Polysulfone resins identified in paragraph (a) of this section may be safely used as articles or components of articles intended for use in contact with food, in accordance with the following prescribed conditions:
(a) For the purpose of this section, polysulfone resins are:
(1) Poly(oxy-
(2) 1,1′-Sulfonylbis[4-chlorobenzene] polymer with 4,4′-(1-methylethylidene)bis[phenol] (minimum 92 percent) and 4,4′-sulfonylbis[phenol] (maximum 8 percent) (CAS Reg. No. 88285–91–0) produced when a mixture of 4,4′-isopropylidenediphenol (minimum 92 percent) and 4,4′-sulfonylbis[phenol] (maximum 8 percent) is made to react with 4,4′-dichlorodiphenyl sulfone in such a way that the finished resin has a minimum number average molecular weight of 26,000, as determined by osmotic pressure in dimethylformamide.
(b) The basic polysulfone resins identified in paragraph (a) of this section may contain optional adjuvant substances required in the production of such basic resins. The optional adjuvant substances required in the production of the basic polysulfone resins may include substances described in § 174.5(d) of this chapter and the following:
(c) Polysulfone resins, when extracted at reflux temperatures for 6 hours with the solvents—distilled water, 50 percent (by volume) ethyl alcohol in distilled water, 3 percent acetic acid in distilled water, and
(d) Polysulfone resins intended for repeated use in contact with food may be used under conditions of use A through