Study On Coating Performance Of Ultra Short Phosphorus Gypsum Whiskers

In resent yeas,due to the rapid development of coating technology,equipment and pigment coated paper,the demands for high-quality pigments coated paper are ever-increasing.The texture of the coating pigments has a decisive role in the function of the coated paper,so the choice of the coating pigments is very important for the whole work.Many minerals can be used as coating pigments,such as clay,calcium carbonate,titanium dioxide and so on.Phosphorus gypsum whisker as a newly developed inorganic raw materials,were found to be widely used in various fields.But not much research is carried on its application in the paper as filler.It has broad prospects if it can further be used as paper coating pigment which not only can protect the natural mineral resources but also can utilize waste gypsum.In this paper,we conducted a preliminary research on the feasibility of gypsum whisker as coating pigments within the scope of the laboratory.Results showed that the diameter of the whiskers particle can meet the requirements of coating when the whiskers were grinded 2.5 hours in lapping machine under the speed of 2100 r/min.In addition,the most suitable grinding dispersant is sodium polycarboxylate and the most suitable addition is 0.6%(for dry phosphorus gypsum whisker)when the dispersion concentration of the phosphorus gypsum whisker is 40%.In the study of viscosity reduction,the most suitable lubricant is calcium stearate and urea aqueous solution,and the best effect of viscosity reduction can be achieved with the calcium stearate dosage of 6.0%,urea dosage of 6.0%,respectively.This paper also studied the effect of the type and dosage of adhesive on the properties of coated paper.The results showed that:the coated paper had poor strength and optical properties when using starch as adhesive.It had good strength properties and gloss when using carboxyl styrene-butadiene or styrene-acrylic latex as adhesive.With the increase of the carboxyl styrene-butadiene latex adhesive dosage,the gloss of the coated paper decreased,while the burst strength and tear strength of the coated paper were gradually increased.Besides the dosage of the adhesive has a little influence on the whiteness and opacity of the coated paper.The coated paper can reach the best performance when adding 12 parts of the adhesive in the coating.In this research,we studied the effect of kaolin on the properties of coated paper by replacing a part of phosphor gypsum whisker with kaolin in coating.It has been discovered that with the increase of the kaolin dosage the brightness and PPS of coated paper decreased while the gross,the tear strength and tensile strength of coated paper increased.In addition,the opacity,print gloss,dry nap strength and bursting of the coated paper was reduces after the first rising trend,although the change is not obvious.An excellent coating can be prepared with adding a small amount of Kaolin,a common used coating pigment,and some of its performance is better than phosphor gypsum whisker.It is worth noting that its amount should not be excessive,and the recommended amount should not exceed 20 parts.