Study On The Modification Of Melamine Formaldehyde Resin By Three (2-hydroxyethyl)isocyanurate For Impregnated Resin Paper

The high-speed development of the artificial board industry has made the surface decoration of artificial board as the main component of the surface decoration of modern woody material.Using the chipboard,fiberboard and other wood-based panels as the substrates,their surface was covered with impregnated resins papers,which was called surface decorated wood-based panels with paper impregnated thermosetting resins.Melamine(M)formaldehyde(F)impregnated paper has shown excellent properties,such as high abrasion,water and chemical resistance.However,its poor hardness and stability,together with brittleness,has caused some issues,including the short storage period and the high mounting pressure.Currently,the use of traditional modifier has been proposed as an efficient way to adjust the properties,but they may decrease certain excellent properties of MF film decorative panel such as abrasion resistance.In order to solve these problems,tris(2-hydroxyethyl)isocyanurate(trade name: THEIC,abbreviated to T)was employed to modify the properties of melamine formaldehyde resin(MFT resin)film..Without compromising the fast curing and sufficient mechanical properties,the high-temperature fluidity of the resin adhesive layer and storage period of MF resin were improved,respectively.As a result,impregnated MF resin paper coated veneer with better performance is produced.(1)The appearance of the MFT resin solution is mainly affected by the dissolution rate of M during the heating stage.The solid content of the reaction is controlled below 70% with ethanol.After the reaction occurred at 40 o C for 10 to 20 minutes,the reaction p H is adjusted to 10 to 10.5.A colorless and transparent MFT resin solution with a storage period of 55 days can be obtained,and the colloidal gel is also transparent.With the increase of THEIC addition(n(T)/n(F)=0~15%),the stability of the MFT resin solution continues to increase.(2)The addition of THEIC reduces the heat resistance,hardness and brittleness of MF resin.The degradation temperature of MFT resin is about 300°C.The degradation temperature of MF resin is reduced by about 1/4 as compared to MFT.,The residual carbon ratio of MFT is not significantly different compared with MF at 795°C.The impact strength of MFT1-2 resinspline reaches 2.62 k J/m2,which is more than 3 times higher than that of MF2 resin.In the rotational rheology analysis,no significant change of elasticity modulus is observed for the cured MFT resin.The rotational elastic modulus of MFT resins with n(F)/n(M)=2.02 is lower than that of MFT resin with n(F)/n(M)=1.85 by an order of magnitude.(3)It is proved that THEIC can participate in the MF resin reaction system analyzed by IR and NMR.NMR results indicate that the main reaction in the preparation of the impregnating solution is the hydroxymethylation of melamine,as well as the etherification between hydroxymethyl groups,and the etherification reaction between methylol and THEIC.The MFT resin system tends to be stable and the content of amino group slightly changes after 1.5hours of reaction.The addition of THEIC reduces the degree of polycondensation between the hydroxymethyl and amino groups in the MF system,thereby increasing the stability of the resin and the storage period.(4)Kinetic parameters of MFT from impregnating solution to glass state were obtained by rheology and DMA.The kinetic energy of the curing reaction of the MFT1-2 resin from the viscous flow to the gel state is 26.44 KJ/mol obtained by the rheological analysis.Two curing peaks of the MFT impregnated film with n(F)/n(M)=2.02 and 1.85 were observed at about100? and 85? respectively.The reaction barriers are mainly affected by the concentration of amino groups.The temperature dependency of elastic modulus G?of the MFT film paper with n(T)/n(F)=15% is more obvious than MFT film paper with n(T)/n(F)=10%.The toughness of impregnated MFT resin paper increases with the increase of THEIC.After the drying process,the reaction activation energy of the impregnated resin glue layer of the MFT1-1 impregnated film is 44.3 k J/mol before the resin gels.The reaction activation energy of MFT1-1impregnated paper is 62.0 k J/mol through the rubbery state to the glassy state.It is 64.69 k J/mol calculated by the non-equilibrium thermodynamic fluctuation equations of Hsich and the Arrhenius relational treatment.(5)Impregnated MFT resin paper has a higher tensile strength than MF paper.Moreover,no significant change of the surface hardness was observed..The hardness of the veneer wood-based panel increases significantly with the increase of the hot-pressing pressure.The shore hardness remains stable at around 81 HD after hot pressure is greater than 2.0 MPa.