Synthesis And HSP Characterization Of Aqueous Polymer Isocyanate Adhesives

The main work of the paper included:Three methods are studied to synthesize acetylied starch by the corn starch, the starch acetate are good water-resistance and used as filler in the PVAc emulsion or PVAc-NAM emulsion, thus reducing production costs.The corn starch was acetyled to synthesize starch acetate with acetic anhydride in acidic conditions. The ultrasonic and microwave methods are also used to get starch acetate. The synthesis and performance of starch acetate are studied.As filler, the starch acetate was blended with PVAc-NAM emulsion or PVAc emulsion as the main agent of API adhesive, and the performance of the blends were studied.The activity period of API adhesive were studied. The results showed that the contents of starch acetate in the API adhesive(weight content) was 30%, the active period of the API adhesive (the starch acetateas filler, DS=2.53) can be up to 78 minutes. And the activity periods of the other kinds of the API adhesive, which was filled with starch acetate (DS=1.67) or corn starch, are 58 and 40 minutes respectively.The factors to affect the strength of API adhesive were discussed, including:the types of emulsions of main agents, the fillers and PAPI, the content of PAPI, catalyst and starch acetate, the degree of substitute and granularity of starch acetate. Then get the conclusion below: choose the PVAc-NMA as emulsions and starch acetate(DS=2.53) as fillers to synthesize main agents, the PAPI synthesized by our lab as curing agent, and the contents of starch acetate, the catalyst and PAPI in the API adhesive(weight content) are 30%,1.2%-1.5% and 12% respectively.The experimental process such as hot-pressing time, hot-pressing temperature also affected the wet shear strength of plywood and results show the appropriate hot-pressing temperature was 120℃, hot-pressing time the appropriate was 3min for the three plate plywood.The tests show that formaldehyde emission of the plywood was only 0.014mg·L-1, less than the national standard GB18580-2001, conforming to the requirements of environmental protection.At the same time, three methods were used to characterize the starch acetate. The starch acetate is demonstrated in the IR spectra.The 1H NMR and 13CNMR spectrum of starch acetate is shown to ensure the structural formula and the degree of substitute in this paper. The DS is calculated to be 2.49. The solubility parameters of high degree of substitution starch acetate (DS=2.53) were examined by inverse gas chromatography (IGC) method. The API adhesive was investigated by the thermogravimetry (TG) method, the result demonstrated that the high degree of substitute starch acetate can availably improve the thermo-resistant. The HSPIP method was used to measure the interface between the wood and the API adhesives. Series of starch-based aqueous polymer isocyanate (API) adhesives were evaluated using Hansen solubility parameters (HSP).