1. Deep processing
Flame retardants or substances with a flame retardant effect are infiltrated into the entire wood or to a certain depth by certain means. Impregnation and impregnation are generally used. The impregnation method is suitable for trees with good permeability, and requires the wood to maintain sufficient moisture content. Inorganic composite wood is the use of this method, so that the material with a flame-retardant effect infiltration into the wood, the impregnation method can generally reach a depth of a few millimeters. Immersion method is used to deal with poor permeability wood, commonly used vacuum injection method. Process: First put the wood into the processing tank, then vacuum, keep the pressure of 1.333 kPa for 20 minutes, inject the flame retardant liquid, and pressurize to l. 5 MPa and maintain l ~ 2 h, the injection depth of the infusion method varies depending on the permeability of the wood.

2. Surface treatment
That is, brushing or spraying fire-retardant materials on the surface of the wood. This treatment method should not be processed with flame retardant. Because of the thick material, brushing or spraying can only form a thin layer of flame-retardant layer on the surface of the wood, which can not achieve the desired flame-retardant effect. If the veneer is processed, the amount of the agent retained can be increased through lamination and can ensure a certain flame retardant effect. For example, fire-retardant treatment of plywood or veneer laminated materials is mostly done by first treating the veneers and then laminating them. In recent years, the use of adhesives has also been used to achieve the purpose of flame-retardant.

Commonly used wood surface treatment methods are flame retardant coatings. There are two types of fire retardant coatings: one is a seal paint. This is a polymer that is very flame resistant. It forms a protective seal on the surface of the wood. It cuts the wood directly into contact with the flame, but it does not prevent the temperature of the wood from rising. When the air in the voids of wood cells is heated and expanded, the paint film will be destroyed and the flame retardant effect will be lost. In addition, the paint film will age as time passes due to environmental factors and it is necessary to regularly maintain the paint film to be effective. The other is an expansive coating. The paint quickly burns before the wood catches fire, producing a non-combustible gas, and the gas quickly swells, forming a protective layer on the surface of the wood, making it difficult for the flammable gas formed by the thermal decomposition of the wood to be ignited by external sources of fire. Formation of flame combustion, flame retardant effect is good. However, this paint has a poor appearance and must be maintained frequently to maintain effective flame retardancy. Some of the expansive coatings are based on natural or artificially synthesized macromolecule polymers and are composed of flame-retardant components such as foaming agents, co-blowing agents, and carbon sources. Under the action of the flame, a uniform and dense honeycomb or sponge-like carbon foam layer can be formed. This foam layer not only has a good oxygen barrier effect, but also has a good thermal insulation effect. This foam layer is sparse, plastic, large, high-temperature burning is not easy to break. This flame-retardant coating has a high cost, but it has a small amount.

Fire retardant coatings are generally composed of base materials, dispersion media, flame retardants, auxiliaries, fillers, solvents, and the like. The base material is a main film-forming substance, which includes an inorganic binder (silicate, phosphate, etc.) and an organic binder (organic synthetic resin). Flame retardants are a key component of flame retardant coatings. At present, ammonium polyphosphate and organic halophosphate esters are commonly used in foreign countries, while ammonium phosphate and ammonium metaphosphate are still the main agents in China. Auxiliaries in the flame retardant coating as an auxiliary component, the amount of less, but the role can not be ignored, it can greatly improve the coating's flexibility, elasticity, adhesion, stability and other properties. The filler can improve the decorative properties of the coating, and more importantly, it improves the mechanical physical properties (weatherability, abrasion resistance) and chemical properties (acid and alkali resistance, corrosion resistance, etc.) of the coating. Rutile titanium dioxide is an excellent white filler widely used in coatings. The solvent facilitates the dispersion of the components, facilitates construction, and provides a uniform, continuous coating. Generally water and organic solvents.

3. Veneer processing
The veneer treatment is to attach a flame-retardant material to the surface of the wood. For example, non-combustible materials such as inorganic materials or metal sheets, or fire-retarded veneers, or the injection of two-layer molten metal liquids on the surface of the wood form so-called “metallized wood”. Inorganic material veneers are more commonly used for gypsum panels. A 15cmX15cm X 230cm wooden column, including a 1cm thick gypsum board under a 10 t load, the wood flame resistance time can be increased by 0.5h; including 2cm thick gypsum board can increase lh.