It is conventional practice in many different areas of technology to improve the bonding capability of surfaces by treating them in one fashion or another. This treatment, in all of its various forms, is generally called priming. The most common methods of priming surfaces include the application of an intermediate layer, physically roughening the substrate, chemically modifying the substrate (e.g., oxidation), and combinations of these methods. With advances in related technologies, each of these methods may be formed by more efficient procedures, but generally accomplish similar effects. For example, in a physical roughening process, the use of such different procedures such as dry abrasive grit, rotary brushes, abrasive grain slurries, and others similar techniques produce similar effects with their own slight variations in properties.
U.S. Pat. Nos. 4,064,030 and 4,155,826 show that radio frequency (R.F.) sputter-etching of fluorinated olefin polymer surfaces provide improved adhesion for other coating materials without the discoloration attendant alkali etching. The sputter-etching is also stated to be more effective than physical roughening or glow discharge to effect priming.
U.S. Pat. No. 3,018,189 shows the use of electrical discharges to modify the surface of a polymer to improve the adhesion of other materials to it.
The deposition of metal oxide coatings onto polymer surfaces to improve adhesion by a cathodic deposition from a solution of isopropanol and a nitrate salt is shown in U.S. Pat. No. 4,094,750.
U.S. Pat. No. 3,852,151 discloses the use of a discontinuous particle adhesion promoting layer of metal, glass, mineral or ceramic spherical particles having diamters of from 10 to 100 micrometers.
Chemical oxidation of polymer surfaces is also generally well known in the art as represented by U.S. Pat. Nos. 3,418,066 and 3,837,798.
The formation of metal-oxygen-polymer complexes at the surface of metal vapor coated, oxygen plasma treated polymeric materials has been noted as improving adhesion between the metal and the polymer (J. Vac. Sci. Technol., J. M. Burkstrand, 16(4) July/August 1979). The effects of improved adhesion by plasma treatment of polymer surfaces is well known in the art (J. Pol. Sci., `ESCA Study of Polymer Surfaces Treated by Plasma,` H. Yasuda et al., (1977) Vol. 15, pp. 991-1019), and (J. Affl. Phys., `Metal-polymer Interfaces`, J. M. Burkstrand, (1981) 52 (7), pp. 4795-4800).
Ion sputtering to texture polymeric and metal surfaces is another availale technique used to improve the adhesion to surfaces (NASA Technical Memoranda 79000 and 79004, Sovery and Mirtich et al., Technical paper present to 25th National Vacuum Symposium Nov. 28-Dec. 1, 1978).
Metal layers have also been sputtered onto electrophotographic films in a thickness of 0.7 to 4.0 mm in order to reduce visible light transmission as shown in U.K. Pat. No. 1,417,628.