Resrarch On Synthesis And Modification By Kaolin Of Waterborne Polyurethane

Waterborne polyurethane(WPU)is the emulsion which is in the process of the preparation of polyurethane(PU)dispersed in water.Compared with the conventional solvent-based polyurethane,WPU has the following advantages:environmental protection,easy transportation and storage,refractory,low production cost.So the PU research workers of WPU produced great interest.So the modern workers have great interest in researching on waterborne polyurethane.WPU is applied in leather coating agent,adhesive,coating and grouting materials.The preparation of high gloss of WPU coating is particularly important when used for leather coating agent.For the preparation of aqueous polyurethane adhesives,improving adhesive strength is the key of the research workers.While the mechanical properties and thermal stability of WPU is not good as solvent polyurethane,the improvement of WPU glossiness and bonding strength at the same time to improve its mechanical properties and water resistance is still one the major issues that need to be fully developed in this application field.The luster and the bonding strength was improved by changing the amount of different raw materials.The mechanical properties and thermal properties were improved by adding nanometer ion.Previous PU researchers have added nanometer WPU composites such as montmorillonite,titanium dioxide,carbon nano-tube to improve its mechanical properties and thermal stabilities.But the current research of WPU glossiness and bonding strength is little reported.The thesis of chapter two is mainly about the impact of TMP content,hydroxyl silicone oil content,the chain extender diphenyl dihydroxy silane content and the R value on the gloss of WPU.By FT1R and 'H NMR analysis of the structure of the WPU,the PU characteristic peaks appeared in IR and NMR,indicating a successful synthesis of WPU.At the same time the glossiness of coating was analyzed by using vancometer,and it is found that when the addition of TMP is 0.25 g,the glossiness is the best at 82%,when the addition of hydroxyl silicone oil is 3.0 g,the glossiness is the best at 82%,when the addition of spread chain agent dihydroxydiphenylsilane is 0.4,the glossiness is the best at 86%,and when R-value is 2.5,the glossiness is the best at 83%.The thesis of chapter three is mainly about the impact of TMP content,DMPA,KH-570,and R-value on Zeta potential and adhesive strength.Through analysis,the impact of the content of TMP,KH-570 and R value on Zeta potential is not obvious,and Zeta potential increases with increasing dosage of DMPA.When the addition of TMP is 0.3 g,the strongest adhesive strength is 6.71 MPa,when the addition of DMPA is 2.2 g,adhesive strength is 7.22 MPa,when the addition of KH-570 is 2.0 g,adhesive strength is 6.89 MPa;when R-value is 2.5,adhesive strength is 5.82 MPa.Adhesive strength is not only affected by Zeta potential and with associated factors such as molecular weight of PU,crystallinity,molecular polarity.And excessive of DMPA could make coating bibulous rate higher.Therefore,it should be taken into account in the actual production.At last,the kaolinite(Kaolin)was modified with DMSO.Through the analysis of XRD spectrum,it showed that the distance of kaolin layers increases from 0.74 nm to 1.25 nm.By the analysis of XPS and FTIR of kaolin,it showed that the surface of kaolin contains large amount of hydroxyl,which reacts with isocyanate.Modified kaolin is used to produce WPU through in-situ polymerization,and dispersed in water to prepare WPU/nano kaolin composite materials.The addition of kaolin has been changed into 0,2%,4%,6%,and 8%to analyze the influence of different additions of kaolin on mechanical properties and adhesive strength.FTIR spectrum shows the characteristic peak of-NH-CO-and CK-OH-,Shows that kaolin grafted successfully polyurethane molecule chain.Mechanical properties and TG analysis show that With the increase of the amount of kaolin,the water absorption first improved and then decreased,while the tensile strength,elongation at break and thermal properties are improved.When the addition of kaolin is 6%,kaolin can be well dispersed in PU emulsion with good mechanical stability,and the water absorbing rate was 10.4%,the tensile strength was 17.44 MPa,the elongation at break was 427%,the initial decomposition temperature increased by 57?,and the maximum weight loss rate of temperature increased by 55?.