Moisture-resistant solar control film

Abstract

Solar control film having a water-activatable adhesive system comprising a normally tacky and pressure-sensitive adhesive coating which is covered by a thin tack-free continuous water-soluble layer. The product, which does not require a liner, can be moistened and installed on a windowpane, the water-soluble layer providing lubrication during positioning and the pressure-sensitive adhesive providing the primary bonding to the glass.

I claim: 
     
       1. Flexible adhesive-coated solar control film which is normally not tacky, can be wound on itself in roll form without the use of a protective liner, readily unwound and easily handled in large sheets but which is capable of being firmly, adherently but removably bonded to a glass sheet with a pressure-sensitive adhesive to provide a bubble-free transparent laminated structure, said solar control film comprising in combination: a transparent film backing,   a thin transparent aluminum coating on one face of said backing,   a thin, transparent moisture-transmitting barrier layer coated over the aluminum,   a thin, transparent primer layer coated over said barrier layer, and   a water-activatable adhesive system comprising: a uniform continuous layer of normally tacky water-insoluble pressure-sensitive adhesive coated over said primer layer and firmly adherently bonded thereto and   a thin, uniform continuous light-transmitting tack-free film-forming water-soluble material coated over and firmly bonded to said layer of pressure-sensitive adhesive, whereby water may be applied to the water-soluble material to activate it and render its surface slippery, thus permitting the solar control film to be readily positioned on a glass windowpane in a desired location, after which excess water and water-soluble material can be expelled at the edges of said film and the remaining water evaporated through said film to permit the pressure-sensitive adhesive to bond firmly to said windowpane and form a laminated structure having excellent optical properties.       
     
     
       2. The solar control film of claim 1 wherein the water-soluble material is essentially incompatible with the pressure-sensitive adhesive, thereby permitting said solar control film to be stored for long periods of time without the coated surface's becoming tacky or the pressure-sensitive adhesive quality's being adversely affected. 
     
     
       3. The solar control film of claim 2 wherein the water-soluble material is selected from the group consisting of vinyl ether:maleic acid copolymers and ammonium salts thereof. 
     
     
       4. The solar control film of claim 2 wherein the water-soluble material is methyl cellulose. 
     
     
       5. The solar control film of claim 2 wherein the water-soluble material is a high molecular weight crystalline thermoplastic ethylene oxide polymer. 
     
     
       6. The solar control film of claim 2 wherein the film backing consists essentially of a biaxially oriented polyethylene terephthalate film. 
     
     
       7. The solar control film of claim 2 wherein the pressure-sensitive adhesive is one which is resistant to sunlight-induced discoloration and has an adhesion value to glass in the range of 10-100 ounces per inch of width, even after being applied thereto and exposed to sunlight for several months. 
     
     
       8. The solar control film of claim 7 wherein the adhesion to glass is in the range of 20 to 50 ounces per inch of width. 
     
     
       9. In a solar control film of the type comprising an optically clear flexible polymeric film backing having on one surface a transparent reflective corrodible metal coating on the order of 25 to 125 angstroms thick, a transparent moisture transmitting water-insoluble protective organic coating uniformly contacting and firmly bonded to said metal coating, and a transparent water-activatable adhesive layer uniformly contacting and firmly bonded to said protective coating, the improvement which comprises: using as said adhesive layer a system which comprises: a primer layer over said organic coating,   a uniform continuous layer of normally tacky water-insoluble pressure-sensitive adhesive bonded to said primer layer, and   a thin, uniform continuous transparent layer of film-forming tackfree water-soluble material coated over and firmly bonded to said layer of pressure-sensitive adhesive so as to constitute the outermost portion of said adhesive layer, whereby said solar control film can be readily handled in large sheets without the use of a liner but can be moistened and immediately applied to a glass surface without removing the water-soluble material to permit the pressure-sensitive adhesive to establish bonding contact with said glass.       
     
     
       10. A method of forming a laminated window glazing consisting essentially of a rigid transparent pane and a flexible light-transmitting solar control film comprising the steps of: providing a thin, highly flexible solar control film comprising in combination: a transparent film backing   a thin transparent metal coating on one face of said backing and   a water activatable adhesive system comprising: a uniform continuous layer of normally tacky water-insoluble pressure-sensitive adhesive coated over and firmly adherently bonded to said metal coating and     a thin, uniform continuous transparent layer of tackfree film-forming water-soluble material coated over and firmly bonded to said layer of pressure-sensitive adhesive,     applying water to the surface of the water-soluble material, thereby tending to dissolve said material and render the surface thereof slippery,   placing the slippery surface of said solar control film in contact with, and sliding it to a predetermined location on, said pane,   squeegeeing the exposed surface of said solar control film to expel excess water and water-soluble material and achieve uniform contact between said pane and said film throughout their coextensive areas, and   permitting the remaining water to evaporate, thereby bringing the pressure-sensitive adhesive into firm bonding contact with the pane.   
     
     
       11. A laminated windowpane made by the method of claim 10.