§177.2470 聚氧亚甲基共聚物(Polyoxymethylene copolymer)

     §177.2470 Polyoxymethylene copolymer

　　    Polyoxymethylene copolymer identified in this section may be safely used as an article or component of articles intended for food-contact use in accordance with the following prescribed conditions:

　　（a） Identity. For the purpose of this section, polyoxymethylene copolymers are identified as the following: The reaction product of trioxane （cyclic trimer of formaldehyde） and ethylene oxide （CAS Reg. No. 24969-25-3） or the reaction product of trioxane （cyclic trimer of formaldehyde） and a maximum of 5 percent by weight of butanediol formal （CAS Reg. No. 25214 85-1）。 Both copolymers may have certain optional substances added to impart desired technological properties to the copolymer.

　　（b） Optional adjuvant substances. The polyoxymethylene copolymer identified in paragraph （a） of this section may contain optional adjuvant substances required in its production. The quantity of any optional adjuvant substance employed in the production of the copolymer does not exceed the amount reasonably required to accomplish the intended technical or physical effect. Such adjuvants may include substances generally recognized as safe in food, substances used in accordance with prior sanction, substances permitted under applicable regulations in parts 170 through 189 of this chapter, and the following:

　　（1） Stabilizers （total amount of stabilizers not to exceed 2.0 percent and amount of any one stabilizer not to exceed 1.0 percent of polymer by weight）

　　Calcium ricinoleate.

　　Cyanoguanidine.

　　Hexamethylene bis（3,5-di-tert-butyl-4-hydroxy-hydro-cinnamate） （CAS Reg. No. 35074-77-2）。

　　Melamine-formaldehyde resin.

　　2,2′-Methylenebis（4-methyl-6-tert-butylphenol）。

　　Nylon 6/66, weight ratio 2/3.

　　Tetrakis [methylene （3,5-di-tert-butyl-4-hydroxyhydrocinnamate）] methane.

　　（2） Lubricant: N,N′Distearoylethyl-enediamine.

　　（c） Specifications. （1） Poly-oxy-meth-ylene copolymer can be identified by its characteristic infrared spectrum.

　　（2） Minimum number average molecular weight of the copolymer is 15,000 as determined by a method titled “Number Average Molecular Weight,” 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） Extractive limitations. （1） Poly-oxy-methylene copolymer in the finished form in which it is to contact food, when extracted with the solvent or solvents characterizing the type of food and under conditions of time and temperature as determined from tables 1 and 2 of § 175.300（d） of this chapter, shall yield net chloroform-soluble extractives not to exceed 0.5 milligram per square inch of food-contact surface.

　　（2） Polyoxymethylene copolymer with or without the optional substances described in paragraph （b） of this section, when ground or cut into particles that pass through a U.S.A. Standard Sieve No. 6 and that are retained on a U.S.A. Standard Sieve No. 10, shall yield total extractives as follows:

　　（i） Not to exceed 0.20 percent by weight of the copolymer when extracted for 6 hours with distilled water at reflux temperature.

　　（ii） Not to exceed 0.15 percent by weight of the copolymer when extracted for 6 hours with n-heptane at reflux temperature.

　　（e） Conditions of use. （1） The polyoxymethylene copolymer is for use as articles or components of articles intended for repeated use.

　　（2） Use temperature shall not exceed 250 °F.

　　（3） In accordance with good manufacturing practice, finished articles containing polyoxymethylene copolymer shall be thoroughly cleansed before their first use in contact with food.

　　　[42 FR 14572, Mar. 15, 1977, as amended at 48 FR 56204, Dec. 20, 1983; 49 FR 5748, Feb. 15, 1984; 50 FR 1842, Jan. 14, 1985; 50 FR 20560, May 17, 1985; 52 FR 4493, Feb. 12, 1987, 54 FR 24898, June 12, 1989]