Why does PVC tarpaulin fade?

Introduction

Many users find that after a period of use, tarpaulins fade and look old to varying degrees. A brand-new blue or green tarpaulin becomes grayish-white and dull after a year or two, which certainly affects its appearance and user experience. So, what exactly causes PVC tarpaulins to fade? Today, we'll explore the reasons behind it.

UV Radiation

Sunlight is the source of all life, but it's the number one killer of PVC tarpaulins. The ultraviolet (UV) rays in sunlight have extremely high energy, continuously cutting the molecular chains of PVC materials and the molecular structure of pigments.

The color of PVC tarpaulins comes from added color pastes or pigments. Under long-term bombardment of UV rays, the chemical bonds of these colored substances break, causing them to lose their ability to absorb specific wavelengths of light, naturally resulting in fading and discoloration. At the same time, UV rays also damage the PVC substrate itself, making it brittle and reducing its toughness.

Rainwater and Acid Rain Erosion

Don't assume that rainwater simply washes tarpaulins clean. Acid rain, especially in modern industrial environments, is particularly damaging to tarpaulins.

Rainwater dissolves acidic substances such as carbon dioxide, sulfur dioxide, and nitrogen oxides from the air, forming an acidic solution with a low pH. These acidic substances slowly react chemically with the pigments and coatings on the tarpaulin surface, corroding it and causing pigment loss. Simultaneously, prolonged soaking in rainwater can cause some poorly water-soluble pigments to gradually leach out.

Improper Use of Cleaning Agents

To keep tarpaulins clean, many users use strong cleaning agents or chemical solvents to scrub them. While this is well-intentioned, it can be counterproductive.

Strong acid or alkaline cleaning agents (such as laundry detergent or dish soap that hasn't been thoroughly rinsed out) or organic solvents (such as gasoline or alcohol) can damage the PVC surface coating and react directly with the pigments, causing color fading or discoloration.

Symptoms: After manual scrubbing, streaks of fading appear, or the overall color becomes mottled and uneven. Temperature Difference and 

Thermal Expansion/Contraction

PVC materials expand and contract with temperature changes. In areas with large diurnal or seasonal temperature differences, this continuous expansion and contraction can cause physical damage to the coating and color layers of the tarpaulin.

Repeated thermal expansion and contraction can create tiny cracks between the pigment layer and the PVC substrate, as well as within the coating itself. These cracks not only compromise the integrity of the color but also create pathways for moisture, dust, and ultraviolet radiation, accelerating the overall aging and fading process.

Production Process and Raw Materials

The raw materials used are crucial to whether the tarpaulin fades. Inferior tarpaulins produced through low-price competition often introduce the risk of fading from the outset.

Inferior Pigments: Using cheap, low-grade pigments results in poor weather resistance and tinting strength, making them easily decomposed under external influences.

Thin Coating: An insufficiently thin protective coating cannot effectively block ultraviolet radiation and chemical corrosion.

Poor formulation: An unreasonable formulation of PVC plasticizers, stabilizers, and other auxiliary materials can accelerate the aging of the substrate, indirectly leading to fading.

Conclusion

In summary, the fading of PVC tarpaulins is a complex process involving the combined effects of light, water, chemicals, physical factors, and the material itself; it is an unavoidable natural aging phenomenon. However, through scientific selection and maintenance, we can significantly slow down this process.