Antiblocking agents incorporation

Colloidal silica from various origins or chalk or other fine-particle fillers are normally added. If the particles of antiblocking agent incorporated are too large, they can impede surface sliding. This effect is used for antislip modification. The products used here are high molecular weight thermoplastics or elastomers [33] predispersed in a suitable carrier, they form evenly distributed particles on the film surface [34]. 

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. 

Antiblock Agent. Antiblocking is the prevention of the adhesion of two plastic films in contact with one another. This effect can be achieved by incorporating fine silica particles in the surface of the film. The relatively low refractive index of silica makes the particles less easy to see. 

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. 

Secondary monoamides particularly are preferred. A particularly preferred secondary monoamide is N-oleyl palmitamide, an amide with a double bond geometry. Preferably the amide is incorporated into the plasticized PVB at a concentration of 0.1-0.3%. The glass adhesion of a PVB sheet produced from the formulated pellets is substantially unaffected by the presence of the amide antiblocking agent. 

Apart from packaging applications, another opportunity for antiblocking agents is in medical gloves. The users traditionally employ talc or a similar powder to facilitate donning, but some recent designs have incorporated an antiblocking composition. 

Years ago, efforts were made to provide antiblocking by dusting the surface with cornstarch or silica. This process was abandoned because of potential health concerns. Antiblocking agents are now melt incorporated into the thermoplastic either via direct addition or by use of a master batch. 

In many cases blocking may be counteracted by incorporation of antiblocking agents in the plastic. These are generally fine-particle silicas and silicates or certain paraffin and waxes. Where applicable, suitable modification of processing conditions... 

Antiblocking Agent (Antiblock) An additive that is incorporated into resins and compounds to prevent surfaces of products (mainly films) from sticking to each other or to other surfaces. The term is not generally used for coatings, dusts, or sprays applied to surfaces for... 

In PE, oleic acid amide is normally used, while in PP erucamide is preferred. Slip agents are added mainly to film grades at a concentration of 0.1%. The additive is incorporated either by the polymer manufacturer in a pelletizing extruder or by the processor in the form of a master batch. In the latter instance, it is possible to combine the slip agent in any desired ratio with an antiblocking agent and to adjust specifically the slip effect of the finished products. 

In ccnqparison with other antiblocking agents, Sipemat 44 is relatively readily dispersible. Mevertheless, it is advisable to Incorporate Sipemat 44, too, according to one of the usual methods (in most cases knsader) to a masterbatch (concentrate). 

Antiblock and slip agents can be incorporated together using combination master batches which give the film extruder greater formulation control. 

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