MATERIALS | POLYOLEFINS
He said that the company’s nepheline syenite is a high clarity anti-blocking agent that is typically used in agricultural film and other applications. The company tested its Minibloc HC1400 against other anti-blocks – diatomaceous earth (DE), talc and synthetic silica – by extruding Dowlex LLDPE resin on a blown film line. The film was tested for haze/clarity, transparency and blocking. For haze, a loading of 0.5 wt% showed the best
How reduced downtime and die lip cleaning increase net profit Source: Shell Polymers
Processing aids Dan Falla, senior technical service for films at Shell Polymers in the USA, highlighted how polymer processing aids (PPAs) can boost extrusion performance. He said that the company’s PPAs – which typically use a combination of fluoropolymers – can help to raise film extrusion output by coating internal extruder components such as die lips and walls. This can help to reduce drag and back pressure – and increase output. In one case study, he said it was important to determine the economic cost-advantage of PPA addition. Factors such as a reduction in back pressure, as well as a drop in motorload, can contribute to cost savings. He summarised the effect of adding the com-
pany’s PPA – at 500ppm and 800ppm – to the extrusion of hexene LLDPE film at 1500 lbs/hour. At the upper end, over a whole year, output had risen by more than 1m lbs. This equated to a net profit of around US$1m – an increase of about 20%. For multi-layer film, adding the PPA helped to
reduce the thickness of the layers – which further reduced cost – boosting net profit by around 30%. In a second example, PPA was used to reduce die lip build-up by creating a coating at the die exit. This reduced downtime because there was less need to clean the die, less scrap and less variation in film thickness. It resulted in 85% uptime, com- pared to 80% without the PPA. This helped to raise net profit by nearly 50%. “Using PPA reduces downtime and can increase output – improving productivity and bottom line profits,” he said.
Optical improvement Kysle King, technical sales manager at Sibelco, said that different anti-block formulations could help to improve the optical properties of LLDPE films.
34 FILM & SHEET EXTRUSION | January/February 2020
result. For clarity, 0.5 wt% was most effective – with 0.75 wt% in second place, ahead of other formulations. Transparency was tested by shining an LED light
source through the film. Software interpreted the data, reporting faults such as gels, holes and die lines. Results were calibrated against DE at 0.5 wt%. Taking this as 100% transparency, HC1400 came out at around 104% – the best result. The same was true for the higher loading. Both loadings showed a transparency of more than 90% – better than any other anti-block. The blocking force at 0.75 wt% was around 3g – the best result. In direct comparison with DE, King said that Minibloc allowed higher loadings (of up to 70%), better top size control and better clarity/lower haze. He said there are three specific grades: HC500 for thin films; HC1400; and HC2000, for thicker films such as agricultural film. n Papers from the recent Polyethylene Films conference, organised by AMI, are now available. Contact Alexandra Fish on +44 (0) 117 314 8111 (
alexandra.fish@
ami.international) for more details.
Stable performance At K2019 last year, there were several additive innovations to boost recycled polyolefins. Clariant showed its AddWorks PKG 906 Circle
stabiliser. It allows producers of polyolefin films to increase the reuse of recyclate in their products – such as their own reground scrap – without any loss of performance or processing efficiency. It is particularly well-suited for BOPP film, says
Clariant, but is also applicable to cast and blown film processes. With Clariant’s additive, the reuse content of the post-production waste in the final film can be increased by up to 30%, the company says. At the same time, the additive protects the resin
so that film quality is maintained – with significant reduction of gel formation and prevention of additional yellowing at high line speeds. AddWorks PKG 906 Circle helps to make plastic
waste reusable, without compromising packaging film quality – and increases the efficiency of the manufacturing process, says Clariant.
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