Pintura de peças plásticas

501-36-51 Paint - General Information 501-36-51 DESCRIPTION AND OPERATION Paint faults on plastic substrates NOTE: Paint faults are fully described in the chapter Paint Defects and Damage. The most common paint faults which can occur when painting plastic components and the methods of repair are briefly described. Discoloration Cause/damage pattern: ‡ Plastic material is not suitable for painting. ‡ Incorrect bonding agent. ‡ Paint used not solvent resistant. Repair of damage: ‡ Repaint using suitable materials. ‡ Install a new unpainted component. Softening Cause/damage pattern: ‡ Substrate not carefully cleaned. ‡ Air humidity too high or working temperature too low. ‡ Drying time incorrect (too short). ‡ Materials for substrate not correctly matched to each other or not mixed correctly. Repair of damage: ‡ Dry out, sand, re-isolate and paint. ‡ Sand away faulty paint coats and re-apply paint finish. Paint damage caused by detachment, poor adhesion Cause/damage pattern: ‡ Insufficient paint adhesion between top coat and filler. The whole of the paint finish detaches from the plastic. ‡ Plastic not cleaned sufficiently, not or inadequately tempered. ‡ Unsuitable cleaning agent or materials used. ‡ Poor or lack of intermediate sanding. ‡ Paint finish underbaked or overbaked. Repair of damage: ‡ Sand away faulty paint coats and re-apply paint finish. Paint damage caused by blisters, craters, sink holes Cause/damage pattern: ‡ Painting on PUR plastic which was not painted in production. ‡ Surface of the plastic material too porous. ‡ Flash-off time not adhered to. ‡ Drying temperature too high. ‡ Moisture in plastic material. ‡ Layers too thick. Repair of damage: ‡ Clean the damaged area, sand, re-isolate and paint. ‡ Remove the paint layers and re-paint. Crack formation Cause/damage pattern: ‡ Overexpansion of painted PUR plastic components. ‡ Use of unsuitable paint materials. ‡ Paint materials not suited to each other or incorrect mixture ratio. Repair of damage: ‡ It is not possible to repair overexpanded PUR plastic components. ‡ On other plastics, sand away damaged layers, isolate and repaint.