Isobutene-isoprene (butyl) rubber (IIR)

1. Except where the context otherwise requires, throughout the Nomenclature the expression 'rubber' means the following products, whether or not vulcanised or hard: natural rubber, balata, gutta-percha, guayule, chicle and similar natural gums, synthetic rubber, factice derived from oils, and such substances reclaimed. 2. This chapter does not cover: (a) goods of Section XI (textile materials and textile articles); (b) footwear or parts of footwear of Chapter 64; (c) headgear or parts thereof (including bathing caps) of Chapter 65; (d) mechanical or electrical appliances or parts thereof of Section XVI (including electrical goods of all kinds), of hard rubber; (e) articles of Chapters 90, 92, 94 or 96; (f) articles of Chapter 95 (other than sports gloves, mittens and mitts and articles of headings 4011 to 4013). 3. In headings 4001 to 4003 and heading 4005, the expression 'primary forms' applies only to the following forms: (a) liquids and pastes (including latex, whether or not pre-vulcanised, and other dispersions and solutions); (b) blocks of irregular shape, lumps, bales, powders, granules, crumbs and similar bulk forms. 4. In Note 1 to this chapter and in heading 4002, the expression 'synthetic rubber' applies to: (a) unsaturated synthetic substances which can be irreversibly transformed by vulcanisation with sulphur into non-thermoplastic substances which, at a temperature between 18 and 29 degrees Celsius, will not break on being extended to three times their original length and will return, after being extended to twice their original length, within a period of five minutes, to a length not greater than one and a half times their original length. For the purposes of this test, substances necessary for the cross-linking, such as vulcanising activators or accelerators, may be added; the presence of substances as provided for by Note 5(B)(ii) and (iii) is also permitted. However, the presence of any substances not necessary for the cross-linking, such as extenders, plasticisers and fillers, is not permitted; (b) thioplasts (TM); (c) natural rubber modified by grafting or mixing with plastics, depolymerised natural rubber, mixtures of unsaturated synthetic substances with saturated synthetic high polymers provided that all the above-mentioned products comply with the requirements concerning vulcanisation, elongation and recovery in (a) above.