Light Stabilizer 944 vs 622: Differences in Structure and Mechanism

Light Stabilizers 944 and 622 are two common light stabilizers that differ in chemical structure and mechanism of action. As a representative of Tiangang Auxiliary, we will detail the differences between these two light stabilizers from the company's perspective.

I. Chemical Structure

Light Stabilizer 944 is mainly a benzotriazole compound, with the chemical name 2-methyl-4-hydroxy-5-chlorobenzotriazole. Its molecular structure contains one benzene ring and three nitrogen atoms, two of which are located ortho to the benzene ring and the other at the 5-position of the ring. In addition, there is a hydroxyl group and a chlorine atom.

Light Stabilizer 622 is mainly a quinoline compound, with the chemical name 2-(2H-benzotriazol-2-yl)-4'-methylquinoline. Its molecular structure also contains one benzene ring and three nitrogen atoms, two of which are ortho to the benzene ring and the other at the 2-position of the quinoline. In addition, there is a 2H-benzotriazole group and a methyl group.

II. Mechanism of Action

Light Stabilizer 944 is a quenching-type light stabilizer; its mechanism is to inhibit the photo-oxidation and photo-degradation of polymers by undergoing quenching reactions with ultraviolet rays. When a 944 molecule absorbs UV rays, it converts that energy into heat, thereby reducing the polymer's photo-oxidation and photo-degradation rates. In addition, 944 can also inhibit photo-oxidation and photo-degradation by interacting with free radicals.

Light Stabilizer 622 is a hindered-amine light stabilizer; its mechanism achieves light stabilization by suppressing free radicals generated in the polymer. The hindered-amine structure in the 622 molecule can capture free radicals and prevent the chain reactions they trigger, thereby delaying the polymer's aging process. In addition, 622 can also reduce the polymer's photo-oxidation and photo-degradation rates by absorbing ultraviolet rays.

III. Performance Characteristics

Light Stabilizer 944 has high UV absorption capacity and quenching efficiency, effectively suppressing the photo-oxidation and photo-degradation of polymers. In addition, the chemical structure and properties of 944 are relatively stable, not easily affected by external factors, and it has good weather resistance and migration resistance. However, the chlorine atom group in 944 may affect the polymer's thermal stability, causing discoloration or decomposition when the temperature rises during processing.

Light Stabilizer 622 has good weather resistance and migration resistance, and is suitable for various polymer materials such as plastics and rubber. The hindered-amine structure of 622 can effectively capture free radicals and delay the polymer's aging process. In addition, the chemical structure and properties of 622 are relatively stable and not easily affected by external factors. However, the quinoline structure of 622 may affect the polymer's chromaticity, causing the product's color to deepen.

IV. Application Scope

Light Stabilizer 944 is suitable for polymer materials such as polyethylene, polypropylene, polycarbonate, polyoxymethylene, and polyamide, and is especially suitable for outdoor plastic products such as plastic films, pipes, and sheets. In addition, 944 is also suitable for rubber products such as rubber hoses and rubber sheets.

Light Stabilizer 622 is suitable for polymer materials such as polyethylene, polypropylene, polyvinyl chloride, and polycarbonate, and is especially suitable for plastic products such as plastic films, sheets, and pipes. In addition, 622 is also suitable for rubber products, coatings, inks, and other materials.

V. Precautions for Use

When using Light Stabilizers 944 and 622, the appropriate type and dosage should be selected according to the specific polymer material and application environment. Generally, the dosage of light stabilizer is 0.1%–0.5% of the polymer mass. During processing, the light stabilizer should be thoroughly and uniformly mixed with the polymer before molding, to ensure uniform dispersion in the polymer. In addition, care should be taken to prevent the light stabilizer from reacting with other chemicals such as acids and alkalis.