Preparation Of Composite Titanium Dioxide And Its Application In Decorative Base Paper

Decorative base paper was the basic material for producing decorative panels.With the diversified requirements of decoration style,the quality of decorative base paper needed to be improved.The main raw materials for decorative base paper were titanium dioxide（TiO₂）and high-quality pulp,which required excellent optical properties.However,the cost of TiO₂ was high,averaging between 15000 and 25000yuan/ton.In this paper,inexpensive inorganic minerals were selected as the matrix,and a layer of TiO₂ was coated on its surface by mechanical grinding method,chemical precipitation method and emulsion method to prepare composite filler,so as to replace TiO₂ filling in decorative base paper and reduce the production cost.The composite filler was prepared by mechanical grinding method.Composite fillers made of TiO₂ and kaolin,talc,heavy calcium carbonate（GCC）,wollastonite was respectively added to the decorative base paper.It was found that the best was talc used as the core.The pregrinding process of talc powder was studied by a single factor test.The results showed that the average particle size of talc was about 1μm when the grinding time was 100 min,the medium ratio was 1:8.5 and the grinding concentration was 40%,which was favorable for coating.Then,the preparation conditions of TiO₂/talc composite filler were optimized by orthogonal experiment.The results indicated that 5:5 of talc and TiO₂ mixing ratio,60%of grinding concentration,50 min of composite grinding time and 1:10 of medium ratio were best conditions.And the opacity and whiteness of the base paper were 97.9%and 86.4%ISO,respectively.In addition,the composite filler was characterized by scanning electron microscopy（SEM）and Fourier transform infrared spectroscopy（FT-IR）.The results suggested that the talc was coated with a dense and uniform layer of TiO₂,which was connected by Ti-O-Si bonds.TiO₂/talc composite filler was prepared by chemical precipitation method.The preparation process of composite filler was optimized through a single factor experiment.The optimum condition was suspension concentration 5%,hydrolysis temperature 80℃,p H=1.7,aging time 3 h,titanium sulfate solution concentration0.25 mol/L,drop acceleration 3 m L/min,and calcination temperature 800℃.The composite filler obtained under this condition was added to the decorative base paper,and the opacity and whiteness of base paper were 97.3%and 84.5%ISO,respectively.The composite fillers were characterized by SEM,X-ray spectrometer（EDS）,X-ray diffraction（XRD）,Ultraviolet-visible spectral analysis（UV-Vis）and FT-IR.The results showed that Zn（NO₃）₂ promoted the crystal type conversion,so that TiO₂deposited on talc surface was rutile type,and the two were connected by Ti-O-Si.TiO₂/talc composite filler was prepared by emulsion method,and its preparation process was optimized by combining the pseudo-ternary phase diagram and response surface method of W/O emulsion.It was found that cyclohexane was more suitable for oil phase than n-heptane,and the amount of n-butanol affected the stability of emulsion.The optimum preparation process of the composite filler was Tween80/n-butanol=1:1（ω/ω）,emulsifier/cyclohexane=4:6（ω/ω）,water/cyclohexane=1:3（ω/ω）,talc/tetrabutyltitanate（TBT）=1:4（ω/ω）,resulting in an opacity of 97.0%and a whiteness of 84.0%ISO for decorative base paper.The composite filler was characterized by the methods such as SEM,EDS,XRD,UV-Vis.The results showed that talc was coated with anatase type TiO₂.The performance of decorative base paper filled with three composite fillers was similar to that filled with TiO₂ in terms of opacity,whiteness,formation,and strength.Among the three methods,the mechanical grinding method had the largest amount of TiO₂ replacement,the lowest cost,simple operation and environmental protection.Therefore,the composite filler prepared by this method could replace TiO₂ filled decorative base paper.