Лако-красочные материалы — производство

Hanetho [427] has discussed the experiences of the particleboard industry regarding the influence of seasonal variations of the wood quality. Some problems do occur using wood that has been harvested in the winter time and which goes into board production immedi­ately. When these logs or chips have been stored for some time, these problems disappear. […]

A precondition for the gluing of two wood surfaces is the wetting of these surfaces by the liquid or liquified adhesive. Wetting here includes the value for the contact angle, the spreading of the liquid on the surface, and the partial penetration of the liquid into the porous adherend. Good wetting enables the creation of […]

The wood surface is a complex and heterogeneous mixture of polymeric substances such as cellulose, hemicellulose, and lignin. It is also influenced by factors such as polymer mor­phology, wood extractives, and processing parameters. During the processing of wood and the generation of new surfaces, damage to the wood material and to the surface can occur, […]

Extractives contained in wood can influence the gluing process in the physical as well as chemical sense. Several authors [391-393] have indicated that the chemical composition of a wood surface after processing might be different due to the concentration on it of polar and apolar substances coming from the wood itself. Even the fiber direction […]

The strength of a bond in a wood panel increases with the value of wood density for the range of approximately 0.7 to 0.8g/cm3. Above this density a decrease of the bond strength occurs. The performance and properties of wood-based panels are strongly influ­enced by the properties of the wood used. Thus, wood anisotropy as […]

In the wood-based panels industry a great variety of wood species are used as raw materi­als. The choice of the wood species used is often determined just by the availability and the price of the raw material. Furthermore, large amounts of wood residues from the primary wood processing industry (e. g., saw mill waste) as […]

The properties of wood-based panels are determined, in principle, by three parameters: wood, adhesive, and processing conditions. Only if all of these three parameters are correct and well balanced in the wood bonding process, can proper bonding results be achieved. The influence of the first parameter, wood, involves several factors. Bonded wood often is described […]

During gelling and hardening of the condensation resins in the hot press one can distin­guish between the chemical advancement of the condensation reaction during curing of the thermosetting resin (build up of the three-dimensional network) and the progressive devel­opment of the mechanical strength of the joint (increase in cohesive bond strength). The two quantities do […]

The molecular weight distribution (MWD) can be determined by means of GPC [or size exclusion chromatography, (SEC)]. This method divides the molecules according to their hydrodynamic volume, which is proportional to their molar mass. The most important consideration in the chromatography of formaldehyde condensation resins is the poor solubility of the resins in most solvents […]

Using different spectroscopic methods such as infrared (IR), 1H-NMR, 13C-NMR, or 15N-NMR, analysis of the adhesive structural compounds enables a deep insight into the structural composition of resins. These results are the basis for correlations of resin structural composition with their molar composition, their preparation procedure, and the properties of the panels produced and hence […]