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Indexed by: Journal Article

Date of Publication: 2006-09-01

Journal: SURFACE COATINGS INTERNATIONAL PART B-COATINGS TRANSACTIONS

Included Journals: Scopus、EI、SCIE

Volume: 89

Issue: 3

Page Number: 209-214

ISSN: 1476-4865

Key Words: poly(phthalazinone ether nitrile ketone)s; hydrophilic modification; heat resistance; aqueous dispersion

Abstract: Poly(phthalazinone ether nitrile ketone)s (PPENK), modified with NaOH, were studied in order to find a hydrophilic resin which could be used in heat-resistant water-borne coatings. The properties of hydrolysates - HPPENKa (0.5 hours), HPPENKb (1.5 hours) and HPPENKc (3.5 hours) - were measured by differential scanning calorimetry (DSC), thermo-gravinnetric analysis (TGA), contact angle (water) and solubility. The structures of the hydrolysates were confirmed by FTIR (Fourier transform infrared spectroscopy) and H-1-NMR. The results indicated that the conversion ratio of the nitrile groups and the glass transition temperature (T-g) of the hydrolysates increased, whereas the weight loss ratio of HPPENK decreased as the hydrolysis time was prolonged, As expected, the hydrophilicity of HPPENK improved greatly (eg when the CN conversion ratio was 93.82%, and the water contact angles decreased from 75.3 degrees for PPENK to 54.4 degrees for HPPENK). By studying the effects of the different reactions of the co-solvents, the reaction temperature and the NaOH concentration on the hydrolysis, it could be concluded that the optimal synthetic technology was of a 6M NaOH solution with DMAc (N,N-dimethylacetamide) as co-solvent at 120 degrees C. Aqueous dispersions based on three modified resins were prepared and their storage stability was as follows: HPPENKc > HPPENKb >HPPENKa. In particular, the HPPENKc dispersion had no settling for more than 30 days and provided good film-forming. The cured film properties of HPPENKc were as follows: pencil rigidity (six hours), thermal impact resistance (300 degrees C, 24 hours), and adhesion (grade 1). Curing agents were applied to the dispersion, such as hexamethoxymethyl melamine (HMMM), epichlorohydrin (ECH), triethanolamine, and glycerol, etc. HMMM and ECH provided excellent curing properties. The co-operating emulsification of (Span) sorbate and (Tween) polyoxyethylene sorbate could improve the stability of the HPPENK dispersion.