ASTM D5155-96

Standard Test Methods for Polyurethane Raw Materials Determination of the Isocyanate Content of Aromatic Isocyanates

SCOPE
1.1 These test methods measure the isocyanate content of aromatic isocyanates used as polyurethane raw materials.
1.1.1 Test Method A—Unheated toluene-dibutylamine determines the amount of toluene diisocyanate in refined toluene-2,4-diisocyanate and toluene-2,6-diisocyanate, or mixtures of the two. Other isomers, if present, will be included in the determination. This test method may also be applied to other isocyanates of suitable reactivity and solubility.
1.1.2 Test Method B—Heated toluene-dibutylamine determines the amine equivalent of crude or modified isocyanates derived from toluene diisocyanate, methylenebis-(4-phenylisocyanate), and polymethylene polyphenylisocyanate.
1.1.3 Test Method C—Unheated trichlorobenzene-toluene-dibutylamine determines the isocyanate content of crude or modified isocyanates derived from toluene diisocyanate, methylene-bis-(4-phenylisocyanate), and polymethylene polyphenylisocyanate. This test method can also be used to assay isomer mixtures of toluene diisocyanate and methylene- bis-(phenylisocyanate).
1.2 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.For specific warning and precautionary statements, see Note 1.
Note 2—Method C of this test method is equivalent to Method B of ISO 14896.

General Information

• Status: Historical
• Publication Date: 09-Nov-2001
• ICS: 83.080.20 - Thermoplastic materials
• Technical Committee: D20 - Plastics
• Drafting Committee: D20.22 - Cellular Materials - Plastics and Elastomers

Relations

• Replaced By: ASTM D5155-01 - Standard Test Methods for Polyurethane Raw Materials Determination of the Isocyanate Content of Aromatic Isocyanates
• Effective Date: 10-Nov-2001
• Referred By: ASTM D1786-21 - Standard Specification for Toluene Diisocyanate
• Effective Date: 10-Nov-2001

Standards Content (Sample)

NOTICE: This standard has either been superseded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
Designation: D 5155 – 96
AMERICAN SOCIETY FOR TESTING AND MATERIALS
100 Barr Harbor Dr., West Conshohocken, PA 19428
Reprinted from the Annual Book of ASTM Standards. Copyright ASTM
Standard Test Methods for
Polyurethane Raw Materials: Determination of the
1
Isocyanate Content of Aromatic Isocyanates
This standard is issued under the fixed designation D 5155; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
4
1. Scope D 1193 Specification for Reagent Water
E 180 Practice for Determining the Precision of ASTM
1.1 These test methods measure the isocyanate content of
5
Methods for Analysis and Testing of Industrial Chemicals
aromatic isocyanates used as polyurethane raw materials.
1.1.1 Test Method A—Unheated toluene-dibutylamine de-
3. Terminology
termines the amount of toluene diisocyanate in refined toluene-
3.1 Definitions:
2,4-diisocyanate and toluene-2,6-diisocyanate, or mixtures of
3.1.1 polyurethane, n—a polymer prepared by the reaction
the two. Other isomers, if present, will be included in the
of an organic diisocyanate with compounds containing hy-
determination. This test method may also be applied to other
droxyl groups.
isocyanates of suitable reactivity and solubility.
3.1.1.1 Discussion—Polyurethanes or urethanes, as they are
1.1.2 Test Method B—Heated toluene-dibutylamine deter-
sometimes called, may be thermosetting, thermoplastic, rigid
mines the amine equivalent of crude or modified isocyanates
or soft and flexible, or cellular or solid (see Terminology
derived from toluene diisocyanate, methylenebis-(4-
D 883).
phenylisocyanate), and polymethylene polyphenylisocyanate.
3.2 Definitions of Terms Specific to This Standard:
1.1.3 Test Method C—Unheated trichlorobenzene-toluene-
3.2.1 amine equivalent—the weight of sample that will
dibutylamine determines the isocyanate content of crude or
combine with 1.0-g equivalent weight of dibutylamine.
modified isocyanates derived from toluene diisocyanate,
3.2.2 assay—the percent by weight of toluene diisocyanate
methylene-bis-(4-phenylisocyanate), and polymethylene
present in the sample.
polyphenylisocyanate. This test method can also be used to
3.2.3 isocyanate (NCO) content—the weight percent of the
assay isomer mixtures of toluene diisocyanate and methylene-
NCO groups present in the sample.
bis-(phenylisocyanate).
1.2 This standard does not purport to address all of the
4. Summary of Test Methods
safety concerns, if any, associated with its use. It is the
4.1 All three test methods react the isocyanate sample with
responsibility of the user of this standard to establish appro-
an excess of dibutylamine to form the corresponding urea. The
priate safety and health practices and determine the applica-
NCO content is determined from the amount of dibutylamine
bility of regulatory limitations prior to use. For specific
consumed in the reaction. Each test method varies solvent or
warning and precautionary statements, see Note 2.
heating times to yield accurate assays of the sample in
NOTE 1—There is no equivalent ISO standard.
question.
4.1.1 Test Method A—The sample is added to an excess of
2. Referenced Documents
dibutylamine in toluene and allowed to stand at room tempera-
2.1 ASTM Standards:
ture for 15 min. The reaction mixture is diluted with isopropyl
2
D 841 Specification for Nitration Grade Toluene
alcohol, and the excess dibutylamine is back-titrated colori-
3
D 883 Terminology Relating to Plastics
metrically with hydrochloric acid.
4.1.2 Test Method B—The sample is added to an excess of
dibutylamine in toluene and stirred for 20 min. The resulting
1
These test methods are under the jurisdiction of ASTM Committee D-20 on
solution is then heated rapidly to 100°C, removed from the
Plastics and are the direct responsibility of Subcommittee D20.22 on Cellular
Plastics. These test methods were recommended to ASTM by the Society of the
heat, and allowed to stand for 30 min. The reaction mixture is
Plastics Industry Polyurethane Raw Materials Analysis Committee.
diluted with isopropyl alcohol, and the excess dibutylamine is
Current edition approved Nov. 10, 1996. Published January 1997. Originally
back-titrated potentiometrically with hydrochloric acid.
published as D 5155 – 91. Last previous edition D 5155 – 91.
Revisions to this edition include the addition of Note 1 as well as the lowering 4.1.3 Test Method C—The sample is added to a solution of
of the normal acidity level of crude isocynates from 0.3 % to 0.05 %. The
dibutylamine in toluene and trichlorobenzene. The resulting
designation of pH in a nonaqueous mixture was changed to “apparent pH.
...