§177.1590 Polyester elastomers
The polyester elastomers identified in paragraph （a） of this section may be safely used as the food-contact surface of articles intended for use in contact with bulk quantities of dry food of the type identified in § 176.170（c） of this chapter, table 1, under Type VIII, in accordance with the following prescribed conditions:
（a） For the purpose of this section, polyester elastomers are those produced by the ester exchange reaction when one or more of the following phthalates—dimethyl terephthalate, dimethyl orthophthalate, and dimethyl isophthalate—is made to react with alpha-hydroomega-hydroxypoly （oxytetramethylene） and/or 1,4- butanediol such that the finished elastomer has a number average molecular weight between 20,000 and 30,000.
（b） Optional adjuvant substances employed in the production of the polyester elastomers or added thereto to impart desired technical or physical properties may include the following substances:
| List of substances | Limitations |
| 4,4′ - Bis (alpha, alpha-dimethyl-benzyl) diphenylamine | For use only as an antioxidant. |
| Tetrabutyl titanate | For use only as a catalyst. |
（c） An appropriate sample of the finished polyester elastomer in the form in which it contacts food when subjected to ASTM method D968-81, “Standard Test Methods for Abrasion Resistance of Organic Coatings by the Falling Abrasive Tester,” which is incorporated by reference （Copies may be obtained from 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: http://www.archives.gov/federal_register/code_of_federal_regulations/ibr_locations.html. ）, using No. 50 emery abrasive in lieu of Ottawa sand, shall exhibit an abrasion coefficient of not less than 100 liters per mil of thickness.
[42 FR 14572, Mar. 15, 1977, as amended at 49 FR 10109, Mar. 19, 1984]
