Introduction of CMIT/MIT Isothiazolinone Preservative

This product is internationally recognized as a safe and broad-spectrum preservative for daily chemical products. Foreign trade name “KATHON CG” (KATHON and KATHON) its active part is isothiazoline-like compounds, structure: (A) 2-methyl-4-isothiazoline-3 and (B) 5-chloro-2-methyl-4-isothiazoline-3, does not contain Any heavy metal, can effectively inhibit and exterminate bacteria and various microorganisms.

Coated polymer photolysis
In addition to the photooxidation that is common in the photoaging process of polymers, certain specific functional groups in coating resins have a significant response to ultraviolet light, which can directly induce chemical bond cleavage, leading to polymer chain scission. Most coating resins contain ester carbonyl groups or urethane bond carbonyl groups. Even relatively inert materials such as polyolefins will slowly produce heteroatomic unsaturated structures such as aldehyde carbonyl groups or ketone carbonyl groups under the action of light and oxygen. The most important photochemical reactions of the carbonyl structure are Norrish type sasol hard wax I and Norrish type II cleavage reactions, the former being the carbonyl group. The direct cleavage of the bond requires the presence of a hydrogen atom at the Y position of the carbonyl group. Taking the ketone structure as an example, the photolysis reaction formula is as follows:

When the carbonyl structure reaches an excited state by absorbing light, it also exhibits a strong hydrogen abstraction, which captures more active hydrogen atoms from environmental molecules, thereby generating free radicals, such as isopropanol and a-hydrogen atoms of tertiary amines. The newly generated carbon center free radicals can participate in the oxidation cycle with higher activity.

Regardless of the environmental impact, internal factors are always the most critical factor. Common coatings are mostly based on basic resins such as epoxy, polyacrylate, polyurethane, and polyester. Polymer coatings with different structures have their own special photodegradation behavior and mechanism. For traditional thermosetting coatings with a large market share (including room temperature curing coatings), there have been many research reports on their photoaging behavior, while the emerging research on photoaging of photocuring coatings is more concerned by industry insiders, related comprehensive reports Rarely. Although the photo-aging behavior of the two generations of coatings has many commonalities, the difference in resin structure often makes the photo-aging of the photo-cured coating more comprehensive.