[Code of Federal Regulations]
[Title 21, Volume 3]
[Revised as of April 1, 2004]
From the U.S. Government Printing Office via GPO Access
[CITE: 21CFR177.1420]

[Page 268]
 
                        TITLE 21--FOOD AND DRUGS
 
CHAPTER I--FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN 
                          SERVICES (CONTINUED)
 
PART 177_INDIRECT FOOD ADDITIVES: POLYMERS--Table of Contents
 
Subpart B_Substances for Use as Basic Components of Single and Repeated 
                        Use Food Contact Surfaces
 
Sec. 177.1420  Isobutylene polymers.

    Isobutylene polymers may be safely used as components of articles 
intended for use in producing, manufacturing, packing, processing, 
preparing, treating, packaging, transporting, or holding food, in 
accordance with the following prescribed conditions:
    (a) For the purpose of this section, isobutylene polymers are those 
produced as follows:
    (1) Polyisobutylene produced by the homopolymerization of 
isobutylene such that the finished polymers have a molecular weight of 
750,000 (Flory) or higher.
    (2) Isobutylene-isoprene copolymers produced by the copolymerization 
of isobutylene with not more than 3 molar percent of isoprene such that 
the finished polymers have a molecular weight of 300,000 (Flory) or 
higher.
    (3) Chlorinated isobutylene-isoprene copolymers produced when 
isobutylene-isoprene copolymers (molecular weight 300,000 (Flory) or 
higher) are modified by chlorination with not more than 1.3 weight-
percent of chlorine.
    (b) The polymers identified in paragraph (a) of this section may 
contain optional adjuvant substances required in the production of the 
polymers. The optional adjuvant substances required in the production of 
the polymers may include substances generally recognized as safe in 
food, substances used in accordance with a prior sanction or approval, 
and aluminum chloride.
    (c) The provisions of this section are not applicable to 
polyisobutylene used in food-packaging adhesives complying with Sec. 
175.105 of this chapter.