1. Stability of processing
2. Baking temperature on the physical matting of gloss also has a relatively large impact
3. Compatibility issues, the
4. Storage stability problems
5. Poor leveling of some products in the black system
The impact of the processing process on the gloss and surface, extrusion conditions on the impact of gloss is currently the most important problem of matting agents, some varieties will also have an impact on the leveling.
Physical matting and 68 series of powder compatibility is not very good or even have a strong repulsive, which is determined by their different curing mechanism, which is why physical matting can not completely replace the 68 series of one of the reasons, but this compatibility problem has been a more compromise solution, although not completely reach the ideal state
Physical matting agent storage stability is still a problem, specifically in powder storage after a period of time (especially high temperature weather) will occur after the gloss or leveling deterioration phenomenon.
The matting agent based on multi-stage reaction mechanism is a polyfunctional cyclic alkyl carboxylic acid for epoxy and hybrid matting. This product can obtain 0-50% matting effect. The high functional group leads to uneven crosslinking density throughout the coating film, and the properties of the alicyclic group also determine a poor miscibility with polyesters and epoxies containing aromatic groups. Aliphatic carboxylic acids have a slower reaction rate than aromatic carboxylic acids. Therefore, ptfe wax yellow, the film is already partially cross-linked at the time of reaction, resulting in shrinkage of the film due to the blocking effect.
Further study revealed that the gloss and curing conditions were not well related. Therefore it can be inferred that incompatibility and immiscibility are more important than the reactivity of the process.
In the epoxy and mixed system can get <5% matting effect, and will not produce yellowing phenomenon. Only the low reactivity requires a special catalyst to start the reaction. Therefore, in order to obtain good matting effect, correct formulation adjustment and suitable catalyst selection are very important.
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