine type ultraviolet absorber, for example, 2- (4,6-bis (2,4-dimethylphenyl) -1,3,5-triazin-2-yl) -5-hydroxyphenyl and [ _(C 10 _{-C 16,} predominantly alkyloxy _C 12 _{-C 13)} reaction products of methyl] oxirane, 2- (2,4-dihydroxyphenyl) -4,6-bis - (2,4-dimethylphenyl ) -1,3,5-triazine and the reaction product of (2-ethylhexyl) -glycidic acid ester, 2,4-bis [2-hydroxy-4-butoxyphenyl] -6- (2,4- Dibutoxyphenyl) -1,3,5-triazine, 2- (4,6-diphenyl-1,3,5-triazin-2-yl) -5-[(hexyl) oxy] -phenol, 2- ( 2-Hide And loxy-4- [1-octyloxycarbonylethoxy] phenyl) -4,6-bis (4-phenylphenyl) -1,3,5-triazine.

  Examples of the benzophenone-based ultraviolet absorber include 2-hydroxy-4-n-octyloxybenzophenone.

  Examples of the benzoate UV absorber include 2,4-di-tert-butylphenyl-3,5-di-tert-butyl-4-hydroxybenzoate.

Commercially available benzotriazole ultraviolet absorbers include, for example, “TINUVIN PS” manufactured by Ciba Japan as 2- (2-hydroxy-5-tert-butylphenyl) -2H-benzotriazole, benzenepropane As an ester compound of an acid and 3- (2H-benzotriazol-2-yl) -5- (1,1-dimethylethyl) -4-hydroxy (C ₇ -C ₉ side chain and straight chain alkyl), “TINUVIN 384-2” manufactured by Japan, Octyl-3- [3-tert-butyl-4-hydroxy-5- (5-chloro-2H-benzotriazol-2-yl) phenyl] propionate and 2-ethyl Xyl-3- [3-tert-butyl-4-hydroxy-5- (5-chloro-2H-benzotriazole-2) “TINUVIN 109”, 2- (2H-benzotriazol-2-yl) -4,6-bis (1-methyl-1-phenylethyl) phenol manufactured by Ciba Japan as a mixture with -yl) phenyl] propionate “TINUVIN 900” manufactured by Ciba Japan, 2- (2H-benzotriazol-2-yl) -6-methyl-1-phenylethyl) -4- (1,1,3,3-tetramethyl Butyl) phenol is “TINUVIN 928” manufactured by Ciba Japan, methyl-3- (3- (2H-benzotriazol-2-yl) -5-tert-butyl-4-hydroxyphenyl) propionate / polyethylene glycol 300 As a reaction product, “TINUVIN 1130” manufactured by Ciba Japan, 2- (2H-ben) “TINUVIN P” manufactured by Ciba Japan as triazol-2-yl) -p-cresol, 2- [5-chloro (2H) -benzotriazol-2-yl] -4-methyl-6- (tert-butyl) ) “TINUVIN 326” manufactured by Ciba Japan as phenol, “TINUVIN 328” manufactured by Ciba Japan as 2- (2H-benzotriazol-2-yl) -4,6-di-tert-pentylphenol, 2 -(2H-benzotriazol-2-yl) -4- (1,1,3,3-tetramethylbutyl) phenol "TINUVIN 329", 2,2'-methylenebis [6- ( 2H-benzotriazol-2-yl) -4- (1,1,3,3-tetramethylbutyl) phenol] “TINUVIN 360” from Chapane, Ciba as the reaction product of methyl-3- (3- (2H-benzotriazol-2-yl) -5-tert-butyl-4-hydroxyphenyl) propionate and polyethylene glycol 300 “TINUVIN 213” manufactured by Japan, “TINUVIN 571” manufactured by Ciba Japan as 2- (2H-benzotriazol-2-yl) -6-dodecyl-4-methylphenol, 2- [2-hydroxy- 3- (3,4,5,6-tetrahydrophthalimido-methyl) -5-methylphenyl] benzotriazole, “Sumisorb 250” manufactured by Sumitomo Chemical Co., Ltd., 2,2′-methylenebis [6- (benzotriazol-2-yl) ) -4-tert-octylphenol] manufactured by ADEKA Such as "ADKSTAB LA31", and the like.

Moreover, as a commercially available hydroxyphenyl triazine type ultraviolet absorber, for example, 2- (4,6-bis (2,4-dimethylphenyl) -1,3,5-triazin-2-yl)- As a reaction product of 5-hydroxyphenyl and [(C ₁₀ -C ₁₆ , mainly C ₁₂ -C ₁₃ alkyloxy) methyl] oxirane, “TINUVIN 400”, 2- (2, 4- As a reaction product of dihydroxyphenyl) -4,6-bis- (2,4-dimethylphenyl) -1,3,5-triazine and (2-ethylhexyl) -glycidic acid ester, manufactured by Ciba Japan “TINUVIN 405”, 2,4-bis [2-hydroxy-4-butoxyphenyl] -6- (2,4-dibutoxyphenyl) -1,3,5-tria “TINUVIN 460” manufactured by Ciba Japan Co., Ltd., Ciba Japan as 2- (4,6-diphenyl-1,3,5-triazin-2-yl) -5-[(hexyl) oxy] -phenol “TINUVIN 1577” manufactured by the company, 2- (2-hydroxy-4- [1-octyloxycarbonylethoxy] phenyl) -4,6-bis (4-phenylphenyl) -1,3,5-triazine Examples thereof include “TINUVIN 479” manufactured by Japan.

  Examples of commercially available benzophenone ultraviolet absorbers include “CHIMASSORB 81” manufactured by Ciba Japan. Examples of the benzoate-based ultraviolet absorber include “TINUVIN 120” manufactured by Ciba Japan as 2,4-di-tert-butylphenyl-3,5-di-tert-butyl-4-hydroxybenzoate. Can be mentioned.

  The amount of the UV absorber used is preferably 0.1% by weight or more and 4.0% by weight or less, preferably 0.5% by weight or more and 2.0% by weight or less, with respect to 100% by weight of the film. Is more preferable. If it is 0.1% by weight or more, absorption of ultraviolet light causing deterioration or coloring is sufficient, and if it is 4.0% by weight or less, coloring by the ultraviolet absorber itself is not caused.

(Light stabilizer)
Examples of the light stabilizer include hindered amine light stabilizers and benzoate light stabilizers. Of these, hindered amine light stabilizers (HALS) are preferred. 1 type (s) or 2 or more types can be used for a photostabilizer.

  As the hindered amine light stabilizer, for example, those represented by the following formula (I) are preferable.

(Wherein R ¹¹ is an alkylene group, an alkyl group, or an ether group, and R ¹² , R ¹³ , R ¹⁴ , R ¹⁵ , R ¹⁶ , and R ¹⁷ are each independently a hydrogen atom or optionally substituted. An alkyl group or an alkoxy group.)

  As a commercially available hindered amine light stabilizer, for example, as a light stabilizer which is a polymer of dimethyl succinate and 4-hydroxy-2,2,6,6-tetramethyl-1-piperidineethanol, TINUVIN 622 "(manufactured by Ciba Japan), a polymer of dimethyl succinate and 4-hydroxy-2,2,6,6-tetramethyl-1-piperidineethanol and N, N ', N", N' '' -Tetrakis- (4,6-bis- (butyl- (N-methyl-2,2,6,6-tetramethylpiperidin-4-yl) amino) -triazin-2-yl) -4,7- As a light stabilizer which is a one-to-one reaction product with diazadecane-1,10-diamine, “TINUVIN 119” (manufactured by Ciba Japan), dibutylamine, 1,3-triazine, N, The weight of '-bis (2,2,6,6-tetramethyl-4-piperidyl-1,6-hexamethylenediamine and N- (2,2,6,6-tetramethyl-4-piperidyl) butylamine As a light stabilizer which is a condensate, “TINUVIN 2020” (manufactured by Ciba Japan), poly [{6- (1,1,3,3-tetramethylbutyl) amino-1,3,5-triazine-2, 4-diyl} {(2,2,6,6-tetramethyl-4-piperidyl) imino} hexamethylene {(2,2,6,6-tetramethyl-4-piperidyl) imino}] As “TINUVIN 944” (manufactured by Ciba Japan), bis (1,2,2,6,6-pentamethyl-4-piperidyl) sebacate and methyl 1,2,2,6,6-pentamethyl-4-piperidyl Sebakei "TINUVIN 765" (manufactured by Ciba Japan Co., Ltd.) as a light stabilizer that is a mixture of TINUVIN 770 as a light stabilizer that is bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate ( Ciba Japan), reaction of decanedioic acid bis (2,2,6,6-tetramethyl-1- (octyloxy) -4-piperidinyl) ester (1,1-dimethylethyl hydroperoxide) with octane As a light stabilizer which is a product, “TINUVIN 123” (manufactured by Ciba Japan), bis (1,2,2,6,6-pentamethyl-4-piperidyl) [[3,5-bis (1,1- “TINUVIN 144” (manufactured by Ciba Japan), Shiku as a light stabilizer that is dimethylethyl) -4-hydroxyphenyl] methyl] butylmalonate Reaction product of hexane and peroxide N-butyl-2,2,6,6-tetramethyl-4-piperidineamine-2,4,6-trichloro-1,3,5-triazine and 2-aminoethanol TINUVIN 152 (manufactured by Ciba Japan), bis (1,2,2,6,6-pentamethyl-4-piperidyl) sebacate and methyl-1,2,2 , 6,6-pentamethyl-4-piperidyl sebacate is a light stabilizer such as “TINUVIN 292” (manufactured by Ciba Japan).

  The amount of the light stabilizer used is preferably 0.1% by weight or more and 4.0% by weight or less, and 0.5% by weight or more and 2.0% by weight or less with respect to 100% by weight of the film. More preferably. When the light stabilizer is used in an amount of 0.1% by weight or more, the deterioration preventing function is sufficiently developed, and when it is 4.0% by weight or less, coloring by the light stabilizer itself is not caused.

(Antioxidant)
As the antioxidant, known antioxidants such as hindered phenol-based antioxidants, phosphorus-based processing heat stabilizers, lactone-based processing heat stabilizers, and sulfur-based heat stabilizers can be used. One kind or two or more kinds of antioxidants can be used.

  The amount of the antioxidant used is preferably 3% by weight or less, more preferably 1% by weight or less, and still more preferably 0.01 to 0.5% by weight with respect to 100% by weight of the film.

  Further, fillers, pigments, colorants, flame retardants, antistatic agents and the like that do not impair the effects of the present invention can be added within a range that does not impair the effects of the present invention. These additives are used in normal amounts depending on the type.

  In the present invention, the film constituting the protective layer can be subjected to a surface treatment having a contamination preventing effect. For example, a coat layer (surface treatment layer) made of a fluoroethylene vinyl ether copolymer is formed on the surface of the film. The fluoroethylene vinyl ether copolymer is preferably one represented by the following formula (II) having fluoroethylene units and vinyl ether units alternately.

In the formula (II), X represents a fluorine atom, a chlorine atom or a bromine atom, R _a represents _a hydrogen atom or a C _{1 to} C ₁₀ alkyl group, R _b represents a C _{1 to} C ₁₆ alkyl group, R _c represents a C _{1 to} C ₁₆ alkylene group. Note that m and n are integers.

  The weight average molecular weight of the fluoroethylene vinyl ether alternating copolymer is 1,000 to 2,000,000, preferably 5,000 to 1,000,000, and more preferably 10,000 to 500,000. is there. In the present invention, m and n in the above formula (II) are selected in the range where the weight average molecular weight of the fluoroethylene vinyl ether alternating copolymer is 1,000 to 2,000,000.

The weight average molecular weight of the fluoroethylene vinyl ether alternating copolymer can be measured by the GPC method. That is, the fluoroethylene vinyl ether alternating copolymer is adjusted to 2.0 g / L using a THF solution and then allowed to stand for 12 hours. Then, this solution is filtered with a 0.45 μm membrane filter, and GPC measurement is performed on the filtrate under the following measurement conditions using “HLC-8120GPC” manufactured by Tosoh Corporation as an analyzer.
Measurement condition:
Column TSKgel GMH-H (S) x 2
Column size 7.8mm ID x 300mm
Eluent THF
Flow rate 0.5mL / min
Detector RI
Column temperature 40 ° C
Injection volume 100μL

  In addition, it is preferable that the thickness of a coating layer is 2-50 micrometers, More preferably, it is 5-40 micrometers, More preferably, it is 8-30 micrometers. When the thickness of the coat layer is less than 2 μm, a defect site where the coat layer is not formed, such as pinholes, is likely to occur, and the characteristics of the coat layer may not be sufficiently exhibited. On the other hand, if it exceeds 50 μm, the physical properties of the coating layer may deteriorate the physical properties of the composite film.

(Crosslinking of composite film and coat layer)
The coat layer is preferably crosslinked with the film and has a crosslinking point. A structure having a crosslinking point can be obtained, for example, by combining the component constituting the coat layer and the component constituting the composite film to form a crosslinking point. For example, if there is a residual isocyanate group in the isocyanate used to form the coat layer, this residual isocyanate group may react with the hydroxyl group of the urethane polymer / acrylic monomer mixture of the composite film to form a crosslinking point. it can. Alternatively, if the hydroxyl group of the fluoroethylene vinyl ether alternating copolymer used for forming the coating layer remains, it can react with the isocyanate group present in the coating solution for composite film to form a crosslinking point. it can. Therefore, when the composite film coating solution is applied, it is necessary that the remaining isocyanate group or the remaining hydroxyl group be present in the coat layer so that it can react. Moreover, it is preferable to apply the composite film coating solution before the crosslinking reaction of the coating layer is completely completed.

  Thus, if the coat layer and the composite film form a cross-linked structure, excellent adhesion is exhibited between the coat layer and the composite film, and the coat layer maintains excellent adhesion to the composite film for a long period of time. Can continue. Therefore, even if an application sheet is affixed for positioning the protective film, the coating layer is not peeled off when the application sheet is peeled off.

  In order for the coat layer and the composite film to form a cross-linked structure, the coat layer needs to be composed of an alternating copolymer of fluoroethylene vinyl ether, and contains an acrylic polymer and a urethane polymer as the composite film. It is necessary to.

  The method for forming the crosslinked structure is not particularly limited. For example, after the coating layer is applied, dried and cured, the coating film surface is applied in a semi-cured state to form a crosslinking point. If the remaining isocyanate groups can react even when the surface of the coat layer is completely cured, a coating solution for composite film can be applied thereon to form a crosslinking point. Therefore, what is necessary is just to adjust the kind of component, usage-amount, etc. which are used for formation of a coating layer and a composite film so that a crosslinking point may be formed. For example, in a state in which the remaining isocyanate group can react, a crosslinked structure can be formed by applying a composite film coating solution within 24 hours and causing a photocuring reaction. In addition, if the remaining isocyanate group can react and is stored at about 5 ° C., a crosslinked structure can be formed by applying a composite film coating solution within 5 days and allowing it to undergo photocuring reaction. it can. If a hydroxyl group-containing monomer is reacted with the isocyanate crosslinking agent in advance, the residual isocyanate group can be reacted even after being stored at 50 ° C. for one week or longer.

(Manufacture of coat layer)
A fluoroethylene vinyl ether alternating polymer is dissolved in a solvent, and a polyfunctional isocyanate is added thereto to form a coating layer coating solution, and this solution is used to form a coating layer. For example, this solution is applied onto a polyethylene film that has been subjected to a release treatment, and dried to form a coat layer. On this coat layer, a mixture containing a urethane polymer and an acrylic monomer (composite film coating solution) was applied, and the coat layer was crosslinked to the composite film by irradiating ultraviolet rays or the like (the composite film was coated). It is possible to obtain a laminate having a structure in which the layers are crosslinked.

  Moreover, after making a hydroxyl-containing monomer and polyfunctional isocyanate react, fluoroethylene vinyl ether alternating polymer is added and a coating layer is formed using this solution. For example, this solution is applied onto a peeled PET film and dried to form a coat layer. On this coating layer, a coating solution for a composite film containing an acrylic monomer and a urethane polymer was applied, and cured by irradiation with ultraviolet rays or the like, whereby the coating layer was crosslinked to the composite film (the composite film was coated). It is possible to obtain a laminate having a structure in which the layers are crosslinked.

  Examples of the polyfunctional isocyanate having two or more isocyanate groups in the molecule include hydrogenated xylylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, hydrogenated diphenylmethane diisocyanate, and ethylene diisocyanate. Bifunctional isocyanates such as 1,4-tetramethylene diisocyanate, trimethylhexamethylene diisocyanate, norbornene diisocyanate, Desmodur N3200 (manufactured by Sumika Bayer Urethane Co., Ltd.), Coronate L, HL, HX (manufactured by Nippon Polyurethane Co., Ltd.) ), Trifunctional isocyanates such as Takenate D-140N, D-127, D-110N (Mitsui Chemical Polyurethane Co., Ltd.). In the present invention, these polyfunctional isocyanates can be used alone or in combination of two or more.

  When reacting a hydroxyl group-containing monomer with a polyfunctional isocyanate, the ratio of the number of moles of hydroxyl group [OH] of the hydroxyl group-containing monomer to the number of moles of isocyanate group [NCO] of the polyfunctional isocyanate ([OH] / [NCO]) Is 0.05 to 0.5, preferably 0.05 to 0.4, and more preferably 0.05 to 0.3.

  The hydroxyl group-containing monomer has one or more hydroxyl groups in the molecule and one or more (meth) acryl groups in the molecule. Examples of the hydroxyl group-containing monomer include 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 4-hydroxybutyl acrylate, 4-hydroxybutyl methacrylate, 1,4-cyclohexanedimethanol monoacrylate, and 1,4-cyclohexane. Xanthodimethanol monomethacrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, pentaerythritol acrylate and the like. In the present invention, these hydroxyl group-containing monomers can be used alone or in combination of two or more.

  In the present invention, the thickness of the protective layer 4 is not particularly limited, but is preferably 5 to 100 μm. In addition, "thickness" here means the thickness of the film when the protective layer is composed of a single film, a surface treatment layer (coat layer) with a weathering stabilizer on the film surface, and / or a surface treatment layer for preventing contamination ( When the coating layer is formed, it is the total thickness of the film and the surface treatment layer (coating layer). If the thickness of the protective layer exceeds 100 μm, there is a tendency to increase the weight and cost of the target electromagnetic wave absorbing pressure-sensitive adhesive sheet, and if it is less than 5 μm, the amount of ultraviolet absorption increases and the durability of the target electromagnetic wave absorbing pressure-sensitive adhesive sheet increases. Property, weather resistance, etc. tend to decrease.

  The protective layer 4 has a film attached to the divided conductive film 1 via an adhesive layer. The pressure-sensitive adhesive used for this pressure-sensitive adhesive layer is not particularly limited, and various pressure-sensitive adhesives can be used. Examples thereof include acrylic adhesives, rubber adhesives, vinyl alkyl ether adhesives, silicone adhesives, polyester adhesives, polyamide adhesives, urethane adhesives, and epoxy adhesives. The pressure-sensitive adhesive layer may be formed in a form in which a base material such as a nonwoven fabric is inserted in the layer. Although the thickness of an adhesive layer is not specifically limited, Generally about 5-300 micrometers is preferable.

[Bubble-containing pressure-sensitive adhesive layer]
The bubble-containing pressure-sensitive adhesive layer used in the present invention is a pressure-sensitive adhesive layer formed from a pressure-sensitive adhesive containing bubbles, and preferably a pressure-sensitive adhesive formed by a pressure-sensitive adhesive containing bubbles and hollow microspheres. It is an agent layer. The bubble-containing pressure-sensitive adhesive layer improves the followability to curved surfaces and uneven surfaces, and improves the adhesion performance to curved surfaces and uneven surfaces, and is a strong and stable adhesion state to outdoor buildings and concrete structures Can be formed.

  The pressure-sensitive adhesive (pressure-sensitive adhesive) is not particularly limited, and a known pressure-sensitive adhesive can be used. 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 Agents, polyester-based adhesives, polyamide-based adhesives, urethane-based adhesives, fluorine-based adhesives, epoxy-based adhesives, and the like. Among these, from the viewpoint of strong adhesiveness, an acrylic pressure-sensitive adhesive and / or a rubber-based pressure-sensitive adhesive is preferable, and an acrylic pressure-sensitive adhesive is more preferable.

  Examples of the rubber adhesive include natural rubber, styrene-isoprene-styrene block copolymer (SIS block copolymer), styrene-butadiene-styrene block copolymer (SBS block copolymer), and styrene-ethylene / butylene. -Rubber components such as styrene block copolymer (SEBS block copolymer), styrene-butadiene rubber, polybutadiene, polyisoprene, polyisobutylene, butyl rubber, chloroprene rubber, silicone rubber, acrylonitrile-butadiene rubber, ethylene-propylene terpolymer Examples thereof include a rubber-based adhesive used as a base polymer.

Examples of the acrylic pressure-sensitive adhesive include pressure-sensitive adhesives containing an acrylic polymer [particularly, an acrylic polymer having a (meth) acrylic acid ester as a monomer component] as a base polymer (main component). As the main monomer component constituting the acrylic polymer, (meth) acrylic acid alkyl ester ((meth) acrylic acid alkyl ester having a linear or branched alkyl group) can be suitably used. 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, (meth) acrylic acid Isodecyl, undecyl (meth) acrylate, dodecyl (meth) acrylate (Meth) acrylic acid tridecyl, (meth) acrylic acid tetradecyl, (meth) acrylic acid pentadecyl, (meth) acrylic acid hexadecyl, (meth) acrylic acid heptadecyl, (meth) acrylic acid octadecyl, (meth) acrylic acid nonadecyl, ( And (meth) acrylic acid C _1-20 alkyl esters such as (meth) acrylic acid eicosyl. Among them, (meth) acrylic acid C _2-14 alkyl ester is preferable, and (meth) acrylic acid C _2-10 alkyl ester is more preferable. The above “(meth) acrylic acid ester” represents “acrylic acid ester” and / or “methacrylic acid ester”, and the same applies to others.

  Examples of (meth) acrylic acid esters other than the above (meth) acrylic acid alkyl esters include cycloaliphatic hydrocarbon groups such as cyclopentyl (meth) acrylate, cyclohexyl (meth) acrylate, and isobornyl (meth) acrylate. (Meth) acrylic acid ester having aromatic hydrocarbon groups such as (meth) acrylic acid ester and phenyl (meth) acrylate.

  The said (meth) acrylic acid ester can be used individually or in combination of 2 or more types. In addition, since (meth) acrylic acid ester is used as a monomer main component of acrylic polymer, the ratio of (meth) acrylic acid ester [especially (meth) acrylic acid alkyl ester] is, for example, acrylic polymer. The amount is preferably 60% by weight or more, more preferably 80% by weight or more, based on the total amount of monomer components for preparing the above.

  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. The copolymerizable monomers can be used alone or in combination of two or more.

  Examples of the polar group-containing monomer include carboxyl group-containing monomers such as (meth) acrylic acid, itaconic acid, maleic acid, fumaric acid, crotonic acid, and isocrotonic acid, and anhydrides thereof (maleic anhydride and the like). 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, 1 to 30% by weight), preferably 3 to 20% by weight, based on the total amount of monomer components for forming the acrylic polymer. . When the usage-amount of a polar group containing monomer exceeds 30 weight%, for example, the cohesion force of an acrylic adhesive will become high too much, and there exists a possibility that the adhesiveness of an adhesive layer may fall. If the amount of the polar group-containing monomer is too small (for example, less than 1% by weight), the effect of copolymerization of these monomers may not be obtained.

  Examples of the polyfunctional monomer include hexanediol di (meth) acrylate, butanediol di (meth) acrylate, (poly) ethylene glycol di (meth) acrylate, (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 (meth) Examples include 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 forming 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, for example, the cohesive force of the pressure-sensitive adhesive becomes too high, and the pressure-sensitive adhesiveness may decrease. . If the amount of the polyfunctional monomer used is too small (for example, less than 0.01% by weight), the effect of copolymerization of these monomers may not be obtained.

  Examples of copolymerizable monomers other than polar group-containing monomers and polyfunctional monomers include vinyl esters such as vinyl acetate and vinyl propionate, and 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 content of the base polymer (in the case of acrylic pressure-sensitive adhesive, acrylic polymer) is not particularly limited, but is preferably 80% by weight or more, more preferably 85 to 95% by weight, based on the total weight of the pressure-sensitive adhesive layer. It is.

  The pressure-sensitive adhesive may contain an appropriate additive as necessary. For example, depending on the type of base polymer, a crosslinking agent (for example, polyisocyanate-based crosslinking agent, silicone-based crosslinking agent, epoxy-based crosslinking agent, alkyl etherified melamine-based crosslinking agent, etc.), tackifier (for example, rosin derivative resin) , Polyterpene resin, petroleum resin, oil-soluble phenol resin, etc., solid, semi-solid, or liquid at room temperature), polymerization regulator (such as lauryl mercaptan or thioglycolic acid), plasticizer, filler, anti-aging agent, An appropriate additive such as a colorant (such as a pigment or a dye) may be included. Note that a fluorosurfactant is a preferred additive. The addition amount of the additive is not particularly limited. For example, it is preferably 50 parts by weight or less with respect to 100 parts by weight of all monomers for forming the base polymer [for example, all monomer components for forming the acrylic polymer]. More preferably, it is 10 parts by weight or less.

  When preparing the acrylic polymer as the base polymer in the above adhesive, use a curing reaction by heat or active energy rays using a polymerization initiator such as a thermal polymerization initiator or a photopolymerization initiator (photoinitiator). can do. Among these, from the viewpoint of shortening the polymerization time and stability of bubbles when bubbles are contained, a curing reaction (photopolymerization) by active energy rays using a photopolymerization initiator can be preferably used. The said polymerization initiator can be used individually or in combination of 2 or more types.

  Examples of the thermal polymerization initiator include azo polymerization initiators [for example, 2,2′-azobisisobutyronitrile, 2,2′-azobis-2-methylbutyronitrile, 2,2′-azobis. (2-methylpropionic acid) dimethyl, 4,4′-azobis-4-cyanovaleric acid, azobisisovaleronitrile, 2,2′-azobis (2-amidinopropane) dihydrochloride, 2,2′-azobis [ 2- (5-Methyl-2-imidazolin-2-yl) propane] dihydrochloride, 2,2′-azobis (2-methylpropionamidine) disulfate, 2,2′-azobis (N, N′-di) Methyleneisobutylamidine) dihydrochloride, etc.], peroxide polymerization initiators (eg, dibenzoyl peroxide, tert-butylpermaleate, etc.) And redox polymerization initiators. The amount of the thermal polymerization initiator used is not particularly limited as long as it can be conventionally used as a thermal polymerization initiator.

  The photopolymerization initiator is not particularly limited. For example, benzoin ether photopolymerization initiator, acetophenone photopolymerization initiator, α-ketol photopolymerization initiator, aromatic sulfonyl chloride photopolymerization initiator, photo An active oxime photopolymerization initiator, a benzoin photopolymerization initiator, a benzyl photopolymerization initiator, a benzophenone photopolymerization initiator, a ketal photopolymerization initiator, a thioxanthone photopolymerization initiator, and the like can be used.

  Specifically, examples of the benzoin ether photopolymerization initiator include benzoin methyl ether, benzoin ethyl ether, benzoin propyl ether, benzoin isopropyl ether, benzoin isobutyl ether, 2,2-dimethoxy-1,2-diphenylethane- Examples include 1-one and anisole methyl ether. Examples of the acetophenone photopolymerization initiator include 2,2-diethoxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 1-hydroxycyclohexyl phenyl ketone, 4-phenoxydichloroacetophenone, and 4- (t-butyl). Examples include dichloroacetophenone. Examples of the α-ketol photopolymerization initiator include 2-methyl-2-hydroxypropiophenone and 1- [4- (2-hydroxyethyl) phenyl] -2-methylpropan-1-one. . Examples of the aromatic sulfonyl chloride photopolymerization initiator include 2-naphthalenesulfonyl chloride. Examples of the photoactive oxime photopolymerization initiator include 1-phenyl-1,1-propanedione-2- (o-ethoxycarbonyl) -oxime.

  The benzoin photopolymerization initiator includes, for example, benzoin. Examples of the benzyl photopolymerization initiator include benzyl. Examples of the benzophenone-based photopolymerization initiator include benzophenone, benzoylbenzoic acid, 3,3′-dimethyl-4-methoxybenzophenone, polyvinyl benzophenone, α-hydroxycyclohexyl phenyl ketone, and the like. Examples of the ketal photopolymerization initiator include benzyl dimethyl ketal. Examples of the thioxanthone photopolymerization initiator include thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, 2,4-dimethylthioxanthone, isopropylthioxanthone, 2,4-diisopropylthioxanthone, dodecylthioxanthone, and the like.

  The amount of the photopolymerization initiator used is not particularly limited. For example, the total monomer components for forming the base polymer in the pressure-sensitive adhesive [for example, all monomer components for forming the acrylic polymer] are 100 parts by weight. On the other hand, it can be selected from the range of 0.01 to 5 parts by weight (preferably 0.05 to 3 parts by weight).

  In activating the photopolymerization initiator, an active energy beam is irradiated. Examples of such active energy rays include ionizing radiation such as α rays, β rays, γ rays, neutron rays, electron rays, and ultraviolet rays, and ultraviolet rays are particularly preferable. The irradiation energy of the active energy beam, the irradiation time, etc. are not particularly limited as long as the photopolymerization initiator can be activated to cause the reaction of the monomer component.

  The amount of bubbles that can be mixed in the bubble-containing pressure-sensitive adhesive layer can be appropriately selected within a range that does not impair adhesive properties and the like, but is usually 5 to 50% by volume (preferably 10 to 40% by volume) with respect to the total volume of the bubble-containing pressure-sensitive adhesive layer. %, More preferably 12 to 30% by volume, and particularly preferably 15 to 25% by volume). If the amount of bubbles is less than 5% by volume, stress relaxation properties are difficult to obtain, and uneven followability (step absorption) and adhesion may be inferior. Moreover, when it exceeds 50 volume%, the bubble which penetrates an adhesive layer will form, and adhesiveness may be inferior, or a bubble containing adhesive layer may become too soft.

  Basically, the bubbles mixed in the bubble-containing pressure-sensitive adhesive layer are desirably closed-cell type bubbles, but the closed-cell type bubbles and the open-cell type bubbles may be mixed.

  In addition, such bubbles usually have a spherical shape, but may have an irregular spherical shape. In the said bubble, it does not specifically limit as the average bubble diameter (diameter), For example, it can select from the range of 1-1000 micrometers (preferably 10-500 micrometers, More preferably, 30-300 micrometers).

  The gas component contained in the bubbles (hereinafter sometimes referred to as “gas component forming bubbles” or “bubble-forming gas”) is not particularly limited, and is an inert gas such as nitrogen, carbon dioxide, or argon. In addition, various gas components such as air can be used. As the bubble forming gas, when a reaction such as a polymerization reaction is performed after mixing the bubble forming gas, it is important to use a gas that does not inhibit the reaction. As the bubble forming gas, nitrogen is preferable from the viewpoint of not inhibiting the reaction and from the viewpoint of cost.

  By using a hollow microsphere as one of the constituent components of the bubble-containing pressure-sensitive adhesive layer, for example, step absorbability and shear adhesion can be increased, and processability can be improved. The hollow microspheres can be used alone or in combination of two or more.

  The hollow microspheres may be hollow inorganic microspheres or hollow organic microspheres. Specifically, as the hollow inorganic microspheres, for example, glass hollow balloons such as hollow glass balloons; metal compound hollow balloons such as hollow alumina balloons; porcelain hollow balloons such as hollow ceramic balloons, etc. Is mentioned. Examples of the hollow organic microspheres include resin hollow balloons such as hollow acrylic balloons and hollow vinylidene chloride balloons.

  Although it does not restrict | limit especially as an average particle diameter of a hollow microsphere, For example, it can select from the range of 1-500 micrometers (preferably 5-200 micrometers, More preferably, 10-100 micrometers). Here, the average particle diameter is a median diameter (volume basis) based on particle size distribution measurement by a laser diffraction / scattering method.

The specific gravity of the hollow microspheres is not particularly limited, for example, 0.1 to 0.8 g / cm ³ (preferably 0.12 / cm ³⁾ can be selected from the range of. If the specific gravity of the hollow microspheres is less than 0.1 g / cm ³ , when the hollow microspheres are mixed and mixed in the bubble-containing pressure-sensitive adhesive composition, the floating becomes large and difficult to disperse uniformly. On the other hand, if it is larger than 0.8 g / cm ³ , it becomes expensive and the cost becomes high.

  The amount of the hollow microspheres used is not particularly limited. For example, it is 5 to 50% by volume (% by volume), preferably 10 to 40% by volume, more preferably 15% with respect to the total volume of the bubble-containing pressure-sensitive adhesive layer. It can be selected from a range of -40% by volume, particularly preferably 20-35% by volume. When the usage amount of the hollow microspheres is less than 5% by volume, the effect of adding the hollow microspheres may be reduced. On the other hand, when the usage amount exceeds 50% by volume, Adhesive strength may be reduced.

  The pressure-sensitive adhesive composition for forming the bubble-containing pressure-sensitive adhesive layer is a known monomer component (for example, (meth) acrylic acid ester) that forms the base polymer of the pressure-sensitive adhesive, a polymerization initiator, various additives, and the like. It can be prepared by mixing using a technique. Moreover, you may polymerize a monomer component partially as needed, such as viscosity adjustment. Specific examples of the preparation method (in the case of photopolymerization) include, for example, the following procedures. (i) A monomer mixture for preparing a base polymer (for example, (meth) acrylic acid ester or other copolymerizable monomer) and a photopolymerization initiator are mixed to prepare a monomer mixture, (ii) Photopolymerization (for example, ultraviolet polymerization) is performed on the monomer mixture to prepare a composition (syrup) in which only a part of the monomer components is polymerized. Next, (iii) the resulting syrup is blended with hollow microspheres, a fluorosurfactant and other additives. Furthermore, a bubble-containing pressure-sensitive adhesive composition can be obtained by introducing and mixing bubbles into the formulation obtained in (iv) and (iii). In addition, the method for preparing the bubble-containing pressure-sensitive adhesive composition is not limited to this. For example, when preparing the syrup, a fluorine-based surfactant or hollow microspheres may be blended in advance during monomer mixing. It may be a preparation method.

  From the viewpoint of allowing air bubbles to be stably mixed and present in the pressure-sensitive adhesive layer, it is preferable to mix and mix the air bubbles as the last component in the pressure-sensitive adhesive composition, for example, as in the preparation method described above. Further, from the viewpoint of stably mixing the bubbles, it is preferable to increase the viscosity of the composition before mixing the bubbles (for example, the composition obtained in the above (iii)). Although it does not specifically limit as a viscosity of the formulation before mixing a bubble, For example, 5-50 Pa.s (BH viscometer, rotor: No.5 rotor, rotation speed: 10 rpm, measurement temperature: 30 degreeC) is preferable. More preferably, it is 10 to 40 Pa · s. When the viscosity is less than 5 Pa · s, the viscosity is too low and the mixed bubbles may immediately coalesce and escape from the system. When the viscosity exceeds 50 Pa · s, the viscosity is too high and the adhesive layer is applied. It may be difficult to form by work. In addition, the said viscosity can be adjusted with the method of mix | blending various polymer components, such as an acrylic rubber and a thickening additive, the method of partially polymerizing the monomer component for forming a base polymer, etc., for example.

  In the method for preparing the bubble-containing pressure-sensitive adhesive composition, the method for mixing the bubbles is not particularly limited, and a known bubble mixing method can be used. For example, as an example of a device, a stator having a large number of fine teeth on a disk having a through-hole at the center, and a stator having a fine tooth on the disk facing the stator with the teeth. An apparatus including a rotor may be used. In this apparatus, a composition for mixing bubbles between teeth on the stator and teeth on the rotor is introduced, and a gas component (bubble forming gas) for forming bubbles through the through-hole while rotating the rotor at high speed is introduced. By introducing, a bubble-containing pressure-sensitive adhesive composition in which a bubble-forming gas is finely dispersed and mixed can be obtained.

  In order to suppress or prevent the coalescence of bubbles, it is preferable to continuously perform from the mixing of bubbles to the formation of the pressure-sensitive adhesive layer as a series of steps. That is, it is preferable to prepare a bubble-containing pressure-sensitive adhesive composition by mixing bubbles as described above, and subsequently form a bubble-containing pressure-sensitive adhesive layer using the pressure-sensitive adhesive composition.

  The gel fraction of the bubble-containing pressure-sensitive adhesive layer 5 is preferably 60 to 90% (% by weight), and more preferably 70 to 80%. When the gel fraction is lower than 60%, the degree of cross-linking tends to be low, and the weather resistance, durability, etc. tend to decrease. When the gel fraction is higher than 90%, the degree of cross-linking becomes too high, so the resilience resistance Defects and poor adhesion tend to occur.

  As shown in FIG. 1, the bubble-containing pressure-sensitive adhesive layer 5 is formed on one surface of the electromagnetic wave reflection sheet 3 in the electromagnetic wave absorbing pressure-sensitive adhesive sheet of the present invention. Therefore, for example, a pressure-sensitive adhesive composition is applied on one surface of the electromagnetic wave reflection sheet 3 before or after being incorporated into the electromagnetic wave absorbing laminated structure 10 to form a coating layer, and the layer is cured by active energy rays. The bubble-containing pressure-sensitive adhesive layer 5 can be formed by a method (direct copying method). In addition, after the pressure-sensitive adhesive composition is applied and cured in the same manner as described above on a suitable support such as a release film (separator) to form the bubble-containing pressure-sensitive adhesive layer 5, the bubble-containing pressure-sensitive adhesive layer 5 is reflected by electromagnetic waves. Examples thereof include a method of transferring onto the sheet 3 (transfer method).

  Although it does not restrict | limit especially as the thickness of the said bubble containing adhesive layer 5, 50-5000 micrometers is preferable, 400-2000 micrometers is more preferable, More preferably, it is 800-1200 micrometers. When the thickness is less than 50 μm, the cushioning property may be lowered, and the adhesiveness of the pressure-sensitive adhesive sheet to the step (unevenness) may be lowered. When the thickness is larger than 5000 μm, the pressure-sensitive adhesive layer having a uniform thickness and / or It tends to be difficult to obtain a pressure-sensitive adhesive sheet having a uniform thickness.

  In the pressure-sensitive adhesive sheet of the present invention, a release film (separator) may be used to protect the surface (pressure-sensitive adhesive surface) of the bubble-containing pressure-sensitive adhesive layer 5 until use. The separator is peeled off when the pressure-sensitive adhesive surface protected by the separator is used (that is, when a pressure-sensitive adhesive sheet is affixed to the surface of an adherend to be an electromagnetic wave reflecting surface).

  A conventional release paper or the like can be used as the separator. Specifically, as the separator, for example, in addition to those having a release treatment layer with a release treatment agent on at least one surface of the separator base material, fluorine-based polymers (for example, polytetrafluoroethylene, polychlorotrifluoroethylene, polyfluoride) Low-adhesive substrates made of vinyl fluoride, polyvinylidene fluoride, tetrafluoroethylene-hexafluoropropylene copolymer, chlorofluoroethylene-vinylidene fluoride copolymer, etc., and nonpolar polymers (for example, polyethylene, polypropylene, etc.) A low-adhesive base material made of an olefin resin or the like can be used.

  As the separator, for example, a separator in which a release treatment layer is formed on at least one surface of the separator substrate can be suitably used. Examples of the separator substrate include polyester films (polyethylene terephthalate film, etc.), olefin resin films (polyethylene film, polypropylene film, etc.), polyvinyl chloride films, polyimide films, polyamide films (nylon film), rayon films, etc. In addition to plastic base film (synthetic resin film) and papers (quality paper, Japanese paper, kraft paper, glassine paper, synthetic paper, top coat paper, etc.), these are laminated by lamination or coextrusion (2-3 layer composite) and the like. The release treatment agent constituting the release treatment layer is not particularly limited, and for example, a silicone release treatment agent, a fluorine release treatment agent, a long-chain alkyl release treatment agent, or the like can be used. The release treatment agents can be used alone or in combination of two or more.

The pressure-sensitive adhesive sheet of the present invention can be attached to a metal (for example, SUS304), concrete, a slate plate, etc. in a normal state (23 ° C., 50% RH). Specifically, being able to be attached in a normal state means that, for example, the shear adhesive strength to a flat surface such as metal, concrete, and slate plate of the pressure-sensitive adhesive sheet is 0.5 N / mm ² or more under the conditions of 23 ° C. and 50% RH ( It means that the peeling speed is 100 mm / min). In the pressure-sensitive adhesive sheet of the present invention, the bubble-containing pressure-sensitive adhesive layer follows the curved surface portion and the uneven portion, and is adhered to the surface including the curved surface portion and the uneven portion with sufficient adhesive force (peeling force). The Therefore, for example, as can be seen from the unevenness follow-up test described later, the same adhesive force (peeling force) as described above can be achieved even on the surface including the uneven portion under the conditions of 23 ° C. and 50% RH. it can. “Unevenness following” means that even if there are uneven parts on the surface of the adherend, the pressure-sensitive adhesive layer of the adhesive sheet to be applied is deformed according to the shape of the unevenness, and bubbles and floats are not generated in the stepped parts. Say.

  Further, the pressure-sensitive adhesive sheet of the present invention has a protective layer formed on the outermost surface, and as is clear from the test examples described later, has an extremely high weather resistance and moisture resistance, and is left outdoors for a long time. However, discoloration or the like does not occur, and the above sufficiently high adhesive force can be maintained. Further, since the entire pressure-sensitive adhesive sheet has excellent weather resistance and high temperature and high humidity resistance, it is possible to obtain stable electromagnetic wave absorption performance for a long period of time.

  EXAMPLES Hereinafter, although an Example and a comparative example are shown and this invention is demonstrated more concretely, this invention is not limited at all by the Example described below.

The physical properties and characteristics of the pressure-sensitive adhesive sheets prepared in Examples and Comparative Examples described later were evaluated by the following methods.
(1) Electromagnetic wave absorption performance (initial)
The absorption performance of 5.8 GHz was evaluated by the time domain method in a six-sided anechoic chamber. The case where the amount of absorption was 20 dB or more was judged as good (◯), and the case where it was less than 20 dB was judged as defective (x).

(2) Shear adhesive strength A double-sided pressure-sensitive adhesive sheet (bubble-containing pressure-sensitive adhesive layer) was attached to an aluminum plate having a thickness of 0.4 mm and backed. This backed adhesive sheet is cut to a width of 20 mm, and is squeezed by reciprocating once with a 2 kg roller on a slate plate (slate board according to JIS A 5430: lithographic plate) under conditions of 23 ° C. and 50% RH, Shear adhesive strength (N / mm ² ) at the initial stage (30 minutes after pasting) and 2000 hours after pasting was measured at a peeling rate of 100 mm / min. The pressure-bonding area between the pressure-sensitive adhesive sheet and the adherend was 500 mm ² (20 mm × 25 mm).

(3) Concavity and convexity followability As shown in FIG. 2 (A), four 10 mm wide PET plates 15 (thickness: 12 μm) are aligned and fixed on a transparent acrylic plate 14 at an interval of 5 mm width, and adhesive is adhered thereon. The sheet 16 (30 mm × 70 mm) was bonded by reciprocating a 5 kg (width 50 mm) roller so that the adhesive surface was in contact. Immediately after bonding, the adhesive state of the adhesive sheet 16 was observed from the back side (acrylic plate side) with an optical microscope. FIG. 2 (B) is a diagram of the state observed from the back side. In the edge part of the acrylic plate PET plate, the width (average value of eight locations) of the portion 18 where the adhesive sheet and the acrylic plate are not in contact is measured. When the thickness is 0.1 mm or less, the step absorbability is good (◯), and when it exceeds 0.1 mm, the step absorbability is poor (x).

  In addition, the code | symbol 17 in FIG. 2 (B) shows the part which the adhesive sheet and the acrylic board have contact | adhered, and the code | symbol 19 has shown the width | variety (measurement object) of the part which the adhesive sheet and the acrylic board have not contact | adhered. .

(4) Weather resistance Adhesive sheet (20mm x 50mm) is affixed to the corner of SUS304 bent to a radius of curvature of 500mm, and exposed outdoors according to JIS K 7350-4 (Nitto, Toyohashi, Aichi Prefecture) A sample treated at Denko Co., Ltd. outdoor exposure field, 2000 hours) was prepared. And about this sample, adhesiveness, discoloration, and electromagnetic wave absorptivity were evaluated as follows.

(Adhesiveness)
The above samples were visually observed to observe the presence or absence of floating / peeling. If there was no lifting / peeling, the weather resistance was good (◯), and if there was lifting / peeling, the weather resistance was poor (×).

(discoloration)
The above samples were visually observed to observe the presence or absence of discoloration. If there was no discoloration, the weather resistance was good (◯), and if there was discoloration, the weather resistance was poor (x).

(Electromagnetic wave absorption)
The absorption performance of 5.8 GHz was evaluated by the time domain method in a six-sided anechoic chamber. When the radio wave absorption performance was lower than before outdoor exposure (electromagnetic wave absorption performance (initial)), it was judged as bad (X), and when it did not drop, it was judged as good (◯).

(5) High temperature and high humidity resistance An adhesive sheet (20 mm x 50 mm) is attached to a corner portion of a SUS304 plate bent to a curvature radius of 500 mm and left in an indoor environment at 85 ° C and 85% RH for 2000 hours. A sample was made. About this sample, adhesiveness, discoloration, and electromagnetic wave absorptivity were evaluated as follows.

(Adhesiveness)
The above samples were visually observed to observe the presence or absence of floating / peeling. If there was no lifting / peeling, it was evaluated as high-temperature and high-humidity resistance (◯), and if there was floating / peeling, it was evaluated as high-temperature high-humidity resistance (×).

(discoloration)
The above samples were visually observed to observe the presence or absence of discoloration. If there was no discoloration, the high temperature and high humidity resistance was good (◯), and if there was discoloration, the high temperature and high humidity resistance was poor (x).

(Electromagnetic wave absorption)
The absorption performance of 5.8 GHz was evaluated by the time domain method in a six-sided anechoic chamber. When the radio wave absorption performance was lower than before standing under high temperature and high humidity (electromagnetic wave absorption performance (initial)), it was judged as bad (X), and when it was not lowered, it was judged as good (◯).

(6) Gel fraction The gel fraction was measured by the following method immediately after crosslinking treatment and after storage for 1 week at room temperature (23 ° C).
The pressure-sensitive adhesive layer is peeled off from the release liner at a size of 5 cm × 5 cm, wrapped in a porous polytetrafluoroethylene sheet having a pore diameter of 0.2 μm (trade name “NTF1122” manufactured by Nitto Denko Corporation), and then bound with a kite string. Then, the weight at that time is measured, and this weight is defined as the weight before immersion. The weight before immersion is the total weight of the pressure-sensitive adhesive layer, the polytetrafluoroethylene sheet, and the kite string. Moreover, the weight of a polytetrafluoroethylene sheet and a kite string is also measured, and let this weight be a wrapping weight.

  Next, the pressure-sensitive adhesive layer wrapped with a polytetrafluoroethylene sheet and tied with a kite string is placed in a 50 ml container filled with ethyl acetate and left at room temperature for 1 week (7 days). Thereafter, the tetrafluoroethylene sheet is taken out from the container, transferred to an aluminum cup, dried in a dryer at 130 ° C. for 2 hours to remove ethyl acetate, the sample weight is measured, and the weight is immersed in the weight. And Then, the gel fraction is calculated from the following formula.

Gel fraction (% by weight) = (A−B) / (C−B) × 100
(In the formula, A is the weight after immersion, B is the weight of the bag, and C is the weight before immersion.)

[Examples 1 to 5 and Comparative Examples 1 and 2]
1. Bubble-containing adhesive layer (1) Bubble-containing adhesive layer A
As a monomer component, in a monomer mixture in which 90 parts by weight of 2-ethylhexyl acrylate and 10 parts by weight of acrylic acid are mixed, 0.05 part by weight of a photopolymerization initiator [trade name “Irgacure 651” (manufactured by Ciba Japan)] After blending 0.05 part by weight of a photopolymerization initiator [trade name “Irgacure 184” (manufactured by Ciba Japan)], the viscosity (BH viscometer, No. 5 rotor, 10 rpm, measurement temperature: 30 ° C.) is about Ultraviolet rays were irradiated to 15 Pa · s to prepare a partially polymerized composition (partial polymerization, syrup).

  To 100 parts by weight of this syrup, 0.04 part by weight of a photopolymerization initiator [trade name “Irgacure 651” (manufactured by Ciba Japan)] and 0.08 part by weight of 1,6-hexanediol diacrylate (HDDA) After the addition, a hollow glass balloon (average particle size of 40 μm, trade name “Fuji Balloon H-40” (manufactured by Fuji Silysia Chemical Co., Ltd.)) was further added to 12.5 wt. It added in the ratio which becomes a part. Contains 33% by volume of bubbles per entire partially polymerized monomer syrup.

  Adhesive containing hollow glass balloon by adding 0.7 part by weight of fluorosurfactant (trade name “Surflon S-393”) (manufactured by AGC Sey Chemical Co.) to partially polymerized monomer syrup after addition of hollow glass balloon Sex composition was obtained. Thereafter, a stator having a large number of fine teeth on a disk having a through-hole in the center, and a rotor facing the stator with the teeth and having fine teeth on the disk similar to the stator were provided. Nitrogen was introduced into the adhesive composition using an apparatus to mix the bubbles. In addition, the bubble was 20 volume% with respect to the whole volume of an adhesive composition. Moreover, the content rate of the hollow glass balloon at this time was 29 volume%.

  The pressure-sensitive adhesive composition containing bubbles was applied to the release surface of the separator. As the separator, a polyethylene terephthalate base material (trade name “MRN” manufactured by Mitsubishi Polyester Film Co., Ltd.) on which one side was peeled off was used.

The pressure-sensitive adhesive composition applied to the separator was irradiated for 3 minutes from both sides using ultraviolet rays with an illuminance of 5 mW / cm ² (“Black Light” manufactured by Toshiba Corporation) to cure the pressure-sensitive adhesive composition, A bubble-containing pressure-sensitive adhesive layer having a thickness of 800 μm was obtained. At this time, a photopolymerization initiator (trade name “Irgacure 651” (manufactured by Ciba Specialty Chemicals) 0.04 part by weight) was added. In addition, as other additive components, an antioxidant (trade name “Irganox 1010” manufactured by Ciba Specialty Chemicals Co., Ltd., 0.5 part by weight), a pigment (trade name “ATDN101” (Daiichi Seika Kogyo Co., Ltd.) 0.02 parts by weight) and a pigment dispersion solvent (0.18 parts by weight of 2-ethylhexyl acrylate) were added.

(2) Bubble-containing pressure-sensitive adhesive layers B and C
A 400-μm thick bubble-containing pressure-sensitive adhesive layer B and a 1200-μm thick bubble-containing pressure-sensitive adhesive layer C were formed in the same manner as described above, except that the amount of the pressure-sensitive adhesive composition applied to the separator was changed.

2. Adhesive layer A monomer mixture in which 90 parts by weight of isononyl acrylate and 10 parts by weight of acrylic acid were mixed as a monomer component, a photopolymerization initiator [trade name “Irgacure 184” (manufactured by Ciba Japan)] 0.1 weight After blending the parts, the composition was partially polymerized by irradiation with ultraviolet rays until the viscosity (BH viscometer, No. 5 rotor, 10 rpm, measurement temperature: 30 ° C.) reached about 15 Pa · s, and partially polymerized. Syrup).

  0.2 parts by weight of trimethylolpropane triacrylate (TMPTA) is added as a crosslinking agent to 100 parts by weight of this syrup, and an anti-aging agent [trade name “Irganox 1010” (manufactured by Ciba Specialty Chemicals)] 1 Part by weight was added and then stirred to obtain a pressure-sensitive adhesive composition.

  On the polyethylene terephthalate film (release liner A1, thickness 50 μm) on which the silicone release agent surface is formed, the acrylic adhesive prepared above is applied to a thickness of 50 μm, and a polyester cover separator (Product name “MRN” (Mitsubishi Polyester Film Co., Ltd.), thickness 38 μm) is laminated, and UV light of about 2000 mJ is irradiated from the release liner side with a UV lamp in a state where the surface of the compound is cut off from the air layer. By reacting the blend, an adhesive layer (thickness 50 μm) was obtained. The gel fraction of the pressure-sensitive adhesive layer was 85%.

3. Divided conductive film 300 mm wide x 300 mm long x 25 μm thick polyimide film on one side, planar shape is 4.5 mm long × 4.5 mm wide square and 35 μm thick conductive film part (Cu film part) is a square matrix A divided conductive film arranged in a gap between the conductive film portions (1.7 mm) was prepared.

4). Electromagnetic wave absorbing sheet (1) Electromagnetic wave absorbing sheet A
In a bead mill, 100 parts by weight of graphite (average particle size: 5 μm), 700 parts by weight of propylene glycol monomethyl ether (PGM) and 1 part by weight of Prisurf A212 (Daiichi Kogyo Seiyaku, phosphate ester dispersant) were dispersed. . Thereafter, 200 parts by weight of a polymethyl methacrylate (PMMA) solution (PMMA: toluene = 20: 80 (weight ratio)) was added to 300 parts by weight of the obtained dispersion and mixed to prepare a coating solution. Next, this coating solution was applied to a PET separator and dried to obtain a graphite-containing PMMA sheet (thickness: 20 μm). A plurality of the graphite-containing PMMA sheets were laminated, and vacuum heat pressing (110 ° C., 10 minutes) was performed using a spacer whose gap was set to 1.5 mm to produce an electromagnetic wave absorbing sheet A having a thickness of 1.6 mm. .

(2) Electromagnetic wave absorbing sheet B
Using a biaxial kneading extruder, graphite and LDPE were extruded to produce pellets (graphite: LDPE = 40: 60 (weight ratio)). The pellets were formed into a sheet (thickness: 0.3 mm) using an extruder. Then, a plurality of graphite-containing LDPE sheets are laminated, and a vacuum heat press (120 ° C., 1 minute) is performed using a spacer whose gap is set to 1.5 mm to obtain an electromagnetic wave absorbing sheet B having a thickness of 1.5 mm. Produced.

(3) Electromagnetic wave absorbing sheet C
Graphite and EPDM were kneaded with a pressure kneader. This kneaded product (graphite: EPDM = 100: 100 (weight ratio)) is vacuum hot pressed (80 ° C., 1 minute) using a spacer with a gap set to 1 mm, and an electromagnetic wave absorbing sheet having a thickness of 1.2 mm C was produced.

5). Electromagnetic wave reflection sheet An aluminum foil having a thickness of 25 μm was prepared.

6). Protective Layer A polyvinylidene fluoride (PVdF) film having a thickness of 100 μm (PVdF film with acrylic adhesive (Duratac PF100 (trade name) manufactured by Nitto Denko Corporation)) was prepared.

Example 1
The material of each layer is cut according to the planar size (width 300 mm x length 300 mm) of the divided conductive film, and the protective layer / divided conductive film / adhesive layer / electromagnetic wave absorbing sheet A (PMMA + graphite) / adhesive layer / electromagnetic wave reflection The sheet / bubble-containing pressure-sensitive adhesive layer A was bonded together in this order to produce an electromagnetic wave absorbing pressure-sensitive adhesive sheet.

(Example 2)
An electromagnetic wave absorbing pressure-sensitive adhesive sheet was prepared in the same manner as in Example 1 except that the bubble-containing pressure-sensitive adhesive layer A (thickness 800 μm) was changed to the bubble-containing pressure-sensitive adhesive layer B (thickness 400 μm).

(Example 3)
An electromagnetic wave absorbing pressure-sensitive adhesive sheet was produced in the same manner as in Example 1 except that the bubble-containing pressure-sensitive adhesive layer A (thickness 800 μm) was changed to the bubble-containing pressure-sensitive adhesive layer C (thickness 1200 μm).

Example 4
An electromagnetic wave absorbing pressure-sensitive adhesive sheet was prepared in the same manner as in Example 1 except that the electromagnetic wave absorbing sheet A (PMMA + graphite) was changed to the electromagnetic wave absorbing sheet B (graphite + LDPE).

(Example 5)
An electromagnetic wave absorbing pressure-sensitive adhesive sheet was prepared in the same manner as in Example 1 except that the electromagnetic wave absorbing sheet A (PMMA + graphite) was changed to the electromagnetic wave absorbing sheet C (graphite + EPDM).

(Comparative Example 1)
An electromagnetic wave absorbing pressure-sensitive adhesive sheet was produced in the same manner as in Example 1 except that the protective layer was not used.

(Comparative Example 2)
Instead of the bubble-containing pressure-sensitive adhesive layer A, an electromagnetic wave absorbing pressure-sensitive adhesive sheet was produced in the same manner as in Example 1 except that the double-sided adhesive tape A described below was used.
"Double-sided adhesive tape A"
5 parts by weight of acrylic acid, 95 parts by weight of butyl acrylate, and 200 parts by weight of toluene as a polymerization solvent were put into a three-necked flask and stirred for 2 hours while introducing nitrogen gas. After removing oxygen in the polymerization system in this way, 0.1 part by weight of benzoyl peroxide was added, the temperature was raised to 80 ° C., and a polymerization reaction was carried out for 6 hours. The weight average molecular weight of the obtained polymer was 400,000. 2 parts by weight of an isocyanate-based crosslinking agent (trade name: Coronate L, manufactured by Nippon Polyurethane Industry Co., Ltd.) is blended as a crosslinking agent with respect to 100 parts by weight of the solid content of this polymer, and the acrylic pressure-sensitive adhesive is stirred sufficiently. Prepared. As the nonwoven fabric base material, the above acrylic pressure-sensitive adhesive has the same weight on both sides of a nonwoven fabric having a thickness of 75 μm and a density of 0.31 g / cm ³ in which 99% by weight of Manila hemp is mixed with 1% by weight of vinylon. And then dried to form an adhesive layer, and a double-sided adhesive tape having a total thickness of 160 μm was produced.

  The evaluation results of Examples and Comparative Examples are shown in Table 1.

  From Table 1, the pressure-sensitive adhesive sheet of the present invention can be stably adhered to the surface including the curved surface portion and the uneven portion, and a strong and stable adhesive state can be obtained simply by pressure bonding to an outdoor building or a concrete structure. In addition, it can be seen that an electromagnetic wave absorbing pressure-sensitive adhesive sheet that can be stably maintained even when exposed to the outdoors or in a high temperature and high humidity environment for a long time can be realized.

DESCRIPTION OF SYMBOLS 1 Divided conductive film 2 Electromagnetic wave absorption sheet 3 Electromagnetic wave reflection sheet 4 Protective layer 5 Bubble-containing adhesive layer 6 Adhesive layer 7 Adhering object 10 Laminated structure part for electromagnetic wave absorption 100 Adhesive sheet for electromagnetic wave absorption

Claims (5)

  The divided conductive film, the electromagnetic wave absorbing sheet and the electromagnetic wave reflecting sheet have an electromagnetic wave absorbing laminated structure layered in this order, and a protective layer is formed on one side opposite to the electromagnetic wave absorbing sheet side of the divided conductive film, An electromagnetic wave absorbing pressure-sensitive adhesive sheet, wherein a bubble-containing pressure-sensitive adhesive layer is formed on one side of the electromagnetic wave reflecting sheet opposite to the electromagnetic wave absorbing sheet side.   The laminated structure part for electromagnetic wave absorption has bonded the divided conductive film to one side of the electromagnetic wave absorbing sheet via an adhesive layer, and bonded the electromagnetic wave reflection sheet to the other side of the electromagnetic wave absorbing sheet via an adhesive layer. The electromagnetic wave-absorbing pressure-sensitive adhesive sheet according to claim 1, which is a product.   The electromagnetic wave absorbing pressure-sensitive adhesive sheet according to claim 2, wherein the pressure-sensitive adhesive layer is formed of an acrylic pressure-sensitive adhesive having a gel fraction of 70 to 90%.   The pressure-sensitive adhesive sheet for electromagnetic wave absorption according to any one of claims 1 to 3, wherein the bubble-containing pressure-sensitive adhesive layer contains 5 to 50% by volume of bubbles. The pressure-sensitive adhesive sheet for absorbing electromagnetic waves according to claim 4, wherein the bubble-containing pressure-sensitive adhesive layer contains 5 to 50% by volume of hollow microspheres having a specific gravity of 0.1 to 0.8 g / cm ³ .

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