Study On Water - Cured Waterborne Acrylic Graft Modified Epoxy Resin

Currently, Waterborne UV-curable epoxy acrylate using “esterified re-esterified”two-step synthetic procedure, introducing unsaturated groups(C=C) after first esterified,and then, introducing a hydrophilic carboxy(-COOH) after second esterified. Although the synthesis process of this method is simple, reliable, but the biggest drawback is that the film have poor hardness and showed a phenomenon of poor brittleness after the epoxy curing. This paper use of “first graft then esterified” process, first graft introduce a certain molecular weight polyacrylate, the molecular weight of the resin is increased while achieving water-based, re-esterified to introduce the UV-curable, then the introduction of double bonds, which can effectively reduce the loss of double bonds in the synthesis process, to improve the follow-up curing efficiency.(1) In the graft stage, the characteristic of the main chain of epoxy resin that the electronegativity of O appears repeatability in ether bond(-O-) and hydroxyl(-OH)greater than C, the electron cloud shifted, so enhanced the activities around the C-H bonds,it is easy to lose “Active H” under the hydrogen extraction initiator, forming the C free radical, resulting in double bond radical polymerization. Through the compensation type of the “hungry” BPO and the stepwise temperature-controlled reaction step, With a small molecular weight was synthesized named epoxy resin E-44 as the grafted substrates, the acid value of water-based epoxy acrylate graft copolymer(EAG) in 60 mgKOH/g.Products using Fourier transform infrared spectroscopy(FT-IR) and gel permeation chromatography(GPC) were characterized. The results showed that when the dosage of initiator accounted for 3.3% of overall quality of epoxy resin and mixed monomers, and the mass ratio of epoxy resin and acrylic monomer was 7:3(or 6:4), In the “hungry” type of BPO compensation and the condition of stepwise temperature control, it can be a good synthesis of a small molecule epoxy resin as the main body, epoxy acrylate grafting modification of low acid value system.(2) In the esterification stage, through the study of theinfluence of different catalytic activity of the catalyst, reaction temperature and dosage of the catalyst, polymerization inhibitor, ratio of raw materials on the degree of esterification. The results showed that thecraft used first add a polymerization inhibitor mixed with prepolymer, and then mixed with the initiator of the acrylic monomer was added the reaction, Take the form of distribution of the reaction temperature for about 3 hours to synthesize better prepolymer system. Determined the best ratio of raw materials: n(epoxy): n(carboxy) = 1:0.95, the polymerization inhibitor(ZJ-701) in an amount of about 0.1% to 0.2%, the dosage of catalyst(N,N-dimethylaniline) was 1%, which can obtain an aqueous photo-curable epoxy-acrylic graft copolymer systems of the rate of esterification was 98% with light color, Characterized by FT-IR found that the polymer occurred C=C double bond of the unsaturated absorption peak at 1650 cm-1.(3) By thermogravimetry analysis(TG), differential scanning calorimetry(DSC) and other methods to analysis the performance of UV curing coating. The results showed that the synthesis of novel water-based uv-curable epoxy acrylate on thermal stability,adhesion, alkali resistance and other mechanical properties are showed a excellent performance. At the same time, from the TG, DSC analysis data can be found in the introduction of the grafted acrylic monomer indeed had a certain influence on curing membrane performance.