additives | Film applications
Figure 4: Product characteristics for a range of mineral additives suitable for enhancing film blocking and optical properties Product
Trefil 1313-400 Trefil 1313-600 Sikron SF 4000 anhydrite
d50 [µm]
Hardness (Mohs) Density [g/cm3] Brightness
Fe2O3 [weight %] 6
3.5 3.0
Y=85 0.1
Source: HPF The Mineral Engineers
applications can be challenging in terms of slip and antiblocking as well as antistatic performances when adding conventional polyethylene-based masterbatch- es, as their mode of action is influenced by the polarity of these resins or their properties like stickiness,” the company says. For this reason, it has developed masterbatches optimised for performance in EVA and ionomers resins.
Below: Pumice has been shown to provide good film antiblock and haze performance
Tackling blocking Mitsui Plastics describes its Silton antiblock as a standard in Asia for LLDPE film producers requiring good anti-block performance together with high clarity and gloss and low haze. The synthetic zeolite-based additive is said to work well with both migratory and non-migratory slip agents, including erucamide and polydimethylsiloxane (PDMS). Due to its narrow particle size distribution, round particle shape and relatively high bulk density, the additive is easy to feed and disperse. Silton particle sizes range from 2-7 microns as stand- ard, with most industry applications using 3 and 5 micron grades based on film thickness and application. As a result of its high clarity and gloss and low haze,
Silton is currently used predominantly in food, cosmet- ics and medical packaging film applications, according to Mitsui, where it is said to outperform talc, DE (diatomaceous earth) and synthetic silica. The company
claims that the Silton antiblock produces 50-60% less haze in films when compared to synthetic silica. In a blown Dowlex 2045 LLDPE film application, it says clarity and gloss was held to within 2% and 1% of the unmodified resin while haze was only affected by 0.1% (Figure 3). Functional high performance additives based on
mineral raw materials are also highly suitable for influencing various properties of plastic films, according to HPF The Mineral Engineers. Among various studies the company has carried out recently was one exploring packaging films with anti-blocking and good optical properties. It compared its Trefil anhydrite (a waterless sulphate), Sikron cristobalite (based on pure silica), Microspar potash feldspar, and pumice. HPF says the effectiveness of the anti-blocking
additive is mainly dependent on the properties of the mineral used and the grain size, so the study included Trefil anhydrite and pumice grades with different average particle sizes. It looked at Trefil 1313-400 and 1313-600, Sikron SF 4000, Microspar 1380-600 and Pumice NCS Grade 3 and Grade 8 (Figure 4). The company concluded that Trefil 1313-600 offered
very good anti-blocking properties but does not do so well on appearance; Sikron SF 4000 showed good values on antiblocking and optical properties; Microspar 1380-600 exhibited the lowest haze and offered very good anti-blocking values; while Pumice NCS Grade 3 and 8 showed both good anti-blocking values and low haze.
Click on the links for more information: ❙
www.akzonobel.com ❙
www.adeka.co.jp ❙
www.pcc-chemax.com ❙
www.palsgaard.com ❙
www.polyone.com ❙
www.polyfilcorp.com ❙
www.polymerdynamix.com ❙
www.ampacet.com ❙
www.mitsuiplastics.com ❙
www.hpfminerals.com
58 COMPOUNDING WORLD | January 2017
www.compoundingworld.com
anhydrite 3
3.5 3.0
Y=89 0.1
6.5
2.35 Y=97 0.03
Microspar
cristobalite 1380-600 feldspar 5
3
6.0 2.6
Y>90 0.05
Pumice NCS Pumice NCS Grade 3
3.6
n.b. 6
Y = 93 1
Grade 8 8.5
n.b. 6
Y = 92 1
PHOTO: HPF MINERALS
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