HS Code for CIIR rubber

CIIR rubber, or Chlorinated Isobutene-Isoprene Rubber (commonly known as Chlorobutyl), is classified under HS code 4002.39. This classification is found in Chapter 40, which covers rubber and articles thereof. Within the 4002 heading for synthetic rubber, sub-heading 4002.31 covers regular isobutene-isoprene (butyl) rubber (IIR), while 4002.39 is the "other" category that specifically captures the halo-isobutene-isoprene derivatives, including both CIIR and BIIR (Bromobutyl). The classification is determined by the chemical modification of the base polymer; the addition of chlorine atoms to the butyl rubber backbone provides the material with unique properties such as faster cure rates and better adhesion to other rubbers. To be classified here, the material must be in primary forms like bales, blocks, or sheets, and must not yet be vulcanized or compounded with fillers.

Products Included

• Chlorobutyl rubber in primary forms
• CIIR synthetic rubber bales
• Unvulcanized chlorinated isobutene-isoprene sheets
• Halo-isobutene-isoprene rubber (CIIR)
• Chlorinated butyl rubber crumbs

Common Misclassification

The most frequent misclassification is using 4002.31, which is reserved for standard, non-halogenated butyl rubber (IIR). Another error involves 4002.99 for "other" synthetic rubbers, but since CIIR is a specific halo-derivative of IIR, 4002.39 is the legally correct specific sub-heading. If the rubber is already mixed with carbon black or silica, it must be moved to 4005 (compounded rubber).

FAQ

What is the HS code for CIIR rubber?

The HS code for CIIR (Chlorobutyl) rubber is 4002.39.

Is Bromobutyl rubber (BIIR) classified under the same code?

Yes, both Chlorobutyl (CIIR) and Bromobutyl (BIIR) fall under the halo-isobutene-isoprene rubber category of 4002.39.