Study On Novel Epoxy Acrylate Coatings Containing Phthalazinone Moieties

Light curing coatings present a number of advantages,such as fast-drying,ambient temperature operations,solvent-free formulations and low energy consumption,as compared with the natural drying and thermosetting coatings.And they have been widely employed in various materials,such as,optical fiber,wood,plastic,metal,paper,glass,leather etc. Meanwhile,they are considered as environmentally friendly coatings because they match various countries' requirements on the environmental protection.However,there are some problems for light curing coatings in the application:the heat-resistance of the cured films is not excellent,and the cure extent of thick films is low,and the cure extent of the film containing fillers is not high.In order to resolve above mentioned problem,in this paper,the novel moiety is utilized to prepare the light curable resin,and to make the cured films with good thermal properties.Furthermore,visible light curing is applied for the curing of the thick films,and is helpful to solve the problem of UV curing the thick films.In this paper,4-hydroxyphenyl-2,3- phthalazin-1-one(DHPZ),which is a non-coplanar heterocyclic moiety,was employed to prepare ER with epichlorohydrin(ECH) by condensation reaction.Epoxy value of ER by one-step method and two-step method are 0.33 mol/100g,0.38 mol/100g.The flow activation energy is calculated with the viscosity of epoxy resins,which are measured by rotational viscometer under different temperature.The flow activation energy of these two kinds of ER are 52.3 kJ/mol,61.7 kJ/mol,respectively.In the meantime,the reaction conditions for the two methods are also optimized.Epoxy methacrylate resin(EMA) for UV curable coating was prepared by using ER containing phthalazinone and methacrylic acid with onium salts as catalyst.The products of the synthesize process were recorded by FTIR.The peak area at 914 cm^-1 gradually decreases along with the increasing of the esterification time.Meanwhile,the peak area at 815 cm^-1 gradually increases.It can identify that EMA has been synthesized.The flow activation energy of EMA-33 and EMA-38 are 36.2 kJ/mol and 50.3 kJ/mol,respectively.The viscosity of EMA-33 and EMA-38 are 52.1 Pa·s,40.25 Pa·s at room temperature.Both of their stable periods are above six monthes at room temperature.EMA obtained were utilized to UV radiation curing by taking photoinitiator in combination with various percentages of reactive diluents,and generated the interpenetraring polymer networks.The reactive diluents as follows:styrene(St),hexanediol diacrylate (HDDA) and trimethylol propane triacrylate(TMPTA).The formulations and curing conditions are optimized.The results as follows:the tack free time of the coatings is lower than 3 s by taking 3 wt%2-hydroxy-2-methyl-phenyl-propanone(HMPP) as photoinitiator and 20 wt%HDDA as reactive diluents,when the light distance is 12 cm.The properties of the cured film as follows:adhesion 1 grade,impact strength 50 cm,pencil hardness 5 H and gloss 147.5.As compared with the bis A epoxy acrylate resin,5%weight loss temperature of the cured film can increase by 25℃,and the corrosion fatigue lifes for 15%hydrochloric acid, 30%sodium hydroxide and 3%sodium chloride can increase by 2 times,4 times and 4times, respectively.The visible curing coatings were prepared using the 2,4,6-trimethyl benzoyldiphenyl phosphine oxide(TPO) as photoinitiator.The tack free time of the coatings were lower than 10 min by taking 2 wt%TPO as photoinitiator.The mechanical properties of the cured films as follow:adhesion,1 grade,impact strength,50 cm,and pencil hardness 5 H.But the gloss of the cured film is 128.3,and lower significantly than UV cured films.However,the thickness of thecured films could reach 200μm by visible light curing.The gel fraction of the cured film is the highest,when the thickness is 200μm.Meanwhile,the wafilms increase firstly and then decrease with increasing the thickness of the cured films.The ter absorption of the cured films decreases firstly and then increase with increasing the thickness of the cured films.The water absorption of the cured film is the highest,when the thickness is 150μm,the corrosion fatigue lifes for 15%hydrochloric acid,30%sodium hydroxide and 3% sodium chloride as follow:40 d,60 d and 55 d.Compare to the anticorrosion epoxy polyurethane coatings under room temperature curing,they can be inceased by 10 d,30 d,25 d.What's more,the sunlight curing coatings could match the requirements of coating and curing for large area outdoors because of soventfree under curing process.The effect of glass flake on the storage of coatings and the properties of the cured films were deeply investigated,baseing on the visible curing coaitngs.The results showed that BYK-P104S as a dispersant can markedly improve the dispersing properties of the glass flake. When GF is pretreated by using KH570,it can prolong the storage time of the coatings and decrease the water absorption of the cured films.Furthermore,the storage time obviously increaseswith adding fumed silica.The critical pigment volume concentration of the coatings is 15 wt%with deteminating the water absorption of the cure films.The anti-heating and anti-corrosion properties of EMA/GF coatings were tested.The results showed that the EMA/GF coatings could endure 15%hydrochloric acid,30%sodium hydroxide and 3% sodium chloride solution's corrosion for more than sixty days.