沉淀白炭黑新工艺.docx
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沉淀白炭黑新工艺.docx
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沉淀白炭黑新工艺
Processfortheprecipitatedsilicanewprecipitatedsilicascontainingzincandtheiruseforthereinforcementofelastomers
Abstract
Theinventionrelatestoanewprocessforthepreparationofprecipitatedsilicawhichhasagooddispersibilityandverysatisfactoryreinforcingproperties.Italsorelatestonewprecipitatedsilicaswhichareintheformofpowder,ofsubstantiallysphericalbeadsorofgranules,thesesilicasbeingcharacterizedbythefactthattheyhaveaCTABspecificsurfaceofbetween90and250m.sup.2/g,aBETspecificsurfaceofbetween90and250m.sup.2/g,aDOPoiluptakelowerthan300ml/100g,azinccontentofbetween1and5%byweight,andbythefactthatthenumberNofstearicacidmoleculesconsumedpernm.sup.2ofsilicasurface,whenstearicacidisreactedwiththissilicainxylenefor2hoursat120.degree.C.,isatleast1.Theinventionalsorelatestotheuseofthesaidsilicasasreinforcingfillersforelastomers,especiallyforimprovingtheirrheologicalproperties.
Inventors:
Bomal;Yves(Paris,FR),Chevallier;Yvonick(Fontaines-Saint-Martin,FR),Prat;Evelyne(Pantin,FR)
Assignee:
RhodiaChimie(Courbevoie,FR)
Appl.No.:
09/248,921
Filed:
February11,1999
RelatedU.S.PatentDocuments
ApplicationNumberFilingDatePatentNumberIssueDate
737976
ForeignApplicationPriorityData
Mar29,1995[FR]9503676
CurrentU.S.Class:
106/492;106/482;423/335;423/339
CurrentInternationalClass:
C01B33/193(20060101);C08K3/00(20060101);C08K3/36(20060101);C01B33/00(20060101);C09C1/28(20060101);C09C1/30(20060101);C01B033/12()
FieldofSearch:
106/492,482423/335,338,339
ReferencesCited[ReferencedBy]
U.S.PatentDocuments
4040858August1977Wason
4161455July1979Wason
5403570April1995Chevallieretal.
5587416December1996Chevallieretal.
PrimaryExaminer:
Marcheschi;Michael
Attorney,AgentorFirm:
Seugnet;Jean-Louis
ParentCaseText
ThisapplicationisadivisionofU.S.applicationSer.No.08/737,976,filedonMar.03,1997,U.S.Pat.No.5,958,127,whichisanapplicationunder35U.S.C.Section371ofInternationalApplicationNo.PCT/FR96/00462,filedMar.28,1996.
Claims
Whatisclaimedis:
1.Aprecipitatedsilicahaving:
aCTABspecificsurfaceofbetween90and250m.sup.2/g,
aBETspecificsurfaceofbetween90and250m.sup.2/g,
aDOPoiluptakelowerthan300ml/100g,
azinccontentofbetween1and5%byweight,
saidsilicabeingintheformofsphericalbeadswithameansizeofatleast80.mu.m,apowderwithameansizeofatleast15.mu.m,orgranuleshavingalengthofatleast1mmalongtheaxisoftheirlargerdimension,and
whereinthenumberNofstearicacidmoleculesconsumedpernm.sup.2ofsilicasurface,whenstearicacidisreactedwiththesaidsilicainxylenefor2hoursat120.degree.C.,isatleast1.
2.Asilicaaccordingtoclaim1,whereinthezincisnotinacrystallineform.
3.Asilicaaccordingtoclaim1,whereinthezinccontentisatleast1.5.
4.Asilicaaccordingtoclaim1,having:
aCTABspecificsurfaceofbetween90and185m.sup.2/g,
amediandiameter(.Oslashed..sub.50),afterdisintegrationwithultrasound,smallerthan4.mu.m,and
anultrasonicdisintegrationfactor(F.sub.D)higherthan6ml.
5.Asilicaaccordingtoclaim1,having:
aCTABspecificsurfacehigherthan185m.sup.2/gandlowerthan220m.sup.2/g,and
amediandiameter(.Oslashed..sub.50),afterdisintegrationwithultrasound,smallerthan7.mu.m.
6.Asilicaaccordingtoclaim5,havingaDOPoiluptakeofbetween200and295ml/100g.
7.Asilicaaccordingtoclaim1,havingaporedistributionandaporevolumesuchthattheporevolumeconsistingoftheporeswhosediameterisbetween175and275.ANG.representsatleast50%oftheporevolumeconsistingoftheporesofdiameterssmallerthanorequalto400.ANG..
8.Asilicaaccordingtoclaim1,beingintheformofsphericalbeadswithameansizeofatleast80.mu.m.
9.Asilicaaccordingtoclaim8,whereinsaidmeansizeisofatleast150.mu.m.
10.Asilicaaccordingtoclaim1,beingintheformofpowderwithameansizeofatleast15.mu.m.
Description
Thepresentinventionrelatestoanewprocessforthepreparationofprecipitatedsilica,toprecipitatedsilicaswhichareinparticularintheformofpowder,ofsubstantiallysphericalbeadsorofgranules,andtotheirapplicationasareinforcingfillerforelastomers.
Itisknownthatprecipitatedsilicahasbeenemployedforalongtimeasawhitereinforcingfillerinelastomers.
However,likeanyreinforcingfiller,itisappropriatethatitshouldbecapableof,ontheonehand,beinghandledandaboveall,ontheotherhand,ofbeingeasilyincorporatedintothemixtures.
Itisknowningeneralthat,toobtaintheoptimumreinforcingpropertiesconferredbyafiller,itisappropriatethatthelattershouldbepresentintheelastomermatrixinafinalformwhichisbothasfinelydividedaspossibleanddistributedashomogeneouslyaspossible.However,suchconditionscanbeachievedonlyinsofaras,ontheonehand,thefillerhasaverygoodabilitytobeincorporatedintothematrixduringmixingwiththeelastomer(incorporabilityofthefiller)andtodisintegrateortodeagglomerateintotheformofaveryfinepowder(disintegrationofthefiller)andas,ontheotherhand,thepowderresultingfromtheabovementioneddisintegrationprocesscanitself,initsturn,beperfectlyandhomogeneouslydispersedintheelastomer(dispersionofthepowder).
Moreover,forreasonsofmutualaffinities,silicaparticleshaveanunfortunatetendency,intheelastomermatrix,toagglomeratewitheachother.Thesesilica/silicainteractionshaveadetrimentalconsequenceoflimitingthereinforcingpropertiestoalevelthatissubstantiallylowerthanthatwhichitwouldbetheoreticallypossibletoexpectifallthesilica/elastomerinteractionscapableofbeingcreatedduringthemixingoperationwereactuallyobtained(thistheoreticalnumberofsilica/elastomerinteractionsbeing,asiswellknown,directlyproportionaltotheexternalsurfaceofthesilicaemployed).
Furthermore,intherawstate,suchsilica/silicainteractionstendtoincreasethestiffnessandtheconsistencyofthemixtures,thusmakingthemmoredifficulttoprocess.
Theproblemarisesofhavingavailablefillerswhich,whilebeingcapableofbeingrelativelylargeinsize,improvetheTheologicalpropertiesofelastomersandadvantageouslyhaveagooddispersibilityinelastomers.
Theaimofthepresentinventionistoovercometheabovementioneddisadvantagesandtosolvetheabovementionedproblem.
Moreprecisely,itsaimisespeciallytoproposeanewprocessforthepreparationofprecipitatedsilicawhich,advantageously,hasagooddispersibility(anddisintegratability)andverysatisfactoryreinforcingproperties,inparticularwhich,whenemployedasareinforcingfillerforelastomers,impartsexcellentrheologicalpropertiestothelatterwhileprovidingthemwithgoodmechanicalproperties.
Theinventionalsorelatestoprecipitatedsilicaswhich,preferably,areintheformofpowder,ofsubstantiallysphericalbeadsor,optionally,ofgranules,andwhich,whilebeingofrelativelylargesize,haveverysatisfactoryreinforcingpropertiesand,inapreferredmanner,averygooddispersibility(anddisintegratability).
Itrelates,finally,totheuseofthesaidprecipitatedsilicasasreinforcingfillersforelastomers.
Inthedescriptionwhichfollows,theBETspecificsurfaceisdeterminedaccordingtotheBrunauer-Emmett-TellermethoddescribedintheJournaloftheAmericanChemicalSociety,Vol.60,page309,February1938andcorrespondingtoNFTstandard45007(November1987).
TheCTABspecificsurfaceistheoutersurfacedeterminedaccordingtoNFTstandard45007(November1987)(5.12).
TheDOPoiluptakeisdeterminedaccordingtoNFTstandard30-022(March1953)byusingdioctylphthalate.
Thepackingdensity(PD)ismeasuredaccordingtoNFTstandard030100.
ThepHismeasuredaccordingtoISOstandard787/9(pHofasuspensionataconcentrationof5%inwater).
Finally,itisspecifiedthatthegivenporevolumesaremeasuredbymercuryporosimetry,theporediametersbeingcalculatedfromtheWashburnrelationshipwithanangleofcontactthetaequalto130.degree.andasurfacetensiongammaequalto484dynes/cm(MICROMERITICS9300POROSIMETER.RTM.).
Thedispersibilityandthedisintegratabilityofthesilicaaccordingtotheinventioncanbequantifiedbymeansofaspecificdisintegrationtest.
Thedisintegrationtestiscarriedoutaccordingtothefollowingprocedure:
thecohesionoftheagglomeratesisassessedbyaparticlesizemeasurement(usinglaserscattering),performedonasilicasuspensionpreviouslydisintegratedbyultrasonictreatment;thedisintegratabilityofthesilicaisthusmeasured(ruptureofobjectsfrom0.1toafewtensofmicrons).ThedisintegrationunderultrasoundisperformedwiththeaidofaVIBRACELLBIOBLOCK(600W.RTM.)sonictransducerequippedwithaprobe19mmindiameter.TheparticlesizemeasurementisperformedbylaserscatteringonaSympatecparticlesizeanalyser.
2gramsofsilicaaremeasuredoutintoaspecimentube(height:
6cmanddiameter4cm)andaremadeupto50gramsbyaddingdemineralizedwater;anaqueoussuspensioncontaining4%ofsilicaisthusproduced,whichishomogenizedfor2minutesbymagneticstirring.Thedisintegrationunderultrasoundisnextperformedasfollows:
withtheprobeimmersedtoadepthofcm,thepowerisadjustedsoastoobtainaneedledeflectiononthepowerdialindicating20%(whichcorrespondstoanenergyof120watts/cm.sup.2
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