亚微米立方体碳酸钙的制备及应用

Preparation and application of submicron cubic calcium carbonate

粒径≤100 nm的纳米碳酸钙容易团聚,分散性不好,用于密封胶时具有挤出性能差、模量高等缺点,为了改进这些缺点,研究了石灰的活性度、石灰生浆氢氧化钙的粒径、碳化反应时不同的碳化率和补浆量等关键参数对立方体碳酸钙合成的影响。在石灰的活性度为330~350 mL、氢氧化钙浆料的平均粒径≤2µm、碳化率达30%~65%、补浆量为原浆的20%~50%的实验条件下,制备了亚微米级碳酸钙。并通过扫描电镜、激光粒度仪对其表面形貌进行表征,发现制备的碳酸钙呈立方体、粒径分布为100~400 nm、比表面积为10~15 m^(2)/g。将其应用于硅烷改性聚醚(MS)密封胶,具有挤出性大、强度高、伸长率高、模量低的优点,符合GB 14683—2017《硅酮和改性硅酮建筑密封胶》中低模量密封胶的标准。

Nano calcium carbonate with particle size≤100 nm is easy to agglomerate and has poor dispersion.When it is used in sealant,there is some disadvantages of poor extrusion performance and high modulus.To overcome these shortcomings,the effect of key parameters such as the activity of lime,the particle size of Ca(OH)2 in lime slurry,different carbonation rate and slurry feeding amount on the synthesis of cubic calcium carbonate were studied.Submicron calcium carbonate was prepared under the experimental conditions:the activity of lime was 330~350 mL,the average particle size of Ca(OH)_(2) slurry was smaller than 2µm,carbonization rate was 30%~65%and the amount of slurry supplement was 20%~50%of the original slurry.The synthesized calcium carbonate was characterized by scanning electron microscope and laser particle size analyzer.It was found that the prepared calcium carbonate was cubic,the particle size distribution was 100~400 nm,and the specific surface area was 10~15 m2/g.When it was applied to MS sealant,it had good extrudability,high strength and elongation,low modulus and the best comprehensive performance.It met the standard of low modulus sealant in GB 14683—2017 silicone and modified silicone building sealant.