Protective film temporarily lamination to electromagnetic wave shielding sheet, method for producing the same, and electromagnetic wave shielding sheet

Abstract

The present invention is to provide an electromagnetic wave shielding sheet with a protective film that is temporarily laminated on a copper mesh layer for shielding electromagnetic waves, the electromagnetic wave shielding sheet is not discolored even after long-term use, especially at high temperature and high humidity, while the protective film exhibits appropriate adhesion properties. To achieve the object, there is provided an electromagnetic wave shielding sheet comprising a transparent substrate, at least a copper mesh layer provided on one surface of the transparent substrate and a protective film temporarily laminated to the copper-mesh-layer-side surface, the protective film comprises a support and an adhesive layer containing a polymer having repeating units derived from an acrylic ester and/or a methacrylic ester on the support, and the amount of free organic acids in the adhesive layer is an amount which makes 10 or less the color difference ΔE L*a*b* of the copper-mesh-layer-side surface of the electromagnetic wave shielding sheet before and after the adhesive layer surface is laminated on the copper-mesh-layer-side surface and they are left for 200 hours in an atmosphere of a temperature of 60° C. and a relative humidity of 95%.

1 . A protective film for temporary lamination to an electromagnetic wave shielding sheet in which at least a copper mesh layer is provided on one surface of a transparent substrate,
 wherein the protective film is for temporary lamination to a copper-mesh-layer-side surface of the electromagnetic wave shielding sheet,   wherein the protective film comprises a support and an adhesive layer containing a polymer having repeating units derived from an acrylic ester and/or a methacrylic ester on the support, and   wherein an amount of free organic acids in the adhesive layer is an amount that makes 10 or less a color difference ΔE L*a*b*  of the copper-mesh-layer-side surface of the electromagnetic wave shielding sheet before and after the adhesive layer surface is laminated on the copper-mesh-layer-side surface and they are left for 200 hours in an atmosphere of a temperature of 60° C. and a relative humidity of 95%.   
     
     
         2 . The protective film for temporary lamination to an electromagnetic wave shielding sheet according to  claim 1 ,
 wherein the repeating units derived from an acrylic ester and/or a methacrylic ester in the adhesive layer comprise repeating units derived from urethane acrylate and/or urethane methacrylate.   
     
     
         3 . A protective film for temporary lamination to an electromagnetic wave shielding sheet,
 wherein the protective film comprises a support and an adhesive layer containing a polymer having repeating units derived from an acrylic ester and/or a methacrylic ester on the support, and   wherein 20 ng/cm 2  or less is a total amount of acetic acid and formic acid extracted upon testing the protective film by a test method in which the adhesive layer surface of the protective film is extracted at 23° C. for 15 minutes with ultrapure water and the resulting extract is measured for an amount of extracted acetic acid and an amount of extracted formic acid by ion chromatography.   
     
     
         4 . The protective film for temporary lamination to an electromagnetic wave shielding sheet according to  claim 3 ,
 wherein the repeating units derived from an acrylic ester and/or a methacrylic ester in the adhesive layer comprise repeating units derived from urethane acrylate and/or urethane methacrylate.   
     
     
         5 . A protective film for temporary lamination to an electromagnetic wave shielding sheet,
 wherein the protective film comprises a support and an adhesive layer containing a polymer having repeating units derived from urethane acrylate and/or urethane methacrylate on the support.   
     
     
         6 . An electromagnetic wave shielding sheet comprising:
 a transparent substrate;   at least a copper mesh layer provided on one surface of the transparent substrate; and   a protective film temporarily laminated to a copper-mesh-layer-side surface,   wherein the protective film comprises a support and an adhesive layer containing a polymer having repeating units derived from an acrylic ester and/or a methacrylic ester on the copper mesh layer side of the support, and   wherein an amount of free organic acids in the adhesive layer is an amount that makes 10 or less a color difference ΔE L*a*b*  of the copper-mesh-layer-side surface of the electromagnetic wave shielding sheet before and after the adhesive layer surface is laminated on the copper-mesh-layer-side surface and they are left for 200 hours in an atmosphere of a temperature of 60° C. and a relative humidity of 95%.   
     
     
         7 . The electromagnetic wave shielding sheet according to  claim 6 ,
 wherein the repeating units derived from an acrylic ester and/or a methacrylic ester in the adhesive layer of the protective film comprise repeating units derived from urethane acrylate and/or urethane methacrylate.   
     
     
         8 . The electromagnetic wave shielding sheet according to  claim 6 ,
 wherein delamination resistance of the adhesive layer of the protective film is from 0.05 to 1.3 N/25 mm with respect to the copper-mesh-layer-side surface.   
     
     
         9 . The electromagnetic wave shielding sheet according to  claim 6 ,
 wherein surface roughness of the copper-mesh-layer-side surface to which the protective film is temporarily laminated is, when a roughness profile is used as a profile of the surface, a ten-point average roughness “Rz JIS” (JIS B0601 (1994)) of the profile from 0.5 to 5.0 μm.   
     
     
         10 . The electromagnetic wave shielding sheet according to  claim 6 ,
 wherein surface roughness of the copper-mesh-layer-side surface to which the protective film is temporarily laminated is a center line average roughness “Ra” (JIS B0601 (1994)) of fine irregularities on the surface from 0.1 to 3.0 μm.   
     
     
         11 . An electromagnetic wave shielding sheet comprising:
 a transparent substrate;   at least a copper mesh layer provided on one surface of the transparent substrate; and   a protective film temporarily laminated to a copper-mesh-layer-side surface,   wherein the protective film comprises a support and an adhesive layer containing a polymer having repeating units derived from an acrylic ester and/or a methacrylic ester on the support;   the protective film is temporarily laminated to the copper-mesh-layer-side surface through the adhesive layer; and   20 ng/cm 2  or less is a total amount of acetic acid and formic acid extracted upon testing the protective film by a test method in which the adhesive layer surface of the protective film is extracted at 23° C. for 15 minutes with ultrapure water and the resulting extract is measured for an amount of extracted acetic acid and an amount of extracted formic acid by ion chromatography.   
     
     
         12 . The electromagnetic wave shielding sheet according to  claim 11 ,
 wherein the repeating units derived from an acrylic ester and/or a methacrylic ester in the adhesive layer of the protective film comprise repeating units derived from urethane acrylate and/or urethane methacrylate.   
     
     
         13 . The electromagnetic wave shielding sheet according to  claim 11 ,
 wherein delamination resistance of the adhesive layer of the protective film is from 0.05 to 1.3 N/25 mm with respect to the copper-mesh-layer-side surface.   
     
     
         14 . The electromagnetic wave shielding sheet according to  claim 11 ,
 wherein surface roughness of the copper-mesh-layer-side surface to which the protective film is temporarily laminated is, when a roughness profile is used as a profile of the surface, a ten-point average roughness “Rz JIS” (JIS B0601 (1994)) of the profile from 0.5 to 5.0 μm.   
     
     
         15 . The electromagnetic wave shielding sheet according to  claim 11 ,
 wherein surface roughness of the copper-mesh-layer-side surface to which the protective film is temporarily laminated is a center line average roughness “Ra” (JIS B0601 (1994)) of fine irregularities on the surface from 0.1 to 3.0 μm.   
     
     
         16 . An electromagnetic wave shielding sheet comprising:
 a transparent substrate;   at least a copper mesh layer provided on one surface of a transparent substrate; and   a protective film temporarily laminated to a copper-mesh-layer-side surface,   wherein the protective film comprises a support and an adhesive layer containing a polymer having repeating units derived from urethane acrylate and/or urethane methacrylate on the copper mesh layer side of the support.   
     
     
         17 . The electromagnetic wave shielding sheet according to  claim 16 ,
 wherein delamination resistance of the adhesive layer of the protective film is from 0.05 to 1.3 N/25 mm with respect to the copper-mesh-layer-side surface.   
     
     
         18 . The electromagnetic wave shielding sheet according to  claim 16 ,
 wherein surface roughness of the copper-mesh-layer-side surface to which the protective film is temporarily laminated is, when a roughness profile is used as a profile of the surface, a ten-point average roughness “Rz JIS” (JIS B0601 (1994)) of the profile from 0.5 to 5.0 μm.   
     
     
         19 . The electromagnetic wave shielding sheet according to  claim 16 ,
 wherein surface roughness of the copper-mesh-layer-side surface to which the protective film is temporarily laminated is a center line average roughness “Ra” (JIS B0601 (1994)) of fine irregularities on the surface from 0.1 to 3.0 μm.   
     
     
         20 . A method for producing a protective film for temporary lamination to a copper-mesh-layer-side surface of an electromagnetic wave shielding sheet in which at least the copper mesh layer is provided on one surface of a transparent substrate, the method comprising the steps of:
 selecting an adhesive in which an amount of free organic acids is an amount that makes 10 or less a color difference ΔE L*a*b*  of the copper-mesh-layer-side surface of the electromagnetic wave shielding sheet before and after the adhesive is laminated on the copper-mesh-layer-side surface and they are left for 200 hours in an atmosphere of a temperature of 60° C. and a relative humidity of 95%, from adhesives containing a polymer having repeating units derived from an acrylic ester and/or a methacrylic ester, and   therewith forming an adhesive layer on a support.