Bayani game da amfani dasinadaran haɗin amino resin
Babban aikin amino resins (melamine-formaldehyde, benzomelamine-formaldehyde, da urea-formaldehyde resins) a cikin rufin thermosetting shine haɗa manyan ƙwayoyin abu masu samar da fim zuwa tsarin hanyar sadarwa mai girma uku ta hanyar halayen sinadarai. Ana samun wannan tsarin hanyar sadarwa ta hanyar amsawar ƙwayoyin amino resin tare da ƙungiyoyin aiki akan ƙwayoyin abu masu samar da fim, kuma a lokaci guda ta hanyar polymerization na condensation tare da sauran ƙwayoyin amino resin. Amino resins cikin sauƙi suna amsawa tare da polymers waɗanda ke ɗauke da ƙungiyoyin hydroxyl na farko da na biyu, ƙungiyoyin carboxyl, da ƙungiyoyin amide; saboda haka, ana amfani da amino resins akai-akai a cikin tsarin fenti bisa ga acrylic, polyester, alkyd, ko epoxy resins.
Ana kuma amfani da resin amino a cikin tsarin polyurethane a matsayin ƙarin kayan shafa don inganta aikin shafa gabaɗaya don wasu aikace-aikace.
Ka'idar amino resins:
Muhimmancin amino resins a cikin yin burodi ya wuce adadin da ake buƙata a cikin shafa. Fahimtar yadda ake amfani da halayen sinadarai na amino resins a cikin ƙirar tsarin shafa yana ƙara zama da mahimmanci. Misali,Idan masu tsara shafi ba su gamsu da wasu kaddarorin fim ɗin rufewa ba, za su iya daidaita su ta amfani da waɗannan hanyoyin:
1. Ingantawa ko sake zaɓar resin da ke samar da fim ɗin kansa;
2. Zaɓin amino resins (methyl etherification ko butyl etherification, da zaɓin matakin etherification, da sauransu);
3. Rabon resin da ke samar da fim da amino resin.
4. Zaɓin mai ƙara kuzari (ko za a ƙara shi ko a'a, da kuma adadin da za a ƙara).
Duk maki huɗu da ke sama, banda na farko,yana da alaƙa da amino resins. Halayen amino resins ya dogara ne akan ƙungiyoyin aikinsu da ayyukansu.saboda haka, fahimtar tsarin amino resins yana da matuƙar muhimmanci. Duk da haka, kafin a fahimci amino resins, yana da mahimmanci a fahimci ainihin resins ɗin da ake amfani da su tare da su.
Kamar yadda aka ambata a baya, amino resins galibi suna da ƙarfi.ana amfani da shi tare da resin alkyd, resin acrylic, resin polyester, da resin epoxy. Ana haɗa resin alkyd da farko daga polyols da polyacid resins ta hanyar esterification. A lokacin hadawa, barasa yawanci suna da yawa; wasu ƙungiyoyin carboxyl na polyacids bazai yi aiki gaba ɗaya ba, wanda ke haifar da resin alkyd wanda ke ɗauke da wani adadin ƙungiyoyin carboxyl da hydroxyl. Adadin ƙungiyoyin carboxyl da hydroxyl yawanci ana siffanta su da ƙimar acid da ƙimar hydroxyl. Darajar acid tana nufin adadin milligrams na KOH da ake buƙata don kawar da 1g na resin mai ƙarfi ta hanyar titration tare da KOH. Darajar Hydroxyl tana nufin adadin milligrams na KOH da ake buƙata don kawar da ƙungiyoyin OH gaba ɗaya a cikin 1g na resin mai ƙarfi ta hanyar titration tare da KOH. Hakazalika, resin polyester, resin acrylic, da amino resins suma suna ɗauke da wani adadin ƙungiyoyin carboxyl da hydroxyl. Bambancin yana cikin kayan da ake amfani da su don haɗa resins; misali, ƙungiyoyin carboxyl a cikin resin acrylic sun fito ne daga acrylic acid, kuma ƙungiyoyin hydroxyl sun fito ne daga hydroxyacrylic acid. Adadin ƙungiyoyin carboxyl da hydroxyl a cikin amino resins suma sun bambanta. Darajar acid, ƙimar hydroxyl, da kuma danko duk muhimman alamomi ne na resins, waɗanda ke shafar aikinsu kai tsaye.
Da muka koma kan batun amino resins, bari mu fara duba tsarinsu:
Hoto na 1:
Hoto na 2
Siffa ta 1 ta nuna wani sinadari mai suna alkylated amino resin wanda ke ɗauke da ƙungiyoyin alkoxy, imino, da hydroxymethyl. Idan muka yi la'akari da zoben da ke da membobi shida da ƙwayoyin carbon da nitrogen suka samar a matsayin kwarangwal, za a iya kwatanta rassan ko tsarin da aka samo daga gare shi a matsayin suna da kai uku da hannaye shida. Bambancin da ke tsakanin halayen amino resins ya faru ne saboda bambance-bambancen da ke cikin waɗannan "hannaye" shida da kuma tsarinsu mai rikitarwa da haɗuwarsu.
Siffa ta 2 ta nuna tsarin HMMM mai matuƙar daidaito, wato, cikakken amino resin mai methylated, tare da ƙungiya ɗaya kawai mai aiki: ƙungiyar methoxy, wadda aka tsara ta da kyau. Tunda matakin etherification ba zai iya kaiwa 1:6 (mafi girma) a ainihin samarwa ba, abin da ake kira cikakken methylated amino resin koyaushe zai ƙunshi wasu ƙungiyoyin imino da hydroxymethyl.
Bari mu fara da fahimtar ƙa'idodin amino resins don ƙarin koyo game da kaddarorinsu:
Mataki na farko wajen haɗa resin shine a mayar da melamine da formaldehyde a gaban wani mai kara kuzari don samar da polyhydroxymethyl melamine. Duk ƙwayoyin hydrogen masu aiki a kan zoben triazine za a iya canza su zuwa ƙungiyoyin hydroxymethyl, amma a zahiri, ƙwayoyin formaldehyde 2 zuwa 6 ne ke amsawa ga zoben triazine. Sauran ƙwayoyin hydrogen masu aiki waɗanda ba su amsawa ba suna wakiltar ƙungiyoyin imino. Kamar yadda za mu gani daga baya, waɗannan ƙungiyoyi suna taka muhimmiyar rawa a cikin tsarin warkarwa ta hanyar polymerization kai tsaye.
Polyhydroxymethyl melamine ba shi da ƙarfi sosai kuma yana da ƙarancin narkewa a cikin sinadaran shafawa na gargajiya. Guraben amino galibi suna aiki azaman abubuwan haɗin gwiwa da warkarwa a cikin abubuwan shafawa. Don ƙirƙirar wakili mai dacewa don shafawa, ƙungiyar hydroxymethyl yawanci ana haɗa ta da barasa mai gajeren sarka don rage amsawarta da inganta dacewarta da kayan samar da fim na gargajiya da abubuwan narkewa na aliphatic. Ana amfani da methanol da butanol galibi azaman abubuwan maye. Ta hanyar sarrafa adadin methanol ko butanol da aka ƙara da sauran yanayi, ana iya samun amino resins tare da matakai daban-daban na etherification.
Sai dai wuraren da suka yi hulɗa da formaldehyde (ƙungiyoyin hydroxymethyl) ne kawai za a iya rufe su da barasa; ƙwayoyin hydrogen marasa amsawa (ƙungiyoyin imino) ba sa amsawa da barasa mai gajeren sarka. Bugu da ƙari, wannan martanin yana nuna cewa duk ƙungiyoyin hydroxymethyl guda shida suna amsawa da barasa don samar da hexaalkoxymethyl melamine, ma'ana cewa ana iya sarrafa martanin ƙungiyoyin hydroxymethyl ɗaya zuwa shida tare da barasa. Shi ya sa muke da nau'ikan amino resins daban-daban.
Yin amfani da kai-tsaye na amino resins :
Nauyin kwayoyin amino resins ana tantance shi ta hanyar matakin da ke tattare da kansa kohaɗin giciyetsakanin ƙungiyoyin aiki (imino, hydroxymethyl, alkoxymethyl) akan zoben triazine da ƙwayoyin melamine. A ƙarshe, matakin polymerization na haɗin gwiwa yana shafar nauyin ƙwayoyin amino resin da aikin fim ɗin rufewa.
Amos resins na iya yin aiki ta hanyar da ta biyo baya:
Hoto na 3:
Amsar da ke hagu tana samar da gadar methylene, yayin da amsawar da ke dama ke samar da gadar methylene ether. Matsayin gada a cikin amino resins yawanci ana bayyana shi azaman matakin polymerization (DP): DP = nauyin kwayoyin halitta / nauyin kowane zoben triazine. Amino resins na farko galibi suna yin polymerization kai tsaye, tare da DP > 3.0. Ci gaban fasaha ya sa ya yiwu a rage cunkoson kai a cikin amino resins da aka gama. A halin yanzu, resin melamine da ake da su a kasuwa suna da DPs ƙasa da 1.1.
Babban tasirin nauyin amino resin kwayoyin halitta yana bayyana ne a cikin dankowar shafi. Dole ne a narkar da resin melamine tare da DP > 2.0 da ruwan da ke narkewa zuwa kashi 50%–80% na daskararru don cimma danko mai dacewa. Resin melamine na nau'in Monomer tare da DP tsakanin 1.1 da 1.5 yawanci ana samar da su a cikin nau'in daskararru masu tasiri 100%; ƙarin ruwan da ke narkewa suna da tasiri mai mahimmanci akan VOCs na murfin da aka gama. Nauyin kwayoyin amino resins shima yana shafar amsawar maganin rufe shafi da halayen fim. Tsarin rufewa ta amfani da resin amino mai girma zai isa ga yawan haɗin giciye da aka ƙayyade a cikin ɗan gajeren lokaci fiye da tsarin rufewa ta amfani da amino resin mai tsari iri ɗaya amma ƙaramin DP. Saboda haka, murfin da ke ɗauke da wakilai masu haɗin gwiwa na high-DP yana buƙatar ƙarancin mai haɓaka ko mai rage ƙarfin acid don cimma yanayin warkarwa iri ɗaya. Tasirin nauyin kwayoyin halitta akan halayen fim galibi yana cikin kewayon sassauci. Rufin da aka warkar da shi da resin amino mai girma-DP yana ɗauke da mafi girman kashi na haɗin amino-amino da ƙarancin haɗin amino-lacquer. Wannan nau'in tsarin haɗin gwiwa yana samar da shafi mai tauri mai kyau amma yana iya zama mai rauni. Wannan wani lokacin ana iya rama shi ta hanyar zaɓar resin fenti mai sassauƙa. Duk da haka, aikace-aikacen da ke buƙatar rufin mai sassauƙa gabaɗaya suna buƙatar resin amino monomeric.
Polyesters masu ɗauke da ƙungiyoyin carboxyl na iya amsawa tare da melamine-formaldehyde don samar da rufin saman thermosetting mai amfani tare da nau'ikan halaye na zahiri iri-iri.
Yawancin resin melamine-formaldehyde na butylated suna da amfani a kasuwanci, musamman saboda bambance-bambancen matakin farko na polymerization (nauyin kwayoyin halitta) da kuma rabon ƙungiyoyin alkoxy da waɗanda ba su da ƙungiyoyin hydroxymethyl da amino hydrogens. Waɗannan bambance-bambancen suna shafar ɗankowar ruwa, dacewar melamine da polyester, da kuma saurin warkar da enamel. Resin melamine na gargajiya, waɗanda ke amsawa da ƙungiyoyin hydroxyl na gefe, galibi suna haɗuwa da ƙwayoyin polyester. Tunda amsawar haɗin gwiwa ana yin catalyze da acid, a yanayin zafi tsakanin 120°C da 150°C, acid masu ƙarfi galibi suna shafar amsawar haɗin gwiwa na resin polyester; duk da haka, wasu polyesters suna buƙatar ƙarin catalysis na acid a cikin acid masu rauni sosai don warkar da tsarin enamel.
Akwai wani abu mai zuwa: Baya ga haɗin gwiwa na melamine-polyester, butylated melamine-formaldehyde resin shi ma yana fuskantar haɗin gwiwa. Wato, amino resin yana fuskantar haɗin gwiwa na kansa don samar da tsarin hanyar sadarwa ta melamine. Wannan haɗin gwiwa yana faruwa a lokaci guda tare da haɗin gwiwar melamine-polyester kuma haɗin gwiwa ne. Dalilin wannan haɗin gwiwa shine, ban da ƙungiyoyin butoxy, butylated melamine-formaldehyde resin shi ma ya ƙunshi ƙungiyoyin hydrocarbon kyauta da hydrogen daga ƙungiyoyin imino, waɗanda duk zasu iya yin hulɗa da juna. Da zarar amino resin ya haɗu da haɗin gwiwa na kansa, zai rasa wasu daga cikin ayyukansa.
Duk da cewa haɗin kai sau da yawa yana ba da ƙarin tauri da juriya ga sinadarai, yana haifar da asarar sassauci sosai. Don samun isasshen sassauci a cikin varnish ɗin polyester...
Hexamethoxymethyl melamine (HMMM) cikakken hydroxymethylated ne kuma cikakken methylated amino resin. Kamar butylated melamine-formaldehyde, yana fuskantar haɗin gwiwa tare da ƙungiyoyin hydroxyl na resin polyester bayan dumama, yana samar da daskararru mara laushi. Ainihin, ba tare da mai haɓaka acid ba, HMMM ba zai fuskanci haɗin kai ba koda kuwa da dogon lokaci ko ƙara yawan zafin jiki. Duk da haka, babban HMMM zai fuskanci haɗin kai a 150°C a gaban mai haɓaka acid mai ƙarfi. Akasin haka, ko da babu mai ƙarfi acid, melamine da resin urea na gargajiya za su fuskanci ƙarfin haɗin kai tare da ƙaruwar zafin jiki.
Maganin tsarkakewa na amino resins:
Tunda ana amfani da amino resins don haɗa manyan ƙwayoyin halitta masu samar da fim zuwa tsarin hanyar sadarwa, haɗin gwiwar haɗin gwiwar amino resins tare da fenti resins yana da matukar sha'awa. Misali na yau da kullun shine amsawar etherification (musanya).na ƙungiyoyin hydroxyl akan resin fenti da ƙungiyoyin alkoxymethyl akan resin amino.
A ƙarƙashin yanayin zafi da sinadarai masu haɓaka acid (yawanci suna warkarwa), haɗin gwiwa yana faruwa da sauri, yana haɗa dukkan ƙungiyoyin hydroxyl da ke akwai akan fenti. A zahiri, yayin da tsarin hanyar sadarwa ta polymer ke tasowa, ruwan sinadaran da ke haifar da amsawa yana raguwa, yana barin wasu ƙungiyoyin hydroxyl ba su amsawa ba. Gabaɗaya, lokacin da yawan amino resin ya kasance a cikin murfin idan aka kwatanta da rabon da ya dace, sauran ƙungiyoyin alkoxy na iya shiga cikin wasu halayen ko kuma su kasance ba su amsawa a cikin fim ɗin rufewa ba. Kamar yadda aka ambata a baya, amino resins suna haɗuwa da kansu cikin sauƙi kuma suna amsawa da juna, wanda ke haifar da ƙaruwar nauyin kwayoyin halitta yayin samarwa. Waɗannan halayen kuma suna faruwa yayin warkar da shafi. Don haka, maimakon zama mummunan abu, wani matakin haɗin kai na amino resins yana da mahimmanci don samun matrix polymer mai ɗorewa, cike da matsi. Duk ƙungiyoyi uku na amino resins suna shiga cikin halayen haɗin kai, kuma a cikin cikakken rufin melamine resin da aka haɓaka ta hanyar acid mai ƙarfi, akwai shaida cewa waɗannan halayen suna faruwa bayan musayar ether tare da resin shafi. Idan babu masu kara kuzari na waje ko masu kara kuzari masu rauni, waɗannan halayen haɗin kai suna faruwa har ma a cikin tsarin resin melamine tare da babban aikin imino/ko hydroxymethyl. A duka halayen biyu, ɗan ƙaramin amsawar kai-tsaye yana da mahimmanci don samar da kyakkyawan tsarin hanyar sadarwa.
A lokacin wargazawar shafi mai hade da amino resin, wasu halayen da ke faruwa sune cire formaldehyde da kuma hydrolysis. Cire formaldehyde yana faruwa cikin sauƙi a yanayin zafi na yau da kullun, wanda shine kusan dalilin sakin formaldehyde yayin wargaza amino resins; ɗayan formaldehyde shine free formaldehyde.
Lokacin da amino resins suka haɗu don samar da fina-finai da kuma warkewa, wasu halayen hydrolysis suna faruwa. A lokacin wannan tsari, wasu ƙungiyoyin alkoxymethyl suna canzawa zuwa ƙungiyoyin hydroxymethyl. Hydrolysis na resin melamine masu yawan imino ko hydroxymethyl za a iya haɓaka su ta hanyar alkalis, kuma har ma yana iya faruwa a hankali a zafin ɗaki. Wannan yana sa amino resins su fi saurin haɗuwa da kansu, wanda ke haifar da ƙaruwar danko na murfin yayin ajiya. Don guje wa wannan, ana iya amfani da resin melamine mai cikakken methylated ko co-solvents waɗanda ke jure wa alkali hydrolysis a cikin rufin ruwa. Resin melamine mai cikakken alkylated suna jure wa hydrolysis da alkali ya yi catalyzed a cikin tsarin tushen ruwa. Resin melamine mai cikakken alkylated da kuma wanda aka ɗan alkylated ba su jure wa hydrolysis da aka yi catalyzed a cikin tsarin tushen ruwa; saboda haka, dole ne a yi amfani da mai toshe acid a cikin tsarin tushen ruwa.
Idan kana son ƙarin bayaniwakilin haɗin gwiwasamfura, jin daɗin tuntuɓar mu.
Lokacin Saƙo: Disamba-19-2025