Top 10 Categories of UV Light Absorbers
Physical vs. Chemical Methods
Methods for preventing the destructive effects of harmful UV light on colors can be broadly classified into two categories: physical methods and chemical methods.
This section focuses solely on the chemical approach—specifically, the use of UV absorbers to effectively protect target materials, thereby preventing or mitigating the degradation of their color.
Ideal Standards for UV Absorbers
- ① Strong UV absorption capabilities (particularly within the 290–400 nm wavelength range);
- ② Excellent thermal stability; they should remain chemically unchanged by heat during processing and exhibit low thermal volatility;
- ③ High chemical stability; they must not undergo adverse reactions with other material components within the finished product;
- ④ Good miscibility; they should disperse uniformly throughout the material without blooming (surface crystallization) or leaching out;
- ⑤ Intrinsic photochemical stability; the absorber itself must not decompose or undergo discoloration upon exposure to light;
- ⑥ Colorless, non-toxic, and odorless;
- ⑦ Resistance to washing and extraction;
- ⑧ Low cost and easy availability;
- ⑨ Insoluble or sparingly soluble in water.
Based on their chemical structure, UV absorbers can be classified into the following categories: salicylates, benzophenones, benzotriazoles, substituted acrylonitriles, triazines, and hindered amines.
Which are the Top 10 Categories of UV Absorbers to Choose from?
| No. | Composition | Properties and Applications |
|---|---|---|
| 1 | Phenyl Salicylate Phenyl 2-hydroxybenzoate |
A colorless crystalline powder. It possesses a pleasant aromatic scent (reminiscent of wintergreen oil). Its density is 1.250 g/cm³; melting point is 43°C; and boiling point (at 1.6 kPa) is 173°C. It is readily soluble in diethyl ether, benzene, and chloroform; soluble in ethanol; and almost completely insoluble in water and glycerol. Purity: 99%. This product functions as a UV absorber and is utilized in plastic products, although its effective UV absorption wavelength range is relatively narrow. |
| 2 | UV Absorber UV-P 2-(2'-Hydroxy-5'-methylphenyl)benzotriazole |
Appears as colorless or pale yellow crystals. Soluble in various organic solvents such as gasoline, benzene, and acetone. It exhibits extremely low solubility in water and is not decomposed by concentrated alkalis or concentrated acids. It can form salts through complexation with heavy metal ions. It is capable of absorbing ultraviolet radiation within the wavelength range of 270–380 nm. Melting point: 130–131°C. This product is primarily used in resins such as polyesters, chlorinated polyesters, cellulose acetates, polyvinyl chloride (PVC), polystyrene, polymethyl methacrylate (PMMA), and polyacrylonitrile. Its stability is generally superior in transparent products compared to colored products. |
| 3 | UV Absorber UV-O 2,4-Dihydroxybenzophenone |
This product appears as pale-colored needle-like crystals or a white powder. This product serves as a UV absorber and is suitable for use in polyvinyl chloride (PVC), polystyrene, epoxy resins, cellulose resins, unsaturated polyesters, coatings, and synthetic rubbers, among others. Its maximum absorption wavelength range is 280–340 nm, and the typical usage level is 0.1% to 1%. However, the light-stabilizing effect of this product is not particularly outstanding. |
| 4 | UV Absorber UV-9 2-Hydroxy-4-methoxybenzophenone |
This product appears as a pale yellow or white crystalline powder. Density: 1.324 g/cm³. Melting point: 62–66°C. Boiling point: 150–160°C (at 0.67 kPa); 220°C (at 2.4 kPa). It is soluble in most organic solvents—such as acetone, ketones, benzene, methanol, ethyl acetate, methyl ethyl ketone, and ethanol—but is insoluble in water. This product serves as a UV absorber suitable for various plastics, including polyvinyl chloride (PVC), polyvinylidene chloride (PVDC), polymethyl methacrylate (PMMA), unsaturated polyesters, ABS resins, and cellulose resins. Its maximum absorption wavelength range is 280–340 nm. The typical dosage is 0.1% to 1.5%. It exhibits excellent thermal stability and does not decompose at temperatures up to 200°C. Since this product absorbs virtually no visible light, it is particularly suitable for use in light-colored and transparent products. |
| 5 | UV Absorber UV-531 2-Hydroxy-4-n-octoxybenzophenone |
This product appears as a pale yellow or white crystalline powder. Its density is 1.160 g/cm³ (at 25°C). The melting point is 48–49°C. Light absorber UV 531 is soluble in acetone, benzene, ethanol, and isopropanol; slightly soluble in dichloroethane; and insoluble in water. The solubility of this product in selected solvents (expressed in g/100 g of solvent at 25°C) is as follows: acetone 74, benzene 72, methanol 2, ethanol (95%) 2.6, n-heptane 40, n-hexane 40.1, and water 0.5. This product functions as a UV absorber capable of strongly absorbing ultraviolet radiation within the 240–340 nm wavelength range. UV-531 is suitable for use in a wide variety of plastics—specifically polyethylene, polypropylene, polystyrene, ABS resins, polycarbonates, and polyvinyl chloride—and demonstrates excellent compatibility with resins as well as low volatility. The typical dosage is 0.1% to 1%. When used in combination with a small amount of 4,4'-thiobis(6-tert-butyl-m-cresol), it exhibits a significant synergistic effect. |
| 6 | UV Absorber UVP-327 2-(2'-Hydroxy-3',5'-di-tert-butylphenyl)-5-chlorobenzotriazole |
This product is a UV absorber; UVP-327's characteristics and applications are similar to those of UV-326. It strongly absorbs ultraviolet radiation in the wavelength range of 270–380 nm, exhibits excellent chemical stability, and possesses extremely low volatility. It demonstrates good compatibility with polyolefins and is particularly suitable for use in polyethylene and polypropylene. Furthermore, it can be utilized in polyvinyl chloride (PVC), polymethyl methacrylate (PMMA), polyoxymethylene (POM), polyurethanes, unsaturated polyesters, ABS resins, epoxy resins, cellulose resins, and similar materials. This product features excellent resistance to thermal sublimation, washing, and gas-induced fading, as well as superior retention of mechanical properties. When used in combination with antioxidants, it exhibits a significant synergistic effect, thereby enhancing the thermo-oxidative stability of the finished products. The typical dosage of this product in plastics ranges from 1% to 3%. |
| 7 | UV Absorber RMB Resorcinol Monobenzoate |
This product is a white crystalline powder. It has a melting point of 132–135°C and a boiling point of 140°C (at 20 Pa). Its bulk density is 0.68 g/cm³ (at 20°C). It is soluble in acetone and ethanol, and slightly soluble in benzene, water, n-heptane, and similar solvents. This product functions as a UV light stabilizer; its efficacy is comparable to that of benzophenone-type light stabilizers. It is primarily used in polyvinyl chloride (PVC), cellulose resins, and polystyrene. The typical dosage ranges from 1% to 2%. |
| 8 | Light Stabilizer GW-540 Tris(1,2,2,6,6-pentamethylpiperidinyl) phosphite |
This product is a white crystalline powder. It has a melting point of 122–124°C. It is soluble in solvents such as ethanol, chloroform, acetone, and benzene, but is sparingly soluble in water. This product is a hindered-amine light stabilizer. While it does not possess the inherent ability to absorb ultraviolet (UV) light, it effectively scavenges active free radicals generated during polymer degradation, decomposes hydroperoxides, and quenches the energy of excited-state molecules. Its light-stabilizing efficacy is 24 times greater than that of general UV absorbers. This product is suitable for use in plastics such as polyethylene; it exhibits excellent compatibility with resins and offers superior processing characteristics. In addition to its light-stabilizing function, it also provides excellent resistance to thermal-oxidative aging. However, the product has relatively poor thermal stability and is not recommended for prolonged use in hot-water environments. Furthermore, it is best processed and utilized at temperatures below 270°C, as significant weight loss occurs when this temperature threshold is exceeded. This product exhibits low toxicity. |
| 9 | Light Stabilizer 744 4-Benzoyloxy-2,2,6,6-tetramethylpiperidine |
UV-744 presents as a white crystalline powder. It has a melting point of 95–98°C and a decomposition temperature exceeding 280°C. It is soluble in acetone, ethanol, ethyl acetate, and toluene, but insoluble in water. This product is a hindered-amine light stabilizer; while it possesses virtually no inherent capacity to absorb UV light, it effectively scavenges the active free radicals generated within polymeric materials under UV exposure, thereby exerting its light-stabilizing effect. It is suitable for use in a wide range of plastics—including polypropylene, polyethylene, polystyrene, polyurethane, polyamide, and polyester—and demonstrates particularly outstanding efficacy in polyolefins. The lightfastness of this product is several times greater than that of general UV absorbers. UV-744 is non-coloring, non-staining, and exhibits excellent thermal processing stability; furthermore, when used in combination with antioxidants and UV absorbers, it demonstrates excellent synergistic effects. |
| 10 | Light Stabilizer HPT Hexamethylphosphoric Triamide |
This product appears as a colorless to pale-yellow transparent liquid. It possesses a faintly fishy and astringent odor. Its density is 1.0253–1.0257 g/cm³ (at 20°C). It has a freezing point of 27°C and a boiling point of 116–117°C (at 1.48 kPa). Refractive index: 1.4582–1.4589 (at 20°C). It is soluble in both polar and non-polar solvents and is miscible in any proportion with common plasticizers such as dioctyl phthalate, dioctyl sebacate, and triphenyl phosphite. This product serves as a light stabilizer for polyvinyl chloride (PVC). It imparts excellent outdoor anti-aging properties to finished products, earning it the reputation of being a highly efficient weather-resistance agent for PVC. The addition of 2 to 5 parts of this product to PVC films not only significantly enhances their weather resistance and cold resistance but also allows for a reduction in processing temperature of approximately 10°C. Furthermore, this product acts as an excellent solvent for various polymeric materials, including polyamides, polyurethanes, urea-formaldehyde resins, and polyphenylene sulfide. This product is non-toxic; however, it must not be used in products intended for contact with food, and direct contact with the skin should be avoided. |
Conclusion
UV absorbers are crucial for protecting plastics (polymers), coatings, and other light-sensitive substrates from the harmful effects of solar ultraviolet radiation. By carefully selecting appropriate UV light absorbers—based on specific structural chemistry, absorption wavelength ranges, compatibility with the substrate, and processing conditions—manufacturers of plastics and coatings can effectively extend the service life of their products while preserving their aesthetic appearance. Among the various classes of compounds used for UV absorption—including benzophenones, benzotriazoles, triazines, and hindered amines—each category exhibits distinct performance characteristics that offer specific advantages depending on the particular application scenario and the type of resin employed.
As environmental regulations worldwide become increasingly stringent, certain UV absorbers have been banned or restricted from use due to non-compliance with new standards. In response to this trend, as one of China Top UV absorber additive manufacturers and suppliers, iSuoChem continues to develop and introduce eco-friendly alternative plastic and paint additives, thereby assisting our customers in achieving a smooth and seamless transition.
FAQ (People Also Asked)
Q1: Which Light UV absorber is best for outdoor polypropylene (PP) applications?
For outdoor polypropylene applications, Ultraviolet Absorber UV-531 and UVP-327 are highly recommended. iSuoChem® UV-531 has excellent compatibility with polypropylene and low volatility, with a strong absorption range of 240–340 nm. UVP-327 offers superior resistance to thermal sublimation and washing, making it ideal for long-term outdoor exposure. When combined with a hindered amine light stabilizer like GW-540, the synergistic effect significantly enhances the service life of PP products. (Get UV absorber 531 TDS from us)
Q2: Can UV absorbers be used in transparent coatings without affecting clarity?
Yes. UV-9 is particularly suitable for transparent and light-colored products because it absorbs virtually no visible light while providing excellent UV protection (280–340 nm range). It also exhibits outstanding thermal stability, remaining stable at temperatures up to 200°C without decomposition. For maximum clarity, benzotriazole-type absorbers like UV-P are also excellent choices as they are colorless or pale yellow and dissolve readily in organic systems without causing haze.
Q3: What is the difference between a UV absorber and a UV stabilizer (HALS)?
Ultraviolet absorbers (such as benzophenones and benzotriazoles UV absorber) function by absorbing harmful UV radiation, and then converting it into harmless heat energy, and then preventing UV light from reaching the polymer matrix. However, UV stabilizer (hindered amine light stabilizers) like GW-540 and Light Stabilizer UV-744 (Equivalent to Tinuvin 744) act through scavenging the free radicals produced during the degradation of polymers, decomposing hydroperoxides, and quenching excited-state molecules—without absorbing the UV light themselves. HALS products can be up to 24 times more effective than conventional UV absorbers, and combining both types often produces the best synergistic protection.
