The plastics world has always been very technical, but with the intense competition over the past years in Asia as well as Europe and North Americas, maximum efficiency is continuously being squeezed out from all products and processes. Furthermore, increasing mandatory legal norms in many client application areas, combined with diversifying customer needs require an excellent understanding of the overall market requirements.
At UniteChem we continuously keep in mind the needs of not only our direct customers, but also their customers’ applications, developing the most cost-efficient and innovative solutions to meet new needs, while of course maintaining all regulatory and environmental requirements. This follows from our “3R philosophy” of being “Reliable, Responsive and Respectful”.
In this article we provide some examples and insights into three application areas: low-VOC automotive interiors, pesticide-resistant agricultural films, and high-performance fibers.
Interior automotive applications require low VOCs (Volatile Organic Compounds) materials certified by international standards (e.g. VDA 277), as well as increasingly long-lasting performance of the parts to assure no discoloration during lifetime of the car.
Since the mid-90’s, the WHO has pushed automotive OEMs and plastic material producers to develop low “Fogging” materials (low organic substances deposition on the auto interior glasses) for automotive interior applications. More recently several norms for low VOC/Fog have been defined (e.g.: VDA 277, VDA 278, SAE J1756, VW Pp”{‘] 3341, GM W8081, NES M0402, TSM 0508G, HJ/T 400-2007, etc.).
VOCs present a potential danger to human health both in interior of autombiles and in indoor air. UniteChem has developed solutions to decrease this VOC risk:
The standard recommended solution until recently for applications in TPOs automotive interior trims have been our LS 3853 in Asia, and the no-dust flowable version LS P58 in Europe. These products were compliant with both low VOC requirements and interior light stability standards. Today we have further developed our synergistic blends LS 5230 and the very cost effective LS 5229, based on highly compatible HALS and Benzoate UV 2908, further enhancing low VOC performance according to VDA 277-TVOC (total volatile organic compounds) and VDA 278 VOG/FOG, and even over-performing the previous solution in respect to light stability norm VW PV 1303 for interior automotive. These solutions can also be used at a lower total additive loading, giving the customers that extra something to be successful and competitive (see Table 1).
The agricultural market is becoming more challenging with increasing demand for high pesticide resistance in agricultural polyethylene greenhouses films. Greenhouse films in the Mediterranean area are nowadays expected to resist 3-4 seasons at 3000 ppm of Sulphur (pesticide amount standard measure on film), compared to a few years ago where 2-3 seasons at 2000 ppm of Sulphur was deemed sufficient.
Sulphur fumigation is the usual practice in many parts of the world to eliminate bugs and to protect plants, typically by burning Sulphur in a small burner, and the resulting SO2 in the presence of moisture generating sulfurous acid (S + O2 SO2, SO2 + H2O H2SO3). As this is very dangerous to farmers’ health, other large-volume agrochemicals containing Chlorine and sometimes fungicides containing Bromine are also used, which are even more aggressive to plastics.
Metal impurities such as iron (typically from the ground sand) or other metal pollutants from fertilizers are also often deposited on the film surface, further contributing to polyethylene degradation through the aggressive redox system Fe3+/Fe2+ that is a strong oxidizing agent for all polymeric materials.
UniteChem can today propose to the PE agricultural film market several solutions based on synergistic systems that combine light stabilizers with different modes of action to extend the greenhouse film lifetime and enhance resistance to high pesticide treatments, complying with customers expectations.
Our acid resistant HALS LS 119 combined with Benzoate UV 2908 and a persistent UV-Absorber (either UV 360 or UV 1164 according to customer needs) meet the challenging high levels of pesticides in the Mediterranean area (Technical background in patent EP1481024 B1, expired in the EU and China, but still valid in the US)
Table 2 shows the results for several films installed in Greenhouses in the Mediterranean area (Morocco, Sicily and Almeria). The results match the customers’ expectations in presence of high content of Sulphur alone, or combined with Chlorine content and ferrous sand pollution.
Two greenhouses were also tested with our new “experimental N-OR Hals 371” under industrial development, exceeding the expectations in terms of field resistance to pesticides.
Some general indications about stabilization systems recommended in greenhouse application are summarized in Table 3 and pesticide amount segmentation for the application is proposed in Table 4.
Fiber applications such as Polyamide (nylon), Polyester, Acrylic, Polyurethane (Spandex) and Polypropylene or Polyethylene fibers applications are another important market segment where UniteChem is supporting customers to become more efficient and effective in light stabilizer utilization.
Many different techniques exist to produce different types of fibers: filament yarns, spun yarns, woven and nonwoven, microfibers, completely oriented or partially oriented, texturized (to give crimp or twist, see Fig. 1) or tentered (treated at high temperature to modify the properties).
For each different type of fiber and processing UniteChem can expertly support customer needs in terms of durability and light stabilization:
For large mass volume fibers like Nylon 6, Acrylics, Polyurethane or Polypropylene the stabilizer of choice remains as LS 944 where long-lasting protection properties are combined with a cost performance advantage. LS 119 combined with AO 3114 and AO 626 are the ideal solution when yellowing over time becomes a critical criterium (e.g. gas-yellowing due to Nitrogen oxides that pollute the air and chemically interact with the fiber causing discoloration). Table 5 provides further insights.
LS 2020 was developed for high melt-processing temperatures (PA6, PA66, PP) and when high production rates without interruptions are required. It’s the best choice to assure high productivity rate to the customer lines.
In all Polyamide and Acrylic fibers, our UVA UV 360 can be added to the HALS of choice to have a synergistic effect that increases the fiber lifetime.
For polyesters fibers, UV 1577 as best technical solution or UV 360 as a cost-performance alternative are the most up-to-date recommendations. If there is a need to further extend the durability of polyester fibers, additionally to the UVA also HALS LS 622 or LS 119 can be added after a lab check to evaluate the influence on Melt Flow Rate (MFR) and fiber spinnability.
Polyurethane fibers such as Spandex, are stabilized with a mix of HALS and UVA to take advantage of their synergistic effect. UniteChem offers UV 234, UV 360 or UV 1577 in combination with HALS such as LS 944 or LS 119 for lighter colors.
In all fiber types applications where a Pigment with low weather or light fastness (weathering fastness < 4 or light fastness <7) is used, it is always suggested to apply UV 1164 in combination with a suitable HALS for the application.
Besides these three application examples, UniteChem can provide customers with expert advice also in other applications such as geomembranes, synthetic turf, packaging, rotomolding, rubbers, coating, adhesives, and many others that require an improved UV stability.
Our guiding 3R philosophy: Reliable, Responsive and Respectful
UniteChem Group, with global headquarters in Suqian City, Jiangsu (China), is one the world’s class suppliers of high-performance light stabilizers for plastics in a wide range of demanding industrial applications. As one of China’s largest specialty chemicals companies, the Group has diversified activities in R&D, application development, production, sales, trading and machine manufacturing. It specializes in the production of light stabilizers, UV absorbers and other related products.
With a workforce of about 1,650 employees worldwide, UniteChem generates a turnover of approximately EUR 300 millions and supports its growing customer base through several production plants in China and a strong network of sales, service and warehousing facilities throughout Asia, the Middle East and Europe.
