UV-curable adhesion promoter, laminated structures using same and methods for fabricating such laminated structures

Abstract

An adhesion promoter for enhancing the bond between adjacent layers of a multilayer structure to prevent delamination thereof is disclosed. The adhesion promoter comprises an aromatic polyimide-based UV-cured acrylate. Also disclosed are laminated structures including liquid crystal displays and bonded missile domes that utilize an adhesion promoter of the invention, and methods for fabricating such structures.

1 . An adhesion promoter comprising an aromatic polyimide-based UV-cured acrylate.  
     
     
         2 . An adhesion promoter comprising as constituents: 
 (a) an aromatic polyimide; and    (b) a UV-cured resin,    wherein the proportions by weight of the constituents (a) and (b) are effective to enhance the bond between adjacent layers of a laminated structure.    
     
     
         3 . The adhesion promoter of  claim 2  wherein: 
 the relative proportions, by weight, of said constituents (a) and (b) are from 20% to 60% of (a), and from 40% to 80% of (b) for a total of 100 parts of (a) and (b).    
     
     
         4 . The adhesion promoter of  claim 2  wherein: 
 the relative proportions, by weight, of said constituents (a) and (b) are from 30% to 50% of (a), and from 50% to 70% of (b) for a total of 100 parts of (a) and (b).    
     
     
         5 . The adhesion promoter of  claim 2  wherein: 
 the relative proportions, by weight, of said constituents (a) and (b) are from 35% to 45% of (a), and from 55% to 65% of (b) for a total of 100 parts of (a) and (b).    
     
     
         6 . A mixture for producing an adhesion promoter, the mixture comprising as constituents: 
 (a) an aromatic polyimide;    (b) a UV-curable resin; and    (c) a solvent comprising: 
 (1) ethyl L-lactate; and  
 (2) isopropanol,  
   wherein the percentages by weight of the constituents (a), (b) and (c) are effective to produce an adhesion promoter for enhancing a bond between adjacent layers of a laminated structure.    
     
     
         7 . The mixture of  claim 6  wherein: 
 the relative proportions, by weight, of said constituents (a), (b) and (c) are from 0.2% to 0.6% of (a), from 0.4% to 0.8% of (b), from 55% to 64% of (c) (1), and from 35% to 44% of (c) (2), for a total of 100 parts of (a), (b) and (c).    
     
     
         8 . The mixture of  claim 6  wherein: 
 the relative proportions, by weight, of said constituents (a), (b) and (c) are from 0.3% to 0.5% of (a), from 0.5% to 0.7% of (b), from 57% to 62% of (c) (1), and from 37% to 42% of (c) (2), for a total of 100 parts of (a), (b) and (c).    
     
     
         9 . The mixture of  claim 6  wherein: 
 the relative proportions, by weight, of said constituents (a), (b) and (c) are from 0.35% to 0.45% of (a), from 0.55% to 0.65% of (b), from 59% to 60% of (c) (1), and from 39% to 40% of (c) (2) , for a total of 100 parts of (a), (b) and (c).    
     
     
         10 . A layered structure comprising: 
 a first layer having a surface;    a second layer having a surface confronting the surface of the first layer; and    an adhesion promoter layer joining the confronting surfaces of the first and second layers, the adhesion promoter comprising an aromatic polyimide-based UV-cured acrylate.    
     
     
         11 . The structure of  claim 10  wherein: 
 the first layer comprises a material selected from the group consisting of an inorganic material and an organic material; and    the second layer comprising a material selected from the group consisting of an inorganic material and an organic material.    
     
     
         12 . The structure of  claim 10  wherein: 
 the adhesion promoter layer comprises as constituents:    (a) an aromatic polyimide; and    (b) a UV-cured resin,    wherein the percentages by weight of the constituents (a) and (b) are effective to enhance the bond between adjacent layers of a laminated structure.    
     
     
         13 . The structure of  claim 12  wherein: 
 the relative proportions, by weight, of said constituents (a) and (b) are from 20% to 60% of (a), and from 40% to 80% of (b) for a total of 100 parts of (a) and (b).    
     
     
         14 . The structure of  claim 13  wherein: 
 the relative proportions, by weight, of said constituents (a) and (b) are from 30% to 50% of (a), and from 50% to 70% of (b) for a total of 100 parts of (a) and (b).    
     
     
         15 . The structure of  claim 13  wherein: 
 the relative proportions, by weight, of said constituents (a) and (b) are from 35% to 45% of (a), and from 55% to 65% of (b) for a total of 100 parts of (a) and (b).    
     
     
         16 . The structure of  claim 10  wherein: 
 The adhesion promoter layer has a thickness in the range of 0.05 to 0.15 μm.    
     
     
         17 . A liquid crystal display comprising: 
 a pair of optically transparent substrates defining a liquid crystal cell, each substrate of the pair of substrates having an outer surface carrying an adhesion promoter layer comprising an aromatic polyimide-based UV-cured acrylate; and    an optical layer coated on the adhesion promoter layer.    
     
     
         18 . The display of  claim 17  wherein: 
 the adhesion promoter comprises as constituents:    (a) an aromatic polyimide; and    (b) a UV-cured resin,    wherein the percentages by weight of the constituents (a) and (b) are effective to enhance the bond between adjacent layers of a laminated structure.    
     
     
         19 . The display of  claim 18  wherein: 
 the relative proportions, by weight, of said constituents (a) and (b) are from 20% to 60% of (a), and from 40% to 80% of, (b) for a total of 100 parts of (a) and (b).    
     
     
         20 . The display of  claim 18  wherein: 
 the relative proportions, by weight, of said constituents (a) and (b) are from 30% to 50% of (a), and from 50% to 70% of (b) for a total of 100 parts of (a) and (b).    
     
     
         21 . The display of  claim 18  wherein: 
 the relative proportions, by weight, of said constituents (a) and (b) are from 35% to 45% of (a), and from 55% to 65% of (b) for a total of 100 parts of (a) and (b).    
     
     
         22 . The display of  claim 17  wherein: 
 the optical layer comprises a compensator.    
     
     
         23 . The display of  claim 17  wherein: 
 the optical layer comprises a polarizer.    
     
     
         24 . The display of  claim 17  wherein: 
 The adhesion promoter coating has a thickness in the range of 0.05 to 0.15 μm.    
     
     
         25 . A liquid crystal display comprising: 
 a pair of optically transparent substrates defining a liquid crystal cell, each substrate of the pair of substrates having an outer surface carrying a multilayer structure comprising in sequence from said outer surface an adhesive promoter layer, a pressure sensitive adhesive layer, a second adhesion promoter layer and an optical layer, each of said adhesive promoter layers comprising an aromatic polyimide-based UV-cured acrylate.    
     
     
         26 . The display of  claim 25  wherein: 
 each of said adhesive promoter layers comprises as constituents:    (a) an aromatic polyimide; and    (b) a UV-cured resin,    wherein the percentages by weight of the constituents (a) and (b) are effective to enhance the bond between adjacent layers of a laminated structure.    
     
     
         27 . The display of  claim 26  wherein: 
 the relative proportions, by weight, of said constituents (a) and (b) are from 20% to 60% of (a), and from 40% to 80% of (b) for a total of 100 parts of (a) and (b).    
     
     
         28 . The display of  claim 26  wherein: 
 the relative proportions, by weight, of said constituents (a) and (b) are from 30% to 50% of (a), and from 50% to 70% of (b) for a total of 100 parts of (a) and (b).    
     
     
         29 . The display of  claim 26  wherein: 
 the relative proportions, by weight, of said constituents (a) and (b) are from 35% to 45% of (a), and from 55% to 65% of (b) for a total of 100 parts of (a) and (b).    
     
     
         30 . The display of  claim 25  wherein: 
 the optical layer comprises a compensator.    
     
     
         31 . The display of  claim 25  wherein: 
 the optical layer comprises a polarizer.    
     
     
         32 . The display of  claim 25  wherein: 
 each of said adhesion promoter layers has a thickness in the range of 0.05 to 0.15 μm.    
     
     
         33 . A laminated structure comprising: 
 a first layer optically transparent at selected wavelengths;    a second layer optically transparent at said selected wavelengths, a surface of said first layer being in confronting relationship with a surface of said second layer;    an adhesive layer between said surfaces;    a first UV-cured adhesion promoter layer interposed between and joining the surface of the first layer and the adhesive layer; and    a second UV-cured adhesion promoter layer interposed between and joining the surface of the second layer and the adhesive layer.    
     
     
         34 . The structure of  claim 33  wherein: 
 said first and second layers are made of sapphire.    
     
     
         35 . The structure of  claim 33  wherein: 
 each of the first and second adhesion promoter layers comprises an aromatic polyimide-based UV-cured acrylate.    
     
     
         36 . The structure of  claim 33  wherein: 
 each of the adhesion promoter layers comprises as constituents:    (a) an aromatic polyimide; and    (b) a UV-cured resin,    wherein the percentages by weight of the constituents (a) and (b) are effective to enhance the bond between adjacent layers of a laminated structure.    
     
     
         37 . The structure of  claim 36  wherein: 
 the relative proportions, by weight, of said constituents (a) and (b) are from 20% to 60% of (a), and from 40% to 80% of (b) for a total of 100 parts of (a) and (b).    
     
     
         38 . The structure of  claim 36  wherein: 
 the relative proportions, by weight, of said constituents (a) and (b) are from 30% to 50% of (a), and from 50% to 70% of (b) for a total of 100 parts of (a) and (b).    
     
     
         39 . The structure of  claim 36  wherein: 
 the relative proportions, by weight, of said constituents (a) and (b) are from 35% to 45% of (a), and from 55% to 75% of (b) for a total of 100 parts of (a) and (b).    
     
     
         40 . The structure of  claim 33  wherein: 
 each of the adhesion promoter layers has a thickness in the range of 0.05 to 0.15 μm.    
     
     
         41 . A method of fabricating a laminated, optically transparent structure comprising: 
 preparing a mixture by dissolving an aromatic polyimide and a UV-curable resin in a solvent;    stirring the mixture;    filtering the mixture;    coating the mixture on a surface of a substrate;    air drying the coated mixture; and    curing the coated mixture using UV radiation, the cured coated mixture comprising an adhesion promoter layer.    
     
     
         42 . The method of  claim 41  further comprising: 
 applying an optical layer over the cured adhesion promoter coating.    
     
     
         43 . The method of  claim 42  wherein: 
 the optical layer comprises an optical element selected from the group consisting of a compensator and a polarizer.    
     
     
         44 . The method of  claim 41  wherein: 
 the relative proportions, by weight, of said aromatic polyimide, UV-curable resin and solvent are, respectively, in the ranges of 0.35% to 0.45%; 0.55% to 0.65%; and 98.9% to 99.1%, by weight.    
     
     
         45 . The method of  claim 41  wherein: 
 the solvent comprises as constituents ethyl L-lactate and isoproponal.    
     
     
         46 . The method of  claim 45  wherein: 
 the relative proportions, by weight, of the solvent constituents comprise 55% to 100% of ethyl L-lactate and 0% to 45% of isoproponal, for a total of 100 parts of the solvent.    
     
     
         47 . The method of  claim 41  wherein: 
 the coated mixture has a thickness in the range of 0.05 to 0.15 μm.    
     
     
         48 . The method of  claim 41  further comprising: 
 coating the mixture on a surface of a second substrate;    air drying the coated mixture on the surface of the second substrate;    curing the coated mixture on the surface of the second substrate using UV radiation, the cured coated mixture on the second substrate comprising an adhesion promoter layer; and    bonding the first and second substrates together using an adhesive between the adhesion promoter layers on the first and second substrates.    
     
     
         49 . The method of  claim 48  wherein: 
 the first and second substrates comprise sapphire.    
     
     
         50 . A method of using an aromatic polyimide-based UV-curable acrylate, the method comprising: 
 depositing a coating of said aromatic polyimide-based UV-curable acrylate on the surface of a first layer;    curing said coating using UV radiation; and    applying a second layer on the UV-cured coating, said coating preventing separation of said layers.    
     
     
         51 . The method of  claim 50  wherein: 
 the first layer comprises a material selected from the group consisting of an inorganic material and an organic material; and    the second layer comprises a material selected from the group consisting of an inorganic material and an organic material.    
     
     
         52 . The method of  claim 50  wherein: 
 the coating of said aromatic polyimide-based UV-curable acrylate has a thickness in the range of 0.05 to 0.15 μm.    
     
     
         53 . A mixture for producing an adhesion promoter, the mixture comprising: 
 (a) an aromatic polyimide;    (b) a UV-curable resin; and    (c) a solvent, wherein: 
 (a) is present in an amount from 0.2% to 0.6% of the mixture by weight;  
 (b) is present in an amount from 0.4% to 0.8% of the mixture by weight, and wherein  
 (c) comprises the remainder of the mixture and comprises from 55% to 100%, by weight, of ethyl L-lactate and from 0% to 45%, by weight, of isopropanol.