{"data":{"id":"us/21-cfr-177.2420","jurisdiction":"us","citation":"21 CFR 177.2420","heading":"Polyester resins, cross-linked.","body":"Cross-linked polyester resins may be safely used as articles or components of articles intended for repeated use in contact with food, in accordance with the following prescribed conditions:\n(a) The cross-linked polyester resins are produced by the condensation of one or more of the acids listed in paragraph (a)(1) of this section with one or more of the alcohols or epoxides listed in paragraph (a)(2) of this section, followed by copolymerization with one or more of the cross-linking agents listed in paragraph (a)(3) of this section:\n(1) Acids:\nAdipic.\nFatty acids, and dimers thereof, from natural sources.\nFumaric.\nIsophthalic.\nMaleic.\nMethacrylic.\nOrthophthalic.\nSebacic.\nTerephthalic.\nTrimellitic.\n(2) Polyols and polyepoxides:\nButylene glycol.\nDiethylene glycol.\n2,2-Dimethyl-1,3-propanediol.\nDipropylene glycol.\nEthylene glycol.\nGlycerol.\n4,4′-Isopropylidenediphenol-epichlorohydrin.\nMannitol.\na-Methyl glucoside.\nPentaerythritol.\nPolyoxypropylene ethers of 4,4′-isopropylide-nediphenol (containing an average of 2-7.5 moles of propylene oxide).\nPropylene glycol.\nSorbitol.\nTrimethylol ethane.\nTrimethylol propane.\n2,2,4-Trimethyl-1,3-pentanediol.\n(3) Cross-linking agents:\nButyl acrylate.\nButyl methacrylate.\nEthyl acrylate.\nEthylhexyl acrylate.\nMethyl acrylate.\nMethyl methacrylate.\nStyrene.\nTriglycidyl isocyanurate (CAS Reg. No. 2451-62-9), for use only in coatings contacting bulk quantities of dry food of the type identified in § 176.170(c) of this chapter, table 1, under type VIII.\nVinyl toluene.\n(b) Optional adjuvant substances employed to facilitate the production of the resins or added thereto to impart desired technical or physical properties include the following, provided that the quantity used does not exceed that reasonably required to accomplish the intended physical or technical effect and does not exceed any limitations prescribed in this section:\nList of substances Limitations (limits of addition expressed as percent by weight of finished resin)\n1. Inhibitors: Total not to exceed 0.08 percent.\nBenzoquinone 0.01 percent.\ntert-Butyl catechol\nTBHQ\nDi-tert-butyl hydroquinone\nHydroquinone\n2. Accelerators: Total not to exceed 1.5 percent.\nBenzyl trimethyl ammonium chloride 0.05 percent.\nCalcium naphthenate\nCobalt naphthenate\nCopper naphthenate\nN, N-Diethylaniline 0.4 percent.\nN, N-Dimethylaniline Do.\nEthylene guanidine hydrochloride 0.05 percent.\n3. Catalysts: Total not to exceed 1.5 percent, except that methyl ethyl ketone peroxide may be used as the sole catalyst at levels not to exceed 2 percent.\nAzo-bis-isobutyronitrile\nBenzoyl peroxide\ntert-Butyl perbenzoate\nChlorbenzoyl peroxide\nCumene hydroperoxide\nDibutyltin oxide (CAS Reg. No. 818-08-6) For use in the polycondensation reaction at levels not to exceed 0.2 percent of the polyester resin.\nDicumyl peroxide\nHydroxybutyltin oxide (CAS Reg. No. 2273-43-0) For use in the polycondensation reaction at levels not to exceed 0.2 percent of the polyester resin.\nLauroyl peroxide\np-Menthane hydroperoxide\nMethyl ethyl ketone peroxide\nMonobutyltin tris(2-ethylhexoate) (CAS Reg. No. 23850-94-4) For use in the polycondensation reaction at levels not to exceed 0.2 percent of the polyester resin.\n4. Solvents for inhibitors, accelerators, and catalysts:\nDiethylene glycol As a solvent for benzyl trimethyl ammonium chloride or ethylene guanidine hydrochloride only.\nMethyl alcohol\nStyrene\nTriphenyl phosphate\n5. Reinforcements:\nAsbestos\nGlass fiber\nPolyester fiber produced by the condensation of one or more of the acids listed in paragraph (a)(1) of this section with one or more of the alcohols listed in paragraph (a)(2) of this section\n6. Miscellaneous materials:\nCastor oil, hydrogenated\nα-Methylstyrene\nPolyethylene glycol 6000\nSilicon dioxide\nWax, petroleum Complying with § 178.3710 of this chapter.\n(c) The cross-linked polyester resins, with or without the optional substances described in paragraph (b) of this section, and in the finished form in which they are to contact food, when extracted with the solvent or solvents characterizing the type of food and under the conditions of time and temperature characterizing the conditions of their intended use, as determined from tables 1 and 2 of § 176.170(c) of this chapter, shall meet the following extractives limitations:\n(1) Net chloroform-soluble extractives not to exceed 0.1 milligram per square inch of food-contact surface tested when the prescribed food-simulating solvent is water or 8 or 50 percent alcohol.\n(2) Total nonvolatile extractives not to exceed 0.1 milligram per square inch of food-contact surface tested when the prescribed food-simulating solvent is heptane.\n(d) In accordance with good manufacturing practice, finished articles containing the cross-linked polyester resins shall be thoroughly cleansed prior to their first use in contact with food.","path":["Title 21—Food and Drugs","CHAPTER I—FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES","SUBCHAPTER B—FOOD FOR HUMAN CONSUMPTION","PART 177—INDIRECT FOOD ADDITIVES: POLYMERS","Subpart C—Substances for Use Only as Components of Articles Intended for Repeated Use"],"source_url":"https://www.ecfr.gov/api/versioner/v1/full/2026-08-25/title-21.xml","current_through":"2026-08-25","vintage":"","retrieved_at":"2026-08-27T02:24:47Z","sha256":"4f6b4d7c5314eb3c0894bfc698a18518e042e76a388dc58707b153515d4ce955","source_id":"us-cfr","stale":true,"prev":"us/21-cfr-177.2415","next":"us/21-cfr-177.2430"},"notice":"GroundRules: Original legal text. Not legal advice."}