Focus on the application of white carbon black matting agent in coatings

The white carbon black manufacturer adds pigment or filler to the coating and evenly distributes it in the coating film to form a slightly rough surface. The larger the surface particles, the greater the degree of micro-roughness and the lower the gloss. Sometimes the production of matt coatings using light calcium carbonate or talc, etc., the amount is large, often exceeds the critical pigment volume concentration of the coating to make the physical properties of the coating film deteriorate, such as delamination and hard precipitation, the use of matting agents can be used Avoid this phenomenon. Commonly used matting agents are classified into organic and inorganic. The inorganic matting agent is mainly white carbon black matting agent. Its chemical composition is silica, which is divided into two types: surface treated with organic matter and untreated.

01 Coating base impact

Some coating bases are difficult to extinction, such as polypropylene polyurethane, long oil alkyd resin coatings and polyester systems. The resin system itself has high gloss and it is difficult to achieve matting. The system of nitrocellulose and short oil alkyd resin in wood coating has its own matting property. Compared with other coatings, the amount of silica can be reduced, and some can be reduced by 2%-4%. Studies have shown that the use of some easily matte resins in coatings that are not easily matte can reduce the amount of matting agent, achieve the same matting effect, and improve the transparency and drying speed of the film.

02 effect of curing agent

Some paint matting properties are also related to the curing agent type. For example, if the trimer of HDI or the mixed trimer of TDI/HDI is matched with the adduct, different degrees of matting can be produced due to different content of the two substances. Acidic, acid-curing amino (urea aldehyde) alkyd coatings can also produce matting properties to reduce the amount of matting agent, reduce cost, and increase film transparency, while conventional TDI-TMP adducts have no matting properties. It seems that the two-component polyurethane coating has a great relationship with the curing agent. The proper use of the curing agent not only reduces the amount of the matting agent, but also improves the transparency of the paint film, reduces the production cost, and also improves the yellowing resistance of the paint film.

03 paint film drying method

The coating is slower to dry and the coating has a higher gloss. On the contrary, if the surface is dried faster, the coating film has a lower gloss. When the solid content of the coating is low, the shrinkage of the coating film is large, and the surface gloss is lowered. The two-component polyurethane coating of the precipitated silica manufacturer, such as a quick-drying curing agent, has a surface drying speed faster than that of the ordinary curing agent, and the surface thereof is faster. The gloss is also reduced quickly, with matting, which is also a way to reduce the amount of matting agent in the coating.

04 thinner effect

The diluent has a high boiling point component, the diluent volatilizes slowly, and the gloss of the paint film is high; on the contrary, the diluent has a low boiling point component, the diluent volatilizes quickly, and the gloss is low.

05 additives

Some additives are used in matt lacquers to assist in matting. Hydrophobic silica manufacturers, such as organotin as a catalyst in a two-component polyurethane coating system, have a slight effect on the coating film. Sex has improved. Another example is to improve the surface feel of various wax auxiliaries, forming a rugged structure on the surface of the paint film, also has a certain matting effect.

06 other factors affect

Two-component polyurethane coatings have low crosslink density and are easy to extinction; high crosslink density is relatively difficult to extinction. The coating has a high solid content and a high gloss, especially when the proportion of the coating resin is large, and its matting property is deteriorated; on the contrary, when the solid content is low, the matting property is good.

07 Dispersion of white carbon black matting agent

During the formation of silica, the hydroxyl groups are connected to some silicon atoms on the surface of the silica particles, the surface becomes hydrophilic, and thus it is easy to deliquesce, and the stacking and vibration during storage and transportation are easy to produce. Reunion, so the dispersion of matting agents is particularly important. The surface treated silica is easier to disperse. Dispersion is carried out in a device with high-speed agitation, which generally keeps the liquid in a laminar vortex state. The blade speed is 5-6 m/s, and the time is generally 15-20 min. When dispersing the wax-treated white carbon matting agent, the temperature is controlled below 50 °C.

08 white carbon black matting agent anti-sedimentation

The wood coating of the masterbatch carbon black manufacturer is prone to precipitation during storage. If the viscosity of the coating is low, the precipitation is more likely to occur. There are usually two types of precipitation: one is that the bottom of the container forms a hard and strong precipitate, which is difficult to mix and it is difficult to form a uniform system. This phenomenon obviously affects the quality of the paint film, reduces the matting effect, and causes the surface to granulate and feel. Rough, can't even be used. The other is to form a soft precipitate on the bottom of the container, which can form a uniform system by stirring, which does not affect the quality of the film.