SUPPLEMENTARY INFORMATION:

Request To Add Substance to the List

(a) Overview. A petition was filed pursuant to Rev. Proc. 2022-26 (2022-29 I.R.B. 90), as modified by Rev. Proc. 2023-20 (2023-15 I.R.B. 636), requesting that sSBR be added to the list of taxable substances under section 4672(a) of the Internal Revenue Code (List). The petition requesting the addition of sSBR to the List is based on weight and contains the information detailed in paragraph (b) of this document. The information is provided for public notice and comment pursuant to section 9 of Rev. Proc. 2022-26. The publication of petition information in this notice of filing is not a determination and does not constitute Treasury Department or IRS confirmation of the accuracy of the information published.

(b) Petition Content.

(1) Substance name: Solution styrene butadiene rubber ((C₄ H₆)_m -(C₈ H₈)_n -(C₂₅ H₄₄ OS₂)_a; m=5,474.21, n=504.08, a=3.30).

The substance is also known as sSBR.

(2) Petitioner: Zeon Chemicals L.P. is an importer and exporter of sSBR.

(3) Proposed classification numbers:

(i) HTSUS number: 4002.19.0016.

(ii) Schedule B number: 4002.19.1600.

(iii) CAS number: 9003-55-8.

(4) Petition filing dates:

(i) Petition filing date for purposes of making a determination: November 21, 2025.

(ii) Petition filing date for purposes of section 11.02 of Rev. Proc. 2022-26, as modified by section 3 of Rev. Proc. 2023-20: April 1, 2023.

(5) Description from petition: sSBR is a general-purpose synthetic rubber derived from butadiene and styrene. sSBR is used in the production of tires, and other rubber parts like gaskets and conveyor belts. sSBR is made from butadiene, benzene, ethylene, propylene, methane, and sodium hydroxide. Taxable chemicals constitute 99.11 percent by weight of the materials used to produce this substance.

(6) Process identified in petition as predominant method of production of substance: The predominant method of producing sSBR is through the termination-free, anionic solution polymerization of butadiene and styrene initiated by alkyl lithium compounds in a hydrocarbon solvent, usually hexane or cyclohexane. Styrene monomer is produced by the dehydrogenation of ethylbenzene. Ethylbenzene is produced via a Friedel-Crafts reaction of benzene and ethylene. Phenol, 2-methyl-4,6-bis[(octylthio)methyl] is produced by reacting o-cresol, 1-octanethiol, and formaldehyde. o-Cresol is produced from the methylation of phenol using methanol. Methanol is made from syngas. Hydrogen is produced from steam-methane reforming. 1-Octanethiol ( printed page 57448) is produced by from halogen substituted octane and sodium hydrosulfide. Halogen substituted octane is produced by reacting octane and a halogen ( e.g., iodine). Sodium hydrosulfide is produced by the reaction of sodium hydroxide with hydrogen sulfide. Formaldehyde is produced by the catalytic oxidation of methanol.

(7) Stoichiometric material consumption equation, based on process identified as predominant method of production: m C₄ H₆ (butadiene) + n [C₆ H₆ (benzene) + C₂ H₄ (ethylene)] + a [C₆ H₆ (benzene) + C₃ H₆ (propylene) + 3/2 CH₄ (methane) + 2 NaOH (sodium hydroxide) + 2 O₂ (oxygen) + 3 CO (syngas) + 2 C₈ H₁₈ (octane) + 2 I₂ (iodine) + 2 H₂ S (hydrogen sulfide)] → (C₄ H₆)_m -(C₈ H₈)_n -(C₂₅ H₄₄ OS₂)_a (sSBR) + n H₂ + a C₃ H₆ O (acetone) + 3/2 a CO₂ + 4a H₂ O + 2a HI + 2a NaI.

(8) Tax rate calculated by Petitioner, based on Petitioner's conversion factors for taxable chemicals used in production of substance:

(i) Tax rate: $9.75 per ton.

(ii) Conversion factors: 0.85 for butadiene, 0.11 for benzene, 0.04 for ethylene, 0.0004 for propylene, 0.0002 for methane, and 0.0008 for sodium hydroxide.

(9) Public docket number: IRS-2026-1030.

91 FR 57447