1、Designation: D2621 87 (Reapproved 2011)D2621 87 (Reapproved 2016)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 a
2、doption or, in the case of 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 characterization or identific
3、ation of separated paint vehicle solids by infraredspectroscopy within the limitations of infrared spectroscopy.1.2 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate saf
4、ety and health practices and determine the applicability of regulatorylimitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D1467 Guide for Testing Fatty Acids Used in Protective Coatings (Withdrawn 2003)3D1962 Test Method for Saponification Value of Drying Oils, Fatty Acids, and Polym
5、erized Fatty Acids (Withdrawn 2004)3D2372 Practice for Separation of Vehicle From Solvent-Reducible PaintsE131 Terminology Relating to Molecular SpectroscopyE275 Practice for Describing and Measuring Performance of Ultraviolet and Visible Spectrophotometers3. Terminology3.1 Definitions:3.1.1 For def
6、initions of terms and symbols, refer to Terminology E131.4. Summary of Test Method4.1 Infrared spectra are prepared from dried films of isolated paint vehicles. Vehicle types are identified by comparing thespectra to a collection of reference infrared spectra.5. Significance and Use5.1 The ability t
7、o qualitatively identify paint vehicles is useful for characterizing unknown or competitive coatings, forcomplaint investigations, and for in-process control.6. Apparatus6.1 SpectrophotometerA recording double-beam infrared spectrophotometer with a wavelength range from at least 2.5 to 15 m and a sp
8、ectral resolution of at least 0.04 m over that range. See Practice E275.6.2 Demountable Cell Mount, with NaCl window.6.3 Vacuum Drying Oven thermostatically controlled to operate at 60 6 2C. A water aspirator vacuum source is satisfactory.6.4 Oven, Gravity or Forced Draft, capable of maintaining tem
9、perature from 105 to 110C.1 This test method is under the jurisdiction of ASTM Committee D01 on Paint and Related Coatings, Materials, and Applications and is the direct responsibility ofSubcommittee D01.21 on Chemical Analysis of Paints and Paint Materials.Current edition approved June 1, 2011Dec.
10、1, 2016. Published June 2011December 2016. Originally approved in 1967. Last previous edition approved in 20052011 asD2621 87 (2005).(2011). DOI: 10.1520/D2621-87R11.10.1520/D2621-87R16.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceast
11、m.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.3 The last approved version of this historical standard is referenced on www.astm.org.This document is not an ASTM standard and is intended only to provide the user of an ASTM
12、 standard an indication of what changes have been made to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof the standard as published b
13、y ASTM is to be considered the official document.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States17. Procedure7.1 Place the vehicle, separated from the paint in accordance with Practice D2372, on a NaCl window and spread to form aunifo
14、rm film. Make sure that the thickness of the film is such that when the infrared spectrum is recorded, the transmittance of thestrongest band falls between 5 and 15 % (Note). Dry the film in an oven at 105 to 110C for 15 min and cool in a desiccator. Inspectthe film visually for defects such as bubb
15、les, wrinkles, contamination, etc. If defects are present, cast another film. If easilyoxidizable substances are present such as tung, oiticica, or linseed oils, make sure that the film is dried at 60 6 2C in a vacuumoven for 1 h. If solvents of low volatility such as cyclohexanone or isophorone are
16、 present, the film may need to be dried for severalhours in a 60C vacuum oven.NOTE 1Numerous procedures and variations may be used to obtain a film on which to prepare a suitable spectrum. These include liquid mountingbetween two NaCl plates, transmission through free films, and reflectance from hig
17、hly polished surfaces.7.2 Immediately record the infrared spectrum from 2.5 to 15 m so that a spectral resolution of 0.04 m is maintainedthroughout that range (methods for achieving this resolution will vary according to the directions of the manufacturer of theinstrument used).7.3 Compare the spect
18、rum obtained with reference spectra prepared from nonvolatile vehicles of known composition (seeAnnexA1) or consult other published spectra available in the literature (AnnexA3). Interpret the spectrum on the basis of availableinformation, recognizing certain limitations of infrared spectroscopy, an
19、d 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 grating and prism is reproduced on
20、the following pages.TABLE 1 Correlation of Absorption Bands in Alkyd SpectraWavelength, m Wavenumbers, cm1 Group 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-plane aromatic C=C6.9, 7.3 1449, 1369
21、 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 (2016)2D2621 87 (2016)3D2621 87 (2016)4D2621 87 (2016)5D2621
22、 87 (2016)6D2621 87 (2016)7D2621 87 (2016)8D2621 87 (2016)9D2621 87 (2016)10D2621 87 (2016)11D2621 87 (2016)12D2621 87 (2016)13D2621 87 (2016)14D2621 87 (2016)15D2621 87 (2016)16D2621 87 (2016)17D2621 87 (2016)18D2621 87 (2016)19D2621 87 (2016)20A2. CONSIDERATIONS IN THE INTERPRETATION OF INFRARED S
23、PECTRA 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 the practical interpretation of the spectrathey obtain.The spectra a
24、re 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 include only those bands which aid in theidentification of the part
25、icular 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 obtained from spectra prepared on very carefully calibratedinstrumen
26、ts. 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: Ortho-Phthalic Alkyd, Medium Oil LengthA2.1.1 2.9-m Region (3448 cm1
27、)The 2.9-m band in alkyds is due to the OH stretching vibration. This is usually attributedto the unesterified hydroxyl OH on the polyhydric alcohol used in manufacturing the alkyd. This absorption is known to increaseon drying of unsaturated oil modified alkyds due to oxidation of the double bonds.
28、 This absorption band can be used to determinethe hydroxyl number of alkyds.A2.1.2 3.3 to 3.6-m Region (3030 to 2778 cm1)The bands in this area are all due to aromatic and aliphatic CH stretchingvibrations.A2.1.3 5 to 6-m Region (2000 to 1667 cm1)The 5.8-m band in alkyds is due to the combined C=O s
29、tretch of the phthalateand fatty acid esters. Unreacted phthalic anhydride, if present, may be detected by the appearance of a sharp absorption band atD2621 87 (2016)21approximately 5.6 m (1786 cm1). Free carboxyl groups (due to unreacted fatty acid or incompletely reacted phthalic acid) mayoften be
30、 detected by the appearance of a shoulder on the high wavelength (low frequency) side of the ester carbonyl band.A2.1.4 6.2 to 6.4-m Region (1613 to 1563 cm1)The doublet appearing in this region of the spectrum is due to vibrationsassociated with the double bonds in an aromatic ring. The band shape
31、and position of this doublet is characteristic of non-oilmodified, o-phthalic alkyds.A2.1.5 6.8 to 6.9-m Region (1470 to 1449 cm1)This absorption is produced by CH bending vibrations of methylene(scissoring deformation) and methyl (asymmetrical deformation) groups in the alkyd. The intensity of this
32、 absorption band willvary with oil length.A2.1.6 7.2 to 7.3-m Region (1389 to 1370 cm1)This absorption band is due to the CCH3 symmetrical deformationvibration, and is produced by the methyl groups on the fatty acid chains.A2.1.7 7.5 to 10.0-m Region (1333 to 1000 cm1)The absorption bands in this re
33、gion are due to the COC stretchingvibrations of the phthalate ester. These absorptions are most strongly influenced by the acid portion of the ester rather than thealcoholic portion.A2.1.8 13.5 and 14.2-m Regions (741 and 704 cm1)These two bands are due to out-of-plane bending vibrations of ringhydr
34、ogens of aromatic compounds having four adjacent hydrogens (orthodisubstitution).A2.1.9 Comments:A2.1.9.1 Note that in oil-modified alkyds, the intensity of the absorption at 8.6 m (1163 cm1) is indicative of the amount of oilmodification or oil length of the alkyd. In unmodified alkyds, this band m
35、ay be little more than a side shoulder on the 8.9-m(1124-cm1) COC absorption. The correlation to oil length is only a very general one in that within a given group of alkydsone may say a sample is a “short,” “medium,” or “long” oil type.A2.1.9.2 Alkyd spectra generally reveal little or no informatio
36、n concerning the type of combined oil or polyol present.A2.1.9.3 Identification of polyol and unsaponifiables may usually be accomplished by infrared examination of saponificationfractions. Identification of the oil acids used usually requires gas chromatographic analysis of the methylated fatty aci
37、ds recoveredby saponification. (For saponification procedures see Guide D1467 and Test Method D1962.)A2.2 Spectrum 2: Ortho-Phthalic Alkyd, Long Oil LengthA2.2.1 8.6 m (1163 cm1); fatty acid ester COCA2.2.2 CommentsNote the difference in the 8.6-m (1163-cm1) peak compared to Spectrum 1, due to incre
38、ased oil length.A2.3 Spectrum 3: Ortho-Phthalic Alkyd, Tung Oil ModifiedA2.3.1 10.12 m (988 cm1); C=CC=CC=C Conjugated triene unsaturationA2.3.2 CommentsNote the difference in band shapes in the 10 to 10.4-m region (1000 to 962 cm1) compared to Spectra 1 and2. Absorption due to conjugated unsaturati
39、on (in such oil types as tung, oiticica, dehydrated castor, and conjugated safflower)occurs here. Oil types used for alkyds 1 and 2 contain only isolated double bonds.A2.4 Spectrum 4: Ortho-Isophthalic AlkydA2.4.1 7.8 m (1282 cm1) isophthalate ester COCD2621 87 (2016)22A2.4.2 8.2 m (1220 cm1) isopht
40、halate 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 of an isophthalic alkyd. The major band that identifies this as anisophthalate is the 13.7-m (730-cm1) band. The presence of ortho
41、phthalic alkyd can be suspected by comparison to a straightisophthalic alkyd spectrum (see following) and noting the influence of the ortho-phthalate at 7.9 m (1266 cm1), 9.0 m (1111cm1), 9.4 m (1064 cm1), and at 14.2 m (704 cm1).A2.5 Spectrum 5: Ortho-Phthalic Alkyd, Benzoic Acid ModifiedA2.5.1 14.
42、0 to 14.1 m (714 to 709 cm1); aromatic ring vibration where ring contains five adjacent hydrogens. Position ischaracteristic of benzoate esters.A2.5.2 CommentsThe band at approximately 14.0 m (714 cm1) is the identifying peak for this modification. Because of theo-disubstitution peak at 14.3 m (699
43、cm1) present in o-phthalates, it is difficult to observe this band when the benzoic acidmodification drops below 3 %.A2.6 Spectrum 6: Ortho-Phthalic Alkyd, Para-Tertiary Butyl Benzoic Acid ModifiedA2.6.1 8.4 m (1190 cm1) COC p-tert. butyl benzoateA2.6.2 9.6 m (1042 cm1) COC p-tert. butyl benzoateA2.
44、6.3 9.8 m (1020 cm1) COC p-tert. butyl benzoateA2.6.4 11.7 m (855 cm1) aromatic ring substitution patternsA2.6.5 12.9 m (775 cm1) aromatic ring substitution patternsA2.6.6 CommentsThe characteristic bands for the identification of the paratertiary butyl benzoic acid modification are the11.7-m (855-c
45、m1) and the 12.9-m (775-cm1) bands. The other absorption bands, although sharp and distinctive, can tend tobe lost in the background of the spectrum when the modification drops below 2 to 3 %A2.7 Spectrum 7: Ortho-Phthalic Alkyd, Tall Oil, Rosin ModifiedA2.7.1 12.3 m (813 cm1) abietic acid ring vibr
46、ationA2.7.2 CommentsThe curve shows only a very slight depression at 12.3 m (183 cm1 ). In general, the band is never veryintense and, if suspected, the presence of rosin is readily confirmed by a Lieberman-Storch spot test. Note also the obscured natureof the 6.3 to 6.5-m (1587 to 1538-cm1) region.
47、 This is most likely due to the salt or “soap” formation with the acids present inthe system and the pigment used.A2.8 Spectrum 8: Ortho-Phthalic Alkyd, p-Phenyl Phenol ModifiedA2.8.1 11.4 m (877 cm1) associated with substituted aromatic ringsD2621 87 (2016)23A2.8.2 12.1 m (826 cm1) associated with
48、substituted aromatic ringsA2.8.3 13.1 m (763 cm1) associated with substituted aromatic ringsA2.8.4 14.4 m (694 cm1) associated with substituted aromatic ringsA2.8.5 CommentsThe main identifying band is the 13.1-m (763-cm1) band. The other bands are less distinctive, especiallythe 14.4-m (694-cm1) ar
49、ea. It is always best to consider the positions of the 3 or 4 absorptions in the far end of the curve as agroup in assigning the modifying structure.A2.9 Spectrum 9: Ortho-Phthalic Alkyd, Styrene ModifiedA2.9.1 6.7 m (1493 cm1) aromatic ring vibrationA2.9.2 13.2 m (758 cm1) monosubstituted aromatic (5 adjacent ring hydrogens)A2.9.3 14.3 m (699 cm1) monosubstituted aromatic (5 adjacent r
