MATERIALS | AGRICULTURAL FILM
He said that greenhouse films have helped to U H S :
raise yields – such as almost trebling that of tomatoes since 1996. “With developments in greenhouse technology, such as new crop protection treatment – and in- creased use of sulphur – crop yield has been con- stantly increasing during the last decades,” he said. This requires long-lasting film that can with- stands higher concentrations of sulphur – which requires better light stabilisers such as the com- pany’s aminoether HALS technology, which it calls Hostavin Now. It says that acidic species in agrochemicals will degrade HALS – but its new technology includes a large hindered amine unit attached to long alkyl chains, which adds stability. The company says it has high compatibility with plastics (especially polyolefins), reduced migration and surface deposits and good distribution within the resin. From here, Clariant has developed a
range of solutions including several AddWorks AGC-branded additives. AGC 172, for instance, gives superior UV
protection, to extend film life. It can be used to create films with higher light transmission to boost crop yields.
Above: Sophisticated greenhouse films can filter out certain
wavelengths to boost the yield of crops such as red roses
Tailored solutions Manuele Vitali, an agricultural plastics expert at BASF’s competence centre for film and tape in Italy, talked about creating tailored solutions in agricultural film. In particular, he pointed to HALS light stabilisers and the need for long-term thermal stability. He said that in artificial weathering tests, Nor-HALS – which BASF supplies – outperform complex mixtures of stabilisers. He added that effective use of HALS helps to extend film lifetime – after which it should be recycled. A key emerging criterion for light stabilisers is the ability to withstand harsh chemicals such as sulphur, which are being used within greenhouses to maximise crop yield. In many cases, it is being used at ever-higher levels, meaning that film must withstand its effect.
White out Jeffrey Drusda, senior technical marketing consult- ant at Chemours, pointed out how titanium dioxide can be used to boost productivity. Its strong reflectivity in the near-infrared (NIR)
region makes it a valuable solar reflective filler. “More than half of the solar power distribution is in the NIR region,” he said.
18 FILM & SHEET EXTRUSION | April 2024
In addition, it is a strong UV absorber, shielding the polymer and contents from damage. White/opaque films have properties including
temperature control and resistance, and the ability to stop the proliferation of aerobic bacteria and lactic acid fermentation. They are often used in silo bags, silage covers and stretch-wrapped bales. In addition, their ability to smother weeds and reduce overheating makes them ideal as a mulch film. They are also found in film for greenhouses and tunnels.
Greenhouse effect Greenhouse films have become far more sophisti- cated, with special grades able to filter out particu- lar light wavelengths, for instance. Ricardo Estrada Lizcano, VP of sustainability and
global procurement at Colombia-based Grupo Plastilene, explained how films with advanced optical properties can help to boost yields in commercial flower growing. He said the properties of greenhouse films can
be tweaked to make growing conditions more suitable. For instance, cloudy and foggy conditions can affect growing – so films can be developed that maximise light transmittance. “Every crop requires a specific type of optical
properties combination,” he said. Some crops require films with as much as 91%
transmittance (T), and less than 25% haze (H) to overcome mountainous weather conditions in Colombia, he said. The company offers one film – Agrolene Transparente – with 91% T and 18% H. One challenge is that algae tends to grow on the film, which reduces transmittance. Cleaning the film then reduces film lifetime. In addition, Polybluv has similar characteristics, as well as blocking out 99% of UV rays at 360nm. UV blocking is important in order to extend the duration of the film – and to maximise the yield of certain crops. (Red and white roses are examples, though other colours of rose require more UV in order to develop their colours properly. Thermal properties are also critical. Some crops, such as blueberries, require a large swing in temperature, while roses, for instance, prefer a more even temperature.
Diffused light Israel-based Politiv produces PE-based agricultural films, with an annual capacity of around 60,000 tonnes. Ahed Watad, chief technical officer at the company, said its Diamond films can be designed for direct or diffused transmittance. “We developed a special film with high diffusion
www.filmandsheet.com
S M I
R
E A
T
T E G
O
T
C
K
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54
