Antiblocking agents, polymers

Peloso, C.W. et al. (1998), Characterising the degradation of the polymer slip additive erucamid in the presence of inorganic antiblock agents, Polym. Degrad. Stab., 62 (2), 285-290. 

Additives. Compounds are often added to the polymer at the extmder or melt homogenizer. Common additives are antioxidants (qv), thermal stabilizers, sHp agents, antiblock agents, anduv stabilizers. Popular antioxidants are 2,6-di-/-butyl-/)-cresol (BHT), octadecyl... 

On a related theme, we can take advantage of the diffusion of molecules incorporated into a polymer to its surface. Thus we can blend lubricants, bactericides, and antiblock agents into polymers, which slowly exude to the surface where they perform a useful role. 

There are at least five types of synthetic silicas that can be considered for use in polymers. These are generally known as fumed, arc, fused, gel and precipitated. A detailed review of their production and uses has been given by Watson [96]. The types most often encountered in thermoplastics are the gel and precipitated silicas which are frequently used as antiblocking agents in polymer films and as gloss reducing agents in polymer sheets. 

The presence of stabilizer has little effect on poly (vinyl chloride) carboxylation (Table VIII). Since the other polymers were also subjected to the carboxylation process without removing commercial additives such as antioxidants, UV and thermal stabilizers, antiblocking agents, etc.—the additives inhibit neither the polymerization of the styrene-maleic anhydride complex nor the grafting reaction. 

Crodamide. [Croda Universal Ltd.] Fatty acid amides slip and antiblock agents for polyolefins release agent for molded thermoplastic polymers. 

When antiblocking agents are incorporated into PE films, other important properties of the polymer are also affected. These include an increase in stiffness, a decrease in the coefficient of friction, and an increase in haze. Interaction effects with processing aids can also result, especially with fluorocarbon elastomers that are added to prevent melt fracture in the blowing process of films. Worker exposure to dust generated by these additives can be hazardous if impurities such as crystalline silica or asbestos are present. 

Slip agents are related to antiblocking agents, but instead of decreasing surface contact, they reduce blocking by introducing a thin, low-friction coating between the plastic materials. These additives are usually mixed into the polymer film, but... 

Uses Wax for polishes, esp. dry-bright emulsions antiblocking agent for polymer dispersions wax for citrus fmit coating emulsions Properties YIsh. flakes insol. in water dens. 1.00-1.02 g/cc (20 C) vise. 30 mmVs (100 C) drop pt. 80-85 C acid no. 30-40 sapon. no. 135-150... 

Antiblocking agents are additives that inhibit the stickiness (blocking) of polymer surfaces. Blocking is most apparent in films, particularly blown films. After a blown film bubble has passed through the nip roller and the two halves have been pressed together, they may tend to block. Antiblocks help the film to be easily pulled apart. Diatomaceous earth is a commonly used antiblock additive. 

Chuayjuljit, S. et al. (2003), Use of Silica from Rice Husk Ash as an Antiblocking Agent in Low-Density Polyethylene Film, J. Appl. Polym. Sci., 88 (3), 848-852. 

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