| Titre : |
Promising coating applications : Uses of near infrared radiation for fast laser or LED activated coating processes |
| Type de document : |
texte imprimé |
| Auteurs : |
Christian Schmitz, Auteur ; Bernd Strehmel, Auteur |
| Année de publication : |
2019 |
| Article en page(s) : |
p. 42-47 |
| Note générale : |
Bibliogr. |
| Langues : |
Anglais (eng) |
| Catégories : |
Diodes électroluminescentes
lasers
Photochimie
Photoréticulation
Revêtements -- Séchage sous rayonnement infrarouge proche:Peinture -- Séchage sous infrarouge proche
|
| Index. décimale : |
667.9 Revêtements et enduits |
| Résumé : |
Near Infrared (NIR) radiation can be applied as a heat source for technical processes. In the coating industry this could be the thermal hardening of a liquid coating or being processed as a powder. These processes reduce the drying or curing time compared to oven heating due to faster heating of the surface without interacting with the substrate [2]. These techniques also prevent damage to heat-sensitive substrates. Another benefit is application to small areas by flexible use of the infrared light source (e.g. the hardening of automotive refinishes). Well known (near)-infrared light sources are black emitters with a broad emission range, which is varied by the temperature of the radiator. |
| Note de contenu : |
- Mechanistic background
- Our results
- Fig. 1 : Line-focus of the diode laser (red line) at 980 nm exposes a coating sample for thermal-induced curing (Photonic Baking) with a maximum length of 200 mm
- Fig. 2 : Curing mechanism for the thermally curable blocked polyisocyanate/OH-polyester and melamine formaldehyde/OH-polyacrylate coating systems for curing by heat transfer with NIR-LED or diode laser light sources
- Fig. 3 : General structure of the heptamethine cyanine absorbers used for the heat transfer of the NIR radiation
- Fig. 4 : Photophysical and photochemical reactions after excitation (a) of the heptamethine cyanine absorber. Deactivation by internal conversion (c) releases heat and fluorescence (b) as a light-emitting deactivation. The photochemical reaction (d) results in the generation of free radicals and calions with photoinduced electron transfer reaction as the first step
- Fig. 5 : Reaction pathways of the heptamethine cyanine absorbers after excitation with laser or LED NIR light. a) Heat transfer can be used for the induction of thermal processes. b) For photopolymerisation, free radicals and cations can be generated using diaryliodonium salis as initiator
- Fig. 6 : Interpenetrating networks being available from simultaneous Thermal-induced curing of the blocked polyisocyanate/OH-polyester or melamine formaldehyde OH-polyacrylate resin system and photopolymerisation of (meth-)acrylates or epoxides
- Fig. 7 : Structure of the monomers (Hisphenol-epoxy resin, TMPTMA, TPGOA) and initiators used for radical and cationic NIR
photopolymerisation. The interpenetrating nehworks were achieved by simultaneous curing reachion in combination with the resin systems in Fig. 2
- Table 1 : Structure and phohophysical properties of the heptamethine cyanine absorbers maximum wavelength of emission, ΦFluor : fluorescence quantum yield).
- Table 2 : Solubility of heptamethine cyanine absorbers in water and water/butyl glycol (80:20) |
| En ligne : |
https://drive.google.com/file/d/1Z19hUn9r-VKSBBGT5cmwvKwz55KoDeOT/view?usp=drive [...] |
| Format de la ressource électronique : |
Pdf |
| Permalink : |
https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=32795 |
in EUROPEAN COATINGS JOURNAL (ECJ) > N° 7-8 (07-08/2019) . - p. 42-47
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Promising coating applications in EUROPEAN COATINGS JOURNAL (ECJ), N° 7-8 (07-08/2019)
