Study On Synthesis And Properties Of Polyacrylate Emulsion For Decorative Paper

With methyl methacrylate?MMA?and butyl acrylate?BA?as monomers and 2,4-diphenyl-4-methyl-1-pentene??MSD?or n-dodecyl mercaptan?NDDM?as molecular weight regulator,acrylate latex was prepared via emulsion polymerization.It was investigated that the feasibility of substituting?MSD with environmental friendly,odorless and low toxicity for the traditional molecular weight regulator NDDM with obvious odor and high toxicity.And the regulation mechanism of MSD in emulsion polymerization was studied.Furthermore,the post-crosslinking acrylate latex used as the impregnation liquid of the decorative paper was obtained by using?MSD as molecular weight regulator and hydroxyethyl acrylate?HEA?or hydroxyethyl methacrylate?HEMA?as cross-linking agent.The appropriate impregnation process was studied.Finally,silica-sol-modified co-polyacrylate latex was synthesized by using silica sol as modifier,MMA and BA as monomers and diallyl phthalate?DAP?as crosslinking monomer.The pure acrylate emulsion was mechanically blended with silica sol,nano-SiO₂ powder and micro-SiO₂powder to prepare various composite emulsions.And then all the composite emulsions were applied as the surface glue to the impregnated paper.The latter was hot-pressed to attach the wood-based panel to prepare the impregnated paper veneer.The surface glue formula and the hot pressing condition of the decorative panel with the best performance of wear resistance and other properties were determined at last.The results were as follows:?1?With the same amount almost,both?MSD and NDDM could significantly reduce the molecular weight and the molecular weight distribution constant?to 1.5?of the polymer,namely had the same regulatory effect on the molecular weight.The chain transfer constant C_tr of?MSD was obtained to be 0.36.Meanwhile,the stability of emulsion polymerization decreased with the increase of NDDM's dosage,however it was not significantly affected by the change of?MSD's dosage.In addition,The regulating effect of?MSD was carried out by irreversible addition-fragment chain transfer reaction,which would reduce the rate of emulsion polymerization?R_p?.The polymerization system showed the retardant properties with the decrease of the monomer conversion and solid content of emulsion obviously since the dosage of?MSD exceeded 1%?according to the amount of acrylate monomer,the same below?.?MSD could be used as molecular weight regulator of acrylate emulsion instead of NDDM,but its dosage should not exceed 1%.?2?With HEA or HEMA as the cross-linking agent,the R_p and the viscosity of acrylate post-cross-linked emulsion with HEA?"E emulsion"?were higher than the other one?"M emulsion"?.When the amount of both crosslinking agents reached 10%,the crosslinking degree of the film obtained by E emulsion was 5%higher than that of M emulsion,and the crosslinking degree of both reached the maximum value?about 80%?.However,effective cross-linking couldn't occur except the dosage of the crosslinking agents both exceed 1%.The mechanical properties analysis showed that the tensile strength,elastic modulus and elongation at break of the emulsion film obtained by E emulsion are all greater than those obtained by M emulsion film.And the mechanical properties of both crosslinked films were greater than the corresponding uncrosslinked films.E emulsion with 10%HEA dosage was the most suitable as the impregnating liquid of decorative paper because of its excellent performance in its crosslinking degree,mechanics property and other properties.And the optimum process conditions were impregnation with three times,dipping for 5 min,3 min,5 min,respectively,and the drying for30 s,30 s and 120 s at 120?.The resin content of the impregnated paper could reach 102.6%,and the curing degree could rise to 11.82%when the volatile content could be 9.42%.?3?For the silicon-sol-acrylate copolymer emulsion,FTIR analysis showed that KH570 was successfully grafted onto the surface of nano-SiO₂,and the modified silica sol could copolymerize with acrylate monomers.The best comprehensive performance of mechanics properties was that of the copolymer films containing 8%SiO₂.The optimum hot-pressing process conditions of the surface decorated wood-based panels with impregnated paper were determined by controlling hot-pressing temperature at 160?,under pressure 1.5 MPa for 10min,respectively.Finally,the wear resistance and oil resistance of the decorative panel obtained by the silicon-sol copolymer composite emulsion containing 8%SiO₂ performed best,but its oil resistance needed to be further improved.