Preparation And Application Of Low Gloss Waterborne Polyurethane

Currently,the main method of waterborne matting coating is prepared by adding silica matting agents to waterborne polyurethane dispersions to achieve matting performance.However,adding matting agents brings defects such as coating brittleness increasing,flatting agent precipitation,decreased resistance to rubbing.By adjusting the formulations and ratio of polyurethane emulsion,waterborne polyurethane matting resin without matting agent can get excellent folding resistance,rubbing resistance and peel strength.This method received attention from paint industry.In this paper,with isophorone diisocyanate(IPDI)and Gather adipic acid-2-methyl-1,3 propylene glycol ester(IPDQ)as main materials,dihydroxy methyl propionic(DMPA)as hydrophilic chain extender,ethylene diamine or diethylenetriamine(DETA)or tetraethylenepentamine(TEPA)as small molecule chain extender,a series of low gloss waterborne polyurethane with different R and different dosage of hydrophilic group are prepared.The structure and properties of the waterborne polyurethane matting resin were characterized by using FTIR,SEM,TG,etc.Explored the effect of the change of R,hydrophilic group?the change of small molecule chain extender on the glossiness and surface micro structure.Then applied to different leathers and tested the adhesion resistance,folding resistance,rubbing resistance and peeling strength,etc.and compared the different effect of various coating thickness,baker temperature and baker time to the glossiness of the leather.The main research contents are as follows:(1)The optimal synthesis process of waterborne polyurethane matting resin discussed by researching the effect of the reaction time and temperature to waterborne polyurethane pre polymers: at 90?,react isophorone diisocyanate(IPDI)and Gather adipic acid-2-methyl-1,3 propylene glycol ester(IPDQ)together constant temperature for 2h,then cooled to 70?,join a mixture of the metering dihydroxy methyl propionic acid(DMPA),1,4-butanediol(BDO),triethylamine(TEA)and acetone,at 55? for 1h,reacting in organic bismuth catalyst,continue to constant temperature reaction after 2h to get pre polymers.After the temperature down to room temperature,add diethylenetriamine(DETA)as chain extender and deionized water to make emulsions.(2)The structure and surface of the waterborne polyurethane film were investigated by FTIR,SEM,and TG.With the single factor analysis method to study the effect of the change of R,hydrophilic group,and the change of small molecule chain extender to the waterborne polyurethane film's glossiness and surface micro structure.Finally,select the excellent waterborne polyurethane emulsion with high stability and waterborne polyurethane matting resin with good matting effect and excellent physical properties.(3)Apply waterborne polyurethane matting resin with good performance on different leather,to research the effect of various coating thickness,baker temperature and baker time to the glossiness of the leather.And compared the adhesion resistance,folding resistance,rubbing resistance and peeling strength,etc.At the final,determine the application effect of waterborne polyurethane matting resin by comparative study.