ADDITIVES | FILM PRODUCTION
withstand chlorine-based insecticides and outdoor weathering (Figure 1). Schwartz said that some specialised greenhouse
films require only partial UV absorption. She cited, for example, growing of plants that require UV for colour development or for greenhouses that use bees for pollination. The company’s new master- batches — UVA 00021 LD and UVA 07920 LD — are designed for such uses (the 07920 LD grade is said to be based on a novel technology). Meanwhile, a new long-lasting antifog master-
batch from Kafrit Group — AF 00854 LD — is recommended for production of the core and internal layers in three-layer greenhouse film structures. Accelerated testing simulating both hot and cold climates predicts that the antifog effect will prove durable for at least two seasons, which the company says is among the longest currently on the market. The masterbatch also has lower haze for more transparent films.
Oriented to quality Biaxially oriented polypropylene (BOPP) is widely used in flexible packaging, and ongoing demands for “faster, cheaper, thinner” continue to be the drivers for improvements. “Quality and consistency of quality is one of the most important criteria, because BOPP are very thin films manufactured at very high speed,” says François Thibeau, Ampacet’s Strategic Business Manager, Films in Europe. One specialised need in the BOPP area is additives that enhance cavitation, which Thibeau explains as “the process of delaminating polypro- pylene at the interface with particles under the action of stretching.” Ampacet’s PEARL portfolio of cavitation master-
Above: BASF has expanded capacity for production of its high molecular weight NOR light stabilisers at its Pontecchio Marconi location in Italy, which is its global testing hub for agricultural applications
batches for BOPP includes both organic and inorganic options. PEARL 368 is a new organic cavitation masterbatch that yields consistent cavitating efficiency across the full web width of the widest BOPP line, according to Thibeau. “It was designed to enable extended run times between die cleanings and requires lower addition rates than other organic cavitating masterbatches,” he says. Organic cavitation masterbatches are said to offer higher gloss and better mechanical properties and enable higher film yields (square metres of film for a defined weight) compared to inorganic alternatives such as calcium carbonate. Matt compounds for the outer layer of a BOPP film
Figure 1: Outdoor weathering performance of 100 micron PE films containing different Kafrit UV stabilisers exposed to monthly hypochlorite or acetamiprid insecticide spraying measured by retained elongation (UVA EXP I and UA EXP II are experimental grades)
Source: Kafrit 18 COMPOUNDING WORLD | January 2021
are supplied as compounds rather than masterbatch- es as they must provide a high level of homogeneity to ensure the matt finish is uniform after stretching. Sealing properties are also critical. Ampacet’s latest MATIF matt compound — MATIF CSR 330 — is designed for producing good cold seals for packag- ing heat-sensitive products. The silicone-free com- pound provides good release performance, includ- ing smooth unwinding and prevention of transfer of adhesive to the wrong side of the film. Biaxially oriented polyethylene terephthalate (BOPET) films are used as part of multilayer, multi- material packaging structures because of their good tensile strength and high gas barrier. These multi- material films are difficult to recycle, however, so some companies are seeking to replace them with mono-material alternatives. Biaxially oriented polyethylene (BOPE) films are making an entrance in all-PE constructions, in some cases replacing BOPET or BOPP as brands and packaging companies look to improve recyclability.
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IMAGE: BASF
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