Acrylonitrile/styrene copolymers identified in this section may be safely used as a component of packaging materials subject to the provisions of this section.
(a) Identity. For the purposes of this section acrylonitrile/styrene copoly-mers are basic copolymers meeting the specifications prescribed in paragraph (c) of this section.
(b) Adjuvants. (1) The copolymers identified in paragraph (c) of this section may contain adjuvant substances required in their production, with the exception that they shall not contain mercaptans or other substances which form reversible complexes with acryl-onitrile monomer. Permissible 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 those authorized in paragraph (b)(2) of this section.
(2) The optional adjuvants for the acrylonitrile/styrene copolymer identified in paragraphs (c) (1) and (3) of this section are as follows:
| Substances | Limitation |
|---|---|
| Condensation polymer of toluene sulfonamide and formaldehyde | 0.15 pct maximum. |
(c) Specifications.
| Acrylonitrile/styrene copolymers | Maximum residual acrylonitrile monomer content of finished article | Nitrogen content of copolymer | Maximum extractable fractions at specified temperatures and times | Conformance with certain specifications |
|---|---|---|---|---|
| 1. Acrylonitrile/styrene copolymer consisting of the copolymer produced by polymerization of 66-72 parts by weight of acrylonitrile and 28-34 parts by weight of styrene; for use with food of Type VI-B identified in table 1 of § 176.170(c) of this chapter under conditions of use C, D, E, F, G described in table 2 of § 176.170(c) of this chapter | 80 ppm 1 | 17.4 to 19 pct | Total nonvolatile extractives not to exceed 0.01 mg/in
2 surface area of the food contact article when exposed to distilled water and 3 pct acetic acid for 10 d at 66 °C (150 °F)
The extracted copolymer shall not exceed 0.001 mg/in 2 surface area of the food contact article when exposed to distilled water and 3 pct acetic acid for 10 d at 66 °C (150 °F) 1 | Minimum number average molecular weight is 30,000. 1 |
| 2. Acrylonitrile/styrene copolymer consisting of the copolymer produced by polymerization of 45-65 parts by weight of acrylonitrile and 35-55 parts by weigth of styrene; for use with food of Types, I, II, III, IV, V, VI (except bottles), VII, VIII, and IX identified in table 1 of § 176.170(c) of this chapter under conditions B (not to exceed 93 °C (200 °F)), C, D, E, F, G described in table 2 of § 176.170(c) of this chapter | 50 ppm 1 | 12.2 to 17.2 pct | Extracted copolymer not to exceed 2.0 ppm in aqueous extract or | Minimum 10 pct solution viscosity at 25 °C (77 °F) is 10cP. 1 |
| 3. Acrylonitrile/styrene copolymer consisting of the copolymer produced by polymerization of 66-72 parts by weight of acrylonitrile and 28-34 parts by weight of styrene; for use with food of Types VI-A and VI-B identified in table 1 of § 176.170(c) of this chapter under conditions of use C, D, E, F, G described in table 2 of § 176.170(c) of this chapter | 0.10 ppm (calculated on the basis of the weight of the acrylonitrile copolymer resin in the finished articles). 2 | 17.4 to 19 pct | Total nonvolatile extractives not to exceed 0.01 mg/in
2 surface area of the food contact article when exposed to distilled water and 3 pct acetic acid for 10 d at 66 °C (150 °F)
The extracted copolymer shall not exceed 0.001 mg/in 2 surface area of the food contact article when exposed to distilled water and 3 pct acetic acid for 10 d at 66 °C (150 °F). 1 | Maximum carbon dioxide permeability at 23 °C (73 °F) for the finished article is 0.04 barrer. 3 |
1 Use methods for determination of residual acrylonitrile monomer content, maximum extractable fraction, number average molecular weight, and solution viscosity, titled: “Determination of Residual Acrylonitrile and Styrene Monomers-Gas Chromatographic Internal Standard Method”; “Infrared Spectrophotometric Determination of Polymer Extracted from Barex 210 Resin Pellets”; “Procedure for the Determination of Molecular Weights of Acrylonitrile/Styrene Copolymers,” and “Analytical Method for 10% Solution Viscosity of Tyril,” which are incorproated by reference. Copies are available from the Center for Food Safety and Applied Nutrition (HFS-200), 5001 Campus Dr., College Park, MD 20740, 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:
2 As determined by the method titled “Headspace Sampling and Gas-Solid Chromatographic Determination of Residual Acrylonitrile in Acrylonitrile Copolyemr Solutions,” which is incorporated by reference. Copies are available from the Center for Food Safety and Applied Nutrition (HFS-200), 5001 Campus Dr., College Park, MD 20740, 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:
3 As determined on appropriately shaped test samples of the article or acrylonitrile copolymer layer in a multilayer construction by ASTM method D-1434-82, “Standard Method for Determining Gas Permeability Characteristics of Plastic Film and Sheeting,” which is incorporated by reference. Copies are available from the Center for Food Safety and Applied Nutrition (HFS-200), 5001 Campus Dr., College Park, MD 20740, and the American Society for Testing 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:
(d) Interim listing. Acrylonitrile copolymers identified in this section shall comply with the provisions of § 180.22 of this chapter.
(e) Acrylonitrile copolymer identified in this section may be used to fabricate beverage containers only if they comply with the specifications of item 3 in paragraph (c) of this section.