Bright prospects for the development of light-curing coatings

What is the principle of UV coating curing? UV coatings are UV-curing coatings. After UV-curing coatings are irradiated with ultraviolet light, the photoinitiator first absorbs the ultraviolet radiation energy and is activated. The electrons in the outer layer of the molecule jump and generate active centers in a very short time. The active center interacts with the unsaturated group in the resin to cause the double bond in the light-curable resin and the reactive diluent molecule to break, and a continuous polymerization reaction occurs, thereby cross-linking each other to form a film. Chemical kinetics studies have shown that the mechanism of UV-induced curing of UV coatings belongs to free radical chain polymerization. The first is the photoinitiation stage; the second is the chain-growth reaction stage. In this stage, as the chain grows, the system will cross-link and solidify to form a film; finally, the chain radicals will complete the chain termination through coupling or disproportionation.

Ultraviolet curing (UV curing) is a type of radiation curing. Radiation curing uses electromagnetic radiation, such as ultraviolet (UV) or electron beam (EB) to irradiate the coating to produce radiation polymerization, radiation crosslinking and other reactions. The chemical process of quickly converting low-molecular-weight substances into high-molecular-weight products. The curing is carried out directly on the substrate without heating. The system does not contain solvents or contains a very small amount of solvents. After irradiation, the liquid film is almost completely cured, so VOC ( Volatile organic compounds) emissions are very low. UV light curing system is divided into free radical system and cationic system, both of which have different curing mechanism components. The free radical system is a photoinitiator that is excited by UV irradiation to generate free radicals, which initiates polymerization and crosslinking of monomers and prepolymers; the cationic system is a cationic photoinitiator that is irradiated to generate strong proton acids, catalyzes addition polymerization, and cures the resin .

Development prospects of UV-curable coatings, data report on the radiation curing market in North America and Asia Industry statistics conducted by the North American Radiation Curing Association every two years show that the growth rate of North American formula products in 2019 is estimated to be 3.7%, the growth rate in 2020 is expected to be 4.6%, and the annual growth rate for the next three years is 5.0%. In the global UV and EB market, Asia occupies the first place with 38%, Europe ranks second with 27%, North America 26% is slightly lower than Europe's third, and other regions account for 9%.

The consumption of formula products in 2019 was 165,000 tons, an increase of 8.4% over 2017. In terms of specific application products, printing and packaging varnish occupies the first place with 25%, but it is lower than the proportion in 2017 (26%); while printing ink ranks second with 22%, and the total increase is mainly It was led by inkjet; wood coatings ranked third with 18%, and plastic coatings ranked fourth with 12%, an increase.