Infrared curing can be used for drying of water-based wood coatings. Infrared curing actually refers to the curing of furniture panels and their coatings by absorbing radiation energy and converting it into heat energy under the irradiation of infrared rays.
Infrared light is an invisible light between visible light and microwave. The wavelength is 0.72-1000um, and it can be divided into “near”, “medium” and “far” infrared rays, which are commonly used for coating drying.
Infrared curing has the advantages of fast curing speed, fast temperature rise and good curing quality. However, when using infrared heating to dry the coating, there is an obvious temperature gradient, and its drying extends from the surface to the inside, which is not suitable for drying thick coatings; infrared drying can only heat the area that can be reached by infrared rays, and cannot be used to dry three-dimensional objects.
Main varieties of paint matting agents
The first matting agent variety invented by American Davison Company was in 1947. For more than half a century, there have been more and more varieties and specifications, and more and more usage. According to statistics from Degussa, Germany, the consumption of micron synthetic silica matting powder in Asia in 2000 exceeded 10kt/a, and more than half of it was used in wood coatings.
At present, there are three main categories of micron-level synthetic silica, which are introduced as follows.
Micron-sized synthetic silica aerogel
It is a micron-sized particle made of high-porosity silica gel (silica gel for short) through a strictly controlled grinding process. Silica gel has a three-dimensional network structure formed by primary particles, its skeleton is stable, its strength is good, and it is resistant to excessive grinding during the coating dispersion process.
Another characteristic of silica gel matting agents is the large pore volume. Generally, silica gel with a pore volume greater than 1.5 mL/g is called aerogel. The larger the pore volume, the higher the matting effect.
In addition, the transparency of the matting coating film is relatively high, wax emulsion china which has no effect on the drying characteristics of the coating, and the matting agent has little effect on the mechanical properties and weather resistance of the coating film is also its advantage.
A typical silica aerogel matting agent is Syl oid series 5 produced by Grace Company.
The Syl oid ED series was introduced to the market in 1981 and entered the Chinese coatings market in the 1990s. It had most of the market in high-end matte coatings. The C series launched by the company in 1997 has more advanced performance and better matting effect. It is said that it can save 1/3 compared with ED series. At present, the ED series is gradually replaced by the C series.
British IN EOS (Cros field) company is also the main manufacturer of micron-sized silica aerogel matting agents, and its product brands are Gas il and HP series.
In addition, Japan’s Fuji Sy lysia company’s Sy series, South Korea’s DCC company’s ML series, etc. also have a certain domestic market.
Some domestic silica gel manufacturers are also developing this product, but it is still in the pilot or trial production stage. The trial product still has a gap with Grace’s ED. There is no domestic matting agent equivalent to the Sy loi dC series on the market.
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