Daidaita Isocyanates tare da Rubbers na Ruwa Masu Aiki HTPB da CTBN

Muhimman Abubuwan Da Ake Ɗauka

• Haɗa robar ruwa mara polar da isocyanates masu ƙamshi don gina kayan da ba su da tsada, masu jure ruwa mai ƙarfi.
• Haɗa isocyanates na aliphatic da robar ruwa don ƙirƙirar manne mai haske, mai jure wa rana.
• Kiyaye naka Sinadaran NCO ma'aunin tsakanin 1.02 da 1.08 don tabbatar da cikakken warkarwa da kuma aiki mai ƙarfi.

Taswirar Sinadarai da Ayyuka

Tsarin Rukunin Tashar da Kinetics

Dole ne ka tsara saurin amsawar isocyanate ɗin da ka zaɓa zuwa takamaiman rukunin ƙarshe na robar ruwa. Polybutadiene da aka ƙare da Hydroxyl (HTPB) yana amsawa cikin sauƙi tare da diisocyanates, yayin da yake robar da aka dakatar da amine (ATBN) Amsa nan take don samar da haɗin polyurea mai ƙarfi. Lokacin da ka ƙirƙiri diisocyanates marasa daidaituwa kamar IPDI, takamaiman abubuwan kara kuzari suna canza amsawar rukuni. Misali, trifluoroacetic acid yana kunna ƙungiyar isocyanate ta farko fiye da ta sakandare. Yanayin sinadarai na ƙungiyoyin gefe da ke kusa yana haifar da wannan zaɓin motsi maimakon hana steric.

Daidaita Sigar Polarity da Solubility

Daidaita Isocyanates da Rubbers na Ruwa Masu Aiki (HTPB vs. CTBN) yana buƙatar kimanta sigogin narkewa da kyau. Kasusuwan polybutadiene marasa polar ba sa tsayayya da haɗuwa da isocyanates na polar, masu ƙanshi. Kuna iya amfani da jagorar mai zuwa don haɗa kashin baya da maganin warkarwa:

Tsarin Isocyanate da Tsarin Rarraba Mai Tauri

Daidaiton kwayoyin halitta na isocyanate yana ƙayyade tsarin lu'ulu'u mai tauri da rabuwar matakai. Tsarin ƙamshi mai simita kamar 4,4'-MDI yana taruwa sosai, yana ƙirƙirar yankuna masu tauri waɗanda ke haɓaka ƙarfin injina. Monoma marasa daidaito kamar TDI ko IPDI suna wargaza marufi kusa, suna rage danko na resin da haɓaka ƙarancin zafin jiki. Kuna iya daidaita ƙarfin polymer gabaɗaya ta hanyar daidaita yanayin geometric da asymmetric.

Daidaita Isocyanates tare da Rubbers na Ruwa Mai Aiki (Tsarin HTPB)

Polybutadiene da aka ƙare da Hydroxyl (HTPB) yana da kashin bayan hydrocarbon mara polar sosai, mai kama da hydrophobic. Dole ne ku zaɓi maganin da ya dace don kare danshi da kuma kiyaye daidaiton tsarin. Daidaita Isocyanates tare da Rubbers na Ruwa Mai Aiki (Tsarin HTPB yana buƙatar yin nazari kan amsawar sinadarai da buƙatun injiniya na ƙarshe.

MDI da TDI don Elastomers masu kama da Hydrophobic

Diisocyanates masu ƙamshi kamar diphenylmethane diisocyanate (MDI) da toluene diisocyanate (TDI) Suna amsawa da sauri da rukunin ƙarshen HTPB hydroxyl. Waɗannan nau'ikan ƙamshi suna ba da ƙarfi na zahiri da ƙarancin farashi. MDI yana ƙirƙirar sassa masu kauri, masu ƙarfi sosai a cikin hanyar sadarwa ta elastomeric. Wannan marufi mai yawa yana ƙara ƙarfin juriya da kuma ƙara juriyar tsagewa.

Kashi na baya na HTPB (Ba ya da polar) + MDI/TDI (Mai ƙamshi) ===> Elastomer mai kama da ruwa 

TDI yana ba da ƙarancin ɗanko na farko fiye da MDI. Za ka iya zuba ƙwayoyin da aka yi amfani da su ta hanyar TDI cikin molds masu rikitarwa cikin sauƙi. Duk da haka, TDI yana nuna matsin lamba mafi girma na tururi. Dole ne ka yi amfani da TDI tare da ƙarin iska don kare masu aiki.

Dukansu magungunan ƙanshi suna kiyaye halayen HTPB masu hana ruwa shiga jiki. Suna kare elastomer na ƙarshe daga shan ruwa, rage acid, da kuma alkalis masu ruwa.

Lura: Sassan ƙamshi masu tauri suna lalacewa ƙarƙashin hasken ultraviolet kai tsaye (UV). Yi amfani da MDI da TDI galibi a cikin aikace-aikacen da aka binne, aka shafa, ko a cikin gida inda hasken UV bai kasance mai yawa ba.

IPDI da HDI don Tsarin Haske Mai Sauƙi

Aliphatic isocyanates suna magance matsalolin tsufa da lalacewar haske. Isophorone diisocyanate (IPDI) da hexamethylene diisocyanate (HDI) suna tsayayya da hasken UV gaba ɗaya. Suna hana launin rawaya da tsagewa a saman yayin fallasa su ga waje na dogon lokaci.

IPDI ya ƙunshi ƙungiyoyin NCO guda biyu marasa daidaito. Babban rukunin NCO yana amsawa a hankali, yayin da ƙungiyar NCO ta biyu ke amsawa da sauri a ƙarƙashin yanayin zafi mai yawa. Kuna iya amfani da wannan bambancin motsi don sarrafa rayuwar tukunya da tsarin jefawa.

HDI yana samar da sassaucin layi. Tsarinsa na aliphatic mai daidaito yana rage zafin rabuwar microphase, wanda ke kiyaye sassauci har zuwa yanayin ƙasa da sifili.

• Fa'idodin IPDI: Tsawon lokacin tukunya, zagayowar warkarwa mai sarrafawa, kwanciyar hankali mai zafi mai yawa.
• Amfanin HDI: Mafi kyawun sassauci a yanayin zafi, kyakkyawan juriya ga UV, ƙarancin ɗanko.

Daidaita Isocyanates tare da Rubbers na Ruwa Mai Aiki (HTPB da maganin aliphatic yana samar da haske mai haske, daidaiton launi, da kuma manne mai jure yanayi.

Haɗakar Prepolymer da Ingantaccen Stoichiometry

Haɗawa kai tsaye da harbi ɗaya na iya haifar da halayen exothermic mara tsari da kuma rabuwar matakai. Kuna iya hana waɗannan matsalolin ta hanyar haɗa wani Prepolymer da aka dakatar da NCO da farko. Haɗakar Prepolymer yana rage jimillar samar da zafi yayin warkarwa ta ƙarshe kuma yana rage fitar da hayakin monomer mai canzawa.

1. Shiri na Amsawa: Yi cajin reactor ɗinka da busasshen resin HTPB.
2. Cire Danshi: Yana cire sinadarin resin a zafin digiri 90 na Celsius don kawar da danshi da ya rage. Ruwa yana amsawa da ƙungiyoyin NCO, yana haifar da kumfa na carbon dioxide da kuma raunin urea.
3. Ƙarin Isocyanate: Sai a zuba diisocyanate da aka zaɓa a ƙarƙashin busasshen bargon nitrogen.
4. Faɗaɗa Sarkar da Aka Sarrafa: A kiyaye zafin jiki tsakanin 70°C da 80°C har sai abun da ke cikin NCO ya daidaita.

Mataki na 1: Isocyanate da ya wuce kima + HTPB ===> Prepolymer da aka dakatar da NCO + Monomer kyauta Mataki na 2: Prepolymer + Sarkar Extender ===> Cibiyar sadarwa ta Polyurethane da aka warke 

Dole ne ka yi lissafin stoichiometry ɗinka a hankali. Ka ajiye jimlar ma'aunin NCO (daidaitaccen rabo na ƙungiyoyin NCO da OH) a cikin kewayon 1.03 zuwa 1.06.

$$\text{NCO Index} = \frac{\text{Jimillar Daidaito na NCO}}{\text{Jimillar Daidaito na OH}}$$

Ma'aunin NCO da ke ƙasa da 1.00 yana barin sarƙoƙin HTPB marasa amsawa. Waɗannan ƙwayoyin ruwa marasa amsawa suna aiki azaman masu amfani da filastik da ba a so, wanda ke rage ƙarfin tensile ɗinku kuma yana rage juriyar sinadarai. Akasin haka, ma'aunin NCO da ke sama da 1.10 yana haifar da haɗin gwiwa mai yawa. Haɗin gwiwa da yawa yana haifar da gazawar rauni a ƙarƙashin nauyin tasirin tasiri mai ƙarfi. Daidaitaccen stoichiometry yana tabbatar da matsakaicin aiki.

Dabaru na Zaɓin CTBN, ATBN, da HTBN

Rukunin tashoshin Carboxyl, amine, da hydroxyl akan kashin baya na robar nitrile suna buƙatar dabarun zaɓi da aka yi niyya. Kuna iya inganta ƙarfin karyewar ƙarfe, juriya ga sinadarai, da aikin zafi sosai ta hanyar haɗa waɗannan roba masu aiki tare da isocyanates masu dacewa.

Hybrids na Epoxy-Polyurethane tare da CTBN da MDI

Butadiene acrylonitrile (CTBN) wanda Carboxyl ya ƙare ya ƙunshi ƙungiyoyin carboxylic acid (-COOH) da kuma kashin baya na nitrile na polar. Haɗakar kai tsaye tsakanin carboxylic acid da diisocyanates yana haifar da haɗin anhydride mara ƙarfi kuma yana fitar da iskar carbon dioxide. Kuna iya kawar da kumfa ta hanyar haɗa hanyoyin sadarwa na epoxy-polyurethane.

CTBN + Resin Epoxy Mai Wuce Gona ===> Robar da aka Kare daga Epoxy Prepolymer + 4,4'-MDI + Mai Faɗaɗa Sarka ===> Matrix Mai Tauri da Haɗaka 

Da farko, a yi amfani da CTBN da ƙarin resin epoxy don samar da matsakaicin roba mai ƙarewa daga epoxy. Na gaba, a ƙara 4,4'-MDI da mai faɗaɗa sarkar diol don gina kashin bayan polyurethane mai haɗin gwiwa a kusa da yankunan roba.

Nasiha ga Ƙwararru: Ajiye abubuwan da ke cikin acrylonitrile (AN) a cikin CTBN tsakanin 18% da 26%Wannan takamaiman kewayon AN yana haɓaka rabuwar lokaci yayin warkarwa. Ƙananan yankuna na roba masu girman micron suna fitowa daga cikin matrix, suna ƙirƙirar shinge masu tasiri don hana yaɗuwar tsagewa.

MDI tana samar da ƙaƙƙarfan sassa masu tauri waɗanda ke ɗaure ga matrix na polar. Lokacin da damuwa mai ƙarfi ta bugi gawar da aka warke, waɗannan yankunan CTBN da aka warwatse suna shan kuzarin tasiri. Kuna samun ƙarfin karyewa mai yawa ba tare da la'akari da kwanciyar hankali na injin zafi ko modulus mai ƙarfi ba.

Samar da Amine-Isocyanate Urea kai tsaye tare da ATBN

Amine-endated butadiene acrylonitrile (ATBN) yana da reactive primary ko secondary end-groups amine (-NH2 ko -NHR). Amines suna amsawa da diisocyanates nan take a zafin ɗaki. Suna samar da haɗin polyurea mai ƙarfi ba tare da buƙatar sinadaran kara kuzari ba.

Lokacin da aka haɗa Isocyanates da Rubbers na Ruwa Mai Aiki (Tsarin HTPB ko tsarin ATBN), dole ne ka daidaita kayan haɗinka don magance waɗannan bambance-bambancen motsi. ATBN yana amsawa da sauri har dole ne ka yi amfani da kawunan haɗin haɗin gwiwa na musamman masu ƙarfi.

ATBN (Amine Ends) + Isocyanate (NCO) ===> Polyurea Hard Segments (Bidentate Linking) 

Sakamakon polyurea hard domains suna samar da ƙarfi bidentate hydrogen bonds. Waɗannan haɗin gwiwa na zahiri suna ɗaga wurin lalata zafi na elastomer ɗinku sama da 150°C. Hakanan kuna kawar da matsalolin jin daɗin danshi yayin sarrafawa. Ƙungiyoyin ƙarshen Amine suna amsawa da NCO da sauri fiye da ruwan da ke kewaye.

Dacewar HTBN a Tsarin da ke Jure Man Fetur

Butadiene acrylonitrile da aka ƙare da Hydroxyl (HTBN) yana haɗa aikin hydroxyl (-OH) tare da kashin baya na nitrile na polar. Rubbai marasa polar suna lalacewa da sauri idan aka fallasa su ga mai mara polar, abubuwan narkewa masu ƙamshi, ko ruwan hydraulic. Rukunin acrylonitrile na polar a cikin HTBN yana korar hydrocarbons, yana kare elastomer ɗinku daga kumburin solvent.

HTBN (Bayanan baya na Polar) + IPDI/MDI ===> Shingen Hydrocarbon Mai Juriya Ga Mai 

Dole ne ku haɗa HTBN da diisocyanates masu jituwa don gina hatimi masu ɗorewa, gaskets, da layukan tankin mai:

• Haɗa HTBN da MDI: Kuna cimma matsakaicin ƙarfin injina, juriya mai yawa ga hawaye, da kuma ƙarfin kore mai sauri don gaskets na masana'antu.
• Haɗa HTBN da IPDI: Za ka sami rufin tankin mai mai sassauƙa, mai karko da hasken UV wanda ke tsayayya da fashewa a ƙarƙashin canjin yanayin zafi mai canzawa.

Za ka iya daidaita abun cikin nitrile a cikin HTBN don daidaita juriyar sinadaran narkewa. Matakan acrylonitrile mafi girma suna ƙara polarity da haɓaka juriyar mai. Duk da haka, mafi girman polarity kuma yana ƙara danko na resin na farko. Ya kamata ka dumama HTBN zuwa 50°C yayin cire gass don rage danko na sarrafawa kafin gabatar da diisocyanate da ka zaɓa.

Ma'aunin Tsarawa da Sarrafawa Mai Muhimmanci

Ma'aunin Stoichiometric da kuma Kula da Ma'aunin NCO

Dole ne ku sarrafa rabon stoichiometric tsakanin ƙungiyoyin isocyanate masu aiki da ƙungiyoyin ƙarshen roba. Yi niyya ga ma'aunin NCO tsakanin 1.02 da 1.08 don tabbatar da cikakken haɗin sinadarai. Ma'aunin da ke ƙasa da 1.00 yana barin oligomers marasa amsawa. Waɗannan ƙwayoyin kyauta suna aiki azaman masu plasticizers da ba a so kuma suna rage daidaiton tsarin. Akasin haka, ma'aunin da ke sama da 1.10 yana haifar da haɗin gwiwa mai yawa, wanda ke sa elastomer ɗinku da aka warke ya yi rauni.

Tsarin Halittar Yanki da Rabuwar Microphase

Rabuwar microphase tana sarrafa aikin injiniya na matrix ɗin polymer ɗinku da aka warke kai tsaye. Kasusuwan roba marasa polar suna korar sassan urea ko polar. Kuna iya daidaita wannan rashin jituwa na sinadarai don motsa haɗa kai yayin warkarwa. Yankunan tauri da aka warwatse suna aiki azaman haɗin gwiwa na zahiri don haɓaka ƙarfin tauri. A halin yanzu, yankuna masu laushi na roba masu ci gaba suna kiyaye sassaucin ƙarancin zafin jiki kuma suna shan kuzarin tasirin tasiri mai ƙarfi.

Sarrafa Danko da Inganta Rayuwar Tukunya

Lokacin da aka haɗa Isocyanates tare da Rubbers na Ruwa Mai Aiki (Tsarin HTPB, yawan ɗanko na farko mai yawa yana hana cikawa da kuma cire gass mai inganci na mold. Masu narkewa marasa amsawa suna rage danko, amma suna haifar da rauni a lokacin fitar da hayaki. Madadin haka, HTPB mai ƙarancin nauyin kwayoyin halitta yana aiki azaman mai narkewa mai amsawa a cikin tsarin polymer, yana ba da damar rage danko mai inganci yayin da yake kiyaye manyan halayen injiniya da na zahiri na kayan.

Shawara: Zafafa robar ruwanka zuwa digiri 50 na Celsius kafin ƙara maganin warkarwa don tsawaita rayuwar tukunya da kuma hanzarta sakin kumfa.

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• Haɗa HTPB mara polar tare da MDI ko TDI don haɓaka yawan zafin jiki da sassauci mai ƙarancin zafi ta hanyar rage farashi.
• Haɗa HTPB da aliphatic IPDI ko HDI don samun juriya mai kyau ga UV da tsawon rai a cikin tukunya.
• Yi amfani da robar nitrile (CTBN, ATBN, HTBN) a cikin tsarin polar don haɓaka ƙarfin karyewa da juriyar mai.
• Sarrafa stoichiometry na NCO sosai. Daidaita rabo yana hana oligomers marasa amsawa rauni daga elastomer ɗinku.

Tambayoyin da ake yawan yi akai-akai

Ta yaya za ku zaɓi tsakanin MDI da IPDI don tsarin HTPB?

Shawara Mai Sauri: Daidaita maganin ku da yanayin aikace-aikacen ku.

Zaɓi MDI lokacin da kake buƙatar ƙarfin juriya mai yawa da ƙarancin farashi don aikace-aikacen cikin gida. Zaɓi IPDI don samfuran waje waɗanda ke buƙatar kwanciyar hankali na UV da tsawaita lokacin tukunya.

Me yasa dole ne ku kula da ma'aunin NCO tsakanin 1.02 da 1.08?

Wannan takamaiman rabo yana tabbatar da cikakken haɗin sinadarai. Yana hana robar ruwa mara amsawa ta laushi matrix ɗinku kuma yana hana haɗin gwiwa mai yawa daga ƙirƙirar elastomer mai rauni.

Ta yaya CTBN ke inganta taurin karyewa a cikin nau'ikan epoxy-polyurethane?

CTBN yana shiga cikin ƙananan sassan roba yayin warkarwa. Waɗannan ƙananan ƙwayoyin roba suna shan kuzarin tasiri kuma suna dakatar da yaɗuwar fasa a cikin matrix ɗin polymer ɗinku da aka warke.