Urea-formaldehyde resin glue is an initial urea-formaldehyde resin which is obtained by polycondensation reaction of urea and formaldehyde as raw materials and has certain viscous properties. When used, it is prepared by adding a hardener or other auxiliary materials. The prepared initial urea-formaldehyde resin is applied to the surface of the wood, and under certain conditions, the resin molecules continue to polycondense and finally form a firm adhesive layer to glue the wood.
Urea-formaldehyde resin binder has high bonding strength, good temperature resistance, water resistance and corrosion resistance. In addition, since the resin itself is transparent or milky white, the prepared particleboard and the medium density fiberboard are beautiful in color, and the produced plywood is not polluted, and the use on the wood product does not affect the appearance.
Urea-formaldehyde resin adhesives have many grades at home and abroad, but urea-formaldehyde resin products as glues mainly have the following three types:
1. Liquid: It can be divided into two types: thick liquid and foam glue.
Viscous liquid: It is a milky liquid resin whose resin content varies with the grade of the product. This resin glue has great instability, and resin storage is limited by a certain period of time, generally three to six months. If the storage time is too long, the resin itself will gradually thicken and gel and lose its effect due to further polycondensation.
Foam urea-formaldehyde glue: Before use, the foaming agent is added to the non-dehydrated urea-formaldehyde resin liquid, and the foam is mechanically stirred to increase the volume of the glue liquid, and the weight is reduced, thereby achieving the effect of saving the rubber compound amount and reducing the production cost.
2, powder: sprayed from liquid resin spray, this glue has a long storage time, easy to use (add appropriate moisture to prepare glue, or directly glue the wet wood with powder), easy to package and transport and so on.
3. Membrane: A kind of adhesive tape film which is coated on paper or immersed in paper and dried.
Among the above types, urea-formaldehyde gums which are viscous liquid are most commonly used. In addition, urea-formaldehyde resin can be divided into cold-set adhesive and thermal adhesive according to the temperature at the time of curing. Due to its good properties, it is currently widely used in the production of wood-based panels and in the bonding of various types of wood products. It is a kind of indoor use rubber.
Silicone Baking Mat,Cookie Baking Mat,Silicone Baking Pastry Mat,Grill Cooking Mat
Changshu Xinneng Silicone Products Co., Ltd. , https://www.xnmat.com