3912.31.00 - Carboxymethylcellulose and its salts

This HTS category, 3912.31.00, specifically covers carboxymethylcellulose (CMC) and its various salt forms. Carboxymethylcellulose is a cellulose ether derived from cellulose through chemical modification, where carboxymethyl groups are introduced. It is a water-soluble polymer commonly found in powder, granular, or solution form and is widely utilized across numerous industries due to its thickening, stabilizing, binding, and film-forming properties.

At this level of the HTS, 3912.31.00 is distinguished from its sibling category, 3912.39.00, which is designated for "Other" cellulose ethers. Therefore, classification under 3912.31.00 is exclusive to products that are definitively carboxymethylcellulose or its salts, whereas 3912.39.00 would encompass other types of cellulose ethers not specifically listed elsewhere.

The subcategories within 3912.31.00 provide further granularity based on the concentration of carboxymethylcellulose. 3912.31.00.10 is reserved for products containing a high percentage of CMC, specifically not less than 90 percent by weight. The remaining products, 3912.31.00.90, fall under "Other," likely representing formulations or mixtures where CMC is present but does not meet the high-purity threshold of the preceding subcategory. These distinctions are crucial for accurate duty assessment and trade statistics.