Study On Photodiscoloration Resistance Of Wooden Products Printed By Modified UV-curing Ink

This paper aims to improve the photodiscoloration resistance of wooden products printed by UV ink.The modifier?Nano-ZnO or Nano-TiO₂?was added to the red,yellow,and black UV inks by physical blending.The basic properties of the modified inks were tested.The effect of the type and the amount of modifier on UV ink were also analyzed.The modified UV inks were printed on wood to investigating the effect of the type and the amount of modifier on the photodiscoloration resistance of printed wood products.The optimum addition amount of two kinds of modifiers in three kinds of UV inks and the UV ink printed wood products with better photodiscoloration properties were obtained.By analyzing the surface changes and the changes of elements and functional groups of the printed wood products after aging,The mechanism of discoloration of wood products printed by UV inks was tentatively explored.The effect of the modifiers on improving the photodiscoloration resistance of wooden products printed by UV-curing ink was also explored.The main research results are as follows:?1?The addition of Nano-TiO₂ or Nano-ZnO has little effect on the basic properties of UV inks and its usage and can also improve the printing effect.After adding proper amount of modifier,the viscosity of the ink is decreased,the color density is increased,and the particle size changes little...The viscosity of the UV ink modified by Nano-TiO₂ or Nano-ZnO respectively reached the lowest when the added amount was 1.5% or 1.0%.The color density of the UV ink increased as the amount of modifier increased.When the amount of modifier was 2.0%,the color density was the lowest.The particle diameter of the ink slightly decreases with the increase of the amount of Nano-TiO₂.The addition of nano-ZnO has little effect on the particle diameter of the ink.When the amount of modifier was high,the stability of the modified UV ink would be reduced.The amount of Nano-TiO₂ on the inks was greater than1.5%,the storage stability time of the modified yellow and black ink drops significantly.When the amount of Nano-ZnO was 2.0%,both the modified yellow and black inks had storage stability of <60 days.?2?After the addition of Nano-TiO₂ or Nano-ZnO,the absorbance of UV ink in the ultraviolet region was enhanced,which has a positive effect on improving the photochromic resistance of the UV ink.After adding 2.0% Nano-TiO₂,the absorbance of the three color modified inks at 357 nm increased by 75.80%,16.50%,and 16.00% respectively,compared to the unmodified inks.After adding 1.5% Nano-ZnO,the absorbance of the three color modified ink at 357 nm increased by 75.80%,16.50%,and 16.00% respectively,compared to the unmodified ink.?3?The addition of Nano-oxides can improve the photodiscoloration resistance of red and yellow printed wooden products.After aging,the Gloss rate of wooden products was maintained at about 20%,and there was no significant difference between the colors.When the amount of Nano-TiO₂ addition was 1.0%,the color difference of aged wooden products printed by modified red or yellow ink was 80.69% and 31.25% lower than that of the unmodified inks respectively.When the amount of Nano-ZnO was 1.0%,the color difference of aged wooden products printed by modified red or yellow ink was 62.93% and 52.73% lower than that of the unmodified inks respectively.The photodiscoloration resistance of flooring products made by the two UV inks above were significantly better than unmodified UV ink printed.?4?UV inks can be printed well on the surface of wooden substrates in this process.After aging,the surface is basically flat and there is no deterioration such as shrinkage,bubbling and cracking.?5?After ageing,the content of C decreases,the content of O increases,and the content of N changes little.The content of C1 decreased,the contents of C2 and C4 increased,and the content of C3 did not change much.The addition of modifier attenuates the photooxidation of C1 to C2 or C4,and the effect of Nano-TiO₂ is better than that of Nano-ZnO.The results of infrared spectroscopy show that the absorption peaks of the secondary amide carbonyl group at1572 cm^-1 were obviously weakened.The characteristic absorption peak of primary amide at the 1630 cm^-1 appears.The characteristic peak absorption intensity of-CO is weakened.The characteristic peak of methylene does not change substantially.Comparing the change of functional group peak area of samples after ageing,it was found that the Nano-ZnO was betterin protecting the UV ink from the micro-phase separation of the molecular structure during the photo-aging process to generate a quinoid structure.