(i)ahydrophilic-lipophiliccopolymerincombinationwithamodifiedtanninand/or
(ii)adiallyldimethylammoniumchloridepolymerincombinationwithamodifiedtannin.
(a)addingtothesprayboothwateratleastabout500ppmofmodifiedtannincompoundsformedbyreactingacondensedtanninwithbothanaminocompoundandanaldehyde;
(b)addingtothesprayboothwateratleastabout300ppmofpolymersderivedfromhydrophilic-lipophilicquaternaryammoniumrepeatunitsoftheformula:##STR2##whereinR1-QisalipophilicradicalincludingR1whichcomprisesanaliphatichydrocarbonchainhavingacarbonchainlengthbetweenabout7andabout28carbonatomsandQ,whichisalinkagegroupselectedfromthegroupconsistingofbenzylgroups,estergroups,andaminegroupsthatcovalentlylinksthelipophilicchainofR1tothequaternarynitrogen;whereineachR2isindependentlyselectedfromalkyl,hydroxyalkyl,orarylgroupsoffrom1to7carbonatoms;whereinR3isanethylenicallyunsaturatedhydrophilicgroupselectedfromacrylicestergroupsoftheformulaCH2--CR4--CO--O--,whereR4ishydrogenormethyl,acrylamidegroupsoftheformulaCH2--CR5--CO--NH--,whereR5ishydrogenormethyl,vinylpyrrolidonegroups,andhydroxyethylmethacrylategroups;andwhereinX-isananion;
(c)providingapHaboveabout6.5inthesprayboothwatersuchthatmodifiedtanninaddedinstep(a)formsaflocwhichisdispersedinthesprayboothwaterfordetackification,withthepolymeraddedinstep(b)stabilizingsuchflocandimprovingdetackificationand
(d)separatingtheflocandpaintparticlefromsaidsprayboothwater.
(b)addingtothesprayboothwateratleastabout50ppmofdiallyldialkylquaternaryammoniumpolymers,whereinthepolymershaveamolecularweiqhtbetweenabout100,000and300,000andachargedensitybetweenabout4.0and8.0meq/g;
(c)providingapHaboveabout6.5inthesprayboothwatersuchthatthemodifiedtanninaddedinstep(a)formsapinflocwhichisdispersedinthesprayboothwaterfordetackification,withthepolymeraddedinstep(b)stabilizingsaidflocandimprovingdetackificationand
(d)separatingtheflocandpaintparticlesfromsaidsprayboothwater.
FIELDOFTHEINVENTION
Thisinventionrelatestotreatmentofpaintsprayboothwastesandinparticulartotreatmentofwastepaintaccumulatedinsprayboothprocesswaterusingtreatmentformulationswhichpreventagglomerationofpaintsprayparticles.BACKGROUNDOFTHEINVENTION
Itis,therefore,desirabletotreatthewaterintheboothinsuchawayastorendertheoversprayedcoatingmaterialfreeofstickinessandtackinesssothatitwillreadilyseparateitselffromthewater,notadheretothecurtainwalls,pipes,pumpsandotherinternalsofthesprayboothsystem,andremainasadetackifiedfloatingsludge.
Oneapproachtodetackificationhasbeentocombinecertainpolymericmaterialswithamphotericmetals.Thus,forexample,U.S.Pat.No.3,861,887disclosestreatmentofpaintboothwashwaterwithablendofpolycationicwaterdispersiblepolymerwithawater-solublesaltofanamphotericmetaltoreducethetackinessofpaint.Oneproblemwiththisapproachisthatuseofmetals,suchaszinc,cancreateadditionaldisposalconcernsforthewastewaterandsludgerecoveredfromit.
Anotherapproachhasbeentouseclay-basedtreatment.Forexample,U.S.Pat.No.4,504,395disclosesthatcertainhectoriteclayscanbeeffectivelyusedtodetackifyoversprayedpaint.Aproblemwiththisapproachisthatthesludgeproducedusingclayscanbedifficulttodewater,resultinginlargervolumesofpotentiallyhazardousmaterialsrequiringhaul-outtoasecurelandfill.
Otherapproachesusingvarioustreatmentshavealsoreportedlybeenconsidered.However,thereremainsaneedforeffectivepaintspraytreatmentwhichdetackifiespaintoversprayandwhichdoesnotaggrevatewastesludgedisposalproblems.Moreover,somepaintsprayfacilitieshavefoundthatpredilutionofpaintswithvariousorganicsolventcombinations,forexample,methylethylketone,toluene,xylene,etc.canbepracticedadvantageouslytoimprovethecoatingfinishandeconomizeuponpaintwastage,andpaintspraytreatmentwhichcaneffectivelydetackifyoverspraycontainingpredilutedpaintformulationscanbeespeciallyvaluable.SUMMARYOFTHEINVENTION
Itisanobjectofthisinventiontoinhibittheaccumulationofpaintwithintheeliminators,recirculationpumps,sludgetanks,watercurtains,andotherequipmentofpaintsprayboothapparatus.
Itisanotherobjectoftheinventiontoprovideforimprovedremovalofdetackifiedpaintfromanaqueoussystem.
Itisafurtherobjectofthisinventiontoprovideatreatmentforpaintsprayfacilitiesemployingpaintswhichhavebeenpredilutedwithorganicsolventformulations.
Itisstillanotherobjectofthisinventiontoprovideadetackifiedsludgewhichisreadilydewatered.
Itisyetanotherobjectofthisinventiontoprovidefordetackificationwhichcanbepracticedwithoutrelyingontoxicmetalsasessentialcomponents.
Theseandotherobjectsandadvantagesofthepresentinventionwillbecomeapparentfromthefollowingdetaileddescriptionoftheinvention.BRIEFDESCRIPTIONOFTHEDRAWING
FIG.1isaschematicisometricdrawingofanapparatususedforevaluatingcontrolofpaintoverspray.DETAILEDDESCRIPTIONOFTHEINVENTION
Thepresentinventionisdirectedtotheuseoftwocationiccomponents,eachcomprisingselectedorganiccompounds,incombinationtoachieveadvantageousdetackificationofpaintsprayboothwastes.Oneofthosecomponentsisselectedfromcertainmodifiedtannins.Themodifiedtannincompoundswhichmaybeusedinthisinventionarethoseformedbyreactingcondensedtanninssuchasextractsfromquebrachowoodorwattlebark,whicharepolyphenolic,withbothanaldehyde,particularlyformaldehyde,andanaminocompoundsuchasmonoethanolamine,ammonia,andammoniumsaltssuchasammoniumchloride.Thereactionbetweenformaldehydeandaminocompoundsandacompound,suchasaphenoliccompound,whichcontainsreactivehydrogenatomsisknownastheMannichReaction.Themolecularweightofthepreferredmodifiedtanninmaterialsisconsideredtobewithintherangeof5,000to50,000.Preferably,thetannin-basedmaterialsusedinthisinventionhaveachargedensityofbetweenabout0.7andabout5.0milliequivalentspergram(meq/g).
U.S.Pat.No.4,558,080describestheproductionofatannin-basedflocculantusingmonoethanolamineastheaminocompoundandformaldehydeasthealdehyde.Asdescribedtherein,areactorcontaining130.75gramsofde-ionizedwaterwaspreheatedto150°F.Gradually125.75gramsofMimosaextract,availableasaspray-driedtanninpowdersoldbyCanadianPackers,Ltd.,wasgraduallyaddedwhilestirring.Thetemperaturewasmaintainedatabout130°to140°Fahrenheit.Aftercompletedissolution,thematerialwascooledto110°Fahrenheit.Then0.15gramsofasiliconantifoamer,SiliconeBmadebyDowChemical,wasadded.
Totheaqueoustanninsolution,47.65gramsofmonoethanolaminewasaddedtoyieldaprimaryaminetotanninratioof1.86:1whilemixing,andthetemperatureofthereactionmixturewasallowedtoriseto130°Fahrenheitanditwasmaintainedatthistemperatureuntilalloftheaminewasadded.Inordertomaintaintheacidconditionsofthereactionmixture80gramsofa32%activehydrochloricacidwasaddedtobringthepHintherangeof6.4to6.7andthetemperaturewasallowedtoriseto140°Fahrenheit.Uponformingitsinitialtannin/aminesolution,themixturewasthencooledto120°Fahrenheit.
Next,theformaldehydewasaddedintheformof62.70gramsof37%activeformaldehydeandthetemperatureduringthisadditionwasmaintainedbetween120°and130°Fahrenheit.Astheformaldehydewasmixedwiththeprevioussolutionthesolutionwasheatedtoinitiatethereactionandthetemperaturewascontrolledsothatitwasnotallowedtogoaboveabout180°Fahrenheit.AsthereactionproceededtheviscosityofthesolutionwasmonitoredusingaBrookfieldLVTviscosimeterwherethesamplesweremeasuredattemperaturesofabout178°to180°Fahrenheit.Whentheviscosityreadingreached38to40cps,thedesireddegreeofreactionwasobtained.Atthispoint,thereactionmaterialwasquenchedbytheadditionofexternalcoolingand45.20gramsofde-ionizedwaterand7.8gramsofmuriaticacidtoobtainafinalpHof2.4andtoobtainasolidscontentofabout40.2%andafinalviscosityof246cps.
AsimilarcompositionproducedinaccordancewithU.S.Pat.No.4,558,080wasavailablecommerciallyastheproductKlar-Aid2400producedbyDearbornDivision,W.R.Grace&Co.Thiscompositioncontainedapproximately40%ofamodifiedcationictannin(mol.wt.about10,000;chargedensityabout1.5-4.0)formedasthereactionproductofMimosaextract,formaldehyde,andmonoethanolamine.Thetannin-basedproductwasusedinthenon-limitingexampleswhichfollowtodemonstrateitsrelativeeffectivenessincombinationwiththeothercationiccomponentofthisinvention.
Thelipophilicradical,R1-Q,maybesaturatedorunsaturated,straightchainorbranched.ApreferredR1-Qradicalisdodecylbenzylchloride.ApreferredR2groupismethyl.
R3ispreferablyanalkylmethacrylate;mostpreferablyethylmethacrylate.
Suitableanions(i.e.X-)areprovidedbyhalides,alkylsulphates,alkylbenzonesulphonates,phenoxyalkylenesulphates,anddialkylsulphosuccinates.X-ispreferablyahalide.
Thehydrophilic-lipophilicrepeatunitsmaybepreparedinaccordancewiththewell-knowntechnologyexemplifiedinU.S.Pat.Nos.3,780,092and3,936,492whichareincorporatedhereinbyreference;andthehydrophilic-lipophilicpolymersofthisinventionmaybeconvenientlyprovidedbypolymerizingtherepeatunitsviatheethylenicallyunsaturatedgroupstherein.Preferably,thehydrophilic-lipophilicpolymerhasamolecularweightbetweenabout50,000and500,000,andachargedensitybetweenabout2.0and8.0meq/g.Polymershavingmolecularweightsofbetweenabout80,000and150,000areparticularlypreferred.Preparationofthesehydrophilic-lipophilicpolymersandthehydrophilic-lipophilicpolymersascompoundsarenotpartofthisinvention;andthehydrophilic-lipophilicpolymeremployedinthefollowingnon-limitingexamplewaspreparedbyothersandsuppliedtotheinventor'semployer.EXAMPLEI
TheeffectivenessofthecombinationofthisinventionindetackifyingpaintoverspraywasevaluatedusingthepaintsprayapparatusdepictedschematicallyinFIG.1.Theapparatus(10)comprisesaspraychamber(12)whichhasafrontwall(14),sidewalls(16)and(18),arearwall(20)andafloor(22).Anelevatedreservoir(24)ispositionedatthefrontwall(14)withthetopedge(26)ofthefrontwallformingthelowestsideofthereservoirsuchthatwastesoverflowingfromthereservoirformawatercurtainforthefrontwall(14).
Anoutlet(28)isprovidedinthespraychamberfloor(22),andwateroverflowingfromthereservoirpassesintooutlet(28)andthroughpiping(30)tothesecondmixingchamber(32).Themixingchamber(32)comprisesendwalls(34)and(36),sidewalls(38)and(40),andfloor(42),andisdividedintoafirstcompartment(44)andasecondcompartment(46)byaweir(48).Waterflowingfrompiping(30)flowsintothefirstcompartment,andanoutlet(50)isprovidedinthefloorofthesecondcompartment.Thetopedge(52)oftheweirterminatesbelowthewallsofthemixingchambersuchthatwateroverflowsfromthefirstcompartmentintothesecondcompartment,andthenintooutlet(50).Piping(52)directsthewaterfromoutlet(50)intothethirdmixingchamber(54)whichcomprisesfourwalls(56)(57)(58)and(59),andfloor(60).Theopenend(61)ofinletpiping(62)forpump(64)ispositionedinthemixingchamber(54)suchthatthepump(64)canbeusedtowithdrawwaterfromthemixingchamber.Waterpumpedfromthemixingchamber(54)isdirectedthroughpumpoutletpiping(65)intotheelevatedreservoir(24).
Thetopedge(21)oftherearwall(20)inspraychamber(12)terminateslowerthanthefronttopedge(26)ofthefrontwall(14),andapaintspraygun(66)ispositionedsuchthatpaintspraymaybedirectedtowardthefrontwall(14)fromadistanceofapproximatelynineinches.Thecapacityoftherecirculatingwatersystemisabout14litersandtherecirculationrateisapproximately7.6litersperminute.
Inoperationwatercirculationisbeguntoprovideacurtainofwateroverflowingfromtopedge(26)towardfloor(22)andpassingadjacenttothefrontwall(14)ofspraychamber(12).Paintisthensprayedfromspraygun(66)towardthefrontwall(14)suchthatthespraybecomesentrainedinthewatercurtain.Generally,paintissprayedataratewithintherangeoffromabout2.5millilitersperminutetoabout5.0millilitersperminute,andthesprayingcontinuesuntilabout100millilitersofpainthasbeensprayed.
ThemodifiedtanninwasaddedtotherecirculatingpaintsprayboothwaterfirstandthepHelevatedtoabout8.5-10usingcaustic.Thesecondpolymericinthecomposition(i.e.diallyldimethylammoniumchloridepolymerorhydrophilic-lipophilicpolymer)wasthenaddedandthetreatmentallowedtomix.Thedetackifiedpaintsolids,afterpaintsprayingwascommenced,wereevaluatedbyrubbingthembetweenthumbandforefinger.Anexcellentratingwasinterpretedasrenderingcompletedetackification.
Theseresultscanbecomparedwiththefollowingrunsusingatreatmentofabout1400ppmmodifiedtanninandasanothercationicagent,about500ppmofapolymerderivedbyreactingdimethylaminewithepichlorohydrin(i.e.aDMA-EPI).
Inonerunabout1400ppmmodificationandabout500ppmdimethylamine-epichlorohydrinpolymerwereaddedtothewater.ThewaterwasadjustedtoapHof10usingcaustic.Afterwatercirculationwasbegun,anundilutedwhitehighsolidsbaseenamelpaintwassprayedtowardthewatercurtaininthespraychamberatapproximately3millilitersperminute.Afteratotalof100millilitersofpainthadbeensprayed,thefloatingsolidsinthestoragechamberwereexaminedandfoundtobecompletelydetackified.
Inasecondrunabout1400ppmmodifiedtanninandabout500ppmdimethylamine-epichlorohydrinpolymerwereaddedtothewater.ThewaterwasadjustedtoapHof10usingcaustic.Afterwatercirculationwasbegun,abluesapphiremetallichighsolidsenamelwhichhadbeenpredilutedwithanorganicsolventblendwassprayedtowardthewatercurtaininthespraychamber.Afteratotalof100millilitersofpainthadbeensprayed,thefloatingsolidsinthestoragechamberwereexaminedandfoundtobefairtopoor.Moreparticularly,thesolidsproducedatthisfairlyheavysprayrate(3.0ml/min)werestickyandsmeared.
Thus,whilethemodifiedtanninanddimethylamine-epichlorohydrincombinationwashighlyeffectiveatdetackifyingundilutedhighsolidsenamelpaints,whenpredilutedpaintsfromtwoautomobileplantswerescreened,theeffectivenessdecreasedmarkedly.Incontrast,themodifiedtanninandhydrophilic-lipophilicpolymertreatmentofthisinventionwasfoundtobeextremelyeffective,evenwhenthepaintsweredilutedwithorganicsolventblends.
TheExamplesillustratethatthecombinationsofthisinventionremaineffectivefordetackifyingpredilutedhighsolidsenamelpaints.Onlyinrun15,usingaredhighsolidsenamel,weretheresultslessthantotaldetackification,presumablyduetothesolventspresent.Theresultsinrun15are,nevertheless,consideredacceptablefromacommercialstandpoint.Iftheaminomethylatedtanninisusedalone,thefloatingpaintistackyandisthusunacceptableforcommercialapplication.Ifthehydrophilic-lipophilicpolymerisusedaloneatelevatedconcentrations(e.g.2,000ppm),thepaintisdetackifiedbutbecomescompletelydispersedthroughoutthewater.Consequently,additionalchemicaltreatmentwouldbenecessaryforcoagulation,flocculation,andsubsequentsludgedewatering.
Itisnotedthatthetannin-basedcomponentusedintheexampleswasnotconsideredatruesolution,butmoreparticularly,ahydrocolloidalsuspensioninwhichpartofthemoleculekeepsthetannininsolutionwhiletheethercyclicgroupishydrophobic.AsthewaterpHisraisedabovealevelofabout6.5,thesolubilityofthetannin-basedcomponentdecreasesandasmallflocisformed.Accordingly,afteradditionofthetannintothewaterofthepaintsprayapparatus,thepHispreferablybroughtwithintherangeofabout8to11toencourageformationofsuchafloc.
Withregardtothemodifiedtannincomponent,itisfurthernotedthatwhilethepreferredtannin-basedcomponenthasbeendescribedabove,itisunderstoodthatothermodifiedtanninsmaybepreparedbyaqueousreactionofatanninwithanaminocompoundandanaldehyde.Mimosaextractisshownabovetoproduceaparticularlysuitableflocformer,butbothquebrachoextractandwattleextractarepreferredfromthestandpointofavailabilityandprovensuitabilityasfloc-formingreactants.Othersuitabletanninscanbeobtainedfromvariouswoodandvegetationmaterialsfoundthroughouttheworld.Tanninsare,infact,alargegroupofwater-soluble,complexorganiccompounds.Almosteverytreeorshrubthatgrowscontainssometaninsintheleaves,twigs,barks,wood,orfruit.Examplesofbarksarewattle,mangrove,oak,eucalyptus,hemlock,pine,larch,andwillow.Examplesofwoodsarethequebracho,chestnut,oakandurunday.
Examplesoffruitsaremyrobalans,valonia,divi-divi,tara,andalgarrobilla.Examplesofleavesaresumacandgambierandexamplesofrootsarecanaigreandpalmetto.Thetanninextractsofmanyofthesematerials,andinparticularthecondensedpolyphenolictanninextracts,arethoughttobesufficientlyreactivetoprovideadequateflocculantqualities.
Thepreferredaldehydeforpreparingthemodifiedtanninusedinthisinventionisformaldehydewhichcanbeusedintheformof37%activeformaldehydesolution.Thisisalsocommerciallyavailableasformalinwhichisanaqueoussolutionof37%formaldehydewhichhasbeenstabilizedwithfrom6-15%methanol.Othercommercialgradesofformaldehydeanditspolymerscouldbeused.Suchcommercialgradesinclude44,45,and50%low-methanolformaldehyde,solutionsofformaldehydeinmethyl,propyl,n-butyl,andisobutylalcohol,paraformaldehydeandtrioxane.Whenusingsolidparaformaldehyde,caremustbetakenthatitalldissolves.
Otheraldehydecontainingorgeneratingreactantsareorganicchemicalcompoundswhichcontainatleastonealdehydegrouptherein,asarewell-knownandinclude,forexample,formaldehyde,acetaldehyde,propionaldehyde,glycolaldehyde,glyoxylicacidandthelikeorpolyaldehydes,i.e.organiccompoundshavingmorethanonealdehydegroupinthecompound,suchasglyoxal,paraformaldehydeandthelike.Othersuitablealdehydereactantsincludealdehydegeneratingagents,i.e.knownorganiccompoundscapableofforminganaldehydegroupinsite,suchasmelamine-formaldehydemonomericproductsandderivativessuchastriandhexamethylolmelamineandthetriandhexa(C1-C3alkoxymethyl)melamine.Suchmaterialscanbeformedbyknownconventionalmethods.Thealkylblockedderivativesarecommerciallyavailable,arestabletoself-polymerizationandare,therefore,preferred.
Particularlypreferredareaminocompoundsthatincludemonoethanolamine,ammoniaandwatersolubleinorganicammoniumsaltssuchasammoniumchloride.Otherpreferredmaterialsincludeprimaryaminessuchasmonoethanolamine,methylamineandethylamine.Secondaryaminesandotheraminecompoundsarealsoacceptable.Theprimaryaminesarepreferredforpreparingthemodifiedtanninsincetheyarethemorereactiveaminesthansecondaryortertiaryamines.
Thehydrophilic-lipophilicpolymercomponentappearstostabilizethesmallfloc,andcanevendecreaseitssize.Thiscomponentispreferablyaddedafterthemodifiedtannintoallowthesmallfloctoformbeforestabilization.Withoutlimitingtheinventiontoaparticulartheoryofoperation,theadditionofthehydrophilic-lipophilicpolymercomponentisconsideredimportantforprovidingaflocwithrelativelyhighsurfacearea,therebyimprovingdetackificationbyfacilitatingcontactbetweentheflocwhichisdispersedinwatercirculatinginthepaintsprayapparatus,andpaintwhichbecomesentrainedtherein.Thisstabilization,togetherwiththehigherchargedfloc,improvesthedispersionofthefloatingpaint.Flotationofthewastesolidsisalsofacilitatedsincethesettlingvelocityoftheflocisreducedbyadditionofthehydrophilic-lipophilicpolymercomponentofthisinvention.Thus,thedetackifiedpaintparticlesproducedinaccordancewiththisinventionarepreferablycollectedbyconventionalflotation.
Animportantbenefitofproducingdetackifiedpaintwhichfloatsisthatsomeoftheresultingsludges,suchasthoseobtainedwithcertainhighsolidsbasecoats,areeasilydewateredevenwithoutfurtherchemicaltreatment.Forexample,asludgecontainingmorethan94%solidswasmechanicallyobtainedusingalaboratoryplateandframepress.Nevertheless,followingdetackificationofthewater-entrainedpaintinaccordancewiththisinvention,andremovalofthedetackifiedparticlesfromthesystem,asbyflotation,furtherchemicaltreatmentmaybeprovidedtodewaterthesludge.Forexample,forhighsolidsenamelclearcoatpaintwaste,conventionalnonionicoranionicpolymericflocculantssuchasananionicpolyacrylamidepolymercanbeadvantageouslyusedtoenhancesludgedewaterability.
Organicsolventsusedforpredilutionofenamelpaintsmayinclude,forexample,methylethylketone,hexane,xylene,toluene,acetone,butanol,oracombinationoftheseandotherconventionalpaintsolvents.Thehydrophilic-lipophilicquaternaryammoniumpolymerasdefinedabovealsopossesssurfactantpropertieswhichareconsideredtocontributetotheiruniquecapabilitytodetackifyprediluted,readytospray,highsolidsenamelpaintssuchasthosecommonlyusedintheautomobileindustry.Moreover,thesehydrophilic-lipophilicpolymersmayevenbeconsideredsuperiortomanycommonlyusedsurfactantsbecausetheydonotgenerallycontributetofoaming.Withoutlimitingthisinventiontoaparticulartheoryofoperation,theeffectivenessofthiscomponentinthecombinationisconsidereddirectlyattributibletoitshydrophilic-lipophilicnature.ThelipophilicradicalR1-Qisbelievedtoformamicellewithsolventssuchasmethylethylketoneandtoluene.Detackificationisconsideredtobefacilitatedasaresultofsucheffectiveisolationofthesolventsfromthepaintmatrix.
Asindicatedabove,thesecondcomponentofthetreatmentcombinationofthisinventionmayalsocomprisediallyldialkylquaternaryammoniumpolymers.Thesepolymersaregenerallyhalides,especiallychlorides.ThepreferreddiallyldialkylquaternaryammoniumhalidepolymerispolydiallyldimethylammoniumchloridesuchasthediallyldimethylammoniumchloridepolymersdisclosedinU.S.Pat.No.3,288,770whichisherebyincorporatedhereinbyreference.Thesepolymersmaybeprepared,forexample,bypolymerizingdiallyldimethylammoniumchloridemonomer,usingbutylhydroperoxideasafreeradicalcatalyst.Typically,whendiallyldimethylquaternaryammoniumpolymersareusedinaccordancewiththisinvention,theyhaveamolecularweightrangebetweenabout100,000and300,000andachargedensitybetweenabout4.0and8.0.Oneproduct(chargedensityabout6.6;molecularweightabout200,000)isavailablefromDearbornDivision,W.R.Grace&Co.asAquafloc459,andwasusedintheExampleswhichfollow.
Thecombinationofthetannin-basedcomponentanddiallyldimethylquaternaryammoniumpolymertotreatwatercontainingpaintoversprayinaccordancewiththisinventionisconsideredparticularlyeffectivewhentheoversprayisanepoxyresinpaint.Practiceofthisembodimentoftheinventionwillbefurtherapparentfromthefollowingnon-limitingExample.EXAMPLEII
TheapparatusofFIG.1wasusedinthegeneralmannerdescribedinExampleI.Inafirstrunofthisexample,however,about1400ppmofthemodifiedtanninandabout100ppmofdiallyldimethylammoniumchloridepolymer(i.e.,aDADMAC)wereaddedtothewatercirculatinginthepaintsprayapparatus.ThewaterwasadjustedtoapHof10usingcaustic(50%).Afterwatercirculationwasbegun,aclearcoatenamelpaint,reducedforsprayingwithmethylethylketone,wassprayedtowardthewatercurtaininthespraychamberatapproximately3.3millilitersperminute.Afteratotalof100millilitersofreducedpainthadbeensprayed,thefloatingsolidsinthepaintsprayboothwereexamined.Itwasestimatedthatlessthan50%detackificationwasachieved.Theresultswereconsideredatleastaspoorastherunusingamineepihalohydrinwithpredilutedpaintdescribedabove.Accordingly,thediallyl-dimethylammoniumchloride/modifiedtannincombinationwasconsideredapoortreatmentfordilutedhighsolidsenamelpaintsystems.
Asecondrunwasmadeusingthesameprocedureasthefirstrun,exceptthataoff-white(base)enamelpaintwasusedatanapplicationrateof3.3ml/min.Atotalof100mlpaintwassprayed.Thishighsolidsenamelpaintwasnotpredilutedwithsolventspriortospraying.Thefloatingsolidsproducedinthisrunwereconsideredtobecompletelydetackified.Theseresultsweresuperiortothoseachievedusingthedimethylamine-epichlorohydrin/modifiedtannincombination.
Athirdrunwasmadeusingthesameprocedureasthefirstrun,exceptthatablackmodifiedepoxyresinwasused.Theapplicationratewasthesameasthatdescribedabove.Thefloatingsolidsproducedinthisrunwereconsideredtobecompletelydetackified.
TheresultsoftheseExampleIIrunsdemonstratethatthediallyldimethylammoniumchloride/modifiedtannincombinationinaccordancewiththisinventioncanbeusedadvantageouslytodetackifycertainpaintsystems.InthefirstrunofExampleII,thiscombinationwasrelativelypoorintreatingpredilutedhighsolidsenamelpaint.Thisisgenerallycomparablewithcertainothercationiccombinationstested,suchasDMA-EPImodifiedtannincombination,andfurtheraccentuatesthevalueofthehydrophilic-lipophilicpolymer/modifiedtannincombinationsofthisinvention.
InthesecondrunofExampleII,usingahighsolidsenamelpaintwhichwasnotprediluted,excellentresultswereachieved.Acombinationofthesametannin-basedproductwithaDMA-EPIpolymerwasalsousedonthispaintwithgooddetackificationresults.Sludgedewaterabilitywastestedforthesolidsproducedbyeachofthetwotreatmentcombinationsusingalaboratoryplateandframepress.ItwasfoundthatthecombinationusingDADMAC/modifiedtanninprovidedadewateredsludgeof82%solids,whereasthecombinationusingDMA-EPI/modifiedtanninprovidedasludgeof75%solids.Accordingly,thecombinationofthisinventionwasconsideredsuperiorintermsofsludgedewaterability.Itisnoted,however,thatincontrasttothesludgeproducedbythehydrophilic-lipophilicpolymer/modifiedtannincombinationsofthisinvention,thefiltermeshofthelaboratorypresswasblindedduringthedewatering.Itwasconcludedthatprecoatingoffieldfilterpresseswithmaterials,suchasdiatomaceousearth,wouldberequiredwhendewateringpaintsolidsdetackifiedbythiscombination.
ThethirdrunofExampleIIconfirmsthatthediallyldimethylammoniumchloride/modifiedtannincombinationofthisinventionisespeciallyeffectiveforepoxyresinpaints.
Epoxyresinpaintsareregardedinthearttoberelativelyeasytodetackifywhencomparedtodilutedhighsolidsenamelpaints.Thediallyldimethylquaternaryammoniumpolymerparticularlywhenhighlychargedappearstostabilizetheformationofapinflocbythetannin-basedcomponent,thereforedecreasingitssize.Withoutlimitingtheinventiontoaparticulartheoryofoperation,theadditionofthediallyldimethylquaternaryammoniumpolymerisconsideredimportantforprovidingaflocwithrelativelyhighsurfaceareaanddispersingit,therebyimprovingdetackificationbyfacilitatingthecontactbetweentheflocwhichisdispersedinwatercirculatinginthepaintsprayapparatus,andpaintwhichbecomesentrainedtherein.Theresultingdetackifiedpaintthenformsafloatingsludge.
Thecombinationsofthisinventionarepreferablyfreeofclayssoastoavoiddewateringproblemsassociatedwithclaymaterials.Thecombinationsofthisinventionarealsopreferablyfreeofamphotericmetals,particularlyzinc,whichprovidedisposalconcernswhenthedetackifiedsolidsareremovedfromthepaintsprayfacility.Indeed,thepreferredcombinationsofthisinventionareorganicinnature,andmayadvantageouslyconsistessentiallyofthetwocomponentsdiscussedabove.
Theinventiondescribedhereinisconsideredeffectivefordetackifyinghighsolidsenamelpaints(bothdilutedandnon-diluted),epoxyresinpaints,andalsopolyurethanepaints.Itisconsideredpreferablethatthepaintsprayboothwaterhaveanalkalinityofatleastabout150ppmasCaCO3whenhighsolidsenamelpaintsaredetackifiedinaccordancewiththisinvention.
Theexamplesdescribedhereinincludevariousembodimentsoftheinvention.Otherembodimentswillbeapparenttothoseskilledintheartfromaconsiderationofthespecificationorpracticeoftheinventiondisclosedherein.Itisunderstoodthatmodificationsandvariationsmaybepracticedwithoutdepartingfromthespiritandscopeofthenovelconceptsofthisinvention.Itisfurtherunderstoodthattheinventionisnotconfinedtotheparticularformulationsandexampleshereinillustrated,butitembracessuchmodifiedformsthereofascomewithinthescopeofthefollowingclaims.