ASTM D4661-98
(Test Method)Standard Test Methods for Polyurethane Raw Materials Determination of Total Chlorine in Isocyanates
Standard Test Methods for Polyurethane Raw Materials Determination of Total Chlorine in Isocyanates
SCOPE
1.1 These test methods determine the total chlorine content of the mixed isomers of toluene diisocyanate (TDI). The difference between the total chlorine content and the hydrolyzable chlorine content (see Test Method D4663) is a measure of the amount of o-dichlorobenzene and other ring-substituted chlorinated products that are present. Both procedures are applicable to a variety of organic compounds but the amount of sample used may have to be varied. (See Note 1.)
1.2 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.
1.3 This standard does not purport to address all of the safety problems, 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 hazards statements, see Notes 2, 4, 5, 6, 10, and Section 12.1. Note 1-There is no equivalent ISO standard.
General Information
Relations
Standards Content (Sample)
NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
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Designation: D 4661 – 98
Standard Test Methods for
Polyurethane Raw Materials: Determination of Total Chlorine
in Isocyanates
This standard is issued under the fixed designation D 4661; 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.
1. Scope is determined potentiometrically by titration with silver nitrate
(AgNO ) solution.
1.1 These test methods determine the total chlorine content
4.1.1 Test Method A—The sample is combusted in a pres-
of the mixed isomers of toluene diisocyanate (TDI). The
surized oxygen bomb.
difference between the total chlorine content and the hydrolyz-
4.1.2 Test Method B—The sample is combusted at atmo-
able chlorine content (see Test Method D 4663) is a measure of
spheric pressure in a Schoniger oxygen flask.
the amount of o-dichlorobenzene and other ring-substituted
chlorinated products that are present. Both procedures are
5. Significance and Use
applicable to a variety of organic compounds but the amount of
5.1 These test methods can be used for research or for
sample used may have to be varied. (See Note 1.)
quality control to determine the total chlorine content of
1.2 The values stated in SI units are to be regarded as the
toluene diisocyanates. In some instances total chlorine content
standard. The values given in parentheses are for information
may correlate with performance in polyurethane systems.
only.
1.3 This standard does not purport to address all of the
6. Interferences
safety concerns, if any, associated with its use. It is the
6.1 Bromine and iodine, if present, will react with the silver
responsibility of the user of this standard to establish appro-
nitrate (AgNO ) solution leading to an erroneously high total
priate safety and health practices and determine the applica-
chlorine value.
bility of regulatory limitations prior to use. For specific
hazards statements, see Notes 2, 4, 5, 6, 10, and Section 12.1.
7. Reagents and Materials
NOTE 1—There is no equivalent ISO standard.
7.1 Purity of Reagents—Use reagent-grade chemicals in all
tests. Unless otherwise indicated, it is intended that all reagents
2. Referenced Documents
conform to the specifications of the Committee on Analytical
2.1 ASTM Standards:
Reagents of the American Chemical Society where such
D 883 Terminology Relating to Plastics
specifications are available. Other grades may be used, pro-
D 1193 Specification for Reagent Water
vided it is first ascertained that the reagent is of sufficiently
D 4663 Test Method for Polyurethane Raw Materials: De-
high purity to permit its use without lessening the accuracy of
termination of Hydrolyzable Chlorine of Isocyanates
the determination.
7.2 Purity of Water—Unless otherwise indicated, references
3. Terminology
to water shall be understood to mean reagent water as defined
3.1 Definitions—For definitions of terms used in these test
by Type I of Specification D 1193.
methods see Terminology D 883.
8. Sampling
4. Summary of Test Method
8.1 Since organic isocyanates react with atmospheric mois-
4.1 In each test method, the organic matter in the sample is
ture, take special precautions in sampling (Warning:
destroyed by combustion with oxygen, the organically com-
Precaution—Note 2). Usual sampling methods (for example,
bined chlorine being converted to ionic chloride. The chloride
sampling an open drum with a thief), even when carried out
1 5
These test methods are under the jurisdiction of ASTM Committee D-20 on For information on the Schöniger flask, refer to Microchemie, Springer
Plastics and are the direct responsibility of Subcommittee D20.22 on Cellular Publishers, Vienna, Austria, Vol 42, 1955, p. 123, or Vol 43, 1956, p. 869.
Plastics. Reagent Chemicals, American Chemical Society Specifications, American
Current edition approved July 10, 1998. Published September 1998. Originally Chemical Society, Washington, DC. For suggestions on the testing of reagents not
published as D 4661 – 87. Last previous edition D 4661 – 93. listed by the American Chemical Society, see Analar Standards for Laboratory
Annual Book of ASTM Standards, Vol 08.01. Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia
Annual Book of ASTM Standards, Vol 11.01. and National Formulary, U.S. Pharmaceutical Convention, Inc. (USPC), Rockville,
Annual Book of ASTM Standards, Vol 08.03. MD.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
D 4661
rapidly, can cause contamination of the sample with insoluble 12. Procedure
urea. Therefore, blanket the sample with dry air or nitrogen at
12.1 Make certain that the bomb (Note 3), oxygen lines, and
all times.
fittings are free of oil and grease. Warning—Small quantities
of either may cause a violent explosion.
NOTE 2—Warning: Organic isocyanates are toxic when they are ab-
sorbed through the skin, or when the vapors are breathed. Precaution—
NOTE 3—When the bomb is used repeatedly, a film may form on its
Provide adequate ventilation and wear protective gloves and eyeglasses.
inner surface. Remove this film periodically by rotating the bomb on a
lathe at about 300 rpm and polishing the inside surface with Grit No. 2/0
9. Test Conditions
or equivalent paper coated with a light machine oil to prevent cutting and
9.1 Since isocyanates react with moisture, keep laboratory
then with a paste made from grit-free chromic oxide and water. This
humidity low, preferably around 50 % relative humidity. procedure will remove all but very deep pits while polishing the surface
well. Before using the bomb, wash it with soap and water to remove
TEST METHOD A—TOTAL CHLORINE BY OXYGEN
residual cutting oil or paste. Bombs with pitted surfaces should not be
BOMB
used because they will retain chlorine from sample to sample.
10. Apparatus
12.2 Weigh a 0.9-g sample by difference to 60.0005 g into
the combustion capsule (Warning: Note 4).
10.1 Weighing Bottle and Balance, suitable for weighing a
liquid sample by difference to the nearest 0.5 mg.
NOTE 4—Warning: A severe safety hazard exists if more than1gof
10.2 Oxygen Bomb Apparatus.
sample is used.
10.3 Fuse Wire, iron-nickel-chromium, No. 34B&S gage.
12.3 Fit a 100-mm, iron-nickel fuse wire onto the two
10.4 Potentiometric Titrator.
electrodes. Place the combustion capsule on the loop electrode
10.5 Silver-Silver Chloride Electrode.
and adjust the fuse wire in the capsule so that it is under the
10.6 Silver Electrode.
surface of the sample but does not touch the capsule. Place
10.7 Bubble Counter, a 100-mL graduate and delivery tube
about 5 mL of Na CO solution in the bomb and, with a rubber
2 3
or a bent “L” glass tube connected to a piece of rubber tubing.
policeman, wet the interior surface of the bomb, including the
The graduate is filled to the 50-mL mark with water to which
head, as thoroughly as possible. Put the bomb head in the bomb
3mL of0.1 N AgNO solution and 1 drop of concentrated
cylinder and the contact ring on top of the bomb head,
nitric acid (HNO , sp gr 1.42) have been added. Any turbidity
screwing the cap down finger-tight. Close the outlet valve
that develops indicates the HCl gas is being lost when venting
securely with the special wrench provided and open the main
the bomb.
oxygen cylinder slightly. Place the bomb in its bench-mounted
10.8 Microburet, 10-mL capacity, 0.05-mL graduations.
holder and tighten the holder bolt with an Allen wrench. Attach
11. Reagents
the union on the oxygen-filling connection to the inlet valve of
the bomb. Admit oxygen slowly (to prevent blowing the
11.1 Ethyl Alcohol, conforming to Formula No.2Bofthe
sample from the cup) to 20 to 25 atmospheres (2.03 to 2.53
U.S. Treasury Department Bureau of Alcohol, Tobacco, and
MPa). Close the operating valve of the oxygen cylinder and
Firearms.
observe the pressure on the bomb gage. If a leak is indicated by
11.2 Nitric Acid (1+1)—To 100 mL of water cooled in an
a gradual pressure drop, check and tighten all connections. Do
ice bath, add 100 mL of nitric acid (HNO , sp gr 1.42) while
not continue with the test until the leak is stopped and the bomb
stirring vigorously.
holds pressure. Release the pressure from the oxygen tank and
11.3 Oxygen—Free of combustible materials and halogen
disconnect the bomb. Place the valve thumb nut on the oxygen
compounds.
inlet valve and tighten finger tight (Note 5).
11.4 Silver Nitrate, Standard Solution (0.01 N)—Prepare a
0.01 N silver nitrate (AgNO ) solution, and standardize fre-
NOTE 5—Precaution: Exercise extreme caution from this point on until
quently enough to detect changes of 0.0005 N, either gravi-
the bomb has been fired, cooled, and bled free of oxygen.
metrically or potentiometrically, using standard hydrochloric
12.4 Pull the plug to the bomb ignition unit (Note 6). Fill the
acid (HCl).
bomb ignition receptacle ⁄4-full with water. Submerge the
11.5 Sodium Carbonate Solution (50 g/L)—Dissolve 135 g
bomb in the center of the ignition receptacle and visually
of sodium carbonate decahydrate (Na CO · 10H O) in water
2 3 2
inspect it for oxygen leaks. If the needle valve is not gas tight,
and dilute to 1 L.
tighten the packing gland slightly. Do not fire the bomb until all
leaks are repaired. Allow cooling water to circulate around the
These test methods as written are based on the use of Parr Bomb No. 1108
bomb the entire time the bomb is in the receptacle.
which has been found to be satisfactory for this purpose. The Parr Bomb No. 1108
is available from the Fisher Scientific Co., 585 Alpha Dr., Pittsburgh, PA. Equivalent
NOTE 6—Warning: A serious shock hazard exists around the bomb
apparatus may be substituted with appropriate changes in the procedure.
ignition receptacle should the ignition unit be shorted. Always pull the
A type of instrument similar to the “Titrimeter,” manufactured by the Fisher
electrical plug before touching this receptacle.
Scientific Co., 585 Alpha Dr., Pittsburgh, PA, may be used. An instrument providing
automatic titration, such as the Mettler DL 40, available from Mettler Instrument
12.5 Connect the terminal at the top of the ignition recep-
Corp., Box 71, Heightstown, NJ 08520, is convenient if many samples are involved.
tacle to the terminal on the top of the bomb. Connect the plugs
Fisher Scientific Co., No. 9-313-216 or its equivalent has been found to be
satisfactory for this purpose.
10 12
Fisher Scientific Co., No. 13-639-122 or its equivalent has been found to be Emery Polishing Paper Grit No. 2/0 may be purchased from the Behr-Manning
satisfactory for this purpose. Co., Troy, NY 12180.
11 13
Zero grade oxygen is suitable for this analysis. Any grade of oxygen that gives Chromic oxide may be purchased from J. T. Baker and Co., 222 Red School
a suitable blank can also be used. Lane, Phillipsburg, NJ 08865.
NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
D 4661
to the cooling receptacle, insert the plug to the ignition unit, 14.2 A limited round-robin was conducted.
and fire the bomb. The red indicator light should flash on, then 14.2.1 It has been estimated that duplicate results by the
off, indicating the bomb fired properly. Pull the electrical plug. same analyst should be considered suspect if they differ by
If the bomb does not fire as indicated, carefully feel the bomb. more than 0.015 % total chlorine.
If it is cold, this indicates that the test was incomplete, and that 14.2.2 It has been estimated that results reported by different
12.1 through 12.5 must be repeated. laboratories should be considered suspect if they differ by more
12.6 Allow the bomb to cool at least 10 min, then remove it than 0.03 % total chlorine.
from the receptacle and connect the bubble counter to the outlet 14.3 Bias—There are no recognized standards by which to
valve. Release the pressure slowly and uniformly, taking at estimate the bias of this test method.
least two min. When all of the gas has bled, open the bomb and
TEST METHOD B—TOTAL CHLORINE BY
examine its contents. Traces of unburned sample or soot
SCHÖNIGER OXYGEN FLASK
indicate incomplete combustion, and that the test must be
repeated.
15. Apparatus
12.7 Carefully wash the bomb head, the electrodes, the
15.1 Schöniger Combustion Flask, a chemically resistant,
capsule, and the cylinder walls with water as follows: Rinse the
1000-mL narrow-mouth (24/40 standard-taper joint) Erlenm-
walls of the cylinder with about 25 mL of distilled water and
eyer flask with a 101.60-mm (4-in.) No. 18 platinum wire
fill the capsule. Scrub both the interior of the bomb and the
sealed into the glass stopper. Using tweezers to avoid contami-
inner surface of the bomb cover with a rubber policeman and
nation from fingerprints (Note 8), make a basket from 45-mesh
wash the policeman into the bomb. Rinse the bomb washings
0.20 mm (0.0078-in.) platinum gauze as follows: Fold over the
into a 250-mL beaker (Note 7). Evaporate the washings in the
edges of a 12.7 by 25.4-mm (0.50 by 1-in.) or 13 by 25-mm
beaker to about 20 mL. Cool below 10°C and acidify the
(0.50 by 1-in.) piece of gauze about 1.6 mm (0.06-in.) and
solution to methyl red indicator by the dropwise addition of
crimp them to prevent the gauze from unraveling. Bend the last
HNO (1 + 1). Insert silver-silver chloride electrodes and add
25.4-mm (1-in.) of the No. 18 wire at a right angle and place
60 to 100 mL of ethyl alcohol to cover the electrode tips. Cool
the gauze on the 25.4-mm (1-in.) section. Bend the last
the solution to 10°C, and titrate potentiometrically with 0.01 N
one-half of the wire back over the gauze and crimp strongly to
AgNO , adding the AgNO solution in 0.1-mL increments near
3 3
hold the gauze firmly in place. Bend the sides of the gauze to
the end point.
form an open basket.
12.8 Titrate a blank exactly as described in 12.1 through
12.7, but without adding the sample.
NOTE 8—Because small amounts of chloride are involved, contamina-
tion from fingerprints can be significant.
NOTE 7—Because it is difficult to rinse the last traces of chloride from
15.2 Absorbent Cotton, cut into squares weighing approxi-
the walls of the bomb, residual chloride tends to carry over from sample
to sample. Therefore, avoid alternating samples with
...
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