The influence of wood swelling on water-based wood coatings and how to improve it!

In recent years, the development of water-based wood coating, in the coating application of a variety of ills and problems, greatly affected the popularization of water-based wood coating, of which the problem of solid wood wood, a water-based wood coating in the promotion and application of unavoidable problems. Because the wood contains the relationship of moisture, in the coating of water-based wood coating, the water of the coating film will penetrate from the surface of the wood, thus destroying the original moisture balance of the wood, so that the wood surface of the catheter and some wood swell up, destroy the original flat wood surface, the phenomenon of rising ribs.
the common reasons for the rise of ribs different wood, due to the natural environment of growth, wood material density is different, wood moisture content is not the same, the serious situation of ribs is very different

. Table 1 is a common condition of several types of wood. From the relevant data, such as pine cork, the rise of ribs is more serious; The existing wood roughly divided into cork (pine, fir) and hardwood (except pine, fir and other soft wood all medium hardness and higher hard wood) two kinds, for different wood materials, can be used two different ideas.
Pine, fir and other softwood wood material is softer, wood is looser, cork is the wood moisture absorption, wood from the contact primer coating film to absorb moisture, so that the cell wall non-crystalline area of adjacent filaments, microfiber filaments and microcrystalline water layer thin (or disappear) and close or thicken and stretch, resulting in cell walls and even the entire wood size and volume changes, is the phenomenon of wood moisture. For cork wood, because the cork tends to cause wood to swell and deform, it is difficult to improve the repair through the follow-up process, so the first primer should be sprayed to avoid the occurrence of wood gluten. Can be used to improve the viscosity of primer, primer as little water or no water as possible, primer resin selection fast dry but poor penetration, resin particle size is larger, Tg higher resin. Minimize the effect of the first primer on the wood's ribs.
The texture of hardwood wood is more fine and hard than cork, the phenomenon of wet rise of wood is not obvious, spraying water-based wood coating generally encountered less gluten phenomenon, mainly to solve the problem of wood burr. For hard wood, it is recommended to spray a closed primer (recommended emulsion content of more than 80%) into the substrate quickly combined with wood fibers, so that the rough fibers or wood ribs poured after grinding rise like needles, through grinding removal, and then do the next process. Through the role of closed primer, so that solid wood hardwood wood surface wood thorn fibers rise and fix, by grinding to remove, so as to avoid the effects of the rise. As can be seen from the process of gluten, moisture plays a key role in it. The moisture in the coating film is absorbed by the wood surface in contact with the wood surface, thus destroying the moisture balance of the wood surface and forming a moisture concentration gradient from the wood inside to the surface. Close to the coating film side due to higher moisture content, wood catheter fibers wood ribs swelling, destroying the surface coating of the flatness. Therefore, from the principle, to avoid the formation of moisture gradient on the surface of wood, can reduce the rise of ribs. From the point of view of formulation, to minimize the penetration time of moisture, improve the drying speed of the coating film, while reducing the moisture content of the coating film, can effectively reduce the condition of the ribs.
Improvement method: (1) different wood ribs are different, cork wood spray the first primer should be as little water as possible to prevent ribs; (2) The formulation resin chooses the resin with the glassesification temperature and the lowest film-forming temperature. (3) the closure effect can be appropriately thick coating, the opening effect should be applied first glue solid primer and remove wood thorns.