Ultraviolet absorber is a kind of light stabilizer, which can absorb the ultraviolet part of sunlight and fluorescent light source without changing itself. Under sunlight and fluorescence, plastics and other polymer materials will undergo auto-oxidative reactions due to the action of ultraviolet rays, resulting in polymer degradation and deterioration, resulting in poor appearance and mechanical properties. After adding a UV absorber, it can selectively absorb this high-energy UV light and turn it into harmless energy for release or consumption.
Different types of polymers have different wavelengths of ultraviolet rays that degrade them. Different ultraviolet absorbers can absorb ultraviolet rays of different wavelengths. When using, the ultraviolet absorbers should be selected according to the type of polymer.
UV absorbers should have the following conditions:
① Can strongly absorb ultraviolet rays (especially ultraviolet rays with a wavelength of 290-400nm)
②Good thermal stability, it will not change due to heat even during processing, and the thermal volatility is small
③Good chemical stability, no adverse reaction with the material components in the product
④Good miscibility, can be evenly dispersed in the material, no frosting, no exudation
⑤ The photochemical stability of the absorber itself is good, no decomposition, no discoloration
⑥Colorless, non-toxic, odorless
⑦Immersion resistance
⑧ Cheap and easy to get.
UV absorbers can be divided into the following categories according to their chemical structures: salicylates, benzophenones, benzotriazoles, substituted acrylonitriles, triazines and others.
No.1 salicylate phenyl ester
Ingredient: Phenyl phthalate
Properties and Uses: Colorless crystalline powder. Has a pleasant aromatic odor (oil of wintergreen). The density is 1.250g/cm3, the melting point is 43°C, and the boiling point (1.6kPa) is 173°C. Soluble in ether, benzene and chloroform, soluble in ethanol, almost insoluble in water and glycerol.
This product is a UV absorber, used in plastic products, but the absorption wavelength range is narrow. Acrylic products approved by the FDA for use in contact with food.
No.2 UV Absorber UV-P
Composition: The reaction product of o-nitroaniline and p-cresol
Properties and uses: Appearance is colorless or light yellow crystals. Soluble in gasoline, benzene, acetone and other organic solvents. The solubility in water is extremely small, and it will not be decomposed by concentrated alkali and concentrated acid. It can ionize with heavy metals to form salts. It can absorb ultraviolet rays with wavelengths of 270 to 280 nm. Melting point 130 ~ 131 ℃.
This product is mainly used in polyester, chlorine-containing polyester, acetate fiber, polyvinyl chloride, polystyrene, plexiglass, polyacrylonitrile and other resins. The stability in transparent articles is better than in colored articles. The dosage in the product is 0.% to 0.5%.
No.3 UV Absorber UV-O
Ingredient: 2,4-Dihydroxybenzophenone
Properties and uses: This product is light-colored needle-like crystal or white powder. Moisture <0.5%. Ash <0.5%. Melting point 136～149 ℃. Soluble in acetone, methanol, ethanol, methyl ethyl ketone, dioxane, N-picoline and ethyl acetate, extremely insoluble in water, n-heptane and benzene. The solubility of this product in some solvents (g/100ml solvent, 25°C) is acetone 50, benzene 1, ethanol > 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, paint and synthetic rubber. The maximum absorption wavelength range is 280~340nm, and the general dosage is 0.1%~1%. However, the light stabilization effect of this product is not outstanding.
No.4 UV Absorber UV-9
Ingredient: 2-Hydroxy-4-methoxybenzophenone
Properties and uses: 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°C) is benzene 56.2, n-hexane 4.3, ethanol (95%) 5.8, carbon tetrachloride 34.5, styrene 51.2, DOP18.7.
This product is an ultraviolet absorber, suitable for various plastics such as polyvinyl chloride, polyvinylidene chloride, polymethyl methacrylate, unsaturated polyester, ABS resin and cellulose resin. The maximum absorption wavelength range is 28~340nm , the general dosage is 0.1% to 1.5%, the thermal stability is good, and it 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 paint and synthetic rubber.
Safety precautions: Japan and Italy stipulate that when this product is used in food contact products, the maximum dosage should not exceed 0.3%.
No.5 UV Absorber UV-531
Ingredient: 2-hydroxy-4-n-octyloxybenzophenone
Properties and uses: This product is light yellow or white crystalline powder. Density 1.160g/cm3 (25 ℃). Melting point 48～49 ℃. Soluble in acetone, benzene, ethanol, isopropanol, slightly soluble in dichloroethane, insoluble in water. The solubility of this product in some solvents (g/100 solvent, 25°C) 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, which can strongly absorb ultraviolet rays with a wavelength of 270~330nm. It can be used for various plastics, especially polyethylene, polypropylene, polystyrene, ABS resin, polycarbonate, polyvinyl chloride and resin. Good compatibility and low volatility. The general dosage is 0.1% to 1%. It has a good synergistic effect when used with a small amount of 4,4-thiobis(6-tert-butyl-p-cresol). This product can also be used as light stabilizer for various coatings.
Safety Precautions: This product has low toxicity. Many countries allow this product to be used in plasticized products that come into contact with food. For example, in the United States for polyolefins, the maximum dosage in the UK is 0.6%, and the maximum dosage for polyethylene and polypropylene in Italy is 0.5%. , Japan's dosage is polyethylene 0.5%, polypropylene 1%, AS resin and ABS resin 0.5%, polyvinyl chloride 0.2% (can not contact greasy food or food with more than 20% ethanol content).
No.6 UV Absorber UVP-327
Composition: 2-(2'-hydroxy-3',5'-di-tert-phenyl)-5-benzotriazole chloride
Properties and uses: This product is an ultraviolet absorber, its characteristics and uses are similar to UV-326, it can strongly absorb ultraviolet rays with a wavelength of 270-380nm, and has good chemical stability and minimal volatility. Good compatibility with polyolefins. Especially suitable for polyethylene and polypropylene. In addition, it can also be used for polyvinyl chloride, polymethyl methacrylate, polyoxymethylene, polyurethane, unsaturated polyester, ABS resin, epoxy resin and cellulose resin. This product has excellent thermal sublimation resistance, washing resistance, gas fading resistance and mechanical property retention. Used in combination with antioxidants for a significant synergistic effect. To improve the thermo-oxidative stability of the product. The general dosage of this product in plastic is 1% to 3%.
Safety Precautions: This product is low in toxicity. Japan, the United States, France, and Italy allow this product to be used in polyolefin plastics that come into contact with food. The maximum dosage is 0.5%. 0.2%, Japan and France 0.5%.
No.7 UV absorber RMB
Ingredient: Resorcinol Monobenzoate
Properties and Uses: This product is white crystalline powder. The melting point is 132 to 135°C, and the boiling point is 140°C (20Pa). Bulk density 0.68g/cm3 (20%). Soluble in acetone and ethanol, slightly soluble in benzene, water, n-heptane, etc.
This product is a UV light stabilizer, and its efficacy is similar to that of benzophenone light stabilizers. Mainly used in polyvinyl chloride, cellulose resin, polystyrene, the general dosage is 1% to 2%.
No.8 Light Stabilizer AM-101
Composition: 2,2'-thiobis(4-tert-octylphenoxy) nickel
Properties and uses: This product is green powder. The absorption peak in the ultraviolet region is 290nm (in chloroform). It is suitable for polyolefin plastics such as polyethylene and polypropylene, especially for the light stabilization of films and fiber products, and can improve the processing performance. This product has a good synergistic effect when used together with a UV absorber, or further improves the light stabilization effect. Its main disadvantage is that the color is darker, which makes the product color, and at the same time, it has an auxiliary antioxidant effect with thioesters at high temperature, making the product gray and black.
Safety Precautions: This product is toxic and should be used with caution.
No.9 Light Stabilizer GW-540
Ingredients: Tris (1,2,2,6,6-pentamethylpiperidinyl) phosphite
Properties and Uses: This product is white crystalline powder. Melting point 122 ~ 124 ℃. Soluble in ethanol, chloroform, acetone, benzene and other solvents, insoluble in water.
This product is a hindered light stabilizer. It does not have the ability to absorb ultraviolet rays, but it can capture the active free radicals generated by polymer degradation, decompose hydroperoxides and transfer the energy of excited molecules, etc. The light stabilization effect is ordinary ultraviolet rays. 24 times the absorbent. This product is suitable for polyethylene, polyethylene and other plastics. It has good compatibility with resins, good processing performance, and low toxicity. In addition to light stabilization, it also has good thermal and oxygen aging resistance. However, this product has poor heat resistance and is not suitable for long-term use in hot water medium. In addition, this product is best processed and used at a temperature below 270 ℃, and the weight loss is more serious when the temperature exceeds this temperature.
No.10 Light Stabilizer 744
Ingredient: 4-benzoyloxy-2,2,6,6-tetramethylpiperidine
Properties and Uses: This product is white crystalline powder. The melting point is 95～98℃, and the decomposition temperature is above 280℃. Soluble in acetone, ethanol, ethyl acetate, toluene, insoluble in water.
This product is a hindered light stabilizer, which has almost no ability to absorb ultraviolet rays, but can effectively capture the active free radicals generated by polymer materials under the action of ultraviolet rays, so as to play a light stabilization effect. This product is suitable for polypropylene, polyethylene, polystyrene, polyurethane, polyamide and polyester and other plastics, especially in polyolefins. The light resistance of this product is several times that of general UV absorbers. No coloring, no pollution, good heat-resistant processability, combined with antioxidants and UV absorbers, it has excellent synergistic effect.
No.11 Triazine UV Absorber
Ingredient: 2,4,6-tris(2'n-butoxyphenyl)-1,3,5-triazine
Properties and uses: This product is light yellow powder. Melting point 156~165℃. Soluble in hexamethylphosphoric triamide, soluble in dimethylformamide when heated, slightly soluble in n-butanol, insoluble in water.
This product is an ultraviolet absorber, which can absorb ultraviolet rays with a wavelength of 300-380nm. It is suitable for various plastics such as polyvinyl chloride, polyoxymethylene, and chlorinated polyether. The dosage is generally not higher than 1%. Its light stabilization efficiency is better than UV-9 and UV-531, but this product has coloring property, which can make the product light yellow, and the compatibility with resin is also poor.
No.12 Light Stabilizer HPT
Ingredient: Hexamethylphosphoric triamide
Properties and uses: This product is a colorless or light yellow transparent liquid with a slightly fishy astringency, density 1.0253～1.0257g/cm3 (20℃), freezing point 27℃, boiling point 116～117℃ (1.48kPa), refractive index 1.4582 ~1.4589 (20°C). 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 proportion.
This product can be used as polyvinyl chloride light stabilizer. It can endow products with excellent outdoor anti-aging properties, so it is called PVC high-efficiency weathering agent. Adding 2 to 5 parts of this product to the polyvinyl chloride film can not only significantly improve its weather resistance and cold resistance, but also reduce the processing temperature by about 10 °C. Excellent solvent for various polymer materials such as phenylene sulfide.
