ADDITIVES | PVC


where they can provide optimum processing while reducing VOC emissions, which is critical for meeting requirements of indoor air quality certifi- cation. One existing grade, Therm-Chek VT 218P, has proven performance in a heavily-filled base layer to replace liquid stabilisers, Hollo claims. “By moving to an all powder stabiliser, there is a 99% reduction in VOCs, with no sacrifice in performance in terms of heat stability,” she says (Figure 2).


Tin alternatives Japan’s Adeka says that many PVC materials — such as flooring, film, wire & cable, and profiles — are required to meet increasingly challenging sustain- ability demands, which it has been addressing in its development of its ADK Stab RX and RUP Series Ca-Zn stabilisers. The company says its ADK Stab RX-400 Series


grades are intended as alternatives to tin stabilisers for rigid applications. They are said to provide transparency, colour stability and heat stability comparable to tin-based systems. Meanwhile, its ADK Stab RUP series products, which are intended for wire & cable compounds, “provide excellent heat stability, colour stability, heat aging character- istics and offer superior mechanical properties compared to lead-based stabiliser systems.” Adeka has also developed a stabiliser system


offering the high weatherability required for flexible PVC used outdoors, such as high-end artificial leather. The new stabiliser system com- bines its Ca-Zn stabilisers with ADK Stab LA-81, a hindered amine light stabiliser (HALS), and a UVA absorber. The improvement in stability can be seen from the exposed samples (Figure 3).


Liquid options Demand is growing for stabilisers that comply with FDA regulations and contain no substances of very high concern (SVHC) such as tris(nonylphenyl) phosphite, TNPP, according to Songwon. It has


Right: Songwon offers a variety of tin and Ca/Zn stabilizer


systems for PVC pipe fitting production


Figure 3: Weatherability of transparent PVC with ADK-Stab LA-81 HALS, ADK-Stab 135A Ca/Zn stabilizer (0.5phr), and UVA (benzophenone-type) Source: Adeka


introduced several new additions to its Songstab product line formulated for different applications. Songstab CZ-LF420 is a liquid calcium-zinc


(Ca-Zn) stabiliser for PVC food-wrap applications that is said to impart high heat stability and transparency along with good processability. For PVC flexible films offering very high transparency, Songwon recommends Songstab BZ-L155, a powerful liquid barium-zinc (Ba-Zn) stabiliser that also offers good heat stability and lubricity. Songwon already supplies a wide range of additives for PVC fittings. It says that liquid tin stabilisers are a robust solution where liquid products are suitable, but they may influence softening point. It describes its Songstab CZ-SF400 series as a “well-balanced” range of solid one-pack tin stabilisers that improve Vicat softening point. Solid one-pack Ca-Zn grades from the Songstab CZ-SF300 series are said to provide good process- ability and impart lubricity and high heat stability. The Songstab CZ-SF600 series of solid Ca-Zn stabilisers incorporate tin boosters and are de- signed for pipe fittings, especially large-diameter systems. Good processability, a high Vicat softening point and easy dosing are among cited advantages.


IMAGE: SONGWON/IISTOCK 48 COMPOUNDING WORLD | June 2021


Performance waxes The latest developments from Clariant include wax products designed to lift production performance in high-output scenarios. “Successful processing of PVC is a balance of internal and external lubrication, wetting out and dispersion of high amounts of fillers and additives, and maintenance of colour standards and physical integrity of the finished product, while achieving maximum output with the least amount of


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