Pintura de peças plásticas

501-36-50 Paint - General Information 501-36-50 DESCRIPTION AND OPERATION ‡ Degree of hardness - the higher-pitched the sound, the harder the plastic. ‡ Elasticity - the more muffled the sound, the higher the elasticity of the plastic. Cleaning plastic Plastic components are manufactured using complicated moulds and presses or other highly engineered tools, mostly using an injection moulding process or reactive injection moulding process. In order to be able to remove the component from a particular tool, a separating agent is used, which in some cases adheres very strongly to the plastic. This separating agent on the plastic components must be completely removed before any surface coating is applied. Warm storage (tempering) before actual cleaning brings the following advantages: ‡ The separating agent sweats out of the plastic. ‡ Tensions in the plastic are released. ‡ Air inclusions can be recognized and removed. Intensively clean the item several times using a pad and fresh cleaning agent. NOTE: A single wipe, even with cleaning agent, is not usually sufficient in most cases. Clean textured components with the aid of a soft brush. After cleaning, it is absolutely vital that cleaning agent absorbed by the plastic should be expelled by tempering again. If the ventilation is good and the room temperature is about 20°C the solvent can be evaporated away by overnight storage. Painting new components It is absolutely vital that the substrate of an unpainted new component is free of separating agent. Paint can only be applied directly to very few plastics. The plastic must first be identified exactly and then worked with a repair system which is matched to the type of plastic. In most cases a plastic etch primer must be applied as adhesion base to all plastics which can be painted. NOTE: Plastics have a tendency to become electrostatically charged. This can easily cause contamination during painting. Special antistatic cleaning cloths prevent electrostatic charging. Work process for thermoplastics: ‡ Thoroughly clean the surface. ‡ Temper the plastic. ‡ Afterwards clean with antistatic cleaner or antistatic cloths. ‡ Apply the bonding agent. ‡ Apply elastic filler. After it has dried, sand and clean. ‡ Apply one coat Uni-paint with elasticizer additive. For two layer painting the elasticizer additive is in the clear lacquer. NOTE: Follow the paint manufacturer's guidelines during all work. Work process for thermosets: ‡ As a rule, thermosets can be handled in the same way as normal body components. Work process for PUR soft foam: ‡ The work process is the same as for thermoplastic. ‡ Instead of using bonding agent, a filler wash is applied to close the pores of the PUR soft foam. The primer which has been applied to a primed new component can vary greatly. If no manufacturer's data is available, the composition and suitability for further working must be tested. Painted components with an already ascertained and intact paint coat present no problems for possible repainting. After sanding and careful cleaning with plastic cleaner or thinners, painting can be done directly. Unknown primer When dealing with unknown substrates it is important to carry out an adhesion test on the existing paint before any repainting is attempted. First of all a mechanical test must be carried out, for instance using a lattice cut and tear-off band. If the adhesion of the old paint is not acceptable, it must be mechanically removed and new paint finish applied. If the adhesion is acceptable, then an etch test is performed using 2-component thinners. If no etching can be detected in this test, application of the the paint finish can be started directly. Otherwise the old paint must be removed and a new paint finish created. With the help of universal or special plastic primers and with only a few materials complementary to those previously present anyway, the painter can now apply a long-lasting paint finish to all popular vehicle attachments made of plastic.