§177.1560 Polyarylsulfone resins
Polyarylsulfone resins （CAS Reg. No. 79293-56-4） may be safely used as articles or components of articles intended for use in contact with food, at temperatures up to and including normal baking temperatures, in accordance with the following prescribed conditions:
（a） Identity. Polyarylsulfone resins are copolymers containing not more than 25 percent of oxy-p -phenylene-oxy-p -phenylenesulfonyl-p- phenylene polymer units and not less than 75 percent of oxy-p -phenylenesulfonyl-p -phenylene-oxy-p -phenylenesulfonyl-p -phenylene polymer units. The copolymers have a minimum reduced viscosity of 0.40 deciliter per gram in 1-methyl-2-pyrrolidinone in accordance with ASTM method D2857-70 （Reapproved 1977）, “Standard Test Method for Dilute Solution Viscosity of Polymers,” which is incorporated by reference. Copies may be obtained from the American Society for Testing and Materials, 100 Barr Harbor Dr., West Conshohocken, Philadelphia, PA 19428-2959, or may be examined at the National Archives and Records Administration （NARA）. For information on the availability of this material at NARA, call 202-741-6030, or go to:http://www.archives.gov/federal_register/code_of_federal_regulations/ibr_locations.html.
（b） Optional adjuvant substances. The basic polyarylsulfone resins identified in paragraph （a） of this section may contain optional adjuvant substances required in the production of such basic copolymers. These optional adjuvant substances may include substances permitted for such use by regulations in parts 170 through 179 of this chapter, substances generally recognized as safe in food, substances used in accordance with a prior sanction of approval, and substances named in this paragraph and further identified as required:
| Substances | Limitations |
| Sulfolane | Not to exceed 0.15 percent as residual solvent in the finished basic resin. |
（c） Extractive limitations. The finished polyarylsulfone resin when extracted for 2 hours with the following solvents at the specified temperatures yields total extractives in each extracting solvent not to exceed 0.008 milligram per square centimeter of food-contact surface: distilled water at 121 °C （250 °F）, 50 percent （by volume） ethyl alcohol in distilled water at 71.1 °C （160 °F）, 3 percent acetic acid in distilled water at 100 °C （212 °F）, and n- heptane at 65.6 °C （150 °F）.
Note: In testing the finished poly-aryl-sulfone resin use a separate test sample for each required extracting solvent.
[50 FR 31046, July 24, 1985]
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