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Views: 0 Author: Site Editor Publish Time: 2021-02-05 Origin: Site
White card has been so popular to be applied in paper boxes and paper bags. We can so easily spot cosmetic boxes, cookie boxes, jewelry boxes, shopping bags and gift packaging bags in white card. The white card enjoys its vast availability and good printability among the paper materials.
Although the white card enjoys its popularity for so many advantages, there is still one thing that we should care about. It is easy to turn yellowish too. Why is the white card so easy to turn yellowish, and what should we do to prevent this issue?
Firstly, we should know how the yellowish happens. After the paper material storage and sunshine radiation, its surface material gets oxidized. And the deeper the oxidation is, the yellowish the white card could be. And there are 3 factors that could contribute to the oxidation, high temperature, the ultraviolet light and PH value.
Besides, the property of the white card paper itself, fluorescent brightener, color matching pigment, and coating adhesives could also affect how yellowish it could be.
Secondly, here are some suggestion of the precautions and solutions for yellowish white cards based on above knowledge of the reason and factors for yellowish issue.
Bleached chemical wood pulp should be used in the original paper material. And the amount of the top pulp should be increased. And the PH value of the based paper surface should be between 6.5 ~ 8.0.
Quality liquid brightener can help prevent the yellowish issue too. And suitable color matching pigment helps to improve the whiteness and reduce the amount of the whitening agent. And suitable proportion of coating adhesive should be adopted to make sure of the strength of the coated white card and to prevent it turning yellowish.
And others factors should be taken into consideration to prevent the yellowish issue as well, for example the PH value of the coating pigment, the purification of the coating water, the liquid content of the coating board, and its packaging and storage.
