Preparation Of TiO₂/Inorganic Composites And Their Application In Papermaking Industry

In the papermaking industry,the heavy use of paper fillers has always been the goal pursued by people.Related studies have shown that the price of paper fillers is about 4 to 7 times lower than the price of pulp.The addition of fillers can reduce the amount of pulp used and the production costs.The fillers can improve papers'optical performance,printing performance and writing performance.TiO₂,wollastonite,kaolin and talcum powder are paper fillers widely used in the papermaking industry.Kaolin can enhance the smoothness,opacity and printing performance of the paper.It has excellent quality and low price.Therefore kaolin is suitable for various papers.Wollastonite can increase the whiteness of the paper and the retention of fillers.TiO₂can effectively enhance the whiteness,the hiding power and the gloss of paper.It is the most excellent filler in the papermaking industry.However,due to shortage of resources and high price,TiO₂ is only used in high-grade paper and special paper.Considering the effect of paper products and the cost of raw material,this paper proposes to prepare a binary composite.Using wollastonite or kaolin as the matrix and TiO₂ as the coating,the composite with similar properties to rutile TiO₂,namely TiO₂/wollastonite and TiO₂/kaolin,were prepared by airflow agitation method.As a result,the composite act as a filler could partly or completely substitute TiO₂ in papermaking industry.Firstly,the wollastonite slurry was well dispersed under mechanical agitation.The TiO₂/wollastonite was then prepared by depositing TiO₂ onto the surface of wollastonite during air agitation.The test results of FESEM,XRD,UV-vis,FT-IR,whiteness and acid resistance indicate that TiO₂ particles had been successfully deposited on the surface of wollastonite.Compared with other composites,TiO₂/wollastonite-20 has the best coating effect and dispersibility.The whiteness and ultraviolet absorption capacity of TiO₂/wollastonite-20 are similar to TiO₂.At the same time,the whiteness of the composites obtained by the blending method?a simple physical mixing of two substances?and the airflow stirring method were compared.The results showed that the whiteness of TiO₂/wollastonite was significantly higher than that of TiO₂-wollastonite when the addition amount of TiO₂ was the same.Secondly,the kaolin slurrry was dispersed under the alkaline condition and mechanical agitation in order to obtain a matte surface of kaolin.Then the TiO₂ was deposited on the kaolin to form the TiO₂/kaolin composite during the air agitation.The results of FESEM,XRD,UV-vis,FT-IR and whiteness show that kaolin had been successfully coated by TiO₂ particles.Compared with other composites,TiO₂/kaolin-15 has the best coating effect and dispersibility.At the same time,the whiteness of the composites obtained by the blending method?TiO₂-kaolin?and the airflow stirring method were compared.The results showed that the whiteness of TiO₂/kaolin was significantly higher than that of TiO₂-kaolin when the addition amount of TiO₂ was the same.Finally,TiO₂/wollastonite,TiO₂/kaolin,TiO₂-wollastonite,TiO₂-kaolin were used as paper fillers instead of TiO₂ in the papermaking industry.The properties of paper products were characterized by whiteness,tearing degree,hiding power and filler retention.The results show that when TiO₂/wollastonite and TiO₂/kaolin were applied in paper products,the whiteness and the hiding power of the paper products were significantly improved.Some properties are even better than those made of TiO₂ as filler.When the amount of TiO₂ added in the composite was the same,the properties of the paper obtained by TiO₂/wollastonite or TiO₂/kaolin are obviously superior to those of the paper obtained by TiO₂-wollastonite or TiO₂-kaolin.Therefore,TiO₂ may be partially or completely replaced by TiO₂/wollastonite or TiO₂/kaolin in the papermaking industry.