Yuan Lei tells you | Application of nano calcium carbonate in the field of coatings

Release time:

2024-01-29 09:35


Yuan Lei tells you | Application of nano calcium carbonate in the field of coatings


Nanomaterials refer to polycrystalline materials with nanometer crystal size, which have two important characteristics of small size and high concentration of grain boundaries. Usually, the continuous energy band of large crystals is split into energy levels close to molecular orbitals, resulting in small size quantum tunneling effect, and due to its high concentration of grain boundaries and interface original The increase in the imbalance of sub-forces produces interface effects, which lead to sudden changes in the mechanical, magnetic, optical, electrical and thermodynamic properties of the material. .


The application of nanomaterials in coatings, because there are many active points in the molecules such as film-forming binders, pigments and fillers, and additives, these active points may have strong interactions with the active points on the surface of nanoparticles, which may form a dense and stable coating, so that the physical and chemical properties of the coating are significantly improved.

Calcium carbonate is a non-toxic, non-stimulating, odorless white soft filler, in the coating industry, its easy to be compatible with all kinds of polymers, good thermal stability, is one of the most commonly used raw materials, in the film-forming material plays a skeleton role. In recent years, with the rise of nanotechnology, the application of nano-calcium carbonate in coatings in order to improve the performance of coatings is one of the hot topics in the coating industry, especially the completion of many domestic tons of nano-calcium carbonate production lines, it is urgent to find applications in a series of fields including coatings, but nano-calcium carbonate directly used in coatings, there are the following defects: high surface energy of particles, in a thermodynamically unstable state, easy to agglomerate; the surface of calcium carbonate is hydrophilic and oleophobic, the polarity is very high, it is difficult to disperse in organic media, and the binding force with the base material is poor, which is easy to form interface defects, resulting in the decline of film performance. 

Surface Modification of Nanometer Calcium Carbonate Particles 

The application of nano-calcium carbonate particles in coatings involves the compatibility of nano-materials and binders. The film-forming binders of coatings are obviously different from polymers such as plastics and rubber in terms of the type and quantity of functional groups and relative molecular mass, which leads to differences in the surface polarity of polymers and the interaction modes with pigments and fillers. For the successful application of nano-calcium carbonate in coatings, the surface of nano-calcium carbonate must be specially modified.

So far, the surface treatment of nano calcium carbonate mostly adopts the traditional treatment method of inorganic pigments and fillers, and the treatment agents used are mostly stearic acid and its salts, various surface active agents and coupling agents. Zhang Shengsheng and others use fatty acid sodium instead of fatty acid. Since carbon dioxide is introduced at the same time during treatment, the actual coating on the surface of calcium carbonate is still fatty acid, but when fatty acid sodium diffuses in water, it is smaller than fatty acid, and the coating effect is improved. However, from the electron microscope images provided by the author, the dispersion improvement is not significant.

nano calcium carbonate composite coating

Known weeks, calcium carbonate itself as a physical filler, widely used In all kinds of coatings. It can change the rheology of the coating, the toughness of the coatingwater resistance, weather resistance, reduce the processing cost of the coating. Compared with the traditional heavy calcium or light calcium, although the cost of nano calcium carbonate has increased significantly, it is still at a lower price than other ordinary pigments and fillers, especially after the nano-sized calcium carbonate, the changes brought about by the coating reinforcement, transparency, thixotropy, leveling and other aspects are the focus of paint manufacturers.

Calcium carbonate, nano, coating, surface, material, material, filler, application, performance

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Fillers in coatings are usually white or slightly colored pigments with a refractive index less than 1.7. It has the basic physical and chemical properties of pigments used in coatings, but due to its refractive index being similar to the film-forming material, it is transparent in coatings and does not have the coloring and covering power of coloring pigments. It is an indispensable pigment in coatings.

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In architectural coatings, commonly used mineral materials include barium sulfate, calcium carbonate, kaolin, mica powder, talc powder, quartz powder, silica micro powder, transparent powder, glass powder, wollastonite powder, etc. Reasonable application of various mineral materials can effectively improve or enhance the performance of coatings. Let's take a look at the application of different mineral materials in coatings.

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Mineral materials refer to the material products obtained by processing and transforming natural minerals (mainly non-metallic minerals) or rocks as the main raw materials, or minerals or rocks that can be directly used as materials and aim to utilize their main physical and chemical properties. This meaning mainly includes the following four aspects: first, natural minerals and rocks that can be directly utilized or processed to be utilized; Secondly, finished or semi-finished materials made mainly from natural non-metallic minerals and rocks through physical and chemical reactions; Thirdly, artificially synthesized minerals or rocks; Fourthly, the direct utilization targets of these materials are mainly their own physical or chemical properties, not limited to individual chemical elements.