Metiletil keton-formaldehit reçinesinin modikasyonları

Abstract

Bu çalışmada, bazik ortamda elde edilen metiletil keton-formaldehit reçinesi, üretimi esnasında, içerisine formaldehit ile reaksiyon verebilen, çeşitli fonksiyonel gruplara sahip bileşikler katılarak modifiye edilmiştir. Modifikasyon iki yöntemle yapılmıştır. Yöntemle göre modifiye edici bileşik, diğer bileşiklerle sisteme baştan konulmuş, yöntem 2'ye göre ise reçinenin oluşum zamanına ve şartlarına bağlı olarak önce reçineleşme belli bir safhaya getirilmiş, modifiye edici bileşik daha sonra reaksiyon ortamına ilave edilmiştir. Bazik ortamda metiletilketon - formaldehit reçinesi oluşum anında fenol, bisfenol A, üre ve sitrik asit ile modifiye edilmiştir. Metiletilketon-formaldehit reçinesi ve onun üretim esnasındaki modifiye reçineleri yapılarında bulunan hidroksil fonksiyonel grupları üzerinden toluen " diizosiyanatla ve karbonil fonksiyonel grupları üzerinden hidroksilaminle reaksiyona girmişlerdir. Aynca metiletilketon-formaldehit reçinesinin karbonil grubu, metilen grubuna "Huang-Minlon" tarafindan geliştirilmiş Wolff-Kishner reaksiyonu tarafından indirgenmiştir. Elde edilen metiletilketon-formaldehit reçinesi, onun üretim esnasındaki modifiyeleri ve karbonil ile hidroksil fonksiyonel grupları üzerinden modifiye ürünlerinin çözünürlükleri, erime noktalan ve FTIR spektrumlanndaki değişiklikler incelenmiştir.Ketones containing a-hydrogens react with formaldehyde in alkaline solutions to give thermoplastic ketone-formaldehyde resins. They are produced via formation of monomethylol derivatives of the ketone as a result of aldol condensation between ketone and formaldehyde. For example, methylethyl ketone reacts with formaldehyde first to give monomethylol of methylethyl ketone under alkaline conditions. ÇH3 CH3 ÇH2 QHG HC- CH2-OH r n + CH2° - J- n C=0 z on 90°r C= O l Formaldehyde Ö";7;;Q l.CH3 PH>9 CH3 Methylethyl Methylethyl ketone ketone Monomethylol After formation of the monomethylol derivatives of the ketones, due to the temperature, ratio of formaldehyde/ketone and type of basic catalyst, ketone monomethylols react fiırther with formaldehyde to give resinous products. Therefore, methylethyl ketone monomethylols react further with formaldehyde to produce thermoplastic solid resins with the following formula. The methylene bridges, shown here in a regular arrangement connect the ketone molecules at their a-positions and form a regular chain. > HOCH7--C CH2 OH 2 l C = 0 l CH3 Jn = 5-8 vıi The resinous products obtained by the condensation reactions between the lower-molecular-weight aliphatic ör cycloaliphatic ketones such as acetone, methylethylketone, ör cyclohexanone with formaldehyde are of commercial importance. Thermoplastic ketone resins are used in the coating industry as additives to modify the properties of high-molecular-weight film formers. These resins are ali low in molecular \veight, mostly in the range 500-1000. They are soluble in aromatic hydrocarbons, ketones, esters, and chlorinated solvents, but not in aliphatic hydrocarbons. Most, but not ali of these resins are soluble in alcohols. Ketone resins have excellent acid and alkali resistance. So, in this work, in-situ modification of methylethylketone-formaldehyde resin was studied. But, first methylethylketone-formaldehyde (MEK-F) resin was obtained under mild alkaline conditions at pH: 9-10 and at temperatures of 80-90°C. The ratio of formaldehyde to methylethylketone was 2. Methylethylketone-, formaldehyde resin was modified during the condensation reaction (in-situ modification) by a number of modifier compounds which react with formaldehyde under alkaline conditions. Those modifier compounds were urea, phenol, bisphenol A and citric acid. Furthermore, methylethylketone-formaldehyde and its in-situ modified resins were modified via their hydroxyl and carbonyl functional groups by a few reagents. Ketonic resins were modified via their carbonyl groups by reaction with hydroxylamine. The modification of ketonic resins via their hydroxyl groups were achieved by reaction with toluene2,4-diisocyanate(TDI). Addition to ali these, the carbonyl group of methylethylketone-formaldehyde resin (MEK-F) was reduced to methylene by the modified reduction reaction of WolfF-Kishner, The modified resins were recovered as parent ketonic resin and examined with TLC and found that they are in the form of cocondensation of both ketone and modified substance with formaldehyde, but not in a physical mixture of ketonic resin and resin of modifier compounds. The aim of these modification reactions is to regulate the melting points, solubilities in organic solvents, and also to widen the application fields of methylethylketone resins. Suggested formulas of the in-situ modified MEK-F resins are as follows; Vİİİ Methylettıylketone - Urea-Formaldehyde Resin (MEK-U-F ) T 1 f 1 C,H3 f2 0 ÇH, ÇH2 + C=0 + CH20-^- HOCH2--C-CH2 N-CH2 OH C=0 l II | NH2 Ç=0 C=0 CH3 ' l L 3 J L N-CH2-- MEK-U-F Mef-hylefhylketone - Phenol - Formaldehyde Resin (MEK-P-F) CH3 ?H f ru l T | 3 L © ^H3 OH ÇH2 + (Q) +CH20 _OH_ HQCH2 C_CH2 JL ÎB° c=o ^ [k \[ ^ MEK-P-F Methylethyl ketona - Bisphenol A - Formatdehyde Resin (MEK-B-F) OH l"3 f^ı © ÇH3 f ^H2 + LŞJ +CH20-°^HOCH2 İ-CH2- -roî~CH2--OH C = 0 H3C-C-CH3 C=0 Y ^ (p) [cH3 Jlf"5"CH3 OH '$J-CH2- - OH MEK-B-F ix Mefhylethylkefone -Citric Acid-Formaldehyde Resin (MEK-C-F) CH3 COOH F CH, ÎT COOH l 3 , Ln3 j CH2 CH2 0HOCH--C-CH2 C-CH,--OH l l OH 2 l l C=0 4 HO-C-COOH + CH20 -^- C = 0 HO-C-COOH III l CH3 CH2 CH3 C-CH2-- COOH COOH MEK-C-F The suggested formula of the MEK-F resin modified via its hydroxyl fünctional groups by TDI is as foUows; (OH/TDI: 10/1) ı"31 HS v^ r ı*3 HO--CH2-C CH2-0-C-NH-LOj_NH-C_o-CH2--C CH2OH C=0 O O C=0 l - l CH3 CH3 L J6 L Jn The suggested formula of the MEK-F resin modified via its carbonyl functional groups by hydroxylamine is as follows; ~CH3 l |"CH3 HOCH2--C-CH2 C_CH2 OH II C=0 C=N-OH CH3 CH3 L Jx L Jy x The suggested formula of the "Reduced" MEK-F resin by the "Huang- Minlon" modified Wolff-Kishner reaction is as follows; CH3 l fcH3 l l C=0 CH2 l l HOCH2--C-CH2 C _CH2 OH CH3 CH3 L Jx L Jy Besides, TLC studies, the modified resins were characterized by FTIR spectroscopy. 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