Brief Introduction and Application of Several Common UV Absorbents

UV absorber is a kind of light stabilizer, can absorb the ultraviolet part of sunlight and fluorescent light source, and itself does not change. Plastics and other polymer materials in sunlight and fluorescence, due to the role of ultraviolet light, produce automatic oxidation reaction, resulting in the degradation of the polymer and deterioration, so that the appearance and mechanical properties of poor. After the addition of the ultraviolet absorber, such high-energy ultraviolet rays can be selectively absorbed to be released or consumed as harmless energy.

Different types of polymers have different ultraviolet wavelengths that degrade them. Different ultraviolet absorbers can absorb ultraviolet rays of different wavelengths. When used, ultraviolet absorbers should be selected according to the type of polymer.

The ultraviolet absorber should have the following conditions: ① it can strongly absorb ultraviolet rays (especially ultraviolet rays with a wavelength of 290-400nm);② good thermal stability, even in processing, it will not change due to heat, and the thermal volatility is small; ③ good chemical stability, no adverse reaction with the material components in the product; ④ good miscibility, can be evenly dispersed in the material, no frost spray, no exudation; ⑤ The photochemical stability of the absorbent itself is good, does not decompose, does not change color; ⑥ colorless, non-toxic, odorless; ⑦ resistance to immersion; ⑧ cheap, easy to get.

Ultraviolet absorbers can be divided into the following categories according to their chemical structures: salicylates, phenones, benzotriazoles, substituted acrylonitriles, triazines and others.

No.1

salicyl ester phenyl ester

Ingredients: Phenyl o-Hydroxybenzoate

Performance and use: colorless crystalline powder. Has a pleasant aromatic odor (wintergreen oil odor). Density 1.250g/cm3, melting point 43 ℃, boiling point (1.6kPa)173 ℃. Soluble in ether, benzene and chloroform, soluble in ethanol, almost insoluble in water and glycerol.

This product is a kind of ultraviolet absorber, used in plastic products, but the absorption wavelength range is narrow. S. Food and Drug Administration approved acrylic products for food contact.

　No.2

UV Absorber UV-P

Composition: reaction product of o-nitroaniline and p-cresol

Performance and use: Appearance is colorless or light yellow crystal. Soluble in gasoline, benzene, acetone and other organic solvents. In water solubility is very small, not by concentrated alkali, concentrated acid decomposition. It can ionize with heavy metals to synthesize salts. Can absorb 270 ~ 280nm wavelength of ultraviolet light. Melting point 130~131 ℃.

This product is mainly used in polyester, chlorine-containing polyester, vinyl acetate, polyvinyl chloride, polystyrene, organic glass, polyacrylonitrile and other resins. Stability in transparent articles is better than in colored articles. The dosage in the product is 0.%~ 0.5%.

　No.3

UV Absorber UV-O

Ingredients: 2,4-Dihydroxybenzophenone

Performance and use: This product is light color needle crystal or white powder. Moisture <0.5%. Ash <0.5%. Melting point 136~149 ℃. Soluble in acetone, methanol, ethanol, methyl ethyl ketone, dioxane, N-methyl pyridone and ethyl acetate, extremely insoluble in water, n-heptane and benzene. The solubility of this product in some solvents (g/100ml solvent, 25 ℃) is acetone 50, benzene 1, ethanol> 50, water <0.5, n-heptane <0.5.

This product is an ultraviolet absorber, suitable for polyvinyl chloride, polystyrene, epoxy resin, cellulose resin, unsaturated polyester, coating and synthetic rubber. The maximum absorption wavelength range is 280 ~ 340nm, and the general dosage is 0.1 ~ 1%. But the light stabilization effect of this product is not outstanding.

No.4

UV Absorber UV-9

Ingredients: 2-hydroxy -4-methoxy benzophenone

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 acetone, ketone, benzene, methanol, ethyl acetate, methyl ethyl ketone and ethanol and other organic solvents, 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, DOP18.7.

This product is an ultraviolet absorber, suitable for polyvinyl chloride, polyvinylidene chloride, polymethyl methacrylate, unsaturated polyester, ABS resin and cellulose resin and other plastics, the maximum absorption wavelength range of 28 ~ 340nm, the general dosage of 0.1%~ 1.5%, good thermal stability, no decomposition at 200 ℃. This product almost does not absorb 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 contact with food products, the maximum dosage shall not exceed 0.3%.

　　No.5

UV Absorber UV-531

Ingredients: 2-hydroxy -4-n-octyloxy benzophenone

Performance and use: 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 ℃) is acetone 74, benzene 72, methanol 2, ethanol (95%)2.6, n-heptane 40, n-hexane 40.1, water 0.5.

This product is an ultraviolet absorbent, can strongly absorb the wavelength of 270 ~ 330nm ultraviolet, can be used for a variety of plastics, especially polyethylene, polypropylene, polystyrene, ABS resin, polycarbonate, polyvinyl chloride and resin compatibility is good, volatile. The general dosage is 0.1 to 1%. With a small amount of 4,4-thiobis (6-tert-butyl p-cresol) and has a good synergistic effect. This product can also be used as a light stabilizer for various coatings.

Safety Precautions: This product is less toxic, and many countries permit this product to be used in contact with food plasticizing products, such as the United States for polyolefin, the UK's maximum dosage of 0.6%, italy's highest dosage of polyethylene and polypropylene is 0.5, Japan's dosage is 0.5, 1%, 0.5,, and 0.2 (non-contact with oily foods or foods containing more than 20% ethanol).

No.6

UV Absorber UVP-327

Ingredients: 2-(2 '-hydroxy -3',5 '-di-tert-phenyl)-5-chlorinated benzotriazole

Performance and use: This product is an ultraviolet absorber, its characteristics and uses are similar to UV-326, can strongly absorb the wavelength of 270 ~ 380nm ultraviolet, good chemical stability, volatile minimum. Good compatibility with polyolefin. Particularly 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 heat sublimation resistance, washing resistance, gas fading resistance and mechanical properties of retention. The use of antioxidants is a significant synergistic effect. To improve the thermal oxygen stability of the product. The general dosage of this product in plastics is 1% ~ 3%.

Safety Precautions: This product has low toxicity. Japan, the United States, France, and Italy permit this product to be used in food contact polyolefin plastics, with a maximum dosage of 0.5%, and for other food contact plastics, with a maximum dosage of 0.2% in Italy and 0.5% in Japan and France.

No.7

UV Absorber RMB

Ingredients: Mono-benzoic acid resorcinol ester

Performance and use: This product is white crystalline powder. Melting point 132~135 ℃, boiling point 140 ℃(20Pa). Bulk density 0.68g/cm3(20%). Soluble in acetone and ethanol, slightly soluble in benzene, water, n-heptane, etc.

This product is an ultraviolet light stabilizer, and its performance is similar to that of benzophenone light stabilizer. Mainly used for polyvinyl chloride, cellulose resin, polystyrene, the general amount of 1% to 2%.

No.8

Light Stabilizer AM-101

Composition: 2,2 '-thiobis (4-tert-octylphenoxy) nickel

Performance and use: This product is green powder. The absorption peak in the ultraviolet region is 290nm (in chloroform), which is suitable for polyolefin plastics such as polyethylene and polypropylene. It has a particularly good light stabilization effect on films and fiber products, and can improve processing performance. This product and the use of UV absorbers have a good synergistic effect, or to further improve the effectiveness of light stability. Its main disadvantage is that the color is darker, so that the product is colored, and at the same time at high temperature and thioester auxiliary antioxidant effect, so that the product is gray and black.

Safety Precautions: This product is toxic and should be used with attention.

　　No.9

Light Stabilizer GW-540

Ingredients: Tris (1,2,2,6, 6-pentamethylpiperidinyl) phosphite

Performance and use: This product is white crystalline powder. Melting point 122~124 ℃. Soluble in ethanol, chloroform, acetone, benzene and other solvents, difficult to dissolve in water.

This product is a hindered light stabilizer, it does not have the ability to absorb ultraviolet light, but it can capture the active free radicals generated by the degradation of polymers, decompose hydroperoxides and transfer the energy of excited state molecules, etc., and the light stabilization effect is 24 times that of the general ultraviolet absorber. This product is suitable for polyethylene, polyethylene and other plastics. It has good compatibility with resin, good processing performance and low toxicity. In addition to light stabilization, it also has good thermal and oxidative aging resistance. However, this product has poor heat resistance and should not be used for a long time in hot water medium. In addition, this product is best processed and used at a temperature below 270°C, and weight loss is more serious when this temperature is exceeded.

　No.10

Light Stabilizer 744

Ingredients: 4-benzoyloxy -2,2,6,6-tetramethylpiperidine

Performance and use: This product is white crystalline powder. Melting point 95~98 ℃, decomposition temperature above 280 ℃. Soluble in acetone, ethanol, ethyl acetate, toluene, insoluble in water.

This product is a hindered light stabilizer. It has almost no ability to absorb ultraviolet rays, but it can effectively capture the active free radicals generated by polymer materials under the action of ultraviolet rays, thereby exerting light stabilization effect. This product is suitable for polypropylene, polyethylene, polystyrene, polyurethane, polyamide and polyester and other plastics, especially in polyolefin. The light resistance of this product is several times that of the general ultraviolet absorber. No coloring, no pollution, good heat-resistant processability, and antioxidant and ultraviolet absorber, with excellent synergistic effect.

　　No.11

Triazine ultraviolet absorber

Ingredients: 2,4, 6-tris (2 'n-butoxyphenyl)-1,3, 5-triazine

Performance and use: This product is light yellow powder. Melting point 156~165 ℃. Soluble in hexamethylphosphoric acid triamide, soluble in dimethylformamide when heated, slightly soluble in n-butanol, insoluble in water.

This product is an ultraviolet absorber, can absorb the wavelength of 300 ~ 380nm ultraviolet, suitable for polyvinyl chloride, polyoxymethylene, chlorinated polyether and other plastics, the dosage is generally not higher than 1%. Its light stability is better than UV-9 and UV-531, but the product has coloring, can make the product with light yellow, and the compatibility with the resin is also poor.

No.12

Light stabilizer HPT

Ingredient: Hexamethylphosphoric triamide

Performance and use: This product is colorless or light yellow transparent liquid, slightly fishy and astringent, density 1.0253~1.0257g/cm3(20 ℃), freezing point 27 ℃, boiling point 116~117 ℃(1.48kPa), refractive index 1.4582~1.4589(20 ℃). Soluble in polar and non-polar solvents, and dioctyl phthalate, dioctyl sebacate, phosphite and other commonly used plasticizers can be miscible in any proportion.

This product can be used as polyvinyl chloride light stabilizer. It can give the product excellent outdoor anti-aging performance, so it is known as the high-efficiency weathering agent of polyvinyl chloride. Adding 2~5 parts of this product to PVC film can not only significantly improve its weather resistance and cold resistance, but also reduce the processing temperature of about 10 ℃. In addition, this product can also be used as an excellent solvent for polyamide, polyurethane, urea-formaldehyde resin, polyphenylene sulfide and other polymer materials.