Fluropolymers like Polyvinylidene Fluoride (PVDF) have a real edge as a coating material that helps in protecting the ACP surfaces from external adversities.
Acrylic resin is one of the common ingredients found in commercial PVDF coating formulations. Particular acrylic resins are thermodynamically miscible with PVDF, and the acrylic properties complement the highly inert PVDF resin… The complicated microscopic phase structure formed in PVDF coating and the combination of crystalline and amorphous phases give PVDF coatings excellent properties like flexibility in combination with solvent resistance.
The excellence of coating performance rests on the ratio of acrylic resins and PVDF in the formulation. The performance graph is directly proportional to the percentage of PVDF because the PVDF crystallites reinforce mechanical properties in the coating. So, a lower percentage of PVDF resin in the formulation will result in a worse performance of the PVDF paint. For, e.g. in the methyl ethyl ketone (MEK) test 50% PVDF coating will have lower performance compared with 70-80% PVDF resin-based coating. The 70:30-ratio of PVDF and acrylic resins give the best results vis-à-vis elongation as well.
The chemical and photochemical inertness of PVDF resins are attributed to the stability of the C-F bonding. On the contrary, the presence of ester and other such functional groups result in more photochemical degradation and other degradation processes like hydrolysis in case of acrylic resins. So, weatherability is one such property that gets decided by the PVDF and acrylic ratio. It has been proved time and again that the mix containing lower levels of PVDF fails to retain the gloss than that with a 70:30 ratio PVDF which is primarily due to the photochemical degradation of the cross-linkage aspect of the acrylic resins. The excellent weatherability feature is well explained by the fact that PVDF resins are highly fluorinated and more inert in PVDF coating.
The high probability of gloss and colour retention with higher levels of PVDF in a coating substance is evident from the table alongside which showcases the data for blue masstone after 20 years of exposure to humid weather conditions in Florida.
The 70:30 ratios of PVDF and acrylic resins for topcoats is a time-tested way to conform to AAMA 2605, the most stringent norm for coating specifications. Thus, to guarantee quality assurance, the KYNAR 500 PVDF grade resin is sold under a licensed agreement which requires that coatings claimed to be KYNAR 500 must contain a minimum of 70 wt% PVDF in the polymer binder.
The licensed agreement for KYNAR 500 also stipulates that the PVDF paint ought to be made of 70:30 ratios of PVDF & ACRYLIC resin, making it highly weather resistant.
Specifying KYNAR 500 coatings, Architects and Specifiers can minimise the risk of getting anything apart from the optimal paint formulation. The loss incurred from paint failure can be huge, not just monetary but also reputational for a contractor or a builder.
Aludecor, having an in-house Coil Coating facility, strictly abides by the international standard of 70:30 ratios of PVDF and acrylic resins, adhering to AAMA 2605 specifications.
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