JP2009147090A - Electromagnetic shielding sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electromagnetic shielding sheet including a resin sheet base material for controlling waving of the entire part and a metal mesh member provided on the base material and also provide an optical sheet including the electromagnetic shielding sheet as a structural element. <P>SOLUTION: The electromagnetic shielding sheet 100 includes the resin sheet base material and the metal mesh member provided on the base material. The metal mesh member includes a metal mesh part 13a and a metal frame 13b provided at least to part of the circumference of the metal mesh part. A metal removing part 14 is formed to the metal frame 13b toward the external edge 13c from the metal mesh part 13a. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an electromagnetic wave shielding sheet such as an optical display panel such as a liquid crystal panel or a plasma display panel (PDP).

  It is known that electromagnetic waves having a possibility of causing malfunction of other electronic devices are radiated from the screen side of a display panel such as a PDP. For this reason, conventionally, an electromagnetic wave shielding sheet for preventing electromagnetic waves from being radiated to the outside is provided on the screen side surface of the display panel. The basic structure of such an electromagnetic wave shielding sheet is that a metal mesh member is laminated on a transparent polyethylene terephthalate substrate via an adhesive layer, and this metal mesh member becomes a frame of a display screen such as a PDP and It is comprised from the metal frame part used also as the earth | ground installation part of the electromagnetic wave shielding sheet | seat, and the metal mesh part formed in the inner side.

  Such an electromagnetic wave shielding sheet is prepared as described below. First, a copper foil is laminated on the surface of a transparent polyethylene terephthalate substrate via an adhesive to obtain a laminated material. Next, the copper foil of this laminated material is etched into a mesh shape leaving a frame-shaped outer periphery, and processed into a metal frame portion and a metal mesh portion inside thereof to obtain an electromagnetic wave shielding sheet (Patent Document) 1). In addition, the obtained electromagnetic shielding sheet is usually an optical filter in which a plurality of optical functional layers are laminated on the metal mesh side surface for color tone correction and antireflection.

Japanese Patent Laid-Open No. 11-233992

  However, while the ratio of the copper foil area per unit area of the metal frame portion is 100%, the ratio of the copper foil area per unit area of the metal mesh portion is only about 10%, and the electromagnetic shielding sheet There is a problem that the heat shrinkage ratio of the metal mesh portion is larger than that of the metal frame portion. For this reason, due to the thermal history when the electromagnetic wave shielding sheet is processed into an optical filter, distortion and undulation are generated in the vicinity of the boundary between the portion corresponding to the metal mesh portion and the portion corresponding to the metal frame portion, and the entire surface is wavy. When the degree of the undulation becomes large, when the electromagnetic wave shielding sheet or the optical filter is bonded to the PDP or the like, wrinkles are generated, bubbles enter the panel or the outer edge is lifted, and the image quality is adversely affected. The probability of appearing is increased.

  The present invention is intended to solve the above-described problems of the prior art, and includes an electromagnetic wave shielding sheet having a resin sheet base material and a metal mesh member provided thereon, and an optical element including the electromagnetic wave shielding sheet. The purpose is to suppress the undulation of the entire filter.

  The inventors of the present invention have found that by forming a metal removal portion in the metal frame portion from the metal mesh portion toward the outer edge, it is possible to suppress undulation of the entire electromagnetic wave shielding sheet, and completed the present invention.

  That is, the present invention includes a resin sheet base material and a metal mesh member provided thereon, and the metal mesh member is provided on at least a part of the metal mesh portion and the peripheral portion thereof. An electromagnetic wave shielding sheet comprising: a metal removing portion formed on the metal frame portion from the metal mesh portion toward the outer edge.

  The present invention also provides an optical filter having the above-described electromagnetic wave shielding sheet and an optical functional layer laminated thereon.

  In the electromagnetic wave shielding sheet of the present invention, a metal removal portion is formed from the metal mesh portion toward the outer edge in the metal frame portion of the metal mesh member laminated on the resin sheet base material. For this reason, the thermal contraction rate of the portion corresponding to the metal frame portion of the electromagnetic wave shielding sheet can be brought close to the thermal contraction rate of the portion corresponding to the metal mesh portion. Therefore, it is possible to suppress undulation of the electromagnetic wave shielding sheet and the entire optical filter including the electromagnetic shielding sheet.

  A sectional view of a basic embodiment of the electromagnetic wave shielding sheet of the present invention is shown in FIG. 1A, and a top view thereof is shown in FIG. 1B. As can be seen from these drawings, the electromagnetic wave shielding sheet 100 of the present invention has a structure having a resin sheet substrate 11 and a metal mesh member 13 provided thereon via an adhesive layer 12. The metal mesh member 13 includes a metal mesh portion 13a and a metal frame portion 13b provided on at least a part of the peripheral edge portion. In the electromagnetic wave shielding sheet of the present invention, as shown in FIG. 1B, a metal removal portion 14 is formed in the metal frame portion 13b from the metal mesh portion 13a toward the outer edge 13c. By forming the metal removal part 14 in the metal frame 13b, the thermal contraction rate of the entire electromagnetic wave shielding sheet can be made uniform.

  The metal mesh member 13 is for shielding electromagnetic waves such as radio waves, infrared rays, visible rays, ultraviolet rays, X-rays, and gamma rays emitted from the PDP without impairing the visibility of the image displayed on the PDP. The metal mesh member 13 is made of copper, gold, iridium-titanium composite oxide, or the like. A preferable material of the metal mesh member 13 is copper from the viewpoint of workability. In the case of copper, it is preferable that the metal mesh member 13 is subjected to a blackened surface treatment by a conventional method from the viewpoint of improving the contrast of the display. Moreover, since the adhesive strength with an adhesive material layer improves, it is preferable.

  If the thickness of the metal mesh member 13 is too thin, uniform formation on the resin sheet substrate becomes difficult, and if it is too thick, the workability by etching becomes low, so that it is preferably 2 μm to 70 μm, more preferably 6 μm to 20 μm. .

  If the metal line width constituting the metal mesh portion 13a constituting the metal mesh member 13 is too thin, it is difficult to stably process by etching or the like, and if it is too thick, the metal electrical resistance value is larger than the surface electric resistance value of the metal mesh portion. Since the electrical resistance value of the frame portion is increased and the function as the ground is reduced, it is preferably 5 μm to 40 μm, more preferably 10 μm to 25 μm. Further, if the metal wire pitch is too small, the visible light transmittance is lowered, and if it is too large, the electromagnetic wave shielding effect is lost. Therefore, the pitch is preferably 150 μm to 500 μm, more preferably 200 μm to 350 μm.

  The metal frame portion 13b serves as a frame for a display screen such as a PDP and also serves as a ground installation portion for the electromagnetic wave shielding sheet. The metal frame portion 13b is preferably arranged so as to surround the entire circumference of the metal mesh 13a from the viewpoint of ground connection and contact setting, but may be discontinuously arranged around the rectangular metal mesh portion 13a. (FIG. 1C), it may be arranged on only one side (FIG. 1C). The width of the metal frame portion 13b is appropriately determined in consideration of the surface resistance value of the metal mesh portion 13a.

  Further, a metal removal portion 14 is formed on the metal frame portion 13b from the metal mesh portion 13a toward the outer edge 13c. A plurality of metal removal portions 14 are usually provided in the metal frame portion 13b. It is preferable that at least some of the plurality of metal removal portions 14 reach the outer edge of the metal frame portion 13b. When the outer edge is reached, it becomes easy to make the heat shrinkage rate of the entire electromagnetic wave shielding sheet uniform.

  As the shape of the metal removing portion 14, a straight line as shown in FIG. 1A, a line shape such as a curved line (FIG. 1E), a tree shape (FIG. 1F), or a shape in which a plurality of ellipses are connected by straight lines (FIG. 1G). ) And other geometric patterns. A preferable shape is a line from the viewpoint of workability. If the removal width in this case is too narrow, it becomes difficult to process by etching, and if it is too wide, the surface electrical resistance value of the remaining metal part becomes large and the function as grounding is reduced, so that it is preferably 10 μm to 300 μm, more preferably 50 μm to 100 μm.

  In the metal frame part 13b, the area ratio between the metal removal part 14 and the metal non-removal part is that the former is too small, the etching processability is lowered, and conversely, the too much is that the resin sheet base material has an electromagnetic shielding effect. When laminating sheets, air entrainment is likely to occur, and since the surface electrical resistance value of the metal frame portion 13b is smaller than the surface electrical resistance value of the metal mesh portion, the function as ground is reduced, Preferably it is 1: 1000-15: 1, More preferably, it is 1: 200-10: 1.

  The resin sheet substrate 11 functions as a support for the metal mesh member 13 and can be formed from a transparent resin material such as polyethylene terephthalate, polyphenylene sulfide, polyethylene naphthalate, or cycloolefin polymer. If the thickness of the transparent resin sheet substrate 11 is too thin, the rigidity as a support becomes insufficient, and if it is too thick, the light transmittance becomes low, so it is preferably 0.025 mm to 0.200 mm, more preferably 0. 075 mm to 0.125 mm.

  The adhesive material layer 12 is for laminating the metal foil to be processed into the metal mesh member 13 on the resin sheet base material 11, and has been conventionally used when laminating the metal foil on the resin sheet. It can be formed from an adhesive. If the thickness of the adhesive layer 12 is too thin, the adhesive strength is not sufficient, and if it is too thick, foaming occurs during the formation of the adhesive layer and the transparency is lowered, so that it is preferably 5 μm to 20 μm, more preferably 8 μm. ~ 15 μm.

  Such an adhesive layer 12 is preferably cross-linked with a known polyisocyanate-based cross-linking agent to form an isocyanate cross-linked adhesive layer in order to improve heat resistance and chemical resistance.

  The electromagnetic wave shielding sheet of the present invention can be produced as described below. First, a metal foil such as a copper foil is laminated on the surface of a resin sheet substrate such as a transparent polyethylene terephthalate substrate via an adhesive to obtain a laminated material. Next, the metal foil of this laminated material is etched into a mesh shape leaving a frame-shaped outer periphery, and processed into a metal frame portion and a metal mesh portion inside the metal frame portion to obtain an electromagnetic wave shielding sheet. Known methods can be employed for the adhesive application method and the metal foil etching method.

  The electromagnetic shielding sheet of the present invention thus obtained can be used as an optical filter by laminating an optical functional layer on the surface of the metal mesh. Examples of such an optical functional layer include an antireflection film, a color tone correction layer, and a near infrared cut layer. Specific examples of such an optical filter are shown in FIGS.

  The optical filter 200 in FIG. 2 has an adhesive material layer 21 formed on the back surface of the transparent resin sheet base material 11, and an adhesive material layer 12, a metal mesh member 13, a transparent adhesive material 22, and color tone adjustment on the front surface side. The function and near-infrared cut functional layer 23, the transparent support layer 24, and the antireflection layer 25 are laminated. The optical filter 300 of FIG. 3 has an adhesive material layer 21 formed on the back surface of a transparent resin sheet base material 11, and an adhesive material layer 12, a metal mesh member 13, a color tone adjustment function, and a near infrared cut function on the front surface side. The transparent resin layer 31, the adhesive material layer 32, the transparent support layer 24, and the antireflection layer 25 are laminated. Each layer of the optical filter shown in FIGS. 2 and 3 can have the same layer structure as that of the prior art, except that a metal removal portion is formed on the metal frame portion of the metal mesh member.

  These optical filters can be produced in the same manner as conventional optical filters except that the electromagnetic wave shielding sheet of the present invention is used.

  Hereinafter, the present invention will be specifically described by way of examples.

Examples 1 to 10 and Comparative Example 1
On the entire surface of a transparent polyethylene terephthalate substrate (O300E, Mitsubishi Polyester) having a thickness of 100 μm, length of 40 cm, and width of 50 cm, 100 parts by mass of a solvent-free adhesive (polyester resin), if necessary, an isocyanate crosslinking agent (hexa An adhesive composition to which 10 parts by mass of methylene diisocyanate) was added was applied to the thickness shown in Table 1 to form an adhesive layer, and a 10 μm thick copper foil (TQM2VLR, Mitsui Kinzoku Co., Ltd.) was formed on the adhesive layer. ) To obtain a laminate.

  The obtained laminate was subjected to a test evaluation of “adhesive layer bubble entrainment characteristics” and “adhesion strength” as described below. The obtained results are shown in Table 1.

<Adhesive layer bubble entrainment characteristics>
Whether or not air bubbles were caught in the adhesive layer was visually observed with a 20 × magnifier. When the bubble is not observed at all, the adhesive layer bubble entrapment property is evaluated as “good”, and when it is slightly observed but at a level where there is no practical problem, it is evaluated as “good”, and when it is observed beyond that Was evaluated as “bad”.

<Adhesive strength>
The copper foil and the resin sheet base material are peeled at a peel angle of 90 degrees and a tensile speed of 50 mm / min, and when the peel strength is 2 N / 12.5 mm or more, the adhesive strength is evaluated as “good”, and 1 to 2 N / The case of 12.5 mm was evaluated as “good”, and the case of less than 1N / 12.5 mm was evaluated as “bad”.

  Moreover, the copper foil of the laminated body obtained separately was etched using ferric chloride, and the width of the metal frame portion was 2 cm, the mesh line width was 10 μm, the mesh pitch was 300 μm, the mesh thickness was 10 μm, and the removal portion of Table 1 It processed into the metal mesh member which has line | wire width, and obtained the sheet | seat for electromagnetic wave shielding.

  About the obtained electromagnetic wave shielding sheet, as described below, “copper foil etching processability”, “surface electrical resistance”, “adhesive layer bubble entrainment property”, “heat resistance / chemical resistance” were evaluated. . The obtained results are shown in Table 1.

<Copper foil etching processability>
When the predetermined removal line width can be etched as a continuous line, the copper foil etching processability is evaluated as “good”, and when the number of continuous lines is larger than the discontinuous portion, it is evaluated as “good”. The case where it was less than the continuous part was evaluated as “bad”.

<Surface electrical resistance>
Ratio of “copper foil area of metal frame part” / “copper foil area of metal mesh part” per 1 cm ² , specifically, copper foil per 1 cm ² surface area of the metal frame part including the metal removal part Surface area A (excluding the height direction) and copper foil surface area B (excluding the height direction) per 1 cm ² of the surface area of the metal mesh part including the opening, A / B is 1/1. The above case was evaluated as “good”, and the case where the surface electrical resistance was 1 / 1.2 or more and less than 1/1 was evaluated as “good”, and the case where it was less than 1 / 1.2 was evaluated as “bad”. .

<Heat resistance and chemical resistance>
Blackening treatment liquid (NaClO ₂ 10% by mass, Na ₃ PO ₄ 0.4% by mass, NaOH 3.4% by mass, H ₂ O 86.2% by mass) was heated to 80 ° C. Immerse the shielding sheet for 1.5 minutes to perform copper blackening treatment. If the blackening treatment liquid does not penetrate the interface between the copper pattern and the adhesive, heat resistance and chemical resistance are "good". Evaluation was evaluated as “good” when the level was slightly infiltrated but had no problem in practical use, and “bad” when the level was more than that.

  Moreover, the obtained electromagnetic shielding sheet was placed on a flat plate so that the metal mesh member was on top. On the other hand, a bonding adhesive (CC8702, Sony Chemical & Information Device Co., Ltd.) was applied to a flat glass plate for PDP (thickness 2.8 mm) 40 cm long and 50 cm wide to a thickness of 25 μm. The adhesive material layer was formed into a film by drying for a minute. The PDP glass plate on which this adhesive material layer was formed was placed on the electromagnetic wave shielding sheet from the adhesive material layer side, and bonded at room temperature using the glass's own weight.

  About the thing bonded together, as demonstrated below, the "air entrainment characteristic" in the case of glass bonding was evaluated. The obtained results are shown in Table 1.

<Air entrainment characteristics>
After 24 hours of bonding the glass to the electromagnetic shielding sheet, visually observe whether or not the air entrained in the metal frame portion (frame portion) remains, and if not, the air entrainment characteristics when bonding the glass Was evaluated as “good”, a level that remained slightly but had no problem in practical use was evaluated as “good”, and a case that remained higher than that was evaluated as “bad”.

  As can be seen from Table 1, in the case of Examples 1 to 10, it was a good or good evaluation for any of the evaluation items, but in the case of Comparative Example 1, the metal removal part is not provided in the metal frame part. Therefore, the air entrainment characteristic at the time of glass bonding was poor.

  In the electromagnetic wave shielding sheet of the present invention, the metal frame portion of the metal mesh member laminated on the resin sheet base is formed with the metal removal portion from the metal mesh portion toward the outer edge. The thermal contraction rate of the portion corresponding to the metal frame portion can be made closer to the thermal contraction rate of the portion corresponding to the metal mesh portion. For this reason, the electromagnetic wave shielding sheet of the present invention and the optical filter comprising the same are suppressed in the entire undulation. Therefore, when incorporated in a display panel such as a PDP, there is no air entrainment and image display. An excellent display panel can be provided.

It is sectional drawing of the sheet | seat for electromagnetic wave shielding of this invention. It is a top view of the electromagnetic wave shielding sheet of the present invention. It is a top view of the electromagnetic wave shielding sheet of the present invention. It is a top view of the electromagnetic wave shielding sheet of the present invention. It is an enlarged view of the metal removal part in the electromagnetic wave shielding sheet of the present invention. It is an enlarged view of the metal removal part in the electromagnetic wave shielding sheet of the present invention. It is an enlarged view of the metal removal part in the electromagnetic wave shielding sheet of the present invention. It is sectional drawing of the optical filter of this invention. It is sectional drawing of the optical filter of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Resin sheet base material 12 Adhesive material layer 13 Metal mesh member 13a Metal mesh part 13b Metal frame part 13c Outer edge 14 Metal removal part 21 Adhesive material layer 22 Transparent adhesive material 23 Color tone adjustment function and near-infrared cut function layer 24 Transparent support layer 25 Antireflection layer 31 Transparent resin layer 32 Adhesive layer 100 Electromagnetic wave shielding sheet 200 Optical filter 300 Optical filter

Claims (8)

  An electromagnetic shielding material having a resin sheet base material and a metal mesh member provided thereon, the metal mesh member having a metal mesh portion and a metal frame portion provided at least at a part of the peripheral edge thereof. It is a sheet | seat, Comprising: The metal removal part is formed in this metal frame part toward the outer edge from a metal mesh part, The electromagnetic wave shielding sheet characterized by the above-mentioned.   The electromagnetic shielding sheet according to claim 1, wherein a plurality of the metal removal portions are present, and at least a part of the plurality of metal removal portions reaches the outer edge of the metal frame portion.   The electromagnetic wave shielding sheet according to claim 1, wherein the metal removal portion is formed in a line shape or a geometric pattern shape.   The electromagnetic wave shielding sheet according to claim 3, wherein the removal width of the line-shaped metal removal portion is 10 μm to 300 μm.   The electromagnetic wave shielding sheet according to any one of claims 1 to 4, wherein the metal frame portion has an area ratio of a metal removal portion and a metal non-removal portion of 1: 1000 to 15: 1.   The electromagnetic shielding sheet according to any one of claims 1 to 5, wherein the metal mesh member is made of copper, and the metal mesh portion is blackened.   The electromagnetic wave shielding sheet according to any one of claims 1 to 6, further comprising an isocyanate cross-linking adhesive layer between the resin sheet substrate and the metal mesh member.   An optical filter comprising the electromagnetic wave shielding sheet according to claim 1 and an optical functional layer laminated thereon.

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