1. Ungazikhetha Kanjani I-Dicarboxylic Acids Yokwenza I-Polyester Polyol?

Ama-Aromatic Acids: Ukuthuthukisa Ukuqina Nokumelana Nokushisa

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

Ama-dicarboxylic acid anephunga elimnandi asetshenziswa kakhulu ukuthuthukisa:

I-Terephthalic acid (PTA)inesakhiwo esiqondile esijwayelekile kakhulu kanye nokuthambekela okuqinile kokwakheka kwamakristalu.

Uma i-PTA isabela ngama-diols amafushane afana ne-ethylene glycol (EG) noma i-1,4-butanediol (BDO), isakhiwo se-polyester esiphumelayo singase sibonise ukuziphatha okuqinile kwe-crystallization, okubangela ukuthi i-polyester polyol ibe yi-wax noma iqine ekushiseni kwegumbi.

Lokhu kunganciphisa:

• ✖Ukucubungula uketshezi
• ✖Ukuqina kwesitoreji
• ✖Ukulula kohlelo lokusebenza

Ngakho-ke, ama-polyester polyol ahlanzekile asekelwe ku-PTA awavamile ukusetshenziswa wodwa ekwakhiweni okusebenzayo.

I-Isophthalic acid (IPA)inesakhiwo sama-molecule esingalingani kangako ngoba amaqembu amabili e-carboxyl atholakala endaweni ye-meta. Lokhu kunciphisa ukuthambekela kwe-crystallization futhi kuthuthukisa ukuzinza koketshezi.

Ama-polyester polyols asekelwe ku-IPA ngokuvamile ahlinzeka:

• ✔I-Tg Ephakeme
• ✔Ukubonakala okungcono
• ✔Ukugeleza okuthuthukisiwe

Ezinhlotsheni eziningi zezimboni, i-IPA yethulwa kanye ne-PTA noma ama-aliphatic acid ukuze kulinganiswe ukuqina nokuguquguquka.

Ama-Acid e-Aliphatic: Ukwandisa Ukuguquguquka

I-Adipic Acid (AA)

I-Adipic acid ingenye yama-asidi e-aliphatic dicarboxylic asetshenziswa kakhulu ekukhiqizweni kwe-polyester polyol.

Iketanga layo eliguquguqukayo le-carbon eziyisithupha linikeza:

• •Ukuguquguquka kwezinga lokushisa eliphansi
• •Ukuqina okuhle
• •I-Tg encishisiwe

Ama-polyester polyol asekelwe ku-Adipic acid ngokuvamile anamanani e-Tg aphakathi kuka--60°C kuya ku-40°C, kuye ngesakhiwo sama-molecule.

Lesi sakhiwo sinegalelo ku:

• •Amandla aphezulu okudonsa
• •Ukumelana okuhle kokuklwebheka
• •Ukusebenza okuhle kakhulu kwemishini

I-Sebacic Acid (SA)

I-Sebacic acid iqukethe uchungechunge lwekhabhoni olude kune-adipic acid.

Izinzuzo:

• ✔Ukuguquguquka okuphezulu
• ✔Ukusebenza okungcono kwezinga lokushisa eliphansi
• ✔Izakhiwo ezithuthukisiwe ze-hydrophobic

Kodwa-ke, ngenxa yezindleko zayo eziphakeme, i-SA isetshenziswa kakhulu ekusetshenzisweni kwe-polyurethane esebenza kahle lapho kudingeka khona ukumelana nokubanda okuthuthukisiwe.

Izingxenye ze-Acid ezisebenzayo: i-Dimer Acid kanye ne-Phthalic Anhydride

I-Dimer Acid

I-Dimer acid iveza okulandelayo:

• •Amaketanga amade aguquguqukayo ama-molecule
• •Izakhiwo ze-Hydrophobic
• •Ukuguquguquka okuthuthukisiwe
• •Ukumelana okungcono kwe-hydrolysis

Kodwa-ke, ukwanda kokuqukethwe kwe-dimer acid kunganciphisa i-Tg kanye nokuqina. Ngokuvamile kubhekwa njengezinhlelo ze-polyurethane ezidinga ukuguquguquka kanye nokumelana nomswakama.

I-Phthalic Anhydride (PA)

I-anhydride ye-phthalic iyisakhi esiphunga esingabizi kakhulu futhi esisebenza kahle ekuphenduleni.

Kungathuthukisa:

• ✔Ubulukhuni
• ✔Ukuqina
• ✔Ukuncintisana kwezindleko

Kodwa-ke, ngenxa yemiphumela ye-steric, ukusebenza kwayo kweqembu lokugcina kuphansi uma kuqhathaniswa ne-IPA.

Isu Elijwayelekile Lokuklama I-Acid

Isu elivamile lokwakha i-polyester polyol yileli:

• •Ama-asidi anuka kamnandi: anikeza ukuqina namandla
• •Ama-asidi e-aliphatic: anikeza ukuguquguquka nokuqina

Isilinganiso esiqondile kufanele ngaso sonke isikhathi silungiswe ngokuya ngesicelo esiqondiwe.

2. Ungazikhetha Kanjani I-Diols Yomklamo We-Polyester Polyol?

I-Ethylene Glycol (EG)

I-ethylene glycol iyi-diol elula kakhulu esetshenziswa kumakhemikhali e-polyester.

Ngenxa yesakhiwo sayo esifushane sama-molecule, i-EG inikeza:

• •Ukuhleleka kwe-high chain
• •Ukuthambekela okunamandla kokwakheka kwamakristalu

Uma ihlanganiswa ne-PTA, i-EG ingakha izakhiwo zekristalu ezifana ne-PET, okungabangela ukuthi ama-polyester polyols aqine ekushiseni kwegumbi. Ngakho-ke, ama-polyester polyols ahlanzekile asekelwe ku-EG awavamile.

Ezakhiweni ezisebenzayo, i-EG ivame ukuhlanganiswa nalokhu:

ukulungisa ukwakheka kwekristali nokusebenza kokucubungula.

Inzuzo eyodwa ebalulekile ye-EG yile:

• ✔Izindleko eziphansi
• ✔Ukutholakala okubanzi

Ekukhiqizweni kwe-polyester polyol ngokusekelwe ezintweni ze-PET eziphinde zasetshenziswa, i-EG isalokhu iyinto eluhlaza ebalulekile.

I-Diethylene Glycol (DEG)

I-DEG ifaka izibopho ze-ether kuchungechunge lwe-polyester.

Ukuxhumana kwe-ether okuguquguqukayo kunikeza:

• •I-Tg engezansi
• •Ukuncipha kwe-viscosity
• •Ukusebenza kahle kokugeleza

Ama-polyester polyol asekelwe ku-DEG asetshenziswa kabanzi lapho ukucubungula ukuguquguquka kubalulekile.

Kodwa-ke, ama-ether bond angase abe nokumelana okuphansi ne-oxidation yokushisa yesikhathi eside. Ngakho-ke, izinhlelo ze-DEG zivame ukuhlanganiswa nama-diol azinzile kakhulu njenge-NPG.

I-Neopentyl Glycol (NPG)

I-NPG iqukethe isakhiwo sekhabhoni esi-quaternary esinamaqembu amabili e-methyl.

Lesi sakhiwo esiyingqayizivele sivimbela ukunyakaza kwama-molecule futhi sinikeza:

• •I-Tg Ephakeme
• •Ukuqina okuhle kakhulu kokushisa
• •Ukumelana nesimo sezulu okuphezulu
• •Ukumelana okuthuthukisiwe kwe-hydrolysis

Ngenxa yokuqina kwayo okuhle kakhulu, i-NPG isetshenziswa kabanzi ku:

• •Izembozo ze-PU
• •Izinhlelo zokusebenza zangaphandle
• •Izinhlelo ze-polyurethane ezingamelani nesimo sezulu

1,4-Butanediol (BDO)

I-1,4-Butanediol ingenye yama-diol abaluleke kakhulu asetshenziswa ku-polyurethane elastomer kanye ne-TPU.

Isakhiwo sayo esiqondile se-carbon ezine sinikeza:

• •Ukuhleleka okuhle kweketanga
• •Ukusebenzisana okunamandla phakathi kwamangqamuzana
• •Izakhiwo ezinhle kakhulu zemishini

Uma ihlanganiswe nama-aromatic acid njenge-PTA, i-BDO ingakha izingxenye zekristalu ezihlelwe kahle ezifana nezakhiwo ze-PBT.

Lokhu kunegalelo ku:

• ✔Amandla aphezulu okuqina
• ✔Ukumelana okungcono kokuklwebheka
• ✔Ukuxhumana okuthuthukisiwe ngokomzimba

Kodwa-ke, okuqukethwe okuphezulu kwe-BDO kungandisa ukuthambekela kokwakheka kwamakristalu, okubangela ukuthi ama-polyester polyol abe yi-wax noma aqine ekushiseni kwegumbi.

Ukuze kuthuthukiswe ukusebenza kokucubungula, i-BDO ivame ukuhlanganiswa nalokhu:

ukunciphisa ukwakheka kwamakristalu ngokweqile ngenkathi kugcinwa amandla okusebenza.

I-Trimethylolpropane (TMP): Ukwethula Ukuhlanganiswa Okulawulwayo

I-Trimethylolpropane (TMP) iwutshwala olunemisebenzi eminingi oluqukethe amaqembu amathathu e-hydroxyl. Ngokungafani nama-diol avamile, i-TMP ifaka izakhiwo ezihlanganisa amagatsha kuma-polyester polyols.

Inani elincane le-TMP linganda:

• •Ukuhlanganiswa kwama-molecule
• •Ubuningi be-Crosslink
• •Ubulukhuni bokugcina be-polyurethane

I-TMP ivame ukusetshenziswa lapho kuklanywa:

• •Izembozo ze-polyurethane ezisebenza kahle kakhulu
• •Izinhlelo ze-PU eziqinile
• •Ama-prepolymer e-polyurethane ahlanganisiwe

Ezimweni eziningi zokwenziwa, okuqukethwe kwe-TMP kulawulwa ngokucophelela ngoba ukwakheka kwamagatsha ngokweqile kungandisa kakhulu i-viscosity futhi kunciphise ukucutshungulwa.

3. Ungasilungisa Kanjani Isilinganiso Sotshwala-ne-Acid ku-Polyester Polyol Formulation?

Isilinganiso Esingaphezu Kotshwala

Ekuhlanganisweni kwe-polyester polyol, izingxenye zotshwala zivame ukusetshenziswa ngokweqile ukuze kufezwe izakhiwo eziqedwe yi-hydroxyl.

Kuma-polyester polyols anesisindo esiphansi sama-molecule, isilinganiso sokuphuza utshwala singandiswa sibe:1.8–2.0 : 1

Amanani aphezulu e-hydroxyl ahlinzeka ngamaqembu e-hydroxyl asabela kakhulu ekwakhekeni kwe-polyurethane.

Kodwa-ke, okuqukethwe utshwala ngokweqile kunganciphisa isisindo sama-molecule futhi kuthinte kabi:

Ngakho-ke, isilinganiso sotshwala-ku-asidi kumele sithuthukiswe ngokuya ngokusetshenziswa kokugcina kwe-polyurethane.

Ubudlelwano Phakathi Kwesilinganiso Sotshwala Nenani Le-asidi

Ngesikhathi sokwenziwa kwe-polyester polyol, amanzi akhiqizwayo asuswa njalo ukuze kuqhutshwe ukusabela kwe-esterification kanye nokujiya phambili.

Uma utshwala obuningi bunganele:

• •Ukuhlushwa kwe-asidi kuhlala kuphezulu
• •Ukusabela kuya ngokuya kuhamba kancane
• •Inani le-asidi lokugcina liba nzima ukulinciphisa

Inani eliphansi le-asidi libalulekile ngoba ama-residual acid angathinta ukusabela kwe-polyurethane. Lapho i-polyester polyol isabela nama-isocyanates, umswakama osele kanye nezingxenye ze-asidi kungabangela:

Kwezinhlelo zokusebenza eziningi ze-polyurethane, ukulawula inani le-asidi kungezansi:1 mg KOH/gkuyinhloso ebalulekile yekhwalithi.

4. Indlela YokukhethaAma-CatalystUkukhiqizwa kwePolyester Polyol?

Ukukhetha phakathi kwe-TBT ne-BTO kuncike ku:

5. Ukulawulwa Kwenqubo Yokukhiqiza iPolyester Polyol

Izigaba eziyinhloko zifaka:

1. Ukwenziwa kwe-esterification
2. Ukujiya kwe-Polycondensation
3. Inani le-Hydroxyl kanye nokulungiswa kwenani le-asidi

Isinyathelo 1: Isigaba Sokuqiniswa Kwe-Esterification

Ngesikhathi sesigaba sokwenziwa kwe-esterification, izinto ezilandelayo zishajwa ku-reactor:

Ukusabela kuvame ukuqala cishe ku:180°C

Amanzi akhiqizwa yi-esterification asuswa ngokusebenzisa:

• •Ukususwa kwe-nitrogen
• •Izinhlelo ze-Condenser

Inqubekela phambili yokusabela ingaqashwa ngokusebenzisa:

• •Inani lokuqoqwa kwamanzi
• •Ukuhlolwa kwenani le-asidi

Isinyathelo 2: Isigaba se-Polycondensation

Ngemva kokuqinisekiswa, uhlelo lungena esigabeni se-polycondensation.

Izimo ezijwayelekile:

• •Izinga lokushisa:200–220°C
• •Ukucindezela okuncishisiwe: ukusebenza kwe-vacuum

I-vacuum isiza ukususa amanzi asele kanye notshwala obuningi, okukhuthaza ukukhula kwama-molecule.

Kodwa-ke, izinga lokushisa elidlulele noma isikhathi eside sokusabela kungabangela ukusabela okungekuhle, ukwanda kombala, kanye nokuwohloka kwe-polymer. Ngakho-ke, izimo zenqubo kumele zilawulwe ngokucophelela.

Isinyathelo 3: Ukulawula Indawo Yokugcina

Ngokungafani ne-PET polymerization, ukukhiqizwa kwe-polyester polyol akudingi ukuthuthukiswa kwesisindo sama-molecule esiphezulu kakhulu. Izinkomba eziyinhloko zekhwalithi yilezi:

Umgomo ojwayelekile wezimboni:Inani le-asidi <1 mg KOH/gngaphambi kokukhishwa.

Ukungasebenzi kahle kwe-vacuum kungenye yezizathu ezinkulu zalokhu:

• ✖Umswakama osele kakhulu
• ✖Inani eliphezulu le-asidi
• ✖Ukusebenza kabi kwe-polyurethane

6. Isifinyezo Somklamo wePolyester Polyol

Isici Sokuklama	Izinguquko Eziyinhloko	Isimiso Sokukhetha	Ibanga Elijwayelekile
Ukuqina komgogodla	I-IPA, i-PTA, i-AA, i-SA	Ama-asidi anuka kamnandi athuthukisa ukuqina; ama-asidi e-aliphatic athuthukisa ukuguquguquka	I-IPA/AA ≈ 7:3
Ukulungiswa kwe-Tg	I-EG, i-DEG, i-NPG, i-BDO	I-EG ikhulisa ubukhristalo; i-DEG inciphisa ubukhristalo; i-NPG ithuthukisa ukuqina; i-BDO ithuthukisa amandla	Kususelwa kuhlelo lokusebenza
Ukulawula isisindo sama-molecule	Isilinganiso sotshwala ne-asidi	Ukweqisa utshwala kudala izakhiwo eziqedwe yi-hydroxyl	Utshwala/I-asidi = 1.3
Ukukhetha kwe-Catalyst	I-TBT vs BTO	I-TBT yokusabela okusheshayo; i-BTO yokuqina okungcono kwe-hydrolysis	I-BTO 0.2–0.5‰
Ukulawula amagatsha	I-TMP/Glycerol	Izengezo ezincane zithuthukisa ubuningi be-crosslink	I-TMP ≤3 mol%

7. Umklamo wePolyester Polyol Uthinta Kanjani Ukusebenza kwePolyurethane?

Isicelo	Umklamo wePolyester Polyol onconyiwe
Izinamathiseli ze-PU	Ama-polyol e-polyester asekelwe ku-AA aguquguqukayo ukuze anamathele futhi abe lukhuni
Izembozo ze-PU	Izinhlelo ze-IPA/NPG zokuqina nokumelana nesimo sezulu
Ama-TPU Elastomers	Izinhlelo ze-AA + BDO zamandla okusebenza kanye nokumelana nokuguguleka
I-PU Eqhutshwa Ngamanzi	Ama-polyester polyols amelana ne-hydrolysis anezinhlelo ze-catalyst ezilungiselelwe kahle
Isikhumba Esihlanganisiwe	Ama-polyester polyols aguquguqukayo anobumnene obulawulwayo

Izidingo zohlelo lokusebenza → Izinhloso zokusebenza → Ukukhethwa kwe-Monomer → Ukwakheka kwesakhiwo sama-molecule → Ukukhethwa kwe-Catalyst → Ukulungiswa kwenqubo