JP2012204731A - Electromagnetic wave shield sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electromagnetic wave shield sheet capable of reducing a force required when a protective sheet is exfoliated, preventing exfoliation of a mesh pattern when the protective film is exfoliated, and preventing exfoliation of the protective film during transportation or storage.SOLUTION: An electromagnetic wave shield sheet comprises an electromagnetic wave shield member, and a protective film provided on a surface of the electromagnetic wave shield member so as to be exfoliated. The electromagnetic wave shield member comprises a transparent substrate, and a conductive pattern layer formed by a filament pattern provided on the transparent substrate. The protective film comprises a substrate, and an adhesive layer provided on the substrate. The filament of the conductive pattern layer projects on both side ends of a peak part, and is indented at a center of the peak part. Projection portions on both side ends of the filament peak part are embedded in the adhesive layer of the protective film. The conductive pattern layer is in tight contact with the adhesive layer, so as to form a gap between a bottom of an indentation at the center of the peak part and the adhesive layer.

Description

  The present invention relates to an electromagnetic wave shielding sheet provided with a protective film, and more specifically, in an electromagnetic wave shielding member attached to the front surface of a plasma display panel or the like, the protective film is peelable on the surface of the conductive layer of the electromagnetic wave shielding member. It relates to the electromagnetic shielding sheet provided.

  In recent years, with the increase in size and thickness of image display devices, plasma displays (hereinafter sometimes abbreviated as PDP) have attracted attention. Since PDP uses plasma discharge for light emission, unnecessary electromagnetic waves in the 30 MHz to 1 GHz band may leak to the outside and affect other devices (for example, remote control devices, information processing devices, etc.). Therefore, it is common to provide a film-like electromagnetic shielding member on the front side (observer side) of the plasma display panel that can shield (shield) only electromagnetic waves that leak while maintaining the transparency of image light. Is.

  The above electromagnetic shielding member is made by etching copper foil into a mesh shape by photolithography method, screen printing electroless plating catalyst paste on a transparent substrate with mesh pattern, and electroless metal layer on it Plating or (Patent Document 1), intaglio printing of a conductive ink composition directly on a transparent substrate with a mesh pattern, and electroplating a metal layer on the mesh pattern on the transparent substrate (Patent Document 2), etc. It has been known.

  Since the electromagnetic shielding member having the structure as described above has a fine surface and is easily damaged, it is usually protected to protect the electromagnetic shielding member surface from the time it is manufactured until it is used (that is, when manufacturing an image display device or the like). The protective film is peeled off when the electromagnetic wave shielding member is incorporated into an image display device or the like while being transported or stored in a state of being covered with a film or the like. The protective film is usually peeled manually or mechanically in a continuous assembly line of the image display device.

  In recent years, the area of image display devices has been increased, and accordingly, the electromagnetic shielding member has also been increased in size (increased in area). When the electromagnetic wave shielding member is enlarged, the force required for peeling off the protective sheet also increases, which has been a work burden when peeling manually. If the adhesion between the electromagnetic shielding member and the protective sheet is weakened, the protective sheet can be easily peeled off. However, as described above, the surface of the electromagnetic shielding member has mesh pattern irregularities. If weakened, the protective film may be peeled off while the electromagnetic wave shielding member is being transported or stored.

  In addition, when a protective film with high adhesion to the surface of the electromagnetic wave shielding member is used, the above problem does not occur, but part of the convex mesh pattern peels off together with the protective film when the protective film is peeled off. There was a case. In particular, in the case of a form having a fine unevenness or fine particle-like blackened layer on the surface of the mesh pattern, the above-described problems are likely to occur.

JP 2001-102792 A Japanese Patent Laid-Open No. 11-174174

  The present inventors peeled off the protective sheet by forming the metal layer on the surface of the mesh pattern of the electromagnetic wave shielding member into a specific shape and making the electromagnetic wave shielding member having such a mesh pattern covered with a protective film. It has been found that the force required for carrying out the process can be reduced, and also when the protective film is peeled off, the mesh pattern is not peeled off and the protective film is not peeled off during transportation or storage. The present invention is based on this finding.

  Therefore, the object of the present invention is to reduce the force required to peel off the protective sheet, and also to peel off the protective film during transportation and storage without peeling off the mesh pattern even when the protective film is peeled off. There is no electromagnetic wave shielding sheet.

An electromagnetic wave shielding sheet according to the present invention is an electromagnetic wave shielding sheet provided with an electromagnetic wave shielding member and a protective film provided on the surface of the electromagnetic wave shielding member so as to be peelable,
The electromagnetic wave shielding member includes a transparent base material, and a conductive pattern layer formed with a wire rod pattern provided on the transparent base material,
The protective film includes a base material and an adhesive layer provided on the base material,
The wire pattern of the conductive pattern layer protrudes at both ends at the top and is recessed at the center of the top, and the protrusions at both ends of the line cover at the both ends are buried in the adhesive layer of the protective film. The conductive pattern layer and the adhesive layer are in close contact so that a gap is formed between the bottom of the adhesive layer and the adhesive layer.

  Moreover, in the aspect of this invention, it is preferable that the metal layer is formed in the surface of the said electroconductive pattern layer.

  Moreover, in the aspect of this invention, it is preferable that the surface of the said metal layer is coat | covered with the blackening layer which consists of acicular metal.

  Moreover, in the aspect of this invention, it is preferable that the said electroconductive pattern layer consists of an electroconductive composition containing electroconductive particle and a resin binder.

  Moreover, in the aspect of this invention, it is preferable that a primer layer is provided between the said transparent base material and the said electroconductive pattern layer.

  Moreover, in the aspect of this invention, it is preferable that the said adhesion layer consists of an acrylic adhesive.

  Furthermore, in the aspect of the present invention, it is preferable that a streak-like concave groove is formed on the surface of the metal layer in the concave portion of the wire rod.

  In the electromagnetic wave shielding sheet according to the present invention, in the adhesive layer of the protective film, the protruding portions at both ends of the line ridge top portion of the conductive pattern layer of the electromagnetic wave shielding sheet are buried, but there is a gap between the bottom of the concave portion of the top portion and the adhesive layer. Since the electromagnetic wave shielding member and the protective film are in close contact with each other, the protective sheet can be peeled off without requiring force even when the electromagnetic wave shielding member is used. Even when peeled off, the conductive pattern layer is not peeled off, and the protective film is not peeled off during transportation or storage.

It is a schematic diagram of the cross section (main cut surface) orthogonal to the running direction (longitudinal direction) of the wire rod pattern of the electromagnetic wave shielding member used in this invention. It is a schematic diagram of the cross section (main cut surface) orthogonal to the running direction (longitudinal direction) of a wire rod pattern in the state which made the electromagnetic wave shielding member and the protective film contact | adhere. It is a scanning electron micrograph of the wire rod pattern of the electroconductive shield member produced in the Example. FIG. 3 (a) is a photograph of the wire wrinkle pattern observed from above, FIG. 3 (b) is an enlarged photograph of the wire wrinkle of (a), and FIG. 3 (c) is a photograph of FIG. 3 (b). It is a further enlarged photograph. It is a schematic schematic diagram of the cross section (main cut surface) orthogonal to the running direction (longitudinal direction) of the wire rod pattern of the electromagnetic wave shielding sheet obtained in Comparative Example 1.

  The electromagnetic wave shielding sheet by this invention is equipped with the electromagnetic wave shielding member and the protective film provided in the surface of the said electromagnetic wave shielding member so that peeling was possible. In the specification of the present application, “electromagnetic wave” means one having a frequency of kHz to GHz centering on a wave number band in a range of 30 MHz to 1 GHz in a broad sense, visible light, ultraviolet light, infrared light, etc. The electromagnetic waves in other frequency bands are referred to as visible light, ultraviolet light, infrared light, and the like. Hereinafter, an electromagnetic wave shielding member and a protective film constituting an electromagnetic wave shielding sheet according to the present invention will be described with reference to the drawings. In addition, in order to make an understanding of an invention easy, the schematic schematic diagram of FIG.1, FIG.2 and FIG.4 changed the vertical-horizontal scale and the dimensional ratio of each member suitably, or showed it exaggerating. Is.

<Electromagnetic wave shielding member>
FIG. 1 is a schematic diagram of a cross section (hereinafter also referred to as a main cut surface) perpendicular to the traveling direction (longitudinal direction) of the wire rod pattern of the electromagnetic wave shielding member 1 used in the present invention. In the electromagnetic wave shielding member 1, the conductive pattern layer 14 is formed on one surface of the transparent substrate 11 with a wire rod pattern. In the case where the conductive pattern layer 14 is formed from a conductive composition containing conductive particles and a resin binder as will be described later, in order to improve the adhesion between the transparent substrate and the conductive pattern layer, A primer layer 13 may be provided between the material and the conductive pattern layer. In order to further improve the conductivity of the conductive pattern layer 14, a metal layer 15 may be provided on the surface of the conductive pattern layer. Furthermore, the electromagnetic wave shielding member 1 used in the present invention is used by being attached to the front surface of a display device such as a PDP. For the purpose of reducing so-called external light reflection, the surface of the metal layer 15 is used. May be covered with the blackening layer 16. Hereinafter, each member which comprises an electromagnetic wave shield member is demonstrated.

<Transparent substrate>
The transparent substrate 11 may be appropriately selected from known materials and thicknesses in consideration of required physical properties such as transparency in the visible region (light transmittance), heat resistance, and mechanical strength, such as glass and ceramics. A plate-like rigid body such as a transparent inorganic plate or a resin plate may be used. However, a flexible resin film (or sheet) is preferable in consideration of suitability for continuous processing with a roll-to-roll having excellent productivity. The roll-to-roll refers to a processing method in which the material is unwound and supplied from a winding (roll), appropriately processed, and then wound and stored in the winding.

  Examples of the transparent inorganic material include soda glass, potassium glass, borosilicate glass, lead glass, and other transparent ceramics such as PLZT, quartz, and the like. Moreover, as resin of a resin film or a resin board, for example, polyethylene terephthalate, polyethylene naphthalate, ethylene glycol-1,4 cyclohexanedimethanol-terephthalic acid copolymer, ethylene glycol-terephthalic acid-isophthalic acid copolymer, etc. Examples thereof include polyester resins, acrylic resins such as polymethyl methacrylate, polyolefin resins such as polypropylene and cycloolefin polymers, cellulose resins such as triacetyl cellulose, and polycarbonate resins. Among these, a biaxially stretched film of polyethylene terephthalate is a preferable transparent substrate from the viewpoint of heat resistance, mechanical strength, light transmittance, cost, and the like.

  The thickness of the transparent substrate 11 is basically not particularly limited and is appropriately selected depending on the application. When a flexible resin film is used, it is, for example, about 12 to 500 μm, preferably about 25 to 200 μm. In the case of using a resin or transparent inorganic plate, the thickness is, for example, about 500 to 5000 μm.

  When using a resin film or resin plate as a transparent substrate, known additives such as ultraviolet absorbers, colorants, fillers, plasticizers and antistatic agents are added to the resin as needed. May be. The transparent base material may be obtained by performing known easy adhesion treatment such as corona discharge treatment, primer treatment, and ground treatment on the surface.

<Primer layer>
When the conductive pattern layer 14 is formed by printing a conductive composition containing conductive particles and a resin binder, which will be described later, on the surface of a transparent substrate to form a pattern of wrinkles, the printed material (transparent) In order to improve the transferability of the ink (conductive composition) to the substrate) and to improve the adhesion between the transferred conductive composition and the printed material, a primer layer 13 is provided on the transparent substrate 11. It is preferable. In addition to improving adhesion to both the transparent substrate 11 and the conductive pattern layer 12, it is also a transparent layer for ensuring light transmittance of the opening (conductive pattern layer non-formed portion) of the conductive pattern layer 14. .

  The material constituting the primer layer 13 is not particularly limited, but an ionizing radiation curable composition containing a liquid (fluid) ionizing radiation polymerizable compound in an uncured state is coated on a transparent substrate. A material that hardens (solidifies) after being worked is preferably used. As the ionizing radiation polymerizable compound, monomers and / or prepolymers that are polymerized and cured by a reaction such as crosslinking with ionizing radiation are used.

  Examples of such monomers include radically polymerizable monomers such as methyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate, isobornyl (meth) acrylate, and dicyclohexane. Monofunctional (meth) acrylates such as pentenyl (meth) acrylate, dipropylene glycol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, trimethylolpropane tri ( (Meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (me ) Acrylate include various (meth) acrylates such as multifunctional (meth) acrylates such as. In addition, the description with (meth) acrylate means an acrylate or a methacrylate. Examples of the cationic polymerizable monomer include alicyclic epoxides such as 3,4-epoxycyclohexenylmethyl-3 ′, 4′-epoxycyclohexene carboxylate, glycidyl ethers such as bisphenol A diglycidyl ether, 4-hydroxybutyl vinyl ether And vinyl ethers, and oxetanes such as 3-ethyl-3-hydroxymethyloxetane.

  Examples of the prepolymer (also referred to as oligomer) include radically polymerizable prepolymers such as urethane (meth) acrylate, epoxy (meth) acrylate, polyester (meth) acrylate, and triazine (meth) acrylate. Examples include prepolymers, polythiol-based prepolymers such as trimethylolpropane trithioglycolate, pentaerythritol tetrathioglycolate, and unsaturated polyester prepolymers. Other examples of the cationic polymerizable prepolymer include novolac type epoxy resin prepolymer and aromatic vinyl ether type resin prepolymer.

  These monomers or prepolymers may be used alone or in combination of two or more monomers, two or more prepolymers, or one or more monomers depending on the required performance, application suitability, etc. And one or more prepolymers may be mixed and used.

  Typical examples of the ionizing radiation for curing the monomer or the prepolymer include ultraviolet rays and electron beams. Besides these, various electromagnetic waves such as visible rays, X-rays, γ rays, and α rays. A charged particle beam such as an ion beam can also be used. When ultraviolet rays or visible rays are employed as the ionizing radiation, a photopolymerization initiator is generally used in combination. As a photopolymerization initiator, in the case of a radical polymerizable monomer or prepolymer, a compound such as a benzophenone-based, thioxanthone-based, benzoin-based, or acetophenone-based compound, or in the case of a cationic polymerization-based monomer or prepolymer, Metallocene, aromatic sulfonium and aromatic iodonium compounds are used. The addition amount of these photoinitiators is about 0.1-5 mass parts with respect to 100 mass parts of compositions which consist of a monomer and / or a prepolymer.

  The ionizing radiation curable composition may contain a solvent, but in this case, since a drying step is required after coating, it is preferably a type that does not contain a solvent (non-solvent type).

  The thickness of the primer layer 13 is not particularly limited, but is usually formed to be about 1 μm to 100 μm in thickness after curing. Further, the thickness of the primer layer is usually about 1 to 50% of the total value of the conductive pattern layer and the primer layer. As will be described later, depending on the method of forming the conductive pattern layer, the thickness of the primer layer may not be uniform. For example, when the thickness of the primer layer directly below the conductive pattern layer is larger than the thickness of the opening (conductive pattern layer non-formed part), the primer layer thickness means the thickness of the conductor layer non-formed part. It shall be.

<Conductive pattern layer>
The conductive pattern layer 14 of the electromagnetic wave shielding member 1 used in the present invention (when the conductive pattern layer includes a metal layer and / or a blackening layer described later, these layers are collectively referred to as a conductive pattern layer 12. 1) is formed so as to have a pattern of wrinkles as shown in FIG. And this wire rod is formed so that it may have a cross-sectional shape in which the top both ends 17 protrude and the top center 18 is recessed. As the planar shape of this wire rod pattern, a mesh (lattice or mesh) shape is usually mentioned, and the shape of the unit lattice is a triangle such as a regular triangle, a square such as a square, a rectangle, a trapezoid, a pentagon, Although it is a polygon such as a hexagon, in addition to these, the shape in a plan view may be a stripe (a striped pattern or a group of parallel lines), a spiral (a spiral or a spiral), or the like. The conductive pattern layer having such a specific shape can also be formed by a conventionally known method of etching a metal foil. However, in order to pattern a wire rod having a narrower line width, a conductive particle It is preferable to form by a printing technique using a conductive composition containing a resin binder. Hereinafter, the case where an electroconductive pattern layer is formed from the electroconductive composition containing electroconductive particle and a resin binder is demonstrated.

  As the conductive particles constituting the conductive composition, particles of low resistivity metal such as gold, silver, platinum, copper, nickel, tin, and aluminum, or high resistivity metal particles, resin particles, non-metallic inorganic particles, etc. Examples of the particle shape include, but are not limited to, particles coated with a low resistivity metal such as gold or silver, and are spherical, spheroidal, regular polyhedral, truncated polyhedral , Scales, discs, dendrites, fibers, and the like. These materials and shapes may be appropriately mixed and used. Since the size of the conductive particles is arbitrarily selected according to the type, it cannot be specified unconditionally. For example, in the case of polyhedral or spherical silver particles, the average particle size of the particles is about 0.1 to 10 μm. Can be used. In addition, an average particle diameter shall mean the value measured by the particle size distribution meter or TEM (transmission electron microscope) observation.

  The content of the conductive particles in the conductive composition is arbitrarily selected according to the conductivity of the conductive particles and the form of the particles, for example, for 100 parts by mass of the total solid content of the conductive composition, The conductive particles can be contained in an amount of 40 to 99 parts by mass, preferably 80 to 97 parts by mass.

  As the binder resin constituting the conductive composition, any of thermosetting resins, ionizing radiation curable resins, and thermoplastic resins can be used. Examples of the thermosetting resin include resins such as melamine resin, polyester-melamine resin, epoxy-melamine resin, phenol resin, polyimide resin, thermosetting acrylic resin, thermosetting polyurethane resin, and thermosetting polyester resin. be able to. Examples of the ionizing radiation curable resin include the above-described resins as a primer material. In addition, examples of the thermoplastic resin include resins such as a thermoplastic polyester resin, a polyvinyl butyral resin, a thermoplastic acrylic resin, and a thermoplastic polyurethane resin. In addition, when using a thermosetting resin, you may add a curing catalyst as needed. When using an ionizing radiation curable resin, a photopolymerization initiator may be added as necessary.

  Further, as will be described later, in order to obtain fluidity suitable for filling the concave portion of the plate, the binder resin is usually used as a varnish dissolved in a solvent. There is no restriction | limiting in particular in the kind of solvent, The solvent generally used for printing ink can be used. The content of the solvent is usually about 10 to 70% by mass at the time of supply to the plate recess, but is preferably as small as possible within a range where necessary fluidity can be obtained. In addition, when an ionizing radiation curable resin is used, a solvent is not necessarily required because it is inherently fluid.

  In order to improve the fluidity and stability of the conductive composition, as long as it does not adversely affect the conductivity and adhesion with the primer layer, fillers, thickeners, surfactants, antioxidants, dispersion An agent, an anti-settling agent, etc. may be added.

  The conductive pattern layer in the form of a wire rod pattern can be formed by performing intaglio printing on the conductive composition as described above as follows. The intaglio printing method and the resultant product use a specific primer, and are filed by the applicant of the present application as PCT / JP2008 / 060427 and published as International Publication WO08 / 149969. As an example, a conductive composition is filled only in the intaglio depression using a doctor blade, etc., and a transparent substrate with a liquid primer layer formed on one side is pressed in this direction so that the primer layer is in contact with the intaglio The primer layer is brought into contact by pressing with a roller or the like, and the primer layer is solidified from a liquid state to a solid state in a contact state, and then the transparent substrate is separated from the intaglio to release the transparent substrate. The conductive composition can be transferred onto the solidified primer layer on the material and printed.

  As an intaglio used for intaglio printing, using an intaglio plate produced so that the center of the bottom of the plate depression is recessed from the peripheral edge, the conductive composition transferred onto the transparent substrate has the shape of the bottom of the intaglio plate. Is formed, and a conductive pattern layer having a shape in which both side ends of the top portion of the wire ridge protrude and the center of the top portion is recessed can be formed.

  When the conductive composition is still in a liquid state after printing, that is, after release, a conductive pattern layer can be formed by solidifying by appropriately performing a drying operation, a heating operation, a cooling operation, a chemical reaction operation, and the like. it can. For example, a drying operation removes unnecessary volatile components such as a solvent in the conductive composition, and a heating operation promotes a necessary chemical reaction such as drying and thermal curing of the conductive composition, so that a cooling operation is performed. In order to accelerate the solidification of the conductive composition and primer layer of thermoplastic resin that has been heated and melted, the chemical reaction operation may be performed by other means such as ionizing radiation irradiation that does not involve heating. To make progress. Further, the conductive composition may be semi-cured and solidified on the plate and completely cured after the release.

  Moreover, you may perform solidification of an electroconductive composition during an intaglio contact. When the conductive composition is solidified during the plate contact, the intaglio serves as a shaping mold for the conductive composition, and the intaglio including the primer layer is used as a complete shaping mold. At this time, the solidification method of the conductive composition may be the same as the solidification method employed in the primer layer, or may be a different method. However, if the same method such as ionizing radiation irradiation is adopted, the primer layer and the conductive composition can be cured simultaneously on the plate surface, so that the apparatus and process can be simplified, and a similar chemical reaction can be adopted. This is also advantageous in terms of adhesion.

  In the present invention, by printing in this way, even if a depression (dent) is formed on the upper part of the conductive composition filled in the intaglio depression, printing is performed via a liquid and fluid primer layer. During printing, the primer layer can be poured into the recess and brought into close contact, and then the primer layer is solidified, and then the transparent substrate is released from the intaglio plate. Even when the line width of the wire rod is thin, the conductive pattern layer of the pattern can be formed without occurrence of printing failure such as disconnection due to insufficient transfer, shape failure, and insufficient ink adhesion. In the intaglio printing process, the thickness of the primer layer in the portion where the conductive pattern layer is formed as a result of the primer layer flowing in and filling into the depressions formed on the surface of the ink filled in the intaglio recesses It becomes thicker than the thickness of the part (opening) where no is formed. Of course, the conductive pattern layer is formed by a method other than the above-described specific intaglio printing method as long as it is a method capable of obtaining the relationship with the formation of the conductive pattern layer in the specific primer layer thickness. Also good.

<Metal layer>
In the electromagnetic wave shielding member 1 used in the present invention, a metal layer 15 may be provided on the surface of the conductive pattern layer 14 in order to further improve the conductivity of the conductive pattern layer 12. The metal layer 15 is formed by performing electrolytic plating or electroless plating on the surface of the conductive pattern layer 12 described above. From the viewpoint of productivity, suitability for selective plating only on the conductive pattern layer, and the like. Electrolytic plating is preferred. During electroplating, power is supplied to the conductive pattern layer from an electrode such as an energizing roll that is in contact with the surface on which the conductive pattern layer is formed. (For example, 100Ω / □ or less), the electrolytic plating can be performed without any problem.

Examples of the material constituting the metal layer include copper, silver, gold, chromium, nickel and the like, which have high conductivity and can be easily plated. As plating conditions, a bath temperature of 20 to 60 ° C., a current density of 0.001 to 10 A / dm ² , and a plating time of about 1 to 10 minutes are preferable. By increasing the current density, electric power concentration occurs at the corners of the conductive pattern layer 14 (both ends 17 at the top of the line ridge) and the plating easily occurs, and the conductive pattern layer 12 whose surface is metal-plated (that is, The surface of the conductive pattern layer 14) having the metal layer 15 on the surface has a shape in which both side ends 17 of the top of the wire ridge protrude and the top center 18 is recessed. Moreover, the higher the current density, the more the difference in plating layer growth rate between the side end portions 17 and the top center portion 18 of the top of the wire ridge, and the relatively higher current density at both ends (edge portions) 17 of the top of the wire ridge. It becomes easy to become the uneven | corrugated surface shape where the wire rod center 18 was recessed. Therefore, when the metal layer 15 is provided, the main cut surface shape of the conductive pattern layer 14 before the metal layer 15 is provided is rectangular or square, or each end portion of these shapes, in addition to the trapezoid shown in FIG. By making the shape protruded by about 0.5 to 2 μm, the current density at both side ends 17 of the wire ridge top portion can be relatively increased as compared with the top center 18, and as a result, the metal layer 15 is provided on the surface. The surface of the conductive pattern layer 12 may have a shape in which both side ends 17 of the top of the wire ridge protrude and the top center 18 is recessed. The height difference between the side end portions 17 at the top of the wire ridge and the recessed portion 18 at the center of the top is about 1 to 3 μm.

  When the current density is increased during the plating process, a streak-like groove (specifically, as shown in FIG. 3, branching, meandering or both of them is formed on the surface of the metal layer 15 of the concave portion 18 of the wire rod. It becomes easy to produce a ditch groove having a shape. When the groove formed in this way is present on the surface of the conductive pattern layer, the light incident on the groove is reflected many times in a complicated path within the groove, resulting in sunlight, lamp light. It contributes to the improvement of the antireflection of external light.

<Blackening layer>
In the electromagnetic wave shielding member 1 used in the present invention, the blackening layer 16 may be provided on the surface of the conductive pattern layer 14. The blackening layer 16 can be formed by forming a blackening treatment after the metal layer 15 is formed. The blackening treatment can be performed, for example, by subjecting to a roughening treatment by cathodic electrolysis using an electrolytic bath in which copper sulfate pentahydrate and sulfuric acid are dissolved in water. By the blackening treatment, a blackened layer 16 made of a metal needle crystal made of copper is formed on the surface of the conductive pattern layer 12 provided with the metal layer 15.

  In such a roughening treatment (blackening treatment), a metal granular projection is deposited by cathodic electrolysis (first layer), and then metal plating is applied thereon to prevent the projection from falling off. This is performed by forming a metal coating (second layer). Such a surface roughening treatment condition is particularly preferable by increasing the current density of the first layer, since acicular crystals are easily formed.

  The length of the needle-like crystal of the blackened layer thus formed is about 0.1 to 1 μm. The acicular crystal absorbs and scatters many times while the incident light beam is multiple-reflected on the surface between the needles, attenuates a lot of light and greatly reduces the amount of reflected light. As a result, a higher external light antireflection effect can be obtained by the synergistic effect of the incident light attenuation action of both the concave portion formed in the width direction of the wire and the acicular crystal.

<Protective film>
The protective film 2 used in the present invention protects the conductive pattern layer 12 formed in the pattern of wire rods from being damaged after the electromagnetic wave shielding member 1 is manufactured and before it is used. It is something to keep. Therefore, when the electromagnetic wave shielding member 1 is used, that is, when incorporated in a PDP or the like, the protective film 2 is peeled off. In the present invention, as shown in FIG. 2, the protective film 2 is embedded in the adhesive layer 22 of the protective film 2 with the protruding portions on both side ends 17 of the line crest portion of the conductive pattern layer 12 being recessed in the center of the top portion. A gap is formed between the bottom of 18 and the adhesive layer 22 so as to be in close contact with the surface of the electromagnetic wave shielding member 1. As described above, the adhesive area between the electromagnetic wave shielding member and the adhesive layer of the protective sheet is only a part of the top of the wire ridge, so that the protective sheet is peeled off without requiring force even when the electromagnetic wave shielding member is used. In addition, when the protective film is peeled off, the conductive pattern layer is not peeled off, and even when the surface of the conductive pattern layer is partially peeled off, It is difficult to stand out because it is limited to the vicinity of the surface of the narrow area and the narrow area only in the vicinity of the protruding portion of the part, and the influence on the conductivity (electromagnetic wave shielding) can be ignored. Furthermore, since only the both side ends of the conductive pattern layer are in close contact with the adhesive layer of the protective film, the protective film is not peeled off during transportation or storage. In other words, the peeling force (adhesive strength) is strong against peeling at a low pruning speed assumed for peeling during storage and transportation, while at the high pruning speed assumed for peeling work. It has a characteristic that the peeling force is strong against peeling.

  As the base material 21 constituting the protective film 1, materials used for general protective films can be used without limitation. For example, polyethylene terephthalate (PET), polyethylene naphthalate (PEN), ethylene glycol-1 , 4 Cyclohexanedimethanol-terephthalic acid copolymer, ethylene glycol-terephthalic acid-isophthalic acid copolymer, polyester-based resins such as polyester-based thermoplastic elastomer, and resin films such as polyolefin-based resins such as polyethylene and polypropylene Can do. These resin films are not limited to a single layer, and may be multilayer resin films. The thickness of such a protective film substrate is generally 20 to 75 μm although it depends on the material of the substrate.

  Moreover, as an adhesive which can adhere the protective film 2 to the surface of the electromagnetic wave shielding member 1 in a peelable manner, for example, natural rubber, synthetic rubber, acrylic resin, polyvinyl ether resin, urethane resin, Examples thereof include a silicone resin system and an ethylene-vinyl acetate copolymer system. Specific examples of synthetic rubbers include styrene-butadiene rubber, acrylonitrile-butadiene rubber, polyisobutylene rubber, isobutylene-isoprene rubber, styrene-isoprene block copolymer, styrene-butadiene block copolymer, styrene-ethylene-butylene block. A copolymer is mentioned. Specific examples of the silicone resin system include dimethylpolysiloxane. Specific examples of acrylic resins include homopolymers or copolymers of one or more of (meth) acrylic acid alkyl ester monomers such as ethyl (meth) acrylate, methyl (meth) acrylate, and butyl (meth) acrylate. , One or more of these (meth) acrylic acid alkyl ester monomers, and (meth) acrylic acid alkyl ester and 2-hydroxyethyl (meth) acrylate, hydroxyl group-containing (meth) methacrylic acid such as 2-hydroxy3-phenoxypropyl (meth) acrylate Copolymers with one or more acid alkyl ester monomers, one or more of these (meth) acrylic acid alkyl ester monomers and carboxylic acids such as (meth) acrylic acid, phthalic acid and maleic acid, olefins such as ethylene and propylene, etc. Examples thereof include a copolymer with a monomer. These pressure-sensitive adhesives can be used singly or in combination of two or more. Among these, an acrylic adhesive is preferable. These adhesives may use what is marketed, for example, Cybinol ATR-340 (made by Seiden Chemical Co., Ltd.) etc. are mentioned.

  The pressure-sensitive adhesive layer 22 can be formed by applying the above-described pressure-sensitive adhesive on the protective film substrate 21 and drying it. The thickness of the pressure-sensitive adhesive layer is about 5 to 30 μm, and the thickness of the pressure-sensitive adhesive layer can be adjusted within the above range depending on the amount of pressure-sensitive adhesive applied.

<Electromagnetic wave shield sheet>
The electromagnetic wave shielding sheet according to the present invention is configured to include the above-described electromagnetic wave shielding member 1 and a protective film 2 that is detachably provided on the surface thereof. Various functional layers (not shown) may be further provided. As such a functional layer, a near-infrared absorbing layer, a neon light absorbing layer, a toning layer, an ultraviolet absorbing layer, an antireflection layer, an antiglare layer, a so-called thin film microlouver layer described in JP-A-2007-272161, and the like Optical functional layer (optical filter layer), hard coat layer, impact resistant layer (impact absorbing layer), antifouling layer, antistatic layer, antibacterial layer, antifungal layer, etc., and these functional layers are single layers Alternatively, a plurality of layers may be used.

  The electromagnetic wave shielding sheet according to the present invention can be used for various applications with the protective film peeled off. In particular, plasma displays (PDP) and cathode ray tube displays used in display units of television receivers, various measuring instruments and instruments, various office equipment, various medical equipment, computer equipment, telephones, electrical signs, various game machines, etc. (CRT), a liquid crystal display (LCD), an electroluminescent display (EL) and the like, which are suitable for a front filter of an image display device, and particularly suitable for a plasma display. In addition, electromagnetic shielding applications such as windows of various home appliances such as windows of buildings such as houses, schools, hospitals, offices, stores, vehicles, vehicles, airplanes, ships, microwave ovens, etc. Can also be used.

  The present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

Example 1
<Production of electromagnetic shielding member>
First, an intaglio was prepared. An intaglio was prepared as follows. The surface of the cylindrical plate with the copper plating layer coated on the hollow iron cylindrical surface is mechanically cut and then electrolytically plated with a chromium film on the front surface. The surface of the cylindrical plate is 20 μm deep and the line width is 20 μm. A square lattice mesh pattern-shaped recess having a repetition period of 300 μm in length and width was formed to obtain an intaglio for printing. The main cutting plane shape of the wire rod pattern of the concave portion of the intaglio is a trapezoidal shape in which the width of the bottom portion (side closer to the center of the cylinder) is limited, and both bottom corners of the bottom corner are exposed to the cylindrical surface portion by 75 degrees. Both corner angles of the corner were 105 degrees, the height of the trapezoid was 20 μm, and the length of the bottom exposed on the surface of the trapezoidal cylinder was 20 μm. In addition, the central portion of the bottom of the concave portion of the trapezoidal main cut surface (corresponding to the top portion in the conductive pattern layer) protrudes by being curved by 2 μm from the end corner portion (in the conductive pattern layer, the central portion of the wire ridge top portion is on both sides of the top portion. It corresponds to a shape that corresponds to a depression by being curved by 2 μm from the end.

  Next, a non-colored transparent biaxially stretched polyethylene terephthalate (PET) strip film (A4300 manufactured by Toyobo Co., Ltd.) having a thickness of 100 μm and a width of 1080 mm × 2000 m was prepared as a transparent substrate. An ultraviolet curable resin composition for the primer layer was applied and formed on one surface of the transparent substrate so that the dry film thickness was 10 μm. The application method employs a normal gravure reverse roll coating method, and the UV curable resin composition includes 35 parts by mass of an epoxy acrylate prepolymer, 12 parts by mass of a urethane acrylate prepolymer, 44 parts by mass of phenoxyethyl acrylate, ethylene oxide-modified isocyanuric. 9 parts by weight of acid triacrylate and further 3 parts by weight of Irgacure 184 (substance name: 1-hydroxy-cyclohexyl-phenyl-ketone, manufacturer: Ciba Specialty Chemicals) as a photopolymerization initiator were used. The viscosity at this time was about 1300 cps (25 ° C., B-type viscometer), and the primer layer after application showed fluidity when touched, but did not flow down from the PET film.

  On the plate surface of the cylindrical intaglio plate obtained as described above, a paste-like conductive composition having the following composition was applied with a pick-up roll, and the conductive composition other than the inside of the recess was scraped off with a steel doctor blade. The conductive composition was filled only in the recess. Next, a PET film in which a primer layer in a fluid state is formed between a roll-shaped intaglio plate in a state where the conductive composition is filled in the concave portion and a nip roll, and the pressing force (attachment) of the nip roll against the roll-shaped intaglio plate is provided. The flowable primer layer is caused to flow into the recess of the conductive composition existing in the recess by force, and the conductive paste and the primer layer in the fluidity maintaining state are brought into close contact with each other without any gap, and a part of the primer is recessed. It was made to osmose | permeate in the inside electroconductive composition.

The conductive composition was prepared by blending the following components, sufficiently stirring and mixing, and kneading with three rolls.
Silver powder with an average particle size of 2 μm 93 parts by weight Thermoplastic polyester urethane resin 7 parts by weight 25 parts by weight of butyl carbitol acetate as a solvent

  Subsequently, while rotating the intaglio roll, ultraviolet rays were irradiated with a high-pressure mercury lamp to cure the fluidized primer layer made of the ultraviolet curable resin composition. Due to the curing of the primer layer, the conductive paste in the recesses of the intaglio roll is in close contact with the cured primer layer, and then the film is peeled from the intaglio roll by the nip roll on the outlet side, and the conductive composition layer is formed on the primer layer. Was transferred and formed. The film thus obtained is passed through a 130 ° C. drying zone, dried with hot air for 60 seconds, the solvent in the conductive composition is evaporated, and the primer layer is composed of the conductive conductive composition. A conductive pattern layer of a square lattice having a thickness of 19 μm, a line width of 20 μm, and a vertical / horizontal line repetition period of 300 μm was formed. The obtained conductive pattern layer had a shape in which the central portion of the top portion was curved and recessed by 1.5 μm from the end corner portion.

  A metal layer was formed on the surface of the mesh pattern formed as described above on the PET film. As the plating solution used for forming the metal layer, water (3000 L) was used as a solvent, copper sulfate pentahydrate (75 g / L), sulfuric acid (180 g / L), hydrochloric acid (60 mg / L), orientation A hydrocarbon-based polymer plating additive (40 mL / L) was mixed as a control component to prepare a plating solution. The plating conditions were bath volume (500 mL), stirring (air stirring), bath temperature (25 ° C.), current density (2 A / dm 2), plating time (5 min), and the film thickness was 2.0 μm. The coating deposited by plating was annealed at 120 ° C. for 60 minutes to obtain a copper plating layer. In the metal layer (copper plating layer) formed in this way, the main cut surface in the width direction of the wire pattern of the conductive pattern layer has a substantially trapezoidal shape, and both side edges of the upper side (line peak) are the upper side (wire model). (Top) The shape protruded 3 μm from the bottom of the central recess.

Blackening treatment was performed on the surface of the metal layer thus formed. The blackening treatment was performed by cathodic electrolysis using an electrolytic bath having the following bath composition and roughening treatment.
1st layer copper sulfate pentahydrate 70g / L
Sulfuric acid 100g / L
Liquid temperature 40 ℃
Current density 40A / dm2
Electrolysis time 5 seconds Anode Platinum
2nd layer copper sulfate pentahydrate 250g / L
Sulfuric acid 100g / L
Liquid temperature 45 ℃
Current density 20A / dm2
Electrolysis time 30 seconds Anode Platinum

  By the roughening treatment performed under the above-described conditions, the main cut surface of the wire ridge of the conductive pattern layer has a substantially trapezoidal shape, and both side ends of the upper side (line ridge crest) are the concave portions at the center of the upper side (line ridge crest). The shape protruded from the bottom by 3 μm, and the surface of the recess was distributed in the range of 0.1 to 0.8 μm in length, in which a number of branched and meandering concave grooves were formed. A blackened layer made of acicular crystals was formed.

  When the wire rod of the conductive shield member thus obtained was observed with a scanning electron microscope, the shape was as shown in FIG.

<Preparation of protective film>
An acrylic adhesive layer in which a PET separator (Therapel BX9A (RX), film thickness 38 μm, manufactured by Toray Film Processing Co., Ltd.) is used as a protective film substrate, and the following components are mixed and dispersed on one surface of the substrate. The forming coating liquid was applied so that the film thickness at the time of drying was 20 g / m ² and sufficiently dried, thereby forming an adhesive layer on the surface of the protective film substrate.
Acrylic adhesive (Cybinol ATR-340, solid content 42%, made by Seiden Chemical Co., Ltd.) 100 parts by mass Curing agent (K-200, solid content 1%, made by Seiden Chemical Co., Ltd.) 2.38 parts by mass Silane coupling agent ( M-2, solid content 0.25%, manufactured by Seiden Chemical Co., Ltd.) 0.60 parts by mass Toluene 25 parts by mass

<Production of electromagnetic shielding sheet>
The prepared protective film is attached to the surface of the electromagnetic shielding member obtained as described above on which the conductive pattern layer is provided, and the protrusions on both sides of the top of the conductive pattern layer on the adhesive layer of the protective film are projected. Although the portion was buried, an electromagnetic wave shielding sheet was produced by closely contacting the conductive pattern layer and the adhesive layer so that a gap was formed between the bottom of the recess at the center of the top and the adhesive layer.

Comparative Example 1
In Example 1, instead of the intaglio plate used, a negative photosensitive resist film was applied to the surface of a cylindrical plate material obtained by coating a hollow iron cylindrical surface with a copper plating layer. A square lattice pattern with a width and a repetition period is exposed with an Ar ion laser, the copper layer is exposed by washing away the unexposed portion on the surface of the cylindrical plate material, and only the opening portion of the square lattice (the portion other than the wire rod portion) In the state where the resist film remains, the copper layer of the resist non-formation portion is corroded with an aqueous ferric chloride solution, and a square plate having a depth of 20 μm, a line width of 20 μm, and a vertical / horizontal line repetition period of 300 μm It was manufactured in the same manner as in Example 1 except that an intaglio plate having a mesh pattern-like concave portion of a lattice was used.

  In the electromagnetic wave shielding member formed using the intaglio as described above, the main cut surface shape of the wire pattern of the conductive pattern layer is a beautiful semicircular shape with less surface irregularities, and the top portion is at the center portion than the end portion. It became the shape where the direction protruded. Even if it was plated, the base shape was affected as it was, resulting in a beautifully rounded plating layer shape. Further, when the vicinity of the wire rod of the conductive shield member was observed with a scanning electron microscope, no groove was formed near the top.

  A protective film was attached to the surface of the electromagnetic shielding member obtained as described above in the same manner as in Example 1 to form an electromagnetic shielding sheet. When the main cut surface in the vicinity of the wire rod of the conductive shield member was observed with a scanning electron microscope, as shown in FIG. 4, the entire wire pattern top portion of the conductive pattern layer was buried in the adhesive layer, and there was no wire wrinkle (opening portion). ) Between the bottom and the adhesive layer.

<Evaluation>
The electromagnetic wave shielding sheets of Example 1 and Comparative Example 1 obtained as described above were left on a flat plate in an environment of 40 ° C. for 48 hours, and then visually checked for floating (mixture of bubbles) on the protective film. Confirmed. As a result, no floating was observed in any of the electromagnetic wave shielding sheets of Example 1 and Comparative Example 1.

  Next, the protective film was peeled off from the electromagnetic shielding sheet vigorously, and the surface state of the electromagnetic shielding member after the protective film was peeled off and the state of the adhesive layer surface of the peeled protective film were visually confirmed. As a result, in the electromagnetic wave shielding sheet of Example 1, no damage was found in the wire pattern of the electromagnetic wave shielding member. In addition, no residue was observed on the surface of the peeled protective film. On the other hand, in the electromagnetic shielding sheet of Comparative Example 1, a part of the wire rod pattern of the electromagnetic shielding member was damaged. Moreover, it has confirmed that the acicular metal considered to be a part of blackening layer remained also on the surface of the adhesion layer of the peeled protective film.

DESCRIPTION OF SYMBOLS 1 Electromagnetic wave shielding member 2 Protective film 11 Transparent base material 12 Conductive pattern layer 17 Projection part of line top part 18 Depression part of line top part 21 Base material for protective films 22 Adhesive layer

Claims (7)

An electromagnetic wave shielding sheet comprising: an electromagnetic wave shielding member; and a protective film provided on the surface of the electromagnetic wave shielding member so as to be peelable,
The electromagnetic wave shielding member includes a transparent base material, and a conductive pattern layer formed with a wire rod pattern provided on the transparent base material,
The protective film includes a base material and an adhesive layer provided on the base material,
The wire pattern of the conductive pattern layer protrudes at both ends at the top and is recessed at the center of the top, and the protrusions at both ends of the line cover at the both ends are buried in the adhesive layer of the protective film. The electromagnetic wave shielding sheet, wherein the conductive pattern layer and the adhesive layer are in close contact so that a gap is formed between the bottom of the adhesive layer and the adhesive layer.   The electromagnetic wave shield sheet according to claim 1, wherein a metal layer is formed on a surface of the conductive pattern layer.   The electromagnetic wave shielding sheet according to claim 2, wherein the surface of the metal layer is covered with a blackening layer made of acicular metal.   The electromagnetic wave shielding sheet according to any one of claims 1 to 3, wherein the conductive pattern layer is made of a conductive composition containing conductive particles and a resin binder.   The electromagnetic wave shield sheet according to claim 4, wherein a primer layer is provided between the transparent substrate and the conductive pattern layer.   The electromagnetic wave shielding sheet according to any one of claims 1 to 5, wherein the adhesive layer is made of an acrylic adhesive.   The electromagnetic wave shielding sheet according to any one of claims 1 to 6, wherein a streak-like concave groove is formed on the surface of the metal layer of the concave portion of the wire rod.