| Acrylates emulsion has acquired an important application in water coatings. But common acrylates emulsion exists some disadvantages such as high temperature of film forming,lower rigidity,tending to get soft,poor water resistance of cured film ,ect. So it becomes a research focus that synthesis of novel acrylates emulsion with more excellent performance.In this paper , a new acrylates emulsion with hard core of P(St-co-MMA)and soft shell of P(BA-co-AA) structure was prepared by the idea of designing partical structure.Futher more ,the emulsion was modified by forming Latex Interpenetrating Polymer Networks(LIPN),grafting copolymerization and physical mixing.Tests showed that the performance of modified emulsion got a prominent improvement in water resistance, rigidity,debasing temperature of film forming,ect.The acrylates emulsion modified has fine applicationin in various fields,from architecture paints to industry paints,to casing paints.The influence of different monomer,ratio of soft/hard monomer ,the proportion and the amount of emulsifier and the concentration of modifying agents was studied in great details.At last the recipe was optimized through orthogoral experiments. ①Respectively acryaltes emulsion was synthesized via intermission emulsion polymerization ,seeded successive emulsion polymerization and pre-emulsification seeded half-successive emulsion polymerization.The influence of polymerization crafts on particle structure ,dimension and stability was investigated in details.By the means of FTIR,DSC,TEM et al,found that the emulsion particles via pre-emulsification seeded half-successive emulsion polymerization have distinct core-shell morphology ,whose vitrification temperature are -54℃ and 105℃,which results in lower temperature of film forming,no tending to get soft and better rigidity.②Tests indicate adhesion,rigidity and water resistance of emulsion are better,when the proportion of soft/hard monomer was changed from 1/1 to 1/1.25.③Composite emulsifiers of SDBS and OP-10 have the result of dual stabilization., the performances of emulsion are better when ratio of anionic/non-ionic emulsifiers are 1/2 and percentage are 4%.④With the increase of initiator(KPS),the conversion of monomer , viscosity and ratio of agglomeration improve.when percentage of KPS exceeds 0.3%, velocity of the conversion improvement gets slower.The more high temperature ,the more velocity of reaction.At last , ascertain percentage of KPS is 0.5%,temperature is 80 ℃.⑤The emulsion was modified by the ways of forming LIPN,grafting copolymerization and physical mixing. The influence of quantity of different modifying agents was investigated .⑥With the NMA,the crossing agent (DVB) could improve water resistance of film.When percentage of NMA is 2%, percentage of AA is 4%, percentage of DVB is 0.4%,ratio of absorbing water is downwards from 13.4% to 7%.If percentage of DVB exceeds 0.3%, crossing density become too much ,which make that viscosity of system increase, levelling property and performance of forming film get poor.⑦Added 6% of AN, ratio of absorbing water is downwards from 13.4% to 7%.If added too much, performance of forming film get poor,water resistance of film declines. Added 0.4% of Phenol, ratio of absorbing water is downwards from 17.3% to 10.8%. Added 0.8% of Melamine, ratio of absorbing water is downwards from 13.4% to 12.9%.⑧The recipe was optimized through orthogoral experiments.Orthogoral experiments indicate that emulsion has more prominent integrate performance when added emulsifier(0.3%),NMA(2%),DVB(0.4%),soft/hard monomer(1/1.25).Through tests,found that the emulsion have better water resistance, adhesion, lower temperature of forming film,no tending to get soft and good rigidity. |
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