PET瓶結(jié)晶介紹課件

結(jié)晶簡介CRYSTALLIZATION化學(xué)學(xué)名為”聚對苯二甲酸乙烯酯(聚酯)”，是由對苯二甲酸(TPA)及乙二醇(EG)聚合而成的熱塑性聚合物，其反應(yīng)化學(xué)式如下：(TPA=PTA)化學(xué)名稱及其聚合反應(yīng)

PolyEthylene

Terephthalate

PET結(jié)晶-熱變化1.放熱反應(yīng)(EXO-THERMICREACTION)射出成型融熔態(tài)(MELTSTATE)固態(tài)瓶胚

2.吸熱反應(yīng)(ENDO-THERMICREACTION)瓶口牙區(qū)結(jié)晶固態(tài)無定型瓶口結(jié)晶態(tài)瓶口QUENCHED△冷卻加熱BCPREFORMBEFORECRYSTALLIZATION未結(jié)晶瓶胚(注塑瓶胚)ACPREFORMAFTERCRYSTALLIZATION

結(jié)晶瓶胚UnderstandingShrinkage&DistortionGlassTransitionTemperature(Tg)-isthepointatwhichaglasslikepolymerbecomessoftandpliable.AttheTgorslighlyabove,thepolymerchainsbecomefreetomove.InastandardstretchblownPETbottlethathasbeenheatedorfilledatTg,theresidualstressesimpartedontheamorphousregionsduringorientationbecomefreetorelaxandthebottleshrinksanddeforms.ThetypicalglasstransitionTemperatureofastandardstretchblownPETbottleis~80°C.Asdiscussedearlierthisdoesnotmeetthetemperaturerequirementsforvarioushotfillproducts.結(jié)晶RateofCrystallization結(jié)晶速率PROCESSWINDOW結(jié)晶速率溫度加工窗結(jié)晶機制

MechanismsforAchievingCrystallinityinPET拉伸誘導(dǎo)結(jié)晶—瓶身

Orientation(“Strain-inducedcrystallinity”) -Improvesmechanicalandbarrierproperties

增強抗力及阻隔效果

-CanAchieve20-28%crystallinityinstandardPETbottlesidewall.

PET瓶瓶壁之結(jié)晶度可達(dá)20-28% -Crystalsdonotinterferewithcontainerclarity

可維持容器之透明度熱誘導(dǎo)結(jié)晶---瓶口

Heating(“thermallyinducedcrystallinity”)

-Improvesthermalstabilityofcontainer

增強容器對熱之穩(wěn)定度

-Canachieve30-35%crystallinity

結(jié)晶度可達(dá)30–35%(NeckFinish瓶口)-Spheruliticcrystalsinterferewithclarityandcauseopacity

所誘導(dǎo)之結(jié)晶大而致不透明LATTICE晶格,點陣結(jié)晶核未定型部位Crystallinty直線型分子結(jié)構(gòu)

結(jié)晶度高分枝型分子結(jié)構(gòu)結(jié)晶度低瓶口于結(jié)晶時發(fā)生之變化體積收縮密度升高會散熱釋放內(nèi)應(yīng)力會變形會變硬但耐熱性增強耐化學(xué)性增強影響PET結(jié)晶之因素加熱時間:時間長結(jié)晶度高加熱溫度:溫度高結(jié)晶度高IV:IV低易結(jié)晶顏色

:顏色深易結(jié)晶含水量:瓶胚含水份高易結(jié)晶OneofthemostimportantcharacteristicsofPETisreferredtoasI.V.(intrinsicviscosity).TheI.V.ofthematerial,measuredindl/g(deciliters/gram)isdependentuponthelengthofitspolymerchains.Thelongerthechains,thestifferthematerial,andthereforethehighertheI.V.Theaveragechainlengthofaparticularbatchofresincanbecontrolledduringpolymerization.IV是PET重要特征之一,原料之IV單位以dl/g表示(deciliters/gram);PETIV與聚合物之分子結(jié)構(gòu)有關(guān),聚合物之化學(xué)煉愈長,,黏稠愈大,也就是IV

高.于聚合反應(yīng)中可以控制所需要之平均化學(xué)煉長度(IV).I.V.ofabout:0.60-Wouldbeappropriateforfiber0.65-Film0.76-0.84-Bottles0.85-TirecordIntrinsicviscosity固有黏度項目單位碳酸飲料水瓶熱罐裝飲料瓶(HR)食用油瓶粘度dl/g0.875±0.0200.8±0.0200.78±0.0200.83±0.020乙醛含量mg/kg≤1.0≤1.0≤1.0≤1.0色度b值--≤2.0≤2.0≤2.0≤2.0端羧基含量mol/t≤35≤35≤35≤35熔點℃249±2249±2253±2248±2粉末mg/kg≤100≤100≤100≤100灰分%≤0.08≤0.08≤0.08≤0.08水分%≤0.4≤0.4≤0.4≤0.4PET瓶原料分類DESCRIPTION

VALUE

TESTINGMETHOD

I.V.(dl/g)0.76±0.02ASTMD2857MELTINGPOINT(°C)253±4ASTMD3418MOISTURECONTENT(wt%)

<0.5ASTMD4019-COOH(equ/kg)MAX.30ZIMMERPV.07013.4A.A.CONTENT(ppm)acetaldehyde<1CELANESEPELLETSHAPEOVAL---------BULKDENSITY(g/cm3)0.9±0.1ASTMD792MOLDINGTEMP.(°C)275～295---------PET原料規(guī)格(HRGRADE)

適用性(BOTTLEGRADE)I.V.VALUEPOLYMER聚合物APPLICATION0.76HOMO-POLYMERORCOPOLYMERHOTFILLINGBOTTLE0.84COPOLYMERSOFTDRINK1-PIECEBOTTLE0.80COPOLYMERWATER&SOFTDRINKWATERBOTTLE0.76COPOLYMERWATERBOTTLE&PETSHEETCOPOLYMER共聚合物

HOMOPOLYMER單一聚合物L(fēng)INEARBRANCHED

HOMOPOLYMER&COPOLYMER

(單一聚合物及共聚合物)BOTTLE-TOP

HOMOPOLYMER(單一聚合物)

1ACID

+1GLYCOL

COPOLYMER(共聚合物) 2ACID+1GLYCOL

OR 1ACID+2GLYCOL

<ACID—酸

GLYCOL--醇

>

POLYCONDENSATIONOPTIONS

HOMOPOLYMER(LINEARSTRUCTURE)

直線分子結(jié)構(gòu)

TPA+EG→PET

COPOLYMER(LINEAR&BRANCHSTRUCTURE)

直線及支鏈分子結(jié)構(gòu)

TPA+IPA+EG→PETTPA+EG+CHDM→PET

HOMOPOLYMER&COPOLYMER比較表

比較項目單一聚合物共聚合物CRYSTALLINEMELTTEMP.(Tm)熔點HIGHERLOWERENERGYCONSUME(MELTING)能源消耗HIGHERLOWERPREFORMINJECTIONCOOLINGTIME注塑冷卻時間LONGERSHORTERA.A.CONTENT乙醛含量HIGHERLOWERTHERMALDEGRADATION熱衰解HIGHERLOWERPROCESSWINDOW加工窗NARROWWIDECLARITY透明性LOWERHIGHERVOLUMEINCREASE(CREEP)蠕動現(xiàn)象LOWERHIGHERTENSILESTRENGTH抗拉強度HIGHERLOWER增加共聚合單體（COPOLYMER）效應(yīng)

性質(zhì)效應(yīng)熔點(能量需求少)結(jié)晶度CRYSTALLITY沖擊強度/韌性(IMPACT)抗StressCrack(抗破裂強度)融熔黏度MELTVISCOCITY阻隔性(BARRIER)

偏極光儀(應(yīng)力儀)之運用

BOTTLE-TOP

偏極光儀(應(yīng)力儀)之運用

BOTTLE-TOP檢視殘留應(yīng)力(射出瓶胚)定期檢視(ONCE2WEEKS)射出瓶胚殘

留應(yīng)力之狀況確保質(zhì)量(質(zhì)量)

干燥射出結(jié)晶吹瓶

殘留應(yīng)力(RESIDUALSTRESS)

高溫之融熔態(tài)原料經(jīng)噴嘴以高壓射出瞬間進入冷卻模具時,會產(chǎn)生大量應(yīng)力當(dāng)應(yīng)力尚未來得及消退時,實時被冷卻,

固化故又稱凍結(jié)應(yīng)力(FROZEN-INSTRESS)WHYWEHAVETO

定期檢視(兩星期一次)射出瓶胚

殘留應(yīng)力之狀況檢視模具內(nèi)各模穴之冷卻狀況是否正常在偏光儀下會有似亂流之現(xiàn)象(不正常)

原料(CHIPS)干燥不夠

原料(CHIPS)干燥不夠

<CHIPS干燥后水份含量小于50ppm為標(biāo)準(zhǔn)>耐沖擊力(IMPACTSTRENGTH)下降加工特性改變結(jié)晶速度加快瓶胚有白化之風(fēng)險(INJECTION)

瓶胚有黃化之風(fēng)險(INJECTION)A.A.(ACETALDEHYDE)乙醛含量增加

耐沖擊力(IMPACTSTRENGTH)下降

在料管及熱澆道融熔狀態(tài)下(MELTSTATE)產(chǎn)生水解作用(HYDROLYSIS)

含水份高時,高分子聚合物水解而切斷化學(xué)鍵分子量變小→耐沖擊下降產(chǎn)生酸解作用(ACIDOLYSIS)

高分子聚合物酸解而切斷化學(xué)鍵分子量下降

A.A.含量增加更加速熱衰解而產(chǎn)生黃變(黃化)

ReduceImpactStrength

Happenduringthemeltstate(insidescrewbarrelandhotrunner)Reactwithmoisture:(Hydrolysis)ThePETchainreactswithH20intheresinandbreaksdownthechain.TheresultisshortermolecularchainsandreducedimpactresistanceACIDOLYSIS:ReactionwithacidbreaksdownthemolecularchainresultinginshortermoleculesandincreasedA.A.level.Alsoincreasethespeedofthermalbreakdownandyellowingof