§177.1970 氯乙烯/月桂基乙烯基醚共聚物(Vinyl chloride-lauryl vinyl ether copolymers)

　　177.1970 Vinyl chloride-lauryl vinyl ether copolymers.


　    　The vinyl chloride-lauryl vinyl ether copolymers identified in paragraph （a） of this section may be used as an article or as a component of an article intended for use in contact with food subject to the provisions of this section.

　　（a） Identity. For the purposes of this section vinyl chloride-lauryl vinyl ether copolymers consist of basic copolymers produced by the copolymerization of vinyl chloride and lauryl vinyl ether such that the finished copolymers contain not more than 3 weight-percent of polymer units derived from lauryl vinyl ether and meet the specifications and extractives limitations prescribed in paragraph （c） of this section.

　　（b） Optional adjuvant substances. The basic vinyl chloride-lauryl vinyl ether copolymers identified in paragraph （a） of this section may contain optional adjuvant substances required in the production of such basic copolymers. These optional adjuvant substances may include substances permitted for such use by regulations in parts 170 through 189 of this chapter, substances generally recognized as safe in food, and substances used in accordance with a prior sanction or approval.

　　（c） Specifications and limitations. The vinyl chloride-lauryl vinyl ether basic copolymers meet the following specifications and extractives limitations:

　　（1） Specifications. （i） Total chlorine content is 53 to 56 percent as determined by any suitable analytical procedure of generally accepted applicability.

　　（ii） Inherent viscosity in cylcoHhexanone at 30 °C is not less than 0.60 deciliter per gram as determined by ASTM method D1243-79, “Standard Test Method for Dilute Solution Viscosity of Vinyl Chloride Polymers,” 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.

　　（2） Extractives limitations. The following extractives limitations are determined by the method described in paragraph （d） of this section:

　　（i） Total extractives do not exceed 0.03 weight-percent when extracted with water at 150 °F for 2 hours.

　　（ii） Total extractives do not exceed 0.60 weight-percent when extracted with n- heptane at 150 °F for 2 hours.

　　（d） Analytical methods. The analytical methods for determining total extractives are applicable to the basic copolymers in powder form having a particle size such that 100 percent will pass through a U.S. Standard Sieve No. 40 and such that not more than 10 percent will pass through a U.S. Standard Sieve No. 200.

　　（1） Reagents— （i） Water. All water used in these procedures shall be demineralized （deionized）, freshly distilled water.

　　（ii） n-Heptane. Reagent grade, freshly distilled n- heptane shall be used.

　　（2） Determination of total amount of extractives. Place an accurately weighed sample of suitable size in a clean borosilicate flask, and for each gram of sample add 3 milliliters of solvent previously heated to 150 °F. Maintain the temperature of the contents of the flask at 150 °F for 2 hours using a hot plate while also maintaining gentle mechanical agitation. Filter the contents of the flask rapidly through No. 42 Whatman filter paper with the aid of suction. Transfer the filtrate to flat glass dishes that are warmed on a hot plate and evaporate the solvent with the aid of a stream of filtered air. When the volume of the filtrate has been reduced to 10 to 15 milliliters, transfer the filtrate to tared 50-milliliter borosilicate glass beakers and complete evaporation to a constant weight in a 140 °F vacuum oven. Carry out a corresponding blank determination with each solvent. Determine the weight of the residue corrected for the solvent blank and calculate the result as percent of the initial weight of the resin sample taken for analysis.

　　（e） Other specifications and limitations. The vinyl chloride-lauryl vinyl ether copolymers identified in and complying with this section, when used as components of the food-contact surface of any article that is subject to a regulation in parts 174, 175, 176, 177, 178 and § 179.45 of this chapter, shall comply with any specifications and limitations prescribed by such regulation for the article in the finished form in which it is to contact food.

　　[42 FR 14572, Mar. 15, 1977, as amended at 49 FR 10110, Mar. 19, 1984]