INVESTIGATION OF DARK YELLOWING BEHAVIOUR OF ALKYD-BASED POLYURETHANE COATINGS

Project no. 32913 · Status: Kapanmış (Yayın bekleniyor) · 2025

Summary

<p>In&nbsp;this&nbsp;study,&nbsp;the&nbsp;dark&nbsp;yellowing&nbsp;behavior&nbsp;of&nbsp;alkyd-based&nbsp;polyurethane&nbsp;coatings&nbsp;was&nbsp;thoroughly&nbsp;investigated.&nbsp;Polyurethane&nbsp;coatings&nbsp;formed&nbsp;by&nbsp;the&nbsp;reaction&nbsp;of&nbsp;polyols&nbsp;and&nbsp;diisocyanates&nbsp;are&nbsp;widely&nbsp;used&nbsp;in&nbsp;the&nbsp;furniture&nbsp;industry&nbsp;as&nbsp;primers,&nbsp;basecoats,&nbsp;and&nbsp;topcoats&nbsp;on&nbsp;wooden&nbsp;surfaces.&nbsp;Among&nbsp;polyols,&nbsp;alkyd&nbsp;resins&nbsp;with&nbsp;polyester&nbsp;structures&nbsp;modified&nbsp;by&nbsp;fatty&nbsp;acids&nbsp;are&nbsp;the&nbsp;most&nbsp;preferred.&nbsp;As&nbsp;cross-linkers,&nbsp;both&nbsp;aromatic&nbsp;and&nbsp;aliphatic&nbsp;diisocyanates&nbsp;are&nbsp;used,&nbsp;and&nbsp;to&nbsp;enhance&nbsp;the&nbsp;physical&nbsp;drying&nbsp;rate,&nbsp;high&nbsp;molecular&nbsp;weight&nbsp;thermoplastic&nbsp;resins&nbsp;such&nbsp;as&nbsp;nitrocellulose&nbsp;(NC)&nbsp;or&nbsp;cellulose&nbsp;acetobutyrate&nbsp;(CAB)&nbsp;are&nbsp;incorporated&nbsp;into&nbsp;the&nbsp;system.</p><p>Within&nbsp;the&nbsp;scope&nbsp;of&nbsp;this&nbsp;diploma&nbsp;project&nbsp;study,&nbsp;the&nbsp;individual&nbsp;and&nbsp;combined&nbsp;effects&nbsp;of&nbsp;parameters&nbsp;such&nbsp;as&nbsp;the&nbsp;degree&nbsp;of&nbsp;fatty&nbsp;acid&nbsp;modification&nbsp;of&nbsp;the&nbsp;alkyd,&nbsp;the&nbsp;type&nbsp;and&nbsp;amount&nbsp;of&nbsp;auxiliary&nbsp;resin,&nbsp;and&nbsp;the&nbsp;type&nbsp;of&nbsp;isocyanate&nbsp;cross-linker&nbsp;on&nbsp;the&nbsp;dark&nbsp;yellowing&nbsp;tendency&nbsp;of&nbsp;the&nbsp;coatings&nbsp;were&nbsp;examined.&nbsp;According&nbsp;to&nbsp;the&nbsp;results,&nbsp;the&nbsp;most&nbsp;influential&nbsp;factor&nbsp;on&nbsp;yellowing&nbsp;in&nbsp;dark&nbsp;conditions&nbsp;was&nbsp;found&nbsp;to&nbsp;be&nbsp;the&nbsp;degree&nbsp;of&nbsp;unsaturation&nbsp;of&nbsp;the&nbsp;oil&nbsp;used&nbsp;in&nbsp;the&nbsp;alkyd&nbsp;resin.&nbsp;It&nbsp;was&nbsp;observed&nbsp;that&nbsp;the&nbsp;combination&nbsp;of&nbsp;a&nbsp;highly&nbsp;unsaturated&nbsp;alkyd&nbsp;resin,&nbsp;a&nbsp;nitrocellulose-based&nbsp;auxiliary&nbsp;resin,&nbsp;and&nbsp;an&nbsp;aromatic&nbsp;cross-linker&nbsp;significantly&nbsp;increased&nbsp;the&nbsp;yellowing&nbsp;tendency.</p>

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