Viscose process means the following:
(1) A manufacturing process that includes the following process steps:
(i) Reaction of cellulose (e.g., wood pulp) with sodium hydroxide to produce alkali cellulose;
(ii) Reaction of alkali cellulose with carbon disulfide to produce sodium cellulose xanthate;
(iii) Combination of sodium cellulose xanthate with additional sodium hydroxide to produce viscose solution;
(iv) Extrusion of the viscose into various shapes (e.g., hollow casings, thin fibers, thin sheets, molds);
(v) Regeneration of the cellulose product;
(vi) Washing of the cellulose product; and
(vii) Possibly acid or salt recovery.
(2) The cellulose products manufactured using the viscose process include cellulose food casings, rayon, cellulosic sponges, and cellophane.
40 CFR § 63.5610
For all affected sources complying with the batch process vent testing provisions in 63.490(c) and the operating limit provisions in 63.505(c), the terms used in this subpart and in subpart U of this part are defined in 63.482 and paragraph (g) of this section.