Protective film

Abstract

A protective film contains a base material and a pressure-sensitive adhesive layer formed thereon, wherein the surface of the pressure-sensitive adhesive layer has a contact angle with methylene iodide as measured just after contact, θ 1 , of 70° or smaller and a change in contact angle with methylene iodide through 30-second standing, Δθ, of 8% or less.

What is claimed is:  
     
         1 . A protective film comprising a base material and a pressure-sensitive adhesive layer formed thereon, wherein the surface of the pressure-sensitive adhesive layer has a contact angle with methylene iodide as measured just after contact, θ 1 , of 70° or smaller and a change in contact angle with methylene iodide through 30-second standing, Δθ, of 8% or less.  
     
     
         2 . The protective film of  claim 1 , wherein the pressure-sensitive adhesive layer comprises a (meth)acrylic polymer as a main polymer.  
     
     
         3 . The protective film of  claim 1 , which is for use in the surface protection of an electromagnetic shielding material.  
     
     
         4 . The protective film of  claim 2 , which is for use in the surface protection of an electromagnetic shielding material.  
     
     
         5 . The protective film of  claim 2 , wherein the (meth)acrylic polymer is a polymer obtained by the homopolymerization or copolymerization of one or more (meth)acrylic esters having an alkyl group having 1 to 18 carbon atoms by solution polymerization or emulsion polymerization.  
     
     
         6 . The protective film of  claim 2 , wherein the (meth)acrylic polymer is a polymer obtained by the copolymerization of one or more (meth)acrylic esters having an alkyl group having 1 to 18 carbon atoms and one or more copolymerizable modifying monomers by solution polymerization or emulsion polymerization.  
     
     
         7 . The protective film of  claim 5 , wherein the (meth)acrylic ester is selected from the group consisting of (meth)acrylic esters having a butyl group, a 2-ethylhexyl group, an isooctyl group, an isononyl group, an ethyl group, or a methyl group.  
     
     
         8 . The protective film of  claim 6 , wherein the (meth)acrylic ester is selected from the group consisting of (meth)acrylic esters having a butyl group, a 2-ethylhexyl group, an isooctyl group, an isononyl group, an ethyl group, or a methyl group.  
     
     
         9 . The protective film of  claim 6 , wherein the copolymerizable modifying monomer is selected from the group consisting of (meth)acrylonitrile, vinyl acetate, styrene, (meth)acrylic acid, maleic anhydride, vinylpyrrolidone, (meth)acrylic esters having a glycidyl group, a dimethylaminoethyl group, or a hydroxyl group, (meth)acrylamide, vinylamine, allylamine, and ethyleneimine.