Study On Synthesis And Properties Of The Keto-aldehyde Resin Modified The Anionic/Non-ionic Type Polyurethane Dispersion

With advantages in environmental protection, nontoxic, convenient to store andtransportation, excellence performance, PUD is widely studied and applied in coatings,adhesives, printing inks and other industrial fields. In recent years, PUD and modified PUDhave become research hotspots for aqueous polymer.PUD used for hard substrate coating needs good hardness, adhesion, water resistance,alcohol resistance, etc. A single PUD, however, is often difficult to achieve the ideal price andapplication performance. Therefore, it is needed to modify PUD with the use of blending,copolymerization and composite. In addition, PUD used for coatings also needs good stabilityof electrolyte resistance. However the current research on the synthesis and application ofmodified PUD in the use of a single anionic hydrophilic monomer DMPA provideshydrophilic groups. With bad stability of electrolyte resistance, it can easily flocculate andaffect the normal usage in coating.In response to these problems, this paper uses the synthesis process of pre-polymermethod, mixed using the new nonionic polyethylene glycol methyl ether and DMBA withhigher reaction activity. Using polyketone resin and polyaldehyde resin which have low price,well water resistance and hardness as modified resin, polyneopentanediol adipate (PNA) andisophorone diisocyanate (IPDI) as the main raw materials, synthesizing polyketone resin orpolyaldehyde resin modified anionic/non-ionic polyurethane dispersions and preparing forwaterborne coatings.This paper studies the influences of the total hydrophilic group content (HGC),anionic/non-ionic hydrophilic monomer molar ratio, polyketone resin addition, NCO/OHmolar ratio (R value) to polyketone resin modified PUD emulsion properties and filmproperties. The experimental results show that with the decrease of the contents of hydrophilicgroups, anionic/non-ionic molar ratio, the amount of polyketone resin, R value are increased,the average particle diameter of dispersion is increased, the viscosity of the emulsion isreduced. Polyketone resin modified PUD particle size is in bimodal distribution. Theanionic/non-ionic type PUD has better stability of electrolyte resistance. The use ofpolyketone resin modified polyurethane dispersions can significantly improve theperformance of coating. When the content of the hydrophilic groups is of25mmol/100g,anionic/non-ionic hydrophilic monomer ratio is of8:2, the content of polyketone resin is of40%, R value is1.3, the pencil hardness of the coating film reaches4H, adhesion up to level1,the impact resistance is greater than50cm, flexibility is of1mm and the water resistance of coating film120h has no abnormal change.This paper studies the the influence of polyaldehyde resin addition and the content ofresidual-NCO groups of prepolymer on the performances of polyaldehyde resin modifiedPUDs. Experimental results show that with the increasing of polyaldehyde resin and thecontent of residual-NCO, the dispersion emulsion particle size increases, the viscositydecreases and particle size is in evident bimodal distribution. When the polyaldehyde resincontent is50%of the total resin content, residual-NCO group content is about1.4%, PUDshas the best comprehensive performance. Polyaldehyde modified polyurethane dispersionshave better yellow degeneration resistance.