Chidule cha kugwiritsa ntchitoothandizira olumikizirana a amino resin
Ntchito yaikulu ya ma amino resins (melamine-formaldehyde, benzomelamine-formaldehyde, ndi urea-formaldehyde resins) mu zophimba za thermosetting ndikulumikiza mamolekyulu akuluakulu opanga filimu kukhala kapangidwe ka netiweki ya magawo atatu kudzera mu zochita za mankhwala. Kapangidwe ka netiweki kameneka kamapezeka kudzera mu momwe mamolekyulu a amino resins amachitira ndi magulu ogwira ntchito pamamolekyulu opanga filimu, komanso nthawi imodzi kudzera mu condensation polymerization ndi mamolekyulu ena a amino resins. Ma amino resins amakumana mosavuta ndi ma polima okhala ndi magulu oyambira ndi achiwiri a hydroxyl, magulu a carboxyl, ndi magulu a amide; chifukwa chake, ma amino resins amagwiritsidwa ntchito kwambiri mumakina opaka utoto kutengera ma acrylic, polyester, alkyd, kapena epoxy resins.
Ma resini a amino amagwiritsidwanso ntchito mu makina a polyurethane ngati zowonjezera pakuphimba kuti ziwongolere magwiridwe antchito onse a zokutira pazinthu zina.
Mfundo ya ma amino resins:
Kufunika kwa ma amino resins mu ma varnish ophikira kumaposa kwambiri kuchuluka kwawo mu zokutira. Kumvetsetsa momwe mungagwiritsire ntchito mankhwala a ma amino resins pakupanga mapangidwe a zokutira kukukulirakulira. Mwachitsanzo,Ngati opanga utoto sakukhutira ndi zinthu zina za filimu yophimba utoto, akhoza kuwasintha pogwiritsa ntchito njira zotsatirazi:
1. Kukonza kapena kusankhanso utomoni wopangira filimuyo;
2. Kusankha ma amino resins (methyl etherification kapena butyl etherification, ndi kusankha mlingo wa etherification, ndi zina zotero);
3. Chiŵerengero cha utomoni wopanga filimu ndi utomoni wa amino.
4. Kusankha Catalyst (kaya muwonjezere kapena ayi, ndi kuchuluka kwa kuwonjezera).
Mfundo zonse zinayi zomwe zili pamwambapa, kupatula yoyamba,Ma amino resin amagwirizana ndi ma amino resin. Kapangidwe ka ma amino resin kamadalira magulu awo ogwira ntchito komanso ntchito zawo.Chifukwa chake, kumvetsetsa kapangidwe ka ma amino resin ndikofunikira kwambiri. Komabe, musanamvetse ma amino resin, ndikofunikira kumvetsetsa bwino ma amino resin omwe amagwiritsidwa ntchito limodzi nawo.
Monga tanenera kale, ma amino resins nthawi zambiri amakhala ndi zinthu zambiri.amagwiritsidwa ntchito pamodzi ndi ma resins a alkyd, ma resins a acrylic, ma resins a polyester, ndi ma resins a epoxy.Ma resin a alkyd amapangidwa makamaka kuchokera ku ma polyol ndi ma polyacid resins kudzera mu esterification. Pakapangidwa, ma alcohols nthawi zambiri amakhala ochulukirapo; magulu ena a carboxyl a ma polyacid sangagwire ntchito mokwanira, zomwe zimapangitsa kuti ma alkyd resins akhale ndi kuchuluka kwa magulu a carboxyl ndi hydroxyl. Kuchuluka kwa magulu a carboxyl ndi hydroxyl nthawi zambiri kumadziwika ndi kuchuluka kwa asidi ndi hydroxyl. Kuchuluka kwa asidi kumatanthauza kuchuluka kwa ma milligram a KOH omwe amafunikira kuti athetse 1g ya utomoni wolimba pogwiritsa ntchito titration ndi KOH. Kuchuluka kwa hydroxyl kumatanthauza kuchuluka kwa ma milligram a KOH omwe amafunikira kuti athetse kwathunthu magulu a OH mu 1g ya utomoni wolimba pogwiritsa ntchito titration ndi KOH. Mofananamo, ma polyester resins, ma acrylic resins, ndi ma amino resins alinso ndi kuchuluka kwa magulu a carboxyl ndi hydroxyl. Kusiyana kuli mu zipangizo zopangira zomwe zimagwiritsidwa ntchito popanga ma resin; mwachitsanzo, magulu a carboxyl mu ma acrylic resins amachokera ku acrylic acid, ndipo magulu a hydroxyl amachokera ku hydroxyacrylic acid. Kuchuluka kwa magulu a carboxyl ndi hydroxyl mu ma amino resins kumasiyananso. Kuchuluka kwa asidi, kuchuluka kwa hydroxyl, ndi kukhuthala zonse ndi zizindikiro zofunika kwambiri za ma resins, zomwe zimakhudza mwachindunji magwiridwe antchito awo.
Tikabwerera ku nkhani ya ma amino resins, choyamba tiyeni tiwone kapangidwe kake:
Chithunzi 1:
Chithunzi 2
Chithunzi 1 chikuwonetsa utomoni wa amino womwe uli ndi alkylated pang'ono wokhala ndi magulu a alkoxy, imino, ndi hydroxymethyl. Ngati tiganizira mphete yokhala ndi ziwalo zisanu ndi chimodzi yopangidwa ndi maatomu a kaboni ndi nayitrogeni ngati chigoba, nthambi kapena kapangidwe kake kochokera pamenepo kangathe kufotokozedwa mophiphiritsa kuti kali ndi mitu itatu ndi manja asanu ndi limodzi. Kusiyana kwakukulu kwa makhalidwe a utomoni wa amino kumachitika chifukwa cha kusiyana kwa "manja" asanu ndi limodzi awa ndi kapangidwe kawo kovuta komanso kuphatikiza kwawo.
Chithunzi 2 chikuwonetsa kapangidwe ka HMMM kofanana kwambiri, mwachitsanzo, amino resin yokhala ndi methylation yonse, yokhala ndi gulu limodzi lokha logwira ntchito: gulu la methoxy, lomwe ndi labwino kwambiri. Popeza kuchuluka kwa etherification sikungafikire 1:6 (yapamwamba kwambiri) pakupanga kwenikweni, chomwe chimatchedwa fully methylated amino resin nthawi zonse chimakhala ndi magulu ena a imino ndi hydroxymethyl.
Tiyeni tiyambe ndi kumvetsetsa mfundo za ma amino resins kuti tidziwe za makhalidwe awo:
Gawo loyamba popanga utomoni ndikuchita zinthu mogwirizana ndi melamine ndi formaldehyde pamaso pa chothandizira kupanga polyhydroxymethyl melamine. Ma atomu onse a haidrojeni omwe amagwira ntchito pa mphete ya triazine amatha kusinthidwa kukhala magulu a hydroxymethyl, koma kwenikweni, ndi ma mole awiri mpaka asanu ndi limodzi a formaldehyde omwe amachita zinthu mogwirizana ndi mphete ya triazine. Ma atomu otsala a haidrojeni omwe sanagwire ntchito amaimiridwa ndi magulu a imino. Monga momwe tidzaonera mtsogolo, magulu awa amachita gawo lofunikira pakupanga zinthu kudzera mu polymerization yodzipangira yokha.
Polyhydroxymethyl melamine ndi yosakhazikika kwambiri ndipo imatha kusungunuka pang'ono mu zosungunulira zachikhalidwe. Ma resini a amino amagwira ntchito makamaka ngati zolumikizira ndi zophikira mu zophimba. Kuti apange cholumikizira choyenera cha zophimba, gulu la hydroxymethyl nthawi zambiri limatenthedwa ndi mowa waufupi kuti lichepetse kuyanjana kwake ndikuwongolera kuyanjana kwake ndi zinthu zopanga filimu zachikhalidwe komanso zosungunulira za aliphatic. Methanol ndi butanol nthawi zambiri zimagwiritsidwa ntchito ngati ma alcohols afupi. Mwa kuwongolera kuchuluka kwa methanol kapena butanol yomwe yawonjezeredwa ndi zina, ma resini a amino okhala ndi madigiri osiyanasiyana a etherification angapezeke.
Malo okhawo omwe achitapo kanthu ndi formaldehyde (magulu a hydroxymethyl) ndi omwe angatsekedwe ndi ma alcohols; ma atomu a hydrogen osachitapo kanthu (magulu a imino) sachitapo kanthu ndi ma alcohols afupiafupi. Kuphatikiza apo, izi zikusonyeza kuti magulu onse asanu ndi limodzi a hydroxymethyl amachitapo kanthu ndi ma alcohols kuti apange hexaalkoxymethyl melamine, zomwe zikutanthauza kuti momwe magulu amodzi mpaka asanu ndi limodzi a hydroxymethyl amachitira ndi ma alcohols zimatha kulamulidwa. Ichi ndichifukwa chake tili ndi mitundu yosiyanasiyana ya ma amino resins.
Kudzipangira polima ma amino resins :
Kulemera kwa mamolekyu a ma amino resins kumatsimikiziridwa ndi kuchuluka kwa kudzipanga komwe kumadziunjikira kapenakulumikizapakati pa magulu ogwira ntchito (imino, hydroxymethyl, alkoxymethyl) pa mphete ya triazine ndi mamolekyu a melamine. Pomaliza, kuchuluka kwa polymerization yolumikizana kumakhudza kwambiri kulemera kwa mamolekyu a amino resin ndi magwiridwe antchito a filimu yophimba.
Kudzipangira kwa ma amino resins kumatha kuchitika kudzera munjira iyi:
Chithunzi 3:
Kuyankha kumanzere kumapanga mlatho wa methylene, pomwe kuchitapo kanthu kumanja kumapanga mlatho wa methylene ether. Mlingo wa kulumikizana mu ma amino resins nthawi zambiri umafotokozedwa ngati mlingo wa polymerization (DP): DP = kulemera kwa molekyulu / kulemera kwa mphete iliyonse ya triazine. Ma amino resins oyambirira anali kudzipanga okha, ndi DP > 3.0. Kupita patsogolo kwaukadaulo kwapangitsa kuti zikhale zotheka kuchepetsa kudzipanga okha mu ma amino resins omalizidwa. Pakadali pano, ma melamine resins omwe amapezeka m'masitolo ali ndi ma DP otsika ngati 1.1.
Kuchuluka kwa kulemera kwa amino resin kumaonekera mu kukhuthala kwa utoto. Ma resini a Melamine okhala ndi DP > 2.0 ayenera kuchepetsedwa ndi solvent mpaka 50%–80% ya zinthu zolimba kuti akwaniritse kukhuthala koyenera. Ma resini a melamine amtundu wa Monomer okhala ndi DP pakati pa 1.1 ndi 1.5 nthawi zambiri amaperekedwa mu mawonekedwe a zinthu zolimba 100%; zinthu zina zowonjezera zimakhudza kwambiri ma VOC a utoto womalizidwa. Kulemera kwa ma amino resin kumakhudzanso momwe ma amino resin amagwirira ntchito komanso mawonekedwe a filimu. Dongosolo lophimba lomwe limagwiritsa ntchito high-DP amino resin lidzafika pamlingo wolumikizana womwe watchulidwa munthawi yochepa kuposa dongosolo lophimba lomwe limagwiritsa ntchito amino resin yokhala ndi kapangidwe komweko koma DP yotsika. Chifukwa chake, zophimba zomwe zili ndi zinthu zolumikizira za high-DP zimafuna chothandizira chochepa kapena chothandizira chofooka cha asidi kuti zikwaniritse momwe zimakhalira. Zotsatira za kulemera kwa ma molekyulu pa zinthu za filimu zimakhala makamaka mu kuchuluka kosinthasintha. Zophimba zomwe zimachiritsidwa ndi ma amino resin okhala ndi high-DP zimakhala ndi kuchuluka kwakukulu kwa ma amino-amino bond ndi ma amino-lacquer bond ochepa. Mtundu uwu wa kapangidwe ka netiweki yolumikizirana umapanga chophimba chokhala ndi kuuma bwino koma chingakhale chofooka. Izi nthawi zina zimatha kulipidwa posankha utomoni wofewa kwambiri. Komabe, kugwiritsa ntchito komwe kumafuna chophimba chofewa kwambiri nthawi zambiri kumafuna ma monomeric amino resins.
Ma polyester okhala ndi magulu a carboxyl amatha kuchitapo kanthu ndi melamine-formaldehyde kuti apange zokutira zothandiza pa thermosetting pamwamba zomwe zimakhala ndi zinthu zosiyanasiyana zakuthupi.
Ma resini ambiri a melamine-formaldehyde okhala ndi butyl amapezeka pamsika, makamaka chifukwa cha kusiyana kwa kuchuluka kwa polymerization koyambirira (kulemera kwa mamolekyulu) ndi chiŵerengero cha magulu a alkoxy ndi omwe alibe magulu a hydroxymethyl ndi amino hydrogens. Kusiyana kumeneku kumakhudza kukhuthala kwamadzimadzi, kugwirizana kwa melamine ndi polyester, komanso liwiro la kuchira kwa enamel. Ma resini achikhalidwe a melamine, omwe amachita ndi magulu a hydroxyl, makamaka amalumikizana ndi mamolekyu a polyester. Popeza kuti crosslinking reaction imayambitsidwa ndi acid, kutentha kwapakati pa 120°C ndi 150°C, ma asidi amphamvu nthawi zambiri amakhudza crosslinking reaction ya ma resini a polyester; komabe, ma polyester ena amafunikira acid catalysis yowonjezera mu ma acid ofooka kwambiri kuti achiritse dongosolo la enamel.
Chochitika chotsatirachi chilipo: Kuwonjezera pa njira yolumikizirana ya melamine-polyester, resin ya melamine-formaldehyde yokhala ndi butylated imadziphatikizanso yokha. Izi zikutanthauza kuti, amino resin imadziphatikiza yokha kuti ipange kapangidwe ka netiweki ya melamine. Izi zimachitika nthawi imodzi ndi njira ya melamine-polyester ndipo ndi njira yopikisana. Chifukwa cha izi ndikuti, kuwonjezera pa magulu a butoxy, resin ya melamine-formaldehyde yokhala ndi butylated imakhalanso ndi magulu a methyl aulere ndi hydrogen ochokera kumagulu a imino, omwe onse amatha kuyanjana. Resin ya amino ikadziphatikiza yokha, idzataya ntchito zake zina.
Ngakhale kudzilumikiza nthawi zambiri kumapangitsa kuti zokutira zikhale zolimba komanso zolimbana ndi mankhwala, zimapangitsa kuti zikhale zotanuka kwambiri. Kuti ma varnish a polyester akhale otanuka mokwanira...
Hexamethoxymethyl melamine (HMMM) ndi utomoni wa monomeric wokhala ndi hydroxymethyl komanso methylated mokwanira. Mofanana ndi butylated melamine-formaldehyde, imadutsa mu cross-linking reaction ndi magulu a hydroxyl a polyester resin ikatenthedwa, ndikupanga cholimba chosafewa. Kwenikweni, popanda asidi catalyst, HMMM sidzadutsa mu crosslinking yokha ngakhale pakapita nthawi yayitali kapena kutentha kwambiri. Komabe, HMMM yambiri idzadutsa mu self-linking reaction pa 150°C pamaso pa asidi catalyst wamphamvu. Mosiyana ndi zimenezi, ngakhale popanda asidi wamphamvu, butylated melamine ndi urea resins wamba zidzadutsa mu crosslinking yamphamvu ndi kutentha kokwera.
Kuchiritsa kwa ma amino resins:
Popeza ma amino resins amagwiritsidwa ntchito kulumikiza mamolekyu akuluakulu opanga filimu kukhala kapangidwe ka netiweki, momwe ma amino resins amagwirira ntchito limodzi ndi ma penti resins ndi ofunikira kwambiri. Chitsanzo chodziwika bwino ndi momwe etherification (exchange) reaction imachitikira.magulu a hydroxyl pa ma resins a utoto ndi magulu a alkoxymethyl pa ma amino resins.
Pansi pa kutentha ndi ma catalyst a asidi (nthawi zambiri amakhala ochiritsa), kulumikizana kumachitika mwachangu, kulumikiza magulu onse a hydroxyl omwe alipo pa utoto. Ndipotu, pamene kapangidwe ka maukonde a polymer kamapangidwa, kusinthasintha kwa ma reactants kumachepa, zomwe zimapangitsa magulu ena a hydroxyl kusachitapo kanthu. Nthawi zambiri, pamene amino resin yochulukirapo ilipo mu utoto poyerekeza ndi chiŵerengero choyenera, magulu otsala a alkoxy amatha kutenga nawo mbali muzochita zina kapena kukhalabe osachitapo kanthu mu filimu yophimba. Monga tanenera kale, ma amino resin amadzilumikiza okha mosavuta ndikuchitapo kanthu wina ndi mnzake, zomwe zimapangitsa kuti kulemera kwa mamolekyulu kuchuluke panthawi yopanga. Zochita izi zimachitikanso panthawi yophimba. Chifukwa chake, m'malo mokhala chinthu choipa, kudzigwirizanitsa kwa ma amino resin ndikofunikira kuti pakhale matrix ya polymer yolimba komanso yolimba. Magulu onse atatu ogwira ntchito a amino resin amagwira nawo ntchito zodzigwirizanitsa, ndipo muzovala za melamine resin zomwe zimapangidwa ndi ma acid amphamvu, pali umboni wakuti zochita izi zimachitika pambuyo pa kusinthana kwa ether ndi utomoni wophimba. Ngati palibe ma catalyst akunja kapena ma acid catalyst ofooka, ma self-crosslinking reactions amenewa amapezeka kwambiri mu melamine resin systems omwe ali ndi imino/kapena hydroxymethyl yambiri. M'zochitika zonsezi, self-polymerization reaction yochepa ndiyofunikira kwambiri popanga network structure yabwino.
Pa nthawi yothira amino resin, zinthu zina zomwe zimachitika ndi kuchotsa formaldehyde ndi hydrolysis. Kuchotsa formaldehyde kumachitika mosavuta kutentha kwabwinobwino, komwe ndi chifukwa chokhacho chomwe chimatulutsira formaldehyde panthawi yothira amino resin; formaldehyde ina ndi free formaldehyde.
Pamene ma amino resins alumikizana kuti apange mafilimu ndi kuchiritsa, ma hydrolysis ena amachitika. Panthawiyi, magulu ena a alkoxymethyl amasinthidwa kukhala magulu a hydroxymethyl. Hydrolysis ya ma melamine resins okhala ndi imino kapena hydroxymethyl yambiri imatha kuyambitsidwa ndi alkalis, ndipo imatha kuchitika pang'onopang'ono kutentha kwa chipinda. Izi zimapangitsa kuti ma amino resins azikhala odzigwirizanitsa okha, zomwe zimapangitsa kuti kukhuthala kwa chophimbacho kuwonjezereke panthawi yosungidwa. Pofuna kupewa izi, ma melamine resins okhala ndi methyl kapena ma co-solvents olimbana ndi alkali hydrolysis angagwiritsidwe ntchito mu zokutira zochokera m'madzi. Ma melamine resins okhala ndi alkylated mokwanira amalimbana ndi alkali-catalyzed hydrolysis m'madzi. Ma melamine resins okhala ndi alkylated mokwanira komanso pang'ono salimbana ndi acid-catalyzed hydrolysis m'madzi; chifukwa chake, chothandizira cha asidi chotsekedwa chiyenera kugwiritsidwa ntchito mumadzi.
Ngati mukufuna kudziwa zambiriwothandizira kulumikizanazinthu, musazengereze kulankhulana nafe.
Nthawi yotumizira: Disembala-19-2025