1. Ma'anar da aikin thickener
Additives da za su iya ƙara danko na tushen ruwa ana kiran su thickeners.
Thickers suna taka muhimmiyar rawa wajen samarwa, adanawa da gina sutura.
Babban aikin thickener shine ƙara danko na sutura don saduwa da bukatun matakai daban-daban na amfani.Duk da haka, danko da ake buƙata ta shafi a matakai daban-daban ya bambanta.Misali:
A lokacin tsarin ajiya, yana da kyawawa don samun babban danko don hana pigment daga daidaitawa;
A lokacin aikin gine-gine, yana da kyawawa don samun danko mai tsaka-tsaki don tabbatar da cewa fenti yana da kyakkyawar gogewa ba tare da wuce kima ba;
Bayan ginawa, ana fatan cewa danko zai iya dawowa da sauri zuwa babban danko bayan ɗan gajeren lokaci (tsarin daidaitawa) don hana sagging.
Ruwan rufin ruwa ba na Newtonian ba ne.
Lokacin da dankowar fenti ya ragu tare da karuwan ƙarfin ƙarfi, ana kiran shi ruwan pseudoplastic, kuma yawancin fenti shine ruwa mai tsabta.
Lokacin da yanayin kwararar ruwa na pseudoplastic yana da alaƙa da tarihinsa, wato, yana dogara da lokaci, ana kiran shi ruwa mai thixotropic.
A lokacin da masana'antu coatings, mu sau da yawa sane kokarin yin coatings thixotropic, kamar ƙara Additives.
Lokacin da thixotropy na sutura ya dace, zai iya magance sabani na matakai daban-daban na suturar, kuma ya sadu da bukatun fasaha na daban-daban danko na rufi a cikin ajiya, matakan ginawa, da kuma bushewa.
Wasu masu kauri na iya baiwa fenti da babban thixotropy, ta yadda zai kasance yana da danko mafi girma a lokacin hutawa ko kuma a ɗan ƙaramin ƙarfi (kamar ajiya ko sufuri), don hana launin launi a cikin fenti daga daidaitawa.Kuma a ƙarƙashin babban juzu'i (kamar tsarin sutura), yana da ƙananan danko, don haka rufin yana da isasshen ruwa da daidaitawa.
Thixotropy yana wakilta ta thixotropic index TI kuma an auna shi ta hanyar Brookfield viscometer.
TI = danko (ana auna a 6r / min) / danko (ana auna a 60r / min)
2. Nau'in thickeners da tasirin su akan kayan shafa
(1) Nau'o'i Dangane da abun da ke tattare da sinadarai, masu kauri sun kasu kashi biyu: Organic da inorganic.
Nau'in inorganic sun haɗa da bentonite, attapulgite, aluminum magnesium silicate, lithium magnesium silicate, da dai sauransu, nau'ikan kwayoyin kamar methyl cellulose, hydroxyethyl cellulose, polyacrylate, polymethacrylate, acrylic acid ko methyl Acrylic homopolymer ko copolymer da polyurethane da dai sauransu.
Daga hangen nesa na tasiri a kan rheological Properties na coatings, thickeners aka raba zuwa thixotropic thickeners da associative thickeners.Dangane da buƙatun aikin, adadin thickener ya kamata ya zama ƙasa kuma tasirin mai ƙarfi yana da kyau;ba shi da sauƙi a rushe ta hanyar enzymes;lokacin da yawan zafin jiki ko pH na tsarin ya canza, dankon rufin ba zai ragu sosai ba, kuma pigment da filler ba za a yi amfani da su ba.;Kyakkyawan kwanciyar hankali na ajiya;mai kyau riƙewar ruwa, babu wani abu na kumfa mai mahimmanci kuma babu wani tasiri mai tasiri akan aikin fim din mai rufi.
①Cellulose thickener
The cellulose thickeners amfani a coatings ne yafi methylcellulose, hydroxyethylcellulose da hydroxypropylmethylcellulose, kuma na karshen biyu ne mafi yawan amfani.
Hydroxyethyl cellulose samfur ne da aka samu ta maye gurbin ƙungiyoyin hydroxyl akan raka'a glucose na cellulose na halitta tare da ƙungiyoyin hydroxyethyl.An bambanta ƙayyadaddun ƙayyadaddun samfuran da samfuran samfuran bisa ga matakin maye da danko.
Hakanan ana rarraba nau'ikan hydroxyethyl cellulose zuwa nau'in rushewar al'ada, nau'in watsawa mai sauri da kwanciyar hankali na ilimin halitta.Dangane da hanyar da ake amfani da ita, ana iya ƙara hydroxyethyl cellulose a matakai daban-daban a cikin tsarin samar da sutura.Za'a iya ƙara nau'in watsawa da sauri kai tsaye a cikin nau'i na busassun foda.Duk da haka, ƙimar pH na tsarin kafin ƙarawa ya kamata ya kasance ƙasa da 7, musamman saboda hydroxyethyl cellulose yana narkewa a hankali a ƙananan ƙimar pH, kuma akwai isasshen lokacin da ruwa zai shiga cikin cikin kwayoyin halitta, sa'an nan kuma ƙimar pH yana ƙaruwa. don sanya shi Narke da sauri.Hakanan za'a iya amfani da matakan da suka dace don shirya wani ƙayyadaddun ƙwayar manne da ƙara shi zuwa tsarin sutura.
Hydroxypropyl methylcellulose samfuri ne da aka samu ta maye gurbin ƙungiyar hydroxyl akan rukunin glucose na cellulose na halitta tare da ƙungiyar methoxy, yayin da ɗayan ɓangaren ya maye gurbinsa da ƙungiyar hydroxypropyl.Its thickening sakamako ne m guda da na hydroxyethyl cellulose.Kuma yana da juriya ga lalatawar enzymatic, amma rashin narkewar ruwa ba shi da kyau kamar na hydroxyethyl cellulose, kuma yana da lahani na gelling lokacin zafi.Don hydroxypropyl methylcellulose da aka yi masa magani, ana iya ƙara shi kai tsaye zuwa ruwa lokacin amfani da shi.Bayan motsawa da watsawa, ƙara abubuwan alkaline kamar ruwan ammonia don daidaita ƙimar pH zuwa 8-9, kuma motsawa har sai an narkar da shi sosai.Ga hydroxypropyl methylcellulose ba tare da maganin saman ba, ana iya jika shi kuma a busa shi da ruwan zafi sama da 85 ° C kafin amfani da shi, sannan a sanyaya shi zuwa dakin da zafin jiki, sannan a jujjuya shi da ruwan sanyi ko ruwan kankara don narkewa sosai.
②Inorganic thickener
Irin wannan thickener yafi wasu kayan yumbu da aka kunna, irin su bentonite, magnesium aluminum silicate lãka, da dai sauransu. An kwatanta shi a cikin cewa ban da sakamako mai kauri, yana da tasiri mai kyau na dakatarwa, zai iya hana nutsewa, kuma ba zai tasiri ba. juriya na ruwa na rufi.Bayan an bushe murfin kuma an kafa shi a cikin fim, yana aiki a matsayin mai cikawa a cikin fim din da aka yi da shi, da dai sauransu. Abinda ba shi da kyau shi ne cewa zai yi tasiri sosai wajen daidaitawa.
③ roba polymer thickener
Roba polymer thickeners yawanci amfani a acrylic da polyurethane (associative thickeners).Acrylic thickeners yawanci acrylic polymers dauke da carboxyl kungiyoyin.A cikin ruwa tare da ƙimar pH na 8-10, ƙungiyar carboxyl ta rabu kuma ta zama kumbura;lokacin da ƙimar pH ta fi 10, ta narke a cikin ruwa kuma ta yi hasarar sakamako mai kauri, don haka tasirin daɗaɗɗa yana da matukar damuwa ga ƙimar pH.
The thickening inji na acrylate thickener shi ne cewa da barbashi za a iya adsorbed a saman latex barbashi a cikin fenti, da kuma samar da wani shafi Layer bayan alkali kumburi, wanda ƙara girma na latex barbashi, hana Brownian motsi na barbashi. , da kuma ƙara danko na fenti tsarin.;Na biyu, kumburin thickener yana ƙara dankowar lokaci na ruwa.
(2) Tasirin thickener a kan kayan shafa
Sakamakon nau'in thickener akan rheological Properties na shafi shine kamar haka:
Lokacin da adadin thickener ya karu, madaidaicin danko na fenti yana ƙaruwa sosai, kuma yanayin canjin danko ya kasance daidai lokacin da aka yi masa ƙarfi na waje.
Tare da tasirin thickener, danko na fenti yana raguwa da sauri lokacin da aka yi shi da karfi, yana nuna pseudoplasticity.
Yin amfani da kauri na cellulose da aka gyaggyara (kamar EBS451FQ), a babban adadin shear, danko yana da girma yayin da adadin ya girma.
Yin amfani da kauri na polyurethane masu haɗin gwiwa (irin su WT105A), a cikin ƙimar girma mai ƙarfi, danko yana da girma yayin da adadin ya girma.
Yin amfani da acrylic thickeners (irin su ASE60), ko da yake madaidaicin danko yana tashi da sauri lokacin da adadin ya girma, danko yana raguwa da sauri a mafi girma girma.
3. Associative thickener
(1) inji mai kauri
Cellulose ether da alkali-swellable acrylic thickeners iya kawai thicken da ruwa lokaci, amma ba su da wani thickening sakamako a kan sauran aka gyara a cikin ruwa tushen Paint, kuma ba za su iya haifar da gagarumin hulda tsakanin pigments a cikin Paint da kuma barbashi na emulsion, don haka. Ba za a iya daidaita rheology na fenti ba.
Associative thickeners suna halin da cewa ban da thickening ta hanyar hydration, kuma suna kauri ta hanyar ƙungiyoyi a tsakanin su, tare da tarwatsa barbashi, da kuma tare da sauran sassa a cikin tsarin.Wannan ƙungiyar ta rabu da haɓakar haɓaka mai girma kuma ta sake haɗawa a cikin ƙananan raguwa, ƙyale rheology na sutura don daidaitawa.
Tsarin kauri na associative thickener shine cewa kwayoyinsa shine sarkar hydrophilic madaidaiciya, wani fili na polymer tare da ƙungiyoyin lipophilic a ƙarshen duka, wato, yana da ƙungiyoyin hydrophilic da hydrophobic a cikin tsarin, don haka yana da halaye na ƙwayoyin surfactant.yanayi.Irin waɗannan ƙwayoyin cuta masu kauri ba za su iya yin ruwa kawai da kumbura don ɗaukar lokaci na ruwa ba, har ma suna samar da micelles lokacin da tattarawar maganin ruwan sa ya wuce ƙima.Micelles na iya haɗawa da ƙwayoyin polymer na emulsion da ɓangarorin pigment waɗanda suka tallata masu watsawa don samar da tsarin cibiyar sadarwa mai girma uku, kuma suna haɗuwa da juna don haɓaka danko na tsarin.
Abin da ya fi mahimmanci shi ne cewa waɗannan ƙungiyoyi suna cikin yanayin ma'auni mai ƙarfi, kuma waɗanda ke hade da micelles zasu iya daidaita matsayinsu lokacin da aka yi wa sojojin waje, don haka rufin yana da matakan daidaitawa.Bugu da kari, tun da kwayar halitta tana da miceles da yawa, wannan tsarin yana rage dabi'ar kwayoyin ruwa don yin ƙaura kuma don haka yana ƙara ɗanɗanowar lokaci mai ruwa.
(2) Matsayi a cikin sutura
Yawancin masu kauri masu haɗin gwiwa sune polyurethanes, kuma ma'aunin ƙwayoyin dangin su yana tsakanin umarni 103-104 na girma, umarni biyu na girma ƙasa da polyacrylic acid na yau da kullun da masu kauri na cellulose tare da ma'aunin ƙwayoyin ƙwayoyin dangi tsakanin 105-106.Saboda ƙananan nauyin kwayoyin halitta, haɓakar ƙarar inganci bayan hydration yana da ƙasa, don haka maɗaurin danko yana da kyau fiye da na masu kauri marasa haɗin gwiwa.
Saboda ƙarancin nauyin kwayoyin halitta na associative thickener, intermolecular entanglement a cikin lokaci na ruwa yana da iyaka, don haka tasirinsa na kauri akan lokacin ruwa ba shi da mahimmanci.A cikin ƙananan ƙananan ƙima, canjin ƙungiyar tsakanin kwayoyin halitta ya fi lalata haɗin gwiwa tsakanin kwayoyin halitta, tsarin duka yana kula da yanayin dakatarwa da watsawa, kuma danko yana kusa da danko na matsakaicin watsawa (ruwa).Saboda haka, mai kauri mai haɗin gwiwa yana sa tsarin fenti na tushen ruwa ya nuna ƙananan danko lokacin da yake cikin ƙananan yanki.
Associative thickeners ƙara m makamashi tsakanin kwayoyin saboda ƙungiyar tsakanin barbashi a cikin tarwatsa lokaci.Ta wannan hanyar, ana buƙatar ƙarin makamashi don karya haɗin gwiwa tsakanin kwayoyin halitta a cikin ƙananan ƙwayoyin cuta, kuma ƙarfin da ake bukata don cimma irin wannan nau'i mai mahimmanci ya fi girma, ta yadda tsarin ya nuna mafi girma mai girma a cikin ƙananan ƙananan ƙira.Bayyanar danko.Mafi girman danko mai ƙarfi da ƙananan danko mai ƙarancin ƙarfi zai iya zama kawai don ƙarancin masu kauri na yau da kullun a cikin kaddarorin rheological na fenti, wato, ana iya amfani da masu kauri biyu a hade don daidaita ruwa na fenti na latex.Canje-canjen aiki, don saduwa da cikakkun buƙatun shafi cikin fim mai kauri da kwararar fim ɗin.
Lokacin aikawa: Nuwamba-24-2022