Molding better products

Praxair's Laminar Barrier Inerting (LBI) technology for the chemical industry is an innovative technique that involves the application of a layer of gaseous nitrogen at the surface of molded plastics and films during the thermoforming process. This reduces thermal, oxidative and hydrolytic degradation. Praxair's inerting systems help chemical manufacturers produce molded parts and plastic films with significantly higher surface quality and reduced scrap rates.

The process of LBI occurs when a laminar flow of gas across an opening forms a barrier that prevents air and unwanted gases from infiltrating the enclosure, typically a furnace. Diffusers, placed on two sides of the opening of an induction furnace, consist of a gas inlet, a plenum chamber, and a porous face. The gas is introduced into the plenum chamber and flows out through the porous face as an evenly distributed, low-velocity flow. Although air and unwanted gases are prevented from passing into the furnace, solid objects can easily pass through the laminar barrier without creating turbulence.

LBI systems typically use argon to create the barrier. However, nitrogen may be used if nitrogen pick-up in the melt can be tolerated. With either gas, oxygen content of the furnace atmosphere is easily kept below 1%. Using argon as a barrier gas can keep the nitrogen content of the headspace below 4%.