Fabrication of a Multilayer Article with Conductive Outer Layer for Improved Paint Transfer
Publication Date: 2005-Jan-14
The IP.com Prior Art Database
Disclosed is an improved method to paint plastic parts, specifically electrostatic painting of a multilayer thermoplastic art comprising a thin outer conductive layer
Improved Paint Transfer
In many applications, plastic parts need to be painted. Especially plastic parts such as information technology equipment housings and automotive plastic parts, especially exterior parts require painting. The process of painting can add enormously to the cost of the part primarily because of inefficient transfer of paint from the gun to the part surface. The problem is especially compounded by low energy substrates. This invention addresses the problem by providing a conductive functionality to a thermoplastic polymer, such as a polycarbonate based polymer, with the resulting material being sufficiently conductive to dramatically improve paint transfer efficiencies. However, in the process of providing the conductive functionality one often sacrifices impact performance and /or ease of processability with respect to part fabrication.
It was discovered as part of this work that coinjection, coextrusion or multilayer blow molding enabled placement of a relatively expensive, thin layer of a polycarbonate based blend with the conductive functionality on the outside layer and a relatively thick and less expensive polycarbonate based blend on the inside. This construct provided conductive PC based blend on the surface of the part where it was needed while retaining the balance of stiffness and toughness with the thick layer on the inside. Painting studies indicated excellent transfer efficiencies as demonstrated by the degree of paint ‘wrap around’. The coextrusion substrate can further be fabricated into final parts by such methods as thermoforming, and sheet and profile extrusion. ...