Urethane-Acrylate 3D-Printed Products With Lightfast Red Dyes

The patent applies parameter changes by selecting dyes with specific chemical structures (perinone, xanthene, oxazine, thiazine, cyanine, carbazole, indigo, anthraquinone, azo, anthracene, phenoxazine, phenothiazine, indoline, isoindoline, pyridine, triarylmethane, flavone, curcumin, thioflavine, thioxanthene, fluorescein, rhodamine, eriochrome, chlorophyll, carotenoid, betalain, quinacridone, disperse blue 194, or disperse blue 147) that inherently resist photodegradation. This chemical parameter selection ensures the dye molecules maintain their coloristic properties throughout the photopolymerization process and subsequent light exposure, resolving the contradiction between enabling curing and maintaining color stability.

The patent specifies precise concentration parameters for the selected dyes within the photopolymerizable composition, ensuring that the color strength and hue remain consistent throughout the printing process. By controlling the dye concentration and selecting dyes with high molar absorptivity in the visible range, the invention maintains manufacturing precision of color properties while enabling complete printing process execution.

The patent converts the potentially harmful effect of light exposure into a beneficial outcome by selecting dyes whose absorption spectra are optimized for the photopolymerization wavelength range. The dyes absorb the curing light efficiently without undergoing degradation, and in some cases, the dye molecules may even enhance the curing process by extending the absorption spectrum of the photoinitiator system. This approach allows simultaneous achievement of complete resin curing and colorant stability.