UV-Curable Waterborne Epoxy Acylate Resin For Paper Coating

With the increasingly serious energy crisis and people's gradually enhanced consciousness on environment protection, coatings have been developed toward the direction of being environmental friendly, high efficiency and energy-saving. Among them, UV curable coatings have received keen interest due to the characteristic of high curing efficiency, low production cost, low content of volatile organic compounds (VOC), less occupation of space area and excellent product performance, and are called green coatings meeting the "5E" requirements. UV curable coatings have been widely used in the areas such as paper coating, ink, furniture coatings, leather coatings, architectural coatings and other fields.At the same time, higher requirements on UV curable coatings, including safety, environment protection and health, have been put forward. It is desirable to reduce the content of the irritated reactive diluents in the traditional UV curable coatings, but not to affect much the performance of the coatings. With this goal in mind, we carried out a preliminary study on waterborne UV curable coatings. The main contents are as follows:1. The UV-curable waterborne epoxy acrylate pre-polymers were prepared using epoxy resin E-44, acrylic acid and maleic anhydride. The effects of synthesis conditions, such as the kinds and concentrations of catalysts, the concentration of inhibitor, stirring speed, the reaction temperature, the acid value of intermediate product, the molar ratio of acrylic acid to epoxy resin, the kinds of neutralizer, etc., on the reaction speed and the water dispersity of pre-polymers produced have been discussed.2. The UV-curable alcohol/water type epoxy acrylate coatings were prepared by mixing waterborne epoxy acrylate prepolymer, reactive diluents, water-soluble resin solution, photoinitiator, non-reactive diluent (alcohol), additives, etc. The influence of the amount of materials on gloss, adhesion, abrasion resistance, solvent resistance, water resistance, after-tack property, etc., of the cured film was investigated and the optimum proportions of raw materials were obtained. 3. New polymeric non-ionic reactive emulsifiers were prepared by using epoxy resin (E-20, E-44, E-51), polyethylene glycol (PEG4000, PEG6000), trimethylolpropane triacrylate (TMPGE) and acrylic acid (AA). The effects of raw materials on the emulsifying capability of the emulsifiers were explored by testing the critical micelle concentration (CMC) of emulsifiers, the centrifugal stability, particle size, dilution stability, Calcium ion stability of the emulsions and the performance of the cured films. The optimum molar ratio of the raw materials epoxy resin E-44/polyethylene glycol (PEG4000)/trimethylolpropane triglycidyl ether (TMPGE)/acrylic acid (AA) was found.4. UV curable emulsion type epoxy acrylate coatings were prepared by a phase inversion process. Water is the solvent of the coatings, meeting the requirements of health, safety, environment protection, etc. Some properties of the cured film, such as gloss, water resistance, adhesion, hardness, etc., reached the level of a waterborne UV-curable coating available in the market, and the abrasion resistance of our product is even superior to it.