Description / Abstract:
This specification covers the requirements of a twocomponent
(2K) urethane monocoat used on chrome plate, exterior vehicle
applications. These requirements cover part performance and general
process methods for ensuring long-term integrity of the coating
system.
Material Description. The paint is a 2K
urethane monocoat used over chrome-plated, exterior vehicle
applications. This specification is in reference to 2K urethane
monocoat paints that are pigmented. It does not pertain to paints
where the intent is to clearcoat or tint. These paints are designed
specifically for obtaining excellent adhesion and weatherability to
chrome-plated surfaces. All qualified paint systems used for this
application shall meet GMW3005 generic topcoat performance
requirements. In addition, supplemental test requirements listed in
Table A1 are required. Paint systems that meet these requirements
can utilize a primer or be single-coat applications. This
specification does not apply to paint systems designed to be
applied over resist coats. Although these paints can be applied
over resist coats, 9984255 covers resist and topcoat applications
specifically. Any paint in contact with chrome shall meet the
requirements of this specification. This also applies to parts with
a combination of resist coating and paint on chrome.
Although primarily intended for use on chrome-plated plastics,
this 2K urethane monocoat paint may be qualified for use on other
substrates, such as metal. The final surface must be
chromiumplated.
These coatings are part of a total painted product system and
must meet the requirements set forth in this specification and
those shown on engineering drawings. Approved Paint on Parts
Specification (APOPS) GMW14797 is required. APOPS requirements are
specific to any given combination of plastic substrates, chrome
finish, physical plating line and physical painting line. APOPS
submissions shall also include supplemental testing listed in Table
A1.
Symbols. Not applicable.
Typical Applications. Typical applications are
grille black-out areas and emblems. Paint on chrome is generally
used for cost savings when compared to resist and topcoat. In other
cases, a two-part component construction may be used with one piece
being chrome-plated and the other molded in color or painted part.
Less masking, multiple components, and more than one pass of paint
can be avoided with paint over chrome. Some durability may require
compromise. For example, resist and topcoat painting will provide
better hiding of small metal chips of the chrome below the paint
surface. Trace appearances of chrome through the paint can occur if
the part is impacted by stones or other objects. The use of paint
on chrome compared to resist and topcoat should be evaluated prior
to design release.