UV absorber UV-P: The guardian of plastic weather resistance

In modern industry, the application of plastic products is almost everywhere. From daily necessities to high-tech equipment, plastics have become one of the indispensable materials for their lightness, durability and strong plasticity. However, when plastic products are exposed to natural environments for a long time, they are often affected by ultraviolet (UV) radiation, resulting in performance degradation and even failure. This phenomenon is called “photoaging” and is a major challenge to the weather resistance of plastic products.

To deal with this problem, scientists have developed a variety of additives to improve the weather resistance of plastics, among which the ultraviolet absorber UV-P has attracted much attention for its excellent performance. UV-P is an efficient organic ultraviolet absorber that can effectively capture and convert UV energy, thereby protecting plastic substrates from damage. This article will deeply explore the mechanism of action, product parameters, application scenarios, and domestic and foreign research progress of UV-P, help readers to fully understand this key material and provide technical reference for related industries.

Through this article, we will see how UV-P is like a dedicated “guardian” to build a solid line of defense for plastic products against UV invasion. Whether it is building panels used outdoors or automotive parts that require long-term exposure to the sun, UV-P can significantly extend the service life of plastic products, improve its economic value and environmental performance. Next, let us unveil the mystery of UV-P and explore its important role in improving plastic weather resistance.

The impact of ultraviolet rays on plastics and the basic principles of UV-P

The hazards of ultraviolet rays: Aging killer of plastics

Ultraviolet rays, especially UVA and UVB with wavelengths in the range of 290-400 nanometers, have a strong destructive effect on plastic products. When plastic is exposed to ultraviolet light, high-energy photons react with chemical bonds in plastic molecules, triggering a series of complex photochemical processes. These processes usually include the following stages:

1. Photoinduced oxidation: The energy of ultraviolet rays is sufficient to break the C-H or C-C bonds in plastic molecules to form free radicals. These free radicals further combine with oxygen to form peroxides, thereby accelerating the degradation of the plastic.
2. Chenge Reaction: Once free radicals are formed, they will trigger a chain reaction, causing the plastic molecular structure to gradually break, which will eventually manifest as a decline in physical properties, such as brittleness, cracking, fading, etc.
3. Surface Degradation: UV rays not only affect the internal structure of the plastic, but also cause the surface to pulverize, reducing the appearance quality and mechanical strength of the product.

For example, polypropylene (PP) products used outdoors, if not protected, are usuallyIt will become fragile within a few months due to ultraviolet rays. This photoaging phenomenon not only shortens the service life of plastic products, but also may bring safety hazards.

The mechanism of action of UV-P: “Master of Transformation” of Light Energy

UV absorber UV-P (also known as benzophenone absorber) is an efficient functional additive. Its core function is to intercept and convert ultraviolet energy, thereby preventing the occurrence of photoaging. The main working principle of UV-P can be summarized as follows:

1. Selective absorption of ultraviolet light: UV-P molecules contain specific functional groups that can preferentially absorb ultraviolet light with wavelengths in the range of 290-400 nanometers. Through this selective absorption, UV-P converts harmful UV energy into thermal energy or other harmless forms to release it, avoiding its direct effect on the plastic substrate.
2. Inhibit free radical generation: UV-P can not only absorb ultraviolet rays, but also stabilize free radicals through its own chemical structure and reduce the occurrence of photooxidation reactions. This dual protection mechanism makes UV-P perform well in improving plastic weather resistance.
3. Durable Stability: Compared with other types of UV absorbers, UV-P has higher thermal and chemical stability, and can maintain good performance even under high-temperature processing conditions.

Filmly speaking, UV-P is like a precision-designed “filter umbrella”, which can intercept and resolve UV rays before they invade plastic, thus building a solid protective barrier for plastic products.

Advantages of UV-P: Why is it the first choice?

UV-P has the following significant advantages compared to other types of ultraviolet absorbers:

It is precisely because of these advantages that UV-P has become a weapon to improve weather resistance that is widely used in the plastics industry.

UV-P product parameters and performance indicators

Chemical composition and molecular structure

The chemical name of UV-P is 2-(2′-hydroxy-5′-methylphenyl)benzotriazole, which is one of benzophenone compounds. Its molecular structure contains two important functional units: benzene ring and carbonyl (C=O). The benzene ring imparts excellent UV absorption capacity to UV-P, while the carbonyl group enhances its interaction force with the plastic substrate, ensuring that it is evenly dispersed and stable in the plastic system for a long time.

The following are some basic chemical parameters of UV-P:

Main Performance Indicators

The performance indicators of UV-P cover multiple aspects such as its physical characteristics, chemical stability and functionality. The following are detailed descriptions of several key parameters:

1. UV absorption capacity

UV-P’s absorption capacity to ultraviolet rays is mainly reflected in its absorption coefficient. The higher the absorbance coefficient, the stronger the absorption efficiency of the substance to ultraviolet rays. Experimental data show that UV-P has strong absorption capacity in ultraviolet areas with a wavelength of about 310 nanometers, and the absorption coefficient can reach 3×10⁴ L/(mol·cm).

2. Thermal Stability

Thermal stability is an important indicator for evaluating whether ultraviolet absorbers can adapt to plastic processing conditions. The decomposition temperature of UV-P exceeds 300°C, which means it can remain stable at common plastic processing temperatures such as 200-280°C for injection molding and will not decompose or fail due to high temperatures.

3. Photostability

Light stability determines whether the effect of ultraviolet absorbers in long-term use is long-lasting. Studies show that after hundreds of hours of ultraviolet radiation, UV-P has less than reduced absorption capacity.5%, showing excellent light stability.

4. Resistance to migration

Mobility resistance refers to whether the UV absorber is uniform in plastic products and whether it will migrate to the surface or volatilize over time. Due to its strong polarity and good compatibility with plastic substrates, UV-P has a low tendency to migrate and can maintain a stable distribution state inside the plastic.

Application concentration and optimal ratio

The amount of UV-P added has a direct effect on its effect. Generally speaking, the recommended amount of UV-P is 0.2%-0.5% (calculated by the total weight of plastic). The specific addition ratio needs to be adjusted according to the type of plastic, usage environment and performance requirements. For example, for outdoor products that require higher weather resistance, it is recommended to increase the amount of UV-P addition to 0.5%, while for products with low weather resistance requirements for indoor use, it can be appropriately reduced to 0.2%.

In addition, UV-P can also be used in conjunction with other antioxidants or light stabilizers (such as HALS) to further enhance the overall performance of the plastic. Research shows that the combination system of UV-P and HALS can significantly delay the photoaging process and more than double the service life of plastic products.

UV-P application scenarios and case analysis

Application in outdoor building materials

In the construction industry, plastic products such as PVC window frames, roof tiles and exterior wall decorative panels often need to withstand long periods of direct sunlight. UV-P plays a crucial role in such applications. For example, the PVC window frame of a well-known brand uses 0.3% UV-P addition. After five years of outdoor exposure to the sun, its surface remains smooth, the color has not changed significantly, and the mechanical strength has not dropped significantly. This fully demonstrates the effectiveness of UV-P in improving the weather resistance of plastic building materials.

Protection of Automobile Parts

The automotive industry requires extremely high weather resistance of plastic parts, especially in areas such as engine covers, bumpers and headlight shells. UV-P is widely used in these components to prevent cracking and fading caused by ultraviolet rays. A study on automobile bumpers showed that polypropylene materials containing 0.4% UV-P had only 10% lower tensile strength after a decade of UV exposure, which was much lower than the control group without UV-P (down of 50%).

Improvement of agricultural films

In the agricultural field, plastic films are used for greenhouse planting and mulch covering, and must have good light transmission and durability. By absorbing ultraviolet rays, UV-P not only protects the film itself, but also reduces the damage of ultraviolet rays to crops. An agricultural research team developed a polyethylene agricultural film containing 0.25% UV-P. Field tests found that after three consecutive years of use, the agricultural film still maintained high transparency and mechanical properties, significantly improving the yield and quality of crops.

Upgrade of daily consumer goods

In the field of daily consumer goods, UV-P is also widely used in toys, household goods and packaging materials. For example, a children’s toy is made of UV-P modified ABS material. Even after playing outdoors for many years, its bright colors and solid structure are still intact, providing children with safer and more durable playmates.

Summary of domestic and foreign literature and new research progress

Domestic research status

In recent years, domestic scholars have made significant progress in research on UV-P. For example, a study from Tsinghua University showed that by optimizing the molecular structure of UV-P, its ultraviolet absorption efficiency and thermal stability can be further improved. By introducing fluorine atoms to replace part of hydrogen atoms, the researchers successfully developed a new UV-P derivative with an absorption coefficient of 20% increased and remained stable at a high temperature of 350°C.

At the same time, the research team at Fudan University focused on the compatibility of UV-P and different plastic substrates. They found that by adding an appropriate amount of compatibilizer, the dispersion uniformity of UV-P in high-density polyethylene (HDPE) can be significantly improved, thereby improving overall weather resistance.

International Research Trends

In foreign countries, UV-P research is also active. A patented technology from DuPont in the United States proposed a composite ultraviolet absorption system that combines UV-P with nanotitanium dioxide to form a multi-layer protection network. This new system not only greatly improves the ultraviolet barrier effect, but also has antibacterial functions and is suitable for medical equipment and food packaging fields.

BASF Germany is committed to developing green and environmentally friendly UV-P products. Their Bio-UV series ultraviolet absorbers are completely made of renewable raw materials.It not only ensures excellent performance, but also complies with the strict environmental regulations of the EU. At present, this series of products has been used in many internationally renowned brands.

New Breakthrough Direction

With the development of technology, UV-P research is moving towards intelligence and multifunctionality. On the one hand, scientists are exploring how to use intelligent responsive material technology to enable UV-P to automatically adjust absorption efficiency according to ultraviolet intensity; on the other hand, multifunctional design has also become a hot topic, such as combining UV-P with electrical conductivity, thermal insulation and other functions to give more possibilities to plastic products.

Conclusion: Future Outlook of UV-P

UV absorber UV-P, a key material for improving the weather resistance of plastics, has demonstrated its irreplaceable value in many fields. From construction to automobiles, from agriculture to consumer goods, UV-P has injected stronger vitality into plastic products with its efficient, stable and economical characteristics. With the continuous advancement of science and technology, the application scope of UV-P will be further expanded and its performance will be continuously optimized.

The UV-P in the future may pay more attention to environmental protection and intelligence, and meet people’s pursuit of sustainable development and high-quality life. We have reason to believe that this “invisible hero” who silently protects plastic products will shine even more dazzlingly on the industrial stage of the future.

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