Polyvinyl chloride

compositionstructure

polyvinylchlorideisapolymermaterialthatusesachlorineatomtoreplaceahydrogenatominpolyethylene.Itisanamorphouspolymerwithasmallamountofcrystallinestructure.Thestructureofthismaterialisasfollows:-(CH₂-CHCl)_n-.PVCisalinearpolymerinwhichmostVCMmonomersareconnectedinahead-to-tailstructure.Thecarbonatomsarearrangedinazigzagpattern,andallatomsareconnectedbysigmabonds.Allcarbonatomsaresp³hybrids.

ThereisashortsyndiotacticstructureonthePVCmolecularchain.Asthepolymerizationtemperaturedecreases,thesyndiotacticityincreases.Themacromolecularstructureofpolyvinylchloridehasthedisadvantagesofheadstructure,branchedchain,doublebond,allylchloride,tertiarychlorineandotherunstablestructures,whichmakeheat-resistantdeformationandpooragingresistance.Afterpretendingtobecross-linked,suchshortcomingscanbeeliminated.

Crosslinkingisdividedintoradiationcrosslinkingandchemicalcrosslinking.

1.Radiationcrosslinking.High-energyraysareused,generallyraysproducedbyacobalt60radiationsourceorelectronraysproducedbyelectronacceleration,andthelatterismainlyused.Addcrosslinkingaids(twoormorecarbon-carbondoublebondmonomers)forcrosslinking.However,theoperationisdifficultandrequireshighequipment.

2.Chemicalcross-linking.Triazoledimercaptoaminesalt(FSH)isusedforcross-linking.Thecross-linkingmechanismisthatamineandsulfhydrylcombinetoattackthecarbon-chlorinepolarbondtoperformsubstitutionreaction.Aftercross-linking,theperformanceoftheproduct,suchasUVresistance,solventresistance,temperatureresistance,impacttoughening,etc.,willbecomprehensivelyimproved.

Historicalevolution

Asearlyas1835,polyvinylchloridewasdiscoveredbyV·LeñointheUnitedStates.Whenitisirradiatedwithsunlight,itproducesawhitesolid,namelypolyvinylchloride.

PVCwasdiscoveredtwiceinthe19thcentury,oncebyHenriVictorRegnaultin1835andtheotherbyEugenBaumannin1872.Onbothoccasions,thepolymerappearedinabeakerofvinylchlorideplacedunderthesunlightasawhitesolid.Atthebeginningofthe20thcentury,RussianchemistIvanOstromislenskyandGermanGriesheim-ElektronchemistFritzKlattesimultaneouslytriedtousePVCforcommercialpurposes,butthedifficultywashowtoprocessthishardandsometimesbrittlepolymer.

In1912,theGermanFritzKlattesynthesizedPVCandappliedforapatentinGermany,butfailedtodevelopasuitableproductbeforethepatentexpired.

In1926,WaldoSemonofB.F.GoodrichCompanyintheUnitedStatessynthesizedPVCandappliedforapatentintheUnitedStates.WaldoSemonandB.F.GoodrichCompanydevelopedamethodofplasticizingPVCbyaddingvariousadditivesin1926,makingitamoreflexibleandeasier-to-processmaterial,andsoonitwaswidelyusedincommercialapplications.

In1914,itwasdiscoveredthatorganicperoxidescouldacceleratethepolymerizationofvinylchloride.In1931,theGermanmethodusedemulsionpolymerizationtorealizetheindustrialproductionofpolyvinylchloride.In1933,W.L.SimonproposedtousehighboilingpointsolventandtricresylphosphatetoheatandmixwithPVC,whichcanbeprocessedintosoftpolyvinylchlorideproducts,whichmadearealbreakthroughinthepracticalityofPVC.BenemenChemicalIndustries,UnitedKingdom,UnionCarbideCorporation,andGoodrichChemicalCompanydevelopedthesuspensionpolymerizationofvinylchlorideandtheprocessingandapplicationofPVCalmostsimultaneouslyin1936.Inordertosimplifytheproductionprocessandreduceenergyconsumption,theFrenchSaint-Gobaincompanydevelopedthebulkpolymerizationmethodin1956.In1983,theworld'stotalconsumptionwasabout11.1Mt,andthetotalproductioncapacitywasabout17.6Mt;itwasthesecondlargestplasticvarietyafterpolyethyleneproduction,accountingforabout15%ofthetotalplasticproduction.China'sself-designedPVCproductionequipmentwasputintotrialproductioninLiaoningJinxiChemicalPlantin1956.The3ktunitwasofficiallyindustrializedin1958,andtheoutputin1984was530.9kt.

PVCwasindustrializedintheearly1930s.Sincethe1930s,foralongperiodoftime,theoutputofPVChasbeenrankedfirstintheworld'splasticconsumption.Inthelate1960s,polyethylenereplacedpolyvinylchloride.AlthoughPVCplasticsrankssecond,buttheoutputstillaccountsformorethanaquarterofthetotaloutputofplastics.

Beforethe1960s,theproductionofmonomervinylchloridewasbasicallybasedoncalciumcarbideacetylene.Theproductionofcalciumcarbiderequiredalotofelectricityandcoke,andthecostwashigh.Aftertheindustrializationofethyleneoxychlorinationtoproducevinylchlorideintheearly1960s,countriesturnedtocheaperpetroleumasrawmaterials.Inaddition,becausealargepartoftherawmaterialofpolyvinylchloride(about57%byweight)istheby-productofthesodaindustry,itisnotonlyarichsourceofrawmaterials,butalsooneofthemostimportantproductsforthedevelopmentofthechlor-alkaliindustryandthebalanceofchlorine.Therefore,althoughtheproportionofPVCinplasticshasdeclined,itstillmaintainsarelativelyhighgrowthrate.

PVCplasticproductsarewidelyused,butinthemid-1970s,peoplerealizedthattheresidualmonomervinylchloride(VCM)inPVCresinandproductsisaseriouscarcinogen.Undoubtedly,itwillaffectthedevelopmentofPVCtoacertainextent.However,peoplehavesuccessfullyreducedtheresidualVCMthroughvehiclesandothermeans,sothatthecontentofVCMinthepolyvinylchlorideresinislessthan10ppm,whichmeetstherequirementsofsanitaryresinandexpandstheapplicationrangeofpolyvinylchloride.ItcanevenmaketheVCMcontentintheresinlessthan5ppm,andtheresidualVCMafterprocessingisextremelysmall.Basicallyharmlesstothehumanbody,itcanbeusedasfoodmedicinepackagingandchildren'stoys.

Mainclassification

Accordingtothedifferentapplicationscope,PVCcanbedividedinto:general-purposePVCresin,highpolymerizationdegreePVCresin,andcross-linkedPVCresin.Thegeneral-purposePVCresinisformedbythepolymerizationofvinylchloridemonomerundertheactionofaninitiator;thehighdegreeofpolymerizationPVCresinreferstotheresinpolymerizedbyaddingachainextendertothevinylchloridemonomerpolymerizationsystem;thecross-linkedPVCresinisAresinpolymerizedbyaddingacrosslinkingagentcontainingdieneandpolyenetothevinylchloridemonomerpolymerizationsystem.

Accordingtothemethodofobtainingvinylchloridemonomer,itcanbedividedintocalciumcarbidemethod,ethylenemethodandimported(EDC,VCM)monomermethod(theethylenemethodandimportedmonomermethodarecommonlyreferredtoasethyleneLaw).

Accordingtothepolymerizationmethod,polyvinylchloridecanbedividedintofourcategories:suspensionpolyvinylchloride,emulsionpolyvinylchloride,bulkpolyvinylchloride,andsolutionpolyvinylchloride.Suspensionprocesspolyvinylchlorideisthelargestvarietyinoutput,accountingforabout80%ofthetotaloutputofPVC.SuspensionmethodPVCisdividedintosixmodelsaccordingtoabsoluteviscosity:XS-1,XS-2……XS-6;XJ-1,XJ-2……,XJ-6.Themeaningofeachletterinthemodel:X-suspensionmethod;S-loosetype;J-compacttype.

Accordingtotheplasticizercontent,PVCplasticolefinplasticsareoftendividedinto:non-plasticizedPVC,plasticizercontentis0;rigidPVC,plasticizercontentislessthan10%;semi-rigidForhigh-qualityPVC,theplasticizercontentis10-30%;forsoftPVC,theplasticizercontentis30-70%;forpolyvinylchloridepasteplastic,theplasticizercontentismorethan80%.

Preparationmethod

Polyvinylchloridecanbemadebysubstitutionreactionofethylene,chlorineandcatalyst.Duetoitsfireandheatresistance,polyvinylchlorideiswidelyusedinvariousproductsinallwalksoflife:wiresheaths,fiberopticsheaths,shoes,handbags,bags,accessories,signsandbillboards,architecturaldecorationsupplies,furniture,ornaments,Rollers,hoses,toys,doorcurtains,rollingdoors,auxiliarymedicalsupplies,gloves,somefoodwraps,somefashions,etc.

Polymerizationmethod

PVCispreparedbyfreeradicaladditionpolymerizationmethod.Thepolymerizationmethodismainlydividedintosuspensionpolymerizationmethod,emulsionpolymerizationmethodandbulkpolymerizationmethod.Suspensionpolymerizationisthemainmethod,whichaccountsforabout80%ofthetotaloutputofPVC.Purewater,liquefiedVCMmonomer,anddispersantareaddedtothereactor,andtheninitiatorandotheradditivesareadded.Afterthetemperatureisraisedtoacertaintemperature,theVCMmonomerundergoesfreeradicalpolymerizationtoformPVCparticles.Continuousstirringmakestheparticlesizeuniformandsuspendstheresultingparticlesinwater.Inaddition,thereisalsoamicro-suspensionmethodtoproducePVCpasteresin,whichhasgoodproductpropertiesandpaste-formingproperties.

①Suspensionpolymerizationmethod:themonomerissuspendedanddispersedinthewaterphaseintheformofdroplets,theselectedoil-solubleinitiatorisdissolvedinthemonomer,andthepolymerizationreactionproceedsinthesedroplets.Theheatofreactionisabsorbedbywaterintime.Inordertoensurethatthesedropletsaredispersedinwaterasbeads,suspensionstabilizerssuchasgelatin,polyvinylalcohol,methylcellulose,andhydroxyethylcelluloseneedtobeadded.Initiatorsmostlyuseorganicperoxidesandazocompounds,suchasdiisopropylperoxydicarbonate,dicyclohexylperoxydicarbonate,diethylhexylperoxydicarbonate,andazobisisoheptonitrile,azoNitrogentwoisobutyronitrileandsoon.Thepolymerizationiscarriedoutinapolymerizationvesselequippedwithastirrer.Afterpolymerization,thematerialflowsintothemonomerrecoverytankorstrippertorecoverthemonomer.Thenitflowsintothemixingkettle,washedwithwater,dewateredbycentrifugation,anddriedtoobtainthefinishedresinproduct.Vinylchloridemonomershouldberemovedfromtheresinasmuchaspossible.ForPVCusedforfoodpackaging,thefreemonomercontentshouldbecontrolledbelow1ppm.Inordertoensurethattheresinwiththespecifiedmolecularweightandmolecularweightdistributionrangeandpreventexplosionduringpolymerization,thetemperatureandpressureofthepolymerizationprocessmustbecontrolled.Theparticlesizeandparticlesizedistributionoftheresinarecontrolledbythestirringspeedandtheselectionanddosageofthesuspensionstabilizer.Thequalityofresinischaracterizedbyparticlesizeandparticlesizedistribution,molecularweightandmolecularweightdistribution,apparentdensity,porosity,fisheye,thermalstability,color,impuritycontentandpowderfreeflowability.Thepolymerizationreactoristhemainequipment.Itismadeofsteelreactorliningstainlesssteelorenamel.Itisequippedwithastirrerandaheattransferjackettocontrolthetemperature,oraninternalcoolingpipe,arefluxcondenser,etc.Inordertoreducetheproductioncost,thevolumeofthereactorhasgraduallydevelopedfromafewcubicmeterstoadozencubicmeterstoalargescale,andthemaximumhasreached200cubicmeters(kettlereactor).Thepolymerizershouldbedescaledafterrepeateduse.PVCmadewithpolyvinylalcoholandcelluloseethersassuspensionstabilizersisgenerallylooser,hasmanypores,andhasalargesurfacearea,whichiseasytoabsorbplasticizersandplasticize.

②Emulsionpolymerization:oneoftheearliestindustrialproductionmethodsofPVC.Inemulsionpolymerization,inadditiontowaterandvinylchloridemonomers,surfactantssuchassodiumalkylsulfonatearealsoaddedasemulsifierstodispersethemonomersinthewaterphasetoformanemulsion,usingwater-solublepotassiumpersulfateorAmmoniumpersulfateistheinitiator,and"oxidation-reduction"initiationsystemcanalsobeused,andthepolymerizationprocessandsuspensionmethodaredifferent.Therearealsoaddedpolyvinylalcoholasanemulsionstabilizer,dodecylmercaptanasaregulator,andsodiumbicarbonateasabuffer.Therearethreepolymerizationmethods:batchmethod,semi-continuousmethodandcontinuousmethod.Thepolymerizedproductislatex-like,theparticlesizeoftheemulsionis0.05-2μm,anditcanbedirectlyappliedorspray-driedintoapowderedresin.Theemulsionpolymerizationmethodhasashortpolymerizationperiodandiseasiertocontrol.Theobtainedresinhasahighmolecularweightandarelativelyuniformpolymerizationdegree.Itissuitableformakingpolyvinylchloridepaste,makingartificialleatherorimpregnatingproducts.Theformulationofemulsionpolymerizationiscomplex,andtheproducthasahighimpuritycontent.

③Bulkpolymerizationmethod:Thepolymerizationdeviceisrelativelyspecial,mainlycomposedofaverticalpre-polymerizationtankandahorizontalpolymerizationtankwithaframestirrer.Theaggregationiscarriedoutintwostages.Monomersandinitiatorsarepre-polymerizedinthepre-polymerizationkettlefor1hourtogenerateseedparticles.Atthistime,theconversionratereaches8%to10%,andthenflowsintothesecond-stagepolymerizationkettletoaddprepolymers,etc.Theamountofmonomercontinuestopolymerize.Aftertheconversionratereaches85%to90%,theresidualmonomersaredischarged,andthencrushedandsievedtoobtainthefinishedproduct.Theparticlesizeandshapeoftheresinarecontrolledbythestirringspeed,andthereactionheatistakenoutbythemonomerrefluxandcondensation.Theproductionprocessofthismethodissimple,theproductqualityisgood,andtheproductioncostislow.

PVCmodificationmethod

PVCresinisapolarnon-crystallinepolymer,density:1.38g/cm³,glasstransitiontemperature:87°C,soithaspoorthermalstabilityandisnoteasytoprocess.Itcannotbeuseddirectly,itmustbemodifiedandcompounded,andrelatedadditivesandfillerscanbeaddedbeforeitcanbeused.However,duetothedifferenttypesandfractionsofrelatedadditivesandfillersadded,thisdeterminesthatthepropertiesandrequirementsofthepreparedPVCmaterialsaredifferent.WeusuallycallitPVCformula,strictlyspeaking,itisPVCmodifiedformula,andPVCcanonlybeusedaftermodification.Thiscategoryisoftenclassifiedaspolymermodifiedmaterials.Themodificationofpolymermaterialsmainlyfocusesonresearchonthehighperformanceofgeneral-purposeplastics,theconversionofsingle-componentmaterialstomulti-componentcompositematerials(alloys,blends,andcomposites),functionalizationofmaterials,andoptimizationofperformanceandprice.Modificationmethodsaremainlychemicalmodification,fillingmodification,reinforcementmodification,blendingmodificationandnano-compositemodification.Thebasicprincipleofmodificationistogivematerialsfunctionsorimprovecertainpropertiesthroughadditives.Therefore,thelevelofPVCformulationtechnologydeterminestheleveloftechnologyandproductioncapacityofafactory.

PVCgenerallyneedstobemodifiedandpelletizedfirst.Afterbeingpreparedintopelletswithascrewextruderunit,itwillbemorefullyplasticizedandeasiertoprocess,especiallyforproductswhoseprocessisinjectionmolding.Screwextruderisoneofthemostimportantequipmentforplasticmoldingandprocessing.Itusesexternalpowertransmissionandheattransferfromexternalheatingelementstocarryoutplasticsolidtransportation,compaction,melting,shearing,mixing,andextrusionmolding.Thescrewextruderoccupiesanimportantpositionwhetherasaplasticizinggranulatingmachineoraformingprocessingmachine.Strictlyspeaking,PVCproductswithspecialrequirementsandPVCmodifiedformulasaretailor-madeaccordingtocustomerrequirements.ThereisalsoacopolymerizationderivativeinthePVCproductionprocess.Suchmodifiedvarietiesincludevinylchloridecopolymers,polyvinylchlorideblends,andchlorinatedpolyvinylchloride.

Colorability

Polyvinylchloridehaspoorthermalstabilityandlightresistance.Hydrogenchloridebeginstodecomposeat150°C,andadversereactionsoccurwiththecontentofplasticizer.Inaddition,theeffectofpigmentsonPVCisreflectedinwhetherthepigmentsreactwithPVCandothercomponentsthatmakeupPVCproducts,aswellasthemigrationresistanceandheatresistanceofthepigmentitself.Certaincomponentsinthecolorantmaypromotethedegradationoftheresin.Forexample,ironionsandzincionsarecatalystsforthedegradationreactionofPVCresin.Therefore,theuseofironoxide(red,yellow,brownandblack)pigmentsorwhitepigmentssuchaszincoxide,zincsulfideandlithoponewillreducethethermalstabilityofPVCresins.CertaincolorantsmayinteractwiththedegradationproductsofPVCresin.Forexample,ultramarinepigmentshavepooracidresistance,sointheprocessofPVCcoloring,theywillinteractwiththehydrogenchloridegeneratedbythedecompositionofPVCandlosetheirpropercolor.Therefore,asfarasPVCcoloringisconcerned,takingintoaccountthecharacteristicsoftheresinandrelatedadditivesused,combinedwiththecharacteristicsofthepigment.Thefollowingissuesshouldbepaidattentiontowhenchoosingcolorants.

1.CertainmetalionsinthepigmentwillpromotethethermaloxygendecompositionofPVCresin.

Themeasuringmethodisthehuechangeofpigmentedpolyethylenewhenheatedto180℃.ThepigmentcontainsmetalionstoacceleratethedecompositionofPVC,resultinginahuechange.Atthesametime,itshouldbenotedthatthesameadditionoflakeredcanmakePVCproducedifferentcolordifferences.Ifcalciumiscontained,thecolordifferenceissmall;ifmanganeseiscontained,thecolordifferenceislarge.ThisisduetothepromotionofdehydrochlorinationofPVCbymetalssuchasmanganese.

Sulfidecolorants(suchascadmiumred,etc.)areusedtocolorPVC,andhydrogensulfidemaybeliberatedduetotheseparationofthecolorant.Suchcolorantsshouldnotbemixedwithleadstabilizerstoavoidtheformationofblackleadsulfide.

2.TheeffectofpigmentsontheelectricalinsulationofPVC

Asthecablematerial,PVCisthesameaspolyethylene,andtheelectricalpropertiesaftercoloringshouldbeconsidered.Inparticular,polyvinylchlorideitselfislessinsulatingthanpolyethylene,sotheinfluenceofpigmentsisevengreater.ItshowsthatchoosinginorganicpigmentstocolorPVCisbetterforitselectricalinsulationthanorganicpigments(exceptforfurnaceblackandanatasetitaniumdioxide).

Migration

MigrationonlyoccursinplasticizedPVCproducts,andwhenusingdyesororganicpigments.Theso-calledmigrationisthatthepartiallysolubledyesororganicpigmentsinthesurroundingsolventpenetrateintothesurfaceofthePVCproductthroughtheplasticizer,andthedissolveddye(pigment)particlesarealsobroughttothesurfaceoftheproduct,whichleadstodissolution.Bleeding,solventbleedingorblooming.

Anotherproblemis"scaling".Itmeansthatthecolorantisreleasedfromthesystemduetopoorcompatibilityorincompatibilityofthecoloringmaterialduringcoloringprocessing,andisdepositedonthesurfaceoftheprocessingequipment(suchastheinnerwalloftheextruderbarrel,theinnerwallofthediehole).

Weatherresistance

referstotheabilityofthepigmenttowithstandvariousweathers.Theseincludevisibleandultravioletlight,moisture,temperature,atmosphericchlorination,andchemicalsencounteredduringproductuse.Themostimportantweatherresistanceincludescolorfastness,chalkingresistanceanddurabilityofphysicalproperties.However,organicpigmentsaredifferentduetotheirdifferentstructures.Inaddition,intheformulationscontainingwhitepigments,theweatherresistanceofthepigmentswillbemoreseverelyaffected.

Thefading,darkeningorhuechangeofthepigmentisgenerallycausedbythereactiongeneofthepigment.Thesereactivegenescaninteractwithmoistureorchemicalsintheatmosphere-acidsandalkalis.Forexample,cadmiumyellowwillfadeundertheactionofmoistureandsunlight.Litholredhasgoodlightresistanceandissuitableformostindoorapplications.However,itwillfadeseverelywhenusedoutdoorswithacidandalkalicomponents.

ThemeasuringmethodofdehydrochlorinationisaccordingtoJIS-K-6723,andthemeasuringtemperatureis180℃.Basedonthetimeofdechlorinationoftheuncoloredpolyvinylchloridecompound,theextensionorretardationtimeiscalculatedat5%and10%intervals.Anegativevalueindicatesaccelerateddecomposition.

Stability

Thesofteningpointofpolyvinylchlorideresinislow,about75-80℃,andtheembrittlementtemperatureislowerthan-50~-60℃.Mostproductsarenotsuitableforlong-termuse.Above55℃,itcanreach90℃withspecialformula.Ifthepolyvinylchlorideresinispurelyalinearstructurewithahead-to-sexinterface,therearenobranchesandunsaturatedbondsinside,althoughtheC-Clbondenergyisrelativelysmall,thestabilityofthepolyvinylchlorideresinshouldberelativelyhigh..However,evenwithhigh-puritypolyvinylchlorideresin,hydrogenchloridegaswillbegintoescapewhenitisabove100°Corexposedtoultravioletradiationforalongtime.Itshowsthattherearesharpgroupsorunstablestructuresinitsmolecularstructure.Thelongerthetime,themoredegradation,andthehigherthetemperature,thefasterthedegradationrate,andthefasterthedegradationrateinthepresenceofoxygenorair.

Electricalproperties

Polyvinylchlorideisapolarpolymerandhasagreateraffinityforwaterandotherconductivematerials,soitsresistanceislowerthanthatofnon-polarpolyolefins,butitstillHighervolumecathodeandbreakdownvoltage.Thepolargroupsofpolyvinylchloridearedirectlyattachedtothemainchain.Belowtheglasstransitiontemperature,thedipolarsegmentisrestrictedbythemainchainatomsofthefrozenstructureandcannotbemoved,soitdoesnotproducedipolarizationandcanbeusedatroomtemperature.Ofhigh-frequencyinsulationmaterials.Whenusedaswireinsulation,theelectricalinsulationofsuspensionresinis10-100timeshigherthanthatoffloatingresin.Thepresenceofchlorideionsproducedbydegradationwillreduceelectricalinsulation.

ThedevelopmentstatusofPVC

PVCmaterialswithspecialrequirementsgenerallyneedtobeimportedfromabroad.ThemorefamousforeigncompaniesincludeUnionCarbideCorporationandBorealis.WiththecontinuousR&Dandtechnologyaccumulationoflargescientificresearchinstitutesandproductionunits,theformulationdesignandmanufacturingofdomesticPVCmodifiedmaterialshavereachedtheinternationaladvancedlevel,whichhascompletelyreplacedforeignimportedmaterials,andmanyproductshavebeenexportedabroad.

Developmentprospects

1DevelopmenttrendofPVCresinindustry

China'sPVCresinconsumptionismainlyconcentratedinSouthandEastChinaInthetworegions,theconsumptionofGuangdong,Zhejiang,Fujian,ShandongandJiangsuaccountsforabout70.0%ofthetotalconsumptionofthecountry.Amongthem,GuangdongandFujianprovinceshavethelargestmarketdemand,buttheirproductioncapacityisinsufficient.ImportedPVCresinTheproportionisrelativelyhigh;thePVCresinprocessingindustryinJiangsu,ShandongandZhejiangisrelativelydeveloped,andtheconsumptionofthethreeprovincesaccountsforabout34.0%ofthetotaldomesticconsumption;theproductionandsalesofNorthChinaarebasicallybalanced.Withthestrengtheningofdevelopmenteffortsinthecentralandwesternregionsandtheconstructionoflarge-scaleinfrastructure,theconsumptionofPVCresininthecentralandwesternregionswillgraduallyincrease.

2Demandforecast

Thepolyvinylchlorideresinindustryisabasicandenergy-intensiveindustry,whichisgreatlyaffectedbydemandandenergyprices.Basicchemicalrawmaterialsarethereforeverycloselyrelatedtoeconomicdevelopment.Judgingfromthesituationin2012,thedomesticPVCresinproductioncapacityisstilldeclining,whiledownstreamdemandgrowthisrelativelyslow,coupledwithblockedexportsandincreasedimports,theoveralloperatingrateofdomesticPVCresincompaniesisnothigh,andthenumberofidlecapacityisrelativelyhigh.Themarketpricehasalwaysremainedlowandmedium,andthepricefluctuationrangehasbeenreduced.Inaddition,thelistingofPVCresinfutureshasincreasedtheuncertaintyofthepricefluctuationofthePVCresinmarkettoacertainextent.mycountry'sPVCresinindustrywillstillbeinarelativelydifficultperiodofintegration,andtherewillbemanyfactorsthatwillaffectthefuturedevelopmentofmycountry'sPVCresin.

3Exportissues

①Costbarriers

PVCisabasicchemicalrawmaterialwithsmallproductdifferentiation,anditiscompletelycompetitiveinChinaUnderthecurrentmarketstructure,costisthemostimportantfactoraffectingthecompetitivenessofenterprises.Duetoindustrycharacteristics,rawmaterialsandenergyaccountforarelativelyhighproportionofproductcosts.Thecostofthepetroleumethylenemethodismainlyaffectedbythepriceofoil;theproductioncostofthecalciumcarbidemethodismainlyaffectedbythecostofcalciumcarbide.Generallyspeaking,thecostofcalciumcarbideaccountsforabout70%ofthecostofPVC,andthecostofelectricityaccountsforabout60%ofthecostofcalciumcarbide.Westernmycountryhasabundantpowerresourcesandrelativelylowelectricityprices.Comparedwitheasterncalciumcarbidemanufacturingenterprises,westerncalciumcarbidemanufacturingenterpriseshavecertainadvantagesintermsofcost.Andenterpriseswithresourceendowmentandsupportingcalciumcarbideproductionwillbuildamoresolidcostbarrier.

②Industrialpolicybarriers

Inordertopromotetheupgradingoftheindustrialstructureofthechlor-alkaliindustryandstandardizethedevelopmentoftheindustry,follow"Technicalprogress",theNationalDevelopmentandReformCommissionformulatedandissuedthe"Chlor-Alkali(CausticSoda,PVC)IndustryAccessConditions",andithasbeenimplementedsinceDecember1,2007:Intermsofindustriallayout,newchlor-alkaliproductionisrequiredEnterprisesshouldbeclosetoresourcesandenergysources.Inprinciple,nonewcalciumcarbide-basedPVCprojectsandsupportingcausticsodaprojectswillbebuiltintheeasternregionexceptfortherelocatedenterprises;technologicalaspectsrequirethatnewandexpandedcalciumcarbide-basedPVCprojectsmustbeconstructedatthesametimeCalciumcarbideslagisacomprehensiveutilizationdeviceforcementandothercalciumcarbideslag;theaccessconditionsalsosetstandardsfornewprojectsintermsofenergyconsumptionindicatorsandenvironmentalprotection.Theadjustmentofindustrialpolicieshasgreatlyraisedthethresholdofcapital,technology,talents,andresourcesforthechlor-alkaliindustry.

③Scalebarriers

ThescaleofinvestmentrequiredtoproducePVCisrelativelylarge,thefixedcostsarerelativelyhigh,andthescalebenefitsarerelativelyobvious.Large-scaleenterprisesareinamoreadvantageouspositioninnegotiationswithsuppliers,whichisconducivetoreducingrawmaterialcosts.Companieswithlargeproductionandsaleshaveacorrespondinglyhighermarketshare,havegreatermarketinfluence,andarerelativelyeasiertoacquirecustomers.OnceaPVCmanufacturerreachesalargescaleofproductionandsales,themarginalcostwillgraduallydecreaseandtheabilitytoresistriskswillbeenhanced.

④Financialbarriers

Atthesametime,withthecountry’sincreasinglystrictsafetyandenvironmentalprotectionsupervision,theconstructionofchlor-alkaliproductionequipmentmustbeequippedwithcorrespondinglarge-scaleenvironmentalprotectionequipment(suchascalciumcarbidelinemustbeequippedwithcalciumcarbideslagCementequipment,etc.),thecapitalinvestmentisrelativelylarge,andmostsmallandmedium-sizedenterprisesgenerallycannotaffordit.

Therefore,manufacturersinvestinginthisindustrymusthavestrongfinancialstrengthandtherearecertainfinancialbarriers.

ThedemandforPVCintheIndiandomesticmarkethasincreasedyearbyyear,frommorethan1.7milliontonsin2009tomorethan2.2milliontonsin2012;however,therewereonlyfivePVCmanufacturersinIndiawithadomesticproductioncapacityof1.25milliontons./year.IndiaFinolexIndustriesisthelargestproducerofPVCpipesinIndia.Duetotheimbalancebetweensupplyanddemand,thereisalargegap,sotheaverageannualPVCimportvolumeinIndiareaches950,000tons.Atthesametime,India'svinylrawmaterialgapisalsoincreasingyearbyyear.In2011,itwas722,000tons,in2012itwas976,000tons,andin2013itwillreach1.12milliontons.Accordingtostatistics,fromApriltoSeptember2012,India'sPVCimportsweremainlyfromSouthKorea,Taiwan,Germany,theUnitedStates,Mexicoandothercountriesandregions.Amongthem,PVCimportsfromSouthKoreaandTaiwanbothexceeded200,000tons.

RajeshDeshpandesaidthatIndia’sPVCdownstreamproductsaremainlyPVCpipesandaccessories,accountingfor43%ofthecountry’stotalPVCdownstreamproducts.Inthefirstsixmonthsofthe2012-2013fiscalyear,downstreamdemandincreasedby20%,andimportsincreasedby50%.Accordingtothedevelopmentspeed,byMarch2013,thedomesticmarketdemandinIndiawillreach2.2milliontons,andthedevelopmentspeedofPVCpipeswillalsoreachdoubledigits.

AsthedownstreamconsumermarketforPVCisexpandingyearbyyear,India'sPVCindustryhasagreateropportunityfordevelopment.AccordingtoRajeshDeshpande'sforecast,thegrowthofthedownstreamconsumermarketforPVCproductsinIndiastemsfrommanyaspects.Thegovernment'sinvestmentininfrastructureconstructionhasincreasedyearbyyear.Statisticsshowthatduringthe"TwelfthFive-YearPlan"period,theIndiangovernment'sinvestmentininfrastructureconstructionwillreach890billionUSdollars;theruralinfrastructureconstructionanddevelopmentfundwillincreaseto3.5billionUSdollars;theruraldrinkingwaterandenvironmentalsanitationinvestmentbudgetwillreach2.5billionUSdollars;US$53millionwillbeinvestedintheconstructionofirrigationsystems;intheDelhi-MumbaiIndustrialCorridor,US$90billionwillbeinvestedintheconstructionoflarge-scaleinfrastructure,ofwhichtheJapanesegovernmentsponsoredUS$4.5billion.

Despitethelargegapbetweensupplyanddemand,theIndianPVCindustryfacescertainchallengesduetothegreatercompetitiveadvantagesofimportedproducts.RajeshDeshpandesaidfranklythattherearestillcertainproblemsinthedevelopmentofthePVCindustryinIndia:forexample,usershavenotyetseentheadvantagesofplasticpipesovertraditionalpipes;environmentalistsandnon-governmentalorganizationshaveexplainedtheharmsofplasticpipesfromtheperspectiveofenvironmentalhazards;relevantproductioncompanieshavenotPayattentiontothequalitycontroloftheirownproducts.Therefore,iftheIndianPVCindustrywantstoachievesustainabledevelopment,itmustcontinuetodevelopnewproductsandnewtechnologies,andatthesametimepayattentiontotherecyclingandreuseofPVCproducts.

AlthoughChinahastheworld’slargestPVCproductioncapacity,duetothedeclineinethyleneprices,theimportvolumeofethylene-basedPVCsetanewrecordin2009.Ontheotherhand,China’sPVCmarkethasalwaysbeenatalowstart.Ratestatus.Inthefirsthalfof2009,Chinaimportedabout1.2milliontonsofpolyvinylchloride,whichis1milliontonsmorethanthetotalimportvolumein2008.Withthesoaringpriceofethylene,thecompetitiveadvantageofChina'scalciumcarbideprocessPVCproductionhasemerged.Inthesecondhalfof2009,China'sPVCimportsdeclinedsteadily.AccordingtoChinaCustomsdata,importsinNovemberwereonly60,646tons.

Inthefirsthalfof2013,affectedbymanyunfavorablefactorssuchasovercapacityintheindustryandweakdownstreamdemand,theoverallperformanceofthepolyvinylchloride(PVC)industrywaspoor,andcompanieswereinadifficultsituation.However,theperformanceofthePVCforeigntrademarketiseye-catching,andanumberofdatahaveobviousrecoveryadjustmentscomparedwiththesameperiodinpreviousyears.However,industryinsiderspointedoutthatwiththeincreaseintheoperatingrateofPVCplantsintheUnitedStates,mycountry'sPVCforeigntradeisexpectedtoshowarecoverygrowthinimportsandasteadydeclineinexports.

AccordingtothestatisticsofChinaChlor-AlkaliIndustryAssociation,asoftheendofJune2013,thedomesticproductioncapacityofPVC(vagueresin)was23.92milliontonsperyear.Amongthem,inthefirsthalfof2013,thenewlyaddedproductioncapacityofPVCwas860,000tons/year,with350,000tons/yearexited,andanetincreaseof510,000tons/year,allwithdrawnproductioncapacitywascalciumcarbideproductionequipment.Theoverallproductioncapacityexpansionrateoftheindustryhassloweddownsignificantly,butthetrendofsteadyincreaseinproductioncapacitycontinues.

Intermsofexports,mycountry’scumulativeexportsofPVCfromJanuarytoMayincreasedsignificantlyby152.4%overthesameperiodlastyear.Fromtheperspectiveofflow,thelargestexportconsumermarketisIndia;thenumberofsourcesexportedtoRussiahassloweddown,rankingsecond.

Inaddition,sincetheoutbreakofthefinancialcrisis,greatchangeshavetakenplaceintheglobalmarketandtradeenvironment.Tradeprotectionisminvariouscountrieshasrisen,andtradefrictionsagainstChineseenterprises’productshaveincreasedsignificantly.

PhysicalandchemicalpropertiesofPVC

Thenaturalcolorisyellowishtranslucentandshiny.Transparencyisbetterthanpolyethyleneandpolypropylene,butworsethanpolystyrene.Dependingontheamountofadditives,itcanbedividedintosoftandhardpolyvinylchloride.Softproductsareflexibleandtough,andfeelsticky.Thehardnessofhardproductsishigherthanthatoflowdensitypolyethylene.However,ifitislowerthanpolypropylene,whiteningwilloccurattheinflection.Stable;noteasilycorrodedbyacidandalkali;relativelyresistanttoheat.

PVChasflameretardant(flameretardantvalueabove40),highchemicalresistance(resistanttoconcentratedhydrochloricacid,90%sulfuricacid,60%nitricacidand20%Sodiumhydroxide),theadvantagesofgoodmechanicalstrengthandelectricalinsulation.

Polyvinylchloridehaspoorstabilitytolightandheat.Thesofteningpointis80°C,anditstartstodecomposeat130°C.Withoutheatingthestabilizer,polyvinylchloridestartstodecomposeat100°C,anddecomposesfasterabove130°C.Whenheated,itdecomposesandreleaseshydrogenchloridegas(hydrogenchloridegasisatoxicgas)tochangeitscolorfromwhite→lightyellow→red→brown→black.Ultravioletraysandoxygeninthesunwillcausethephoto-oxidationanddecompositionofpolyvinylchloride,whichwillreducetheflexibilityofpolyvinylchlorideandeventuallybecomebrittle.ThisisthereasonwhysomePVCplasticsturnyellowandbecomebrittleovertime.

Ithasstablephysicalandchemicalproperties,isinsolubleinwater,alcohol,gasoline,andhaslowgasandwatervaporleakage;itcanwithstandanyconcentrationofhydrochloricacid,lessthan90%sulfuricacid,50-60%atroomtemperatureThenitricacidandcausticsodasolutionbelow20%havecertainresistancetochemicalcorrosion;itisquitestabletosalts,butitcanbedissolvedinorganicsolventssuchasethers,ketones,chlorinatedaliphatichydrocarbonsandaromatichydrocarbons.

Industrialpolyvinylchlorideresinismainlyamorphousstructure,butalsocontainssomecrystallineregions(about5%),sopolyvinylchloridehasnoobviousmeltingpoint,anditstartstosoftenatabout80°C,andtheheatdistortiontemperature(Under1.82MPaload)itis70-71°C,itstartstoflowat150°Cunderpressure,andslowlyreleaseshydrogenchloride,causingPVCtochangecolor(fromyellowtored,brown,orevenblack).

Theweight-averagerelativemolecularmassofindustrialpolyvinylchlorideisintherangeof4.8-48,000,andthecorrespondingnumber-averagerelativemolecularmassis2-19.5million.Theweight-averagerelativemolecularmassofmostindustrialresinsisbetween100,000and200,000,andthenumber-averagerelativemolecularmassisbetween45,000and64,000.Rigidpolyvinylchloride(withoutplasticizer)hasgoodmechanicalstrength,weatherresistanceandflameresistance,andcanbeusedaloneasastructuralmaterialforthemanufactureofpipes,platesandinjectionmoldedproductsinthechemicalindustry.Rigidpolyvinylchloridecanbeusedasareinforcingmaterial.

Materialproperties

Density:1380kg/m³

Young’smodulusofelasticity(E):2900-3400MPa

Tensilestrength(σt):50-80MPa

Elongationatbreak：20-40%

Glasstransitiontemperature:87℃

Meltingpoint:212℃

Softeningtemperature:85℃

(λ):0.16W/(m·K)

Coefficientofthermalexpansion(α):8×10^-5/K

Heatcapacity(c):0.9kJ/(kg·K)

Waterabsorption(ASTM):0.04-0.4

Refractiveindex:1.52~1.55

ThebiggestfeatureofPVCisflameretardant,soitiswidelyusedinfireprotectionapplications.Butpolyvinylchloridewillreleasehydrogenchlorideandothertoxicgasessuchasdioxinsduringthecombustionprocess.

ThecombustionofPVCisdividedintotwosteps.First,thehydrogenchloridegasandthedienecontainingdoublebondsaredecomposedbyburningat240°C-340°C,andthencarboncombustionoccursat400-470°C.

Itisoneofthelargestplasticproductsintheworld.Itischeapandwidelyused.PVCresiniswhiteorlightyellowpowder.Differentadditivescanbeaddedaccordingtodifferentpurposes,andPVCplasticscanpresentdifferentphysicalandmechanicalproperties.Addinganappropriateamountofplasticizertothepolyvinylchlorideresincanbemadeintoavarietyofhard,softandtransparentproducts.

Thedensityofpurepolyvinylchlorideis1.4g/cm³,andthedensityofpolyvinylchlorideplasticpartsaddedwithplasticizersandfillersisgenerally1.15-2.00g/cm³.

Rigidpolyvinylchloridehasgoodtensile,bending,compressionandimpactresistance,andcanbeusedasastructuralmaterialalone.

Theflexibility,elongationatbreak,andcoldresistanceofsoftPVCwillincrease,butthebrittleness,hardness,andtensilestrengthwilldecrease.

Polyvinylchloridehasgoodelectricalinsulationproperties,canbeusedaslow-frequencyinsulationmaterials,anditschemicalstabilityisalsogood.Duetothepoorthermalstabilityofpolyvinylchloride,long-termheatingwillcausedecomposition,releaseHCLgas,andmakepolyvinylchloridediscolor,soitsapplicationrangeisnarrow,andtheusetemperatureisgenerallybetween-15and55℃.

TheconversionofPVChardnessvaluePa(Pa)andShore(shore)hardnessisasfollows:

Moldingconditions

RigidPVC

Barreltemperature:160-190℃

Moldtemperature:40-60℃

Dryingtemperature:80℃×2h

Pressure:700-1500kg/cm²

Density:1.4g/cm³

Moldingshrinkage:0.1-0.5%

Meatthickness:2.0-50.mm

Waterabsorption(24h):0.1-0.4%

Meltingsofteningpoint:89℃

Heatdistortiontemperature:70℃

SoftPVC

Materialtubetemperature:140-170℃

Moldtemperature:40-60℃

Dryingtemperature:80℃×2h

Injectionpressure:600-1500kg/cm²

Density:1.4g/cm³

Moldingshrinkage:0.1-0.5%

Meatthickness:2.0-50.mm

Waterabsorption(24h):0.1-0.4%

Meltingsofteningpoint:85℃

Heatdistortiontemperature:55℃

Materialprocessing

PolyVinylchlorideplasticshavedifferentforms,withgreatdifferences,andvariousprocessingmethods,suchaspressing,extrusion,injection,coatingandsoon.Theparticlesize,fisheyes,bulkdensity,purity,foreignimpurities,andporosityofpolyvinylchlorideresinhaveanimpactonprocessability;forpasteresin,theviscosityandgellingpropertiesofthepasteshouldbeconsidered.

Polyvinylchlorideisanamorphouspolymerwithlowshrinkage.Thepowdershouldbepreheatedbeforeprocessingtoremovemoisture,enhancetheplasticizingeffect,andpreventbubbles.Moreover,PVCiseasytodecompose,especiallywhenitcomesincontactwithsteelandcopperathightemperatures(decompositiontemperature200degrees).Themoldingtemperaturerangeissmall,andthematerialtemperaturemustbestrictlycontrolled.Whenusingascrewinjectionmachineandastraight-throughnozzle,theapertureshouldbelargetopreventdeadendsfromstagnating.Themoldpouringsystemshouldbethick,thegatesectionshouldbelarge,themoldshouldbecooled,themoldtemperatureis30-60℃,andthematerialtemperatureis160-190℃.

Belowtheglasstransitiontemperature(Tg,80°C),polyvinylchlorideisglassy;atTg→viscousflowtemperature(Tf,about160°C),itisahighlyelasticrubberwithplasticity;atTf→Thethermaldecompositiontemperature(Td)isaviscousfluidstate,thehigherthetemperature,theeasiertheflow.WhenthetemperatureexceedsTd,PVCdecomposesalargeamountofhydrogenchloride(HCl),andthemateriallosesitschemicalstabilityandphysicalproperties.Therefore,Tdistheupperlimittemperatureforprocessingandmolding.DuetothelargeforcebetweenthepolyethylenemoleculesandthehighTf,evenclosetothedecompositiontemperature,itisnecessarytoaddaplasticizertoreducetheTf.Ontheotherhand,itisalsonecessarytoaddstabilizerstoincreasetheTdofPVCinordertobeprocessedandformed.

Theglasstransitiontemperature(Tg)isonlyrelatedtothemolecularchainsegmentstructure,andhaslittletodowiththemolecularweight.Theviscousflowtemperature(Tf)isthetemperatureatwhichmacromoleculesstarttomove,andisrelatedtothemolecularweight.Larger,thehigherTf.Therefore,forsomeprocessingmolding(suchasinjectionmolding),itisnecessarytoappropriatelyreducethemolecularweightoftheresin.Accordingtothedifferentmolecularweight,domesticsuspensionPVCresinisdividedinto1-7grades,thelargertheserialnumber,thesmallerthemolecularweight.XJ-4(XS-4)toXJ-7(XS-7)resinsareoftenusedinthemanufactureofhardpipes,hardboards,etc.OtherresinswithlowermodelsandlargermolecularweightsneedtobeaddedinlargeamountsduetohigherTf.TheagentreducesTf,soitisoftenusedinthemanufactureofsoftproducts.Polyvinylchloridewithanaveragedegreeofpolymerizationbelow1000iscalledlow-polymerizationdegreepolyvinylchloride,whichhasgoodprocessingproperties,andlessplasticizerscanbeaddedduringprocessing,sothattheproductwillnotbeacceleratedduetothemigrationofplasticizersAgeing.Polyvinylchlorideproductswithlowdegreeofpolymerizationhavegoodtransparencyandarewidelyusedinbuildingmaterials,foodandpharmaceuticalpackagingmaterialsandtoreplaceorganicglassproducts.

Polyvinylchloridemeltisanon-Newtonianpseudo-fluid.Thehighertheshearrate,thesmallertheapparentviscosity,andthechangeisquitesensitive.Increasingthetemperaturewillnotreducetheviscositymuch.Eveniftheplasticisbelowthedecompositiontemperature,itwillcauseheatandoxidativedegradationduetothehightemperatureforalongtime,whichwillaffectitsperformance.Therefore,toimprovethefluidityofPVCmelt,themainconsiderationshouldbetoincreasetheshearrate(increasethepressure).Infact,increasingtheexternalforcewillhelpthemovementofthemacromolecules,sothattheTfwillbereduced,andthemacromoleculescanflowatalowertemperature.

Mainuses

1.PVCprofile

ProfilesandprofilesarethelargestconsumptionofPVCinmycountry.Itaccountsforabout25%ofthetotalconsumptionofPVC.Itismainlyusedtomakedoorsandwindowsandenergy-savingmaterials.Itsapplicationvolumeisstillincreasingsignificantlyacrossthecountry.Indevelopedcountries,themarketshareofplasticdoorsandwindowsisalsothehighest,forexample,Germanyis50%,Franceis56%,andtheUnitedStatesis45%.

2.Polyvinylchloridepipes

Amongmanypolyvinylchlorideproducts,polyvinylchloridepipesarethesecondlargestconsumptionarea,accountingforabout20%ofitsconsumption.Inmycountry,polyvinylchloridepipesaredevelopedearlierthanPEpipesandPPpipes,withmorevarieties,excellentperformance,andawiderangeofapplications,andoccupyanimportantpositioninthemarket.

3.Polyvinylchloridefilm

TheconsumptionofPVCinthefieldofPVCfilmranksthird,accountingforabout10%.AfterPVCismixedwithadditivesandplasticized,athree-rollorfour-rollcalenderisusedtomakeatransparentorcoloredfilmwithaspecifiedthickness.Thefilmisprocessedinthiswaytobecomeacalenderedfilm.Itcanalsobecutandheat-sealedtoprocesspackagingbags,raincoats,tablecloths,curtains,inflatabletoys,etc.Thewidetransparentfilmcanbeusedforgreenhouses,plasticgreenhousesandmulchfilms.Thebiaxiallystretchedfilmhasthecharacteristicsofheatshrinkageandcanbeusedforshrinkpackaging.

4.PVChardmaterialsandplates

Stabilizers,lubricantsandfillersareaddedtoPVC.Aftermixing,itcanbeextrudedwithanextruder.Hardpipes,special-shapedpipesandcorrugatedpipesofvariouscalibersareusedassewerpipes,drinkingwaterpipes,wirecasingsorstaircasehandrails.Thecalenderedsheetsareoverlappedandhotpressedtomakehardplatesofvariousthicknesses.Theplatecanbecutintotherequiredshape,andthenweldedwithhotairwithPVCweldingrodtoformvariouschemicalresistantstoragetanks,airductsandcontainers.

5.GeneralsoftPVCproducts

Usinganextruder,itcanbeextrudedintohoses,cables,wires,etc.;usinganinjectionmoldingmachinetomatchvariousMoldscanbemadeintoplasticsandals,shoesoles,slippers,toys,autoparts,etc.

6.Polyvinylchloridepackagingmaterials

PVCproductsaremainlyusedforpackagingvariouscontainers,filmsandrigidsheets.PVCcontainersmainlyproducebottlesofmineralwater,beverages,andcosmetics,aswellaspackagingforrefinedoil.PVCfilmcanbeusedtoco-extrudewithotherpolymerstoproducelow-costlaminatesandtransparentproductswithgoodbarrierproperties.Polyvinylchloridefilmcanalsobeusedforstretchorheatshrinkpackagingforpackagingmattresses,cloth,toysandindustrialgoods.

7.Polyvinylchloridewallpanelsandfloors

PVCwallpanelsaremainlyusedtoreplacealuminumwallpanels.ExceptforapartofPVCresin,theothercomponentsofPVCfloortilesarerecycledmaterials,adhesives,fillersandothercomponents.Theyaremainlyusedonthegroundofairportterminalbuildingsandotherhardground.

8.Polyvinylchloridedailyconsumergoods

Luggagebagsaretraditionalproductsmadeofpolyvinylchloride,andpolyvinylchlorideisusedtomakeAllkindsofimitationleather,usedinluggage,sportsproducts,suchasbasketball,footballandrugby,etc.Itcanalsobeusedtomakebeltsforuniformsandspecialprotectiveequipment.Polyvinylchloridefabricsforclothingaregenerallyabsorbentfabrics(noneedtobecoated),suchasponchos,babypants,imitationleatherjacketsandvariousrainboots.Polyvinylchlorideisusedinmanysportsandentertainmentproducts,suchastoys,records,andsportsgoods.Polyvinylchloridetoysandsportsgoodshavealargegrowthrate.Theyhaveanadvantageduetotheirlowproductioncostandeasymolding.

9.PVCcoatedproducts

TheartificialleatherwithabackingismadebycoatingPVCpasteonclothorpaper,andthenplasticizingitatatemperatureabove100℃.化成。ItcanalsobeformedbycalenderingPVCandadditivesintoafilm,andthenpressingitwiththesubstrate.Artificialleatherwithoutasubstrateisdirectlycalenderedbyacalenderintoasoftsheetofacertainthickness,andthenthepatterncanbepressed.Artificialleathercanbeusedtomakesuitcases,purses,bookcovers,sofasandcarcushions,etc.,aswellasfloorleather,usedasfloorcoveringsforbuildings.

10.PVCfoamproducts

WhensoftPVCismixed,addanappropriateamountoffoamingagenttomakeasheet,whichisfoamedintofoamPlastic,canbeusedasfoamslippers,sandals,insoles,andshock-proofcushioningpackagingmaterials.Theextrudercanalsobeusedtoformlow-foamedhardPVCboardsandprofiles,whichcanreplacewoodandisanewtypeofbuildingmaterial.

11.PVCtransparentsheet

TheimpactmodifierandorganotinstabilizerareaddedtothePVCtobecometransparentaftermixing,plasticizingandcalenderingSheet.Thermoformingcanbemadeintothin-walledtransparentcontainersorusedforvacuumblisterpackaging.Itisanexcellentpackagingmaterialanddecorativematerial.

12.Others

Doorsandwindowsareassembledwithhardspecial-shapedmaterials.Insomecountries,ithasoccupiedthedoorandwindowmarkettogetherwithwoodendoors,windows,aluminumwindows,etc.;wood-likematerials,steel-basedbuildingmaterials(northern,seaside);hollowcontainers.

Virtualcircuitisoneoftheservicesprovidedbypacketswitchingnetwork(theotherisdatagramservice).Simplyput,itistoestablishavirtuallogicalconnectionbetweenuserhoststhroughthecontrolmechanisminsidethenetwork,Andtoensurethecorrectnessandsequenceofthetransmissionoftheenvelope,theestablishmentandremovalofthevirtualcircuitbeforeandafterthecommunication.Apermanentvirtualcircuitisavirtualcircuitthatisestablishedwhenthenetworkisinitialized,andthevirtualcircuitisalwaysmaintained.BothX.25networkandB-ISDNprovidePVCservices.PVCplasticbagsaregenerallyprohibited.

Researchonnewmaterials

Currently,thetotalannualdemandformodifiedplasticsinmycountryisabout5milliontons,accountingforabout10%oftotalplasticconsumption,anditsproportionisfarlowerthanthatoftheworld.Theaveragelevel.Comparedwiththedevelopedcountriesintheworld,mycountry'spercapitaplasticconsumptionstillhasabiggap.Inordertorealizetherapidandstabledevelopmentofmycountry'smodifiedplasticsindustry,innovativetechnologyisthekeytofuturedevelopment.

Chemicalindustryanalystsbelievethatthecurrentoveralldevelopmentlevelofmycountry’smodifiedplasticsindustryisnotveryhigh.Theproductionscaleofenterprisesintheindustryisgenerallysmall,theproductmarketproducesmanyprimaryproducts,andthequalityofintermediateproductsisnotstableenough.,Thelackofhigh-endproductsisfarfrommeetingtheneedsofmycountry’scurrentsocialandeconomicdevelopment.Asanimportantcomponentinthefieldofnewchemicalmaterials,modifiedplasticshavebeenlistedasoneofthekeyscientificandtechnologicalfieldsfordevelopmentbythecountry.Thesuccessiveintroductionofvariouspoliciesinmycountrywillfurtherpromotethedevelopmentofthemodifiedplasticsindustry.Theautomobileandhomeapplianceindustriesarehotspotsforthedevelopmentofmodifiedplastics,andbothaccountformorethan50%.

Theapplicationofplasticsintheautomotiveindustryhasahistoryofmorethan50years.Withthedevelopmentofautomobilesinthedirectionoflightweightandenergysaving,higherrequirementsareputforwardformaterials.Because1kgofplasticcanreplace2-3kgofsteelandotherheaviermaterials,andevery10%reductionintheweightofthecar,fuelconsumptioncanbereducedby6%-8%.Therefore,increasingtheamountofmodifiedplasticsusedinautomobilescanreducethecostandweightoftheentirevehicle,andachieveenergy-savingeffects.Theamountofdifferentplasticsusedinpassengercarsandcommercialvehiclesisalsodifferent.ThedemandformodifiedPP,PCalloyandmodifiedABSwasapproximately114.63,15.13and149,700tonsrespectivelylastyear.Themodifiedplasticsmarketforhouseholdappliancesinmycountryismainlyoccupiedbyforeigncompanies,anddomesticmodifiedplasticscompaniesaccountforlessthanone-thirdofthemarketshare.Sincetheproductsofdomesticcompaniesaremostlylimitedtolow-techandlow-standardlevels,theabilitytodevelopfieldswithhigh-performancerequirementsisobviouslyinsufficient.

Accordingtothe"2009-2012ChinaModifiedPlasticIndustryMarketAnalysisandInvestmentValueResearchReport",withthesubstantialimprovementofpeople’slivingstandardsandtheimprovementoftechnicalmeans,domestic"plasticsinsteadofsteel","Plasticinsteadofwood"willbecomeatrend.Themodifiedplasticsindustry,asasub-industrywiththefastestgrowthandgreatpotentialintheplasticsprocessingindustry,isexpectedtomaintainagrowthrateofmorethan10%inmycountry'stotalmarketdemandinthenextfiveyears.

1.PVCisusedtoreplacesteelmaterialwithplastic

ThroughtheresearchonPVCmodificationtechnology,theuseofforeignadvancedinternalplasticizationtechnologyandadditiveformulaensuresthemechanicalperformanceofPVCplasticsteel.,Electricalperformance,improvedflameretardantperformance,sothattheproducthastheadvantagesofhighstrength,corrosionresistance,flameretardant,goodinsulationperformance,lightweight,andconvenientconstruction.Itcancompletelyreplacesteelpipesinelectricalwiringsystems.

2.PVCisreplacedbywoodwithplastic

PVCwood-plasticcompositeisthemainrawmaterialofwastewoodfiberandplastic,supplementedbyappropriateprocessingaids,andispreparedbyhotpressing.Preparedintoanewtypeofcompositematerial.Itsproductsfullyreflecttheconceptofrecyclingofrenewableresourcesandpetroleumproducts,andareofgreatsignificancetoalleviatingthecurrentshortageofwoodandpetroleumresourcesandseriousenvironmentalpollution.

HomebuildingmaterialsproductsusingPVCasthemainrawmaterialhavebecomethesecondpillarofmycountry'splasticsindustry,withanaverageannualgrowthrateofmorethan15%.Inthenext10years,thecountryisexpectedtoincreasethebuildingareaof​​30billionsquaremeters.Ifthesebuildingsachieve50%energysavingontheexistingbasis,themarketdemandforenergy-savingbuildingmaterialscanreachtrillionsofyuan,whichisanindoorenergy-savingdecorationmaterial.Thereisahugeroomfordevelopment.Foralongtime,thebuildingmaterialsindustryhasalwaysappearedintheimageofhighenergyconsumptionandhighpollution.Inordertomeettherequirementsofthelow-carboneconomy,afteryearsofresearchanddevelopment,householdbuildingmaterialscompanieshavedevelopedabatchofPVChigh-simulationbuildingmaterialsthatuseplasticinsteadofwood,whichhavebecomeaperfectcombinationoflow-carbonandpracticalhouseholdproducts.

IndustryexpertspointedoutthattheuseofplasticinsteadofwoodforPVCbuildingmaterialsnotonlysavescosts,butisalsorecyclable,inlinewiththegeneraltrendofenvironmentalsustainabilityandcirculareconomy.

14.Syntheticmaterials

Polyvinylchloride,orPVCforshort,isathermoplasticresin.Polyvinylchloridefuturesarealsofuturesvarietieswithpolyvinylchlorideasthesubjectmatter.

Plastics:polyethylene;polyvinylchloride;polystyrene;polyvinylalcohol;polypropylene;polyacrylicacid;polybutene;polyisobutylene;polysulfone;polyoxymethylene;polyamide;polycarbonate;Polylacticacid;polytetrafluoroethylene;polyethyleneterephthalate;epoxyresin;phenolicresin;polyurethane

Syntheticrubber:butadienerubber;styrenebutadienerubber;nitrilerubber;neoprene

Syntheticfibers:polypropylene;polyester;nylon;acrylic;spandex;vinylon;nylon;dacron;Keflon

Identificationmethod

PVCConventionTheidentificationmethodsaregenerallysummarizedintothefollowingthreecategories,namely:

(1)Combustionmethodidentification:

Softeningormeltingtemperaturerange:75~90°C;

Combustionstatus:self-extinguishingafterbeingignited;

Combustionflamestatus:upperyellowandgreenwithsmoke;afterleavingthefire:leavingthefireextinguished;smell:pungentsour.

Thismethodistheeasiestandmostdirect,andisgenerallythefirstchoice.

(2)Solventtreatmentidentification:

Solvent:tetrahydrofuran,cyclohexanone,ketone,dimethylformamide;

Non-solvent:methanol,Acetone,heptane.

ByaddingthesuspectedPVCplastictotheabovesolvent,observethedissolutionoftheplastictodeterminewhetheritisPVC.Afterthesolventisheated,thedissolvingeffectwillbemoreobvious.

(3)Specificgravitymethod:

ThespecificgravityofPVCis1.35~1.45,generallyaround1.38.ThedifferenceinspecificgravityorthemethodofdeterminingspecificgravitycanbeusedtodistinguishPVCfromotherplastics.ButbecausePVCcanaddplasticizers,modifiersandfillerstomakethePVCbecomeverydifferentinspecificgravity,thedifferenceinsoftnessandhardnessisverylarge,andatthesametime,duetotheadditionofsomeingredients,manypropertiesofPVCplasticwillchange,resultinginOurcommonlyusedidentificationmethodsarenoteffective,andeventhephenomenonhaschanged,makingitimpossibletomakeaccuratejudgments.Forexample,intermsofdensity,plasticizedpolyvinylchloride(containingapproximately40%plasticizer)is1.19~1.35;whilePVChardproductshaveincreasedto1.38~1.50.IfitisahighlyfilledPVCproduct,thedensitysometimesexceeds2.

Inaddition,itcanalsobedeterminedbymeasuringwhetherthematerialcontainschlorine,butbecausevinylchloridecopolymers,neoprenerubber,polyvinylidenechloride,chlorinatedpolyvinylchloride,etc.allcontainahigherproportionofchlorine,Butalsothroughthepyridinecolorreactiontoidentify.Notethatbeforethetest,thesamplemustbeextractedwithethertoremovetheplasticizer.Testmethod:Dissolvethesampletakenfrometherwithbenzeneintetrahydrofuran,filterouttheinsolublecomponents,addmethanoltomakeitprecipitate,andextractthesamplebefore75Belowthedegreeofdryness.Donotneed1mLofpyridinetoreactwithasmallamountofdriedsample.Afterafewminutes,add2dropsofmethanolsolutionof5%sodiumhydroxide(1gsodiumhydroxideisdissolvedin20mLmethanol),andobservethecolorimmediately,5minAndobserveagainafter1h.Differentchlorine-containingplasticscanbeidentifiedbasedonthecolor.

Indailylife,PVCandPEplasticfilm(bag)needtobedistinguishedfrommorecontact.Simplemethod:

(1)Touchmethod

Itfeelslubricioustothetouch,andthesurfacelookslikealayerofwax(chemicallycalledwaxfeel).Thisisanon-toxicpolyethylenefilmbag,whilethePVCfilmfeelsalittlesticky.

(2)Shakingmethod

Whenshakingwithhands,thesoundisbrittle,andthethingthatfloatseasilyisapolyethylenefilmbag.Andthelowsoundofshakingwithhandsisapolyvinylchloridefilmbag.

(3)Combustionmethod

Incaseoffire,itisflammable,theflameisyellow,andthereisparaffin-likeoildrippingwhenburning,andthereisgasfromcandleburning.Itisanon-toxicpolymer.Vinylfilmbag.Ifitisnoteasytoburn,itwillbeextinguishedafterleavingthefire,theflamewillbegreen,anditwillbeapolyvinylchloridefilmbag.

(4)Immersionmethod

Immersetheplasticbaginwater,pressitintothewaterwithyourhand,theonethatcanrisetothesurfaceispolyethylene,andtheonethatsinksintothewaterispolyvinylchloride(polyvinylchloride).Thedensityofethyleneislessthanthatofwater,andthedensityofpolyvinylchlorideisgreaterthanthatofwater;atroomtemperature,theyareabout0.92g/cm³and1.4g/cm³).

Youcanalsotakeapieceofcopperwireandburnitinthefiretomakeitred.Then,contactthecopperwirewiththetestplasticfilmtocauseachemicalchange,andthenputthecopperwiredippedintheplasticcomponentbackagainIntheflames.Atthistime,youneedtoobservecarefully.Ifthereisacolorful,dazzlinggreenflame,itmeansthatthisplasticmaterialcontainschlorineandbelongstothepolyvinylchloridematerial.

Mainhazards

Polyvinylchlorideisalsoakindofplasticthatisoftenused.Itisaresincomposedofpolyvinylchlorideresin,plasticizerandantioxidant,anditisnottoxic.However,themainauxiliarymaterialssuchasplasticizersandantioxidantsaretoxic.TheplasticizersindailyPVCplasticsmainlyusedibutylterephthalateanddioctylphthalate.ThesechemicalsAllaretoxic,andleadstearate,anantioxidantforPVC,isalsotoxic.Lead-containinganti-agingagentofpolyvinylchloride(PVC)productscontactwithethanol,etherandothersolventswillprecipitatelead.Lead-salt-containingPVCisusedforfoodpackagingandencounterswithfrieddoughsticks,friedcakes,friedfish,cookedmeatproducts,cakesandsnacks,whichwillcauseleadmoleculestodiffuseintothegrease,soPVCplasticbagscannotbeusedContainfood,especiallyfoodcontainingoil.Inaddition,polyvinylchlorideplasticproductswillslowlydecomposehydrogenchloridegasatahighertemperature,suchasabout50°C,whichisharmfultothehumanbody.Therefore,polyvinylchlorideproductsarenotsuitableforfoodpackaging.

Becausemostdisposablemedicaldeviceproductsusemedicalgradepolyvinylchloride(PVC)orpolycarbonate(PC),andthethermaldecompositionproductsinthePVCprocessingprocessarecorrosivetosteel,PCThehardnessishighandtheviscosityishigh.Therefore,thematerialoftheplasticizedpartmustbecorrosion-resistant,wear-resistantandhavehighpolishingperformance.Mostmedicalinjectionmoldingmachinesusehardchromiumplatingonthebarrelscreworusestainlesssteelasthematerialtomakethemachinescrewtomeettheabovespecialrequirements.Inaddition,inordertopreventthermaldecompositionandgasgenerationduringPVCprocessing,itisrequiredtoaluminizethesurfaceofthemovabletemplate,andalsotoaluminizetheoutersheetmetalorusestainlesssteeltomakethesheetmetal,andthesheetmetaljointsaresealedwithnon-toxicsilicagel.Inordertopreventthegasgeneratedduringtheplasticprocessingfromescapingoutside(thegasgeneratedduringtheplasticprocessingcanbecollectedthroughspecialequipmentandthenpurifiedbeforebeingdischargedintotheatmosphere).

PVCisthemainsourceofdioxins.Dioxin(TCDD),thedeadliestsubstanceinthedioxinsfamily,isawell-knowncarcinogenandhormonedecomposer,andatoxiccompound,whichisveryharmfultohumansandanimals.DioxinsareproducedwhenPVCisproduced,recycled,anddestroyedinincinerators,orwhenPVCproductsareaccidentallyburned,suchaswhenburiedingarbage.