Foreword
Ultraviolet absorber is a kind of light stabilizer that can absorb the ultraviolet part of sunlight and fluorescent light sources without changing itself. Under sunlight and fluorescence, plastics and other polymer materials will undergo an auto-oxidation reaction due to the action of ultraviolet rays, leading to the degradation of the polymer and deterioration of appearance and mechanical properties. After adding ultraviolet absorbers, this high-energy ultraviolet ray can be selectively absorbed and turned into harmless energy for release or consumption.
Different types of polymers cause different UV wavelengths to cause degradation. Different UV absorbers can absorb UV rays of different wavelengths. When used, UV absorbers should be selected according to the type of polymer.
Ultraviolet absorbers should meet the following conditions: ① Strongly absorb ultraviolet rays (especially ultraviolet rays with a wavelength of 290-nm); ② Good thermal stability and will not change due to heat even during processing, and thermal volatility Small; ③ Good chemical stability, no adverse reactions with material components in the product; ④ Good miscibility, can be evenly dispersed in the material, no blooming, no bleeding; ⑤ The absorber itself has good photochemical stability, Does not decompose or discolor; ⑥ Colorless, non-toxic, odorless; ⑦ Resistant to soaking and washing; ⑧ Cheap and easy to obtain.
Ultraviolet absorbers can be divided into the following categories according to their chemical structures: salicylates, benzophenones, benzotriazoles, substituted acrylonitriles, triazines and other categories.
No.1 Salicyl phenyl ester
Ingredients: phenyl ortho-hydroxybenzoate
Performance and use: colorless crystalline powder. Has a pleasant aromatic smell (wintergreen oil smell). Density 1.250g/cm3, melting point 43℃, boiling point (1.6kPa) 173℃. Easily soluble in ether, benzene and chloroform, soluble in ethanol, almost insoluble in water and glycerin.
This product is a UV absorber, used in plastic products, but its absorption wavelength range is narrow. The U.S. Food and Drug Administration approves acrylic resin articles for use in contact with food.
No.2 UV absorber UV-P
Ingredients: reaction product of o-nitroaniline and p-cresol
Performance and use: Appearance is colorless or light yellow crystal. It can be dissolved in various organic solvents such as gasoline, benzene, acetone and so on. It has very little solubility in water and is not decomposed by concentrated alkali or concentrated acid. It can ionize with heavy metals to form salts. Can absorb ultraviolet rays with a wavelength of 270~280nm. Melting point 130~131℃.
This product is mainly used in polyester, chlorine-containing polyester, fiber acetate, polyvinyl chloride, polystyrene, organic glass, polyacrylonitrile and other resins. The stability in transparent products is better than that in colored products. The dosage in products is 0.% ~ 0.5%.
No.3 UV absorber UV-O
Ingredients: 2,4-dihydroxybenzophenone
Performance and use: This product is light-colored needle-like crystals or white powder. Moisture <0.5%. Ash content 50, water < 0.5, n-heptane < 0.5.
This product is a UV absorber, suitable for polyvinyl chloride, polystyrene, epoxy resin, cellulose resin, unsaturated polyester, coatings and synthetic rubber. The maximum absorption wavelength range is 280~340nm, and the general dosage is 0.1%~1%. However, the light stabilizing effect of this product is not outstanding.
No.4 UV absorber UV-9
Ingredients: 2-hydroxy-4-methoxybenzophenone
Performance and use: This product is light yellow or white crystalline powder. Density 1.324g/cm3. Melting point 62~66℃. Boiling point: 150~160℃ (0.67kPa), 220℃ (2.4kPa). Soluble in most organic solvents such as acetone, ketone, benzene, methanol, ethyl acetate, methyl ethyl ketone and ethanol, but insoluble in water. The solubility of this product in some solvents (g/100g solvent, 25℃) is benzene 56.2, n-hexane 4.3, ethanol (95%) 5.8, carbon tetrachloride 34.5, styrene 51.2, and DOP 18.7.
This product is a UV absorber, suitable for various plastics such as polyvinyl chloride, polyvinylidene chloride, polymethylmethacrylate, unsaturated polyester, ABS resin and cellulose resin. The maximum absorption wavelength range is 28~340nm. , the general dosage is 0.1% to 1.5%, it has good thermal stability and does not decompose at 200°C. This product hardly absorbs visible light, so it is suitable for light-colored transparent products. This product can also be used in paints and synthetic rubber.
Safety precautions: Japan and Italy stipulate that when this product is used in products that come into contact with food, the maximum dosage should not exceed 0.3%.
No.5 UV absorber UV-531
Ingredients: 2-hydroxy-4-n-octyloxybenzophenone
Performance and use: This product is light yellow or white crystalline silane powder. Density 1.160g/cm3 (25℃). Melting point 48~49℃. Soluble in acetone, benzene, ethanol, isopropyl alcohol, slightly soluble in dichloroethane, insoluble in water. The solubility of this product in some solvents (g/100 solvent, 25℃) is acetone 74, benzene 72, methanol 2, ethanol (95%) 2.6, n-heptane 40, n-hexane 40.1, and water 0.5.
This product is an ultraviolet absorber that can strongly absorb ultraviolet light with a wavelength of 270~330nm. It can be used in various plastics, especially polyethylene, polypropylene, polystyrene, ABS resin, and polycarbonate. , PVC has good compatibility with resin and low volatility. The general dosage is 0.1% to 1%. With a small amount of 4,4-thiobisate/p>
Performance and use: This product is a colorless or light yellow transparent liquid with a slightly fishy smell. The density is 1.0253~1.0257g/cm3 (20℃), the freezing point is 27℃, and the boiling point is 116~117℃ (1.48kPa). Refractive index 1.4582～1.4589 (20℃). It is soluble in polar and non-polar solvents and can be miscible with common plasticizers such as dioctyl phthalate, dioctyl sebacate, and triphenyl phosphite in any ratio.
This product can be used as a light stabilizer for polyvinyl chloride. It can give products excellent outdoor anti-aging properties, so it is known as high-efficiency weathering agent for polyvinyl chloride. Adding 2 to 5 parts of this product to polyvinyl chloride film can not only significantly improve its weather resistance and cold resistance, but also reduce the processing temperature by about 10°C. In addition, this product can also be used as polyamide, polyurethane, urea-formaldehyde resin, polyethylene Excellent solvent for various polymer materials such as phenyl sulfide.
