Knowledge of urea formaldehyde adhesive for wood-based panel
Guide: The wood-based panel without urea formaldehyde adhesive is easy to crack. The discovery of urea formaldehyde adhesive makes the wood-based panel no longer affect its quality due to cracking.
Wood is very important in our daily life. The bed we sleep in, the floor of our home, and the desks and chairs we work with are made of wood. However, what we may not know is that the wood used for furniture can only be used after being glued with urea formaldehyde adhesive. Our country has a long history of urea formaldehyde adhesive. In the process of constant precipitation, many experiences summarized by predecessors can be directly used for various adhesive problems we encounter. How to deal with the dull wood? Because the moisture volatilization in the wood changes during the drying process, which is easy to cause changes in the size and volume of the wood and internal stress in the wood, the wood after drying out of the kiln generally needs to be kept in the dry feeding warehouse for a certain time. The wood-based panel without urea formaldehyde adhesive is easy to crack. The discovery of urea formaldehyde adhesive makes the quality of wood-based panel no longer affected by cracking. Therefore, it is necessary to store the wood for a certain time before using the UF glue panel. According to experience, it is recommended that the wood should be stored for at least one month (the specific time depends on the environmental humidity, environmental temperature, raw materials of wood-based panels and other reasons), which can play a role in reducing the internal stress of wood We wood-based panel manufacturers should all know the specific process. Of course, it is necessary to strictly control the final moisture content of the wood using UF glue panel. It is generally recommended that the moisture content should be between 8-15%. It is necessary to ensure that the error of wood moisture content in the whole kiln is controlled to a relatively small range, so that the assembled wood-based panels will not crack. Double sided wood veneer glue is mainly used for manual veneer, special-shaped veneer, scientific veneer and veneer repair. 1. When applying the glue on both sides of the veneer glue short hair roller, it is required to flatten, polish, dedust and other conventional processing on the data in advance. When applying wood veneer glue, the amount of glue applied on each side shall reach 80-100g/㎡ on the premise that the amount of glue is uniform; 2. When applying wood veneer glue, select the side that is not easy to absorb water to apply glue first. For example, when wood veneer is applied to solid wood based panels, apply glue to solid wood first, and then apply glue to wood veneer; If the wood-based panel is MDF, it is necessary to glue the veneer first, and then glue the wood-based panel; 3. After the veneer glue is applied, it is necessary to stand at 25 ℃ for 60-180 seconds (the specific standing time depends on the actual situation of the glue amount, ambient temperature, ambient humidity, raw materials of wood-based panels, etc.). When the back of the hand contacts the veneer, you can feel the viscosity but the glue does not stick to the hand. 4. If conditions permit, it is required to use an electric iron to heat it for 3-10 seconds (the temperature is 150-170 ℃ is preferred). If thick wood bark is used, the heating time should be appropriately increased. After the bonding is completed, it is necessary to check whether there are bubbles or whether the wood surface is firm. If not, you can use an electric iron to continue ironing, and use sandpaper to polish it until it is lubricated and flat. After the inspection is correct, the next process shall be carried out after more than 26 hours of exposure. Precautions for the use of urea formaldehyde glue: 1. The moisture content of wood spliced with urea formaldehyde glue should be controlled at 8-12%. The wood should be treated first to make the surface smooth, flat, and not warped, so that it can closely fit; 2. The main agent of two-component urea formaldehyde adhesive is generally milky white viscous liquid, the color of curing agent is light brown, and the proportion of main agent and curing agent is generally 100:15. Before use, the main agent and curing agent must be mixed according to the specified proportion, and fully mixed together for 3-5 minutes to make them evenly mixed; 3. In order to achieve a better assembly effect of urea formaldehyde adhesive, it is necessary to ensure that the glue is used up within 30-40 minutes after the completion of manufacturing. If the glue has severe foaming phenomenon, and you see that the glue is thickened, please do not use it and put it aside for storage; 4. For example, if the wood-based panels are cold pressed, the pressurization time shall be 1-3 hours according to the actual situation. In the future, the wood-based panels need to be stored for a period of time (more than 18 hours in summer and more than 24 hours in winter). After the products arrive at the storage time, the urea formaldehyde glue assembled products are normal and can enter the next processing procedure.
