The wood dyeing technology is called wood dyeing technology by combining with dyes physically or chemically to obtain a firm color. Ordinary or low-quality wood is processed through techniques such as dyeing and simulating wood grain, which can eliminate the color difference between wood core and sapwood, morning and evening wood, improve the visual characteristics of wood, and increase the added value of materials; wood dyeing technology is wood deep processing and fast-growing wood The important direction of utilization has attracted more and more attention from the furniture and interior decoration industries.
The dye molecules in the dye solution first enter the wood through permeable channels such as wood cell spaces, and then adsorb, settle, and fix on the surface of wood fibers to achieve the purpose of dyeing. The commonly used dyes for wood dyeing are: direct dyes, acid dyes, basic dyes and reactive dyes.
In recent years, with the improvement of people's awareness of environmental protection, the pollution caused by synthetic dyes in the production and application process has attracted more and more attention, and natural dyes have begun to be paid more attention to.
The pigment used in wood dyeing is a kind of color particles that are insoluble in water and organic solvents, such as carbon black, zinc white, etc., which can penetrate into the pipe part of the wood ring porous material. Pigment-colored wood can get an obvious coloring effect, and its light resistance is better than that of dyes. The disadvantage is that it has poor transparency.
When dyeing wood with dyes, it is necessary to add various auxiliaries to the dye liquor to help improve the permeability of the dye. They promote the dyeing effect individually or interactively during the dyeing process. The auxiliary agents used in the dyes include penetrants, leveling agents, fixing agents, mordants, light fasting agents, pH regulators, etc.
There are many wood dyeing methods, and the dyeing process used by different tree species is not the same, but from the construction principle, it can be roughly summarized into the following four methods: cooking method, dipping method, pressure injection method and coating method. The cooking method and the dipping method are relatively mature and the equipment investment is low, but these two processes are only suitable for the dyeing of surface or sheet materials; the pressure injection method is to achieve the penetration of the dye liquor by repeatedly heating and pressurizing the dye liquor. Function; The coating method is to use machinery or hand to color the wood surface. Let me introduce to you the common impregnation method and pressure injection in wood dyeing process.
1. Atmospheric impregnation is a common method for veneer dyeing. The veneer is dyed by immersion and dyeing with heated dye solution under normal pressure. First, the veneer is subjected to pre-treatment such as extraction and bleaching, and then the dye is prepared and heated. The wood is impregnated with dye, and finally the wood is rinsed and dried.
2. Pressure injection method is suitable for longer and thicker wood. Generally, deep dyeing is difficult to achieve uniform dyeing by the penetration of the dye itself. At this time, pressure injection method is often used, which is under heating conditions. Vacuum pressure, the specific pressure injection process is to first place the wood in a pressure vessel vertically, separate adjacent materials with a screen, seal the vessel and vacuum the vessel to 0.08-0.09 MPa and add dye to the vessel Liquid so that it completely soaks the wood. Finally, heat and pressurize the container to allow the dye solution to circulate for one to two hours, then release the pressure to cool down and take out the wood. The thickness of wood processed in this way can reach 32 mm.
1. The main factor affecting the dyeing effect of wood is the permeability of the wood itself. Wood is an inhomogeneous capillary material. The dye will settle on the surface of the fiber along with the aqueous solution through the wood capillary channel, making the wood dyed. The permeability of wood is closely related to wood dyeing. Generally speaking, the higher the permeability of wood, the better the dyeing effect.
2. Temperature also has many effects on the dyeing effect. Too low temperature will cause high viscosity and poor permeability of the dye solution. Too high temperature will cause hydrolysis reaction of wood, reduce the mechanical properties of wood, and destroy the characteristics of wood itself. Therefore, it is very important to control the dyeing temperature.
3. Dyeing time is not as long as possible, too long dyeing time will cause damage to the wood itself. Therefore, it is necessary to select the appropriate dyeing time according to the actual situation and the characteristics of the tree species being dyed.
4. The p H value is another important factor affecting wood staining. Specific dyes need to be dyed in a specific pH environment. For example, the pH value of acid dyes is generally between 4-5, while the pH value of reactive dyes is generally between 9-10.
Wood dyeing must not only make the wood dyed evenly and beautifully, light and weather resistant, but also not affect the subsequent finishing and gluing of the wood, so as to meet the modern needs of the multi-functionalization of dyed wood; it is necessary to vigorously strengthen the wood dyeing technology and other functionalization Integration and innovation between modification technologies, research and development of multifunctional dyed wood, comprehensively enhance the utilization value of plantation wood.