Study On Preparation And Properties Of Hydrophilic Polyurethane(Urea)-Acrylate Composite Emulsions

Waterborne polyurethane(urea)(WPU)possesses excellent mechanical properties and chemical resistance,and has no harm to the environment.Waterborne polyacrylate(PA)also uses water as a solvent,which is green and outstanding in weather resistance.Both are environmental friendly emulsions with multiple uses in the coating industry.However,WPU emulsions and PA emulsions still exist their own defects in their separate use.Many studies have shown that the combination of these two emulsions by chemical coupling is able to achieve the purpose of complementary advantages,and get composite emulsions with superior comprehensive performance.In this paper,a variety of novel hydrophilic polyurethane monomers were designed and prepared,including waterborne polyurethane(urea)(WPUU),allyl polyurethane(urea)siloxane(PUSi)and alkenyl polyurethane intermediates(PUEG).Then the composite emulsions and films were obtained through emulsion copolymerization by using acrylate monomers and above WPUU,PUSi or PUEG,respectively.The macro properties and microstructure of the film were analyzed through the characterization methods of mechanical properties,TEM,DMA,AFM and so on.The main research contents are as follows:1.Based on the molecular design,three types of waterborne polyurethane(urea): WPUU1,WPUU2 and WPUU3 with different molecular weights were synthesized by using self-developed low-active amino-terminated polyether(N-1000),dimethylolbutanoic acid(DMBA)and isophorone diisocyanate(IPDI)as raw materials by a new preparation process.The problem that the uncontrollable violent reaction between the conventional amino-terminated polyether and –NCO group was solved,and the reaction conditions of N-1000 and –NCO group were examined emphatically.The results showed that the suitable reaction temperature between –NCO group and N-1000 was 40℃ and the reaction time was 2h.2.Above WPUU1,WPUU2 and WPUU3 were copolymerized with acrylate monomers(AC)to synthesize waterborne polyurethane(urea)-acrylate composite emulsions(WPUUA).The effects of WPUU molecular weight and WPUU/AC mass ratio on the properties of emulsions and films were investigated.The results showed that compared with PA emulsion and film without WPUU,gel rates of all WPUUA composite emulsions were reduced to 0%.The tensile strength and heat resistance of WPUUA films were improved.DMA analysis indicated that the hardness and rigidity of WPUUA films were increased.AFM images showed that the surface roughness of WPUUA films was reduced and the molecular chains of polymer were arranged more neatly.3.A type of allyl polyurethane(urea)siloxane(PUSi)were synthesized using allyl polyglycol ether(APEG-600),isophorone diisocyanate(IPDI)and 3-aminopropyltriethoxysilane(KH-550)as raw materials,then PUSi was introduced into WPUUA emulsion to obtain the modified composite emulsions(PUSiA).The effect of PUSi content on the properties of composite emulsions and films were investigated.The results showed that compared with WPUUA film,the water absorption of PUSi A films was decreased and the thermal stability was improved.The tensile strength increased first and then decreased with the increase of PUSi addition.DMA analysis showed that the introduction of PUSi had a certain effect on the improvement of film rigidity.AFM images showed that PUSiA films have lower roughness and lower molecular chain arrangement.4.Four kinds of alkenyl polyurethane intermediates: PUEG1,PUEG2,PUEG3 and PUEG4 were prepared by reaction between alkenyl polyoxyethylene ethers with different molecular weight and isophorone diisocyanate(IPDI)at a mole ratio of 2:1,and then they were copolymerized with acrylate monomers(AC)to obtain a serious of composite emulsions(PUEGA).The effect of PUEG molecular weight and PUEG/AC mass ratio on the properties of composite emulsions and films were investigated.The results showed that compared with the PA film without PUEG,the tensile strength and elongation at break of PUEG1 A films and PUEG2 A films prepared by PUEG1 and PUEG2 with a smaller molecular weight were decreased.While the elongation at break of PUEG3 A films and PUEG4 A films prepared by PUEG3 and PUEG4 with a larger molecular weight was increased,but the tensile strength increased slightly only when PUEG3/AC=20/80 or PUEG4/AC=20/80.This illustrated that the comprehensive performance of the film would be improved only when the segment length of polyoxyethylene ether was suitable.DMA analysis indicated that the rigidity of PUEGA films was increased with the increase of PUEG molecular weight.AFM images showed that PUEGA films had a smooth surface and the larger the PUEG molecular weight,the more regular the polymer molecular chains arrangement were.