Retroreflective sheet material and method of making same

In a process for producing a retroflective sheeting having microretroreflective formations on one surface which are partially metallized and partially exposed to the atmosphere about them, the steps comprising:

• (a) forming a retroreflective sheeting having microretroreflective formations closely spaced on one surface thereof, said formations being configured to retroreflect light entering the other surface of said sheeting and impinging upon the surface of said formations;
• (b) forming a coating on said one surface by first depositing a thin metallic deposit providing a first coating material over substantially the entire surface of said formations and thereafter depositing a second coating material on said metallic deposit over only a minor portion of said formations, said second coating material comprising a protective organic adhesive;
• (c) applying a solvent for the metal of said metallic deposit to said one surface to remove said metallic deposit in the areas unprotected by said second coating material and thereby from the major portion of the surface area of said formations to expose the surface thereof, said removal leaving a partial coating of said metallic deposit and second coating material on the surface of said formations over a minor portion of the surface area;
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• (d) adhering a backing element to said second coating material on said one surface, said backing element extending in a plane generally above said formations and being spaced from said major portion of said surface area of said formations to leave said surface area exposed to the atmosphere thereabout, whereby light rays entering the said other surface of said sheeting and impinging upon said residual coating are reflected thereby and those impinging upon said exposed surface area are reflected by the interface with the atmosphere.

In a process for producing a retroreflective sheeting having microretroreflective formations on one surface which are partially metallized and partially exposed to the atmosphere about them, the steps comprising:

• (a) forming a retroreflective sheeting having microretroreflective formations closely spaced on one surface thereof, said formations being configured to retroreflect light entering the other surface of said sheeting and impinging upon the surface of said formations;
• (b) forming a coating on said one surface by first depositing a second coating material over the major portion of said formations, and thereafter forming a thin metallic deposit comprising a first coating material over substantially the entire surface of said formations, said metallic deposit and second coating material being superposed over only a minor portion of said one surface;
• (c) applying a solvent for said second coating material to said one surface to remove said second coating material and the overlying metallic deposit from the major portion of the surface area of said formations and thereby to expose the surface thereof, said metallic deposit remaining on the surface of said formations over a minor portion of the surface area;
• (d) depositing an adhesive upon said one surface in a grid-like pattern;
• and
• (e) adhering a backing element to said adhesive on said one surface, said backing element extending in a plane generally above said formations and being spaced from said major portion of said surface area of said formations to leave said surface area exposed to the atmosphere thereabout, whereby light rays entering the said other surface of said sheeting and impinging upon said residual metallic deposit are reflected thereby and those impinging upon said exposed surface area are reflected by the interface with the atmosphere.