ASTM_D_4499_-_07_2015.pdf

Designation:D449907(Reapproved 2015)Standard Test Method forHeat Stability of Hot-Melt Adhesives1This standard is issued under the fixed designation D4499;the number immediately following the designation indicates the year oforiginal adoption 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 evaluation of hot-meltadhesives with respect to the change in properties that occurswhile the adhesive is aged in the molten state during hot-meltapplication.Melt properties monitored are viscosity,color,skinformation,and phase separation.1.2 The values stated in SI units are to be regarded as thestandard.1.3 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 and determine the applica-bility of regulatory limitations prior to use.2.Referenced Documents2.1 ASTM Standards:2D907 Terminology of AdhesivesD1544 Test Method for Color of Transparent Liquids(Gard-ner Color Scale)D3236 Test Method for Apparent Viscosity of Hot MeltAdhesives and Coating MaterialsE691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method3.Terminology3.1 DefinitionsMany of the terms found in this testmethod are defined in Terminology D907.3.2 Definitions of Terms Specific to This Standard:3.2.1 color,nthe aspect of the appearance of an objectdependent upon the spectral composition of the incident light,the spectral reflectance or transmittance of the object,and thespectral response of an observer.3.2.2 melt viscosity,nmeasure of the ratio of shear stressto shear rate when the hot-melt is in its molten state.3.2.3 phase separation,nformation of a second liquidportion from a previously homogenous liquid over time.3.2.4 skin formation,nappearance of a relatively looselayer at the surface of a polymeric material.4.Summary of Test Method4.1 Samples of hot-melt adhesives are conditioned at theadhesive manufacturers recommended application tempera-ture for a conditioning cycle that corresponds to the expectedresidence time during which the adhesive will be held moltenin the storage and application equipment.If so specified by theadhesive manufacturer,the molten adhesive will be protectedagainst exposure to air.The total residence time is divided intotwo or three intervals at which points the aged adhesive colorand melt viscosity are measured and compared to the initialadhesive color and viscosity.Prior to measuring the meltviscosity and color,the adhesive is subjectively evaluated forevidence of phase separation and surface skinning.Separateadhesive samples are conditioned for each test period.4.2 The test report includes percent change in melt viscosity,percent of adhesive surface skinned,percent change in Gardnercolor,and description of phase separation,if any.5.Significance and Use5.1 Hot-melt adhesives must generally be applied at rela-tively high temperatures in order that the adhesive viscosity islow enough that it can be readily handled in typical hot-meltequipment.Changes in the adhesive caused by exposure to thesevere environment required during hot-melt processing willdisrupt the adhesive application process and may affect thequality of the adhesive bond.Changes in adhesive viscositymay affect the quantity of adhesive dispensed by the applicator.Phase separation or changes in viscosity and color may be anindication of changes occurring in the adhesive which couldaffect the quality of the adhesive joint.A skin formed on theadhesive may eventually clog the applicator nozzle or die.5.2 The data generated in this test procedure are compara-tive in nature.Results can be useful in observing batch-to-batch variation or relative thermal stability of alternate adhe-sive formulations.Results can also be useful in selecting1This test method is under the jurisdiction of ASTM Committee D10 onPackaging and is the direct responsibility of Subcommittee D10.14 on Tape andLabels.Current edition approved Oct.15,2015.Published October 2015.Originallyapproved in 1985.Last previous edition approved in 2007 as D4499 07.DOI:10.1520/D4499-07R15.2For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For Annual Book of ASTMStandards volume information,refer to the standards Document Summary page onthe ASTM website.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 application equipment and establishing operating conditionsfor satisfactory handling of a particular hot-melt adhesive.5.3 Round-robin testing showed that the reproducibility ofthis test method can depend strongly on the characteristics ofthe adhesive being tested.Results showed that,for the particu-lar adhesives