Painting trends for plastic parts

For plastic parts, painting is more than just a protective skin: it provides the product with optical and haptic characteristics which decisively influence the customer’s perception and buying decision as well. Due to the fact that painting is also one of the most energy-intensive processes in the manufacturing sequence, costs have to be kept under control. As a consequence, the painting technologies industry is working on solutions which promote efficient use of resources while simultaneously optimising quality.

Whether the automotive industry, household appliances, consumer electronics, the cosmetics industry or toys are concerned, painting plastic parts is becoming more and more common. Optimisation of the qualitative characteristics is one of the challenges in this respect. On the one hand, this involves improving functional characteristics such as durability and resistance to physical, chemical and mechanical influences. On the other hand, emphasis is also placed upon improved optics and haptics which serve the purpose of, amongst other things, individualisation.

Resource-conserving pre-treatment

Surface cleanliness has a decisive influence on painting results. In order to conduct cleaning as efficiently as possible, more and more companies are making use of alternatives to conventional power washing systems. Amongst others, these include CO2 snow blasting and plasma technology. Particulates as well as film-like contamination can be removed with the help of CO2 snow. Plasma cleaning, using low pressure plasmas and plasmas at atmospheric pressure, is above all suitable for removing thin layers of organic contamination. Both processes allow for dry cleaning and can be integrated into the painting process in a space-saving fashion.

Pre-treatment, for example by means of a flaming process, is necessary in order to avoid adhesion problems due to excessively low surface tension, for example in the case of non-polar plastics. This involves briefly exposing the plastic surface to a gas flame with excess oxygen. As a result, molecular bonds in the surface of the substrate are broken down and free, active ions in the flame are integrated. Consequently, polar groups occur within the originally non-polar material which allow for good paint adhesion. Corona treatment can be used as an alternative. It’s conducted with an alternating voltage electrode by means of which atmospheric oxygen is ionised with the help of corona discharge, resulting in oxidation of the plastic surface.

Simpler processes for perfect surfaces

Reducing the number of steps required in the painting process makes a significant contribution to increased efficiency. In addition to reduced energy consumption, this also results in less material usage, lower emissions and a smaller footprint for the painting system. Consequently, the trend is moving towards painting processes which provide the desired results with just a single coat. Painting systems for lean processes of this sort are available with solvent as well as water-based paints. Use of these systems necessitates corresponding preparation during production of the respective parts – for example assurance of flawless, glossy surfaces. If this challenge is met successfully, it’s even possible to omit pre-treatment in some cases.

Solvent-based paints are still widely used for coating plastics. Very-high and ultra-high-solid paints are available in order to further reduce the emissions whicAir Jordan 12 Low