Research On The Factors Influencing The Brightness Stability Of Coating

As high quality print paper coated paper, the coated paper can not only adapt each kind ofrequirements of the advanced press, but also to have brightly color, clear, natureafter printing,and the price must be moderate, with high performance to price ratio. Asians have highrequirement on the whiteness of the paper,so it's very important to improve the brightness.There are a number of factors influencing brightness of coated paper and brightness stability,coating is one of the most important factors.From the coating process, this paper researched on effects of Optical Brightening Agent,Optical Brightening Agent carrier,dye,pigments on brightness and stability of brightness.And discussed the impaction of brightness on the color reproduction of print. This paperanalyzed the key factor of effect on brightness and brightness stability, and then get the bestcoatings formulation, for improving the quality of coated paper and performance of print.Theresearch shows that:1,Cobinder can increase the CIE brightness of coated paper. The effect of PVA are betterthan CMC and PEG. All of these threecarriers could improve the hue of the coated paper,reduce chromatic index b~*value, increase the L~*value; but it may reduce increase of the colorindex a~*value, and then turn the color of paper to red.2,When dye was used with OBA, the CIE brightness could be high,there do havesynergistic effect between these two things.Therefore, the amount of OBA could be less.Meanwhile, the L~*value and b~*value was reduced, so the amount of dye could not be verymuch, experiments using blue dye0.002%, purple dyes for0.008%.3,With the increased proportion of calcium carbonate pigment, whiteness, brightnessstability of coated paper, ink absorption and surface strength is significantly enhanced,soputcalcium carbonateinto the coating,can improve the brightness of coated paper. Then it canbe judged that,to get the same ink absorption value and the same surface strength, the amountof adhesive could be reduced. PCC's positive effect on brightness stability of the paper wasbetter than GCC.4,OBA changed the hue of paper and local spectrum reflection rate. This method of localimprove reflection rate has effected on print process under the color management. Blow440nm,spectrum reflection rate became lower after corrected. Because of this, the print wasinfluenced.During the copy, the regional color began turning to yellow when the coated paperhas OBA in it. While at the same level,the effects of copy was most clear on light tone,middle tone followed by, and the dark tone was the last one.