With the prevalence of green environmental protection concepts and increasingly stringent environmental regulations, water-based inks are gradually becoming the mainstream choice in the printing industry due to their low volatile organic compound (VOC) emissions and environmentally friendly and safe characteristics. However, in outdoor application scenarios, the UV resistance (i.e., UV durability) of water-based inks often becomes a key concern for users.

I. Overview of UV Resistance of Water-based Inks
Ultraviolet light (UV), with wavelengths ranging from 100 to 400 nanometers in the solar spectrum, has a strong destructive effect on printed materials. Prolonged exposure to UV light can cause printed materials to fade, lose gloss, crack, and degrade. Therefore, for outdoor billboards, packaging printing, and other applications that require prolonged exposure to sunlight, the UV resistance of inks is particularly important.

Compared to traditional solvent-based inks and UV inks, water-based inks often have certain disadvantages in terms of UV resistance. This is mainly related to the composition and drying methods of water-based inks. However, by improving formulations and adding UV-resistant additives, the UV resistance of water-based inks is gradually being enhanced.

II. Influencing Factors of UV Resistance of Water-based Inks

Pigment Types

Inorganic Pigments (e.g., iron oxide, titanium dioxide): Generally exhibit good UV resistance and color fastness, making them more favored in outdoor applications. These pigments are chemically stable and are not easily decomposed upon exposure to UV light.

Organic Pigments (e.g., phthalocyanine blue, phthalocyanine green): Offer vibrant colors but have poor UV resistance, tending to fade over time when exposed to UV light. However, by selecting high-weatherability organic pigments, UV resistance can still be improved.

Resin Composition

The resin in water-based inks directly affects UV resistance. Acrylic resins and polyurethane resins are commonly used resin materials in water-based inks. Generally, polyurethane resins exhibit better UV resistance and are therefore preferred in applications requiring high UV resistance.

UV-resistant Additives

Adding appropriate amounts of UV-resistant additives (such as UV absorbers and light stabilizers) can significantly enhance the UV resistance of water-based inks. These additives can absorb or disperse UV energy, thereby reducing the breakage of ink molecular chains and extending the lifespan of printed materials.

Drying Methods

Water-based inks dry through evaporation of water, differing from the UV curing method of UV inks. Therefore, under prolonged UV exposure, the surface of water-based inks is more susceptible to environmental factors such as oxidation and degradation. Improved drying techniques (such as hot air drying and infrared-assisted drying) can help enhance UV resistance.

Printing Substrates

The compatibility between ink and substrate also affects UV resistance. Certain plastics, metals, and specially coated papers can enhance the UV resistance of inks, while ordinary paper and uncoated materials are more prone to fading and aging.

III. Improvement Measures for UV Resistance of Water-based Inks

Formula Optimization: By adjusting the types and proportions of resins, selecting UV-resistant pigments, and increasing the content of additives, the UV resistance of water-based inks can be significantly improved. For example, using polyurethane resins to replace some acrylic resins and incorporating efficient UV absorbers.

Introduction of Nanotechnology: In recent years, materials such as nano-zinc oxide and nano-titanium dioxide have gradually been applied in water-based inks to enhance their UV and oxidation resistance. These nanomaterials can effectively absorb UV light and reduce the degradation of pigments and resins.

Protective Coating: Applying a UV-resistant protective coating on the surface of printed materials can further extend their outdoor lifespan. This coating can block direct UV exposure, reducing fading and aging of the printed image.

Although the UV resistance of water-based inks is not as good as that of UV inks, through formula adjustments, the addition of UV-resistant additives, and the introduction of advanced technologies, their UV resistance has been significantly improved. In the context of increasingly stringent environmental regulations, water-based inks are gradually replacing traditional solvent-based inks as the mainstream choice in the market due to their low VOC emissions and environmentally friendly and safe characteristics.

For printed materials requiring outdoor applications, when selecting water-based inks, attention should be paid to their UV resistance, considering the use of weather-resistant pigments, polyurethane resins, and nano-UV-resistant additives. At the same time, reasonable printing processes and drying methods can further enhance the UV resistance of inks, thereby extending the lifespan of printed materials.