GMNA-9984160-1990.pdf

m 7006379 0000387 350 I GENERAL MOTORS ENGINEERING STANDARDS I Materials and Processes - Paint COATING, SPRAYABLE MASKING 9984160 1 SCOPE. This specification covers the requirements for sprayable coating materials which mask the substrate from subsequent applied coatings. It is generally intended that portions of the coating will be removed prior to topcoating to provide two-tone or accent effects. For this purpose, the mask coating must trim easily without lifting and have sufficient tensile strength to be removed without tearing. The coating must not harm the substrate or previously applied coatings in any way, and in areas where the coating has been removed, there shall be no affect on the appearance, adhesion or durability of the subsequently applied topcoat. In areas where the masking material is subsequently coated, there shall be no affect on the cure of the topcoat, which would result in tackiness or other effects detrimental to the process. These mask coatings are waterborne for reduced solvent emissions. 2 REFERENCED STANDARDS. GM950SP ASTM2697 ASTM D147S ASTM D3960 ASTM 02 196 ASTM D4212 ASTM D2369B ASTM E70 3 REQUIREMENTS. Documentation covering all mate- rial properties and performance test results must be supplied in a form acceptable to the General Motors Engineering activity to which submission is made. Any significant change made to the material components or manufacturing process must be assessed to determine if requalification is required. 3.1 Material Requirements. The following requirements are for the masking material before application and drying: 3.1.1 Identification. All materials must have complete iden- tification by product code and manufactunng batch. All required safety/hygiene information per 5.1 must be fur- nished. Specific parameters required are: 3.1.1.1 Physical Constants. Mass (ASTM D2369) and vol- ume (ASTM D2697) percent solids, VOC (ASTM D3960) and density (ASTM D147S). 3.1.1.2 Viscosity. Newtonian materials (ASTM D4212). For non-Newtcnian matenals use Brookfield (ASTM D2196i. or equivalent. 3.1.1.3 pH (ASTM E70). 3.1.1.4 Odor. The matenal s odor shall be reviewed in comparison with current production materials, when evaluat- ed in laboratory and production tnals. Any changes in formulation must be reassessed for effect on odor. 3.1.1 .S Solvent Emissions Compliance. All coating materials must meet specific plant solvent emissions restrictions. Any change m formulation which affects VOC content or applica- tion tn-insfer efficiency must be evaluated for effect on compliance before production use. 3.2 Performance Requirements. The following requirements apply to the dry masking film, its ability to perform the intended masking function, and its effect on previous and subsequently applied coatings. Panel should be prepared using the intended substrate and primer(s), if applicable. Spray the masking material to a wet film build sufftcient to yield the specified dry film thickness. Allow to air dry or force dry per supplier recommendation. Prior to test, cut and remove one half of the masking material from test panel. Qualification of a masking material to these requirements allows its use only in the tested combination of substrate, primer and topcoat. Use in other combinations requires retesting to the applicable performance requirements. 3.2.1 Appearance. The film shall be smooth and uniform, free of voids or other defects detrimental to its masking function. Color shall be per agreed Standard. 3.2.2 Film Thickness (ASTM D1186). Range 75 to 125 pm. All performance and processability requirements must be met within entire film build range. 3.2.3 Adhesion. The coating must have sufficient adhesion to allow cutting and removal of portions of the film without lifting the remaining film. Tensile strength and elongation shall be sufficient to allow easy removal without tearing, both before and after topcoating. 3.2.4 Effect On Substrate Prior To Topcoating. The masking material must have no effects on the substrate or prior coatings which impact performance or paintability. After the simulated aging tests below, the film must be cleanly removable from the substrate, leaving no residue or contami- nation which would afTect the appearance or durability of the subsequently applied topcoat. There shall be no lifting or other effect on the cut edge which would detract from the masking function. 3.2.4.1 Heat age 168 h at 80 C. 3.2.4.2 Cycle Test (GM9SOSP. Cycle E). One week cycle. 3.2.5 Effect On Substrate After Topcoating. After topcoat- mg, the film and topcoat shall be easily removable, without leaving any residue, and there shall be no softening or other deletenous effect upon the underlying substrate and coatings. The masking material must not affect the cure of topcoat such that topcoat remains tacky. Topcoat shall be applied to masked panels (1) as is, immediately after application, (2) after heat aging per 3.2.4.1 and (3) after cycle test per 3.2.4.2. The topcoat shall be baked at the upper limit of its bake range ior twice the nommal bake time. 3.2.6 Effect On Topcoat Performance. The masking material shall have no effect on the substrate or previously applied coatings, such that after removal and topcoating, the topcoat meets all of its specified durability requirements. Topcoat testing shall consist of a minimum of adhesion after humidity and environmental cycle testing per applicable topcoat sped- MARCH 1990 PAGE 1 9984160 Copyright General Motors North America Provided by IHS under license with GM Licensee=IHS Employees/1111111001, User=Japan, IHS Not for Resale, 06/23/2008 19:45:28 MDTNo reproduction or networking permitted without license from IHS -,-,- m 9006377 0000388 297 I I GENERAL MOTORS ENGINEERING STANDARDS I Materials and Processes - Paint COATING, SPRAYABLE MASKING 9984160 fication. There shall be no effect on the topcoat, such as cure inhibition, at cut edges. department or laboratory), or equivalent, must be submitted with any new submissions or where a composition change has OCCUlTed. 3.3 Processability Requirements. These masking materials are intended to be applied by airless spray. Although capable of air drying, a nominal bake of 30 minutes a 70 to 90 C is used to achieve handling properties. The masking material must have st&cient tensile and tear strength to allow removal from warm parts without tearing. Complete guidelines for the processing of these materials may be found in surface coating process specifications issued by GM engineering groups. 4 SOURCE SHIPMENT RESPONSIBILITY. It will be the responsibility of the supplier to insure that the material is not exposed to temperatures during shipment which would cause the material to fail to meet any of the requirements of this specification. 6 INSPECTION AND REJECTION. All shipments of material or parts under contract or purchase order manufac- tured to this specification shall be equivalent in every respect to the initial samples approved by engineering. There shall be no changes in either formulation or manufacturing processes permitted without prior notification and approval by engi- neering. Lack of notification by the supplier constitutes grounds for rejection of any shipment. While samples may be taken from incoming shipments and checked for conformance to this specification, the supplier shail accept the responsibili- ty for incoming shipments meeting this specification without dependence upon purchaser s inspection. 5 INlTlAL SOURCE APPROVAL No shipment shall be made by any supplier until representative initial production samples have been approved by engineering as meeting the requirements of this specification. 7 APPROVED SOURCES. Engineering qualification of an approved source is required for this specification. Only sources listed in the GM Corporate Materials File under this specification number have been qualified by engineering as meeting the requirements of this specification. 5.1 Completed copies of the GM Material Safety Data Sheet 8 GENERAL INFORMATION. This specification was and Critical Material Register (available from the engmeering issued in March 1990, approved by the Paint-Committee. 9984160 PAGE 2 MARCH 1990 Copyright General Motors North America Provided by IHS under license with GM Licensee=IHS Employees/1111111001, User=Japan, IHS Not for Resale, 06/23/2008 19:45:28 MDTNo reproduction or networking permitted without license from IHS -,-,-