A kind of production method of low alkalinity nanometer calcium carbonate

Abstract

The invention discloses a production method of low-alkalinity nanometer calcium carbonate. The production method of the low-alkalinity nanometer calcium carbonate comprises the following steps: carbonizing calcium hydroxide suspension liquid and adding a crystal-form regulator to obtain nanometer calcium carbonate slurry; standing the prepared nanometer calcium carbonate slurry; performing secondary carbonization on the nanometer calcium carbonate slurry after standing and adding an auxiliary additive; performing surface modification on the nanometer calcium carbonate slurry after secondary carbonization; and performing aftertreatment. The low-alkalinity nanometer calcium carbonate prepared by the method has stable alkalinity, good diameter uniformity, small length-diameter ratio span andhigh crystal-form purity; and the low-alkalinity nanometer calcium carbonate serving as a filling agent has excellent reinforcing performance, can improve the tensile strength and the tensile elongation of products and can reduce tensile deformation rate.

Description

technical field [0001] The invention relates to the field of calcium carbonate preparation technology, in particular to a production method of low-alkalinity nanometer calcium carbonate. Background technique [0002] Calcium carbonate is a widely used inorganic salt industrial product, which can be used as filling and modifying materials. It is commonly used in industries such as plastics, rubber, paint, adhesives, papermaking, food processing, and pharmaceuticals. daily life are closely related. [0003] At present, the commonly used calcium carbonate production method in industry is to introduce carbon dioxide into the calcium hydroxide suspension for carbonization, then dehydrate, dry, depolymerize, and sieve to obtain the finished calcium carbonate product. If in the carbonization process of calcium hydroxide, Control carbonization at a certain temperature and add a certain crystal form regulator to make the particle size of calcium carbonate particles within 100 nanome...

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Problems solved by technology

[0004] In the carbonization process of calcium carbonate, the temperature control in the production process, the dosage and type of the added crystal form regulator are all directly related to the crystal form of nano calcium carbonate. At present, the nano calcium carbonate produced by the crystal form regulator is The purity of the calcium crystal form is not high, the particle size uniformity is poor, and the length-to-diameter ratio span is large; the untreated nano-calcium carbonate has a small particle size and the adsorption force between the particles is equivalent to its own gravity, and the surface is hydrophilic and oleophobic. Poor capacity, difficult to disperse in composite materials

Poorly dispersed nano-calcium carbonate not only seriously affects the appearance of the product, but the large-sized aggregates are also easy to form internal defects in the material, which cannot achieve the ideal reinforcement effect on polymer materials; in addition, since calcium carbonate itself is a strong base and weak acid salt, Moreover, calcium carbonate products always contain more or less magnesium ions in the form of magnesium carbonate, and because magnesium carbonate has a higher solubility in water than calcium carbonate, the alkalinity obtained by hydrolysis is stronger, and the prepared nanocarbonate Calcium and alkalinity are high, resulting in limited applicability

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