OK
BASF

Light stabilizers and UV absorbers are designed to solve the polymers degradation issues caused by exposure to sunlight.

BASF has developed a comprehensive range of light stabilizers and UV absorbers to meet the requirements of various markets and applications (Agriculture, Automotive, Building & Construction and others).

Light stabilizers and UV absorbers to prevent polymer degradation

Exposure to sunlight and some artificial lights can have adverse effects on the integrity and the durability of plastics articles. UV radiation can break down the chemical bonds in a polymer. This process is called photodegradation and ultimately causes cracking, chalking, color changes and the loss of physical properties such as impact strength, tensile strength, elongation and other properties.
Figure 1: Polymer before exposure to sunlight Figure 2: Polymer after exposure to sunlight

There is one effective solution to prevent polymer from photodegradation: the use of light stabilizers.

BASF has developed a comprehensive range of light stabilizers and UV absorbers to meet the requirements of various markets and applications.

What causes polymer degradation?

Solely the UV radiation of the solar spectrum has enough energy to degrade a polymer. According to the 1st law of the photochemistry, light must be absorbed by a chemical substance in order for a photochemical reaction to take place.

The UV radiation on the globe varies with latitude, altitude and seasons as shown in Figure 3:

Figure 3: Annual UV radiation on the globe

Weathering of plastics includes, in addition to the effect of UV radiation, environmental factors like temperatures, precipitations, contaminants and others:
  • Polyolefins absorb UV light only because of impurities present in the polymer, oxidation products formed during processing or additives and pigments used in the formulation of a finished article.
  • On the other hand, other polymers like Engineering Plastics and Rubbers absorb UV-light because of their intrinsic chemical structure (e.g. Polystyrene, Polyesters, ...)

How do UV and Light stabilizers work?

To counteract these damaging effects on plastics performance, a broad range of UV stabilizers designed to solve the degradation problems associated with exposure to sunlight have been developed.
Although you can find many types of UV stabilizers, they can be categorized into two general classifications:

Ultraviolet Light Absorbers (UVA) to retard photodegradation

UVAs slow down the degradation process by preferentially absorbing harmful ultraviolet radiation and dissipating it as thermal energy.

Figure 4: UV radiation absorption

The absorption of UV Light is governed by the Law of Lambert-Beer:

Absorbance = Molar Absorptivity · Concentration · Path Length

or A = ε.c.l = log 1/T where T (transmittance) = I/Io (Io is the initial light intensity)

To obtain an optimal absorption and thus effectively retard photodegradation, it is required to have high concentrations of absorbers and sufficient polymer thickness.

UV Absorbers are therefore effective:

  • At protecting the polymer bulk
  • At protecting the content when used in packaging films or bottles
  • At protecting other additives, more sensitive to UV light (e.g. pigments and flame retardants)
  • In UV absorbing substrates, such as polystyrenes, polyesters, etc.

However, they are less effective at protecting surfaces (crazing) and very thin articles such as film/fiber.

Hindered Amine Light Stabilizers (HALS) to inhibit polymer degradation

HALS are very efficient stabilizers for polymers and especially polyolefins. They do not absorb UV radiation, but act to inhibit degradation of the polymer. Significant levels of stabilization are achieved at relatively low concentrations. HALS' high efficiency and longevity are due to a cyclic process wherein the HALS are regenerated rather than consumed during the stabilization process.

Figure 5: Cyclic process - HALS regeneration

HALS are therefore:

  • Very effective in high surface area applications such as film and fiber
  • The most effective additive for the light stabilization of polyolefins
  • Also highly effective thermal stabilizers for longer polyolefin articles service life

UVAs and HALS synergy to enhance light stability

In some applications, combinations of UVAs and HALS create a synergistic interaction that may enhance light stability of a plastic article. Other additives could also have their importance in the light stability performance of a UVA - HALS system and particularly the process stabilization package.

A variety of UV Absorbers and HALS have been developed to meet polymer and specific applications requirements. High molecular weight products were commercialized to address issues like volatility and migration of light stabilizers. The selection of the optimal UV Stabilizer will depend on the polymer type, the thickness, the use of pigments and other additives and of course the expected lifetime in a specified environment.

Browse the BASF UV & light stabilizers selector to find the most appropriate solutions according to the polymer, the application and the processing mode!

Find out how BASF UV & Light stabilizers can help you meet the needs of various markets:

       Agriculture       

4

Product Selection

Products and Documents
Description
Access contents and get support
Liquid Cyanoacrylate UV Absorber. Access product details.
Liquid light stabilizer system. Access product details.
Liquid benzotriazole UV absorber. Access product details.
Liquid Benzotriazole UV Absorber. Access product details.
4 items matching your search
4

Case Studies from Light stabilizers and UV absorbers

Protection against Light Degradation for Polyethylene monofilaments and tapes used in exterior applications

Tinuvin® XT 55 is BASF’s latest generation of HALS for the film, fibers and tapes industry. Its primary application is polyethylene monofilaments and tapes.

Tinuvin® XT 55 is a high-performance light stabilizer that has very low contribution to water carry over and therefore enables the production line to run without disturbance.

Download

Tinuvin® XT 847 light stabilizer fulfills revised TPO roofing membranes standard ASTM D 6878

Tinuvin® XT 847, a proprietary light stabilizer solution based on NOR-HALS (hindered amine light stabilizer) technology provides exceptional durability when used in a properly formulated TPO roofing membrane compound.

It imparts outstanding light and long term thermal stability to enable the TPO to fulfill the revised ASTM D 6878 requirements.

Due to the inherent advantages of NOR-HALS technology products from BASF, it also has lower interaction with system components and acidic environmental contaminants than traditional HALS based chemistries, helping to retain the mechanical properties of TPO membranes to meet the demands of the marketplace and building owners.

Read more about Tinuvin® XT 847 in TPO roofing membranes and access technical data.

Download

Long Lasting TPO Roofing membranes with Chimassorb® 2020 Light Stabilizer

Struggling to formulate long lasting TPO roofing membranes?

Read this Case Study featuring Chimassorb® 2020 light stabilizer which is recommended by the DOW™ Chemical Company for the use in VERSIFY™-based TPO roofing.

Chimassorb® 2020 combines exceptionally high UV stabilization and long-term thermal stability for both MDH and ATH flame retardant-containing TPO roofing membranes, in compliance with revised ASTM D 6878 standard.

 

Download

Increase Durability of Agricultural Greenhouse Films with Tinuvin® XT 100 light stabilizer

BASF has developed Tinuvin® XT 100, an advanced NOR® HALS (Hindered Amine Light Stabilizer) technology based solution providing low interaction with acidic pesticide derivatives thanks to its low basicity and its very specific alkoxy-amines chemical content.
Tinuvin® XT 100 is a cost effective light stabilizer designed to prolong the agriculture Polyethylene film lifetime. 

Read this Case Study including a Testimonial from a Chinese greenhouse films manufacturer.

Download

13

Downloads from Light stabilizers and UV absorbers

46
Back to Top