§177.2400 Perfluorocarbon cured elastomers.
Perfluorocarbon cured elastomers identified in paragraph （a） of this section may be safely used as articles or components of articles intended for repeated use in contact with nonacid food （pH above 5.0）, subject to the provisions of this section.
（a） Identity. （1） For the purpose of this section, perfluorocarbon cured elastomers are produced by terpolymerizing tetrafluorethylene （CAS Reg. No. 116-14-3）, perfluoromethyl vinyl ether （CAS Reg. No. 1187-93-5）, and perfluoro-2-phenoxypropyl vinyl ether （CAS Reg. No. 24520-19-2） and subsequent curing of the terpolymer （CAS Reg. No. 26658-70-8） using the cross
（2） The perfluorocarbon base polymer shall contain no less than 40 weight-percent of polymer units derived from tetrafluoroethylene, no less than 40 weight-percent of polymer units derived from perfluoromethyl vinyl ether and no more than 5 weight-percent polymer units derived from perfluoro-2-phenoxy-propyl vinyl ether.
（3） The composition limitations of the cured elastomer, calculated as parts per 100 parts of terpolymer, are as follows:
Phenol, 4,4′-[2,2,2-trifluoro-1-（trifluoromethyl）-ethylidene] bis-,dipotassium salt—not to exceed 5 parts.
1,4,7,10,13,16-Hexaoxacyclo-octadecane—not to exceed 5 parts.
（b） Optional adjuvant substances. The perfluorocarbon cured elastomer identified in paragraph （a） of this section may contain the following optional adjuvant substances, subject to any limitations cited on their use:
（1） Substances generally recognized as safe （GRAS） in food or food packaging.
（2） Substances used in accordance with a prior sanction.
（3） Substances authorized under applicable regulations in this part and in parts 175 and 178 of this chapter and subject to any limitations prescribed therein.
（4） Substances identified in this paragraph （b）（4） subject to such limitations as are provided:
| Substances | Limitations |
| Carbon black (channel process of furnace combustion process) (CAS Reg. No. 1333-86-4) | Not to exceed 15 parts per 100 parts of the terpolymer. |
| Magnesium oxide (CAS Reg. No. 1309-48-4) | Not to exceed 5 parts per 100 parts of the terpolymer. |
（c） Specifications— （1） Infrared identification. Perfluorocarbon cured elastomers may be identified by the characteristic infrared spectra of the pyrolysate breakdown product that is obtained by heating and decomposing the elastomer using the method entitled “Qualitative Identification of Kalrez ? by Infrared Examination of Pyrolysate.” This method is incorporated by reference. Copies of the method are available from the Center for Food Safety and Applied Nutrition （HFS-200）, Food and Drug Administration, 5100 Paint Branch Pkwy., College Park, MD 20740, or available for inspection 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.
（2） Thermogravimetry. Perfluorocarbon cured elastomers have a major decomposition peak occurring at 490 ° ±15 °C （914 °F）. Less than 1.5 percent of the elastomers will volatilize below 400 °C （752 °F） when run under nitrogen at a 10 °C or 18 °F per minute heating rate using a Du Pont Thermal Analyzer Model 1099 with Model 951 TGA unit or the equivalent.
（d） Extractive limitations. Articles fabricated from perfluorocarbon cured elastomers having a thickness of at least 1.0 millimeter （0.039 inch） when extracted at reflux temperatures for 2 hours separately with distilled water, 50 percent ethanol, and n -heptane, shall meet the following extractability limits:
（1） Total extractives not to exceed 3.1 milligrams per square decimeter （0.2 milligrams per square inch）.
（2） Fluoride extractives calculated as fluorine not to exceed 0.47 milligram per square decimeter （0.03 milligram per square inch）.
（e） Conditions of use. In accordance with current good manufacturing practice, finished food contact articles containing the perfluorocarbon cured elastomers shall be thoroughly cleaned prior to their first use in contact with food.
[49 FR 43050, Oct. 26, 1984]