Preparation and properties of UV-curable polyurethane-acrylate coatings of pre-coated metal (PCM): effect of polyol type/contents on adhesive property

Abstract

Since UV curing coatings form a coating film with low adhesive property, it is difficult to use it as a coating for pre-coated metal (PCM) of post-processing method which has been actively studied recently. In this study, to apply UV-curing type coatings to pre-coated metal (PCM), which is applied as a method to improve productivity and to shorten the coating process, urethane acrylate oligomers were synthesized by using the content of polycaprolactone diol and hydrogenated polybutadiene glycol as a soft segment. UV-curable polyurethane acrylate coatings were prepared by varying the kind and content of the reactive diluent (IBOA, TMPEOTA). The urethane-acrylate oligomer and the coatings were well-prepared and confirmed using FT-IR. The storage modulus at RT, tensile strength and modulus were the highest values and the elongation at break was low. Also, as TMPEOTA content increased, the T_g of hard segment and storage modulus at RT, tensile strength and modulus increased, but elongation at break decreased. The surface free energy of all coating films was lower than that of metal plate. And the adhesive property of coatings using HPBD polyol of 30 and 50 mole% was the best and pencil hardness was also high in these coatings. MEK rubbing was increased with the increase of HPBD polyol and TMPEOTA content.

Keywords:

• Adhesive property
• pre-coated metal (PCM
• UV-curable)

Additional information

Funding

This research was supported by the Ministry of Trade, Industry and Energy of the Republic of Korea (contract grant number:10070142).