1、Designation: D2621 87 (Reapproved 2011)Standard Test Method forInfrared Identification of Vehicle Solids From Solvent-Reducible Paints1This standard is issued under the fixed designation D2621; the number immediately following the designation indicates the year oforiginal adoption or, in the case of
2、 revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers the qualitative characterizationor identification of separated paint ve
3、hicle solids by infraredspectroscopy within the limitations of infrared spectroscopy.1.2 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices an
4、d determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D1467 Guide for Testing Fatty Acids Used in ProtectiveCoatings3D1962 Test Method for Saponification Value of DryingOils, Fatty Acids, and Polymerized Fatty Acids3D2372 Practice for Separa
5、tion of Vehicle From Solvent-Reducible PaintsE131 Terminology Relating to Molecular SpectroscopyE275 Practice for Describing and Measuring Performanceof Ultraviolet and Visible Spectrophotometers3. Terminology3.1 Definitions:3.1.1 For definitions of terms and symbols, refer to Termi-nology E131.4. S
6、ummary of Test Method4.1 Infrared spectra are prepared from dried films of isolatedpaint vehicles. Vehicle types are identified by comparing thespectra to a collection of reference infrared spectra.5. Significance and Use5.1 The ability to qualitatively identify paint vehicles isuseful for character
7、izing unknown or competitive coatings, forcomplaint investigations, and for in-process control.6. Apparatus6.1 SpectrophotometerA recording double-beam infraredspectrophotometer with a wavelength range from at least 2.5 to15 m and a spectral resolution of at least 0.04 m over thatrange. See Practice
8、 E275.6.2 Demountable Cell Mount, with NaCl window.6.3 Vacuum Drying Oven thermostatically controlled tooperate at 60 6 2C. A water aspirator vacuum source issatisfactory.6.4 Oven, Gravity or Forced Draft, capable of maintainingtemperature from 105 to 110C.7. Procedure7.1 Place the vehicle, separate
9、d from the paint in accordancewith Practice D2372, on a NaCl window and spread to form auniform film. Make sure that the thickness of the film is suchthat when the infrared spectrum is recorded, the transmittanceof the strongest band falls between 5 and 15 % (Note). Dry thefilm in an oven at 105 to
10、110C for 15 min and cool in adesiccator. Inspect the film visually for defects such as bubbles,wrinkles, contamination, etc. If defects are present, cast an-other film. If easily oxidizable substances are present such astung, oiticica, or linseed oils, make sure that the film is dried at60 6 2C in a
11、 vacuum oven for 1 h. If solvents of low volatilitysuch as cyclohexanone or isophorone are present, the film mayneed to be dried for several hours in a 60C vacuum oven.NOTE 1Numerous procedures and variations may be used to obtain afilm on which to prepare a suitable spectrum. These include liquidmo
12、unting between two NaCl plates, transmission through free films, andreflectance from highly polished surfaces.7.2 Immediately record the infrared spectrum from 2.5 to 15m so that a spectral resolution of 0.04 m is maintainedthroughout that range (methods for achieving this resolutionwill vary accord
13、ing to the directions of the manufacturer of theinstrument used).1This test method is under the jurisdiction of ASTM Committee D01 on Paintand Related Coatings, Materials, andApplications and is the direct responsibility ofSubcommittee D01.21 on Chemical Analysis of Paints and Paint Materials.Curren
14、t edition approved June 1, 2011. Published June 2011. Originallyapproved in 1967. Last previous edition approved in 2005 as D2621 87 (2005).DOI: 10.1520/D2621-587R11.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual B
15、ook of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Withdrawn. The last approved version of this historical standard is referencedon www.astm.org.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,
16、 United States.7.3 Compare the spectrum obtained with reference spectraprepared from nonvolatile vehicles of known composition (seeAnnex A1) or consult other published spectra available in theliterature (Annex A3). Interpret the spectrum on the basis ofavailable information, recognizing certain limi
17、tations of infra-red spectroscopy, and qualifying the interpretation accordingly(Annex A2).8. Keywords8.1 infrared spectra; paint binders; solvent reducible paintANNEXES(Mandatory Information)A1. INFRARED SPECTRA OF NONVOLATILE VEHICLES OF KNOWN COMPOSITIONA1.1 A set of reference infrared spectra on
18、 grating andprism is reproduced on the following pages.TABLE 1 Correlation of Absorption Bands in Alkyd SpectraWavelength, m Wavenumbers, cm1Group Vibration2.9 3448 OH stretch3.4 to 3.5 2941 to 2857 alkane CH stretch5.8 1724 ester, C=O stretch6.2, 6.3, 6.6, 6.7 1613, 1587, 1515, 1493 skeletal in-pla
19、ne aromatic C=C6.9, 7.3 1449, 1369 aliphatic CH bending7.5 to 9.4 1333 to 1063 ester, COC stretch (o-phthalate ester)8.6 1163 ester, COC stretch (fatty acid ester)9.6, 13.5, 14.3 1042, 741, 699 out-of-plane aromatic CH bending denoting o-disubstituted benzene ring.D2621 87 (2011)2D2621 87 (2011)3D26
20、21 87 (2011)4D2621 87 (2011)5D2621 87 (2011)6D2621 87 (2011)7D2621 87 (2011)8D2621 87 (2011)9D2621 87 (2011)10D2621 87 (2011)11D2621 87 (2011)12D2621 87 (2011)13D2621 87 (2011)14D2621 87 (2011)15D2621 87 (2011)16D2621 87 (2011)17D2621 87 (2011)18D2621 87 (2011)19D2621 87 (2011)20D2621 87 (2011)21D26
21、21 87 (2011)22A2. CONSIDERATIONS IN THE INTERPRETATION OF INFRARED SPECTRA OF NONVOLATILE VEHICLES SEPARATEDFROM SOLVENT-TYPE PAINTSINTRODUCTIONThe infrared spectra of vehicles recovered from whole paint are presented in Annex A1. The aimof this compilation is to aid those using this test method in
22、the practical interpretation of the spectrathey obtain.The spectra are compiled with one representative spectrum of each vehicle presented in both a prismand a grating format. In the discussion of the spectra, the general assignment refers to the firstspectrum. The subsequent spectra discussion will
23、 include only those bands which aid in theidentification of the particular modifications being illustrated. In addition, some practical informationis provided where it is believed to be helpful to the analyst. In general, previously noted bandassignments are not repeated.The data compiled here were
24、obtained from spectra prepared on very carefully calibratedinstruments. In comparing them to spectra prepared in any given laboratory, it is expected that thewavelength values of absorption bands may differ slightly depending upon the calibration of theinstrument used.GROUP I-ALKYDSA2.1 Spectrum 1:
25、Ortho-Phthalic Alkyd, Medium OilLengthA2.1.1 2.9-m Region (3448 cm1)The 2.9-m band inalkyds is due to the OH stretching vibration. This is usuallyattributed to the unesterified hydroxyl OH on the polyhydricalcohol used in manufacturing the alkyd. This absorption isknown to increase on drying of unsa
26、turated oil modified alkydsdue to oxidation of the double bonds. This absorption band canbe used to determine the hydroxyl number of alkyds.A2.1.2 3.3 to 3.6-m Region (3030 to 2778 cm1)Thebands in this area are all due to aromatic and aliphatic CHstretching vibrations.A2.1.3 5 to 6-m Region (2000 to
27、 1667 cm1)The 5.8-mband in alkyds is due to the combined C=O stretch of thephthalate and fatty acid esters. Unreacted phthalic anhydride, ifpresent, may be detected by the appearance of a sharpabsorption band at approximately 5.6 m (1786 cm1). Freecarboxyl groups (due to unreacted fatty acid or inco
28、mpletelyreacted phthalic acid) may often be detected by the appearanceof a shoulder on the high wavelength (low frequency) side ofthe ester carbonyl band.A2.1.4 6.2 to 6.4-m Region (1613 to 1563 cm1)Thedoublet appearing in this region of the spectrum is due tovibrations associated with the double bo
29、nds in an aromaticring. The band shape and position of this doublet is character-istic of non-oil modified, o-phthalic alkyds.A2.1.5 6.8 to 6.9-m Region (1470 to 1449 cm1)Thisabsorption is produced by CH bending vibrations of methyl-ene (scissoring deformation) and methyl (asymmetrical defor-mation)
30、 groups in the alkyd. The intensity of this absorptionband will vary with oil length.A2.1.6 7.2 to 7.3-m Region (1389 to 1370 cm1)Thisabsorption band is due to the CCH3symmetrical deforma-tion vibration, and is produced by the methyl groups on thefatty acid chains.A2.1.7 7.5 to 10.0-m Region (1333 t
31、o 1000 cm1)Theabsorption bands in this region are due to the COCstretching vibrations of the phthalate ester. These absorptionsare most strongly influenced by the acid portion of the esterrather than the alcoholic portion.A2.1.8 13.5 and 14.2-m Regions (741 and 704 cm1)These two bands are due to out
32、-of-plane bending vibrations ofring hydrogens of aromatic compounds having four adjacenthydrogens (orthodisubstitution).A2.1.9 Comments:A2.1.9.1 Note that in oil-modified alkyds, the intensity ofthe absorption at 8.6 m (1163 cm1) is indicative of theamount of oil modification or oil length of the al
33、kyd. Inunmodified alkyds, this band may be little more than a sideshoulder on the 8.9-m (1124-cm1) COC absorption. Thecorrelation to oil length is only a very general one in that withina given group of alkyds one may say a sample is a “short,”“medium,” or “long” oil type.A2.1.9.2 Alkyd spectra gener
34、ally reveal little or no infor-mation concerning the type of combined oil or polyol present.A2.1.9.3 Identification of polyol and unsaponifiables mayusually be accomplished by infrared examination of saponifi-cation fractions. Identification of the oil acids used usuallyrequires gas chromatographic
35、analysis of the methylated fattyacids recovered by saponification. (For saponification proce-dures see Guide D1467 and Test Method D1962.)A2.2 Spectrum 2: Ortho-Phthalic Alkyd, Long OilLengthA2.2.1 8.6 m (1163 cm1); fatty acid ester COCA2.2.2 CommentsNote the difference in the 8.6-m(1163-cm1) peak c
36、ompared to Spectrum 1, due to increasedoil length.D2621 87 (2011)23A2.3 Spectrum 3: Ortho-Phthalic Alkyd, Tung OilModifiedA2.3.1 10.12 m (988 cm1); C=CC=CC=C Conju-gated triene unsaturationA2.3.2 CommentsNote the difference in band shapes inthe 10 to 10.4-m region (1000 to 962 cm1) compared toSpectr
37、a 1 and 2. Absorption due to conjugated unsaturation (insuch oil types as tung, oiticica, dehydrated castor, and conju-gated safflower) occurs here. Oil types used for alkyds 1 and 2contain only isolated double bonds.A2.4 Spectrum 4: Ortho-Isophthalic AlkydA2.4.1 7.8 m (1282 cm1) isophthalate ester
38、COCA2.4.2 8.2 m (1220 cm1) isophthalate ester COCA2.4.3 8.9 m (1124 cm1) isophthalate ester COCA2.4.4 13.7 m (730 cm1) meta-disubstituted benzene ringA2.4.5 CommentsThe spectrum of this alkyd is typical ofan isophthalic alkyd. The major band that identifies this as anisophthalate is the 13.7-m (730-
39、cm1) band. The presence oforthophthalic alkyd can be suspected by comparison to astraight isophthalic alkyd spectrum (see following) and notingthe influence of the ortho-phthalate at 7.9 m (1266 cm1), 9.0m (1111 cm1), 9.4 m (1064 cm1), and at 14.2 m (704cm1).A2.5 Spectrum 5: Ortho-Phthalic Alkyd, Be
40、nzoic AcidModifiedA2.5.1 14.0 to 14.1 m (714 to 709 cm1); aromatic ringvibration where ring contains five adjacent hydrogens. Positionis characteristic of benzoate esters.A2.5.2 CommentsThe band at approximately 14.0 m(714 cm1) is the identifying peak for this modification.Because of the o-disubstit
41、ution peak at 14.3 m (699 cm1)present in o-phthalates, it is difficult to observe this band whenthe benzoic acid modification drops below 3 %.A2.6 Spectrum 6: Ortho-Phthalic Alkyd, Para-TertiaryButyl Benzoic Acid ModifiedA2.6.1 8.4 m (1190 cm1) COC p-tert. butyl benzoateA2.6.2 9.6 m (1042 cm1) COC p
42、-tert. butyl benzoateA2.6.3 9.8 m (1020 cm1) COC p-tert. butyl benzoateA2.6.4 11.7 m (855 cm1) aromatic ring substitution pat-ternsA2.6.5 12.9 m (775 cm1) aromatic ring substitution pat-ternsA2.6.6 CommentsThe characteristic bands for the identi-fication of the paratertiary butyl benzoic acid modifi
43、cation arethe 11.7-m (855-cm1) and the 12.9-m (775-cm1) bands.The other absorption bands, although sharp and distinctive, cantend to be lost in the background of the spectrum when themodification drops below 2 to 3 %.A2.7 Spectrum 7: Ortho-Phthalic Alkyd, Tall Oil, RosinModifiedA2.7.1 12.3 m (813 cm
44、1) abietic acid ring vibrationA2.7.2 CommentsThe curve shows only a very slightdepression at 12.3 m (183 cm1). In general, the band is neververy intense and, if suspected, the presence of rosin is readilyconfirmed by a Lieberman-Storch spot test. Note also theobscured nature of the 6.3 to 6.5-m (158
45、7 to 1538-cm1)region. This is most likely due to the salt or “soap” formationwith the acids present in the system and the pigment used.A2.8 Spectrum 8: Ortho-Phthalic Alkyd, p-Phenyl PhenolModifiedA2.8.1 11.4 m (877 cm1) associated with substitutedaromatic ringsA2.8.2 12.1 m (826 cm1) associated wit
46、h substitutedaromatic ringsA2.8.3 13.1 m (763 cm1) associated with substitutedaromatic ringsA2.8.4 14.4 m (694 cm1) associated with substitutedaromatic ringsA2.8.5 CommentsThe main identifying band is the13.1-m (763-cm1) band. The other bands are less distinctive,especially the 14.4-m (694-cm1) area
47、. It is always best toconsider the positions of the 3 or 4 absorptions in the far endof the curve as a group in assigning the modifying structure.A2.9 Spectrum 9: Ortho-Phthalic Alkyd, StyreneModifiedA2.9.1 6.7 m (1493 cm1) aromatic ring vibrationA2.9.2 13.2 m (758 cm1) monosubstituted aromatic (5ad
48、jacent ring hydrogens)A2.9.3 14.3 m (699 cm1) monosubstituted aromatic (5adjacent ring hydrogens)A2.9.4 CommentsThe very general forebroadening in the13 to 13.3-m (769 to 758-cm1) area of the ortho substitutionband is characteristic of styrene modification. The 14.3-m(699-cm1) absorption that obscur
49、es the normally present small14.3-m (699-cm1) band is the primary styrene absorption.Note also the sharp 6.7-m (1493-cm1) peak which is asso-ciated with the presence of an aromatic.A2.10 Spectrum 10: Ortho-Phthalic Alkyd, Vinyl TolueneModifiedA2.10.1 6.6 m (1515 cm1) aromatic ring vibrationsA2.10.2 6.7 m (1492 cm1) aromatic ring vibrationsA2.10.3 11.4 m (877 cm1) meta-disu
