The New Products Development And Application Evaluation Of In-situ Modified Nano-calcium Carbonate

Light calcium carbonate(PCC)is one of the most productive inorganic synthetic products.Due to its non-toxicity,low production cost and wide source of raw materials,it is widely used in plastics,rubber,paper,paint and other fields.The industrially produced calcium carbonate is basically a stable calcite calcium carbonate,and there are few studies on the characteristics and use effects of vaterite calcium carbonate.Like other inorganic powder materials,calcium carbonate tends to agglomerate.Due to the hydrophilic nature of the surface,it is easier to agglomerate in the case of a paste.Therefore,calcium carbonate is generally sold as a powder product.Difficult to disperse and poor compatibility with polymer organic materials is the biggest problem in the use of powder materials.Therefore,the development of modified nanomaterials is the development direction of the calcium carbonate industry.The common stearic acid modified calcium carbonate by dry or wet method can improve the compatibility with synthetic macromolecule materials,but it still can't solve the problem that the agglomeration of calcium carbonate particles leads to performance degradation.Even with nano-calcium carbonate,the superiority of nanomaterials is difficult to achieve due to severe agglomeration problems,especially in the case of high filling content.Therefore,it is of great significance to develop new nano-modified calcium carbonate products which can overcome the above problems.The work of this thesis is mainly divided into three parts:First,the utilization of carbide slag and flue gas can be realized by making full use of glycine as solubilizer,crystal control agent and modifier.The vaterite calcium carbonate with crystalline size of about 13 nm can be obtained by the rapid synthesis method of glycine liquid-liquid reaction.Two,it has been found that polymers such as sodium lignin and styrene acrylic emulsion are good crystalline size control agents and nano-calcium carbonate modifiers.Polymer-modified vaterite calcium carbonate with crystalline size of 10 nm or less and polymer-modified calcite calcium carbonate with crystalline size of about 20 nm can be obtained by simply adding a polymer modifier in the glycine liquid-liquid method and the carbonization method.Third,the application evaluation of nano-calcium carbonate modified in-situ by macromolecule and unmodified calcium carbonate in polypropylene resin(PP)was compared.The results show that the polymer in-situ modified nano-calcium carbonate has good performance.The main innovations of this paper are as follows:1.A new process of synthesizing vaterite calcium carbonate with smaller nanometer size by glycine liquid-liquid method was developed,which can make full use of carbide slag and flue gas resources and use glycine as calcium solubilizer and sodium glycine as carbon dioxide absorbent.Under the optimum reaction conditions,the vaterite calcium carbonate with a crystalline size of about 13 nm,an aggregate size of 2.5 ?m about,columbite type of about 96%,and calcium carbonate content of more than 94%can be produced,and the filtrate can be recycled while the crystal and crystalline size are basically unchanged.Sodium glycine is used to absorb carbon dioxide,which makes the reaction turn into a liquid-liquid fast synthesis reaction.It overcomes the disadvantage of calcium carbonate synthesis in traditional gas-liquid system because of long aeration time and easy crystal growth.2.Further research found that the simple method of adding polymer modifier in situ can effectively control the growth rate of calcium carbonate crystals,reduce the crystalline size and agglomerate size of calcium carbonate,and improve the dispersibility and processing properties of calcium carbonate.In the glycine-liquid-liquid process,10%sodium lignin or 5%E01 emulsion polymer modifier can reduce the crystalline size of calcium carbonate by 34.3%or 55.2%,and the average agglomerate size by 74.2%.In the carbonization process,adding 1%E01 emulsion polymer modifier can obtain calcite nano calcium carbonate with a crystalline size of 21.8 nm,an average agglomerate size of 58.52 nm,a specific surface area of 34.91 m2/g,and a density of 2.367 g/cm3.In the carbonization process,adding 5%sodium lignin polymer modifier can obtain calcite calcium carbonate with a crystalline size of 21.9 nm,and can effectively reduce the oil absorption value of calcium carbonate.3.Whether it is vaterite calcium carbonate or calcite calcium carbonate,the calcium carbonate modified by the polymer modifier has better application performance in the polypropylene resin(PP)than the unmodified calcium carbonate.The modified calcium carbonate can greatly increase the filling amount in the polypropylene resin while satisfying the use performance of the composite material,and the composite material cost can be greatly reduced.Polymer modifier not only play the role of material crystallization template control agent,but also be used as in-situ modifier for nano-materials synthesis and component of composite materials,which is the greatest discovery and highlight of this paper.This kind of new organic-inorganic hybrid calcium carbonate products will have great application potential in coatings,plastics,rubber,paper making and so on.