ASTM D1653 有机涂层水蒸气渗透率的测试方法r.docx

ASTM D1653 有机涂层水蒸气渗透率的测试方法r.docx

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ASTMD1653有机涂层水蒸气渗透率的测试方法r

woodandmasonry,thecoatinghastoallowmoderateamountsofwatervaportopassthroughthefilmwithoutdamagetoit.Hence,thewatervaportransmissioncharacteristicsofcoatingsareimportantinassessingtheirperformanceinpracticaluse.5.2Thepurposeofthesetestmethodsistoobtainvaluesofwatervaportransferthroughcoatingsthatrangeinpermeabil-ityfromhightolow.Thesevaluesareforuseindesign,manufacture,andmarketing.

5.3Thewatervaportransmissionisnotalinearfunctionoffilmthickness,temperatureorrelativehumidity.

5.4Valuesofwatervaportransmissionrate（WVTandwatervaporpermeance（WVPcanbeusedintherelativeratingofcoatingsonlyifthecoatingsaretestedunderthesamecloselycontrolledconditionsoftemperatureandrelativehu-midity,andiftheirthicknessesareequal.

5.5TestMethodA—TheDryCupMethodisthepreferredtestmethodforobtainingvaluesthatrelatetoconventionaldwellingswherehighrelativehumiditiesarenotanticipated.5.6TestMethodB—TheWetCupMethodisthepreferredtestmethodforobtainingvaluesthatrelatetoapplicationswherehighrelativehumiditiesareanticipatedinthevicinityofthebarriermaterial.Ingeneral,themorepermeableacoatingistothepassageofmoistureasistypicalofmanywater-reduciblecoatings,thegreateritsaffinityforwaterandthegreatertheincreaseintransmissionwhentestedinandexposedtohighhumidities.Absorptionofwatermaymakeacoatinglessdense,thusallowingmoisturetodiffuseeasilyandcauseamuchhighermoisturevaportransmissionrate,（WVTRthanwouldoccurindrierenvironments.

6.Apparatus

6.1PermCuporDish,consistingofacontainermadeofanoncorrodingmaterial,impermeabletowaterorwatervapor.Ifthecupordishismadeofaluminum,itmustbeanodizedorgivenaprotectiveclearcoatingtopreventcorrosion.6.1.1Onetypeofcupthatissuitablehasaflangededgeandisequippedwithaseparatecorrespondingflange,sothatthetestspecimencanbeheldbetweenthem.Thecontactingfacesoftheflangesshallbegroundtosuchflatnessthatwhenthefilmisinposition,moisturetransfercanoccuronlythroughtheexposedfilmarea.Forhardfilms,orfilmshavingaveryroughsurface,asoftrubbergasketmaybeinsertedbetweenthefilmandtheflange.Theflangesshallthenbeheldtogetherwithsuitableclamps.

6.1.2Anothersuitablecupisanyopencircularorrectangu-lardishtowhichthetestfilmcanbesealedwithwaxorsealant.6.2TestChamber,withacontrolledtemperatureandrela-tivehumidityasspecifiedinSection4.Airshallbecirculatedthroughoutthechambertomaintainuniformconditionsatalltestlocations.Forloworhighhumidityconditions,astandarddesiccatororothersuitablecabinetmaybeused.Formaintain-ingconstantrelativehumiditybymeansofaqueoussolutions,refertoproceduresoutlinedinPracticeE104.

6.3AnalyticalBalance,havinganadequatecapacityfortheweightofthetestcupsandasensitivityof1mg.

7.ReagentsandMaterials

7.1PurityofWater—Unlessotherwiseindicated,referencetowatershallbeunderstoodtomeanreagentwaterconformingtoTypeIVofSpecificationD1193.

7.2Desiccant,consistingofeitheranhydrouscalciumchlo-ride（CaCL2oranhydrousmagnesiumperchlorate（Mg-（CLO42.Thecalciumchlorideshouldbedriedat400°F（200°Cbeforeuse.Ifcalciumchloridewillreactwiththetestspecimen,anadsorbingdesiccantsuchasasilicagelmaybeusedbutthemoisturegainbythisdesiccantduringthetestmustbelimitedto4%.Usecautioninhandlingmagnesiumperchloratebecauseofpossiblechemicalreactionthatmaybeproducedifitcomesincontactwithsomeorganicmaterialsandissubsequentlyheatedtoregeneratetheanhydroussalt.7.3Sealant,suchaswaxforattachingthetestspecimentothetopofthepermcupordish.Itmustbehighlyresistanttothepassageofwatervapor.Itmustnotloseweightto,orgainweightfrom,theatmosphereinanamount,overtherequiredperiodoftime,thatwouldaffectthetestresultsbymorethan2%.Itmustnotaffectthevaporpressureinawater-filleddish.NOTE1—Amongacceptablesealantsare（1a60:

40mixtureofmicrocrystallinewaxandrefinedcrystallineparafinwax,（2tissueembeddingwax,and（3a50:

50mixtureofbeeswaxandrosin.7.4ReleasePaper,preparefreefilms,wheneverpossibletoeliminatethepotentialinterferenceofsubstrates,onreleasepaper5orglasssubstratesfollowingproceduresoutlinedinPracticeD4708.

7.5FilmSupport,forpreparingfilmsthataretoobrittleorotherwiseunsatisfactoryforhandlingasfreefilms.Supportmaterialssuchaspapercharts,6filterpaper,andglassclothhavebeenfoundsatisfactoryinsomeinstances.Suchsupportcanhaveaneffectonthetestresults.

8.TestSpecimens

8.1Itisveryimportantthatthetestspecimensbesmooth,andcompletelycontinuousfilmsofuniformthicknessthrough-outthetestarea.ApplyairdryingcoatingstosubstratesusingoneofthemethodsdescribedinPracticesD823orD4708.NOTE2—Specialtestconditionsmayrequirethatthecoatingbeappliedbybrushing,rollercoatingorotherspecialmethods.Thethicknessofthecoatingappliedshallbewithinnormalrangeforthetypeofmaterialundertest,andshallnotvarybymorethan5%ofthetotalthicknessinanytestseries.

NOTE3—Whenapplyingbakingfinishes,bakeforspecifiedtimeandtemperatureinaccordancewithmanufacturers’instructions.Permeancemayvarywiththebakingscheduleorthetimeofairdrying.

8.2Airdrythecoatedmaterialinahorizontalpositionfor7daysinaroompreferablymaintainedat73.563.5°F（2362°Cand5065%relativehumidity.Ifthematerialistobetestedasafreefilm,removeitfromthesubstrateandallowthepreviouslyunexposedsurfacetodryforanadditional7days.Thedryingschedulemaybemodifiedasrecommendedbymanufacturer.

5ThesolesourceofsupplyofreleasePaper,FormRP-1K,knowntothecommitteeatthistimeistheLenetaCo.,15WhitneyRd.,Mahwah,NJ07430.Ifyouareawareofalternativesuppliers,pleaseprovidethisinformationtoASTMHeadquarters.Yourcommentswillreceivecarefulconsiderationatameetingoftheresponsibletechnicalcommittee,1whichyoumayattend.

6Thesolesourceofsupplyofpapercharts,FormNWK,knowntothecommitteeatthistimeistheLenetaCo.,15WhitneyRd.,Mahwah,NJ07430.Ifyouareawareofalternativesuppliers,pleaseprovidethisinformationtoASTMHeadquarters.Yourcommentswillreceivecarefulconsiderationatameetingoftheresponsibletechnicalcommittee,1whichyoumay

attend.

NOTE4—Examinetestfilmsforthepresenceofpinholesorotherdefectsbeforecommencingthetest.Itmaybeadvisabletoapplythetestmaterialintwocoats,applyingthesecondcoatperpendiculartothefirstcoatandallowingforanadequatedryingperiodbetweencoatstoachievethedesiredfilmthickness.

8.3MeasurethethicknessofthetestspecimeninseveralplaceswithamicrometerusingproceduresinTestMethodsD1005toensureauniformthickness.

8.4Whencoatingsareappliedtosupportmaterials,thecoatedsideofthetestspecimenshouldbeplacedawayfromthedesiccantortowardsthewaterinthecup,dependingupontheserviceenvironment.Coatingsshouldnotbeappliedtobothsidesofasupport.Glassclothispreferredforcoatingsthatarecuredbybaking.

TESTMETHODA—DRYCUPMETHOD9.TestConditions

9.1Unlessotherconditionsareagreeduponbetweenthepurchaserandtheseller,thetestsshallbeperformedunderoneormoreofthefollowingconditions:

9.1.1ConditionA—Testchamberorcabinetmaintainedat73°61°F（2360.6°Cand5062%relativehumidity.9.1.2ConditionB—Testchamberordesiccatormaintainedat10061°F（3860.6°Cand9062%relativehumidity.10.Procedure

10.1Prepareatleastthreepermcupsordishesforeachtestmaterialasfollows:

10.1.1Fillthecupswithdesiccanttowithin1⁄4in.（6mmofthetopedge.

10.1.2Ifthecupsareequippedwithflanges,placethetestspecimenbetweentheflangesandadjusttheclampstoholditfirmlyinposition.

10.1.3Ifthecupsarenotequippedwithflanges,sealthetestspecimentothetopedgeofthecupswithwaxasfollows:

10.1.3.1Firstcarefullyplacethetestspecimen,cuttothesizeoftheframe,onathincardboardringsoakedinmoltenwax.

10.1.3.2Thenplacethespecimen-coveredframeoverthemouthofthecup.Thoroughlysealtheframetotheedgeofthecupatthetemperaturetobeusedinthetest.Ifthecoatingisonasubstrateorsupport,placethecoatedsideawayfromthedesiccantinthecup.

NOTE5—Imperfectionsinthefilmthatarenotreadilyvisiblemayproduceinconsistentresults;consequentlymakesurethatthetestisalwaysrunatleastintriplicate.

10.2Weightheloadedcupsto1mgandifatestchamberisnotbeingused,placetheminthetestcabinetsordesiccators.Recordtime,temperature,andrelativehumidity.10.3Removeifnecessary,thecupsforperiodicweighingtodetermineweightgain.CoatingsexpectedtohavehighWVTratings,over10perms,mayrequireweighingsmorefrequentlythanonceaday.

10.4Ingeneral,weighthecupsevery24hforaperiodof3weeks,oruntiltheweightchangeversustimebecomesconstant.Recordthetimethatweighingsaretakentotheprecisionofapproximately1%ofthetimespanbetweenweighings.Thus,ifweighingsaremadeeveryday,atimetothenearest15minuteswouldbeallowed.

10.5Shakecupscontainingdesiccanteverydaytopreventsurfacesaturationofthematerial.Ifmoistureabsorbedbythedesiccantexceeds20%ofthedesiccantweight,discontinuethetest.

10.6Returnthecupstothetestchamberimmediatelyafterweighing.

TESTMETHODB—WETCUPMETHOD

11.TestCon