5000 Turbo L5-2144cc 2.14L SOHC Turbo (WK) (1982)
Paint: All Technical Service Bulletins
Body Trim - Identifying/Painting Plastic Parts
Applies To
All
Group
5
Subject
Body Trim
Part Identifier N/A
Key Points
Identifying/painting plastic parts
Supercedes Product Circular, Group 50, No. 85-06
D
Number
86-03
September 30, 1986
Plastic Identification
Since many varieties of plastics are being used in the manufacture of Audi vehicles, it is important to identify the type of plastic to be painted (pg. 3).
Plastics are currently divided into two categories:
Thermoplastics and Thermosets.
Thermoplastics
PP - Polypropylene EPDM - Ethylene propylene diene-mixed polymerisate
TPE - Thermoplastic elastomer based on EDPM ABS - Acrylnitrile butadiene styrene PA - Polyamide (Nylon) PC - Polycarbonate PE - Polyethylene
PVC - Polyvinyl chloride PPO - Polyphenylene oxide (Noryl)
Thermosets
PUR - Polyurethane UP - Unsaturated polyester, better known as:
GFR-UP - Glassfiber reinforced unsaturated polyester
Painting of plastic parts
Untreated "raw" plastic pans may be painted for use on a vehicle only with special attention to the problems of paint adhesion, flexibility, color match
and service repair.
Successful painting of plastic pans is accomplished with the addition of two chemicals to the paint process:
1 - A bonding agent which is sprayed directly onto the untreated, "raw" parts (parts not primed or which have not been previously painted):
Part No. ALO 822 000 04 for EPDM Part No. ALO 822 200 10 for PUR/PC
2 - An elastic additive, Part No. ALZ 011 000, which is mixed with 2K unicolor acrylic paint.
CAUTION
Never add elastic additive to metallic base coats. The additive is to be combined with the 2K Acrylic Clear Lacquer on metallic paint applications.
The bonding agents will not adhere to PE and PP. These two thermoplastics are considered to be unpaintable.
No bonding agent is used when repainting plastic pads which have already been painted or parts supplied primed from the factory.
Depending on the type of plastic, the amount of elastic additive added to the spray coat varies from 30% for EPDM to 70% for PUR.
Increasing the quantity of elastic additive naturally reduces the covering capability which, in turn, leads to thicker coats. A thicker coat requires a longer
drying time.