Polyolefin additives | markets feature
Polyolefins are the most widely used of all plastics, and rely on a host of additives – from light stabilisers to anti-static agents – to ensure optimum performance. Lou Reade reports
Adding value to polyolefins
Additives are usually credited with helping plastics to push into new areas of application – by enhancing their physical properties, for example. However, it can also be the case that a polymer helps an additive become more widely adopted. Sunshow, a speciality chemicals company in China,
has developed a new type of hindered amine light stabiliser (HALS) that is encapsulated in porous polypro- pylene. Sunovin 5513PP was developed by mixing its Sunovin 5513 liquid light stabiliser into extrusion-foamed PP. In this way, it has broadened the use of low-alkaline liquid light stabilisers from liquid to solid polymer. HALS additives traditionally contain an N-H chemical
group, which can react with acidic agents in polymers. It is not usually suitable for acidic polymer compounds like PVC and polycarbonate, or others that contain flame retardants. Sunovin 5513, on the other hand, is an ester-class polymer with an N-OR structure. Sunshow says that it can avoid reactions with acidic
ingredients in compounds, and could therefore minimise ageing defects such as cracking, gloss reduction and chalking of clear coatings. Incorporating the additive into porous PP then improves its stability – allowing Sunovin 5513PP to be used in polymer acid compounds, says the company.
www.filmandsheet.com Compounds were prepared, in which the HALS
content was 20, 40, 50 and 60%, then tested using thermogravimetric analysis (TGA). The tests showed that the compounds had higher thermal stability than pure Sunovin 5513. Ageing resistance tests showed that the compound had superior anti-light ageing effects. Sunshow present- ed the results at this year’s Antec conference in the USA.
Silicone slip Dow Corning says that its MB25-035 Masterbatch, which can reduce the coefficient of friction (COF) in high-speed form-fill-seal (FFS) packaging operations. The silicone-based formulation was developed as an
alternative to organic additives, whose slip performance can degrade over time, and at elevated temperatures. Used as a slip additive for low-density polyethylene (LDPE) blown film, the masterbatch only needs to be incorporated in the outside layer of the film – unlike organics, which are used in all layers. This saves money and prevents migration into package contents. It also prevents die build-up and gel deposition, and disperses easily and completely for optimal slip performance, says the company. Dow Corning says that organic slip additives such as
October 2016 | FILM & SHEET EXTRUSION 17
Dow Corning’s new master- batch cuts
friction in FFS packaging operations
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