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177.2415 Poly(aryletherketone) resins
Poly（aryletherketone resins identified in paragraph （a of this section may be safely used as articles or components of articles intended for repeated use in contact with food subject to the provisions of this section.
（a Identity. For the purposes of this section, poly（aryletherketone resins are poly（p -oxyphenylene p -oxyphenylene p -carboxyphenylene resins （CAS Reg. No. 29658-26-2 produced by the polymerization of hydroquinone and 4,4-difluorobenzophenone, and have a minimum weight-average molecular weight of 12,000, as determined by gel permeation chromatography in comparison with polystyrene standards, and a minimum mid-point glass transition temperature of 142 C, as determined by differential scanning calorimetry.
（b Optional adjuvant substances. The basic resins identified in paragraph （a may contain optional adjuvant substances used in their production. These adjuvants may include substances described in 174.5（d of this chapter and the following:
| Substance | Limitations |
| Diphenyl sulfone | Not to exceed 0.2 percent by weight as a residual solvent in the finished basic resin. |
（c Extractive limitations. The finished food contact article, when extracted at reflux temperatures for 2 hours with the following four solvents, yields in each extracting solvent net chloroform soluble extractives not to exceed 0.05 milligrams per square inch of food contact surface: Distilled water, 50 percent （by volume ethanol in distilled water, 3 percent acetic acid in distilled water, and n -heptane. In testing the final food contact article, a separate test sample shall be used for each extracting solvent.
[63 FR 20315, Apr. 24, 1998]
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