Synthesis And Characterization Of Cyclohexanone-isobutyraldehyde And Its Copolymerization Resin

Ketone-aldehyde resin is used as an additive to improve the hardness, gloss and adhesion ofthe coating/ink. Cyclohexanone-isobutyraldehyde （CI） resin and cyclohexanone-formalde-hyde-isobutyraldehyde （CFI） resin are two novel products, and there are rarely reports aboutthem. In this paper, CI and CFI resins were synthesized from cyclohexanone,isobutyraldehyde, formaldehyde, and sodium methylate was used as catalyst. The effect ofmolar ratio of materials, the amount of catalyst and reaction time on properties and yields ofthe resins was studied. FT-IR and¹H-NMR were used to characterize the structures of theresins. The main research contents and achievements are listed as follows:（1） The cyclohexanone-isobutyraldehyde （CI） resin with good yellowing-resistance andsolubility in common organic solvents was prepared from cyclohexanone andisobutyraldehyde, and sodium methylate was used as catalyst. FT-IR and¹H-NMR results ofCI resin show that there are hydroxyl groups and–CH（CH₃）₂groups in its structure, and thealdehyde groups disappear. It is suggested thatα-H of cyclohexanone has reacted withisobutyraldehyde via the synthesis reaction. When the molar ratio of isobutyraldehyde tocyclohexanone increased, the hydroxyl value of the resin increased, the kinematic viscosityand yield of the resin firstly increased and then decreased; When the amount of catalystincreased or the reaction time expanded, the hydroxyl value decreased, the kinematicviscosity and yield increased. The effect of evaporation time on the hydroxyl value andkinematic viscosity of the resin was similar to that of the catalyst. Considering the impact ofabove-mentioned factors on the hydroxyl value, kinematic viscosity and yield, the optimalreaction condition was chosen as follows: the molar ratio of isobutyraldehyde tocyclohexanone was 1.3, the amount of catalyst was 6.0 wt %, reaction time was 9 h andevaporation time was 1.5h. The obtained CI resin has the yield of 52.3%, the kinematicviscosity of 7.78 mm²/s, the hydroxyl value of 43.60 mg KOH /g and the number-averagemolecular weight of 469g/mol.（2） The cyclohexanone-formaldehyde-isobutyraldehyde （CFI） resin was synthesized fromcyclohexanone, formaldehyde and isobutyraldehyde, and sodium methylate was used as catalyst. FT-IR results show that there are hydroxyl groups and–CH（CH₃）₂groups in itsstructure, and the aldehyde groups disappear. It is suggested that aldol condensation ofisobutyraldehyde, formaldehyde andα-H of cyclohexanone has happened during its synthesisreaction. When the amount of catalyst increased or the reaction time expanded, the hydroxylvalue of the obtained resin decreased, its softening point and yield increased. When the molarratio of aldehyde to cyclohexanone increased, the hydroxyl value of the resin increased, thesoftening point and yield firstly increased and then decreased. The hydroxyl value andsoftening point of the resin decreased with increasing amount of isobutyraldehyde.Considering the impact of above-mentioned factors on the hydroxyl value, the softening pointand yield, the optimal reaction condition was chosen as follows: the molar ratio of aldehyde tocyclohexanone was 2.0, the molar ratio of isobutyraldehyde to formaldehyde was 1.0, theamount of catalyst was 5.0 wt % and reaction time was 5h. The obtained CFI resin has thesoftening point of 77℃, the hydroxyl value of 235.5 mg KOH /g and the yield of 78.4%. Also,the yellowing-resistance and solubility in nonpolar solvents of the obtained CFI resin is betterthan CF resin.