Reasons for Cracking of Melamine Paper in Melamine paper Panel
Melamine paper will crack in daily use, which is mainly caused by uneven dryness of various parts of wood. In the industry, according to the parts where cracks occur, they are generally called cracks, surface cracks, internal cracks and wheel cracks; The size and number of cracks will vary depending on dry conditions, tree species and the size of the wood section.
1、 End face crack.
An end crack occurs in a section of wood, perhaps extending to one or both sides of the end, which is often called a crack.
The main reason is that the water conductivity of wood along the grain direction is far greater than that in the cross grain direction. When the wood is dry, water transpiration from the end surface is much faster than that from the side surface. The moisture content of the end is lower than that of the middle part, and the shortening of the end is constrained by the wood in the middle part, so the tensile effect occurs at the end. When the tensile force is applied to the transverse tensile strength of the wood, the end face will crack.
2、 External cracks.
Surface cracks refer to the cracks on the surface of the raw wood itself, which are usually on the chord surface and develop in a direct direction.
Shallow surface cracks can be removed by planing, but deep surface cracks are not only ugly, but also reduce the strength of wood, especially the shear strength. The appearance cracks also affect the paint quality of wood. After the melamine board with surface cracks is painted, the cracks can open and close due to the change of climate conditions, causing the paint film to crack.
On the pressure side, if the pressure is too low, it will affect the bonding strength of the substrate and impregnated paper, but if the pressure is too high, it will affect the quality of the board, so this is a test of technology.
Then is the hot pressing time, which depends on the curing degree of the impregnating resin and the hot pressing temperature. If the time is too long, the curing degree of the resin will be too strong, the original elasticity will be lost, and the products processed later will appear cracking and deformation; However, if the curing time is too short, it will be insufficient, and the phenomenon of sticking will easily occur, which will directly affect the performance of the surface, and will also affect the performance of the product.
