§177.1050 用丁二烯/苯乙烯高弹性体改性的丙烯�?苯乙烯共聚物

��177.1050 Acrylonitrile/styrene copoly-mer modified with butadiene/styrene elastomer

　　 Acrylonitrile/styrene copolymer modified with butadiene/styrene elastomer identified in this section may be safely used as a component of bottles intended for use with foods identified in table I of �� 176.170（c� of this chapter as Type VI-B under conditions for use E, F, or G described in table 2 of �� 176.170（c� of this chapter.

　　（a� Identity. For the purpose of this section, acrylonitrile/styrene copoly- mer modified with butadiene/styrene elastomer consists of a blend of:

　　�?� 82-88 parts by weight of a matrix copolymer produced by polymerization of 77-82 parts by weight of acrylonitrile and 18-23 parts of styrene; and

　　�?� 12-18 parts by weight of a grafted rubber consisting of （i� 8-12 parts of butadiene/styrene elastomer containing 77-82 parts by weight of butadiene and 18-23 parts by weight of styrene and （ii� 4-6 parts by weight of a graft copolymer consisting of 70-77 parts by weight of acrylonitrile and 23-30 parts by weight of styrene.

　　（b� Adjuvants. The modified copoly-mer identified in paragraph （a� of this section may contain adjuvant substances required in its production. Such adjuvants may include substances generally recognized as safe in food, substances used in accordance with prior sanction, substances permitted under applicable regulations in this part, and the following:

　　（c� Specifications. �?� Nitrogen content of the modified copolymer is in the range of 17.7-19.8 percent.

　　�?� Intrinsic viscosity of the matrix copolymer in butyrolactone is not less than 0.5 deciliter/gram at 35 ��C, as determined by the method titled ��Molecular Weight of Matrix Copolymer by Solution Viscosity,�� which is incorporated by reference. Copies 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.

　　�?� Residual acrylonitrile monomer content of the modified copolymer articles is not more than 11 ppm as determined by a gas chromatographic method titled ��Determination of Residual Acrylonitrile and Styrene Monomers-Gas Chromatographic Internal Standard Method,�� which is incorporated by reference. Copies 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.

　　（d� Extractives limitations. The following extractives limitations are determined by an infrared spectro-photo-metric method titled ��Infrared Spectro-photo-metric Determination of Polymer Extracted from Borex ? 210 Resin Pellets,�� which is incorporated by reference. Copies 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. Copies are applicable to the modified copolymers in the form of particles of a size that will pass through a U.S. Standard Sieve No. 6 and that will be held on a U.S. Standard Sieve No. 10:

　　�?� The extracted copolymer shall not exceed 2.0 ppm in aqueous extract obtained when a 100-gram sample of copolymer is extracted with 250 milliliters of freshly distilled water at reflux temperature for 2 hours.

　　�?� The extracted copolymer shall not exceed 0.5 ppm in n- heptane when a 100-gram sample of the basic copol-ymer is extracted with 250 milliliters spectral grade n- heptane at reflux temperature for 2 hours.

　　（e� Accelerated extraction end test. The modified copolymer shall yield acrylonitrile monomer not in excess of 0.4 ppm when tested as follows:

　　�?� The modified copolymer shall be in the form of eight strips 1/2 inch by 4 inches by .03 inch.

　　�?� The modified copolymer strips shall be immersed in 225 milliliters of 3 percent acetic acid in a Pyrex glass pressure bottle.

　　�?� The pyrex glass pressure bottle is then sealed and heated to 150 ��F in either a circulating air oven or a thermostat controlled bath for a period of 8 days.

　　�?� The Pyrex glass pressure bottle is then removed from the oven or bath and cooled to room temperature. A sample of the extracting solvent is then withdrawn and analyzed for acrylonitrile monomer by a gas chromatographic method titled ��Gas-Solid Chromatographic Procedure for Determining Acrylonitrile Monomer in Acrylonitrile-Containing Polymers and Food Simulating Solvents,�� which is incorporated by reference. Copies, 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.

　　（f� Acrylonitrile copolymers identified in this section shall comply with the provisions of �� 180.22 of this chapter.

　　（g� Acrylonitrile copolymers identified in this section are not authorized to be used to fabricate beverage containers.

　　　　[42 FR 14572, Mar. 15, 1977, as amended at 42 FR 48544, Sept. 23, 1977; 47 FR 11841, Mar. 19, 1982; 47 FR 16775, Apr. 20, 1982; 54 FR 24898, June 12, 1989]