Melamine formaldehyde resin has good heat resistance and high bonding strength

so it is widely used in wood processing adhesives

coating curing agents

paper wet strength agents. However

the rigid triazine ring structure of melamine causes the melamine formaldehyde resin to have defects such as hard and brittle

poor mechanical properties

low strength

and poor tensile and bending properties. The above drawbacks limit the use of melamine formaldehyde resins in certain fields. In order to expand its application range

the toughening problem of melamine formaldehyde resin has received more and more attention. This paper mainly reviews two main methods of toughening of small molecules and toughening of polymers. The toughening of small molecules includes toughening of isocyanurate

toughening of glycols

toughening of dialdehydes

toughening of amines

and varieties of small molecules synergistic toughening. Polymer toughening includes polyhydric alcohol toughening and polyurethane toughening. In addition

several other methods have been introduced

such as biomass toughening

silane toughening. At the same time

the toughening mechanism of the above method is also described.