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Antiblock Additives

21

Joerg Ulrich Zilles

Contents

Definition........................................................................................ 426

Introduction...................................................................................... 426

Key Information................................................................................. 426

Light and Thermal Management in Agricultural Films........................................ 433

References....................................................................................... 437

Abstract

Anti-blocking is a term used to describe measures to prevent film sheets to stick together. Polyolefin films tend to adhere to each other due to strong van der Waals interaction or electrostatic charges when being in close contact (adjacent layers). The higher the temperature, pressure, and contact/processing time, the higher the tendency to stick to each other.

To avoid the adherence of layers due to a close contact, particulate matter is introduced into the film in a highly diluted concentration. By that measure a micro-rough surface is created, and contact area of film layers is minimized; the distance between the layers is maximized and adherence suppressed. Minerals used for that application should have little to no impact on the mechanical properties of the film; must not deteriorate transparency, haze, color, gloss of the film; and should be compatible with the film-processing process. Several minerals are used for this purpose: talc, calcined kaolin, cristobalite, precipitated silica, diatomaceous earth, mica, calcium carbonates, calcium sulfate (anhydrite), magnesium carbonate, magnesium sulfate, and feldspars.

Organic alternatives used for anti-blocking or anti-stick are amides, fatty acid amides, fatty acids, salts of fatty acids, silicones, or others. They work with

J.U. Zilles (*)

Quarzwerke GmbH, Frechen, Germany e-mail: This email address is being protected from spam bots, you need Javascript enabled to view it

© Springer International Publishing Switzerland 2017

R. Rothon (ed.), Fillers for Polymer Applications, Polymers and Polymeric Composites: A Reference Series, DOI 10.1007/978-3-319-28117-9_15

different mechanisms compared to the inorganic anti-blocking additives, migrating to the film surface upon cooling and forming a release layer. Sometimes combinations of inorganic and organic anti-blocking additives are used. Organic additives typically have lower anti-blocking ability in comparison to the inorganic ones but better slip effect.

This entry summarizes the mechanisms of anti-blocking and subsumes results from literature on that subject with an emphasis on the mineral anti-blocking additives.

Keywords

Feldspar • Cristobalite • Nepheline syenite • Film • Anti-blocking • Greenhouse

Definition

Anti-blocking describes measures to minimize adhesion of adjacent polymer film layers to each other.

Introduction

Anti-blocking is a term used to describe measures to prevent film sheets from sticking together. Different strategies are used to achieve anti-blocking, i.e., increasing roughness to decrease contact area between layers by adding mineral particles into the polymer or using slip additives allowing the sheets to slide easily against each other by organic molecules diffusing to the surface. This entry summarizes the mechanisms of anti-blocking and subsumes results from literature on that subject with an emphasis on the mineral anti-blocking additives.

 
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