A simple Raman technique to measure the degree of cure in UV curable coatings

“…The second derivative was used to minimize the effect of fluorescence and baseline slope. 11 This ratio was used to calculate the percent cure of the top and bottom of each clearcoat sample after set time intervals and to create a cure profile for each sample surface.…”

Section: Cure Monitoringmentioning

confidence: 99%

Epoxy thiol photolatent base clearcoats: curing and formulation

Seubert

Nichols

2010

J Coat Technol Res

View full text Add to dashboard Cite

Photolatent base crosslinked epoxy thiol coatings were characterized using transmission FTIR spectroscopy, Raman spectroscopy, UV spectroscopy, and Vickers micro-hardness testing. Curing rate constants were calculated for a series of formulations with varying concentrations of photolatent-DBN, ITX (2-isopropyl thioxanthone), and BP (benzophenone), as well as varying curing times. A design of experiments demonstrated that increased UV dose had the greatest impact on increasing the curing rate of the clearcoat system. BP wt% proved to have little impact on the clearcoat curing rate, while PL-DBN and ITX exhibited minimal improvement above 2.5 wt% and 1 wt%, respectively. Vickers micro-hardness results showed that irradiation dose had no impact on the final physical properties of the clearcoat. However, a 24-h ambient post-cure proved to increase the final hardness of the clearcoat under some conditions.

show abstract

“…The emission peaks at 1620 1 cm in the spectra of the liquid lacquer can be dedicated to the C=C double bonds of the monomers. 5 This band can be used as indicator for the acrylate group conversion. If this signal disappears, there are no more monomers in the lacquer and the polymerization is finished.…”

Section: Two Dimensional Datamentioning

confidence: 99%

Depth tracing the influence of oxygen on UV curing

Pieke

Heering

2007

SPIE Proceedings

View full text Add to dashboard Cite

The degree of cure of the coatings should be known for quality control and design of the curing system. Often the radiation part of the curing installation is oversized, because the spectral irradiances needed for a certain conversion of carbon double bonds were not determined beforehand. The usual testing methods for the quality of a coating, as for instance ATR spectroscopy, are only sensitive to the attributes of the surface. In our investigations, we measured the degree of conversion locally at different depths of the layer by means of confocal Raman spectroscopy with a spatial resolution of approximately 1µm. For the kinetic studies, we measured the change of Raman scattering of 532 nm Laser radiation. Which induces a transition on a vibration level of the carbon double bond corresponding to a wavenumber of 1620 cm −1 . The change was normalized with respect to the CH 2 deformation mode. Furthermore, we investigated the effect of different spectral distributions of radiation on the local conversion at different depths. By this it could be shown that most of the radiation power is needed to harden the surface. This is caused by the inhibiting effect of oxygen which hinders the generation of radicals. The measured depth profile of conversion reveals that oxygen is effective up to depths of 30 µm. The results of confocal Raman spectroscopy could also be used to optimize a curing system with inertization so that the radiation power could by reduced by 91%.

show abstract

A simple Raman technique to measure the degree of cure in UV curable coatings

Cited by 23 publications

References 6 publications

UV curable EA-Si hybrid coatings prepared by combination of radical and cationic photopolymerization

UV curable EA-Si hybrid coatings prepared by combination of radical and cationic photopolymerization

Epoxy thiol photolatent base clearcoats: curing and formulation

Depth tracing the influence of oxygen on UV curing

Contact Info

Product

Resources

About