1. According to the number of colonies in the production environment, seasonal and climatic conditions, water sources, raw materials and other conditions to adjust the amount of addition, the general use of concentration of 1-5 ‰, the actual amount of addition, please use * microbiological test.
2. In the system rich in protein, starch, paste, hydroxymethyl cellulose, polyvinyl alcohol and other materials, the recommended addition amount is 5‰, and the actual amount of addition should be obtained by *microbial test.
3. The recommended addition amount is 0.3-0.5% for water-based emulsion paint, acrylic emulsion, acrylic emulsion, polypropylene emulsion, paint and other products.
2-Hydroxybenzophenone derivatives are a type of UVA with a wide range of research applications, and have been relatively mature applications in the field of polymer light stabilization such as traditional plastics and coatings. This type of UVA is generally derived from 2,4-dihydroxybenzophenone. Sometimes, the parent compound also includes incompletely etherified derivatives of 2,2′,4-trihydroxybenzophenone or 2,2′,4,4′-tetrahydroxybenzophenone, regardless of the derivative structure, the carbonyl group The vicinal sasol wax a28 hydroxyl group needs to be retained to ensure its light stabilization performance. The maximum absorption wavelength of the precursor of 2-hydroxybenzophenone is at 260nm and has no color. However, the higher the degree of substitution of the alkoxy group of 2-hydroxybenzophenone, the greater the absorption wavelength may be, and it may even appear yellow. Be careful. The light stabilization mechanism of 2-hydroxybenzophenone UVA mainly relies on the hydrogen bond between 2-hydroxyl and carbonyl oxygen atom. The molecule absorbs light to reach an excited state, and the carbonyl oxygen atom becomes more alkaline and hydrogen bonds with it. The proton of the hydroxyl group is taken away to form an enol quinone structure, which is unstable and releases energy in the form of heat. The enol-quinone structure rearranges back to the original structure, completing a protection cycle [341. In a non-damage cycle, the harm of ultraviolet rays is eliminated, and UVA molecules can be recycled and reused.
Due to the phenolic hydroxyl group in the structure of 2-hydroxybenzophenone UVA, it is likely to cause polymerization inhibition in the photo-initiated free radical polymerization, which affects the smooth curing of the coating. In addition, when the 2-hydroxybenzophenone-based UVA structure is improperly selected or unreasonably matched, it may act as a photosensitizer by itself, which not only cannot resolve the damage of ultraviolet rays, but may also aggravate the photoaging behavior of the polymer system. UVA-like application in light-curing coating systems should be particularly cautious.
2. Benzotriazole UVA
Benzotriazole (BTZ) UVA is a relatively new type of light stabilizer with a wider range of applications. The parent compound is 2-hydroxyphenyl benzotriazole,
The 5-position chlorine substitution on the benzene ring of 2-hydroxyphenyl benzotriazole, as well as the 3’and 5′-position alkyl substitutions will all make the maximum wavelength absorption peak of the absorption spectrum red shift. The electronic structure of the ground state of 2-hydroxyphenyl benzotriazole is more complicated, which can be regarded as the mixed result of the following resonance structures.
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