1、Designation: D 4499 07Standard Test Method forHeat Stability of Hot-Melt Adhesives1This standard is issued under the fixed designation D 4499; 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 p
2、arentheses indicates the year of last reapproval. Asuperscript epsilon (e) 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
3、 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.
4、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:2D 907 Terminology of AdhesivesD 1544 Test Method for Color of Transparent Liqu
5、ids(Gardner Color Scale)D 3236 Test Method for Apparent Viscosity of Hot MeltAdhesives and Coating MaterialsE 691 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 Terminol
6、ogy D 907.3.2 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, nme
7、asure 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. S
8、ummary 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 s
9、o 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
10、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, perc
11、ent 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 t
12、he 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 ch
13、anges 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 c
14、an be useful in observing batch-to-batch variation or relative thermal stability of alternate adhe-sive formulations. Results can also be useful in selectingapplication equipment and establishing operating conditionsfor satisfactory handling of a particular hot-melt adhesive.5.3 Round-robin testing
15、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 tested in the round robin, the test method waswell suited for testing the heat stability of the adhesives based1This test meth
16、od is under the jurisdiction of ASTM Committee D14 onAdhesives and is the direct responsibility of Subcommittee D14.50 on Hot MeltPressure Sensitive Archive Adhesives.Current edition approved May 1, 2007. Published June 2007. Originallyapproved in 1985. Last previous edition approved in 2000 D 4499
17、95 (2000).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.1Copyright ASTM International, 100 Barr Harbor Driv
18、e, PO Box C700, West Conshohocken, PA 19428-2959, United States.on an EVA copolymer, a polyolefin, and a polyamide. How-ever, because of poor reproducibility, the test method proved tobe unsuitable for assessing the heat stability of the adhesivebased on a block copolymer. Precision of this test met
19、hod isdiscussed in Section 11.6. Apparatus6.1 Glass Beakers, 300-mL, each approximately 6.6-cminside diameter by 11.7 cm high.6.2 Mechanical Convection Oven, with specified tempera-ture uniformity of 61C (1.8F).6.3 Viscometer, rotating-spindle type with leveling stand,stainless steel spindles, and s
20、ample chamber with precisiontemperature controller which provides accuracy of 61.0C orbetter through the range from 100 to 200C.6.4 Glass Standards, 18, as described in Test MethodD 1544.6.5 Glass Tubes, clear, 10.65-mm in inside diameter, andabout 114-mm in outside length, as described in Test Meth
21、odD 1544.6.6 Suitable apparatus for comparing sample and standard,as described in Test Method D 1544.7. Sample Preparation7.1 Large differences exist among hot-melt adhesives intheir hot-melt processing requirements. Many types of adhe-sives, such as those based on an unsaturated or a reactivepolyme
22、r, can be held molten for only a short period of time. Insome cases, these adhesives must be protected against expo-sure of the hot adhesive to the atmosphere. Other types ofadhesives, such as those based on a saturated polymer, can beheld molten and unprotected from the atmosphere for extendedperio
23、ds of time. The adhesive manufacturers recommenda-tions on exposure time and temperature and the need to protectthe molten adhesive against exposure to air must be followed.7.2 Repeated melting or extended storage of a hot-meltadhesive will adversely affect the products performance in aheat-stabilit
24、y test. Choose a representative sample materialfrom batches recently received from the manufacturer.7.3 Avoid contamination of adhesive with water to preventfoaming problems during melting and possible reactivity withadhesive components.8. Procedure8.1 Test TemperatureSet oven and viscometer tempera
25、-ture controller at adhesive manufacturers recommended appli-cation temperature.8.2 Test CycleChoose a test cycle which is representativeof the time period during which the adhesive will be heldmolten in the application equipment to be used. Verify that thecycle chosen is consistent with the adhesiv
26、e manufacturersrecommendations. Two typical test cycles of heat-aging timesat which samples are taken for testing are as follows:Cycle I Cycle IIInitial (no preconditioning) Initial24 h 8 h48 h 18 h96 h 24 h48 h8.3 Initial Data:8.3.1 Melt ViscositySelect a representative sample ofadhesive, as receiv
27、ed from the manufacturer, and measure themelt viscosity at the chosen conditioning temperature inaccordance with Test Method D 3236. For some hot-meltadhesives, the change in viscosity with aging can be affectedby changes in shear rate. Use the same spindle size and speedof rotation to measure the v
28、iscosity of the unaged and all of theheat-aged samples.8.3.2 Color:8.3.2.1 Nonpigmented AdhesivesFill a clear glass tubewith slivers of the hot-melt adhesive in “as-received” condi-tion. Place the tube in an oven set at the minimum temperaturenecessary to produce a transparent melt. Remove the tube
29、ofmolten adhesive from the oven and immediately place into thecolor comparator apparatus. Make the color determination, inaccordance with Test Method D 1544, before the adhesivecools below the cloud point. Record the adhesive color to thenearest color unit.8.3.2.2 Pigmented AdhesivesPlace about 150
30、g of adhe-sive in “as-received” condition into a 300-mL beaker. Heat inan oven to the manufacturers recommended application tem-perature, and stir the adhesive thoroughly to ensure uniformpigment dispersion. Avoid aeration of the adhesive. Prepare anadhesive film 0.25 mm thick on white paper. Select
31、 appropriatevisual color standards such as those used in the PantoneMatching System color chip sets and books. Identify the colorchip that most closely matches the initial adhesive color.NOTE 1The adhesive supplier and adhesive user can jointly preparecustom-made color standard for individual adhesi
32、ves to be tested.8.4 Sample PreparationWeigh 150 g of adhesive into a300-mL beaker and place in the oven. Glass beakers are usedinstead of metal containers to allow the observation of phaseseparation. Prepare three samples for Test Cycle I or foursamples for Test Cycle II. Cover the samples with alu
33、minumfoil prior to placement in the oven. If the use of an inert gasatmosphere during molten processing is recommended by theadhesive manufacturer, provide a continuous inert gas purgefor the adhesive samples during the elevated temperatureconditioning.8.5 Test DataFirst Test Period:8.5.1 SkinningRe
34、move one beaker from the oven at theconclusion of the first conditioning period. Examine the moltenadhesive for the presence of a skin (a thermoset membrane) bycarefully probing the adhesive surface with a metal spatula. Ifskinning is observed, estimate the percentage of adhesivesurface covered. Des
35、cribe the characteristics of the skin usingterms such as: dark color, thin, thick, brittle, or sticky. Checkfor the presence of a skin immediately after removal from theoven to avoid confusing a chilled adhesive surface for a skin.8.5.2 Phase SeparationExamine the conditioned adhesivefor phase separ
36、ation (as evidenced by appearance of discretelayers, opacity, cloudiness, or formation of visible particles),using a fresh sample of molten adhesive for comparisonpurpose. Describe observed phase separation with particularattention directed at specifying the relative amounts andphysical characterist
37、ics of the separated materials.D44990728.5.3 Melt ViscosityCarefully remove any skin from theconditioned adhesive and measure the viscosity according toTest Method D 3236. Use the same spindle size and speed ofrotation as was used to measure the viscosity of the unagedsample. Discontinue the test if
38、 phase separation or gellationoccurs.8.5.4 Color:8.5.4.1 Nonpigmented AdhesivesFill a clear glass tubewith conditioned adhesive, taking care to exclude skin frag-ments. Determine color while molten as described in 8.3.8.5.4.2 Pigmented AdhesivesStir the conditioned moltenadhesive carefully to disper
39、se any settled pigment. Avoidaeration of the sample. Prepare an adhesive film, 0.25 mmthick on white paper. Compare the adhesive color with thevisual standards used to identify the initial adhesive color.Since color matches are likely to be approximate, make thecolor comparisons with color chips in
40、same color series as theinitial color chip. For example:Initial Adhesive ColorPantone 127 Creme Yellow!962h Adhesive ColorCompare with Pantone 128133Since the presence of a skin tends to preserve light color,note the occurrence of a skin with color data.8.6 Test DataRemaining Test PeriodsRepeat 8.5
41、untilthe chosen test sequence is complete or prematurely terminateddue to adhesive gellation or phase separation.9. Calculation9.1 Melt Viscosity:9.1.1 Tabulate viscosity data, and calculate percent changein viscosity (DV) for each test period using the followingformula:DV 5V8h 2 VI! 3 100VI(1)VI= i
42、nitial viscosity, andV8h = viscosity after8hofoven conditioning.9.1.2 See 10.1.4 for report instructions.9.2 Color:9.2.1 Tabulate color data along with the percentage ofadhesive surface which had a skin. Calculate percent change inGardner color (dC) for each test period using the followingformula:DC
43、 5C8h 2 CI!CI3 100 (2)CI= initial Gardner color, andC8= Gardner color after8hofoven conditioning.9.2.2 See 10.1.5 for report instructions.10. Report10.1 Report the following information:10.1.1 Test Conditions:10.1.1.1 Aging temperature.10.1.1.2 Adhesive exposed to or protected from atmo-sphere.10.1.
44、2 Skin Formation:10.1.2.1 Heat aging time at which skin was observed.10.1.2.2 Description of skin.10.1.2.3 Percentage of surface covered.10.1.3 Phase Separation:10.1.3.1 Heat aging time at which phase separation wasobserved.10.1.3.2 Description of phases.10.1.3.3 Percentage of adhesive in each phase
45、.10.1.4 Melt Viscosity (see 9.1):10.1.4.1 Use designations V18h; V24h; V48h; V96h forappropriate test periods. Record the direction of change (or + ) with calculated data.10.1.4.2 Report temperature, spindle size, and revolutionsper minute (rpm) used for each viscosity determination.10.1.5 Color (se
46、e 9.2):10.1.5.1 Use designations C18h, C24h, C48h, C96h, forappropriate test periods.11. Precision and Bias11.1 PrecisionThe precision of this test method is basedon an interlaboratory study of Test Method D 4499, conductedbetween 1974 and 1979. Each of nine laboratories tested fourdifferent hot mel
47、t adhesives. The laboratories obtained onefinal test result for each material over a 48 or 96-hour testingperiod.3Since only individual measurements were taken, noreplicate information is available; therefore, this study does notmeet the basic criteria set forth in Practice E 691. A new studywill be
48、 conducted to address this deficiency.11.1.1 RepeatabilityTwo test results obtained within onelaboratory shall be judged not equivalent if they differ by morethan the “r” value for that material; “r” is the intervalrepresenting the critical difference between two test results forthe same material, o
49、btained by the same operator using thesame equipment on the same day in the same laboratory.11.1.1.1 No repeatability data was collected as part of thisstudy.11.1.2 ReproducibilityTwo test results should be judgednot equivalent if they differ by more than the “R” value for thatmaterial; “R” is the interval representing the difference be-tween two test results for the same material, obtained bydifferent operators using different equipment in different labo-ratories.11.1.2.1 It is expected that the ability of this test method toreproduce changes i
