ANTI-BLOCKING AGENT

In addition, polyester bottles may contain colorants in the form of pigments, dyes or lakes. The colorants may be dispersed or dissolved in the polymer or may be covalently bound to the polymer backbone. Polyester packaging, which may be collected for depolymerization, may include nucleators for enhanced crystallization, anti-slip agents, branching agents, anti-blocking agents and anti-stats. 

Processing aids - additives such as viscosity depressants, mold-release agents, emulsifiers, lubricants, and anti-blocking agents (3). 

Perhaps the simplest use of colloidal silica in this area is its use to firictionize and coat the film base material to both make it easier to be conveyed through the process and also to prevent it from blocking or adhering to itself when rolled up. The use of colloidal silica as an anti-blocking agent is discussed above under the Surface Modification of plastic films. 

Ternary blends contained 87-96 wt% LLDPE (with either butene-1, hexene-1, or octene-1), 1-10 wt% isotactic polybutene, 1-10 wt% PS, and 0.01-10 wt% color and anti-blocking agents. The blends exhibited improved process efficiency in terms of extruder amps/ rpm ratio, while the terpolymer substantially retained the inherent strength of the LLDPE. The compositions were used for blown films and for the manufacture of waste bags ... 

However, it is critically important to plasma clean a polymer for a sufficiently long time to remove all of the contamination from the surface. Almost all polymer films, and most molded parts, contain additives or contaminants such as oligomers, anti-oxidants, mold release agents, solvents, anti-block agents, etc. which are oils or waxes. Most of these are deliberately incorporated into the polymer formulation to improve its properties or manufacturability and are designed to bloom to the surface of the polymer and coat that surface. 

The problem is that almost all polymers have some contamination on the surface. This comes accidently fi-om handling or storage contamination, or, most importantly, fi om the diffusion of oily or waxy additives from the bulk polymer to the surface of the polymer. These additives can be antioxidents, anti-blocking agents, mold release, plasticizers, lubricants, etc. The diffusion of the additives usually cannot be stopped because they are designed to diffuse to the surface to perform their desired role. Unfortunately, when they reach the surface they cover-up the surface moieties left by the plasma treatment and the effects of that treatment may disappear. 

Multifunctional concentrate n. A plastic compound that contains high percentages of at least two of such additives as colorants, stabilizers, flame retardants, lubricants, antistatic agents, anti-blocking agents, blowing agents, fillers, etc, that will be diluted in base resin to provide a tailored compound with the desired final concentrations of the additives in the extruded or molded product. 

Anti-blocking agents reduce the tendency of layers of film to stick together in tightly wound reels or stacked sheets. The use of an anti-blocking agent may affect the performance of other additives (such as slip or anti-static). It is therefore important that a full evaluation is carried out to determine the suitability of combinations of additives. 

Combination masterbatches have been developed to give the film extruder greater control over the quantities of slip and anti-block agent in the film, with a good balance of other properties such as clarity and freedom for use in contact with food. 

Armid slip/anti-blocking agents Akzo-Nobel... 

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