Yuan Lei's Little Knowledge | How to Choose Good Calcium Carbonate
Calcium carbonate (CaCO) is an inorganic compound, commonly known as limestone, limestone, stone powder, marble and so on. Calcium carbonate is neutral, insoluble in water, soluble in hydrochloric acid. It is one of the common substances on the earth, which exists in aragonite, calcite, chalk, limestone, marble, travertine and other rocks. It is also the main component of animal bones or shells. Calcium carbonate is also an important building material and is widely used in industry.
The use of calcium carbonate is so wide, so how to distinguish the quality of calcium carbonate, and how to choose a good calcium carbonate? The following methods may help you.
We know that calcium carbonate has many excellent characteristics, compared to other powder materials has obvious advantages, such as cheap; good color, easy coloring; low hardness; good thermal stability and chemical stability; easy to dry, no crystal water; non-toxic, non-irritating, tasteless, etc.
Therefore, after understanding its characteristics, there are basic requirements for how to choose calcium carbonate.
The content of calcium carbonate should be high, and the compounds of silicon, iron and other elements should be as low as possible;
2, the content of harmful heavy metal elements should be more strict requirements;
Although the content of harmful heavy metals in calcium carbonate is low and meets the national health level requirements, the content of harmful heavy metals must be strictly required to avoid harm to the human body.
3, whiteness should be as high as possible;
Calcium carbonate itself is whiter than other inorganic mineral powders, and it is enough to reach 90 degrees from the specific value. Although the whiteness has no significant effect on the performance of filled plastics, enterprises still hope that the higher the whiteness, the better, mainly based on these reasons:
(1) The higher the whiteness, the higher the purity, and the lower the content of other mineral components other than calcium carbonate. The ash of calcium powder indicates that there may be free carbon, the yellow indicates that there may be more iron compounds, and the dark indicates that the content of silicon is high. High impurity content sometimes affects the color and appearance of filled plastic products, and causes heavy wear and tear on processing equipment and molds during processing.
(2) The higher the whiteness, the better the intuitive impression, and the higher the grade.
(3) the higher the whiteness, with other pigments, the final color is more positive, more stable and uniform.
4. The lower the oil absorption value, the better;
The maximum amount of butylene phthalate (DBP) that can be absorbed by 100g of powder material is referred to as the oil absorption value of the material.
For some plastic products, such as soft polyvinyl chloride, artificial leather, cable materials, etc., need to use plasticizers, calcium carbonate oil absorption value is higher, the more easy to plasticizer adsorption into the filler, so that it loses the role of plasticized resin, so as to achieve a certain degree of softness need to increase the amount of plasticizer, resulting in rising costs. The oil absorption value can be reduced by surface treatment of calcium carbonate to coat the surface of calcium carbonate particles. For example, the oil absorption value of light calcium carbonate treated with coupling agent can be reduced from 92.91g/100g to 49.33g/100g.
5, fineness and particle size distribution should be appropriate;
(1) Considering the cost, as long as it can meet the requirements of use, it is better to use coarse ones than fine ones.
(2) Considering the performance of the filled plastic, under the premise that the cost can be appropriately increased, the effect of finer particle size will be better.
(3) From the perspective of processing fluidity, under the premise of controlling the maximum particle size, it is better to have a larger average particle size.
6, activation is not activated should be based on the needs of downstream users.
Choice, calcium carbonate, content, the higher, indicate, reach, fill, element, material, plasticizer
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