Abstract:
A graphics-bearing element is provided in which improved durability in liquid environments is provided through inclusion in a graphics layer of polyvinyl formal resin.

Description:
FIELD OF THE INVENTION 
     This invention relates to graphics bearing elements highly resistant to liquids, and in particular to a heat-activated fluid line marking tape useful in aircraft environments. 
     BACKGROUND OF THE INVENTION 
     The prior art has had difficulty providing marking labels suitably resistant to environments of hydraulic fluid, oils, aircraft fuels and other liquids. 
     SUMMARY OF THE INVENTION 
     We have found that products of highly desirable durability in such environments may be provided through using in the ink of a graphic layer a polyvinyl formal resin. In preferred embodiments, the polyvinyl formal resin is present in amount in the range of 25-50%, is tied to a transparent polyester layer through a primer layer, and carries on the side of the laminate away from the polyester layer a heat-activatable adhesive layer. 
    
    
     PREFERRED EMBODIMENT 
     We turn now to a presently preferred embodiment of the invention. 
     DRAWING 
     There is shown in the drawing a diagrammatic vertical sectional view, partially broken away, through a preferred embodiment of the invention. 
    
    
     DESCRIPTION 
     Turning now to the FIGURE, there is shown a fluid line marking tape indicated generally at 10. It includes a layer of 92 gauge transparent polyester 12, a primer layer 14, an ink graphics layer 16, an adhesive layer 18, and a release liner 20. 
     In the preferred embodiment disclosed, the primer formulation is as follows (by weight): 
     
         ______________________________________Example 149002 polyester resin (DuPont)                 2%Desmodur N-100 polyisocyanate                 0.2%Methylene Chloride    7.8%Cyclohexanone         8%1,1,1 Trichloroethane 64%Nitroethane           18%______________________________________ 
    
     Preferred formulations for four specific colored inks are as follows: 
     
         ______________________________________Color     % by Weight  Material______________________________________Example 2Black     12.5%        carbon black     12.5%        Formvar 7/95*     37.5%        n-propanol     37.5%        nitroethaneExample 3White     30.0%        titanium dioxide     12.0%        Formvar 7/95     29.0%        n-propanol     29.0%        nitroethaneExample 4Yellow    12.8%        Ciba-Geigy X-3218                  Regal Yellow Medium     12.8%        Ciba-Geigy X-2283                  Golden Cadmium Yellow     10.3%        Formvar 7/95     32.05%       n-propanol     32.05%       nitroethaneExample 5Blue      18.33%       titanium dioxide     8.33%        Ciba-Geigy X-2285                  C.P.Ar. Blue     0.12%        carbon black     13.44%       Formvar 7/95     29.89%       n-propanol     29.89%       nitroethane______________________________________ *Trademark of Monsanto. 
    
     The pigments set forth in the above formulations are of the character known in the art as &#34;halogen-free&#34;. 
     The preferred adhesive formulation is (by weight): 
     
         ______________________________________Example 6______________________________________49001 Polyester Resin(DuPont)           40%Mondur SH (BlockedPolyisocyanate)    10%Methyl Ethyl Ketone              50%______________________________________ 
    
     In manufacture, about five pounds of primer (dry basis) are applied per ream of polyester film 12. The primer is then dried to produce primer layer 14, which is then flexographically printed, over the primer 14, with ink graphics layer 16, which includes a last flood coat of white for opacity. 
     Adhesive layer 18 is first cast on the release-coated liner 20 following which the subunit 18, 20 is laminated to the subunit 12, 14, 16. 
     The tape may be applied by wrapping onto a clean metal surface. Adhesive layer 18 may then be cured by heating to at least 270° F. 
     The ink graphics layer 16 is preferably applied using a plate formed from the ultraviolet-curable DuPont material sold by it under the mark &#34;CYREL&#34;. 
     OTHER EMBODIMENTS 
     A preferred general formula for use in graphic layers according to the invention is as follows: 
     
         ______________________________________% by Weight Material______________________________________ 8-30%      Halogen free pigment 8-20%      Monsanto &#34;Formvar&#34; polyvinyl formal       resin20-40%      ethanol, isopropanol, or n-propanol20-40%      nitromethane, nitroethane, 1-nitro-       propane, or 2-nitropropane______________________________________ 
    
     In the final product, after evaporation of the solvent, the polyvinyl formal resin is present in amount in the range of 25-50%.