[Code of Federal Regulations]
[Title 21, Volume 3]
[Revised as of January 1, 2007]
From the U.S. Government Printing Office via GPO Access
[CITE: 21CFR177.1810]
[Page 319-321]
TITLE 21--FOOD AND DRUGS
CHAPTER I--FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN
SERVICES (CONTINUED)
PART 177 INDIRECT FOOD ADDITIVES: POLYMERS--Table of Contents
Subpart B Substances for Use as Basic Components of Single and Repeated
Use Food Contact Surfaces
Sec. 177.1810 Styrene block polymers.
The styrene block polymers identified in paragraph (a) of this
section may be safely used as articles or as components of articles
intended for use in contact with food, subject to provisions of this
section.
(a) For the purpose of this section, styrene block polymers are
basic polymers manufactured as described in this paragraph, so that the
finished polymers meet the specifications prescribed in paragraph (b) of
this section, when tested by the methods described in paragraph (c) of
this section.
(1) Styrene block polymers with 1,3-butadiene are those produced by
the catalytic solution polymerization of styrene and 1,3-butadiene.
(2) Styrene block polymers with 2-methyl.1,3-butadiene are those
produced by the catalytic solution polymerization of styrene and 2-
methyl.1,3-butadiene.
(3) Styrene block polymers with 1,3-butadiene, hydrogenated are
those produced by the catalytic solution polymerization of styrene and
1,3-butadiene, and subsequently hydrogenated.
(b) Specifications:
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Maximum Maximum
extractable extractable
fraction in fraction in 50
Molecular Glass distilled water percent ethanol
Styrene block polymers weight Solubility transition at specified at specified
(minimum) points temperatures, temperatures,
times, and times, and
thicknesses thicknesses
----------------------------------------------------------------------------------------------------------------
1. (i) Styrene block polymers 29,000 Completely -98 [deg]C (- 0.0039 mg/cm\2\ 0.002 mg/cm\2\
with 1,3-butadiene; for use as soluble in 144 [deg]F) (0.025 mg/in\2\) (0.01 mg/in\2\)
articles or as components of toluene. to -71 of surface at of surface at 66
articles that contact food of [deg]C (-96 reflux [deg]C (150
Types I, II, IV-B, VI, VII-B, [deg]F) and temperature for [deg]F) for 2 hr
and VIII identified in table 1 86 [deg]C 30 min on a 0.19 on a 0.19 cm
in Sec. 176.170(c) of this (187 [deg]F) cm (0.075 in) (0.075 in) thick
chapter under conditions of to 122 thick sample. sample.
use D, E, F, and G described [deg]C (252
in table 2 in Sec. [deg]F).
176.170(c) of this chapter.
[[Page 320]]
(ii) Styrene block polymers 29,000 ......do...... ......do..... ......do......... Do.
with 1,3-butadiene; for use as
components of pressure-
sensitive adhesives that
contact food of Types I, II,
IV-B, VI, VII-B, and VIII
identified in table 1 in Sec.
176.170(c) of this chapter
under conditions of use C, D,
E, F and G described in table
2 in Sec. 176.170(c) of this
chapter, provided the pressure-
sensitive adhesives be applied
only to closure tapes for
sealing containers having a
capacity of not less than 160
cc (5.5 fluid ounces) and that
the area of the adhesive
exposed to food shall not
exceed 4.03 cm\2\ (0.625
in\2\). The pressure-sensitive
adhesive may contain terpene
resins as identified in Sec.
175.125(b)(2) of this chapter.
2. Styrene block polymers with 29,000 ......do...... -65 [deg]C (- 0.002 mg/cm\2\ 0.002 mg/cm\2\
2-methyl.1,3-butadiene; for 85 [deg]F) (0.01 mg/in\2\) (0.01 mg/in\2\)
use as articles or as to -47 of surface at of surface at 66
components of articles that [deg]C (-53 reflux [deg]C (150
contact food of Types I, II, [deg]F) and temperature for [deg]F) for 2 hr
IV-B, VI, VII-B, and VIII 86 [deg]C 2 hr on a 0.071 on a 0.071 cm
identified in table 1 in Sec. (187 [deg]F) cm (0.028 in) (0.028 in) thick
176.170(c) of this chapter. to 122 thick sample. sample.
[deg]C (252 (Optionally, (Optionally,
[deg]F). maximum net maximum net
residue soluble residue soluble
in chloroform in chloroform
shall not exceed shall not exceed
0.00020 mg/cm\2\ 0.00040 mg/cm\2\
(0.0013 mg/ (0.0025 mg/
in\2\) of in\2\) of
surface.). surface.)
3. (i) Styrene block polymers 16,000 ......do...... -50 [deg]C (- 0.002 mg/cm\2\ 0.002 mg/cm\2\
with 1,3-butadiene, 58 [deg]F) (0.01 mg/in\2\) (0.01 mg/in\2\)
hydrogenated (CAS Reg. No. to -30 of surface at of surface at 66
66070-58-4): for use as [deg]C (-22 reflux [deg]C (150
articles or as components of [deg]F) and temperature for [deg]F) for 2 hr
articles that contact food of 92 [deg]C 2 hr on a 0.071 on a 0.071 cm
Types I, II, IV-B, VI, VII-B, (198 [deg]F) cm (0.028 in) (0.028 in) thick
and VIII identified in table 1 to 98 [deg]C thick sample. sample.
in Sec. 176.170(c) of this (208 [deg]F).
chapter.
(ii) Styrene block polymers 16,000 ......do...... ......do..... ......do......... Do.
with 1,3-butadiene,
hydrogenated (CAS Reg. No.
66070-58-4): for use at levels
not to exceed 42.4 percent by
weight as a component of
closures with sealing gaskets
that would contact food of
Types III, IV-A, V, VII-A,
VIII, and IX identified in
table 1 in Sec. 176.170(c)
of this chapter, and in
condition of use D as
described under table 2 in
Sec. 176.170(c) of this
chapter.
----------------------------------------------------------------------------------------------------------------
(c) The analytical methods for determining whether styrene block
polymers conform to the specifications prescribed in this section are as
follows and are applicable to the finished polymer.
(1) Molecular weight. Molecular weight shall be determined by
intrinsic viscosity (or other suitable method).
(2) Glass transition points. The glass transition points shall be
determined by either of the following methods:
(i) ASTM method D2236-70 (``Standard Method of Test for Dynamic
Mechanical Properties of Plastics by Means of Torsional Pendulum,''
which is incorporated by reference; copies are available from American
Society for Testing and Materials (ASTM), 100
[[Page 321]]
Barr Harbor Dr., West Conshohocken, Philadelphia, PA 19428-2959, 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.)
modified by using a forced resonant vibration instead of a fixed
vibration and by using frequencies of 25 to 40 cycles per second instead
of 0.1 to 10 cycles per second.
(ii) Direct reading viscoelastometric method titled ``Direct Reading
Viscoelastrometric Method for Determining Glass Transition Points of
Styrene Block Polymers'' (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.), by which the glass transition points are determined in
the tensile mode of deformation at a frequency of 35 hertz using a
Rheovibron Model DDV-II (or equivalent) Direct Reading Viscoelastometer.
Take maxima in the out-of-phase component of the complex modulus as the
glass transition points. For block polymers of low styrene content or
for simple block polymers, the polymer may be treated with 0.3 part per
hundred dicumyl peroxide and cured for 30 minutes at 153 [deg]C to
accentuate the upper transition point.
(3) Maximum extractable fractions in distilled water and 50 percent
ethanol and the maximum net residue solubles in chloroform. The maximum
extractable fractions in distilled water and 50 percent ethanol, and the
maximum net residue solubles in chloroform, shall be determined in
accordance with Sec. 176.170(d)(3) of this chapter using a sandwich
form of the finished copolymer of the specified thickness and for the
time and temperature specified in paragraph (b) of this section.
(d) The provisions of this section are not applicable to butadiene-
styrene copolymers listed in other sections of this subpart.
(e) The provisions of this section are not applicable to styrene
block polymers with 1,3-butadiene listed in Sec. 175.105 of this
chapter.
[42 FR 14572, Mar. 15, 1977, as amended at 42 FR 43621, Aug. 30, 1977;
47 FR 11844, Mar. 19, 1982; 51 FR 16828, May 7, 1986; 54 FR 24898, June
12, 1989; 58 FR 65546, Dec. 15, 1993]
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