Men'S No Blade Electric Trimmer,Men'S Beard Shaver,Callus Remover Machine For Feet,Foot Dead Skin Remover Electric Ningbo Chuangxiang Electrical Appliance Co.,Ltd , https://www.hshaircurler.com
Many woods are browned by light, and some even brown under indirect indoor light, especially white and bleached wood. Browning is more pronounced. One of the causes of browning is that the double bond of the side chain of the ligand bound to the phenolic substance in the wood absorbs ultraviolet light energy and undergoes polymerization inside the molecule.
The phenolic plywood is browned in the outdoor rain, because the alkaline agent (catalyst) used in the curing of the plywood dissolves in the rainwater and reacts with the wood component. In addition, browning of wood can also contaminate other items. For example, when the mortar in the plywood form is solidified, the water discharged is brown. If the brown water flows onto the light gray hollow brick wall below, it will cause brown stain on the surface.
2 Browning removal and prevention
Currently, the only way to remove light browning is to use an oxidative bleach for bleaching. After the wall is brown-contaminated, it can be effectively decomposed with sodium chlorinated bleach. Since the wall has numerous pores, it is necessary to remove the brown contaminants in the pores, and the decomposition method is better than the dissolution with the alkali solution. In addition, the wall is an alkali-curing substance, and the use of an acid bleach destroys the performance of the wall, so acid bleach cannot be used.
Ways to prevent browning:
(1) There are three methods for preventing photochromism: 1 changing the absorbance of carbonyl groups in wood so that it cannot absorb light energy. The specific method is to apply semicarbazide on the surface of the wood; 2 pre-coating a lead material agent which gradually decomposes browning, such as ethylene glycol, which also has the function of decomposing colored substances, and can effectively inhibit the white material and the bleaching material. Browning, but not suitable for colored materials such as Dalbergia; 3 pre-coated with ultraviolet absorbing agents. Since ultraviolet rays have the greatest influence on the color change, the ultraviolet absorber can be applied to the surface of the wood.
(2) Prevention of browning of phenolic resin plywood: To prevent plywood from being exposed to rain, or to use other types of water resistant adhesives.
(3) Method for preventing the discharge of brown sewage when the mortar is hardened: the veneer which is easy to change color with alkali is used as the surface plate of the concrete formwork plywood, or the finishing process is performed on the plate surface in advance.
The cause of wood brown pollution and its prevention and solution
1 Features and causes