21 CFR § 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:
(2) Polyols and polyepoxides:
(3) Cross-linking agents:
(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. |
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|
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| TBHQ | |
| Di |
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| Hydroquinone | |
| 2. Accelerators: | Total not to exceed 1.5 percent. |
| Benzyl trimethyl ammonium chloride | 0.05 percent. |
| Calcium naphthenate | |
| Cobalt naphthenate | |
| Copper naphthenate | |
|
|
0.4 percent. |
|
|
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 | |
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|
|
| 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 | |
|
|
|
| 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: | |
| Diethylene glycol | As a solvent for benzyl trimethyl ammonium chloride or ethylene guanidine hydrochloride only. |
| 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 | |
| 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.