Txheej txheem cej luam ntawm daim ntawv thov ntawmcov neeg sawv cev amino resin crosslinking
Lub luag haujlwm tseem ceeb ntawm cov amino resins (melamine-formaldehyde, benzomelamine-formaldehyde, thiab urea-formaldehyde resins) hauv cov txheej txheem thermosetting yog los txuas cov khoom siv tseem ceeb ntawm zaj duab xis mus rau hauv cov qauv network peb-seem los ntawm cov tshuaj tiv thaiv. Cov qauv network no tau txais los ntawm kev tiv thaiv ntawm cov amino resin molecules nrog cov pab pawg ua haujlwm ntawm cov khoom siv zaj duab xis, thiab tib lub sijhawm los ntawm kev sib xyaw polymerization nrog lwm cov amino resin molecules. Amino resins yooj yim tiv thaiv nrog cov polymers uas muaj cov pab pawg hydroxyl thawj thiab theem nrab, cov pab pawg carboxyl, thiab cov pab pawg amide; yog li ntawd, cov amino resins feem ntau siv rau hauv cov txheej txheem pleev xim raws li acrylic, polyester, alkyd, lossis epoxy resins.
Cov amino resins kuj tseem siv rau hauv cov polyurethane systems ua cov tshuaj ntxiv rau txheej kom txhim kho kev ua tau zoo ntawm cov txheej rau qee yam kev siv.
Lub hauv paus ntsiab lus ntawm cov amino resins:
Qhov tseem ceeb ntawm cov amino resins hauv cov varnishes ci ntau dua li lawv qhov sib piv hauv cov txheej txheej. Kev nkag siab txog yuav ua li cas siv cov khoom siv tshuaj lom neeg ntawm cov amino resins hauv kev tsim cov txheej txheem txheej txheem tau dhau los ua qhov tseem ceeb dua. Piv txwv li,Yog tias cov neeg tsim cov txheej txheem tsis txaus siab rau qee yam khoom ntawm cov zaj duab xis txheej, lawv tuaj yeem kho lawv siv cov txheej txheem hauv qab no:
1. Kev txhim kho lossis kev xaiv dua ntawm cov yas ua zaj duab xis nws tus kheej;
2. Kev xaiv cov amino resins (methyl etherification lossis butyl etherification, thiab kev xaiv ntawm qib ntawm etherification, thiab lwm yam);
3. Qhov piv ntawm cov yas ua zaj duab xis rau cov amino resin.
4. Kev xaiv cov tshuaj catalyst (seb puas yuav ntxiv nws lossis tsis ntxiv, thiab yuav ntxiv ntau npaum li cas).
Tag nrho plaub lub ntsiab lus saum toj no, tshwj tsis yog thawj qhov,muaj feem cuam tshuam nrog cov amino resins. Cov khoom ntawm cov amino resins nyob ntawm lawv cov pab pawg ua haujlwm thiab lawv cov haujlwm; yog li ntawd, kev nkag siab txog cov qauv ntawm cov amino resins yog qhov tseem ceeb heev. Txawm li cas los xij, ua ntej nkag siab txog cov amino resins, nws yog ib qho tseem ceeb kom muaj kev nkag siab yooj yim txog cov resins uas siv ua ke nrog lawv.
Raws li tau hais ua ntej lawm, cov amino resins feem ntau yogsiv ua ke nrog alkyd resins, acrylic resins, polyester resins, thiab epoxy resins. Cov tshuaj alkyd feem ntau yog tsim los ntawm polyols thiab polyacid resins los ntawm esterification. Thaum lub sijhawm tsim cov cawv, feem ntau muaj ntau dhau; qee pawg carboxyl ntawm cov polyacids yuav tsis teb tag nrho, ua rau cov tshuaj alkyd muaj qee qhov ntawm cov carboxyl thiab hydroxyl pawg. Tus nqi ntawm cov carboxyl thiab hydroxyl pawg feem ntau yog tus cwj pwm los ntawm cov nqi acid thiab tus nqi hydroxyl. Tus nqi acid hais txog tus lej ntawm milligrams ntawm KOH xav tau los neutralize 1g ntawm cov khoom siv resin los ntawm titration nrog KOH. Tus nqi Hydroxyl hais txog tus lej ntawm milligrams ntawm KOH xav tau los neutralize tag nrho cov pawg OH hauv 1g ntawm cov khoom siv resin los ntawm titration nrog KOH. Ib yam li ntawd, polyester resins, acrylic resins, thiab amino resins kuj muaj qee qhov ntawm cov carboxyl thiab hydroxyl pawg. Qhov sib txawv nyob rau hauv cov ntaub ntawv raw siv los synthesize cov resins; piv txwv li, cov pawg carboxyl hauv acrylic resins los ntawm acrylic acid, thiab cov pawg hydroxyl los ntawm hydroxyacrylic acid. Cov nqi ntawm cov carboxyl thiab hydroxyl pawg hauv cov amino resins kuj txawv. Tus nqi acid, tus nqi hydroxyl, thiab viscosity yog cov cim qhia tseem ceeb ntawm cov resins, uas cuam tshuam ncaj qha rau lawv cov kev ua tau zoo.
Rov qab mus rau lub ncauj lus ntawm cov amino resins, cia peb xub saib lawv cov qauv:
Daim Duab 1:
Daim Duab 2
Daim Duab 1 qhia txog cov amino resin uas muaj cov alkoxy, imino, thiab hydroxymethyl pawg. Yog tias peb xav txog lub nplhaib uas muaj rau tus tswv cuab uas tsim los ntawm cov pa roj carbon thiab nitrogen atoms ua ib lub pob txha, cov ceg lossis cov qauv uas tau los ntawm nws tuaj yeem piav qhia ua piv txwv tias muaj peb lub taub hau thiab rau caj npab. Qhov sib txawv ntawm cov yam ntxwv ntawm cov amino resins yog vim qhov sib txawv ntawm rau "caj npab" no thiab lawv cov kev npaj thiab kev sib xyaw ua ke.
Daim Duab 2 qhia txog cov qauv HMMM uas sib xws heev, piv txwv li, cov amino resin uas muaj methylated tag nrho, nrog tsuas yog ib pawg ua haujlwm: methoxy pawg, uas yog idealized. Vim tias qib ntawm etherification tsis tuaj yeem ncav cuag 1: 6 (qhov siab tshaj plaws) hauv kev tsim khoom tiag tiag, qhov hu ua methylated tag nrho amino resin yuav ib txwm muaj qee pawg imino thiab hydroxymethyl.
Cia peb pib los ntawm kev nkag siab txog cov ntsiab cai ntawm cov amino resins kom paub txog lawv cov khoom:
Kauj ruam thawj zaug hauv kev tsim cov resin yog los ua kom melamine nrog formaldehyde nyob rau hauv qhov muaj cov catalyst los tsim polyhydroxymethyl melamine. Tag nrho cov hydrogen atoms nquag ntawm lub nplhaib triazine tuaj yeem hloov pauv mus rau hydroxymethyl pawg, tab sis qhov tseeb, nws yog 2 txog 6 moles ntawm formaldehyde uas ua rau lub nplhaib triazine. Cov hydrogen atoms nquag uas tsis tau ua haujlwm seem yog sawv cev los ntawm imino pawg. Raws li peb yuav pom tom qab, cov pab pawg no ua lub luag haujlwm tseem ceeb hauv cov txheej txheem kho los ntawm kev sib xyaw ua ke ntawm tus kheej.
Polyhydroxymethyl melamine tsis ruaj khov heev thiab muaj kev yaj tsawg hauv cov tshuaj yaj ib txwm muaj. Cov amino resins feem ntau ua haujlwm ua cov neeg sawv cev sib txuas thiab kho hauv cov txheej txheej. Txhawm rau tsim cov neeg sawv cev sib txuas rau cov txheej txheej, pawg hydroxymethyl feem ntau yog etherified nrog cov cawv luv luv kom txo nws cov tshuaj tiv thaiv thiab txhim kho nws qhov sib xws nrog cov ntaub ntawv tsim cov yeeb yaj kiab ib txwm muaj thiab cov kuab tshuaj aliphatic. Methanol thiab butanol feem ntau yog siv ua cov cawv luv luv. Los ntawm kev tswj cov nyiaj ntawm methanol lossis butanol ntxiv thiab lwm yam mob, cov amino resins nrog ntau qib ntawm etherification tuaj yeem tau txais.
Tsuas yog cov chaw uas tau ua tshuaj nrog formaldehyde (hydroxymethyl pawg) thiaj li tuaj yeem kaw nrog cov cawv; cov hydrogen atoms tsis tau ua tshuaj (imino pawg) tsis ua tshuaj nrog cov cawv luv luv. Ntxiv mus, qhov kev ua tshuaj no qhia tau hais tias tag nrho rau pawg hydroxymethyl ua tshuaj nrog cov cawv los tsim hexaalkoxymethyl melamine, txhais tau hais tias qhov kev ua tshuaj ntawm ib mus rau rau pawg hydroxymethyl nrog cov cawv tuaj yeem tswj tau. Qhov no yog vim li cas peb thiaj muaj ntau hom amino resins sib txawv.
Kev ua polymerization tus kheej cov amino resins :
Qhov hnyav molecular ntawm cov amino resins yog txiav txim siab los ntawm qib ntawm kev sib sau ua ke lossiskev sib txuasntawm cov pab pawg ua haujlwm (imino, hydroxymethyl, alkoxymethyl) ntawm lub nplhaib triazine thiab melamine molecules. Hauv kev siv kawg, qib ntawm kev sib txuas polymerization cuam tshuam rau qhov hnyav molecular ntawm cov amino resin thiab kev ua tau zoo ntawm cov zaj duab xis txheej.
Cov tshuaj tiv thaiv tus kheej ntawm cov amino resins tuaj yeem tshwm sim los ntawm txoj hauv kev hauv qab no:
Daim Duab 3:
Cov tshuaj tiv thaiv ntawm sab laug tsim ib lub choj methylene, thaum cov tshuaj tiv thaiv ntawm sab xis tsim ib lub choj methylene ether. Qib ntawm kev sib txuas hauv cov amino resins feem ntau yog qhia ua qib ntawm polymerization (DP): DP = qhov hnyav molecular / qhov hnyav ntawm txhua lub nplhaib triazine. Cov amino resins thaum ntxov feem ntau yog tus kheej-polymerizing, nrog DP> 3.0. Kev nce qib thev naus laus zis tau ua rau nws muaj peev xwm txo qis tus kheej-condensation hauv cov amino resins tiav lawm. Tam sim no, melamine resins muaj nyob hauv khw muaj DPs qis li 1.1.
Qhov cuam tshuam tseem ceeb ntawm qhov hnyav molecular ntawm amino resin yog pom tseeb hauv qhov viscosity ntawm txheej. Melamine resins nrog DP > 2.0 yuav tsum tau diluted nrog cov kuab tshuaj rau 50% –80% cov khoom khov kom ua tiav qhov viscosity siv tau. Monomer-hom melamine resins nrog DP ntawm 1.1 thiab 1.5 feem ntau yog muab rau hauv 100% cov khoom khov zoo; cov kuab tshuaj ntxiv muaj qhov cuam tshuam tseem ceeb rau VOCs ntawm cov txheej tiav. Qhov hnyav molecular ntawm amino resins kuj cuam tshuam rau cov tshuaj kho txheej thiab cov khoom zaj duab xis. Lub kaw lus txheej siv cov amino resin siab-DP yuav ncav cuag qhov ceev crosslinking teev tseg hauv lub sijhawm luv dua li lub kaw lus txheej siv cov amino resin nrog tib lub qauv tab sis DP qis dua. Yog li ntawd, cov txheej uas muaj cov neeg sawv cev crosslinking siab-DP xav tau tsawg dua catalyst lossis cov kua qaub qis dua catalyst kom ua tiav tib lub xeev kho. Qhov cuam tshuam ntawm qhov hnyav molecular ntawm cov khoom zaj duab xis feem ntau yog nyob rau hauv qhov ntau yam yooj ywm. Cov txheej kho nrog cov amino resins siab-DP muaj feem pua ntau dua ntawm cov amino-amino bonds thiab tsawg dua amino-lacquer bonds. Hom kev sib txuas ntawm cov qauv network no tsim ib txheej uas muaj qhov tawv zoo tab sis tej zaum yuav tawg yooj yim. Qhov no qee zaum tuaj yeem them rov qab los ntawm kev xaiv cov xim pleev xim uas yooj ywm dua. Txawm li cas los xij, cov ntawv thov uas xav tau cov txheej txheej uas yooj ywm heev feem ntau xav tau cov monomeric amino resins.
Cov polyesters uas muaj cov carboxyl pawg tuaj yeem ua rau muaj kev cuam tshuam nrog melamine-formaldehyde los tsim cov txheej txheem thermosetting surface uas muaj txiaj ntsig zoo nrog ntau yam khoom siv lub cev.
Ntau cov butylated melamine-formaldehyde resins muaj peev xwm ua lag luam tau, feem ntau yog vim muaj qhov sib txawv ntawm qib pib ntawm polymerization (qhov hnyav molecular) thiab qhov sib piv ntawm alkoxy pawg rau cov uas tsis muaj hydroxymethyl pawg thiab amino hydrogens. Cov kev sib txawv no cuam tshuam rau cov kua viscosity, qhov sib xws ntawm melamine nrog polyester, thiab qhov ceev ntawm cov enamel. Cov melamine resins ib txwm muaj, ua rau muaj kev cuam tshuam nrog cov pab pawg hydroxyl sab, feem ntau yog crosslink nrog cov polyester molecules. Txij li thaum qhov kev cuam tshuam crosslinking yog acid-catalyzed, ntawm qhov kub kho ntawm 120 ° C thiab 150 ° C, cov kua qaub muaj zog feem ntau cuam tshuam rau qhov kev cuam tshuam crosslinking ntawm polyester resins; txawm li cas los xij, qee cov polyesters xav tau cov kua qaub ntxiv catalysis hauv cov kua qaub tsis muaj zog heev los kho cov txheej txheem enamel.
Muaj cov xwm txheej hauv qab no: Ntxiv rau qhov kev sib txuas ntawm melamine-polyester, butylated melamine-formaldehyde resin kuj dhau los ua qhov kev sib txuas ntawm tus kheej. Ntawd yog, cov amino resin dhau los ua tus kheej-crosslinking los tsim cov qauv melamine network. Qhov kev sib txuas no tshwm sim tib lub sijhawm nrog cov kev sib txuas ntawm melamine-polyester thiab yog qhov kev sib tw sib tw. Qhov laj thawj rau qhov kev sib txuas no yog tias, ntxiv rau cov pab pawg butoxy, butylated melamine-formaldehyde resin kuj muaj cov hydrocarbon methyl pawg dawb thiab hydrogen los ntawm imino pawg, txhua tus tuaj yeem sib cuam tshuam nrog ib leeg. Thaum cov amino resin dhau los ua tus kheej-crosslinking, nws yuav poob qee qhov ntawm nws cov haujlwm.
Txawm hais tias kev sib txuas tus kheej feem ntau ua rau cov txheej txheem tawv dua thiab tiv taus tshuaj lom neeg, nws ua rau poob qhov elasticity tseem ceeb. Yuav kom ua tiav qhov elasticity txaus hauv cov varnishes polyester...
Hexamethoxymethyl melamine (HMMM) yog ib qho hydroxymethylated thiab methylated monomeric amino resin. Zoo ib yam li butylated melamine-formaldehyde, nws dhau los ntawm kev sib txuas nrog cov hydroxyl pawg ntawm polyester resin thaum cua sov, tsim cov khoom tsis mos. Yeej, tsis muaj cov tshuaj catalyst acid, HMMM yuav tsis dhau los ntawm kev sib txuas tus kheej txawm tias ntev lossis kub ntxiv. Txawm li cas los xij, bulk HMMM yuav dhau los ntawm kev sib txuas tus kheej ntawm 150 ° C nyob rau hauv qhov muaj cov tshuaj catalyst acid muaj zog. Ntawm qhov tod tes, txawm tias tsis muaj cov kua qaub muaj zog, cov tshuaj butylated melamine thiab urea resins ib txwm yuav dhau los ntawm kev sib txuas tus kheej muaj zog nrog qhov kub nce ntxiv.
Kev kho cov tshuaj tiv thaiv ntawm cov amino resins:
Vim tias cov amino resins siv los txuas cov khoom siv tseem ceeb rau hauv cov qauv network, qhov kev sib xyaw ua ke ntawm cov amino resins nrog cov xim pleev xim yog qhov txaus siab heev. Ib qho piv txwv zoo yog qhov kev sib pauv etherification (kev sib pauv)ntawm cov pab pawg hydroxyl ntawm cov xim pleev xim thiab cov pab pawg alkoxymethyl ntawm cov amino resins.
Nyob rau hauv cov xwm txheej ntawm cua sov thiab acid catalysts (feem ntau yog cov xwm txheej kho), crosslinking tshwm sim sai sai, txuas txhua pawg hydroxyl muaj nyob rau ntawm cov xim. Qhov tseeb, thaum cov qauv network polymer tsim, qhov fluidity ntawm cov reactants txo qis, tawm hauv qee pawg hydroxyl tsis muaj kev cuam tshuam. Feem ntau, thaum muaj ntau dhau ntawm amino resin nyob rau hauv lub txheej piv rau qhov piv zoo tagnrho, cov pab pawg alkoxy seem tuaj yeem koom nrog lwm cov tshuaj tiv thaiv lossis tseem tsis muaj kev cuam tshuam hauv zaj duab xis txheej. Raws li tau hais ua ntej, amino resins yooj yim tus kheej-crosslink thiab cuam tshuam nrog ib leeg, ua rau muaj kev nce hauv molecular hnyav thaum lub sijhawm tsim khoom. Cov tshuaj tiv thaiv no kuj tshwm sim thaum lub sijhawm txheej kho. Yog li, es tsis txhob yog qhov tsis zoo, qee qib ntawm tus kheej-crosslinking ntawm amino resins yog qhov tseem ceeb rau kev tau txais cov khoom siv polymer matrix zoo-ruaj khov, ntim nruj. Tag nrho peb pawg ua haujlwm ntawm amino resins koom nrog tus kheej-crosslinking tshuaj tiv thaiv, thiab hauv cov txheej txheem alkylated melamine resin tag nrho catalyzed los ntawm cov kua qaub muaj zog, muaj pov thawj tias cov tshuaj tiv thaiv no tshwm sim tom qab ether pauv nrog cov txheej txheem txheej. Yog tsis muaj cov tshuaj catalysts sab nraud lossis cov tshuaj catalysts kua qaub tsis muaj zog, cov kev sib txuas ntawm tus kheej no tshwm sim ntau dua hauv cov kab ke melamine resin nrog cov haujlwm siab imino / lossis hydroxymethyl. Hauv ob qho tib si, qhov kev sib txuas me ntsis ntawm tus kheej yog qhov tseem ceeb rau kev tsim cov qauv network zoo.
Thaum lub sijhawm kho cov amino resin crosslinked coatings, lwm yam kev cuam tshuam uas tshwm sim yog formaldehyde tshem tawm thiab hydrolysis. Formaldehyde tshem tawm tshwm sim yooj yim ntawm qhov kub kho ib txwm, uas yuav luag yog tib qho laj thawj rau kev tso tawm ntawm formaldehyde thaum lub sijhawm kho cov amino resins; lwm yam formaldehyde yog formaldehyde dawb.
Thaum cov amino resins sib txuas ua cov yeeb yaj kiab thiab kho, qee qhov kev hloov pauv hydrolysis tshwm sim. Thaum lub sijhawm no, qee cov pab pawg alkoxymethyl raug hloov mus rau hydroxymethyl pawg. Kev hydrolysis ntawm melamine resins nrog cov ntsiab lus imino lossis hydroxymethyl siab tuaj yeem catalyzed los ntawm alkalis, thiab tuaj yeem tshwm sim qeeb ntawm chav tsev kub. Qhov no ua rau amino resins yooj yim rau kev sib txuas tus kheej, ua rau muaj kev nce ntxiv ntawm viscosity ntawm lub txheej thaum lub sijhawm khaws cia. Txhawm rau kom tsis txhob muaj qhov no, cov methylated melamine resins lossis cov co-solvents uas tiv taus alkali hydrolysis tuaj yeem siv rau hauv cov txheej txheem dej. Cov melamine resins alkylated tag nrho yog tiv taus alkali-catalyzed hydrolysis hauv cov txheej txheem dej. Cov melamine resins alkylated tag nrho thiab ib nrab alkylated tsis tiv taus acid-catalyzed hydrolysis hauv cov txheej txheem dej; yog li ntawd, yuav tsum siv cov tshuaj catalyst acid uas raug thaiv hauv cov txheej txheem dej.
Yog koj xav paub ntxivtus neeg sawv cev sib txuascov khoom lag luam, xav tiv tauj peb.
Lub sijhawm tshaj tawm: Lub Kaum Ob Hlis-19-2025