Study On Preparation,Properties Of Low-odor Waterborne Polyurethane Adhesive

Polyurethane,as a kind of polymer material,is widely used in coatings,adhesives,elastomers and other fields.And,water-based polyurethane has become research hotspot in this field because of environmentally friendly characteristics,and it has developed rapidly over the years.Waterborne polyurethane adhesive uses water as a dispersion medium and has the advantages of non-toxicity,no pollution and low VOC.However,due to its poor solvent resistance,chemical resistance and water resistance,and strong ammonia smell,the application and development of waterborne polyurethane adhesive are limited.In order to improve the performance of waterborne polyurethane adhesives,this paper prepares a series of waterborne polyurethane adhesives by adjusting the formulation of waterborne polyurethane adhesives;removing the irritating ammonia of polyurethane by modifying β-cyclodextrin and changing the type of neutralizing agent;the WPU-PMMA composite emulsion is prepared by PMMA modification to improve the water resistance of the waterborne polyurethane adhesive.First,using carbonate diol(PCDL)and isophorone diisocyanate(IPDI)as the main materials,changing the ratio of soft and hard segments,epoxy resin content,hydrophilic chain extender content and neutralization degree to study the effects of different formulations on the properties of waterborne polyurethane adhesives and film.The properties of polyurethane emulsion and film were tested,and it was found that when the ratio of soft and hard segments was 1:1,Wt(E-44)=5%,Wt(DMPA)=5%,and the degree of neutralization was 100%,the waterborne polyurethane emulsion and film were the most excellent.Secondly,to remove the ammonia odor of waterborne polyurethanes,we have used two methods.First,the modification of β-cyclodextrin,including physical blending and chemical grafting,the β-cyclodextrin was introduced into the system,and the prepared aqueous polyurethane emulsion and film still have obvious irritating ammonia smell.The second method is changing the neutralizing agent of waterborne polyurethane.The ionic compound TMAH,TEAH and TBAH are used as neutralizing agents to prepare aqueous polyurethane emulsion,and the results show that the adhesive with TEAH as the neutralizing agent has good stability,excellent mechanical properties and bonding performance,and slight ammonia flavor that not easy to detect.In addition,due to the poor water resistance of the low ammonia-flavored aqueous polyurethane,different proportions of WPU-PMMA composite emulsion were prepared by core-shell emulsion polymerization.Studies have shown that due to the formation of the core-shell structure,the polyurethane and acrylate will exhibit a certain degree of "microphase separation" regardless of the presence or absence of chemical bonds,which leads to the great improvement of water resistance and solvent resistance of WPU composites.Therefore,the preparation of WPU-PMMA composite emulsion on the basis of water-borne polyurethane adhesive with low ammonia flavor can not only meet the requirements of low ammonia taste,but also greatly improve its water and solvent resistance.