Preparation Of Copolyvinyl Acetate Emulsion And Modified Starch As Main Agent For API Adhesive

UF resin is widely applied in the interior products.However,there are the releases of formaldehyde from the products of urea-formaldehyde resin.Therefore,the using of the products is limited.The waterbring polymers isocyanate adhesive is a non-formaldehyde adhesive(API) and can completely solved the problem of formaldehyde release.In recent years,it has been attached great importance to people.But the API adhesive have defects,such as,the short active time,aging time,high cost,therefore,the purpose of this experiment is to develop a low-cost, environmentally friendly main agent of API adhesive.In the paper,first reseaching the PVAc emulsion polymerization,PVAc-NMA emulsion copolymerization.The synthesis and the performance of PVAc emulsion are studied,specifically including the emulsion stability,viscosity,wet strength of the plywood in the different contents of PVA,ammonium persulfate.In order to enhance the PVAc water-resistance,the experimental add N-methylol acrylamide(NMA)monomer to copolymerize with vinyl acetate monomer,the results of the emulsion stability,viscosity,wet strength of the plywood are studied with the different contents of NMA,respectively;results show:the water-resistance of the copolymers are improved by NMA,the other performances do not change largely.As well as,TG,FTIR,etc are used to perform the copolymers.The hot stability of copolymers is enhanced.In order to decrease the cost of the adhensise and do not influence it's used properties,the reproducte and cheap natureral polymer corn is modified as filler in the PVAc-NMA emulsion. First,the corn starch was oxidzed to dialdyhyde starch with periodate in acidic conditions. Second,the dialdehyde starch and the urea condensed to prepare cross-linked starch.The synthesis and performance of modified corn starch are studied.Second,the oxidized starch with H₂O₂ was also discussed.Then cross-linked oxidized starch was prepared with borax.The main agent API adhesive were prepared with the two modified corn starch blended in PVAc-NMA emulsion,and the performance of the main agent API adhesive were studied.The active time of API adhesive and wet strength of plywood were studied.Results show the performances of sodium periodate,urea modified corn starch is better the performance of H₂O₂, borax modified.With sodium periodate,urea modified corn starch to as the API adhesive filler,The results showed that the active time would be up to 3d,and the wet strength of plywood reached to 1.3MPa that corresponded to the National Standard demand of theâ…¡class plywood.The formaldehyde emission of the plywood was determined.The tests show that formaldehyde emission of the plywood was only 0.0144mg·L^-1,less than the national standard GB/T9846-2004, conforming the requirements of environmental protection.