Synthesis Of Water Soluble CMFR And Its Application In MF Impregnating Resin

The cyclohexanone-melamine-formaldehyde resin(CMFR)was synthesiz-ed by "one step method" and "two-step method",using cyclohexanone,melamine and formaldehyde as raw materials and sodium hydroxide as catalyst.The effects of material molar ratio,reaction time and the amount use of catalyst on the free formaldehyde content and water solubility of CMFR were investigated.What's more,the yellowing resistance,ultraviolet light resistance and solvent resistance were also tested in the paper.The resin was characterized by FT-IR,1H-NMR,13C-NMR,and the curing properties and heating resistance properties were mersured by DSC and TG The CMFR was added to the impregnated MF resin for the production of melamine impregnated paper and veneered wood panels,and then the properties of the surface gloss,abrasion resistance and hardness of the panels were tested.The main research contents and results of this paper are as follows::(1)The reaction conditions for the synthesis of CMFR by "one-step method" are the C/M/F=1.0:0.22:2.0,the reaction time is 120 min,the amount of catalyst is 1.7%,the reaction temperature is 90?.The synthesized CMFR free formaldehyde content is 0.31%,the water solubility is 7.3.The suitable reaction conditions for the "two-step method" are C/M/F=1.0:0.2:2.0,the reaction time is 120 min,the amount of the catalyst is 0.6%,and the reaction temperature is 90?,the free formaldehyde content of the prepared CMFR is 0.45%,the water solubility is 8.2.The CMFR synthesized by the two methods has certain yellowing resistance and ultraviolet light resistance,and good solvent resistance after curing.(2)FT-IR,'H-NMR and 13C-NMR analysis showed that there is a melamine structure in the molecule of CMFR linked by ether bond and methylene bond.The CMFR has two different synthesis mechanisms of Mannich reactions between cyclohexanone,melamine and formaldehyde and the dehydration condensation reaction between hydroxymethyl cyclohexanone and hydroxymethylol melamine under alkaline conditions.(3)TG and DSC results show that CMFR has higher thermal stability and curing reaction activity than CF resin.With the same raw material ratio,the"two-step method" in the synthesis of the CMFR,is better than the“one-step method" in the thermal stability,in the temperature range of 220?350?,but the final residual carbon ratio,curing temperature and thermal enthalpy value are not much different.(4)Applying the CMFR to the MF impregnating resin,which can enhance the flexibility of the impregnated paper,and the surface properties such as surface gloss,abrasion resistance and hardness of the impregnated paper-finished wood-based panels are also improved under certain hot pressing process conditions.