Method for forming graded shade band on substrate

摘要

Forming a colored shade band on an elongated area of a flexible sheet of interlayer material comprising applying a dye composition by electrostatic spraying against a portion of a surface of a flexible sheet of non-conductive interlayer material such as polyurethane or plasticized polyvinyl butyral. A novel grounded shielding structure of electroconductive material comprises a primary shield located in close proximity to the upper surface of a workpiece to be partially coated. A preferred embodiment comprises primary and secondary shields with an optional manifold between the shields to ensure superior control of a pattern of graded intensity along the transverse dimension of an elongated area to be coated. One or both shields may be heated to avoid the deposit of spray particles that cause optical defects. The workpiece so coated is useful as an interlayer in shaded, bent laminated safety glass windshields.