 | Nitrocellulose is produced by causing cellulose to react with nitrating acid (a mixture of nitric acid and sulfuric acid). Following complex washing and stabilizing stages, damping agents (alcohols or water) or plasticizers are added to the nitrocellulose which is then marketed as Walsroder Nitrocellulose or Walsroder NC-Chips.
The schematic flow chart gives an outline of the individual stages of the process.
The raw material used for producing Walsroder Nitrocellulose and Walsroder NC-Chips is carefully selected and well-characterized types of cellulose, the exact specifications having been agreed with the cellulose suppliers. Compliance with these specifications is regularly checked during incoming goods inspections. This also applies to all other raw materials, thus assuring the consistent quality of Walsroder Nitrocellulose and Walsroder NC-Chips.
The cellulose is caused to react with the nitrating acid (a mixture of nitric acid and sulfuric acid) in the nitrating process. A new nitrating plant came on stream at Dow Wolff Cellulosics in 1996. It is a state-of-the-art production unit incorporating 125 years of nitrocellulose manufacturing experience.
After nitration, centrifuges separate the nitrocellulose from the spent nitrating acid used in excess quantities. This spent nitrating acid is separated into nitric acid, sulfuric acid and water, and completely recycled back into the process.
The next stage is the pre-stabilization stage where the nitrocellulose is washed with water, thus separating off any acid left on the fibres. Next, the viscosity of the nitrocellulose is adjusted by pressure boiling (heating under pressure to temperatures above 100°C).
This is followed by the post-stabilization stage where the nitrocellulose is washed with water and heated to temperatures below 100°C. The water is subsequently separated off to leave a water content of 35%. This water-wet nitrocellulose can then be packaged. To produce alcohol-damped Walsroder Nitrocellulose, the water is replaced with the appropriate damping alcohol. To produce Walsroder NC-Chips, the appropriate plasticizer is added to water-wet nitrocellulose which is then dried.
In the course of the entire production process all relevant properties of the nitrocellulose and of the process are constantly monitored to ensure the consistent high quality of Walsroder Nitrocellulose and Walsroder NC-Chips.
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