Efficient matting of UV-coatings

It can be difficult to obtain matt finishes with 100% solids UV curable coatings. A recent article describes different matting agents and explains what other formulation variables are important.

3D surface imaging based on microscopic image of an excimer cured coating. Red areas are hills -

The main article of the latest issue of the European Coatings Journal describes the difficulty of achieving matt 100 % solids UV-coatings. For example, consumer products are exposed to repeated wear and contaminants throughout their life cycle, soft-feel coatings must be highly durable. However, balancing soft feel with wear resistance is a great challenge. Also the abundance of film shrinkage is an obstacle in achieving a good matting effect.

The authors tested various combinations of silica matting agents and UV reactive diluents and studies their rheology and appearance. The test showed a high variation of results, depending on silica type and diluents.

Additionally, the authors studied ultrafine polyamide powders which showed high efficiency matting and had less effect on the rheology than the silicas.  As a third option excimer pre-curing was investigated. This technology is used in many industrial sectors and applications. Excimer stands for “excited dimer”, in other words a dimer (e.g. Xe-Xe-, Kr-Cl gas) which is excited to a higher energy state following application of an alternating voltage. Because these “excited dimers” are unstable they disintegrate within a few nanoseconds, converting their excitation energy to optical radiation. This technology showed good results, however only in certain cases.

On May 29, Xavier Drujon, the author of the article will explain the study and results during our monthly webcast European Coatings Live. Attending the webcast is completely free of charge.

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