英语科技论文写作结课论文

英语科技论文写作结课论文

The Preparation and Research Of Epoxy Resin Modified Water-bone Polyurethane Emulsion

1. Introduction

There are various types of raw materials for synthetic water-bone polyurethane emulsion, including not only main raw materials such as isocyanates of polyurethane resin、polyhydric alcohols or polyamine , but also auxiliary raw materials like chain extender、catalytic agent、neutralizer. By different synthetic processes and compound designs we can produce water-bone polyurethanes with different properties[1]. The great advantage of water-bone polyurethane is using water as dispersion medium, the method we use to compose water-bone polyurethane is self-emulsification method, as it need not to add emulsification. As the epoxy resin has many excellent properties: great binding power and intensity, and it has hydroxide radical which can react with –NCO in polyurethane then reach the aim of modifying polyurethane[2]. This modification overcomes the polyurethane’s shortcoming to a large extent[3]. In our experiment , we discussed the temperature and time of pre-polymerization 、the temperature of emulsification、the R value、the addition of DMPA、the molecular weight of PEG、the addition of BDO and EDA, then make sure the best matching. Afterwards we use epoxy resin to modify PU, and discussed the addition of DMPA、the different kinds of epoxy resins and the addition to affect the properties of water-bone PU, then determine the best matching of the addition of DMPA and epoxy resin which enhanced the properties of PU the greatest degree[4].

2. Experiment

We first studied the reaction temperature, reaction time on the properties of water-bone polyurethane emulsion. Then in the best reaction temperature and time we discussed different ratio of raw materials affected the water-bone polyurethane emulsion’s appearance、storage stability and the waterproof、the mechanical property and the heat endurance of the coating. From this we obtained the best formula.

The preparation of epoxy resin modified water-bone polyurethane emulsion mainly divided into two stages[5]: The first stage is pre-polymer, and the main reaction is the –NCO in MDI react with –OH in PEG to produce Carbamic acid ester bond, when added DMPA then –COOH added, afterwards added BDO to increase the length of the chain, the last adding the –OH to bring in the epoxy groups; The second stage is neutralization emulsification. We cooled the pre-polymer to 30°, then add TEA to neutralize –COOH, followed under the action of high-speed shearing join EDA aqueous emulsion, among this the epoxy ring opening to –OH. At last the epoxy resin modified water-bone polyurethane emulsion made.

The picture in the following is the analysis of FTIR of the epoxy、the water-bone polyurethane emulsion and the epoxy modified water-bone polyurethane emulsion.