1. Ungazikhetha njani iiDicarboxylic Acids kwiPolyester Polyol Formulation?

IiAromatic Acids: Ukuphucula Ukuqina kunye Nokumelana Nobushushu

I-Isophthalic Acid (IPA) kunye ne-Terephthalic Acid (PTA)

Ii-aromatic dicarboxylic acids zisetyenziswa kakhulu ukuphucula:

I-Terephthalic acid (PTA)inesakhiwo esithe ngqo nesiqinileyo kunye notyekelo oluqinileyo lwekristale.

Xa i-PTA isabela kwii-diols ezimfutshane ezifana ne-ethylene glycol (EG) okanye i-1,4-butanediol (BDO), isakhiwo se-polyester esiphumayo sinokubonisa ukuziphatha okuqinileyo kwe-crystallization, okubangela ukuba i-polyester polyol ibe yi-wax okanye iqine kubushushu begumbi.

Oku kunokunciphisa:

• ✖Ukucubungula ukutyibilika
• ✖Uzinzo lokugcina
• ✖Ukulungeleka kwesicelo

Ngoko ke, iipolyester polyols ezisekelwe kwi-PTA ezicocekileyo azisetyenziswa rhoqo zodwa kwiifomyula ezisebenzayo.

I-Isophthalic acid (IPA)inesakhiwo semolekyuli esingalinganiyo kangako kuba amaqela amabini e-carboxyl akwindawo ye-meta. Oku kunciphisa ukuthambekela kwe-crystallization kwaye kuphucula uzinzo lolwelo.

Iipolyester polyols ezisekwe kwi-IPA ngokubanzi zibonelela:

• ✔I-Tg ephezulu
• ✔Ukucaca okungcono
• ✔Ukuphucula ukuhamba kwamanzi

Kwiifomyula ezininzi zoshishino, i-IPA iziswa kunye ne-PTA okanye ii-aliphatic acids ukulinganisela ukuqina kunye nokuguquguquka.

I-Aliphatic Acids: Ukwandisa Ukuguquguquka

I-Adipic Acid (AA)

I-Adipic acid yenye yezona asidi ze-aliphatic dicarboxylic ezisetyenziswa kakhulu kwimveliso ye-polyester polyol.

Ikhonkco layo eliguquguqukayo leekhabhoni ezintandathu libonelela:

• •Ukuguquguquka kobushushu obuphantsi
• •Ukuqina okuhle
• •I-Tg encitshisiweyo

Iipolyester polyols ezisekelwe kwi-Adipic acid zihlala zinexabiso le-Tg elimalunga ne--60°C ukuya ku -40°C, kuxhomekeke kwisakhiwo seemolekyuli.

Olu lwakhiwo lunegalelo koku:

• •Amandla aphezulu okuxinana
• •Ukumelana okuhle nokukrala
• •Ukusebenza kakuhle koomatshini

I-Sebacic Acid (SA)

I-asidi yeSebacic inekhonkco lekhabhoni elide kune-asidi ye-adipic.

Iingenelo:

• ✔Ukuguquguquka okuphezulu
• ✔Ukusebenza ngcono kobushushu obuphantsi
• ✔Iipropati eziphuculweyo zokungakhathali ngamanzi

Nangona kunjalo, ngenxa yexabiso layo eliphezulu, i-SA isetyenziswa kakhulu kwizicelo ze-polyurethane ezisebenza kakuhle apho kufuneka khona ukumelana nokubanda okuphuculweyo.

Iinxalenye ze-Acid ezisebenzayo: i-Dimer Acid kunye ne-Phthalic Anhydride

I-Dimer Acid

I-asidi ye-Dimer ivelisa oku:

• •Iitsheyini ezinde eziguquguqukayo zemolekyuli
• •Iimpawu ze-hydrophobic
• •Ukuphucula ukuguquguquka
• •Ukumelana okungcono kwe-hydrolysis

Nangona kunjalo, ukonyuka komxholo we-dimer acid kunokunciphisa i-Tg kunye nobunzima. Iqhele ukuqwalaselwa kwiinkqubo ze-polyurethane ezifuna ukuguquguquka kunye nokumelana nokufuma.

I-Phthalic Anhydride (PA)

I-anhydride ye-Phthalic yinxalenye yevumba elimnandi nelingabizi kakhulu kwaye isebenza kakuhle.

Ingaphucula:

• ✔Ukuqina
• ✔Ukuqina
• ✔Ukhuphiswano lweendleko

Nangona kunjalo, ngenxa yeziphumo ze-steric, i-reactivity yayo yeqela lesiphelo iphantsi xa ithelekiswa ne-IPA.

Icebo Eliqhelekileyo Lokuyila I-Acid

Icebo eliqhelekileyo lokwenza i-polyester polyol lelo:

• •Iiasidi ezinuka kamnandi: zinika ukuqina kunye namandla
• •Iiasidi ze-Aliphatic: zibonelela ngokuguquguquka nokuqina

Umlinganiselo ochanekileyo kufuneka uhlengahlengiswe rhoqo ngokwesicelo esijoliswe kuso.

2. Ungazikhetha njani iiDiols zoYilo lwePolyester Polyol?

I-Ethylene Glycol (EG)

I-ethylene glycol yeyona diol ilula esetyenziswa kwi-polyester chemistry.

Ngenxa yesakhiwo sayo esifutshane seemolekyuli, i-EG ibonelela:

• •Ukuhlala rhoqo kwetyathanga eliphezulu
• •Utyekelo oluqinileyo lwe-crystallization

Xa idityaniswe ne-PTA, i-EG inokwenza izakhiwo zekristale ezifana ne-PET, ezinokubangela ukuba ii-polyester polyols zibe ziqinile kubushushu begumbi. Ke ngoko, ii-polyester polyols ezisekelwe kwi-EG ezicocekileyo aziqhelekanga.

Kwiifomyula ezisebenzayo, i-EG idla ngokudityaniswa nezi:

ukulungisa ubukrelekrele kunye nokusebenza kokucubungula.

Enye inzuzo ebalulekileyo ye-EG yile:

• ✔Ixabiso eliphantsi
• ✔Ukufumaneka ngokubanzi

Kwimveliso yepolyester polyol esekwe kwizixhobo zePET ezisetyenzisiweyo, i-EG ihlala iyinto ebalulekileyo eluhlaza.

I-Diethylene Glycol (DEG)

I-DEG ingenisa iibhondi ze-ether kwikhonkco le-polyester.

Unxibelelwano oluguquguqukayo lwe-ether lubonelela:

• •I-Tg esezantsi
• •Ukuncipha kwe-viscosity
• •Ukusebenza kakuhle kokuhamba kwamanzi

Iipolyester polyols ezisekwe kwi-DEG zisetyenziswa kakhulu xa kubalulekile ukucubungula ukuguquguquka.

Nangona kunjalo, iibhondi ze-ether zinokuba nokumelana okuphantsi kwi-oxidation yobushushu bexesha elide. Ke ngoko, iinkqubo ze-DEG zihlala zidityaniswa nee-diols ezizinzileyo ngakumbi ezifana ne-NPG.

I-Neopentyl Glycol (NPG)

I-NPG inesakhiwo sekhabhoni esibizwa ngokuba yi-quaternary carbon esinamaqela amabini e-methyl.

Olu lwakhiwo lukhethekileyo luthintela intshukumo ye-molecular kwaye lubonelela:

• •I-Tg ephezulu
• •Uzinzo oluhle kakhulu lobushushu
• •Ukumelana nemozulu okugqwesileyo
• •Ukuphucula ukumelana ne-hydrolysis

Ngenxa yokuqina kwayo okugqwesileyo, i-NPG isetyenziswa kakhulu kwezi zinto zilandelayo:

• •Iingubo ze-PU
• •Izicelo zangaphandle
• •Iinkqubo ze-polyurethane ezimelana nemozulu

I-1,4-Butanediol (BDO)

I-1,4-Butanediol yenye yezona diol zibalulekileyo ezisetyenziswa kwi-polyurethane elastomer kunye ne-TPU.

Ulwakhiwo lwayo olunemigca ye-carbon ezine lubonelela:

• •Ukulungelelaniswa kakuhle kwetyathanga
• •Ukusebenzisana okunamandla phakathi kweemolekyuli
• •Iipropati ezibalaseleyo zoomatshini

Xa zidityaniswe nee-aromatic acids ezifana ne-PTA, i-BDO inokwenza amacandelo e-crystalline acwangciswe kakuhle afana nezakhiwo ze-PBT.

Oku kunegalelo koku:

• ✔Amandla aphezulu okuxinana
• ✔Ukumelana okungcono kokukrala
• ✔Ukuphucula ukunxibelelana ngokwasemzimbeni

Nangona kunjalo, umxholo ophezulu we-BDO unokunyusa ukuthambekela kwe-crystallization, okubangela ukuba ii-polyester polyols zibe yi-wax okanye ziqine kubushushu begumbi.

Ukuphucula ukusebenza kokucubungula, i-BDO idla ngokudityaniswa ne:

ukunciphisa i-crystallization egqithisileyo ngelixa kugcinwa amandla oomatshini.

I-Trimethylolpropane (TMP): Ukwazisa i-Controlled Branching

I-Trimethylolpropane (TMP) yi-alcohol esebenza ngeendlela ezininzi equlethe amaqela amathathu e-hydroxyl. Ngokungafaniyo nee-diols eziqhelekileyo, i-TMP ingenisa izakhiwo ezidibanisayo kwii-polyester polyols.

Inani elincinci le-TMP linokwanda:

• •Ukwahlulwa kweemolekyuli
• •Uxinano lwe-Crosslink
• •Ubulukhuni bokugqibela be-polyurethane

I-TMP isetyenziswa kakhulu xa kuyilwa:

• •Iingubo zepolyurethane ezisebenza kakuhle
• •Iinkqubo ze-PU eziqinileyo
• •Iiprepolymers ze-polyurethane ezihlanganisiweyo

Kwiifomyula ezininzi, umxholo we-TMP ulawulwa ngononophelo kuba ukuhluma okugqithisileyo kunokunyusa kakhulu i-viscosity kwaye kunciphise ukuqhubekeka kokusebenza.

3. Ungaluhlengahlengisa njani umlinganiselo we-Alcohol-to-Acid kwi-Polyester Polyol Formulation?

Umlinganiselo Ogqithisileyo Wotywala

Kwi-polyester polyol synthesis, izinto ezisetyenziswa kwi-alcohol zihlala zisetyenziswa kakhulu ukuze kufezekiswe izakhiwo ezipheliswe yi-hydroxyl.

Kwi-polyester polyols ezinobunzima obuphantsi be-molecular weight, umlinganiselo wotywala ogqithisileyo unokwandiswa uye kwi:1.8–2.0: 1

Amaxabiso aphezulu e-hydroxyl anika amaqela e-hydroxyl asabela ngakumbi ekwakhiweni kwe-polyurethane.

Nangona kunjalo, ukusela kakhulu kunokunciphisa ubunzima beemolekyuli kwaye kuchaphazele kakubi:

Ngoko ke, umlinganiselo wotywala kwi-asidi kufuneka uphuculwe ngokwendlela esetyenziswa ngayo i-polyurethane yokugqibela.

Ubudlelwane Phakathi Komlinganiselo Wotywala kunye Nexabiso Le-Asidi

Ngexesha lokwenziwa kwepolyester polyol, amanzi avelisiweyo asuswa rhoqo ukuze kuqhutywe phambili i-esterification kunye ne-condensation reactions.

Ukuba utywala obuninzi alwanelanga:

• •Uxinzelelo lwe-asidi luhlala luphezulu
• •Impendulo iba kancinci
• •Ixabiso le-asidi yokugqibela liba nzima ukulinciphisa

Ixabiso eliphantsi le-asidi libalulekile kuba ii-residual acids zinokuchaphazela ii-polyurethane reactions. Xa i-polyester polyol isabela kunye nee-isocyanates, i-residual moisture kunye nee-acid components zinokuba negalelo kwi:

Kwizicelo ezininzi ze-polyurethane, ixabiso le-asidi elilawulwayo lingezantsi:1 mg ye-KOH/gyinto ekujoliswe kuyo esemgangathweni obalulekileyo.

4. Indlela yokukhethaIikhatalystkwiMveliso yePolyester Polyol?

Ukukhetha phakathi kweTBT kunye neBTO kuxhomekeke koku kulandelayo:

5. Ulawulo lweNkqubo yokuVelisa iPolyster Polyol

Amanqanaba aphambili aquka:

1. Ukuqinisekiswa kwe-esterification
2. Ukufuma kwePolycondensation
3. Ixabiso leHydroxyl kunye nokulungiswa kwexabiso le-asidi

Inyathelo 1: Isigaba sokuqinisekiswa kwe-Esterification

Ngexesha lesigaba sokwenziwa kwe-esterification, ezi zinto zilandelayo zitshajwa kwi-reactor:

Impendulo idla ngokuqala malunga:180°C

Amanzi aveliswa yi-esterification asuswa ngolu hlobo:

• •Ukususwa kwenitrogen
• •Iinkqubo zeCondenser

Inkqubela yempendulo ingajongwa ngokusebenzisa:

• •Ubungakanani bokuqokelelwa kwamanzi
• •Uvavanyo lwexabiso le-asidi

Inyathelo lesi-2: Inqanaba le-Polycondensation

Emva kokuqinisekiswa kwe-esterification, inkqubo ingena kwisigaba se-polycondensation.

Iimeko eziqhelekileyo:

• •Ubushushu:200–220°C
• •Uxinzelelo oluncitshisiweyo: ukusebenza kwe-vacuum

I-vacuum inceda ukususa amanzi aseleyo kunye notywala obuninzi, nto leyo eqhuba ukukhula kwee-molecular.

Nangona kunjalo, ubushushu obugqithisileyo okanye ixesha elide lokuphendula linokubangela iimpembelelo ezingalindelekanga, ukwanda kombala, kunye nokuwohloka kwepolymer. Ke ngoko, iimeko zenkqubo kufuneka zilawulwe ngononophelo.

Inyathelo lesi-3: Ulawulo lwePoint End

Ngokungafaniyo ne-PET polymerization, ukuveliswa kwe-polyester polyol akudingi uphuhliso oluphezulu kakhulu lwe-molecular weight. Izalathisi eziphambili zomgangatho zezi:

Injongo eqhelekileyo yemizi-mveliso:Ixabiso le-asidi <1 mg KOH/gngaphambi kokukhululwa.

Ukungabikho komoya owaneleyo yenye yezizathu eziphambili zezi:

• ✖Ukufuma okuphezulu okushiyekileyo
• ✖Ixabiso eliphezulu le-asidi
• ✖Ukusebenza kakubi kwe-polyurethane

6. Isishwankathelo soYilo lwePolyester Polyol

Into yoYilo	Iinguqu eziphambili	Umgaqo wokukhetha	Uluhlu oluqhelekileyo
Ukuqina komqolo	I-IPA, i-PTA, i-AA, i-SA	Iiasidi ezinuka kamnandi ziphucula ukuqina; iiasidi ze-aliphatic ziphucula ukuguquguquka	I-IPA/AA ≈ 7:3
Uhlengahlengiso lwe-Tg	I-EG, i-DEG, i-NPG, i-BDO	I-EG inyusa ubukhristalo; i-DEG inciphisa ubukhristalo; i-NPG iphucula ukuqina; i-BDO iphucula amandla	Ngokusekelwe kwisicelo
Ulawulo lobunzima be-molecular	Umlinganiselo wotywala kwi-asidi	Utywala obuninzi budala izakhiwo ezipheliswe yi-hydroxyl	Utywala/i-asidi = 1.3
Ukukhetha iCatalyst	I-TBT vs BTO	I-TBT yokusabela ngokukhawuleza; i-BTO yozinzo olungcono lwe-hydrolysis	I-BTO 0.2–0.5‰
Ulawulo lwamasebe	I-TMP/iGlycerol	Izongezo ezincinci ziphucula uxinano lwe-crosslink	I-TMP ≤3 mol%

7. Uyilo lwePolyester Polyol luyichaphazela njani indlela esebenza ngayo iPolyurethane?

Isicelo	Uyilo lwePolyester Polyol olucetyiswayo
Izincamathelisi zePU	Iipolyols zepolyester ezisekelwe kwi-AA eziguquguqukayo ukuze zinamathele kwaye ziqine
Iingubo zePU	Iinkqubo ze-IPA/NPG zokuqina kunye nokumelana nemozulu
Ii-TPU Elastomers	Iinkqubo ze-AA + BDO zokomelela koomatshini kunye nokumelana nokukrala
I-PU eqhutywa ngamanzi	Iipolyol zepolyester ezingamelani ne-hydrolysis ezineenkqubo ze-catalyst ezilungiselelweyo
Isikhumba esenziwe ngokwenziwa	Iipolyester eziguquguqukayo kunye nokuthamba okulawulwayo

Iimfuno zesicelo → Iithagethi zokusebenza → Ukukhethwa kweMonomer → Uyilo lwesakhiwo seMolekyuli → Ukukhethwa kweCatalyst → Ukulungiswa kwenkqubo