§177.2420 交联聚酯树脂(Polyester resins, cross-linked)

       §177.2420 Polyester resins, cross-linked

　　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:

　　（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:

　　（1） Acids:

　　Adipic.

　　Fatty acids, and dimers thereof, from natural sources.

　　Fumaric.

　　Isophthalic.

　　Maleic.

　　Methacrylic.

　　Orthophthalic.

　　Sebacic.

　　Terephthalic.

　　Trimellitic.

　　（2） Polyols and polyepoxides:

　　Butylene glycol.

　　Diethylene glycol.

　　2,2-Dimethyl-1,3-propanediol.

　　Dipropylene glycol.

　　Ethylene glycol.

　　Glycerol.

　　4,4′-Isopropylidenediphenol-epi-chloro-hydrin.

　　Mannitol.

　　a-Methyl glucoside.

　　Pentaerythritol.

　　Polyoxypropylene ethers of 4,4′-isopropylide-nediphenol （containing an average of 2-7.5 moles of propylene oxide）.

　　Propylene glycol.

　　Sorbitol.

　　Trimethylol ethane.

　　Trimethylol propane.

　　2,2,4-Trimethyl-1,3-pentanediol.

　　（3） Cross-linking agents:

　　Butyl acrylate.

　　Butyl methacrylate.

　　Ethyl acrylate.

　　Ethylhexyl acrylate.

　　Methyl acrylate.

　　Methyl methacrylate.

　　Styrene.

　　Triglycidyl 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.

　　Vinyl toluene.

　　（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:

List of substances	Limitations (limits of addition expressed as percent by weight of finished resin)
1. Inhibitors:	Total not to exceed 0.08 percent.
Benzoquinone	0.01 percent.
tert-Butyl catechol
TBHQ
Di-tert-butyl hydroquinone
Hydroquinone
2. Accelerators:	Total not to exceed 1.5 percent.
Benzyl trimethyl ammonium chloride	0.05 percent.
Calcium naphthenate
Cobalt naphthenate
Copper naphthenate
N, N-Diethylaniline	0.4 percent.
N, N-Dimethylaniline	Do.
Ethylene guanidine hydrochloride	0.05 percent.
3. 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.
Azo-bis-isobutyronitrile
Benzoyl peroxide
tert-Butyl perbenzoate
Chlorbenzoyl peroxide
Cumene hydroperoxide
Dibutyltin 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.
Dicumyl peroxide
Hydroxybutyltin 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.
Lauroyl peroxide
p-Menthane hydroperoxide
Methyl ethyl ketone peroxide
Monobutyltin 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.
4. Solvents for inhibitors, accelerators, and catalysts:
Butyl benzyl phthalate (containing not more than 1.0 percent by weight of dibenzyl phthalate)
Dibutyl phthalate
Diethylene glycol	As a solvent for benzyl trimethyl ammonium chloride or ethylene guanidine hydrochloride only.
Dimethyl phthalate
Methyl alcohol
Styrene
Triphenyl phosphate
5. Reinforcements:
Asbestos
Glass fiber
Polyester 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
6. Miscellaneous materials:
Castor oil, hydrogenated
α-Methylstyrene
Polyethylene glycol 6000
Code of Federal Regulations 343
Silicon dioxide
Wax, petroleum	Complying with § 178.3710 of this chapter.

　　（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:

　　（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.

　　（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.

　　（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.

　　　　[42 FR 14572, Mar. 15, 1977, as amended at 48 FR 37618, Aug. 19, 1983; 54 FR 48858, Nov. 28, 1989]