Abstract The use of polygraphic varnishes in the packaging production process is common today. Free-radical polygraphic varnishes are most commonly used. The economic aspects of polygraphic industry have recently attracted academic and commercial attention to the possibility of replacing the classical UV lamps by the LED lamps in the curing process of polygraphic varnish layers. The paper compares some physicochemical properties of polyacrylate varnish layers cured by the classical UV lamp and the LED lamp emitting 395 nm. The model varnish containing ethyl (2,4,6-trimethylbenzoyl) phenylphosphinate (TPO-L) as photoinitiator was used in reported experiments. The presented data prove that polygraphic layers cured by the LED lamp: – are less cross-linked (more in the upper and less in the bottom part of the layer) – have a rougher surface, and – emit greater amount of unreacted photoinitiator than those cured by the classical UV lamp, despite the application of the same UV doses in the curing process. These conclusions concern all the packaging materials employed in the experiments: aluminum and polyethylene foils and paper. Greater cross-linking of the varnish layers cured by the classical UV lamps probably results from the presence of high-energy short wavelength in their spectrum which induces more effectively the formation of radicals from TPO-L than 395 nm wavelength of the LED lamps.

中文翻译：

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由经典和 LED (395 nm) 紫外线光源固化的聚丙烯酸酯清漆层的一些物理化学特性

摘要 如今，在包装生产过程中使用多图清漆很常见。自由基多图清漆是最常用的。印刷行业的经济方面最近引起了学术和商业的关注，即在印刷清漆层的固化过程中用 LED 灯代替传统紫外线灯的可能性。该论文比较了由经典 UV 灯和发射 395 nm 的 LED 灯固化的聚丙烯酸酯清漆层的一些物理化学特性。在报告的实验中使用了含有（2,4,6-三甲基苯甲酰基）苯基次膦酸乙酯（TPO-L）作为光引发剂的模型清漆。所提供的数据证明，由 LED 灯固化的多图形层： – 交联较少（层的上部较多，底部较少） – 具有更粗糙的表面，- 尽管在固化过程中应用了相同的紫外线剂量，但比传统紫外线灯固化的光引发剂释放出更多的未反应光引发剂。这些结论涉及实验中使用的所有包装材料：铝箔和聚乙烯箔以及纸。由经典 UV 灯固化的清漆层的更大交联可能是由于其光谱中存在高能短波长，与 LED 灯的 395 nm 波长相比，TPO-L 更有效地诱导自由基的形成。